Molecular sieve abstract
The present invention relates to new crystalline, molecular sieve
CIT-6 that has the topology of zeolite beta. CIT-6 can be in an
all-silica form, in a form wherein zinc is in the crystal framework,
or a form containing silicon oxide and non-silicon oxides. In a
preferred embodiment, CIT-6 has a crystal size of less than one
micron and a water adsorption capacity of less than 0.05 g/g.
Molecular sieve claims
What is claimed is:
1. A molecular sieve comprising an oxide of silicon and an oxide
of zinc and having the framework topology of zeolite beta, wherein
the molecular sieve contains zinc in its crystal framework.
2. The molecular sieve of claim 1 wherein the oxides of silicon
and zinc are the only oxides in the framework of the molecular sieve.
3. A molecular sieve having the topology of zeolite beta, and having
a composition, as synthesized and in the anhydrous state, in terms
of mole ratios as follows:
8 SiO.sub.2/ZnO 10-100 M/SiO.sub.2 0.01-0.1 Q/SiO.sub.2 0.07-0.14
wherein M is lithium or a mixture of lithium and another alkali
metal; and Q comprises a tetraethylammonium cation, wherein the
molecular sieve contains zinc in its crystal framework.
4. A molecular sieve comprising silicon oxide, zinc oxide, and
an oxide selected from aluminum oxide, boron oxide, gallium oxide,
iron oxide, titanium oxide, vanadium oxide, zirconium oxide, tin
oxide or mixtures thereof and having the framework topology of zeolite
beta, wherein the molecular sieve contains zinc in its crystal framework.
5. The molecular sieve of claim 4 comprising silicon oxide, zinc
oxide and aluminum oxide.
6. The molecular sieve of claim 4 comprising silicon oxide, zinc
oxide and boron oxide.
7. The molecular sieve of claim 4 comprising silicon oxide, zinc
oxide and gallium oxide.
8. The molecular sieve of claim 4 comprising silicon oxide, zinc
oxide and titanium oxide.
9. A molecular sieve having the topology of zeolite beta, and having
a composition, as synthesized and in the anhydrous state, in terms
of mole ratios as follows:
9 SiO.sub.2/ZnO 10-100 SiO.sub.2/ W 30-250 M/SiO.sub.2 0.01-0.1
Q/SiO.sub.2 0.07-0.14
wherein W is an oxide of aluminum, boron, gallium, vanadium, iron,
titanium or mixtures thereof M is lithium or a mixture of lithium
and another alkali metal; and Q comprises a tetraethylammonium cation,
wherein the molecular sieve contains zinc in its crystal framework.
10. A method of preparing a crystalline material comprising an
oxide of silicon and an oxide of zinc and having the framework topology
of zeolite beta, wherein the molecular sieve contains zinc in its
crystal framework, said method comprising contacting in admixture
under crystallization conditions sources of said oxides, a source
of lithium or a mixture of lithium and another alkali metal and
a templating agent comprising a tetraethylammonium cation.
11. The method of claim 10 wherein the source of the alkali metal
contains no alkali metal other than lithium.
12. The method of claim 10 wherein the source of alkali metal contains
lithium and another alkali metal.
13. A method of preparing a crystalline material comprising an
oxide of silicon, an oxide of zinc and an oxide selected from aluminum
oxide, boron oxide, gallium oxide, vanadium oxide, iron oxide, titanium
oxide or mixtures thereof and having the framework topology of zeolite
beta, wherein the molecular sieve contains zinc in its crystal framework,
said method comprising contacting in admixture under crystallization
conditions sources of said oxides, a source of lithium or a mixture
of lithium and another alkali metal and a templating agent comprising
a tetraethylammonium cation.
14. A method of removing a tetraethylammonium organic template
from the pores of a molecular sieve, said method comprising contacting
the molecular sieve with acetic acid or a mixture of acetic acid
and pyridine at elevated temperature for a time sufficient to remove
essentially all of the tetraethylammonium organic template from
the molecular sieve.
15. The method of claim 14 wherein the molecular sieve has the
topology of zeolite beta.
16. The method of claim 14 wherein the elevated temperature is
60.degree. C. or less.
17. The method of claim 14 wherein the elevated temperature is
from about 80.degree. C. to about 135.degree. C.
18. A method of removing an organic template from the pores of
a molecular sieve and at the same time removing zinc atoms from
the framework of the molecular sieve, wherein the molecular sieve
comprises-an oxide of-silicon, an oxide of zinc and, optionally,
an oxide selected from aluminum oxide, boron oxide, gallium oxide,
vanadium oxide, iron oxide, titanium oxide and mixtures thereof
and having the framework topology of zeolite beta, said method comprising
contacting the molecular sieve with acetic acid or a mixture of
acetic acid and pyridine at elevated temperature for a time sufficient
to remove essentially all of the organic template and zinc from
the molecular sieve.
19. The method of claim 18 wherein the elevated temperature is
about 60.degree. C. or less.
20. The method of claim 18 wherein the elevated temperature is
from about 80.degree. C. to about 135.degree. C.
21. A method of making a crystalline material comprising (1) contacting
in admixture under crystallization conditions a source of silicon
oxide, a source of zinc oxide, a source of lithium or a mixture
of lithium and another alkali metal and a templating agent comprising
a tetraethylammonium cation until a crystalline material comprised
of oxides of silicon and zinc and having the topology of zeolite
beta are formed, (2) contacting the crystals with acetic acid or
a mixture of acetic acid and pyridine at an elevated temperature
of about 60.degree. C. or less for a time sufficient to-remove essentially
all of the organic template and zinc from the crystals, and (3)
contacting the crystals with a solution containing a source of aluminum,
boron, gallium, iron, titanium, vanadium, zirconium, tin or mixtures
thereof.
22. The product produced by the method of claim 18.
23. The product produced by the method of claim 21.
24. A crystalline molecular sieve having the topology of zeolite
beta, a crystal size of less than one micron and a water adsorption
capacity of less than 0.05 g/g of molecular sieve.
25. A crystalline silicate molecular sieve having the topology
of zeolite beta, a crystal size of less than one micron and a water
adsorption capacity of less than 0.05 g/g of molecular sieve.
26. A method of preparing a crystalline material having the topology
of zeolite beta comprising impregnating a silica-containing mesoporous
material with an aqueous solution of tetraethylammonium cation in
an amount sufficient to form a crystalline product having the topology
of zeolite beta, and wherein the water to mesoporous material molar
ratio is from about 0.5 to about 2 and subjecting the impregnated
mesoporous material to crystallizing conditions of heat and pressure
for a time sufficient to form crystals of a material having the
topology of zeolite beta.
27. The method of claim 26 wherein the mesoporous material is an
all-silica material.
28. The method of claim 26 wherein the mesoporous material comprises,
in addition to silica, an oxide selected from the group consisting
of aluminum oxide, boron oxide, titanium oxide, vanadium oxide,
zirconium oxide, zinc oxide and mixtures thereof.
29. The method of claim 27 wherein the mesoporous material is MCM-41
or MCM-48.
30. The method of claim 28 wherein the mesoporous material is MCM-41
or MCM-48.
31. A process for converting hydrocarbons comprising contacting
a hydrocarbonaceous feed at hydrocarbon converting conditions with
a catalyst comprising a molecular sieve comprising an silicon oxide,
zinc oxide, and an oxide selected from aluminum oxide, boron oxide,
gallium oxide, iron oxide, vanadium oxide, zirconium oxide, tin
oxide or mixtures thereof and having the framework topology of zeolite
beta.
32. The process of claim 31 wherein the molecular sieve is predominantly
in the hydrogen form.
33. The process of claim 31 wherein the molecular sieve is substantially
free of acidity.
34. The process of claim 31 wherein the process is a hydrocracking
process comprising contacting the catalyst with a hydrocarbon feedstock
under hydrocracking conditions.
35. The process of claim 43 wherein the molecular sieve is predominantly
in the hydrogen form.
36. The process of claim 31 wherein the process is a dewaxing process
comprising contacting the catalyst with a hydrocarbon feedstock
under dewaxing conditions.
37. The process of claim 36 wherein the molecular sieve is predominantly
in the hydrogen form.
38. The process of claim 31 wherein the process is a process for
improving the viscosity index of a dewaxed product of waxy hydrocarbon
feeds comprising contacting the catalyst with a waxy hydrocarbon
feed under isomerization dewaxing conditions.
39. The process of claim 38 wherein the molecular sieve is predominantly
in the hydrogen form.
40. The process of claim 31 wherein the process is a process for
producing a C.sub.20+ lube oil from a C.sub.20+ olefin feed comprising
isomerizing said olefin feed under isomerization conditions over
the catalyst.
41. The process of claim 40 wherein the molecular sieve is predominantly
in the hydrogen form.
42. The process of claim 40 wherein the catalyst further comprises
at least one Group VIII metal.
43. The process of claim 31 wherein the process is a process for
catalytically dewaxing a hydrocarbon oil feedstock boiling above
about 350.degree. F. and containing straight chain and slightly
branched chain hydrocarbons comprising contacting said hydrocarbon
oil feedstock in the presence of added hydrogen gas at a hydrogen
pressure of about 15-3000 psi under dewaxing conditions with the
catalyst.
44. The process of claim 43 wherein the molecular sieve is predominantly
in the hydrogen form.
45. The process of claim 43 wherein the catalyst further comprises
at least one Group VIII metal.
46. The process of claim 43 wherein said catalyst comprises a layered
catalyst comprising a first layer comprising the molecular sieve
and at least one Group VIII metal, and a second layer comprising
an aluminosilicate zeolite which is more shape selective than the
molecular sieve of said first layer.
47. The process of claim 31 wherein the process is a process for
preparing a lubricating oil which comprises: hydrocracking in a
hydrocracking zone a hydrocarbonaceous feedstock to obtain an effluent
comprising a hydrocracked oil; and catalytically dewaxing said effluent
comprising hydrocracked oil at a temperature of at least about 400.degree.
F. and at a pressure of from about 15 psig to about 3000 psig in
the presence of added hydrogen gas with the catalyst.
48. The process of claim 47 wherein the molecular sieve is predominantly
in the hydrogen form.
49. The process of claim 47 wherein the catalyst further comprises
at least one Group VIII metal.
50. The process of claim 31 wherein the process is a process for
isomerization dewaxing a raffinate comprising contacting said raffinate
in the presence of added hydrogen under isomerization dewaxing conditions
with the catalyst.
51. The process of claim 50 wherein the molecular sieve is predominantly
in the hydrogen form.
52. The process of claim 50 wherein the catalyst further comprises
at least one Group VIII metal.
53. The process of claim 50 wherein the raffinate is bright stock.
54. The process of claim 31 wherein the process is a process for
increasing the octane of a hydrocarbon feedstock to produce a product
having an increased aromatics content comprising contacting a hydrocarbonaceous
feedstock which comprises normal and slightly branched hydrocarbons
having a boiling range above about 40.degree. C. and less than about
200.degree. C. under aromatic conversion conditions with the catalyst.
55. The process of claim 54 wherein the molecular sieve is substantially
free of acid.
56. The process of claim 54 wherein the molecular sieve contains
a Group VIII metal component.
57. The process of claim 31 wherein the process is a catalytic
cracking process comprising contacting a hydrocarbon feedstock in
a reaction zone under catalytic cracking conditions in the absence
of added hydrogen with the catalyst.
58. The process of claim 57 wherein the molecular sieve is predominantly
in the hydrogen form.
59. The process of claim 57 wherein the catalyst additionally comprises
a large pore crystalline cracking component.
60. The process of claim 31 wherein the process is a process for
alkylating an aromatic hydrocarbon which comprises contacting under
alkylation conditions at least a molar excess of an aromatic hydrocarbon
with a C.sub.2 to C.sub.20 olefin under at least partial liquid
phase conditions and in the presence of the catalyst.
