Molecular sieve abstract
The invention relates to a catalyst composition, a method of making
the same and its use in the conversion of a feedstock, preferably
an oxygenated feedstock, into one or more olefin(s), preferably
ethylene and/or propylene The catalyst composition comprises a molecular
sieve and at least one oxide of a metal from Group 4 optionally
in combination with at least one metal from Groups 2 and 3 of the
Periodic Table of Elements.
Molecular sieve claims
36. A process for converting a feedstock into one or more olefin(s)
in the presence of a catalyst composition comprising a molecular
sieve and an active Group 4 metal oxide having an uptake of carbon
dioxide at 100.degree. C. of at least 0.03 mg/m.sup.2 of the metal
oxide.
37. The process of claim 36 wherein said metal oxide has an uptake
of carbon dioxide at 100.degree. C. of at least 0.035 mg/m.sup.2
of the metal oxide.
38. The process of claim 36 wherein said metal oxide has an uptake
of carbon dioxide at 100.degree. C. of less than 10 mg/m.sup.2 of
the metal oxide.
39. The process of claim 36 wherein said metal oxide has an uptake
of carbon dioxide at 100.degree. C. of less than 5 mg/m.sup.2 of
the metal oxide.
40. The process of claim 37 and also including at least one of
a binder and a matrix material different from said metal oxide.
41. The process of claim 37 and also including a binder and a matrix
material each being different from one another and from said metal
oxide.
42. The process of claim 41 wherein the binder is an alumina sol.
43. The process of claim 41 wherein the matrix is a clay.
44. The process of claim 36 wherein the catalyst composition has
a Lifetime Enhancement Index (LEI) greater than 1.
45. The process of claim 36 wherein the molecular sieve is synthesized
from reaction mixture comprising at least two of a silicon source,
a phosphorus source and an aluminum source, optionally in the presence
of a templating agent.
46. The process of claim 36 wherein the molecular sieve is a silicoaluminophosphate.
47. The process of claim 36 wherein the catalyst composition also
includes an active Group 2 and/or Group 3 metal oxide.
48. The process of claim 36 wherein the feedstock comprises methanol
and/or dimethylether.
49. A process for converting a feedstock into one or more olefin(s)
in the presence of a molecular sieve catalyst composition comprising
a molecular sieve, a binder, a matrix material and a mixture of
metal oxides different from the binder and the matrix material.
50. The process of claim 49 wherein the mixture of metal oxides
comprises a Group 4 metal oxide in combination with a Group 2 and/or
Group 3 metal oxide.
51. A process for converting feedstock into one or more olefin(s)
in the presence of the catalyst composition prepared by a method
for making the catalyst composiition, the method comprising physically
mixing first particles comprising a molecular sieve with second
particles comprising a Group 4 metal oxide having an uptake of carbon
dioxide at 100.degree. C. of at least 0.03 mg/hr2 of the metal oxide
particles.
52. A process for converting feedstock into one or more olefin(s)
in the presence of a catalyst composition prepared by a method of
making the catalyst composition, the method comprising: (i) synthesizing
a molecular sieve from a reaction mixture comprising at least one
templating agent and at least two of a silicon source, a phosphorus
source and an aluminum source; and (ii) recovering the molecular
sieve synthesized in (i); (iii) forming a hydrated precursor of
a Group 4 metal oxide by precipitation from a solution containing
a source of Group 4 metal ions; (iv) recovering the hydrated precursor
formed in (iii): (v) calcining the hydrated precursor recovered
(iv) to form a calcined Group 4 metal oxide that has an uptake of
carbon dioxide at 100.degree. C. of at least 0.03 mg/m.sup.2 of
the metal oxide; and (vi) physically mixing the molecular sieve
recovered in (i) and the calcined metal oxide produced in (v).
53. A process for producing one or more olefin(s), the process
comprising: (a) introducing a feedstock comprising at least one
oxygenate to a reactor system in the presence of a catalyst composition
comprising a molecular sieve, a binder, a matrix material, and an
active Group 4 metal oxide; (b) withdrawing from the reactor system
an effluent stream containing one or more olefins; and (c) passing
the effluent stream through a recovery system; and (d) recovering
at least the one or more olefin(s).
54. The process of claim 53 wherein the binder is an alumina sol.
55. The process of claim 53 wherein the matrix material is a clay.
56. The process of claim 53 wherein the molecular sieve is a silicoaluminophosphate
molecular sieve and/or an aluminophosphate molecular sieve.
57. The process of claim 53 wherein the active Group 4 metal oxide
is an active zirconium metal oxide or an active haffnium metal oxide
or a mixture thereof.
58. The process of claim 53 wherein the active Group 4 metal oxide
has an uptake of carbon dioxide at 100.degree. C. of at least 0.03
mg/m.sup.2 of the metal oxide.
59. The process of claim 53 wherein the catalyst composition also
includes an active Group 2 and/or Group 3 metal oxide.
60. The process of claim 53 wherein the feedstock comprises methanol
and/or dimethylether.
61. The process of claim 53 wherein the active metal oxide has
a surface area greater than 10 m.sup.2/g.
62. The process of claim 53 wherein the LEI of the catalyst composition
is greater than that for the same catalyst composition without the
active metal oxide.
63. The process of claim 53 wherein the sieve catalyst composition
has an LEI greater than 1.5.
64. An integrated process for making one or more olefin(s), the
integrated process comprising: (a) passing a hydrocarbon feedstock
to a syngas production zone to produce a synthesis gas stream; (b)
contacting the synthesis gas stream with a catalyst to form an oxygenated
feedstock; and (c) converting the oxygenated feedstock into the
one or more olefin(s) in the presence of a molecular sieve catalyst
composition comprising a molecular sieve and an active metal oxide.
65. The integrated process of claim 64 wherein the process further
comprises (d) polymerizing the one or more olefin(s) in the presence
of a polymerization catalyst into a polyolefin.
66. The integrated process of claim 64 wherein the oxygenated feedstock
comprises methanol, the olefin(s) include ethylene and propylene,
and the active metal oxide is an active Group 4 metal oxide having
a surface area greater than 10 m.sup.2/g.
67. The integrated process of claim 66 wherein the Group 4 metal
oxide is an active zirconium oxide.
68. The integrated process of claim 66 wherein the molecular sieve
is a silicoaluminophosphate molecular sieve.
Molecular sieve description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 USC 120
from U.S. Provisional Patent Application Ser. No. 60/360963 filed
Feb. 28 2002 and from U.S. Provisional Patent Application Ser.
No. 60/366012 filed Mar. 20 2002 and is related to U.S. Patent
Application Ser. No. 60/374697 (Attorney Docket 2002B057) filed
concurrently herewith and U.S. patent application Ser. No. 10/215511
(Attorney Docket 2002B106) filed concurrently herewith, the entire
contents of which applications are incorporated herein by reference.
FIELD
[0002] The present invention relates to molecular sieve compositions
and catalysts containing the same, to the synthesis of such compositions
and catalysts and to the use of such compositions and catalysts
in conversion processes to produce olefin(s).
BACKFROUND
[0003] Olefins are traditionally produced from petroleum feedstocks
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 feedstocks. Ethylene
and propylene are important commodity petrochemicals useful in a
variety of processes for making plastics and other chemical compounds.
[0004] The petrochemical industry has known 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 or 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. Other known syngas
production processes include conventional steam reforming, autothermal
reforming, or a combination thereof.
[0005] Methanol, the preferred alcohol for light olefin production,
is typically synthesized from the catalytic reaction of hydrogen,
carbon monoxide and/or carbon dioxide in a 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 process
for converting a feedstock containing methanol into one or more
olefin(s), primarily ethylene and/or propylene, involves contacting
the feedstock with a molecular sieve catalyst composition.
[0006] 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.
[0007] There are many different types of molecular sieve 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 the zeolite, ZSM-5 to convert methanol into
olefin(s); U.S. Pat. No. 4062905 discusses the conversion of methanol
and other oxygenates to ethylene and propylene using crystalline
aluminosilicate zeolites, for example Zeolite T, ZK5 erionite and
chabazite; U.S. Pat. No. 4079095 describes the use of ZSM-34 to
convert methanol to hydrocarbon products such as ethylene and propylene;
and U.S. Pat. No. 4310440 describes producing light olefin(s)
from an alcohol using a crystalline aluminophosphate, often designated
AIPO.sub.4.
[0008] Some of the most useful molecular sieves for converting
methanol to olefin(s) are silicoaluminophosphate molecular sieves.
Silicoaluminophosphate (SAPO) molecular sieves contain a three-dimensional
microporous crystalline framework structure of [SiO.sub.4], [AlO.sub.4]
and [PO.sub.4] corner sharing tetrahedral units. SAPO synthesis
is described in U.S. Pat. No. 4440871 which is herein fully incorporated
by reference. SAPO molecular sieves are generally synthesized by
the hydrothermal crystallization of a reaction mixture of silicon-,
aluminum- and phosphorus- sources and at least one templating agent.
Synthesis of a SAPO molecular sieve, its formulation into a SAPO
catalyst, and its use in converting a hydrocarbon feedstock into
olefin(s), particularly where the feedstock is methanol, are disclosed
in U.S. Pat. Nos. 4499327 4677242 4677243 4873390 5095163
5714662 and 6166282 all of which are herein fully incorporated
by reference.
[0009] Typically, molecular sieves are formed into molecular sieve
catalyst compositions to improve their durability in commercial
conversion processes. These molecular sieve catalyst compositions
are formed by combining the 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.
[0010] Although it is known to use binders and matrix materials
to form molecular sieve catalyst compositions useful in converting
oxygenates into olefin(s), these binders and matrix materials typically
only serve to provide desired physical characteristics to the catalyst
composition, and have little to no effect on conversion and selectivity
of the molecular sieve. It would therefore be desirable to have
an improved molecular sieve catalyst composition having a better
conversion rate, improved olefin selectivity and a longer lifetime.
[0011] U.S. Pat. No. 4465889 describes a catalyst composition
comprising a silicalite molecular sieve impregnated with a thorium,
zirconium, or titanium metal oxide for use in converting methanol,
dimethyl ether, or a mixture thereof into a hydrocarbon product
rich in iso-C.sub.4 compounds.
[0012] U.S. Pat. No. 6180828 discusses the use of a modified
molecular sieve to produce methylamines from methanol and ammonia,
where for example, a silicoaluminophosphate molecular sieve is combined
with one or more modifiers, such as a zirconium oxide, a titanium
oxide, an yttrium oxide, montmorillonite or kaolinite.
