Molecular sieve abstract
The 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. In particular,
the invention is directed to a conversion process for producing
olefin(s), preferably ethylene and/or propylene, from a feedstock,
preferably an oxygenate containing feedstock in the presence of
a molecular sieve having been synthesized in the presence of a flocculant.
Molecular sieve claims
We claim:
1. A process for producing one or more olefin(s), the process comprising
the steps of: (a) introducing a feedstock to a reactor system in
the presence of a molecular sieve catalyst composition comprising
a synthesized molecular sieve having been recovered in the presence
of a flocculent; (b) withdrawing from the reactor system an effluent
stream; and (c) passing the effluent gas through a recovery system
recovering at least the one or more olefin(s).
2. The process of claim 1 wherein the feedstock comprises one or
more oxygenates.
3. The process of claim 1 wherein the synthesized 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.
4. The process of claim 1 wherein the formulated molecular sieve
catalyst composition further comprises a binder and a matrix material.
5. The process of claim 1 wherein the flocculant has a molecular
weight (MW) in the range of from 10000 to 800000.
6. The process of claim 1 wherein the flocculant is present in
an amount of about 0.01 to 10 wt % flocculant based on the total
weight of the synthesized molecular sieve.
7. The process of claim 1 wherein the flocculant is a polymeric
amine.
8. The process of claim 1 wherein the flocculant is represented
by the formula: (R--NH).sub.x, where (R--NH) is a polymeric or monomeric
unit where R contains from 1 to 20 carbon atoms, and x is an integer
from 1 to 500000.
9. The process of claim 1 wherein the flocculant is represented
by the formula: (--NHCH.sub.2CH.sub.2--).sub.m[--N(CH.sub.2CH.sub.2NH.sub.2)CH.s-
ub.2CH.sub.2--]n), wherein m is from 10 to 20000 and n is from
0 to 2000.
10. The process of claim 1 wherein the synthesized 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.
11. The process of claim 1 wherein the greater than 1000 Kg of
one or more olefin(s) is being produced.
12. The process of claim 1 wherein the one or more olefin(s) include
ethylene and propylene.
13. The process of claim 1 wherein the synthesized molecular sieve
is formulated into a formulated molecular sieve catalyst composition,
the formulated molecular sieve catalyst composition comprising the
synthesized molecular sieve, a matrix material, and optionally a
binder.
14. An integrated process for making one or more olefin(s), the
integrated process comprising the steps of: (a) passing a hydrocarbon
feedstock to a syngas production zone to producing a synthesis gas
stream; (b) contacting the synthesis gas stream with a catalyst
to form an oxygenated feedstock; and (c) converting the oxygenated
feedstock into the one or more olefin(s) in the presence of a molecular
sieve catalyst composition, the molecular sieve catalyst composition
comprising a synthesized molecular sieve having been recovered in
the presence of a flocculant.
15. The integrated process of claim 14 wherein the process further
comprises the step of: (d) polymerizing the one or more olefin(s)
in the presence of a polymerization catalyst into a polyolefin.
16. The integrated process of claim 14 wherein the oxygenated feedstock
comprises methanol, the olefin(s) include ethylene and propylene,
and the synthesized molecular sieve is a silicoaluminophosphate
molecular sieve.
17. The integrated process of claim 14 wherein the flocculant has
a molecular weight (MW) in the range of from 10000 to 800000.
18. The integrated process of claim 14 wherein the flocculant is
present in an amount of about 0.01 to 10 wt % flocculant based on
the total weight of the molecular sieve synthesized.
19. The integrated process of claim 14 wherein the flocculant is
a polymeric amine.
20. The integrated process of claim 14 wherein the flocculant is
represented by the formula: (R--NH).sub.x, where (R--NH) is a polymeric
or monomeric unit where R contains from 1 to 20 carbon atoms, and
x is an integer from 1 to 500000.
21. The integrated process of claim 14 wherein the flocculant is
represented by the formula: (--NHCH.sub.2CH.sub.2--).sub.m[--N(CH.sub.2CH-
.sub.2NH.sub.2)CH.sub.2CH.sub.2--].sub.n), wherein m is from 10
to 20000 and n is from 0 to 2000.
22. The integrated process of claim 14 wherein the flocculant is
a polyethyleneimine.
23. The integrated process of claim 14 wherein the molecular sieve
catalyst composition further comprises a matrix material, and optionally
a binder.
24. The integrated process of claim 14 wherein the flocculant is
present in an amount of about 0.01 to 10 wt % flocculant based on
the total weight of the synthesized molecular sieve.
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 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 reactor in the presence
of a heterogeneous catalyst. For example, in one synthesis process
methanol is produced using a copper/zinc oxide catalyst in a water-cooled
tubular reactor. The preferred methanol conversion process is generally
referred to as a methanol-to-olefin(s) process (MTO), where an oxygenate,
typically mostly methanol, is converted into primarily ethylene
and/or propylene in the presence of a molecular sieve.
[0005] There are many different types of molecular sieves well
known to convert a feedstock, especially an oxygenate containing
feedstock, into one or more olefin(s). Molecular sieves, such as
zeolites or zeolite-type molecular sieves, carbons and oxides, are
porous solids having pores of different sizes that selectively adsorb
molecules that can enter the pores, and exclude other molecules
that are too large. Examples of molecular sieves useful in converting
an oxygenate into olefin(s) are: U.S. Pat. No. 5367100 describes
the use of a well known zeolite, ZSM-5 to convert methanol into
olefin(s); U.S. Pat. No. 4062905 discusses the conversion of methanol
and other oxygenates to ethylene and propylene using crystalline
aluminosilicate zeolites, for example Zeolite T, ZK5 erionite and
chabazite; U.S. Pat. No. 4079095 describes the use of ZSM-34 to
convert methanol to hydrocarbon products such as ethylene and propylene;
U.S. Pat. No. 4310440 describes producing light olefin(s) from
an alcohol using a crystalline aluminophosphates, often represented
by ALPO.sub.4; and U.S. Pat. No. 4440871 describes silicoaluminophosphate
molecular sieves (SAPO), one of the most useful molecular sieves
for converting methanol into olefin(s).
[0006] Typically, molecular sieves are formed into molecular sieve
catalyst compositions to improve their durability in commercial
conversion processes. The collisions within a commercial process
between catalyst composition particles themselves, the reactor walls,
and other reactor systems cause the particles to breakdown into
smaller particles called fines. The physical breakdown of the molecular
sieve catalyst composition particles is known as attrition. Problems
develop in the recovery systems because fines often exit the reactor
in the product containing effluent stream. Catalyst compositions
having a higher resistance to attrition generate fewer fines; this
results in improved process operability, and less catalyst composition
being required for a conversion process, and therefore, lower overall
operating costs.
[0007] It is known that the way in which the molecular sieve catalyst
compositions are made or formulated affects catalyst composition
attrition. Molecular sieve catalyst compositions are formed by combining
a molecular sieve and a matrix material usually in the presence
of a binder. For example, PCT Patent Publication WO 03/000413 A1
published Jan. 3 2003 discloses a low attrition molecular sieve
catalyst composition using a synthesized molecular sieve that has
not been fully dried, or partially dried, in combination in a slurry
with a matrix material and/or a binder. Also, PCT Patent Publication
WO 03/000412 A1 published Jan. 3 2003 discusses a low attrition
molecular sieve catalyst composition produced by controlling the
pH of the slurry above the isoelectric point of the molecular sieve.
