Molecular sieve abstract
This invention provides methods of making molecular sieve catalyst
particles, molecular sieve slurries that can be used in such methods,
molecular sieve catalyst compositions and their use in catalytic
hydrocarbon conversion processes. In one of its aspects, the invention
provides a method of making molecular sieve catalyst particles,
the method comprising the steps of: a) providing a solution or suspension
of an aluminum-containing inorganic oxide precursor in a liquid
medium; b) combining the solution or suspension of aluminum-containing
inorganic oxide precursor with a molecular sieve, and optionally
other formulating agents, to form a catalyst formulation slurry;
c) aging the catalyst formulation slurry to generate in said slurry
a percentage, or increase in said slurry the existing percentage,
of aluminum atoms of the aluminum-containing precursor in the form
of oligomers having a sharp .sup.27Al NMR peak at 62-63 ppm; and
d) forming molecular sieve catalyst particles from the catalyst
formulation slurry. The catalyst compositions obtained by the methods
of the present invention have improved attrition resistance, and
are particularly useful in hydrocarbon conversion processes.
Molecular sieve claims
1. A method of making molecular sieve catalyst particles, the method
comprising the steps of: a) providing a solution or suspension of
an aluminum-containing inorganic oxide precursor in a liquid medium;
b) combining the solution or suspension of aluminum-containing inorganic
oxide precursor with a molecular sieve, and optionally other formulating
agents, to form a catalyst formulation slurry; c) aging the catalyst
formulation slurry to generate in said slurry a percentage, or increase
in said slurry the existing percentage, of aluminum atoms of the
aluminum-containing precursor in the form of oligomers having a
sharp .sup.27Al NMR peak at 62-63 ppm; and d) forming molecular
sieve catalyst particles from the catalyst formulation slurry.
2. The method of claim 1 wherein the liquid medium is water.
3. The method of claim 1 wherein aging is carried out at a temperature
and for a period of time such that at least 5 atom % of the aluminum
atoms of the aluminum-containing precursor in the catalyst formulation
slurry is in the form of oligomers having between 10 and 75 aluminum
atoms per molecule.
4. The method of claim 3 wherein aging is carried out at a temperature
and for a period of time such that at least 10 atom % of the aluminum
atoms of the aluminum-containing precursor in the catalyst formulation
slurry is in the form of oligomers having between 10 and 75 aluminum
atoms per molecule.
5. The method of claim 2 wherein at least 6 atom % of the aluminum
atoms of the aluminum-containing precursor in the catalyst formulation
slurry is in the form of oligomers having a sharp .sup.27Al NMR
peak at 62-63 ppm.
6. The method of claim 2 wherein at least 8 atom % of the aluminum
atoms of the aluminum-containing precursor in the catalyst formulation
slurry is in the form of oligomers having a sharp .sup.27Al NMR
peak at 62-63 ppm.
7. The method of claim 2 wherein the inorganic oxide precursor
comprises an aluminum oxide precursor and a zirconium oxide precursor.
8. The method of claim 2 wherein the inorganic oxide precursor
is an aluminum oxide or aluminum-zirconium oxide precursor.
9. The method of claim 2 wherein the inorganic oxide precursor
is selected from the group consisting of aluminum chlorohydrate
and aluminum-zirconium chlorohydrate.
10. The method of claim 2 wherein aging in step c) takes place
by maintaining the catalyst formulation slurry at a temperature
of from 0.degree. C. to 100.degree. C. for a period of at least
2 hours, preferably for a period of at least 4 hours.
11. The method of claim 10 wherein the catalyst formulation slurry
is maintained at a temperature of from 15.degree. C. to 80.degree.
C.
12. The method of claim 11 wherein aging of the catalyst formulation
slurry takes place for a period of at least 5 hours, preferably
at least 8 hours.
13. The method of claim 2 wherein aging of the catalyst formulation
slurry does not take place for more than 24 hours.
14. The method of claim 2 wherein the solution or suspension of
inorganic oxide precursor is not aged.
15. The method of claim 2 wherein the solution or suspension of
inorganic oxide precursor is maintained at a temperature of from
15.degree. C. to 50.degree. C. for a period of not more than 4 hours.
16. The method of claim 1 wherein the catalyst formulation slurry
further contains a matrix material, preferably a clay, more preferably
kaolin clay.
17. The method of claim 1 wherein the molecular sieve is a metalloaluminophosphate
molecular sieve.
18. The method of claim 1 wherein the molecular sieve is a silicoaluminophosphate
molecular sieve.
19. The method of claim 18 wherein the molecular sieve is selected
from SAPO-18 SAPO-34 SAPO-44 intergrown forms thereof, metal-containing
forms thereof, and mixtures thereof.
20. The method of claim 1 wherein at least a portion of the molecular
sieve used in step b) is provided in the form of uncalcined molecular
sieve catalyst particles.
21. The method of claim 2 wherein the catalyst formulation slurry
prepared in step b) has a viscosity of from 1.0 to 10.0 Pa-s, preferably
of from 1.2 to 9.5 Pa-s, when measured at a temperature between
23.degree. C. and 30.degree. C., using a Brookfield LV viscometer,
with a #3 spindle at 10 rpm.
22. The method of claim 1 wherein forming the catalyst particles
is performed by spray drying.
23. The method of claim 1 further comprising the step of calcining
the molecular sieve catalyst particles.
24. A method of making molecular sieve catalyst particles, the
method comprising the steps of: a) preparing a solution or suspension
of inorganic oxide precursor in a liquid medium; b) combining the
solution or suspension of inorganic oxide precursor with a molecular
sieve, and optionally other formulating agents, to form a catalyst
formulation slurry; c) aging the suspension of inorganic oxide;
and d) forming molecular sieve catalyst particles from the catalyst
formulation slurry; wherein said aging is carried out at a temperature
and for a duration such that the catalyst formulation slurry has
a Relative Binding Efficiency between 1.02 and 1.25.
25. The method of claim 24 wherein the liquid medium is water.
26. The method of claim 25 wherein aging is carried out at a temperature
and for a period of time such that the catalyst formulation slurry
has a Relative Binding Efficient between 1.02 and 1.2 preferably
1.18 more preferably 1.15.
27. The method of claim 25 wherein the inorganic oxide precursor
comprises an aluminum oxide precursor and a zirconium oxide precursor.
28. The method of claim 25 wherein the inorganic oxide precursor
is an aluminum oxide or aluminum-zirconium oxide precursor.
29. The method of claim 25 wherein the inorganic oxide precursor
is selected from the group consisting of aluminum chlorohydrate
and aluminum-zirconium chlorohydrate.
30. The method of claim 25 wherein aging in step c) takes place
by maintaining the catalyst formulation slurry at a temperature
of from 0.degree. C. to 100.degree. C. for a period of at least
2 hours, preferably for a period of at least 4 hours.
31. The method of claim 30 wherein the catalyst formulation slurry
is maintained at a temperature of from 15.degree. C. to 80.degree.
C.
32. The method of claim 31 wherein aging of the catalyst formulation
slurry takes place for a period of at least 5 hours, preferably
at least 8 hours.
33. The method of claim 32 wherein aging of the catalyst formulation
slurry does not take place for more than 24 hours.
34. The method of claim 32 wherein the solution or suspension
of inorganic oxide precursor is not aged.
35. The method of claim 32 wherein the solution or suspension
of inorganic oxide precursor is maintained at a temperature of from
15.degree. C. to 50.degree. C. for a period of not more than 4 hours.
36. The method of claim 25 wherein the catalyst formulation slurry
further contains a matrix material, preferably a clay, more preferably
kaolin clay.
37. The method of claim 25 wherein the molecular sieve is a metalloaluminophosphate
molecular sieve.
38. The method of claim 25 wherein the molecular sieve is a silicoaluminophosphate
molecular sieve.
39. The method of claim 38 wherein the molecular sieve is selected
from SAPO-18 SAPO-34 SAPO-44 intergrown forms thereof, metal-containing
forms thereof, and mixtures thereof.
40. The method of claim 25 wherein at least a portion of the molecular
sieve used in step b) is provided in the form of uncalcined molecular
sieve catalyst particles.
41. The method of claim 25 wherein the catalyst formulation slurry
prepared in step b) has a viscosity of from 1.0 to 10.0 Pa-s, preferably
of from 1.2 to 9.5 Pa-s, when measured at a temperature between
23.degree. C. and 30.degree. C., using a Brookfield LV viscometer,
with a #3 spindle at 10 rpm.
42. The method of claim 24 wherein forming the catalyst particles
is performed by spray drying.
43. The method of claim 24 further comprising the step of calcining
the molecular sieve catalyst particles.
44. A method of making molecular sieve catalyst particles, the
method comprising the steps of: a) preparing a solution or suspension
of inorganic oxide precursor in a liquid medium; b) combining the
solution or suspension of inorganic oxide precursor with a molecular
sieve, and optionally other formulating agents, to form a catalyst
formulation slurry; c) aging the catalyst formulation slurry; and
d) forming molecular sieve catalyst particles from the catalyst
formulation slurry; wherein said aging is carried out at a temperature
and for a duration such that the molecular sieve catalyst particles
obtained after step d) have an ARI value of less than 1.0.
45. The method of claim 44 wherein the molecular sieve catalyst
particles obtained after step d) have an ARI of less than 0.5.
46. The method of claim 44 wherein the liquid medium is water.
47. The method of claim 46 wherein the inorganic oxide precursor
comprises an aluminum oxide precursor and a zirconium oxide precursor.
48. The method of claim 46 wherein the inorganic oxide precursor
is an aluminum oxide or aluminum-zirconium oxide precursor.
49. The method of claim 46 wherein the inorganic oxide precursor
is selected from the group consisting of aluminum chlorohydrate
and aluminum-zirconium chlorohydrate.
50. The method of claim 46 wherein aging in step c) takes place
by maintaining the catalyst formulation slurry at a temperature
of from 0.degree. C. to 100.degree. C. for a period of at least
2 hours, preferably for a period of at least 4 hours.
51. The method of claim 50 wherein the catalyst formulation slurry
is maintained at a temperature of from 15.degree. C. to 80.degree.
C.
52. The method of claim 51 wherein aging of the catalyst formulation
slurry takes place for a period of at least 5 hours, preferably
at least 8 hours.
