Molecular sieve abstract
A catalyst composition that comprises an over flocculated molecular
sieve and a phosphorous compound and, optionally, a non-over flocculated
molecular sieve. A method of preparing a catalyst composition that
comprises mixing an over flocculated molecular sieve and a phosphorous
compound and, optionally, a non-over flocculated molecular sieve.
Molecular sieve claims
1. A catalyst composition comprising an over flocculated molecular
sieve and a phosphorous compound.
2. The catalyst composition of claim 1 wherein the over flocculated
molecular sieve is recovered with a first flocculant.
3. The catalyst composition of claim 1 wherein the phosphorous
compound comprises an acidic phosphorous compound.
4. The catalyst composition of claim 1 wherein the catalyst composition
has an ARI of less than about 1.0 weight %/hour.
5. The catalyst composition of claim 1 wherein the over flocculated
molecular sieve has a debris factor, .PHI., greater than about 0.2.
6. The catalyst composition of claim 1 further comprising a binder,
and optionally a matrix material.
7. The catalyst composition of claim 1 wherein the phosphorus compound
is selected from phosphoric acid, phosphorous acid, polyphosphoric
acid, ammonium dihydrogen phosphate, ammonium hydrogen phosphate,
pyrophosphoric acid, ortho-phosphoric acid, hypophosphorous acid.
8. The catalyst composition of claim 1 or 2 further comprising
a non-over flocculated molecular sieve.
9. The catalyst composition of claim 8 wherein the catalyst composition
has a weight ratio of the non-over flocculated molecular sieve to
the over flocculated molecular sieve of about 1:20 to 20:1.
10. The catalyst composition of claim 8 wherein the non-over flocculated
molecular sieve has a debris factor, .PHI., less than about 0.2.
11. The catalyst composition of claim 2 wherein the first flocculant
has an average molecular weight of about 500 to about 50000000.
12. The catalyst composition of claim 1 wherein the phosphorus
compound is in the range of from about 0.03 wt % to about 20 wt
% P.sub.2O.sub.5 based on the total weight of the molecular sieve(s)
and phosphorous compound comprising the catalyst composition.
13. The catalyst composition of claim 8 wherein the non-over flocculated
molecular sieve is recovered with a second flocculant.
14. The catalyst composition of claim 13 wherein the second flocculant
has an average molecular weight of about 500 to about 50000000.
15. The catalyst composition of claim 1 wherein the over flocculated
molecular sieve is selected from one or more of the group consisting
of: a metalloaluminophosphate, a silicoaluminophosphate, an aluminophosphate,
a CHA framework-type molecular sieve, an AEI framework-type molecular
sieve and a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
16. The catalyst composition of claim 8 wherein the non-over flocculated
molecular sieve is selected from one or more of the group consisting
of: a metalloaluminophosphate, a silicoaluminophosphate, an aluminophosphate,
a CHA framework-type molecular sieve, an AEI framework-type molecular
sieve and a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
17. The catalyst composition of claim 13 wherein the first flocculant
and the second flocculant are the same.
18. A method of preparing a catalyst composition comprising combining
an over flocculated molecular sieve with a phosphorous compound.
19. The method of claim 18 wherein the over flocculated molecular
sieve is recovered with a first flocculent.
20. The method of claim 18 wherein the phosphorous compound comprises
an acidic phosphorous compound.
21. The method of claim 19 wherein the first flocculant has an
average molecular weight of about 500 to about 50000000.
22. The method of claim 18 wherein the over flocculated molecular
sieve has a debris factor, .PHI., greater than about 0.2.
23. The method of claim 18 wherein the catalyst composition has
an ARI of less than about 1.0 weight %/hour.
24. The method of claim 18 wherein the catalyst composition comprises
from 5% to 65% by weight of the over flocculated molecular sieve.
25. The method of claim 18 wherein the phosphorous compound is
selected from phosphoric acid, phosphorous acid, polyphosphoric
acid, ammonium dihydrogen phosphate, ammonium hydrogen phosphate,
pyrophosphoric acid, ortho-phosphoric acid, hypophosphorous acid.
26. The method of claim 18 wherein the phosphorus compound is in
the range of from about 0.03 wt % to about 20 wt % P.sub.2O.sub.5
based on the total weight of the molecular sieve(s) and phosphorous
compound comprising the catalyst composition.
27. The method of claim 18 or 19 further comprising combining a
non-over flocculated molecular sieve.
28. The method of claim 27 wherein the non-over flocculated molecular
sieve is recovered with a second flocculant.
29. The method of claim 28 wherein the second flocculant has an
average molecular weight of about 500 to about 50000000.
30. The method of claim 18 wherein the over flocculated molecular
sieve is selected from one or more of the group consisting of: a
metalloaluminophosphate, a silicoaluminophosphate, an aluminophosphate,
a CHA framework-type molecular sieve, an AEI framework-type molecular
sieve and a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
31. The catalyst composition of claim 27 wherein the non-over flocculated
molecular sieve is selected from one or more of the group consisting
of: a metalloaluminophosphate, a silicoaluminophosphate, an aluminophosphate,
a CHA framework-type molecular sieve, an AEI framework-type molecular
sieve and a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
32. The method of claim 27 wherein the non-over flocculated molecular
sieve has a debris factor, .PHI., less than about 0.2.
33. The method of claim 27 wherein the catalyst composition has
a weight ratio of the over flocculated molecular sieve to the non-over
flocculated molecular sieve of about 1:20 to 20:1.
34. The method of claim 28 wherein the first flocculant and the
second flocculant are the same.
35. The method of claim 27 wherein the catalyst composition comprises
0% to 60% by weight of the non-over flocculated molecular sieve.
36. A process for producing one or more olefin(s), the process
comprising the steps of: (a) introducing a feedstock comprising
one or more oxygenates to a reactor system in the presence of a
molecular sieve catalyst composition comprising: (i) an over flocculated
molecular sieve, and (ii) a phosphorous compound; (b) withdrawing
from the reactor system an effluent stream; and (c) passing the
effluent stream through a recovery system recovering at least the
one or more olefin(s).
37. The process of claim 36 wherein the over flocculated molecular
sieve is recovered with a first flocculant.
38. The process of claim 36 wherein the phosphorous compound comprises
an acidic phosphorous compound.
39. The process of claim 36 wherein the over flocculated molecular
sieve is synthesized from a synthesis mixture comprising a silicon
source, a phosphorous source and an aluminum source, optionally
in the presence of a templating agent.
40. The process of claim 36 wherein the molecular sieve catalyst
composition further comprises a binder, and optionally a matrix
material.
41. The process of claim 37 wherein the first flocculant has an
average molecular weight (MW) in the range of about 500 to about
50000000.
42. The process of claim 36 wherein the over flocculated molecular
sieve is present in an amount of about 5 to 95 wt % based on the
total weight of the molecular sieve(s) and phosphorous compound
comprising the catalyst composition.
43. The process of claim 36 wherein the molecular sieve catalyst
composition has an ARI of less than about 1.0 weight %/hour.
44. The process of claim 36 wherein the over flocculated molecular
sieve has a debris factor, .PHI., greater than about 0.2.
45. The process of claim 36 wherein the over flocculated molecular
sieve is selected from one or more of the group consisting of: a
metalloaluminophosphate, a silicoaluminophosphate, an aluminophosphate,
a CHA framework-type molecular sieve, an AEI framework-type molecular
sieve and a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
46. The process of claim 36 wherein greater than 1000 kg of one
or more olefin(s) is being produced.
47. The process of claim 36 wherein the one or more olefin(s) include
ethylene and propylene.
48. The process of claim 36 wherein the phosphorous compound is
selected from phosphoric acid, phosphorous acid, polyphosphoric
acid, ammonium dihydrogen phosphate, ammonium hydrogen phosphate,
pyrophosphoric acid, ortho-phosphoric acid, hypophosphorous acid.
49. The process of claim 36 wherein the phosphorus compound is
in the range of from about 0.03 wt % to about 20 wt % P.sub.2O.sub.5
based on the total weight of the molecular sieve(s) and phosphorous
compound comprising the catalyst composition.
50. The process of claim 36 or 37 wherein the molecular sieve catalyst
composition further comprises a non-over flocculated molecular sieve.
51. The process of claim 50 wherein the non-over flocculated molecular
sieve is recovered with a second flocculant.
52. The process of claim 51 wherein the second flocculant has an
average molecular weight (MW) in the range of about 500 to about
50000000.
53. The process of claim 50 wherein the non-over flocculated molecular
sieve is present in an amount of about 0 to 90 wt % based on the
total weight of the molecular sieve(s) and phosphorous compound
comprising the catalyst composition.
54. The process of claim 50 wherein the non-over flocculated molecular
sieve is selected from one or more of the group consisting of: a
metalloaluminophosphate, a silicoaluminophosphate, an aluminophosphate,
a CHA framework-type molecular sieve, an AEI framework-type molecular
sieve and a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
55. The process of claim 51 wherein the first flocculant and the
second flocculant are the same.
56. The process of claim 50 wherein the molecular sieve catalyst
composition has a weight ratio of the non-over flocculated molecular
sieve to the over flocculated molecular sieve of about 1:20 to 20:1.