U.S. Patent Application Publication No. U.S. 2003/0018228 published
Jan. 23 2003 shows making a low attrition molecular sieve catalyst
composition by making a slurry of a synthesized molecular sieve,
a binder, and optionally a matrix material, wherein 90 percent by
volume of the slurry contains particles having a diameter less than
20 .mu.m. U.S. patent application Ser. No. 10/178455 filed Jun.
24 2002 which is herein fully incorporated by reference, illustrates
making an attrition resistant molecular sieve catalyst composition
by controlling the ratio of a binder to a molecular sieve. U.S.
Pat. No. 6503863 is directed to a method of heat treating a molecular
sieve catalyst composition to remove a portion of the template used
in the synthesis of the molecular sieve. U.S. Pat. No. 6541415
describes improving the attrition resistance of a molecular sieve
catalyst composition that contains molecular sieve-containing recycled
attrition particles and virgin molecular sieve and having been calcined
to remove the template from the molecular sieve catalyst. U.S. Pat.
No. 6660682 describes the use of a polymeric base to reduce the
amount of templating agent required to produce a particular molecular
sieve.
[0008] It is also known that in typical commercial processes that
flocculants are used in the recovery of synthesized molecular sieves.
These flocculants are known to facilitate the crystal recovery and
to increase the yield of recovery of the synthesized molecular sieve
typically in a large scale commercial process. However, the presence
of a flocculate can affect the catalyst formulation, and in some
cases flocculation can result in the formulation of catalyst compositions
having lower attrition resistance and lower selectivity in various
conversion processes.
[0009] 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 selectivity to in particular prime olefins, especially
ethylene and propylene.
SUMMARY OF THE INVENTION
[0010] This invention generally 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).
[0011] In one embodiment the invention is directed to a process
for producing one or more olefin(s), the process comprising the
steps of: (a) introducing a feedstock to a reactor system in the
presence of a formulated molecular sieve catalyst composition comprising
a synthesized molecular sieve having been recovered in the presence
of a flocculant; (b) withdrawing from the reactor system an effluent
stream; and (c) passing the effluent stream through a recovery system
recovering at least the one or more olefin(s). In one embodiment,
the flocculent is a charged organic polymer. Preferably the synthesized
molecular sieve is a metallo-aluminophosphate, a silicoaluminophosphate,
an aluminophosphate, a chabazite (CHA) framework-type molecular
sieve, or a CHA and AEI intergrowth or mixed framework-type molecular
sieve.
[0012] In another preferred embodiment, the invention relates to
a method for synthesizing a molecular sieve, the method comprising
the steps of: (a) forming a synthesis mixture comprising two or
more a silicon source, an aluminum source, a phosphorous source,
and a templating agent; (b) introducing to the synthesis mixture
a flocculent; and (c) recovering the synthesized molecular sieve.
In one embodiment, the flocculant is a charged organic polymer.
In another embodiment, the flocculant is selected from one or more
of the group consisting of polyethylenimine. In yet another preferred
embodiment, the synthesis mixture comprising three or more of a
silicon source, an aluminum source, a phosphorous source, and a
templating agent. In yet another embodiment, step (c) of recovering
is one or more filtration step(s) or one or more filtration step(s)
and washing step(s), or a combination of one or more of a centrifugation
step(s), a washing step(s), and a filtration step(s). In yet another
preferred embodiment of this embodiment, the amount of molecular
sieve recovered in a single batch is greater than 250 Kg, preferably
greater than 500 Kg, and most preferably greater than 1000 Kg.
DETAILED DESCRIPTION OF THE INVENTION INTRODUCTION
[0013] The invention is directed toward a molecular sieve catalyst
composition, its making, and to its use in the conversion of a feedstock
into one or more olefin(s). A formulated molecular sieve catalyst
composition is typically formed from a slurry of the combination
of a molecular sieve, a matrix material, and optionally, most preferably,
a binder. It has been discovered that when recovering a molecular
sieve in the presence of a flocculant in a molecular sieve synthesis
process, the synthesized molecular sieve exhibits improved selectivity
for primarily ethylene and propylene in a conversion process of
one or more alcohols, more specifically methanol.
[0014] Molecular Sieves
[0015] 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.
For additional information on molecular sieve types, structures
and characteristics, see van Bekkum, et al., Introduction to Zeolite
Science and Practice, Second Completely Revised and Expanded Edition,
Volume 137 Elsevier Science, B. V., Amsterdam, Netherlands (2001),
which is also fully incorporated herein by reference.
[0016] Non-limiting examples of these molecular sieves are the
small pore molecular sieves, AEI, AFT, APC, ATN, ATT, ATV, AWW,
BIK, CAS, CHA, CHI, DAC, DDR, EDI, ERI, GOO, KFI, LEV, LOV, LTA,
MON, PAU, PHI, RHO, ROG, THO, and substituted forms thereof; the
medium pore molecular sieves, AFO, AEL, EUO, HEU, FER, MEL, MFI,
MTW, MTT, TON, and substituted forms thereof; and the large pore
molecular sieves, EMT, FAU, and substituted forms thereof. Other
molecular sieves include ANA, BEA, CFI, CLO, DON, GIS, LTL, MER,
MOR, MWW and SOD. Non-limiting examples of the preferred molecular
sieves, particularly for converting an oxygenate containing feedstock
into olefin(s), include AEI, AEL, AFY, BEA, CHA, EDI, FAU, FER,
GIS, LTA, LTL, MER, MFI, MOR, MTT, MWW, TAM and TON. In one preferred
embodiment, the molecular sieve of the invention has an AEI topology
or a CHA topology, or a combination thereof, most preferably an
intergrowth thereof.
[0017] The small, medium and large pore molecular sieves have from
a 4-ring to a 12-ring or greater framework-type. In a preferred
embodiment, the molecular sieves have 8-, 10- or 12-ring structures
or larger and an average pore size in the range of from about 3
.ANG. to 15 .ANG.. In the most preferred embodiment, the molecular
sieves, preferably SAPO molecular sieves, have 8-rings and an average
pore size less than about 5 .ANG., preferably in the range of from
3 .ANG. to about 5 .ANG., more preferably from 3 .ANG. to about
4.5 .ANG., and most preferably from 3.5 .ANG. to about 4.2 .ANG..
[0018] Molecular sieves based on silicon, aluminum, and phosphorous,
and metal containing molecular sieves thereof, have been described
in detail in numerous publications including for example, U.S. Pat.
No. 4567029 (MeAPO where Me is Mg, Mn, Zn, or Co), U.S. Pat. No.
4440871 (SAPO), European Patent Application EP-A-0 159 624 (ELAPSO
where El is As, Be, B, Cr, Co, Ga, Ge, Fe, Li, Mg, Mn, Ti or Zn),
U.S. Pat. No. 4554143 (FeAPO), U.S. Pat. Nos. No. 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 5098684 (MCM-41), 5198203 (MCM-48), 5241093 5304363
(MCM-50), 5493066 5675050 6077498 (ITQ-1), 6409986 (ITQ-5),
6419895 (UZM-4), 6471939 (ITQ-12), 6471941 (ITQ-13), 6475463
(SSZ-55), 6500404 (ITQ-3), 6500998 (UZM-5 and UZM-6), 6524551
(MCM-58) and 6544495 (SSZ-57), 6547958 (SSZ-59), 6555090 (ITQ-36)
and 6569401 (SSZ-64), all of which are herein fully incorporated
by reference. Other molecular sieves are described in R. Szostak,
Handbook of Molecular Sieves, Van Nostrand Reinhold, New York, N.Y.
