Molecular sieve abstract
This invention relates to processes for converting oxygenates to
olefins that include a step of pretreating catalyst, which comprises
molecular sieve and one or more active metal oxides of one or more
metals, with a hydrocarbon composition to provide an integrated
hydrocarbon co-catalyst within the molecular sieve. The combination
of molecular sieve and hydrocarbon co-catalyst converts oxygenate
to an olefin product with high selectivity to light olefins (i.e.,
ethylene or propylene, or mixture thereof).
Molecular sieve claims
1. A process for making an olefin product from an oxygenate feed,
the process comprising the steps of: a) providing a catalyst composition,
wherein the catalyst comprises a metalloaluminophosphate molecular
sieve having a porous framework and an active metal oxide; b) pretreating
the catalyst composition by contacting the catalyst composition
with a hydrocarbon in a pretreatment zone to form an integrated
hydrocarbon co-catalyst within the porous framework of the molecular
sieve; and c) contacting the pretreated catalyst composition with
an oxygenate in an oxygenate conversion zone to convert the oxygenate
to olefin product.
2. The process of claim 1 wherein the active metal oxide is an
active metal oxide of one or more metals selected from the group
consisting of Group 2 metals, Group 3 metals, the Lanthanide series
of metals, the Actinide series of metals, and Group 4 metals of
the Periodic Table.
3. The process of claim 1 wherein the active metal oxide is an
active metal oxide of one or more metals selected from the Group
2 metals.
4. The process of claim 1 wherein the active metal oxide is an
active metal oxide of one or more metals selected from the Group
3 metals, the Lanthanide series of metals, and the Actinide series
of metals.
5. The process of claim 1 wherein the active metal oxide is an
active metal oxide of one or more metals selected from the Group
4 metals.
6. The process of claim 1 wherein the active metal oxide is an
active metal oxide of one of the Group 2 metals and one or more
of the Group 3 metals.
7. The process of claim 1 wherein the active metal oxide is an
active metal oxide of one of the Group 4 metals and one or more
of the Group 2 or 3 metals.
8. The process of claim 1 wherein the active metal oxide has a
carbon dioxide uptake at 100.degree. C. of at least 0.03 mg/m.sup.2
of the active metal oxide composition.
9. The process of claim 8 wherein the active metal oxide has a
carbon dioxide uptake at 100.degree. C. of at least 0.035 mg/m.sup.2
of the active metal oxide composition.
10. The process of claim 1 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of less than 10 mg/m.sup.2
of the active metal oxide.
11. The process of claim 10 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of less than 5 mg/m.sup.2
of the active metal oxide.
12. The process of claim 1 wherein the active metal oxide has
a surface area of at least 10 m.sup.2/g.
13. The process of claim 12 wherein the active metal oxide has
a surface area of at least 15 m.sup.2/g.
14. The process of claim 1 wherein the active metal oxide comprises
at least one active metal oxide selected from the group consisting
of zirconium oxide, magnesium oxide, calcium oxide, barium oxide,
lanthanum oxide, yttrium oxide, scandium oxide and cerium oxide.
15. The process of claim 1 wherein the metalloaluminophosphate
molecular sieve is silicoaluminophosphate molecular sieve.
16. The process of claim 1 wherein the metalloaluminophosphate
molecular sieve is comprised of one or a combination of molecular
sieves selected from the group consisting of SAPO-5 SAPO-8 SAPO-1
SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35 SAPO-36
SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 SAPO-47 SAPO-56 AlPO-5
AlPO-11 AlPO-18 AlPO-31 AlPO-34 AlPO-36 AlPO-37 AlPO-46 and
metal containing molecular sieves thereof.
17. The process of claim 1 wherein the catalyst composition comprises
an alumina binder.
18. The process of claim 1 wherein the catalyst composition comprises
a clay.
19. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone has a kinetic diameter
less than the average pore opening of the molecular sieve.
20. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises an alcohol,
olefin, aldehyde, ketone, ether, or any combination thereof.
21. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises methanol,
ethanol or any combination thereof.
22. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises butene, pentene,
hexene, heptene or any combination thereof.
23. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises acetaldehyde,
propionaldehyde, butyraldehyde or any combination thereof.
24. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises acetone,
butanone, pentanone or any combination thereof.
25. The process of claim 1 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises dimethyl
ether, methyl ethyl ether, diethyl ether, methyl propyl ether, ethyl
propyl ether, dipropyl ether, methyl butyl ether, ethyl butyl ether,
propyl butyl ether, dibutyl ether or any combination thereof.
26. The process of claim 1 wherein the pretreatment zone is at
a temperature higher than that of the oxygenate conversion zone.
27. The process of claim 1 wherein the pretreatment zone is at
a temperature of at least 10.degree. C. higher than that of the
oxygenate conversion zone.
28. The process of claim 1 wherein the pretreatment zone is at
a temperature of at least 20.degree. C. higher than that of the
oxygenate conversion zone.
29. The process of claim 1 wherein the pretreatment zone is at
a temperature of at least 50.degree. C. higher than that of the
oxygenate conversion zone.
30. The process of claim 1 wherein at least one olefin in the
olefin product is contacted with a polyolefin forming catalyst to
form polyolefin.
31. A process for making an olefin product from an oxygenate feed,
the process comprising the steps of: a) providing a catalyst composition,
wherein the composition comprises a metalloaluminophosphate molecular
sieve having a porous framework, a binder, a matrix material, and
an active metal oxide of one or more metals selected from the group
consisting of Group 2 metals, Group 3 metals, the Lanthanide series
of metals, the Actinide series of metals, and Group 4 metals of
the Periodic Table; b) pretreating the catalyst composition by contacting
the catalyst composition with a hydrocarbon in a pretreatment zone
to form an integrated hydrocarbon co-catalyst within the porous
framework of the molecular sieve; and c) contacting the pretreated
catalyst composition with an oxygenate in an oxygenate conversion
zone to convert the oxygenate to olefin product, wherein the pretreatment
zone is at a temperature the same as or higher than that of the
reaction zone.
32. The process of claim 31 wherein the pretreatment zone is at
a temperature higher than that of the reaction zone.
33. The process of claim 32 wherein the pretreatment zone is at
a temperature of at least 10.degree. C. higher than that of the
reaction zone.
34. The process of claim 33 wherein the pretreatment zone is at
a temperature of at least 20.degree. C. higher than that of the
reaction zone.
35. The process of claim 34 wherein the pretreatment zone is at
a temperature of at least 50.degree. C. higher than that of the
reaction zone.
36. The process of claim 31 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the Group
2 metals.
37. The process of claim 31 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the Group
3 metals, the Lanthanide series of metals, and the Actinide series
of metals.
38. The process of claim 31 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the Group
4 metals.
39. The process of claim 31 wherein the active metal oxide is
an active metal oxide of one of the Group 2 metals and one or more
of the Group 3 metals.
40. The process of claim 31 wherein the active metal oxide is
an active metal oxide of one of the Group 4 metals and one or more
of the Group 2 or 3 metals.
41. The process of claim 31 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of at least 0.03 mg/m.sup.2
of the active metal oxide composition.
42. The process of claim 41 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of at least 0.035 mg/m.sup.2
of the active metal oxide composition.
43. The process of claim 31 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of less than 10 mg/m.sup.2
of the active metal oxide.
44. The process of claim 43 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of less than 5 mg/m.sup.2
of the active metal oxide.
45. The process of claim 31 wherein the active metal oxide has
a surface area of at least 10 m.sup.2/g.
46. The process of claim 45 wherein the active metal oxide has
a surface area of at least 15 m.sup.2/g.
47. The process of claim 31 wherein the active metal oxide comprises
at least one active metal oxide selected from the group consisting
of zirconium oxide, magnesium oxide, calcium oxide, barium oxide,
lanthanum oxide, yttrium oxide, scandium oxide and cerium oxide.
48. The process of claim 31 wherein the metalloaluminophosphate
molecular sieve is silicoaluminophosphate molecular sieve.
49. The process of claim 31 wherein the metalloaluminophosphate
molecular sieve is comprised of one or a combination of molecular
sieves selective from the group consisting of SAPO-5 SAPO-8 SAPO-11
SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35 SAPO-36
SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 SAPO-47 SAPO-56 AlPO-5
AlPO-11 AlPO-18 AlPO-31 AlPO-34 AlPO-36 AlPO-37 AlPO-46 and
metal containing molecular sieves thereof.
50. The process of claim 31 wherein the binder comprises an alumina
composition.
51. The process of claim 31 wherein the matrix comprises a clay.
52. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone has a kinetic diameter
less than the average pore opening of the molecular sieve.
53. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises an alcohol,
olefin, aldehyde, ketone, ether or any combination thereof.
54. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises methanol,
ethanol or any combination thereof.
55. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises butene, pentene,
hexene, heptene or any combination thereof.
56. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises acetaldehyde,
propionaldehyde, butyraldehyde or any combination thereof.
57. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises acetone,
butanone, pentanone or any combination thereof.
58. The process of claim 31 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises dimethyl
ether, methyl ethyl ether, diethyl ether, methyl propyl ether, ethyl
propyl ether, dipropyl ether, methyl butyl ether, ethyl butyl ether,
propyl butyl ether, dibutyl ether or any combination thereof.
59. The process of claim 31 wherein at least one olefin in the
olefin product is contacted with a polyolefin forming catalyst to
form polyolefins.
60. A process for making an olefin product and polyolefin from
an oxygenate feed, the process comprising the steps of: a) providing
a catalyst composition, wherein the catalyst comprises a metalloaluminophosphate
molecular sieve having a porous framework and an active metal oxide;
b) pretreating the catalyst composition by contacting the molecular
sieve in the catalyst composition with a hydrocarbon in a pretreatment
zone to form an integrated hydrocarbon co-catalyst within the porous
framework of the molecular sieve; c) contacting the pretreated catalyst
composition with an oxygenate in an oxygenate conversion zone to
convert the oxygenate to olefin product; and d) contacting at least
one olefin in the olefin product with a polyolefin forming catalyst
to form polyolefin.
61. The process of claim 60 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the group
consisting of Group 2 metals, Group 3 metals, the Lanthanide series
of metals, the Actinide series of metals, and Group 4 metals of
the Periodic Table.
62. The process of claim 60 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the Group
2 metals.
63. The process of claim 60 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the Group
3 metals, the Lanthanide series of metals, and the Actinide series
of metals.
64. The process of claim 60 wherein the active metal oxide is
an active metal oxide of one or more metals selected from the Group
4 metals.
65. The process of claim 60 wherein the active metal oxide is
an active metal oxide of one of the Group 2 metals and one or more
of the Group 3 metals.
66. The process of claim 60 wherein the active metal oxide is
an active metal oxide of one of the Group 4 metals and one or more
of the Group 2 or 3 metals.
67. The process of claim 60 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of at least 0.03 mg/m.sup.2
of the active metal oxide composition.
68. The process of claim 67 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of at least 0.035 mg/m.sup.2
of the active metal oxide composition.
69. The process of claim 60 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of less than 10 mg/m.sup.2
of the active metal oxide.
70. The process of claim 69 wherein the active metal oxide has
a carbon dioxide uptake at 100.degree. C. of less than 5 mg/m.sup.2
of the active metal oxide.
71. The process of claim 60 wherein the active metal oxide has
a surface area of at least 10 m.sup.2/g.
72. The process of claim 71 wherein the active metal oxide has
a surface area of at least 15 m.sup.2/g.