[0013] U.S. Pat. No.5417949 relates to a process for converting
noxious nitrogen oxides in an oxygen containing effluent into nitrogen
and water using a molecular sieve and a metal oxide binder, where
the preferred binder is titania and the molecular sieve is an aluminosilicate.
[0014] EP-A-312981 discloses a process for cracking vanadium-containing
hydrocarbon feed streams using a catalyst composition comprising
a physical mixture of a zeolite embedded in an inorganic refractory
matrix material and at least one oxide of beryllium, magnesium,
calcium, strontium, barium or lanthanum, preferably magnesium oxide,
on a silica-containing support material.
[0015] Kang and Inui, Effects of decrease in number of acid sites
located on the external surface of Ni-SAPO-34 crystalline catalyst
by the mechanochemical method, Catalysis Letters 53 pages 171-176
(1998) disclose that the shape selectivity can be enhanced and the
coke formation mitigated in the conversion of methanol to ethylene
over Ni-SAPO-34 by milling ihe catalyst with MgO, CaO, BaO or Cs.sub.2O
on microspherical non-porous silica, with BaO being the most preferred.
[0016] International Publication No. WO 98/29370 discloses the
conversion of oxygenates to olefins over a small pore non-zeolitic
molecular sieve containing a metal selected from the group consisting
of a lanthanide, an actinide, scandium, yttrium, a Group 4 metal,
a Group 5 metal or combinations thereof.
SUMMARY
[0017] In one aspect, the invention resides in a catalyst composition
comprising a molecular sieve and at least one oxide of a metal selected
from Group 4 of the Periodic Table of Elements, wherein said metal
oxide has an uptake of carbon dioxide at 100.degree. C. of at least
0.03 and typically at least 0.035 mg/m.sup.2 of the metal oxide.
[0018] The catalyst composition may also include at least one of
a binder and a matrix material different from said metal oxide.
[0019] The catalyst composition may also include an oxide of a
metal selected from Group 2 and Group 3 of the Periodic Table of
Elements. In one embodiment, the Group 4 metal oxide comprises zirconium
oxide and the Group 2 and/or Group 3 metal oxide comprises one or
more oxides selected from calcium oxide, barium oxide, lanthanum
oxide, yttrium oxide and scandium oxide.
[0020] The molecular sieve conveniently comprises a framework including
at least two tetrahedral units selected from [SiO.sub.4], [AlO.sub.4]
and [PO.sub.4] units, such as a silicoaluminophosphate.
[0021] In another aspect, the invention resides in a molecular
sieve catalyst composition comprising an active Group 4 metal oxide
and a Group 2 and/or a Group 3 metal oxide, a binder, a matrix material,
and a silicoaluminophosphate molecular sieve.
[0022] In another aspect, the invention resides in a method for
making a catalyst composition, the method comprising the step of
physically mixing first particles comprising a molecular sieve with
second particles comprising a Group 4 metal oxide having an uptake
of carbon dioxide at 100.degree. C. of at least 0.03 mg/m.sup.2
of the metal oxide particles.
[0023] In one embodiment, the molecular sieve, a binder and a matrix
material are made into a formulated molecular sieve catalyst composition
that is then contacted, mixed, combined, spray dried, or the like,
with an active Group 4 metal oxide, such as an active zirconium
metal oxide and/or an active hafnium metal oxide, optionally in
the presence of a Group 2 and/or a Group 3 metal oxide.
[0024] In another aspect, the invention resides in a method of
making a catalyst composition, the method comprising:
[0025] (i) synthesizing a molecular sieve from a reaction mixture
comprising at least one templating agent and at least two of a silicon
source, a phosphorus source and an aluminum source; and
[0026] (ii) recovering the molecular sieve synthesized in step
(i);
[0027] (iii) forming a hydrated precursor to a Group 4 metal oxide
by precipitation from a solution containing a source of Group 4
metal metal ions;
[0028] (iv) recovering the hydrated precursor formed in step (iii);
[0029] (v) calcining the hydrated precursor recovered in step (iv)
to form a calcined metal oxide that has an uptake of carbon dioxide
at 100.degree. C. of at least 0.03 mg/m.sup.2 of the metal oxide;
and
[0030] (vi) physically mixing the molecular sieve recovered in
step (i) and the calcined metal oxide of step (v).
[0031] In yet another aspect, the invention is directed to a process
for producing olefin(s) by converting a feedstock, such as an oxygenate,
conveniently an alcohol, for example methanol, in the presence of
any of the above molecular sieve compositions and/or molecular sieve
or formulated molecular sieve catalyst compositions.
[0032] In yet another aspect, the invention is directed to a process
for converting a feedstock into one or more olefin(s) in the presence
of a molecular sieve catalyst composition comprising a molecular
sieve, a binder, a matrix material and a mixture of metal oxides
different from the binder and the matrix material.
[0033] In one embodiment, the catalyst composition has a Lifetime
Enhancement Index (LEI) greater than 1 such as greater than 1.5.
LEI is defined herein as the ratio of the lifetime of the catalyst
composition to that of the same catalyst composition in the absence
of an active metal oxide.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Introduction
[0034] The invention is directed to a molecular sieve catalyst
composition and to its use in the conversion of hydrocarbon feedstocks,
particularly oxygenated feedstocks, into olefin(s). It has been
found that combining a molecular sieve with one or more active metal
oxides results in a catalyst composition with an enhanced olefin
yield and/or a longer lifetime when used in the conversion of feedstocks,
such as oxygenates, more particularly methanol, into olefin(s).
In addition, the resultant catalyst composition tends to bc more
propylene selective and to yield lower amounts of unwanted ethane
and propane, together with other undesirable compounds, such as
aldehydes and ketones, specifically acetaldehyde.
[0035] The preferred active metal oxides are those having a Group
4 metal (for example zirconium and hafnium) from the Periodic Table
of Elements using the IUPAC format described in the CRC Handbook
of Chemistry and Physics, 78th Edition, CRC Press, Boca Raton, Fla.
(1997). In some cases, it is found that improved results are obtained
when the catalyst composition also contains at least one oxide of
a metal selected from Group 2 and/or Group 3 of the Periodic Table
of Elements.
Molecular Sieves
[0036] Molecular sieves have been classified by the Structure Commission
of the International Zeolite Association according to the rules
of thc IUPAC Commission on Zeolite Nomenclature. According to this
classification, framework-type zeolite and zeolite-type molecular
sieves, for which a structure has been established, are assigned
a three letter codc and are described in the Atlas of Zeolite Framework
Types, 5th edition, Elsevier, London, England (2001), which is herein
fully incorporated by reference.
[0037] Crystalline molecular sieves all have a 3-dimensional, four-connected
framework structure of comer-sharing [TO.sub.4] tetrahedra, where
T is any tetrahedrally coordinated cation. 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-typc 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 Bckkum, et al., Introduction
to Zeolite Science and Praclice, Second Completely Revised and Expanded
Edilion, Volume 137 pages 1-67 Elsevier Science, B.V., Amsterdam,
Netherlands (2001).
[0038] Non-limiting examples of 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, HEO, PER, 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 preferred molecular sieves, particularly
for converting an oxygenate containing feedstock into olefin(s),
include AEL, AFY, AEI, BEA, CHA, EDI, FAU, FER, GIS, LTA, LTL, MER,
MFI, MOR, MTT, MWW, TAM and TON. In one preferred embodiment, the
molecular sieve of the invention has an AEI topology or a CHA topology,
or a combination thereof, most preferably a CHA topology.
[0039] 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 and an average pore size in the range of from about 3
.ANG. to 15 .ANG.. In a more preferred embodiment, the molecular
sieves, preferably silicoaluminophosphate molecular sieves, have
8-rings and an average pore size less than about 5 .ANG., such as
in the range of from 3 .ANG. to about 5 .ANG., for example from
3 .ANG. to about 4.5 .ANG., and particularly from 3.5 .ANG. to about
4.2 .ANG..
[0040] Molecular sieves have a molecular framework of one, preferably
two or more comer-sharing [TO4] tetrahedral units, more preferably,
two or more [SiO.sub.4], [AlO.sub.4] and/nr [PO.sub.4] tetrahedral
units, and most preferably [SiO.sub.4], [AlO.sub.4] and [PO.sub.4]
tetrahedral units. These silicon, aluminum, and phnsphorus based
molecular sieves and metal containing derivatives thereof have been
described in detail in numerous publications including for example,
U.S. Pat. No. 4567029 (MeAPO where Me is Mg, Mn, Zn, or Co), U.S.
Pat. No. 4440871 (SAPO), European Patent Application EP-A-0 159
624 (ELAPSO where El is As, Be, B, Cr, Co, Ga, Ge, Fe, Li, Mg, Mn,
Ti or Zn), U.S. Pat. No. 4554143 (FeAPO), U.S. Pat. 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 (AIPO.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 6.156931
(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.
[0041] Other molecular sieves include those described in R. Szostak
Handbook of Molecular Sieves, Van Nostrand Reinhold, New York, N.Y.
(1992), which is herein fully incorporated by reference.
[0042] The more preferred molecular sieves include aluminophosphate
(AIPO) molecular sieves and silicoaluminophosphate (SAPO) molecular
sieves and substituted, preferably metal substituted, AIPO 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 1 of the Periodic Table of
Elements, an alkaline earth metal of Group 2 of the Periodic Table
of Elements, a rarc earth metal of Group 3 of the Periodic Table
of Elcmcnts, including the Lanthanides: lanthanum, cerium, praseodymiwn,
neodymium, samarium, europium, gadolinium, tcrbium, dysprosium,
holmium, erbium, thulium, yttcrbium and lutetium; and scandium or
yttrium, a transition metal of Groups 4 to 12 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.
[0043] 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
[0044] wherein R represents at Icast one templating agent, preferably
an organic templating agent; m is the number of moles of R per mole
of (M.sub.xA.sub.yP.sub.z)O.sub.2 and has a value from 0 to 1 preferably
0 to 0.5 and most preferably firom 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 Groups 1 2 3 4 5 6 7 8 9
10 11 12 13 14 and Lanthanide's of the Periodic Table of Elements,
preferably M is selected from one of the group consisting of Si,
Co, Cr, Cu, Fc, 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 grcater than
or equal to 0.01. In another embodinent, m is greatcr 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.