(1992), which is herein fully incorporated by reference.
[0019] 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.
[0020] 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
[0021] wherein R represents at least one templating agent, preferably
an organic templating agent; m is the number of moles of R per mole
of (M.sub.xAl.sub.yP.sub.z)O.sub.2 and m has a value from 0 to 1
preferably 0 to 0.5 and most preferably from 0 to 0.3; x, y, and
z represent the mole fraction of Al, P and M as tetrahedral oxides,
where M is a metal selected from one of Group IA, IIA, IB, IIIB,
IVB, VB, VIIB, 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.
[0022] Synthesis of a molecular sieve, especially a SAPO molecular
sieve, its formulation into a SAPO catalyst, and its use in converting
a hydrocarbon feedstock into olefin(s), is shown in, for example,
U.S. Pat. Nos. 4499327 4677242 4677243 4873390 5095163
5714662 and 6166282 all of which are herein fully incorporated
by reference. Non-limiting examples of SAPO and ALPO molecular sieves
of the invention include one or a combination of SAPO-5 SAPO-8
SAPO-11 SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35
SAPO-36 SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 (U.S. Pat.
No. 6162415), SAPO-47 SAPO-56 ALPO-5 ALPO-11 ALPO-18 ALPO-31
ALPO-34 ALPO-36 ALPO-37 ALPO-46 and metal containing molecular
sieves thereof. The more preferred molecular sieves include one
or a combination of SAPO-18 SAPO-34 SAPO-35 SAPO-44 SAPO-56
ALPO-18 and ALPO-34 even more preferably one or a combination of
SAPO-18 SAPO-34 ALPO-34 and ALPO-18 and metal containing molecular
sieves thereof, and most preferably one or a combination of SAPO-34
and ALPO-18 and metal containing molecular sieves thereof.
[0023] In an embodiment, the molecular sieve is an intergrowth
material having two or more distinct phases of crystalline structures
within one molecular sieve composition. In particular, SAPO intergrowth
molecular sieves are described in the U.S. patent application Ser.
No. 09/924016 filed Aug. 7 2001 PCT Publication WO 02/070407
published Sep. 12 2002 and PCT Publication WO 98/15496 published
Apr. 16 1998 which are herein fully incorporated by reference.
For example, SAPO-18 ALPO-18 and RUW-18 have an AEI framework-type,
and SAPO-34 has a CHA framework-type. In another embodiment, the
molecular sieve comprises at least one intergrown phase of AEI and
CHA framework-types, preferably the molecular sieve has a greater
amount of CHA framework-type to AEI framework-type, and more preferably
the molar ratio of CHA to AEI is greater than 1:1.
[0024] Molecular Sieve Synthesis
[0025] 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, and are placed
in a sealed pressure vessel, optionally lined with an inert plastic
such as polytetrafluoroethylene, and heated, under a crystallization
pressure and temperature, at static or stirred conditions, until
a crystalline material is formed in a synthesis mixture. Then, in
a commercial process in particular, one or more flocculant(s) is
added to the synthesis mixture. A liquid portion of the synthesis
mixture is removed, decanted, or reduced in quantity. The remaining
synthesis mixture containing the crystalline molecular sieve is
then, optionally, contacted with the same or a different fresh liquid,
typically with water, in a washing step, from once to many times
depending on the desired purity of the supernatant, liquid portion,
of the synthesis mixture being removed. It is also optional to repeat
this process by adding in additional flocculent followed by additional
washing steps. Then, the crystallized molecular sieve is recovered
by filtration, centrifugation and/or decanting. Preferably, the
molecular sieve is filtered using a filter that provides for separating
certain crystal sized molecular sieve particles from any remaining
liquid portion that may contain different size molecular sieve crystals.
[0026] In a preferred embodiment the molecular sieves are synthesized
by forming a reaction product or synthesis mixture of a source of
silicon, a source of aluminum, a source of phosphorous and an organic
templating agent, preferably a nitrogen containing organic templating
agent. This particularly preferred embodiment results in the synthesis
of a silicoaluminophosphate crystalline material in a synthesis
mixture. One or more flocculants are added to the synthesis mixture,
and the crystallized molecular sieve is then removed or isolated
by filtration, centrifugation and/or decanting.
[0027] Non-limiting examples of silicon sources include a silicates,
fumed silica, for example, Aerosil-200 available from Degussa Inc.,
New York, N.Y., and CAB-O-SIL M-5 silicon compounds such as tetraalkyl
orthosilicates, for example, tetramethyl orthosilicate (TMOS) and
tetraethylorthosilicate (TEOS), colloidal silicas or aqueous suspensions
thereof, for example Ludox-HS-40 sol available from E.I. du Pont
de Nemours, Wilmington, Del., silicic acid, alkali-metal silicate,
or any combination thereof. The preferred source of silicon is a
silica sol.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] The quaternary ammonium compounds, in one embodiment, are
represented by the general formula R.sub.4N.sup.+, where each R
is hydrogen or a hydrocarbyl or substituted hydrocarbyl group, preferably
an alkyl group or an aryl group having from 1 to 10 carbon atoms.
In one embodiment, the templating agents include a combination of
one or more quaternary ammonium compound(s) and one or more of a
mono-, di- or tri-amine.
[0032] Non-limiting examples of templating agents include tetraalkyl
ammonium compounds including salts thereof such as tetramethyl ammonium
compounds including salts thereof. The preferred templating agent
or template is a tetraethylammonium compound, tetraethyl ammonium
hydroxide (TEAOH) and salts thereof, particularly when producing
a SAPO molecular sieve.
[0033] Flocculants
[0034] When commercially synthesizing any of the molecular sieves
discussed above, typically one or more chemical reagents are added
to the crystallization vessel or synthesis reactor after crystallization
is substantially complete, preferably complete. Optionally, in another
embodiment, the synthesis mixture is transferred to another vessel
separate from the reaction vessel or the vessel in which crystallization
occurs, and a flocculant is then added to this other vessel from
which the crystalline molecular sieve is ultimately recovered. These
chemical reagents or flocculants are used to increase the recovery
rate of the molecular sieve crystals and increase the yield of the
synthesized molecular sieve crystals. While not wishing to be bound
to any particular theory, these flocculants act either as (1) a
surface charge modifier that results in the agglomeration of very
small particles into larger aggregates of molecular sieve particles;
or (2) surface anchors that bridge many small particles to form
aggregates of molecular sieve particles. The aggregates of the molecular
sieve crystals are then easily recovered by well known techniques
such as filtration or through a filter press process.
[0035] Flocculants can be added at any point during or with any
other source or templating agent used in the synthesis of any one
of the molecular sieves discussed above. In one embodiment, flocculants
are added to a molecular sieve synthesis mixture comprising one
or more of a silicon source, a phosphorous source, an aluminum source,
and a templating agent depending on the molecular sieve being synthesized.
In the most preferred embodiment, the flocculant is added to the
synthesis mixture after crystallization has occurred from the combination
of one or more of a silicon source, a phosphorous source, an aluminum
source, and a templating agent. The synthesized molecular sieve
is then recovered by filtration, however, optionally, the synthesized
molecular sieve is washed and additional flocculant is used to further
aggregate any remaining synthesized molecular sieve from the liquid
portion of the synthesis mixture.