57. The process of claim 36 further comprising the steps of: passing
a hydrocarbon feedstock to a syngas production zone to produce a
synthesis gas stream; and contacting the synthesis gas stream with
a catalyst to form the feedstock comprising one or more oxygenates.
58. The process of claim 36 wherein the process further comprises
the step of: polymerizing the one or more olefin(s) in the presence
of a polymerization catalyst into a polyolefin.
59. The process of claim 57 wherein the process further comprises
the step of: polymerizing the one or more olefin(s) in the presence
of a polymerization catalyst into a polyolefin.
60. The process of claim 57 wherein the feedstock comprising one
or more oxygenates comprises methanol, the one or more olefin(s)
include ethylene and propylene, and the over flocculated molecular
sieve is a silicoaluminophosphate molecular sieve.
61. The process of claim 57 wherein the molecular sieve catalyst
composition further comprises a non-over flocculated molecular sieve.
62. A catalyst slurry comprising: (a) an over flocculated molecular
sieve; (b) a phosphorous compound; (c) a binder; and (d) optionally
a matrix material.
63. The catalyst slurry of claim 62 wherein the phosphorous compound
comprises an acidic phosphorous compound.
64. The catalyst slurry of claim 62 having a viscosity less than
about 10000 cPs at 10 RPM.
65. The catalyst slurry of claim 64 having a viscosity less than
about 7000 cPs at 10 RPM.
66. The catalyst slurry of claim 62 having a solids content greater
than about 40%.
67. The catalyst slurry of claim 62 further comprising a second
flocculated molecular sieve having a slurry viscosity of at least
1000 cPs less than the over flocculated molecular sieve.
68. The catalyst slurry of claim 67 wherein the second flocculated
molecular sieve comprises a non-over flocculated molecular sieve.
69. An activated molecular sieve catalyst composition having an
ARI of less than about 0.60 weight %/hr, said activated molecular
sieve catalyst composition formed by: (a) mixing the catalyst slurry
of claim 62 to form a formulation composition; (b) forming the formulation
composition in a forming unit to form a shaped catalyst; and (c)
calcining the shaped catalyst to form the activated molecular sieve
catalyst composition.
70. The activated molecular sieve catalyst composition of claim
69 wherein the catalyst slurry further comprises a non-over flocculated
molecular sieve.
Molecular sieve description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/648946 filed Jan. 31 2005 U.S. Provisional
Application No. 60/648878 filed Jan. 31 2005 and U.S. Provisional
Application No. 60/650052 filed Feb. 4 2005 the disclosures
of which are fully incorporated herein by reference.
FIELD OF THE INVENTION
[0002] 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 molecular
sieve catalyst composition.
BACKGROUND OF THE INVENTION
[0003] 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.
[0004] The petrochemical industry has known 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.
[0005] 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 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 reactor. The preferred methanol conversion process is generally
referred to as a methanol-to-olefin(s) process (MTO), where an oxygenate,
typically mostly methanol, is converted into primarily ethylene
and/or propylene in the presence of a molecular sieve.
[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). Molecular sieves, such as
zeolites or zeolite-type molecular sieves, carbons and oxides, are
porous solids having pores of different sizes that selectively adsorb
molecules that can enter the pores, and exclude other molecules
that are too large. Examples of molecular sieves useful in converting
an oxygenate into olefin(s) are: 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;
U.S. Pat. No. 4310440 describes producing light olefin(s) from
an alcohol using a crystalline aluminophosphates, often represented
by ALPO.sub.4; and U.S. Pat. No. 4440871 describes silicoaluminophosphate
molecular sieves (SAPO), one of the most useful molecular sieves
for converting methanol into olefin(s).
[0007] 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. Problems
develop in the recovery systems because fines often exit the reactor
in the product containing effluent stream. Catalyst compositions
having a higher resistance to attrition generate fewer fines; this
results in improved process operability, and less catalyst composition
being required for a conversion process, and therefore, lower overall
operating costs.
[0008] It is known that the way in which the molecular sieve catalyst
compositions are made or formulated affects catalyst composition
attrition. Molecular sieve catalyst compositions are formed by combining
a molecular sieve and a matrix material usually in the presence
of a binder. For example, PCT Patent Publication WO 03/000413 A1
published Jan. 3 2003 discloses a low attrition molecular sieve
catalyst composition using a synthesized molecular sieve that has
not been fully dried, or partially dried, in combination in a slurry
with a binder and/or a matrix material. Also, PCT Patent Publication
WO 03/000412 A1 published Jan. 3 2003 discusses a low attrition
molecular sieve catalyst composition produced by controlling the
pH of the slurry away from the isoelectric point of the molecular
sieve. U.S. Pat. No. 6787501 shows making a low attrition molecular
sieve catalyst composition by making a slurry of a synthesized molecular
sieve, a binder, and optionally a matrix material, wherein 90 percent
by volume of the slurry contains particles having a diameter less
than 20 .mu.m. U.S. Patent Application Publication No. U.S. 2003/0181322
published Sep. 25 2003 which is herein fully incorporated by reference,
illustrates making an attrition resistant molecular sieve catalyst
composition by controlling the ratio of a binder to a molecular
sieve. U.S. Pat. No. 6503863 is directed to a method of heat treating
a molecular sieve catalyst composition to remove a portion of the
template used in the synthesis of the molecular sieve. U.S. Pat.
No. 6541415 describes improving the attrition resistance of a
molecular sieve catalyst composition that contains molecular sieve-containing
recycled attrition particles and virgin molecular sieve. U.S. Pat.
No. 6660682 describes the use of a polymeric base to reduce the
amount of templating agent required to produce a particular molecular
sieve.
[0009] It is also known that in typical commercial processes that
flocculants are used in the recovery of synthesized molecular sieves.
These flocculants are known to facilitate the crystal recovery and
to increase the yield of recovery of the synthesized molecular sieve
typically in a large scale commercial process. However, the presence
of a flocculate can affect the catalyst formulation, and in some
cases flocculation can result in the formulation of catalyst compositions
having lower attrition resistance, lower selectivity in various
conversion processes, and high slurry viscosity.
[0010] Although these 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 performance and lower slurry viscosity.
SUMMARY OF THE INVENTION
[0011] This invention generally provides for a method of formulating
a molecular sieve catalyst composition and to its use in a conversion
process for converting a feedstock into one or more olefin(s).
[0012] In one embodiment the invention is directed to a catalyst
composition comprising an over flocculated molecular sieve and a
phosphorous compound, preferably an acidic phosphorous compound,
and, optionally, a non-over flocculated molecular sieve. The above
embodiment can be combined with any one or more of the various embodiments
described below.
[0013] In another embodiment, the invention relates to a catalyst
composition comprising an over flocculated molecular sieve recovered
with a first flocculant, and a phosphorous compound, preferably
an acidic phosphorous compound, and, optionally a non-over flocculated
molecular sieve recovered with a second flocculant. In one embodiment,
the first flocculent has an average molecular weight of about 500
to about 50000000. In another embodiment, the second flocculant
has an average molecular weight of about 300000 to about 30000000.
In one embodiment, the phosphorous compound is selected from, but
not limited to, phosphoric acid, phosphorous acid, polyphosphoric
acid, ammonium dihydrogen phosphate, ammonium hydrogen phosphate,
pyrophosphoric acid, ortho-phosphoric acid, hypophosphorous acid.
[0014] In another embodiment, the invention relates to a method
of preparing a catalyst composition comprising combining an over
flocculated molecular sieve with a phosphorous compound, preferably
an acidic phosphorous compound, and, optionally, with a non-over
flocculated molecular sieve.
[0015] In another embodiment, the invention relates to a process
for producing one or more olefin(s), the process comprising the
steps of (a) introducing a feedstock to a reactor system in the
presence of a molecular sieve catalyst composition comprising (i)
an over flocculated molecular sieve recovered with a first flocculant,
and (ii) a phosphorous compound and, optionally, (iii) a non-over
flocculated molecular sieve recovered with a second flocculant;
(b) withdrawing from the reactor system an effluent stream; and
(c) passing the effluent gas through a recovery system recovering
at least the one or more olefin(s).
[0016] In another embodiment, the invention relates to an integrated
process for making one or more olefin(s), the integrated process
comprising the steps of (a) passing a hydrocarbon feedstock to a
syngas production zone to produce a synthesis gas stream; (b) contacting
the synthesis gas stream with a catalyst to form an oxygenated feedstock;
and (c) converting the oxygenated feedstock into the one or more
olefin(s) in the presence of a molecular sieve catalyst composition,
the molecular sieve catalyst composition comprising (i) an over
flocculated molecular sieve recovered with a first flocculant, and
(ii) a phosphorous compound and, optionally, (iii) a non-over flocculated
molecular sieve recovered with a second flocculant.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
[0017] The invention is directed toward a molecular sieve catalyst
composition, its making, and its use in the conversion of a feedstock
into one or more olefin(s). A formulated molecular sieve catalyst
composition is typically formed from a slurry of the combination
of a molecular sieve, a binder, and optionally, most preferably,
a matrix material. It has been discovered that the presence of an
excess of flocculant, which may result in an over flocculated molecular
sieve, can result in processing difficulties, such as a high viscosity.