61. The process of claim 60 wherein the molecular sieve is predominantly
in the hydrogen form.
62. The process of claim 60 wherein the olefin is a C.sub.2 to
C.sub.4 olefin.
63. The process of claim 62 wherein the aromatic hydrocarbon and
olefin are present in a molar ratio of about 4:1 to about 20:1
respectively.
64. The process of claim 62 wherein the aromatic hydrocarbon is
selected from the group consisting of benzene, toluene, ethylbenzene,
xylene, or mixtures thereof.
65. The process of claim 31 wherein the process is a process for
transalkylating an aromatic hydrocarbon which comprises contacting
under transalkylating conditions an aromatic hydrocarbon with a
polyalkyl aromatic hydrocarbon under at least partial liquid phase
conditions and in the presence of the catalyst.
66. The process of claim 65 wherein the molecular sieve is predominantly
in the hydrogen form.
67. The process of claim 65 wherein the aromatic hydrocarbon and
the polyalkyl aromatic hydrocarbon are present in a molar ratio
of from about 1:1 to about 25:1 respectively.
68. The process of claim 65 wherein the aromatic hydrocarbon is
selected from the group consisting of benzene, toluene, ethylbenzene,
xylene, or mixtures thereof.
69. The process of claim 65 wherein the polyallyl aromatic hydrocarbon
is a dialkylbenzene.
70. The process of claim 31 wherein the process is a process to
convert paraffins to aromatics which comprises contacting paraffins
under conditions which cause paraffins to convert to aromatics with
a catalyst comprising the molecular sieve and gallium, zinc, or
a compound of gallium or zinc.
71. The process of claim 31 wherein the process is a process for
isomerizing olefins comprising contacting said olefin under conditions
which cause isomerization of the olefin with the catalyst.
72. The process of claim 31 wherein the process is a process for
isomerizing an isomerization feed comprising an aromatic C.sub.8
stream of xylene isomers or mixtures of xylene isomers and ethylbenzene,
wherein a more nearly equilibrium ratio of ortho-, meta and para-xylenes
is obtained, said process comprising contacting said feed under
isomerization conditions with the catalyst.
73. The process of claim 31 wherein the process is a process for
oligomerizing olefins comprising contacting an olefin feed under
oligomerization conditions with the catalyst.
74. A process for converting lower alcohols and other oxygenated
hydrocarbons comprising contacting said lower alcohol or other oxygenated
hydrocarbon under conditions to produce liquid products with a catalyst
comprising a molecular sieve comprising silicon oxide, zinc oxide,
and an oxide selected from aluminum oxide, boron oxide, gallium
oxide, iron oxide or mixtures thereof and having the framework topology
of zeolite beta.
75. In a process for the reduction of oxides of nitrogen contained
in a gas stream in the presence of oxygen wherein said process comprises
contacting the gas stream with a molecular sieve, the improvement
comprising using as the molecular sieve a molecular sieve comprising
silicon oxide, zinc oxide, and an oxide selected from aluminum oxide,
boron oxide, gallium oxide, iron oxide, vanadium oxide, zirconium
oxide, tin oxide or mixtures thereof and having the framework topology
of zeolite beta, wherein the molecular sieve contains zinc in its
crystal framework.
76. The process of claim 75 wherein said molecular sieve contains
a metal or metal ions capable of catalyzing the reduction of the
oxides of nitrogen.
77. The process of claim 76 wherein the metal is copper, cobalt
or mixtures thereof.
78. The process of claim 76 wherein the gas stream is the exhaust
stream of an internal combustion engine.
79. A method of removing liquid organic compounds from a mixture
of liquid organic compounds and water, comprising contacting the
mixture with an all-silica molecular sieve having the framework
topology of zeolite beta, a crystal size less than one micron and
a water adsorption capacity of less than 0.05 g/g of molecular sieve.
80. A method of removing liquid organic compounds from a mixture
of liquid organic compounds and water, comprising contacting the
mixture with a molecular sieve comprising an oxide of silicon, an
oxide of zinc and, optionally, an oxide selected from aluminum oxide,
boron oxide, gallium oxide, iron oxide and mixtures thereof, and
having the framework topology of zeolite beta, wherein the molecular
sieve contains zinc in its crystal framework.
Molecular sieve description
[0001] This application is a continuation-in-part of application
Ser. No. 09/106598 filed Jun. 29 1998.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to new crystalline molecular
sieve CIT-6 a method for preparing CIT-6 using a tetraethylammonium
cation templating agent, a method of using CIT-6 as a precursor
for making other crystalline molecular sieves, and processes employing
CIT-6 as a catalyst.
[0004] 2. State of the Art
[0005] Because of their unique sieving characteristics, as well
as their catalytic properties, crystalline molecular sieves are
especially useful applications such as hydrocarbon conversion, gas
drying and separation. Although many different crystalline molecular
sieves have been disclosed, there is a continuing need for new molecular
sieves with desirable properties for gas separation and d hydrocarbon
and chemical conversions, and other applications. New molecular
sieves may contain novel internal pore architectures, providing
enhanced selectivities in these processes.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a crystalline molecular
sieve with unique properties, referred to herein as "molecular
sieve CIT-6" or simply "CIT-6". When the CIT-6 contains
a metal (or non-silicon) oxide, such as aluminum oxide, boron oxide,
titanium oxide or iron oxide, it is referred to as "catalytically
active" CIT-6.
[0007] The CIT-6 can be made in two forms. The first contains silicon
oxide, zinc oxide and optional metal (or non-silicon) oxides (such
as aluminum oxide), wherein the zinc is in the crystal framework
of the CIT-6. This form of CIT-6 is referred to herein as "Zn-CIT-6".
Another form of CIT-6 is where the molecular sieve is composed only
of silicon oxide. This form of CIT-6 is referred to herein as "all-Si
CIT-6".
[0008] Zn-CIT-6 and all-Si CIT-6 each have die topology of zeolite
beta.
[0009] In accordance with this invention, there is provided a molecular
sieve comprising an oxide of silicon and an oxide of zinc and having
the framework topology of zeolite beta, wherein the molecular sieve
contains zinc in its crystal framework.
[0010] The present invention further provides such a molecular
sieve having the topology of zeolite beta, and having a composition,
as synthesized and in the anhydrous state, in terms of mole ratios
as follows:
1 SiO.sub.2/ZnO 10-100 M/SiO.sub.2 0.01-0.1 Q/SiO.sub.2 0.07-0.14
[0011] wherein M is lithium or a mixture of lithium and another
alkali metal, and Q comprises a tetraethylammonium cation, wherein
the molecular sieve contains zinc in its crystal framework.
[0012] Also in accordance with this invention there is provided
a molecular sieve comprising silicon oxide, zinc oxide, and an oxide
selected from aluminum oxide, boron oxide, gallium oxide, iron oxide,
titanium oxide, vanadium oxide, zirconium oxide, tin oxide or mixtures
thereof and having the framework topology of zeolite beta, wherein
the molecular sieve contains zinc in its crystal framework.
[0013] The present invention also provides such a molecular sieve
having the topology of zeolite beta, and having a composition, as
synthesized and in the anhydrous state, in terms of mole ratios
as follows:
2 SiO.sub.2/ZnO 10-100 SiO.sub.2/W 30-250 M/SiO.sub.2 0.01-0.1
Q/SiO.sub.2 0.07-0.14
[0014] wherein W is an oxide of aluminum, boron, gallium, vanadium,
iron, titanium or mixture thereof M is lithium or a mixture of lithium
and another alkali metal, and Q comprises a tetraethylammonium cation,
wherein the molecular sieve contains zinc in its crystal framework.
[0015] Also provided in accordance with the present invention is
a method of preparing a crystalline material comprising an-oxide
of silicon and an oxide of zinc and having the framework topology
of zeolite beta, wherein the molecular sieve contains zinc in its
crystal framework, said method comprising contacting in admixture
under crystallization conditions sources of said oxides, a source
of lithium or a mixture of lithium and another alkali metal and
a templating agent comprising a tetraethylammonium cation.
[0016] The present invention also provides a method of preparing
a crystalline material comprising an oxide of silicon, an oxide
of zinc and an oxide selected from aluminum oxide, boron oxide,
gallium oxide, vanadium oxide, iron oxide, titanium oxide or mixtures
thereof and having the framework topology of zeolite beta, wherein
the molecular sieve contains zinc in its crystal framework, said
method comprising contacting in admixture under crystallization
conditions sources of said oxides, a source of lithium or a mixture
of lithium and another alkali metal and a templating agent comprising
a tetraethylammonium cation.
[0017] Further provided by the present invention is a method of
removing a tetraethylammonium organic template from the pores of
a molecular sieve, said method comprising contacting the molecular
sieve with acetic acid, or a mixture of acetic acid and pyridine
at elevated temperature for a time sufficient to remove essentially
all of the tetraethylammonium organic template from the molecular
sieve. Ina preferred embodiment, the molecular sieve has the topology
of zeolite beta.
[0018] The present invention further provides a method of removing
an organic template from the pores of a molecular sieve and at the
same time removing zinc atoms from the framework of the molecular
sieve, wherein the molecular sieve comprises an oxide of silicon,
an oxide of zinc and, optionally an oxide selected from aluminum
oxide, boron oxide, gallium oxide, vanadium oxide, iron oxide, titanium
oxide or mixtures thereof, and has the framework topology of zeolite
beta, said method comprising contacting the molecular sieve with
acetic acid or a mixture of acetic acid and pyridine at elevated
temperature for a time sufficient to remove essentially all of the
organic template and zinc from the molecular sieve. The present
invention also provides the product of this method.
[0019] Also provided by the present invention is a method of making
a crystalline material comprising (1) contacting in admixture under
crystallization conditions a source of silicon oxide, a source of
zinc oxide, a source of lithium or a mixture of lithium and another
alkali metal and a templating agent comprising a tetraethylammonium
cation until a crystalline material comprised of oxides of silicon
and zinc and having the topology of zeolite beta is formed, (2)
contacting the crystals with acetic acid or a mixture of acetic
acid and pyridine at an elevated temperature of about 60.degree.
C. or less for a time sufficient to remove essentially all of the
organic template and zinc from the cystals, and (3) contacting the
crystals with a solution containing a source of aluminum, boron
gallium, iron, vanadium, titanium, zirconium, tin or mixtures thereof.
The present invention also provides the product of this method.
[0020] This invention also provides a crystalline molecular sieve
having the topology of zeolite beta, a crystal size of less than
one micron and a water adsorption capacity of less than 0.05 g/g
of molecular sieve.
[0021] Further provided by the present invention is a crystalline
silicate molecular sieve having the topology of zeolite beta, a
crystal size of less than one micron and a water adsorption capacity
of less than 0.05 g/g of molecular sieve.
[0022] In addition, the present invention provides a method of
preparing a crystalline material having the topology of zeolite
beta comprising impregnating a silica-containing mesoporous material
with an aqueous solution comprising tetraethylammonium cation in
an amount sufficient to form a crystalline product having the topology
of zeolite beta, and wherein the water to mesoporous material molar
ratio is from about 0.5 to about 2 and subjecting the impregnated
mesoporous material to crystallizing conditions of heat and pressure
for a time sufficient to form crystals of a material having the
topology of zeolite beta.
[0023] The present invention additionally provides a process for
converting hydrocarbons comprising contacting a hydrocarbonaceous
feed at hydrocarbon converting conditions with a catalyst comprising
a catalytically active molecular sieve comprising silicon oxide,
zinc oxide, and an oxide selected from aluminum oxide, boron oxide,
gallium oxide, iron oxide, zirconium oxide, tin oxide or mixtures
thereof and having the frameworking topology of zeolite beta, wherein
the molecular sieve contains zinc in its crystal framework. The
molecular sieve may be predominantly in the hydrogen form, partially
acidic or substantially free of acidity, depending on the process.
