EMERGING TECHNOLOGY FOR
P-XYLENE PRODUCTION
Ashim Ghosh* and Mohammad Shafiei
SABIC Technology Center - Houston
November 3, 2013
Presentation
PRESENTATION
OUTLINEPlan
 Introduction
 New p-Xylene Technology
•
Chemistry
•
Challenges
•
Catalyst Design
 SABIC Catalyst & Technology
 Summary
No. 1
P-XYLENE TECHNOLOGY

P-XYLENE
particularly in Asia & Middle East
[33 MM mt/y,
5.7% Growth]
MIXED-XYLENE
(18-24% PX)
MIXED-XYLENE
(84-93% PX)
TDP
PYROLYSIS
GASOLINE
CATALYTIC
REFORMATE
“On-purpose” p-X growth increasing rapidly,
STDP
Toluene
Disproportion
ation
>15%
PX only
Production
Technology
Toluene
Methylation
First Commercial (Sinopec)
Plant Nov 2012
>80%
Ghosh, SABIC - AIChE San Francisco 2013
No. 2
NEW TECHNOLOGY FOR P-XYLENE
CH3
CH3
CH3
+ CH3OH
+ H2O
Catalyst
(mixed-xylene, >84% p-Xylene)
1980’s
 Mobil tested modified ZSM-5 for toluene methylation
 DuPont tested crystalline silica (presumably high SAR ZSM-5)
 Research discontinued due to strategic reason and/or unattractive
economics
Recent Interest
 GTC bought catalyst right from IPCL, started piloting but discontinued for
unknown reasons
 Exxon-Mobil testing ZSM-5 catalyst for fluidized bed technology
 Sinopec developed the technology, commercial plant Dec 2012
Ghosh, SABIC - AIChE San Francisco 2013
No. 3
CHEMISTRY AND CHALLENGES
Possible Reactions over Zeolite Catalyst
 Methanol  ethylene, propylene (MTO reaction)
 Toluene  benzene, mixed-xylene (TDP)
 Toluene + Methanol  mixed-xylene (TM)
Reference: SRI PEP Review 83-1-1
40C8H10 + C9H12 + 4(CH3)2O + CO + 2H2 + 6CH4
41C6H5.CH3 + 100CH3OH
+ 2CO2 + 17.5C2H4 + 2C3H6 + 91H2O


Low methanol selectivity (40%)
Major byproduct – ethylene, propylene
Overall: 27.3 kcal/mol p-xylene
Technical Challenges
 Reduction of unselective conversion of methanol to C2= and C3=
 Improvement of catalyst stability
Ghosh - AIChE San Francisco 2013
No. 4
CATALYST DESIGN
+ CH3OH
Surface Reactions
+ CH2=CH2
CH3OH +
}
Inactivation or removal
of site will increase p-X
selectivity
Desirable
Pore Reactions
CH3OH
CH2=CH2 + CH3CH=CH2
 Increased shape selectivity can be obtained by diffusion control and by
inactivation or removal of external site
Ghosh - AIChE San Francisco 2013
No. 5
SABIC PREFORMED CATALYST
 P/ZSM-5 (P 9-10 wt.%)
 Relative zeolite crystallinity ~60%
 FWAl/EFWAl = 0.1-0.25
 Various P-species as identified by PNMR
27Al-NMR
EFWAl
 Medium strength acid site (NH3-TPD
peaks at 300 and 400 C)
FWAl
 SA 180 20 m2/g, PV = 0.13 0.02 ml/g
ZSM-5
P/ZSM-5
ppm
Ghosh - AIChE San Francisco 2013
No. 6
STABLE CATALYST PERFORMANCE
20
550
18
16
500
14
450
12
% Toluene Conversion
10
Delta P, psig
8
400
Bed Inlet Temp, °C
Bed Inlet Temp
Conversion/ ∆ P
Unit Upset
6
4
350
2
0
300
0
200
400
600
800
1000
1200
Time on Stream, h
Ghosh - AIChE San Francisco 2013
No. 7
TOLUENE METHYLATION BENCH UNIT
•
•
Catalyst formed with binder, cylindrical shaped (1/16-inch) catalyst
Catalyst scaled up to 1 ton size production
Vaporizer
Toluene
580 kg PX/Yr
Vaporizer
Methanol
Vaporizer
Water
FS-1
FS-2
FS-3
Hydrogen
3rd Reactor
2nd Reactor
240 g/h
47
49
19
1st Reactor
Toluene
Methanol
Water
Hydrogen
g/h
Toluene 169
Methanol 5.0
Water
72.5
H2
16.0
C4- Gas
7.0
PX
72.5
MX
3.5
OX
1.7
C9+ Arom 3.5
Product
Stream (PS)
Ghosh - AIChE San Francisco 2013
No. 8
1.2
60
1.0
50
0.8
40
0.6
30
g pX per g Toluene Converted
0.4
20
g mixed-X per g Toluene Converted
g C9 per g Toluene Converted
 Semicommercial
catalyst
 Catalyst
tested 5
months
% Toluene Conversion
g Product/g Toluene Converted
SCALED-UP CATALYST STABILITY
Toluene Conversion
0.2
10
0.0
0
0
20
40
60
80
100
120
140
160
Days on Stream
Ghosh - AIChE San Francisco 2013
No. 9
1.2
60
1
50
0.8
40
0.6
30
0.4
20
p-XYLENE
Mixed-XYLENE
C9+ Aromatics
Toluene Conversion
0.2
% Toluene Conversion
g Product/g Toluene Converted
CATALYST AT VARIOUS CONDITIONS
 Semi-commercial
catalyst
 Catalyst tested 18
months
 23 Catalyst
Regenerations
 Accelerated aging
10
0
0
0
100
200
300
400
500
600
Days on Stream
Ghosh - AIChE San Francisco 2013
No. 10
TECHNOLOGY FEATURE





ZSM-5 based robust catalyst system
Fixed-bed multi-reactor, methanol staged
Pressure 20-200 psi, temperature 500-700 C
Cofeed H2 and steam
H2/(Toluene+Methanol) 3-8 molar
 Toluene Selectivity to
•
•
•
Mixed-Xylene 90-96%,
C9+ 4-10%
p-Xylene in mixed-X 85-95%
 Trace benzene, no EB
 Light HC, mostly C2-C3 olefins
 Technology is economically competitive
Ghosh - AIChE San Francisco 2013
No. 11
SUMMARY
 Toluene Methylation is a niche technology for p-xylene
production
 SABIC developed ZSM-5 based catalyst for TM
technology
 Catalyst scale-up demonstrated
 Catalyst performance demonstrated bench scale with
multi-reactor system with gas recycle
 Demonstrated stable catalyst performance with multiple
regeneration
 SABIC would consider partners for commercialization of
the technology
Ghosh - AIChE San Francisco 2013
No. 12