[0045] Non-limiting examples of SAPO and AIPO molecular sieves
useful herein include one or a combination of SAPO-5 SAPO-8 SAPO-11
SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35 SAPO-36
SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 (U.S. Pat. No. 6162415),
SAPO-47 SAPO-56 AIPO-5 AIPO-11 AIPO-18 AIPO-31 AIPO-34 AIPO-36
AIPO-37 AIPO-46 and metal containing molecular sieves thereof.
Of these, particularly useful molecular sieves are one or a combination
of SAPO-18 SAPO-34 SAPO-35 SAPO-44 SAPO-56 AIPO-18 and AIPO-34
and metal containing derivatives thereof, such as one or a combination
of SAPO-18 SAPO-34 AIPO-34 and AlPO-18 and metal containing derivatives
thereof, and especially one or a combination of SAPO-34 and AIPO-18
and metal containing derivatives thereof.
[0046] In an embodiment, the molecular sieve is an intergrowth
material having two or more distinct crystalline phases within one
molecular sieve composition. In particular, intergrowth molecular
sieves are described in the U.S. patent application Ser. No. 09/924016
filed Aug. 72001 and International Publication No. WO 98/15496
published Apr. 16 1998 both of which are herein fully incorporated
by reference. For example, SAPO-18 AIPO-18 and RUW-18 have an AEI
framework-type, and SAPO-34 has a CHA framework-type. Thus the molecular
sieve used herein may comprise at least one intergrowth phase of
AEI and CHA framework-types, especially where the ratio of CHA fiamework-type
to AEI framework-type, as determined by the DIFFaX method disclosed
in U.S. patent application Ser. No. 09/924106 filed Aug. 7 2001
is greater than 1:1.
Molecular Sieve Synthesis
[0047] 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 phosphorus, a source of silicon
and a templating agent, such as a nitrogen containing organic compound.
Typically, a combination of sources of silicon, aluminum and phosphorus,
optionally with one or more templating agents, is 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 material is formed, and then
recovered by filtration, centrifugation and/or decanting.
[0048] Non-limiting examples of silicon sources include silicates,
fimed silica, for example, Aerosil-200 available from Degussa Inc.,
New York, N.Y., and CAB-O-SIL M-5 organosilicon compounds such
as tetraalkyl orthosilicates, for example, tetramethyl orthosilicate
(TMOS) and tetraethylorthosilicate (TEOS), colloidal silicas or
aqueous suspensions thereof, for example Ludox HS40 sol available
from E.I. du Pont de Nemours, Wilmington, De., silicic acid or any
combination thereof.
[0049] Non-limiting examples of aluminum sources include aluminum
alkoxides, for example aluminum isopropoxide, aluminum phosphate,
aluminum hydroxide, sodium aluminate, pseudo-boehmite, gibbsite
and aluminum trichloride, or any combination thereof. A convenient
source of aluminum is pseudo-boehmite, particularly when producing
a silicoaluminophosphate molecular sieve.
[0050] Non-limiting examples of phosphorus sources, which may also
include aluminum-containing phosphorus compositions, include phosphoric
acid, organic phosphates such as triethyl phosphate, and crystalline
or amorphous aluminophosphates such as AIPO.sub.4 phosphorus salts,
or combinations thereof. A convenient source of phosphorus is phosphoric
acid, particularly when producing a silicoaluminophosphate.
[0051] Templating agents are generally compounds that contain elements
of Group 15 of the Periodic Table of Elements, particularly nitrogen,
phosphorus, arsenic and antimony. Typical templating agents also
contain at least one alkyl or aryl group, such as an alkyl or aryl
group having from 1 to 10 carbon atoms, for example from 1 to 8
carbon atoms. Preferred templating agents are often nitrogen-containing
compounds, such as amines, quaternary ammonium compounds and combinations
thereof. Suitable quaternary ammonium compounds are represented
by the general formula R.sub.4N.sup.+ where each R is hydrogen or
a hydrocarbyl or substituted hydrocarbyl group, preferably an alkyl
group or an aryl group having from 1 to 10 carbon atoms.
[0052] Non-limiting examples of templating agents include tetraalkyl
ammonium compounds including salts thereof, such as tetramethyl
ammonium compounds, tetraethyl ammonium compounds, tetrapropyl ammonium
compounds, and tetrabutylammonium compounds, cyclohexylamine, morpholine,
di-n-propylamine (DPA), tripropylamine, triethylamine (TEA), triethanolamine,
piperidine, cyclohexylamine, 2-methylpyridine, N,N-dimethylbenzylamine,
N,N-diethylethanolamine, dicyclohexylamine, N,N-dimethylethanolamine,
choline, N,N'-dimethylpiperazine, 14-diazabicyclo(222)octane,
N',N',N,N-tetramethyl-(16)hexanediamine, N-methyldiethanolamine,
N-methyl-ethanolamine, N-methyl piperidine, 3-methyl-piperidine,
N-methylcyclohexylamine, 3-methylpyridine, 4-methyl-pyridine, quinuclidine,
N,N'-dimethyl-14-diazabicyclo(222) octane ion; di-n-butylamine,
neopentylamine, di-n-pentylamine, isopropylamine, t-butyl-amine,
ethylenediamine, pyrrolidine, and 2-imidazolidone.
[0053] The pH of the synthesis mixture containing at a minimum
a silicon-, aluminum-, and/or phosphorus- composition, and a templating
agent, is generally in the range of from 2 to 10 such as from 4
to 9 for example from 5 to 8.
[0054] Generally, the synthesis mixture described above is sealed
in a vessel and heated, preferably under autogenous pressure, to
a temperature in the range of from about 80.degree. C. to about
250.degree. C., such as from about 100.degree. C. to about 250.degree.
C., for example from about 125.degree. C. to about 225.degree. C.,
such as from about 150.degree. C. to about 180.degree. C.
[0055] In one embodiment, the synthesis of a molecular sieve is
aided by seeds from another or the same framework type molecular
sieve.
[0056] The time required to form the crystalline product is usually
dependent on the temperature and can vary from immediately up to
several weeks. Typically the crystallization time is from about
30 minutes to around 2 weeks, such as from about 45 minutes to about
240 hours, for example from about 1 hour to about 120 hours. The
hydrothermal crystallization may be carried out with or without
agitation or stirring.
[0057] Once the crystalline molecular sieve product is formed,
usually in a slurry state, it may be recovered by any standard technique
well known in the art, for example, by centrifugation or filtration.
The recovered crystalline product may then be washed, such as with
water, and then dried, such as in air.
[0058] One method for crystallization involves producing an aqueous
reaction mixture containing an excess amount of a templating agent,
subjecting the mixture to crystallization under hydrothermal conditions,
establishing an equilibrium between molecular sieve formation and
dissolution, and then, removing some of the excess templating agent
and!or organic base to inhibit dissolution of the molecular sieve.
See for example U.S. Pat. No. 5296208 which is herein fully incorporated
by reference.
[0059] Other methods for synthesizing molecular sieves or modifying
molecular sieves are described in U.S. Pat. No. 5879655 (controlling
the ratio of the templating agent to phosphorus), U.S. Pat. No.
6005155 (use of a modifier without a salt), U.S. Pat. No. 5475182
(acid extraction), U.S. Pat. No. 5962762 (treatment with transition
metal), U.S. Pat. Nos. 5925586 and 6153552 (phosphorus modified),
U.S. Pat. No. 5925800 (monolith supported), U.S. Pat. No. 5932512
(fluorine treated), U.S. Pat. No. 6046373 (electromagnetic wave
treated or modified), U.S. Pat. No. 6051746 (polynuclear aromatic
modifier), U.S. Pat. No. 6225254 (heating template), PCT WO 01/36329
published May 25 2001 (surfactant synthesis), PCT WO 01/25151 published
Apr. 12 2001 (staged acid addition), PCT WO 01/60746 published
Aug. 23 2001 (silicon oil), U.S. patent application Ser. No. 09/929949
filed Aug. 15 2001 (cooling molecular sieve), U.S. patent application
Ser. No. 09/615526 filed Jul. 13 2000 (metal impregnation including
copper), U.S. patent application Ser. No. 09/672469 filed Sep.
28 2000 (conductive microfilter), and U.S. patent application Ser.
No. 09/754812 filed Jan. 4 2001(freeze drying the molecular sieve),
which are all herein fully incorporated by reference.
[0060] Where a templating agent is used in the synthesis of the
molecular sieve, any templating agent retained in the product may
be removed after crystallization by numerous well known techniques,
for example, by calcination. Calcination involves contacting the
molecular sieve containing the templating agent with a gas, preferably
containing oxygen, at any desired concentration at an elevated temperature
sufficient to either partially or completely remove the templating
agent.
[0061] Aluminosilicate and silicoaluminophosphate 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 such as less than 0.40 for example
less than 0.32 and particularly 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 such as from about 0.40 to about 0.10 for example
from about 0.32 to about 0.10 and particularly from about 0.32
to about 0.15.
Active Metal Oxides
[0062] Active metal oxides useful herein are those metal oxides,
different from typical binders and/or matrix materials, that, when
used in combination with a molecular sieve, provide benefits in
catalytic conversion processes. Preferred active metal oxides are
those metal oxides having a Group 4 metal, such as zirconium and/or
hafnium, either alone or in combination with a Group 2 (for example
magnesium, calcium, strontium and barium) and/or a Group 3 metal
(including the Lanthanides and Actinides) oxide (for example yttrium,
scandium and lanthanum). The most preferred active Group 4 metal
oxide is an active zirconium metal oxide, either alone or in combination
with calcium oxide, barium oxide, lanthanum oxide and/or yttrium
oxide. In general, oxides of silicon, aluminum, and combinations
thereof are not preferred.
[0063] In one embodiment, active metal oxides are those metal oxides,
different from typical binders and/or matrix materials that, when
used in combination with a molecular sieve in a catalyst composition,
are effective in extending of the useful life of the catalyst composition.
