Diss. ETH No 12978
Heterogeneous
Transition Metal
Catalyzed
Amination of Aliphatic Diols
A dissertation submitted to the
Swiss Federal Institute of
for the
degree of Doctor
Technology Zurich
of Technical Sciences
presented by
Achim Fischer
Diplomchemiker,
Universität Karlsruhe (TH)
born
August 7,1968
German citizen
accepted
on
the recommendation of
Prof. Dr. A. Baiker, examiner
Prof. Dr. A. Wokaun, co-examiner
1998
Leer
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Danksagung
Das
Anfertigen
einer Doktorarbeit ist ohne Rat und Tat
Freunden nicht durchzuführen. Ich möchte
für meine Arbeit unverzichtbar
Chancen
eröffnet.
Die
dieser Stelle,
Mitarbeitern und
diejenigen nennen, die
waren.
Mein ganz besonderen Dank
durch die Aufnahme in seine
an
von
gilt Herrn Prof. Dr. Alfons Baiker. Er hat mir
Arbeitsgruppe eine grosse Freude gemacht und neue
Themenstellung
der
Arbeit
ermöglichte
mir
eine
abwechslungsreiche und breite Ausbildung im Bereich der heterogenen Katalyse.
Seine stete Hilfsbereitschaft und sein Vertrauen, das
war
für mich immer wieder
er
mir entgegen
ermutigend und Ansporn.
angenehmere Arbeitsatmosphäre vorstellen
gebracht hat,
Ich hätte mir keine
können.
Herrn Prof. Dr. Alexander Wokaun danke ich für sein Interesse
Arbeit und seine
Herrn
Bereitschaft, das Korreferat
Dr.
Tamas
Mallat
danke
zu
an
dieser
übernehmen.
ich
für
die
freundschaftliche
Zusammenarbeit während meiner Zeit in Zürich. Sein immerwährendes Interesse
am
Fortgang der Arbeit,
massgeblich
zum
seine vielfache
Gelingen
der
Anregung und konstruktive Kritik haben
vorliegenden Arbeit beigetragen.
Den Mitarbeitern der Werkstatt, allen
Max
voran
Herrn Urs Krebs und Herrn
Wohlwend, gilt meinen Dank für die Mithilfe bei der Realisierung der
kontinuierlichen Hochdruckanlage und für
so
manchen
Verbesserungsvorschlag.
Ebenso leistete Herr Dr. R. Huwiler (EMPA Dübendorf) entscheidende Beiträge
zur
Konstruktion des Reaktors.
Herrn Fortunat Luck, dem Leiter der Hochdrucklaborwerkstatt, bin ich
iv
dankbar für seine
pragmatischen Vorschläge
und Hilfen
zu
der
Handhabung
von
Hochdruckapparaturen.
HerrH. Bruder (Hoffmann-LaRoche AG,
den
Phasenzustand
der
Kaiseraugst) half mir spontan, um
Reaktionsmischung bei Reaktionsbedingungen
zu
bestimmen.
Herr Franz
Analytik
Mayer
auftraten. Er
hatte immer ein offenes Ohr für
war
mir durch seine reiche
Für die freundschaftliche und fachlich
danke ich Dr. Steffen Auer,
Probleme, die bei der
Erfahrung
eine grosse Hilfe.
ausgezeichnete
Karoly Borszéky,
Zusammenarbeit
Dr. Thomas
Bürgi,
Patrizia
Fabrizioli, Davide Ferri, Dr. Jan-Dierk Grunwaldt, Dr. René Koppel, Beatrice
Lüthi, Dr. Eamonn Murphy, Dr. Marek Maciejewski und Clemens Wögerbauer.
Ein herzliches Dankeschön
mir
entgegengebrachte
Arbeiten im Labor
alle weiteren
Mitglieder des Arbeitskreises für ihre
Kameradschaft und
angenehm werden
Der Lonza AG,
Projektes.
an
Visp
Hilfsbereitschaft, die das tägliche
Hess.
danke ich für die finanzielle
Unterstützung
des
Table of Contents
Summary
ix
Zusammenfassung
xiii
1 General Introduction: Amination of
Aliphatic
Diols and
Polyols
1.1 Introduction
1.2
Catalysts,
1.2.1
1
Reaction Routes and Conditions
Amination
over
Metal
1.2.2 Amination
over
Solid Acid
Catalysts
3
Catalysts
10
over
Zeolites
10
1.2.2.2 Reaction Route
over
Phosphates
15
Synthesis
Polyfunctional Alcohols
of Ethylenediamine from
Ethylene Glycol
Ethanolamine
1.3.2 Amination of Ethylene
1.3.5
Amination of
Glycol
Aliphatic
Polyoxyalkylene
2
Diols
24
26
Diols and Triols
30
Synthesis of Polyalkylene Polyamines
34
Sugars
1.4 Conclusions
Scope
with Amines
with Ammonia
1.3.6 Amination of
1.5
17
and
17
1.3.3 Amination of Higher
1.3.4
3
1.2.2.1 Reaction Route
1.3 Amination of Bi- and
1.3.1
1
of the Thesis
37
39
40
1.6 References
42
Experimental
47
2.1
Apparatus
47
2.2
GC-Analysis
50
2.2.1
50
General
2.2.2 Quantitative Determination
51
VI
3
Cobalt-Catalyzed Amination
Promotion and Use of
of
1,3-Propanediol:
Supercritical Ammonia
as
Effect of
Catalyst
Reactant
and Solvent
55
3.1 Introduction
55
3.2
Experimental
57
3.2.1
Materials
57
3.2.2
Catalyst Characterization
3.2.3
Catalytic
58
Amination
60
3.3 Results
3.3.1
61
Catalyst Characterization
3.3.1.1 Textural
Calcined
Properties
61
and Surface
Catalysts
61
3.3.1.2 Characteristics of the Reduced
3.3.1.3
3.3.2
Adsorption
Catalytic
Composition of the
Catalysts
of Ammonia
Amination
3.3.2.1 Choice of
66
68
Catalyst
68
3.3.2.2 Product Distribution
70
3.3.2.3 Influence of Reaction Parameters
72
3.3.2.4 Amination of
76
3.3.2.5
Catalytic
3-Amino-l-propanol
Performance of Co-Fe Treated with
NaOAc and
(NH4)2HP04
3.4 Discussion
3.4.1
4
63
77
78
Influence of
Supercritical
Ammonia
78
3.4.2 Promotion of Co with La and Fe
79
3.4.3 Role of Surface Basic and Acidic Sites
80
3.5 Conclusion
81
3.6 References
83
Nickel-Catalyzed
Amination of
1,3-Propanediols:
Influence of Reactant Structure
85
4.1 Introduction
85
4.2
86
Experimental
vu
88
4.3 Results
4.3.1
Catalyst Properties
4.3.2 Amination of
1,3-Propanediols
89
4.4 Discussion
95
4.5 Conclusion
98
4.6 References
99
5 Influence of Pressure
on
the Amination of Propanediols
5.1 Introduction
5.2
6
88
Experimental
101
101
103
5.3 Results and Discussion
104
5.4 Conclusion
109
5.5 References
111
Synthesis
of
1,4-DiaminocycIohexane
6.1 Introduction
6.2
Experimental
113
113
115
6.3 Results and Discussion
116
6.4 Conclusion
119
6.5 References
120
Outlook
121
Appendix
123
Construction of the Reactor
125
List of Publications
129
Curriculum Vitae
131
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Summary
The
heterogeneously catalyzed
amination of
primary, secondary or tertiary amines is
a
aliphatic alcohols by ammonia,
well known and
important
process for
the synthesis of amines. In comparison to numerous reports on amination of simple
aliphatic alcohols, studies on the amination of diols to the corresponding diamines
are rare.
This is
diamines find
a
clearly
not due to a
missing interest
broad range of commercial
fungicides, fibres, polyamide resins,
epoxy
in these
products,
because
application (e.g. chelating agents,
curing agents). The likely
the limited scientific interest is that the amination of
reason
for
simple aliphatic alcohols
is
already a very complex process with several side reactions: (I) disproportion of the
amine to form secondary and tertiary amines,
(ii) condensation or decarbonylation
of the carbonyl compound intermediate, (iii) formation of nitriles
at
high
temperature and low hydrogen partial pressure and (iv) hydrocracking and
hydrogenolysis. The difficulties in obtaining reasonable selectivities are increased,
when
using
a
diol.
diol. Most of the
Interestingly,
primary
dichlorides. However,
a
no
established industrial process starts from the
diamines
disadvantage
are
manufactured from a,œ-
alkylene
of this method is the corrosion caused
by
hydrogen chloride. The neutralization of the acid creates large amounts of aqueous
sodium chloride and
growing disposal problems. Considering
the
availability of
reactants, the corrosion and environmental problems, the heterogeneous transition
metal
catalyzed amination
established processes. The
work.
Catalytic aminations
of diols could be
study of diol
were
all
an
attractive alternative to
amination
was
performed using
a
some
the aim of the present
continuous fixed bed
Summary
X
operating
reactor
in the pressure range up to 150 bar and temperatures up to
235 °C.
The
catalytic synthesis
ammonia
was
Co-based
catalysts applied
of
1,3-diaminopropane
from
1,3-propanediol
studied in the pressure range from 50 to 150 bar. The
were
characterized
and
unsupported
by N2-physisorption, XRD, XPS,
TPR, and ammonia adsorption using pulse thermal analysis and DRIFTspectroscopy. The latter investigations revealed that the best catalyst, 95 wt% Co-5
wt%
Fe, contained only very weak acidic sites, unable to chemisorb ammonia. The
absence of strong acidic and basic sites
base
catalyzed
side reactions
disproportionation,
requirement
for
crucial
to
oligomerization).
improved diaminopropane formation
transformation of this
suppress the various acid-
(retro-aldol reaction, hydrogenolysis, alkylation,
dimerization and
ß-Co phase.
metastable
was
An
other
important
was
the presence of the
A small amount of Fe additive could
efficiently hinder the
phase to the thermodynamically stable a-Co phase, and thus
prevent catalyst deactivation up
to ten
days on stream. The use of excess ammonia
(molar ratio NH3/diol >20) was necessary to minimize the formation of oligomers.
The
application
of
significant improvement
supercritical
in
as
solvent and reactant afforded
primary
diamines in the Co- and Ni-
ammonia
selectivity
to
catalyzed synthesis of 1,3-diaminopropane and 2,2'-dimethyl-1,3-diaminopropane.
Selectivity enhancements by
a
factor of 4
to 18 were
observed in the
near
critical
region of ammonia. The selectivity improvement is attributed to the higher surface
concentration of ammonia which favoured the amination and
degradation
limited
to a
reactions. It
seems
specific catalyst
or
that the effect of
supercritical
suppressed
the
ammonia is not
reactant.
The heterogeneously catalyzed amination of 2,2'-dimethyl-1,3-propanediol,
2-methyl-1,3-propanediol and 1,3-propanediol over a commercial silica supported
Ni
catalyst
Summary
has been studied
using supercritical
ammonia at 135 bar in the
xi
temperature range 180
afforded
as
main
alcohol (7 %)
The
products
resulting
application
235 °C. The amination of 2,2'-dimethyl-l,3-propanediol
-
of
in
a
the
corresponding
cumulative
supercritical
desired reactions also in this
(70 %) and the amino
selectivity of 77
ammonia and
case.
diamine
an
% at 75 % conversion.
ammonia
At temperatures
>
excess
favoured the
210 °C the amination
selectivity decreased due to the formation of wo-butylamine. The amination of the
structurally related 2-methyl-l,3-propanediol and 1,3-propanediol
reaction conditions afforded much lower amination selectivities
due to
degradation products formed by
water is not
possible
for
under similar
(< 20 %) mainly
water elimination. Direct
elimination of
2,2'-dimethyl-l,3-propanediol.
To complement the study about the influence of the reactant structure on the
diamine
diol in
selectivity, 1,4-cyclohexanediol was selected. The amination of the cyclic
supercritical
ammonia has been studied at 135 bar. An
unsupported cobalt
catalyst stabilized by
5 wt%
aminocyclohexanol
1,4-diaminocyclohexane with a cumulative selectivity of
and
Fe afforded the main reaction
products
4-
97 % at 76 % conversion. Excess of ammonia and short contact time favoured the
desired reactions. At low and high conversions the amination
selectivity decreased
due to the formation of dimers and oligomers, and degradation products.
Recycling
of the unreacted diol and amino alcohol intermediate
alternative
economic process for the
synthesis
of
can
provide
an
1,4-diaminocyclohexane.
Summary
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Zusammenfassung
Die
heterogen katalysierte Aminierung
von
aliphatischen
Alkoholen durch
Ammoniak, primäre, sekundäre und tertiäre Amine ist ein bekanntes und wichtiges
Verfahren
zur
Synthese von Aminen. Im Vergleich zu zahlreichen Berichten über
die Aminierung
die
von
Aminierung
Sachverhalt
einfachen aliphatischen Alkoholen, sind Untersuchungen über
von
liegt
Diolen
sicher nicht
zum
am
Diamine eine breite industrielle
entsprechenden Diamin
fehlenden Interesse
an
selten.
den
Dieser
Produkten, da
Anwendung (z.B. Chelat-Reagenzien, Fungizide,
Fasern, Polyamidharze oder Epoxidhärtemittel) finden. Der mögliche Grund für
das
geringe
wissenschaftliche Interesse ist vielleicht die
Tatsache, dass die
Aminierung von einfachen Alkoholen bereits ein komplexes Verfahren mit einigen
Nebenreaktionen ist.
Amins
zu
Wichtige Nebenreaktionen sind: (i) Disproportionierung des
sekundären
und
tertiären
Aminen,
(ii)
Kondensation
oder
Decarbonylierung des Carbonyl-Zwischenproduktes, (iii) Bildung von Nitrilenbei
hohen
Temperaturen
Hydrocracking
Selektivitäten
bzw.
zu
und
niederem
Hydrogenolyse.
Wasserstoffpartialdruck
Die
erhalten, sind grösser,
Schwierigkeiten
wenn
ein
Diol
(iv)
und
angemessene
verwendet
wird.
Interessanterweise, benutzt kein etablierter industrieller Prozess ein Diol als
Reaktant. Die meisten
Dichloroalkanen
primären Diamine werden durch die Umsetzung
hergestellt.
Der Nachteil dieses Verfahrens ist
von a,co
jedoch
-
die
Korrosion, die durch Salzsäure hervorgerufen wird. Die Neutralisation der Säure
erzeugt
grosse
Mengen
Entsorgungsprobleme.
von
Betrachtet
wässrigem
man
die
NaCl
Verfügbarkeit
und
wachsenende
des Reaktanten, die
Zusammenfassung
xiv
Korrosions-
und
Aminierung
von
Umweltprobleme,
Diolen eine attraktive Alternative
Schwerpunkt dieser Arbeit war deshalb
Die
katalytischen
die
zu
etablierten Prozessen sein.
katalytische Aminierung
von
Diolen.
Studien werden in einem kontinuierlichen Festbettreaktor im
Druckbereich bis 150 bar und bei
Die
übergangsmetallkatalysierte
die
könnte
Temperaturen
bis 235 °C
durchgeführt.
katalytische Synthese von 1,3-Diaminopropan aus 1,3-Propandiol und
Ammoniak wurde in einem Druckbereich
wurden charakterisiert mit Hilfe
Cobalt-Katalysatoren
verwendeten
50 bis 150 bar untersucht. Die
von
N2-
von
Physisorption, XRD, XPS, TPR, Ammoniak Adsorption durch Pulsthermoanalyse
und DRIFT-Spektroskopie. Die
letztgenannten Untersuchungen ergaben sehr gute
Resultate mit einem 95 Gew.% Co- 5 Gew.% Fe
schwache
von
saure
starken
und basischen Zentren
war
entscheidend,
nur
sehr
andere
wichtige
verschiedene
Hydrogenolyse,
Oligomerisierung)
und
Alkylierung, Disproportionierung, Dimerisierung
Eine
um
(retro-Aldol,
Nebenreaktionen
katalysierte
unterdrücken.
welcher
Zentren besitzt und kein Ammoniak adsorbiert. Die Abwesenheit
sauren
säure-basen
Katalysator,
Voraussetzung
für
die
zu
verbesserte
Diaminbildung war das Vorhandensein einer metastabilen ß-Co Phase. Eine kleine
Menge von
Eisen konnte die
Phase verhindern und die
Umwandlung
zur
thermodynamisch stabileren a-Co
Deaktivierung des Katalysators unterdrücken.
Verwendung eines Ammoniaküberschusses (molares
war
notwendig,
Die
Verwendung
um
die
von
Bildung
von
Oligomeren
-
vermindern.
katalysierten Synthese
für die
von
im
nahkritischen
Selektivitätsverbesserung
Zusammenfassung
Bereich
wird
auf
von
eine
Lösungsmittel
Diaminbildung
1,3-Diaminopropan
Dimethyl-l,3-diaminopropan. Selektivitätssteigerungen
wurden
NH3/ Diol > 20)
überkritischem Ammoniak als Reaktant und
ergab signifikante Selektivitätsverbesserungen
Cobalt- und Nickel
zu
Verhältnis
Die
um
Ammoniak
höhere
bei der
und
2,2'-
den Faktor 4 bis 18
beobachtet.
Die
Ammoniakoberflächen-
XV
konzentration
zurückgeführt,
welche
die
Aminierung begünstigt
und
die
Abbaureaktionen unterdrückt. Es scheint, dass der Effekt des überkritischen
Ammoniaks nicht auf einen bestimmten
Die
heterogenkatalysierte Aminierung
2-Methyl-l,3-propandiol
Ni/Silika
Katalysator oder Reaktanten begrenzt ist.
Katalysator
Temperaturen
180
von
und
-
1,3-Propandiol wurde
überkritischem
mit
2,2'-Dimethyl-l,3-propandiol,
von
über einem kommerziellen
Ammoniak
235 °C untersucht. Die
bei
Aminierung
135
von
bar
und
2,2'-Dimethyl-
1,3-propandiol ergab die Hauptprodukte, Diamin (70 %) und Aminoalkohol (7 %),
mit einer Gesamtselektivität
von
überkritischem Ammoniak im
Reaktionen.
Aminierungsselektivität
des
zu
Gunsten
sehr viel kleinere
°C
210
>
der
strukturell verwandten
Propandiols ergab
Verwendung
von
Überschuss begünstigte auch hier die erwünschten
Temperaturen
Bei
Aminierung
77 % bei 75 % Umsatz. Die
verminderte
Bildung
von
sich
die
Isobutylamin.
Die
und
1,3-
2-Methyl-l,3-propandiols
Aminierungselektivitäten (<
20
%),
was
hauptsächlich auf Abbaureaktionen durch Wassereliminierung zurückzuführen ist.
Eine direkte
Wassereliminierung
ist bei
2,2'-Dimethyl-l,3-propandiol nicht
möglich.
Um
die
Untersuchungen
Diaminselektivität
zu
ergänzen,
über
wurde
Struktureinfluss
auf
die
1,4-Cyclohexandiol gewählt.
Die
den
Aminierung des cyclischen Diols wurde in überkritschem Ammoniak bei
untersucht. Mit einem
wurde,
bildeten
sich
Diaminocyclohexan
Cobalt-Katalysator, der
die
mit 5 Gew.% Eisen stabilisiert
Hauptprodukte 4-Aminocyclohexanol
mit einer Gesamtselektivität
Ammoniaküberschuss und kurze Verweilzeiten
Reaktionen.
Bei
tiefen
Aminierungselektivität
Produkten
aus
was
und
hohen
auf die
von
von
und
1,4-
97 % bei 76 % Umsatz.
begünstigten die
Umsätzen
Bildung
135 bar
erwünschten
verminderte
sich
die
Dimeren, Oligomeren und
Abbaureaktionen zurückzuführen ist. Das
Rezyklieren
des nicht
Zusammenfassung
xvi
umgesetzten Diols und Aminoalkohols kann eine alternatives, wirtschaftliches
Verfahren
zur
Synthese
Zusammenfassung
von
1,4-Diaminocyclohexan darstellen.
1
General Introduction:
Amination of Diols and
Polyols
Acyclic
to
Aminés
1.1 Introduction
The
an
heterogeneously catalyzed amination of aliphatic alcohols,
alcohol with ammonia,
for the
primary or secondary amine,
beginning
established
variety
of
as
was
of this century.
the
industrially
aliphatic
described
by Sabatier
in patents,
In
most
important
indicating
polyamines
missing
interest
ethylenediamine
the
and its
can
a
be found in
data have been
published
amination of simple
to
the
aliphatic alcohols,
corresponding acyclic di-,
This apparent contradiction is
products. Diamines
and
studies
clearly
not due to a
polyamines, especially
polyethylene polyamine homologues, find a broad range
of commercial application
[20,21 ]. The likely explanation for the limited scientific
interest is that the amination of
complex
reaction has been
examples
original
diols, triols and polyols
are scarce.
in
[1.2] already
the commercial value of the reaction.
comparison to reports on
tri- and
and Mailhe
process for the manufacture of
and aromatic amines. Numerous
the transformation of
rather
well-known process
During the past decades, the
reviews and books [3-19], though most of the
on
a
synthesis of the corresponding primary, secondary and tertiary amines. The
basics of alcohol amination
at the
is
i.e. the reaction of
a
simple (monofunctional) alcohol
process with several side
is
already
a
reactions, and only the proper choice of
General Introduction
2
the
catalyst and reaction conditions can provide sufficiently high selectivity to the
desired
product.
The difficulties
alcohol reactant and in many
below the
As
illustration, the
the
cases
economically acceptable
an
amplified when using
are
most
selectivity
for
amination
alcohol
ethylenediamine.
the desired
applied commercially.
Most of the diamines
product
is far
The
only example
monoethanolamine
to
(and polyethylene polyamines)
are
of
dichlorides.
traditionally
manufactured
disadvantage
of the method is the corrosion caused
from
polyfunctional
[21 -23]. Remarkably, no process
1
transformation
the
is
or
processes for the manufacture of
important
diol is
relatively cheap
from the
di-
level.
simple aliphatic diamines are collected in Table
starting
to
a
a,co-alkylene
A
well
known
by hydrogen chloride.
The
amounts of aqueous sodium chloride and
subsequent neutralization
creates
growing difficulties in
environmentally acceptable disposal. Considering
availability
of
its
corrosion
and
environmental
the
reactants,
large
problems,
the
the
heterogeneously catalyzed amination of diols could be an attractive and economic
alternative to
Table 1 :
(for
more
some
established processes.
Industrially applied processes
details, see refs. [21-23]).
Diamine
for the manufacture of
(a) C1-(CH2)2-C1
NH3 (aq.)
+
(b) H2N-(CH2)2-OH
1,3-diaminopropane
CH=CH-CN
1,4-diaminobutane
(a)THF
+
+
+
NH3; +H2
of
a
diol
or
polyol
General Introduction
with
a
of
two-stage process
Cl2; +NH3
NC-(CH2)4-CN
point of view
minor process yet
NH3 + H2
(b) CH2=CH-CH=CH2
1,6-diaminohexane
primary aliphatic diamines
Comment
Process
1,2-diaminoethane
From the
some
+
two-stage process
+
Cl2;
+
NH3
two-stage process
H2
selectivity, the
secondary amine,
easiest reaction is the amination
as
the
product tertiary
amine is
3
relatively unreactive (Not considering the cyclization reactions).
On the other
hand, the most demanding reaction type is the amination with ammonia to produce
primary amines,
ammonia. The
the
as
topic
product
of this
is
chapter
considerably
is the latter
triols and polyols to the corresponding
more
reactive
(basic) than
reaction, the amination of diols,
primary amines. For a better understanding,
the formation of amino alcohols and their transformation to diamines will also be
discussed. As concerns the basic knowledge on the catalytic amination of aliphatic
alcohols, the reader should consult with former reviews [3-7,9-11].
1.2
Catalysts, Reaction
Two
types of materials
of alcohols:
Routes and Conditions
are
suitable for the
heterogeneously catalyzed
amination
hydrogenation-dehydrogenation catalysts, usually being supported
metals, and solid acid catalysts, such
Accordingly,
as
zeolites, phosphates and oxides.
the reaction routes and conditions will be discussed in separate sub¬
chapters.
1.2.1 Amination
The metal and
of diols and
of
over
polyols [25-58],
and selective
are
are
alcohols. No
catalyst
can
similar to those
widely applied
in the amination
general rule concerning the choice of an active
be found in the literature, which
range of amination reactions. The
frequently
guide
and contain
some
would be valid
used active components
Ni, Co, Cu and Ru. Many catalysts described in patents
multicomponent materials
for
Catalysts
supported metal catalysts, reported to be efficient in the amination
simple aliphatic
to a broad
Metal
or
papers
are
additive (e.g. Cr, Fe, Zn, Ir and Rh)
enhancing the activity, selectivity or long term stability.
An
example is shown
General Introduction
4
in Table 2. Fe/alumina
ethanolamine to
of Co and Ni
to
be inactive in the transformation of
ethylenediamine, but incorporation of Fe improved the selectivity
catalysts.
Frequently
amination of
found
was
used supports
diethylene glycol
are
alumina, silica and titania. A study of the
with ammonia
over
supported
3) revealed a rather good correlation between the reaction
surface determined
stabilize the
acidity
of the support.
Comparison
metal and the reaction rate
dispersed
of metal
catalysts
catalysts (Table
rate and the
by oxygen chemisorption [59]. Seemingly,
was to
Table 2:
Ni
was
specific Ni
the role of support
independent
in the amination of ethanolamine to
of the
ethylenediamine.
Conditions: 7 g catalyst, 29 g ethanolamine, 37 g water, 81 g ammonia, 44 bar H2,150 bar total
pressure, 225 °C, autoclave (adapted from ref. [31]).
Catalyst
Atomic
(molar)
ratio
at 40
Ni-Fe
1: 1
Ni-Fe/Al203
0.9:0.1
Ni-Fe/Al203
0.95
Ni/Al203
1: 1
Raney Ni
Selectivity to ethylenediamine, [%]
:
:
1
0.05
:
1
-
%
conv.
at 60 % conv.