[0024] Further provided by the present invention is a hydrocracking
process comprising contacting a hydrocarbon feedstock under hydrocracking
conditions with a catalyst comprising the catalytically active molecular
sieve of this invention, preferably predominantly in the hydrogen
form.
[0025] This invention also includes a dewaxing process comprising
contacting a hydrocarbon feedstock under dewaxing conditions with
a catalyst comprising the catalytically active molecular sieve of
this invention, preferably predominantly in the hydrogen form.
[0026] The present invention also includes a process for improving
the viscosity index of a dewaxed product of waxy hydrocarbon feeds
comprising contacting the waxy hydrocarbon feed under isomerization
dewaxing conditions with a catalyst comprising the catalytically
active molecular sieve of this invention, preferably predominantly
in the hydrogen form.
[0027] The present invention further includes a process for producing
a C.sub.20+ lube oil from a C.sub.20+ olefin feed comprising isomerizing
said olefin feed under isomerization conditions over a catalyst
comprising at least one Group VIII metal and the catalytically active
molecular sieve of this invention. The molecular sieve may be predominantly
in the hydrogen form.
[0028] In accordance with this invention, there is also provided
a process for catalytically dewaxing a hydrocarbon oil feedstock
boiling above about 350.degree. F. and containing straight chain
and slightly branched chain hydrocarbons comprising contacting said
hydrocarbon oil feedstock in the presence of added hydrogen gas
at a hydrogen pressure of about 15-3000 psi with a catalyst comprising
at least one Group VIII metal and the catalytically active molecular
sieve of this invention, preferably predominantly in the hydrogen
form The catalyst may be a layered catalyst comprising a first layer
comprising at least one Group VIII metal and the catalytically active
molecular sieve of this invention, and a second layer comprising
an aluminosilicate zeolite which is more shape selective than the
catalytically active molecular sieve of said first layer.
[0029] Also included in the present invention is a process for
preparing a lubricating oil which comprises hydrocracking in a hydrocracking
zone a hydrocarbonaceous feedstock to obtain an effluent comprising
a hydrocracked oil, and catalytically dewaxing said effluent comprising
hydrocracked oil at a temperature of at least about 400.degree.
F. and at a pressure of from about 15 psig to about 3000 psig in
the presence of added hydrogen gas with a catalyst comprising at
least one Group VIII metal and the catalytically active molecular
sieve of this invention. The molecular sieve may be predominantly
in the hydrogen form.
[0030] Further included in this invention is a process for isomerization
dewaxing a raffinate comprising contacting said raffinate in the
presence of added hydrogen with a catalyst comprising at least one
Group VIII metal and the catalytically active molecular sieve of
this invention. The raffinate maybe bright stock, and the molecular
sieve may be predominantly in the hydrogen form.
[0031] Also included in this invention is a process for increasing
the octane of a hydrocarbon feedstock to produce a product having
an increased aromatics content comprising contacting a hydrocarbonaceous
feedstock which comprises normal and slightly branched hydrocarbons
having a boiling range above about 40.degree. C. and less than about
200.degree. C., under aromatic conversion conditions with a catalyst
comprising the catalytically active molecular sieve of this invention
made substantially free of acidity by neutralizing said molecular
sieve with a basic metal. Also provided in this invention is such
a process wherein the molecular sieve contains a Group VIII metal
component.
[0032] Also provided by the present invention is a catalytic cracking
process comprising contacting a hydrocarbon feedstock in a reaction
zone under catalytic cracking conditions in the absence of added
hydrogen with a catalyst comprising the catalytically active molecular
sieve of this invention, preferably predominantly in the hydrogen
form. Also included in this invention is such a catalytic cracking
process wherein the catalyst additionally comprises a large pore
crystalline cracking component.
[0033] Also provided by the present invention is a process for
alkylating an aromatic hydrocarbon which comprises contacting under
alkylation conditions at least a molar excess of an aromatic hydrocarbon
with a C.sub.2 to C.sub.20 olefin under at least partial liquid
phase conditions and in the presence of a catalyst comprising the
catalytically active molecular sieve of this invention, preferably
predominantly in the hydrogen form. The olefin may be a C.sub.2
to C.sub.4 olefin, and the aromatic hydrocarbon and olefin may be
present in a molar ratio of about 4:1 to about 20:1 respectively.
The aromatic hydrocarbon may be selected from the group consisting
of benzene, toluene, ethylbenzene, xylene, or mixtures thereof.
[0034] Further provided in accordance with this invention is a
process for transalkylating an aromatic hydrocarbon which comprises
contacting under transalkylating conditions an aromatic hydrocarbon
with a polyalkyl aromatic hydrocarbon under at least partial liquid
phase conditions and in the presence of a catalyst comprising the
catalytically active molecular sieve of this invention, preferably
predominantly in the hydrogen form. The aromatic hydrocarbon and
the polyalkyl aromatic hydrocarbon may be present in a molar ratio
of from about 1:1 to about 25:1 respectively. The aromatic hydrocarbon
may be selected from the group consisting of benzene, toluene, ethylbenzene,
xylene, or mixtures thereof, and the polyalkyl aromatic hydrocarbon
may be a dialkylbenzene.
[0035] Further provided by this invention is a process to convert
paraffins to aromatics which comprises contacting paraffins under
conditions which cause paraffins to convert to aromatics with a
catalyst comprising the catalytically active molecular sieve of
this invention, said catalyst comprising gallium, zinc, or a compound
of gallium or zinc.
[0036] In accordance with this invention there is also provided
a process for isomerizing olefins comprising contacting said olefin
under conditions which cause isomerization of the olefin with a
catalyst comprising the catalytically active molecular sieve of
this invention.
[0037] Further provided in accordance with this invention is a
process for isomerizing an isomerization feed comprising an aromatic
C.sub.8 stream of xylene isomers or mixtures of xylene isomers and
ethylbenzene, wherein a more nearly equilibrium ratio of ortho-,
meta- and para-xylenes is obtained, said process comprising contacting
said feed under isomerization conditions with a catalyst comprising
the catalytically active molecular sieve of this invention.
[0038] The present invention further provides a process for oligomerizing
olefins comprising contacting an olefin feed under oligomerization
conditions with a catalyst comprising the catalytically active molecular
sieve of this invention.
[0039] This invention also provides a process for converting lower
alcohols and other oxygenated hydrocarbons comprising contacting
said lower alcohol or other oxygenated hydrocarbon with a catalyst
comprising the catalytically active molecular sieve of this invention
under conditions to produce liquid products.
[0040] Also provided by the present invention is an improved process
for the reduction of oxides of nitrogen contained in a gas stream
in the presence of oxygen wherein said process comprises contacting
the gas stream with a molecular sieve, the improvement comprising
using as the molecular sieve, the molecular sieve of this invention.
The molecular sieve may contain a metal or metal ions (such as cobalt,
copper or mixtures thereof) capable of catalyzing the reduction
of the oxides of nitrogen, and may be conducted in the presence
of a stoichiometric excess of oxygen. In a preferred embodiment,
the gas stream is the exhaust stream of an internal combustion engine.
[0041] Further provided by the present invention is a method of
removing liquid organic compounds from a mixture of liquid organic
compounds and water, comprising contacting the mixture with an all-silica
molecular sieve having the framework topology of zeolite beta, a
crystal size less than one micron and a water adsorption capacity
of less than 0.05 g/g of molecular sieve.
[0042] The present invention further provides a method of removing
liquid organic compounds from a mixture of liquid organic compounds
and water, comprising contacting the mixture with a molecular sieve
comprising an oxide of silicon, an oxide of zinc and, optionally,
an oxide selected from aluminum oxide, boron oxide, gallium oxide,
iron oxide, vanadium oxide, titanium oxide, zirconium oxide, tin
oxide and mixtures thereof, and having the framework topology of
zeolite beta, wherein the molecular sieve contains zinc in its crystal
framework.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIGS. 1 and 2 show the results of water adsorption isotherms
at 25.degree. C. of the molecular sieves of this invention and beta
zeolite.
DETAILED DESCRIPTION OF TH INVENTION
[0044] In preparing CIT-6 molecular sieves, a tetraethylammonium
cation ("TEA") is used as a crystallization template (--also
known as a structure directing agent, or SDA). The anion associated
with the cation may be any anion which is not detrimental to the
formation of the molecular sieve. Representative anions include
halogen, e.g., fluoride, chloride, bromide and iodide, hydroxide,
acetate, sulfate, tetrafluoroborate, carboxylate, and the like.
Hydroxide is the most preferred anion.
[0045] In general Zn-CIT-6 is prepared by contacting an active
source of silicon oxide, an active-source of zinc oxide, an active
source of lithium or mixture of lithium and another alkali metal
with the TEA templating agent.
[0046] Zn-CIT-6 is prepared from a reaction mixture having the
following composition:
bM:cTA:aZnO:SiO2:dH2O
[0047] where M is lithium or a mixture of lithium and another alkali
metal, b=0.05-0.1; c=0.55-0.7; a=0.03-0.05; d=30-40. It is believed
the concentrations of Li.sup.+, Zn.sup.2+ and TEAOH are critical
to the formation of Zn-CIT-6.
[0048] When it is desired to prepare Zn-CIT-6 containing zinc oxide
in combination with another metal oxide, such as aluminum oxide,
a reaction mixture having the following composition:
bM:cTEA:aZnO:SiO2:e:dH2O
[0049] where M is lithium or a mixture of lithium and another alkali
metal, W is an oxide of aluminum, boron, gallium, vanadium, iron,
titanium or mixtures thereof; b, c, a and d are as defined above
and c=0.005-0.1.
[0050] In practice, Zn-CIT-6 is prepared by a process comprising:
[0051] (a) preparing an aqueous solution containing sources of
silicon oxide, zinc oxide, lithium or a mixture of lithium and another
alkali metal, TEA having an anionic counterion which is not detrimental
to the formation of Zn-CIT-6 and, optionally, an oxide selected
from aluminum oxide, boron oxide, gallium oxide, vanadium oxide,
iron oxide, titanium oxide or mixtures thereof;
[0052] (b) maintaining the aqueous solution under conditions sufficient
to form crystals of Zn-CIT-6; and
[0053] (c) recovering the crystals of Zn-CIT-6.
[0054] The aqueous solution prepared in step (a) should be a clear
solution. In some cases, heating a reaction mixture that is a white,
cloudy mixture at room temperature will convert the mixture to a
clear solution from which Zn-CIT-6 will form.
[0055] It has been discovered that higher amounts of TEA and lower
reaction temperatures favor the formation of Zn-CIT-6.
[0056] Typical sources of silicon oxide include silicates, silica
hydrogel silicic acid, fumed silica, colloidal silica, tetra-alkyl
orthosilicates, and silica hydroxides. Typical sources of zinc oxide
include water-soluble zinc salts, such as zinc acetate. Typical
sources of aluminum oxide for the reaction mixture include aluminates,
alumina, aluminum colloids, aluminum oxide coated on silica sol,
and hydrated alumina gels such as Al(OH).sub.3. Sources of boron,
gallium, vanadium, iron and titanium compounds analogous to those
listed for silicon and aluminum, and are known in the art.
[0057] Lithium or a mixture of lithium and another alkali metal
is added to the reaction mixture. A variety of sources can be used,
such as alkali metal hydroxides and alkali metal carbonates, with
lithium hydroxide being particularly preferred. The lithium cation
may be part of the as-synthesized crystalline oxide material, in
order to balance valence electron charges therein. Other alkali
metals which can be used in combination with the lithium include
sodium and potassium, with the hydroxides being preferred, provided
that lithium is the predominant alkali metal in the combination.
The alkali metal (i.e., lithium or mixture of lithium and another
alkali metal) may be employed in an amount of from about 0.05 to
about 0.1 mole of alkali metal per mole of silica.