73. The process of claim 60 wherein the active metal oxide comprises
at least one active metal oxide selected from the group consisting
of zirconium oxide, magnesium oxide, calcium oxide, barium oxide,
lanthanum oxide, yttrium oxide, scandium oxide and cerium oxide.
74. The process of claim 60 wherein the metalloaluminophosphate
molecular sieve is silicoaluminophosphate molecular sieve.
75. The process of claim 60 wherein the metalloaluminophosphate
molecular sieve is comprised of one or a combination of molecular
sieves selected from the group consisting of SAPO-5 SAPO-8 SAPO-11
SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35 SAPO-36
SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 SAPO-47 SAPO-56 AlPO-5
AlPO-11 AlPO-18 AlPO-31 AlPO-34 AlPO-36 AlPO-37 AlPO-46 and
metal containing molecular sieves thereof.
76. The process of claim 60 wherein the catalyst composition comprises
an alumina binder.
77. The process of claim 60 wherein the catalyst composition comprises
a clay.
78. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone has a kinetic diameter
less than the average pore opening of the molecular sieve.
79. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises an alcohol,
olefin, aldehyde, ketone, ether, or any combination thereof.
80. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises methanol,
ethanol or any combination thereof.
81. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises butene, pentene,
hexene, heptene or any combination thereof.
82. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises acetaldehyde,
propionaldehyde, butyraldehyde or any combination thereof.
83. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises acetone,
butanone, pentanone or any combination thereof.
84. The process of claim 60 wherein the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises dimethyl
ether, methyl ethyl ether, diethyl ether, methyl propyl ether, ethyl
propyl ether, dipropyl ether, methyl butyl ether, ethyl butyl ether,
propyl butyl ether, dibutyl ether or any combination thereof.
85. The process of claim 60 wherein the pretreatment zone is at
a temperature higher than that of the oxygenate conversion zone.
86. The process of claim 60 wherein the pretreatment zone is at
a temperature of at least 10.degree. C. higher than that of the
oxygenate conversion zone.
87. The process of claim 60 wherein the pretreatment zone is at
a temperature of at least 20.degree. C. higher than that of the
oxygenate conversion zone.
88. The process of claim 60 wherein the pretreatment zone is at
a temperature of at least 50.degree. C. higher than that of the
oxygenate conversion zone.
Molecular sieve descriptionFIELD OF THE INVENTION
[0001] This invention relates to processes for converting oxygenates
to olefins. In particular, this invention relates to processes for
converting oxygenates to olefins that include a step of pretreating
catalyst, which comprises molecular sieve and one or more active
metal oxides of one or more metals, with a hydrocarbon composition
to provide an integrated hydrocarbon co-catalyst within the molecular
sieve.
BACKGROUND OF THE INVENTION
[0002] Methanol is used as a feed stock for a variety of chemical
manufacturing processes. One process that is more recently being
developed is the conversion of methanol to olefin products, particularly
products containing the olefins ethylene and propylene. The olefins
produced from the methanol conversion process are of suitable quality
to be used in polymer manufacturing processes. Of a commercial concern
in the methanol conversion process, however, is whether sufficient
quantities of light olefins (i.e., ethylene and propylene) can be
produced. Another concern is whether an appropriate catalyst can
be supplied at sufficient quantities to meet the rigors of commercial
scale processing.
[0003] Conventional molecular sieves used in converting oxygenates
to olefins are zeolites and various metalloaluminophosphates. For
example, U.S. Pat. No. 5367100 describes the use of the zeolite,
ZSM-5 to convert methanol into olefin(s); U.S. Pat. No. 4062905
discusses the conversion of methanol and other oxygenates to ethylene
and propylene using crystalline aluminosilicate zeolites, for example
Zeolite T, ZK5 erionite and chabazite; U.S. Pat. No. 4079095
describes the use of ZSM-34 to convert methanol to hydrocarbon products
such as ethylene and propylene; and U.S. Pat. No. 4310440 describes
producing light olefin(s) from an alcohol using a crystalline aluminophosphate,
often designated AlPO.sub.4.
[0004] Some of the most useful molecular sieves for converting
methanol to olefin(s) are silicoaluminophosphate molecular sieves.
Silicoaluminophosphate (SAPO) molecular sieves contain a three-dimensional
microporous crystalline framework structure of [SiO.sub.4], [AlO.sub.4]
and [PO.sub.4] corner sharing tetrahedral units. SAPO synthesis
is described in U.S. Pat. No. 4440871 which is herein fully incorporated
by reference. SAPO molecular sieves are generally synthesized by
the hydrothermal crystallization of a reaction mixture of silicon-,
aluminum- and phosphorus-sources and at least one templating agent.
Synthesis of a SAPO molecular sieve, its formulation into a SAPO
catalyst, and its use in converting a hydrocarbon feedstock into
olefin(s), particularly where the feedstock is methanol, are disclosed
in U.S. Pat. Nos. 4499327 4677242 4677243 4873390 5095163
5714662 and 6166282 all of which are herein fully incorporated
by reference.
[0005] Typically, molecular sieves are formed into molecular sieve
catalyst compositions (generally referred to as formulated catalysts)
to improve their durability in commercial conversion processes.
These formulated catalyst compositions are conventionally formed
by combining molecular sieve, and one or more matrix materials,
with a binder. The binder acts to hold the matrix material to the
molecular sieve.
[0006] U.S. Pat. No. 4465889 describes a catalyst composition
comprising a silicalite molecular sieve impregnated with a thorium,
zirconium, or titanium active metal oxide for use in converting
methanol, dimethyl ether, or a mixture thereof into a hydrocarbon
product rich in iso-C.sub.4 compounds.
[0007] U.S. Pat. No. 6180828 discusses the use of a modified
molecular sieve to produce methylamines from methanol and ammonia,
where for example, a silicoaluminophosphate molecular sieve is combined
with one or more modifiers, such as a zirconium oxide, a titanium
oxide, an yttrium oxide, montmorillonite or kaolinite.
[0008] U.S. Pat. No. 5417949 relates to a process for converting
noxious nitrogen oxides in an oxygen containing effluent into nitrogen
and water using a molecular sieve and a active metal oxide binder,
where the preferred binder is titania and the molecular sieve is
an aluminosilicate.
[0009] EP-A-312981 discloses a process for cracking vanadium-containing
hydrocarbon feed streams using a catalyst composition comprising
a physical mixture of a zeolite embedded in an inorganic refractory
matrix material and at least one oxide of beryllium, magnesium,
calcium, strontium, barium or lanthanum, preferably magnesium oxide,
on a silica-containing support material.
[0010] Kang and Inui, "Effects of decrease in number of acid
sites located on the external surface of Ni-SAPO-34 crystalline
catalyst by the mechanochemical method," Catalysis Letters
53 pages 171-176 (1998) disclose that the shape selectivity can
be enhanced and the coke formation mitigated in the conversion of
methanol to ethylene over Ni-SAPO-34 by milling the catalyst with
MgO, CaO, BaO or Cs.sub.2O on microspherical non-porous silica,
with BaO being the most preferred.
[0011] International Publication No. WO 98/29370 discloses the
conversion of oxygenates to olefins over a small pore non-zeolitic
molecular sieve containing a metal selected from the group consisting
of a lanthanide, an actinide, scandium, yttrium, a Group 4 metal,
a Group 5 metal or combinations thereof.
[0012] U.S. Pat. No. 4677242 (Kaiser) describes the use of a
silicoaluminophosphate (SAPO) molecular sieve catalyst for converting
various oxygenates, such as methanol, to olefins. According to the
patent, the SAPO catalyst is an extremely efficient catalyst for
the conversion of oxygenates to light olefin products when the feed
is converted in the presence of a diluent. The diluent used has
an average kinetic diameter larger than the pores of the SAPO molecular
sieve. The selected SAPO molecular sieves have pore sizes capable
of absorbing oxygen (average kinetic diameter of about 3.36 angstroms),
but with negligible adsorption of isobutane (average kinetic diameter
of about 5.0 angstroms).
[0013] U.S. Pat. No. 6046372 (Brown et al.) discloses another
method of converting methanol to light olefins. The method incorporates
the use of medium pore zeolite molecular sieves, particularly medium
pore ZSM type zeolites, in converting methanol and/or dimethyl ether
to light olefin. Light olefin production is aided by the use of
an aromatic compound as a co-feed. The aromatic compound has a critical
diameter less than the pore size of the catalyst, and is capable
of alkylation by the methanol and/or dimethyl ether. Ethylene product
selectivity is believed to be derived from the back-cracking of
ethyl-aromatic intermediates. The formation of the ethyl-aromatic
intermediates is believed to be facilitated by a mechanism in which
the aromatic compound effectively acts as a catalyst in the conversion
of two molecules of methanol to one molecule of ethylene.
[0014] U.S. Pat. No. 6051746 (Sun et al.) also describes a method
for increasing light olefin selectivity in the conversion of oxygenates
using a small pore molecular sieve catalyst. The selectivity is
increased by exposing a catalyst to a modifier before or during
the conversion reaction. The modifier is a polynuclear aromatic
having at least three interconnected ring structures, with each
ring structure having at least 5 ring members. It is adsorbed onto
the catalyst prior to or simultaneously with the introduction of
feed.
[0015] U.S. Pat. No. 6137022 (Kuechler et al.) is to a process
for increasing the selectivity of a reaction to convert oxygenates
to olefins. The process involves contacting the oxygenate in a reaction
zone containing 15 volume percent or less of a catalyst comprising
SAPO molecular sieve, and maintaining conversion of the feedstock
between 80% and 99% under conditions effective to convert 100% of
the feedstock when the reaction zone contains at least 33 volume
percent of the molecular sieve material. The process is considered
to be beneficial in maximizing the production of ethylene and/or
propylene, and to minimize the production of undesired products.
[0016] U.S. Pat. No. 6225254 (Janssen et al.) is directed to
a method of maintaining acid catalyst sites of a SAPO molecular
sieve catalyst. According to the patent, catalyst sites are lost
when exposed to a moisture-containing environment. In order to maintain
the catalyst sites, and thereby preserve catalyst activity, template-containing
SAPO molecular sieves are heated in an oxygen depleted environment
under conditions effective to provide an integrated catalyst life
that is greater than that obtained in a non-oxygen depleted environment.
[0017] U.S. Pat. No. 6436869 (Searle et al.) is directed to a
method of obtaining olefin product high in ethylene and/or propylene
content, while reducing the amount of any one or more of C.sub.1-C.sub.4
paraffin by-products, and to reduce the amount of coke deposits
on the catalyst during the reaction. The method is accomplished
by providing a catalyst that comprises SAPO crystals, a binder comprising
AlPO crystals, and nickel, cobalt and/or iron, wherein the catalyst
does not contain significant amounts of amorphous binder, but rather
contains crystalline AlPO.
[0018] U.S. Pat. No. 6437208 (Kuechler et al.) discloses a method
for making olefin product from an oxygenate-containing feedstock.
In the method, a SAPO molecular sieve catalyst is contacted with
the oxygenate-containing feedstock in a reactor at an average catalyst
feedstock exposure index of at least 1.0. The average catalyst feedstock
exposure index is the total weight of oxygenate plus hydrocarbon
fed to the reactor divided by the total weight of fresh and regenerated
SAPO molecular sieve (i.e., excluding binder, inerts, etc., of the
catalyst composition) sent to the reactor, both total weights measured
over the same period of time. The method is shown to be effective
in maintaining a high ethylene and propylene selectivity.