53. The method of claim 46 wherein aging of the catalyst formulation
slurry does not take place for more than 24 hours.
54. The method of claim 46 wherein the solution or suspension
of inorganic oxide precursor is not aged.
55. The method of claim 46 wherein the solution or suspension
of inorganic oxide precursor is maintained at a temperature of from
15.degree. C. to 50.degree. C. for a period of not more than 4 hours.
56. The method of claim 44 wherein the catalyst formulation slurry
further contains a matrix material, preferably a clay, more preferably
kaolin clay.
57. The method of claim 44 wherein the molecular sieve is a metalloaluminophosphate
molecular sieve.
58. The method of claim 44 wherein the molecular sieve is a silicoaluminophosphate
molecular sieve.
59. The method of claim 58 wherein the molecular sieve is selected
from SAPO-18 SAPO-34 SAPO-44 intergrown forms thereof, metal-containing
forms thereof, and mixtures thereof.
60. The method of claim 44 wherein at least a portion of the molecular
sieve used in step b) is provided in the form of uncalcined molecular
sieve catalyst particles.
61. The method of claim 46 wherein the catalyst formulation slurry
prepared in step b) has a viscosity of from 1.0 to 10.0 Pa-s, preferably
of from 1.2 to 9.5 Pa-s, when measured at a temperature between
23.degree. C. and 30.degree. C., using a Brookfield LV viscometer,
with a #3 spindle at 10 rpm.
62. The method of claim 44 wherein forming the catalyst particles
is performed by spray drying.
63. The method of claim 44 further comprising the step of calcining
the molecular sieve catalyst particles.
64. A catalyst formulation slurry comprising (a) molecular sieve
particles; (b) a hydrolyzed form of aluminum oxide; (c) water; (d)
optionally, matrix particles; wherein at least 5 atom %, preferably
at least 6 atom %, more preferably at least 10 atom % of the hydrolyzed
form of aluminum oxide is in the form of oligomers having a sharp
.sup.27Al NMR peak at 62-63 ppm
65. The catalyst formulation slurry of claim 64 further comprising
a hydrolyzed form of zirconium oxide.
66. The catalyst formulation slurry of claim 65 wherein the molecular
sieve is a metalloaluminophosphate molecular sieve.
67. The catalyst formulation slurry of claim 65 wherein the molecular
sieve is a silicoaluminophosphate molecular sieve.
68. The catalyst formulation slurry of claim 65 wherein the molecular
sieve is selected from SAPO-18 SAPO-34 SAPO-44 intergrown forms
thereof, metal-containing forms thereof and mixtures thereof.
69. The catalyst formulation slurry of claim 65 wherein the catalyst
formulation slurry has a viscosity of from 1.0 to 10.0 Pa-s, preferably
of from 1.2 to 9.5 Pa-s, when measured at a temperature between
23.degree. C. and 30.degree. C., using a Brookfield LV viscometer,
with a #3 spindle at 10 rpm.
70. A molecular sieve catalyst comprising a silicoaluminophosphate
molecular sieve; aluminum oxide; zirconium oxide; and a clay; wherein
the catalyst has an ARI of less than 1.0 preferably less than 0.7
more preferably less than 0.5 most preferably less than 0.2.
71. The molecular sieve catalyst of claim 70 having an aluminum
to zirconium atomic ratio of from 0.1 to 20 preferably of from
2.0 to 15 more preferably of from 3.0 to 10.0.
72. The molecular sieve catalyst of claim 70 wherein the molecular
sieve is a metalloaluminophosphate molecular sieve.
73. The molecular sieve catalyst of claim 70 wherein the molecular
sieve is a silicoaluminophosphate molecular sieve.
74. The molecular sieve catalyst of claim 70 wherein the molecular
sieve is selected from SAPO-18 SAPO-34 SAPO-44 metal-containing
forms thereof and mixtures thereof.
75. The molecular sieve catalyst of claim 70 wherein the amount
of molecular sieve within the catalyst is from 2 wt % to 85 wt %,
preferably of from 20 wt % to 80 wt %.
76. The molecular sieve catalyst of claim 70 wherein the combined
total amount of aluminum oxide and zirconium oxide within the catalyst
is from 4 wt % to 30 wt %.
77. The molecular sieve catalyst of claim 70 wherein the particle
size distribution of the catalyst is 15-200 microns.
78. A process for the manufacture of olefins from a feedstock,
wherein the catalyst of claim 70 is contacted with a feedstock under
conditions to convert the feedstock to olefins.
79. The process of claim 78 wherein the feedstock comprises one
or more oxygenated hydrocarbons.
80. The process of claim 79 wherein the feedstock comprises methanol.
82. A method of making molecular sieve catalyst particles, the
method comprising the steps of: a) providing a solution or suspension
of inorganic oxide precursor in a liquid medium; b) aging the solution
or suspension of inorganic oxide precursor, c) combining the solution
or suspension of inorganic oxide precursor with molecular sieve,
and optionally other formulating agents, to form a catalyst formulation
slurry; d) forming molecular sieve catalyst particles from the catalyst
formulation slurry; wherein aging is carried out at a temperature
and for a duration such that the molecular sieve catalyst particles
obtained after step d) have an ARI value of less than 1.0.
83. The method of claim 82 wherein the liquid medium is water.
84. The method of claim 82 wherein the molecular sieve catalyst
particles obtained after step d) have an ARI value of less than
0.5.
85. The method of claim 82 wherein the catalyst formulation slurry
is maintained at a temperature of from 15.degree. C. to 50.degree.
C. for a period of not more than 12 hours, preferably not more than
8 hours, before forming the molecular sieve catalyst particles in
step d).
86. The method of claim 82 wherein the inorganic oxide precursor
comprises an aluminum oxide precursor and a zirconium oxide precursor.
87. The method of claim 82 wherein the inorganic oxide precursor
is an aluminum oxide or aluminum-zirconium oxide precursor.
88. The method of claim 87 wherein the inorganic oxide precursor
is selected from the group consisting of aluminum chlorohydrate
and aluminum-zirconium chlorohydrate, and mixtures thereof.
89. The method of claim 88 wherein aging of the inorganic oxide
precursor solution or suspension is carried out by maintaining the
solution or suspension of inorganic oxide at a temperature of from
10.degree. C. to 80.degree. C. for a period of at least 1 hours,
preferably for a period of at least 1.5 hours, more preferably for
a period of at least 2 hours, even more preferably for a period
of at least 3 hours, most preferably for a period of at least 4
hours.
90. The method of claim 89 wherein the temperature at which the
solution or suspension of inorganic oxide is maintained is of from
15.degree. C. to 70.degree. C., preferably of from 20.degree. C.
to 50.degree. C.
91. The method of claim 90 wherein aging takes place for a period
of at least 5 hours, preferably at least 12 hours, more preferably
at least 24 hours, most preferably at least 48 hours.
92. The method of claim 82 wherein the catalyst formulation slurry
further contains a matrix material, preferably a clay, more preferably
kaolin clay.
93. The method of claim 82 wherein the catalyst formulation slurry
has a viscosity of from 1.0 to 10.0 Pa-s, preferably of from 1.2
to 9.5 Pa-s, when measured at a temperature between 23.degree. C.
and 30.degree. C., using a Brookfield LV viscometer, with a #3 spindle
at 10 rpm.
94. The method of claim 82 wherein the molecular sieve is a metalloaluminophosphate
molecular sieve.
95. The method of claim 94 wherein the molecular sieve is a silicoaluminophosphate
molecular sieve.
96. The method of claim 95 wherein the molecular sieve is selected
from SAPO-18 SAPO-34 SAPO-44 intergrown forms thereof, metal-containing
forms thereof and mixtures thereof.
97. The method of claim 82 wherein at least a portion of the molecular
sieve used in step c) is provided in the form of uncalcined molecular
sieve catalyst particles.
98. The method of claim 82 wherein forming the catalyst particles
is performed by spray drying.
99. The method of claim 82 further comprising the step of calcining
the molecular sieve catalyst particles.
100. A process for converting a feedstock comprising organic compounds
to conversion product which comprises contacting said feedstock
with a catalyst comprising an active form of the molecular sieve
catalyst particles prepared by the process of claim 1.
101. The process of claim 100 wherein said feedstock comprises
oxygenates and said conversion product comprises one or more olefins.
102. A process for converting a feedstock comprising organic compounds
to conversion product which comprises contacting said feedstock
with an active form of the molecular sieve catalyst of claim 70.
103. The process of claim 102 wherein said feedstock comprises
oxygenates and said conversion product comprises one or more olefins.
Molecular sieve description
FIELD OF THE INVENTION
[0001] The present invention relates to a molecular sieve catalyst
composition, to a method of making or forming the molecular sieve
catalyst composition, and to a conversion process using the catalyst
composition.
BACKGROUND OF THE INVENTION
[0002] Olefins are traditionally produced from petroleum feedstock
by catalytic or steam cracking processes. These cracking processes,
especially steam cracking, produce light olefin(s) such as ethylene
and/or propylene from a variety of hydrocarbon feedstock. Ethylene
and propylene are important commodity petrochemicals useful in a
variety of processes for making plastics and other chemical compounds.
[0003] The petrochemical industry has known for some time that
oxygenates, especially alcohols, are convertible into light olefin(s).
There are numerous technologies available for producing oxygenates
including fermentation or reaction of synthesis gas derived from
natural gas, petroleum liquids, carbonaceous materials including
coal, recycled plastics, municipal waste or any other organic material.
Generally, the production of synthesis gas involves a combustion
reaction of natural gas, mostly methane, and an oxygen source into
hydrogen, carbon monoxide and/or carbon dioxide. Syngas production
processes are well known, and include conventional steam reforming,
autothermal reforming, or a combination thereof.
[0004] Methanol, the preferred alcohol for light olefin production,
is typically synthesized from the catalytic reaction of hydrogen,
carbon monoxide and/or carbon dioxide in a methanol reactor in the
presence of a heterogeneous catalyst. For example, in one synthesis
process methanol is produced using a copper/zinc oxide catalyst
in a water-cooled tubular methanol reactor. The preferred methanol
conversion process is generally referred to as a methanol-to-olefin(s)
process, where methanol is converted to primarily ethylene and/or
propylene in the presence of a molecular sieve.