Quantification of the extension in catalyst life is determined by
the Lifetime Enhancement Index (LEI) as defined by the following
equation: 1 LEI = Lifetime of Catalyst in Combination with Active
Metal Oxide Lifetime of Catalyst
[0064] where the lifetime of the catalyst or catalyst composition,
in the same process under the same conditions, is the cumulative
amount of feedstock processed per gram of catalyst composition until
the conversion of feedstock by the catalyst composition falls below
some defined level, for example 10%. An inactive metal oxide will
have little to no effect on the lifetime of the catalyst composition,
or will shorten the lifetime of the catalyst composition, and will
therefore have a LEI less than or equal to 1. Thus active metal
oxides of the invention are those metal oxides, different from typical
binders and/or matrix materials, that, when used in combination
with a molecular sieve, provide a molecular sieve catalyst composition
that has a LEI greater than 1. By definition, a molecular sieve
catalyst composition that has not been combined with an active metal
oxide will have a LEI equal to 1.0.
[0065] It is found that, by including an active metal oxide in
combination with a molecular sieve, a catalyst composition can be
produced having an LEI in the range of from greater than 1 to 20
such as from about 1.5 to about 10. Typically catalyst compositions
according to the invention exhibit LEI values greater than 1.1
for example in the range of from about 1.2 to 15 and more particularly
greater than 1.3 such as greater than 1.5 such as greater than
1.7 such as greater than 2.
[0066] In one embodiment, the active metal oxide when combined
with a molecular sieve in a catalyst composition enhances the lifetime
of the catalyst composition in the conversion of a feedstock comprising
methanol, preferably into one or more olefin(s).
[0067] In particular, the metal oxides useful herein have an uptake
of carbon dioxide at 100.degree. C. of at least 0.03 mg/m.sup.2
of the metal oxide, such as at least 0.035 mg/m.sup.2 of the metal
oxide. Although the upper limit on the carbon dioxide uptake of
the metal oxide is not critical, in general the metal oxides useful
herein will have a carbon dioxide at 100.degree. C. of less than
10 mg/m.sup.2 of the metal oxide, such as less than 5 mg/m.sup.2
of the metal oxide. Typically, the metal oxides useful herein have
a carbon dioxide uptake of 0.04 to 0.2 mg/m.sup.2 of the metal oxide.
[0068] In order to determine the carbon dioxide uptake of a metal
oxide, the following procedure is adopted. A sample of the metal
oxide is dehydrated by heating the sample to about 200.degree. C.
to 500.degree. C. in flowing air until a constant weight, the "dry
weight", is obtained. The temperature of the sample is then
reduced to 100.degree. C. and carbon dioxide is passed over the
sample, either continuously or in pulses, again until constant weight
is obtained. The increase in weight of the sample in terms of mg/mg
of the sample based on the dry weight of the sample is the amount
of adsorbed carbon dioxide.
[0069] In the Examples reported below, the carbon dioxide adsorption
is measured using a Mettler TGA/SDTA 851 thermogravimetric analysis
system under ambient pressure. The metal oxide sample is dehydrated
in flowing air to about 500.degree. C. for one hour. The temperature
of the sample is then reduced in flowing helium to 100.degree. C.
After the sample has equilibrated at the desired adsorption temperature
in flowing helium, the sample is subjected to 20 separate pulses
(about 12 seconds/pulse) of a gaseous mixture comprising 10-weight
% carbon dioxide with the remainder being helium. After each pulse
of the adsorbing gas the metal oxide sample is flushed with flowing
helium for 3 minutes. The increase in weight of the sample in terms
of mg/mg adsorbent based on the adsorbent weight after treatment
at 500.degree. C. is the amount of adsorbed carbon dioxide. The
surface area of the sample is measured in accordance with the method
of Brunauer, Emmett, and Teller (BET) published as ASTM D 3663 to
provide the carbon dioxide uptake in terms of mg carbon dioxide/m.sup.2
of the metal oxide.
[0070] In one embodiment, the active metal oxide(s) has a BET surface
area of greater than 10 m.sup.2/g, such as greater than 10 m.sup.2/g
to about 300 m.sup.2/g. In another embodiment, the active metal
oxide(s) has a BET surface area greater than 20 m.sup.2/g, such
as from 20 m.sup.2/g to 250 m.sup.2/g. In yet another embodiment,
the active metal oxide(s) has a BET surface area greater than 25
m.sup.2/g, such as from 25 m.sup.2/g to about 200 m.sup.2/g. In
a preferred embodiment, the active metal oxide(s) includes a zirconium
oxide having a BET surface area greater than 20 m.sup.2/g, such
as greater than 25 m.sup.2/g and particularly greater than 30 m.sup.2/g
[0071] The active metal oxide(s) used herein can be prepared using
a variety of methods. It is preferable that the active metal oxide
is made from an active metal oxide precursor, such as a metal salt,
such as a halide, nitrate sulfate or acetate. Other suitable sources
of the metal oxide include compounds that form the metal oxide during
calcination, sucn as oxychlorides and nitrates. Aikoxides are also
suitable sources of the Group 4 metal oxide, for example zirconium
n-propoxide. A preferred source of the Group 4 metal oxide is hydrated
zirconia. The expression, hydrated zirconia, is intended to connote
a material comprising zirconium atoms covalently linked to other
zirconium atoms via bridging oxygen atoms, and further comprising
available hydroxyl groups.
[0072] In one embodiment, the hydrated zirconia is hydrothermally
treated under conditions that include a temperature of at least
80.degree. C., preferably at least 100.degree. C. The hydrothermal
treatment typically takes place in a sealed vessel at greater than
atmospheric pressure. However, a preferred mode of treatment involves
the use of an open vessel under reflux conditions. Agitation of
hydrated Group 4 metal oxide in a liquid medium, for example, by
the action of refluxing liquid and/or stirring, promotes the effective
interaction of the hydrated oxide with the liquid medium. The duration
of the contact of the hydrated oxide with the liquid medium is conveniently
at least 1 hour, such as at least 8 hours. The liquid medium for
this treatment typically has a pH of about 6 or greater, such as
8 or greater. Non-limiting examples of suitable liquid media include
water, hydroxide solutions (including hydroxides of NH.sub.4.sup.+,
Na.sup.+, K.sup.+, Mg.sup.2+, and Ca.sup.2+), carbonate and bicarbonate
solutions (including carbonates and bicarbonates of NH.sub.4.sup.+,
Na.sup.+, K.sup.+, Mg.sup.2+, and Ca.sup.2+), pyridine and its derivatives,
and alkyl/hydroxyl amines.
[0073] In another embodiment, the active metal oxide is prepared,
for example, by subjecting a liquid solution, such as an aqueous
solution, comprising a source of ions of a Group 4 metal to conditions
sufficient to cause precipitation of a hydrated precursor of the
solid oxide material, such as by the addition of a precipitating
reagent to the solution. Conveniently, the precipitation is conducted
at a pH above 7. For example, the precipitating agent may be a base
such as sodium hydroxide or ammonium hydroxide.
[0074] When a mixture of a Group 4 metal oxide with a Group 2 and/or
3 metal oxide is to be prepared, a first liquid solution comprising
a source of ions of a Group 4 metal can be combined with a second
liquid solution comprising a source of ions of a Group 2 and/or
Group 3 metal. This combination of two solutions can take place
under conditions sufficient to cause co-precipitation of the mixed
oxide material as a solid from the liquid medium. Alternatively,
the source of ions of the Group 4 metal and the source of ions of
the Group 2 and/or Group 3 metal may be combined into a single solution.
This solution may then be subjected to conditions sufficient to
cause co-precipitation of a hydrated precursor of the solid mixed
oxide material, such as by the addition of a precipitating reagent
to the solution.
[0075] The temperature at which the liquid medium is maintained
during the precipitation is generally less than about 200.degree.
C., such as in the range of from about 0.degree. C. to about 200.degree.
C. A particular range of temperatures for precipitation is from
about 20.degree. C. to about 100.degree. C. The resulting gel is
preferably then hydrothermally treated at temperatures of at least
80.degree. C., preferably at least 100.degree. C. The hydrothermal
treatment typically takes place in a vessel at atmospheric pressure.
The gel, in one embodiment, is hydrothermally treated for up to
10 days, such as up to 5 days, for example up to 3 days.
[0076] The hydrated precursor to the metal oxide(s) is then recovered,
for example by filtration or centrifugation, and washed and dried.
The resulting material can then be calcined, such as in an oxidizing
atmosphere, at a temperature of at least 400.degree. C., such as
at least 500.degree. C., for example from about 600.degree. C. to
about 900.degree. C., and particularly from about 650.degree. C.
to about 800.degree. C., to form the active metal oxide or active
mixed metal oxide. The calcination time is typically up to 48 hours,
such as for about 0.5 to 24 hours, for example for about 1.0 to
10 hours. In one embodiment, calcination is carried out at about
700.degree. C. for about 1 to about 3 hours.
[0077] In another embodiment, the Group 4 metal oxide and the Group
2 and/or Group 3 metal oxide are made separately and then contacted
together to form the mixed metal oxide that is then contacted with
the molecular sieve. For example, the Group 4 metal oxide can be
contacted with the molecular sieve prior to introducing the Group
2 and/or Group 3 metal oxide or alternatively, the Group 2 and/or
Group-3 metal oxide can be contacted with the molecular sieve prior
to introducing the Group 4 metal oxide.
[0078] Where the catalyst composition comprises a Group 4 metal
oxide and a Group 3 metal oxide, the mole ratio of the Group 4 metal
oxide to the Group 3 metal oxide may be in the range of from 1000:1
to 1:1 such as from about 500:1 to 2:1 such as from about 100:1
to about 3:1 such as from about 75:1 to about 5:1 based on the
total moles of the Group 4 and Group 3 metal oxides. In addition,
the catalyst composition can contain from 1 to 25%, such as from
1 to 20%, such as from 1 to 15%, by weight of Group 3 metal based
on the total weight of the mixed metal oxide, particularly where
the Group 3 metal oxide is a lanthanum or yttrium metal oxide and
the Group 4 metal oxide is a zirconium metal oxide.
[0079] Where the catalyst composition comprises a Group 4 metal
oxide and a Group 2 metal oxide, the mole ratio of the Group 4 metal
oxide to the Group 2 metal oxide may be in the range of from 1000:1
to 1:2 such as from about 500:1 to 2:3 such as from about 100:1
to about 1:1 such as from about 50:1 to about 2:1 based on the
total moles of the Group 4 and Group 2 metal oxides. In addition,
the catalyst composition can contain from 1 to 25%, such as from
1 to 20%, such as from 1 to 15%, by weight of Group 2 metal based
on the total weight of the mixed metal oxide, particularly where
the Group 2 metal oxide is calcium oxide and the Group 4 metal oxide
is a zirconium metal oxide.