[0019] WO 01/62382 A2 (ExxonMobil Chemical Patents Inc.) discloses
that selectivity to ethylene and propylene can be increased by pretreating
a SAPO molecular sieve to form an integrated hydrocarbon co-catalyst
within the framework of the molecular sieve prior to contacting
with oxygenate feed. Acetone, methanol, propene, butene, pentene
and hexene are given as examples of pretreatment compounds capable
of forming an integrated hydrocarbon co-catalyst. The conditions
for pretreatment include pretreating at a lower temperature relative
to the reaction temperature. A preferred pretreatment vessel is
an auxiliary fluidized bed reactor system associated with the oxygenate
conversion reactor.
[0020] U.S. Patent Application, Publication No. U.S. 2003/0176753
A1 (Levin et al.), discloses a catalyst composition comprising a
molecular sieve and at least one oxide of a metal selected from
Group 3 of the Periodic Table of Elements, the Lanthanide series
of elements and the Actinide series of elements. The metal oxide
has an uptake of carbon dioxide at 100.degree. C. of at least 0.03
and typically at least 0.04 mg/m.sup.2 of the metal oxide. The
catalyst is useful in converting oxygenate compounds into one or
more olefins, preferably ethylene and/or propylene.
[0021] U.S. Patent Application, Publication No. U.S. 2003/0176752
A1 (Levin et al.), discloses another metal oxide catalyst composition
useful in converting oxygenate compounds into one or more olefins,
preferably ethylene and/or propylene. The catalyst composition comprises
a molecular sieve and at least one oxide of a metal selected from
Group 4 of the Periodic Table of Elements. The metal oxide has an
uptake of carbon dioxide at 100.degree. C. of at least 0.03 and
typically at least 0.035 mg/m.sup.2 of the metal oxide.
[0022] U.S. Patent Application, Publication No. U.S. 2003/0176733
A1 (Xu et al.), discloses another type of metal oxide catalyst composition
useful in converting oxygenate compounds into one or more olefins,
preferably ethylene and/or propylene. The catalyst composition comprises
a silicoaluminophosphate molecular sieve and a metal oxide which
has a surface area greater than 20 m.sup.2/g, which has been calcined
at temperature greater than 200.degree. C. When saturated with acetone,
and contacted with acetone for 1 hour at 25.degree. C., the catalyst
converts more than 80% of the acetone. The molecular sieve has an
average pore size of less than 5 angstroms.
[0023] In spite of the recent technological advances in converting
oxygenates to olefins, there remains a need to further increase
the quantity of light olefins in the conversion product. In particular,
there remains a need to increase product selectivity to ethylene
and propylene, and particularly to ethylene. There also remains
a need to reduce the amount of undesirable by-products in converting
the oxygenates to olefins. Additionally, there remains a need to
provide catalysts that have characteristics that enable the catalysts
to endure the various rigors of commercial demands. Catalysts that
have substantially increased catalyst lifetimes are also of value.
SUMMARY OF THE INVENTION
[0024] This invention provides processes for converting oxygenates
to olefins that show enhanced selectivity to ethylene and/or propylene,
as well as substantially increased catalyst lifetimes. The processes
involve providing an oxygenate conversion catalyst that contains,
inter alia, molecular sieve and one or more oxides of one or more
metals, and pretreating the conversion catalyst with a hydrocarbon
composition in a pretreatment zone.
[0025] In one aspect, there is provided a process for making an
olefin product from an oxygenate feed. The process includes a step
of providing a catalyst composition, wherein the catalyst comprises
a metalloaluminophosphate molecular sieve having a porous framework
and an active metal oxide. The catalyst composition is pretreated
by contacting the catalyst composition (i.e., the molecular sieve
in the catalyst composition) with a hydrocarbon in a pretreatment
zone to form an integrated hydrocarbon co-catalyst within the porous
framework of the molecular sieve. The pretreated catalyst composition
is then contacted with an oxygenate in an oxygenate conversion zone
to convert the oxygenate to olefin product.
[0026] The invention further provides a process for making an olefin
product and polyolefin from an oxygenate feed. The process includes
a step of providing a catalyst composition, wherein the catalyst
comprises a metalloaluminophosphate molecular sieve having a porous
framework and an active metal oxide. The catalyst composition is
pretreated by contacting with a hydrocarbon in a pretreatment zone
to form an integrated hydrocarbon co-catalyst within the porous
framework of the molecular sieve. The pretreated catalyst composition
is then contacted with an oxygenate in an oxygenate conversion zone
to convert the oxygenate to olefin product, and at least one olefin
in the olefin product is contacted with a polyolefin forming catalyst
to form polyolefin.
[0027] The active metal oxide used in the catalyst of this invention,
is desirably an active metal oxide of one or more metals selected
from the group consisting of Group 2 Group 3 (including the Lanthanide
series of metals, and the Actinide series of metals) and Group 4
metals of the Periodic Table. In one embodiment, the active metal
oxide is an active metal oxide of one of the Group 2 metals and
one or more of the Group 3 metals. In another embodiment, the active
metal oxide is an active metal oxide of one of the Group 4 metals
and one or more of the Group 2 or 3 metals.
[0028] In one embodiment of the invention, the active metal oxide
has a carbon dioxide uptake at 100.degree. C. of at least 0.03 mg/m.sup.2
of the active metal oxide composition. Preferably, the active metal
oxide has a carbon dioxide uptake at 100.degree. C. of at least
0.035 mg/m.sup.2 of the active metal oxide composition.
[0029] In another embodiment, the active metal oxide has a carbon
dioxide uptake at 100.degree. C. of less than 10 mg/m.sup.2 of the
active metal oxide. Preferably, the active metal oxide has a carbon
dioxide uptake at 100.degree. C. of less than 5 mg/m.sup.2 of the
active metal oxide.
[0030] In another embodiment, the active metal oxide has a surface
area of at least 10 m.sup.2/g. Preferably, the active metal oxide
has a surface area of at least 15 m.sup.2/g.
[0031] In yet another embodiment of the invention, the active metal
oxide comprises at least one active metal oxide selected from the
group consisting of zirconium oxide, magnesium oxide, calcium oxide,
barium oxide, lanthanum oxide, yttrium oxide, scandium oxide and
cerium oxide.
[0032] Desirably, the metalloaluminophosphate molecular sieve is
silicoaluminophosphate molecular sieve. Preferably, the metalloaluminophosphate
molecular sieve is comprised of one or a combination of molecular
sieves selected from the group consisting of SAPO-5 SAPO-8 SAPO-11
SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35 SAPO-36
SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 SAPO-47 SAPO-56 AlPO-5
AlPO-11 AlPO-18 AlPO-31 AlPO-34 AlPO-36 AlPO-37 AlPO-46 and
metal containing molecular sieves thereof.
[0033] Optionally, the catalyst composition comprises an alumina
binder. The catalyst composition also optionally comprises a clay.
[0034] Preferably, the hydrocarbon contacting the molecular sieve
in the pretreatment zone has a kinetic diameter less than the average
pore opening of the molecular sieve. In one embodiment, the hydrocarbon
contacting the molecular sieve in the pretreatment zone comprises
an alcohol, olefin, aldehyde, ketone, ether, or any combination
thereof. In another embodiment, the hydrocarbon contacting the molecular
sieve in the pretreatment zone comprises methanol, ethanol or any
combination thereof. In another, the hydrocarbon contacting the
molecular sieve in the pretreatment zone comprises butene, pentene,
hexene, heptene or any combination thereof. In yet another, the
hydrocarbon contacting the molecular sieve in the pretreatment zone
comprises acetaldehyde, propionaldehyde, butyraldehyde or any combination
thereof. In still another, the hydrocarbon contacting the molecular
sieve in the pretreatment zone comprises acetone, butanone, pentanone
or any combination thereof. In another, the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises dimethyl
ether, methyl ethyl ether, diethyl ether, methyl propyl ether, ethyl
propyl ether, dipropyl ether, methyl butyl ether, ethyl butyl ether,
propyl butyl ether, dibutyl ether or any combination thereof.
[0035] The pretreatment zone can be operated at varying degrees
of temperature. In one embodiment, the pretreatment zone is at a
temperature higher than that of the oxygenate conversion zone. Preferably,
the pretreatment zone is at a temperature of at least 10.degree.
C. higher, more preferably at least 20.degree. C. higher, and most
preferably at least 50.degree. C. higher than that of the oxygenate
conversion zone.
DETAILED DESCRIPTION OF THE INVENTION
I. Pretreatment of Molecular Sieve with Hydrocarbon
[0036] This invention is directed to processes for making olefin
product from an oxygenate feed. The processes include a step of
pretreating a fresh or regenerated molecular sieve catalyst with
a hydrocarbon composition. The hydrocarbon in the composition forms
a hydrocarbon co-catalyst within the pore structure of the molecular
sieve. This combination of molecular sieve and hydrocarbon co-catalyst
converts oxygenate to an olefin product with high selectivity to
light olefins (i.e., ethylene or propylene, or mixture thereof).
[0037] The molecular sieve catalyst of the invention contains a
metalloaluminophosphate molecular sieve that further acts to convert
the oxygenate to an olefin product, with high selectivity to light
olefins. In addition, the catalyst contains one or more active metal
oxides of one or more metals. This active metal oxide composition
substantially increases the lifetime of the catalyst, meaning that
the catalyst can be used for longer periods of time during the reaction
process. The invention, therefore, provides processes for converting
oxygenates to olefins that are very high in selectivity to ethylene
and propylene products, and that operate at relatively long catalyst
lifetimes.
II. Molecular Sieve and Metal Oxide Components
[0038] The catalysts of this invention comprise metalloaluminophosphate
molecular sieve and one or more active metal oxides of one or more
metals. The combination of metalloaluminophosphate molecular sieve
and active metal oxide provides a catalyst that has a longer catalyst
lifetime in oxygenate conversion reactions and produces additional
ethylene and propylene products with lower amounts of undesirable
ethane and propane by-products.
A. Metalloaluminophosphate Molecular Sieves
[0039] Metalloaluminophosphate molecular sieves have a molecular
framework that include [AlO.sub.4] and [PO.sub.4] tetrahedral units,
such as metal containing aluminophosphates (AlPO). In one embodiment,
the metalloaluminophosphate molecular sieves include [AlO.sub.4],
[PO.sub.4] and [SiO.sub.4] tetrahedral units, such as silicoaluminophosphates
(SAPO).
[0040] Various silicon, aluminum, and phosphorus based molecular
sieves and metal-containing derivatives thereof have been described
in detail in numerous publications including for example, U.S. Pat.
No. 4567029 (MeAPO where Me is Mg, Mn, Zn, or Co), U.S. Pat. No.
4440871 (SAPO), European Patent Application EP-A-0 159 624 (ELAPSO
where El is As, Be, B, Cr, Co, Ga, Ge, Fe, Li, Mg, Mn, Ti or Zn),
U.S. Pat. No. 4554143 (FeAPO), U.S. Pat. Nos. 4822478 4683217
4744885 (FeAPSO), EP-A-0 158 975 and U.S. Pat. No. 4935216 (ZnAPSO,
EP-A-0 161 489 (CoAPSO), EP-A-0 158 976 (ELAPO, where EL is Co,
Fe, Mg, Mn, Ti or Zn), U.S. Pat. No. 4310440 (AIP04), EP-A-0 158
350 (SENAPSO), U.S. Pat. No. 4973460 (LiAPSO), U.S. Pat. No. 4789535
(LiAPO), U.S. Pat. No. 4992250 (GeAPSO), U.S. Pat. No. 4888167
(GeAPO), U.S. Pat. No. 5057295 (BAPSO), U.S. Pat. No. 4738837
(CrAPSO), U.S. Pat. Nos. 4759919 and 4851106 (CrAPO), U.S.
