Molecular sieve abstract
A catalyst composition that comprises a non-over flocculated molecular
sieve and an over flocculated molecular sieve. A method of preparing
a catalyst composition that comprises combining a non-over flocculated
molecular sieve and an over flocculated molecular sieve.
Molecular sieve claims
1. A catalyst composition comprising a non-over flocculated molecular
sieve and an over flocculated molecular sieve.
2. The catalyst composition of claim 1 wherein the catalyst composition
has an ARI of less than about 1.0 weight %/hour.
3. The catalyst composition of claim 1 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.
4. The catalyst composition of claim 1 wherein the non-over flocculated
molecular sieve has a debris factor, .PHI., less than about 0.2.
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 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.
8. 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.
9. The catalyst composition of claim 1 wherein: the non-over flocculated
molecular sieve is recovered with a first flocculant, and the over
flocculated molecular sieve is recovered with a second flocculant.
10. The catalyst composition of claim 9 wherein the first flocculant
has an average molecular weight of about 500 to about 50000000.
11. The catalyst composition of claim 9 wherein the second flocculant
has an average molecular weight of about 500 to about 50000000.
12. The catalyst composition of claim 9 wherein the first flocculant
and the second flocculant are the same.
13. A method of preparing a catalyst composition comprising combining
a non-over flocculated molecular sieve and an over flocculated molecular
sieve.
14. The method of claim 13 further comprising combining a binder
and optionally a matrix material.
15. The method of claim 13 wherein: the non-over flocculated molecular
sieve is recovered with a first flocculant, and the over flocculated
molecular sieve is recovered with a second flocculent.
16. The method of claim 15 wherein the first flocculant has an
average molecular weight of about 500 to about 50000000.
17. The method of claim 15 wherein the second flocculant has an
average molecular weight of about 500 to about 50000000.
18. The method of claim 15 wherein the first flocculant and the
second flocculant are the same.
19. The method of claim 13 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.
20. The method of claim 13 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.
21. The method of claim 13 wherein the catalyst composition has
an ARI of less than about 1.0 weight %/hour.
22. The method of claim 13 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.
23. The method of claim 13 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 sieves comprising the catalyst composition.
24. The method of claim 23 wherein the non-over flocculated molecular
sieve is present in an amount of about 5 to 95 wt % based on the
total weight of the molecular sieves comprising the catalyst composition.
25. 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) a non-over
flocculated molecular sieve, and (ii) an over flocculated molecular
sieve; (b) withdrawing from the reactor system an effluent stream;
and (c) passing the effluent stream through a recovery system recovering
the one or more olefin(s).
26. The process of claim 25 wherein: the non-over flocculated molecular
sieve is recovered with a first flocculant, and the over flocculated
molecular sieve is recovered with a second flocculant.
27. The process of claim 25 wherein the non-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.
28. The process of claim 25 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.
29. The process of claim 25 wherein the molecular sieve catalyst
composition further comprises a binder and optionally a matrix material.
30. The process of claim 26 wherein the first flocculant has an
average molecular weight (MW) in the range of about 500 to about
50000000.
31. The process of claim 26 wherein the second flocculant has an
average molecular weight (MW) in the range of about 500 to about
50000000.
32. The process of claim 25 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 sieves comprising the catalyst composition.
33. The process of claim 32 wherein the non-over flocculated molecular
sieve is present in an amount of about 5 to 95 wt % based on the
total weight of the molecular sieves comprising the catalyst composition.
34. The process of claim 26 wherein the first flocculant and the
second flocculant are the same.
35. The process of claim 25 wherein the molecular sieve catalyst
composition has an ARI of less than about 1.0 weight %/hour.
36. The process of claim 25 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.
37. The process of claim 25 wherein the non-over flocculated molecular
sieve has a debris factor, .PHI., less than about 0.2.
38. The process of claim 25 wherein the over flocculated molecular
sieve has a debris factor, .PHI., greater than about 0.2.
39. The process of claim 25 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.
40. The process of claim 25 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.
41. The process of claim 25 wherein greater than 1000 kg of one
or more olefin(s) is being produced.
42. The process of claim 25 wherein the one or more olefin(s) include
ethylene and propylene.
43. The process of claim 25 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.
44. The process of claim 25 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.
45. The process of claim 43 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.
46. The process of claim 43 wherein the feedstock comprising one
or more oxygenates comprises methanol, the one or more olefin(s)
include ethylene and propylene, and the non-over flocculated and
over flocculated molecular sieves are silicoaluminophosphate molecular
sieves.
47. A catalyst slurry comprising: (a) at least one over flocculated
molecular sieve; (b) a second flocculated molecular sieve having
a slurry viscosity of at least 1000 cPs less than the at least
one over flocculated molecular sieve; (c) a binder; and (d) optionally
a matrix material.
48. The catalyst slurry of claim 47 wherein the second flocculated
molecular sieve comprises a non-over flocculated molecular sieve.
49. The catalyst slurry of claim 47 having a viscosity less than
about 10000 cPs at 10 RPM.
50. The catalyst slurry of claim 49 having a viscosity less than
about 7000 cPs at 10 RPM.
51. The catalyst slurry of claim 47 having a solids content greater
than about 40%.
52. An activated molecular sieve catalyst composition having an
ARI of less than about 1.0 weight %/hr, said activated molecular
sieve catalyst composition formed by: (a) mixing the catalyst slurry
of claim 47 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.
Molecular sieve description
FIELD OF THE INVENTION
[0001] The present invention relates to a molecular sieve catalyst
composition, to a method of making or forming the molecular sieve
catalyst composition, and to a conversion process using the catalyst
composition.
BACKGROUND OF THE INVENTION
[0002] Olefins are traditionally produced from petroleum feedstock
by catalytic or steam cracking processes. These cracking processes,
especially steam cracking, produce light olefin(s) such as ethylene
and/or propylene from a variety of hydrocarbon feedstock. Ethylene
and propylene are important commodity petrochemicals useful in a
variety of processes for making plastics and other chemical compounds.
[0003] The petrochemical industry has known for some time that
oxygenates, especially alcohols, are convertible into light olefin(s).
There are numerous technologies available for producing oxygenates
including fermentation or reaction of synthesis gas derived from
natural gas, petroleum liquids, carbonaceous materials including
coal, recycled plastics, municipal waste or any other organic material.
Generally, the production of synthesis gas involves a combustion
reaction of natural gas, mostly methane, and an oxygen source into
hydrogen, carbon monoxide and/or carbon dioxide. Syngas production
processes are well known, and include conventional steam reforming,
autothermal reforming, or a combination thereof.
[0004] Methanol, the preferred alcohol for light olefin production,
is typically synthesized from the catalytic reaction of hydrogen,
carbon monoxide and/or carbon dioxide in a methanol reactor in the
presence of a heterogeneous catalyst. For example, in one synthesis
process methanol is produced using a copper/zinc oxide catalyst
in a water-cooled tubular methanol reactor. The preferred methanol
conversion process is generally referred to as a methanol-to-olefin(s)
process, where methanol is converted to primarily ethylene and/or
propylene in the presence of a molecular sieve.
[0005] Molecular sieves are porous solids having pores of different
sizes such as zeolites or zeolite-type molecular sieves, carbons
and oxides. The most commercially useful molecular sieves for the
petroleum and petrochemical industries are known as zeolites, for
example aluminosilicate molecular sieves. Zeolites in general have
a one-, two- or three-dimensional crystalline pore structure having
uniformly sized pores of molecular dimensions that selectively adsorb
molecules that can enter the pores, and exclude those molecules
that are too large.
[0006] There are many different types of molecular sieves well
known to convert a feedstock, especially an oxygenate containing
feedstock, into one or more olefin(s). For example, U.S. Pat. No.