Catalyst Composition
[0080] The catalyst composition of the invention includes any one
of the molecular sieves previously described and one or more of
the active metal oxides described above, optionally with a binder
and/or matrix material different from the active metal oxide(s).
Typically, the weight ratio of the molecular sieve to the active
metal oxide(s) in the catalyst composition is in the range of from
5 weight percent to 800 weight percent, such as from 10 weight percent
to 600 weight percent, particularly from 20 weight percent to 500
weight percent, and more particularly from 30 weight percent to
400 weight percent.
[0081] There are many different binders that are useful in forming
catalyst compositions. Non-limiting examples of binders that are
useful alone or in combination include various types of hydrated
alumina, silicas, and/or other inorganic oxide sols. One preferred
alumina containing sol is aluminum chlorhydrol. The inorganic oxide
sol acts like glue binding the synthesized molecular sieves and
other materials such as the matrix together, particularly after
thermal treatment. Upon heating, the inorganic oxide sol, preferably
having a low viscosity, is converted into an inorganic oxide binder
component. For example, an alumina sol will convert to an aluminum
oxide binder following heat treatment.
[0082] Aluminum chlorhydrol, a hydroxylated aluminum based sol
containing a chloride counter ion, has the general formula of Al.sub.mO.sub.n(OH).sub.oCl.sub.p.x(H.sub.2O)
wherein m is 1 to 20 n is 1 to 8 o is 5 to 40 p is 2 to 15 and
x is 0 to 30. In one embodiment, the binder is Al.sub.13O.sub.4(OH).sub.24Cl.sub.7.12(H.sub.2O)
as is described in G. M. Wolterman, et al., Stud. Surf. Sci. and
Catal., 76 pages 105-144 (1993), which is herein incorporated by
reference. In another embodiment, one or more binders are combined
with one or more other non-limiting examples of alumina materials
such as aluminum oxyhydroxide, .gamma.-alumina, boehmite, diaspore,
and transitional aluminas such as .alpha.-alumina, .beta.-alumina,
.gamma.-alumina, .delta.-alumina, .epsilon.-alumina, .kappa.-alumina,
and .rho.-alumina, aluminum trihydroxide, such as gibbsite, bayerite,
nordstrandite, doyelite, and mixtures thereof.
[0083] In another embodiment, the binder is an alumina sol, predominantly
comprising aluminum oxide, optionally including some silicon. In
yet another embodiment, the binder is peptized alumina made by treating
an alumina hydrate, such as pseudobohemite, with an acid, preferably
an acid that does not contain a halogen, to prepare a sol or aluminum
ion solution. Non-limiting examples of commercially available colloidal
alumina sols include Nalco 8676 available from Nalco Chemical Co.,
Naperville, Ill., and Nyacol AL20DW available from Nyacol Nano Technologies,
Inc., Ashland, Mass.
[0084] Where the catalyst composition contains a matrix material,
this is preferably different from the active metal oxide and any
binder. Matrix materials are typically effective in reducing overall
catalyst cost, acting as thermal sinks to assist in shielding heat
from the catalyst composition for example during regeneration, densifying
the catalyst composition, and increasing catalyst strength such
as crush strength and attrition resistance.
[0085] Non-limiting examples of matrix materials include one or
more non-active metal oxides including beryllia, quartz, silica
or sols, and mixtures thereof, for example silica-magnesia, silica-zirconia,
silica-titania, silica-alumina and silica-alumina-thoria. In an
embodiment, matrix materials are natural clays such as those from
the families of montmorillonite and kaolin. These natural clays
include subbentonites and those kaolins known as, for example, Dixie,
McNamee, Georgia and Florida clays. Non-limiting examples of other
matrix materials include haloysite, kaolinite, dickite, nacrite,
or anauxite. The matrix material, such as a clay, may be subjected
to well known modification processes such as calcination and/or
acid treatment and/or chemical treatment.
[0086] In a preferred embodiment, the matrix material is a clay
or a clay-type composition, particularly a clay or clay-type composition
having a low iron or titania content, and most preferably the matrix
material is kaolin. Kaolin has been found to form a pumpable, high
solids content slurry, to have a low fresh surface area, and to
pack together easily due to its platelet structure. A preferred
average particle size of the matrix material, most preferably kaolin,
is from about 0.1 .mu.m to about 0.6 .mu.m with a D.sub.90 particle
size distribution of less than about 1 .mu.m.
[0087] Where the catalyst composition contains a binder or matrix
material, the catalyst composition typically contains from about
1% to about 80%, such as from about 5% to about 60%, and particularly
from about 5% to about 50%, by weight of the molecular sieve based
on the total weight of the catalyst composition.
[0088] Where the catalyst composition contains a binder and a matrix
material, the weight ratio of the binder to the matrix material
is typically from 1:15 to 1:5 such as from 1:10 to 1:4 and particularly
from 1:6 to 1:5. The amount of binder is typically from about 2%
by weight to about 30% by weight, such as from about 5% by weight
to about 20% by weight, and particularly from about 7% by weight
to about 15% by weight, based on the total weight of the binder,
the molecular sieve and matrix material. It has been found that
a higher sieve content and lower matrix content increases the molecular
sieve catalyst composition performance, whereas a lower sieve content
and higher matrix content improves the attrition resistance of the
composition.
[0089] The catalyst composition typically has a density in the
range of from 0.5 g/cc to 5 g/cc, such as from from 0.6 g/cc to
5 g/cc, for example from 0.7 g/cc to 4 g/cc, particularly in the
range of from 0.8 g/cc to 3 g/cc.
Method of Making the Catalyst Composition
[0090] In making the catalyst composition, the molecular sieve
is first formed and is then physically mixed with the active metal
oxide, preferably in a substantially dry, dried, or calcined state.
Most preferably the molecular sieve and active metal oxides are
physically mixed in their calcined state. Without being bound by
any particular theory, it is believed that intimate mixing of the
molecular sieve and one or more active metal oxides improves conversion
processes using the molecular sieve composition and catalyst composition
of the invention. Intimate mixing can be achieved by any method
known in the art, such as mixing with a mixer muller, drum mixer,
ribbon/paddle blender, kneader, or the like. Chemical reaction between
the molecular sieve and the metal oxide(s) is unnecessary and, in
general, is not preferred.
[0091] Where the catalyst composition contains a matrix and/or
binder, the molecular sieve is conveniently initially formulated
into a catalyst precursor with the matrix and/or binder and the
active metal oxide is then combined with the formulated precursor.
The active metal oxide can be added as unsupported particles or
can be added in combination with a support, such as a binder or
matrix material. The resultant catalyst composition can then be
formed into useful shaped and sized particles by well-known techniques
such as spray drying, pelletizing, extrusion, and the like.
[0092] In one embodiment, the molecular sieve composition and the
matrix material, optionally with a binder, are combined with a liquid
to form a slurry and then mixed, preferably rigorously mixed, to
produce a substantially homogeneous mixture containing the molecular
sieve composition. Non-limiting examples of suitable liquids include
one or a combination of water, alcohol, ketones, aldehydes, and/or
esters. The most preferred liquid is water. In one embodiment, the
slurry is colloid-milled for a period of time sufficient to produce
the desired slurry texture, sub-particle size, and/or sub-particle
size distribution.
[0093] The molecular sieve composition and matrix material, and
the optional binder, can be combined in the same or different liquids,
and can be combined in any order, together, simultaneously, sequentially,
or a combination thereof. In the preferred embodiment, the same
liquid, preferably water is used. The molecular sieve composition,
matrix material, and optional binder, are combined in a liquid as
solids, substantially dry or in a dried form, or as slurries, together
or separately. If solids are added together as dry or substantially
dried solids, it is preferable to add a limited and/or controlled
amount of liquid.
[0094] In one embodiment, the slurry of the molecular sieve composition,
binder and matrix materials is mixed or milled to achieve a sufficiently
uniform slurry of sub-particles of the molecular sieve catalyst
composition that is then fed to a forming unit that produces the
molecular sieve catalyst composition. In a preferred embodiment,
the forming unit is spray dryer. Typically, the forming unit is
maintained at a temperature sufficient to remove most of the liquid
from the slurry, and from the resulting molecular sieve catalyst
composition. The resulting catalyst composition when formed in this
way takes the form of microspheres.
[0095] When a spray drier is used as the forming unit, typically,
the slurry of the molecular sieve composition ard matrix material,
and optionally a binder, is co-fed to the spray drying volume with
a drying gas with an average inlet temperature ranging from 200.degree.
C. to 550.degree. C., and a combined outlet temperature ranging
from 100.degree. C. to about 225.degree. C. In an embodiment, the
average diameter of the spray dried formed catalyst composition
is from about 40 .mu.m to about 300 .mu.m, such as from about 50
.mu.m to about 250 .mu.m, for example from about 50 .mu.m to about
200 .mu.m, and conveniently from about 65 .mu.m to about 90 .mu.m.
[0096] Other methods for forming a molecular sieve catalyst composition
are 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.
[0097] Once the molecular sieve catalyst composition is formed
in a substantially dry or dried state, to further harden and/or
activate the formed catalyst composition, a heat treatment such
as calcination, at an elevated temperature is usually performed.
Typical calcination temperatures are in the range from about 400.degree.
C. to about 1.000.degree. C., such as from about 500.degree. C.
to about 800.degree. C., such as from about 550.degree. C. to about
700.degree. C. Typical calcination environments are air (which may
include a small amount of water vapor), nitrogen, helium, flue gas
(combustion product lean in oxygen), or any combination thereof.
[0098] In a preferred embodiment, the catalyst composition is heated
in nitrogen at a temperature of from about 600.degree. C. to about
700.degree. C. Heating is carried out for a period of time typically
from 30 minutes to 15 hours, such as from 1 hour to about 10 hours,
for example from about 1 hour to about 5 hours, and particularly
from about 2 hours to about 4 hours.
