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 metal oxide, such as a magnesium oxide that,
when saturated with acetone and contacted with said acetone for
1 hour at 25.degree. C., converts more than 80% of the acetone.
Molecular sieve claims
We claim:
1. A catalyst composition comprising: (a) a metal oxide which has
a surface area greater than 20 m.sup.2/g, which has been calcined
at temperature greater than 200.degree. C., and which, when saturated
with acetone and contacted with said acetone for 1 hour at 25.degree.
C., converts more than 80% of the acetone; (b) a binder; (c) a matrix
material; and (d) a molecular sieve having an average pore size
less than 5 .ANG..
2. The catalyst composition of claim 1 wherein the surface area
of said metal oxide is greater than 70 m.sup.2/g.
3. The catalyst composition of claim 1 wherein the molecular sieve
is a silicoaluminophosphate and/or an aluminophosphate molecular
sieve.
4. The catalyst composition of claim 1 wherein said metal oxide
comprises a magnesium oxide.
5. The catalyst composition of claim 4 further comprising a Group
3 metal oxide.
6. A catalyst composition comprising a molecular sieve and at least
one oxide of a metal selected from Group 2 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 mg/m.sup.2 of the metal oxide.
7. The catalyst composition of claim 6 wherein said metal oxide
has an uptake of carbon dioxide at 100.degree. C. of at least 0.35
mg/m.sup.2 of the metal oxide.
8. The catalyst composition of claim 6 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.
9. The catalyst composition of claim 6 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.
10. The catalyst composition of claim 6 and also including at least
one of a binder and a matrix material different from said metal
oxide.
11. The catalyst composition of claim 6 wherein said metal oxide
has a surface area greater than the binder and/or the matrix material.
12. The catalyst composition of claim 6 wherein said metal oxide
has a surface area greater than 20 m.sup.2/g.
13. The catalyst composition of claim 6 and also including a binder
and a matrix material each being different from one another and
from said metal oxide.
14. The catalyst composition of claim 13 wherein the binder comprises
an alumina sol and the matrix material comprises a clay.
15. The catalyst composition of claim 6 wherein said metal oxide,
when saturated with acetone and contacted with said acetone for
1 hour at 25.degree. C., converts more than 80% of the acetone.
16. The catalyst composition of claim 6 wherein said metal oxide
comprises a magnesium oxide.
17. The catalyst composition of claim 6 further comprising a Group
3 metal oxide.
18. The catalyst composition of claim 17 wherein the Group 3 metal
oxide is selected from yttrium oxide, lanthanum oxide, scandium
oxide and mixtures thereof.
19. The catalyst composition of claim 6 wherein the molecular sieve
comprises a framework consisting of two or three tetrahedral units
selected from [SiO.sub.4], [AlO.sub.4] and [PO.sub.4] units.
20. The catalyst composition of claim 6 wherein the molecular sieve
comprises a silicoaluminophosphate.
21. The catalyst composition of claim 6 wherein the molecular sieve
comprises a CHA framework-type molecular sieve.
22. The catalyst composition of claim 21 wherein the molecular
sieve further comprises an AEI framework-type molecular sieve.
23. The catalyst composition of claim 6 wherein the weight ratio
of the molecular sieve to metal oxide is in the range of from 1
percent to 800 percent.
24. A method for making a catalyst composition, the method comprising
physically mixing first particles comprising a molecular sieve with
second particles comprising at least one oxide of a metal selected
from Group 2 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 mg/m.sup.2 of the metal oxide.
25. The method of claim 24 wherein said second particles have a
surface area greater than 70 m.sup.2/g.
26. The method of claim 24 wherein said first particles comprise
a silicoaluminophosphate molecular sieve and/or an aluminophosphate
molecular sieve.
27. The method of claim 24 wherein at least one said first and
said second particles also include at least one of a binder and
a matrix material.
28. The method of claim 27 wherein said first particles comprise
a silicoaluminophosphate molecular sieve, a binder including an
alumina sol and a matrix material including a clay.
29. The method of claim 24 wherein said metal oxide, when saturated
with acetone and contacted with said acetone for 1 hour at 25.degree.
C., converts more than 25% of the acetone.
30. The method of claim 29 wherein said metal oxide comprises a
magnesium oxide.
31. The method of claim 24 wherein said second particles further
comprise at least one oxide of a metal selected from Group 3 of
the Periodic Table of Elements.
32. A method of making a catalyst composition, the method comprising
combining a molecular sieve, a binder, a matrix material, and at
least one metal oxide that, when saturated with acetone and contacted
with said acetone for 1 hour at 25.degree. C., converts more than
25% of the acetone.
33. The method of claim 32 wherein said at least one metal oxide,
when saturated with acetone and contacted with said acetone for
1 hour at 25.degree. C., converts more than 80% of the acetone.
34. The method of claim 32 wherein said at least one metal oxide
has a surface area of greater than 70 m.sup.2/g.
35. The method of claim 32 wherein said at least one 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.
36. The method of claim 32 wherein said at least one metal oxide
comprises a magnesium oxide.
37. The method of claim 36 wherein said at least one metal oxide
further comprises at least one oxide of a metal selected from Group
3 of the Periodic Table of Elements.