[0036] There are many types of flocculants both inorganic and organic
flocculants. Inorganic flocculants are typically aluminum or iron
salts that form insoluble hydroxide precipitates in water. Non-limiting
examples such as aluminum sulfate, poly (aluminum chloride), sodium
aluminate, iron (III)-chloride, sulfate, and sulfate-chloride, iron
(II) sulfate, and sodium silicate (activated silica). The major
classes of flocculants are: (1) nonionic flocculant, for example,
polyethylene oxide, polyacrylamide (PAM), partially hydrolyzed polyacrylamide
(HPAM), and dextran; (2) cationic flocculant, for example, polyethyleneimine
(PEI), polyacrylamide-co-trimethylammonium, ethyl methyl acrylate
chloride (PTAMC), and poly (N-methyl-4-vinylpyridinium iodide);
and (3) anionic flocculant, for example, poly (sodium acrylate),
dextran sulfates, alum (aluminum sulfate), and/or high molecular
weight ligninsulfonates prepared by a condensation reaction of formaldehyde
with ligninsulfonates, and polyacrylamide. In a preferred embodiment,
where the synthesis mixture includes the presence of water, it is
preferable that the flocculant used is water soluble. Additional
information on flocculation is discussed in T. C. Patton, Paint
Flow and Pigment Dispersion-A Rheological Approach to Coating and
Ink Technology, 2nd Edition, John Wiley & Sons, New York, p.
270 1979 which is fully incorporated by reference.
[0037] In another embodiment, the flocculant is added to the synthesis
mixture after crystallization in an amount of 0.01 to 10 wt % flocculant
based on expected solid molecular sieve product yield, preferably
between 0.05 to 5 wt % flocculant based on expected solid molecular
sieve product yield, more preferably from 0.05 to 3 wt % based on
expected solid molecular sieve product yield. In yet another embodiment,
it is preferable that the product slurry and/or flocculant are diluted
to obtain a volume of product slurry to volume of flocculant of
between 1:1 and 10:1. Good mixing between the product slurry and
the flocculant is also preferred. One can recover the flocculated
sieve starting from the total mixture by centrifugation or filtration
or one can allow the mixture to settle, decant the liquid, re-slurry
with water, eventually repeatedly decant and re-slurry, and finally
recover by centrifugation or filtration. The settling of the sieve
can take from seconds to days; however, the settling can be accelerated
by adding additional flocculant. The flocculant is typically added
to the slurry at room temperature, and is preferably added as a
solution. Should a solid flocculant be used then it is preferable
that a substantially homogeneous flocculant solution is prepared
by dissolving the solid flocculant in a medium.
[0038] In one preferred embodiment, the flocculant is a polymeric
imine such as polyethyleneimine. In another preferred embodiment,
the flocculant is represented by the formula: (R--NH).sub.x, where
(R--NH) is a polymeric or monomeric unit where R contains from 1
to 20 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably
from 1 to 6 carbon atoms, and most preferably from 1 to 4 carbon
atoms; x is an integer from 1 to 500000.
[0039] In yet another embodiment, the flocculant is a polyethylenimine
that is represented by the following general formula: (--NHCH.sub.2CH.sub.2--).sub.m[--N(CH.sub.2CH.sub.2NH.sub.2)CH.sub.2CH.su-
b.2--]), wherein m is from 10 to 20000 and n is from 0 to 2000
preferably from 1 to 2000.
[0040] In another embodiment, the flocculant of the invention,
preferably a polyethyleneimine, has an average molecular weight
from about 500 to about 1000000 preferably from about 10000
to about 800000 more preferably from about 20000 to about 750000
and most preferably from about 50000 to about 750000.
[0041] Non-limiting examples of polyethylenimine flocculants include:
epichlorohydrin modified polyethylenimine, ethoxylated polyethylenimine,
polypropylenimine diamine dendrimers (DAB-Am-n), poly (allylamine)
[CH.sub.2CH(CH.sub.2NH.sub.2)].sub.n, poly (12-dihydro-224-trimethylqu-
inoline), and poly (dimethylamine-co-epichlorohydrin-co-ethylenediamine).
[0042] In one embodiment, the flocculant is in an a solution, preferably
an aqueous solution. In a further embodiment, the flocculant in
the aqueous solution is diluted with water. Without being bound
to any particular theory, it has been found that dilution of the
molecular sieve slurry, preferably one recovered using a flocculant,
prevents dissolution of the molecular sieve in the slurry. This
benefit provides for a further improvement in yield, and allows
for the slurry to be stored for an extended period of time.
[0043] A synthesis mixture comprising a molecular sieve and a flocculant
has a pH depending on the composition of the molecular sieve. In
a preferred embodiment, the synthesis mixture has a pH in the range
of from 2 to 10 preferably in the range of from 4 to 9 and most
preferably in the range of from 5 to 8. Generally, the synthesis
mixture 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
molecular sieve is typically from immediately up to several weeks,
the duration of which is usually dependent on the temperature; the
higher the temperature the shorter the duration. Typically, the
crystalline molecular sieve product is formed, usually in a slurry
state, and then a flocculant is introduced to this slurry, the synthesis
mixture. The crystalline molecular sieve is then recovered by any
standard technique well known in the art, for example centrifugation
or filtration. Alternatively, in another embodiment, the flocculant
is introduced into the synthesis mixture directly.
[0044] Determination of the percentage of liquid or liquid medium
and the percentage of flocculant and/or template for purposes of
this patent specification and appended claims uses a Thermal Gravimetric
Analysis (TGA) technique as follows: An amount of a molecular sieve
material, the sample, is loaded into a sample pan of a Cahn TG-121
Microbalance, available from Cahn Instrument, Inc., Cerritos, Calif.
During the TGA technique, a flow of 114 cc/min (STP) air was used.
The sample is then heated from 25.degree. C. to 180.degree. C. at
30.degree. C./min, held at 180.degree. C. for 3 hours or until the
weight of this sample becomes constant. The weight loss the percentage
to the starting molecular sieve material is then treated 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).
[0045] In one embodiment, the isolated or separated crystalline
product, the synthesized molecular sieve, is washed, typically using
a liquid such as water, from one to many times, or in a semi-continuous
or continuous way for variable lengths of time. The washed crystalline
product is then optionally dried, preferably in air to a level such
that the resulting, partially dried or dried crystalline product
or synthesized molecular sieve has a LOI in the range of from about
0 weight percent to about 80 weight percent, 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] The amount of flocculant introduced to the reactor vessel
depends on the quantity of molecular sieve being recovered, the
type of molecular sieve, the pH of the synthesis mixture, etc. In
one embodiment, the amount of molecular sieve recovered is the range
of from about 100 Kg to about 20000 Kg or greater, preferably in
the range of from 250 Kg to about 20000 Kg, more preferably from
about 500 Kg to about 20000 Kg, and most preferably from about
1000 Kg to about 20000 Kg. In another embodiment, the reactor vessel
is capable of synthesizing an amount of molecular sieve in one batch
or at one time in the range from about 100 Kg to about 20000 Kg
or greater, preferably greater than about 250 Kg to about 20000
Kg, more preferably from about 500 Kg to about 20000 Kg, and most
preferably from about 1000 Kg to about 20000 Kg.