Process for Using the Molecular Sieve Catalyst Compositions
[0099] The catalyst compositions described above are useful in
a variety of processes including cracking, of for example a naphtha
feed to light olefin(s) (U.S. Pat. No. 6300537) or higher molecular
weight (MW) hydrocarbons to lower MW hydrocarbons; hydrocracking,
of for example heavy petroleum and/or cyclic feedstock; isomerization,
of for example aromatics such as xylene; polymerization, of for
example one or more olefin(s) to produce a polymer product; reforming;
hydrogenation; dehydrogenation; dewaxing, of for example hydrocarbons
to remove straight chain paraffins; absorption, of for example alkyl
aromatic compounds for separating out isomers thereof; alkylation,
of for example aromatic hydrocarbons such as benzene and alkyl benzene,
optionally with propylene to produce cumene or with long chain olefins;
transalkylation, of for example a combination of aromatic and polyalkylaromatic
hydrocarbons; dealkylation; hydrodecylization; disproportionation,
of for example toluene to make benzene and paraxylene; oligomerization,
of for example straight and branched chain olefin(s); and dehydrocyclization.
[0100] Preferred processes include processes for converting naphtha
to highly aromatic mixtures; converting light olefin(s) to gasoline,
distillates and lubricants; converting oxygenates to olefin(s);
converting light paraffins to olefins and/or aromatics; and converting
unsaturated hydrocarbons (ethylene and/or acetylene) to aldehydes
for conversion into alcohols, acids and esters.
[0101] The most preferred process of the invention is a process
directed to the conversion of a feedstock to one or more olefin(s).
Typically, the feedstock contains one or more aliphatic-containing
compounds such that the aliphatic moiety contains from 1 to about
50 carbon atoms, such as from 1 to 20 carbon atoms, for example
from 1 to 10 carbon atoms, and particularly from 1 to 4 carbon atoms.
[0102] Non-limiting examples of aliphatic-containing compounds
include alcohols such as methanol and ethanol, alkyl mercaptans
such as methyl mercaptan and ethyl mercaptan, alkyl sulfides such
as methyl sulfide, alkylamines such as methylamine, alkyl ethers
such as dimethyl ether, diethyl ether and methylethyl ether, alkyl
halides such as methyl chloride and ethyl chloride, alkyl ketones
such as dimethyl ketone, formaldehydes, and various acids such as
acetic acid.
[0103] 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.
[0104] 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.
[0105] 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.
[0106] The various feedstocks discussed above, particularly a feedstock
containing an oxygenate, more particularly a feedstock containing
an alcohol, is converted primarily into one or more olefin(s). The
olefin(s) produced from the feedstock typically have from 2 to 30
carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2
to 6 carbon atoms, still more preferably 2 to 4 carbons atoms, and
most preferably are ethylene and/or propylene.
[0107] The catalyst composition of the invention is particularly
useful in the process that is generally referred to as the gas-to-olefins
(GTO) process or alternatively, the methanol-to-olefins (MTO) process.
In this process, an oxygenated feedstock, most preferably a methanol-containing
feedstock, is converted in the presence of a molecular sieve catalyst
composition into one or more olefin(s), preferably and predominantly,
ethylene and/or propylene.
[0108] Using the catalyst composition of the invention for the
conversion of a feedstock, preferably a feedstock containing one
or more oxygenates, the amount of olefin(s) produced based on the
total weight of hydrocarbon produced is greater than 50 weight percent,
typically greater than 60 weight percent, such as greater than 70
weight percent, and preferably greater than 80 weight percent. Moreover,
the amount of ethylene and/or propylene produced based on the total
weight of hydrocarbon product produced is greater than 40 weight
percent, typically greater than 50 weight percent, for example greater
than 65 weight percent, and preferably greater than 78 weight percent.
Typically, the amount ethylene produced in weight percent based
on the total weight of hydrocarbon product produced, is greater
than 20 weight percent, such as greater than 30 weight percent,
for example greater than 40 weight percent. In addition, the amount
of propylene produced in weight percent based on the total weight
of hydrocarbon product produced is typically greater than 20 weight
percent, such as greater than 25 weight percent, for example greater
than 30 weight percent, and preferably greater than 35 weight percent.
[0109] Using the catalyst composition of the invention for the
conversion of a feedstock comprising methanol and dimethylether
to ethylene and propylene, it is found that the production of ethane
and propane is reduced by greater than 10%, such as greater than
20%, for example greater than 30%, and particularly in the range
of from about 30% to 40% compared to a similar catalyst composition
at the same conversion conditions but without the active metal oxide
component(s).
[0110] In addition to the oxygenate component, such as methanol,
the feedstock may contains one or more diluent(s), which are generally
non-reactive to the feedstock or molecular sieve catalyst composition
and are typically used to reduce the concentration of the feedstock.
Non-limiting examples of diluents include helium, argon, nitrogen,
carbon monoxide, carbon dioxide, water, essentially non-reactive
paraffins (especially alkanes such as methane, ethane, and propane),
essentially non-reactive aromatic compounds, and mixtures thereof.
The most preferred diluents are water and nitrogen, with water being
particularly preferred.
[0111] The diluent, for example water, may be used either in a
liquid or a vapor form, or a combination thereof. The diluent may
be either added directly to the feedstock entering a reactor or
added directly to the reactor, or added with the molecular sieve
catalyst composition.
[0112] The present process can be conducted over a wide range of
temperatures, such as in the range of from about 200.degree. C.
to about 1000.degree. C., for example from about 250.degree. C.
to about 800.degree. C., including from about 250.degree. C. to
about 750.degree. C., conveniently from about 300.degree. C. to
about 650.degree. C., typically from about 350.degree. C. to about
600.degree. C. and particularly from about 350.degree. C. to about
550.degree. C.
[0113] Similarly, the present process can be conducted over a wide
range of pressures including autogenous pressure. Typically the
partial pressure of the feedstock exclusive of any diluent therein
employed in the process is in the range of from about 0.1 kPaa to
about 5 MPaa, such as from about 5 kPaa to about 1 MPaa, and conveniently
from about 20 kPaa to about 500 kPaa.
[0114] The weight hourly space velocity (WHSV), defined as the
total weight of feedstock excluding any diluents per hour per weight
of molecular sieve in the catalyst composition, typically ranges
from about 1 hr-1 to about 5000 hr-1 such as from about 2 hr-1
to about 3000 hr-1 for example from about 5 hr-1 to about 1500
hr-1 and conveniently from about 10 hr-1 to about 1000 hr-1. In
one embodiment, the WHSV is greater than 20 hr-1 and, where feedstock
contains methanol and/or dimethyl ether, is in the range of from
about 20 hr-1 to about 300 hr-1.
[0115] Where the process is conducted in a fluidized bed, the superficial
gas velocity (SGV) of the feedstock including diluent and reaction
products within the reactor system, and particularly within a riser
reactor(s), is at least 0.1 meter per second (m/sec), such as greater
than 0.5 m/sec, such as greater than 1 m/sec, for example greater
than 2 m/sec, conveniently greater than 3 m/sec, and typically greater
than 4 m/sec. See for example U.S. patent application Ser. No. 09/708753
filed Nov. 8 2000 which is herein incorporated by reference.
[0116] The process of the invention is conveniently conducted as
a fixed bed process, or more typically as a fluidized bed process
(including a turbulent bed process), such as a continuous fluidized
bed process, and particularly a continuous high velocity fluidized
bed process.
[0117] The process can take place in a variety of catalytic reactors
such as hybrid reactors that have a dense bed or fixed bed reaction
zones and/or fast fluidized bed reaction zones coupled together,
circulating fluidized bed reactors, riser reactors, and the like.
Suitable conventional reactor types are described in for example
U.S. Pat. No. 4076796 U.S. Pat. No. 6287522 (dual riser), and
Fluidization Engineering, D. Kunii and O. Levenspiel, Robert E.
Krieger Publishing Company, New York, N.Y. 1977 which are all herein
fully incorporated by reference.
[0118] The preferred reactor types are riser reactors generally
described in Riser Reactor, Fluidization and Fluid-Particle Systems,
pages 48 to 59 F. A. Zenz and D. F. Othmo, Reinhold Publishing
Corporation, New York, 1960 and U.S. Pat. No. 6166282 (fast-fluidized
bed reactor), and U.S. patent application Ser. No. 09/564613 filed
May 4 2000 (multiple riser reactor), which are all herein fully
incorporated by reference.
[0119] In one practical embodiment, the process is conducted as
a fluidized bed process or high velocity fluidized bed process utilizing
a reactor system, a regeneration system and a recovery system.
[0120] In such a process the reactor system would conveniently
include a fluid bed reactor system having a first reaction zone
within one or more riser reactor(s) and a second reaction zone within
at least one disengaging vessel, typically comprising one or more
cyclones. In one embodiment, the one or more riser reactor(s) and
disengaging vessel are contained within a single reactor vessel.
Fresh feedstock, preferably containing one or more oxygenates, optionally
with one or more diluent(s), is fed to the one or more riser reactor(s)
into which a molecular sieve catalyst composition or coked version
thereof is introduced. In one embodiment, prior to being introduced
to the riser reactor(s), the molecular sieve catalyst composition
or coked version thereof is contacted with a liquid, preferably
water or methanol, and/or a gas, for example, an inert gas such
as nitrogen.
[0121] In an embodiment, the amount of fresh feedstock fed as a
liquid and/or a vapor to the reactor system is in the range of from
0.1 weight percent to about 85 weight percent, such as from about
1 weight percent to about 75 weight percent, more typically from
about 5 weight percent to about 65 weight percent based on the total
weight of the feedstock including any diluent contained therein.
The liquid and vapor feedstocks may be the same composition, or
may contain varying proportions of the same or different feedstocks
with the same or different diluents.
[0122] The feedstock entering the reactor system is preferably
converted, partially or fully, in the first reactor zone into a
gaseous effluent that enters the disengaging vessel along with the
coked catalyst composition. In the preferred embodiment, cyclone(s)
are provided within the disengaging vessel to separate the - coked
catalyst composition from the gaseous effluent containing one or
more olefin(s) within the disengaging vessel. Although cyclones
are preferred, gravity effects within the disengaging vessel can
also be used to separate the catalyst composition from the gaseous
effluent. Other methods for separating the catalyst composition
from the gaseous effluent include the use of plates, caps, elbows,
and the like.
[0123] In one embodiment, the disengaging vessel includes a stripping
zone, typically in a lower portion of the disengaging vessel. In
the stripping zone the coked catalyst composition is contacted with
a gas, preferably one or a combination of steam, methane, carbon
dioxide, carbon monoxide, hydrogen, or an inert gas such as argon,
preferably steam, to recover adsorbed hydrocarbons from the coked
catalyst composition that is then introduced to the regeneration
system.