5367100 describes the use of a well known zeolite, ZSM-5 to convert
methanol into olefin(s); U.S. Pat. No. 4062905 discusses the conversion
of methanol and other oxygenates to ethylene and propylene using
crystalline aluminosilicate zeolites, for example Zeolite T, ZK5
erionite and chabazite; U.S. Pat. No. 4079095 describes the use
of ZSM-34 to convert methanol to hydrocarbon products such as ethylene
and propylene; and U.S. Pat. No. 4310440 describes producing light
olefin(s) from an alcohol using a crystalline aluminophosphates,
often represented by ALPO.sub.4.
[0007] One of the most useful molecular sieves for converting methanol
to olefin(s) is a silicoaluminophosphate molecular sieves. Silicoaluminophosphate
(SAPO) molecular sieves contain a three-dimensional microporous
crystalline framework structure of [SiO.sub.2], [AlO.sub.2] and
[PO.sub.2] corner sharing tetrahedral units. SAPO synthesis is described
in U.S. Pat. No. 4440871 which is herein fully incorporated by
reference. SAPO is generally synthesized by the hydrothermal crystallization
of a reaction mixture of silicon-, aluminum- and phosphorus-sources
and at least one templating agent. Synthesis of a SAPO molecular
sieve, its formulation into a SAPO catalyst, and its use in converting
a hydrocarbon feedstock into olefin(s), particularly where the feedstock
is methanol, is shown in U.S. Pat. Nos. 4499327 4677242 4677243
4873390 5095163 5714662 and 6166282 all of which are
herein fully incorporated by reference.
[0008] Typically, molecular sieves are formed into molecular sieve
catalyst compositions to improve their durability in commercial
conversion processes. The collisions within a commercial process
between catalyst composition particles themselves, the reactor walls,
and other reactor systems cause the particles to breakdown into
smaller particles called fines. The physical breakdown of the molecular
sieve catalyst composition particles is known as attrition. Pines
often exit the reactor in the effluent stream resulting in problems
in recovery systems. Catalyst compositions having a higher resistance
to attrition generate fewer fines, less catalyst composition is
required for conversion, and longer life times result in lower operating
costs.
[0009] Molecular sieve catalyst compositions are formed by combining
a molecular sieve and a matrix material usually in the presence
of a binder. The purpose of the binder is hold the matrix material,
often a clay, to the molecular sieve. The use of binders and matrix
materials in the formation of molecular sieve catalyst compositions
is well known for a variety of commercial processes. It is also
known that the way in which the molecular sieve catalyst composition
is made or formulated affects catalyst composition attrition.
[0010] Example of methods of making catalyst compositions include:
U.S. Pat. No. 5126298 discusses a method for making a cracking
catalyst having high attrition resistance by combining two different
clay particles in separate slurries with a zeolite slurry and a
source of phosphorous, and spray drying a mixture of the slurries
having a pH below 3; U.S. Pat. Nos. 4987110 and 5298153 relates
to a catalytic cracking process using a spray dried attrition resistant
catalyst containing greater than 25 weight percent molecular sieve
dispersed in a clay matrix with a synthetic silica-alumina component;
U.S. Pat. Nos. 5194412 and 5286369 discloses forming a catalytic
cracking catalyst of a molecular sieve and a crystalline aluminum
phosphate binder having a surface area less than 20 m.sup.2/g and
a total pore volume less than 0.1 cc/g; U.S. Pat. No. 4542118
relates to forming a particulate inorganic oxide composite of a
zeolite and aluminum chlorhydrol that is reacted with ammonia to
form a cohesive binder; U.S. Pat. No. 6153552 claims a method
of making a catalyst, by drying a slurry of a SAPO molecular sieve,
an inorganic oxide sol, and an external phosphorous source; U.S.
Pat. No. 5110776 illustrates the formation of a zeolite containing
catalytic catalyst by modifying the zeolite with a phosphate containing
solution; U.S. Pat. No. 5348643 relates to spray drying a zeolite
slurry with a clay and source of phosphorous at a pH of below 3;
U.S. Pat. No. 4973792 is directed to a conversion process using
a formulated molecular sieve catalyst composition, however, there
is no mention of the solid content of the slurry spray dried, nor
any discussion of the amount of liquid medium in the SAPO-34 added
to the slurry; U.S. patent application Ser. No. 09/891674 filed
Jun. 25 2001 discusses a method for steaming a molecular sieve
to remove halogen; U.S. Pat. No. 5248647 illustrates spray drying
a SAPO-34 molecular sieve admixed with kaolin and a silica sol;
U.S. Pat. No. 5346875 discloses a method for making a catalytic
cracking catalyst by matching the isoelectric point of each component
of the framework structure to the pH of the inorganic oxide sol;
Maurer, et al, Aggregation and Peptization Behavior of Zeolite Crystals
in Sols and Suspensions, Ind. Eng. Chem. Vol. 40 pages 2573-2579
2001 discusses zeolite aggregation at or near the isoelectric point;
PCT Publication WO 99/21651 describes making a catalyst by drying
a mixture of an alumina sol and a SAPO molecular sieve; PCT Publication
WO 02/05950 describes making a catalyst composition of a molecular
sieve containing attrition particles with fresh molecular sieve;
and WO 02/05952 discloses a crystalline metallo-aluminophosphate
molecular sieve and a matrix material of an inorganic oxide binder
and filler where the molecular sieve is present in an amount less
than 40 weight percent relative to the catalyst weight and a preferable
weight ratio of the binder to molecular sieve close to 1.
[0011] 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 resistance and commercially desirable operability
and cost advantages.
SUMMARY OF THE INVENTION
[0012] This invention provides for a method of making or formulating
a molecular sieve catalyst composition and to its use in a conversion
process for converting a feedstock into one or more olefin(s).
[0013] In one embodiment the invention is directed to a method
for formulating a molecular sieve catalyst composition, the method
comprising the steps of: (a) providing a synthesized molecular sieve
having not been fully dried, or alternatively, partially dried;
(b) making a slurry of the synthesized molecular sieve, a binder,
and optionally a matrix material; and (c) forming the slurry to
produce a formulated molecular sieve catalyst composition. In a
preferred embodiment, the synthesized molecular sieve is synthesized
from the combination of at least two of the group consisting of
a silicon source, a phosphorous source and an aluminum source, optionally
in the presence of a templating agent. In a most preferred embodiment,
the slurry in step (c) is formed by spray drying. In another preferred
embodiment, the weight ratio of binder to molecular sieve in the
slurry in step (c) is greater than 0.12 to about 0.45. In yet another
embodiment, the slurry contains a solid content of from about 20
percent to about 80 percent based on the total weight of the slurry
on a calcined basis. The solids include the molecular sieve, the
binder, and optionally the matrix material. In still another embodiment
of any of the above, after step (b) and prior to step (c) the slurry
is mixed until 90 percent by volume of the slurry contains particles
having a diameter less than 20 .mu.m, preferably less than 10 .mu.m.
[0014] In an embodiment, the invention is directed to a method
for formulating a molecular sieve catalyst composition, the method
comprising the steps of: (a) providing a synthesized molecular sieve
in the presence of a liquid medium; (b) introducing a binder, and
optionally adding the same or different liquid medium and/or a matrix
material; and (c) mixing and forming the slurry to produce a formulated
molecular sieve catalyst composition, wherein the synthesized molecular
sieve is not fully dried or partially dried prior to step (a). In
a preferred embodiment, the liquid medium is water, and the amount
of liquid medium prior to drying is in the range of from 20 weight
percent to 70 weight percent based on the total weight of the molecular
sieve and liquid medium. Preferably the synthesized molecular sieve
is a silicoaluminophosphate, an aluminophosphate and/or a chabazite
(CHA) framework-type molecular sieve. In yet another embodiment,
the weight ratio of the binder to the molecular sieve is greater
than 0.12 to less than 0.45 wherein the binder is an alumina and
the molecular sieve is a silicoaluminophosphate. In yet another
embodiment, the slurry contains a solid content of from about 30
percent to about 50 percent, preferably about 35 percent to about
50 percent, and more preferably from about 40 to about 50 percent,
based on the total weight of the slurry on a calcined basis. In
still yet another embodiment of any of the above, the slurry is
mixed until at least 90 percent by volume of solid particles in
the slurry have a diameter less than 20 .mu.m, preferably less than
10 .mu.m.
