U.S. patent application number 10/465119 was filed with the patent office on 2004-02-12 for manufacture of xylenes from reformate.
Invention is credited to Buchanan, John Scott, Crane, Robert A., Dakka, Jihad M., Feng, Xiaobing, Laccino, Larry L., Luo, Shifang L., Mohr, Gary D..
Application Number | 20040030210 10/465119 |
Document ID | / |
Family ID | 30000498 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040030210 |
Kind Code |
A1 |
Mohr, Gary D. ; et
al. |
February 12, 2004 |
Manufacture of xylenes from reformate
Abstract
A process is provided for the production of xylenes from
reformate. The process is carried out by methylating the benzene,
toluene, or both present in the reformate to produce a resulting
product having a higher xylenes content than the reformate. Greater
than equilibrium amounts of para-xylene can be produced by the
process.
Inventors: |
Mohr, Gary D.; (Houston,
TX) ; Buchanan, John Scott; (Lambertville, NJ)
; Crane, Robert A.; (Lumberton, TX) ; Dakka, Jihad
M.; (Whitehouse Station, NJ) ; Feng, Xiaobing;
(Houston, TX) ; Laccino, Larry L.; (Seabrook,
TX) ; Luo, Shifang L.; (Pittsford, NY) |
Correspondence
Address: |
ExxonMobil Chemical Company
Law Technology
P. O. Box 2149
Baytown
TX
77522-2149
US
|
Family ID: |
30000498 |
Appl. No.: |
10/465119 |
Filed: |
June 18, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60389981 |
Jun 19, 2002 |
|
|
|
Current U.S.
Class: |
585/446 ; 208/62;
208/67; 585/322; 585/323 |
Current CPC
Class: |
C07C 2529/70 20130101;
C07C 2529/85 20130101; C07C 2521/18 20130101; C07C 2521/08
20130101; C07C 2/86 20130101; C07C 2529/40 20130101; C07C 2521/02
20130101; C07C 2529/65 20130101; C10G 2400/30 20130101; C07C
2527/14 20130101; C07C 2521/06 20130101; C07C 2523/02 20130101;
C07C 2523/74 20130101; C07C 2523/18 20130101; C07C 2523/34
20130101; C07C 2523/40 20130101; C07C 2523/10 20130101; C07C 2/86
20130101; C07C 15/08 20130101 |
Class at
Publication: |
585/446 ;
585/322; 585/323; 208/62; 208/67 |
International
Class: |
C07C 002/64; C10G
063/02 |
Claims
What is claimed is:
1. A process for producing xylenes from reformate, which process
comprises: (a) providing a reformate containing benzene, toluene or
mixtures thereof in methylation reaction zone; and, (b) methylating
at least a portion of the benzene, toluene, or mixtures thereof
present in said reformate in said methylation reaction zone with a
methylating agent under vapor phase conditions effective for the
methylation and in the presence of a catalyst effective for the
methylation to produce a resulting product having a higher xylenes
content than said reformate.
2. A process recited in claim 1, wherein said reformate is formed
in an aromatization zone and at least a portion of the reformate
formed in said aromatization zone is transferred to said
methylation reaction zone.
3. The process recited in claim 2, wherein said reformate is
transferred to said methylation reaction zone without interstage
separation.
4. The process recited in claim 1, wherein a hydrocarbon stream
comprising benzene, toluene, or mixtures thereof is added to said
reformate present in said methylation reaction zone.
5. The process recited in claim 1, wherein hydrogen is supplied to
said methylation reaction zone.
6. The process recited in claim 1, wherein said conditions include
a temperature from about 300.degree. C. to about 700.degree. C., a
pressure from about 1 to 1000 psig, a weight hourly space velocity
of between about 0.1 and about 200, a molar ratio of methylating
agent to toluene between about 0.1:1 to about 20:1 and a weight
hourly space velocity of between about 0.1 and about 200.
7. The process recited in claim 6, wherein said catalyst comprises
an intermediate pore size molecular sieve.
8. The process recited in claim 7, wherein said intermediate pore
size molecular sieve is selected from the group consisting of AEL,
AFI, MWW, MFI, MEL, MFS, MEI, MTW, EUO, MTT, HEU, FER, and TON.
9. The process recited in claim 7, wherein said intermediate pore
size molecular sieve is selected from the group consisting of
ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38,
ZSM-48, ZSM-50, ZSM-57, MCM-22, MCM-49, MCM-56, and SAPO-11.
10. The process recited in claim 9, wherein said catalyst further
comprises at least one hydrogenation/dehydrogenation metal.
11. The process recited in claim 10, wherein said at least one
hydrogenation/dehydrogenation metal is a Group VIII metal.
12. The process recited in claim 9, wherein said molecular sieve is
MFI or MEL.
13. The process recited in claim 7, wherein said molecular sieve
further comprises a selectivating agent.
14. The process recited in claim 13, wherein said selectivating
agent is selected from the group consisting of silica, coke,
phosphorus, alkaline earth metal oxide, rare earth metal oxides,
lanthanum oxide, boron oxide, titania, antimony oxide, manganese
oxide, titania and mixtures thereof.
15. The process recited in claim 14, wherein said molecular sieve
is ZSM-5.
16. The process recited in claim 7, wherein said methylating agent
is selected from the group consisting of methanol, dimethylether,
methylchloride, methylbromide, methylcarbonate, acetaldehyde,
dimethoxyethane, acetone, and dimethylsulfide.
17. The process recited in claim 7, wherein said methylating agent
is injected into said methylation reaction zone through more than
one feed point.
18. The process recited in claim 7, wherein said methylating agent
is formed from synthesis gas.
19. The process recited in claim 1, wherein said reformate is
formed by the catalytic reforming of naphtha.
20. The process recited in claim 19, wherein said reforming is
carried out a temperature in the range of from about 427.degree. C.
to about 565.degree. C., a pressure in the range of from about 50
psig (446 kPa) to about 500 psig (3,549 kPa), a mole ratio of
hydrogen to hydrocarbons from 1:1 to 10:1 and a liquid hour space
velocity of between 0.3 and 5 and in the presence of a catalyst
suitable for the catalytic reforming of naphtha.
21. The process recited in claim 20, wherein the catalyst used in
said reforming is a bifunctional catalyst.
22. The process recited in claim 21, wherein said bifunctional
catalyst is an acidic reforming catalyst comprising a metallic
oxide support and a Group VIII metal.
23. The process recited in claim 22, wherein said metallic oxide
support of said bifunctional catalyst is silica or alumina and said
Group VIII metal is platinum.
24. The process recited in claim 22, wherein said bifunctional
catalyst further comprises a metal promoter.
25. The process recited in claim 24, wherein said metal promoter is
tin, rhenium, or mixtures thereof.
26. The process recited in claim 20, wherein the catalyst used in
said reforming is a monofunctional catalyst.
27. The process recited in claim 26, wherein said monofunctional
catalyst comprises a molecular sieve selected from the group
consisting of zeolite L, zeolite X, zeolite Beta, zeolite Y, and
ETS-10.
28. The process recited in claim 27, wherein said monofunctional
catalyst further comprises from about 0.1 to about 5% of at least
one hydrogenation/dehydrogenation metal selected from the group
consisting of a Group VIII metal, Group VIIB metal, or mixtures
thereof, based on the weight of the catalyst.