70
62
61
55
54
51
54
52
46
41
(a)
(a)
65
60
Fe/Al203
1
:
1
Ni-Co-Fe/Al203
1
:
1
Co-Fe/Al203
1:1:2
69
62
Ni-Co/Al203
1:1:2
51
50
Co/Al203
1
50
48
(a)
-
inactive
catalyst,
no
:
:
1
:
3
1
reaction occurred
On the basis of the very few mechanistic studies available in the literature
[48, 59, 60], Scheme 1 illustrates the key steps and the typical side reactions
during
the
metal-catalyzed
reactions. For the sake of
General Introduction
amination of a,ra-alkanediols
simplicity, the
1 used
as
model
interactions of reactants, intermediates
and
products
catalyst
with the
schemes, simple
transformations
arrows
are
surface
reactions. The
with ammonia,
an
rmine 3
a
a
equilibrium
most
is indicated
of the
only
to
carbonyl
group,
(ii)
(i) dehydrogenation of
condensation of the
one
of the
-
carbonyl group
primary or a secondary amine via a carbinolamine adduct to form
(or enamine [7]), and (iii) hydrogénation to the monoaminated alcohol
(frequently
4
of 1 to
though
and in other
of both directions.
The main reaction steps include the
CH2OH groups
specified. Also, here
indicate the reaction route,
equilibrium
emphasize the importance
are not
termed
as
"aminol"). Basically, these steps
are
the
same as
those
proposed for the amination of small and long chain aliphatic amines [6,7,61-63].
Table 3: Performance of various Ni
catalysts
in the amination of
below. Conditions: fixed bed reactor, 190 °C, 1 bar, 0.5 g
1 : 10:5 molar ratio (adapted from ref. [59]).
diethylene glycol, as shown
catalyst, diethylene glycol : NH3 : H2
=
CH2CH2NH2
CH2CH2OH
O
+
NH3
+
H2
O
.H 0
——
Catalyst
Ni
^BET
Chemisorbed 02
MÉ1
[wt.-%]
NH
CH2CH2/
VCH2CH2OH
NCH2CH2OH
CH2CH2
O
Rate constant"
[mmol h'1 g']
Ni/Si02
57
199
8.1
8.8
Ni/Si02
38
142
7.2
7.6
Ni/Si02
24
179
5.2
5.8
Ni/Al203
52
123
4.0
4.7
Ni/V205
57
121
3.5
2.7
Ni/Ti02
54
64
1.6
2.1
Ni/Zr02
58
58
1.2
1.2
Ni/ZnO
52
88
1.2
1.1
Ni/Nb205
52
46
0.2
0.6
-
for the
consumption
of diethylene
glycol.
General Introduction
ho'
'0H
r~2
4
n=
CH,
I
retro
aldol
^
+
r
1
-
O^-^OHn=
I
1
Jn-1
12
NH,
'n
11
10
k
H,
o
o
NH3
-H,0
n=4
r
h2/nh3*
L.r/1
|_ Jn_
-2H20
HN<^LJ^0H
^
13
f^X
H2
4
h2
n=
H
LfLr;/l
^
-H20
1
H,N'
1 n-3,
I
14
OH
N'
9
H
n
=
0
•NH,
n
51
8
HoN-
=
2,3
LJn
-H2°
5
HoN'
15
'NH
1
in
H,
NH.
H?N
n
=
4
-NH,
Scheme 1
General Introduction
L
-H20
NH3
H20
Jn-1
7
The second hydroxyl group of the diol reacts
5-7. The
key intermediates
their formation and
The
to
the two adsorbed
are
consumption
similarly forming compounds
carbonyl compounds
determine the overall
can
rate and
2 and
5;
selectivity.
selectivity to the aminol 4 is usually good, but the diaminoalkane 7 is difficult
produce as a major product. (On the other hand,
with
good yield when starting
from the
A multitude of side reactions
have
some
diamines
be
can
prepared
aminol).
are
possible. Typical
side
reactions, which
already been evidenced in the animation of simple aliphatic alcohols, are the
(i) disproportion of the amine to form secondary and tertiary amines, and ammonia
[64], (ii) condensation or decarbonylation of the carbonyl compound intermediate
and
(iii) the formation of nitriles
pressure
at
high temperature
and low
[65]. Hydrocracking and hydrogenolysis of amines
dominant
at
are
can
result in
"polyamines";
important products.
fully excluded,
multifunctional
as
some
example
One
undesired formation of oligomers and
be
also become
can
high temperature [6].
With bifunctional alcohols the condensation and
reactions
hydrogen partial
most
disproportionation
of them with limited molecular
mass
is the formation of 8 from 5 and 7. The
is
polymers
frequently reported
of the intermediates and
products
and cannot
are
bi-
or
compounds.
Cyclization
reactions represent
an
other
important
class of side reactions.
Some dominant routes to the formation of (hetero)cyclic products 9 and 12 -15
illustrated in Scheme 1
[46,48].
The structure of the
are
alcohol, i.e. the distance of
the functional groups determines the direction of the amination reaction. Short
chain diols tend
to
dimerize
oligomers, depending
ethanediol (and
polyamines
of
on
the
to
form stable
catalyst
cyclic compounds
and reaction conditions. For
ethanolamine) dimerize easily to piperazine
higher
molecular
mass.
9
or
or
produce
example, 1,2-
form 8 and other
1,6-Hexanediol tends
to
cyclization,
General Introduction
8
forming
five-
of
aminol intermediates 4 to 15 via 5
C4-C6
or
six-member
rings
such
the basis of thermodynamic considerations,
and
[48,51]. The self-condensation
12-14
as
or
a
7 has also been
similar
cyclic products. Dehydrogenation
dominant at high temperatures,
compounds [66].
of the
As the formation of 8
-
1,4-butanediol
typical
of metal
to dimerize and
1,3-diols
an
"retro" aldol reaction
intermediate
additional
producing
possibility
two
primary
7
at elevated
is acid-
or
are
temperature
base-catalyzed
from the
amines is
based
thermodynamically
kinetic
on
A
saturation of the
catalyst
some
as
diminishing
suppressed by applying high
higher [e.g. 55]).
recommended for the
amines to
compared
the
the
to
by
selectivity
too
large
ammonia and
of linear
to
primary amines,
a
(20
ammonia
be
can
to 1 or even
excess
is the
activity,
decrease of
excess
as
is
polyamines [9, 39, 79-81].
Although from a stoichiometric point of view hydrogen
General Introduction
can
to that of ammonia.
[39, 43]. Similarly, moderate ammonia
production
secondary
higher reactivity
molar ratio of ammonia to diol
surface
that the
favoured. A similar behaviour
possible disadvantage of
cases
primary
considerations, due
(nucleophilicity) of the primary amine,
Consecutive reactions,
secondary and tertiary amines
kcalmor1). Thus, assuming
contribution of entropy is minor, the conversion of
in
oligomerize.
amines from ammonia and alcohol is close to
slightly exothermic (each step by
reported
energetically
carbonyl compounds
thermoneutral [10], whereas the further reactions to
expected
is
ß-hydroxy-aldehyde 2 [47].
The formation of
tertiary
rings
of the C-0 and C-N bonds
catalyzed amination reactions, especially
and pressure. With
reverse
cyclic products becomes
12 membered
Fragmentation products by hydrogenolysis
be
of
leading to thermodynamically more stable aromatic
unfavourable, long chain diols (>C8) tend
and
reactivity
On
1,5-pentanediol can also be expected. Low ammonia concentration favours the
formation of
are
proposed [60].
is not
essential, its
9
addition to the reaction mixture in amounts
ranging
from 0.1 to 2 moles per mole
hydroxyl group is necessary when the amination is performed over metal catalysts
[e.g. 55]. Saturated
amines
are
formed
predominantly
in the presence of
sufficient amount of hydrogen, whereas imines, enamines and nitriles
in
the
absence
hydrogen [6, 46]. Besides, hydrogen
of
simultaneously occurring disproportionation
are
a
favoured
suppresses
of amines and protects the
the
catalyst
from deactivation by incorporation of nitrogen and/or carbon into the metal lattice
[28, 67, 68].
It
was
found in many
that both batch reactors
cases
(autoclaves) and
continuous flow systems (fixed bed reactors) are suitable for the amination of diols
and
polyols.
though
The
generally applied total pressure ranges between
it has been demonstrated that
prerequisite
for
high
(for ammonia: pcm
no
report has been published yet
on
the rate and
selectivity of an
on
=
Some
discussed in the
a
[46, 48]. The
ammonia-hydrogen
114 bar,
Tcnt
=
132 °C
or
mixture is in the
[69]). Interestingly,
supercritical medium
amination reaction.
the amination of ethanolamine to
cyclic product.
fixed bed reactor is not
the influence of sub-
Solvents (other than ammonia)
addition of water increased the
bar,
achieving reasonable conversions is around
180-250 °C. Under these conditions the
state
a
reaction rates and selectivities
obtaining good
reaction temperature necessary for
supercritical
pressure in
50 and 300
a
are
rarely applied.
mixture of
selectivity
of
It
was
found [70] that in
ethylenediamine
a
contradictory observations
and
Ni-Cu-Cr-oxide
on
piperazine,
catalyst
to the
the influence of water will be
following chapters.
In batch reactors the amount of metal
catalyst is usually between
5 and 30
wt.-% related to the amount of alcohol. In continuous reactors the total amount of
reactant
h and g
feed varies in
a
broad range,
usually between 0.5 and 10
g total feed per
catalyst (WHSV) [e.g. 35].
General Introduction
10
1.2.2 Amination
Solid Acid
over
1.2.2.1 Reaction Route
Among
small
the solid acid
chain
over
Zeolites
catalysts,
aliphatic
Catalysts
zeolites
diamines
are
[71-77]
frequently
or
cyclic
used for the
amines
synthesis
of
[78] from the
corresponding amino alcohols. Y-zeolites, ZSM-5 and mordenites in their protonic
form
are
mostly employed molecular sieves. Only
the
acidic oxides
diamines
diols
or
over
compared
[79]
or
silicates [80, 81]
polyamines. Concerning
acid
as
efficient
catalysts
for the
applied
preparation of
the reaction conditions, the amination of
catalysts requires rather high temperature (250
to the conditions
with
supported
metal
-
450 °C),
as
catalysts.
the limited number of mechanistic studies it is clear that the
Despite
Br0nsted sites of zeolites play
a
key role in alcohol amination [71-75, 82, 83].
studies indicated that ammonia and amines
form ammonium
species.
The
of ammonia. Amino alcohols
ions
very few patents propose
adsorption
are
are
adsorbed
IR
Br0nsted sites and
on
of the amine is much stronger than that
adsorbed as ammonium-ions and not as oxonium-
[73,74].
It has been
alcohols
proposed
zeolites
over
that the first step of the amination of monofunctional
(and acidic oxides) is
the
dehydration
to
an
olefin
or
ether
[3, 10, 18]. Using the example of the amination of ethylene glycol, Scheme 2
illustrates the
key steps
which have been
proposed
for the zeolite
catalyzed
reaction, and also the rather broad range of products detected [74, 76, 77]. It is
assumed that
ethylene oxide is
ethyleneimine
when
distributions observed
4 [77].
using
General Introduction
ethanolamine
over an
Ethylenediamine
22
the intermediate after
as
the
minor
reactant.
of the diol and
Typical product
are
shown in Table
product, independent
of the reaction
iron-promoted natural
was a
dehydration
zeolite
11
conditions or catalyst modification. Similar reaction steps and the formation of the
corresponding epoxide and imine
amination of
as
key intermediates
were
proposed for
the
1,2-propanediol over H-ZSM-5 [76].
18
NH,
HO
16
(iv r\/-\
NH2 -H,0
HO
O
OH
17
HO
N
OH
H
20
19
H,0
NH,
NH-
Y7
-
-H20
3-
N
H
/~\
H2N
NH2
21
/ \
/^
NH2
23
0-0:
24
H
:
25
i
Scheme 2
Ethylenediamine
can
be
is ethanolamine, instead of
spectroscopic
ethylene glycol,
studies indicated that
intermediate and,
ethyleneimine.
produced with good selectivity, when the reactant
interestingly,
in
as
illustrated in Table 5
protonated ethyleneimine
some
cases
even
the main
[74]. IR
the
key
product
was
was
The results also suggest that strong acidic sites in the limited size
General Introduction
12
of
the
zeolite
ethylenediamine
channels
and for the
for
favourable
are
the
selective
synthesis
of
suppression of the formation of bulky polyamines and
heterocyclic compounds. There is no steric control when using macroporous silicaalumina, accordingly, self-condensation of ethanolamine to form cyclic and linear
polyethyleneamines
ammonia
dominates
the reaction with the less
over
nucleophilic
[71].
ethylene glycol (16) over a natural aluminosilicate (gumbrin) promoted
composition (according to scheme 2): 9 piperazine, 17
ethylene oxide, 18 acetaldehyde, 19 ethanolamine, 22 1,2-diaminoethane, 24 methyl
pyridines, 25 pyrrolidine. Conditions: fixed bed reactor, space velocity of glycol: 0.2 h"1, glycol
to NH, molar ratio =1:1 (adapted from ref. [77]).
Table 4: Amination of
with 5 wt.-% ferric oxide. Product
-
-
-
-
-
-
-
T, °C
Products, [wt.-%]
liquid
gas
of the
Composition
liquid product, [wt.-%]
9
16
17
18
19
22
25
24
7.8
92.2 1.6
82.4
4.7
2.0
3.7
0.3
1.8
2.3
1.2
325
12.6
87.4 1.2
80.0
5.7
1.6
3.5
0.5
2.1
3.8
1.5
350
17.0
83.0 1.1
76.6
7.0
1.5
3.4
0.7
2.1
6.5
1.1
375
23.7
76.3 1.0
75.3
6.6
1.2
3.1
0.7
2.3
8.9
0.9
400
28.8
71.2 1.0
73.6
6.6
1.2
2.8
0.9
2.5
10.7
0.7
300
An increase of the ammonia/ethanolamine molar ratio
positive
influence
on
(up
the rate of ethanolamine conversion and the
to
NH,
80) had
selectivity
a
to
ethylenediamine (Fig. 1). Recently, transient response experiments indicated that
in methylamines
synthesis over zeolites the rate determining step is the desorption
of amines from the acidic sites, aided
by adsorbing
enhancement observed in the presence of
ethylenediamine synthesis
ammonia concentration
can
on
be
a
large
explained similarly.
was
observed when
General Introduction
using
silica-alumina
excess
The
ethylenediamine selectivity
Scheme 2. A similar correlation between ammonia
selectivity
ammonia [82]. The rate
of ammonia in
positive effect of high
is understandable from
excess
and
ethylenediamine
catalysts [79].
13
catalysts, according to
',330°C, 1 bar, NH3/alcohol
acid
Amination of ethanolamine with ammonia and solid
Table 5:
'mol
Scheme 2 Conditions fixed bed reactor, contact time 200 g h
molar ratio 50
(adapted
from refs
Pore size,
Catalyst
[73, 74])
Conv
SiOrAl20.,
-
Selectivity, [%]
Cyclic'
.
Others'1
IV
21"
100
1
7
49
43
14
[nm]
H-Chabazite
0 38
4
4
69
13
H-Faujasite
0 74
6
13
76
9
9
H-Linde-type
071
L
0 70
H-Mordenite
a
-
ethylenediamme,
-
15
23
32
21
21
42
81
7
9
3
ethyleneimine,
c
-
mainly piperazme
and derivatives, and
1,4-
diazabicyclo-octane,d mainly pol> amines
-
(NHg/ethanolamine)
Figure
1:
Ethylenediamme synthesis
(Si/Al=6 1)
as a
from ethanolamine
ethanolamine/NH3/H2
On the basis of the observed
the
molar ratio
on
function of ammoma/ethanolamine molar
310 DC, 1 bar total pressure,
m
40
20
5
0
zeolite-catalyzed amination
EDTA-modified H-MOR zeolite
ratio
Conditions fixed bed reactor,
molar ratio 1/50/25
(adapted from ref [74])
product distribution, the possible reaction route
of
1,4-butanediol
27 is
depicted
in
Scheme 3.
The main product is pyrrolidine 29, independent of the reaction temperature (Table
General Introduction
14
6) [77]. (Note
the
same
zeolite
promoted
applied for ethylene glycol amination,
step
can
as
provide either tetrahydrofuran
rapidly animated to
the main
catalyst
and similar conditions
shown in Table
28
or
4.)
The first dehydration
3-buten-l-ol 30.
product pyrrolidine,
but
no
were
Tetrahydrofuran is
amines derived from the
amination of the olefin 30 could be detected. This explanation is in agreement with
former observations, that tetrahydrofuran reacts
over
acidic zeolites
selectivity [84-86].
(e.g.
H-Y) forming pyrrolidine with
H-L and
On the other
smoothly at 350 °C with ammonia
HO
V
V
90 %
hand, the selective amination of olefins (via
Markownikow addition of ammonia) is limited at low temperature
/\/V0H
over
\
\y
/
-H20
*
27
NH,
-H20"
by
the
/ "
V
H
29
28
-H20
'
'
HC^^
NH
3^
no
""
products
detected
30
Scheme 3
insufficient
activity
of zeolites and
temperatures above 300-350 °C [9, 87].
General Introduction
by
the
thermodynamic equilibrium
at
15
Table 6: Ammation of 1,4-butanediol 27
over a
with 5 wt -% ferric oxide Product composition
reactor, space velocity of diol- 0 2 h
',
diol to
Products, [wt -%}
T, [°C]
gas
64 7
49 3
12
47 6
1.9
49 5
13
46 8
21
425
187
813
450
28 6
714
phosphoric
-
They
and
alkylamines [9, 88]
performance
of
some
ethylenediamine
phosphates,
are
or
such
titania
suggested
cyclic
bed reactors
be
LaHP04,
and also
interest in
catalytic
synthesis
of mixed
and
gain increasing
in the transformation of ethanolamine
is illustrated in Table 7.
noncychc tri-
and
The
LaHP04
case more
polyamines.
was
the
most selective
than 50 % of the
products
Both autoclaves and fixed
(under pressure) have been used [89]. A vapor phase operation
can
advantageous to minimize leaching problems.
It has been
proposed [9, 88]
phosphate catalysts
activated
by
a
elimination of
occurs
surface
a
via
a
phosphate
water molecule
that the amination of alcohols
"phosphate ester"
group and
a
new,
alkylated amine
and
a
(Scheme 4).
substitution reaction the amine reactant
in
SrHP04
as
acyclic polyalkylene polyamines [89-91].
phosphate catalysts
amines and
3-buten-l-ol
for the selective
catalyst to ethylenediamine, but even in this
were
-
Phosphates
acid treated alumina
amination reactions.
to
33
1,4-butanediol,b tetrahydrofuran,c pyrrolidine,d
I-IIIa and Illb metal
liquid product, [wt -%]
30"
29J;
1 1
57 8
Group
(adapted from ref [77])
25
400
over
1
08
85 6
12 2 2 Reaction Route
1
38 6
918
14 4
-
=
30 2
82
-
of the
2j£
2T
(gumbnn) promoted
to Scheme 3. Conditions: fixed bed
NHt molar ratio
Composition
liquid
350
a
natural aluminosilicate
according
regenerating
metal
mechanism. The alcohol is
phosphate
In the
replaces the
over
ester is
formed after
following nucleophilic
surface
phosphate, resulting
the surface active site.
General Introduction
16
Table 7: Amination of ethanolamine 19 with ammonia over metal phosphate catalysts,
below. Conditions: batch reactor, 300 °C, 130 bar,
ethanolamine, 35.5
ho7
g
\w2
NH3/ethanolamine molar ratio
=
as
shown
2/1,63.3 g
NH3 (adapted from ref. [90]).
'
iW^\h2
+
nàf^éT^m
22
19
+
m/~~\h
+
31
+
HjN
NH
Mb
+
«»her polyamines
32
Time, [h]
Catalyst, (wt.-%)
Conv., [%]
Selectivity, [%]
22
31
32
9
LaHP04 (19.3)
2
53
34.8
7.5
9.1
7.0
LaHP04 (18.5)
4
50
49.2
26.5
10.2
5.0
NdHP04(19.3)
2
68
12.3
9.8
11.5
9.9
YHP04 (15.7)
2
67
14.8
12.8
12.4
6.9
GdHP04 (20.3)
2
70
13.9
6.2
7.4
5.2
PrHP04 (19.2)
2
80
18.4
3.6
9.9
6.3
possible
Other
could be excluded
RNR'R'
ROH
are
acids and their
be
cannot
acidic
and
hydrolysis
intermediate. A
of the amide would
a
phosphate catalyst
General Introduction
weak
catalytic activity
attributed
properties
subsequent interaction
to
their
alone. Another
a
surface
with the alcohol reactant
provide the alkylated amine and regenerate the
active site. The formation of surface
treating
relatively
the activation of the amine via
probable mechanism would be
phosphoramide
the basis of
experimental observations. Metal
phosphates
Scheme 4
on
routes
with
phosphoramides
ammonia
had been observed when
[92, 93]. However, tertiary
17
aminoalcohols
are
also reactive
on
phosphate catalysts
and form
cyclic amines.
Since tertiary amines cannot form amides, this observation supports the phosphate
ester
mechanism of alcohol amination.
1.3 Amination of Bi- and
1.3.1
Polyfunctional
Alcohols
Synthesis of Ethylenediamine from Ethylene Glycol and Ethanolamine
Ethylene glycol is
at a low
the
simplest aliphatic diol which is produced in a large
price. Nevertheless, only
ethylene glycol
to
a
few patents
are
available
ethylenediamine [26,32,33,57,58].
the selectivities to the ethanolamine intermediate is
ethylenediamine
are
reactions. A Co-oxide
exception:
usually
catalyst
this material
Pd/silica
Ni-Re/alumina
No further
for
raw
aminated
good,
early patent [58]
an
as
yields
to
and dimerization
cyclization
seems to
ethylenediamine yield
less efficient
are
but the
at
90%
be
an
glycol
Ni-Cu/alumina, Ni-
[33, 57].
development of this process or recent reports on more promising
ethylene glycol
commercial interest. As it
is the
70 %
the amination of
At moderate conversions
180 °C and 300 bar. Other catalysts, such
at
catalysts
described in
provided
conversion,
or
moderate due to
on
amount
appeared, indicating
amination have
was
discussed in the introduction, not
material for the commercialized process, rather
directly to ethanolamine and
than in
a
[21-24,94]. Accordingly, only the ethanolamine
separate step
-
the
lacking
ethylene glycol
ethylene oxide
to
is
ethylenediamine
ethylenediamine transformation
will be discussed below.
The usual reaction temperature is around 200 °C. The
ethylenediamine
is
high
at low
selectivity
to
temperature, but the activity of metal catalysts is
rather low at 150 -170 °C. At higher temperature
cyclization reactions and (above
General Introduction
18
250
°C) fragmentation of the alcohol and/or the amine become dominant [45] An
example demonstrating
range
is
shown
m
the
product
distribution
the interesting temperature
in
Fig 2 [36]
o
o
N$
>—'
B0-
ty
>
t)
bO-
CD
(1)
CD
40-
C
n
30(i>
>
c
o
XI-
O
10I
1
1
1
1
.
1
180
170
1—'
1
1
190
210
200
Temperature [°C]
Figure 2:
Influence of temperature
catalyst Conditions
NH3/ethanolamine molar ratio 5 3
a
Ni-Cu-Cr
on
product selectivity
6 3, 8 7-10 6 ml
product
as
is
in
Fig
3
amination reactions
catalyst
the
the
as
shown
cyclic product
General Introduction
favoured
is
conversion
ref
and
over
ml cat),
[36])
product
by¬
by the long reaction time,
at
in
Fig
high
4
thoroughly discussed
an increase
enhances the ethanolamme
formation of piperazine,
to
is
catalyst composition
patent literature [31,43, 56] For example,
selectivity
on
g/(h
[31]
The crucial role of
Ni/alumina
4 9-5 5
similar to that of temperature The formation of piperazine
in consecutive
illustrated
the animation of ethanolamme
H2/greactant (adapted from
The influence of increasing reaction time
distribution
m
fixed bed reactor, 172 bar, feed
of the metal
conversion
in
content
the
of
a
and favours the
[56] It is not clear, whether the higher
metal
loading
is
due to the
higher
19
Time
[h]
Figure 3: Influence of reaction time on the product composition in the reaction
19 with
ammonia
19/NH3
molar ratio
piperazine, 22
-
of ethanolamme
autoclave, Ni-Co-Fe/Al203 catalyst (24 wt -%, related to 19)
1/10, 225°C, 150 bar Numbers (according to scheme in Table 7) 9
Conditions
-
ethylenediamine,
70
I
31
-
aminoethylethanolamine (adapted
from ref [31])
I Conversion
H Piperazine
60
V//A
Elhylendiamine
2^50
o
<D
>,40
c
§
30
5
§20
o
10
I
H.
10
30
44
Ni
Figure
loading [wt -%]
loading of Ni/alumina in the amination of ethanolamme with
NH3/ethanolamine molar ratio 10/1, ca 0 5 bar H2, 195°C,
reaction time (adapted from ref [56])
4: Influence of the metal
ammonia
Conditions autoclave,
146 bar total pressure, 8 h
General Introduction
20
conversion
or to
promoters, such
improve
the
the different size and
morphology
of the metal
particles.
Several
iron, chromium and molybdenum, have been suggested
as
ethylenediamine selectivity;
for
examples
see
to
Table 2.
As it was discussed in the former chapter, the concentration of ammonia and
hydrogen
strongly
can
catalysts. High selectivity
ammonia, usually
catalyst, 130
selectivity
to
ethylenediamine requires
to
at least 10 mole per
ethylenediamine
at
a
large
reacting hydroxyl
170 bar ammonia pressure
-
selectivity
influence the reaction rate and
suggested
was
molar
was
to afford
polyamines
can
even at
low conversion, when the ammonia/alcohol ratio is not
[32],
illustrated in
as
Fig.
lifetime in the amination of small and
of
hydrogen
can
hydrogen
long
chain
0.1-2 mol per mol
hydroxyl
ethanolamine
multimetallic
increase of the
for
low
General Introduction
the
be
significant
sufficiently high
selectivity
and
catalyst
the relative
cyclic
and linear amines in the
hydrogen
concentration is around
The continuous amination of
catalyst is shown in Fig. 6
as an
example.
An
molar ratio from 0.02 toi.3 resulted in
molar ratio
by
hydrogen concentration,
obtaining good selectivity
reaction rate due to
70-90 %
selectivity to
aliphatic alcohols,
[e.g. 28, 55].
ethylenediamine/piperazine
[35]. The application of
advantageous
group
hydrogen/ethanol-amine
decrease of the
on
control the ratio between
amination of bifunctional alcohols. The usual
over a
Ni
5.