This invention is directed toward a catalyst composition and method
of making and using the catalyst composition, that comprises the
over flocculated molecular sieve. A synergistic effect has been
discovered wherein an over flocculated molecular sieve and a phosphorous
compound, for example phosphoric acid, and optionally, a non-over
flocculated molecular sieve are combined to form a slurry that can
exhibit improved properties, e.g., lower slurry viscosity and better
attrition performance when it is formed into shaped particles, e.g.,
spray drying.
Molecular Sieves
[0018] Molecular sieves have various chemical, physical, and framework
characteristics. Molecular sieves have been well classified by the
Structure Commission of the International Zeolite Association (IZA)
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.
For additional information on molecular sieve types, structures
and characteristics, see van Bekkum, et al., Introduction to Zeolite
Science and Practice, Second Completely Revised and Expanded Edition,
Volume 137 Elsevier Science, B.V., Amsterdam, Netherlands (2001),
which is also fully incorporated herein by reference.
[0019] Non-limiting examples of these molecular sieves are 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 AEI, 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 an
intergrowth thereof.
[0020] 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 molecular sieves have 8-, 10- or 12-ring structures
or larger and an average pore size in the range of about 3 .ANG.
to 15 .ANG.. In the most preferred embodiment, the molecular sieves,
preferably SAPO 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..
[0021] Molecular sieves based on silicon, aluminum, and phosphorous,
and metal containing molecular sieves thereof, have been described
in detail in numerous publications including for example, U.S. Pat.
No. 4567029 (MeAPO where Me is Mg, Mn, Zn, or Co), U.S. Pat. No.
4440871 (SAPO), European Patent Application EP-A-0 159 624 (ELAPSO
where El is As, Be, B, Cr, Co, Ga, Ge, Fe, Li, Mg, Mn, Ti or Zn),
U.S. Pat. No. 4554143 (FeAPO), U.S. Pat. Nos. 4822478 4683217
4744885 (FeAPSO), EP-A-0 158 975 and U.S. Pat. No. 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 5098684 (MCM-41), U.S. Pat. No. 5198203
(MCM-48), U.S. Pat. Nos. 5241093 5304363 (MCM-50), U.S. Pat.
Nos. 5493066 5675050 6077498 (ITQ-1), U.S. Pat. No. 6409986
(ITQ-5), U.S. Pat. No. 6419895 (UZM-4), U.S. Pat. No. 6471939
(ITQ-12), U.S. Pat. No. 6471941 (ITQ-13), U.S. Pat. No. 6475463
(SSZ-55), U.S. Pat. No. 6500404 (ITQ-3), U.S. Pat. No. 6500998
(UZM-5 and UZM-6), U.S. Pat. No. 6524551 (MCM-58) and U.S. Pat.
No. 6544495 (SSZ-57), U.S. Pat. No. 6547958 (SSZ-59), U.S. Pat.
No. 6555090 (ITQ-36) and U.S. Pat. No. 6569401 (SSZ-64), 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.
[0022] 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 substituted, preferably metal substituted, ALPO and SAPO molecular
sieves. The most preferred molecular sieves are SAPO molecular sieves,
and metal substituted SAPO molecular sieves.
[0023] 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
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 from 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.
[0024] Synthesis of a molecular sieve, especially a SAPO molecular
sieve, its formulation into a SAPO catalyst, and its use in converting
a hydrocarbon feedstock into olefin(s), is shown in, for example,
U.S. Pat. Nos. 4499327 4677242 4677243 4873390 5095163
5714662 and 6166282 all of which are herein fully incorporated
by reference. Non-limiting examples of SAPO and ALPO molecular sieves
of the invention include one or a combination of SAPO-5 SAPO-8
SAPO-1 SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35
SAPO-36 SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 (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.
[0025] In an embodiment, the molecular sieve is an intergrowth
material having two or more distinct phases of crystalline structures
within one molecular sieve composition. In particular, SAPO intergrowth
molecular sieves are described in the U.S. Pat. No. 6812372 PCT
Publication WO 02/070407 published Sep. 12 2002 and PCT Publication
WO 98/15496 published Apr. 16 1998 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, preferably the molecular sieve
has a greater amount of CHA framework-type to AEI framework-type,
and more preferably the molar ratio of CHA to AEI is greater than
1:1.
Molecular Sieve Synthesis
[0026] Generally, molecular sieves are synthesized by the hydrothermal
crystallization of one or more of a source of aluminum, a source
of phosphorous, a source of silicon, a templating agent, and a metal
containing compound. Typically, a combination of sources of silicon,
aluminum and phosphorous, optionally with one or more templating
agents and/or one or more metal containing compounds, are placed
in a sealed pressure vessel, optionally lined with an inert plastic
such as polytetrafluoroethylene, and heated, under a crystallization
pressure and temperature, at static or stirred conditions, until
a crystalline material is formed in a synthesis mixture. Then, in
a commercial process in particular, one or more flocculant(s) is
added to the synthesis mixture to speed up settling of the crystals
and to achieve phase separation, i.e., a solids-rich phase in the
lower portion of the vessel and a solids-free or solids-lean liquid
layer in the upper portion of the vessel. A portion of the upper
liquid layer is removed, decanted, or reduced in quantity. The remaining
flocculated product containing the crystalline molecular sieve is
then, optionally, contacted with the same or a different fresh liquid,
typically with water, in a washing step, from once to many times
depending on the desired purity of the supernatant, liquid portion,
of the synthesis mixture being removed. It is also optional to repeat
this process by adding in additional flocculant followed by additional
washing steps. Then, the crystallized molecular sieve is recovered
by filtration, centrifugation and/or decanting. Preferably, the
molecular sieve is filtered using a filter that provides for separating
certain crystal sized molecular sieve particles from any remaining
liquid portion that may contain different size molecular sieve crystals.
[0027] In a preferred embodiment the molecular sieves are synthesized
by forming a reaction product or synthesis mixture of a source of
silicon, a source of aluminum, a source of phosphorous and an organic
templating agent, preferably a nitrogen containing organic templating
agent. This particularly preferred embodiment results in the synthesis
of a silicoaluminophosphate crystalline material in a synthesis
mixture. One or more flocculants are added to the synthesis mixture,
and the crystallized molecular sieve is then removed or isolated
by filtration, centrifugation and/or decanting.
[0028] Non-limiting examples of silicon sources include a silicates,
fumed silica, for example, Aerosil-200 available from Degussa Inc.,
New York, N.Y., and CAB-O-SIL M-5 silicon compounds such as tetraalkyl
orthosilicates, for example, tetramethyl orthosilicate (TMOS) and
tetraethylorthosilicate (TEOS), colloidal silicas or aqueous suspensions
thereof, for example Ludox-HS-40 sol available from E.I. du Pont
de Nemours, Wilmington, Del., silicic acid, alkali-metal silicate,
or any combination thereof. The preferred source of silicon is a
silica sol, such as Nalco colloidal silica, available from Nalco
Chemical, Sugarland, Tex.
[0029] Non-limiting examples of aluminum sources include aluminum-containing
compositions such as aluminum alkoxides, for example aluminum isopropoxide,
aluminum phosphate, aluminum hydroxide, sodium aluminate, pseudo-boehmite,
gibbsite and aluminum trichloride, or any combinations thereof.
A preferred source of aluminum is pseudo-boehmite, particularly
when producing a silicoaluminophosphate molecular sieve.
[0030] Non-limiting examples of phosphorous sources, which may
also include aluminum-containing phosphorous compositions, include
phosphorous-containing, inorganic or organic, compositions such
as phosphoric acid, organic phosphates such as triethyl phosphate,
and crystalline or amorphous aluminophosphates such as AlPO.sub.4
phosphorous salts, or combinations thereof. The preferred source
of phosphorous is phosphoric acid, particularly when producing a
silicoaluminophosphate.
[0031] Templating agents are generally compounds that contain elements
of Group VA of the Periodic Table of Elements, particularly nitrogen,
phosphorus, arsenic and antimony, more preferably nitrogen or phosphorous,
and most preferably nitrogen. Typical templating agents of Group
VA of the Periodic Table of elements also contain at least one alkyl
or aryl group, preferably an alkyl or aryl group having from 1 to
10 carbon atoms, and more preferably from 1 to 8 carbon atoms. The
preferred templating agents are nitrogen-containing compounds such
as amines and quaternary ammonium compounds.
[0032] The quaternary ammonium compounds, in one embodiment, are
represented by the general formula R.sub.4N.sup.+, where each R
is hydrogen or a hydrocarbyl or substituted hydrocarbyl group, preferably
an alkyl group or an aryl group having from 1 to 10 carbon atoms.
In one embodiment, the templating agents include a combination of
one or more quaternary ammonium compound(s) and one or more of a
mono-, di- or tri-amine.
[0033] Non-limiting examples of templating agents include tetraalkyl
ammonium compounds including salts thereof such as tetramethyl ammonium
compounds including salts thereof. The preferred templating agent
or template is a tetraethylammonium compound, tetraethyl ammonium
hydroxide (TEAOH) and salts thereof, particularly when producing
a SAPO molecular sieve.
