Enhanced Acidic and Catalytic Properties
of Modified Sulfonic Acid Resins
D R Brown, H E Cross and P F Siril
Department of
Chemical and Biological Chemistry,
University of Huddersfield
1 Homogeneous Acid Catalysts:
AlCl3, H2SO4, HF - DISPOSAL!!
2 Heterogeneous Acid Catalysts
A) Rigid Solid Acids
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
OO
O O
O O
O O
1 nm pores X
10 nm pores OK
B) Non-Rigid Solid Acids
Solvent
Gel
e.g. Sulfonated Polystyrene Resins
SO 3 H SO 3 H
Sulfonated polystyrene
SO3H
[H+]
4.9 mmol g-1
SO3H
SO3H
CH3
SO3H
p-toluenesulfonic
acid
SO3H
[H+]
2.9 mmol g-1
SO3H
SO3H
SO2
SO3H
SO3H
SO3H
SO3H
SO3H
[H+]
5.4 mmol g-1
Surface Acidity Characterisation
Base Temperature Programmed Desorption
Base Adsorption Calorimetry
NMR – direct or with probe (eg triethylphosphine)
IR – direct or with probe
Hammett Indicators (eg dicinnamalacetone pKa -3.0
benzalacetophenone pKa -5.6)
Enthalpy of NH3 Adsorption (as a measure of acid site strength)
NH3 + Solid-H
∆Hoads (NH3) = -150 kJ mol-1
NH4+…..Solid-
Enthalpy of NH3 Adsorption (as a measure of acid site strength)
NH3 + Solid-H
∆Hoads (NH3) = -150 kJ mol-1
-∆Ho(PA Solid-)
Solid-
+
∆Ho(Binding)
Solid- + NH4+
H+
∆HoPA(NH3) = - 860 kJ mol-1
H+ + NH3
NH4+…..Solid-
NH4+
40
30
Heat Flow /mW
Heat
flow
/mW
20
10
0
5000
10000
15000
-10
20000
25000
30000
35000
Time /s
-20
Time /s
-130
-125
-120
(NH3)/
kJ mol-1
Sulfonated
Polystyrene
Resins
CT-275,
-1
ads
Hads (NH3) /kJ mol
ΔHo
5.40 mmol g
-115
-1
CT-375,
5.52 mmol g
-1
CT-175,
-110
4.90 mmol g
-1
-105
SP21-51,
-100
1.82 mmol g
D4034,
0.74 mmol g
-1
AMB15,
-1
4.74 mmol g
-1
-95
-90
0.0
1.0
2.0
3.0
4.0
Average Coverage /mmol g
5.0
-1
NH3 Coverage /mmol g-1
6.0
SO 3 H SO 3 H
Molar enthalpy of adsorption of NH3 vs. amount of NH3 adsorbed
on macroporous sulfonated polystyrene beads at 100 OC
-130
-125
-120
Hads (NH3) /kJ mol
-1
CT-275,
5.40 mmol g
-115
-1
CT-375,
5.52 mmol g
-1
CT-175,
-1
4.90 mmol g
-110
-105
SP21-51,
-100
1.82 mmol g
D4034,
0.74 mmol g
-1
AMB15,
-1
4.74 mmol g
-1
-95
-90
0.0
1.0
2.0
3.0
4.0
-1
Average Coverage /mmol g
5.0
6.0
-130
-125
-120
Hads (NH3) /kJ mol
-1
CT-275,
5.40 mmol g
-115
-1
CT-375,
5.52 mmol g
-1
CT-175,
-1
4.90 mmol g
-110
-105
SP21-51,
-100
1.82 mmol g
D4034,
-1
0.74 mmol g
-1
AMB15,
4.74 mmol g
-95
-1
-90
0.0
1.0
2.0
3.0
4.0
5.0
6.0
-1
Average Coverage /mmol g
OH
Catalyst
H
+
(-H2O)
Reaction
Rate
-2
/10 μmol
-1 -1
converted g h
+
O
Specific
Activity
Selectivity/
[Hexene] [Ether]
-3
/10 μmol converted
-1
-1
mmol (-SO3H) h
----------------------------------------------------------------------------------------------------------------------Amb15 ([H+] = 4.7 mmol g-1)
2.5
5.3
1.4
CT-175 ([H ] = 4.9 mmol g )
2.3
4.7
1.0
CT-275 ([H+] = 5.4 mmol g-1)
7.6
14.1
1.4
+
-1
Catalyst
Reaction
Rate
-2
/10 μmol
converted g-1 h-1