[0058] The reaction mixture is maintained at an elevated temperature
until the crystals of the Zn-CIT-6 molecular sieve are formed. The
hydrothermal crystallization is usually conducted under autogenous
pressure, at about 100.degree. C. to less than about 150.degree.
C. It has been discovered that higher reaction temperatures, e.g.,
150.degree. C. and higher, favor the formation of a molecular sieve
having the topology of zeolite VPI-8 rather than the desired molecular
sieve with the topology of zeolite beta. Preferably, the reaction
temperature should be about 135.degree. C. to 150.degree. C.
[0059] The crystallization period is typically greater than 1 day
to less than 7 days. The Zn-CIT-6 crystals should be recovered from
the reaction mixture as soon as they form, since it has been discovered
that under some circumstances if they remain in the reaction mixture
for too long after formation, they can convert to a molecular sieve
having the topology of VPI-8.
[0060] During the hydrothermal crystallization step, the Zn-CIT-6
crystals an be allowed to nucleate spontaneously from the reaction
mixture. The use of Zn-CIT-6 crystals as seed material can be advantageous
in deceasing the time necessary for complete crystallization to
occur. In addition, seeding can lead to an increased purity of the
product obtained by promoting the nucleation and/or formation of
Zn-CIT-6 over any undesired phases. When used as seeds, Zn-CIT-6
crystals are added in an amount between 0.1 and 10% ofthe weight
of silica used in the reaction mixture.
[0061] Once the molecular sieve crystals have formed, the solid
product is separated from the reaction mixture by standard mechanical
separation techniques such as filtration. The crystals h and then
dried, e.g., at 90.degree. C. to 150.degree. C. for from 8 to 24
hours, to obtain the as-synthesized Zu-CIT-6 molecular sieve crystals.
The drying step can be performed at atmospheric pressure or under
vacuum.
[0062] Zn-CIT-6 has a composition, as synthesized and in the anhydrous
state, in terms of mole ratios, shown in Table B below.
3TABLE B As-Synthesized Zn-CIT-6 SiO.sub.2/ZnO 10-100 M/SiO.sub.2
0.01-0.1 Q/SiO.sub.2 0.07-0.14
[0063] where M and Q are as defined above.
[0064] Zn-CIT-6 can also have a composition, as synthesized and
in the anhydrous state, in terms of mole ratios, shown in Table
C below.
4TABLE C As-Synthesized Zn-CIT-6 SiO.sub.2/ZnO 10-100 SiO.sub.2/W
30-250 M/SiO.sub.2 0.01-0.1 Q/SiO.sub.2 0.07-0.14
[0065] where W, M and Q are as defined above.
[0066] Solid state .sup.29Si NMR analysis and acidity measurements
have shown that at least part of the zinc is in the framework of
the Zn-CIT-6 crystals. Indeed, in one embodiment, the Zn-CIT-6 crystal
framework contains only silicon, zinc and oxygen atoms, i.e., there
are no other metals in this form of Zn-CIT-6.
[0067] Once the Zn-CIT-6 crystals have been formed and recovered,
the organic template should be removed. This is typically done by
calcining the crystals at high temperature until the organic template
is removed. However, it has been discovered that calcination can
be avoided by extracting the organic template from the molecular
sieve. This extraction technique has advantages over calcination.
For example, no calcination equipment is needed. Also, the organic
template is not destroyed by the extraction, so it may be possible
to recycle it, thereby reducing the cost of making the molecular
sieve.
[0068] The organic template can be removed by contacing the Zn-CIT-6
crystals with acetic acid or a mixture of acetic acid and pyridine
at a temperature of about 80.degree. C. to about 135.degree. C.
for a period sufficient to remove essentially all of the organic
template from the crystals (typically about two days). At the same
time, the zinc is removed from the crystals, and they convert to
all-Si CIT-6 i.e., an all-silica crystal having the framework topology
of zeolite beta. As shown by water adsorption isotherms, all-Si
CIT-6 is highly hydrophobic. .sup.29Si NMR analysis further shows
that the crystal lattice has virtually no defects.
[0069] It has quite surprisingly been found that CIT-6 prepared
as described above, i.e., the CIT-6 is prepared and then contacted
with acetic acid or a mixture of acetic acid and pyridine at a temperature
of about 80.degree. C. to about 135.degree. C. (referred to herein
as "extraction"), is highly hydrophobic. This is in marked
contrast to CIT-6 or beta zeolite in which the organic template
has been removed by calcination.
[0070] This phenomenon is illustrated in the FIG. 1. Five water
adsorption isotherms are shown for the following materials:
[0071] (a) All-Si-CIT-6 prepared by extraction at 135.degree. C.
[0072] (b) Zn-CIT-6 prepared using calcination
[0073] (c) Silicoalumino-CIT-6 extracted at 60.degree. C. followed
by insertion of aluminum
[0074] (d) Silicoalumino-CIT-6 prepared using aluminum oxide in
the reaction mixture with the product extracted at 135.degree. C.
[0075] (e) Calcined all-silica beta zeolite
[0076] The data indicate that the extracted aluminum-containing
CIT-6 (sample d) is more hydrophobic than the sample prepared via
aluminum insertion (sample c) and far more hydrophobic than the
calcined zeolite beta (sample e). Calcined Zn-CIT-6 (sample b) likewise
is far more hydrophobic than calcined zeolite beta, with extracted
all-Si-CIT-6 (sample a) exhibiting the highest degree of hydrophobicity.
[0077] Alternatively, the extraction or removal of the organic
template from Zn-CIT-6 can be accomplished by contacting the Zn-CIT-6
crystal with acetic acid or a mixture of acetic acid and pyridine
at an elevated temperature of about 60.degree. C. or less for a
period sufficient to remove essentially all of the organic template
from the crystals.
[0078] It has also been found that this latter action technique
also removes some or all of the zinc atoms from the crystal framework.
However, in this case the resultant molecular sieve contains internal
silanol groups and other metals (or non-silicon atoms), such as
aluminum, boron, gallium, vanadium, iron, titanium, zirconium, tin
or mixes thereof can be inserted into the crystal framework, replacing
the zinc.
[0079] The metal can be inserted into the crystal framework by
contacting the molecular sieve with a solution containing a source,
such as a salt, of the desired metal. Although a wide variety of
sources can be employed, chlorides and other halides, acetates,
nitrates, and sulfates are particularly preferred. The preferred
metals (or non-silicon atoms) are aluminum, boron, gallium, iron,
titanium, vanadium, zirconium, tin, zinc and mixtures thereof. Representative
techniques for inserting the metal are disclosed in a wide variety
of patents including U.S. Pat. No. 3140249 issued Jul. 7 1964
to Plank et al.; U.S. Pat. No. 3140251 issued on Jul. 7 1964to
Plank et al.; and U.S. Pat. No. 3140253 issued on Jul. 7 1964
to Plank et al., each of which is incorporated by reference herein.
By way of example, aluminum can be inserted into the molecular sieve
in place of some or all of the zinc by extracting the zinc (at about
60.degree. C.) as described above, and then contacting the molecular
sieve with an aluminum nitrate solution in about a 1:2:50 weight
ratio of sieve: aluminum nitrate: water at about 80.degree. C. for
about one day.
[0080] As an alternative to making Zn-CIT-6 extracting the zinc
and inserting, e.g., aluminum, an aluminosilicate can be made directly
by synthesizing aluminozincosilicate CIT-6 as described above and
in Example 27 and then extracting the zinc at the higher extraction
temperature (135.degree. C.). This removes the zinc from the CIT-6
and leaves an aluminosilicate molecular sieve with the topology
of zeolite beta. .sup.27Al NMR analysis of aluminosilicates made
in this manner shows that the aluminum remains in the crystal framework.
[0081] All-Si CIT-6 can be made by preparing Zn-CIT-6 as described
above, followed by extraction of the zinc. It has surprisingly been
found that all-Si CIT-6 made by this method has a much lower water
adsorption capacity than all-silica zeolite beta made by traditional
methods. The all-Si CIT-6 made by this method also has a crystal
size of less than about one micron, whereas all-silica zeolite beta
made by traditional method has a crystal size of greater than one
micron, e.g., on the order of five microns. Furthermore, the all-Si
CIT-6 made by this method has essentially no defect (i.e., Si--OH
instead of Si--O--Si) sites, whereas all-silica zeolite beta made
by traditional methods does contain defect sites that adsorb water.
[0082] A series of silica-containing mesoporous materials denoted
M41S have been reported. These materials have been further classified,
e.g., MCM-41 (hexagonal), MCM-48 (cubic) and others. These materials
have uniform pores of 1.5-10 nm diameters, and are made by using
a variety of surfactants as structure-directing agents. Non-silicon
atom, e.g., Al, B, Ga, Ti, V, Zr, Fe, Mn, Sn, Zn, Ca and Nb, containing
mesoporous materials have also been prepared.
[0083] The inorganic portion of MCM-41 resembles amorphous silicas
rather than crystalline molecular sieves in terms of the local structure
and bonding, but has many peculiar properties. It possesses uniformly
sized mesopores with thin walls (around 10 Angstroms) and shows
hydrophobic adsorption behavior.
[0084] It has now been discovered that zeolites having the topology
of zeolite beta, in either all-silica form or in a form containing
silica and metal (or non-silicon) oxide(s), can be made using the
inorganic portion of ordered, mesoporous materials as reagents.
The mesoporous materials may be all-silica, or they may contain
silica and metal (or non-silicon) oxide(s), e.g., aluminum oxide.
Examples of such mesoporous materials include, but are not limited
to, MCM-41 and MCM-48.
[0085] The mesoporous materials are used in combination with tetraethylammonium
cation organic templating agent, e.g., tetraethylammonium hydroxide
(TEAOH). It has been found that, in order to assure the zeolite
beta has essentially no defect sites, the reaction mixture containing
the mesoporous material and TEAOH should be in the form of a "dry
gel". The dry gel is made by impregnating the mesoporous material
with an aqueous solution of TEAOH, allowing the resulting impregnated
material to dry for about one day at room temperature. The thus-impregnated
product should have a molar ratio of water to mesoporous material
of about 0.5 to about 2 and contain sufficient TEAOH to cause formation
of the beta structure. The impregnated material is then subject
to crystallization conditions in an autoclave. The resulting crystalline
product can either be calcined to remove the TEAOH, or it can be
subjected to the extraction technique described above, thus assuring
the product will be essentially defect-free.
[0086] If it is desired that the final product contain silicon
oxide and a metal (or non-silicon) oxide, the mesoporous starting
material can contain-silicon oxide and the desired metal (or non-silicon)
oxide. Metal oxides such as aluminum oxide, titanium oxide, vanadium
oxide, zinc oxide, zirconium oxide, and magnesium oxide, as well
as non-silicon oxides such as boron oxide, can be incorporated into
the zeolite beta structure in this manner.
[0087] The molecular sieves made by either of these two techniques
are highly hydrophobic. FIG. 2 shows the results of water adsorption
isotherms for calcined all-silica beta zeolite (line 1), all-Si
CIT-6 made from MCM-41 and subjected to extraction rather than calcination
(line 2), and Zn-CIT-6 made by extraction (line 3). As can be seen,
the water adsorption capacities of both the all-Si CIT-6 and Zn-CIT-6
are substantially lower than that of calcined all-silica beta zeolite.
[0088] When used in a catalyst, the molecular sieve can be used
in intimate combination with hydrogenating components, such as tungsten,
vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese,
or a noble metal, such as palladium or platinum, for those applications
in which a hydrogenation-dehydrogenation function is desired.
[0089] Metals may also be introduced into the molecular sieve by
replacing some of the cations in the molecular sieve with metal
cations via standard ion exchange techniques (see, for example,
U.S. Pat. No. 3140249 issued Jul. 7 1964 to Plank et al.; U.S.