[0015] In another preferred embodiment, the invention relates to
a method for making a formulated molecular sieve catalyst composition,
the method comprising the steps of: (a) synthesizing with a liquid
medium a molecular sieve from the combination of at least two of
the group consisting of a silicon source, a phosphorous source and
an aluminum source, optionally in the presence of a templating agent,
to form a slurry; (b) removing the molecular sieve from the slurry;
(c) drying the molecular sieve to a level in the range of from 20
weight percent to 80 weight percent liquid medium based on the total
weight of the liquid medium and the molecular sieve; (d) combining
the molecular sieve with a binder, and optionally adding the same
or different liquid medium and/or with a matrix material, to form
a formulation composition; and (e) drying and/or forming the formulation
composition to form the formulated molecular sieve catalyst composition.
In a preferred embodiment, in step (c) the slurry is dried to a
level in the range of from 30 weight percent to 70 weight percent
liquid medium, preferably water, based on the total weight of the
liquid medium, preferably water, and the molecular sieve. In another
embodiment, in step (e) the formulation composition is formed by
spray drying the formulation composition to form the formulated
molecular sieve catalyst composition. In a further embodiment, prior
to step (c) and/or (e), the slurry and/or the formulation composition
is washed in a liquid, preferably the liquid is the same as the
liquid medium, and most preferably the liquid is water. In another
preferred embodiment, the method further comprises a step (f) in
which the formulated molecular sieve catalyst composition is calcined.
In another embodiment, the weight ratio of the binder to the molecular
sieve is in the range of greater than 0.1 to less than 0.5 preferably
in the range greater than 0.12 to 0.45 and most preferably in the
range of from 0.13 to about 0.40. In yet another embodiment of any
of the above, slurry contains a solid content of from about 35 percent
to about 50 percent based on the total weight of the slurry on a
calcined basis. In still another embodiment of any of the above,
the combining of the slurry comprises the step of mixing the slurry
comprising a liquid and solid particles until at least 90 percent
by volume of the solid particles have a diameter less than 20 .mu.m,
preferably less than 10 .mu.m.
[0016] In yet another embodiment, the invention is directed to
a process for producing olefin(s) in the presence of any of the
above formulated molecular sieve catalyst compositions. In particular,
the process involves producing olefin(s) in a process for converting
a feedstock, preferably a feedstock containing an oxygenate, more
preferably a feedstock containing an alcohol, and most preferably
a feedstock containing methanol in the presence of one or more of
the formulated molecular sieve catalyst compositions discussed above.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
[0017] The invention is directed toward a molecular sieve catalyst
composition, its making, and to its use in the conversion of a hydrocarbon
feedstock into one or more olefin(s). The molecular sieve catalyst
composition is made or formed from the combination of a molecular
sieve, a binder, and optionally, most preferably, a matrix material.
Typically in the art a dried or calcined molecular sieve is combined
with a binder and/or matrix material. However, it has been surprisingly
found that using a molecular sieve that has not been fully dried
that is combined with a binder and/or a matrix material an improved
formulated molecular sieve catalyst composition is made. In particular,
using a partially dried molecular sieve with a binder and/or a matrix
material results in making a formulated molecular sieve catalyst
composition having improved resistance to attrition. This results
in an improved catalyst composition more resistant to breaking apart
in a conversion processes, and therefore having an extended catalyst
life. Additionally, not calcining the molecular sieve after its
synthesis also reduces the cost associated with the synthesis and
also improves its susceptibility to deactivation especially in its
storage or transportation.
[0018] It has been known in the art that varying the weight percent
of the molecular sieve in the total catalyst composition is important.
However, it has also been surprisingly found that the weight ratio
of the binder to the molecular sieve, especially where the molecular
sieve is partially dried as discussed above, is important to making
or forming an attrition resistance catalyst composition. Without
being bound to any particular theory it is believed that when the
weight ratio of the binder to molecular sieve is too high then the
surface area of the catalyst composition decreases resulting in
lower conversion rates, and when the weight ratio of the binder
to molecular sieve is too low then the catalyst composition will
break apart into fines more easily.
[0019] It has also been discovered that in addition to the dryness
of the molecular sieve and the binder to molecular sieve ratio in
the formulation of a molecular sieve catalyst composition, that
the amount of solids present in a slurry of the molecular sieve
and the binder, optionally including a matrix material, used in
a spray drying process for example is important. When the solids
content of the slurry is too low or too high the attrition resistance
properties of the molecular sieve catalyst composition is reduced.
The amount of solids in combination with the other discoveries discussed
above also determines the level of attrition resistance a particular
molecular sieve catalyst composition has.
Molecular Sieves and Catalysts Thereof
[0020] Molecular sieves have various chemical and physical, framework,
characteristics. Molecular sieves have been well classified by the
Structure Commission of the International Zeolite Association according
to the rules of the IUPAC Commission on Zeolite Nomenclature. A
framework-type describes the connectivity, topology, of the tetrahedrally
coordinated atoms constituting the framework, and making an abstraction
of the specific properties for those materials. Framework-type zeolite
and zeolite-type molecular sieves for which a structure has been
established, are assigned a three letter code and are described
in the Atlas of Zeolite Framework Types, 5th edition, Elsevier,
London, England (2001), which is herein fully incorporated by reference.
[0021] 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, EMI, FAU, and substituted forms thereof. Other
molecular sieves include ANA, BEA, CFI, CLO, DON, GIS, LTL, MER,
MOR, MWW and SOD. Non-limiting examples of the preferred molecular
sieves, particularly for converting an oxygenate containing feedstock
into olefin(s), include AEL, AFY, BEA, CHA, EDI, FAU, FER, GIS,
LTA, LTL, MER, MFI, MOR, MTT, MWW, TAM and TON. In one preferred
embodiment, the molecular sieve of the invention has an AEI framework-type
or a CHA framework-type, or a combination thereof, most preferably
a CHA framework-type.
[0022] Molecular sieve materials all have 3-dimensional framework
structure of corner-sharing TO.sub.4 tetrahedra, where T is any
tetrahedrally coordinated cation. These molecular sieves are typically
described in terms of the size of the ring that defines a pore,
where the size is based on the number of T atoms in the ring. Other
framework-type characteristics include the arrangement of rings
that form a cage, and when present, the dimension of channels, and
the spaces between the cages. See van Bekkum, et al., Introduction
to Zeolite Science and Practice, Second Completely Revised and Expanded
Edition, Volume 137 pages 1-67 Elsevier Science, B.V., Amsterdam,
Netherlands (2001).
[0023] The small, medium and large pore molecular sieves have from
a 4-ring to a 12-ring or greater framework-type. In a preferred
embodiment, the zeolitic molecular sieves have 8-, 10- or 12-ring
structures or larger and an average pore size in the range of from
about 3 .ANG. to 15 .ANG.. In the most preferred embodiment, the
molecular sieves of the invention, preferably silicoaluminophosphate
molecular sieves have 8-rings and an average pore size less than
about 5 .ANG., preferably in the range of from 3 .ANG. to about
5 .ANG., more preferably from 3 .ANG. to about 4.5 .ANG., and most
preferably from 3.5 .ANG. to about 4.2 .ANG..