Specific
ACTIVITY
Selectivity/
[Hexene] [Ether]
-3
/10 μmol converted
mmol-1(-SO3H) h-1
---------------------------------------------------------------------------------------------------------------------Amb15 ([H+] =
4.7 mmol g )
2.5
5.3
1.4
CT-175 ([H+] =
4.9 mmol g )
2.3
4.7
1.0
CT-275 ([H+] =
5.4 mmol g )
7.6
14.1
1.4
-1
-1
-1
H
II
O
I
O
O_
O
O
H
H
O+
H
_
O
O
S
S
O
H
H
O
H
O
O
O
O+
H
H
H
S
H
O
H
O
O
S
S
O
H
H
H
O
O
S
O
O
O
O
H
O
H
H
S
O
O
S
O
O
H
III
NH3 Adsorption from He
1
1.3
-0.1
1.1
-0.2
4
-0.3
6
Amb15 Sulfonated
polystyrene
A
6
0.9
0.8
9
0.7
st
0.6
11
0.5
13
0.4
Heat flow / mW
1.2
1.0
Heat flow / mW
1
0.0
th
-0.4
10
-0.5
B
-0.6
-0.7
-0.8
th
-0.9
0.3
H-ZSM5
-1.0
th
th
0.2
Exo
-1.1
0.1
-1.2
th
0.0
0
200
400
th
Endo
-1.3
600
Time / s
800
1000
1200
0
200
400
600
800
1000
1200
Time / s
The shape of the calorimeter signal changes
as the solid acid becomes progressively saturated
- Signals for pulses 1, 6, 9, 11 and 13.
Solvent
Gel
“Internal Solution”
(m)
a)
Aqueous Titration
Microcalorimetry
- Hydrated Sulfonated
Resins with
0.1 M NaOH solution
2
Heat Flow
/mW
0
0
500
Time/min
b)
NaOH / mmole
0
0.1
0
-4
Δ H neut / kJ
o
-8
-12
ΔH
neut
= - 58.0 kJ mol-1
0.2
Liquid Titration Calorimetry
ΔHOneut. (NaOH)aq- Sulfonated Polystyrene Resins Dependence on Level of Sulfonation
ΔHoneut NaOH(aq) / kJ mol -1
62
60
58
56
54
52
50
0
1
2
3
4
5
Cation Exchange Capacity / mmol g-1
6
Liquid Titration Calorimetry Sulfonated Resins
ΔHOneut. (NaOH)aq- vs Concn “Internal Solution”
58
Gel resin
Gel resins
-1
ΔH neut /kJ mol
ΔHOneut.
(NaOH)aq
/kJ mol-1
54
50
0
1
2
3
4
Internal Solution Concentration /mol kg
5
-1
(water)
6
Concn “Internal Solution” /mol kg-1
Liquid Titration Calorimetry Sulfonated Resins
ΔHOneut. (NaOH)aq- vs Concn “Internal Solution”
58
Gel resins
/kJ mol
ΔH
ΔHOneut.
(NaOH)aq
/kJ mol-1
neut
-1
HCl
54
p-TsOH
50
0
2
4
Internal Solution Concentration /mol kg
6
-1
(water)
Concn “Internal Solution” /mol kg-1
FT-Raman Spectroscopy
- Hydrated Sulfonated Resins (H+ Form)
-SO31035 cm-1
Polystyrene 97% sulfonated
-SO3H
1127 cm-1
Polystyrene 70% sulfonated
Polystyrene 43% sulfonated
Polystyrene 24% sulfonated
Degree of Acid Dissociation vs Concn of Internal Solution
- FT-Raman Data
100
Et-SO3H
p-TsOH
α /%
50
%
Dissociation
Gel resins
0
0
2
4
Internal Solution Concentration /mol kg-1
6
Conclusions
Sulfonated Polystyrene (Hydrated)
High sulfonation
= reduced acid dissocation
= increased acid strength
= higher catalytic activity
Effective acid catalysts in water
Enhanced acid strength/activity not seen in
other supported sulfonic acids
Sulfonated polystyrene
SO3H
Sulfonated silica
SO3H
SO3H
O
Et
Si
FF
FF
F
OH
F
Si
F F
F
F
F
F
O
F
F
O
OH
OH
Si
Si
Si
Si
O
F
CF3
O
F
F
SO3H
F
O
O
Fluorinated polyethylene – “Nafion”
O
O
O
+
O
H
H2O
Catalyst
O
+
OH
∆ Honeut.