[0047] Method for Making Molecular Sieve Catalyst Compositions
[0048] Once the molecular sieve is synthesized and heat treated
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), preferably after being thermally treated, with
a binder, and optionally, but preferably, with a matrix material
to form a formulated molecular sieve catalyst composition. It has
been found that when thermally treating a synthesized molecular
sieve having been recovered in the presence of a flocculant, prior
to formulation, maintains or improves the formulated molecular sieve
catalyst composition's resistance to attrition in various conversion
processes.
[0049] This formulated composition is formed into useful shape
and sized particles by well-known techniques such as spray drying,
pelletizing, extrusion, and the like, spray drying being the most
preferred. It is also preferred that after spray drying for example
that the formulated molecular sieve catalyst composition is then
calcined.
[0050] 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.
[0051] 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.24C.sub.17.12(H.sub.2O)
as is described in G. M. Wolterman, et al., Stud. Surf. Sci. and
Catal., 76 pages 105-144 (1993), which is herein incorporated by
reference. In another embodiment, the binders are alumina sols,
predominantly comprising aluminum oxide, optionally including some
silicon. In yet another embodiment, the binders are peptized alumina
made by treating alumina hydrates such as pseudobohemite, with an
acid, preferably an acid that does not contain a halogen, to prepare
sols or aluminum ion solutions. Non-limiting examples of commercially
available colloidal alumina sols include Nalco 8676 available from
Nalco Chemical Co., Naperville, Ill., and Nyacol AL20DW, available
from Nyacol Nano Technologies, Inc., Ashland, Mass.
[0052] 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.
[0053] Non-limiting examples of matrix materials include one or
more of: rare earth metals, non-active, metal oxides including titania,
zirconia, magnesia, thoria, beryllia, quartz, silica or sols, and
mixtures thereof, for example silica-magnesia, silica-zirconia,
silica-titania, silica-alumina and silica-alumina-thoria. In an
embodiment, matrix materials are natural clays such as those from
the families of montmorillonite and kaolin. These natural clays
include sabbentonites and those kaolins known as, for example, Dixie,
McNamee, Georgia and Florida clays. In one embodiment, the matrix
material, preferably any of the clays, are subjected to well known
modification processes such as calcination and/or acid treatment
and/or chemical treatment. In one preferred embodiment, the matrix
material is kaolin, particularly kaolin having an average particle
size 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.
[0054] Upon combining the heat treated 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 heat
treated 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.
[0055] The liquid containing the heat treated 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.
[0056] 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 more preferably
in the range of from 0.11 to 0.48 even more preferably from 0.12
to about 0.45 yet even more preferably from 0.13 to less than 0.45
and most preferably in the range of from 0.15 to about 0.4. See
for example U.S. patent application Ser. No. 10/178455 filed Jun.
24 2002 which is herein fully incorporated by reference.
[0057] The molecular sieve catalyst composition particles contains
some water, templating agent or other liquid components, therefore,
the weight percents that describe the solid content in the slurry
are preferably expressed in terms exclusive of the amount of water,
templating agent and/or other liquid contained within the particle.
The most preferred condition for measuring solids content is on
a calcined basis as, for example, as measured by the LOI procedure
discussed above. 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. See for example U.S. Patent Application
Publication No. U.S. 2003/0018228 published Jan. 23 2003 which
is herein fully incorporated by reference.
[0058] In another embodiment, the heat treated molecular sieve
is combined with a binder and/or a matrix material forming a slurry
such that the pH of the slurry is above or below the isoelectric
point of the molecular sieve. Preferably the slurry comprises the
molecular sieve, the binder and the matrix material and has a pH
different from, above or below, preferably below, the IEP of the
molecular sieve, the binder and the matrix material. In an embodiment,
the pH of the slurry is in the range of from 2 to 7 preferably
from 2.3 to 6.2; the IEP of the molecular sieve is in the range
of from 2.5 to less than 7 preferably from about 3.5 to 6.5; the
IEP of the binder is greater than 10; and the IEP of the matrix
material is less than 2. See PCT Patent Publication WO 03/000412
A1 published Jan. 3 2003 which is herein fully incorporated by
reference.
[0059] 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,
preferably less than 15 .mu.m, more preferably less than 10 .mu.m,
and most preferably about 7 .mu.m. The d.sub.90 for purposes of
this patent application and appended claims means that 90 percent
by volume of the particles in the slurry have a particle diameter
lower than the d.sub.90 value. For the purposes of this definition,
the particle size distribution used to define the d.sub.90 is measured
using well known laser scattering techniques using a Honeywell (Microtrac
Model 3000 particle size analyzer from Microtrac, Inc., Largo, Florida).
[0060] 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 a spray dryer. Typically,
the forming unit is maintained at a temperature sufficient to remove
most of the liquid from the slurry, and from the resulting molecular
sieve catalyst composition. The resulting catalyst composition when
formed in this way takes the form of microspheres.
[0061] 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.
[0062] During spray drying, the slurry is passed through a nozzle
distributing the slurry into small droplets, resembling an aerosol
spray into a drying chamber. Atomization is achieved by forcing
the slurry through a single nozzle or multiple nozzles with a pressure
drop in the range of from 100 psia to 1000 psia (690 kpaa to 6895
kpaa). In another embodiment, the slurry is co-fed through a single
nozzle or multiple nozzles along with an atomization fluid such
as air, steam, flue gas, or any other suitable gas. Generally, the
size of the microspheres is controlled to some extent by the solids
content of the slurry. However, control of the size of the catalyst
composition and its spherical characteristics are controllable by
varying the slurry feed properties and conditions of atomization.
[0063] Other methods for forming a molecular sieve catalyst composition
is described in U.S. Pat. No. 6509290 (spray drying using a recycled
molecular sieve catalyst composition), which is herein incorporated
by reference.
[0064] In a preferred embodiment, once the molecular sieve catalyst
composition is formed, to further harden and/or activate the formed
catalyst composition, the spray dried molecular sieve catalyst composition
or formulated molecular sieve catalyst composition is calcined.
Typical calcination temperatures are in the range of from about
500.degree. C. to about 800.degree. C., and 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. Calcination
time is typically dependent on the degree of hardening of the molecular
sieve catalyst composition and ranges from about 15 minutes to about
20 hours at a temperature in the range of from 500.degree. C. to
700.degree. C.
[0065] In one embodiment, the attrition resistance of a molecular
sieve catalyst composition is measured using an Attrition Rate Index
(AR1), measured in weight percent catalyst composition attrited
per hour. AR1 is measured by adding 6.0 g of catalyst composition
having a particle size distribution 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
in grams 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.
[0066] In one embodiment, the molecular sieve catalyst composition
or formulated molecular sieve catalyst composition has an ARI less
than 10 weight percent per hour, preferably less than 5 weight percent
per hour, more preferably less than 2 weight percent per hour, and
most preferably less than 1 weight percent per hour.
[0067] Process For Using the Molecular Sieve Catalyst Compositions
[0068] The molecular sieve catalyst compositions described above
are useful in a variety of processes including: cracking, of for
example a naphtha feed to light olefin(s) (U.S. Pat. No. 6300537)
or higher molecular weight (MW) hydrocarbons to lower MW hydrocarbons;
hydrocracking, of for example heavy petroleum and/or cyclic feedstock;
isomerization, of for example aromatics such as xylene, polymerization,
of for example one or more olefin(s) to produce a polymer product;
reforming; hydrogenation; dehydrogenation; dewaxing, of for example
hydrocarbons to remove straight chain paraffins; absorption, of
for example alkyl aromatic compounds for separating out isomers
thereof; alkylation, of for example aromatic hydrocarbons such as
benzene and alkyl benzene, optionally with propylene to produce
cumeme or with long chain olefins; transalkylation, of for example
a combination of aromatic and polyalkylaromatic hydrocarbons; dealkylation;
hydrodecylization; disproportionation, of for example toluene to
make benzene and paraxylene; oligomerization, of for example straight
and branched chain olefin(s); and dehydrocyclization.