29. The process recited in claim 25, wherein said monofunctional
catalyst further comprises a metal promoter and said Group VIII
metal is platinum.
30. The process recited in claim 1, wherein said reformate is
formed by the dehydrocyclo-oligomerization of C.sub.2-C.sub.5
aliphatics.
31. The process recited in claim 30, wherein a catalyst comprising
an intermediate pore size molecular sieve is used in the
dehydrocyclo-oligomerization of C.sub.2-C.sub.5 aliphatics.
32. The process recited in claim 31, wherein said intermediate pore
size molecular sieve is selected from the group consisting of AEL,
AFI, MWW, MFI, MEL, MFS, MEI, MTW, EUO, MTT, HEU, FER, and TON.
33. The process recited in claim 31, wherein said intermediate pore
size molecular sieve is selected from the group consisting of
ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38,
ZSM-48, ZSM-50, ZSM-57, MCM-22, MCM-49, MCM-56, and SAPO-11.
34. The process recited in claim 31, wherein said molecular sieve
further comprises a selectivating agent.
35. The process recited in claim 34, wherein said selectivating
agent is selected from the group consisting of silica, coke,
phosphorus, alkaline earth metal oxide, rare earth metal oxides,
lanthanum oxide, boron oxide, titania, antimony oxide, manganese
oxide, titania and mixtures thereof.
36. The process recited in claim 35, wherein said molecular sieve
is MFI.
37. The process recited in claim 36, wherein said molecular sieve
is ZSM-5.
38. The process recited in claim 1, wherein said reformate is
formed by the cracking of hydrocarbons.
39. The process recited in claim 38, wherein said cracking of
hydrocarbons is accomplished in a catalytic cracking process.
40. The process recited in claim 38, wherein said cracking of
hydrocarbons is accomplished in a steam cracking process.
41. The process recited in claim 1, wherein at least 7 weight
percent of the benzene and/or toluene present in said reformate is
converted to xylenes.
42. The process recited in claim 13, wherein the resulting product
contains greater than equilibrium amounts of para-xylene.
43. The process recited in claim 13, wherein the resulting product
contains more than 80 weight percent of para-xylene based on the
total weight of the xylenes produced by said process.
44. An integrated process for upgrading a petroleum naphtha which
comprises the steps of: (a) aromatizing naphtha in an aromatization
zone under aromatization conditions and in the presence of a
catalyst effective for the aromatization of the naphtha to produce
a reformate containing benzene, toluene or mixtures thereof; (b)
transferring at least a portion of said reformate from said
aromatization zone to a methylation reaction zone; and (c)
methylating in said methylation reaction zone at least a portion of
the benzene, toluene, or mixtures thereof present in said reformate
with a methylating agent under conditions effective for the
methylation and in the presence of a catalyst effective for the
methylation to produce a resulting product having a higher xylenes
content than said reformate; wherein said reformate is transferred
from said aromatization zone to said methylation reaction zone
without interstage separation.
45. The process recited in claim 44, wherein the methylation
reaction is carried out in vapor phase.
46. The process recited in claim 44, wherein said aromatization
zone and methylation reaction zone are in series flow
arrangement.
47. The process recited in claim 44, wherein a hydrocarbon stream
comprising benzene, toluene, or mixtures thereof is added to said
reformate present in said methylation reaction zone.
48. The process recited in claim 44, wherein hydrogen is supplied
to said methylation reaction zone
49. The process recited in claim 45, wherein said methylation is
carried out at a temperature from about 300.degree. C. to about
700.degree. C., a pressure from about 1 to 1000 psig, a weight
hourly space velocity of between about 0.1 and about 200, a molar
ratio of methylating agent to toluene between about 0.1:1 to about
20:1 and a weight hourly space velocity of between about 0.1 and
about 200.
50. The process recited in claim 49, wherein said catalyst in said
methylation zone comprises an intermediate pore size molecular
sieve.
51. The process recited in claim 50, wherein said intermediate pore
size molecular sieve is selected from the group consisting of AEL,
AFI, MWW, MFI, MEL, MFS, MEI, MTW, EUO, MTT, HEU, FER, and TON.
52. The process recited in claim 50, wherein said intermediate pore
size molecular sieve is selected from the group consisting of
ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38,
ZSM-48, ZSM-50, ZSM-57, MCM-22, MCM-49, MCM-56, and SAPO-11.
53. The process recited in claim 52, wherein said catalyst further
comprises at least one hydrogenation/dehydrogenation metal.
54. The process recited in claim 53, wherein said at least one
hydrogenation/dehydrogenation metal is a Group VIII metal.
55. The process recited in claim 52, wherein said molecular sieve
further comprises a selectivating agent.
56. The process recited in claim 55, wherein said selectivating
agent is selected from the group consisting of silica, coke,
phosphorus, alkaline earth metal oxide, rare earth metal oxides,
lanthanum oxide, boron oxide, titania, antimony oxide, manganese
oxide, titania and mixtures thereof.
57. The process recited in claim 56, wherein said molecular sieve
is MFI or MEL.
58. The process recited in claim 44, wherein said aromatization is
carried out a temperature in the range of from about 427.degree. C.
to about 565.degree. C., a pressure in the range of from about 50
psig (446 kPa) to about 500 psig (3,549 kPa), a mole ratio of
hydrogen to hydrocarbons from 1:1 to 10:1 and a liquid hour space
velocity of between 0.3 and 5.
59. The process recited in claim 58, wherein the catalyst used in
said reforming is a bifunctional catalyst.
60. The process recited in claim 59, wherein said bifunctional
catalyst is an acidic reforming catalyst comprising a metallic
oxide support and a Group VIII metal.
61. The process recited in claim 60, wherein said metallic oxide
support of said bifunctional catalyst is silica or alumina and said
Group VIII metal is platinum.
62. The process recited in claim 60, wherein said bifunctional
catalyst further comprises a metal promoter.
63. The process recited in claim 62, wherein said metal promoter is
tin, rhenium, or mixtures thereof.
64. The process recited in claim 53, wherein the catalyst used in
said reforming is a monofunctional catalyst.
65. The process recited in claim 64, wherein said monofunctional
catalyst comprises a molecular sieve selected from the group
consisting of zeolite L, zeolite X, zeolite Beta, zeolite Y, and
ETS-10.
66. The process recited in claim 65, wherein said monofunctional
catalyst further comprises from about 0.1 to about 5% of at least
one hydrogenation/dehydrogenation metal selected from the group
consisting of a Group VIII metal, Group VIIB metal, or mixtures
thereof, based on the weight of the catalyst.
67. The process recited in claim 66, wherein said monofunctional
catalyst further comprises a metal promoter and said Group VIII
metal is platinum.
68. The process recited in claim 44, wherein said methylating agent
is selected from the group consisting of methanol, dimethylether,
methylchloride, methylbromide, methylcarbonate, acetaldehyde,
dimethoxyethane, acetone, and dimethylsulfide.
69. The process recited in claim 44, wherein said methylating agent
is injected into said methylation reaction through more than one
feed point.
70. The process recited in claim 44, wherein said methylating agent
is formed from synthesis gas.
71. The process recited in claim 55, wherein the resulting product
contains greater than equilibrium amounts para-xylene.
72. The process recited in claim 44, wherein at least 7 weight
percent of the benzene and/or toluene present in said reformate is
converted to xylenes.