Beside the well known effects of
amount
a
of
200°C [30]. Lower ammonia concentration
%. The formation of di- and
only 40
metal
excess
Using
group.
favoured the formation of polyethylenepolyamines and at 80 bar the
diamine
over
to
catalyst deactivation [45].
a
a
factor of around 4
which
the diamine, is limited
would
be
by the
low
21
NHj/ethanolamine
Figure
5: Influence of
ethanolamme
bar
(adapted
NH^ethanolamine
conversion
from ref
molar ratio
molar ratio
on
the
ammonia mention the
or
possibility
of
terf-butanol have been
or
to increase the
low pressure conditions.
the
proposed
majority
of the
reported
Under medium and
excess, acts
solvent
A
is
special
as a
high
solvent
of
a
no
solvent
processes
to
in order to moderate the
were
minimize the self-condensation of
liquid phase
on
under
unambiguous conclusions concerning
can
be drawn from the literature. The
performed
without any added solvent.
usually applied in high
supercritical fluid).
A clear effect of added
(liquid
or
mixture
the lower reaction rate due to dilution of the reaction
case
activity
pressure conditions ammonia,
is the addition of water, which is formed also
stoichiometric amount. Water
influence
ethanolamine with
ammonia concentration in the
Unfortunately,
advantages of the presence
or
using solvents. Mainly water, dioxane,
(and improve the selectivity) of the catalyst,
ethanolamine
catalyst, 270°C, 186
[32])
All patents describing the amination of ethylene glycol
cyclohexane
distribution at 20%
product
Conditions fixed bed reactor, Cu-Ni-Cr-oxide
the diamine
as a
solvent
can
have either
selectivity [24, 38, 57, 93],
as
[30, 93].
during reaction
positive
or
depicted
in
negative
in
Fig.
7.
General Introduction
22
Depending on the reaction time (conversion), higher initial water concentration in
improved
the reaction mixture
supported
Ni
decreased the
or
ethylenediamine yield
over a
catalyst.
.=
ra
k_
-
(0
°8-
y
o
£
\
\
0)
S
N
\
6-
\
(0
t_
\
D.
Q.
•35
\
o
„
\
4"
\
\
c
>v
\^
IUI
(0
<D
35 % Conversion
\
<U
N.
^^*~~——~_?_
Ov
2-
c
(D
hyl
UJ
60 % Conversion
o-
i
«
i
00
05
1 0
Hj/ethanolamine molar
Figure
6:
Product composition
ethanolamine
space
conversion
velocity
4 5
as
a
1 5
ratio
hydrogen/ethanolamine
function of
Conditions fixed bed reactor, Ni-Cu-Cr-oxide
g/(h, mlcat), NH3/ethanolamine
molar ratio
6/1,
molar ratio and
catalyst, liquid hourly
172 bar,
no
data for
temperature (adapted from ref [35])
Interestingly, addition
of
piperazine
to
improves the ethylenediamine selectivity [24]
at
2
ethanolamine before the reaction
The presence of 3
the beginning of the amination reaction enhanced the
-
and
10 %
over a
cyclic
Ni/(alumina-silica) catalyst,
dimers. This observation offers
selectivity by recycling piperazine
responsible
for its formation.
General Introduction
a
and
-
6 %
piperazine
ethylenediamine yield by
and decreased the amount of linear
simple
way to
shifting
the
improve
the diamine
equilibrium
reaction
23
30
?S
o^
T)
ÜU
<D
>.
(1)
C
15
t(0
T)
10
r
ID
>.
(
LU
0
Reaction time
Figure
7.
solvent
Influence of the relative amount of water used as
transformation Conditions autoclave 160°C p(NH,)
ethylenediamine
catalyst (1 g/ 10g ethanolamine)
Ni/alumma silica
available
[hi
(adapted
The
from ref
synthesis
acidic zeolites
of
[72-74],
in
the ethanolamine
2 bar
=
data for 25% water at 7 h and 9 h
ethylenediamine
as
from ethanolamine
discussed above
at almost
in
chapter
catalyzed
is
12 2 1
properties and the Si/Al
The necessary reaction temperature
was more
active but
was in
provide a variety of linear and cyclic amines
instead of
a
powder,
in a
by
ratio
of
denvatives and
the range of 300-330 °C
hardly selective to ethylenediamine
Ethylenediamine is a reactive intermediate and its
was
also
Good selectivities
mordenite Dominant by-products were piperazine, its N-alkylated
ethylenediamine yield
are not
complete conversion of ethanolamine were
obtained after proper tuning of the acidic
Silica-alumina
-
2 bar
[93])
(up to 72 % ethylenediamine)
polyamines
p(H2)
=
further transformation can
It is therefore not astonishing that the
found to be lower when using
a
pelletted catalyst
fixed bed reactor under otherwise identical conditions
diffusion
[24] The negative effect of slow intraparticle
can
be minimized by using
General Introduction
24
jAminol
| Diamine
70
\ Enamine
60-
50
„
st
£,40
>
I
I
30
o
W20H
10
0
20
50
40
30
Hydrogen [%]
Figure 8: Influence of relative hydrogen concentration on selectivity m the animation of
ethylene glycol with dimethylamine, according to Scheme 5 Main products 2-N,Ndimethylammo-ethanol (33, ammol), N,N,N',N'-tetramethyl-1,2-diaminoethane (34, diamine) and
N,N,N',N'-tetramethyl-l,2-diaminoethene (35, enamine)
Cu/alumina, 230 QC, 1 bar total pressure, ethylene glycol
diluent nitrogen,
meso- or
conversion
macroporous
almost 100 %
(adapted
Conditions
0 1 bar,
from ref
fixed
bed
dimethylamine-
reactor,
0 3
bar,
[46])
catalysts with relatively high outer surface area ("egg-shell"
type catalyst).
1.3.2 Amination
In
the
ofEthylene Glycol
amination
of
ethylene glycol
amine/alcohol molar ratios
of reactions
with
[46,48].
with Amines
An
with
secondary
(typically between
example
is the
1 and
6)
amines
can
be
relatively
low
applied in this type
Cu-catalyzed amination of ethylene glycol
dimethylamine in a continuous fixed bed reactor at atmospheric pressure [46].
Beside the amine/alcohol ratio, the
controlling
dominant
the
product
product
General Introduction
was
hydrogen partial pressure had a crucial
distribution
(Fig. 8).
the enamine 35
In the absence of
(Scheme 5), but
an
role in
hydrogen
the
increase of the molar
25
hydrogen concentration up
to
and diamine 34 close to 80 %
was
60 %
improved the total selectivity to "aminol"
33
(at over 90 % conversion of glycol). The conversion
hardly dependent on the hydrogen/glycol or amine/glycol ratios. Addition
of
25 wt.-% water to the reactant feed did not effect the reaction rate and diamine
selectivity, but increased
the fraction of aminol
\
H0,
^
V
um^
.
^
~
Cu/alumina
HN^
+
~K~
\
N
\
\
2
OH
/
\
/
N
•
,
the expense of enamine.
on
+
\
\
33
\
N
OH
16
+
/
N
\
N
34
35
Scheme 5
Even better selectivities to aminol and diamine
were
obtained in the
reaction conditions
same
reaction
over a
were more severe
(53 and 31%, respectively)
SrHP04 catalyst [88], though
(275 °C and 55 bar). SrHP04 showed
outstanding selectivity, 97
% at 71 % conversion, in the amination of
glycol
diazabicyclo[2,2,2]octane
with
piperazine
9 to
the
26 at 350
°C,
as
ethylene
shown in
Scheme 6.
H
/N
HO
+
OH
^n"
""n2U
^N'
H
16
9
26
Scheme 6
An
industrially important process, the synthesis of polyethylene polyamines
by the amination of ethylene glycol or ethanolamine with ethylenediamine will be
discussed later in
chapter
1.3.5.
General Introduction
26
1.3.3 Amination
of Higher Aliphatic Diols
Only a few examples
are
known in literature for the animation of higher
diols with ammonia. Moreover, these reactions
demonstrate the
information
on
application
1,3-propanediol
demonstrate the amination
catalyst,
sometimes used
without
product distribution.
A
(45 %) estimated
on
is
chosen to
was
There
are
the results of the reaction, except the
the basis of water formed. Other
bifunctional alcohols used for the
to
typical example
with ammonia, which reaction
concerning
only
providing detailed
activity of a nickel-rhenium catalyst [33,34].
any data available
conversion
a new
the reaction route and
the amination of
hardly
range of
are
aliphatic
production
of
primary
aliphatic
diamines
1,2-
are
propanediol [58], 1,4-butanediol [95], 2,3-butanediol [31], 1,6-hexanediol [28,48,
51,52,58,96,97], 1,8-octanediol and 1,10-decanediol [52]. In all
supported metal hydrogénation catalysts
were
to
main
usually good. For
Na2S03
to
product over
Raney Ni catalyst
suppress the side reactions.
zeolite-based
catalysts
was
pretreated
Conversely, pyrrolidine
at 350
-
450 °C
scale for
application,
polyamide production.
because
[51],
or
in
a
The reaction is
cyclization
with
was
the
interesting
1,6-diaminohexane is used in large
complicated by
the simultaneous
formation of hexamethyleneimine 37 via disproportionation reaction,
Scheme 7
an
[77].
The amination of 1,6-hexanediol with ammonia is the most
reaction for industrial
selectivity
[125]. The reaction was performed in
autoclave at 210 °C and 47 bar, and the
aqueous
are
the reaction of 1,4-butanediol with ammonia afforded 73 %
4-amino-l-butanol at 47 % conversion
metal and
applied.
The selectivities to the half-aminated product "aminol"
example,
cases
as
shown in
reaction from the aminol intermediate. For
example, a Co-Ni-Cu/alumina catalyst converted an 80% aqueous solution of 1,6hexanediol and ammonia to
General Introduction
a
mixture of imine
(49%) and diamine (23%),
at
220
27
°C and 300 bar
2
[28].
^^^^^NH,
\^hJ
=
NH3
+
H
36
The process
was more
67 % diamine and 33 %
selective in dioxane
are common
200 °C and 138 bar total pressure in
molar ratio of 20. Partial
imine
was
A
recycling
selectivity
to
in
a
metal-catalyzed
comparison
of the
100 %
of the amination of
indicates
a
atmospheric
diamine from
ethylene glycol (34,
250 °C and
at 38 %
conversion, i.e.
no
additional
1,6-hexanediol and ethylene glycol with
pressure
were
over an
was
the
performed in a continuous fixed
alumina-supported
Cu
Scheme 5) is formed with 20 %
catalyst.
The
selectivity
at
high hydrogen concentration. The maximum selectivity to the
in the amination of 1,6-
65 % at 230 °C, and the influence of hydrogen concentration
minor. Besides, in the amination of ethylene
was a
hexamethyleneimine by-product
(N,N,N',N'-tetramethyl-l,6-diaminohexane)
hexanediol
ammonia/alcohol
an
significant influence of the distance between
bed reactor at
diamine
Raney Ni provided
amination of alcohols:
batch reactor, and
reacting OH groups [46,48]. Both reactions
at
solvent:
formed.
dimethylamine
best,
as a
hexamethyleneimine selectivities at 58 % conversion. The
reaction conditions used
enhanced the diamine
37
Scheme 7
major product (Fig. 8),
glycol
was
the rather stable enamine 35
whereas enamine formation
was
negligible
in the
amination of 1,6-hexanediol.
General Introduction
28
A+î
dealdolization
/*&*
H
a;1
•H,0
-2H2H/
OH
OH
OH
NEt,
O
ELNH
NEt2
2H
iH
H.NH,
I
-2
v2H
H2oy'.
H
XJ ^^ ^J ^* ^J ^*^JH
de-
aldohzationl
EtH2H
I
Et2NH2H
-
-
l|
Et2NH
H20
H,ol
-
H2Oj
MEt,
NEt2
'J
2Et2NH4H
-2H20|
2
(C2H6)3N
Scheme 8
Interestingly,
no
diamine among the
amination of 1,3-butanediol with
diethylamine
[47]. The major product was 2-butanone, its
as a
function of
space
10
temperature (170
velocity (0.15
-
6 cm3 h
%), triethylamine (8
reaction network,
Scheme 8. An
-
-
g"1).
23 %) and
proposed
important
'
on
products
250
could be identified in the
over a
amount
CuO-Cr203-ZnO catalyst
ranging between 38 and 60
°C), amine/diol molar ratio (1
Other
important products
N,N-diethyl-l-buthylarnine (3
the basis of the
product distribution,
feature is the dealdolization of the
compound intermediates formed by dehydrogenation
Dealdolization is
the field of
catalyzed by diethylamine,
homogeneous aldol
General Introduction
were
-
a
-
4) and
acetone
-
is
14
%
(5
-
%). The
depicted
in
ß-hydroxy-carbonyl
of the diol reactant.
well known effect of N-bases in
condensation and de-aldolization reactions
[98].
29
The
high reactivity of ß-hydroxylamines (possible half-aminated intermediates of
ß-diols) was also demonstrated
for
N,N-dimethyl-l-amino-3-butanol
butanone
special
A
primary
more
over
a
at 200 °C over a
and
case
a
wide range of molecules
was
almost
quantitatively
is the amination of
aliphatic diols,
groups [100]. The
reactive and usually selectively convertible to
supported Co and Ni catalysts,
on
For
example,
transformed to 2-
Cu-ZnO-Cr203 catalyst.
secondary hydroxyl
substantial influence
[99],
as
which contain both
secondary hydroxyl group is
an
amino group with ammonia
shown in Table 8. The
the reaction rate
catalyst support had
(conversion) and selectivity. Excellent
selectivities at moderate conversions could be achieved at
or
below 200 °C. The
activation of the primary hydroxyl group at higher temperatures enhanced the rate
of side reactions and diminished the overall amination
selectivity [100].
Table 8: Partial amination of 1,2-butanediol over
supported Co, Ni and Pt catalysts. Conditions:
autoclave, 10 g catalyst, 3 moles 1,2-butanediol, 6 moles ammonia, 180 °C, 50 atm initial
hydrogen pressure (adapted from ref. [106]).
Catalyst
atomic
ratio of
Conv.,
Selectivity
Molar ratio of
[%]
to 2-amino-
aminated
1-butanol, [%]
metals
{sec.OWprim.OH)
Co/MgO
95/5
22
60
5.3
Co/BaO
95/5
21
70
4.7
Co/Fe203
Co/Zr02
Co/LaA
Co/Th02
Co/Th02-Fe203
Ni/Fe203
Ni/Th02
Ni/La203
90/10
26
93
13.6
95/5
67
56
8.6
95/5
68
79
10.3
99/1
65
92
20
97/1/2
64
86
14.5
80/20
20
43
14.4
99/1
19
53
24.3
95/5
41
91
18.5
Pt/C
5/95
48
7.7
2.1
General Introduction
30
The
regioselectivity of the
ot the diol
was
[1001 The
achieved
secondary
in
OH
hydroxyketone
to the
the animation of 1,2-alkanediols
can
be
also
on
the structure
secondary hydroxyl
group
(Fig 9) Higher reactivity of the
the
explained by
intei mediate, which is
easy
formation
of the
cx-
thermodynamically more favoured than the
hydroxyaldehyde Competitive
a
depends
most selective animation of the
group
formation of the
over a
animation reaction
animation of 1
and 2-butanol
Co/La203 catalyst showed hardly any difference in reactivity and selectivity
corresponding
hydroxyl
groups
m
amines,
the
indicating
regioselective
the crucial importance of the vicinal
animation
of diols
16
80
1
I Conversion
l^ü Set to
n amino
V//A Ratio (n
amino
1 alkanol
h 14
1 alkanol/1
am no n
alkanol)
12
£, 60-
<D
-10
^
8
O
40
E
6
4
O
o
DC
2
0
1 2
Figure
1 2
propanediol
9- Selective transformation of the
and 1 3-diols to
n
diol/ammonta molar ratio
1.3.4 Amination
1/20 180°C
=
p(H2)
=
50 atm
ofPolyoxyalkylene Diols
Polyoxyalkylene glycols
a
secondary hydroxyl group in the animation of some
2 or 3) over a Co catalyst Conditions autoclave,
1-alkanols (n
amino
usual molecular
1 3 butanediol
1 2 butanediol
of 200
-
8000
a
linear or branched structure with
Linear
polyoxyalkylene
synthesized by the polymenzation of terminal epoxides,
Genet al Introduction
ref [100])
and Triols with Ammonia
and triols may possess
mass
(adapted from
such
as
diols
are
ethylene oxide or
31
propylene oxide (38 and 39 in Table 9) or by polymerizing tetrahydrofuran 40 [42,
101 -109,124]. The polymer contains primary or secondary OH groups,
on
the
monomer structure.
41 and 42,
are
Branched oligomers and polymers, such
obtained in the presence of an initiator, e.g.
The latter reaction is nonselective,
as
depending
compounds
glycerol [104,110-112].
resulting in a mixture of polyoxyalkylene triols
with different side chain sizes. The amination of such
triols with ammonia includes also
undesired
oligomeric
and
polymeric
reactions
cyclization
[110],
as
illustrated in Scheme 9.
Ni, frequently Raney Ni [103,104,110-112]. A drawback
The preferred catalyst is
of Raney Ni is the deactivation
Various promoters,
improve
the
by
water formed
including Fe, Ru, Cu, Cr,
during the
Mo and Co, have been
selectivity and life time. Mesoporous
alumina) is important in
the amination of
The available information
bulky
concerning
structure of the
reactants
the
selectivity by the
indirect
analysis,
ratio of
the
primary
amination of
and
amount
polyoxyalkylene
On the basis of this
diols and triols to the
primary OH
hydrogenolysis
deteriorates the
product quality [106]. Fig. 10 illustrates
a
of the less reactive
polyoxypropylene
Table 9. With increasing temperature
is rather
of water formed, and
reported for the amination of small chain aliphatic diols.
in the amination of
support (e.g.
better selectivities and
reaction is the
triol with the
to
[105].
secondary amines.
corresponding primary amines provides distinctly
than those
proposed
product composition
limited. The conversion is usually estimated from the
the
amination reaction.
the
A
yields
typical side
groups, which
good yields obtained
general
formula of 42 in
(and conversion), the yield of primary amine
approached 8 5 % [ 104]. Even better results were obtained by enhancing the loading
of a
Mo-promoted Raney nickel catalyst, as depicted in Fig.
11.
Interestingly, the
selectivity to primary amines was hardly affected by the conversion, at least on the
basis of the indirect
analysis.
General Introduction
32
Table 9: Structures of
polyoxyalkylene glycols used
for the amination.
Polyoxyalkylene glycol compound
M
x
[g/mol]
Ref.
3-170
>230
104
HO-CH-04-(0-CH2-CH)X-OH
33-85
230-500
105
HO-C^CH2-CH2-CH2-(0-(CH2)4)x-OH
1-50
162-4000
102
1-5
>230
104
38
HO-a4-CH2-(0-CH2-CH2)x-OH
39
40
ÇH3
ÇH3
CH3
CH2fO-CH2-CHlOH
ÇH3
'
|
^0[CH-Clt-0]bÇH)x
41
la
ÇH3
CH2{0-CH2-CH]pH
ÇH3
CH2-0-CH2-CH-OH
ÇH3
1
42 HO-CH-CH2-0-CH
1
110
-
-
„„
1
3
CH2-O-CH2-CH-OH
a +
b
+ c
=
7to 170.
A
OH
OH
+
n?>^
rS
—
HO
+
HO
HO
2NH,
3H20
rS
HO
|3NH3
|-3H20
O
Scheme 9
General Introduction
OH
NH,
33
80
9
60
o
Q.
E
o
40
ü
p
20-
—i
1
1
1
1—
1
210
200
230
220
Temperature [°C]
Figure 10: Influence of temperature on the selective ammation to primary amines of a
polypropylene polyol containing three terminal hydroxyl groups (average molecular mass 5000)
Conditions fixed bed reactor, Raney-mckel nuggets, 145 bar, space velocity 1 53 -1 62 g/(h ml
cat ),NH3/OH groups molar ratio 67 (mean value), lyOH groups molar ratio 3 4 (mean value),
(adapted from ref [104])
100
1
t
8°-
-,
1
60-
o
Q.
e
8
lo¬
ts
o
2
20-
0-
0-1
1
0
1
1
1
2
4
6
1
1
Catalyst/reactant
Figure
11:
Influence of
amination of a
molecular
mass
.
8
catalyst/reactant weight
1
1
1
12
14
16
ratio
[wt -%]
ratio on the
product composition
in
the
polypropylene polyol containing three terminal hydroxyl groups (average
5000) over a Raney nickel catalyst containing 1 % Mo promoter Conditions
autoclave, 118 bar (mean value), 220°C, 7 2 wt-%
selectivity
1
10
to primary amines
ammonia, 20 nun reaction time, 99 %
(adapted from ref [104])
General Introduction
34
The amination with ammonia of
groups is slow and
primary hydroxyl
difference in their
the presence of
For
example,
used after
some
The
big
as
discussed in the former
chapter.
polyoxyalkylene triols with a molecular mass of 300 -1700 are
amination with ammonia for the
of amination
degree
residence time in the
1.3.5
Due to the
special applications only a partial amination of polyols is required.
partial
foams. The
incomplete [111. 112].
reactivity, secondary OH groups can be selectively aminated in
primary alcohols [100],
For some
polyoxyalkylene glycols containing
can
production
be controlled
by
of
polyurethane
the reaction time
(or
catalyst bed) [107].
Synthesis ofPolyalkylene Polyamines
industrially produced polyalkylene polyamines
ethylenediamine.
The
major
ethyleneamines
are
mainly
the
oligomers
diethylenetriamine
are
of
32,
triethylenetetramine 45, tetraethylenepentamine 46 and pentaethylenehexamine 47,
as
shown in Scheme 10.
Polyalkylene polyamines
starting
in each amination process
oligomers,
piperazine
piperazine,
branched chain
9 and its
the
arise
alkylated derivatives,
are
as
by-products
from bifunctional alcohols. Beside these
and
homologues (e.g. 44)
oligomers
normally
e.g.
regarded
43)
as
are
cyclic products (mainly
also formed. In contrast to
valuable
products, especially
diethylenetriamine.
For the
production
of
polyalkylene polyamines, both
metal
catalysts [39,
113-117] and solid acids, mainly phosphates [9,79-81,88-91,118] are employed.
The
supported phosphoric
vapour
phase operation
128]. The
reactants are
Piperazine (up to
10
General Introduction
acid type
catalysts
are
not
is necessary to minimize the
ethanolamine
or
ethylene
truly heterogeneous
and
phosphate leaching [126-
oxide [117], and ammonia.
wt.-%) can be added before reaction to minimize its formation
35
during amination [39],
U.MX
+
H2N
NH3^
—*~
N/
(H2)
19
+
^NH2
/V
2
31
22
/
\
\
/
HN
NH
/
\
\
/
HN
+
H
N
+
"NN/%,„,
H2N
43
H,N
*
32
'
H,N
+
NH
Jr
H,N
+
2
44
+
45
HoN
+
Ma
NH
H,N
+
2
Scheme 10
Similarly, diaminoethane
can
also be
recycled [39,119].
of diaminoethane to ethanolamine from 0.1
from 5 to 10 and
for metal
Re-B
hydrogen
catalysts.
catalyst,
A
in the range of 1
to
-
In
0.25, of ammonia
Fig.
to
a
molar ratio
ethanolamine
30 mol% of the total feed
typical product composition of such
is shown in
general,
12. The conversion
was
a
process,
increased
are
using
used
a
Ni-
by applying
higher temperatures. The most striking effect of high conversion (temperature)
the
rapidly enhancing
ethylenediamine
to
over
on
the expense of
acid catalysts is usually carried out at higher temperatures
400 °C). Still,
diethylenetriamine
over a
piperazine, mainly
22.
The reaction
(250
fraction of
is
phosphated
as
Fig.
13 illustrates, selectivities up to 70% to
32 and around 20% to
titania
catalyst.
triethylenetetramine 45
The formation of undesired
were
achieved
cyclic products
9
General Introduction
36
and 43
remarkably low.
was
detectable
selectivity.
to obtain the
Note that titania without
In other
cases
phosphoric
temperatures below 270 °C
required product composition
Conversion
over
acid showed
were
no
suggested
phosphate type catalysts [126].
[%]
12: Amination selectivity in the reaction of ethanolamine 19 with a mixture of ammonia
ethylenediamine 22, according to Scheme 10. Conversion was increased at constant space
velocity by increasing the temperature from 167 to 190 °C. Conditions: fixed bed reactor, Ni-Re12.4 mmol/(h, gcat), 22 2.25
B catalyst; 150 bar, NH3/19 molar ratio: 7, space velocities: 19
mmol/(h, gcat). Main products: 9
N-(2-aminoethyl)ethanolamine, 32
piperazine, 31
diethylenetriamine, 45 triethylenetetraamine (adapted from ref. [39]).
Figure
and
-
-
-
-
-
-
3-Amino-l-propanol
synthesis
of
oligomers,
1,3-diaminopropane
also used for the
were
polyalkylene polyamines [113-115]. Contrary
the
deaminated
and
polypropylene polyamines
are
to diaminoethane
almost free of cyclic, branched and
products [113, 114]. By increasing
the
hydrogen
conversion decreased and the formation of dipropyltriamine dimer
whereas at higher temperatures the
molecular
mass
could be
114].