Pat. No. 3140251 issued Jul. 7 1964 to Plank et al.; and U.S.
Pat. No. 3140253 issued Jul. 7 1964 to Plank et al.). Typical
replacing cations can include metal cations, e.g., rare earth, Group
IA, Group IIA and Group VIII metals, as well as their mixtures.
Of the replacing metallic cations, cations of metals such as rare
earth, Mn, Ca, Mg, Zn, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, and Fe are
particularly preferred.
[0090] The hydrogen, ammonium, and metal components can be ion-exchanged
into the catalytically active CIT-6. The molecular sieve can also
be impregnated with the metals, or, the metals can be physically
and intimately admixed with the molecular sieve using standard methods
known to the art.
[0091] Typical ion-exchange techniques involve contacting the synthetic
molecular sieve with a solution containing a salt of the desired
replacing cation or cations. Although a wide variety of salts can
be employed, chlorides and other halides, acetates, nitrates, and
sulfates are particularly preferred. The molecular sieve is usually
calcined prior to the ion-exchange procedure to remove the organic
matter present in the channels and on the surface, since this results
in a more effective ion exchange. Representative ion exchange techniques
are disclosed in a wide variety of patents including U.S. Pat. No.
3140249 issued on Jul. 7 1964 to Plank et al.; U.S. Pat. No.
3140251 issued on Jul. 7 1964 to Plank et at; and U.S. Pat. No.
3140253 issued on Jul. 7 1964 to Plank et al.
[0092] Following contact with the salt solution of the desired
replacing cation, the molecular is typically washed with water and
dried at temperatures ranging from 65.degree. C. to about 200.degree.
C. After washing, the molecular sieve can be calcined in air or
inert gas at temperatures ranging from about 200.degree. C. to about
800.degree. C. for periods of time ranging from 1 to 48 hours, or
more, to produce a catalytically active product especially useful
in hydrocarbon conversion processes.
[0093] Regardless of the cations present in the synthesized form
of CIT-6 the spatial arrangement of the atoms which form the basic
crystal lattice of the molecular sieve remains essentially unchanged.
[0094] Catalytically active CIT-6 can be formed into a wide variety
of physical shapes. Generally speaking, the molecular sieve can
be in the form of a powder, a granule, or a molded product, such
as extrudate having a particle size sufficient to pass through a
2-mesh (Tyler) screen and be retained on a 400-mesh (Tyler) screen.
In cases where the catalyst is molded, such as by extrusion with
an organic binder, the molecular sieve can be extruded before drying,
or, dried or partially dried and then extruded.
[0095] Catalytically active CIT-6 can be composited with other
materials resistant to the temperatures and other conditions employed
in organic conversion processes. Such matrix materials include active
and inactive materials and synthetic or naturally occurring zeolites
as well as inorganic materials such as clays, silica and metal oxides.
Examples of such materials and the manner in which they can be used
are disclosed in U.S. Pat. No. 4910006 issued May 20 1990 to
Zones et al., and U.S. Pat. No. 5316753 issued May 31 1994 to
Nakagawa, both of which are incorporated by reference herein in
their entirety.
[0096] Hydrocarbon Conversion Processes
[0097] The catalytically active CIT-6 molecular sieves are useful
in hydrocarbon conversion reactions. Hydrocarbon conversion reactions
are chemical and catalytic processes in which carbon containing
compounds are changed to different carbon containing compounds.
Examples of hydrocarbon conversion reactions in which catalytically
active CIT-6 is expected to be useful include hydrocracking, dewaxing,
catalytic cracking and olefin and aromatics formation reactions.
The catalysts are also expected to be useful in other petroleum
refining and hydrocarbon conversion reactions such as polymerizing
and oligomerizing olefinic or aceylenic compounds such as isobutylene
and butene-1 reforming, isomerizing polyalkyl substituted aromatics
(e.g., m-xylene), and disproportionating aromatics (e.g., toluene)
to provide mixtures of benzene, xylenes and higher methylbenzenes
and oxidation reactions. Also included are rearrangement reactions
to make various naphthalene derivatives. The catalytically active
CIT-6 catalysts may have high selectivity, and under hydrocarbon
conversion conditions can provide a high percentage of desired products
relative to total products.
[0098] The catalytically active CIT-6 molecular sieves can be used
in processing hydrocarbonaceous feedstocks. Hydrocarbonaceous feedstocks
contain carbon compounds and can be from many different sources,
such as virgin petroleum fractions, recycle petroleum fractions,
shale oil, liquefied coal, tar sand oil, synthetic paraffins from
NAO, recycled plastic feedstocks and, in general, can be any carbon
containing feedstock susceptible to zeolitic catalytic reactions.
Depending on the type of processing the hydrocarbonaceous feed is
to undergo, the feed can contain metal or be free of metals, it
can also have high or low nitrogen or sulfur impurities. It can
be appreciated, however, that in general processing will be more
efficient (and the catalyst more active) the lower the metal, nitrogen,
and sulfur content of the feedstock.
[0099] The conversion of hydrocarbonaceous feeds can take place
in any convenient mode, for example, in fluidized bed, moving bed,
or fixed bed reactors depending on the types of process desired.
The formulation of the catalyst particles will vary depending on
the conversion process and method of operation.
[0100] Other reactions which can be performed using the catalyst
of this invention containing a metal, e.g., a Group VIII metal such
platinum, include hydrogenation-dehydrogenation reactions, denitrogenation
and desulfurization reactions.
[0101] Depending upon the type of reaction which is catalyzed,
the molecular sieve may be predominantly in the hydrogen form, partially
acidic or substantially free of acidity. As used herein, "predominantly
in the hydrogen form" means that, after calcination, at least
80% of the cation sites are occupied by hydrogen ions and/or rare
earth ions.
[0102] The following table indicates typical reaction conditions
which may be employed when using catalysts comprising catalytically
active CIT-6 in the hydrocarbon conversion reactions of this invention.
Preferred conditions are indicated in parentheses.
5 Process Temp., .degree. C. Pressure LHSV Hydrocracking 175-485
0.5-350 bar 0.1-30 Dewaxing 200-475 15-3000 psig 0.1-20 (250-450)
(200-3000) (0.2-10) Aromatics 400-600 atm.-10 bar 0.1-15 formation
(480-550) Cat. cracking 127-885 subatm.-.sup.1 0.5-50 (atm.-5 atm.)
Oligomerization 232-649.sup.2 0.1-50 atm..sup.23 0.2-50.sup.2 10-232.sup.4
-- 0.05-20.sup.5 (27-204).sup.4 -- (0.1-10).sup.5 Paraffins to 100-700
0-1000 psig 0.5-40.sup.5 aromatics Condensation of 260-538 0.5-1000
psig 0.5-50.sup.5 alcohols Xylene 260-593.sup.2 0.5-50 atm..sup.2
0.1-100.sup.5 isomerization (315-566).sup.2 (1-5 atm).sup.2 (0.5-50).sup.5
38-371.sup.4 1-200 atm..sup.4 0.5-50 .sup.1Several hundred atmospheres
.sup.2Gas phase reaction .sup.3Hydrocarbon partial pressure .sup.4Liquid
phase reaction .sup.5WHSV
[0103] Other reaction conditions and parameters are provided below.
[0104] Hydrocracking
[0105] Using a catalyst which comprises catalytically active CIT-6
preferably predominantly in the hydrogen form, and a hydrogenation
promoter, heavy petroleum residual feedstocks, cyclic stocks and
other hydrocracked charge stocks can be hydrocracked using the process
conditions and catalyst components disclosed in the aforementioned
U.S. Pat. No. 4910006 and U.S. Pat. No. 5316753.
[0106] The hydrocracking catalysts contain an effective amount
of at least one hydrogenation component of the type commonly employed
in hydrocracking catalysts. The hydrogenation component is generally
selected from the group of hydrogenation catalysts consisting of
one or more metals of Group VIB and Group VIII, including the salts,
complexes and solutions containing such. The hydrogenation catalyst
is preferably selected from the group of metals, salts and complexes
thereof of the group consisting of at least one of platinum, palladium,
rhodium, iridium, ruthenium and mixtures thereof or the group consisting
of at least one of nickel, molybdenum, cobalt, tungsten, titanium,
chromium and mixtures thereof. Reference to the catalytically active
metal or metals is intended to encompass such metal or metals in
the elemental state or in some form such as an oxide, sulfide, halide,
carboxylate and the like. The hydrogenation catalyst is present
in an effective amount to provide the hydrogenation function of
the hydrocracking catalyst, and preferably in the range of from
0.05 to 25% by weight
[0107] Dewaxing
[0108] Catalytically active CIT-6 preferably predominantly in
the hydrogen form, can be used to dewax hydrocarbonaceous feeds
by selectively removing straight chain paraffins. Typically, the
viscosity index of the dewaxed product is improved (compared to
the waxy feed) when the waxy feed is contacted with catalytically
active CIT-6 under isomerization dewaxing conditions.
[0109] The catalytic dewaxing conditions are dependent in large
measure on the feed used and upon the desired pour point. Hydrogen
is preferably present in the reaction zone during the catalytic
dewaxing process. The hydrogen to feed ratio is typically between
about 500 and about 30000 SCF/bbl (standard cubic feet per barrel),
preferably about 1000 to about 20000 SCF/bbl. Generally, hydrogen
will be separated from the product and recycled to the reaction
zone. Typical feedstocks include light gas oil, heavy gas oils and
reduced crudes boiling above about 350.degree. F.
[0110] A typical dewaxing process is the catalytic dewaxing of
a hydrocarbon oil feedstock boiling above about 350.degree. F. and
containing straight chain and slightly branched chain hydrocarbons
by contacting the hydrocarbon oil feedstock in the presence of added
hydrogen gas at a hydrogen pressure of about 15-3000 psi with a
catalyst comprising catalytically active CIT-6 and at least one
Group VIII metal.
[0111] The catalytically active CIT-6 hydrodewaxing catalyst may
optionally contain a hydrogenation component of the type commonly
employed in dewaxing catalysts. See the aforementioned U.S. Pat.
No. 4910006 and U.S. Pat. No. 5316753 for examples of these
hydrogenation components.
[0112] The hydrogenation component is present in an effective amount
to provide an effective hydrodewaxing and hydroisometization catalyst
preferably in the range of from about 0.05 to 5% by weight. The
catalyst may be run in such a mode to ineeease isodewaxing at the
expense of cracking reactions.
[0113] The feed may be hydrocracked, followed by dewaxing. This
type of two stage process and typical hydrocracking conditions are
described in U.S. Pat. No.4921594 issued May 1 1990 to Miller,
which is incorporated herein by reference in its entirety.
[0114] Catalytically active CIT-6 may also be utilized as a dewaxing
catalyst in the form of a layered catalyst. That is, the catalyst
comprises a first layer comprising catalytically active molecular
sieve CIT-6 and at least one Group VIII metal, and a second layer
comprising an aluminosilicate zeolite which is more shape selective
than catalytically active molecular sieve CIT-6. The use of layered
catalysts is disclosed in U.S. Pat. No. 5149421 issued Sep. 22
1992 to Miller, which is incorporated by reference herein in its
entirety. The layering may also include a bed of catalytically active
CIT-6 layered with a non-zeolitic component designed for either
hydrocracking or hydrofinishing.
[0115] Catalytically active CIT-6 may also be used to dewax raffinates,
including bright stock, under conditions such as those disclosed
in U.S. Pat. No. 4181598 issued Jan. 1 1980 to Gillespie et
al., which is incorporated by reference herein in its entirety.
[0116] It is often desirable to use mild hydrogenation (sometimes
referred to as hydrofinishing) to produce more stable dewaxed products.