+
OH
Acid Site
Concentration
/mmol g-1
(aq. NaOH)
/kJ mol-1
Polystyrene-SO3H
AMB-15
AMB-35
4.74
5.4
-58.3
-61.2
2.5
4.6
Silica-SO3H
MCM41-1
MCM41-2
MCM41-3
SBA-15
1.2
1.31
2.8
1.15
-54.6
-54.9
-54.5
-54.9
2.7
2.7
2.7
2.6
-
-52.8
-52.4
Aqueous Strong Acids
0.1 mol dm-3 HCl
0.5 mol dm-3 p-TsOH
Initial Rate (TON)
/mol (acid-mol)-1 min-1
Physical characteristics of Amberlyst resin powders
Cation Surface
Pore Average pore size
exchange areab volumec /nm
capacitya /m2 g-1 /cm3 g-1
/mmol g-1
Sulfonated
polystyrene
resin
(≤ 125 μm)
Amberlyst 70
Amberlyst 15
Amberlyst 35
a
b
c
2.55
4.7
5.2
1.0
37.3
40.7
0.002
0.203
0.218
29.3
24.0
24.2
Rohm and Haas data.5
BET adsorption isotherm using N2.
Total volume of pores with diameters 1.7-300 nm (BJH).
Physical characteristics of Amberlyst resin powders
Cation Surface
Pore Average pore size
exchange areab volumec /nm
capacitya /m2 g-1 /cm3 g-1
/mmol g-1
Sulfonated
polystyrene
resin
(≤ 125 μm)
Amberlyst 70
Amberlyst 15
Amberlyst 35
a
b
c
2.55
4.7
5.2
1.0
37.3
40.7
0.002
0.203
0.218
29.3
24.0
24.2
Rohm and Haas data.5
BET adsorption isotherm using N2.
Total volume of pores with diameters 1.7-300 nm (BJH).
Physical characteristics of Amberlyst resin powders
Cation Surface
Pore Average pore size
exchange areab volumec /nm
capacitya /m2 g-1 /cm3 g-1
/mmol g-1
Sulfonated
polystyrene
resin
(≤ 125 μm)
Amberlyst 70
Amberlyst 15
Amberlyst 35
a
b
c
2.55
4.7
5.2
1.0
37.3
40.7
0.002
0.203
0.218
29.3
24.0
24.2
Rohm and Haas data.5
BET adsorption isotherm using N2.
Total volume of pores with diameters 1.7-300 nm (BJH).
-ΔH0ads/adsorbed NH3 for Amberlyst resins at 100 oC by
adsorption calorimetry, sample size 5 mg
-ΔH0ads/adsorbed NH3 for Amberlyst resins at 100 oC by
adsorption calorimetry, sample size 20 mg
Acidity data by NH3 adsorption calorimetry at 100 oC.
Sulfonated
resin
Amberlyst 70
Amberlyst 15
Amberlyst 35
Nafion NR50
a
b
c
Average
-ΔH0adsa
/kJ mol-1
117 ± 2
110 ± 2
117 ± 2
158 ± 4
Total NH3
adsorbedb
/mmol g-1
1.65 ± 0.05
4.70 ± 0.10
5.20 ± 0.10
0.85 ± 0.10
Cation exchange
capacityc
/mmol g-1
2.55
4.7
5.2
0.8
Average up to coverage where ΔH0ads falls below -80 kJ mol-1.
coverage where ΔH0ads falls numerically below -80 kJ mol-1.