[0069] 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).
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] The various feedstocks discussed above, particularly a feedstock
containing an oxygenate, more particularly a feedstock containing
an alcohol, is converted primarily into one or more olefin(s). The
olefin(s) or olefin monomer(s) produced from the feedstock typically
have from 2 to 30 carbon atoms, preferably 2 to 8 carbon atoms,
more preferably 2 to 6 carbon atoms, still more preferably 2 to
4 carbons atoms, and most preferably ethylene and/or propylene.
Non-limiting examples of olefin monomer(s) include ethylene, propylene,
butene-1 pentene-14-methyl-pent- ene-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.
[0075] 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.
[0076] The are many processes used to convert feedstock into olefin(s)
including various cracking processes such as steam cracking, thermal
regenerative cracking, fluidized bed cracking, fluid catalytic cracking,
deep catalytic cracking, and visbreaking. The most preferred process
is generally referred to as gas-to-olefins (GTO) or alternatively,
oxygenate-to-olefins (OTO) or methanol-to-olefins (MTO). In a MTO
or an OTO process, typically an oxygenated feedstock, most preferably
a methanol containing feedstock, is converted in the presence of
a molecular sieve catalyst composition into one or more olefin(s),
preferably and predominantly, ethylene and/or propylene, often referred
to as light olefin(s).
[0077] 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.
[0078] 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.
[0079] The reaction processes can take place in a variety of catalytic
reactors such as hybrid reactors that have a dense bed or fixed
bed reaction zones and/or fast fluidized bed reaction zones coupled
together, circulating fluidized bed reactors, riser reactors, and
the like. Suitable conventional reactor types are described in for
example U.S. Pat. No. 4076796 U.S. Pat. No. 6287522 (dual riser),
and Fluidization Engineering, D. Kunii and O. Levenspiel, Robert
E. Krieger Publishing Company, New York, N.Y. 1977 which are all
herein fully incorporated by reference. The preferred reactor type
are riser reactors generally described in Riser Reactor, Fluidization
and Fluid-Particle Systems, pages 48 to 59 F. A. Zenz and D. F.
Othmer, Reinhold Publishing Corporation, New York, 1960 and U.S.
Pat. No. 6166282 (fast-fluidized bed reactor), and U.S. patent
application Ser. No. 09/564613 filed May 4 2000 (multiple riser
reactor), which are all herein fully incorporated by reference.
[0080] 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.
[0081] Reactor System
[0082] 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.
[0083] The feedstock entering the reactor system is preferably
converted, partially or fully, in the first reactor zone into a
gaseous effluent that enters the disengaging vessel along with a
coked or further coked molecular sieve catalyst composition. In
the preferred embodiment, cyclone(s) within the disengaging vessel
are designed to separate the molecular sieve catalyst composition,
preferably a coked or further coked molecular sieve catalyst composition,
from the gaseous effluent containing one or more olefin(s) within
the disengaging zone. Cyclones are preferred, however, gravity effects
within the disengaging vessel will also separate the catalyst compositions
from the gaseous effluent. Other methods for separating the catalyst
compositions from the gaseous effluent include the use of plates,
caps, elbows, and the like.
[0084] 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.
[0085] 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.
[0086] 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.
[0087] The weight hourly space velocity (WHSV), particularly in
a process for converting a feedstock containing one or more oxygenates
in the presence of a molecular sieve catalyst composition within
a reaction zone, is defined as the total weight of the feedstock
excluding any diluents to the reaction zone per hour per weight
of molecular sieve in the molecular sieve catalyst composition in
the reaction zone. The WHSV is maintained at a level sufficient
to keep the catalyst composition in a fluidized state within a reactor.
Typically, the WHSV 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-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.
[0088] 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. Other processes for converting an oxygenate
to olefin(s) are described in U.S. Pat. No. 5952538 (WHSV of at
least 20 hr.sup.-1 and a Temperature Corrected Normalized Methane
Selectivity (TCNMS) of less than 0.016), EP-0 642 485 B1 (WHSV is
from 0.01 hr.sup.-1 to about 100 hr.sup.-1 at a temperature of
from about 350.degree. C. to 550.degree. C.), and PCT WO 01/23500
published Apr. 5 2001 (propane reduction at an average catalyst
feedstock exposure of at least 1.0), which are all herein fully
incorporated by reference.
[0089] 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.
[0090] Regeneration System
[0091] The regeneration system comprises a regenerator where the
coked catalyst composition is contacted with a regeneration medium,
preferably a gas containing oxygen, under general regeneration conditions
of temperature, pressure and residence time. Non-limiting examples
of the regeneration medium include one or more of oxygen, O.sub.3
SO.sub.3 N.sub.2O, NO, NO.sub.2 N.sub.2O.sub.5 air, air diluted
with nitrogen or carbon dioxide, oxygen and water (U.S. Pat. No.
6245703), carbon monoxide and/or hydrogen. The regeneration conditions
are those capable of burning coke from the coked catalyst composition,
preferably to a level less than 0.5 weight percent based on the
total weight of the coked molecular sieve catalyst composition entering
the regeneration system. The coked molecular sieve catalyst composition
withdrawn from the regenerator forms a regenerated molecular sieve
catalyst composition. By controlling the flow of the regenerated
molecular sieve catalyst composition or cooled regenerated molecular
sieve catalyst composition from the regeneration system to the reactor
system, the optimum level of coke on the molecular sieve catalyst
composition entering the reactor is maintained. There are many techniques
for controlling the flow of a molecular sieve catalyst composition
described in Michael Louge, Experimental Techniques, Circulating
Fluidized Beds, Grace, Avidan and Knowlton, eds., Blackie, 1997
(336-337), which is herein incorporated by reference.
[0092] 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.
[0093] Other regeneration processes are described in U.S. Pat.
No. 6023005 (coke levels on regenerated catalyst), U.S. Pat. No.
6245703 (fresh molecular sieve added to regenerator) and U.S.
Pat. No. 6290916 (controlling moisture), U.S. patent application
Ser. No. 09/587766 filed Jun. 6 2000 (cooled regenerated catalyst
returned to regenerator), U.S. patent application Ser. No. 09/785122
filed Feb. 16 2001 (regenerated catalyst contacted with alcohol),
and PCT WO 00/49106 published Aug. 24 2000 (cooled regenerated
catalyst contacted with by-products), which are all herein fully
incorporated by reference.
[0094] The gaseous effluent is withdrawn from the disengaging system
and is passed through a recovery system.