Pat. Nos. 4758419 4882038 5434326 and 5478787 (MgAPSO),
U.S. Pat. No. 4554143 (FeAPO), U.S. Pat. No. 4894213 (AsAPSO),
U.S. Pat. No. 4913888 (AsAPO), U.S. Pat. Nos. 4686092 4846956
and 4793833 (MnAPSO), U.S. Pat. Nos. 5345011 and 6156931 (MnAPO),
U.S. Pat. No. No. 4737353 (BeAPSO), U.S. Pat. No. 4940570 (BeAPO),
U.S. Pat. Nos. 4801309 4684617 and 4880520 (TiAPSO), U.S.
Pat. Nos. 4500651 4551236 and 4605492 (TiAPO), U.S. Pat.
Nos. 4824554 4744970 (CoAPSO), U.S. Pat. No. 4735806 (GaAPSO)
EP-A-0 293 937 (QAPSO, where Q is framework oxide unit [QO.sub.2]),
as well as U.S. Pat. Nos. 4567029 4686093 4781814 4793984
4801364 4853197 4917876 4952384 4956164 4956165
4973785 5241093 5493066 and 5675050 all of which are
herein fully incorporated by reference. Other molecular sieves include
those described in R. Szostak, Handbook of Molecular Sieves, Van
Nostrand Reinhold, New York, N.Y. (1992), which is herein fully
incorporated by reference.
[0041] The more preferred molecular sieves are SAPO molecular sieves,
and metal-substituted SAPO molecular sieves. Suitable metal substituents
are alkali metals of Group IA of the Periodic Table of Elements,
an alkaline earth metals of Group IIA of the Periodic Table of Elements,
a rare earth metals of Group IIIB, including the Lanthanides: lanthanum,
cerium, praseodymium, neodymium, samarium, europium, gadolinium,
terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium;
and scandium or yttrium of the Periodic Table of Elements, transition
metals of Groups IVB, VB, VIIB, VIIB, VIIIB, and EB of the Periodic
Table of Elements and mixtures of any of these metal species. In
one embodiment, the metal is selected from the group consisting
of Co, Cr, Cu, Fe, Ga, Ge, Mg, Mn, Ni, Sn, Ti, Zn and Zr, and mixtures
thereof. The metal atoms may be inserted into the framework of a
molecular sieve through a tetrahedral unit, such as [MeO.sub.2],
and carry a net charge depending on the valence state of the metal
substituent. For example, in one embodiment, when the metal substituent
has a valence state of +2 +3 +4 +5 or +6 the net charge of
the tetrahedral unit is between -2 and +2.
[0042] In one embodiment, the metalloaluminophosphate molecular
sieve is represented, on an anhydrous basis, by the formula: mR:(M.sub.xAl.sub.yP.sub.z)O.sub.2
wherein R represents at least one templating agent, preferably an
organic templating agent; m is the number of moles of R per mole
of (M.sub.xAl.sub.yP.sub.z)O.sub.2 and m has a value from 0 to 1
preferably 0 to 0.5 and most preferably from 0 to 0.3; x, y, and
z represent the mole fraction of Al, P and M as tetrahedral oxides,
where M is a metal selected from the group consisting of Group IA,
IIA, IB, IIIB, IVB, VB, VIIB, VIIB, VIIIB and Lanthanide's of the
Periodic Table of Elements. Preferably M is one or more metals selected
from the group consisting of Si, Co, Cr, Cu, Fe, Ga, Ge, Mg, Mn,
Ni, Sn, Ti, Zn and Zr. In an embodiment, m is greater than or equal
to 0.2 and x, y and z are greater than or equal to 0.01. In another
embodiment, m is greater than 0.1 to about 1 x is greater than
0 to about 0.25 y is in the range of from 0.4 to 0.5 and z is
in the range of from 0.25 to 0.5 more preferably m is from 0.15
to 0.7 x is from 0.01 to 0.2 y is from 0.4 to 0.5 and z is from
0.3 to 0.5.
[0043] In one embodiment of the invention, the metalloaluminophosphate
molecular sieves contain silicon and aluminum. Desirably, the metalloaluminophosphate
molecular sieves of this invention contain Si and Al, at a Si/Al
ratio of not greater than about 0.5 preferably not greater than
about 0.3 more preferably not greater than about 0.2 still more
preferably not greater than about 0.15 and most preferably not
greater than about 0.1. In another embodiment, the Si/Al ratio is
sufficiently high to allow for increased catalytic activity of the
molecular sieve. Preferably, the metalloaluminophosphate molecular
sieves contain Si and Al at a ratio of at least about 0.005 more
preferably at least about 0.01 and most preferably at least about
0.02.
[0044] Non-limiting examples of SAPO and AlPO molecular sieves
useful herein include one or a combination of SAPO-5 SAPO-8 SAPO-11
SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35 SAPO-36
SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 SAPO-47 SAPO-56 AlPO-5
AlPO-11 AlPO-18 AlPO-31 AlPO-34 AlPO-36 AlPO-37 AlPO-46 and
metal containing molecular sieves thereof. Of these, particularly
useful molecular sieves are one or a combination of SAPO-18 SAPO-34
SAPO-35 SAPO-44 SAPO-56 AlPO-18 AlPO-34 and metal containing
derivatives thereof, such as one or a combination of SAPO-18 SAPO-34
AlPO-34 AlPO-18 and metal containing derivatives thereof, and
especially one or a combination of SAPO-34 AlPO-18 and metal containing
derivatives thereof.
[0045] In an embodiment, the molecular sieve is an intergrowth
material having two or more distinct crystalline phases within one
molecular sieve composition. In particular, intergrowth molecular
sieves are described in U.S. Patent Application Publication No.
2002-0165089 and International Publication No. WO 98/15496 published
Apr. 16 1998 both of which are herein fully incorporated by reference.
For example, SAPO-18 AlPO-18 and RUW-18 have an AEI framework-type,
and SAPO-34 has a CHA framework-type. Thus, the molecular sieve
used herein may comprise at least one intergrowth phase of AEI and
CHA framework-types, especially where the ratio of CHA framework-type
to AEI framework-type, as determined by the DIFFaX method disclosed
in U.S. Patent Application Publication No. 2002-0165089 is greater
than 1:1.
[0046] Generally, molecular sieves (i.e., molecular sieve crystals)
are synthesized by the hydrothermal crystallization of one or more
of a source of aluminum, a source of phosphorus, a source of silicon,
water and a templating agent, such as a nitrogen containing organic
compound. Typically, a combination of sources of silicon and aluminum,
or silicon, aluminum and phosphorus, water and one or more templating
agents, is placed in a sealed pressure vessel. The vessel is optionally
lined with an inert plastic such as polytetrafluoroethylene, and
heated under a crystallization pressure and temperature, until a
crystalline material is formed, which can then be recovered by filtration,
centrifugation and/or decanting.
[0047] Non-limiting examples of silicon sources include silicates,
fumed silica, for example, Aerosil-200 available from Degussa Inc.,
New York, N.Y., and CAB-O-SIL M-5 organosilicon compounds such
as tetraalkylorthosilicates, for example, tetramethylorthosilicate
(TMOS) and tetraethylorthosilicate (TEOS), colloidal silicas or
aqueous suspensions thereof, for example Ludox-HS-40 sol available
from E.I. du Pont de Nemours, Wilmington, Del., silicic acid or
any combination thereof.
[0048] Non-limiting examples of aluminum sources include aluminum
alkoxides, for example aluminum isopropoxide, aluminum phosphate,
aluminum hydroxide, sodium aluminate, pseudo-boehmite, gibbsite
and aluminum trichloride, or any combination thereof. A convenient
source of aluminum is pseudo-boehmite, particularly when producing
a silicoaluminophosphate molecular sieve.
[0049] Non-limiting examples of phosphorus sources, which may also
include aluminum-containing phosphorus compositions, include phosphoric
acid, organic phosphates such as triethyl phosphate, and crystalline
or amorphous aluminophosphates such as AlPO.sub.4 phosphorus salts,
or combinations thereof. A convenient source of phosphorus is phosphoric
acid, particularly when producing a silicoaluminophosphate.
[0050] In general, templating agents or templates include compounds
that contain elements of Group 15 of the Periodic Table of Elements,
particularly nitrogen, phosphorus, arsenic and antimony. Typical
templates also contain at least one alkyl or aryl group, such as
an alkyl or aryl group having from 1 to 10 carbon atoms, for example
from 1 to 8 carbon atoms. Preferred templates are nitrogen-containing
compounds, such as amines, quaternary ammonium compounds and combinations
thereof. Suitable quaternary ammonium compounds are represented
by the general formula R.sub.4N.sup.+, where each R is hydrogen
or a hydrocarbyl or substituted hydrocarbyl group, preferably an
alkyl group or an aryl group having from 1 to 10 carbon atoms.
[0051] Non-limiting examples of templates include tetraalkyl ammonium
compounds including salts thereof, such as tetramethyl ammonium
compounds, tetraethyl ammonium compounds, tetrapropyl ammonium compounds,
and tetrabutylammonium compounds, cyclohexylamine, morpholine, di-n-propylamine
(DPA), tripropylamine, triethylamine (TEA), triethanolamine, piperidine,
cyclohexylamine, 2-methylpyridine, N,N-dimethylbenzylamine, N,N-diethylethanolamine,
dicyclohexylamine, N,N-dimethylethanolamine, choline, N,N'-dimethylpiperazine,
14-diazabicyclo(222)octane, N',N',N,N-tetramethyl-(16)hexanediamine,
N-methyldiethanolamine, N-methyl-ethanolamine, N-methyl piperidine,
3-methyl-piperidine, N-methylcyclohexylamine, 3-methylpyridine,
4-methyl-pyridine, quinuclidine, N,N'-dimethyl-14-diazabicyclo(222)
octane ion; di-n-butylamine, neopentylamine, di-n-pentylamine, isopropylamine,
t-butylamine, ethylenediamine, pyrrolidine, and 2-imidazolidone.
Preferred templates are selected from the group consisting of tetraethyl
ammonium salts, cyclopentylamine, aminomethyl cyclohexane, piperidine,
triethylamine, cyclohexylamine, tri-ethyl hydroxyethylamine, morpholine,
dipropylamine (DPA), pyridine, isopropylamine, heated degraded forms
thereof, and combinations thereof.
[0052] The pH of the synthesis mixture containing at a minimum
a silicon, aluminum, optionally a phosphorus composition, and a
templating agent, is generally in the range of from 2 to 10 such
as from 4 to 9 for example from 5 to 8.
[0053] Generally, the synthesis mixture described above is sealed
in a vessel and heated, preferably under autogenous pressure, to
a temperature in the range of from about 80.degree. C. to about
250.degree. C., such as from about 100.degree. C. to about 250.degree.
C., for example from about 125.degree. C. to about 225.degree. C.,
such as from about 150.degree. C. to about 180.degree. C.
[0054] In one embodiment, the synthesis of molecular sieve crystalline
particles is aided by seeds from another or the same framework type
molecular sieve.