[0124] The coked catalyst composition is withdrawn from the disengaging
vessel and introduced to the regeneration system. The regeneration
system comprises a regenerator where the coked catalyst composition
is contacted with a regeneration medium, preferably a gas containing
oxygen, under conventional regeneration conditions of temperature,
pressure and residence time.
[0125] Non-limiting examples of suitable regeneration media include
one or more of oxygen, O3 SO3 N2O, NO, NO2 N2O5 air, air diluted
with nitrogen or carbon dioxide, oxygen and water (U.S. Pat. No.
6245703), carbon monoxide and/or hydrogen. Suitable regeneration
conditions are those capable of burning coke from the coked catalyst
composition, preferably to a level less than 0.5 weight percent
based on the total weight of the coked molecular sieve catalyst
composition entering the regeneration system. For example, the regeneration
temperature may be in the range of from about 200.degree. C. to
about 1500.degree. C., such as from about 300.degree. C. to about
1000.degree. C., for example from about 450.degree. C. to about
750.degree. C., and conveniently from about 550.degree. C. to 700.degree.
C. The regeneration pressure may be in the range of from about 15
psia (103 kPaa) to about 500 psia (3448 kPaa), such as from about
20 psia (138 kPaa) to about 250 psia (1724 kPaa), including from
about 25 psia (172 kPaa) to about 150 psia (1034 kPaa), and conveniently
from about 30 psia (207 kPaa) to about 60 psia (414 kPaa).
[0126] The residence time of the catalyst composition in the regenerator
may be in the range of from about one minute to several hours, such
as from about one minute to 100 minutes, and the volume of oxygen
in the regeneration gas may be in the range of from about 0.01 mole
percent to about 5 mole percent based on the total volume of the
gas.
[0127] The burning.of coke in the regeneration step is an exothermic
reaction, and in an embodiment, the temperature within the regeneration
system is controlled by various techniques in the art including
feeding a cooled gas to the regenerator vessel, operated either
in a batch, continuous, or semi-continuous mode, or a combination
thereof. A preferred technique involves withdrawing the regenerated
catalyst composition from the regeneration system and passing it
through a catalyst cooler to form a cooled regenerated catalyst
composition. The catalyst cooler, in an embodiment, is a heat exchanger
that is located either internal or external to the regeneration
system,. Other methods for operating a regeneration system are disclosed
in U.S. Pat. No. 6290916 (controlling moisture), which is herein
fully incorporated by reference.
[0128] The regenerated catalyst composition withdrawn from the
regeneration system, preferably from a catalyst cooler, is combined
with a fresh molecular sieve catalyst composition and/or re-circulated
molecular sieve catalyst composition and/or feedstock and/or fresh
gas or liquids, and returned to the riser reactor(s). In one embodiment,
the regenerated catalyst composition withdrawn from the regeneration
system is returned to the riser reactor(s) directly, preferably
after passing through a catalyst cooler. A carrier, such as an inert
gas, feedstock vapor, steam or the like, may be used, semi-continuously
or continuously, to facilitate the introduction of the regenerated
catalyst composition to the reactor system, preferably to the one
or more riser reactor(s).
[0129] By controlling the flow of the regenerated catalyst composition
or cooled regenerated catalyst composition from the regeneration
system to the reactor system, the optimum level of coke on the molecular
sieve catalyst composition entering the reactor is maintained. There
are many techniques for controlling the flow of a catalyst composition
described in Michael Louge, Experimental Techniques, Circulating
Fluidized Beds, Grace, Avidan and Knowlton, eds., Blackie, 1997
(336-337), which is herein incorporated by reference.
[0130] Coke levels on the catalyst composition are measured by
withdrawing the catalyst composition from the conversion process
and determining its carbon content. Typical levels of coke on the
molecular sieve catalyst composition, after regeneration, are in
the range of from 0.01 weight percent to about 15 weight percent,
such as from about 0.1 weight percent to about 10 weight percent,
for example from about 0.2 weight percent to about 5 weight percent,
and conveniently from about 0.3 weight percent to about 2 weight
percent based on the weight of the molecular sieve.
[0131] The gaseous effluent is withdrawn from the disengaging system
and is passed through a recovery system. There are many well known
recovery systems, techniques and sequences that are useful in separating
olefin(s) and purifying olefin(s) from the gaseous effluent. Recovery
systems generally comprise one or more or a combination of various
separation, fractionation and/or distillation towers, columns, splitters,
or trains, reaction systems such as ethylbenzene manufacture (U.S.
Pat. No. 5476978) and other derivative processes such as aldehydes,
ketones and ester manufacture (U.S. Pat. No. 5675041), and other
associated equipment, for example various condensers, heat exchangers,
refrigeration systems or chill trains, compressors, knock-out drums
or pots, pumps, and the like.
[0132] 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 de-ethanizer,
a depropanizer, a wash tower often referred to as a caustic-wash
tower and/or quench tower, absorbers, adsorbers, membranes, ethylene
(C2) splitter, propylene (C3) splitter, butene (C4) splitter, and
the like.
[0133] Various recovery systems useful for recovering predominantly
olefin(s), preferably 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.
[0134] Other recovery systems that include purification systems,
for example for the purification of olefin(s), are described in
Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, Volume
9 John Wiley & Sons, 1996 pages 249-271 and 894-899 which
is herein incorporated by reference. Purification systems are also
described in for example, U.S. Pat. No. 6271428 (purification
of a diolefin hydrocarbon stream), U.S. Pat. No. 6293999 (separating
propylene from propane), and U.S. patent application Ser. No. 09/689363
filed Oct. 20 2000 (purge stream using hydrating catalyst), which
are herein incorporated by reference.
[0135] 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.
[0136] 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.
[0137] Typically, in converting one or more oxygenates to olefin(s)
having 2 or 3 carbon atoms, a minor amount hydrocarbons, particularly
olefin(s), having 4 or more carbon atoms is also produced. The amount
of C4+ hydrocarbons is normally less than 20 weight percent, such
as less than 10 weight percent, for example less than 5 weight percent,
and particularly less than 2 weight percent, based on the total
weight of the effluent gas withdrawn from the process, excluding
water. Typically, therefore the recovery system may include one
or more reaction systems for converting the C4+ impurities to useful
products.
[0138] Non-limiting examples of such reaction systems are described
in U.S. Pat. No. 5955640 (converting a four carbon product into
butene-1), U.S. Pat. No. 4774375 (isobutane and butene-2 oligomerized
to an alkylate gasoline), U.S. Pat. No. 6049017 (dimerization
of n-butylene), U.S. Pat. Nos. 4287369 and 5763678 (carbonylation
or hydroformulation of higher olefins with carbon dioxide and hydrogen
making carbonyl compounds), U.S. Pat. No.4542252 (multistage adiabatic
process), U.S. Pat. No. 5634354 (olefin-hydrogen recovery), and
Cosyns, J. et al., Process for Upgrading C3 C4 and C5 Olefinic
Streams, Pet. & Coal, Vol. 37 No. 4 (1995) (dimerizing or oligomerizing
propylene, butylene and pentylene), which are all herein fully incorporated
by reference.
[0139] The preferred light olefin(s) produced by any one of the
processes described above are high purity prime olefin(s) products
that contain a single carbon number olefin in an amount greater
than 80 percent, such as greater than 90 weight percent, such as
greater than 95 weight percent, for example at least about 99 weight
percent, based on the total weight of the olefin.
[0140] In one practical embodiment, the process of the invention
forms part of an integrated process for producing light olefin(s)
from a hydrocarbon feedstock, preferably a gaseous hydrocarbon feedstock,
particularly methane and/or ethane. The first step in the process
is passing the gaseous feedstock, preferably in combination with
a water stream, to a syngas production zone to produce a synthesis
gas (syngas) stream, typically comprising carbon dioxide, carbon
monoxide and hydrogen. Syngas production is well known, and typical
syngas temperatures are in the range of from about 700.degree. C.
to about 1200.degree. C. and syngas pressures are in the range of
from about 2 MPa to about 100 MPa. Synthesis gas streams are produced
from natural gas, petroleum liquids, and carbonaceous materials
such as coal, recycled plastic, municipal waste or any other organic
material. Preferably synthesis gas stream is produced via steam
reforming of natural gas.
[0141] The next step in the process involves contacting the synthesis
gas stream generally with a heterogeneous catalyst, typically a
copper based catalyst, to produce an oxygenate containing stream,
often in combination with water. in one embodiment, the contacting
step is conducted at temperature in the range of from about 150.degree.
C. to about 450.degree. C. and a pressure in the range of from about
5 MPa to about 10 MPa.
[0142] This oxygenate containing stream, or crude methanol, typically
contains the alcohol product and various other components such as
ethers, particularly dimethyl ether, ketones, aldehydes, dissolved
gases such as hydrogen methane, carbon oxide and nitrogen, and fuel
oil. The oxygenate containing stream, crude methanol, in the preferred
embodiment is passed through a well known purification processes,
distillation, separation and fractionation, resulting in a purified
oxygenate containing stream, for example, commercial Grade A and
AA methanol.
[0143] The oxygenate containing stream or purified oxygenate containing
stream, optionally with one or more diluents, can then be-used as
a feedstock in a process to produce light olefin(s), such as ethylene
and/or propylene. Non-limiting examples of this integrated process
are described in EP-B-0 933 345 which is herein fully incorporated
by reference.
[0144] In another more fully integrated process, that optionally
is combined with the integrated processes described above, the 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.)
[0145] Polymerization processes include solution, gas phase, slurry
phase and a high pressure processes, or a combination 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 the Ziegler-Nana, Phillips-type, metallocene, metallocene-type
and advanced polymerization catalysts, and mixtures thereof.
[0146] In a preferred embodiment, the integrated process comprises
a process for polymerizing 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) have been made by converting an alcohol, particularly
methanol, using a molecular sieve catalyst composition as described
above. 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.
[0147] 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.
EXAMPLES
[0148] In order to provide a better understanding of the present
invention including representative advantages thereof, the following
Examples are offered.
[0149] In the Examples, LEI is defined as the ratio of the lifetime
of a molecular sieve catalyst composition containing an active metal
oxide(s) compared to that of the same molecular sieve in the absence
of a metal oxide, defined as having an LEI of 1. For the purpose
of determining LEI, lifetime is defined as the cumulative amount
of oxygenate converted, preferably into one or more olefin(s), per
gram of molecular sieve, until the conversion rate drops to about
10% of its initial value. If the conversion has not fallen to 10%
of its initial value by the end of the experiment, lifetime is estimated
by linear extrapolation based on the rate of decrease in conversion
over the last two data points in the experiment. For the purposes
of determining the LEI for the following Examples in a preferred
oxygenate conversion process, methanol is converted to one or more
olefin(s) at 475.degree. C., 25 psig (172 kPag) and a methanol weight
hourly space velocity of 100 h-1.