Rohm and Haas data.5
Acidity data by NH3 adsorption calorimetry at 100 oC.
Sulfonated
resin
Amberlyst 70
Amberlyst 15
Amberlyst 35
Nafion NR50
a
b
c
Average
-ΔH0adsa
/kJ mol-1
117 ± 2
110 ± 2
117 ± 2
158 ± 4
Total NH3
adsorbedb
/mmol g-1
1.65 ± 0.05
4.70 ± 0.10
5.20 ± 0.10
0.85 ± 0.10
Cation exchange
capacityc
/mmol g-1
2.55
4.7
5.2
0.8
Average up to coverage where ΔH0ads falls below -80 kJ mol-1.
coverage where ΔH0ads falls numerically below -80 kJ mol-1.
Rohm and Haas data.5
Acidity data by NH3 adsorption calorimetry at 100 oC.
Sulfonated
resin
Amberlyst 70
Amberlyst 15
Amberlyst 35
Nafion NR50
a
b
c
Average
-ΔH0adsa
/kJ mol-1
117 ± 2
110 ± 2
117 ± 2
158 ± 4
Total NH3
adsorbedb
/mmol g-1
1.65 ± 0.05
4.70 ± 0.10
5.20 ± 0.10
0.85 ± 0.10
Cation exchange
capacityc
/mmol g-1
2.55
4.7
5.2
0.8
Average up to coverage where ΔH0ads falls below -80 kJ mol-1.
coverage where ΔH0ads falls numerically below -80 kJ mol-1.
Rohm and Haas data.5
Acidity data by NH3 adsorption calorimetry at 100 oC.
Sulfonated
resin
Amberlyst 70
Amberlyst 15
Amberlyst 35
Nafion NR50
a
b
c
Average
-ΔH0adsa
/kJ mol-1
117 ± 2
110 ± 2
117 ± 2
158 ± 4
Total NH3
adsorbedb
/mmol g-1
1.65 ± 0.05
4.70 ± 0.10
5.20 ± 0.10
0.85 ± 0.10
Cation exchange
capacityc
/mmol g-1
2.55
4.7
5.2
0.8
Average up to coverage where ΔH0ads falls below -80 kJ mol-1.
coverage where ΔH0ads falls numerically below -80 kJ mol-1.
Rohm and Haas data.5
H3C
CH3
CH2
CH3
CH3
+
Limonenes
CH3
CH2OH
+
CH3
CH2
CH3
+
H2O
Reaction rate data
Isomerisation of α-pinene
(conversion at 100 oC)
Benzylation of toluene (conversion
of benzyl alcohol at 80 oC)
Initial turnover frequency
per acid site /h-1
Initial turnover frequency
per acid site /h-1
Amberlyst 70
12
17
Amberlyst 15
47
13
Amberlyst 35
112
19
Nafion NR
1325
33
Catalyst
H3C
CH3
CH2
CH3
CH3
+
Limonenes
CH3
CH2OH
+
CH3
CH2
CH3
+
H2O
Reaction rate data
Isomerisation of α-pinene
(conversion at 100 oC)
Benzylation of toluene (conversion
of benzyl alcohol at 80 oC)
Initial turnover frequency
per acid site /h-1
Initial turnover frequency
per acid site /h-1
Amberlyst 70
12
17
Amberlyst 15
47
13
Amberlyst 35
112
19
Nafion NR
1325
33
Catalyst
H3C
CH3
CH2
CH3
CH3
+
Limonenes
CH3
CH2OH
+
CH3
CH2
CH3
+
H2O
Reaction rate data
Isomerisation of α-pinene
(conversion at 100 oC)
Benzylation of toluene (conversion
of benzyl alcohol at 80 oC)
Initial turnover frequency
per acid site /h-1
Initial turnover frequency
per acid site /h-1
Amberlyst 70
12
17
Amberlyst 15
47
13
Amberlyst 35
112
19
Nafion NR
1325
33
Catalyst
H3C
CH3
CH2
CH3
CH3
+
Limonenes
CH3
CH2OH
+
CH3
CH2
CH3
+
H2O
Reaction rate data
Isomerisation of α-pinene
(conversion at 100 oC)
Benzylation of toluene (conversion