[0055] The time required to form the crystalline particles is usually
dependent on the temperature and can vary from immediately up to
several weeks. Typically, the crystallization time is from about
30 minutes to around 2 weeks, such as from about 45 minutes to about
240 hours, for example from about 1 hour to about 120 hours. The
hydrothermal crystallization may be carried out with or without
agitation or stirring.
[0056] One method for crystallization involves subjecting an aqueous
reaction mixture containing an excess amount of a templating agent
to crystallization under hydrothermal conditions, establishing an
equilibrium between molecular sieve formation and dissolution, and
then, removing some of the excess templating agent and/or organic
base to inhibit dissolution of the molecular sieve. See, for example,
U.S. Pat. No. 5296208 which is herein fully incorporated by reference.
[0057] Other methods for synthesizing molecular sieves or modifying
molecular sieves are described in U.S. Pat. No. 5879655 (controlling
the ratio of the templating agent to phosphorus), U.S. Pat. No.
6005155 (use of a modifier without a salt), U.S. Pat. No. 5475182
(acid extraction), U.S. Pat. No. 5962762 (treatment with transition
metal), U.S. Pat. Nos. 5925586 and 6153552 (phosphorus modified),
U.S. Pat. No. 5925800 (monolith supported), U.S. Pat. No. 5932512
(fluorine treated), U.S. Pat. No. 6046373 (electromagnetic wave
treated or modified), U.S. Pat. No. 6051746 (polynuclear aromatic
modifier), U.S. Pat. No. 6225254 (heating template), PCT WO 01/36329
published May 25 2001 (surfactant synthesis), PCT WO 01/25151 published
Apr. 12 2001 (staged acid addition), PCT WO 01/60746 published
Aug. 23 2001 (silicon oil), U.S. Patent Application Publication
No. 20020055433 published May 9 2002 (cooling molecular sieve),
U.S. Pat. No. 6448197 (metal impregnation including copper), U.S.
Pat. No. 6521562 (conductive microfilter), and U.S. Patent Application
Publication No. 20020115897 published Aug. 22 2002 (freeze drying
the molecular sieve), which are all herein fully incorporated by
reference.
[0058] Once the crystalline molecular sieve product is formed,
usually in a slurry state, it may be recovered by any standard technique
well known in the art, for example, by centrifugation or filtration.
The recovered crystalline particle product, normally termed the
"wet filter cake", may then be washed, such as with water,
and then dried, such as in air, before being formulated into a catalyst
composition. Alternatively, the wet filter cake may be formulated
into a catalyst composition directly, that is without any drying,
or after only partial drying.
B. Active Metal Oxides
[0059] The catalyst of this invention further comprises at least
one active metal oxide of one or more metals. Active metal oxides
are those metal oxides, typically different from the binder or matrix
materials, that, when used in combination with the metalloaluminophosphate
molecular sieve, provide benefits in catalytic conversion processes.
In particular, active metal oxides are those metal oxides, different
from typical binders and/or matrix materials that, when used in
combination with a molecular sieve in a catalyst composition, are
effective in extending of the useful life of the catalyst composition.
Quantification of the extension in catalyst life is determined by
the Lifetime Enhancement Index (LEI) as defined by the following
equation: LEI = Lifetime .times. .times. of .times. .times. Catalyst
.times. .times. in .times. .times. .times. .times. Combination .times.
.times. with .times. .times. Active .times. .times. Metal .times.
.times. Oxide Lifetime .times. .times. of .times. .times. Catalyst
[0060] where the lifetime of the catalyst or catalyst composition,
in the same process under the same conditions, is the cumulative
amount of feedstock processed per gram of catalyst composition until
the conversion of feedstock by the catalyst composition falls below
some defined level, for example 10%. An inactive metal oxide will
have little to no effect on the lifetime of the catalyst composition,
or will shorten the lifetime of the catalyst composition, and will
therefore have a LEI less than or equal to 1. Thus active metal
oxides of the invention are those metal oxides, different from typical
binders and/or matrix materials, that, when used in combination
with a molecular sieve, provide a molecular sieve catalyst composition
that has a LEI greater than 1. By definition, a molecular sieve
catalyst composition that has not been combined with an active metal
oxide will have a LEI equal to 1.0.
[0061] It is found that, by including an active metal oxide in
combination with a molecular sieve, a catalyst composition can be
produced having an LEI in the range of from greater than 1 to 2000
such as from about 1.5 to about 1000. Typically catalyst compositions
according to the invention exhibit LEI values greater than 1.1
for example in the range of from about 1.2 to 150 and more particularly
greater than 1.3 such as greater than 1.5 such as greater than
1.7 such as greater than 2.
[0062] Preferred active metal oxides are oxides of one or more
metals selected from the group consisting of Group 2 metals, Group
3 metals, Lanthanide and Actinide series metals, and Group 4 metals
of the Periodic Table of the Elements.
[0063] In one embodiment of the invention, the catalyst of the
invention comprises at least one active metal oxide that is an oxide
of one or more metals selected from the Group 2 metals of the Periodic
Table of the Elements. Preferably, the active metal oxide component
of the catalyst comprises at least one active metal oxide that is
an oxide of one or more metals selected from the group consisting
of magnesium, calcium, strontium and barium. More preferably, the
active metal oxide is magnesium oxide, calcium oxide or barium oxide.
[0064] In another embodiment, the catalyst of the invention comprises
at least one active metal oxide that is an oxide of one or more
metals selected from the Group 3 metals of the Periodic Table of
the Elements, including the Lanthanides and Actinides. Preferably,
the active metal oxide component of the catalyst comprises at least
one active metal oxide that is an oxide of one or more metals selected
from the group consisting of scandium, yttrium, lanthanum and cerium.
More preferably, the active metal oxide is scandium oxide, yttrium
oxide, lanthanum oxide or cerium oxide.
[0065] In another embodiment, the catalyst of the invention comprises
at least one active metal oxide that is an oxide of one or more
metals selected from the Group 4 metals of the Periodic Table of
the Elements. Preferably, the active metal oxide component of the
catalyst comprises at least one active metal oxide that is an oxide
of one or more metals selected from the group consisting of zirconium
and hafnium. More preferably, the active metal oxide is zirconium
oxide.
[0066] In a preferred embodiment, the active metal oxide is an
active metal oxide of one of the Group 2 metals and one or more
of the Group 3 metals. In another preferred embodiment, the active
metal oxide is an active metal oxide of one of the Group 4 metals
and one or more of the Group 2 or 3 metals.
[0067] In one embodiment, the active metal oxide when combined
with a molecular sieve in a catalyst composition enhances the lifetime
of the catalyst composition in the conversion of a feedstock comprising
methanol, preferably into one or more olefin(s).
[0068] In particular, the metal oxides useful herein have an uptake
of carbon dioxide at 100.degree. C. of at least 0.03 mg/m.sup.2
of the metal oxide, such as at least 0.035 mg/m.sup.2 of the metal
oxide. Although the upper limit on the carbon dioxide uptake of
the metal oxide is not critical, in general the metal oxides useful
herein will have a carbon dioxide at 100.degree. C. of less than
10 mg/m.sup.2 of the metal oxide, such as less than 5 mg/m.sup.2
of the metal oxide. Typically, the metal oxides useful herein have
a carbon dioxide uptake of 0.04 to 0.2 mg/m.sup.2 of the metal oxide.
[0069] In order to determine the carbon dioxide uptake of a metal
oxide, the following procedure is adopted. A sample of the metal
oxide is dehydrated by heating the sample to about 200.degree. C.
to 500.degree. C. in flowing air until a constant weight, the "dry
weight", is obtained. The temperature of the sample is then
reduced to 100.degree. C. and carbon dioxide is passed over the
sample, either continuously or in pulses, again until constant weight
is obtained. The increase in weight of the sample in terms of mg/mg
of the sample based on the dry weight of the sample is the amount
of adsorbed carbon dioxide.
[0070] Carbon dioxide uptake is preferably measured using a Mettler
TGA/SDTA 851 thermogravimetric analysis system under ambient pressure.
The metal oxide sample is dehydrated in flowing air to about 500.degree.
C. for one hour. The temperature of the sample is then reduced in
flowing helium to 100.degree. C. After the sample has equilibrated
at the desired adsorption temperature in flowing helium, the sample
is subjected to 20 separate pulses (about 12 seconds/pulse) of a
gaseous mixture comprising 10-weight % carbon dioxide with the remainder
being helium. After each pulse of the adsorbing gas the metal oxide
sample is flushed with flowing helium for 3 minutes. The increase
in weight of the sample in terms of mg/mg adsorbent based on the
adsorbent weight after treatment at 500.degree. C. is the amount
of adsorbed carbon dioxide. The surface area of the sample is measured
in accordance with the method of Brunauer, Emmett, and Teller (BET)
published as ASTM D 3663 to provide the carbon dioxide uptake in
terms of mg carbon dioxide/m.sup.2 of the metal oxide.
[0071] In one embodiment, the active metal oxide(s) has a BET surface
area of greater than 10 m.sup.2/g, such as greater than 10 m.sup.2/g
to about 300 m.sup.2/g. In another embodiment, the active metal
oxide(s) has a BET surface area greater than 20 m.sup.2/g, such
as from 20 m.sup.2/g to 250 m.sup.2/g. In yet another embodiment,
the active metal oxide(s) has a BET surface area greater than 25
m.sup.2/g, such as from 25 m.sup.2/g to about 200 m.sup.2/g.
[0072] The active metal oxide(s) used herein can be prepared using
a variety of methods. It is preferable that the active metal oxide
is made from an active metal oxide precursor, such as a metal salt,
such as a halide, nitrate, sulfate or acetate. Other suitable sources
of the metal oxide include compounds that form the metal oxide during
calcination, such as oxychlorides and nitrates. Alkoxides are also
suitable sources of the Group 4 metal oxide, for example zirconium
n-propoxide.
[0073] In one embodiment, the metal oxide is hydrothermally treated
under conditions that include a temperature of at least 80.degree.
C., preferably at least 100.degree. C. The hydrothermal treatment
typically takes place in a sealed vessel at greater than atmospheric
pressure. However, a preferred mode of treatment involves the use
of an open vessel under reflux conditions. Agitation of the hydrated
metal oxide in a liquid medium, for example, by the action of refluxing
liquid and/or stirring, promotes the effective interaction of the
hydrated oxide with the liquid medium. The duration of the contact
of the hydrated oxide with the liquid medium is conveniently at
least 1 hour, such as at least 8 hours. The liquid medium for this
treatment typically has a pH of about 6 or greater, such as 8 or
greater. Non-limiting examples of suitable liquid media include
water, hydroxide solutions (including hydroxides of NH.sub.4.sup.+,
Na.sup.+, K.sup.+, Mg.sup.2+, and Ca.sup.2+), carbonate and bicarbonate
solutions (including carbonates and bicarbonates of NH.sub.4.sup.+,
Na.sup.+, K.sup.+, Mg.sup.2+, and Ca.sup.2+), pyridine and its derivatives,
and alkyl/hydroxylamines.
[0074] In another embodiment, the active metal oxide is prepared,
for example, by subjecting a liquid solution, such as an aqueous
solution, comprising a source of ions of a Group 2 3 or 4 metal
to conditions sufficient to cause precipitation of a hydrated precursor
of the solid oxide material, such as by the addition of a precipitating
reagent to the solution. Conveniently, the precipitation is conducted
at a pH above 7. For example, the precipitating agent may be a base
such as sodium hydroxide or ammonium hydroxide.