73. The process recited in claim 55, wherein the resulting product
contains more than 60 weight percent of para-xylene based on the
total weight of the xylenes produced in said methylation reaction
zone by the methylation of said benzene, toluene, or mixtures
thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/389,981, filed Jun. 19, 2002, which is hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a process for producing xylenes
from reformate by methylating benzene and/or toluene present in the
reformate to produce xylenes.
[0004] 2. Description of the Prior Art
[0005] Most aromatics production is based on the recovery of
aromatics derived from catalytic reforming of naphtha. That
process, using a feed containing a C.sub.6+ hydrocarbons, typically
produces a reformate comprised of C.sub.6-C.sub.8 aromatics along
with paraffins and heavier aromatics.
[0006] Aromatics can also be produced by the
dehydrocyclo-oligomerization of C.sub.2-C.sub.5 aliphatic
hydrocarbons. That process typically produces a product comprised
of benzene, toluene, xylenes, C5+ paraffins, C.sub.4- light
paraffins, olefins, and unreacted C.sub.2-C.sub.5 aliphatic
hydrocarbons.
[0007] Another technique for producing aromatics involves the
cracking of hydrocarbons such as by steam cracking or catalytic
cracking. That process typically produces a product comprised of
benzene, toluene, xylenes, C.sub.6+ paraffins, and other
hydrocarbons.
[0008] The aromatics present in the reformate stream from a
reformer or cracker will depend on the composition of the feedstock
to the reformer or cracker, the type of reformer or cracker, and
the operating conditions of the reformer or cracker. Normally, the
aromatics present in the reformate stream will comprise benzene,
toluene, a near equilibrium mixture of xylenes, ethylbenzene, and a
mixture of nominally of C.sub.9-C.sub.10. Products of the reformate
having the most value are benzene and xylenes. Of the xylene
isomers, i.e., ortho-, meta- and para-xylene, the para-xylene is of
particular value as a large volume chemical intermediate in a
number of applications, such as the manufacture of terephthalic
acid, which is an intermediate in the manufacturer of
polyester.
[0009] The reformate is usually sent to an aromatics recovery
complex where it undergoes several processing steps in order to
recover high value products, e.g., xylenes and benzene, and to
convert lower value products, e.g., toluene, into higher value
products. For example, the aromatics present in the reformate are
usually separated into different fractions by carbon number; e.g.
benzene, toluene, xylenes, and ethylbenzene, etc. The C.sub.8
fraction is then subjected to a processing scheme to make more high
value para-xylene. Para-xylene is usually recovered in high purity
from the C.sub.8 fraction by separating the para-xylene from the
ortho-xylene, meta-xylene, and ethylbenzene using selective
adsorption or crystallization. The ortho-xylene and meta-xylene
remaining from the para-xylene separation are isomerized to produce
an equilibrium mixture of xylenes. The ethylbenzene is isomerized
into xylenes or is dealkylated to benzene and ethane. The
para-xylene is then separated from the ortho-xylene and the
meta-xylene using adsorption or crystallization and the
para-xylene-deleted-stream is recycled to extinction to the
isomerization unit and then to the para-xylene recovery unit until
all of the ortho-xylene and meta-xylene are converted to
para-xylene and recovered.
[0010] Toluene is typically recovered as a separate fraction and
then may be converted into higher value products, e.g., benzene
and/or xylenes. One toluene conversion process involves the
disproportionation of toluene to make benzene and xylenes. Another
process involves the hydrodealkylation of toluene to make
benzene.
[0011] Both toluene disproportionation and toluene
hydrodealkylation result in the formation of benzene. With the
current and future anticipated environmental regulations involving
benzene, it is desirable that the toluene conversion not result in
the formation of significant quantities of benzene.
[0012] Xylenes can be produced by the methylation of toluene. Such
a process is disclosed in U.S. Pat. No. 3,965,207. One advantage of
producing xylenes by this process is that the xylenes production
does not result in the formation of benzene by-product.
[0013] In the past when it was desirable to methylate toluene,
toluene present in the reformate has usually been first separated
from the other hydrocarbons present in the reformate, such as by
fractionation and extraction, before entering a methylation
reactor. Such a separation requires substantial capital investment
in equipment, e.g., heat exchangers, high pressure separator,
fractioners, etc. In addition, the reformate leaving the reformer
is at elevated temperature and highly suitable for further
conversion. With the separation of toluene from the reformate, the
recovered toluene must be heated again to conversion
temperatures.
SUMMARY OF THE INVENTION
[0014] In accordance with the present invention, there is provided
a process for producing xylenes from reformate, which process
comprises:
[0015] (a) providing a reformate containing benzene, toluene or
mixtures thereof in methylation reaction zone; and,
[0016] (b) methylating at least a portion of the benzene, toluene,
or mixtures thereof present in said reformate in said methylation
reaction zone with a methylating agent under conditions effective
for the methylation and in the presence of a catalyst effective for
the methylation to produce a resulting product having a higher
xylenes content than said reformate.
[0017] In another embodiment, the present invention provides a
process for producing xylenes from reformate formed in an
aromatization zone, which process comprises:
[0018] (a) forming reformate containing benzene, toluene or
mixtures thereof in an aromatization zone;
[0019] (b) transferring at least a portion of the reformate from
said aromatization zone to a methylation reaction zone; and,
[0020] (c) methylating at least a portion of the benzene, toluene,
or mixtures thereof present in said reformate in said methylation
reaction zone with a methylating agent under conditions effective
for the methylation and in the presence of a catalyst effective for
the methylation to produce a resulting product having a higher
xylenes content than said reformate.
[0021] In a further embodiment, the present invention provides a
multistage integrated process for upgrading a petroleum naphtha
which comprises the steps of:
[0022] (a) introducing the naphtha to an aromatization zone;
[0023] (b) reforming the naphtha under aromatization conditions and
in the presence of a catalyst effective for the aromatization of
the naphtha to produce a reformate containing benzene, toluene or
mixtures thereof;
[0024] (c) transferring at least a portion of said reformate from
said aromatization zone to a methylation reaction zone; and
[0025] (d) methylating in said methylation reaction zone at least a
portion of the benzene, toluene or mixtures thereof present in said
reformate with a methylating agent under conditions effective for
the methylation and in the presence of a catalyst effective for the
methylation to produce a resulting product having a higher xylenes
content than said reformate.
[0026] An important feature of the present invention is that the
aromatization zone and methylation zone can be in series flow
arrangement preferably without intermediate separation of the
reformer effluent so that the two zones are operated under
compatible conditions including hydrogen circulation rate and
pressure.
[0027] The methylation reaction can occur in the liquid phase or
the vapor phase. Usually the reaction will occur in the vapor
phase. The presence of the vapor phase in the reactor zone results
in increased catalytic activity in the reactor zone and increased
diffusion of molecules to the catalytic sites of the catalyst,
e.g., pores of the molecular sieve. The expression "vapor phase",
as used herein, includes the presence of minor amounts of some
liquid phase, e.g., less than 10 percent by volume of liquid, as
well as the substantial absence of liquid phase.
BRIEF DESCRIPTION OF THE DRAWING
[0028] The FIGURE is a simplified process flow diagram,
illustrating a preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The term "aromatization", as used herein, shall mean the
production of aromatics comprising benzene, toluene, or mixtures
thereof by the conversion of non-aromatic hydrocarbons to aromatic
hydrocarbons comprising benzene, toluene, or mixtures thereof. The
term "aromatization", as used herein, shall also include the
production of aromatics comprising benzene, toluene, or mixtures
thereof by the cracking of heavy aromatic hydrocarbons to produce
the aromatic hydrocarbons comprising benzene, toluene, or mixtures.