[0095] Recovery System
[0096] There are many well known recovery systems, techniques and
sequences that are useful in separating olefin(s) and purifying
olefin(s) from the gaseous effluent. Recovery systems generally
comprise one or more or a combination of a various separation, fractionation
and/or distillation towers, columns, splitters, or trains, reaction
systems such as ethylbenzene manufacture (U.S. Pat. No. 5476978)
and other derivative processes such as aldehydes, ketones and ester
manufacture (U.S. Pat. No. 5675041), and other associated equipment
for example various condensers, heat exchangers, refrigeration systems
or chill trains, compressors, knock-out drums or pots, pumps, and
the like. Non-limiting examples of these towers, columns, splitters
or trains used alone or in combination include one or more of a
demethanizer, preferably a high temperature demethanizer, a dethanizer,
a depropanizer, preferably a wet depropanizer, a wash tower often
referred to as a caustic wash tower and/or quench tower, absorbers,
adsorbers, membranes, ethylene (C2) splitter, propylene (C3) splitter,
butene (C4) splitter, and the like.
[0097] Various recovery systems useful for recovering predominately
olefin(s), preferably prime or light olefin(s) such as ethylene,
propylene and/or butene are described in U.S. Pat. No. 5960643
(secondary rich ethylene stream), U.S. Pat. Nos. 5019143 5452581
and 5082481 (membrane separations), U.S. Pat. No. 5672197 (pressure
dependent adsorbents), U.S. Pat. No. 6069288 (hydrogen removal),
U.S. Pat. No. 5904880 (recovered methanol to hydrogen and carbon
dioxide in one step), U.S. Pat. No. 5927063 (recovered methanol
to gas turbine power plant), and U.S. Pat. No. 6121504 (direct
product quench), U.S. Pat. No. 6121503 (high purity olefins without
superfractionation), and U.S. Pat. No. 6293998 (pressure swing
adsorption), which are all herein fully incorporated by reference.
[0098] In particular with a conversion process of oxygenates into
olefin(s) utilizing a molecular sieve catalyst composition the resulting
effluent gas typically comprises a majority of ethylene and/or propylene
and a minor amount of four carbon and higher carbon number products
and other by-products, excluding water. In one embodiment, high
purity ethylene and/or high purity propylene is produced by the
process of the invention at a rate greater than 4500 kg per day,
preferably greater than 100000 kg per day, more preferably greater
than 500000 kg per day, even more preferably greater than 1000000
kg per day, yet even more preferably greater than 1500000 kg per
day, still even more preferably greater than 2000000 kg per day,
and most preferably greater than 2500000 kg per day.
[0099] Generally accompanying most recovery systems is the production,
generation or accumulation of additional products, by-products and/or
contaminants along with the preferred prime products. The preferred
prime products, the light olefins, such as ethylene and propylene,
are typically purified for use in derivative manufacturing processes
such as polymerization processes. Therefore, in the most preferred
embodiment of the recovery system, the recovery system also includes
a purification system to remove various non-limiting examples of
contaminants and by-products include generally polar compounds such
as water, alcohols, carboxylic acids, ethers, carbon oxides, ammonia
and other nitrogen compounds, chlorides, hydrogen and hydrocarbons
such as acetylene, methyl acetylene, propadiene, butadiene and butyne.
[0100] Other recovery systems that include purification systems,
for example for the purification of olefin(s), are described in
Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, Volume
9 John Wiley & Sons, 1996 pages 249-271 and 894-899 which
is herein incorporated by reference. Purification systems are also
described in for example, U.S. Pat. No. 6271428 (purification
of a diolefin hydrocarbon stream), U.S. Pat. No. 6293999 (separating
propylene from propane), and U.S. patent application Ser. No. 09/689363
filed Oct. 20 2000 (purge stream using hydrating catalyst), which
is herein incorporated by reference.
[0101] Included in the recovery systems of the invention are reaction
systems for converting the products contained within the effluent
gas withdrawn from the reactor or converting those products produced
as a result of the recovery system utilized. Suitable well known
reaction systems as part of the recovery system primarily take lower
value products such as the C.sub.4 hydrocarbons, butene-1 and butene-2
and convert them to higher value products. Non-limiting examples
of these types of reaction systems include U.S. Pat. No. 5955640
(converting a four carbon product into butene-1), U.S. Pat. No.
4774375 (isobutane and butene-2 oligomerized to an alkylate gasoline),
U.S. Pat. No. 6049017 (dimerization of n-butylene), U.S. Pat.
Nos. 4287369 and 5763678 (carbonylation or hydroformulation
of higher olefins with carbon dioxide and hydrogen making carbonyl
compounds), U.S. Pat. No. 4542252 (multistage adiabatic process),
U.S. Pat. No. 5634354 (olefin-hydrogen recovery), and Cosyns,
J. et al., Process for Upgrading C.sub.3 C.sub.4 and C.sub.5 Olefinic
Streams, Pet. & Coal, Vol. 37 No. 4 (1995) (dimerizing or oligomerizing
propylene, butylene and pentylene), which are all herein fully incorporated
by reference.
[0102] Other conversion processes, in particular, a conversion
process of an oxygenate to one or more olefin(s) in the presence
of a molecular sieve catalyst composition, especially where the
molecular sieve is synthesized from a silicon-, phosphorous-, and
alumina-source, include those described in for example: U.S. Pat.
No. 6121503 (making plastic with an olefin product having a paraffin
to olefin weight ratio less than or equal to 0.05), U.S. Pat. No.
6187983 (electromagnetic energy to reaction system), PCT WO 99/18055
publishes Apr. 15 1999 (heavy hydrocarbon in effluent gas fed to
another reactor) PCT WO 01/60770 published Aug. 23 2001 and U.S.
patent application Ser. No. 09/627634 filed Jul. 28 2000 (high
pressure), U.S. patent application Ser. No. 09/507838 filed Feb.
22 2000 (staged feedstock injection), and U.S. patent application
Ser. No. 09/785409 filed Feb. 16 2001 (acetone co-fed), which
are all herein fully incorporated by reference.
[0103] Integrated Processes
[0104] In an embodiment, an integrated process is directed to producing
light olefin(s) from a hydrocarbon feedstock, preferably a hydrocarbon
gas feedstock, more preferably methane and/or ethane. The first
step in the process is passing the gaseous feedstock, preferably
in combination with a water stream, to a syngas production zone
to produce a synthesis gas (syngas) stream. Syngas production is
well known, and typical syngas temperatures are in the range of
from about 700.degree. C. to about 1200.degree. C. and syngas pressures
are in the range of from about 2 MPa to about 100 MPa. Synthesis
gas streams are produced from natural gas, petroleum liquids, and
carbonaceous materials such as coal, recycled plastic, municipal
waste or any other organic material, preferably synthesis gas stream
is produced via steam reforming of natural gas. Generally, a heterogeneous
catalyst, typically a copper based catalyst, is contacted with a
synthesis gas stream, typically carbon dioxide and carbon monoxide
and hydrogen to produce an alcohol, preferably methanol, often in
combination with water. In one embodiment, the synthesis gas stream
at a synthesis temperature in the range of from about 150.degree.
C. to about 450.degree. C. and at a synthesis pressure in the range
of from about 5 MPa to about 10 MPa is passed through a carbon oxide
conversion zone to produce an oxygenate containing stream.
[0105] This oxygenate containing stream, or crude methanol, typically
contains the alcohol product and various other components such as
ethers, particularly dimethyl ether, ketones, aldehydes, dissolved
gases such as hydrogen methane, carbon oxide and nitrogen, and fusel
oil. The oxygenate containing stream, crude methanol, in the preferred
embodiment is passed through a well known purification processes,
distillation, separation and fractionation, resulting in a purified
oxygenate containing stream, for example, commercial Grade A and
AA methanol. The oxygenate containing stream or purified oxygenate
containing stream, optionally with one or more diluents, is contacted
with one or more molecular sieve catalyst composition described
above in any one of the processes described above to produce a variety
of prime products, particularly light olefin(s), ethylene and/or
propylene. Non-limiting examples of this integrated process is described
in EP-B-0 933 345 which is herein fully incorporated by reference.