[0075] When a mixture of a Group 4 metal oxide with a Group 2 and/or
3 metal oxide is to be prepared, a first liquid solution comprising
a source of ions of a Group 4 metal can be combined with a second
liquid solution comprising a source of ions of a Group 2 and/or
Group 3 metal. This combination of two solutions can take place
under conditions sufficient to cause co-precipitation of the mixed
oxide material as a solid from the liquid medium. Alternatively,
the source of ions of the Group 4 metal and the source of ions of
the Group 2 and/or Group 3 metal may be combined into a single solution.
This solution may then be subjected to conditions sufficient to
cause co-precipitation of a hydrated precursor of the solid mixed
oxide material, such as by the addition of a precipitating reagent
to the solution.
[0076] The temperature at which the liquid medium is maintained
during the precipitation is generally less than about 200.degree.
C., such as in the range of from about 0.degree. C. to about 200.degree.
C. A particular range of temperatures for precipitation is from
about 20.degree. C. to about 100.degree. C. The resulting gel is
preferably then hydrothermally treated at temperatures of at least
80.degree. C., preferably at least 100.degree. C. The hydrothermal
treatment typically takes place in a vessel at atmospheric pressure.
The gel, in one embodiment, is hydrothermally treated for up to
10 days, such as up to 5 days, for example up to 3 days.
[0077] The hydrated precursor to the metal oxide(s) is then recovered,
for example by filtration or centrifugation, and washed and dried.
The resulting material can then be calcined, such as in an oxidizing
atmosphere, at a temperature of at least 400.degree. C., such as
at least 500.degree. C., for example from about 600.degree. C. to
about 900.degree. C., and particularly from about 650.degree. C.
to about 800.degree. C., to form the active metal oxide or active
mixed metal oxide. The calcination time is typically up to 48 hours,
such as for about 0.5 to 24 hours, for example for about 1.0 to
10 hours. In one embodiment, calcination is carried out at about
700.degree. C. for about 1 to about 3 hours.
[0078] In another embodiment, the Group 4 metal oxide and the Group
2 and/or Group 3 metal oxide are made separately and then contacted
together to form the mixed metal oxide that is then contacted with
the molecular sieve. For example, the Group 4 metal oxide can be
contacted with the molecular sieve prior to introducing the Group
2 and/or Group 3 metal oxide or alternatively, the Group 2 and/or
Group 3 metal oxide can be contacted with the molecular sieve prior
to introducing the Group 4 metal oxide.
[0079] Where the catalyst composition comprises a Group 4 metal
oxide and a Group 3 metal oxide, the mole ratio of the Group 4 metal
oxide to the Group 3 metal oxide may be in the range of from 1000:1
to 1:1 such as from about 500:1 to 2:1 such as from about 100:1
to about 3:1 such as from about 75:1 to about 5:1 based on the
total moles of the Group 4 and Group 3 metal oxides. In addition,
the catalyst composition can contain from 1 to 25%, such as from
1 to 20%, such as from 1 to 15%, by weight of Group 3 metal based
on the total weight of the mixed metal oxide, particularly where
the Group 3 metal oxide is a lanthanum or yttrium metal oxide and
the Group 4 metal oxide is a zirconium metal oxide.
[0080] Where the catalyst composition comprises a Group 4 metal
oxide and a Group 2 metal oxide, the mole ratio of the Group 4 metal
oxide to the Group 2 metal oxide may be in the range of from 1000:1
to 1:2 such as from about 500:1 to 2:3 such as from about 100:1
to about 1:1 such as from about 50:1 to about 2:1 based on the
total moles of the Group 4 and Group 2 metal oxides. In addition,
the catalyst composition can contain from 1 to 25%, such as from
1 to 20%, such as from 1 to 15%, by weight of Group 2 metal based
on the total weight of the mixed metal oxide, particularly where
the Group 2 metal oxide is calcium oxide and the Group 4 metal oxide
is a zirconium metal oxide.
[0081] In another embodiment, the active metal oxides are made
from active metal oxide precursors, such as metal salts, preferably
Group 2 or Group 3 metal salt precursors. Other suitable sources
of the Group 2 metal oxide include compounds that form these metal
oxides during calcination, such as oxychlorides and nitrates. A
further suitable source of the Group 2 or Group 3 metal oxides include
salts containing the cation of the Group 2 or Group 3 metals, such
as halides, nitrates, and acetates. Alkoxides are also sources of
the Group 2 or Group 3 metal oxides.
[0082] TP one method, the active metal oxide is prepared by the
thermal decomposition of metal-containing compounds, such as magnesium
oxalate and barium oxalate, at high temperatures, such as 600.degree.
C., in flowing air. Thus prepared metal oxides usually have low
BET surface area, e.g., less than 30 m.sup.2/g.
[0083] In another method, the active metal oxide is prepared by
the hydrolysis of metal-containing compounds followed by dehydration
and calcination. For example, MgO is hydroxylated by mixing the
oxide with deionized water, forming a white slurry. The slurry is
slowly heated to dryness on a heating plate to form white powder.
The white powder is further dried in a vacuum oven at 100.degree.
C. for at least 4 hrs, such as for 12 hrs. The dried white powder
is then calcined in air at a temperature of at least 400.degree.
C., such as at least 500.degree. C., and typically at least 550.degree.
C. Thus-prepared active metal oxides generally have higher BET surface
area (between 30 to 300 m.sup.2/g) than that prepared by thermal
decomposition of the active metal oxide precursors.
[0084] In yet another method, the active metal oxide is prepared
by the so-called aerogel method (Koper, O. B., Lagadic, I., Volodin,
A. and Klabunde, K. J., Chem. Mater., 1997 9 2468-2480). In this
method, Mg powder is reacted under nitrogen purge with anhydrous
methanol, to form Mg(OCH.sub.3).sub.2 solution in methanol. The
resultant Mg(OCH.sub.3).sub.2 solution is added to toluene. Water
is then added dropwise to the Mg(OH).sub.2 solution in methanol-toluene
under vigorous stirring. The resultant colloidial suspension of
Mg(OH).sub.2 is placed in an autoclave, pressurized to 100 psig
(690 kpag) with dry nitrogen, and heated slowly to a final pressure
of about 1000 psig (6895 kpag). The supercritical solvent is vented
to produce a fine white powder of Mg(OH).sub.2. Nanocrystalline
MgO is obtained by heating the fine white powder at 400.degree.
C. under vacuum. Such prepared active metal oxides have the highest
BET surface area, generally greater than 300 m.sup.2/g.
[0085] Various methods exist for making mixed metal oxides from
Group 2 and Group 3 metal oxide precursors, e.g., wet impregnation,
incipient wetness and co-precipitation.
[0086] In one embodiment, mixed metal oxides are prepared by impregnating
a Group 3 metal oxide precursor onto a Group 2 metal oxide. In a
typical preparation, a Group 3 metal oxide precursor such as La(acetylacetonate).sub.3
is dissolved in an organic solvent such as toluene. The amount of
solvent used is enough to fill the mesoporous and macroporous volume
of the Group 2 metal oxide. The Group 3 metal oxide precursor solution
is added dropwise to the Group 2 metal oxide. The wet mixture is
dried in a vacuum oven for 1 to 12 hours to remove the solvent.
The resulting solid mixture is then calcined at a temperature, e.g.,
400.degree. C., high enough to decompose the Group 3 metal oxide
precursor into an oxide.
[0087] In another embodiment, a mixed oxide is prepared by the
incipient wetness technique. Typically, a Group 3 metal oxide precursor
such as lanthanum acetate is dissolved in deionized water. The solution
is added dropwise to a Group 2 metal oxide. The mixture is dried
in a vacuum oven at 50.degree. C. for 1 to 12 hours. The dried mixture
is broken up and calcined at 550.degree. C. in air for 3 hours.
[0088] In yet another embodiment, a mixed metal oxide is prepared
by co-precipitation. An aqueous solution comprising Group 2 and
Group 3 metal oxide precursors is subject to conditions sufficient
to cause precipitation of a hydrated precursor of the solid oxide
materials, such as by the addition of sodium hydroxide or ammonium
hydroxide. The temperature at which the liquid medium is maintained
during the co-precipitation is typically from about 20.degree. C.
to about 100.degree. C. The resulting gel is then hydrothermally
treated at temperatures between 50 and 100.degree. C. for several
days. The hydrothermal treatment typically takes place at greater
than atmospheric pressure.
[0089] The resulting material is then recovered, for example by
filtration or centrifugation, and washed and dried. The resulting
material is then calcined at a temperature of greater than 200.degree.
C., preferably greater than 300.degree. C., and more preferably
greater 400.degree. C., and most preferably greater than 450.degree.
C.
[0090] In yet another embodiment, it is preferred to utilize two
or more active metal oxides, preferably one Group 4 metal oxide
and one Group 2 or Group 3 metal oxide. The active metal oxides
useful in the invention are combinable in many ways to form the
mixed metal oxides. In an embodiment, the metal oxides are mixed
together in a slurry or hydrated state or in a substantially dry
or dried state, preferably the metal oxides are contacted in a hydrated
state.
III. Catalyst Composition
[0091] The catalyst composition of the invention includes any one
of the molecular sieves previously described and one or more of
the active metal oxides described above, optionally with a binder
and/or matrix material different from the active metal oxide(s).
Typically, the weight ratio of the molecular sieve to the active
metal oxide(s) in the catalyst composition is in the range of from
5 weight percent to 800 weight percent, such as from 10 weight percent
to 600 weight percent, particularly from 20 weight percent to 500
weight percent, and more particularly from 30 weight percent to
400 weight percent.
[0092] There are many different binders that are useful in forming
catalyst compositions. Non-limiting examples of binders that are
useful alone or in combination include various types of hydrated
alumina, silicas, and/or other inorganic oxide sols. One preferred
alumina containing sol is aluminum chlorhydrol. The inorganic oxide
sol acts like glue binding the synthesized molecular sieves and
other materials such as the matrix together, particularly after
thermal treatment. Upon heating, the inorganic oxide sol, preferably
having a low viscosity, is converted into an inorganic oxide binder
component. For example, an alumina sol will convert to an aluminum
oxide binder following heat treatment.
[0093] Aluminum chlorhydrol, a hydroxylated aluminum based sol
containing a chloride counter ion, has the general formula of Al.sub.mO.sub.n(OH).sub.oCl.sub.p.x(H.sub.2O)
wherein m is 1 to 20 n is 1 to 8 o is 5 to 40 p is 2 to 15 and
x is 0 to 30. In one embodiment, the binder is Al.sub.13O.sub.4(OH).sub.24Cl.sub.7.12(H.sub.2O)
as is described in G. M. Wolterman, et al., Stud. Surf. Sci. and
Catal., 76 pages 105-144 (1993), which is herein incorporated by
reference. In another embodiment, one or more binders are combined
with one or more other non-limiting examples of alumina materials
such as aluminum oxyhydroxide, .gamma.-alumina, boehmite, diaspore,
and transitional aluminas such as .alpha.-alumina, .beta.-alumina,
.gamma.-alumina, .delta.-alumina, .epsilon.-alumina, .kappa.-alumina,
and .rho.-alumina, aluminum trihydroxide, such as gibbsite, bayerite,
nordstrandite, doyelite, and mixtures thereof.
[0094] In another embodiment, the binder is an alumina sol, predominantly
comprising aluminum oxide, optionally including some silicon. In
yet another embodiment, the binder is peptized alumina made by treating
an alumina hydrate, such as pseudobohemite, with an acid, preferably
an acid that does not contain a halogen, to prepare a sol or aluminum
ion solution. Non-limiting examples of commercially available colloidal
alumina sols include Nalco 8676 available from Nalco Chemical Co.,
Naperville, Ill., and Nyacol AL20DW available from Nyacol Nano Technologies,
Inc., Ashland, Mass.