Examples of aromatization processes include catalytic reforming of
naphtha, dehydrocyclo-oligomerization of C.sub.2-C.sub.5 aliphatic
hydrocarbons, steam cracking of hydrocarbons to produce aromatic
hydrocarbons comprising benzene, toluene, or mixtures thereof, and
the catalytic cracking of hydrocarbons to produce aromatic
hydrocarbons comprising benzene, toluene, or mixtures thereof.
[0030] The term "reformate", as used herein, shall mean the product
produced by "aromatization".
[0031] In a preferred embodiment of the invention as depicted in
the FIGURE, a methylation unit is located inside the reforming loop
with reformate methylation carried out without interstage
separation.
[0032] Referring to the Figure, naphtha is directed via line 1 to
heat exchanger 3 where the temperature of the naphtha is elevated.
The naphtha feed can be either naphtha alone or the naphtha can be
combined with toluene. Next, the heated naphtha is sent via line 5
to reformer heater 7 which elevates the temperature of the feed to
a temperature suitable for reforming. After heating, the naphtha is
withdrawn via line 9 to aromatization reactor zone 11 where the
naphtha is reformed into aromatic products. Although only one
reactor zone is shown, there can be more than one reactor zone. The
reformate is then withdrawn through line 13 to heat exchanger 15
where the temperature of the reformate is adjusted for the
methylation reaction. Next, the reformate is supplied via line 17
to methylation reaction zone 19. If desired, a stream of
hydrocarbons comprised of benzene and/or toluene can be added to
the reformate. The methylation reaction is usually carried out in
the vapor phase. When carried out in the vapor phase, if additional
heat is necessary for the reformate to be in the vapor phase, the
reformate can be heated to the vapor phase either before it enters
the methylation reaction zone or after it has entered the
methylation reaction zone. The methylating agent can be supplied to
methylation reaction zone 19 via line 21. Usually the methylating
agent is supplied to the methylation reaction zone through more
than one feed point. In methylation reaction zone 19, the toluene
present in the reformate is methylated to form xylenes. Also,
benzene present in the reformate can be methylated to form toluene
which, in turn, can be methylated to form xylenes. Depending upon
the composition of the reformate, other reactions may also occur.
For example, ethylbenzene can be methylated to form
para-ethyl-methylbenzene or dealkylated to form benzene, which in
turn, can be methylated to form toluene which can be methylated to
form xylenes. Also, any ethyl-methyl-benzene present in the
reformate can be dealkylated to form toluene, which can be
methylated to form xylenes. The catalyst used in the methylation
reaction can be a catalyst that produces equilibrium amounts of
xylene isomers or can be a catalyst that is selective to produce
greater than equilibrium amounts of a desired xylene isomer, e.g.,
para-xylene. The methylated product is then sent via line 23 to
heat exchanger 3. Heat exchanger 3 cools the methylated product and
uses heat recovered from the methylated product to elevate the
temperature of the naphtha supplied via line 1. Next, the
methylated product is withdrawn through line 25 to heat exchanger
27 to further cool the methylated product for separation of
hydrogen from the product. Next, the cooled methylated product is
sent via line 29 to high pressure separator 31 where hydrogen is
recovered. Hydrogen is removed via line 33 and sent to water
dryer/oxygenate removal unit 35. It is important that the water and
oxygenates not be recycled with the hydrogen into aromatization
reaction zone 11. Hydrogen is removed from unit 35 via line 36 and
either recycled back to the reforming unit or removed from the
system via line 37. Water present in the methylated product can be
removed from high pressure separator 31 via line 39. Next, the
product is sent via line 41 to dryer 43 where remaining water and
oxygenates are removed. The product is then sent via line 45 to
separation block 47 where low pressure hydrogen, C.sub.4- and
C.sub.5 are separated and removed via line 49. The resulting
product, C.sub.6+, is transferred via line 51 to distillation
column 53 where C.sub.6/C.sub.7, including benzene and toluene, are
removed overhead via line 55 for further processing. The C.sub.8+
fraction is removed from the bottom of distillation column 53 via
line 57 and further separated and converted in xylene loop 59 to
the desired molecules, e.g., para-xylene and other by-products.
Practicing of the invention according to this embodiment allows
sharing of the heat exchangers, furnace, compressor, phase
separator, distillation, and the extraction hardware.
[0033] Aromatization
[0034] Aromatization will usually be carried out by catalytic
reforming of naphtha or the dehydrocyclo-oligomerization of
C.sub.2-C.sub.5 aliphatics.
[0035] Dehydrocyclo-oligomerization involves converting
C.sub.2-C.sub.5 aliphatic hydrocarbons to aromatic hydrocarbons.
The process is carried out by contacting C.sub.2-C.sub.5 aliphatic
hydrocarbons in an aromatization zone and in the presence of a
catalyst suitable for dehydrocyclodimerization and under conditions
effective to produce a aromatics product comprising benzene and/or
toluene. The dehydrocyclodimerization process increases carbon
chain length by oligomerization, promotes cyclization, and
dehydrogenates cyclics to their respective aromatics.
[0036] The feedstream used in the dehydrocyclo-oligomerization
process will contain at least one aliphatic hydrocarbon containing
2 to about 5 carbon atoms. The aliphatic hydrocarbons may be open
chain, straight chain, or cyclic. Examples such as hydrocarbons
include ethane, ethylene, propane, propylene, n-butane, n-butenes,
isobutane, isobutene, butadiene, straight and branch pentane,
pentene, and pentyldiene. Dehydrocyclo-oligomerization conditions
will vary depending on such factors as feedstock composition and
desired conversion. A desired range of conditions for the
dehydro-cyclodimerization of the aliphatic hydrocarbons to
aromatics include a temperature from about 350.degree. to about
650.degree. C., a pressure from about 1 to about 100 atmospheres,
and weight hour space velocity from about 0.2 to about 8. It is
understood that, as the average carbon number of the feed
increases, a temperature in the lower end of temperature range is
required for optimum performance and conversely, as the average
carbon number of the feed decreases, the higher the required
reaction temperature.
[0037] The catalyst used in the dehydrocyclo-oligomerization
reaction will preferably comprise an intermediate pore size
molecular sieve. Intermediate pore size molecular sieves have a
pore size from about 5 to about 7 .ANG. and include, for example,
AEL, AFI, MWW, MFI, MEL, MFS, MEI, MTW, EUO, MTT, HEU, FER, and TON
structure type molecular sieves. These materials are described in
"Atlas of Zeolite Structure Types", eds. W. H. Meier, D. H. Olson,
and Ch. Baerlocher, Elsevier, Fourth Edition, 1996, which is hereby
incorporated by reference. Examples of suitable intermediate pore
size molecular sieves include ZSM-5, ZSM-11, ZSM-12, ZSM-22,
ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM-50, ZSM-57, MCM-22,
MCM-49, MCM-56, and SAPO-5. Preferred molecular sieves are SAPO-11,
as well as titanosilicate, gallosilicate, aluminosilicate, and
gallium-containing aluminosilicate molecular sieves having a MFI
structure.