General Introduction
yield of dimer was
decomposed
lower.
pressure, the
was
favoured,
Oligomers of higher
to the valuable dimers and trimers
[113,
37
80
1 wt -% P
(as phosphate)
5 2 wt -% P
(as phosphate)
12
I
70-
H
60
3" 50
CT>,
|40H
"o
V
30-
CD
CO
20-
10
I
0
rim
toa
46
32
22 and
ethylenediamine
Polyethylenepolyamine products from the reaction
the P content), according
ethanolamine 19 over phosphated titania catalysts (characterized by
of
Figure 13:
325°C, 22/19 molar
Scheme 10 Conditions fixed bed reactor, 70-140 bar(not specified),
2, 65%
conversion
Main
of 19
9
products
-
piperazine, 32
31
tnethylenetetramine, 46 tetraethylene-pentamine,
(hydroxyethyl)-piperazme (adapted from ref [118])
-
-
1.3.6 Amination
In fact,
none
mild conditions
aminated
applied,
selectivity
belongs only formally
of the OH groups
to
rather the
form,
monosaccharides, such
as
e
g.
is
transferred
carbonyl
glucamine [120]
glucose,
are
metal catalyst,
usually Ni,
The reaction
runs
glucosyde intermediate
as
or
-
-
N-
is
to
the amination of
amino group under the
an
aldose
or
ketose
is
isomaltamine [121]. Simple
converted with
depicted
smoothly
to an
group of
glucosyde (imine), followed by hydrogénation to the
a
45
N-(2-armnoethyl)ethanolamine, 43
ofSugars
The reaction of sugars with ammonia
polyols.
diethylenetnamine,
-
to
ratio
liquid
amine
ammonia to the N-
(glutamine [ 120]) over
in Scheme 11.
at 50
-
100 °C and 120 bar
[122]. The
N-
and
labile, especially in the presence of water,
General Introduction
38
CHO
HC=NH
HCOH
susceptible to caramelization (Maillard
CH2t
HCOH
HCOH
I
HOCH
HOCH
-HjO
HCOH
I
+
H.
Ni
HCOH
HCOH
I
Glucose
I
CH2OH
CH2OH
N-Glucosyde
Glucanune
the
I
HCNH2
I
HCOH
HCOH
I
HOCH
HOCH
I
HCOH
required
more severe
tendency
to
products
such
the
Scheme 11
of water
as
shorten the
as
are
hand,
applied
higher
is the
fragmentation
ethanolamine and
Still, under optimized
conditions about 90 % selectivities
HC
CH2OH
of monosaccharides
the
form
diaminoethane.
I
conditions
hydrogénation,
HCOH
HC-
to
lifetime of imine. On the other
for
HCOH
high hydro¬
a
HCOH
I
CH2OH
rate is
génation
I
HCOH
HCOH
reaction). Therefore,
HOCH
desired
amines
were
primary
polyhydroxy-
obtained in the amination
[120]. The proposed continuous process allows
solvent without formation of
Amination with ammonia of
quantitative preparation
of such
secondary
to
even
the
use
amines.
polysaccharides
is less selective. For the
a
better
aminating agent [121], though it is too expensive for industrial applications.
In the
amination of
was
palatinose
very slow
(17h
50 °C and 150 bar
yields
of 17
to the
-
fast and efficient
two
[123]. The yield
stereoisomers)
was
over
to
97 %,
hydrazine,
Raney Ni
at
"isomaltamine"
as
compared
to
aminating agent. In the amination of other dissacharides the
corresponding monoaminoglycosyl-hexitols
63 %. Possible side reactions
are
was
lower, in the range
isomerization, retro-aldol reaction, ß-
elimination, Heyns- and Amadoni-rearrangement,
General Introduction
found to be
°C) but the subsequent hydrogénation
(sweetener, equimolar mixture of
79 % with ammonia as
was
the first reaction step, the condensation with
at 20
was
amino-sugars, hydrazine
or
Millard-reaction [123].
39
OH
(H2)
OH
OH
48
OH
49
Scheme 12
A similar reaction is the
according
prepared
synthesis of serinol 49 from dihydroxyacetone 48,
Scheme 12 [129-131]. This
to
over
Raney Ni
or
pharmaceutical
supported noble
100 bar, in the presence of ammonia and
reported
when the condensation step
was
metal
intermediate
catalysts
at
50
hydrogen. Yields
completed
before
-
can
be
90 °C and 6
up to 99 %
starting
the
-
were
catalytic
hydrogénation.
1.4 Conclusions
The animation of di- and
secondary and tertiary
those
acids
metal
(mainly
complexity
amines
zeolites and
proper
development
are
rather
corresponding primary,
performed under conditions
simple aliphatic
phosphates).
of the reactions: many
Accordingly, the
triamines
be
to the
rather similar to
alcohols. Both reactions
hydrogenation-dehydrogenation type catalysts
amination of diols and triols,
and the
can
in the amination of
applied
catalyzed by
polyfunctional alcohols
of
as
tuning
an
more
compared
side reactions
to that of
far, there
are
times
conversion)
possible
are even
are
synthesis of diamines and
sufficiently high,
less
in the
catalyst composition,
not too many reactions
in which the selectivities to the desired amines
yields (i.e. selectivity
are
monofunctional alcohols.
of reaction parameters and
So
by solid
The main difference resides in the
economic process for the
demanding.
and
are
reported
and
good
frequent.
General Introduction
40
However, the industrial importance of di- and polyamines and the need for
non-corrosive and
relatively cheap,
manufacture create
Scope
The
possible
the
of the
primary
A continuous
of the
the
availability
of
of
a one
step amination of
were
the motivation for
investigating
production by heterogeneous
amine
aliphatic
advantages
of reactants, the environmental and corrosion
of established processes,
catalyzed amination
tests and
strong driving force initiating further research in this field.
a
technical and economical
aliphatic diols,
feasibility
processes for their
of Thesis
1.5
problems
environmentally friendly
the
transition metal
diols with ammonia.
high pressure reactor system was set up to enable the catalytic
analytical facilities were designed to determine
liquid
reaction mixture.
Based
on
preliminary screening
tests two
catalytic investigations: unsupported
the
product composition
types of catalysts
cobalt based
catalysts
were
used for
and nickel
on
silica.
The influence of iron and lanthanum
pretreatment (acidic/base modification)
on
the
promoters
as
well
as
catalyst
catalytic performance of cobalt
were
characterized by means
of several bulk and surface characterization methods. The
potential of these cobalt
catalysts
has been examined. The
catalytic materials
catalysts was evaluated in the amination of 1,3-propanediol. 1,3-Propanediol is the
simplest representative
data available
of higher
concerning
heterogeneous catalytic
the
aliphatic diols,
cyclization
amination of this
side reactions.
General Introduction
of the process and the
efficiency
therefore it is easy to dose to the reactor.
but in the literature there
requirements
compound. 1,3-Propanediol
Additionally,
Disadvantageous
it shows
are no
a
low
is
a
for
liquid,
tendency to
is the 1-3 functional group distance
41
(fgd)
of this molecule. The
reactions
ß-hydroxy-aldehyde intermediate is
(e.g. retro-aldol reaction,
elimination, decarbonylation). The
water
influence of the structure of the diols
selectivity
on
prone to side
to diamine and
degradation
products in the nickel-catalyzed amination was investigated using 1,3-propanediol,
2-methyl-1,3-propanediol and 2,2-dimethyl-1,3-propanediol. 1,4-cyclohexanediol
selected to
was
alcohol
the
complement
are more
cyclic
study.
the
reactive than the
structure is
The
stable and contains
more
products
In order to
are
at
and reactant ratio
on
the
affords
fluid
on
to
a
at pressures,
supercritical
solvent
fluids
properties.
to
tune
the solvent
selectivity
a
to the desired
supercritical.
as
particularly,
This
attention
was
paid
to
provides
°C, Pc
132.4
=
a
114.8 bar).
media for chemical reactions
In this
at
properties,
study,
ammonia
supercritical
to
was a
conditions
eliminate transport
reaction
can
be affected
when the reaction medium is
an
the
where ammonia forms
integrate reaction and product separation.
heterogeneously catalyzed
pressure,
=
Conducting chemical reactions
reaction rates and to
reaction steps of
indirectly by
selectivity
the
unique
opportunities
limitations
sub-
on
reactant.
a
fgd. Accordingly,
the effect of temperature, pressure, contact time
(critical data of ammonia: Tc
from their
solvent and
increased
product distribution. Special
for the utilization of
originates
an
an even
expected.
elucidating
influence of pressure
Impetus
groups of this
optimize the reaction conditions reaction parameter studies were
performed aiming
supercritical
-
primary ones of 1,3-propanediol. Additionally,
decreased number of side reactions and
amination
secondary hydroxyl
interesting potential
for
All
directly or
changed from
controlling
the
selectivity of heterogeneous catalytic reactions.
The thesis has been written in such
independently. This
individual
leads to
some
a
fashion that each
repetition
chapter can be read
in the introduction parts of the
chapters.
General Introduction
42
1.6 References
Mailhe, Cr., 150 (1910) 823.
[I]
P. Sabatier and A.
[2]
P. Sabatier and E.E.
Reid, Catalysis in Organic Chemistry, Van Nostrand, New York,
1922.
[3]
[4]
H. Glaser, in Methoden der
[5]
R.G. Herman, in
V.A. Nekrasova and N.L.
Org.
Chem.
Shuikin,
Catalytic Conversion
Vol. XJ71, p. 112.
(Houben-Weyl), 1957,
Russ. Chem. Rev., 34
(1965) 843.
of Synthesis Gas and Alcohols to Chemicals (Ed.
Herman), Plenum, New York, 1984, p. 433.
Baiker, M.L. Kijenski, Catal. Rev. Sei. Eng., 27 (1985) 653.
R.G.
[6]
A.
[7]
T. Mallat and A. Baiker, in Handbook of
[8]
Heterogeneous Catalysis, Vol. 5 (Eds. G. Ertl,
Knözinger and J. Weitkamp) VCH-Wiley, Weinheim, 1997, p. 2334.
P.F. Vogt and J.J. Gerulis, in Ullmann's Encycl. Ind. Chem., 5th Ed., VCH, Weinheim,
[9]
M. Deeba, M.E.
[10]
D.M. Roundhill, Chem. Rev., 92
[II]
A. Baiker, in
[12]
York, 1994, p. 91.
M.G. Turcotte, T.A. Johnson, in Kirk-Othmer, Encycl. Chem. Technol. 4th ed., Wiley,
New York 1992,Vol. 2, p. 369.
[13]
J.P.
H.
Vol. A2, p. 37.
Ford, T.A. Johnson, in Catalysis of Organic Reactions (Ed. D.W.
Blackburn), Dekker, New York, 1990, p. 241.
(1992)
Catalysis of Organic
1.
Reactions (Eds.: J.R. Kosak, T.A.
Johnson), Dekker,
New
in Kirk-Othmer, Encycl. Chem. Technol., 4th ed., Wiley, New York 1992,
2, p. 386.
K. Visek, in Kirk-Othmer, Encycl. Chem. Technol., 4th ed., Wiley, New York 1992,
Casey,
Vol.
[14]
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[15]
[16]
Amini, in Kirk-Othmer, Encycl. Chem. Technol., 4th ed., Wiley, New York 1992, Vol.
2, p. 426.
R.W. Layer, in Kirk-Othmer, Encycl. Chem. Technol. 4th ed., Wiley, New York 1992,
B.
Vol. 2, p. 452.
[17]
H.J. Heilen
Mercker, D. Frank, R.A. Reck, R. Jackh, in Ullmann's Encycl. Ind. Chem.,
5th Ed., VCH, Weinheim 1985, Vol. A2, p. 1.
Klyuev,
Khidekel, Russ. Chem. Rev., 49 (1980) 14.
[18]
M.V.
[19]
L.D. Pesce, W.R. Jenksin, in Riedel's Handbook of Industrial
M.L.
Chemistry
9th ed., Van
Nostrand Reinhold, New York, 1992, p. 1109.
[20]
[21]
G.C. Carter, A.R. Doumaux, S.W. Kaiser, P.R.
Umberger,
in Kirk-Othmer,
Chem. Technol. 4th ed.,
Wiley,
New York, 1992, Vol. 8, p. 88.
H.J. Heilen Mercker, D.
Frank.,
R.A. Reck, R. Jàckh, in Ullmann's
Encycl.
Encycl.
Ind. Chem.,
5th Ed., VCH, Weinheim, 1985, Vol. A2, p. 23.
Ind. Chem. 5th Ed., VCH, Weinheim,
[22]
R.A.
[23]
G.C. Carter, A.R. Doumaux, S.W. Kaiser, P.R.
Smiley,
A12a,p.629.
in Ullmann's
Encycl.
1985, Vol.
[24]
[25]
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General Introduction
Leer
-
Vide
-
Empty
2
Experimental
Catalyst preparation,
characterization methods,
specifications of reactants
and the gas
are
described in each
chapter. Here, only the apparatus
chromatographic analysis that was used to determine quantitatively the
composition of the liquid reaction mixture
2.1
experimental conditions and
are
described.
Apparatus
Investigations of heterogeneously catalyzed amination of aliphatic diols
were
performed in a continuous high pressure reactor system (Scheme 1). The apparatus
consisted of four units:
-
gas
dosing
unit for
-
liquid dosing
-
reactor
-
separation
for
hydrogen
and
nitrogen
pressurized liquid ammonia
unit for the
separation
The system included both
a
and
of gases and
main and
a
from
a
hydrogen cylinder,
a
a
secondary
gas feed sections. The
hydrogen
bulkhead union to refill the
stainless steel stop valve,
alcohol
liquid
main gas feed section allowed accurate control of the
range 0 to 1.6 Nl/h. It consisted of
liquid
a
7
um
flow rate in the
connecting
line
stainless steel filter,
Experimental
48
a
manometer
(0
250
-
bar) with
stream of the flow meter and
hydrogen flow
comprised
a
capacity:
valve
specifications
pressure
mass
measure
the pressure up¬
flow controller to
was
a
used for
gas
adjust
the
nitrogen.
cylinder,
a
It
stainless
(1 psi).
was
pumped by a syringe pump (ISCO 500 D)
of the pump
are:
507 ml
flow rate: 1.0
max.
cheque
a
liquid ammonia
to the reactor. The
-
high
valve to
1/8" bulkhead union to refill the unit from
Pressurized
-
insulating
The second gas feed section
rate.
steel stop valve and
-
a
an
pi min"1
to 170 ml
min"1
pressure: 259 bar
Alcohol
dosage
was
made with
a
similar pump. Solid alcohols
dissolved and mixed in liquid ammonia in
were
500 ml autoclave at
an
room
temperature. The ammonia alcohol solution was then transported by the ammonia
pump to the reactor.
The reactor
workshop drawings
working
high
was a
pressure tube
of the reactor and
pressure of the reactor
against overpressure by
a
oven
of 38 ml volume
Appendix 7).
see
200 bar at 300 °C. The reactor
(for
The maximal
protected
was
nickel rupture disc with 200 bar release pressure. The
temperature in the reaction
zone was
center of the tube. The reactor
The reaction mixture
was
(Inconel®-718)
measured
heating
passed through
was
by
a
thermocouple located
regulated by
the reactor in
a
in the
PID cascade controller.
down flow fashion. The
catalyst was situated in the center of the reactor and the remaining free volume was
filled with glass
pellets.
Tescom back pressure
The reactor
cm) attached
Experimental
to
was
The total pressure in the reactor system
was
set
by
a
regulator (4000 psi).
connected to
a
cooler
the inlet of the separator.
section,
a
1/8 inch tube
(length,
100
!
R-OH>-<J>
NH
liquid
&
0-250 bar
Scheme 1: Flow scheme of the continuous
500 ml
separation
high pressure reactor system
220 bar
»quid
sample
50
Product
separation
carried out in
was
separator. The specifications of the separator
-
-
max.
operating
hydraulic
maximum
-
total volume: 35 ml
-
material in contact with
operating temperature:
outlet contained
liquid phase
high
pressure
gas/liquid
were:
pressure: 200 bar
bar
-
liquid
0.36 ml
test pressure: 300
was
a
50 °C
products: stainless steel, quartz glas
The gas outlet line included a 7
The
a
15
collected
urn
um
filter, and a manual backpressure valve.
filter,
a
manually
stop valve and
from
the
a
needle valve. The
needle
valve
for
gas
chromatographical analysis.
2.2
GC-Analysis
2.2.1 General
The GC
(HP 5890A)
purged packed injector,
(30
m,
0.53
1.5 ml min"'
mm
was
equipped
was
an
with
an
autosampler/injector (HP 7673A),
integrator (HP 3396) and a HP-1701 capillary
a
column
i.d., film thickness 1.0 um). A helium carrier gas flow of
used. The applied temperature programs are shown in Table 1, the
retention times of the reactants, amino alcohol intermediates and diamines
are
listed in Table 2.
Commercially
800)
were
applied
Experimental
to
available references and
identify the
reaction
a
GC-MS system
products.
(Finnigan
ITD-
51
Table 1:
Temperature
programs for the
GC-analysis
of the reaction mixture; carrier gas flow:
1.5 ml min"1.
1
"
b
'start
tlstart
t/
rAc
[°C]
[min]
[° min']
[°C]
[min]
[° min1]
[°C]
[min]
1,3-Propanediol
77
12
2
80
0
2.5
180
0
2-Methyl1,3-propanediol
90
12
2
140
0
5
180
0
2,2-Dimethyl1,3-propanediol
90
12
2
140
0
5
180
0
3 -Amino-1 -propanol
93
12
1
110
0
3
125
0
1,4-Cyclohexanediol
100
12
2
107
1.5
2.5
170
0
a
rri
Reactant
temperature;
time;c heating
Table 2: Retention time
c
r
'start
T
a
tlA
rate.
[min] of the
reactant and amination
products;
carrier gas flow: 1.5 ml
mir.''
Reactant
Amino alcohol
Diamine
1,3-Propanediol
19.5
13.9
10.3
2-Methyl-
16.9
12.6
9.0
2,2-Dimethyl1,3-propanediol
24.7
19.3
14.2
3-Amino-1 -propanol
15.1
-
1,4-Cyclohexanediol
34.4
29.5
Reactant
1,3-propanediol
2.2.2
24.7
Quantitative Determination
The catalyst typically attained
After this
a
constant catalytic
period, a liquid product mixture of ca.
gas/liquid separator
which
11.3
were
for
dosed to the
liquid product mixture
water and diluted
by
a
performance after 3 h on stream.
18 ml volume was collected in the
GC-analysis (The volume of
reactor could be
was
monitored
then transferred to
factor of ten. 0.5 ul
a
the alcohol and ammonia
by the pump controller.). The
glassy vessel, dissolved
samples of this solution
were
in 25 ml
injected
Experimental
52
into
a
purged packed injector
at 150 °C
Quantitative determination
performed by
an
by
the
autosampler/injector.
of conversion,
external standard method (absolute
solutions of different concentrations
calibration factors
were
were
yield
and
calibration). Three
prepared
amount of the
was
standard
for the calibration. New
determined for each reaction type.
equations have been used to calculate the
selectivity
following
The
component in the product
mixture:
Calibration
f.
=
(1)
A,,s/c,st
Calibration factor of component i
f,:
A, St:
Peak
c, St:
Concentration of component i in the calibration solution
area
of component i in the calibration solution
(standard)
(standard)
Analysis
c,
=
A/f1
=
sample
solution
Peak
area
of component /
Peak
area
of component i in the calibration solution (standard)
c,:
Concentration of component
c, St:
Concentration of component i in the calibration solution
=
c,
*
m
i
in the
solution
(standard)
(3)
F,:
Molar flow rate of component i
c,:
Concentration of component i
V:
Volumetric flow rate
yield and selectivity of reaction products
following equations:
Experimental
sample
V
The conversion of diol,
the
the
A,:
A, Sl:
F,
by
(2)
(A1*c1,St)/A,,St
were
determined
53
XA
=
Molar flow rate of diol A (reactant) at reactor inlet
Molar flow rate of diol A (reactant) at reactor outlet
=
YB:
FB:
FA0:
SB
SB:
(4)
Conversion of diol A
XA:
FA0:
FA:
YB
(FA0-FA)/FA0
=
FB/FA0
(5)
Yield of product amine B
Molar flow rate of product amine B at reactor outlet
Molar flow rate of diol A (reactant) at reactor inlet
YB/XA
Selectivity
(6)
to the
product
amine B
Experimental
Leer
-
Vide
-
Empty
3
Cobalt-Catalyzed
Effects of
Amination of
1,3-Propanediol:
Catalyst Promotion
Supercritical Ammonia
as
and Use of
Solvent and Reactant
3.1 Introduction
Amination of
aliphatic
alcohols for the
industrially relevant process.
synthesis
Numerous examples with
found in reviews and books
by
solid acids
In
studies
(mainly
comparison
on
are scarce
zeolites and
reports
and
mainly presented
reactions. A
amines is
an
good to high yields can be
on
such
as
nickel, cobalt and copper,
phosphates).
the amination of
the transformation of diols to the
available in patents
was
to
aliphatic
[1-12]. The reaction is catalyzed by metal
hydrogenation-dehydrogenation type catalysts
and
of
simple aliphatic alcohols,
corresponding acyclic primary amines
in the patent literature
provides only little insight
[13-18].The information
into this type of amination
typical example is the amination of 1,3-propanediol
with
NH3, which
chosen to illustrate the application range of a nickel-rhenium catalyst [ 17,18].
There
are no
data available
conversion (45 %) estimated
Amination of
complex
process
a
concerning
on
consists
alcohol
of
hydrogénation steps (Scheme 1 ) [ 12,19].
catalyzed by the metal,
product composition, except
the
the basis of water formed.
simple aliphatic
which
the
over a
metal
dehydrogenation,
catalyst is already
condensation
a
and
The first and the last redox processes are
while the reaction of the intermediate
carbonyl compound
56
with
can
NH3 or an amine
be accelerated
product amine
from the
by
form
imine
an
acid/base
or
enamine does not
catalysis [12, 20].
the
require a catalyst,
but
Each intermediate and the
take part in various side reactions. The
corresponding diol requires
multiplies
and
can
to
synthesis of a diamine
repetition of the three major steps which
the likelihood of undesired side reactions,
including oligomerization
cyclization [21-23].
-H2
2-~
R-CH2-OH
R-CHO
R-ÇH-NH,
OH
/-H20
R-CH2-NH2
*Ü-
R-CH=NH
Scheme 1
A further complication in the
amines
significantly
are
illustrated
by
more
corresponding
provides
a
compared
at
This effect may be
using NH3, only
atmospheric pressure and
23 %
1,6-
[16]. Amination with
195 °C,
affording
51 %
diamine [24].
application of supercritical ammonia (scNH3) as a solvent and reactant
remarkable
to the
selectivity improvement in the amination
performance
applying subcritical
pressures
of the
as
same
shown in
The aim of the work described in this
in this
NH3.
obtained at 220 °C and 300 bar
was
dimethylamine ran smoothly
The
reactive than the reagent
the amination of 1,6-hexanediol. When
diaminohexane
of the
synthesis of primary amines is that the product
demanding type
controlling
the
of aliphatic diols,
catalyst under similar conditions, but
Chapter
5
[25].
chapter was to obtain a deeper insight
of amination reaction and reveal the role of
catalyst
in
product distribution. From economic and environmental points of
Cobalt-Catalyzed Amination ofl,3-Propanediol
57
views, the direct synthesis of aliphatic diamines from diols and NH3 would be
attractive alternative to the
3.2
an
presently applied methods [3,26,27].
Experimental
3.2.1 Materials
1,3-Propanediol (>
97 %,
Fluka), 3-amino-l-propanol (> 98 %, Huka), NH3
(99.98 %, Pan-Gas), H2 (99.999 %, Pan-Gas) and N2 (99.995 %„ Pan-Gas)
used without further
Table 1 :
Preparation
were
purification.
of various cobalt based
Catalyst
Metal content
Co
Co (100)
Co-La
Co
(88),
Co-Fe
Co
(95), Fe (5)
La
(wt%)a
(12)
catalysts.
Precursors
(mmol)
Reduction temp.,
Co(N03)2-6 H20 (172)
335
Co(N03)2-6H20(171)
La(N03)3-6 H20 (9.2)
335
Co(N03)2-6 H20 (171)
335
[°C]
Fe(N03)3-9 H20 (9.2)
Co-Fe-48
Co (52), Fe
Co-Fe-PQ,
Co
(48)
(95), Fe (5)
b
Co(N03)2-6 H20 (171)
Fe(N03)3-9 H20 (9.2)
340
Co(N03)2-6H20(171)
420
Fe(N03)3-9 H20 (9.2)
(NH4)2HP04c
Co-Fe-Na
Co (95), Fe
(5)b
Co(N03)2-6H20(171)
Fe(N03)3-9 H20 (9.2)
335
NaOAcc
a
determined
b
PO,,3' and Na+ contents were minor, for surface composition see Table 3.
"precipitate" was treated with aqueous (NH4)2HP04 or NaOAc solutions before
drying and calcination
c
by
ICP-AES
bulk
Co-Fe catalyst
Cobalt-Catalyzed Amination of J, 3-Propanediol
58
Important properties of the various cobalt-based catalysts used are collected
in Table 1. Distilled water
a
was
applied
in all
general procedure, the metal nitrates
100 g of
an
were
containing
aqueous solution
catalyst preparations. According
reached. After 2 h
(Table 1), depending
on
hydrogen consumption
NaOAc
or
reduction with
by
rate
in order to
wet
hydrated
(NH4)2HP04
with those of the
then
of 7
pH
a
dropped
was
100 °C
for 4 h at 335
in TPR,
of the Co-Fe
their acid/base
oxide-carbonate
solution. The
carefully
420 °C
maximum
(see Table 2).
precipitate
modify
by the
-
catalyst (Table 1)
was
slurry
properties.
were
hydrogen phosphate,
For this purpose,
ca.
mixed with 100 ml 0.1 M aqueous
was
with hot water. The
mixed at 90 °C for 30
following steps
min,
identical
were
general procedure.
Catalyst Characterization
Specific
surface
pore volumes
areas
(SBET),
(Vp(N2))
mean
cylindrical pore diameters (<d,,>), and specific
determined
were
Micromeritics ASAP 2000 apparatus.
10 h at 100 °C. The surface
0.05 to 0.2,
mean
H2
treated with sodium acetate and ammonium
filtered and washed
3.2.2
temperature until
their redox behaviour characterized
Two fractions of the wet
respectively,
was
(< 10 kPa). The material was calcined in air at 400 °C for 2 h,
and activated in situ in the reactor
68 g of the
(NH4)2C03
stirring the precipitate was filtered, washed, and dried at
at reduced pressure
additionally
dissolved in 500 ml water. About
20 wt% of
to the metal nitrate solution in 1 h at room
to
assuming
cylindrical
area was
a cross
section
pore diameter
by N2 physisorption
Catalyst samples
were
at 77 K
first
using
degassed
a
for
calculated in the relative pressure range of
area
was
of 0.162
mm2 for the N2 molecule. The
determined using the relation <dp>
4Vp(N2/c>BET.
Cobalt-Catalyzed Amination of 1,3-Propanediol
=
59
X-ray diffraction patterns were obtained on a Siemens D5000 powder X-ray
diffractometer using the
CuKa radiation (35 mA, 35 mV, Ni-filter).