[0095] Where the catalyst composition contains a matrix material,
this is preferably different from the active metal oxide and any
binder. Matrix materials are typically effective in reducing overall
catalyst cost, acting as thermal sinks to assist in shielding heat
from the catalyst composition for example during regeneration, densifying
the catalyst composition, and increasing catalyst strength such
as crush strength and attrition resistance.
[0096] Non-limiting examples of matrix materials include one or
more non-active metal oxides including beryllia, quartz, silica
or sols, and mixtures thereof, for example silica-magnesia, silica-zirconia,
silica-titania, silica-alumina and silica-alumina-thoria. In an
embodiment, matrix materials are natural clays such as those from
the families of montmorillonite and kaolin. These natural clays
include subbentonites and those kaolins known as, for example, Dixie,
McNamee, Georgia and Florida clays. Non-limiting examples of other
matrix materials include haloysite, kaolinite, dickite, nacrite,
or anauxite. The matrix material, such as a clay, may be subjected
to well known modification processes such as calcination and/or
acid treatment and/or chemical treatment.
[0097] In a preferred embodiment, the matrix material is a clay
or a clay-type composition, particularly a clay or clay-type composition
having a low iron or titania content, and most preferably the matrix
material is kaolin. Kaolin has been found to form a pumpable, high
solids content slurry, to have a low fresh surface area, and to
pack together easily due to its platelet structure. A preferred
average particle size of the matrix material, most preferably kaolin,
is from about 0.1 .mu.m to about 0.6 .mu.m with a D.sub.90 particle
size distribution of less than about 1 .mu.m.
[0098] Where the catalyst composition contains a binder or matrix
material, the catalyst composition typically contains from about
1% to about 80%, such as from about 5% to about 60%, and particularly
from about 5% to about 50%, by weight of the molecular sieve based
on the total weight of the catalyst composition.
[0099] Where the catalyst composition contains a binder and a matrix
material, the weight ratio of the binder to the matrix material
is typically from 1:15 to 1:5 such as from 1:10 to 1:4 and particularly
from 1:6 to 1:5. The amount of binder is typically from about 2%
by weight to about 30% by weight, such as from about 5% by weight
to about 20% by weight, and particularly from about 7% by weight
to about 15% by weight, based on the total weight of the binder,
the molecular sieve and matrix material. It has been found that
a higher sieve content and lower matrix content increases the molecular
sieve catalyst composition performance, whereas a lower sieve content
and higher matrix content improves the attrition resistance of the
composition.
[0100] The catalyst composition typically has a density in the
range of from 0.5 g/cc to 5 g/cc, such as from 0.6 g/cc to 5 g/cc,
for example from 0.7 g/cc to 4 g/cc, particularly in the range of
from 0.8 g/cc to 3 g/cc.
IV. Method of Making the Catalyst Composition
[0101] In making the catalyst composition, the molecular sieve
is first formed and is then physically mixed with the active metal
oxide, preferably in a substantially dry, dried, or calcined state.
Most preferably the molecular sieve and active metal oxides are
physically mixed in their calcined state. Mixing can be achieved
by any method known in the art, such as mixing with a mixer muller,
drum mixer, ribbon/paddle blender, kneader, or the like.
[0102] Where the catalyst composition contains a matrix and/or
binder, the molecular sieve is conveniently initially formulated
into a catalyst precursor with the matrix and/or binder and the
active metal oxide is then combined with the formulated precursor.
The active metal oxide can be added as unsupported particles or
can be added in combination with a support, such as a binder or
matrix material. The resultant catalyst composition can then be
formed into useful shaped and sized particles by conventional techniques
such as spray drying, pelletizing, extrusion, and the like.
[0103] In one embodiment, the molecular sieve composition and the
matrix material, optionally with a binder, are combined with a liquid
to form a slurry and then mixed, preferably rigorously mixed, to
produce a substantially homogeneous mixture containing the molecular
sieve composition. Non-limiting examples of suitable liquids include
one or a combination of water, alcohol, ketones, aldehydes, and/or
esters. The most preferred liquid is water. In one embodiment, the
slurry is colloid-milled for a period of time sufficient to produce
the desired slurry texture, sub-particle size, and/or sub-particle
size distribution.
[0104] The molecular sieve composition and matrix material, and
the optional binder, can be combined in the same or different liquids,
and can be combined in any order, together, simultaneously, sequentially,
or a combination thereof. In the preferred embodiment, the same
liquid, preferably water is used. The molecular sieve composition,
matrix material, and optional binder, are combined in a liquid as
solids, substantially dry or in a dried form, or as slurries, together
or separately. If solids are added together as dry or substantially
dried solids, it is preferable to add a limited and/or controlled
amount of liquid.
[0105] In one embodiment, the slurry of the molecular sieve composition,
binder and matrix materials are mixed or milled to achieve a sufficiently
uniform slurry of sub-particles of the molecular sieve catalyst
composition that is then fed to a forming unit that produces the
molecular sieve catalyst composition. In a preferred embodiment,
the forming unit is spray dryer. Typically, the forming unit is
maintained at a temperature sufficient to remove most of the liquid
from the slurry, and from the resulting molecular sieve catalyst
composition. The resulting catalyst composition when formed in this
way takes the form of microspheres.
[0106] When a spray drier is used as the forming unit, typically,
the slurry of the molecular sieve composition and matrix material,
and optionally a binder, is co-fed to the spray drying volume with
a drying gas with an average inlet temperature ranging from 200.degree.
C. to 550.degree. C., and a combined outlet temperature ranging
from 100.degree. C. to about 225.degree. C. In an embodiment, the
average diameter of the spray dried formed catalyst composition
is from about 40 .mu.m to about 300 .mu.m, such as from about 50
.mu.m to about 250 .mu.m, for example from about 50 .mu.m to about
200 .mu.m, and conveniently from about 65 .mu.m to 90 .mu.m.
[0107] Other methods for forming a molecular sieve catalyst composition
are described in U.S. Pat. No. 6509290 (Vaughn et al., spray drying
using a recycled molecular sieve catalyst composition), which is
incorporated herein by reference.
[0108] Once the molecular sieve catalyst composition is formed
in a substantially dry or dried state, to further harden and/or
activate the formed catalyst composition, a heat treatment such
as calcination, at an elevated temperature is usually performed.
Typical calcination temperatures are in the range from about 400.degree.
C. to about 1000.degree. C., such as from about 500.degree. C.
to about 800.degree. C., such as from about 550.degree. C. to about
700.degree. C. Typical calcination environments are air (which may
include a small amount of water vapor), nitrogen, helium, flue gas
(combustion product lean in oxygen), or any combination thereof.
[0109] In a preferred embodiment, the catalyst composition is heated
in nitrogen at a temperature of from about 600.degree. C. to about
700.degree. C. Heating is carried out for a period of time typically
from 30 minutes to 15 hours, such as from 1 hour to about 10 hours,
for example from about 1 hour to about 5 hours, and particularly
from about 2 hours to about 4 hours.
V Hydrocarbon Pretreatment Composition
[0110] The hydrocarbon that is used to pretreat the molecular sieve
composition is one that can be adsorbed into the porous framework
of the structure of the molecular sieve. Preferably, the hydrocarbon
has a kinetic diameter less than the average pore opening of the
molecular sieve.
[0111] The hydrocarbon is contacted with the molecular sieve so
as to form an integrated hydrocarbon co-catalyst within the pore
structure of the molecular sieve. The integrated hydrocarbon co-catalyst
is preferably a single ring aromatic compound. More preferably,
the integrated hydrocarbon co-catalyst is a benzene-based compound.
Still more preferably, the integrated hydrocarbon co-catalyst is
identified by Solid State Nuclear Magnetic Resonance (SSNMR) spectra
comprising a peak in the 18 ppm to 40 ppm region and a peak in the
120 ppm to 150 ppm region. Alternatively, the intensity of the peak
in the 18 ppm to 40 ppm region is negligible, with a single peak
near 128 ppm. In one embodiment, the molecular sieve exhibits a
ratio in the intensity of the peak in the 18 ppm to 40 ppm region
to the intensity of the peak in the 120 ppm to 150 ppm region of
not greater than about 1.0. More preferably, the molecular sieve
exhibits a ratio in the intensity of the peak in the 18 ppm to 40
ppm region to the intensity of the peak in the 120 ppm to 150 ppm
region of between about 0.15 and 0.7.
[0112] Enough hydrocarbon is used to pretreat fresh or regenerated
molecular sieve to form the active co-catalyst. The hydrocarbon
pretreatment composition provides a substantial increase in the
amount of ethylene and propylene produced in the oxygenate to olefin
reaction process. Typically, an effective amount of hydrocarbon
as a pretreatment agent will result in an increase of at least 2
wt % ethylene and propylene in the olefin product. Preferably, the
amount of hydrocarbon applied as a pretreatment agent will result
in an increase of at least 3 wt % ethylene and propylene in the
olefin product, more preferably at least 4 wt % ethylene and propylene
in the olefin product.
[0113] In one embodiment, the hydrocarbon contacting the molecular
sieve in the pretreatment zone comprises one or more oxygenated
hydrocarbons or olefins having a kinetic diameter less than the
average pore opening of the molecular sieve. Preferably, the hydrocarbon
contacting the molecular sieve in the pretreatment zone comprises
an alcohol, olefin, aldehyde, ketone, ether or any combination thereof.
[0114] In a particular embodiment, the hydrocarbon contacting the
molecular sieve in the pretreatment zone comprises a C.sub.1-C.sub.4
alcohol. More preferably, the hydrocarbon contacting the molecular
sieve in the pretreatment zone comprises methanol or ethanol.
[0115] In another embodiment, the hydrocarbon contacting the molecular
sieve in the pretreatment zone comprises a C.sub.3-C.sub.7 olefin.
Preferably, the hydrocarbon contacting the molecular sieve in the
pretreatment zone comprises butene, pentene, hexene, or heptene.
[0116] In yet another embodiment, the hydrocarbon contacting the
molecular sieve in the pretreatment zone comprises a C.sub.2-C.sub.6
aldehyde. Preferably, the hydrocarbon contacting the molecular sieve
in the pretreatment zone comprises acetaldehyde, propionaldehyde,
or butyraldehyde.
[0117] In another embodiment, the hydrocarbon contacting the molecular
sieve in the pretreatment zone comprises a C.sub.3-C.sub.6 ketone.
Preferably, the hydrocarbon contacting the molecular sieve in the
pretreatment zone comprises acetone, butanone, or pentanone.
[0118] In still another embodiment, the hydrocarbon contacting
the molecular sieve in the pretreatment zone comprises a C.sub.2-C.sub.8
ether. Preferably, the hydrocarbon contacting the molecular sieve
in the pretreatment zone comprises dimethyl ether, methyl ethyl
ether, diethyl ether, methyl propyl ether, ethyl propyl ether, dipropyl
ether, methyl butyl ether, ethyl butyl ether, propyl butyl ether,
or dibutyl ether.
VI. Pretreatment Conditions
[0119] According to the invention, fresh, regenerated, or a combination
of fresh and regenerated molecular sieve is pretreated with the
pretreatment composition in a pretreatment zone to form an integrated
hydrocarbon co-catalyst within the porous framework of the molecular
sieve. Effective pretreatment of the molecular sieve is obtained
over a wide range of temperatures, pressures and space velocities.