[0005] Molecular sieves are porous solids having pores of different
sizes such as zeolites or zeolite-type molecular sieves, carbons
and oxides. The most commercially useful molecular sieves for the
petroleum and petrochemical industries are known as zeolites, for
example aluminosilicate molecular sieves. Zeolites in general have
a one-, two- or three-dimensional crystalline pore structure having
uniformly sized pores of molecular dimensions that selectively adsorb
molecules that can enter the pores, and exclude those molecules
that are too large.
[0006] There are many different types of molecular sieves well
known to convert a feedstock, especially an oxygenate containing
feedstock, into one or more olefin(s). For example, U.S. Pat. No.
5367100 describes the use of a well known 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 aluminophosphates,
often represented by ALPO.sub.4.
[0007] One of the most useful molecular sieves for converting methanol
to olefin(s) is a silicoaluminophosphate molecular sieve. Silicoaluminophosphate
(SAPO) molecular sieves contain a three-dimensional microporous
crystalline framework structure of [SiO.sub.2], [AlO.sub.2] and
[PO.sub.2] corner sharing tetrahedral units. SAPO synthesis is described
in U.S. Pat. No. 4440871 which is herein fully incorporated by
reference. SAPO is 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, is shown in U.S. Pat. Nos. 4499327 4677242 4677243
4873390 5095163 5714662 and 6166282 all of which are
herein fully incorporated by reference.
[0008] Typically, molecular sieves are formed into molecular sieve
catalyst compositions to improve their durability in commercial
conversion processes. The collisions within a commercial process
between catalyst composition particles themselves, the reactor walls,
and other reactor systems cause the particles to breakdown into
smaller particles called fines. The physical breakdown of the molecular
sieve catalyst composition particles is known as attrition. Fines
often exit the reactor in the effluent stream resulting in problems
in recovery systems. Catalyst compositions having a higher resistance
to attrition generate fewer fines, less catalyst composition is
required for conversion, and longer life times result in lower operating
costs.
[0009] Molecular sieve catalyst compositions are formed by combining
a molecular sieve and a matrix material usually in the presence
of a binder. The purpose of the binder is to hold the matrix material,
often a clay, to the molecular sieve. The use of binders and matrix
materials in the formation of molecular sieve catalyst compositions
is well known for a variety of commercial processes. It is also
known that the way in which the molecular sieve catalyst composition
is made or formulated affects catalyst composition attrition.
[0010] Examples of methods of making catalyst compositions include:
U.S. Pat. No. 5126298 discusses a method for making a cracking
catalyst having high attrition resistance by combining two different
clay particles in separate slurries with a zeolite slurry and a
source of phosphorous, and spray drying a mixture of the slurries
having a pH below 3; U.S. Pat. Nos. 4987110 and 5298153 relate
to a catalytic cracking process using a spray dried attrition resistant
catalyst containing greater than 25 weight percent molecular sieve
dispersed in a clay matrix with a synthetic silica-alumina component;
U.S. Pat. Nos. 5194412 and 5286369 disclose forming a catalytic
cracking catalyst of a molecular sieve and a crystalline aluminum
phosphate binder having a surface area less than 20 m.sup.2/g and
a total pore volume less than 0.1 cc/g; U.S. Pat. No. 4542118
relates to forming a particulate inorganic oxide composite of a
zeolite and aluminum chlorhydrol that is reacted with ammonia to
form a cohesive binder; U.S. Pat. No. 6153552 claims a method
of making a catalyst, by drying a slurry of a SAPO molecular sieve,
an inorganic oxide sol, and an external phosphorous source; U.S.
Pat. No. 5110776 illustrates the formation of a zeolite containing
catalytic catalyst by modifying the zeolite with a phosphate containing
solution; U.S. Pat. No. 5348643 relates to spray drying a zeolite
slurry with a clay and source of phosphorous at a pH of below 3;
U.S. Pat. No. 6440894 discusses a method for steaming a molecular
sieve to remove halogen; U.S. Pat. No. 5248647 illustrates spray
drying a SAPO-34 molecular sieve admixed with kaolin and a silica
sol; U.S. Pat. No. 5346875 discloses a method for making a catalytic
cracking catalyst by matching the isoelectric point of each component
of the framework structure to the pH of the inorganic oxide sol;
Murer, et al, Aggregation and Peptization Behavior of Zeolite Crystals
in Sols and Suspensions, Ind. Eng. Chem. Vol. 40 pages 2573-2579
2001 discusses zeolite aggregation at or near the isoelectric point;
PCT Publication WO 99/21651 describes making a catalyst by drying
a mixture of an alumina sol and a SAPO molecular sieve; PCT Publication
WO 02/05950 describes making a catalyst composition of a molecular
sieve containing attrition particles with fresh molecular sieve;
WO 02/05952 discloses a crystalline metallo-aluminophosphate molecular
sieve and a matrix material of an inorganic oxide binder and filler
where the molecular sieve is present in an amount less than 40 weight
percent relative to the catalyst weight and a preferable weight
ratio of the binder to molecular sieve close to 1; U.S. Pat. No.
4443553 discusses the addition of aluminum hydroxychloride to
an aqueous slurry employed in the preparation of fluid catalytic
cracking catalysts in order to reduce the viscosity of the slurry;
U.S. Pat. No. 4987110 discloses cracking catalysts containing
a mixture of clay and a synthetic silica-alumina component derived
from a silica sol and aluminum chlorhydroxide.
[0011] Although the molecular sieve catalyst compositions described
above are useful in hydrocarbon conversion processes, it would be
desirable to have an improved molecular sieve catalyst composition
having better attrition resistance and commercially desirable operability.
SUMMARY OF THE INVENTION
[0012] This invention provides methods of making molecular sieve
catalyst particles, molecular sieve slurries that can be used in
such methods, molecular sieve catalyst compositions and their use
in catalytic hydrocarbon conversion processes such as for the manufacture
of one or more olefin(s).
[0013] In a first aspect, the invention provides a method of making
molecular sieve catalyst particles, the method comprising the steps
of: a) providing a solution or suspension of an aluminum-containing
inorganic oxide precursor in a liquid medium; b) combining the solution
or suspension of aluminum-containing inorganic oxide precursor with
a molecular sieve, and optionally other formulating agents, to form
a catalyst formulation slurry; c) aging the catalyst formulation
slurry to generate in said slurry a percentage, or increase in said
slurry the existing percentage, of aluminum atoms of the aluminum-containing
precursor in the form of oligomers having a sharp .sup.27Al NMR
peak at 62-63 ppm; and d) forming molecular sieve catalyst particles
from the catalyst formulation slurry.
[0014] Preferably, aging is carried out at a temperature and for
a period of time such that at least 5 atom %, more preferably 10
atom %, of the aluminum atoms of the aluminum-containing precursor
in the catalyst formulation slurry is in the form of oligomers having
between 10 and 75 aluminum atoms per molecule.
[0015] In another preferred embodiment, at least 6 atom %, preferably
8 atom %, of the aluminum atoms of the aluminum-containing precursor
in the catalyst formulation slurry is in the form of oligomers having
a sharp .sup.27Al NMR peak at 62-63 ppm.
[0016] In a second aspect, the invention provides a method of making
molecular sieve catalyst particles, the method comprising the steps
of: a) preparing a solution or suspension of inorganic oxide precursor
in a liquid medium; b) combining the solution or suspension of inorganic
oxide precursor with a molecular sieve, and optionally other formulating
agents, to form a catalyst formulation slurry; c) aging the suspension
of inorganic oxide; and d) forming molecular sieve catalyst particles
from the catalyst formulation slurry; wherein said aging is carried
out at a temperature and for a duration such that the catalyst formulation
slurry has a Relative Binding Efficiency between 1.02 and 1.25.
Preferably, aging is carried out at a temperature and for a period
of time such that the catalyst formulation slurry has a Relative
Binding Efficient between 1.02 and 1.2 preferably 1.18 more preferably
1.15.
[0017] In a third aspect, the present invention provides a method
of making molecular sieve catalyst particles, the method comprising
the steps of: a) preparing a solution or suspension of inorganic
oxide precursor in a liquid medium; b) combining the solution or
suspension of inorganic oxide precursor with a molecular sieve,
and optionally other formulating agents, to form a catalyst formulation
slurry; c) aging the catalyst formulation slurry; and d) forming
molecular sieve catalyst particles from the catalyst formulation
slurry; wherein said aging is carried out at a temperature and for
a duration such that the molecular sieve catalyst particles obtained
after step d) have an ARI value of less than 1.0 preferably of
less than 0.5.
[0018] In all three aforementioned aspects of the invention, it
is preferred that aging in step c) takes place by maintaining the
catalyst formulation slurry at a temperature of from 0.degree. C.
to 100.degree. C., more preferably of from 15.degree. C. to 80.degree.
C. for a period of at least 2 hours, more preferably for a period
of at least 4 hours, even more preferably at least 5 hours and most
preferably at least 8 hours. It is also preferred that the solution
or suspension of inorganic oxide is not aged before combining with
the other formulation slurry ingredients.
[0019] In a fourth aspect, the present invention provides method
of making molecular sieve catalyst particles, the method comprising
the steps of: a) providing a solution or suspension of inorganic
oxide precursor in a liquid medium; b) aging the solution or suspension
of inorganic oxide precursor, c) combining the solution or suspension
of inorganic oxide precursor with molecular sieve, and optionally
other formulating agents, to form a catalyst formulation slurry;
d) forming molecular sieve catalyst particles from the catalyst
formulation slurry; wherein aging is carried out at a temperature
and for a duration such that the molecular sieve catalyst particles
obtained after step d) have an ARI value of less than 1.0 preferably
of less than 0.5.
[0020] In this fourth aspect of the invention, it is preferred
that the catalyst formulation slurry is maintained at a temperature
of from 15.degree. C. to 50.degree. C. for a period of not more
than 12 hours, preferably not more than 8 hours, before forming
the molecular sieve catalyst particles in step d).
[0021] Also, in this fourth aspect of the invention, aging of the
inorganic oxide precursor solution or suspension is preferably carried
out by maintaining the solution or suspension of inorganic oxide
at a temperature of from 110.degree. C. to 80.degree. C. for a period
of at least 1 hours, preferably for a period of at least 1.5 hours,
more preferably for a period of at least 2 hours, even more preferably
for a period of at least 3 hours, most preferably for a period of
at least 4 hours. More preferably, the solution or suspension of
inorganic oxide is maintained is of from 15.degree. C. to 70.degree.