[0038] Usually the molecular sieve will be combined with binder
material resistant to the temperature and other conditions employed
in the process. Examples of suitable binder material include clays,
alumina, silica, silica-alumina, silica-magnesia, silica-zirconia,
silica-thoria, silica-beryllia, and silica-titania, as well as
ternary compositions, such as silica-alumina-thoria,
silica-alumina-zirconia, silica-alumina-magnesia and
silica-magnesia-zirconia. The molecular sieve may also be
composited with zeolitic material such as the zeolitic materials
which are disclosed in U.S. Pat. No. 5,993,642, which is hereby
incorporated by reference.
[0039] The relative proportions of molecular sieve and binder
material will vary widely with the molecular sieve content ranging
from between about 1 to about 99 percent by weight, more preferably
in the range of about 10 to about 70 percent by weight of molecular
sieve, and still more preferably from about 20 to about 50
percent.
[0040] To make enhanced amounts (greater than equilibrium amounts)
of para-xylene (versus the other xylene isomers produced by the
dehydrocyclo-oligomerization reaction), a molecular sieve catalyst,
e.g., ZSM-5 catalyst, can be selectivated by the use of a
selectivating agent.
[0041] Examples of compounds for selectivating the catalysts
include treating the surface of the catalyst with compounds of
phosphorus and/or various metal oxides such as alkaline earth metal
oxides, e.g., calcium oxide, magnesium oxide, etc. rare earth metal
oxides, lanthanum oxide, and other metal oxides such as boron
oxide, titania, antimony oxide, and manganese oxide.
[0042] Selectivation may also be accomplished by depositing coke on
the catalyst. The coke selectivation can be carried Qut during the
methylation reaction such as by running the methylation reaction at
conditions which allow the deposition of coke on the catalyst.
Also, the catalyst can be preselectivated with coke such as by
exposing the catalyst in the reactor to a thermally decomposable
organic compound, e.g., benzene, toluene, etc. at a temperature in
excess of the decomposition temperature of said compound, e.g.,
from about 400.degree. C. to about 650.degree. C., more preferably
425.degree. C. to about 550.degree. C., at a WHSV in the range of
from about 0.1 to about 20 lbs. of feed per pound of catalyst per
hour, at a pressure in the range of from about 1 to about 100
atmospheres, and in the presence of 0 to about 2 moles of hydrogen,
more preferably from about 0.1 to about 1 moles of hydrogen per
mole of organic compound, and optionally in the presence of 0 to
about 10 moles of nitrogen or another inert gas per mole of organic
compound. This process is conducted for a period of time until a
sufficient quantity of coke has deposited on the catalyst surface,
generally at least about 2% by weight and more preferably from
about 8 to about 40% by weight of coke.
[0043] Selectivation of the catalyst may also be accomplished using
organosilicon compounds. The silicon compounds may comprise a
polysiloxane include silicones, a siloxane, and a silane including
disilanes and alkoxysilanes.
[0044] Silicone compounds that can be used in the present invention
include the following: 1
[0045] wherein R.sub.1 is hydrogen, fluoride, hydroxy, alkyl,
aralkyl, alkaryl or fluoro-alkyl. The hydrocarbon substituents
generally contain from 1 to about 10 carbon atoms and preferably
are methyl or ethyl groups. R.sub.2 is selected from the same group
as R.sub.1, and n is an integer of at least 2 and generally in the
range of 2 to about 1000. The molecular weight of the silicone
compound employed is generally between about 80 to about 20,000 and
preferably about 150 to about 10,000. Representative silicone
compounds include dimethylsilicone, diethylsilicone,
phenylmethylsilicone, methyl hydrogensilicone,
ethylhydrogensilicone, phenylhydrogensilicone,
fluoropropylsilicone, ethyltrifluoroprophysilicone,
tetrachlorophenyl methyl methylethylsilicone, phenylethylsilicone,
diphenylsilicone, methyltrisilicone, tetrachlorophenylethyl
silicone, methylvinylsilicone and ethylvinylsilicone. The silicone
compound need not be linear but may be cyclic as for example
hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane,
hexaphenyl cyclotrisiloxane and octaphenylcyclotetrasiloxane.
Mixtures of these compounds may also be used as well as silicones
with other functional groups.
[0046] Useful siloxanes and polysiloxanes include as non-limiting
example hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane,
decamethyl cyclopentasiloxane, hexamethyldisiloxane,
octamethytrisiloxane, decamethyltetrasiloxane,
hexaethylcyclotrisiloxane, octaethylcyclo tetrasiloxane,
hexaphenylcyclotrisiloxane and octaphenylcyclo-tetrasiloxa- ne.
[0047] Useful silanes, disilanes, or alkoxysilanes include organic
substituted silanes having the general formula: 2
[0048] wherein R is a reactive group such as hydrogen, alkoxy,
halogen, carboxy, amino, acetamide, trialkylsilyoxy, R.sub.1,
R.sub.2 and R.sub.3 can be the same as R or can be an organic
radical which may include alkyl of from 1 to about 40 carbon atoms,
alkyl or aryl carboxylic acid wherein the organic portion of alkyl
contains 1 to about 30 carbon atoms and the aryl group contains
about 6 to about 24 carbons which may be further substituted,
alkylaryl and arylalkyl groups containing about 7 to about 30
carbon atoms. Preferably, the alkyl group for an alkyl silane is
between about 1 and about 4 carbon atoms in chain length. Mixtures
may also be used.
[0049] The silanes or disilanes include, as non-limiting examples,
dimethylphenylsilane, phenytrimethylsilane, triethylsilane and
hexamethyldislane. Useful alkoxysilanes are those with at least one
silicon-hydrogen bond.
[0050] Selectivation of the catalyst can also be accomplished using
a combination of coke and silicon applied by the procedures
described above.
[0051] Catalytic reforming involves the production of aromatics
from a C.sub.6+ paraffinic feed, e.g., naphtha, by contacting the
feed with a reforming catalyst under reforming conditions to
produce a reaction product comprising aromatics and paraffins. The
reformate is formed under typical reforming conditions designed to
promote dehydrogenation of naphthenes, isomerization of paraffinic
hydrocarbons and dehydrocyclization of non-aromatic
hydrocarbons.
[0052] Catalysts suitable for use in catalytic reforming include
acidic reforming catalysts (bifunctional catalysts) and non-acidic
reforming catalysts (monofunctional catalysts).
[0053] Acidic reforming catalysts usually comprise a metallic oxide
support having disposed therein a Group VIII metal. Suitable
metallic oxide supports include alumina and silica. Preferably, the
acidic reforming catalyst comprises a metallic oxide support having
disposed therein in intimate admixture a Group VIII metal
(preferably platinum) and a metal promoter, such as rhenium, tin,
germanium, cobalt, nickel, iridium, rhodium, ruthenium and
combinations thereof. More preferably, the acidic reforming
catalyst comprises an alumina support, platinum, and rhenium or
platinum and tin on an alumina support.
[0054] Non-acidic or monofunctional reforming catalysts will
comprise a non-acidic molecular sieve, e.g., zeolite, and one or
more hydrogenation/dehydrogenation components. Examples of suitable
molecular sieves include MFI structure type, e.g., silicalite, and
molecular sieves having a large pore size, e.g., pore size from
about 7 to 9 Angstroms. Examples of large pore molecular sieves
include LTL, FAU, and *BEA structure types. Examples of specific
molecular sieves include zeolite L, zeolite X, zeolite Beta,
zeolite Y, and ETS-10.