The hydrofinishing step can be performed either before or after
the dewaxing step, and preferably after. Hydrofinishing is typically
conducted at temperatures ranging from about 190.degree. C. to about
340.degree. C. at pressures from about 400 psig to about 3000 psig
at space velocities (LHSV) between about 0.1 and 20 and a hydrogen
recycle rate of about 400 to 1500 SCF/bbl. The hydrogenation catalyst
employed must be active enough not only to hydrogenate the olefins,
diolefins and color bodies which may be present, but also to reduce
the aromatic content. Suitable hydrogenation catalyst are disclosed
in U.S. Pat. No. 4921594 issued May 1 1990 to Miller, which
is incorporated by reference herein in its entirety. The hydrofinishing
step is beneficial in preparing an acceptably stable product (e.g.,
a lubricating oil) since dewaxed products prepared from hydrocracked
stocks tend to be unstable to air and light and tend to form sludges
spontaneously and quickly.
[0117] Lube oil may be prepared using catalytically active CIT-6.
For example, a C.sub.20+ lube oil may be made by isomerizing a C.sub.20+
olefin feed over a catalyst comprising catalytically active CIT-6in
the hydrogen form and at least one Group VIII metal. Alternatively,
the lubricating oil may be made by hydrocracking in a hydrocracking
zone a hydrocarbonaceous feedstock to obtain an effluent comprising
a hydrocracked oil, and catalytically dewaxing the effluent at a
temperature of at least about 400.degree. F. and at a pressure of
from about 15 psig to about 3000 psig in the presence of added hydrogen
gas with a catalyst comprising catalytically active CIT-6 in the
hydrogen form and at least one Group VIII metal.
[0118] Aromatics Formation
[0119] Catalytically active CIT-6 can be used to convert light
straight run naphthas and similar mixtures to highly aromatic mixtures.
Thus, normal and slightly branched chained hydrocarbons, preferably
having a boiling range above about 40.degree. C. and less than about
200.degree. C., can be converted to products having a substantial
higher octane aromatics content by contacting the hydrocarbon feed
with a catalyst comprising catalytically active CIT-6. It is also
possible to convert heavier feeds into BTX or naphthalene derivatives
of value using a catalyst comprising catalytically active CIT-6.
[0120] The conversion catalyst preferably contains a Group VIII
metal compound to have sufficient activity for commercial use. By
Group VIII metal compound as used herein is meant the metal itself
or a compound thereof. The Group VIII noble metals and their compounds,
platinum, palladium, and iridium, or combinations thereof can be
used. Rhenium or tin or a mixture thereof may also be used in conjunction
with the Group VIII metal compound and preferably a noble metal
compound. The most preferred metal is platinum. The amount of Group
VIII metal present in the conversion catalyst should be within the
normal range of use in reforming catalysts, from about 0.05 to 2.0
weight percent, preferably 0.2 to 0.8 weight percent.
[0121] It is critical to the selective production of aromatics
in useful quantities that the conversion catalyst be substantially
free of acidity, for example, by neutralizing the molecular sieve
with a basic metal, e.g., alkali metal, compound. Methods for rendering
the catalyst free of acidity are known in the art. See the aforementioned
U.S. Pat. No. 4910006 and U.S. Pat. No. 5316753 for a description
of such methods.
[0122] The preferred alkali metals are sodium, potassium, rubidium
and cesium.
[0123] Catalytic Cracking
[0124] Hydrocarbon cracking stocks can be catalytically cracked
in the absence of hydrogen using catalytically active CIT-6 preferably
predominantly in the hydrogen form.
[0125] When catalytically active CIT-6 is used as a catalytic cracking
catalyst in the absence of hydrogen, the catalyst may be employed
in conjunction with traditional cracking catalysts, e.g., any aluminosilicate
heretofore employed as a component in cracking catalysts. Typically,
these are large pore, crystalline aluminosilicates. Examples of
these traditional cracking catalysts are disclosed in the aforementioned
U.S. Pat. No.4910006 and U.S. Pat. No. 5316753. When a traditional
cracking catalyst (TC) component is employed, the relative weight
ratio of the TC to the catalytically active CIT-6 is generally between
about 1:10 and about 500:1 desirably between about 1:10 and about
200:1 preferably between about 1:2 and about 50:1 and most preferably
is between about 1:1 and about 20:1. The novel molecular sieve and/or
the traditional cracking component may be further ion exchanged
with rare earth ions to modify selectivity.
[0126] The cracking catalysts are typically employed with an inorganic
oxide matrix component. See the aforementioned U.S. Pat. No. 4910006
and U.S. Pat. No. 5316753 for examples of such matrix components.
[0127] Alkylation and Transalkylation
[0128] Catalytically active CIT-6 can be used in a process for
the alkylation or transalkylation of an aromatic hydrocarbon. The
process comprises contacting the aromatic hydrocarbon with a C.sub.2
to C.sub.16 olefin alkylating agent or a polyalkyl aromatic hydrocarbon
transalkylating agent, under at least partial liquid phase conditions,
and in the presence of a catalyst comprising catalytically active
CIT-6.
[0129] Catalytically active CIT-6 can also be used for removing
benzene from gasoline by alkylating the benzene as described above
and removing the alkylated product from the gasoline.
[0130] For high catalytic activity, the catalytically active CIT-6
molecular sieve should be predominantly in its hydrogen ion form.
It is preferred that, after calcination, at least 80% of the cation
sites are occupied by hydrogen ions and/or rare earth ions.
[0131] Examples of suitable aromatic hydrocarbon feedstocks which
may be alkylated or transalkylated by the process of the invention
include aromatic compounds such as benzene, toluene and xylene.
The preferred aromatic hydrocarbon is benzene. There may be occasions
where naphthalene derivatives may be desirable. Mixtures of aromatic
hydrocarbons may also be employed.
[0132] Suitable olefins for the alkylation of the aromatic hydrocarbon
are those containing 2 to 20 preferably 2 to 4 carbon atoms, such
as ethylene, propylene, butene-1 trans-butene-2 and cis-butene-2
or mixtures thereof. There may be instances where pentenes are desirable.
The preferred olefins are ethylene and propylene. Longer chain alpha
olefins may be used as well.
[0133] When transalkylation is desired, the transalkylating agent
is a polyalkyl aromatic hydrocarbon containing two or more alkyl
groups that each may have from 2 to about 4 carbon atoms. For example,
suitable polyalkyl aromatic hydrocarbons include di-, tri- and tetra-alkyl
aromatic hydrocarbons, such as diethybeneene, triethylbenzene, diethylmethylbenzene
(diethyltoluene), di-isopropylbenzene, di-isopropyltoluene, dibutylbenzene,
and the like. Preferred polyalkyl aromatic hydrocarbons are the
dialkyl benzenes. A particularly preferred polyalkyl aromatic hydrocarbon
is di-isopropylbenzene.
[0134] When alkylation is the process conducted, reaction conditions
are as follows. The aromatic hydrocarbon feed should be present
in stoichiometric excess. It is preferred that molar ratio of aromatics
to olefins be greater than four-to-one to prevent rapid catalyst
fouling. The reaction temperature may range from 100.degree. F.
to 600.degree. F., preferably 250.degree. F. to 450.degree. F. The
reaction pressure should be sufficient to maintain at least a partial
liquid phase in order to retard catalyst fouling. This is typically
50 psig to 1000 psig depending on the feedstock and reaction temperature.
Contact time may range from 10 seconds to 10 hours, but is usually
from 5 minutes to an hour. The weight hourly space velocity (WHSV),
in terms of grams (pounds) of aromatic hydrocarbon and olefin per
gram (pound) of catalyst per hour, is generally within the range
of about 0.5 to 50.
[0135] When transalkylation is the process conducted, the molar
ratio of aromatic hydrocarbon will generally range from about 1:1
to 25:1 and preferably from about 2:1 to 20:1. The reaction temperature
may range from about 100.degree. F. to 600.degree. F., but it is
preferably about 250.degree. F. to 450.degree. F. The reaction pressure
should be sufficient to maintain at least a partial liquid phase,
typically in the range of about 50 psig to 1000 psig, preferably
300 psig to 600 psig. The weight hourly space velocity will range
from about 0.1 to 10. U.S. Pat. No. 5082990 issued on Jan. 21
1992 to Hsieh, et al. describes such processes and is incorporated
herein by reference.
[0136] Isomerization of Olefins
[0137] Catalytically active CIT-6 can be used to isomerize olefins.
The feed stream is a hydrocarbon stream containing at least one
C.sub.4-6 olefin, preferably a C.sub.4-6 normal olefin, more preferably
normal butene. Normal butene as used in this specification means
all forms of normal butene, e.g., 1-butene, cis-2-butene, and trans-2-butene.
Typically, hydrocarbons other than normal butene or other C.sub.4-6
normal olefins will be present in the feed stream These other hydrocarbons
may include, e.g., alkanes, other olefins, aromatics, hydrogen,
and inert gases.
[0138] The feed stem typically may be the effluent from a fluid
catalytic cracking unit or a methyl-tert-butyl ether unit. A fluid
catalytic cracking unit effluent typically contains about 40-60
weight percent normal butenes. A methyl-tert-butyl ether unit effluent
typically contains 40-100 weight percent normal butene. The feed
stream-preferably contains at least about 40 weight percent normal
butene, more preferably at least about 65 weight percent normal
butene. The terms iso-olefin and methyl branched iso-olefin may
be used interchangeably in this specification.
[0139] The process is carried out under isomerization conditions.
The hydrocarbon feed is contacted in a vapor phase with a catalyst
comprising the catalytically active CIT-6. The process may be carried
out generally at a temperature from about 625.degree. F. to about
950.degree. F. (329-510.degree. C.), for butenes, preferably from
about 700.degree. F. to about 900.degree. F. (371-482.degree. C.),
and about 350.degree. F. to about 650.degree. F. (177-343.degree.
C.) for pentenes and hexenes. The pressure ranges from subatmospheric
to about 200 psig, preferably from about 15 psig to about 200 psig,
and more preferably from about 1 psig to about 150 psig.
[0140] The liquid hourly space velocity during contacting is generally
from about 0.1 to about 50 hr.sup.-1 based on the hydrocarbon feed,
preferably from about 0.1 to about 20 hr.sup.-1 more preferably
from about 0.2 to about 10 hr.sup.-1most preferably from about
1 to about 5 hr.sup.-1. A hydrogen/hydrocarbon molar ratio is maintained
from about 0 to about 30 or higher. The hydrogen can be added directly
to the feed stream or directly to the isomerization zone. The reaction
is preferably substantially free of water, typically less than about
two weight percent based on the feed. The process can be carried
out in a packed bed reactor, a fixed bed, fluidized bed reactor,
or a moving bed reactor. The bed of the catalyst can move upward
or downward. The mole percent conversion of e.g., normal butene
to iso-butene is at least 10 preferably at least 25 and more preferably
at least 35.
[0141] Conversion of Paraffins to Aromatics
[0142] Catalytically active CIT-6 can be used to convert light
gas C.sub.2-C.sub.6 paraffins to higher molecular weight hydrocarbons
including aromatic compounds. Preferably, the molecular sieve will
contain a catalyst metal or metal oxide wherein said metal is selected
from the group consisting of Groups IB, IIB, VIII and IIIA of the
Periodic Table. Preferably, the metal is gallium, niobium, indium
or zinc in the range of from about 0.05 to 5% by weight.
[0143] Xylene Isomerization
[0144] Catalytically active CIT-6 may also be useful in a process
for isomerizing one or more xylene isomers in a C.sub.8 aromatic
feed to obtain ortho-, meta-, and para-xylene in a ratio approaching
the equilibrium value. In particular, xylene isomerization is used
in conjunction with a separate process to manufacture para-xylene.