C., preferably of from 20.degree. C. to 50.degree. C.
[0022] In yet another preferred embodiment of all four aforementioned
aspects of the invention, it is preferred that forming the catalyst
particles is performed by spray drying and that the method comprises
the step of calcining the molecular sieve catalyst particles before
catalytic use.
[0023] Also, for all four aforementioned aspects of the invention,
the preferred inorganic oxide precursor comprises an aluminum oxide
precursor and/or a zirconium oxide precursor, and is more preferably
an aluminum chlorohydrate or an aluminum-zirconium chlorohydrate.
[0024] In a separate embodiment of all four aforementioned aspects
of the invention, the preferred liquid medium is water.
[0025] In a fifth aspect, the present invention provides a catalyst
formulation slurry comprising (a) molecular sieve particles; (b)
a hydrolyzed form of aluminum oxide; (c) water; (d) optionally,
matrix particles; wherein at least 5 atom %, preferably at least
6 atom %, more preferably at least 10 atom % of the hydrolyzed form
of aluminum oxide is in the form of oligomers having a sharp .sup.27Al
NMR peak at 62-63 ppm Preferably, the catalyst formulation slurry
further comprises a hydrolyzed form of zirconium oxide.
[0026] In all five aforementioned aspects of the invention, it
is preferred that the catalyst formulation slurry further contains
a matrix material, preferably a clay, more preferably kaolin clay.
[0027] In another embodiment of all five aforementioned aspects
of the invention, it is preferred that the catalyst formulation
slurry has a viscosity of from 1.0 to 10.0 Pa-s, preferably of from
1.2 to 9.5 Pa-s, when measured at a temperature between 23.degree.
C. and 30.degree. C., using a Brookfield LV viscometer, with a #3
spindle at 10 rpm.
[0028] In a sixth aspect, the present invention provides a molecular
sieve catalyst comprising a silicoaluminophosphate molecular sieve;
aluminum oxide; zirconium oxide; and a clay; wherein the catalyst
has an ARI of less than 1.0 preferably less than 0.7 more preferably
less than 0.5 most preferably less than 0.2. Preferably the catalyst
has having an aluminum to zirconium atomic ratio of from 0.1 to
20 preferably of from 2.0 to 15 more preferably of from 3.0 to
10.0.
[0029] The present invention also relates to the use of the catalysts
of the present invention, or made by any method of the present invention
in the conversion of hydrocarbon feedstocks.
[0030] In all aspects of the invention, the molecular sieve is
preferably a metalloaluminophosphate molecular sieve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 shows .sup.27Al NMR spectra of aluminum chlorohydrate
(ACH) solutions prepared with and without aging;
[0032] FIG. 2 shows .sup.27Al NMR spectra of NALCO-1056 and NALCO-8676
solutions prepared with an without aging.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Introduction
[0034] The invention is directed toward molecular sieve catalyst
compositions, their making and to their use in the conversion of
feedstocks into one or more olefin(s).
[0035] The molecular sieve catalyst compositions of the present
invention are formed from what we shall hereinafter refer to as
a catalyst formulation slurry. The catalyst formulation slurry is
prepared by combining a solution or suspension of an inorganic oxide
precursor, preferably an aluminum oxide or an aluminum-zirconium
oxide precursor, with a molecular sieve, optionally in the presence
of at least another formulating agent. The slurry then goes through
a forming process to produce shaped products, e.g., spray drying.
After calcination, molecular sieve catalyst particles are obtained,
which have a high resistance to attrition, i.e. physical breakdown.
[0036] We have surprisingly found that when the catalyst formulation
slurry is submitted to a mild thermal treatment (aging) before formation
of the catalyst particles, the molecular sieve catalyst particles
are more resistant to attrition than when the catalyst formulation
slurry is not aged before formation of the catalyst particles. Also,
we have surprisingly found that, if the solution or suspension of
inorganic oxide precursor is submitted to a mild thermal treatment
(aged) before forming the catalyst formulation slurry, the molecular
sieve catalyst particles are more resistant to attrition than when
the solution or suspension of inorganic oxide is not aged. In addition,
we have found that, when the solution or suspension of inorganic
oxide precursor is submitted to a mild thermal treatment (aged)
before forming the catalyst formulation slurry, aging of the catalyst
formulation slurry should be prevented in order to obtain catalyst
particles with highest attrition resistance.
[0037] Without wishing to be bound to any theory, when appropriate
aging of the solution or suspension of inorganic oxide or appropriate
aging of the catalyst formulation slurry is applied, there appears
to be an ideal distribution of reactive ionic species in the catalyst
formulation slurry, that determines the binding efficiency of the
inorganic oxide precursors during the catalyst formulation process.
For example, with precursors of aluminum oxide and precursors of
aluminum-zirconium oxides, various hydrated forms of aluminum ions,
zirconium ions, aluminum hydroxide, zirconium hydroxide, aluminum
oxide and zirconium oxide are believed to be present in water solutions
or suspensions. Various forms of aluminum compounds are present
in the liquid phase, such as oligomeric forms of aluminum containing
from 2 to several hundred aluminum atoms per molecule. Various forms
of zirconium compounds are present in the liquid phase, such as
oligomeric forms of zirconium containing from 2 to several hundreds
of zirconium atoms per molecule. The distribution of oligomers depends
on several factors including, but not limited to, the aluminum oxide
precursor concentration, temperature, the pH, mixing, treatment
history, and the ionic strength.
[0038] The present invention provides methods by which an optimal
distribution of reactive ionic species is obtained in the catalyst
formulation slurry, during the catalyst formulation process. The
distribution of reactive ionic species, preferably reactive aluminum
species, is optimal in that the catalyst formulation slurry yields
molecular sieve catalyst particles with higher attrition resistance
than when aging according to the invention is not applied.
[0039] Catalyst Formulation Slurries
[0040] In the context of the present invention, the molecular sieves
synthesized above are used in commercial catalytic processes. For
this purpose, they are made or formulated into molecular sieve catalyst
particles. Molecular sieve catalyst formulation involves making
a catalyst formulation slurry, which is then formed into catalyst
particles. In the context of the present invention, the molecular
sieve-containing slurry which is formed into catalyst particles
shall be referred to as the catalyst formulation slurry.
[0041] The catalyst formulation slurry is made by combining the
synthesized molecular sieve(s) with an inorganic oxide precursor
and optionally with a matrix material and/or other formulating agents.
In an embodiment, the catalyst formulation slurry is formed by combining
an aqueous solution or suspension of an inorganic oxide precursor
with a molecular sieve under mixing.
[0042] Preferably, the molecular sieve is used in a not fully dried
state, such as a filter cake obtained after molecular sieve synthesis,
often referred to as a wet filter cake. In another, but less preferred,
embodiment, the molecular sieve is fully dried, and optionally calcined,
before combining with the solution or suspension of inorganic oxide
precursor.
[0043] The catalyst formulation slurry may also contain uncalcined
molecular sieve-containing catalyst particles, which are recycled
in the formulation process, as described in PCT publication No.
WO 02/05950 U.S. Pat. Nos. 6605749 6541415 6509290 and
US Application publication No. 2003/0135079 all incorporated herewith
by reference.
[0044] There are many inorganic oxide precursors that are useful
according to the present invention, non-limiting examples of which
include various types of hydrated alumina, silicas, and/or other
inorganic oxide sol. Examples of preferred inorganic oxide precursors
are alumina precursors, more preferably aluminum chlorohydrate and
aluminum-zirconium chlorohydrate. The inorganic oxide precursor
used according to the present invention, is converted into an inorganic
oxide during the process for manufacturing molecular sieve catalyst
particles. During the catalyst manufacturing process, the inorganic
oxide precursor acts like glue, binding the synthesized molecular
sieves and other optional catalyst formulation materials together,
particularly after drying, and/or calcination. Upon heating, the
inorganic oxide precursor is converted into an inorganic oxide matrix
component. For example, an alumina sol (precursor) will convert
to an aluminum oxide matrix following heat treatment and a mixed
zirconia-alumina sol (precursor) will convert to a mixed aluminum-zirconium
oxide.
[0045] Aluminum chlorohydrate, also referred to as aluminum chlorhydrol
or aluminum hydroxychloride, 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.multidot.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. Aluminum chlorohydrate
is usually prepared by dissolving either metallic aluminum or hydrated
alumina in hydrochloric acid under controlled conditions. Aluminum
chlorohydrate is available commercially in different forms, such
as solid products, for example, the solid of chemical formula Al.sub.2(OH).sub.5Cl.n(H.sub.2O)
or as pre-prepared, commercially available, aqueous solutions. Other
non-limiting examples of useful aluminum oxide precursors that may
be used according to this invention include aluminum hexahydrate,
aluminum pentachlorohydrate (Al.sub.2(OH)Cl.sub.5), aluminum tetrachlorohydrate
(Al.sub.2(OH).sub.2Cl.sub.4), aluminum trichlorohydrate (Al.sub.2(OH).sub.3Cl.sub.3),
aluminum dichlorohydrate (Al.sub.2(OH).sub.4Cl.sub.2), aluminum
sesquichlorohydrate (Al.sub.2(OH).sub.4.5Cl.sub.1.5).
[0046] In aqueous solution, aluminum chlorohydrate forms monomeric,
dimeric, oligomeric and polymeric aluminum species, depending on
several factors such as the pH, temperature, treatment history,
and the presence of other ionic species or concentration of other
ionic species.
[0047] Other non-limiting example of binders useful according to
the present invention are precursors of aluminum-zirconium oxides.
Such precursors include, but are not limited to, aluminum zirconium
chlorohydrates, for example, aluminum zirconium trichlorohydrate,
aluminum zirconium tetrachlorohydrate, aluminum zirconium pentachlorohydrate,
aluminum zirconium octachlorohydrate, aluminum zirconium chlorhydrex,
aluminum zirconium chlorhydrex glycine complexes, for example, aluminum
zirconium trichlorohydrex glycine complex, aluminum zirconium tetrachlorohydrex
glycine complex, aluminum zirconium pentachlorohydrex glycine complex,
and aluminum zirconium octachlorohydrex glycine complex. In the
absence of glycine, these materials form gels in aqueous solutions.