XPS measurements
were
performed with
Leybold Hearaeus LHS11
a
apparatus using Mg Ka radiation. The work function of the spectrometer
that the Au
so
pressed
were
f7/2 line for metallic gold was
sample holder, evacuated in
on a
transferred into the UHV chamber for
were
used.
an
as
Slight sample charging
of NH3
A
quadrupol
the gas
were
mass
sample injection
Pass
corrected
using
charging
was
energies
sample films
subsequently
of 151 and 63 V
the C Is line at 284.6 eV
estimated
by varying
the
analyser.
using the pulse thermal analysis technique
valve
equipped with
spectrometer QMG 420 (Balzers)
composition.
injected
studied
load lock and
analyser STA 409 [28, 29]. NH3 pulses
Netzsch thermal
valco dual external
was
a
analysis.
tubus in the lens system of the
Adsorption
on a
was
internal standard. Differential
potential of a
located at 84.0 eV. Thin
was set
two 1 ml
injected by
After calcination and reduction of the
a
sample loops.
used for the
was
analysis of
catalyst, NH3 pulses
min"1,
into the He carrier gas flow of 50 ml
were
under isothermal
conditions.
The
profiles.
same
80 mg
thermal
analyser system
catalyst was
heated in
a
was
used for
flow of 10 %
H2
determining
in He, at
a
the TPR
heating
rate
of 5 K min"1. The formation of water (product of catalyst reduction) was monitored
by
MS. For
investigating
prereduced in H2
a
heating rate
in
a
decomposition
of
NH3,
60 mg Co-Fe
preceding cycle, was heated in a flow
of 10 K
The chemical
the
of 10 %
NH3
catalyst,
in He at
min"1.
composition
of the
catalysts
was
determined by ICP-AES
using an IRIS ICP-AES Spectrometer (Thermo Jarell Ash) in an inductive coupled
Ar
plasma chamber.
The DRIFT spectroscopic measurements were carried out on aPerkin-Elmer
Cobalt-Catalyzed Amination of1,3-Propanediol
60
2000 FT-IR spectrometer. A KBr
(100
scans
with
a
physisorbed
water.
temperature
as
sample
to 250 °C. After
in
after
heating
catalyst was pretreated
Subsequently,
applied
spectrum of the
cm"1)
resolution of 1
flow of 15 ml min'1. The
background spectrum
before the
sample
catalytic
recorded at 50 °C
sample
for 1 h in
an
Ar
at 300 °C for 1 h in Ar to remove
was
tests
reduced with
H2
at
the
same
(see above). The background
recorded in Ar at temperature steps of 50 °C from 50
was
cooling
the
the
was
to 50
°C, the catalyst
was
flushed with
NH3 (3600 ppm
Ar, 50 ml min"1) for 20 min. Spectra were recorded at temperature steps of 50 °C
from 50 °C to 250 °C.
Catalytic Amination
3.2.3
The apparatus consisted
essentially
pressure fixed-bed reactor and
of
a
temperature
in the reaction
center of the tube and
was set
were
standard conditions used
were:
40 000 gs
mol"1; molar ratio
dosing system
for the reactants,
measured
a
by
a
thermocouple
located in the
PID cascade controller. The total
by a Tescom back pressure regulator. Liquid
dosed with
8.0 g
syringe
pumps
(ISCO D500). The
catalyst; 195 °C, 135 bar,
contact time:
of propanediol/NH3/H2: 1/60/2.
Conversion, selectivity and yield (conversion times selectivity)
determined
1701
by GC analysis
of the
capillary column). Products
of the
analysis
A 50 ml
see
high
a
inner diameter and 38 ml volume. The
regulated by
was
1,3-propanediol
and
mm
zone was
pressure in the reactor system
NH3
a
gas/ liquid separator. The reactor was constructed
Inconel®-718 tubing of 13
an
of
were
liquid products (HP-5890A, FID detector;
were
identified
HP-
by GC-MS analysis (for details
Chapter 2).
high
pressure
reaction mixture was in the
quartz cell
was
used to
investigate
whether the
supercritical state. The experiment was performed with
Cobalt-Catalyzed Amination of 1,3-Propanediol
61
a
mixture
consisting of propanediol/NH3/H2
inspection of the phase
of
a
at a
molar ratio of 1/60/2. Visual
behaviour at 130 bar and 200 °C confirmed the existence
substantially homogeneous supercritical phase.
NH3
Tc
are
=
132.4 °C and
Pc
114.8 bar,
=
Note that
Tc
and
Pc
of pure
respectively [30].
3.3 Results
Catalyst Characterization
3.3.1
3.3.1.1
Textural Properties and Surface Composition
important properties
Some
of
the
Co-based
physisorption,
TPR and XRD methods,
catalysts
poorly crystalline. During
were
volume decreased considerably,
as
are
of the Calcined Catalysts
catalysts,
obtained
by N2
summarized in Table 2. All uncalcined
calcination the surface
area
and pore
emerges from the comparison of Co-Fe and Co-
Fe*. The unsupported materials after calcination possessed relatively high surface
areas
up to 133
m2g "'.
considerably the
treatments
Addition of Fe
La to Co
or
as a
second component changed
pore volume, pore diameter and surface
of Co-Fe after
precipitation
and before
drying
hydrogen phosphate (Co-Fe-P04) or sodium acetate(Co-Fe-Na)
influence
on
the textural
the calcined
oxides, mainly Co304. The CoO phase
XPS
and P,
identified
or
catalysts
on
was
had
a
remarkable
absent after addition of 5 wt% La
or
(NH4)2HP04.
the surface of the modified Co-Fe
by the peak at
with ammonium
showed the presence of cobalt
analysis of Co-Fe-Na and Co-Fe-P04 confirmed
respectively,
Similarly,
properties.
X-ray patterns of
treatments with NaOAc
area.
1071.1 eV
the existence of Na
catalysts. Sodium
(Na Is) and phosphorus by the signal
was
at 132.5
Cobalt-Catalyzed Amination of 1,3-Propanediol
62
eV
(P 2p) which is indicative for phosphate [31]. The 2p3/2 line of cobalt
found at
Only
a
energy of 780 1 eV, consistent with
binding
weak
shake-up
satellites for the
Co(III) The Fe 2p3/2 line
or
Co203 [32, 33].
2p3/2 line indicated mostly diamagnetic
characteristic of Fe304
at 710.5 eV is
Table 2: Structural properties of the Co-based
and XRD
Co304
was
catalysts
determined
or
Fe203 [33].
by N2-physisorption, TPR
analysis
Catalyst
C
Calcination
a
°BET
b
V
<dp>c
vp> N2
d
rr
XTPR
Phases detected
by
XRD
[°C]
Kg1]
[cm3g']
[nm]
[°C]
Co
400
54
0 34
21
338
CoO(12),Co304(22)
Co-La
400
37
0 43
34
356
Co304 (16)
108
0 58
14
Co-Fe*
-
(crystallite
size in
nm)e
poorly crystalline
-
CoO (25),
Co304 (22)
Co-Fe
400
35
031
29
383
Co-Fe"
400
12
010
43
-
Co-Fe*"
400
6
0 02
15
Co-Fe-48
400
68
0 15
7
401
poorly crystalline
17
492
Co304(13)
23
397
Co304(16)
Co-Fe-P04
400
133
0 67
Co-Fe-Na
400
91
06
ß-Co(31)
ß-Co(31)
-
desorption pore volume,c mean pore diameter <dp> 4
Vp N2/SBET,d temperature of maximum hydrogen consumption,e mean crystallite size determined
after amination
calcined and reduced,
by XRD line broadening, without calcination,
*
BET surface area,
BJH cumulative
=
*"
"
*
reaction
Table 3: Surface composition (in
atom-%)
of
some
Co-Fe
catalysts, determined by
XPS
Element
(Sensitivity factor)
Catalyst
Co2p
Fe
2p
(3 8)
(3 0)
Co-Fe
45 2
45
Co-Fe-Na
45 4
25
Co-Fe-P04
44 5
23
Cobalt-Catalyzed Amination of 1,3-Propanedwl
Na Is
(2 3)
P2p
(0 39)
27
57
63
The surface composition was estimated by integrating the XPS
different elements,
are
sensitivity factors [34].
The results
listed in Table 3. The relative abundance of iron to cobalt at the surface of the
Co-Fe
see
determined
using formerly
signals of the
catalyst was almost twice as much as in the bulk (determined by ICP-AES,
Table 1). The materials treated with sodium acetate
phosphate exhibited
about the
3.3.1.2 Characteristics
Amination of alcohols
The calcined
Co-based
acidic
or
examples
were
mono-
are
over
metal
can
prereduced
and bimetallic
basic salts
were
shown in
Co/Fe ratio
at
ammonium
the surface
as
hydrogen
in the bulk.
of the Reduced Catalysts
catalysts, which
active materials,
same
or
catalysts is catalyzed by the surface M°
only be
in situ before
catalysts,
studied
considered
use.
as
sites.
"precursors"
of the real
reducibility
of various
The
and the influence of treatments with
by temperature programmed
reduction. Three
Fig. 1.
Co-Fe
Co-Fe-PO,
c
<D
O)
2
a
>.
Temperature, [°C]
Figure
1:
Temperature programmed
Conditions: 10 % H2 in He,
heating
reduction of Co-Fe,
rate 5°
C
min"1,
Co-Fe-P04
and Co-Fe-Na
gas flow rate 50 ml
catalysts.
min"1.
Cobalt-Catalyzed Amination of 1,3-Propanediol
64
The
shape
of the reduction
obtained for the calcined
during
curves
of Co-Fe and Co-Fe-Na
sample containing only
reduction indicated that the two
Co via CoO
Co. The
similar to that
are
weight
loss observed
peaks represent the reduction of Co304 to
[35]. Reduction of Co-Fe-P04 (and also Co-Fe-48) occurred in three
steps. The maxima of the biggest peaks of all catalysts
are
shown in Table 2. TPR
confirmed that temperatures listed in Table
measurements
prereduction before amination
were
for
1
catalyst
sufficiently high to complete the reduction of
oxides to metals.
In additional sets of TPR
as a
to
reducing agent.
experiments, NH3 (10
The reduction started above 250 °C and all
higher temperatures, compared
to
with Co-Fe the maximum of the TPR
experiment
vol-% in
with Co-Fe
was
repeated
the
runs
H2
where
signal was
with the
was
was
applied
peaks were shifted
used. For
example,
shifted from 383 to 470 °C. The
prereduced catalyst
range where the metals
unambiguously the temperature
He)
are
to
determine
active in
NH3
decomposition. This reaction, indicated by the formation of H2, was observed only
from 250 °C
on.
Therefore, decomposition of NH3
catalytic amination of propanediol
The
phase composition
reaction is shown in
consisted of
Fig.
hexagonal
at or
below 210 °C
of Co after
packed
a
side reaction
(see later)
prereduction
2. After reduction with
closed
as
H2
can
during
be excluded.
and after the amination
at
335 °C, the
a-Co and face centered cubic
catalyst
ß-Co (Fig.
2/a). At moderate temperatures ß-Co is metastable, which fact explains the growth
of the main reflexion of the a-Co
reaction
(at 150
ascertained the
and
-
210 °C for 12
importance of the
ß phases. Only ß-Co
sluggish
transition from
a-
was
to
phase
at 47.5
°
hours). Previous XRD-studies
reduction temperature in the
generated by H2
ß-
(Fig. 2/b) during
Co
was
the amination
on
Co
catalysts
development
reduction at 400 °C
of a
[36]. The
observed between 340 and 380 °C [37].
Cobalt-Catalyzed Amination of1,3-Propanediol
65
ß-Co
H
•"—
*
+
o-Co
+
(Wairauite)
i
d)
..M—-
c)
l
ill
Il
i.
(4,.*
(}.*
Jt
b)l
LjdL
*
*,m
—
*
Jj
a)
'—'
CoFe
—i—'—i——i—'—i——i——i—'—'
'
1
1
r—
1
1
1
1
1
-i1
40
50
60
80
70
100
90
28,11
Figure 2: X-ray diffraction patterns of Co (a), Co-Fe (c) and Co-Fe-48 (d), after calcination
reduction, and Co (b) after
Patterns
c
use
and d in
and
in animation.
2 illustrate the influence of Fe additive
Fig.
on
the
phase
composition of the reduced catalysts. Interestingly, only ß-Co was detectable when
the
catalyst containing
5 wt% Fe
(Co-Fe)
was
reduced at 335 °C. At this
temperature the formation of the a-Co phase is expected [37]. Apparently, the
presence of Fe favoured the formation of the metastable
restructuring during
was
the amination reaction
still present after
use at
150
-
was
210 °C for 10
ß-Co phase. Moreover,
suppressed
days (not
and the
shown in
ß-Co phase
Fig. 2).
in reduced Co-Fe remained unaffected
The
during
the
average size of Co
crystallites
amination reaction
(see Co-Fe" and Co-Fe*" in Table 2). Similarly, addition of 5
wt% La to Co
prevented the restructuring of Co during amination; these results are
not shown here. These
experimental observations
small amount of Fe
effect of
a
48 wt%
(Co-Fe-48) resulted
or
La additive.
in the
-
reflect the excellent
stabilizing
An increase of the iron content to
development
of
a new
phase,
a
CoFe-alloy
(Wairauite) during reduction by H2.
Cobalt-Catalyzed Amination of 1,3-Propanediol
66
ß-Co
«i*
*-
*
a-Co
1
Co-Fe-PO,
ft
Co-Fe-Na
*
1
LuAumM.,.,
^->**OiiW|mJ.
Co-Fe
l-l
1
1
1
1
1
r
1
-r
40
1—-I
.
«
1
1
50
2 e,
Figure 3: X-ray diffraction patterns
of Co-Fe,
i
1
r-1
1
60
[ °]
Co-Fe-P04
and Co-Fe-Na, after calcination and
reduction.
A
partly
different
treated with basic
or
picture
was
obtained in the
study
of Co-Fe
acidic salts. The XRD patterns of Co-Fe-Na
°C) and Co-Fe-P04 (reduced
at 440
(reduced
animation
3.3.1.3
were
not
at 335
°C), disclosed the presence of both cobalt
phases, though the amount of a-Co was very small in Co-Fe-Na (Fig. 3).
changes during
catalysts
observed for any of these two
Structural
catalysts.
Adsorption ofAmmonia
Pulse thermal
analysis (PTA)
was
used for the
quantitative study
of
NH3
physisorption and chemisorption. This method provides correct, undistorted values
by following
the
data measured
50 °C
are
weight change during adsorption
on
the reduced
samples
of Co-Fe,
collected in Table 4. The amount of
small and it
was
and
desorption [28, 29].
Co-Fe-P04
Cobalt-Catalyzed Amination of1,3-Propanediol
and Co-Fe-Na at
NH3 physisorbed
completely removed by the He carrier gas
The
on
Co-Fe
was
within 5 min. Besides,
67
no
chemisorbed
earlier that the
NH3 could be detected. A combined UPS and XPS study revealed
of NH3
adsorption
Co-Fe-P04
was
the
on
Co is very weak at
only catalyst
occurred between 75 and 250 °C, with
of
NH3
is
a
a
which chemisorbed
maximum
The enhanced
for
capacity
NH3.
rate at 170 °C.
clear indication for acidic sites introduced
(NH4)2HP04.
temperature [38].
room
by the
physisorbed NH3
Its
desorption
Chemisorption
treatment with
of this
catalyst
may
simply be attributed to the higher surface area, as compared to the untreated Co-Fe
On the other hand, neither physisorption,
catalyst (Table 4).
NH3
could be detected
Table 4: Ammonia
BET surface
areas.
on
Co-Fe-Na,
as
expected
chemisorption of
nor
for this base-treated material.
adsorption determined by pulse thermal analysis at 50 °C, together with the
Both measurements
Catalyst
were
carried out
catalysts prereduced by H7.
on
Physisorption
Chemisorption
SBET
[cm3 g']
[cm3 g']
[mV]
Co-Fe
0.4
0
12
Co-Fe-P04
0.8
1.5
31
Co-Fe-Na
0
0
6
To
our
adsorption
NH3
knowledge,
on
adsorbed
no
report has appeared yet
Co. Due to the lack of
on
Ni and Cu
a
catalysts
on
the DRIFT
study
of NH3
reference spectrum, the DRIFT spectra of
were
used to allocate the
adsorption bands
[39-41]. Figure 4 shows the spectra of NH3 chemisorbed on the prereduced Co-FeP04 catalyst
at
different temperatures. Adsorbed
250 °C. Vibrations at 1240
(5S NH3, SK NH3).
cm"1 and 1610 cm"1
are
NH3
could be detected up to
ascribed to Lewis acid centers
The weaker deformation mode at 1423 cm"1 is attributed to
Br0nsted populations (5^ NH4+). The weak 6S NH4+ around 1670 cm"1 could
clearly
identified. A
multiplet
was
observed
in the NH
not be
stretching region
(3352 cm"1,3258 cm"1,3216 cm"1,3165 cm"1) which is assigned to the asymmetric
and
symmetric
vN-H and to the first overtone of
28as NH3
vibrations
[42]. The
Cobalt-Catalyzed Amination of 1,3-Propanediol
68
reverse
adsorption signal
hydroxyl
groups
on
the
at 3668 cm
'
catalyst surface,
indicates
because
a
decrease of the amount of
NH3
was
adsorbed
on
Br0nsted
sites.
With
increasing temperature NH3 desorbed
decreased. No chemisorbed
intensity of the signals
surface of Co-Fe and Co-Fe-Na
catalysts,
from the surface and the
could be detected
NH3
on
the
in agreement with the PTA experiments
(Table 4).
4000
3500
3000
2500
Wavenumber, [cm
Figure 4: DRIFT-spectra
temperatures,
spectrum
3.3.2
carrier
min
'
ammonia on
1500
1000
']
the reduced
Co-Fe-P04 catalyst at
different
Ar, spectra, obtained after subtraction of the background
shown
are
Catalytic Amination
3 3 2 1
Choice
Screening
of Catalyst
of several
revealed that
of
of adsorbed
gas 50 ml
2000
supported
only Co-,
1,3-propanediol.
and
unsupported
Ni- and Cu-based
Ru/C and Pd/C
were
metal
catalysts
catalysts in
were
autoclave
useful for the amination
active but unselective.
Cobalt-Catalyzed Animation of 1,3-Propanedwl
an
69
A parameter
study
promising catalysts Co,
H2 in the
feed
was
carried
Co-La and Co-Fe. It
(1-5 mol %)
For the
comparison
was
set to 135 bar and the
that
NH3 forms
[30]).
a
rather
A
oligomerization
Table 5:
was
a
small
most
proportion of
prevent the undesired
of
excess
Tc
NH3
the pressure
=
132.4 °C and
was
Pc
employed
=
to
114.8 bar
minimize
products.
amination of
tests for the
catalysts
varied between 190 and 210 °C. Note
at above
of the intermediates and
Catalyst screening
to
of Co, Co-Fe and Co-La
temperature
molar
found that
the
to the formation of nitriles and carbonaceous
supercritical fluid
high
was
sufficient
was
dehydrogenation reactions leading
deposit [43].
out in the fixed-bed reactor with
1,3-propanediol.
Conditions: 135 bar,
contact time 60 000 gs mol "',
Catalyst
Selectivity, [%]
Conversion
Aminol (3) Diamine
[°C]
diol/NH3/H2
[%]
Co"
210
1/20/2
90
6
11
Co"
210
1/20/2
58
26
21
Co"
195
1/60/2
98
5
12
Co-La
190
1/20/2
36
31
12
Co-La
210
1/20/2
80
12
11
Co-La
210
1/60/2
98
5
23
Co-Fe
210
1/20/2
94
0
11
Co-Fe
195
1/60/2
95
9
34
Co-Fe-48c
195
1/60/2
42
14
7
"
195
1/60/2
<3
<3
Co-Fe-48
"
molar ratio
Temp.
Values
stream;
were
c
determined after 3 h time
Contact time: 40 000 gs
on
mol"1;
d
stream;
96
b
Values
confirmed
Some
by separate experiments
representative
data
determined after 12 h time
on
Contact time: 100 000 gs mol"1.
The existence of a substantially homogeneous
was
were
illustrating
in
the
a
supercritical reaction mixture
quartz cell (see experimental part).
activity
and
selectivity of Co-based
Cobalt-Catalyzed Amination of 1,3-Propanediol
70
catalysts
are
stream was
listed in Table 5. A considerable deactivation within 12 h time-on-
observed with
connected with the
unpromoted
Co. It is
likely
that deactivation is
restructuring of Co, as observed by XRD (Fig. 2, patterns a and
*)•
Restructuring was negligible with bimetallic catalysts containing 5
or
La. Conversion and
tables could be
Co-Fe
were
selectivity
values
reproduced after 6-12
chosen for further
presented
in the
h time-on-stream.
wt% Fe
following figures
Accordingly,
and
Co-La and
investigations.
3.3.2.2 Product Distribution
On the basis of the
GC-MS
analysis,
propanediol
are
major components,
the
important
Beside the
aldol reaction via the
mixture, likely due
key intermediate amino alcohol
and dimerization
ß-hydroxyaldehyde
These
to
amination of 1,3-
4, various compounds have been detected which formed by
fragmentation (7,8), alkylation (9,10,14)
compounds (5 and 6).
liquid product mixture by
occurring during
reactions
depicted in Scheme 2.
3 and product diamine
identified in the
their
aldehydes
2
(11 -13). The
[21] produced reactive carbonyl
could not be detected in the
high reactivity
retro-
and
volatility.
liquid product
Their existence
was
deduced from the formation of alkylation products 9 and 10. The ratio of main and
by-products
varied
strongly with the reaction conditions, as will be
Cobalt-Catalyzed Amination of J, 3-Propanediol
shown below.
71
n
OfOH
OHDH
lH>
1
6
r^
^
^
OH
-H,0
|-H20 .H^ ^
2
+
NH,
OlOH\!
O
O
5
O
0
NH3f+H2
+H2
n
^
NH2
7
NH.
'2
9
NH2
^
.Hz0
+H2
10
-
Bifunctional
NH2
H,
n
/NH
NH2
-H20
intermediates/products
-
HO
NH
a*-
HnO
HN
H,N
HN
HNS
.OH
*^OH
l^iOH
11
Scheme 2:
dimers, oligomers,
H,N
Important
The intermediates and
^°:
Hp
OH
|-H20
3
,NH
HN
reactions
occurring
products (except 2,
in the amination of
5 and
6)
were
V,NH2
13
12
1,3-propanediol
by GC-MS.
with ammonia.
identified
Cobalt-Catalyzed Amination of 1,3-Propanediol
72
3.3.2.3
Influence ofReaction
Figures
5/a-d
propanediol
the influence of temperature
depict
and
on
Parameters
the
yields
of
some
key products
the conversion of 1,3-
on
over
Co-Fe.
Co-Fe
100-
O
Co-Fe-P04
A
0
80/
/
o
'
60-
CD
>
C
/
0/
40-
/
o
o
*'
O
A
V
20-
.-*''
o-lI
»-"."
150
|
i—
,
r
160
170
180
'
T
190
1
—i
200
1
210
Temperature, [°C]
Figure 5a: Influence of temperature on the conversion of 1,3-propanediol over Co-Fe, Co-Fe-Na
and Co-Fe-P04; standard conditions.
50
Co-Fe
g
40
.
o
Co-Fe-Na
a
Co-Fe-PO,,
"5
c
co
.30
o
0
O
\
0
/
20
I
,'
CO
t
10
0
..-5
o
o
CD
>
0
-I—$^t—i—.
150
160
„,
170
„
,
—p——r-—f-
180
190
200
Ï
-
210
Temperature, [°C]
Figure.
5b: Influence of temperature
on
the
yields of 3
standard conditions.
Cobalt-Catalyzed Amination of 1,3-Propanediol
over
Co-Fe, Co-Fe-Na and Co-Fe-P04;
73
50
Co-Fe
o
Co-Fe-Na
û
Co-Fe-PO,,
Ç-40-1
a>
c
ffl
|30
O.
O
_Ç
Ë
/
20
CO
^5
°
M
i
CO
if
io
0
0
o
tj
o
>
0
.--A—*'"
rf£-^
150
..A--'''
p^
160
170
180
190
200
210
Temperature, [°C]
Figure
5c: Influence of temperature
on
the
yields of 4
over
Co-Fe, Co-Fe-Na and Co-Fe-P04;
standard conditions.
Co-Fe
o
Co-Fe-Na
A
Co-Fe-PO,
40-
T3
o
30c
o
to
TJ
20-
2
0
en
O
o
•*—
o
'
100
a
...A''"
CD
>
4
o
CD
n
Ï
0-
—»'''
150
P-f
160
i——
170
1
180
190
1-—«
200
1
210
Temperature, [°C]
Figure 5d:
Fe-Na and
Influence of temperature on the yields of degradation products
Co-Fe-P04; standard conditions.
7-10 over Co-Fe, Co-
Cobalt-Catalyzed Amination of 1,3-Propanediol
74
The conversion of
1,3-propanediol,
via the formation of
which indicates the
in the temperature range 150-180 °C. Variation of the
diamine 4 and
degradation products
7-10 with
of the diol
order of
magnitude
by
increased
ß-hydroxyaldehyde 2,
a
consumption
an
yields
of amino alcohol 3,
temperature is typical for
a
consecutive reaction series.
The effect of total pressure
results
obtained
the
over
on
Co-La
the
product distribution
is illustrated with the
is
catalyst (Fig. 6). There
enhancement in selectivities to 3 and 4 in the range of subcritical
transition of NH3(PC
=
114.8 bar
[30]). The change in selectivity
100 bar and above 135 bar, and the variation in conversion
pressure range. It has been
reaction mixture
was
in
a
proved independently
was
remarkable
a
-
was
supercritical
minor below
small in the whole
that at 200 °C and 130 bar the
homogeneous supercritical phase.
100'
I
I Conversion
I
I Selectivity
to 3
HI Selectivity
to 4
12
o
Ü
Pressure, [bar]
Figure
210°
6: Effect of total pressure
C,
reactant molar ratio
The influence of
on
the amination of
(diol/NH/H2): 1/20/2;
NH3/diol
1,3-propanediol
contact time:
over
Co-La. Conditions:
60 000 gs
molar ratio is shown in
Fig.
mol"'.