[0024] Molecular sieves, particularly zeolitic and zeolitic-type
molecular sieves, preferably have a molecular framework of one,
preferably two or more corner-sharing [TO.sub.4] tetrahedral units,
more preferably, two or more [SiO.sub.4], [AlO.sub.4] and/or [PO.sub.4]
tetrahedral units, and most preferably [SiO.sub.4], [PO.sub.4] and
[PO.sub.4] tetrahedral units. These silicon, aluminum, and phosphorous
based molecular sieves and metal containing silicon, aluminum and
phosphorous based molecular sieves have been described in detail
in numerous publications including for example, U.S. Pat. No. 4567029
(MeAPO where Me is Mg, Mn, Zn, or Co), U.S. Pat. No. 4440871 (SAPO),
European Patent Application EP-A-0 159 624 (ELAPSO where El is As,
Be, B, Cr, Co, Ga, Ge, Fe, Li Mg, Mn, Ti or Zn), U.S. Pat. No. 4554143
(FeAPO), U.S. Pat. Nos. 4822478 4683217 4744885 (FeAPSO),
EP-A-0 158 975 and U.S. Pat. No. 4935216 (ZnAPSO, EP-A-0 161 489
(CoAPSO), EP-A-0 158 976 (ELAPO, where EL is Co, Fe, Mg, Mn, Ti
or Zn), U.S. Pat. No. 4310440 (AlPO.sub.4), EP-A-0 158 350 (SENAPSO),
U.S. Pat. No. 4973460 (LiAPSO), U.S. Pat. No. 4789535 (LiAPO),
U.S. Pat. No. 4992250 (GeAPSO), U.S. Pat. No. 4888167 (GeAPO),
U.S. Pat. No. 5057295 (BAPSO), U.S. Pat. No. 4738837 (CrAPSO),
U.S. Pat. Nos. 4759919 and 4851106 (CrAPO), U.S. Pat. Nos.
4758419 4882038 5434326 and 5478787 (MgAPSO), U.S. Pat.
No. 4554143 (FeAPO), U.S. Pat. No. 4894213 (AsAPSO), U.S. Pat.
No. 4913888 (AsAPO), U.S. Pat. Nos. 4686092 4846956 and 4793833
(MnAPSO), U.S. Pat. Nos. 5345011 and 6156931 (MnAPO), U.S. Pat.
No. 4737353 (BeAPSO), U.S. Pat. No. 4940570 (BeAPO), U.S. Pat.
Nos. 4801309 4684617 and 4880520 (TiAPSO), U.S. Pat. Nos.
4500651 4551236 and 4605492 (TiAPO), U.S. Pat. Nos. 4824554
4744970 (CoAPSO), U.S. Pat. No. 4735806 (GaAPSO) EP-A-0 293
937 (QAPSO, where Q is framework oxide unit [QO.sub.2]), as well
as U.S. Pat. Nos. 4567029 4686093 4781814 4793984 4801364
4853197 4917876 4952384 4956164 4956165 4973785
5241093 5493066 and 5675050 all of which are herein fully
incorporated by reference. Other molecular sieves are described
in R. Szostak, Handbook of Molecular Sieves, Van Nostrand Reinhold,
New York, N.Y. (1992), which is herein fully incorporated by reference.
[0025] 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. In an embodiment, the
metal is an alkali metal of Group IA of the Periodic Table of Elements,
an alkaline earth metal of Group IIA of the Periodic Table of Elements,
a rare earth metal of Group IIIB, including the Lanthanides: lanthanum,
cerium, praseodymium, neodymium, samarium, europium, gadolinium,
terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium;
and scandium or yttrium of the Periodic Table of Elements, a transition
metal of Groups IVB, VB, VIB, VIIB, VIIIB, and IB of the Periodic
Table of Elements, or mixtures of any of these metal species. In
one preferred embodiment, the metal is selected from the group consisting
of Co, Cr, Cu, Fe, Ga, Ge, Mg, Mn, Ni, Sn, Ti, Zn and Zr, and mixtures
thereof. In another preferred embodiment, these metal atoms discussed
above are inserted into the framework of a molecular sieve through
a tetrahedral unit, such as [MeO.sub.2], and carry a net charge
depending on the valence state of the metal substituent. For example,
in one embodiment, when the metal substituent has a valence state
of +2 +3 +4 +5 or +6 the net charge of the tetrahedral unit
is between -2 and +2.
[0026] 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 0 to 0.5 and most preferably from 0 to 0.3; x, y, and
z represent the mole fraction of M, Al and P 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.
[0027] Non-limiting examples of SAPO and ALPO molecular sieves
of the invention include one or a combination of SAPO-5 SAPO-8
SAPO-11 SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35
SAPO-36 SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAP-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 zeolite-type 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.
[0028] 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, intergrowth
molecular sieves are described in the U.S. patent application Ser.
No. 09/924016 filed Aug. 7 2001 and PCT WO 98/15496 published
Apr. 16 1998 both of which are herein fully incorporated by reference.
For example, SAPO-18 ALPO-18 and RUW-18 have an AEI framework-type,
and SAPO-34 has a CHA framework-type. In another embodiment, the
molecular sieve comprises at least one intergrown phase of AEI and
CHA framework-types, preferably the molecular sieve has a greater
amount of CHA framework-type to AEI framework-type, and more preferably
the ratio of CHA to AEI is greater than 1:1.
Molecular Sieve Synthesis
[0029] The synthesis of molecular sieves is described in many of
the references discussed above. 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, until a crystalline
molecular sieve material is formed, and then recovered by filtration,
centrifugation and/or decanting.
[0030] For purposes of this patent application and appended claims,
the term "not being fully dried" is defined to include
the condition where the sieve as obtained after synthesis has not
been dried up to the condition where the molecular sieve has been
dried but not calcined.
[0031] For purposes of this patent application and appended claims,
the term "partially dried" is defined to include drying
the molecular sieve to a level wherein, after drying, the molecular
sieve contains an amount of templating agent in the range of from
about 50 weight percent, preferably about 60 weight percent, more
preferably about 70 weight percent, and most preferably about 80
percent to 100 weight percent of the original amount of templating
agent used to form the crystalline molecular sieve material or the
synthesized molecular sieve originally.
[0032] In another preferred embodiment, the molecular sieve is
wet, preferably with water. Most preferably, the molecular sieve
is in the "wet filter cake" state, which means that the
molecular sieve has been recovered after molecular sieve crystallization
and dried, preferably partially dried. In the wet filter cake state,
the template has not been removed or has only been partially removed
from the molecular sieve.
[0033] In one particular embodiment, the crystalline molecular
sieve material or the synthesized molecular sieve is optionally
dried, preferably in air, to a level such that the synthesized molecular
sieve has in the range of from about 0 weight percent to about 80
weight percent liquid, preferably where the liquid is water, based
on the total weight of the synthesized molecular sieve and liquid,
preferably the range is from greater than 5 weight percent to about
70 weight percent, more preferably from about 10 weight percent
to about 70 weight percent, and most preferably from about 20 weight
percent to about 60 weight percent.
[0034] 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 a SAPO-34 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 determined as the percentage to
the starting SAPO-34 molecular sieve material is then regarded as
the percentage of the liquid or 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 weight loss as a
percentage of the original sample weight during this treatment is
regarded as the weight loss of the templating agent. The total weight
loss as a percentage in terms of the original first sample weight
during this entire TGA treatment is defined as Loss-On-Ignition
(LOI).
[0035] In a preferred embodiment, the crystalline molecular sieve
or synthesized molecular sieve is used directly after recovery from
the molecular sieve synthesis mixture without drying after synthesis,
and then forming the slurry of the crystalline molecular sieve or
synthesized molecular sieve, binder, and optional matrix material,
and then formulate the slurry into the molecular sieve catalyst
composition of the invention.
[0036] In a preferred embodiment the molecular sieves are synthesized
by forming a reaction product of a source of silicon, a source of
aluminum, a source of phosphorous, an organic templating agent,
preferably a nitrogen containing organic templating agent. This
particularly preferred embodiment results in the synthesis of a
silicoaluminophosphate crystalline material that is then isolated
by filtration, centrifugation and/or decanting.