Reheis Chemicals Inc., Berkeley Heights, N.J. produces a variety
of aluminum zirconium chlorohydrates. These materials can be prepared
from a variety of zirconium starting materials such as zirconyl
chloride (ZrOCl.sub.2), zirconyl hydroxychloride (ZrO(OH)Cl), zirconium
hydroxy carbonate paste (ZrO(OH)(CO.sub.3)0.5), and combinations
of these zirconium starting materials, with a hydrated aluminum
solution, such as a solution of aluminum chlorohydrate, aluminum
hexahydrate, aluminum sesquichlorohydrate or aluminum dichlorohydrate
solution, or a solution obtained by combining one or several of
these aluminum species solutions. Aluminum zirconium tetrachlorohydrates
are used in antiperspirants and deodorants (Joe Parekh, "APD
Aluminum Chlorohydrate", in Soap, Perfumery & Cosmetics,
July, 2001; Allan H. Rosenberg and John J. Fitzgerald, "Chemistry
of Aluminum-Zirconium-Glycine Complexes", in Antiperspirants
and Deodorants, 2nd Edition, Revised and Expanded, ed. by Karl Laden,
Marcel Dekker, New York, 1999 pp. 137-168.). Products from Reheis
include REACH AZP 902 REACH AZP 908 REACH AZP 855 REACH AZZ 902
REACH AZZ 855 and REACH AZN 855.
[0048] In concentrated zirconium solutions, cationic polynuclear
Zr.sup.4+ complexes, e.g., Zr.sub.3(OH).sub.4.sup.8+, Zr.sub.3(OH).sub.5.sup.7+,
Zr.sub.4(OH).sub.8.sup.8+, rather than mononuclear hydrolysis species,
are predominant in the pH range of 0 to 3.
[0049] Without wishing to be bound by any particular theory, it
is believed that the presence of the zirconium complexes in aluminum
zirconium chlorohydrate solutions causes depolymerization of the
high-molecular-weight aluminum species together with the formation
of aluminum dimer and monomer species. The acid catalyzed depolymerization
of the aluminum species is also accomplished by further polymerization
of the various zirconium species.
[0050] Other non-limiting examples of alumina precursors that can
be used as inorganic oxide precursors in the catalyst formulation
slurry include one or several of the following: aluminum oxyhydroxide,
.gamma.-alumina, boehmite, diaspore, and transitional aluminas such
as .beta.-alumina, .gamma.-alumina, .delta.-alumina, .epsilon.-alumina,
.kappa.-alumina, and .rho.-alumina, aluminum trihydroxide, such
as gibbsite, bayerite, nordstrandite, doyelite, and mixtures thereof.
[0051] In an embodiment, the inorganic oxide precursor solution
or suspension, preferably an alumina or mixed aluminum-zirconium
oxide precursor solution, is prepared immediately before catalyst
formulation from an inorganic oxide precursor in powder form and
water. Such inorganic oxide precursor solutions shall be hereinafter
referred to as "fresh" solutions or "not-aged"
solutions. In an embodiment, the fresh inorganic oxide precursor
solution is not aged before combining with the other catalyst formulation
slurry ingredients, i.e. the inorganic oxide precursor solution
is maintained at a temperature of from 15.degree. C. to 50.degree.
C. for a period of not more than 8 hours, more preferably not more
than 6 hours, even more preferably not more than 4 hours and most
preferably not more than 2 hours, before combining with the other
ingredients used to formulate the catalyst.
[0052] The fresh inorganic oxide solution is combined with the
molecular sieve to form the catalyst formulation slurry, and then
allowed to age before forming the molecular sieve catalyst particles.
In this embodiment, aging means submitting the catalyst formulation
slurry to a mild thermal treatment, with or without agitation and/or
stirring and/or mixing. The duration of the thermal treatment should
be sufficient to allow the generation of the reactive ionic species
at a sufficient rate and in an amount sufficient to allow the best
attrition resistance properties in the catalyst particles.
[0053] Conditions of duration and temperature that allow to achieve
this result include: maintaining the catalyst formulation slurry
at a temperature of from 0.degree. C. to 100.degree. C., preferably
of from 10.degree. C. to 90.degree. C., more preferably of from
15.degree. C. to 80.degree. C., most preferably of from 20.degree.
C. to 70.degree. C. The duration of this mild thermal treatment
can vary, depending on various factors such as the type of inorganic
oxide precursor, the concentration of the inorganic precursor and
the temperature. The higher the temperature and the lower the concentration
in inorganic oxide precursor, the less time will be required to
achieve the proper level of aging of the catalyst formulation slurry
according to the invention. Periods of aging will typically be at
least 2 hours, preferably at least 4 hours, more preferably at least
5 hours, even more preferably at least 8 hours and most preferably
at least 10 hours. In a preferred embodiment, aging of the catalyst
formulation slurry is performed for not more than 150 hours, preferably
not more than 120 hours, most preferably not more than 100 hours.
If aging takes place at a temperature of from 30.degree. C. to 50.degree.
C., aging of the catalyst formulation preferably takes place for
a period of from 4 hours to 80 hours, preferably of from 5 hours
to 75 hours, more preferably of from 6 hours to 50 hours, most preferably
of from 7 hours to 26 hours.
[0054] In a separate embodiment, the inorganic oxide precursor
aqueous solution (or suspensions) has been prepared well before
combining with the first molecular sieve slurry, i.e. the aluminum
chlorohydrate solution has been allowed to age before combining
with the first molecular sieve slurry. This would be the case, for
example, when commercially available solutions of inorganic oxide
precursors are used. In this embodiment, aging of the inorganic
oxide precursor aqueous solution means submitting the solution or
suspension of inorganic oxide precursor to a mild thermal treatment
with or without agitation and/or stirring and/or mixing, before
combining the solution of inorganic oxide precursor with the other
ingredients used to formulate the catalyst. The duration of this
mild thermal treatment should be sufficient to allow the generation
of the reactive ionic species at a sufficient rate and in an amount
sufficient when the solution or suspension of inorganic oxide precursor
is combined with the molecular sieve in the catalyst formulation
slurry. Aging should be performed at a temperature and for a period
of time sufficient to allow the best attrition resistance properties
in the catalyst particles.
[0055] Conditions of duration and temperature that allow to achieve
this result include: maintaining the solution or suspension of inorganic
oxide precursor at a temperature of from 0.degree. C. to 100.degree.
C., preferably of from 10.degree. C. to 90.degree. C., more preferably
of from 15.degree. C. to 80.degree. C., most preferably of from
20.degree. C. to 70.degree. C. The duration of this mild thermal
treatment can vary, depending on various factors such as the type
of inorganic oxide precursor, the concentration of the inorganic
precursor and the temperature. The higher the temperature and the
lower the concentration in inorganic oxide precursor, the less time
will be required to achieve the proper level of aging of the solution
or suspension of inorganic oxide precursor according to the invention.
Periods of aging will typically be at least 2 hours, preferably
at least 4 hours, more preferably at least 5 hours and most preferably
at least 6 hours. In a preferred embodiment, aging of the solution
or suspension of inorganic oxide precursor takes place at a temperature
of from 30.degree. C. to 90.degree. C. and for a period of from
4 to 24 hours, preferably at a temperature of from 30.degree. C.
to 55.degree. C. and for a period of from 5 to 20 hours.
[0056] If the inorganic oxide precursor aqueous solution or suspension
has been aged before forming the catalyst formulation slurry, it
is preferred that the catalyst formulation slurry not be aged before
forming the molecular sieve catalyst particles.
[0057] In a preferred embodiment, the inorganic oxide precursor
solution or suspension contains from 1% to 80%, preferably from
2% to 75%, more preferably from 4 to 35 wt % of the inorganic oxide
precursor, regardless of whether the inorganic oxide solution or
suspension has been aged or not before combining with the other
catalyst formulation ingredients.
[0058] Besides the inorganic oxide precursor, the catalyst formulation
slurry of the invention contains at least one molecular sieve and,
optionally a matrix material or other formulating agents.
[0059] The molecular sieve that can be used in the catalyst formulation
process of the present invention vary within wide ranges of composition
and structural features.
[0060] Molecular sieves have various chemical and physical, framework,
characteristics. Molecular sieves have been classified by the Structure
Commission of the International Zeolite Association according to
the rules of the IUPAC Commission on Zeolite Nomenclature. A framework-type
describes the connectivity, topology, of the tetrahedrally coordinated
atoms constituting the framework, and making an abstraction of the
specific properties for those materials. Framework-type zeolite
and zeolite-type molecular sieves for which a structure has been
established, are assigned a three letter code and are described
in the Atlas of Zeolite Framework Types, 5th edition, Elsevier,
London, England (2001), which is herein fully incorporated by reference.
[0061] Molecular sieve materials have 3-dimensional framework structure
of corner-sharing TO.sub.4 tetrahedra, where T is any tetrahedrally
coordinated cation. These molecular sieves are typically described
in terms of the size of the ring that defines a pore, where the
size is based on the number of T atoms in the ring. Other framework-type
characteristics include the arrangement of rings that form a cage,
and when present, the dimension of channels, and the spaces between
the cages. See van Bekkum, et al., Introduction to Zeolite Science
and Practice, Second Completely Revised and Expanded Edition, Volume
137 pages 1-67 Elsevier Science, B. V., Amsterdam, Netherlands
(2001).
[0062] The small, medium and large pore molecular sieves have from
a 4-ring to a 12-ring or greater framework-type. In a preferred
embodiment, the zeolitic molecular sieves have 8-, 10- or 12-ring
structures or larger and an average pore size in the range of from
about 3 .ANG. to 15 .ANG.. In the most preferred embodiment, the
molecular sieves of the invention, preferably silicoaluminophosphate
molecular sieves have 8-rings and an average pore size less than
about 5 .ANG., preferably in the range of from 3 .ANG. to about
5 .ANG., more preferably from 3 .ANG. to about 4.5 .ANG., and most
preferably from 3.5 .ANG. to about 4.2 .ANG..