7. The
higher
this
ratio, the higher is the conversion of diol 1, and selectivities for aminol 3 and
Cobalt-Catalyzed Amination of 1,3-Propanediol
75
is
the formation of dimers 11-13
Simultaneously,
diamine 4
illustrated
the
by
of 13 As discussed
example
was
diminished, which
the introduction, the reactivity
in
(basicity) of NH3 is markedly lower than that of the primary amines produced
This
dimenzation
and
leads
difference
reactivity
the
to
of
formation
ohgomerization products (the aldehyde intermediate
of
NH3,
(>20)
produce
a
secondary amine)
necessary to
is
primary
the
to
amines
Large
reacts with an amine, instead
molar ratio
relatively large NH3/diol
selectivities
compensate this effect and improve the
excess
aldehyde intermediate
suppresses the
A
various
of
NH3
favours also the condensation of
the
by shifting
2
equilibrium
NH3
to
with
towards the adduct, and
and NH3
disproportionation of primary amines to secondary amines
25
I
I Conversion
I
13 Amino 1
1 3 D
am
propanol (3)
nopropane (4)
Bis(3 aminopropyl)amine (13;
ü
1/60
1/40
1/20
n(diol/NH3), [molar ratio]
Figure
7.
Influence of
distribution
over
NH3/diol
molar ratio
on
the
conversion
Co La Conditions 210° C, contact time
of 1,3
propanediol and product
', otherwise standard
60 000 gs mol
conditions
Product distribution
Fig
8
Longer
contact
was
strongly affected by
times
increased the
selectivities for 3 and 4 However, the
yields
the contact time,
conversion
of these
and
as
shown
decreased
products (î
Cobalt-Catalyzed Animation of 1
in
the
e conversion
3
Propanediol
76
times
selectivity) remained almost
contact time at
a
longer
constant.
higher temperature (20 000
afforded almost identical conversions (34
improve
3 and 4
(43 %). Attempts
varying
either the temperature
100-
I
',
gs mol
210 °C,
see
or
-
36
see
a
short
or
with
Table
5)
%) and cumulative selectivities for
the diamine
yield
at
high
diol conversion
by
the contact time resulted in rather similar values.
I Conversion
f~~l Selectivity to
with
Fig. 8),
temperature (60 000 gs mol ',190 °C,
contact time at lower
to
Interestingly, working
40
3
to 4
Selectivity
-30
60
-20
VI
CD
rv i
20-
n-l
-
Imma
H
B,l
I
40000
20000
60000
50000
Contact time,
[gs
mol
80000
]
Figure 8: Effect of contact time on conversion of 1,3-propanediol (1), and selectivities for 3amino-1-propanol (3) and 1,3-diaminopropane (4), over Co-La Conditions 210° C, reactant
molar ratio (diol/NH1/H2) 1/20/2, otherwise standard conditions
3 3 2 4 Amination
of 3-Ammo-l-propanol (3)
Each intermediate and the
as
shown in Scheme 2
intermediate
product
In
a
amine
series of
3-amino-l-propanol (3)
can
take part in various side
experiments
was
Cobalt-Catalyzed Animation of 1,3'-Propanediol
reactions,
the animation of the
investigated. Starting
from
key
this
77
intermediate instead of 1, the number of necessary reaction steps
selectivity
to the
diamine 4
is
expected
Fig 9 confirm this expectation
higher
The maximal
considerably
yield
halved and the
The results shown
of 50 % to 4
was
drop
(Fig 5c)
of the diol 1
in
diamine
of degradation
yield
above 210 CC
products (see Fig
100
Sl
80-
>
60-
In both reactions,
9
as an
I
I Conversion of 3
i
1
Yield of
is
mainly
of diamine 4
^ Yield
of dimer 13
due
in
the
the amination of 1 and 3,
to
the enhanced formation
example)
degrad products
H Yield
in
in
remarkably
than the best value of 32 % achieved under similar conditions
animation
the
to rise
is
7 10
c:
|
40-
>
A
c
o
Ü
20
0
JJJfc, -a,
180
165
160
225
210
195
Temperature, [°C]
Figure
9
Influence of temperature
Conditions molar ratio
3 3 2 5
on
propanol (3)
1/40/2, otherwise standard conditions
the amination of 3-ammo 1
(alcohol/NH3/H2)
=
Catalytic Performance of Co-Fe
Treated with NaOAc
The effect of basic and acidic treatments of Co Fe
and
product distribution
is
shown
in
on
the
conversions
by 20
-
60 % achieved at 150
-
Co-Fe
(NH^flP04
propanediol
Figs 5a-d Introduction of acidic
phosphate treatment resulted in a significant deactivation
lower
or
over
conversion
sites
by the
A clear indication is the
210 °C,
as
compared
to the
Cobalt-Catalyzed Amination of 1 3-Propanediol
78
performance
3 and 4
of unmodified Co-Fe
shifted to
was
(Fig. 5a). Similarly,
higher temperatures (^210°) (Figs. 5b, c).
explanation for the observed deactivation
formed
on
the
is that
partly
-
-
metal
yields for
A
possible
phosphates were
catalyst surface during calcination, and in the amination of alcohols
phosphates require markedly higher temperatures
Treatment with NaOAc
was
then metal
catalysts [44,45].
less detrimental for the formation of the amino
alcohol intermediate, but the diamine
side
the maximum in
yield dropped above
180 °C due to various
reactions, mainly degradation (Fig. 5d).
3.4 Discussion
3.4.1
Influence ofSupercritical Ammonia
The one-step amination of
studied
Co-based
over
1,3-propanediol (1)
catalysts
supercritical medium (above
catalyst (Co-Fe) afforded
Fe
Compared
metal
work, there is
1. The
likely
no
32 % diamine
is not the
missing
in the
The
to
including
production
many
supercritical
on
interest in the
more
a
95 wt% Co-5 wt%
complete
conversion.
alcohols with
NH3
over
our
the successful amination of
product diamine,
which is
a
complexity of the process eight
-
elementary steps
-
hampers
any easy
as
reactant and
reaction medium has been found
obtaining reasonable selectivities. A change from subcritical
conditions
a
of 4.
application of scNH3
be essential for
was
[8, 46]. However, excluding
other report in the open literature
reaction steps
success
at almost
simple monofunctional
useful and versatile intermediate [3]. Rather the
major
bar). At best,
yield
this result is rather moderate
reason
1,3-diaminopropane (4)
under conditions where ammonia forms
132.4 °C and 114.8
to the amination of
catalysts,
to
by increasing
to
the total pressure almost doubled the
Cobalt-Catalyzed Amination of 1,3-Propanediol
79
selectivity to the amino alcohol intermediate 3
An
pronounced influence
even more
selective Co-Fe
of
liquid
48].
and gas
It is very
critical
catalyst [25].
phases)
likely
of pressure
The existence of a
eliminates the
that the
and diamine 4
interphase
positive changes
observed
Co-La
over
(Fig. 6).
the
more
single supercritical phase (instead
mass
transfer resistance
in amination
selectivity
in the
[47,
near
region are due to the increased surface NH3 concentration. Analysis of the
main and side reactions in Scheme 2 suggests that
favours the desired reaction series
reactions
leading
high surface NH3 concentration
4, and suppresses several side
to
including dimerization, oligomerization, disproportionation,
reaction and
aldol
reproducible yields
5 wt% Fe. La
as
no
with La and Fe
of Co
The proper choice of
remarkable:
retro
hydrogenolysis.
3.4.2 Promotion
-
was
over
catalyst
was
to 4. The best
additive
was
also
important
catalyst
was
in
achieving reasonable
developed by promoting
less efficient. The
stability
of the Co-Fe
and
Co with
catalyst
significant deactivation was observed even after 10 days use at
is
150
210 °C.
Only
the metastable
amination reaction, and
on-stream.
For
no
ß-Co phase
detectable
formed
a
few hours
-
reduction
prior
to the
restructuring occurred in several days time-
comparison, unpromoted
deactivated within
during
Co
-
which
contained both
a-
was
and
less selective and
ß-Co phases,
and the
proportion of the a-Co phase increased parallel with the loss of activity. Moreover,
both
a-
and
ß-Co phases
salts. These three
existed in Co-La, and Co-Fe treated with acidic
catalysts afforded considerably lower selectivities
4. A further increase of the iron content from 5 to 48 wt%
formation of
a
Co-Fe
alloy (Wairauite),
and also this
and
or
yields
(Co-Fe-48) led
catalyst
was
basic
to
to the
less efficient
Cobalt-Catalyzed Amination of], 3-Propanediol
80
than Co-Fe.
ß-Co phase,
metastable
be
a
Apparently,
the small amount of Fe additive
and the presence of this
key requirement for obtaining
3.4.3 Role
a
in
a
or
seems to
catalyst.
stable and selective
(NH4)2HP04
was
prior to drying and calcination with aqueous
found to be detrimental to the
broad range of reaction parameters. A feasible
catalytic performance
explanation
influence of strong acidic and basic surface sites is based
on a
the reactions shown in Scheme 2. The main reaction line
includes
in the bulk
ofSurface Basic and Acidic Sites
Treatments of the best catalyst Co-Fe
NaOAc
single phase
stabilize the
can
metal-catalyzed
redox and acid-base
catalyzed
for the
careful
leading
negative
analysis
of
from 1 to 4
condensation
(addition-
elimination) reactions. A former investigation of the animation of monofunctional
aliphatic
alcohols
[49] demonstrated that the overall reaction
the abstraction of
a-hydrogen.
an
dehydrogenation
of the alcohol to the
amination of
alkanediol
reactions, it
an
can
can
This is the first
be divided into two
to
10 and
resulting
in 7
affording
non-volatile
and
of
"independent"
preparation
-
or
amination
basic sites
4 transformation, and therefore cannot
4. On the contrary, these acidic and basic sites
accelerate the retro aldol reaction
The
elementary step during
be concluded that the presence of strong acidic
improve the selectivity
by
corresponding aldehyde. Accepting that the
cannot increase the overall rate of the 1
-
rate was limited
leading
to 5 and
can
6, the alkylation reactions
14, and dimerization and oligomerization reactions
byproducts.
conditions for Co, Co-Fe and Co-La
(choice of precursors
precipitating agent, deposition at neutral pH, etc.) were designed with the aim
minimizing
the final
the concentration of strong acidic and basic sites
catalyst.
It
was
hoped that the model catalysts
Cobalt-Catalyzed Amination of1,3-Propanediol
on
the surface of
Co-Fe-Na and
Co-Fe-P04
81
will differ from Co-Fe
will enable
us
only by the presence
of surface basic and acidic sites, and
confirm the above concept.
to
changes during preparation (adsorption
aqueous solutions, followed
Unexpectedly,
of NaOAc
by careful removal
of
or
even
(NH4)2HP04
the minor
from dilute
salts with hot water)
excess
resulted in remarkable
changes in the physico-chemical properties. The different
properties (excluding
the acid-base
illustrated in Tables 2, 3 and
performance
Figs.
of Co-Fe-Na and
"structural" effects.
Especially
of the a-Co
and the
phase
properties)
1-3. It is
of Co-Fe after modification
probable
Co-Fe-P04 (Figs. 5a-d)
in the
case
that the poor
is
partly
of Co-Fe-P04, the
partial transformation of
are
catalytic
due to these
significant
amount
surface oxide to inactive
phosphate during
calcination may also contribute to the detrimental influence of
phosphate
catalyst
on
the
surface.
3.5 Conclusion
The amination of
1,3-propanediol
with ammonia
fixed-bed reactor in the temperature range 150
was
-
carried out in
210 °C and
a
a
continuous
total pressure
ranging from 50-150 bar. Promotion of the unsupported cobalt catalyst with iron
and
lanthanum, respectively, improved the diamine selectivity compared
pure cobalt
wt% Fe
cobalt
catalyst.
Best
catalytic
results
were
obtained with
catalyst, containing only very weak acidic sites.
phase tends
to transform to the
to the
95 wt% Co
a
-
The active metastable
thermodynamically
more
5
ß-
stable a-cobalt
phase under reaction conditions Addition of small amount of iron suppresses
this
transformation providing stable cobalt catalysts. The absence of strong acidic and
basic sites
on
the
catalyst was found to be crucial for favoured diamine production
due to the various undesired side reactions (retro-aldol reaction,
hydrogenolysis,
alkylation, disproportionation, dimerization and oligomerization) occurring in the
Cobalt-Catalyzed Amination of], 3-Propanediol
82
reaction system. The
to
use
of supercritical ammonia
be beneficial for both amino alcohol
selectivity
enhancement at the
elimination
of
the
near
interfacial
as
critical
mass
as
well
region
transfer
solvent and reactant proved
diamine formation. This
as
is
likely
leading
to be caused
to
higher
by
the
ammonia
concentration.
The
feasibility
propanediol
in
of
a
one-step synthesis of 1,3-diaminopropane from 1,3-
supercritical
ammonia has been demonstrated.
large number of elementary steps involved
best
yield of
alcohol
are
attractive values. The excellent stability of the best Co-Fe
process. However,
to
in this consecutive reaction
the
series, the
32 % for the diamine and 8 % for the valuable intermediate amino
significant deactivation up to
required
Considering
achieve
a
10
days on stream
substantial further
yields
-
is also
improvement
useful for technical
Cobalt-Catalyzed Amination of 1,3-Propanediol
a
of
catalyst
-
no
promising feature of the
catalyst composition
application.
is
83
3.6 References
[I]
Glaser, H., in: Methoden der Org. Chem. (Houben-Weyl), Vol. XVI, ed. E. Müller
(Georg Thieme, Stuttgart 1957) p. 112.
[2]
Herman, R. G., in: Catalytic Conversion of Synthesis Gas and Alcohols to Chemicals, ed.
R. G. Herman (Plenum Press, New York, London, Bethlehem 1984) p. 433.
Heilen Mercker, H. J., Frank, D., Reck, R. A. and Jackh, R., in: Ullmann's Encycl. Ind.
[3]
Chem., Vol. A2, eds. B. Elvers, S. Hawkins, M. Ravenscroft, J. F. Rounsaville and G.
Schulz
[4]
[5]
(Chemie, Weinheim 1985)
p. 23.
Baiker, A. and Kijenski, J., Catal. Rev. Sei. Eng. 27, 653 (1985).
Vogt, P. F. and Gerulis, J. J., in: Ullmann's Encycl. Ind. Chem., Vol. A2, eds. B. Elvers,
S. Hawkins, M. Ravenscroft, J. F. Rounsaville and G. Schulz (Chemie, Weinheim 1985)
p. 37.
[6]
[7]
[8]
[9]
[10]
[II]
[12]
Deeba, M., Ford, M. E. and Johnson,
T. A., in:
Catalysis of Organic Reactions,
Vol. 40,
ed. D. W. Blackburn (Marcel Dekker, New York 1990) p. 241.
Roundhill, D. M., Chem. Rev. 92,1 (1992).
Turcotte, M. G. and Johnson, T. A., in: Kirk-Othmer, Encycl. Chem. Technol., Vol. 2,
eds. F. M. Mark, D. F. Othmer, C. G. Overberger and G. T. Seaborg (Wiley, New York
1992) p. 369.
Visek, K„ in: Kirk-Othmer, Encycl. Chem. Technol., Vol. 2, eds. F. M. Mark, D. F.
Othmer, C. G. Overberger and G. T. Seaborg (Wiley, New York 1992) p. 405.
Amini, B., in: Kirk-Othmer, Encycl. Chem. Technol., Vol. 2, eds. F. M. Mark, D. F.
Othmer, C. G. Overberger and G. T. Seaborg (Wiley, New York 1992) p. 426.
Baiker, A., in: Catalysis of Organic Reactions, Vol. 53, eds. J. R. Kosak and T.
Johnson (Marcel Dekker, New York 1994) p. 91.
A.
[19]
Mallat, T. and Baiker, A., in: Handbook of Heterogeneous Catalysis, Vol. 5, eds. G. Ertl,
Knözinger and J. Weitkamp (VCH Verlagsgesellschaft, Weinheim 1997) p. 2334.
Schreyer, R., US Patent 2 754 330 (1952).
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[20]
March, J., Advanced Organic Chemistry Reactions, Mechanisms, and Structure (Wiley,
H.
[13]
[14]
[15]
[16]
[17]
[18]
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New York
[21]
[22]
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[24]
[25]
[26]
[27]
1992)
p. 898.
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Vultier, R. E., Baiker, A. and Wokaun, A., Appl. Catal. 30,167 (1987).
Fischer, A., Mallat, T. and Baiker, A., Angew. Chem. Int. Ed., in press (1998).
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M. Ravenscroft, J. F. Rounsavielle and G. Schulz (Chemie, Weinheim 1985) p. 629.
Carter, G. C, Doumaux, A. R., Kaiser, S. W. and Umberger, P. R., in: Kirk-Othmer,
Encycl. Chem. Technol., Vol. 8, eds. F. M. Mark, D. F. Othmer, C. G. Overberger and
Cobalt-Catalyzed Amination of1,3 -Propanediol
84
G T
[28]
Seaborg (Wiley, New
Maciejewski, M Müller,
,
York
C
1992) p 74
A, Tschan, R, Emmerich, W
D
and Baiker, A,
Thermochim Acta295, 167(1997)
[29]
Maciejewski,
M
,
Emmerich, W D and Baiker, A
,
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(1998)
[30]
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Encyclopédie
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Amsterdam
1976)
p
951
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Pelavin, M
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Deviney and J L Gland (ASC, Washington 1985) p 144
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Metal Oxides,
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m
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,
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W and
Holstein, W L
(1983)
Cobalt-Catalyzed Aminatwn ofl 3-Propanedwl
,
Ind
Eng Chem Prod
Res Dev 22, 217
4
Nickel-Catalyzed Amination
of
1,3-Propanediols:
Influence of Reactant Structure
4.1 Introduction
The
metal-catalyzed
interesting pathway
selectivities
are
corresponding
The
amination of
to a
aliphatic alcohols provides
in the
synthesis
of aliphatic diamines from the
diols and ammonia.
metal-catalyzed synthesis of aliphatic amines
alcohol includes the
dehydrogenation of the alcohol to
condensation with ammonia to form
to
[1-4]. However, the yields and
multitude of amines
usually rather low
economically
an
an
imine
or
the amine [5, 6]. Each intermediate and the
various side reactions, such
as
a
from the
corresponding
carbonyl compound;
the
enamine, and the hydrogénation
product
amine
can
take part in
condensation, decarbonylation, disproportionation
and hydrogenolysis [7-10]. The synthesis of a diamine from the corresponding diol
requires the repetition of all three steps which increases the by-product formation.
In
addition, the bifunctional intermediates have the tendency
oligomerization reactions [4,11,12].
and
product
The
amines
are
difficulty is
undergo
that the intermediate
reactive than ammonia.
ammonia
(scNH3)
as a
solvent and reactant
selectivity improvement in the amination of 2,2-dimethyl-1,3-
propanediol, compared
5
more
application of supercritical
affords remarkable
Chapter
significantly
A further
to
to the
[13]. Here the studies
subcritical pressure
on
amination with
procedure
scNH3
to
as
described in
structurally related
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
86
1,3-propanediols were extended. The nickel-catalyzed amination of 2,2-dimethyl1,3-propanediol, 2-methyl-1,3-propanediol and 1,3-propanediol is compared. The
aim is to
gain
a
better
understanding
the reactant diol and the amination
4.2
of the
relationship between
the structure of
selectivity.
Experimental
A commercial
silica-supported
56 wt% nickel
was
used. The
catalyst (Ni-6458, Engelhard) containing
nickel
catalyst
was
reduced and stabilized form. Before the
hydrogen flowing
The
at
>
98 %
purities
reactant
The
specific surface
pore volume
physisorption
at 77 K
measurements, the
section
were
quoted by
the manufacturer: 1,3-
%
>
99 %
(Aldrich), 2,2-
(Fluka), ammonia 99.98 %(Pan-Gas), hydrogen
area
(SBET),
of the
(Vp(N2))
using
mean
a
cylindrical
catalyst
pore diameter
determined
were
catalyst sample
of 0.162 mm2 for the
was
determined
using
(<dp>) and
by nitrogen
Micromeritics ASAP 2000 apparatus. Before
was
degassed
for 10 h at 150 °C. The surface
calculated in the relative pressure range of 0.05 to 0.2,
area
diameter
catalyst was activated in
(Pan-Gas) and nitrogen 99.995 % (Pan-Gas).
99.999 %
area was
a
the
experiments,
(Fluka), 2-methyl-1,3-propanediol
dimethyl-1,3-propanediol > 98
specific
from the manufacturer in
30 ml min'1 for 4 h at 250 °C.
following
propanediol
supplied
nitrogen molecule.
the
equation <dp>
=
The
assuming
mean
a cross
cylindrical
pore
4Vp(N2/SBET.
X-ray diffraction patterns were measured on a Siemens D5000 powder X-ray
diffractometer using CuKa-radiation (35 mA, 35 mV, Ni-filter). The diffractograms
were
compared to JCPDS data files [ 14] for catalyst phase identification. The mean
nickel
crystallite
size
Adsorption
was
estimated
of ammonia
was
using
the Scherrer
studied
applying
equation [15].
the
pulse thermal analysis
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
87
(PTA) technique on a Netzsch thermal analyser STA 409 coupled with a quadrupol
mass
spectrometer QMG 420 (Balzers). Ammonia pulses
dual external
sample injection
catalyst activation,
carrier gas
was
ammonia pulses
equipped with
were
are
-
two 1 ml
injected by a valco
sample loops. After
injected at 50 °C. The flow rate of the He
50 ml min'1. Details about the
the TPA method
DRIFT
valve
were
experimental setup
and
principle of
reported elsewhere [16, 17].
spectroscopic
measurements
of ammonia
adsorption
were
performed on a Perkin-EImer 2000 FT-IR-spectrometer. Preliminary, a potassium
bromide
background spectrum
catalyst was pretreated at 300 °C for 1
h in
physisorbed
was
Subsequently,
water.
(100
recorded at 50 °C
was
it
an
scans, 1
cm"1).
argon flow of 15 ml min"1 to
activated with
hydrogen
The
remove
at 250
°C,
similarly as before catalytic tests. Then the background spectra of the samples were
recorded in argon at temperature steps of 50 °C from 50 °C to 250 °C. After
cooling
to
50 °C, the
catalyst
was
exposed
flowing
to ammonia
at 50 ml
min"'
(3600 ppm in Ar) for 20 min. Finally, the catalyst was heated and the spectra were
recorded at 50 °C
to
250 °C, in steps of 50 °C.
The apparatus for
catalytic
ammonia, the alcohol (two
meter),
was
a
high
tests consisted of the
an
for
liquid
syringe pumps ISCO D500) and hydrogen (mass flow
pressure fixed- bed reactor and
constructed of
dosing system
a
Inconel®-718 tubing of 13
volume. The temperature in the reaction
located in the center of the tube and
The total pressure in the reactor
was
liquid separator.
gas
mm
zone was
The reactor
inner diameter and 38 ml
measured
by
a
thermocouple
regulated by
a
PID cascade controller.
by
a
Tescom back pressure
system
was set
regulator.
Standard reaction conditions were: 8.0 g catalyst;
-
0.4 mm; 210
°C,
total pressure
molar ratio of the reactants
=
catalyst sieve fraction 0.14
135 bar, contact time
R-OH/NH3/H2
=
=
40 000 gs mol"1 and
1/60/2.
Nickel-Catalyzed Amination ofl,3-Propanediols: Influence of Reactant Structure
88
Conversion, yield and selectivity of the liquid products
a
gas
were
Chromatograph (HP-5890A, FID-Detector;
identified
by
GC-MS
analysis (for details
HP-1701
were
column). The products
analysis
of the
determined by
see
Chapter 2).
4.3 Results
4.3.1
Catalyst Properties
The commercial
silica-supported
adsorption, XRD,
and ammonia
DRIFT
-
spectroscopic
shows strong
catalyst
characterized by
and
characterization
are
Fig. 1.
are
nitrogen
adsorption applying pulse thermal analysis
The DRIFT
adsorption bands
1240 cm"1 and 1610 cm"1
was
measurements. The results of the
summarized in Table 1 and
(Fig. 1)
Ni
-
spectrum of ammonia adsorption
due to Lewis acidic sites. Vibrations at
ascribed to deformation modes
(ôs NH3, ôas NH3) [18,
19].
Table 1:
Properties
Catalyst
of nickel
Ni-6458 E
<dp>c
0"
Nickel crystallite
[cmV]
[nm]
[Hmol g"1]
size, [nm]e
0.17
4.9
418
5
vp) N2
180
BET specific surface
b
V
JBET
Kg1]
a
catalyst (Engelhard, No-6458).
area;b
BJH cumulative
desorption pore volume;c mean pore diameter
d
of
chemisorbed
amount
ammonia at 50 °C;
mean crystallite size
N2/SBET;
Vp
determined by XRD line broadening of (111) and (200) reflection.
<dp>
=
4
A
3187
'
multiplet was observed in the NH stretching region (3362 cm'1,3252 cm"1,
cm'1,3165 cm"') due to the asymmetric and symmetric vN-H as well
first overtone of
2Sas NH3 [20].
Vibrational bands due to Br0nsted sites
as
to the
were
not
observed. The adsorbed ammonia species could be totally removed from the
surface
by heating
the
sample
to 250 °C.
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
89
c
o
ÏS
S
'S
oc
1111
i
4000
3500
i
i
3000
i
11
2500
Wavenumber,
i
111
i
2000
1500
i
1000
[cm1]
Figure 1: DRIFT-spectrum of ammonia adsorbed on activated commercial Ni catalyst at 50 °C;
carrier gas: 50 ml min"1 Ar, difference spectrum, obtained after subtraction of the background
spectrum is shown.
4.3.2 Amination
of1,3-Propanediols
explore the influence of
To
animations
performed
were
reactant
with
structure
the
on
product distributions
1,3-propanediols differently
substituted in C2
position: 2,2-dimethyl-1,3-propanediol, 2-methyl-l,3-propanediol
comparative catalytic
propanediol.
The
range 180
235 °C at 135 bar
ammonia:
-
Tc
existence of
=
a
Pc
=
1,3-
temperature
(critical data of
using supercritical
ammonia
114.8 bar
solvent and reactant. The
single supercritical phase
Chapter 5) [13].
to
132.4 °C,
tests were carried out in the
and
[21])
was
as
confirmed
A small ratio of hydrogen in the feed
by separate
(1-5 mol %)
was
tests
(see
sufficient
prevent the undesired dehydrogenation reactions and the formation of nitriles
and carbonaceous
was
deposit.