[0037] Non-limiting examples of silicon sources include silicates,
fumed silica, for example, Aerosil-200 available from Degussa Inc.,
New York, N.Y., and CAB-O-SIL M-5 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] The quaternary ammonium compounds, in one embodiment, are
represented by the general formula RN, 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.
[0042] Non-limiting examples of templating agents include tetraalkyl
ammonium compounds including salts thereof such as tetramethyl ammonium
compounds including salts thereof, tetraethyl ammonium compounds
including salts thereof, tetrapropyl ammonium including salts thereof,
and tetrabutylammonium including salts thereof, cyclohexylamine,
morpholine, di-n-propylamine (DPA), tripropylamine, triethylamine
(TEA), triethanolamine, piperidine, cyclohexylamine, 2-methylpyridine,
N,N-dimethylbenzylamine, N,N-diethylethanolamine, dicyclohexylamine,
N,N-dimethylethanolamine, choline, N,N'-dimethylpiperazine, 14-diazabicyclo(222)octane,
N',N',N,N-tetramethyl-(16)hexanediamine, N-methyldiethanolamine,
N-methyl-ethanolamine, N-methyl piperidine, 3-methyl-piperidine,
N-methylcyclohexylamine, 3-methylpyridine, 4-methyl-pyridine, quinuclidine,
N,N'-dimethyl-14-diazabicyclo(222) octane ion; di-n-butylamine,
neopentylamine, di-n-pentylamine, isopropylamine, t-butyl-amine,
ethylenediamine, pyrrolidine, polyethylenimine and 2-imidazolidone.
[0043] The preferred templating agent or template is a tetraethylammonium
compound, such as tetraethyl ammonium hydroxide (TEAOH), tetraethyl
ammonium phosphate, tetraethyl ammonium fluoride, tetraethyl ammonium
bromide, tetraethyl ammonium chloride and tetraethyl ammonium acetate.
The most preferred templating agent is tetraethyl ammonium hydroxide
and salts thereof, particularly when producing a silicoaluminophosphate
molecular sieve. In one embodiment a combination of two or more
of any of the above templating agents is used in combination with
one or more of a silicon-, aluminum-, and phosphorous-source.
[0044] A synthesis mixture containing at a minimum a silicon-,
aluminum-, and/or phosphorous-composition, and a templating agent
is sealed in a vessel and heated, preferably under autogenous pressure,
to a temperature in the range of from about 80.degree. C. to about
250.degree. C., and more preferably from about 150.degree. C. to
about 180.degree. C. The time required to form the crystalline product
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
is recovered by any standard technique well known in the art for
example, decantation, centrifugation or filtration.
[0045] In a preferred 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 to a level such
that the crystalline product or synthesized molecular sieve has
in the range of from about 0 weight percent to about 80 weight percent
liquid, preferably were the liquid is water, based on the total
weight of the crystalline product or synthesized molecular sieve
and liquid medium, preferably the range is from about greater than
1 weight percent to about 80 weight percent, more preferably from
about 10 weight percent to about 70 weight percent, even more preferably
from about 20 to about 60 weight percent, and most preferably from
about 40 weight percent to about 60 weight percent. This liquid
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.
[0046] In one embodiment, where the synthesized molecular sieve
is partially dried, for example by heating, the temperature and
time period is sufficient to maintain a major proportion of the
templating agent in the molecular sieve, where more than 50% of
the templating agent is retained. In addition a preferred temperature
for heating the synthesized molecular sieve is typically about 180.degree.
C. or less, preferably less than 150.degree. C., even more preferably
less than 120.degree. C. for about 3 hours or less.
[0047] Molecular sieves have either a high silicon (Si) to aluminum
(Al) ratio or a low silicon to aluminum ratio, however, a low Si/Al
ratio is preferred for SAPO synthesis. In one embodiment, the molecular
sieve has a Si/Al ratio less than 0.65 preferably less than 0.40
more preferably less than 0.32 and most preferably less than 0.20.
In another embodiment the molecular sieve has a Si/Al ratio in the
range of from about 0.65 to about 0.10 preferably from about 0.40
to about 0.10 more preferably from about 0.32 to about 0.10 and
more preferably from about 0.32 to about 0.15.
Method for Making Molecular Sieve Catalyst Compositions
[0048] Once the molecular sieve is synthesized 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 synthesized molecular sieve(s) with
a binder and optionally, but preferably, a matrix material to form
a formulation composition. This formulation 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 formulation composition is then calcined.
[0049] In one embodiment, the weight ratio of the binder to the
molecular sieve is in the range of from about 0.1 to 0.5 preferably
in the range of from 0.1 to less than 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. In another
embodiment, the weight ratio of the binder to the molecular sieve
is in the range of from 0.11 to 0.45 preferably in the range of
from about 0.12 to less than 0.40 more preferably in the range
of from 0.15 to about 0.35 and most preferably in the range of
from 0.2 to about 0.3. All values between these ranges are included
in this patent specification.
[0050] In another embodiment, the molecular sieve catalyst composition
or formulated molecular sieve catalyst composition has a micropore
surface area (MSA) measured in m.sup.2/g-molecular sieve that is
about 70 percent, preferably about 75 percent, more preferably 80
percent, even more preferably 85 percent, and most preferably about
90 percent of the MSA of the molecular sieve itself. The term "MSA
on a contained sieve basis of the molecular sieve by itself"
or the term "MSA of X m.sup.2/g-molecular sieve" means
that the calculated MSA of a molecular sieve catalyst composite
is the measured MSA divided by the contained fraction of the molecular
sieve. For example, a molecular sieve catalyst composite with a
measured MSA of 200 m.sup.2/g and containing 40% molecular sieve
would be calculated to have an "MSA on a contained sieve basis
of the molecular sieve by itself" of 200 m.sup.2/g/0.4=500
m.sup.2/g-contained molecular sieve.
[0051] In one embodiment, the catalyst composition has a MSA on
a contained molecular sieve basis of the molecular sieve by itself
in the range of from 400 m.sup.2/g-molecular sieve to about 600
m.sup.2/g-molecular sieve, preferably an MSA in the range of from
425 m.sup.2/g-molecular sieve to about 575 m.sup.2/g-molecular,
more preferably in the range of from 425 m.sup.2/g-molecular sieve
to about 550 m.sup.2/g-molecular sieve, and most preferably in the
range of from about 450 m.sup.2/g-molecular sieve to about 550 m.sup.2/g-molecular
sieve.
[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 matrix component. For example, an alumina sol will convert
to an aluminum oxide matrix 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, one or more binders are combined
with one or more other non-limiting examples of alumina materials
such as aluminum oxyhydroxide, .gamma.-alumina, boehmite, diaspore,
and transitional aluminas such as .alpha.-alumina, .beta.-alumina,
.gamma.-alumina, .delta.-alumina, .epsilon.-alumina, .kappa.-alumina,
and .rho.-alumina, aluminum trihydroxide, such as gibbsite, bayerite,
nordstrandite, doyelite, and mixtures thereof.
[0054] 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.
[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. Non-limiting examples of other
matrix materials include: haloysite, kaolinite, dickite, nacrite,
or anauxite. 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.
[0057] In one preferred embodiment, the matrix material is a clay
or a clay-type composition, preferably the clay or clay-type composition
having a low iron or titania content, and most preferably the matrix
material is kaolin. Kaolin has been found to form a pumpable, high
solid content slurry, it has a low fresh surface area, and it packs
together easily due to its platelet structure. A preferred average
particle size of the matrix material, most preferably kaolin, is
from about 0.1 .mu.m to about 0.6 .mu.m with a d.sub.90 particle
size distribution of less than about 1 .mu.m.
[0058] In one embodiment, the binder, the synthesized molecular
sieve and the matrix material are combined in the presence of a
liquid such as water to form a molecular sieve catalyst composition,
where the amount of binder is from about 2% by weight to about 30%
by weight, preferably from about 5% by weight to about 20% by weight,
and more preferably from about 7% by weight to about 15% by weight,
based on the total weight of the binder, the molecular sieve and
matrix material, excluding the liquid.