[0063] Molecular sieves, particularly zeolitic and zeolitic-type
molecular sieves, preferably have a molecular framework of one,
preferably two or more corner-sharing [TO.sub.4] tetrahedral units,
more preferably, two or more [SiO.sub.4], [AlO.sub.4] and/or [PO.sub.4]
tetrahedral units, and most preferably [SiO.sub.4], [AlO.sub.4]
and [PO.sub.4] tetrahedral units.
[0064] Non-limiting examples of molecular sieves having a molecular
framework made of corner-sharing [SiO.sub.4] and [AlO.sub.4] tetrahedral
units that can be used include the small pore molecular sieves,
AEI, AFT, APC, ATN, ATT, ATV, AWW, BIK, CAS, CHA, CHI, DAC, DDR,
EDI, ERI, GOO, KFI, LEV, LOV, LTA, MON, PAU, PHI, RHO, ROG, THO,
and substituted forms thereof; the medium pore molecular sieves,
AFO, AEL, EUO, HEU, FER, MEL, MFI, MTW, MTT, TON, and substituted
forms thereof; and the large pore molecular sieves, EMT, FAU, and
substituted forms thereof. Other molecular sieves include ANA, BEA,
CFI, CLO, DON, GIS, LTL, MER, MOR, MWW and SOD. Non-limiting examples
of the preferred molecular sieves, particularly for converting an
oxygenate containing feedstock into olefin(s), include AEL, AFY,
BEA, CHA, EDI, FAU, FER, GIS, LTA, LTL, MER, MFI, MOR, MTT, MWW,
TAM and TON. In one preferred embodiment, the molecular sieve of
the invention has an AEI topology or a CHA topology, or a combination
thereof, most preferably a CHA topology.
[0065] Non-limiting examples of molecular sieves having a molecular
framework made of corner-sharing [AlO.sub.4] and [PO.sub.4], optionally
with [SiO.sub.4], tetrahedral units that can be used in the catalyst
formulation processes of the invention include those 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 (AlPO.sub.4), 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. 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 are
described in R. Szostak, Handbook of Molecular Sieves, Van Nostrand
Reinhold, New York, N.Y. (1992), which is herein fully incorporated
by reference.
[0066] The more preferred silicon, aluminum and/or phosphorous
containing molecular sieves, and aluminum, phosphorous, and optionally
silicon, containing molecular sieves include aluminophosphate (ALPO)
molecular sieves and silicoaluminophosphate (SAPO) molecular sieves
and metal substituted ALPO and SAPO molecular sieves. The most preferred
molecular sieves are SAPO molecular sieves, and metal substituted
SAPO molecular sieves. In an embodiment, the metal is an alkali
metal of Group IA of the Periodic Table of Elements, an alkaline
earth metal of Group IIA of the Periodic Table of Elements, a rare
earth metal 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, a transition
metal of Groups IVB, VB, VIB, VIIB, VIIIB, and IB of the Periodic
Table of Elements, or mixtures of any of these metal species. In
one preferred 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. In another preferred embodiment, these metal atoms discussed
above are 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.
[0067] In one embodiment, the molecular sieve, as described in
many of the U.S. patents mentioned above, is represented by the
empirical formula, on an anhydrous basis:
mR:(M.sub.xAl.sub.yP.sub.z)O.sub.2
[0068] 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 one of Group IA, IIA, IB, IIIB,
IVB, VB, VIB, VIIB, VIIIB and Lanthanide's of the Periodic Table
of Elements, preferably M is selected from one of the group consisting
of 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.
[0069] Desirably, the molecular sieves of this invention are metalloaluminophosphate
that contain Si and Al, at a Si/Al atomic 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. Preferably,
the metalloaluminophosphate molecular sieves contain Si and Al at
an atomic ratio of at least about 0.005 more preferably at least
about 0.01.
[0070] Non-limiting examples of SAPO and ALPO molecular sieves
of the invention 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 (U.S. Pat.
No. 6162415), 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. The more preferred molecular sieves include one
or a combination of SAPO-18 SAPO-34 SAPO-35 SAPO-44 SAPO-56
ALPO-18 and ALPO-34 even more preferably one or a combination of
SAPO-18 SAPO-34 ALPO-34 and ALPO-18 and metal containing molecular
sieves thereof, and most preferably one or a combination of SAPO-34
and ALPO-18 and metal containing molecular sieves thereof.
[0071] In an embodiment, the molecular sieve is an intergrowth
material having two or more distinct phases of crystalline structures
within one molecular sieve composition. AEI/CHA intergrowths are
described in the U.S. patent application Ser. No. 09/924016 filed
Aug. 7 2001 and PCT 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. In another embodiment, the molecular sieve comprises
at least one intergrown phase of AEI and CHA framework-types.
[0072] Optionally, the catalyst formulation slurry also contains
one or more matrix material(s). Matrix materials are typically effective
in reducing overall catalyst cost, act as thermal sinks assisting
in shielding heat from the catalyst composition for example during
regeneration, densifying the catalyst composition, increasing catalyst
strength such as crush strength and attrition resistance, and to
control the rate of conversion in a particular process.
[0073] Non-limiting examples of matrix materials include one or
more of: rare earth metals, non-active, metal oxides including titania,
zirconia, magnesia, thoria, 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; most preferably the
matrix material is kaolin. Kaolin has been found to form a pumpable,
high solid content slurry, it has a low fresh surface area, and
it packs together easily due to its platelet structure. A preferred
average particle size of the matrix material, most preferably kaolin,
is from about 0.05 .mu.m to about 0.6 .mu.m with a d.sub.90 particle
size of less than about 1 .mu.m.
[0074] The amount of inorganic oxide precursor (when expressed
as inorganic oxide) in the catalyst formulation slurry is from about
2% by weight to about 35% by weight, preferably from about 3% by
weight to about 28% by weight, and more preferably from about 4%
by weight to about 24% by weight, based on the total weight of the
inorganic oxide precursor (when expressed as inorganic oxide), the
molecular sieve and matrix material, excluding the liquid.
[0075] Non-limiting examples of other optional formulation agents
that can be present in the catalyst formulation slurry include surfactants,
for example, Calloway 3330 from Vulcan Chemicals Inc., Mongomery,
Ala., or other water soluble polymers, for example, polyvinyl provilidone
(PVP)-K90 from BASF America, Rockway, N.J.
[0076] At all stages of the molecular sieve catalyst formulation
process, mixing, and preferably, vigorous mixing is needed to produce
a substantially homogeneous mixture. In one embodiment, the slurry
is subjected to high shear for a period of time sufficient to produce
the desired slurry texture, size and/or size distribution of catalyst
formulation slurry components in the form of solid particles. Suitable
means for subjecting the slurry to milling including colloid mills,
inline mixers, and the like.
[0077] While the present invention is illustrated with slurries
of molecular sieves in water, other liquids can used in partial
or complete replacement of water. Non-limiting examples of suitable
liquids include one or a combination of water, alcohols, ketones,
aldehydes, and/or esters. The most preferred liquid is water.
[0078] To ensure the quality of the catalyst formulation slurry
before forming catalyst particles of the invention, the pH, surface
area, solid content and density of the slurry are also preferably
monitored using respectively, for example, a Cole Palmer pH meter,
Micromeritics Gemini 9375 surface area instrument available from
Micometrics Instrument Corporation, Norcross, Ga., CEM MAS 700 microwave
muffle furnace for solid content determination available from CEM
Corporation, Mathews, N.C. and any standard volume measuring device
that can be accurately weighed.
[0079] Aging during the catalyst formulation process of the present
invention results in catalyst formulation slurries having relatively
high viscosity. Preferably, before forming the catalyst particles,
the catalyst formulation slurry has a viscosity of from 1000 centipoise
to 10000 centipoise (1.0 to 10 Pa-s), more preferably of from 1200
centipoise to 9500 centipoise (1.2-9.5 Pa-s), when measured at
a temperature between 23 and 30.degree. C., as measured using a
Brookfield LV-DVE viscometer with a #3 spindle at 10 rpm.
[0080] In one embodiment, the sequence of adding each individual
component, the molecular sieve, inorganic oxide precursor, matrix
material, and other ingredient, is performed in a specific order.
Sequence of addition is most important when the surface of the different
particles, whether these are of the molecular sieve, the binder,
or the matrix materials, have opposite charges, negative and positive,
or different charge densities. As a general rule, after size reduction
is completed, if necessary, the last step is the addition and mixing
of the opposite charged particles. In one preferred embodiment,
it is best to add the component selected from the molecular sieve,
the binder or the matrix material, having a higher charge density
per unit mass to a component having a lower charge density per unit
mass.
[0081] Molecular Sieve Catalyst Particles
[0082] The catalyst formulation slurry is formed into catalyst
particles, using a forming unit. In a preferred embodiment, the
forming unit is a spray dryer. Typically, the forming unit is maintained
at a temperature sufficient to evaporate most of the liquid from
the catalyst formulation slurry, and form the resulting molecular
sieve catalyst particles. The resulting catalyst composition when
formed in this way preferably takes the form of microspheres.
[0083] When a spray dryer is used as the forming unit, typically,
the catalyst formulation slurry is fed to the spray drying volume
with a drying gas with an average inlet temperature ranging from
100.degree. C. to 550.degree. C., and a combined outlet temperature
ranging from 50.degree. C. to about 225.degree. C. In an embodiment,
the average diameter of the spray dried formed catalyst composition
is from about 10 .mu.m to about 300 .mu.m, preferably from about
20 .mu.m to about 250 .mu.m, more preferably from about 30 .mu.m
to about 150 .mu.m, and most preferably from about 40 .mu.m to about
120 .mu.m.
[0084] During spray drying, the slurry is passed through a nozzle
distributing the slurry into small droplets, resembling an aerosol
spray into a drying chamber. Atomization is achieved by forcing
the slurry through a single nozzle or multiple nozzles with a pressure
drop in the range of from 100 psig to 2000 psig (690 kpag to 13790
kPag). In another embodiment, the slurry is co-fed through a single
nozzle or multiple nozzles along with an atomization fluid such
as air, steam, flue gas, or any other suitable gas with a pressure
drop in the range of from 1 psig to 150 psig (6.9 kPag to 1034 kpag).