But
a
rather
high ammonia/alcohol
molar ratio of 60
product
amines with the
necessary to minimize the condensation of the
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
90
aldehyde
intermediate and to favour the reaction with the less reactive
ammonia
(Chapter 3, Fig 7) [22]
Scheme 1: Identified
animation
are
products and suggested reactions occurring dunng the nickel-catalyzed
2,2'-dimethyl-l,3-propanediol with supercntical ammonia Compounds identified
The dashed line frames indicate detected by-products
of
framed
Nickel-Catalyzed Animation of I 3-Propanediols Influence of Reactant Structure
91
Reactions
are
summarized in Scheme 1.
propanediol
and
occurring during the animation of 2,2 -dimefhyl-l,3-propanediol
and the
Figure 2 shows the conversion of 2,2-dimethyl-1,3-
selectivity
corresponding
to
wo-butylamine (8a, by-product) as
increased from 13
to
a
amino alcohol
function of temperature. The conversion
94 % in the range 180 to 235 °C. With increasing temperature
(conversion) the selectivity to amino alcohol dropped from 50 %
235 °C, whereas the diamine
(corresponding
below 210 °C is
(3), diamine (S)
to 75 %
selectivity
reached
a
maximum of 70 %
conversion). The loss of selectivity
mainly due to
to almost zero at
to the
at
210 °C
amino alcohol
the consecutive reaction of this intermediate to the
diamine. At temperature above 210 °C the
selectivity
to amino alcohol
diamine (5) decreased, but the formation of wo-butylamine (8a)
was
(3)
and
noticeable
favoured.
100-
s
o
Conversion
•
S3
s5
s„
A
X
Of 80"
ity
>
5
»-
<D
»
co
-
40-
c
^\»
o
'in
L.
§
20-
c
o
Ü
n
X
180
"
v
195
-
210
235
Temperature, [°C]
Figure
2:
Influence of temperature
on
conversion of
2,2'-dimethyl-l,3-propanediol (1)
and
selectivities to 2,2 -dimethyl-3-amino- 1-propanol (S3), 2,2'-dimethyl-l ,3-diaminopropane (S5) and
wo-butylamine (Sga). Superscripts denote products
Experimental Part).
as
given by numbers
in Scheme 1. Standard
conditions (see
Nickel-Catalyzed Amination of1, S-Propanediols: Influence of Reactant Structure
92
A
change
of conversion from 61 to 89 % induced
time in the range 20 000 to 80 000 gs mol"1
desired reaction products
(5) decreased about 3
with
hardly
by varying
affected the
the contact
selectivity
to
(Fig. 3). The selectivity to amino alcohol (3) and diamine
to 6
%, the wo-butylamine formation increased about 5 %
higher conversion.
100-1
1
Conversion, [%]
Figure 3: Influence of conversion on selectivity to 2,2-dimethyl-3-amino-l-propanol (S3), 2,2dimethyl-1,3-diaminopropane (S5) and wo-butylamine (Sga). Superscripts denote products as
given by numbers in Scheme 1. Conditions: contact time: 20 000 to 80 000 gs mol"1; 227 °C,
otherwise standard conditions (see
Experimental Part).
In contrast to the amination of 2,2'-dimethyl-1,3-propanediol, 2-methyl-1,3-
propanediol
to
and
1,3-propanediol amination (Fig. 4) afforded only low selectivity
the diamines (< 20 %). The shift of the
temperature indicates
an
propanediol and their
distribution
increased
reactivity
consecutive
selectivity
of
products.
maximum
to lower
2-methyl-1,3-propanediol, 1,3comparison
A
of the
product
(selectivities) obtained in the amination of the three different diols is
shown in Table 2. At the
1,3-propanediol
same
conversion of 59 %,
indicate much stronger
tendency
2-methyl-1,3-propanediol and
to
undergo degradation
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
93
80•
a
1,3-Propanediol
o
2-Methyl-1,3-propanediol
2,2'-Dimethyl-1,3-propanediol
*
,,--\
<D
c
60
''
'
x
N
s
o
O 40
»
/
XA
/
'§
A
JB 20
a>
^^Kr
CO
kS^
180
-<?-.
^^
195
9
->
235
210
Temperature, [°C]
Figure 4:
Influence of temperature
the different
1,3-propanediols.
on
diamine
selectivity of the nickel-catalyzed amination
Experimental Part).
Product distribution in amination of
Table 2:
(Engelhard, No-6458), 135 bar, 40 000
Temp. [°C]
Reactant
of
Standard conditions (see
gs mol
',
1,3-propanediols.
reactant molar ratio
Conditions: catalyst Ni
(R-OH/NHVH,) 1/60/2.
=
Selectivity S„ [%]
Conv. [%]
3
+
Liquidb
5'
Dimers
degr. prod.
2,2-Dimethyl1,3-propanediol
204
59
83
2-Methyl-
204
59
21
32
189
59
26
35
Gaseousc
degr. prod
<2
ca.
9
<2
ca.
<2
ca.37
45
1,3-propanediol
1,3-Propanediol
a
b
c
designate products in Schemes 1 and
degradation products 6,8a, 8b, 13a, 13b, 16 and 18a.
Numbers refer
Selectivity
Selectivity
reactions.
to
to
those used to
to gaseous
2.
degradation products.
the amount of
Interestingly,
oligomers
in the
product
degradation products determined
in the
mixtures
was
liquid product
minor. The
selectivity
mixture
function of temperature is presented in Fig. 5. The diamine selectivity
as a
of the amination of
to
2,2'-dimethyl-l,3-propanediol
shows
a
prominent
maximum
Nickel-Catalyzed Amination of 1,3-Propanediols- Influence of Reactant Structure
94
around 210 °C. The decline at
reactions. In contrast,
higher temperature
2-methyl-1,3-propanediol
weak maximum at lower temperature
and
is due to the
degradation
1,3-propanediol show only a
(ca. 180 °C) due
to
strong degradation
reactions.
-^
70-
of 60-
d
1,3-Propanediol
°
2-Methyl 1,3-propanediol
A
2,2'-Dimethyl-1,3-propanediol
t3
3
|
SO-
D
tt
ri 40-
,-'
gra
<B
a
,.<s''
y^
30-
t
/
'
?''
o
S.20-
,-"'''
/
,-''
.>
O
4
,''
,'*
10-
w
f
Q'
/
_>-'
o
195
180
210
235
Temperature [°C]
Figure
5:
Influence of temperature
to degradation products (compare
-dimethyl- 1,3-diaminopropane, 2-methyl1,3-propanediol. Standard conditions (see Experimental Part).
Schemes 1 and 2) formed
1,3-propanediol
A
more
side
and
detailed
products
during the
insight
were
various identified
on
diamine
selectivity
amination of 2,2
into the various reaction
obtained
by
compounds
GC-MS
in the
analysis
pathways affording undesired
of the reaction mixture. The
product mixture
are
summarized in the
Scheme 1 and 2.
Nickel-Catalyzed Amination of 1,3-Propanediols Influence of Reactant Structure
95
4.4 Discussion
The
origin of the strikingly different selectivity behaviour of 1,3-propanediols can
be traced to their different
conditions. Based
1 and 2
mainly wo-butylamine (8a).
(2)
or a
are
side reactions under amination
and intermediates the
pathways
conversion
produced
proposed.
2,2'-dimethyl-1,3-propanediol
The side reactions of the
feasible. A base
undergo
to
analyzed products
the
on
presented in Schemes
tendency
Two reaction
pathways
for the
production
of 8a
are
(or acid) catalyzed re/ro-aldol reaction of the ß-hydroxyaldehyde
refro-hydroformylation
of 2 and/or 4. The
catalytic activity
of amines in
homogeneous aldol condensation and refro-aldol reaction has been known for long
[23-25]. The refro-aldol reaction
reaction in the amination of
recently found
was
important
reaction in the heterogeneous system.
an
amine enhanced the re/ro-aldol
Accordingly, it is very likely that the product
reaction and the temperature above 200 °C
investigated
side
1,3-butanediol with dimethylamine [26]. Higher
reaction temperature and the presence of
amines of the
to be an
(Fig. 5)
caused the formation of 8a.
Zso-butylamine (8a)
which
was
found
could also be
in
the
a
consecutive
of the gas
monoxide. Both 6 and CO
were
hydroformylation)
catalysts
is
of 2. The
phase
the
gas
revealed the formation of carbon
probably produced by
hydroformylation
always accompanied by
Additionally,
mixture.
liquid product
chromatographic analysis
product of wo-butylalcohol (6),
a
decarbonylation (retro-
reaction of
an
alkene
over
metal
strong parallel hydrogénation reaction.
a
Supported Ni mainly catalyzes the hydrogénation of the unsaturated bond (and not
the
hydroformylation) [27].
favoured alkene
It is very likely that the release of CO and the strongly
hydrogénation shifted
aminated to the consecutive
the reaction
equilibrium
to
6, which
was
product 8a.
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
96
1,3-Propanediol
2-Methyl-1,3-propariediol
(R1
=
CH3
R2
=
(R1
H)
I
|
NH,
Scheme 2:
ammonia
products and suggested
2-methyl-l,3-propanediol (left)
Identified
amination of
Compounds
identified
are
H R2
=
H)
NH,
O
+NH
=
+
H2C
H2
NH,
during the nickel-catalyzed
1,3-propanediol (right) with supercntical
dashed line frames indicate the detected by¬
reactions
occurring
and
framed The
products
Nickel-Catalyzed Amination ofl 3-Propanediols Influence of Reactant Structure
97
observed side reaction of amines is the ammonia elimination
frequently
A
reaction
[26]. However,
the
of this
products
reaction, weo-pentanol
or
the
corresponding amine neo-aminopentane were not detected in the reaction mixture.
The
degradation products
animation
of
shown in Scheme 2.
are
and
2-methyl-l,3-propanediol
1,3-propanediol
2-Methyl-1,3-propanediol degraded
to iso-
butylamine (8b) and aminopropane (13a), which were found in a mass ratio of 4:1.
13a is
again
contrast
the
product of the
retro-aldol
8b, the major by-product,
was
reaction. Possible reaction sequences
3
10
-
8b.
-*
types
of
side
very
are:
re/ro-hydroformylation reaction.
likely generated by
an
the conversion of
(i) the elimination of water 1
reactions
as
1,3-propanediol over nickel
2-methyl- 1,3-propanediol:
In
elimination
(ii) the elimination of ammonia from intermediate 3
8b and
Interestingly,
or
9
-*
to
-*
8b,
produce
showed the
rerro-aldol,
same
retro-
hydroformylation to produce aminoethane (16) and the elimination reaction, which
produced
major by-product aminopropane (13b) via
the
of water is not
possible in the
missing hydrogen
at the
case
17. A direct elimination
of 2,2'-dimethyl-l,3-propanediol, because of a
C2-position. Accordingly,
it is very
likely
that the rather
high difference in selectivity to the diamine is due to dehydration of 2-methyl-l,31,3-propanediol, respectively. Dehydration
propanediol
and
catalyzed by
acidic
used nickel
catalysts [28].
of alcohols
The amount of chemisorbed ammonia
on
are
the
catalyst (Table 1 ) was approximately half of that adsorbed on an acidic
zeolite, which indicates considerable Lewis acidity of the catalyst [29]. Several
affected by the
acidity of the support. This is corroborated by the
side reactions
are
studies of the
cobalt-catalyzed amination of 1,3-propanediol
shown in
Chapter
3
[22].
Nickel-Catalyzed Amination oj1,3-Propanediols: Influence of Reactant Structure
98
4.5 Conclusion
The
comparative study
of the
propanediols in supercritical
achievable diamine
ammonia indicated
a
product
(53 %) and amino alcohol (5 %)
mixture
as
a
1,3-
strong dependence of the
which
was
containing
the
corresponding
major products. Temperature
found to be detrimental to diamine
wo-butylamine,
amination of different
selectivity on the 1,3-propanediol structure. 2,2-dimethyl-1,3-
propanediol afforded
were
nickel-catalyzed
selectivity due
to
above 210 °C
favoured formation of
retro-aldol and/or
generated by
diamine
refro-formylation
reactions. In contrast to the amination of 2,2'-dimethyl-l,3-propanediol,
2-methyl-
1,3-propanediol and 1,3-propanediol afforded only low diamine and amino alcohol
selectivity under similar reaction
higher tendency
of these diols to
direct elimination
propanediol,
water
on
a
missing hydrogen
acidic
a
undergo degradation reactions, particularly the
of water, which does
due to
is favoured
conditions. This behaviour could be traced to
not
with
2,2'-dimethyl-l,3-
position.
The elimination of
occur
at the C2
catalysts.
Nickel-Catalyzed Amination of 1,3-Propanediols: Influence of Reactant Structure
99
4.6 References
[I]
D M Roundhill, Chem Rev 92,1
[2]
M G Turcotte and T A Johnson,
F M Mark,D F
(1992)
Kirk-Othmer, Encycl Chem Technol.Vol 2, eds
Othmer.C G Overberger and G T Seaborg (Wiley, New York 1992)
in
p 369
[3]
in Handbook of Heterogeneous Catalysis, Vol 5, eds G Ertl,
Weitkamp (VCH Verlagsgesellschaft, Weinheim 1997) p 2334
A Fischer, T Mallat and A Baiker, Catal Today 37, 167 (1997)
R E Vultier, A Baiker and A Wokaun, Appl Catal 30,167 (1987)
J Kijenski.P J Niedzielski and A Baiker, Appl Catal S3,107(1989)
A Baiker, in Catalysis ofOrganic Reactions, eds J R KosakandT A Johnson (Marcel
T MallatandA Baiker,
H
[4]
[5]
[6]
[7]
Knozinger
and J
Dekker, New York 1994) p 91
Kijenski, Catal Rev Sa Eng 27, 653 (1985)
Kijenski.J Burger and A Baiker, Appl Catal 11,295(1984)
J Card and J L Schmitt, J Org Chem 46,754(1981)
[8]
A Baiker and J
[9]
J
[10]
R
[II]
[12]
[13]
[14]
[15]
Yeaky, US Patent 4 547 591 (1985)
Europ Patent 0 256 516 (1987)
A Fischer, T MallatandA Baiker, Angew Chem lnt Ed in press (1998)
JCPDS Mineral Powder Diffraction Data Files, Park Lane, Pennsylvania, USA
HP Klug and L E Alexander, X-ray Diffraction Procedures for Polycrystalline and
Amorphous Materials, J Wiley & Sons, New York 1974
M Maciejewski, C A Muller.R Tschan.W D Emmerich and A Baiker, Thermochim
[16]
ME Brennan, J
Templeton
and E L
Y Hara,S KumoiandY Tsutsumi,
Acta 295, 167(1997)
[17]
M
Maciejewski,W
[18]
E
Jobson, Dissertation, Laboratory
D EmmenchandA
Baiker.J Therm Anal Cal submitted(1998)
of Technical
Chemistry,
ETH-No 8974, Zurich
(1989)
[19]
A A
Davydov, Infrared Spectroscopy of Adsorbed Species on the Surface of Transition
Metal Oxides,
[20]
[21]
Wiley,
Chichester 1990
Appl Catal 64,243(1990)
Allamagny (L'Air Liquide, Elsevier, Amsterdam 1976)
G Ramis, G Busca,V Lorenzelli and P Fotzatti,
Encyclopédie
de Gaz, ed P
p
951
MallatandA Baiker.J Catal
[27]
[28]
submitted(1998)
60,90(1938)
R W Hay and K R Täte, Austr J Chem 19,1651 (1966)
A T Rielsen and W J Houlihan, Org Reactions 16,7 (1968)
G Sirokmân, Â Molnâr and M Bartok, J Mol Catal 19 (1983) 35
S NaitoandM Tanimoto,J Chem Soc Chem Commun 1403(1989)
M Kraus, in Handbook ofHeterogeneous Catalysis, Vol 3, eds G Ertl, H Knozinger
[29]
F
[22]
[23]
[24]
[25]
[26]
A Fischer,M
Maciejewski,T
F H Wesheimer and H Cohen, J Am Chem Soc
Weitkamp (Wiley-VCH, Weinheim 1997) p 1061
Eigenmann, Diploma Thesis, Laboratory of Technical Chemistry,
Institute of Technology, Zurich (1998)
and J
Swiss Federal
Nickel-Catalyzed Aminatwn ofl 3-Propanedwls Influence of Reactant Structure
Leer
-
Vide
-
Empty
5
Influence of Pressure
on
the Animation of Propanediols
5.1 Introduction
The
heterogeneously catalysed
amination of alcohols has been established
industrially most important process
for the manufacture of a
[1-6]. However, the yields and selectivities
low in the
of
primary aliphatic
diamines from the
the
variety of aliphatic
and aromatic amines
synthesis
as
are
usually ramer
corresponding diols
and ammonia.
The transformation of a simple aliphatic alcohol to the corresponding amine
on
a
metal
catalyst includes three major reaction steps (Scheme 1): (i)
dehydrogenation
to a
carbonyl compound; (ii) condensation with ammonia or an
amine to form an imine or an enamine and (iii) hydrogénation to the corresponding
amine [7, 8]. Each intermediate and the
reactions
such
as
condensation,
hydrogenolysis [4, 9-11].
corresponding
the
diamine
amine
can
undergo
various side
decarbonylation, disproportionation
The direct transformation of
an
aliphatic
and
diol to the
requires the repetition of the steps (i) (iii) which favours
by-product formation.
scope of
product
-
In
addition, the bifunctional intermediates extend the
possible side reactions (e.g. oligomerization
and
cyclization) [12, 13].
Still, reasonable yields have been reported for the amination of alkanediols with
secondary amines,
Unfortunately,
as
the
product tertiary
the situation is the
amine is
reverse
moderately reactive [7, 14].
in aminations with ammonia
reactivities of the intermediate and product primary amines
are
as
the
significantly higher
Influence of Pressure
102
than that of ammonia. The above considerations account for the difficulties in the
selective
synthesis
of
primary
diamines from diols. A
practical solution
is the
separate preparation of the amino alcohol intermediate and its further amination
with ammonia which method
provides good selectivities
to diamines
[15-19].
OH
OH
|-H2
r*n -££Jr^R
O
OH
; OH
\
a-NH3
OH
H2
-H2|
+
NH 3/-
NH2
OH
0
1
|-H2
H20
V
'NH2
NH3/-
H
-co
NH2
O
+
i+H2
NH2
I+NH3/•H20
t
R
=
H,
Important
H2
CH3
NH2
Scheme 1:
+
reactions
occurring in
NH2
the amination of alkanediols with ammonia. The
continuous and dashed line frames indicate the detected main and
Intrigued by the
obvious
of alkanediols with ammonia
Influence of Pressure
advantages of the
was
one
by-products, respectively.
step process, the amination
reinvestigated at pressures
where the ammonia
103
forms
a
[20]).
The amination of
chosen
supercritical fluid (critical data of ammonia: Tc
as
types of catalysts
5 wt% Fe and
Preliminary experiments indicated that
a
rather
Pc
=
114.8 bar
1,3-propanediol and 2,2'-dimethyl-l,3-propanediol
test reactions. Two
catalyst stabilised by
132.4 °C,
=
high ammonia/alcohol
a
were
used:
an
unsupported
commercial supported Ni
Co
catalyst.
in agreement with the literature data
-
were
[21]-
molar ratio in the range of 10/1 to 100/1
was
necessary to suppress the dimerization and oligomerization of the intermediate and
product amines.
A small ratio of hydrogen in the feed
(1-5 mol% of the reaction
mixture) was sufficient to prevent the undesired dehydrogenation reactions and the
formation of nitriles and carbonaceous
5.2
deposit.
Experimental
The Co-Fe catalyst
was
prepared by coprecipitation. Aqueous
nitrate and iron nitrate, and ammonium carbonate were mixed
and the
pH was
set to 7. The
area was
8
temperature
100 °C in
m2g~'
vacuum
and the pore
cm3g"'.
The commercial
Ni-catalyst (Engelhard
prereduced Ni. The BET surface
0.3 cm3
at room
precipitate was filtered off, dried at
and calcined at 400 °C for 4 h. The BET surface
volume 0.1
solutions of cobalt
area was
N°
6458) contained 56 wt%
180 m2
g"1
and the pore volume
g1.
The amination
tubular reactor with
crushed and sieved
experiments
an
were
carried out
inner diameter of 13
catalyst particles
mm.
isothermally in
The reactor
of 140 to 400 yum. The
a
was
liquid
continuous
loaded with
ammonia and
1,3-propanediol or the solution of 2,2-dimethyl-1,3-propanediol in ammonia were
dosed to the
reactor
reaction system
by ISCO
was set
by
a
D500
syringe
pumps. The total pressure in the
TESCOM back pressure regulator. Details of the
Influence ofPressure
104
reaction conditions
separated from the
are
gas and
column). The products
analysis
see
indicated in the
figure captions.
analysed by an
identified
were
HP 5890 gas
by
GC-MS
The
liquid product
was
Chromatograph (HP 1701
analysis (for
details of the
Chapter 2).
5.3 Results and Discussion
Fig.
over
1 illustrates the role of the total pressure in the amination of
the
unsupported Co-Fe catalyst.
conversion varied only from 85
over
100 bar had
a
to
striking effect
In the whole pressure range
99 %. However,
on
1,3-propanediol
a
the amination
studied, the
pressure increase from 50 to
selectivity.
The
technically
important cumulative selectivity to 3-amino-l-propanol and 1,3-diaminopropane
increased from
ca.
1 % to 43
-
48 %.
On the basis of literature data [22-25] it is
where the
the
selectivity to
the diamine is constant
supercritical (sc) region.
of the reaction mixture
was
To confirm this
expected that at 135 bar or above,
(Fig. 1), the reaction
assumption,
the
Accordingly,
it is
proposed
selectivity with increasing
in the
near
critical
phase composition
investigated in a 50 ml quartz autoclave.
of a homogeneous fluid at 130 bar and 200 °C was confirmed
that the remarkable
region
of ammonia
The presence
by visual inspection.
improvement
pressure is connected with the
mixture is in
in amination
change of the
(110-120 bar)
medium
and at the reaction
temperature 60 °C above the critical temperature.
It
seems
from
Fig.
1 that the amination
selectivity increased
in both
consecutive steps, in the formation and in the further amination of the amino
alcohol intermediate.
Influence of Pressure
105
I Conversion
I
I
I Sel
100
aminol
to
Sel to diamine
8030
„
o
to
-20
>
c
o
40
[km
o
I
^m-.n
135
100
50
Pressure
[bar]
of propanediol, and the selectivity to 3-aminoFigure 1: Influence of pressure on the conversion
Conditions 95 wt % Co- 5 wt %
1-propanol ("aminol") and 1,3-diammopropane ("diamine").
of alcohol/H2/ammoma: 1/2/60
Fe catalyst, 195 °C, contact time 60 000 gs mol ', molar ratio
In
a
control
reactor under
likewise
a
selectivity
experiment the intermediate 3-amino-l -propanol was
fed to the
increasing
pressure:
similar conditions.
small
was
drop
in
2 shows the effect of
conversion and
observed in the
near
the variations in conversion and
The
Fig.
critical
selectivity
not limited to the use of the Co-Fe
Fig.
3 presents another
case
example,
the reaction
increasing pressure
had
was
only
region.
were
Below and above this
catalyst
or
the amination of
carried out with the
minor influence
on
selectivity
above the critical pressure of
were
region
minor.
amination of alkanediols
1,3-propanediol
as
reactant.
2,2'-dimethyl-l,3-propanediol.
supported Ni catalyst. Again,
the
the diol conversion, but favoured
the formation of amino alcohol intermediate and
diamine. The changes in
in diamine
significant improvement
striking effect of supercritical conditions in the
was
In this
a
especially
negligible below
the desired
90 bar and
product
only
minor
ammonia.
Influence of Pressure
106
100-
n
n
80-
[%]
o
Conversion
•
Sel. to diamine
D
°
o
50
40
•
ersion
o
t
40-
»
S
h 30
t3
—
PJNHJ
"53
20
O
Ü
20-
-10
-0
040
80
60
100
Pressure
2: Effect of pressure
[bar]
the conversion of 3-amino-l-propanol and the
Figure
diaminopropane ("diamine"). Conditions: 95 wt % Co- 5 wt %
40 000 gs mol"1, molar ratio of alcohol/H2/ammonia: 1/2/40.
on
140
120
Fe
catalyst,
selectivity to 1,3-
195 °C, contact time
uu-
R0-
d
Conversion
•
Sel. to aminol
a
Sel. to diamine
x
Sel. to
alkylamines
r-30
D
r-,
o\
D
D
°
°>
0}
O)
60-
—
L
P*(NHJ
40o
/
>
C
O
'
X
20-
Ü
j^
040
•
-—-__.
—•—'
»_
60
80
100
Pressure
120
140
[bar]
Figure 3: Influence of pressure on the conversion of 2,2'-dimethyl-l,3-propanediol, and the
selectivity to 2,2'-dimethyl-3-amino-l-propanol ("aminol") and 2,2'-dimethyl-l,3diaminopropane ("diamine"). Conditions: 56 wt % Ni on support (Engelhard Ni-6458), 210 °C,
contact time 40 000 gs mol"1, molar ratio of alcohol/H2/ammonia: 1/2/60.
Influence of Pressure
107
Before
discussing
enhancement it has
to
the
possible
for the
reasons
to the
corresponding diamines.
dimethyl-1,3-propanediol
diaminopropane
at
selectivity
propanediol
to
in
227
°C
only
a
example,
For
small influence
from 61 to 89 %
diamine of
a
ca. ±
2 %
the
in the amination of 2,2
selectivity
the
on
-
2,2'-dimethyl-l,3-
to
decreased from 58 to 53 % when the conversion increased
increasing the contact time)
in
selectivity
ascertain that in the amination of various alkanediols and
amino alcohols the conversion above 60 % had
selectivity
observed
(by
(Chapter 4, Fig. 3). A minor variation
observed in the amination of 1,3-
was
(Chapter 3, Fig. 8). The likely
similar conversion range
interpretation for the small effect of increasing conversion is that more diamine is
formed from the amino alcohol intermediate
consumed
by consecutive
side
at
reactions,
such
the
hydrogenolysis (degradation). Accordingly,
increasing
pressure
(Figs. 1-3)
higher contact time, but also more
as
disproportionation
changes
in
selectivity
or
with
variations in
cannot be traced to the small
conversion.