[0120] In general, the temperature in the pretreatment zone is
from about 150.degree. C. to about 850.degree. C. Preferably, the
temperature in the pretreatment zone is from about 200.degree. C.
to about 800.degree. C., more preferably from about 250.degree.
C. to about 750.degree. C.
[0121] The temperature in the pretreatment zone can be lower, higher,
or the same as that in the reaction zone. In a preferred embodiment,
the pretreatment temperature (i.e., the temperature in the pretreatment
zone) is at least about the same as or greater than the oxygenate
reaction temperature (i.e., the temperature in the oxygenate reaction
zone). Preferably, the pretreatment temperature is greater than
the oxygenate reaction temperature. Desirably, the temperature in
the pretreatment zone is at least 10.degree. C. higher than that
in the oxygenate reaction zone. Preferably, the temperature in the
pretreatment zone is at least 25.degree. C., more preferably at
least 50.degree. C., and most preferably at least about 100.degree.
C. higher than that in the reaction zone.
[0122] In one embodiment, the temperature in the pretreatment zone
is at least 450.degree. C. Preferably, the temperature in the pretreatment
zone is at least 500.degree. C., and most preferably at least 550.degree.
C.
[0123] Pretreatment of the molecular sieve is particularly effective
on fresh, activated catalyst, or regenerated catalyst. Such catalyst
is substantially low in total carbon content. As the fresh or regenerated
catalyst contacts the olefin pretreatment composition, the integrated
hydrocarbon co-catalyst forms within the internal pore structure
of the molecular sieve. In one embodiment, the molecular sieve that
contacts the olefin pretreatment composition to form the integrated
hydrocarbon co-catalyst has a total carbon content of not greater
than about 2 wt % prior to contact with the olefin pretreatment
composition. Preferably the molecular sieve catalyst that contacts
the olefin pretreatment composition has a total carbon content of
not greater than about 1.5 wt %, more preferably not greater than
about 1 wt %, and most preferably not greater than about 0.5 wt
%, prior to contact with the olefin pretreatment composition.
[0124] Following pretreatment, the molecular sieve contains the
integrated hydrocarbon co-catalyst, which is a benzene type compound,
within the various cages of the internal pore structure. In addition
to using SSNMR to determine appropriate pretreatment of the molecular
sieve, an additional embodiment involves measuring hydrocarbon content
of the molecular sieve that has contacted the olefin pretreatment
composition. In one embodiment, the molecular sieve containing the
integrated hydrocarbon co-catalyst has a hydrocarbon content of
at least 0.1 wt %, preferably at least 1 wt %, more preferably at
least about 5 wt %, and most preferably at least about 10 wt %,
based on total weight of the molecular sieve, which excludes non-molecular
sieve components such as binder, matrix, etc., which are optionally
present in a catalyst composition.
[0125] The weight hourly space velocity (WHSV), defined as the
total weight of the pretreatment stream per hour, excluding any
diluents, per weight of molecular sieve in the catalyst composition,
typically ranges in the pretreatment zone from about 1 hr.sup.-1
to about 5000 hr.sup.-1 such as from about 2 hr.sup.-1 to about
3000 hr.sup.-1 for example from about 5 hr.sup.-1 to about 1500
hr.sup.-1 and conveniently from about 10 hr.sup.-1 to about 1000
hr.sup.-1. In one embodiment, the WHSV in the pretreatment zone
is greater than 20 hr.sup.-1 and, where feedstock contains methanol
and/or dimethyl ether, is in the range of from about 20 hr.sup.-1
to about 300 hr.sup.-1.
[0126] The pretreatment zone can be contained in a separate pretreatment
zone or within a reactor vessel where the catalytic conversion of
oxygenate to olefin takes place. In one embodiment, a separate pretreatment
vessel is used. In a particular embodiment, the pretreatment vessel
is an auxiliary fluidized bed reactor associated with the oxygenate
conversion reactor and regenerator system. The auxiliary reactor
is capable of continuously receiving catalyst from the regenerator
and subsequently supplying pretreated catalyst to the oxygenate
conversion reactor. Depending on the reactivity of the pre-treatment
hydrocarbons, the fluidized bed pretreatment can be operated, optionally,
as a dense bed system (in bubbling mode, U<1 ft/s, or in turbulent
mode 1<U<3-5 ft/s) or a transport bed system (U>3-5 ft/s).
[0127] In another embodiment, pretreatment is carried out within
the same vessel where the catalytic conversion of oxygenate to olefin
product takes place. Preferably, two separate temperature zones
are maintained to get proper introduction of hydrocarbon and formation
of the integrated hydrocarbon co-catalyst. In one aspect, the molecular
sieve to be pretreated is introduced into one zone along with the
olefin pretreatment composition to form the integrated hydrocarbon
co-catalyst. Then, the pretreated molecular sieve containing the
integrated hydrocarbon co-catalyst is sent to the other zone and
contacted with oxygenate to convert the oxygenate to olefin product.
Operating conditions in the two zones are controlled for pretreatment
and oxygenate reaction conditions. Either zone or both zones optionally
includes heating or cooling equipment such as heat exchangers, steam
coils, and cooling coils. In one embodiment, the pretreatment zone
includes cooling equipment.
VII. Converting Oxygenate to Olefins Using Pretreated Catalysts
[0128] One embodiment of the invention is directed to a process
of converting a feedstock to one or more olefin(s). Typically, the
feedstock contains one or more aliphatic-containing compounds such
that the aliphatic moiety contains from 1 to about 50 carbon atoms,
such as from 1 to 20 carbon atoms, for example from 1 to 10 carbon
atoms, and particularly from 1 to 4 carbon atoms.
[0129] Non-limiting examples of aliphatic-containing compounds
include alcohols such as methanol and ethanol, alkyl mercaptans
such as methyl mercaptan and ethyl mercaptan, alkyl sulfides such
as methyl sulfide, alkylamines such as methylamine, alkyl ethers
such as dimethyl ether, diethyl ether and methylethyl ether, alkyl
halides such as methyl chloride and ethyl chloride, alkyl ketones
such as dimethyl ketone, formaldehydes, and various acids such as
acetic acid.
[0130] In a preferred embodiment of the process of the invention,
the feedstock contains one or more oxygenates, more specifically,
one or more organic compound(s) containing at least one oxygen atom.
In the most preferred embodiment of the process of invention, the
oxygenate in the feedstock is one or more alcohol(s), preferably
aliphatic alcohol(s) where the aliphatic moiety of the alcohol(s)
has from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms,
and most preferably from 1 to 4 carbon atoms. The alcohols useful
as feedstock in the process of the invention include lower straight
and branched chain aliphatic alcohols and their unsaturated counterparts.
[0131] Non-limiting examples of oxygenates include methanol, ethanol,
n-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethyl
ether, diisopropyl ether, formaldehyde, dimethyl carbonate, dimethyl
ketone, acetic acid, and mixtures thereof.
[0132] In the most preferred embodiment, the feedstock is selected
from one or more of methanol, ethanol, dimethyl ether, diethyl ether
or a combination thereof, more preferably methanol and dimethyl
ether, and most preferably methanol.
[0133] The various feedstocks discussed above, particularly a feedstock
containing an oxygenate, more particularly a feedstock containing
an alcohol, is converted primarily into one or more olefin(s). The
olefin(s) produced from the feedstock typically have from 2 to 30
carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2
to 6 carbon atoms, still more preferably 2 to 4 carbons atoms, and
most preferably are ethylene and/or propylene.
[0134] The pretreated catalyst composition of the invention is
particularly useful in the process that is generally referred to
as the gas-to-olefins (GTO) process or, alternatively, the methanol-to-olefins
(MTO) process. In this process, an oxygenated feedstock, most preferably
a methanol-containing feedstock, is contacted with the pretreated
molecular sieve catalyst composition in an oxygenate conversion
zone into one or more olefin products, preferably and predominantly
olefin products comprised of a majority of ethylene and propylene.
[0135] Using the pretreated catalyst composition of the invention
for the conversion of a feedstock, preferably a feedstock containing
one or more oxygenates, the amount of olefin(s) produced based on
the total weight of hydrocarbon produced is greater than 50 weight
percent, typically greater than 60 weight percent, such as greater
than 70 weight percent, and preferably greater than 75 weight percent.
In one embodiment, the amount of ethylene and/or propylene produced
based on the total weight of hydrocarbon product produced is greater
than 65 weight percent, such as greater than 70 weight percent,
for example greater than 75 weight percent, and preferably greater
than 78 weight percent. Typically, the amount ethylene produced
in weight percent based on the total weight of hydrocarbon product
produced, is greater than 30 weight percent, such as greater than
35 weight percent, for example greater than 40 weight percent. In
addition, the amount of propylene produced in weight percent based
on the total weight of hydrocarbon product produced is greater than
20 weight percent, such as greater than 25 weight percent, for example
greater than 30 weight percent, and preferably greater than 35 weight
percent.
[0136] In addition to the oxygenate component, such as methanol,
the feedstock may contains one or more diluent(s), which are generally
non-reactive to the feedstock or molecular sieve catalyst composition
and are typically used to reduce the concentration of the feedstock.
Non-limiting examples of diluents include helium, argon, nitrogen,
carbon monoxide, carbon dioxide, water, essentially non-reactive
paraffins (especially alkanes such as methane, ethane, and propane),
essentially non-reactive aromatic compounds, and mixtures thereof.
The most preferred diluents are water and nitrogen, with water being
particularly preferred.
[0137] The diluent, for example water, may be used either in a
liquid or a vapor form, or a combination thereof. The diluent may
be either added directly to the feedstock entering a reactor or
added directly to the reactor, or added with the molecular sieve
catalyst composition.
[0138] The oxygenate conversion can be conducted over a wide range
of temperatures, such as in the range of from about 200.degree.
C. to about 1000.degree. C., for example from about 250.degree.
C. to about 800.degree. C., including from about 250.degree. C.
to about 750.degree. C., conveniently from about 300.degree. C.
to about 650.degree. C., typically from about 350.degree. C. to
about 600.degree. C. and particularly from about 350.degree. C.
to about 550.degree. C.
[0139] Similarly, the oxygenate conversion can be conducted over
a wide range of pressures including autogenous pressure. Typically
the partial pressure of the feedstock exclusive of any diluent therein
employed in the process is in the range of from about 0.1 kPaa to
about 5 MPaa, such as from about 5 kPaa to about 1 MPaa, and conveniently
from about 20 kPaa to about 500 kPaa.
[0140] The weight hourly space velocity (WHSV), defined as the
total weight of feedstock excluding any diluents per hour per weight
of molecular sieve in the catalyst composition, typically ranges
in the oxygenate conversion zone from about 1 hr.sup.-1 to about
5000 hr.sup.-1 such as from about 2 hr.sup.-1 to about 3000 hr.sup.-1
for example from about 5 hr.sup.-1 to about 1500 hr.sup.-1 and
conveniently from about 10 hr.sup.-1 to about 1000 hr.sup.-1. In
one embodiment, the WHSV in the oxygenate conversion zone is greater
than 20 hr.sup.-1 and, where feedstock contains methanol and/or
dimethyl ether, is in the range of from about 20 hr.sup.-1 to about
300 hr.sup.-1.
[0141] Where the process is conducted in a fluidized bed as the
oxygenate conversion zone, the superficial gas velocity (SGV) of
the feedstock including diluent and reaction products within the
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