[0085] In yet another embodiment, the slurry described above is
directed to the perimeter of a spinning wheel that distributes the
slurry into small droplets, the size of which is controlled by many
factors including slurry viscosity, surface tension, flow rate,
pressure, and temperature of the slurry, the shape and dimension
of the nozzle(s), or the spinning rate of the wheel. These droplets
are then dried in a co-current or counter-current flow of air passing
through a spray drier to form a substantially dried or dried molecular
sieve catalyst composition, more specifically a molecular sieve
catalyst composition in a microspherical form.
[0086] Generally, the size of the microspheres is controlled to
some extent by the solids content of the slurry. However, control
of the size of the catalyst composition and its spherical characteristics
are also controllable by varying the slurry feed properties and
conditions of atomization.
[0087] Other methods for forming a molecular sieve catalyst composition
is described in U.S. patent application Ser. No. 09/617714 filed
Jul. 17 2000 (spray drying using a recycled molecular sieve catalyst
composition), which is herein incorporated by reference.
[0088] In another embodiment, the formulated molecular sieve catalyst
composition contains from about 1% to about 99%, preferably from
about 10% to about 90%, more preferably from about 10% to about
80%, even more preferably from about 20% to about 70%, and most
preferably from about 20% to about 60% by weight of the molecular
sieve based on the total weight of the molecular sieve catalyst
composition.
[0089] 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.
A conventional calcination environment is air that typically includes
a small amount of water vapor. Typical calcination temperatures
are in the range from about 400.degree. C. to about 1000.degree.
C., preferably from about 500.degree. C. to about 800.degree. C.,
and most preferably from about 550.degree. C. to about 700.degree.
C., preferably in a calcination environment such as air, nitrogen,
helium, flue gas (combustion product lean in oxygen), or any combination
thereof. In one embodiment, calcination of the formulated molecular
sieve catalyst composition is carried out in any number of well
known devices including rotary calciners, fluid bed calciners, batch
ovens, and the like. Calcination time is typically dependent on
the degree of hardening of the molecular sieve catalyst composition
and the temperature ranges from about 1 minutes to about 10 hours,
preferably 15 minutes to about 2 hours.
[0090] In one embodiment, the attrition resistance of a molecular
sieve catalyst composition is measured using an Attrition Rate Index
(ARI), measured in weight percent catalyst composition attrited
per hour. An apparatus that can be used for this purpose is as described
in S. A. Weeks and P. Dumbill, in Oil & Gas Journal, pages 38
to 40 1987 which is herein fully incorporated by reference. A
detailed description of the test is provided in the examples below,
that illustrate the present invention.
[0091] In one embodiment, the molecular sieve catalyst composition
or formulated molecular sieve catalyst composition has an ARI less
than 5 weight percent per hour, preferably less than 2 weight percent
per hour, more preferably less than 1 weight percent per hour and
most preferably less than 0.5 weight percent per hour. In one embodiment,
the molecular sieve catalyst composition or formulated molecular
sieve catalyst composition has an ARI in the range of from 0.1 weight
percent per hour to less than 5 weight percent per hour, more preferably
from about 0.2 weight percent per hour to less than 3 weight percent
per hour, and most preferably from about 0.2 weight percent per
hour to less than 2 weight percent per hour.
[0092] Process For Using the Molecular Sieve Catalyst Compositions
[0093] The catalyst compositions described above are useful in
a variety of processes including cracking, of for example a naphtha
feed to light olefin(s) (U.S. Pat. No. 6300537) or higher molecular
weight (MW) hydrocarbons to lower MW hydrocarbons; hydrocracking,
of for example heavy petroleum and/or cyclic feedstock; isomerization,
of for example aromatics such as xylene; polymerization, of for
example one or more olefin(s) to produce a polymer product; reforming;
hydrogenation; dehydrogenation; dewaxing, of for example hydrocarbons
to remove straight chain paraffins; absorption, of for example alkyl
aromatic compounds for separating out isomers thereof; alkylation,
of for example aromatic hydrocarbons such as benzene and alkyl benzene,
optionally with propylene to produce cumene or with long chain olefins;
transalkylation, of for example a combination of aromatic and polyalkylaromatic
hydrocarbons; dealkylation; hydrodecyclization; disproportionation,
of for example toluene to make benzene and paraxylene; oligomerization,
of for example straight and branched chain olefin(s); and dehydrocyclization.
[0094] Preferred processes include processes for converting naphtha
to highly aromatic mixtures; converting light olefin(s) to gasoline,
distillates and lubricants; converting oxygenates to olefin(s);
converting light paraffins to olefins and/or aromatics; and converting
unsaturated hydrocarbons (ethylene and/or acetylene) to aldehydes
for conversion into alcohols, acids and esters.
[0095] The most preferred process of the invention is a process
directed to the conversion of 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.
[0096] 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.
[0097] 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.
[0098] Non-limiting examples of oxygenates include methanol, ethanol,
n-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethyl
ether, di-isopropyl ether, formaldehyde, dimethyl carbonate, dimethyl
ketone, acetic acid, and mixtures thereof.
[0099] 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.
[0100] 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.
[0101] The 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 converted in the presence of a molecular sieve catalyst
composition into one or more olefin(s), preferably and predominantly,
ethylene and/or propylene.
[0102] Using the 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.
[0103] 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.
[0104] 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.
[0105] The present process 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.
[0106] Similarly, the present process 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.
[0107] 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
from about 1 hr-I 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 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.
[0108] Where the process is conducted in a fluidized bed, the superficial
gas velocity (SGV) of the feedstock including diluent and reaction
products within the reactor system, and particularly within a riser
reactor(s), is at least 0.1 meter per second (m/sec), such as greater
than 0.5 m/sec, such as greater than 1 m/sec, for example greater
than 2 m/sec, conveniently greater than 3 m/sec, and typically greater
than 4 m/sec. See for example U.S. patent application Ser. No. 09/708753
filed Nov. 8 2000 which is herein incorporated by reference.
[0109] The process of the invention is conveniently conducted as
a fixed bed process, or more typically as a fluidized bed process
(including a turbulent bed process), such as a continuous fluidized
bed process, and particularly a continuous high velocity fluidized
bed process.
[0110] The process can take place in a variety of catalytic reactors
such as hybrid reactors that have a dense bed or fixed bed reaction
zones and/or fast fluidized bed reaction zones coupled together,
circulating fluidized bed reactors, riser reactors, and the like.
Suitable conventional reactor types are described in for example
U.S. Pat. No. 4076796 U.S. Pat. No. 6287522 (dual riser), and
Fluidization Engineering, D. Kunii and O. Levenspiel, Robert E.
Krieger Publishing Company, New York, N.Y. 1977 which are all herein
fully incorporated by reference.
[0111] The preferred reactor types are riser reactors generally
described in Riser Reactor, Fluidization and Fluid-Particle Systems,
pages 48 to 59 F. A. Zenz and D. F. Othmo, Reinhold Publishing
Corporation, New York, 1960 and U.S. Pat. No. 6166282 (fast-fluidized
bed reactor), and U.S. patent application Ser. No. 09/564613 filed
May 4 2000 (multiple riser reactor), which are all herein fully
incorporated by reference.
[0112] In one practical embodiment, the process is conducted as
a fluidized bed process or high velocity fluidized bed process utilizing
a reactor system, a regeneration system and a recovery system.
[0113] In such a process the reactor system conveniently includes
a fluid bed reactor system having a first reaction zone within one
or more riser reactor(s) and a second reaction zone within at least
one disengaging vessel, typically comprising one or more cyclones.
In one embodiment, the one or more riser reactor(s) and disengaging
vessel are contained within a single reactor vessel. Fresh feedstock,
preferably containing one or more oxygenates, optionally with one
or more diluent(s), is fed to the one or more riser reactor(s) into
which a molecular sieve catalyst composition or coked version thereof
is introduced. In one embodiment, prior to being introduced to the
riser reactor(s), the molecular sieve catalyst composition or coked
version thereof is contacted with a liquid, preferably water or
methanol, and/or a gas, for example, an inert gas such as nitrogen.
[0114] In an embodiment, the amount of fresh feedstock fed as a
liquid and/or a vapor to the reactor system is in the range of from
0.1 weight percent to about 85 weight percent, such as from about
1 weight percent to about 75 weight percent, more typically from
about 5 weight percent to about 65 weight percent based on the total
weight of the feedstock including any diluent contained therein.
The liquid and vapor feedstocks may be the same composition, or
may contain varying proportions of the same or different feedstocks
with the same or different diluents.
[0115] The feedstock entering the reactor system is preferably
converted, partially or fully, in the first reactor zone into a
gaseous effluent that enters the disengaging vessel along with the
coked catalyst composition. In the preferred embodiment, cyclone(s)
are provided within the disengaging vessel to separate the coked
catalyst composition from the gaseous effluent containing one or
more olefin(s) within the disengaging vessel. Although cyclones
are preferred, gravity effects within the disengaging vessel can
also be used to separate the catalyst composition from the gaseous
effluent. Other methods for separating the catalyst composition
from the gaseous effluent include the use of plates, caps, elbows,
and the like.
[0116] In one embodiment, the disengaging vessel includes a stripping
zone, typically in a lower portion of the disengaging vessel. In
the stripping zone the coked catalyst composition is contacted with
a gas, preferably one or a combination of steam, methane, carbon
dioxide, carbon monoxide, hydrogen, or an inert gas such as argon,
preferably steam, to recover adsorbed hydrocarbons from the coked
catalyst composition that is then introduced to the regeneration
system.
[0117] The coked catalyst composition is withdrawn from the disengaging
vessel and introduced to the regeneration system. The regeneration
system comprises a regenerator where the coked catalyst composition
is contacted with a regeneration medium, preferably a gas containing
oxygen, under conventional regeneration conditions of temperature,
pressure and residence time.