Flocculants
[0034] When commercially recovering any of the molecular sieves
discussed above, typically one or more chemical reagents are added
to the crystallization vessel or synthesis reactor after crystallization
is substantially complete, preferably complete. Optionally, the
synthesis mixture is transferred to another vessel separate from
the reaction vessel or the vessel in which crystallization occurs,
and a flocculant is then added to this other vessel from which the
crystalline molecular sieve is ultimately recovered. These chemical
reagents or flocculants are used to increase the recovery rate of
the molecular sieve crystals and increase the yield of the synthesized
molecular sieve crystals. While not wishing to be bound to any particular
theory, these flocculants act either as (1) a surface charge modifier
that results in the agglomeration of very small particles into larger
aggregates of molecular sieve particles; (2) surface anchors that
bridge many small particles to form aggregates of molecular sieve
particles; or (3) spacers to prevent crystals from packing too closely
that may restrict liquid flow during filtration and washing. The
aggregates of the molecular sieve crystals are then easily recovered
by well known techniques such as filtration or through a filter
press process.
[0035] The flocculant is added to the synthesis mixture after crystallization
has occurred from the combination of one or more of a silicon source,
a phosphorous source, an aluminum source, and a templating agent.
The synthesized molecular sieve is then recovered by filtration,
however, optionally, the synthesized molecular sieve is washed and
additional flocculant is used to further aggregate any remaining
synthesized molecular sieve from the liquid portion of the synthesis
mixture.
[0036] There are many types of flocculants, including both inorganic
and organic flocculants. Inorganic flocculants are typically aluminum
or iron salts that form insoluble hydroxide precipitates in water.
Non-limiting examples such as aluminum sulfate, poly (aluminum chloride),
sodium aluminate, iron (III)-chloride and sulfate, iron (II) sulfate,
and sodium silicate (activated silica). The major classes of organic
flocculants are: (1) nonionic flocculant, for example, polyethylene
oxide, polyacrylamide (PAM), partially hydrolyzed polyacrylamide
(HPAM), and dextran; (2) cationic flocculant, for example, polyethyleneimine
(PEI), polyacrylamide-co-trimethylammonium, ethyl methyl acrylate
chloride (PTAMC), and poly(N-methyl-4-vinylpyridinium iodide); and
(3) anionic flocculant, for example, poly (sodium acrylate), dextran
sulfates, and/or high molecular weight ligninsulfonates prepared
by a condensation reaction of formaldehyde with ligninsulfonates,
and polyacrylamide. Where the synthesis mixture includes the presence
of water, it is preferable that the flocculant used is water soluble.
Additional information on flocculation is discussed in G. J. Fleer
and J. H. M. Scheutjens, Coagulation and Flocculation Theory and
Applications, ed. by B. Dobias, pp. 209-263 Marcel Dekker, New
York, 1993 which is fully incorporated by reference.
[0037] The flocculant may be added to the synthesis mixture after
crystallization in an amount of 0.01 to 5 wt % flocculant based
on expected solid molecular sieve product yield, crystal size, and
presence of nano particles and ionicity of the medium, preferably
between 0.02 to 2 wt % flocculant based on expected solid molecular
sieve product yield, crystal size, and presence of nano particles
and ionicity of the medium, more preferably from 0.03 to 1.5 wt
% based on expected solid molecular sieve product yield, crystal
size, and presence of nano particles and ionicity of the medium.
It is preferable that the product slurry and/or flocculant are diluted
to obtain a volume of product slurry to volume of flocculant of
between 1:1 and 10:1. Good mixing between the product slurry and
the flocculant is also preferred. One can recover the flocculated
sieve starting from the total mixture by centrifugation or filtration
or one can allow the mixture to settle, decant the liquid, re-slurry
with water, eventually repeatedly decant and re-slurry, and finally
recover by centrifugation or filtration. The settling of the sieve
can take from minutes to days; however, the settling can be accelerated
by adding additional flocculant or use of high molecular weight
flocculant. The flocculant is typically added to the slurry at room
temperature, and is preferably added as a solution. Should a solid
flocculant be used then it is preferable that a substantially homogeneous
flocculant solution or suspension or emulsion is prepared by dissolving
or dispersing the solid flocculant in a medium.
[0038] In one embodiment, a flocculant has an average molecular
weight about 500 to about 50000000 preferably about 10000 to
about 20000000 more preferably about 20000 to about 15000000
and most preferably about 50000 to about 10000000.
[0039] The flocculant may be in solution, an emulsion, or a micro-emulsion,
preferably an aqueous solution, emulsion, or micro-emulsion. Further,
the flocculant in the aqueous solution may be diluted with water.
Without being bound to any particular theory, it has been found
that dilution of the molecular sieve slurry, preferably one recovered
using a flocculant, prevents or reduces dissolution of the molecular
sieve in the slurry. This benefit provides for a further improvement
in yield, and allows for the slurry to be stored for an extended
period of time.
[0040] A synthesis mixture comprising a molecular sieve and a flocculant
has a pH depending on the composition of the molecular sieve, excess
amount of template, degree of crystallization. In a preferred embodiment,
the synthesis mixture has a pH in the range of from 2 to 10 preferably
in the range of from 2.5 to 9.5 and most preferably in the range
of from 3 to 9. Generally, the synthesis mixture is sealed in a
vessel and heated, preferably under autogenous pressure, to a temperature
in the range of about 80.degree. C. to about 250.degree. C., and
more preferably about 150.degree. C. to about 180.degree. C. The
time required to form the crystalline molecular sieve is typically
from immediately up to several weeks, the duration of which is usually
dependent on the temperature; the higher the temperature the shorter
the duration. Typically, the crystalline molecular sieve product
is formed, usually in a slurry state, and then a flocculant is introduced
to this slurry, the synthesis mixture. The crystalline molecular
sieve is then recovered by any standard technique well known in
the art, for example centrifugation or filtration. Alternatively,
in another embodiment, the flocculant is introduced into the synthesis
mixture directly.
[0041] In one embodiment, the isolated or separated crystalline
product, the synthesized molecular sieve, is washed, typically using
a liquid such as water, from one to many times, or in a semi-continuous
or continuous way for variable lengths of time. The washed crystalline
product is then optionally dried, preferably in air, more preferably
in flowing air, to a level such that the resulting, partially dried
or dried crystalline product or synthesized molecular sieve has
a LOI in the range of about 0.5 weight percent to about 80 weight
percent, preferably the range is about greater than 1 weight percent
to about 75 weight percent, more preferably about 5 weight percent
to about 70 weight percent, even more preferably about 8 to about
65 weight percent, and most preferably about 10 weight percent to
about 60 weight percent. This moisture containing crystalline product,
synthesized molecular sieve or wet filtercake, is then used below
in the formulation of the molecular sieve catalyst composition of
the invention.
[0042] The amount of flocculant introduced to the reactor, or crystallization
vessel, depends on the quantity of molecular sieve being recovered,
the type of molecular sieve, the pH of the synthesis mixture, the
size of the molecular sieve crystals, etc. In one embodiment, the
amount of molecular sieve recovered is the range of about 50 kg
to about 20000 kg or greater, preferably in the range of from 100
kg to about 20000 kg, more preferably about 150 kg to about 20000
kg, and most preferably about 250 kg to about 20000 kg. In another
embodiment, the reactor vessel is capable of synthesizing an amount
of molecular sieve in one batch or at one time in the range of about
50 kg to about 20000 kg or greater, preferably greater than about
100 kg to about 20000 kg, more preferably about 150 kg to about
20000 kg, and most preferably about 250 kg to about 20000 kg.
[0043] In one embodiment of the present invention, an over flocculated
molecular sieve and a phosphorous compound, preferably an acidic
phosphorous compound, and, optionally, a non-over flocculated molecular
sieve are combined to form a catalyst composition. In order to determine
the extent of flocculation of a molecular sieve product recovered
with a flocculation process, the following analytical method is
followed by preparing a formulated slurry using the flocculated
molecular sieve, which includes, but is not limited to, molecular
sieves based on silicon, aluminum, and phosphorous; metal containing
molecular sieves; and zeolites. The viscosity of the slurry is measured
using a Brookfield DV-II+Pro Viscometer (Brookfield Instrument Laboratories
Inc., Middleboro, Mass.) using a #6 spindle at 10 RPM shear rate.
The measurement is carried out at temperatures of 23-24.degree.
C. The viscometer is first calibrated with calibration standards
having viscosities of 500 cPs, 1000 cPs, and 3000 cPs before taking
a measurement of the slurry samples. These calibration standards
are certified and are from Brookfield Instrument Laboratories Inc.,
Middleboro, Mass. The over-flocculated molecular sieve slurry, made
according to the following procedure, has a viscosity at about 7000
cPs or higher, while a non-over-flocculated molecular sieve slurry,
made according to the following procedure, has a viscosity below
7000 cPs.