[0059] Upon combining the synthesized molecular sieve and the matrix
material, optionally with a binder, in a liquid to form a slurry,
mixing, preferably rigorous mixing is needed to produce a substantially
homogeneous mixture containing the synthesized 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 colloid-milled
for a period of time sufficient to produce the desired slurry texture,
sub-particle size, and/or sub-particle size distribution.
[0060] The liquid containing synthesized molecular sieve and matrix
material, and the optional binder, 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.
[0061] The molecular sieve catalyst composition in a preferred
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 50% by weight of the molecular sieve, preferably from about
30% to about 48% by weight of the molecular sieve, more preferably
from about 40% to about 48% by weight molecular sieve, about 5%
to about 20%, preferably from 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.
[0062] In another most preferred 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 from about
20 weight percent to about 80 weight percent, more preferably in
the range of from 30 weight percent to about 70 weight percent,
even more preferably in the range of from 35 weight percent to 60
weight percent, still even more preferably from about 36 weight
percent to about 50 weight percent, yet even more preferably in
the range of from 37 weight percent to about 45 weight percent,
and most preferably in the range of from 38 weight percent to about
45 weight percent.
[0063] As the slurry is mixed, the solids in the slurry aggregate
preferably to a point where the slurry contains solid molecular
sieve catalyst composition particles. It is preferable that these
particles are small and have a uniform size distribution such that
the d.sub.90 diameter of these particles is less than 20 .mu.M,
more preferably less than 15 .mu.l, and most preferably less than
10 .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 3000 particle size
analyzer from Microtrac, Inc., Clearwater, Fla.). In one embodiment,
the slurry of the invention contains at least 90 percent by volume
of the molecular sieve catalyst composition particles comprising
the molecular sieve, binder, and optional matrix material, have
a diameter of less than 20 .mu.m, preferably less than 15 .mu.m,
and most preferably less than 10 .mu.m.
[0064] In one preferred embodiment the slurry comprising a liquid
portion and solid portion, wherein the solid portion comprises solid
particles, the solid particles comprising a molecular sieve, a binder
and/or a matrix material; wherein the slurry contains in the range
of from about 30 weight percent to about 50 weight percent solid
particles, preferably from about 35 weight percent to 45 weight
percent, and at least 90 percent of the solid particles having a
diameter less than 20 .mu.m, preferably less than 10 .mu.m.
[0065] 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 measured, preferably exclusive of the amount of water,
templating agent and/or other liquid contained within the particle.
In the most preferred condition for measuring solids content is
on a calcined basis. Thus, the weight of the solid content in the
slurry is equal to or very similar to the weight of the calcined
molecular sieve catalyst composition. On a calcined basis, the solid
content in the slurry, more specifically, the molecular sieve catalyst
composition particles in the slurry, are from about 20 percent by
weight to 45 percent by weight molecular sieve, 5 percent by weight
to 20 percent by weight binder, and from about 30 percent by weight
to 80 percent by weight matrix material.
[0066] In one embodiment, the slurry of the synthesized molecular
sieve, binder and matrix material is mixed or milled to achieve
a sufficiently uniform slurry of sub-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 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.
[0067] When a spray drier is used as the forming unit, typically,
any one or a combination of the slurries described above, more particularly
a slurry of the synthesized molecular sieve, matrix material, and
binder, 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 100.degree. C. to
about 225.degree. C. In an embodiment, the average diameter of the
spray dried formed catalyst composition is from about 40 .mu.m to
about 300 .mu.m, preferably from about 50 .mu.m to about 250 .mu.m,
more preferably from about 50 .mu.m to about 200 .mu.m, and most
preferably from about 65 .mu.m to about 90 .mu.m.
[0068] 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.
[0069] In yet another embodiment, the slurry described above is
directed to the perimeter of a spinning wheel that distributes the
slurry into small droplets, the size of which is controlled by many
factors including slurry viscosity, surface tension, flow rate,
pressure, and temperature of the slurry, the shape and dimension
of the nozzle(s), or the spinning rate of the wheel. These droplets
are then dried in a co-current or counter-current flow of air passing
through a spray drier to form a substantially dried or dried molecular
sieve catalyst composition, more specifically a molecular sieve
composition in a powder or a microsphere form.
[0070] 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.
[0071] Other methods for forming a molecular sieve catalyst composition
is described in U.S. patent application Ser. No. 09/617714 filed
Jul. 17 2000 (spray drying using a recycled molecular sieve catalyst
composition), which is herein incorporated by reference.
[0072] In another embodiment, the formulated molecular sieve catalyst
composition contains from about 1% to about 99%, preferably from
about 10% to about 90%, more preferably from about 10% to about
80%, even more preferably from about 20% to about 70%, and most
preferably from about 25% to about 60% by weight of the molecular
sieve based on the total weight of the molecular sieve catalyst
composition.
[0073] Once the molecular sieve catalyst composition is formed
in a substantially dry or dried state, to further harden and/or
activate the formed catalyst composition, a heat treatment such
as calcination, at an elevated temperature is preferably performed.
A conventional calcination environment is air that typically includes
a small amount of water vapor. Typical calcination temperatures
are in the range from about 400.degree. C. to about 1000.degree.
C., preferably from about 500.degree. C. to about 800.degree. C.,
and most preferably from about 550.degree. C. to about 700.degree.
C., preferably in a calcination environment such as air, nitrogen,
helium, flue gas (combustion product lean in oxygen), or any combination
thereof. In one embodiment, calcination of the formulated molecular
sieve catalyst composition is carried out in any number of well
known devices including rotary calciners, fluid bed calciners, batch
ovens, and the like. Calcination time is typically dependent on
the degree of hardening of the molecular sieve catalyst composition
and the temperature ranges from about 15 minutes to about 20 hours.
In a preferred embodiment, the molecular sieve catalyst composition
is heated in nitrogen at a temperature of from about 600.degree.
C. to about 700.degree. C. Heating is carried out for a period of
time typically from 15 minutes to 15 hours, preferably from 30 minutes
to about 10 hours, more preferably from about 30 minutes to about
5 hours.
[0074] In one embodiment, the attrition resistance of a molecular
sieve catalyst composition is measured using an Attrition Rate Index
(ARI), measured in weight percent catalyst composition attrited
per hour. ARI is measured by adding 6.0 g of catalyst composition
having a particles size ranging from 53 microns to 125 microns to
a hardened steel attrition cup. Approximately 23700 cc/min of nitrogen
gas is bubbled through a water-containing bubbler to humidify the
nitrogen. The wet nitrogen passes through the attrition cup, and
exits the attrition apparatus through a porous fiber thimble. The
flowing nitrogen removes the finer particles, with the larger particles
being retained in the cup. The porous fiber thimble separates the
fine catalyst particles from the nitrogen that exits through the
thimble. The fine particles remaining in the thimble represent the
catalyst composition that has broken apart through attrition. The
nitrogen flow passing through the attrition cup is maintained for
1 hour. The fines collected in the thimble are removed from the
unit. A new thimble is then installed. The catalyst left in the
attrition unit is attrited for an additional 3 hours, under the
same gas flow and moisture levels. The fines collected in the thimble
are recovered. The collection of fine catalyst particles separated
by the thimble after the first hour are weighed. The amount in grams
of fine particles divided by the original amount of catalyst charged
to the attrition cup expressed on per hour basis is the ARI, in
weight percent per hour (wt. %/hr). ARI is represented by the formula:
ARI=C/(B+C)/D multiplied by 100%, wherein B is weight of catalyst
composition left in the cup after the attrition test, C is the weight
of collected fine catalyst particles after the first hour of attrition
treatment, and D is the duration of treatment in hours after the
first hour attrition treatment.