[0150] "Prime Olefin" is the sum of the selectivity to
ethylene and propylene. The ratio "C2=/C3=" is the ratio
of the ethylene to propylene selectivity weighted over the run.
The "C3 Purity" is calculated by dividing the propylene
selectivity by the sum of the propylene and propane selectivities.
The selectivities for methane, ethylene, ethane, propylene, propane,
C4's and C5+'s are average selectivities weighted over the run.
Note that the C5+'s consist only of C5's, C6's and C7's. The selectivity
values do not sum to 100% in the Tables because they have been corrected
for coke as is well known.
Example A
Preparation of Molecular Sieve
[0151] A silicoaluminophosphate molecular sieve, SAPO-34 designated
as MSA, was crystallized in the presence of tetraethyl ammonium
hydroxide (R1) and dipropylamine (R2) as the organic structure directing
agents or templating agents. A mixture of the following mole ratio
composition:
0.2SiO.sub.2/Al.sub.2O.sub.3/P.sub.2O.sub.5/0.9R1/1.5R2/50H.sub.2O.
[0152] was prepared by initially mixing an amount of Condea Pural
SB with deionised water, to form a slurry. To this slurry was added
an amount of phosphoric acid (85%). These additions were made with
stirring to form a homogeneous mixture. To this homogeneous mixture
Ludox AS40 (40% of SiO2) was added, followed by the addition of
R1 with mixing to form a homogeneous mixture. To this homogeneous
mixture R2 was added. This homogeneous mixture was then crystallized
with agitation in a stainless steel autoclave by heating to 170.degree.
C. for 40 hours. This provided a slurry of the crystalline molecular
sieve. The crystals were then separated from the mother liquor by
filtration. The molecular sieve crystals were then mixed with a
binder and matrix material and formed into particles by spray drying.
Example B
Conversion Process
[0153] All catalytic or conversion data presented was obtained
using a microflow reactor consisting of a stainless steel reactor
(1/4 inch (0.64 cm) outer diameter) located in a furnace to which
vaporized methanol was fed. The reactor was maintained at a temperature
of 475.degree. C. and a pressure of 25 psig (172.4 kPag) The flow
rate of the methanol was such that the flow rate of methanol on
weight basis per gram of molecular sieve, also known as the weight
hourly space velocity (WHSV) was 100 h-1. Product gases exiting
the reactor were collected and analyzed using gas chromatography.
The catalyst load in each experiment was 50 mg and the reactor bed
was diluted with quartz to minimize hot spots in the reactor. In
particular, for the catalyst composition of the invention, a physical
mixture of the MSA molecular sieve of Example A and the active metal
oxide(s) was used. The total catalyst composition load remained
50 mg, and the methanol flow rate was adjusted as the amount of
molecular sieve in the reactor bed was reduced by the addition of
the mixed metal oxide such that the methanol WHSV was 100 h-1 based
on the amount of molecular sieve in the reactor bed.
Example 1
[0154] One thousand grams of ZrOCl2.8H2O was dissolved with stirring
in 3.0 liters of distilled water. Another solution containing 400
grams of concentrated NH4OH and 3.0 liters of distilled water was
prepared. Both solutions were heated to 60.degree. C. These two
heated solutions were combined at a rate of 50ml/min using nozzle
mixing. The pH of the final composite was adjusted to approximately
9 by the addition of concentrated ammonium hydroxide. This slurry
was then put in polypropylene bottles and placed in a steambox (100.degree.
C.) for 72 hours. The product formed was recovered by filtration,
washed with excess water, and dried overnight at 85.degree. C. A
portion of this product was calcined to 700.degree. C. in flowing
air for 3 hours to produce an active zirconium oxide material.
Example 2
[0155] Five hundred grams of ZrOCl2.8H2O and 84 grams of La(NO3)3.6H2O
were dissolved with stirring in 3.0 liters of distilled water. Another
solution containing 260 grams of concentrated NH4OH and 3.0 liters
of distilled water was prepared. Both solutions were heated to 60.degree.
C. and then combined at the rate of 50 ml/min using nozzle mixing
to form the final mixture, a slurry. The pH of the final mixture
was adjusted to approximately 9 by the addition of concentrated
ammonium hydroxide. This slurry was then put in a polypropylene
bottle and placed in a steam box (100.degree. C.) for 72 hours.
The resulting product formed was recovered by filtration, washed
with excess-water, and dried overnight at 85.degree. C. A portion
of this product, was calcined to 700.degree. C. in flowing air for
3 hours to produce an active mixed metal oxide containing a nominal
10 weight percent La (lanthanum) based on the final weight of the
mixed metal oxide.
Example 3
[0156] Fifty grams of ZrOCl2.8H2O were dissolved with stirring
in 300 ml of distilled water. Another solution containing 4.2 grams
of La(NO3)3.6H2O and 300 ml of distill water was prepared. These
two solutions were combined with stirring to form a final mixture.
The pH of the final mixture, a slurry, was adjusted to approximately
9 by the addition of concentrated ammonium hydroxide (28.9 grams).
This slurry was then put in a polypropylene bottle and placed in
a steam box (100.degree. C.) for 72 hours. The resulting product
formed was recovered by filtration, washed with excess water, and
dried overnight at 85.degree. C. A portion of this resulting product
was calcined to 700.degree. C. in flowing air for 3 hours to produce
an active mixed metal oxide containing a nominal 5 weight percent
La based on the final weight of the mixed metal oxide.
Example 4
[0157] Five hundred grams of ZrOCl2.8H2O and 70 grams of Y(NO3)3.5H2O
were dissolved with stirring in 3.0 liters of distilled water. Another
solution containing 260 grams of concentrated NH4OH and 3.0 liters
of distilled water was prepared. Both solutions were heated to 60.degree.
C. and then combined at the rate of 50 ml/min using nozzle mixing
to form a final mixture. The pH of the final mixture, a slurry,
was adjusted to approximately 9 by the addition of concentrated
ammonium hydroxide. This slurry was then put in a polypropylene
bottle and placed in a steam box (100.degree. C.) for 72 hours.
The resulting product formed was recovered by filtration, washed
with excess water, and dried overnight at 85.degree. C. A portion
of the resulting product was calcined to 700.degree. C. in flowing
air for 3 hours to produce an active mixed metal oxide containing
a nominal 10 weight percent Y (yttrium) based on the final weight
of the mixed metal oxide.
Example 5
[0158] Five hundred grams of ZrOCl2.8H2O and 56 grams of Ca(NO3)2.4H2O
were dissolved with stirring in 3000 ml of distilled water. Another
solution containing 260 grams of NH40H and 3000ml of distilled water
was prepared. These two solutions were combined with stirring. The
pH of the final composite was adjusted to approximately 9 by the
addition of concentrated ammonium hydroxide (160 grams). This slurry
was then put in polypropylene bottles and placed in a steambox (100.degree.
C.) for 72 hours. The resulting product formed was recovered by
filtration, washed with excess water, and dried overnight at 85.degree.
C. A portion of this product was calcined to 700.degree. C. in flowing
air for 3 hours to produce an active mixed metal oxide containing
a nominal 5 weight percent Ca (calcium) based on the final weight
of the mixed metal oxide.
Example 6
[0159] Seventy grams of TiOSO.sub.4.xH.sub.2SO.sub.4.xH.sub.2O(x=1)
were dissolved with stirring in 400 ml of distilled water. Another
solution containing 12.8 grams of CeSO.sub.4 and 300 ml of distilled
water was prepared. These two solutions were combined with stirring.
The pH of the final composite was adjusted to approximately 8 by
the addition of concentrated ammonium hydroxide (64.3 grams). This
slurry was then put in polypropylene bottles and placed in a steambox
(100.degree. C.) for 72 hours. The product formed was recovered
by filtration, washed with excess water, and dried overnight at
85.degree. C. A portion of this product was calcined to 700.degree.
C. in flowing air for 3 hours to produce an active mixed metal oxide
containing a nominal 5 weight percent Ce based on the final weight
of the mixed metal oxide.
Example 7
[0160] Five grams of HfOCl.sub.2.xH.sub.2O was dissolved with stirring
in 100 ml of distilled water. The pH of the final composite was
adjusted to approximately 9 by the addition of concentrated ammonium
hydroxide (4.5 grams). This slurry was then put in a polypropylene
bottle and placed in a steambox (100.degree. C.) for 72 hours. The
product formed was recovered by filtration, washed with excess water,
and dried overnight at 85.degree. C. A portion of this catalyst
was calcined to 700.degree. C. in flowing air for 3 hours to produce
an active hafnium oxide.
Example 8
[0161] Five grams of HfOCl.sub.2.xH.sub.2O and 0.62 grams of La(NO.sub.3).sub.3.6H.sub.2O
were dissolved with stirring in 100 ml of distilled water. The pH
of the final composite was adjusted to approximately 9 by the addition
of concentrated ammonium hydroxide (3.5 grams). This slurry was
then put in a polypropylene bottle and placed in a steambox (100.degree.
C.) for 72 hours. The product formed was recovered by filtration,
washed with excess water, and dried overnight at 85.degree. C. A
portion of this catalyst was calcined to 700.degree. C. in flowing
air for 3 hours to produce an active mixed metal oxide containing
a nominal 5 weight % La based on the final weight of the mixed metal
oxide.
Example 9
[0162] The carbon dioxide uptake of the oxides of Examples 1 through
8 were measured using a Mettler TGA/SDTA 851 thermogravimetric analysis
system under ambient pressure. The metal oxide samples were first
dehydrated in flowing air to about 500.degree. C. for one hour after
which the uptake of carbon dioxide was measured at 100.degree. C.
The surface area of the samples were measured in accordance with
the method of Brunauer, Emmett, and Teller (BET) to provide the
carbon dioxide uptake in terms of mg carbon dioxide/m.sup.2 of the
metal oxide presented in Table 1.
1TABLE 1 Catalyst Dry Surface Area CO.sub.2 Uptake Example Weight
(mg) mg of CO.sub.2 (m.sup.2/g) (mg of CO.sub. |