[0044] A determination of the flocculation conditions of a sample
of molecular sieve is made as follows. The slurry sample having
a solids content of 45%, of which 45% being a molecular sieve, 13.5%
alumina binder derived from aluminum chlorohydrite (ACH), and 41.5%
kaolin clay is prepared by the following procedure. To make 1000
grams of formulated slurry: (1) add 244 grams of an aluminum chlorohydrite
(ACH) solution from Reheis Inc., Berkeley Heights, N.J. (LOI: 75.1%)
to 224.5 grams of de-ionized water and mix using a Yamato Model
2100 homogenizer (Yamato Scientific America Inc., Orangeburg, N.Y.)
at 700 RPM for 5 minutes; (2) add 310 grams of flocculated molecular
sieve and mix using Yamato mixer at 700 RPM for 10 minutes; then
mix using a Silverson L4RT-A high-shear mixer (from Silverson Machines
Inc., East Longmeadow, Mass.) at 6000 RPM for 3 minutes; (3) add
221.5 grams of APS Ultrafine clay from Engelhard Corporation, Gordon,
Ga. (LOI: 15.69%) while mixing using Yamato mixer at 700 RPM for
10 minutes, then mix using a Silverson L4RT-A in-line mixer at 7500
RPM for 60 passes at a flow rate of 1500 g/min. The slurry is left
to equilibrate at room temperature to 23-24.degree. C. then the
viscosity is measured. A molecular sieve that gives a slurry with
a viscosity of about 7000 cPs or higher prepared according to the
procedure described above is defined herewith as an over-flocculated
molecular sieve, and a molecular sieve that gives a slurry viscosity
of less than 7000 cPs is defined herewith as a non-over flocculated
molecular sieve. A non-over flocculated molecular sieve includes,
but is not limited to, a molecular sieve that has been recovered
without the use of a flocculant.
[0045] For micro-crystalline materials recovered from a flocculation
process, there are some debris deposited on the surface of the micro-crystalline
materials. The debris is defined as material that is smaller in
size and having a different composition than that of the micro-crystalline
product. One way to express the amount of debris on a crystalline
material is defined as surface coverage factor (.PHI.), or debris
factor, which is the fraction of the crystalline external surface
covered by debris. An over flocculated molecular sieve, as used
herein, may also have a debris factor, .PHI., greater than 0.2.
An over flocculated molecular sieve may also give a spray dried
product having an ARI greater than 1 wt. %/hr. A non-over flocculated
molecular sieve, as used herein, may also have a debris factor,
.PHI., less than 0.2 preferably less than 0.1. A non-over flocculated
molecular sieve may also give a spray dried product having an ARI
less than 1 wt. %/hr, more preferably less than 0.5 wt. %/hr. ARI,
or Attrition Rate Index, is discussed further below.
[0046] In one embodiment of the present invention, the catalyst
composition comprises an over flocculated molecular sieve is recovered
with a first flocculant and a phosphorus compound, preferably an
acidic phosphorous compound, and, optionally, a non-over flocculated
molecular sieve is recovered with a second flocculant. The first
flocculant and the second flocculant have an average molecular weight
of about 500 to about 50000000 preferably about 10000 to about
20000000 more preferably about 20000 to about 15000000 most
preferably about 30000 to about 10000000. The amount of first
flocculant used to recover the over flocculated molecular sieve
is about 50 to about 50000 ppm, preferably about 100 to about 30000
ppm, more preferably about 200 to about 20000 ppm. The amount of
second flocculant used to recover the non-over flocculated molecular
sieve is about 500 to about 50000 ppm, preferably about 800 to
about 30000 ppm, more preferably about 1000 to about 10000 ppm.
The first flocculant and the second flocculant may be the same.
[0047] In one embodiment of the present invention, the catalyst
composition comprises about 5 wt % to about 95 wt % of an over flocculated
molecular sieve, preferably about 10 wt % to about 90 wt % of an
over flocculated molecular sieve, more preferably about 15 wt %
to about 85 wt % of an over flocculated molecular sieve, most preferably
about 20 wt % to about 80 wt % of an over flocculated molecular
sieve. In one embodiment of the present invention, the catalyst
composition comprises a phosphorous compound expressed in terms
of P.sub.2O.sub.5 added during formulation in the range of about
0.03 wt % to about 20 wt % P.sub.2O.sub.5 preferably about 0.1
wt % to about 15 wt % P.sub.2O.sub.5 more preferably about 0.2
wt % to about 12 wt % P.sub.2O.sub.5 most preferably about 0.3
wt % to about 10 wt % P.sub.2O.sub.5. In one embodiment of the present
invention, the catalyst composition comprises about 0 wt % to about
94.97 wt % of a non-over flocculated molecular sieve, preferably
about 5 wt % to about 94.9 wt % of a non-over flocculated molecular
sieve, more preferably about 10 wt % to about 90 wt % of a non-over
flocculated molecular sieve, even more preferably about 15 wt %
to about 85 wt % of a non-over flocculated molecular sieve, most
preferably about 20 wt % to about 80 wt % of a non-over flocculated
molecular sieve. The weight % are based on total weight of the molecular
sieve(s) and phosphorous compound comprising the catalyst composition.
[0048] In one embodiment of the present invention, the catalyst
composition has a weight ratio of the non-over flocculated molecular
sieve to the over flocculated molecular sieve of about 1:20 to 20:1;
preferably about 1:10 to 10:1; more preferably about 1:5 to 5:1.
[0049] In an embodiment of the present invention, the catalyst
composition comprises about 5 wt % to about 100 wt % of an over
flocculated molecular sieve, preferably about 10 wt % to about 95
wt % of an over flocculated molecular sieve, more preferably about
15 wt % to about 90 wt % of an over flocculated molecular sieve,
yet more preferably about 20 wt % to about 85 wt %, most preferably
about 25 wt % to about 80 wt % of an over flocculated molecular
sieve, wherein the total weight percent is based on the total weight
of the molecular sieve(s). In an embodiment of the present invention,
the catalyst composition comprises about 0 wt % to about 95 wt %
of a non-over flocculated molecular sieve, preferably about 5 wt
% to about 90 wt % of a non-over flocculated molecular sieve, more
preferably about 10 wt % to about 85 wt % of a non-over flocculated
molecular sieve, even more preferably about 15 wt % to about 80
wt % of a non-over flocculated molecular sieve, most preferably
about 20 wt % to about 75 wt % of a non-over flocculated molecular
sieve, wherein the total weight percent is based on the total weight
of the molecular sieve(s).
Method for Making Molecular Sieve Catalyst Compositions
[0050] Once the molecular sieve is synthesized and recovered as
described above, depending on the requirements of the particular
conversion process, the molecular sieve is then formulated into
a molecular sieve catalyst composition, particularly for commercial
use. The molecular sieves synthesized above are made or formulated
into molecular sieve catalyst compositions by combining the recovered
molecular sieves, with a binder, and optionally, but preferably,
with a matrix material to form a formulated molecular sieve catalyst
composition. It has been found that when thermally treating a synthesized
molecular sieve having been recovered in the presence of a flocculant,
prior to formulation, thermal treatment can maintain or improve
the formulated molecular sieve catalyst composition's resistance
to attrition in various conversion processes.
[0051] This formulated catalyst composition is formed into useful
shape and sized particles by well-known techniques such as spray
drying, pelletizing, extrusion, and the like, spray drying being
the most preferred. It is also preferred that after spray drying
for example that the formulated molecular sieve catalyst composition
is then calcined.
Binder
[0052] There are many different binders that are useful in forming
the molecular sieve catalyst composition. Non-limiting examples
of binders that are useful alone or in combination include various
types of hydrated alumina, silicas, and/or other inorganic oxide
sol. One preferred alumina containing sol is aluminum chlorhydrate.
The inorganic oxide sol acts like glue binding the synthesized molecular
sieves and other materials such as the matrix together, particularly
after thermal treatment. Upon heating, the inorganic oxide sol,
preferably having a low viscosity, is converted into an inorganic
oxide component. For example, an alumina sol will convert to an
aluminum oxide following heat treatment.
[0053] Aluminum chlorhydrate, a hydroxylated aluminum based sol
containing a chloride counter ion, has the general formula of Al.sub.mO.sub.n(OH).sub.oCl.sub.p.x(H.sub.2O)
wherein m is 1 to 20 n is 1 to 8 o is 5 to 40 p is 2 to 15 and
x is 0 to 30. In one embodiment, the binder is Al.sub.13O.sub.4(OH).sub.24Cl.sub.7.12(H.sub.2O)
as is described in G. M. Wolterman, et al., Stud. Surf Sci. and
Catal., 76 pages 105-144 (1993), which is herein incorporated by
reference. In another embodiment, the binders are alumina sols,
predominantly comprising aluminum oxide, optionally including some
silicon. In yet another embodiment, the binders are peptized alumina
made by treating alumina hydrates such as pseudobohemite, with an
acid, preferably an acid that does not contain a halogen, to prepare
sols or aluminum ion solutions. Non-limiting examples of commercially
available colloidal alumina sols include Nalco 8676 available from
Nalco Chemical Co., Naperville, Ill., and Nyacol AL20DW, available
from Nyacol Nano Technologies, Inc., Ashland, Mass.
[0054] In one embodiment, the weight ratio of the binder to the
molecular sieve is in the range of about 0.1 to 0.5 more preferably
in the range of from 0.11 to 0.48 even more preferably from 0.12
to about 0.45 yet even more preferably from 0.13 to less than 0.45
and most preferably in the range of from 0.15 to about 0.4. See
for example U.S. Patent Application Publication No. U.S. 2003/0181322
published Sep. 25 2003 which is herein fully incorporated by reference.
Matrix Material
[0055] The synthesized molecular sieves described above, in a preferred
embodiment, is combined with a binder and 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.