For example, a portion of the para-xylene in a mixed C.sub.8 aromatics
stream may be recovered by crystallization and centrifugation. The
mother liquor from the crystallizer is then reacted under xylene
isomerization conditions to restore ortho-, meta- and para-xylenes
to a near equilibrium ratio. At the same time, part of the ethylbenzene
in the mother liquor is converted to xylenes or to products which
are easily separated by filtration. The isomerate is blended with
fresh feed and the combined stream is distilled to remove heavy
and light by-products. The resultant C.sub.8 aromatics stream is
then sent to the crystallizer to repeat the cycle.
[0145] Optionally, isomerization in the vapor phase is conducted
in the presence of 3.0 to 30.0 moles of hydrogen per mole of alkylbenzene
(e.g., ethylbenzene). If hydrogen is used, the catalyst should comprise
about 0.1 to 2.0 wt. % of a hydrogenation/dehydrogenation component
selected from Group VIII (of the Periodic Table) metal component,
especially platinum or nickel. By Group VIII metal component is
meant the metals and their compounds such as oxides and sulfides.
[0146] Optionally, the isomerization feed may contain 10 to 90
wt. % of a diluent such as toluene, trimethylbenzene, naphthenes
or paraffins.
[0147] Oligomerization
[0148] It is expected that catalytically active CIT-6 can also
be used to oligomerize straight and branched chain olefins having
from about 2 to 21 and preferably 2-5 carbon atoms. The oligomers
which are the products of the process are medium to heavy olefins
which are useful for both fuels, i.e., gasoline or a gasoline blending
stock and chemicals.
[0149] The oligomerization process comprises contacting the olefin
feedstock in the gaseous or liquid phase with a catalyst comprising
catalytically active CIT-6.
[0150] The molecular sieve can have the original cations associated
therewith replaced by a wide variety of other cations according
to techniques well known in the art. Typical cations would include
hydrogen, ammonium and metal cations including mixtures of the same.
Of the replacing metallic cations, particular preference is given
to cations of metals such as rare earth metals, manganese, calcium,
as well as metals of Group II of the Periodic Table, e.g., zinc,
and Group VIII of the Periodic Table, e.g., nickel. One of the prime
requisites is that the molecular sieve have a fairly low aromatization
activity, i.e., in which the amount of aromatics produced is not
more than about 20% by weight. This is accomplished by using a molecular
sieve with controlled acid activity [alpha value] of from about
0.1 to about 120 preferably from about 0.1 to about 100 as measured
by its ability to crack n-hexane.
[0151] Alpha values are defined by a standard test known in the
art; e.g., as shown in U.S. Pat. No. 3960978 issued on Jun. 1
1976 to Givens et al. which is incorporated totally herein by reference.
If required, such molecular sieves may be obtained by steaming,
by use in a conversion process or by any other method which may
occur to one skilled in this art.
[0152] Condensation of Alcohols
[0153] Catalytically active CIT-6 can be used to condense lower
aliphatic alcohols having 1 to 10 carbon atoms to a gasoline boiling
point hydrocarbon product comprising mixed aliphatic and aromatic
hydrocarbon. The process disclosed in U.S. Pat. No. 3894107 issued
Jul. 8 1975 to Butter et al., describes the process conditions
used in this process, which patent is incorporated totally herein
by reference.
[0154] The catalyst may be in the hydrogen form or may be base
exchanged or impregnated to contain ammonium or a metal cation complement,
preferably in the range of from about 0.05 to 5% by weight. The
metal cations that may be present include any of the metals of the
Groups I through VIII of the Periodic Table. However, in the case
of Group IA metals, the cation content should in no case be so large
as to effectively inactivate the catalyst, nor should the exchange
be such as to eliminate all acidity. There may be other processes
involving treatment of oxygenated substrates where a basic catalyst
is desired.
[0155] Other Uses for CIT-6
[0156] CIT-6 can also be used as an adsorbent with high selectivities
based on molecular sieve behavior and also based upon preferential
hydrocarbon paclnng within the pores.
[0157] CIT-6 is a hydrophobic material that can be used to remove
some organic compounds from water.
[0158] CIT-6 may also be used for the catalytic reduction of the
oxides of nitrogen in a gas stream. Typically, the gas stream also
contains oxygen, often a stoichiometric excess thereof. Also, the
CIT-6 may contain a metal or metal ions within or on it which are
capable of catalyzing the reduction of the nitrogen oxides. Examples
of such metals or metal ions include copper, cobalt and mixtures
thereof.
[0159] One example of such a process for the catalytic reduction
of oxides of nitrogen in the presence of a molecular sieve is disclosed
in U.S. Pat. No. 4297328 issued Oct. 27 1981 to Ritscher et
al., which is incorporated by reference herein. There, the catalytic
process is the combustion of carbon monoxide and hydrocarbons and
the catalytic reduction of the oxides of nitrogen contained in a
gas stream, such as the exhaust gas from an internal combustion
engine. The molecular sieve used is metal ion-exchanged, doped or
loaded sufficiently so as to provide an effective amount of catalytic
copper metal or copper ions within or on the molecular sieve. In
addition, the process is conducted in an excess of oxidant, e.g.,
oxygen.
[0160] Oxidation
[0161] Titanium-containing CIT-6 may be used as a catalyst in oxidation
reactions.
[0162] The oxidizing agent employed in the oxidation processes
of this invention is a hydrogen peroxide source such as hydrogen
peroxide (H.sub.2O.sub.2) or a hydrogen peroxide precursor (i.e.,
a compound which under the oxidation reaction conditions is capable
of generating or liberating hydrogen peroxide).
[0163] The amount of hydrogen peroxide relative to the amount of
substrate is not critical, but must be sufficient to cause oxidation
of at least some of the substrate. Typically, the molar ratio of
hydrogen peroxide to substrate is from about 100:1 to about 1:100
preferably 10:1 to about 1:10. When the substrate is an olefin containing
more than one carbon-carbon double bond, additional hydrogen peroxide
may be required. Theoretically, one equivalent of hydrogen peroxide
is required to oxidize one equivalent of a mono-unsaturated substrate,
but it may be desirable to employ an excess of one reactant to optimize
selectivity to the epoxide. In particular, the use of a moderate
to large excess (e.g., 50 to 200%) of olefin relative to hydrogen
peroxide may be advantageous for certain substrates.
[0164] If desired, a solvent may additionally be present during
the oxidation reaction in order to dissolve the reactants other
than the Ti-containing CIT-6 to provide better temperature control,
or to favorably influence the oxidation rates and selectivities.
The solvent, if present, may comprise from 1 to 99 weight percent
of the total-oxidation reaction mixture and is preferably selected
such that it is a liquid at the oxidation reaction temperature.
Organic compounds having boiling points at atmospheric pressure
of from about 50.degree. C. to about 150.degree. C. are generally
preferred for use. Excess hydrocarbon may serve as a solvent or
diluent. Illustrative examples of other suitable solvents include,
but are not limited to, ketones (e.g., acetone, methyl ethyl ketone,
acetophenone), ethers (e.g., tetrahydrofuran, butyl ether), nitrites
(e.g., acetonitrile), aliphatic and aromatic hydrocarbons, halogenated
hydrocarbons, and alcohols (e.g., methanol, ethanol, isopropyl alcohol,
t-butyl alcohol, alpha-methyl benzyl alcohol, cyclohexanol). More
than one type of solvent may be utilized. Water may also be employed
as a solvent or diluent.
[0165] The reaction temperature is not critical, but should be
sufficient to accomplish substantial conversion of the substrate
within a reasonably short period of time. It is generally advantageous
to carry out the reaction to achieve as high a hydrogen peroxide
conversion as possible, preferably at least about 50%, more preferably
at least about 90%, most preferably at least about 95%, consistent
with reasonable selectivities. The optimum reaction temperature
will be influenced by catalyst activity, substrate reactivity, reactant
concentrations, and type of solvent employed, among other factors,
but typically will be in a range of from about 0.degree. C. to about
150.degree. C. (more preferably from about 25.degree. C. to about
120.degree. C.). Reaction or residence times from about one minute
to about 48 hours (more desirably from about ten minutes to about
eight hours) will typically be appropriate, depending upon the above-identified
variables. Although subatmospheric pressures can be employed, the
reaction is preferably performed at atmospheric or at elevated pressure
(typically, between one and 100 atmospheres), especially when the
boiling point of the substrate is below the oxidation reaction temperature.
Generally, it is desirable to pressurize the reaction vessel sufficiently
to maintain the reaction components as a liquid phase mixture. Most
(over 50%) of the substrate should preferably be present in the
liquid phase.
[0166] The oxidation process of this invention may be carried out
in a batch, continuous, or semi-continuous manner using any appropriate
type of reaction vessel or apparatus such as a fixed bed, transport
bed, fluidized bed, stirred slurry, or CSTR reactor. The reactants
may be combined all at once or sequentially. For example, the hydrogen
peroxide or hydrogen peroxide precursor may be added incrementally
to the reaction zone. The hydrogen peroxide could also be generated
in situ within the same reactor zone where oxidation is taking place.
[0167] Once the oxidation has been carried out to the desired degree
of conversion, the oxidized product may be separated and recovered
from the reaction mixture using any appropriate technique such as
fractional distillation, extractive distillation, liquid-liquid
extraction, crystallization, or the like.
[0168] Additional details for oxidation reactions are disclosed
in U.S. Pat. No. 5869706 issued Feb. 9; 1999 to Dartt and Davis,
which is incorporated herein by reference in its entirety.
[0169] Vanadium-containing CIT-6 may be used as a catalyst in the
oxidation/dehydrogenation of hydrocarbons. For example, vanadium-containing
CIT-6 may be used to partially (or completely) oxidize hydrocarbons
in the presence of oxygen (air) or hydrogen peroxide. The oxidation
may either be complete, i.e., oxidizing the hydrocarbon to carbon
dioxide, or partial, as in the oxidation of propane to propylene.
The reaction is conducted under conditions that yield the desired
degree of oxidation, and are known in the art.
EXAMPLES
[0170] The following examples demonstrate but do not limit the
present invention.
Example 1-25
Synthesis of Zn-CIT-6
[0171] Zn-CIT-6 reaction mixtures are prepared by the following
method. After the organic and inorganic cations are dissolved in
distilled water, zinc acetate dihydrate is added. Next, silica is
added and the mixture is stirred for two hours.
[0172] The starting mixtures are each charged into Teflon-lined,
stainless autoclaves and heated statically in convection ovens.
The products are collected by vacuum filtration, washed with distilled
water, and dried in air at room temperature. In order to remove
the occluded organic molecules, the product is heated in air to
540.degree. C. within six hours and maintained at this temperature
for six hours. An as-made Zn-CIT-6 is treated with 1 M aqueous ammonium
nitrate solution at 80.degree. C. for ten hours. The treated sample
is recovered by vacuum filtration and washed with distilled water.
This procedure is repeated four times. The final material is dried
in air at room temperature.