At medium pressures
a
liquid phase
(< 90 bar) the reaction mixture consists of two phases:
rich in the non-volatile alkanediol and amines
along the catalyst bed), and
conversion
a
gas
(depending
on
the
phase containing dominantly
ammonia. In this pressure range the influence of total pressure
on
conversion and
product composition was minor as illustrated in Figs. 1-3. In the near critical region
the transformation of the
results in
phase
a
two-phase system
homogeneous
sc
fluid
generally
significant improvement of mass transport due to the elimination of the
transfer resistance, and to the
viscosity, compared
pressure
to a
on
to the situation in the
the chemical
Unfortunately, for
pressure is rather
a
higher
diffusion coefficients and lower
liquid phase. Besides,
equilibria and reaction rates
network of consecutive and
complex
can
parallel
the effect of
also be crucial
[26-28].
reactions the effect of
due to the different reaction volumes
(AVT)
and
Influence ofPressure
108
(aV#).
activation volumes
ammonia concentration is
governing
enhanced
effect)
supercritical region
the surface
significantly higher than under two phase conditions,
region. Although
in the subcritical
mass
can
It is assumed that in the
transfer in the
fluid,
sc
also contribute. There
a
this
change
is
mainly
as
due to the
change in adsorption equilibrium (solvent
are some
recent
examples
in the literature
the
on
enhancement of stereoselectivity {cisltrans ratio) in the hydrogénation of vegetable
oils in
scC02 [29].
improvement
The
hydrogen availability on the metal
limitations in the
A clearer
sc
was
attributed to the
surface due
to the
significantly
better
elimination of mass transport
fluid phase.
picture
is obtained
by analyzing the
influence of the subcritical-
supercritical transition on the main reaction steps and the side reactions. The major
side reactions
producing
primary alcohols
surface results in
intermediate
can
also form via the
forms
Fig.
alkylamines
3 for the animation of
significant drop in the
amount
supercritical region completes
supercritical region
were
It is
not
of this
the
liquid product
2,2-dimethyl-1,3-propanediol.
details
see
in the
by-product
picture discussed
A
critical and
oligomerization
side
important.
that the
near
critical
changes
region
in amination
are
selectivity and alkanediol
due to the increased surface ammonia
concentration. This change favours the amination and suppress the
(hydrogenolysis) type side
Influence of Pressure
The latter
Chapter 4).
near
is
above. Note that in the
of ammonia, the dimerization and
suggested
conversion in the
alkylamines. This aldehyde
detected in the
by-product mainly wo-butylamine (for
as
reactions
to
by¬
(acid-base catalysed) retro-aldol reaction [13].
The variation of the total amount of
illustrated in
and amines. Amination of the alkanol
aldehyde intermediate leads
via the
are
Decarbonylation of the intermediate aldehydes on the metal
illustrated in Scheme 1.
product
volatile monofunctional alcohols and amines
degradation
reactions. The situation is rather similar to the well
109
known and
in the
example,
adsorbing
alcohols
widely applied
selective
of
hydrogénation
poisoning
carbonyl compounds the
amines hinders the C-0 bond
can
be
prepared
in very
hydrogenolysis
presence of
and the
For
strongly
corresponding
high yields.
In the animation of alkanediols and alkanolamine
drop
catalysts [30-32].
of metal
(Figs.
1 and
in conversion and the strong decrease in the amount of
2), the small
alkylamines by¬
products in the liquid phase (Fig. 3) are clear indications of selective poisoning: the
demanding degradation type reactions are effectively slowed down but also the first
step, the dehydrogenation of the alcohol
to
the
carbonyl compound,
is affected. On
the other hand, the higher surface ammonia concentration favours the fast ammonia
addition
the
to
aldehyde-type intermediates, and suppresses
alcoholic OH group with the intermediate
dimerization products. That is, the weaker
or
product
the reaction of the
amines
leading
basicity of ammonia, compared
to
to the
product amines, is partly compensated by its higher surface concentration. All these
effects
can
contribute to the remarkable enhancements in the overall amination
selectivities
(Figs. 1-3).
5.4 Conclusion
The
application
of
scNH3
solvent and reactant in the amination of
as a
alkanediols and amino alcohol affords
primary diamines, compared
changes in selectivities
of the medium. The
occur
to
in
simple
significant improvement in selectivities
the subcritical pressure
a narrow
procedure.
pressure range in the
selectivity improvement is attributed
near
to the
to
Most of the
critical
region
higher surface
concentration of ammonia which favours the amination with ammonia and
suppresses the degradation type side reactions. It seems that the phenomenon is not
limited
to a
specific catalyst
or
reactant,
though the
final
selectivity is
a
function
Influence of Pressure
110
of the structure of the reactant amino alcohol
Influence of Pressure
or
diol
as
discussed in
Chapter 4.
Ill
5.5 References
[1 ]
[2]
Encycl. Chem. Technol., Vol. 2, Wiley, New
York, (1992), p. 369.
G. C. Carter, A. R. Doumaux, S. W. Kaiser, P. R. Umberger, Kirk-Othmer, Encycl. Chem.
Technol., Vol. 8, Wiley, New York, (1992), p. 74.
M. G. Turcotte, T. A. Johnson, Kirk-Othmer,
Roundhill, Chem. Rev. 92, 1 (1992).
Baiker, in J. R. Kosak, T. A. Johnson (Eds.): Catalysis of Organic Reactions, Marcel
Dekker, New York, (1994), p. 91.
[3]
[4]
D. M.
[5]
[6]
Fischer, T. Mallat, A. Baiker, Catal. Today 37, 167 (1997).
Mallat, A. Baiker, in G. Ertl, H. Knözinger, J. Weitkamp (Eds.): Handbook of
Heterogeneous Catalysis, Vol. 5, VCH Verlagsgesellschaft, Weinheim, 1997, p. 2334.
[7]
R. E. Vultier, A. Baiker, A. Wokaun, Appl. Catal. 30, 167
[8]
J.
[9]
A.
Baiker,
[10]
J.
Kijenski,
[11]
R.J.
[12]
G. Sirokmân, A. Molnâr, M. Bartok, J. Mol. Catal. 19, 35 (1983).
Ä. Molnâr, G. Sirokmân, M. Bartok, J. Mol. Catal. 19, 25 (1983).
J. Runeberg, A. Baiker, J. Kijenski, Appl. Catal. 17, 309 (1985).
R. Becker, V. Menger, W. Reif, A. Henne, US Patent 5 608 113, (1997), [Chem. Abstr.
(1996), 124, 316502].
C. A. Gibson, J. R. Winters, US Patent 4 400 539, (1983), [Chem. Abstr. 1983, 99,
[13]
[14]
[15]
[16]
A.
A.
T.
Kijenski,
(1987).
Appl. Catal. 53, 107 (1989).
Eng. 27, 653 (1985).
P. J. Niedezielski, A. Baiker,
Kijenski, Catal Rev. Sei.
Burger, A. Baiker, Appl. Catal. 11, 295 (1984).
Card, J. L. Schmitt, J. Org. Chem. 46, 754 ( 1981 ).
J.
J.
21938w].
Moriya, Europ. Patent 0 652 207, (1994), [Chem.
Nagasaka, Y. Hara, Europ. Patent
[17]
A.
[18]
T. Hironaka, N.
Abstr. (1995), 123, 9064].
0 526 851,
(1992), [Chem. Abstr.
(1993), 118, 212475].
[19]
[20]
[21]
F.
Merger,
A.
(1979).
Allamagny, Elsevier, Netherlands (1976), p. 951.
Aschmann, H. Birnkraut, US Patent 4 078 003, (1978), [Chem. Abstr.
Segnitz,
US Patent 4 158 017,
Encyclopédie de Gaz, éd.
H.
Feichtinger,
H.
P.
(1975),S5,78566x],
[22]
E. Brunner, J. Chem.
[23]
E. Brunner, J. Chem.
[24]
[25]
J. C.
[26]
[27]
[28]
A.
[29]
T.
S.
Giddings,
M.
Thermodynamics 20, 1397 (1988).
Thermodynamics 20, 273 (1988).
N. Myers, L. McLaren, R. A. Keller, Science 162,
67
(1968).
Borman, Science/Technologie 33 (1995).
Baiker, Chem. Rev. (1999), in press.
C. Eckert, B. L. Knutson, P. G. Debenedetti, Nature 383, 313
P. E.
Savage,
S.
Gopalan,
T. I.
(1996).
Mizan, C. J. Martino, E. E. Brock, AIChE Journal, 41,
1723 (1995).
S. Wielander, P. Panster, in R. von Rohr, C. Trepp (Eds.): High Pressure
Engineering, Vol. 12, Elsevier, Zurich, Switzerland, (1996), p. 17.
Rylander, Catalytic Hydrogénation over Platinium Metals, Academic Press, New
Tacke,
Chemical
[30]
P. N.
[31]
P.
York and London, (1967).
Rylander, Catalytic Hydrogénation in Organic Synthesis, Academic Press, New York,
(1979).
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112
[32]
M. Freifelder, Practical
Catalytic Hydrogénation Techniques
Interscience, New York (1971).
Influence of Pressure
-
and
Applications, Wiley-
6
Synthesis
of
1,4-Diaminoc\ clohexane
6.1 Introduction
Amination of aliphatic alcohols
to
a
multitude of amines
rather low in the
on a
metal
catalyst provides
an
economic
[1-4]. However, the yields and selectivities
are
access
usually
synthesis of aliphatic diamines from the corresponding diols
and
ammonia.
The
metal-catalyzed synthesis
alcohol includes the
dehydrogenation of the alcohol
condensation with ammonia to form
to the amine
corresponding
of aliphatic amines from the
an
imine
or
to a
carbonyl compound, the
enamine, and the hydrogénation
[5, 6]. Each intermediate and the product amine
can
take part in
condensation, decarbonylation, disproportionation and hydrogenolysis side
reactions
the
[7-10]. The synthesis of a diamine from the corresponding diol requires
repetition
addition,
the
of all three steps which increases the
bifunctional
oligomerization
and
reactions
product amines
are
intermediates
have
by-product
the
tendency
formation. In
to
undergo
[6,11,12]. A further difficulty is that the intermediate
significantly more reactive than ammonia. Application of
supercritical fluids provides interesting opportunities for improving the efficiency
(conversion, selectivity, catalyst life time and separation) of heterogeneous
catalytic processes.
recent
review
The
The advances made in this field have been discussed in
a
[13].
application of supercritical
ammonia
(scNH3)
as a
solvent and reactant
Synthesis of 1,4-Diaminocyclohexane
114
affords remarkable
compared
to
selectivity improvement in
the subcritical pressure
the amination of
1,3-propanediol,
procedure (Chapter 5) [14].
The
selectivity
improvement could be traced to the suppression of degradation type side reactions.
In this
in
a
chapter the cobalt-catalyzed amination of 1,4-cyclohexanediol (Scheme 1)
continuous
high pressure reactor under supercritical conditions is
CT
*
described.
CT-*- OtX
H2
+
-H,0
n
X
J
+nh*.
-H,0
[Y
X
J
±mk
-H20
H,N
•H,0
XT"
NH,
mxy xXoPz^y Xa^xj txH2
oligomers
Scheme 1:
Important
reactions
ammonia. The intermediates and
occurring during the amination of 1,4-cyclohexanediol with
products shown were identified by GC-MS.
Synthesis of 1,4-Diaminocyclohexane
115
present, diaminocyclohexanes
At
hydrogénation
Considering
amines
of aromatic
the
availability,
such
as
the oxidation
stability
and the
diaminocyclohexane
important chemical applied
polyurea
elastomers [17],
ZSM-35 [19] and
6.2
a
toxicology
an
tumour
agent
of the
1,4-
chain extender in
as
ingredient of lubricants [18], agent
component of anti
catalytic
attractive alternative.
cyclohexanediol
an
is
the
p-phenylenediamine [15, 16].
reactant, the amination of
is
by
manufactured
are
in the
synthesis
of
platinum complexes [20].
Experimental
For the
preparation
of the 95 wt-% Co-5 wt-% Fe
catalyst,
the metal nitrates
(molar ratio of 20/1 ; total metal nitrates: 0.18 mol) were dissolved in 500 ml water.
100 g of an aqueous solution
temperature over
a
time
containing 20 wt-% of (NH4)2C03 was added at room
period of
1 h until
a
pH of 7
was
washing,
reached. The
the
precipitate
suspension
was
stirred for 2 h and filtered. After careful
100
°C, calcined at 400 °C for 2 h and activated by hydrogen reduction
was
dried at
at 335 °C
for 4 h.
The apparatus
mixture (ISCO D500
comprised the dosing system
syringe pump) and hydrogen (mass
pressure continuous fixed-bed reactor and
constructed of an Inconel-718
tubing of 13
a
mm
zone was
the centre of the tube and
regulated by
was
pressure in the reactor system
was
set
Standard reaction conditions were: 8.0 g
time, and molar ratio of the
The
alcohol
high
The reactor
was
inner diameter and 38 ml volume.
measured
by
-
flow meter), the
gas/liquid separator.
The temperature in the reaction
contact
for the ammonia
by a thermocouple
located in
a
PID cascade controller. The total
a
Tescom back pressure
regulator.
catalyst; 165 °C, 135 bar, 40 000 gs mol"1
reactants
R-OH/NH3/H2
=
1/60/2.
liquid products were analyzed using a gas Chromatograph ( HP-5890A,
Synthesis of J, 4-Diaminocyclohexane
116
FID detector and
details of the
The
following
>
column) and were identified by GC-MS analysis (for
HP-1701
analysis
cyclohexanediol
%
an
see
Chapter 2).
reactant
98 %
purities
were
quoted by
the manufacturer: 1,4-
(Fluka), ammonia 99.98 %(Pan-Gas), hydrogen 99.999
(Pan-Gas) and nitrogen 99.995
(Pan-Gas).
%
The existence of a single fluid phase under the
experimental conditions used
( 130 bar, 200 °C) has been corroborated by independent visual tests with two diols
in
similarly diluted mixtures (1.5 mol-% diol). The critical
=
132.4 °C and
Pc
114.8 bar
=
data of ammonia
are
Tc
[21].
6.3 Results and Discussion
As stated in the
introduction, the activity of ammonia is usually lower than that of
the intermediate and
product
amines. To compensate this
relatively large NH3/R-OH
selectivities to
is
necessary to
obtain
primary amines (Chapter 3, Fig. 7). Accordingly,
carried out at 135 bar with
hydrogen
molar ratio
reactivity difference,
in the feed
a
molar ratio
(1-5 mol %)
was
NH3/R-OH
a
acceptable
all reactions
were
60/1. A low amount of
=
sufficient to
prevent the undesired
dehydrogenation reactions and the formation of nitriles and carbonaceous deposit.
Figure
1 illustrates the influence of temperature
cyclohexanediol (1)
in
supercritical
ammonia
over a
on
the amination of 1,4-
95 % Co
-
5 % Fe
catalyst.
The conversion indicates the consumption of 1 via dehydrogenation to 4-hydroxy-
cyclohexanone.
This
in the amination of
metal-catalyzed step has been found to be rate determinating
simple aliphatic alcohols [22].
The formation of the amination
products 4-aminocyclohexanol (2, Scheme
1) and 1,4-diaminocyclohexane (3) shows the typical
reaction series. A maximum
yield of 32
Synthesis of I,4-Diaminocyclohexane
course
% for the amino alcohol
of
(2)
a
consecutive
was
achieved
117
at 165 °C and 54 % for the diamine
r
Oo
Convers
F
1 Y eld of
B
[%]
(3)
on
4
Aminocyclohe
Yield of 1 4
'p
CD
60-
c
o
2
r
40-
CD
>
[-
O
Ü
20-
p
X ^
n-
anol
\\\
Diammocyck hexane
CO o
-j:
at 185 °C
1
r
1
210
175
Temperature [°C]
Figurel: Influenceof terapeiatuie
The
selectivity
contact time
Some
formed
dominant
products
there
examples
doubling
depict
are
the
the
shown
same
in
be further
At 165 °C the
only
a
improved by
5%
small
conversion
Table 1 The two sets of experiments
tendency
at
higher
catalyst
was
contact times the
change
in
the diamine
of diol The amount of
'
Contrary
yield
at 195
such
as
to
the
by¬
became
rather selective and the amount of
by¬
expectation,
°C, despite of the
by products barely changed when
the contact time from 30 000 to 60 000 gs mol
product
varying the
by hydrogenolysis and dimerization/oligomenzation
oligomers, degradation products
in
(3) could
did not exceed 3 % up to 40 000 gs mol
was
complete
cyclohexanediolovera95%Co
the animation of 1 4
to the diamine
at 165 °C and 195 °C
products
on
standaid conditions
catalyst
Fe
7 and 8
'
Beside dimers and
(Scheme 1 ) could
be identified
mixture
Synthesis of 1 4-Diaminocyclohexane
118
Table 1 : Influence of the
Scheme 1)
over a
Contact time
contact
time
on
the amination of
1,4-cyclohexanediol (1, accordingly
95% Co- 5% Fe under otherwise standard conditions.
Temp.
Conversion
[°C]
[%]
2
3
By-products
30000
165
70
21
46
3
40 000
165
76
32
42
2
60 000
165
93
9
29
55
20 000
195
99
6
67
26
30 000
195
100
3
55
42
40 000
195
100
3
54
43
60 000
195
100
1
52
47
[gs
mol
']
Yield, [%]
100
~
80
>
60-
40-
40
60
Conversion
[%]
Figure 2: Influence of temperature on the cumulative selectivity to 4-aminocyclohexanol (2) and
1,4-diaminocyclohexane (3) over a 95% Co- 5% Fe catalyst; standard conditions.
Figure
2 illustrates the cumulative
diamine (3)
as a
The amination
selectivity
to the
function of reaction temperature,
selectivity
has
an
Synthesis ofl, 4-Diaminocyclohexane
optimum
on
amino alcohol (2) and
the basis of the data in Fig. 1.
of 97 % at 76 % diol conversion. The
119
lower
selectivity at low
and
high conversion
is due to the formation of dimers
6), oligomers and degradation products. At low conversion the dimer (5)
main
by-product.
transformed
to
At
high conversion (and longer
dimers
contact
times)
was
2 and 3
(4the
were
(mainly 6) and insoluble oligomers, and the generation of
degradation products,
e.g.
aminocyclohexane (8),
was
also favoured.
The
degradation products were partly further aminated with ammonia or some amines.
6.4 Conclusions
An alternative
catalytic
route for the
been shown which is based
catalyst
in
scNH3.
on
synthesis
the amination of
of
1,4-diaminocyclohexane
has
1,4-cyclohexanediol over a Co-Fe
The amination affords 67 %
yield
at almost
complete
conversion. The efficiency of the reaction can be further improved by recycling the
unreacted diol and amino alcohol intermediate,
products
to ca. 3 %.
advantages
The
reducing the
amount of
by¬
high chemical efficiency combined with the engineering
of continuous
operation and
solvent and reactant ammonia
provides
a
easy
separation
good basis
from the
for industrial
supercritical
application of
the process.
Synthesis of J, 4-Diaminocyclohexane
120
6.5 References
[I]
[2]
Roundhill, D M Chem Rev 92, 1 (1992)
Turcotte, M G and Johnson, T A in Kirk-Othmer, Encycl Chem Technol, Vol 2,
,
,
eds F M Mark, D F Othmer, C G
Overberger and
G T
Seaborg (Wiley,
[3]
1992) p 369
Mallat,T and Baiker,
[4]
[5]
[6]
Weitkamp (VCH Verlagsgesellschaft, Weinheim 1997)
Fischer, A, Mallat, T and Baiker, A Catal Today 37,167 (1997)
Vultier, R E Baiker, A and Wokaun, A Appl Catal 30, 167 (1987)
Kijenski, J Niedzielski, P J and Baiker, A Appl Catal 53,107 (1989)
[7]
Baiker, A
[8]
Johnson (Marcel Dekker, New York 1994) p 91
Baiker, A and Kijenski, J Catal Rev Sei Eng 27, 653
H
[9]
[10]
[II]
A
,
Handbook of Heterogeneous
in
Catalysis,
Vol 5, eds G Ertl,
and J
Knozinger
New York
p 2334
,
,
,
,
,
Catalysis
in
,
of
Organic Reactions,
Vol
53, eds J R Kosak and T A
,
J
Kijenski,
,
Burger,
J and Baiker, A
,
Appl Catal 11,
(1985)
295 (1984)
Card, R J and Schmitt, J L, J Org Chem 46, 754 (1981)
Sirokmân, G Molnâr, Ä and Bartok, M, J Mol Catal 19, 35 (1983)
,
[12]
[13]
[14]
[15]
[16]
Molnâr, Â
[17]
[18]
Pnmeaux, I and Dudley, J
Baiker, A
,
Chem Rev,
,
Fischer, A
Sirokmân, G and Bartok, M, J Mol Catal 19, 25 (1983)
,
in
press
(1999)
Mallat, T and Baiker, A Angew Chem Int Ed, inpress (1999)
,
Brake, L, US Patent 3 636 108 (1977)
Rutter, H, Ruhl, T, Breitscheidel, B
Patent 5 773 657 (1998)
Cheng,
V M
Farng,
,
Henkelmann, J, Henne, A and Wettling, T, US
US Patent 5 162 388
,
L O
,
,
Horodysky,
(1992)
A G and
Poole, R J
,
US Patent 5 407 592
(1995)
S D
Chang,
C D and
[19]
Hellnng,
[20]
[21]
Khokhar, A and Siddik, Z H
Encyclopédie
,
de Gaz, ed P
,
Lutner, J D
,
US Patent 5 190 736
US Patent 5 393 909
Allamagny (L'Air Liquide, Elsevier, Amsterdam 1976)
951
[22]
Bassih, V and Baiker, A
,
(1993)
(1995)
Applied Catal 70,
Synthesis ofl 4-Diaminocyclohexane
325
(1991)
p
Outlook
The
efficiency
conditions
of the described amination process
(supercritical conditions,
properties
optimize the heterogeneous
to
are
the reaction
on
reactant ratio and contact
and reactant structure. These factors
developments
depends
time), catalyst
starting points
transition metal
for further
catalyzed synthesis
of primary diamines.
The
use
represents
a
of
supercritical ammonia
neat solution to
improve
as
reactant and
the diamine
selectivity.
reaction medium
The
experimental
results of this thesis should encourage to extend theoretical and
investigations
in order to make
supercritical ammonia.
more
on
than
one
rate and
A
a
proper
use
of the
problem in interpreting
effect may be
the
practical
opportunities provided by
experimental
results is that
operative, rendering a clear assignment of the effects
selectivity difficult. First,
some
fundamental aspects have to be
understood, e.g. effect of local density variation of solvent and solute
heterogeneously catalyzed reaction,
which may
behaviour and thus the surface reaction. The
control the
selectivity
fluid in
phase behaviour, separation,
of the
change adsorption, desorption
supercritical
rate, and
catalytic surface reaction.
on a
as
It is very
fluid
illustrated,
likely
can
to
that the
be used to
influence the
supercritical
heterogeneously catalyzed reaction demands also special catalyst surface
properties. Spectroscopic
correlation. For this task,
have to be
in situ measurements could
new
catalyst
help
to understand the
materials with known surface
properties
prepared. The study would reveal the relationship between preparation
technique, catalyst properties and catalytic activity of the material in a supercritical
fluid.
122
Finally,
potential
the
the extension of
of the amination with
stereo
selective
intermediates for
a
screening
supercritical
production
numerous
reactant
ammonia. A
of amines.
pharmaceuticals
would
Such
help
to
explore
demanding
products
and fine chemicals.
are
the
task is e.g.
important
Appendix
Appendix
Leer
-
Vide
-
Empty
125
Reactor and Oven
snM.
I
I
a.
a
^
Material:
lnconel-718
Volume:
38 ml
200 bar
(rmaxlmum):
Temperature (maximum): 300 °C
Pressure
Appendix
126
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in
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<o
1
"
020
a>
Mi
Volume:
38 ml
Pressure
200 bar
(maximum):
Temperature (maximum):
Appendix
.
lnconel-718
300 °C
m
m
1/
^
\
/
s.
\»,
\s-
Material:
T
co
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127
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Appendix
Leer
-
Vide
-
Empty
List of Publications
Publications which
originated
Amination of Diols and
from this thesis
Polyols
to
Acyclic Amines
Fischer, T. Mallat, A. Baiker
A.
Catal
Today, 1997, 37,
167
(Chapter 1)
Cobalt
Catalyzed Amination of 1,3-Propanediol in Supercritical
Fischer, M. Maciejewski, T. Bürgi, T. Mallat and A. Baiker
A.
J.
Ammonia
Catal., submitted
(Chapter 3)
Nickel-Catalyzed
C2
A.
-
Amination of
1,3-Propanediols Differently Substituted at
Position: Influence of Reactant Structure
on
Diamine Production
Fischer, T. Mallat and A. Baiker
J. Mol.
Catal, submitted
(Chapter 4)
Continuous Amination of
A.
Propanediols
in
Supercritical
Angew. Chem.,
(Chapter 5)
Int. Ed.
Eng.,
in press
Synthesis of 1,4-Diaminocyclohexane in Supercritical
A. Fischer, T. Mallat, A. Baiker
J. Catal., submitted
(Chapter 6)
Patents
Verfahren
zur
Herstellung
von
Aminen
Fischer, T. Mallat, A. Baiker, O. Werbitzky
Europ. Patent, Appl. No. 98-113-540.3 (21.7.1998)
A.
Ammonia
Fischer, T. Mallat, A. Baiker
Ammonia
130
Verfahren
zur
Herstellung
von
Diaminocyclohexanen
Fischer, T. Mallat, A. Baiker
Europ. Patent, (12.11.1998)
A.
Curriculum Vitae
Name
Achim Fischer
Date of birth
August 7, 1968
Place of birth
Baden-Baden
Nationality
German
Education
1975-1979
Primary School: Jestetten, Stuttgart and Waldshut
1980-1988
Grammar School: Rastatt and Oberkirch
1988-1989
Military Service:
1989-1995
Chemistry studies
1995-1998
Stetten
at the
Ph. D. Thesis under the
the
Laboratory
a.
k. M. and Pfullendorf
Universität Karlsruhe (TH)
supervision
of Technical
of Prof. Dr. A. Baiker at
Chemistry of the
ETH Zürich