[0056] 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. These natural clays
include sabbentonites and those kaolins known as, for example, Dixie,
McNamee, Georgia and Florida clays. In one embodiment, the matrix
material, preferably any of the clays, are subjected to well known
modification processes such as calcination and/or acid treatment
and/or chemical treatment. In one preferred embodiment, the matrix
material is kaolin, particularly kaolin having an average particle
size of about 0.1 .mu.m to about 0.6 .mu.m with a d.sub.90 particle
size of less than about 10 .mu.m. Binder may also function as a
matrix material. Where the binder functions as a matrix material,
a second matrix material may also be added.
[0057] Upon combining the over flocculated molecular sieve, phosphorous
compound, optionally a non-over flocculated molecular sieve, and
the binder, with, optionally, a matrix material, in a liquid to
form a slurry, mixing, preferably rigorous mixing, is needed to
produce a substantially homogeneous mixture containing the flocculated
molecular sieve. Non-limiting examples of suitable liquids include
one or a combination of water, alcohol, ketones, aldehydes, and/or
esters. The most preferred liquid is water. In one embodiment, the
slurry is high shear or bead milled for a period of time sufficient
to produce the desired slurry texture, particle size, and/or particle
size distribution.
[0058] The liquid containing the over flocculated molecular sieve,
phosphorous compound, optionally the non-over flocculated molecular
sieve, and binder, and optionally the matrix material, are in the
same or different liquid, and are combined in any order, together,
simultaneously, sequentially, or a combination thereof. In the preferred
embodiment, the same liquid, preferably water is used.
Solids Content
[0059] The molecular sieve catalyst composition in one embodiment
is made by preparing a slurry containing a molecular sieve, a binder,
and, optionally while preferably, a matrix material. The solids
content of the preferred slurry includes about 20% to about 80%
by weight of the molecular sieve, preferably about 25% to about
65% by weight of the molecular sieve, more preferably about 30%
to about 50% by weight molecular sieve, about 5% to about 20%, preferably
about 8% to about 15%, by weight of the binder, and about 30% to
about 80%, preferably about 40% to about 60%, by weight of the matrix
material.
[0060] In another embodiment, the solids content in a slurry comprising
a molecular sieve, a binder, and optionally a matrix material, and
a liquid medium is in the range of about 40 weight percent to about
80 weight percent, more preferably in the range of from 40.5 weight
percent to about 70 weight percent, even more preferably in the
range of from 41 weight percent to 60 weight percent, still even
more preferably about 41.5 weight percent to about 59 weight percent,
yet even more preferably in the range of from 42 weight percent
to about 58 weight percent, and most preferably in the range of
from 42.5 weight percent to about 57.5 weight percent.
[0061] The molecular sieve catalyst composition particles contains
some water, templating agent or other liquid components, therefore,
the weight percents that describe the solid content in the slurry
are preferably expressed in terms exclusive of the amount of water,
templating agent and removable components upon calcination at elevated
temperature. The most preferred condition for measuring solids content
is on a calcined basis as, for example, measured by the LOI procedure
discussed below. On a calcined basis, the solid content in the slurry,
more specifically, the molecular sieve catalyst composition particles
in the slurry, are about 20 percent by weight to 80 percent by weight
molecular sieve, 5 percent by weight to 20 percent by weight binder,
and about 0 percent by weight to 80 percent by weight matrix material.
See for example U.S. Pat. No. 6787501 which is herein fully incorporated
by reference.
[0062] In another embodiment, the over flocculated molecular sieve
and phosphorous compound, and optionally the non-over flocculated
molecular sieve, are combined with a binder and/or a matrix material
forming a slurry such that the pH of the slurry is above or below
the isoelectric point (IEP) of the molecular sieve. Preferably the
slurry comprises the molecular sieve, the binder and the matrix
material and has a pH different from, above or below, preferably
below, the IEP of the molecular sieve, the binder and the matrix
material. In an embodiment, the pH of the slurry is in the range
of from 2 to 7 preferably from 2.3 to 6.2; the IEP of the molecular
sieve is in the range of about 2.5 to less than 7 preferably about
3.0 to 6.5; the IEP of the binder is greater than 10; and the IEP
of the matrix material is less than about 2. See PCT Patent Publication
WO 03/000412 A1 published Jan. 3 2003 which is herein fully incorporated
by reference.
[0063] As the slurry is mixed, particle size reduction is achieved.
It is preferable that these particles are small and have a desired
size distribution such that the d.sub.90 of these particles is less
than 20 .mu.m, preferably less than 15 .mu.m, more preferably less
than 10 .mu.m, and most preferably about 7 .mu.m. The d.sub.90 for
purposes of this patent application and appended claims means that
90 percent by volume of the particles in the slurry have a particle
diameter lower than the d.sub.90 value. For the purposes of this
definition, the particle size distribution used to define the d.sub.90
is measured using well known laser scattering techniques using a
Honeywell Microtrac Model S3000 particle size analyzer from Microtrac,
Inc., Largo, Fla.
[0064] In an embodiment, the invention relates to a catalyst slurry
that comprises (a) an over flocculated molecular sieve; (b) a phosphorous
compound, preferably an acidic phosphorous compound; (c) a binder;
and (d) optionally a matrix material. In another embodiment of the
present invention, the catalyst slurry has a viscosity less than
about 10000 cPs at 10 RPM, preferably less than about 7000 cPs
at 10 RPM. In another embodiment of the present invention, the catalyst
slurry has a solids content greater than about 40%. In another embodiment,
the catalyst slurry further comprises a second flocculated molecular
sieve having a slurry viscosity of at least 1000 cPs less than
the at least one over flocculated molecular sieve. In an embodiment,
the invention relates to a catalyst slurry wherein the second flocculated
molecular sieve comprises a non-over flocculated molecular sieve.
In another embodiment of the present invention, an activated molecular
sieve catalyst composition that has an ARI of less than about 1.0
weight %/hr, preferably less than 0.60 weight %/hr., preferably
less than 0.50 weight %/hr., is formed by: (a) mixing the catalyst
slurry to form a formulation composition; (b) forming the formulation
composition in a forming unit to form a shaped catalyst; and (c)
calcining the shaped catalyst to form the activated molecular sieve
catalyst composition.
[0065] In one embodiment, the slurry of the over flocculated molecular
sieve, phosphorous compound, optionally the non-over flocculated
molecular sieve, binder and optionally the matrix material is mixed
or milled to achieve a sufficiently uniform slurry of particles
of the molecular sieve catalyst composition to form a formulation
composition that is then fed to a forming unit that produces the
molecular sieve catalyst composition or formulated molecular sieve
catalyst composition. In a preferred embodiment, the forming unit
is a spray dryer. Typically, the forming unit is maintained at a
temperature sufficient to remove most of the liquid from the slurry,
and from the resulting molecular sieve catalyst composition. The
resulting catalyst composition when formed in this way takes the
form of microspheres.
[0066] When a spray dryer is used as the forming unit, typically,
any one or a combination of the slurries described above, more particularly
a slurry of the over flocculated molecular sieve, phosphorous compound,
optionally the non-over flocculated molecular sieve, binder, and
optionally matrix material is co-fed to the spray dryer with a drying
gas with an average inlet temperature ranging from 200.degree. C.
to 550.degree. C., and a combined outlet temperature ranging from
70.degree. C. to about 225.degree. C. In an embodiment, the average
diameter of the spray dried formed catalyst composition is about
40 .mu.m to about 300 .mu.m, preferably about 45 .mu.m to about
250 .mu.m, more preferably about 50 .mu.m to about 200 .mu.m, and
most preferably about 55 .mu.m to about 120 .mu.m.
[0067] 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 psia to 1000 psia (690 kPaa to 6895
kPaa). 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. 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 controllable by
varying the slurry feed properties and conditions of atomization,
such as nozzle size, atomization medium, pressure drop, and flow
rate.
[0068] Other methods for forming a molecular sieve catalyst composition
are described in U.S. Pat. No. 6509290 (spray drying using a recycled
molecular sieve catalyst composition), which is herein incorporated
by reference.
[0069] In a preferred embodiment, once the molecular sieve catalyst
composition is formed, to further harden and/or activate the formed
catalyst composition, the spray dried molecular sieve catalyst composition
or formulated molecular sieve catalyst composition is calcined.
Typical calcination temperatures are in the range of about 500.degree.
C. to about 800.degree. C., and preferably 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. Calcination time is typically
dependent on the degree of hardening of the molecular sieve catalyst
composition and is in the range of about 15 minutes to about 20
hours at a temperature in the range of from 500.degree. C. to 700.degree.
C.
[0070] In one embodiment, the molecular sieve catalyst composition
or formulated molecular sieve catalyst composition has an ARI less
than 10 weight percent per hour, preferably less than 5 weight percent
per hour, more preferably less than 2 weight percent per hour, and
most preferably less than 1 weight percent per hour. ARI was calculated
as discussed below.
Process for Using the Molecular Sieve Catalyst Compositions
[0071] The molecular sieve 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
cumeme or with long chain olefins; transalkylation, of for example
a combination of aromatic and polyalkylaromatic hydrocarbons; dealkylation;
hydrodecylization; disproportionation, of for example toluene to
make benzene and paraxylene; oligomerization, of for example straight
and branched chain olefin(s); and dehydrocyclization.