[0173] Using the above procedure, the products indicated below
are made from a reaction mixture having the following composition:
bLiOH:cTEAOH:aZn(CH.sub.3COO):2H.sub.2O:SiO2:dH2O
6 Ex- am- ple Temp. No. b c a D (.degree. C.) Days Product 1 0.05
0.55 0.03 30 150 3 CIT-6 2 0.05 0.55 0.03 30 150 5 CIT-6 + VPI-8
3 0.05 0.55 0.03 30 150 7 VPI-8 4 0.2 0.4 0.03 30 150 3 VPI-8 5
0.05 0.55 0.03 30 175 2 Amorph. 6 0.05 0.55 0.03 30 175 3 VPI-8
7 0.05 0.55 0.03 30 135 9 CIT-6 8 0.05 0.55 0.03 30 135 15 CIT-6
9 0.05 0.55 0.03 30 135 18 VPI-8 10 0.05 0.45 0.03 30 150 6 VPI-8
11 0.05 0.55 0.03 30 150 4 CIT-6 12 0.05 0.55 0.03 30 150 6 VPI-8
13 0.05 0.6 0.03 30 150 4 CIT-6 14 0.05 0.6 0.03 30 150 29 VPI-8
+ small amnt. CIT-6 15 0.05 0.65 0.03 30 150 4 CIT-6 16 0.05 0.65
0.03 30 150 17 CIT-6 + small amnt. VPI-8 17 0.05 0.65 0.03 40 150
4 CIT-6 18 0.05.sup.1 0.65 0.03 30 150 14 Amorph. 19 0.05 0.6 0.01
30 150 11 Amorph. + small amnt. MFI 20 0.05 0.6 0.01 30 150 18 MFI
21 0.05 0.55 -- 30 150 5 MTW 22 0.05 0.65 0.05 30 150 4 CIT-6 +
small amnt. VPI-8 23 0.02 0.6 0.03 30 150 17 Amorph. 24 0.1 0.6
0.03 30 150 4 Unknown + CIT-6 25.sup.23 0.05 0.7 0.03 30 150 4
CIT-6 .sup.1NaOH used instead of LiOH. .sup.2Silica source is Cab-O-Sil
M5 fumed silica. All others are HS-30. .sup.3Milky white mixture
heated at 80.degree. C. for three hours to get a clear solution.
[0174] The results above demonstrate that (1) too long a reaction
time can produce VPI-8 instead of Zn-CIT-6 (Ex. 39 12 14 and
17); (2) too high a reaction temperature may not produce Zn-CIT-6
(Ex. 5 and 6); (3) the presence and concentration of lithium is
critical to formation of Zn-CIT (Ex. 4 18 and 22); and the presence
and concentration of zinc is critical to formation of Zn-CIT-6 (Ex.
19 20 and 21).
Example 26
Synthesis of Zincoaluminosilicate CIT-6
[0175] A solution of tetraethylammonium hydroxide (4.10 grams of
a 35 wt. % solution) is added to 3.34 grams of water. To this is
added 0.018 gram of LiOH, 0.098 gram of zinc acetate dihydrate,
and 0.056 gram of Al(NO.sub.3).sub.3.9 H.sub.2O and the resulting
mixture stirred. Three grams of Ludox HS-30 silica is added and
the resulting mixture stirred for two hours. The resulting solution
is charged into a Teflon-lined autoclave, and heated (statically)
at 150.degree. C. for four days. The product was CIT-6 containing
both zinc and aluminum in the crystal framework.
Example 27
Extraction of TEA and Zinc
[0176] The TEA and zinc are extracted from the CIT-6 prepared in
Example 26 by contacting 0.1 gram of the aluminozincosilicate CIT-6
with a solution containing 6 ml acetic acid, 1 ml pyridine and 10
ml water at 135.degree. C. for two days. The TEA and zinc are extracted
from the CIT-6 but the aluminum remains in the crystal framework,
as shown by .sup.27Al NMR.
Example 28
Cyclohexane Adsorption
[0177] The adsorption amount of vapor-phase cyclohexane (99.5%,
EM) for Zn-CIT-6 is measured at 25.degree. C. using a McBaine-Bakr
balance. Prior to the adsorption experiment, calcined samples of
CIT-6 are dehydrated at 350.degree. C. under vacuum for five hours.
The saturation pressure, P.sub.0 of cyclohexane is 97.5 mm Hg.
The adsorption is performed at a cyclohexane pressure of 30 mm Hg.
The amount of adsorbed cyclohexane of the Zn-CIT-6 sample is 0.16
ml/g. This value is slightly smaller than that of aluminosilicate
beta (0.22 ml/g).
Example 29
Extraction of TEA and Zinc
[0178] The TEA and zinc are extracted from Zn CIT-6 by contacting
0. 1 gram of CIT-6 with a solution containing 6 ml acetic acid,
0.1 ml pyridine and 10 ml water at 60.degree. C. for three days.
Example 30
Insertion of Aluminum
[0179] Aluminum is inserted into the product of Example 29 by contacting
the product with an aqueous solution of aluminum nitrate at a 1:2:50
weight ratio of Zn-CIT-6: aluminum nitrate:water at 80.degree. C.
for one day.
Example 31
Insertion of Titanium
[0180] Titanium is inserted into the product of Example 29 by contacting
the product with 1.5 ml 1M TiCl.sub.4 toluene solution and 10 ml
toluene at 80.degree. C. for 12 hours under nitrogen atmosphere.
After treatment, the sample is filtrated, washed with acetone and
dried. UV analysis of the resultant product shows that titanium
is inserted in the product.
Example 32
Preparation of Pd--Zn-CIT-6
[0181] 2.84 grams of Zn-CIT-6 synthesized as in Example 1 is calcined
to 540.degree. C. in a mixture of air and nitrogen, and subsequently
ion-exchanged once with ammonium nitrate at 85.degree. C. for two
hours, recovered and dried to 300.degree. C. Pd acetylacetonate
(0.0286 gms) in toluene (2.25 ml) is admitted into a sealed bottle
in which the heated Zn-CIT-6 has been placed. This provides for
some vacuum at room temperature. The bottle is manually shaken while
the solution is admitted by syringe. The wetted solid is allowed
to stand overnight. Next the material is calcined to 425.degree.
C. in air.
Example 33
Catalytic Activity
[0182] The Pd--Zn-CIT-6 prepared in Example 30 is loaded as 24-40
mesh particles into a stainless steel reactor. 0.50 Gram is packed
into a 3/8 inch stainless steel tube with alundum on both sides
of the zeolite bed. A Lindburg furnace is used to heat the reactor
tube. Helium is introduced into the reactor tube at 10 cc/min. and
at atmospheric pressure. The reactor is heated to about 372.degree.
C., and a 50/50 (w/w) feed of n-hexane and 3-methylpentane is introduced
into the reactor at a rate of 8 .mu.l/min. Feed delivery is made
via a Brownlee pump. Direct sampling into a gas chromatograph begins
after 10 minutes of feed introduction. At 800.degree. F. (427.degree.
C.) and 10 minutes on stream the catalyst gives 47% conversion with
the products being about 1/3 aromatics, 1/3 isomerized C.sub.6 and
a third olefins from dehydrogenation. There is a few percent cracked
product. There is no preference for reaction of either isomer.
Example 34
Synthesis of All-Si CIT-6 From All-silica Mesoporous Material
[0183] MCM-41 is prepared using the following gel composition where
C.sub.16TMA is hexadecyltrimethylammonium:
[0184] SiO.sub.2/0.39 Na.sub.2O/0.26 (C.sub.16TMA).sub.2O/0.14
H.sub.2SO.sub.4/0.51 HBr/62.53 H.sub.2O Th gel is placed in an autoclave
at 120.degree. C. for three days. The resulting MCM-41 crystals
are recovered and calcined at 540.degree. C. for ten hours.
[0185] The calcined MCM-41 (0.1 gram) is impregnated with 0.3 gram
of 35 wt. % TEAOH aqueous solution and dried at room temperature
for one day (TEAOH/Si=0.4 H.sub.2O/Si=.about.2). The resulting
powder is charged into an autoclave and heated at 150.degree. C.
for seven days. The product is all-silica zeolite beta.
[0186] 0.1 Gram of the all-silica zeolite beta (still containing
TEAOH) is treated with a mixture of 6 ml acetic acid and 10 ml water
at 135.degree. C. for two days. Almost all of the TEAOH is removed
from the material, and it retains the beta zeolite structure. The
resulting product is highly hydrophobic.
Example 35
Synthesis of Si-MCM-41
[0187] Si-MCM-41 materials (Si-1-MCM-41) are prepared by adding
2.4 grams of 29 wt. % NH.sub.4OH solution (EM) to 26.4 grams of
29 wt. % hexadecyltrimethylammonium-chloride (C.sub.16TMACI) solution.
This solution is combined with 2.3 grams of tetramethylammonium
hydroxide pentahydrate (TMAOH.5H.sub.2O), 20 grams of tetramethylammonium
silicate (10 wt. % SiO.sub.2 TMA/Si=0.5) and 4.5 grams of fumed
silica (Cab-O-Sil M-5 from Cabot), under stirring. The composition
of the resulting gel is:
SiO.sub.2:0.11(C.sub.16TMA).sub.2O:0.09(NH.sub.4).sub.2O:0.11HCl:19.3H.sub-
.2O.
[0188] The reaction mixture is charged into a Teflon-lined, stainless
steel autoclave and heated statically at 140.degree. C. for three
days. The product is collected by vacuum filtration, washed with
water and dried in air at room temperature. In order to remove occluded
molecules, the as-made sample is calcined in air at 550.degree.
C. within six hours and maintained at this temperature for six hours.
The product is identified as MCM-41 and designated Si-1-MCM-41.
Example 36
Synthesis of Si-MCM-41
[0189] Concentrated H.sub.2SO.sub.4 (1.2 grams) is added dropwise
to 20 grams of sodium silicate (10.8 wt. % Na.sub.2O, 27.0 wt. %
SiO.sub.2 and 62.2 wt. % H.sub.2O) in 42.8 grams of water under
stirring. Next, 16.8 grams of C.sub.16TMABr in 50.3 grams of water
is added to the solution and the resulting mixture is stirred for
two hours. The resulting gel has the composition:
SiO.sub.2:0.26(C.sub.16TMA).sub.2O:0.39Na.sub.2O:0.14H.sub.2SO.sub.4:0.51H-
Br:62.5H.sub.2O.
[0190] The reaction mixture is charged into a Teflon-lined, stainless
steel autoclave and heated statically at 120.degree. C. for three
days. The product is collected by vacuum filtration, washed with
water and dried in air at room temperature and calcined in air at
550.degree. C. within six hours and maintained at this temperature
for six hours to remove the organic molecules. The organic molecules
occluded in the pores of the material are also removed by contacting
the as-made sample with 1M HCl solution in diethyl ether at room
temperature. The product is identified as MCM-41 and designated
Si-2-MCM-41.
Example 37
Synthesis of MCM-48
[0191] NaOH (0.8 gram) is dissolved in 44 grams of water. To this
solution is added 8.89 grams of C.sub.16TMABr and finally 8.33 grams
of TEOS is added to it. The resulting mixture is stirred at room
temperature for two hours. The mixture has the following composition:
SiO.sub.2:0.61C.sub.16TMABr:60H.sub.2O:0.5NaOH:4EtOH.
[0192] The reaction mixture is charged into a Teflon-lined, stainless
steel autoclave and heated statically at 105.degree. C. for three
days. The product is collected by vacuum filtration, washed with
water and dried in air at room temperature and calcined in air at
550.degree. C. within six hours and maintained at this temperature
for six hours to remove the organic molecules. The product is identified
as MCM-48.
Example 38
Synthesis of Al-Containing MCM-41
[0193] 2.4 Grams of 29 wt. % NH.sub.4OH solution is added to 26.4
grams of 29 wt. % C.sub.16TMACl solution. To this, 0.37 gram of
sodium aluminate (54 wt. % Al.sub.2O.sub.3 41 wt. % Na.sub.2O,
5 wt. % H.sub.2O) is added and the solution is combined with 2.3
grams of TMAOH.5H.sub.2O, 20 grams of tetramethylammonium silicate
(10 wt. % SiO.sub.2 TMA/Si=0.5) and 4.5 grams of fumed silica (Cab-O-Sil
M-5) under stirring. The resulting gel composition is:
SiO.sub.2:0.02Al.sub.2O.sub.3:0.02Na.sub.2O:0.11(C.sub.16TMA).sub.2O:0.13(-
TMA).sub.2O:0.09(NH.sub.4).sub.2O:0.22HCl:19.3H.sub.2O.
[0194] The reaction mixture is charged into a Teflon-lined, stainless
steel autoclave and heated statically at 135.degree. C. for three
days. The product is collected by vacuum filtration, washed with
water and dried in air at room temperature. In order to remove the |