In another more fully integrated process, optionally with the integrated
processes described above, olefin(s) produced are directed to, in
one embodiment, one or more polymerization processes for producing
various polyolefins. (See for example U.S. patent application Ser.
No. 09/615376 filed Jul. 13 2000 which is herein fully incorporated
by reference.)
[0106] Light Olefin Usage
[0107] The light olefin products, especially the ethylene and the
propylene, are useful in polymerization processes that include solution,
gas phase, slurry phase and a high pressure processes, or a combinations
thereof. Particularly preferred is a gas phase or a slurry phase
polymerization of one or more olefin(s) at least one of which is
ethylene or propylene. These polymerization processes utilize a
polymerization catalyst that can include any one or a combination
of the molecular sieve catalysts discussed above, however, the preferred
polymerization catalysts are those Ziegler-Natta, Phillips-type,
metallocene, metallocene-type and advanced polymerization catalysts,
and mixtures thereof. The polymers produced by the polymerization
processes described above include linear low density polyethylene,
elastomers, plastomers, high density polyethylene, low density polyethylene,
polypropylene and polypropylene copolymers. The propylene based
polymers produced by the polymerization processes include atactic
polypropylene, isotactic polypropylene, syndiotactic polypropylene,
and propylene random, block or impact copolymers.
[0108] In preferred embodiment, the integrated process comprises
a polymerizing process of one or more olefin(s) in the presence
of a polymerization catalyst system in a polymerization reactor
to produce one or more polymer products, wherein the one or more
olefin(s) having been made by converting an alcohol, particularly
methanol, using a molecular sieve catalyst composition. The preferred
polymerization process is a gas phase polymerization process and
at least one of the olefins(s) is either ethylene or propylene,
and preferably the polymerization catalyst system is a supported
metallocene catalyst system. In this embodiment, the supported metallocene
catalyst system comprises a support, a metallocene or metallocene-type
compound and an activator, preferably the activator is a non-coordinating
anion or alumoxane, or combination thereof, and most preferably
the activator is alumoxane.
[0109] In addition to polyolefins, numerous other olefin derived
products are formed from the olefin(s) recovered any one of the
processes described above, particularly the conversion processes,
more particularly the GTO process or MTO process. These include,
but are not limited to, aldehydes, alcohols, acetic acid, linear
alpha olefins, vinyl acetate, ethylene dicholoride and vinyl chloride,
ethylbenzene, ethylene oxide, cumene, isopropyl alcohol, acrolein,
allyl chloride, propylene oxide, acrylic acid, ethylene-propylene
rubbers, and acrylonitrile, and trimers and dimers of ethylene,
propylene or butylenes.
EXAMPLES
[0110] In order to provide a better understanding of the present
invention including representative advantages thereof, the following
examples are offered.
[0111] LOI and ARI are specified in this patent specification.
Example A
[0112] There are numerous methods well known for making molecular
sieves. The following is an example preparation of a molecular sieve,
particularly a silicoaluminophosphate molecular sieve. Procedures
for making a similar molecular sieve used in the examples below
is described in PCT Publication WO 02/070407 published Sep. 12
2002 which is fully incorporated by reference.
[0113] To a solution of 63.94 grams of phosphoric acid (85% in
water) and 51.22 grams of de-mineralized water, 4.15 grams of Ludox
AS 40 (40% silica) was added upon stirring. Then, 116.71 grams of
TEAOH (35% in water) was added. Finally 37.75 grams of pseudoboehmite
alumina (Condea Pural SB) was added together with 6.22 grams of
de-mineralized water. This slurry solution, a synthesis mixture,
had a composition expressed as the molar ratio:
0.1SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/34H.sub.2O
[0114] This synthesis mixture was then mixed until homogeneous
and put into a 300 ml stainless steel autoclave. The autoclave was
mounted on a rotating axis in an oven. The axis was rotated at 60
rpm and the oven was heated in 8 hours to 175.degree. C. The autoclave
was kept at this temperature for 12 hours. After crystallization
a milky suspension with a pH of 10 was obtained, the slurry was
then homogenized before dividing into 3 Parts:
[0115] Comparative Part 1: 50.04 g of the slurry above. No flocculant
was added. Part 2: 50.0 g of the slurry above and 19.26 g prepared
5 wt % PEI (polyethyleneimine) (MW 750000) solution. (Preparation
of 5 wt % PEI solution: 2 g of 50 wt % PEI (Aldrich, MW 750000)
and 18 g of bi-distilled water was mixed with a spatula until homogeneous).
Part 3: 50.02 g of the slurry above and 19.69 g prepared 5 wt %
lower molecular weight PEI (MW 50000 to 60000) solution. (Preparation
of PEI solution: 2.07 g of 50 wt % PEI (Aldrich, MW 50000 to 60000)
and 18.1 g of bi-distilled water was mixed with a spatula until
homogeneous). Parts 2 and 3 with the PEI flocculant immediately
became viscous after addition of the flocculent. Comparative Part
1 and Part 2 were stirred on a magnetic stirrer plate for 25 minutes
before washing. During that time Part 3 was left without stirring
on the bench and allowed to settle. This resulted in a thick white
slurry settling to the bottom with a substantially clear liquid
on top. Then, Part 3 was also stirred and washed.
[0116] Each of Comparative Part 1 Parts 2 and 3 were washed three
(3) times with about 180 g of distilled water for 10 minutes in
a centrifuge at 3500 rpm. The wash water of Comparative Part lwas
hazy while that of Parts 2 and Parts 3 were clear and colorless.
The recovered products, the synthesized molecular sieves, were dried
overnight in air at 120.degree. C. The dried weights of the synthesized
molecular sieves were: Comparative Part 1: 11.81 g, Part 2: 15.15
g and Part 3: 15.05 g.
Example 2
[0117] Conversion Process
[0118] The three synthesized molecular sieves above, Comparative
Part 1 and Parts 2 and 3 were tested in a conversion process where
in the oxygenated feed stock was methanol, and the conversion conditions
were 25 WHSV, 25 psig (172 kPag) pressure, and at a temperature
450.degree. C. The results of which are reported in the following
Table 1.
1 TABLE 1 Comparative Products Part 1 Part 2 Part 3 C2.dbd. (ethylene)
32.34 31.59 31.79 C3.dbd. (propylene) 40.41 41.58 42.38 C2.dbd.
+ C3.dbd. 72.75 73.16 74.17 C3.sup.0 (Propane) 0.77 0.58 0.54 .sup.2C4.sup.+
23.59 23.60 23.04 .sup.1Life Time 19.01 17.15 17.26 .sup.1Life Time
is measured as grams of methanol converted per gram of molecular
sieve. .sup.2C4.sup.+includes butene-1 butene-2 and higher carbon
number hydrocarbons.
[0119] While the present invention has been described and illustrated
by reference to particular embodiments, those of ordinary skill
in the art will appreciate that the invention lends itself to variations
not necessarily illustrated herein. For example, it is contemplated
that one or more molecular sieves are recoverable in the presence
of one or more flocculants. For this reason, then, reference should
be made solely to the appended claims for purposes of determining
the true scope of the present invention. |