[0072] Preferred processes are conversion processes including naphtha
to highly aromatic mixtures; light olefin(s) to gasoline, distillates
and lubricants; oxygenates to olefin(s); light paraffins to olefins
and/or aromatics; and unsaturated hydrocarbons (ethylene and/or
acetylene) to aldehydes for conversion into alcohols, acids and
esters. The most preferred process of the invention is a process
directed to the conversion of a feedstock comprising one or more
oxygenates to one or more olefin(s).
[0073] The molecular sieve catalyst compositions described above
are particularly useful in conversion processes of different feedstock.
Typically, the feedstock contains one or more aliphatic-containing
compounds that include alcohols, amines, carbonyl compounds for
example aldehydes, ketones and carboxylic acids, ethers, halides,
mercaptans, sulfides, and the like, and mixtures thereof. The aliphatic
moiety of the aliphatic-containing compounds typically contains
from 1 to about 50 carbon atoms, preferably from 1 to 20 carbon
atoms, more preferably from 1 to 10 carbon atoms, and most preferably
from 1 to 4 carbon atoms.
[0074] 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, alkyl-amines such as methyl amine, 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.
[0075] In an 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.
[0076] 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. 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.
[0077] 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) or olefin monomer(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 ethylene and/or propylene.
Non-limiting examples of olefin monomer(s) include ethylene, propylene,
butene-1 pentene-1 4-methyl-pentene-1 hexene-1 octene-1 and
decene-1 preferably ethylene, propylene, butene-1 pentene-14-methyl-pentene-1
hexene-1 octene-1 and isomers thereof. Other olefin monomer(s)
include unsaturated monomers, diolefins having 4 to 18 carbon atoms,
conjugated or nonconjugated dienes, polyenes, vinyl monomers and
cyclic olefins.
[0078] In the most preferred embodiment, the feedstock, preferably
of one or more oxygenates, is converted in the presence of a molecular
sieve catalyst composition of the invention into olefin(s) having
2 to 6 carbons atoms, preferably 2 to 4 carbon atoms. Most preferably,
the olefin(s), alone or combination, are converted from a feedstock
containing an oxygenate, preferably an alcohol, most preferably
methanol, to the preferred olefin(s) ethylene and/or propylene.
[0079] The are many processes used to convert feedstock into olefin(s)
including various cracking processes such as steam cracking, thermal
regenerative cracking, fluidized bed cracking, fluid catalytic cracking,
deep catalytic cracking, and visbreaking. The most preferred process
is generally referred to as gas-to-olefins (GTO) or alternatively,
oxygenate-to-olefins (OTO) or methanol-to-olefins (MTO). In a MTO
or an OTO process, typically 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, often referred
to as light olefin(s).
[0080] The feedstock, in one embodiment, contains one or more diluent(s),
typically used to reduce the concentration of the feedstock, and
are generally non-reactive to the feedstock or molecular sieve catalyst
composition. 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.
[0081] The process for converting a feedstock, especially a feedstock
containing one or more oxygenates, in the presence of a molecular
sieve catalyst composition of the invention, is carried out in a
reaction process in a reactor, where the process is a fixed bed
process, a fluidized bed process (includes a turbulent bed process),
preferably a continuous fluidized bed process, and most preferably
a continuous high velocity fluidized bed process.
[0082] The reaction processes 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. The preferred reactor type
are riser reactors generally described in Riser Reactor, Fluidization
and Fluid-Particle Systems, pages 48 to 59 F. A. Zenz and D. F.
Othmer, 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.
[0083] In the preferred embodiment, a fluidized bed process or
high velocity fluidized bed process includes a reactor system, a
regeneration system and a recovery system.
Reactor System
[0084] The reactor system preferably is 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,
preferably comprising one or more cyclones. In one embodiment, the
one or more riser reactor(s) and disengaging vessel is 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) in which a molecular
sieve catalyst composition or coked version thereof is introduced.
In one embodiment, the molecular sieve catalyst composition or coked
version thereof is contacted with a liquid or gas, or combination
thereof, prior to being introduced to the riser reactor(s), preferably
the liquid is water or methanol, and the gas is an inert gas such
as nitrogen.
[0085] 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 a
coked or further coked molecular sieve catalyst composition. In
the preferred embodiment, cyclone(s) within the disengaging vessel
are designed to separate the molecular sieve catalyst composition,
preferably a coked or further coked molecular sieve catalyst composition,
from the gaseous effluent containing one or more olefin(s) within
the disengaging zone. Cyclones are preferred, however, gravity effects
within the disengaging vessel will also separate the catalyst compositions
from the gaseous effluent. Other methods for separating the catalyst
compositions from the gaseous effluent include the use of plates,
caps, elbows, and the like.
[0086] In one embodiment of the disengaging system, the disengaging
system includes a disengaging vessel, typically a lower portion
of the disengaging vessel is a stripping zone. In the stripping
zone the coked molecular sieve 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
molecular sieve catalyst composition that is then introduced to
the regeneration system. In another embodiment, the stripping zone
is in a separate vessel from the disengaging vessel.
[0087] The conversion temperature employed in the conversion process,
specifically within the reactor system, is in the range of about
200.degree. C. to about 1000.degree. C., preferably about 250.degree.
C. to about 800.degree. C., more preferably about 250.degree. C.
to about 750.degree. C., yet more preferably about 300.degree. C.
to about 650.degree. C., yet even more preferably about 350.degree.
C. to about 600.degree. C., and most preferably about 350.degree.
C. to about 550.degree. C.
[0088] The conversion pressure employed in the conversion process,
specifically within the reactor system, varies over a wide range
including autogenous pressure. The conversion pressure is based
on the partial pressure of the feedstock exclusive of any diluent
therein. Typically the conversion pressure employed in the process
is in the range of about 0.1 kPaa to about 5 MPaa, preferably about
5 kPaa to about 1 MPaa, and most preferably about 20 kPaa to about
500 kPaa.
[0089] The weight hourly space velocity (WHSV), particularly in
a process for converting a feedstock containing one or more oxygenates
in the presence of a molecular sieve catalyst composition within
a reaction zone, is defined as the total weight of the feedstock
excluding any diluents to the reaction zone per hour per weight
of molecular sieve in the molecular sieve catalyst composition in
the reaction zone. The WHSV is maintained at a level sufficient
to keep the catalyst composition in a fluidized state within a reactor.
Typically, the WHSV is in the range of about 1 hr.sup.-1 to about
5000 hr.sup.-1 preferably about 2 hr.sup.-1 to about 3000 hr.sup.-1
more preferably about 5 hr.sup.-1 to about 1500 hr.sup.-1 and most
preferably about 10 hr.sup.-1 to about 1000 hr.sup.-1. In one preferred
embodiment, the WHSV is greater than 20 hr.sup.-1 preferably the
WHSV for conversion of a feedstock containing methanol and dimethyl
ether is in the range of about 20 hr.sup.-1 to about 300 hr.sup.-1.
[0090] The superficial gas velocity (SGV) of the feedstock including
diluent and reaction products within the reactor system is preferably
sufficient to fluidize the molecular sieve catalyst composition
within a reaction zone in the reactor. The SGV in the process, particularly
within the reactor system, more particularly within the riser reactor(s),
is at least 0.1 meter per second (m/sec), preferably greater than
0.5 m/sec, more preferably greater than 1 m/sec, even more preferably
greater than 2 m/sec, yet even more preferably greater than 3 m/sec,
and most preferably greater than 4 m/sec. See for example U.S. Pat.
No. 6552240 which is herein incorporated by reference. Other
processes for converting an oxygenate to olefin(s) are described
in U.S. Pat. No. 5952538 (WHSV of at least 20 hr.sup.-1 and a
Temperature Corrected Normalized Methane Selectivity (TCNMS) of
less than 0.016), EP-0 642 485 B1 (WHSV is from 0.01 hr.sup.-1 to
about 100 hr.sup.-1 at a temperature of about 350.degree. C. to
550.degree. C.), and PCT WO 01/23500 published Apr. 5 2001 (propane
reduction at an average catalyst feedstock exposure of at least
1.0), which are all herein fully incorporated by reference.
[0091] The coked molecular sieve catalyst composition is withdrawn
from the disengaging vessel, preferably by one or more cyclones(s),
and introduced to the regeneration system.
Regeneration System
[0092] The regeneration system comprises a regenerator where the
coked catalyst composition is contacted with a regeneration medium,
preferably a gas containing oxygen, under general regeneration conditions
of temperature, pressure and residence time. Non-limiting examples
of the regeneration medium 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. The 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. The coked molecular sieve catalyst composition
withdrawn from the regenerator forms a regenerated molecular sieve
catalyst composition. By controlling the flow of the regenerated
molecular sieve catalyst composition or cooled regenerated molecular
sieve 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 molecular sieve 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.
[0093] The regeneration temperature is in the range of about 200.degree.
C. to about 1500.degree. C., preferably about 300.degree. C. to
about 1000.degree. C., more preferably about 450.degree. C. to about
750.degree. C., and most preferably about 550.degree. C. to 700.degree.