[0055] The non-acidic catalysts will contain one or more
hydrogenation/dehydrogenation metals, e.g., Group VII B metals,
such as rhenium, and Group VIII metals, such as nickel, ruthenium,
rhodium, palladium, iridium or platinum. The preferred Group VIII
metal is platinum. Also, the nonacidic catalyst can contain a metal
promoter such as tin.
[0056] The amount of hydrogenation/dehydrogenation metal present on
the non-acidic catalyst will usually be from about 0.1% to about 5%
of hydrogenation/dehydrogenation metal based on the weight of the
catalyst. The metal can incorporated into the zeolite during
synthesis of the zeolite, by impregnation, or by ion exchange of an
aqueous solution containing the appropriate salt. By way of
example, in an ion exchange process, platinum can be introduced by
using cationic platinum complexes such as tetraammine-platinum (II)
nitrate.
[0057] The non-acidic catalyst will usually include a binder. The
binder can be a natural or a synthetically produced inorganic oxide
or combination of inorganic oxides. Typical inorganic oxide
supports which can be used include clays, alumina, and silica, in
which acidic sites are preferably exchanged by cations that do not
impart strong acidity.
[0058] The reforming process can be continuous, cyclic or
semi-regenerative. The process can be in a fixed bed, moving bed,
tubular, radial flow or fluid bed.
[0059] Conditions for reforming conditions include temperatures of
at least about 400.degree. C. to about 600.degree. C. and pressures
from about 50 psig (446 kPa) to about 500 psig (3,549 kPa), a mole
ratio of hydrogen to hydrocarbons from 1:1 to 10:1 and a liquid
hour space velocity of between 0.3 and 10.
[0060] Substantially any hydrocarbon feed containing C.sub.6+ e.g.,
naphtha can be utilized. The naphtha will generally comprise
C.sub.6-C.sub.9 aliphatic hydrocarbons. The aliphatic hydrocarbons
may be straight or branched chain acyclic hydrocarbons, and
particulary paraffins such as heptane.
[0061] Toluene/Benzene Methylation
[0062] The methylation reaction will usually occur in vapor phase.
Reaction conditions for use in the present invention include
temperatures from about 300.degree. C. to about 700.degree. C. and
preferably about 400.degree. C. to about 700.degree. C. The
reaction is preferably carried out at a pressure from about 1 to
1000 psig, and a weight hourly space velocity of between about 0.1
and about 200 and preferably between about 1 and about 100 weight
of charge per weight of catalyst per hour. The molar ratio of
toluene and benzene to methylating agent can vary and will usually
be from about 0.1:1 to about 20:1. Preferred ratios for operation
are in the range of 2:1 to about 4:1. Hydrogen gas can be supplied
to the reaction as an anticoking agent and diluent. The methylating
agent is usually supplied to the methylation reaction zone through
multiple feed points, e.g., 3-6 feed points.
[0063] Typical methylating agents include methanol, dimethylether,
methylchloride, methylbromide, methylcarbonate, acetaldehyde,
dimethoxyethane, acetone, and dimethylsulfide. The methylating
agent can also be formed from synthesis gas, e.g., the agent can be
formed from the H.sub.2, CO, and/or CO.sub.2 of synthesis gas. The
methylating agent can be formed from the synthesis gas within the
methylation reaction zone. One skilled in the art will know that
other methylating agents may be employed to methylate the benzene
and/or toluene based on the description provided therein. Preferred
methylating agents are methanol and dimethylether. Methanol is most
preferred.
[0064] Catalysts suitable for use in the present invention include
any catalyst that is effective for toluene or benzene methylation.
The catalyst used in the process will usually comprise a
crystalline molecular sieve.
[0065] The catalyst used in the methylation reaction will
preferably comprise an intermediate pore size molecular sieve.
Intermediate pore size molecular sieves have a pore size from about
5 to about 7 .ANG. and include, for example, AEL, AFI, MWW, MFI,
MEL, MFS, MEI, MTW, EUO, MTT, HEU, FER, and TON structure type
zeolites. These materials are described in "Atlas of Zeolite
Structure Types", eds. W. H. Meier, D. H. Olson, and Ch.
Baerlocher, Elsevier, Fourth Edition, 1996, which is hereby
incorporated by reference. Examples of suitable intermediate pore
size molecular sieves include ZSM-5, ZSM-11, ZSM-12, ZSM-22,
ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM-50, ZSM-57, MCM-22,
MCM-49, MCM-56, and SAPO-5. Preferred molecular sieves are SAPO-11,
as well as titanosilicate, gallosilicate, aluminosilicate, and
gallium-containing aluminosilicate molecular sieves having a MFI
structure.
[0066] The intermediate pore size molecular sieve will generally be
a composition having the following molar relationship:
X.sub.2O.sub.3:(n)YO.sub.2
[0067] wherein X is a trivalent element such as titanium, aluminum,
iron, boron, and/or gallium and Y is a tetravalent element such as
silicon, tin, and/or germanium; and n has a value greater than 12,
said value being dependent upon the particular type of molecular
sieve. When the intermediate pore size molecular sieve is a MFI
structure type molecular sieve, n is preferably greater than 10 and
preferably, from 20:1 to 200:1.
[0068] When the molecular sieve has a gallium silicate composition,
the molecular sieve usually will be a composition having the
following molar relationship:
Ga.sub.2O.sub.3:ySiO.sub.2
[0069] wherein y is between about 20 and about 500. The molecular
sieve framework may contain only gallium and silicon atoms or may
also contain a combination of gallium, aluminum, and silicon.
[0070] Usually the molecular sieve will be incorporated with binder
material resistant to the temperature and other conditions employed
in the process. Examples of suitable binder material include clays,
alumina, silica, silica-alumina, silica-magnesia, silica-zirconia,
silica-thoria, silica-beryllia, and silica-titania, as well as
ternary compositions, such as silica-alumina-thoria,
silica-alumina-zirconia, silica-alumina-magnesia and
silica-magnesia-zirconia. The molecular sieve may also be
composited with zeolitic material such as the zeolitic materials
which are disclosed in U.S. Pat. No. 5,993,642.
[0071] The relative proportions of molecular sieve and binder
material will vary widely with the molecular sieve content ranging
from between about 1 to about 99 percent by weight, more preferably
in the range of about 10 to about 70 percent by weight of molecular
sieve, and still more preferably from about 20 to about 50
percent.
[0072] The catalyst may also include at least one
hydrogenation/dehydrogen- ation metal. Such metals can reduce the
rate of deactivation of the catalyst. Reference to
hydrogenation/dehydrogenation metal or metals is intended to
encompass such metal or metals in the elemental state (i.e. zero
valent) or in some other catalytically active form such as an
oxide, sulfide, halide, carboxylate and the like. Such metals are
known to persons skilled in the art and include, for example, one
or more metals, and metals of Groups IIIA, IVA, VA, VIA, VIIA,
VIII, IB, IIB, IIIB, IVB, VB, VIB, and VIIB of the Periodic Table
of the Elements. Examples of suitable metals include Group VIII
metals (i.e., Pt. Pd, Ir, Rh, Os, Ru, Ni, Co and Fe), Group IVA
metals (i.e., Sn and Pb), Group VA metals (i.e., Sb and Bi), and
Group VIIB metals (i.e., Mn, Tc and Re). Noble metals (i.e., Pt,
Pd, Ir, Rh, Os and Ru) are sometimes preferred.