[0075] In one embodiment, the molecular sieve catalyst composition
or formulated molecular sieve catalyst composition has an ARI less
than 15 weight percent per hour, preferably less than 10 weight
percent per hour, more preferably less than 5 weight percent per
hour, and even more preferably less than 2 weight percent per hour,
and most preferably less than 1 weight percent per hour. In one
embodiment, the molecular sieve catalyst composition or formulated
molecular sieve catalyst composition has an ARI in the range of
from 0 weight percent per hour to less than 5 weight percent per
hour, more preferably from about 0.05 weight percent per hour to
less than 3 weight percent per hour, and most preferably from about
0.01 weight percent per hour to less than 2 weight percent per hour.
[0076] In one preferred embodiment of the invention, the molecular
sieve catalyst composition or formulated molecular sieve catalyst
composition comprises a synthesized molecular sieve in an amount
of from 20 weight percent to 60 weight percent, a binder in an amount
of from 5 to 50 weight percent, and a matrix material in an amount
of from 0 to 78 weight percent based on the total weight of the
catalyst composition, upon calcination, and the catalyst composition
having weight ratio of binder to sieve of from 0.1 to less than
0.5. In addition, the catalyst composition of this embodiment has
an MSA on a contained sieve basis of the molecular sieve by itself
from 450 m.sup.2/g-molecular sieve to 550 m.sup.2/g-molecular sieve,
and/or an ARI less than 2 weight percent per hour.
Process for Using the Molecular Sieve Catalyst Compositions
[0077] The molecular sieve catalyst compositions or formulated
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.
[0078] 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).
[0079] 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.
[0080] 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.
[0081] In a preferred embodiment of the process of the invention,
the feedstock contains one or more oxygenates, more specifically,
one or more organic compound(s) containing at least one oxygen atom.
In the most preferred embodiment of the process of invention, the
oxygenate in the feedstock is one or more alcohol(s), preferably
aliphatic alcohol(s) where the aliphatic moiety of the alcohol(s)
has from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms,
and most preferably from 1 to 4 carbon atoms. The alcohols useful
as feedstock in the process of the invention include lower straight
and branched chain aliphatic alcohols and their unsaturated counterparts.
[0082] 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.
[0083] 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 an/or propylene. Non-limiting
examples of olefin monomer(s) include ethylene, propylene, butene-1
pentene-14-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.
[0084] 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.
[0085] 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,
methanol-to-olefins (MTO). In a GTO process, typically natural gas
is converted into a synthesis gas that is converted into an oxygenated
feedstock, preferably containing methanol, where the oxygenated
feedstock is converted in the presence of a molecular sieve catalyst
composition into one or more olefin(s), preferably ethylene and/or
propylene. In a MTO process, typically an oxygenated feedstock most
preferably a methanol containing feedstock, is converted in the
presence of a molecular sieve catalyst composition thereof into
one or more olefin(s), preferably and predominantly, ethylene and/or
propylene, often referred to as light olefin(s).
[0086] In one embodiment of the process for conversion of a feedstock,
preferably a feedstock containing one or more oxygenates, the amount
of olefin(s) produced based on the total weight of hydrocarbon produced
is greater than 50 weight percent, preferably greater than 60 weight
percent, more preferably greater than 70 weight percent, and most
preferably greater than 75 weight percent. In another embodiment
of the process for conversion of one or more oxygenates to one or
more olefin(s), the amount of ethylene and/or propylene produced
based on the total weight of hydrocarbon product produced is greater
than 65 weight percent, preferably greater than 70 weight percent,
more preferably greater than 75 weight percent, and most preferably
greater than 78 weight percent.
[0087] In another embodiment of the process for conversion of one
or more oxygenates to one or more olefin(s), the amount ethylene
produced in weight percent based on the total weight of hydrocarbon
product produced, is greater than 30 weight percent, more preferably
greater than 35 weight percent, and most preferably greater than
40 weight percent. In yet another embodiment of the process for
conversion of one or more oxygenates to one or more olefin(s), the
amount of propylene produced in weight percent based on the total
weight of hydrocarbon product produced is greater than 20 weight
percent, preferably greater than 25 weight percent, more preferably
greater than 30 weight percent, and most preferably greater than
35 weight percent.
[0088] 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.
[0089] The diluent, water, is used either in a liquid or a vapor
form, or a combination thereof. The diluent is either added directly
to a feedstock entering into a reactor or added directly into a
reactor, or added with a molecular sieve catalyst composition. In
one embodiment, the amount of diluent in the feedstock is in the
range of from about 1 to about 99 mole percent based on the total
number of moles of the feedstock and diluent, preferably from about
1 to 80 mole percent, more preferably from about 5 to about 50
and most preferably from about 5 to about 25.
[0090] In one embodiment, other hydrocarbons are added to a feedstock
either directly or indirectly, and include olefin(s), paraffin(s),
aromatic(s) (see for example U.S. Pat. No. 4677242 addition of
aromatics) or mixtures thereof, preferably propylene, butylene,
pentylene, and other hydrocarbons having 4 or more carbon atoms,
or mixtures thereof.
[0091] 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.
[0092] 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.
Othmo, Reinhold Publishing Corporation, New York, 1960 and U.S.
Pat. No. 6166282 (fast-fluidized bed reactor), and U.S. patent
application Ser. No. 09/564613 filed May 4 2000 (multiple riser
reactor), which are all herein fully incorporated by reference.
[0093] 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.
[0094] 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.
[0095] In an embodiment, the amount of fresh feedstock fed separately
or jointly with a vapor feedstock, to a reactor system is in the
range of from 0.1 weight percent to about 85 weight percent, preferably
from about 1 weight percent to about 75 weight percent, more preferably
from about 5 weight percent to about 65 weight percent based on
the total weight of the feedstock including any diluent contained
therein. The liquid and vapor feedstocks are preferably of similar
or the same composition, or contain varying proportions of the same
or different feedstock with the same or different diluent.
[0096] 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 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 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.
[0097] 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 and the gas
is passed at a gas hourly superficial velocity (GHSV) of from 1
hr.sup.-1 to about 20000 hr.sup.-1 based on the volume of gas to
volume of coked molecular sieve catalyst composition, preferably
at an elevated temperature from 250.degree. C. to about 750.degree.
C., preferably from about 350.degree. C. to 650.degree. C., over
the coked molecular sieve catalyst composition.
[0098] The conversion temperature employed in the conversion process,
specifically within the reactor system, is in the range of from
about 200.degree. C. to about 1000.degree. C., preferably from about
250.degree. C. to about 800.degree. C., more preferably from about
250.degree. C. to about 750.degree. C., yet more preferably from
about 300.degree. C. to about 650.degree. C., yet even more preferably
from about 350.degree. C. to about 600.degree. C. most preferably
from about 350.degree. C. to about 550.degree. C.
[0099] 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 from about 0.1 kPaa to about 5 MPaa, preferably
from about 5 kPaa to about 1 MPaa, and most preferably from about
20 kPaa to about 500 kPaa.
[0100] 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.
[0101] Typically, the WHSV ranges from about 1 hr.sup.-1 to about
5000 hr.sup.-1 preferably from about 2 hr.sup.-1 to about 3000
hr.sup.-1 more preferably from about 5 hr.sup.-1 to about 1500
hr.sup.-1 and most preferably from 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 from about
20 hr.sup.-1 to about 300 hr.sup.-1.
[0102] 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. patent
application Ser. No. 09/708753 filed Nov. 8 2000 which is herein
incorporated by reference.