C. The regeneration pressure is in the range of about 15 psia (103
kPaa) to about 500 psia (3448 kPaa), preferably about 20 psia (138
kPaa) to about 250 psia (1724 kPaa), more preferably about 25 psia
(172 kPaa) to about 150 psia (1034 kPaa), and most preferably about
30 psia (207 kPaa) to about 60 psia (414 kPaa). The preferred residence
time of the molecular sieve catalyst composition in the regenerator
is in the range of about one minute to several hours, most preferably
about one minute to 100 minutes, and the preferred volume of oxygen
in the gas is in the range of about 0.01 mole percent to about 5
mole percent based on the total volume of the gas.
[0094] Other regeneration processes are described in U.S. Pat.
No. 6023005 (coke levels on regenerated catalyst), U.S. Pat. No.
6245703 (fresh molecular sieve added to regenerator) and U.S.
Pat. No. 6290916 (controlling moisture), U.S. Pat. No. 6613950
(cooled regenerated catalyst returned to regenerator), U.S. Pat.
No. 6441262 (regenerated catalyst contacted with alcohol), and
PCT WO 00/49106 published Aug. 24 2000 (cooled regenerated catalyst
contacted with by-products), which are all herein fully incorporated
by reference.
[0095] The gaseous effluent is withdrawn from the disengaging system
and is passed through a recovery system.
Recovery System
[0096] 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 a 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. 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, preferably a wet 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,
butene (C4) splitter, and the like.
[0097] Various recovery systems useful for recovering predominately
olefin(s), preferably prime or light 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.
[0098] In particular with a conversion process of oxygenates into
olefin(s) utilizing a molecular sieve catalyst composition the resulting
effluent gas typically comprises a majority of ethylene and/or propylene
and a minor amount of four carbon and higher carbon number products
and other by-products, excluding water. In one embodiment, high
purity ethylene and/or high purity propylene is produced by the
process of the invention at a rate greater than 4500 kg per day,
preferably greater than 100000 kg per day, more preferably greater
than 500000 kg per day, even more preferably greater than 1000000
kg per day, yet even more preferably greater than 1500000 kg per
day, still even more preferably greater than 2000000 kg per day,
and most preferably greater than 2500000 kg per day.
[0099] 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 to remove various non-limiting examples of
contaminants and by-products including, but not limited to, generally
polar compounds such as water, alcohols, carboxylic acids, ethers,
carbon oxides, ammonia and other nitrogen compounds, chlorides,
hydrogen and hydrocarbons such as acetylene, methyl acetylene, propadiene,
butadiene and butyne.
[0100] 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. Pat. No. 6593506 (purge stream
using hydrating catalyst), which is herein incorporated by reference.
[0101] Included in the recovery systems of the invention are reaction
systems for converting the products contained within the effluent
gas withdrawn from the reactor or converting those products produced
as a result of the recovery system utilized. Suitable well known
reaction systems as part of the recovery system primarily take lower
value products such as the C.sub.4 hydrocarbons, butene-1 and butene-2
and convert them to higher value products. Non-limiting examples
of these types of reaction systems include 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 C.sub.3 C.sub.4 and C.sub.5 Olefinic
Streams, Pet. & Coal, Vol. 37 No. 4 (1995) (dimerizing or oligomerizing
propylene, butylene and pentylene), which are all herein fully incorporated
by reference.
[0102] Other conversion processes, in particular, a conversion
process of an oxygenate to one or more olefin(s) in the presence
of a molecular sieve catalyst composition, especially where the
molecular sieve is synthesized from a silicon-, phosphorous-, and
alumina-source, include those described in for example: U.S. Pat.
No. 6121503 (making plastic with an olefin product having a paraffin
to olefin weight ratio less than or equal to 0.05), U.S. Pat. No.
6187983 (electromagnetic energy to reaction system), PCT WO 99/18055
publishes Apr. 15 1999 (heavy hydrocarbon in effluent gas fed to
another reactor) PCT WO 01/60770 published Aug. 23 2001 and U.S.
Pat. No. 6441261 (high pressure), U.S. patent application Ser.
No. 09/507838 filed Feb. 22 2000 (staged feedstock injection),
and U.S. Pat. No. 6518475 (acetone co-fed), which are all herein
fully incorporated by reference.
Integrated Processes
[0103] In an embodiment, an integrated process is directed to producing
light olefin(s) from a hydrocarbon feedstock, preferably a hydrocarbon
gas feedstock, more preferably 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. Syngas production is
well known, and typical syngas temperatures are in the range of
about 700.degree. C. to about 1200.degree. C. and syngas pressures
are in the range of 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. Generally, a heterogeneous catalyst,
typically a copper based catalyst, is contacted with a synthesis
gas stream, typically carbon dioxide and carbon monoxide and hydrogen
to produce an alcohol, preferably methanol, often in combination
with water. In one embodiment, the synthesis gas stream at a synthesis
temperature in the range of about 150.degree. C. to about 450.degree.
C. and at a synthesis pressure in the range of about 5 MPa to about
10 MPa is passed through a carbon oxide conversion zone to produce
an oxygenate containing stream.
[0104] 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 fusel
oil. The oxygenate containing stream, crude methanol, in the preferred
embodiment is passed through well known purification processes,
distillation, separation and fractionation, resulting in a purified
oxygenate containing stream, for example, commercial Grade A and
AA methanol. The oxygenate containing stream or purified oxygenate
containing stream, optionally with one or more diluents, is contacted
with one or more molecular sieve catalyst compositions described
above in any one of the processes described above to produce a variety
of prime products, particularly light olefin(s), ethylene and/or
propylene. Non-limiting examples of this integrated process is described
in EP-B-0 933 345 which is herein fully incorporated by reference.
In another more fully integrated process, optionally with the integrated
processes described above, olefin(s) produced are directed to, in
one embodiment, one or more polymerization processes for producing
various polyolefins. (See for example U.S. patent application Ser.
No. 09/615376 filed Jul. 13 2000 which is herein fully incorporated
by reference.)
Light Olefin Usage
[0105] The light olefin products, especially the ethylene and the
propylene, are useful in polymerization processes that include solution,
gas phase, slurry phase and high pressure processes, or a combinations
thereof. Particularly preferred is a gas phase or a slurry phase
polymerization of one or more olefin(s) at least one of which is
ethylene or propylene. These polymerization processes utilize a
polymerization catalyst that can include any one or a combination
of the molecular sieve catalysts discussed above, however, the preferred
polymerization catalysts are those Ziegler-Natta, Phillips-type,
metallocene, metallocene-type and advanced polymerization catalysts,
and mixtures thereof. The polymers produced by the polymerization
processes described above include linear low density polyethylene,
elastomers, plastomers, high density polyethylene, low density polyethylene,
polypropylene and polypropylene copolymers. The propylene based
polymers produced by the polymerization processes include atactic
polypropylene, isotactic polypropylene, syndiotactic polypropylene,
and propylene random, block or impact copolymers.
[0106] In an embodiment, the integrated process comprises a polymerizing
process of one or more olefin(s) in the presence of a polymerization
catalyst system in a polymerization reactor to produce one or more
polymer products, wherein the one or more olefin(s) having been
made by converting an alcohol, particularly methanol, using a molecular
sieve catalyst composition. The preferred polymerization process
is a gas phase polymerization process and at least one of the olefins(s)
is either ethylene or propylene, and preferably the polymerization
catalyst system is a supported metallocene catalyst system. In this
embodiment, the supported metallocene catalyst system comprises
a support, a metallocene or metallocene-type compound and an activator,
preferably the activator is a non-coordinating anion or alumoxane,
or combination thereof, and most preferably the activator is alumoxane.
[0107] In addition to polyolefins, numerous other olefin derived
products are formed from the olefin(s) recovered by any one of the
processes described above, particularly the conversion processes,
more particularly the GTO process or MTO process. These include,
but are not limited to, aldehydes, alcohols, acetic acid, linear
alpha olefins, vinyl acetate, ethylene dicholoride and vinyl chloride,
ethylbenzene, ethylene oxide, cumene, isopropyl alcohol, acrolein,
allyl chloride, propylene oxide, acrylic acid, ethylene-propylene
rubbers, and acrylonitrile, and trimers and dimers of ethylene,
propylene or butylenes.
EXAMPLES
Test Methods
[0108] Determination of the percentage of liquid or liquid medium
and the percentage of template for purposes of this patent specification
and appended claims uses a Thermal Gravimetric Analysis (TGA) technique
as follows: An amount of a molecular sieve material, the sample,
is loaded into a sample pan of a Cahn TG-121 Microbalance, available
from Cahn Instrument, Inc., Cerritos, Calif. During the TGA technique,
a flow of 114 cc/min (STP) air was used. The sample is then heated
from 25.degree. C. to 180.degree. C. at 30.degree. C./min, held
at 180.degree. C. for 3 hours or until the weight of this sample
becomes constant. The weight loss is defined as the Loss on Drying
(LOD) and represents the fraction of the original sample that is
principally water or other liquid medium. Subsequently, the sample
is heated at 30.degree. C./min from 180.degree. C. to 650.degree.
C. and held at 650.degree. C. for 2 hours. This second loss in weight
is considered to be due to removing the template contained in the
sieve crystals. The sum of these two losses relative to the initial
sample weight is defined as the Loss-On-Ignition (LOI).
[0109] 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. ARI is measured
by adding 6.0 g of catalyst composition having a particle size distribution
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