[0073] When the catalyst used for the methylation reaction is a
molecular sieve, the catalyst can be selectivated to enhance the
amount of para-xylene produced by the methylation reaction by the
use of a selectivating agent. Suitable selectivating agents include
the selectivating agents disclosed earlier in this application for
selectivating dehydrocyclo-oligomerization molecular sieve
catalysts.
[0074] Catalysts particularly suited for the methylation reaction
are zeolite bound zeolite catalysts. These catalysts, as well as
their method of preparation, are described in U.S. Pat. No.
5,994,603, which is hereby incorporated by reference. The zeolite
bound zeolite catalysts will comprise first crystals of an acidic
intermediate pore size first molecular sieve and a binder
comprising second crystals of a second molecular sieve. Preferably,
the zeolite bound zeolite catalyst contains less than 10 percent by
weight based on the total weight of the first and second zeolite of
non-zeolitic binder, e.g., amorphous binder. An example of such a
catalyst comprises first crystals of a MFI or MEL structure type,
e.g., ZSM-5 or ZSM-11, and a binder comprising second crystals of
MFI or MEL structure type, e.g., Silicalite 1 or Silicalite 2.
[0075] The amount of benzene/toluene converted to xylenes will
depend on a number of factors including the make up of the
reformate to be methylated, the methylation conditions, and the
catalyst used. Usually, at least 5 weight percent of the
benzene/toluene will be converted to xylenes. Preferably, at least
7 weight percent of the benzene/toluene will be converted to
xylenes, and, more preferably, at least 30 weight percent of the
benzene/toluene will be converted to xylenes.
[0076] The process of methylation of the benzene, toluene, or
mixtures thereof present in the reformate can produce greater than
equilibrium amounts of para-xylene. Preferably, the process will
produce a xylene product containing greater than 30 weight percent
para-xylene based on the total weight of xylenes produced by the
process. More preferably, the process produces a xylene product
containing greater than 60 weight percent para-xylene based on the
total weight of the xylenes produced by the process. Most
preferably, the process produces a xylene product containing
greater than 80 weight percent para-xylene based on the total
weight of the xylenes produced by the process.
[0077] The invention is further exemplified by the examples below,
which are present to illustrate certain specific embodiments of the
invention, but are not intended to be construed as to be
restrictive of the spirit and scope thereof
EXAMPLE 1
[0078] A simulated light naphtha reformate feed was subjected to
toluene methylation. The catalyst used in the test comprised 1/16
inch extrudates which contained 65 weight percent H-ZSM-5 and 35
weight percent silica binder. The catalyst had an alpha value of
330. The "alpha value" of a catalyst is an approximate indication
of its catalytic cracking activity. The alpha test is described in
U.S. Pat. No. 3,354,078 and in the Journal of Catalysis, Vol. 4,
522-529 (1965); Vol. 6, 278 (1966); and Vol. 61, 395 (1980), each
incorporated herein by reference to that description.
[0079] The reformate feed used in the test had the composition
given below:
1 TABLE 1 Component Wt. % C.sub.5- 0.00 n-C.sub.6 18.58 i-C.sub.6
15.04 n-C.sub.7 4.30 i-C.sub.7 5.37 Benzene 15.32 Toluene 41.38 PX
0.00 MX 0.00 OX 0.00 EB 0.00 C.sub.9+ 0.00 Total 100
[0080] The test was carried out under the following conditions:
2 TABLE 2 Component WHSV ((h.sup.-1) 1 MeOH/:Toluene [molar] 1
H2:(MeOH + HCs) [molar] 1 Pressure (psig) 64 Temperature (.degree.
F.) 700
[0081] The test was carried out by loading the catalyst into a
fixed bed reactor and heating the catalyst in flowing hydrogen at
reactor temperature range from room temperature to 950.degree. F.
for two hours. Next, the reformate was introduced into the reactor
and the test was carried out under the conditions shown in Table 2.
The results of the test are set forth below in Table 3.
3 TABLE 3 Component Wt. % C.sub.5- 1.13 n-C.sub.6 16.58 i-C.sub.6
13.43 n-C.sub.7 3.87 i-C.sub.7 4.33 Benzene 11.06 Toluene 35.82 PX
2.59 MX 3.20 OX 3.76 EB 0.00 C.sub.9+ 4.23 Total 100
[0082] The results report in Table 3 shows that after toluene
methylation, the content of the reformate increased from no xylenes
being present to 9.49% xylenes. Also, the amount of para-xylene
produced (27% para-xylene) was greater than an equilibrium amount
(24% para-xylene).
EXAMPLE 2
[0083] A simulated light naphtha reformate feed was subjected to
toluene methylation using a silicon-selectivated H-ZSM-5/silica
bound catalyst.
[0084] The catalyst was selectivated by contacting H-ZSM-5/silica
bound (65 weight % H-ZSM-5 35 weight % silica) with
dimethylphenylmethyl polysiloxane dissolved in decane and
subsequently calcining the selectivated catalyst. The catalyst was
treated with 3 additional silicon selectivation treatments using
substantially the same procedure. The catalyst had an alpha value
of approximately 300.
[0085] The reformate feed used in the test had the composition
given below:
4 TABLE 4 Component Wt. % C.sub.5- 0.00 n-C.sub.6 27.85 i-C.sub.6
3.64 n-C.sub.7 8.77 i-C.sub.7 0.05 Benzene 15.76 Toluene 43.93 PX
0.00 MX 0.00 OX 0.00 EB 0.00 C.sub.9+ 0.00 Total 100
[0086] The test was carried out under the following conditions:
5 TABLE 5 Component WHSV (h.sup.-1) 1 MeOH/:Toluene [molar] 1
H2:(MeOH + HCs) [molar] 1 Pressure (psig) 200 Temperature (.degree.
F.) 700
[0087] The test was carried out by loading the catalyst into a
fixed bed reactor and heating the catalyst in flowing hydrogen at a
reactor temperature range from room temperature to 950.degree. F.
for two hours. Next, the reformate was introduced into the reactor
and the test was run at the conditions shown in Table 5. The
results of the test are set forth below in Table 6.
6 TABLE 6 Component Wt. % C.sub.5- 5.61 n-C.sub.6 21.32 i-C.sub.6
3.85 n-C.sub.7 5.44 i-C.sub.7 0.22 Benzene 11.39 Toluene 33.12 PX
2.66 MX 3.67 OX 2.36 EB 1.31 C.sub.9+ 9.05 Total 100
[0088] The results in Table 6 shows that after toluene methylation,
the content of the reformate increased from no xylenes being
present to 8.69% xylenes. Also, the amount of para-xylene produced
(31% para-xylene) was greater than an equilibrium amount (24%
para-xylene).
EXAMPLE 3
[0089] A simulated light naphtha reformate feed was subjected to
toluene methylation using a zeolite bound zeolite catalyst.
[0090] The catalyst comprised 70 wt. % H-ZSM-5 core crystals
(average particle size of 3.5 microns) having a silica to alumina
mole ratio of 75:1 and 30 wt. % ZSM-5 binder crystals having a
silica to mole ratio of approximately 900:1. The catalyst was
prepared by first mixing the ZSM-5 core crystals with amorphous
silica containing a trace amount of alumina and then extruding the
mixture into a silica bound extrudate. Next, the silica binder of
the extrudate was converted to the second zeolite by aging the
aggregate at elevated temperatures in an aqueous solution
containing a template and hydroxy ions sufficient to covert the
silica to the binder crystals. The resulting zeolite bound zeolite
was then washed, dried, calcined, and ion exchanged into the
hydrogen form.