[0118] Non-limiting examples of suitable regeneration media include
one or more of oxygen, O.sub.3 SO.sub.3 N.sub.2O, NO, NO.sub.2
N.sub.2O.sub.5 air, air diluted with nitrogen or carbon dioxide,
oxygen and water (U.S. Pat. No. 6245703), carbon monoxide and/or
hydrogen. Suitable regeneration conditions are those capable of
burning coke from the coked catalyst composition, preferably to
a level less than 0.5 weight percent based on the total weight of
the coked molecular sieve catalyst composition entering the regeneration
system. For example, the regeneration temperature may be in the
range of from about 200.degree. C. to about 1500.degree. C., such
as from about 300.degree. C. to about 1000.degree. C., for example
from about 450.degree. C. to about 750.degree. C., and conveniently
from about 550.degree. C. to 700.degree. C. The regeneration pressure
maybe in the range of from about 15 psia (103 kpaa) to about 500
psia (3448 kpaa), such as from about 20 psia (138 kPaa) to about
250 psia (1724 kpaa), including from about 25 psia (172 kPaa) to
about 150 psia (1034 kpaa), and conveniently from about 30 psia
(207 kPaa) to about 60 psia (414 kpaa).
[0119] The residence time of the catalyst composition in the regenerator
may be in the range of from about one minute to several hours, such
as from about one minute to 100 minutes, and the volume of oxygen
in the regeneration gas may be in the range of from about 0.01 mole
percent to about 5 mole percent based on the total volume of the
gas.
[0120] The burning of coke in the regeneration step is an exothermic
reaction, and in an embodiment, the temperature within the regeneration
system is controlled by various techniques in the art including
feeding a cooled gas to the regenerator vessel, operated either
in a batch, continuous, or semi-continuous mode, or a combination
thereof. A preferred technique involves withdrawing the regenerated
catalyst composition from the regeneration system and passing it
through a catalyst cooler to form a cooled regenerated catalyst
composition. The catalyst cooler, in an embodiment, is a heat exchanger
that is located either internal or external to the regeneration
system. Other methods for operating a regeneration system are in
disclosed U.S. Pat. No. 6290916 (controlling moisture), which
is herein fully incorporated by reference.
[0121] The regenerated catalyst composition withdrawn from the
regeneration system, preferably from the catalyst cooler, is combined
with a fresh molecular sieve catalyst composition and/or re-circulated
molecular sieve catalyst composition and/or feedstock and/or fresh
gas or liquids, and returned to the riser reactor(s). In one embodiment,
the regenerated catalyst composition withdrawn from the regeneration
system is returned to the riser reactor(s) directly, preferably
after passing through a catalyst cooler. A carrier, such as an inert
gas, feedstock vapor, steam or the like, may be used, semi-continuously
or continuously, to facilitate the introduction of the regenerated
catalyst composition to the reactor system, preferably to the one
or more riser reactor(s).
[0122] By controlling the flow of the regenerated catalyst composition
or cooled regenerated catalyst composition from the regeneration
system to the reactor system, the optimum level of coke on the molecular
sieve catalyst composition entering the reactor is maintained. There
are many techniques for controlling the flow of a catalyst composition
described in Michael Louge, Experimental Techniques, Circulating
Fluidized Beds, Grace, Avidan and Knowlton, eds., Blackie, 1997
(336-337), which is herein incorporated by reference.
[0123] Coke levels on the catalyst composition are measured by
withdrawing the catalyst composition from the conversion process
and determining its carbon content. Typical levels of coke on the
molecular sieve catalyst composition, after regeneration, are in
the range of from 0.01 weight percent to about 15 weight percent,
such as from about 0.1 weight percent to about 10 weight percent,
for example from about 0.2 weight percent to about 5 weight percent,
and conveniently from about 0.3 weight percent to about 2 weight
percent based on the weight of the molecular sieve.
[0124] The gaseous effluent is withdrawn from the disengaging system
and is passed through a recovery system. There are many well known
recovery systems, techniques and sequences that are useful in separating
olefin(s) and purifying olefin(s) from the gaseous effluent. Recovery
systems generally comprise one or more or a combination of various
separation, fractionation and/or distillation towers, columns, splitters,
or trains, reaction systems such as ethylbenzene manufacture (U.S.
Pat. No. 5476978) and other derivative processes such as aldehydes,
ketones and ester manufacture (U.S. Pat. No. 5675041), and other
associated equipment, for example various condensers, heat exchangers,
refrigeration systems or chill trains, compressors, knock-out drums
or pots, pumps, and the like.
[0125] Non-limiting examples of these towers, columns, splitters
or trains used alone or in combination include one or more of a
demethanizer, preferably a high temperature demethanizer, a dethanizer,
a depropanizer, a wash tower often referred to as a caustic wash
tower and/or quench tower, absorbers, adsorbers, membranes, ethylene
(C2) splitter, propylene (C3) splitter and butene (C4) splitter.
[0126] Various recovery systems useful for recovering olefin(s),
such as ethylene, propylene and/or butene, are described in U.S.
Pat. No. 5960643 (secondary rich ethylene stream), U.S. Pat. Nos.
5019143 5452581 and 5082481 (membrane separations), U.S.
Pat. No. 5672197 (pressure dependent adsorbents), U.S. Pat. No.
6069288 (hydrogen removal), U.S. Pat. No. 5904880 (recovered
methanol to hydrogen and carbon dioxide in one step), U.S. Pat.
No. 5927063 (recovered methanol to gas turbine power plant), and
U.S. Pat. No. 6121504 (direct product quench), U.S. Pat. No. 6121503
(high purity olefins without superfractionation), and U.S. Pat.
No. 6293998 (pressure swing adsorption), which are all herein
fully incorporated by reference.
[0127] Other recovery systems that include purification systems,
for example for the purification of olefin(s), are described in
Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, Volume
9 John Wiley & Sons, 1996 pages 249-271 and 894-899 which
is herein incorporated by reference. Purification systems are also
described in for example, U.S. Pat. No. 6271428 (purification
of a diolefin hydrocarbon stream), U.S. Pat. No. 6293999 (separating
propylene from propane), and U.S. patent application Ser. No. 09/689363
filed Oct. 20 2000 (purge stream using hydrating catalyst), which
are herein incorporated by reference.
[0128] Generally accompanying most recovery systems is the production,
generation or accumulation of additional products, by-products and/or
contaminants along with the preferred prime products. The preferred
prime products, the light olefins, such as ethylene and propylene,
are typically purified for use in derivative manufacturing processes
such as polymerization processes. Therefore, in the most preferred
embodiment of the recovery system, the recovery system also includes
a purification system. For example, the light olefin(s) produced
particularly in a MTO process are passed through a purification
system that removes low levels of by-products or contaminants.
[0129] Non-limiting examples of contaminants and by-products include
generally polar compounds such as water, alcohols, carboxylic acids,
ethers, carbon oxides, sulfur compounds such as hydrogen sulfide,
carbonyl sulfides and mercaptans, ammonia and other nitrogen compounds,
arsine, phosphine and chlorides. Other contaminants or by-products
include hydrogen and hydrocarbons such as acetylene, methyl acetylene,
propadiene, butadiene and butyne.
[0130] Typically, in converting one or more oxygenates to olefin(s)
having 2 or 3 carbon atoms, a minor amount hydrocarbons, particularly
olefin(s), having 4 or more carbon atoms is also produced. The amount
of C.sub.4+ hydrocarbons is normally less than 20 weight percent,
such as less than 10 weight percent, for example less than 5 weight
percent, and particularly less than 2 weight percent, based on the
total weight of the effluent gas withdrawn from the process, excluding
water. Typically, therefore the recovery system may include one
or more reaction systems for converting the C.sub.4+ impurities
to useful products.
[0131] Non-limiting examples of such reaction systems are described
in U.S. Pat. No. 5955640 (converting a four carbon product into
butene-1), U.S. Pat. No. 4774375 (isobutane and butene-2 oligomerized
to an alkylate gasoline), U.S. Pat. No. 6049017 (dimerization
of n-butylene), U.S. Pat. Nos. 4287369 and 5763678 (carbonylation
or hydroformulation of higher olefins with carbon dioxide and hydrogen
making carbonyl compounds), U.S. Pat. No. 4542252 (multistage
adiabatic process), U.S. Pat. No. 5634354 (olefin-hydrogen recovery),
and Cosyns, J. et al., Process for Upgrading C3 C4 and C5 Olefinic
Streams, Pet. & Coal, Vol. 37 No. 4 (1995) (dimerizing or oligomerizing
propylene, butylene and pentylene), which are all fully herein incorporated
by reference.
[0132] The preferred light olefin(s) produced by any one of the
processes described above are high purity prime olefin(s) products
that contain a single carbon number olefin in an amount greater
than 80 percent, such as greater than 90 weight percent, such as
greater than 95 weight percent, for example at least about 99 weight
percent, based on the total weight of the olefin.
[0133] In one practical embodiment, the process of the invention
forms part of an integrated process for producing light olefin(s)
from a hydrocarbon feedstock, preferably a gaseous hydrocarbon feedstock,
particularly methane and/or ethane. The first step in the process
is passing the gaseous feedstock, preferably in combination with
a water stream, to a syngas production zone to produce a synthesis
gas (syngas) stream, typically comprising carbon dioxide, carbon
monoxide and hydrogen. Syngas production is well known, and typical
syngas temperatures are in the range of from about 700.degree. C.
to about 1200.degree. C. and syngas pressures are in the range of
from about 2 MPa to about 100 MPa. Synthesis gas streams are produced
from natural gas, petroleum liquids, and carbonaceous materials
such as coal, recycled plastic, municipal waste or any other organic
material. Preferably synthesis gas stream is produced via steam
reforming of natural gas.
[0134] The next step in the process involves contacting the synthesis
gas stream generally with a heterogeneous catalyst, typically a
copper based catalyst, to produce an oxygenate containing stream,
often in combination with water. In one embodiment, the contacting
step is conducted at temperature in the range of from about 150.degree.
C. to about 450.degree. C. and a pressure in the range of from about
5 MPa to about 10 MPa.
[0135] This oxygenate containing stream, or crude methanol, typically
contains the alcohol product and various other components such as
ethers, particularly dimethyl ether, ketones, aldehydes, dissolved
gases such as hydrogen methane, carbon oxide and nitrogen, and fuel
oil. The oxygenate containing stream, crude methanol, in the preferred
embodiment is passed through a well known purification processes,
distillation, separation and fractionation, resulting in a purified
oxygenate containing stream, for example, commercial Grade A and
AA methanol.
[0136] The oxygenate containing stream or purified oxygenate containing
stream, optionally with one or more diluents, can then be used as
a feedstock in a process to produce light olefin(s), such as ethylene
and/or propylene. Non-limiting examples of this integrated p |