of benzyl alcohol at 80 oC)
Initial turnover frequency
per acid site /h-1
Initial turnover frequency
per acid site /h-1
Amberlyst 70
12
17
Amberlyst 15
47
13
Amberlyst 35
112
19
Nafion NR
1325
33
Catalyst
Hydrothermal stability of Amberlyst 70 compared to Amberlysts 15, 35 and 36
Acid Site concentration after 6 h hydrothermal
5.5
5.0
Amberlyst 35
Acid Sites (meq/g)
4.5
Amberlyst 15
4.0
3.5
3.0
2.5
Amberlyst 70
2.0
1.5
1.0
0.5
0.0
0
50
100
150
o
Temperature ( C)
200
T
o t a l
a c id
s it e
c o n c e n t r a t io n
a f t e r
t h e r m
a l
t r e a t m
e n t
( 2 0 0 ° C
% of original total acid concn
1 0 0
8 0
A
3 5
R
E
A
7 0
A
1 5
B
L U
E
D
6 0
B
L A
C
K
4 0
2 0
0
0 . 0
0 . 2
0 . 4
0 . 6
lo g [ t ]
0 . 8
1 . 0
1 . 2
1 . 4
)
S
u lf u r
c o n t e n t
b y
X
R
F
-
2 0 0 ° C
h y d r o t h e r m
a l
Sulfur content (% of original)
1 0 0
8 0
6 0
4 0
A
3 5
A
1 5
R
E
D
A
2 0
B
L A
C
7 0
B
L U
E
K
0
0 . 0
0 . 2
0 . 4
0 . 6
lo g [ t ]
0 . 8
1 . 0
1 . 2
1 . 4
Acknowledgements
EPSRC
DTI
Royal Society
Purolite International Ltd
BP
University of Huddersfield
Howell Edwards, University of Bradford
Graham Fuller
Colin Park
Prem Siril
Said Koujout
Hannah Cross
Flow adsorption calorimeter
1% NH3 in He
Automated gas sampling valve
Differential Scanning Calorimeter
(flow-through
cell)
He carrier
Mass spec
α-pinene conversion to camphene at 100 oC
H3C
CH3
CH2
CH3
CH3
+
Limonenes
CH3
100
Nafion powder
155 kJ/mol
1.0 mmol/g
80
Amberlyst 35 powder
% conversion
125 kJ/mol
5.0 mmol/g
60
40
Silica-SO3H
Amberlyst
15 powder
135 kJ/mol
1.0 mmol/g
20
0
0
20
40
60
80
100
120
140
Time / min
160
180
200
220
240
∆Hoads (NH3) at 100 oC for supported sulfonic acids
160
Nafion
140
Amberlyst 35
100
Amberlyst 15
80
ΔH
0
/ kJ mol
ads
-1
120
60
MCM-41-SO3 H
(Silica –SO3H)
40
20
0
1
2
3
4
Surface coverage / mmol g
5
-1
6
Calorimeter signal
Time /s
Mass spec signal
(m/e 15)
Heat Flow / mW
Output sensitive to the RATE of adsorption
Increased probe gas flow rate over sample
(reduced contact time)
0.2
Typical data for higher NH3 flow rate
-0.2
-0.6
heat
-1.0
-1.4
-1.8
17500
22500
27500
-9
37500
Time / s
1.2x10
Intensity of m/z - 15 /
arbitary units
32500
Falling STICKING
Factor
-10
8.0x10
-10
4.0x10
0.0
17500
22500
27500
32500
Time / s
37500
MS signal
Acknowledgements
Prem Siril
Said Koujout
Mark Hart
Graham Fuller
Howell Edwards (Bradford)
Adsorption Calorimetry
Gas/Vapour on Solid
Capacities of
adsorbent/catalysts
Adsorption enthalpies
Adsorption rates
Desorption
Adsorption Calorimetry
Gas/Vapour on Solid
Capacities of
adsorbent/catalysts
Adsorption enthalpies
Adsorption rates
Desorption
Strength/abundance of
catalytic sites
Calorimeter signal
Time /s
Mass spec signal
(m/e 15)