[0091] The reformate feed used in the test had the composition
given below:
7 TABLE 7 Component Wt. % C.sub.5- 0.00 n-C.sub.6 33.45 i-C.sub.6
3.88 n-C.sub.7 0.00 i-C.sub.7 0.00 Benzene 16.01 Toluene 46.66 PX
0.00 MX 0.00 OX 0.00 EB 0.00 C.sub.9+ 0.00 Total 100
[0092] The test was carried out under the following conditions:
8 TABLE 8 Component WHSV (h.sup.-1) 4 MeOH/:Toluene [molar] 1
H2:(MeOH + HCs) [molar] 1 Pressure (psig) 200 Temperature (.degree.
F.) 700
[0093] The test was carried out by loading the catalyst into a
fixed bed reactor and heating the catalyst in flowing hydrogen at
reactor temperature range from room temperature to 950.degree. F.
for two hours. Next, the reformate was introduced into the reactor
and the test was carried out at the conditions shown in Table 8.
The results of the test are set forth below in Table 9.
9 TABLE 9 Component Wt. % C.sub.5- 4.42 n-C.sub.6 26.69 i-C.sub.6
3.77 n-C.sub.7 0.00 i-C.sub.7 0.00 Benzene 13.21 Toluene 39.40 PX
2.18 MX 2.41 OX 1.79 EB 0.90 C.sub.9+ 5.24 Total 100
[0094] The results in Table 6 shows that after toluene methylation,
the content of the reformate increased from no xylenes being
present to 6.38% xylenes. Also, the amount of para-xylene produced
(34% para-xylene) was greater than an equilibrium amount (24%
para-xylene).
EXAMPLE 4
[0095] A simulated light reformate, which would be formed by the
dehydrocyclo-oligomerization of C.sub.2-C.sub.5 aliphatic
hydrocarbons, was subjected to toluene methylation. The catalyst
used in the test had an alpha value of approximately 22 and
comprised 1/16 inch extrudates which contained 65 wt. % H-ZSM-23
having a silica to alumina mole ratio of 110:1 and 35 wt. % of
alumina binder. The ZSM-23 was prepared according to U.S. Pat. No.
4,076,842.
[0096] The reformate feed used in the test had the composition
given below:
10 TABLE 10 Component Wt. % C.sub.5- 0.00 n-C.sub.6 0.00 i-C.sub.6
0.00 n-C.sub.7 35.00 i-C.sub.7 5.00 Benzene 15.00 Toluene 45.00 PX
0.00 MX 0.00 OX 0.00 EB 0.00 C.sub.9+ 0.00 Total 100
[0097] The test was carried out under the following conditions:
11 TABLE 11 Component WHSV (h.sup.-1) 8 MeOH/:Toluene [molar] 1/3
H2:(MeOH + HCs) [molar] 2 Pressure (psig) 150 Temperature (.degree.
F.) 932
[0098] The test was carried out by loading the catalyst into a
fixed bed reactor and heating the catalyst in flowing hydrogen to
the reaction temperature. Next, the reformate was introduced into
the reactor and the test was run at the conditions shown in Table
11. The results of the test are set forth below in Table 12.
12 TABLE 12 Component Wt. % C.sub.5- 19.25 n-C.sub.6 0.00 i-C.sub.6
0.00 n-C.sub.7 16.10 i-C.sub.7 4.65 Benzene 13.07 Toluene 41.45 PX
2.74 MX 1.83 OX 0.91 EB 0.00 C.sub.9+ 0.00 Total 100
[0099] The results in Table 12 show that after toluene methylation,
the content of the reformate increased from no xylenes being
present to 5.48% xylenes. Also, the amount of para-xylene produced
(50% para-xylene) was greater than an equilibrium amount (24%
para-xylene).
EXAMPLE 5
[0100] A simulated full range naphtha reformate (without
C.sub.1-C.sub.5 hydrocarbons) was subjected to toluene methylation
using a silica selectivated ZSM-5 catalyst.
[0101] The ZSM-5 catalyst was selectivated using the procedure
described above in Example 2. The catalyst had an alpha value of
approximately 300.
[0102] The reformate feed used in the test had the composition
given below:
13 TABLE 13 Component Wt. % C.sub.5- 0.00 n-C.sub.6 33.12 i-C.sub.6
3.69 n-C.sub.7 0.00 i-C.sub.7 0.00 Benzene 15.85 Toluene 47.35 PX
0.00 MX 0.00 OX 0.00 EB 0.00 C.sub.9+ 0.00 Total 100
[0103] The test was carried out under the following conditions:
14 TABLE 14 Component WHSV (h.sup.-1) 9.2 MeOH/:Toluene [molar]
0.37 H2:(MeOH + HCs) [molar] 2 Pressure (psig) 200 Temperature
(.degree. F.) 700
[0104] The test was carried out by loading the catalyst into a
fixed bed reactor and heating the catalyst in flowing hydrogen at a
reactor temperature range from room temperature to 950.degree. F.
for two hours. Next, the reformate was introduced into the reactor
and the test was run at the conditions shown in Table 14. The
product contained greater than 90% para-xylene based on the total
amount of xylenes in the product.
EXAMPLE 6
[0105] A simulated light reformate, which would be formed by the
dehydrocyclo-oligomerization of C.sub.2-C.sub.5 aliphatic
hydrocarbons, was subjected to toluene methylation using a SAPO-11
catalyst. The catalyst had an alpha value of approximately 52 and
its chemical analysis was Si.sub.0.1Al..sub.0.46P.sub.0.44. The
SAPO-11 was prepared according to U.S. Pat. No. 6,294,493
[0106] The reformate feed used in the test had the composition
given below:
15 TABLE 15 Component Wt. % C.sub.5- 0.00 n-C.sub.6 0.00 i-C.sub.6
0.00 n-C.sub.7 35.00 i-C.sub.7 5.00 Benzene 15.00 Toluene 45.00 PX
0.00 MX 0.00 OX 0.00 EB 0.00 C.sub.9+ 0.00 Total 100
[0107] The test was carried out under the following conditions:
16 TABLE 16 Component WHSV (h.sup.-1) 8 MeOH/:Toluene [molar] 1/3
H2:(MeOH + HCs) [molar] 2 Pressure (psig) 150 Temperature (.degree.
F.) 932
[0108] The test was carried out by loading the catalyst into a
fixed bed reactor and heating the catalyst in flowing hydrogen to
the reaction temperature. Next, the reformate was introduced into
the reactor and the test was run at the conditions shown in Table
16. The results of the test are set forth below in Table 17.
17 TABLE 17 Component Wt. % C.sub.5- 19.25 n-C.sub.6 0.00 i-C.sub.6
0.00 n-C.sub.7 16.10 i-C.sub.7 4.65 Benzene 13.07 Toluene 41.45 PX
2.74 MX 1.83 OX 0.91 EB 0.00 C.sub.9+ 0.00 Total 100
[0109] The results in Table 17 shows that after toluene
methylation, the content of the reformate increased from no xylenes
being present to 5.8% xylenes. Also, the amount of para-xylene
produced was greater than 40% para-xylene.
* * * * *