[0103] In one preferred embodiment of the process for converting
an oxygenate to olefin(s) using a silicoaluminophosphate molecular
sieve catalyst composition, the process is operated at a WHSV of
at least 20 hr.sup.-1 and a Temperature Corrected Normalized Methane
Selectivity (TCNMS) of less than 0.016 preferably less than or
equal to 0.01. See for example U.S. Pat. No. 5952538 which is
herein fully incorporated by reference. In another embodiment of
the processes for converting an oxygenate such as methanol to one
or more olefin(s) using a molecular sieve catalyst composition,
the WHSV is from 0.01 hr.sup.-1 to about 100 hr.sup.-1 at a temperature
of from about 350.degree. C. to 550.degree. C.; and silica to Me.sub.2O.sub.3
(Me is a Group IIIA or VIII element from the Periodic Table of Elements)
molar ratio of from 300 to 2500. See for example EP-0 642 485 B1
which is herein fully incorporated by reference. Other processes
for converting an oxygenate such as methanol to one or more olefin(s)
using a molecular sieve catalyst composition are described in PCT
WO 01/23500 published Apr. 5 2001 (propane reduction at an average
catalyst feedstock exposure of at least 1.0), which is herein incorporated
by reference.
[0104] 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. 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.
[0105] The regeneration temperature is in the range of from about
200.degree. C. to about 1500.degree. C., preferably from about 300.degree.
C. to about 1000.degree. C., more preferably from about 450.degree.
C. to about 750.degree. C., and most preferably from about 550.degree.
C. to 700.degree. C. The regeneration pressure is in the range of
from about 15 psia (103 kPaa) to about 500 psia (3448 kPaa), preferably
from about 20 psia (138 kPaa) to about 250 psia (1724 kPaa), more
preferably from about 25 psia (172 kPaa) to about 150 psia (1034
kPaa), and most preferably from 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
from 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 from about 0.01 mole percent to about 5 mole
percent based on the total volume of the gas.
[0106] In one embodiment, regeneration promoters, typically metal
containing compounds such as platinum, palladium and the like, are
added to the regenerator directly, or indirectly, for example with
the coked catalyst composition. Also, in another embodiment, a fresh
molecular sieve catalyst composition is added to the regenerator
containing a regeneration medium of oxygen and water as described
in U.S. Pat. No. 6245703 which is herein fully incorporated by
reference. In yet another embodiment a portion of the coked molecular
sieve catalyst composition from the regenerator is returned directly
to the one or more riser reactor(s), or indirectly, by pre-contacting
with the feedstock, or contacting with fresh molecular sieve catalyst
composition, or contacting with a regenerated molecular sieve catalyst
composition or a cooled regenerated molecular sieve catalyst composition
described below.
[0107] The burning of coke is an exothermic reaction, and in an
embodiment, the temperature within the regeneration system is controlled
by various techniques in the art including feeding a cooled gas
to the regenerator vessel, operated either in a batch, continuous,
or semi-continuous mode, or a combination thereof. A preferred technique
involves withdrawing the regenerated molecular sieve catalyst composition
from the regeneration system and passing the regenerated molecular
sieve catalyst composition through a catalyst cooler that forms
a cooled regenerated molecular sieve catalyst composition. The catalyst
cooler, in an embodiment is a heat exchanger that is located either
internal or external to the regeneration system. In one embodiment,
the cooler regenerated molecular sieve catalyst composition is returned
to the regenerator in a continuous cycle, alternatively, (see U.S.
patent application Ser. No. 09/587766 filed Jun. 6 2000) a portion
of the cooled regenerated molecular sieve catalyst composition is
returned to the regenerator vessel in a continuous cycle, and another
portion of the cooled molecular sieve regenerated molecular sieve
catalyst composition is returned to the riser reactor(s), directly
or indirectly, or a portion of the regenerated molecular sieve catalyst
composition or cooled regenerated molecular sieve catalyst composition
is contacted with by-products within the gaseous effluent (PCT WO
00/49106 published Aug. 24 2000), which are all herein fully incorporated
by reference. In another embodiment, a regenerated molecular sieve
catalyst composition contacted with an alcohol, preferably ethanol,
1-propnaol, 1-butanol or mixture thereof, is introduced to the reactor
system, as described in U.S. patent application Ser. No. 09/785122
filed Feb. 16 2001 which is herein fully incorporated by reference.
Other methods for operating a regeneration system are in disclosed
U.S. Pat. No. 6290916 (controlling moisture), which is herein
fully incorporated by reference.
[0108] The regenerated molecular sieve catalyst composition withdrawn
from the regeneration system, preferably from the catalyst cooler,
is combined with a fresh molecular sieve catalyst composition and/or
re-circulated molecular sieve catalyst composition and/or feedstock
and/or fresh gas or liquids, and returned to the riser reactor(s).
In another embodiment, the regenerated molecular sieve catalyst
composition withdrawn from the regeneration system is returned to
the riser reactor(s) directly, optionally after passing through
a catalyst cooler. In one embodiment, a carrier, such as an inert
gas, feedstock vapor, steam or the like, semi-continuously or continuously,
facilitates the introduction of the regenerated molecular sieve
catalyst composition to the reactor system, preferably to the one
or more riser reactor(s).
[0109] In one embodiment, the optimum level of coke on the molecular
sieve catalyst composition in the reaction zone is maintained 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, a complete regeneration.
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.
In another embodiment, the optimum level of coke on the molecular
sieve catalyst composition in the reaction zone is maintained by
controlling the flow rate of oxygen containing gas flowing to the
regenerator, a partial regeneration. Coke levels on the molecular
sieve catalyst composition is measured by withdrawing from the conversion
process the molecular sieve catalyst composition at a point in the
process and determining its carbon content. Typical levels of coke
on the molecular sieve catalyst composition, after regeneration
is in the range of from 0.01 weight percent to about 15 weight percent,
preferably from about 0.1 weight percent to about 10 weight percent,
more preferably from about 0.2 weight percent to about 5 weight
percent, and most preferably from about 0.3 weight percent to about
2 weight percent based on the total weight of the molecular sieve
and not the total weight of the molecular sieve catalyst composition.
[0110] In one preferred embodiment, the mixture of fresh molecular
sieve catalyst composition and/or regenerated molecular sieve catalyst
composition and/or cooled regenerated molecular sieve catalyst composition
in the reaction zone contains in the range of from about 1 to 50
weight percent, preferably from about 2 to 30 weight percent, more
preferably from about 2 to about 20 weight percent, and most preferably
from about 2 to about 10 coke or carbonaceous deposit based on the
total weight of the mixture of molecular sieve catalyst compositions.
See for example U.S. Pat. No. 6023005 which is herein fully incorporated
by reference. It is recognized that the molecular sieve catalyst
composition in the reaction zone is made up of a mixture of regenerated
and fresh molecular sieve catalyst composition that have varying
levels of carbon and carbon-like deposits, coke. The measured level
of these deposits, specifically coke, represents an average of the
levels on individual molecular sieve catalyst composition particles.
[0111] The gaseous effluent is withdrawn from the disengaging system
and is passed through a recovery system. There are many well known
recovery systems, techniques and sequences that are useful in separating
olefin(s) and purifying olefin(s) from the gaseous effluent. Recovery
systems generally comprise one or more or a combination of 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.
[0112] 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.
[0113] Generally accompanying most recovery systems is the production,
generation or accumulation of additional products, by-products and/or
contaminants along with the preferred prime products. The preferred
prime products, the light olefins, such as ethylene and propylene,
are typically purified for use in derivative manufacturing processes
such as polymerization processes. Therefore, in the most preferred
embodiment of the recovery system, the recovery system also includes
a purification system. For example, the light olefin(s) produced
particularly in a MTO process are passed through a purification
system that removes low levels of by-products or contaminants. Non-limiting
examples of contaminants and by-products include generally polar
compounds such as water, alcohols, carboxylic acids, ethers, carbon
oxides, sulfur compounds such as hydrogen sulfide, carbonyl sulfides
and mercaptans, ammonia and other nitrogen compounds, arsine, phosphine
and chlorides. Other contaminants or by-products include hydrogen
and hydrocarbons such as acetylene, methyl acetylene, propadiene,
butadiene and butyne.
[0114] Other recovery systems that include purificatio |