38. A method of making a catalyst composition, the method comprising
(a) combining a molecular sieve, a binder and a matrix material
to produce a catalyst precursor; and (b) adding to the catalyst
precursor a metal oxide that has been calcined to a temperature
in the range of from 200.degree. C. to 700.degree. C.
39. The method of claim 38 wherein said metal oxide, when saturated
with acetone and contacted with said acetone for 1 hour at 25.degree.
C., converts more than 25% of the acetone.
40. The method of claim 38 wherein said 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.
41. The method of claim 38 wherein the metal oxide comprises a
magnesium oxide.
42. The method of claim 41 wherein the method further comprises
the step (c) of introducing a Group 3 metal oxide selected from
yttrium oxide, lanthanum oxide and scandium oxide.
43. A method of making a 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 phosphorous source and an aluminum source; and (ii) recovering
the molecular sieve synthesized in step (i); (iii) calcining a magnesium
oxide or a magnesium oxide precursor at a temperature in the range
of from about 200.degree. C. to about 700.degree. C. to produce
an active magnesium oxide; and (iv) physically mixing the molecular
sieve recovered in step (i) and said active magnesium oxide.
44. The method of claim 43 wherein the active magnesium oxide has
an uptake of carbon dioxide at 100.degree. C. of at least 0.03 mg/m.sup.2
of the magnesium oxide.
45. The method of claim 43 wherein the active magnesium oxide has
a surface area in the range of from about 70 m.sup.2/g to about
600 m.sup.2/g.
46. The method of claim 43 wherein the molecular sieve and/or active
magnesium oxide is combined with a binder and/or a matrix material
prior to step (vi).
47. The method of claim 43 and including the further step of introducing
a Group 3 metal oxide into the catalyst composition.
48. 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 metal oxide
that, when saturated with acetone and contacted with said acetone
for 1 hour at 25.degree. C., converts more than 80% of the acetone.
49. The process of claim 48 wherein the metal oxide is calcined
to a temperature in the range of from 200.degree. C. to 700.degree.
C..
50. The process of claim 48 wherein the metal oxide has a surface
area of greater than 70 m.sup.2/g.
51. The process of claim 48 wherein said 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.
52. The process of claim 48 wherein said metal oxide is magnesium
oxide.
53. The process of claim 52 wherein the catalyst composition also
contains a Group 3 metal oxide.
54. The process of claim 48 wherein the feedstock comprises methanol
and/or dimethylether.
55. A process for converting a feedstock into one or more olefin(s)
in the presence of the catalyst composition prepared by the method
of claim 24.
56. A process for converting a feedstock into one or more olefin(s)
in the presence of the catalyst composition prepared by the method
of claim 32.
57. A process for converting a feedstock into one or more olefin(s)
in the presence of the catalyst composition prepared by the method
of claim 38.
58. A process for converting a feedstock into one or more olefin(s)
in the presence of the catalyst composition prepared by the method
of claim 43.
59. 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 small pore molecular sieve, a binder, a matrix material,
a magnesium oxide that has been calcined in the temperature range
of from 200.degree. C. to 700.degree. C., and a Group 3 metal oxide;
(b) withdrawing from the reactor system an effluent stream containing
the 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).
60. The process of claim 59 wherein the olefins(s) include ethylene
and propylene, the molecular sieve is a silicoaluminophosphate molecular
sieve, the feedstock comprises methanol, the magnesium oxide has
a surface area of greater than 80 m.sup.2/g, the binder is an alumina
sol, and the matrix material is a clay.
61. The process of claim 59 wherein the magnesium oxide, when saturated
with acetone and contacted with said acetone for 1 hour at 25.degree.
C., converts more than 80% of the acetone.
62. 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 small pore molecular sieve having an average
pore size less than 5A and an metal oxide having a surface area
of greater than 80 m.sup.2/g.
63. The integrated process of claim 62 wherein the 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.
64. The integrated process of claim 62 wherein the process further
comprises (d) polymerizing the one or more olefin(s) in the presence
of a polymerization catalyst into a polyolefin.
65. The integrated process of claim 62 wherein the oxygenated feedstock
comprises methanol, the olefin(s) include ethylene and propylene,
and the metal oxide is a magnesium oxide that has been calcined
in the temperature range of from 300.degree. C. to 575.degree. C.
Molecular sieve description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 USC 120
from U.S. Provisional Patent Application Serial No. 60/374697 filed
Apr. 22 2002 and is related to U.S. patent application Serial No.
60/360963 (Attorney Docket 2002B010) 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).
BACKGROUND
[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
AlPO.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 better conversion
rates, olefin selectivity, longer lifetimes, and commercially desirable
operability and cost advantages.
[0011] U.S. Pat. No. 4465889 describes a catalyst composition
comprising a silicalite molecular sieve impregnated with a thorium,
zirconium, or a 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, a 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 the catalyst with MgO, CaO, BaO or Cs.sub.2O
on microspherical non-porous silica, with BaO being 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:
[0018] (a) a metal oxide which has a surface area greater than
20 m.sup.2/g, which has been calcined at temperature greater than
200.degree. C., and which, when saturated with acetone and contacted
with said acetone for 1 hour at 25.degree. C., converts more than
80% of the acetone;
[0019] (b) a binder;
[0020] (c) a matrix material; and
[0021] (d) a molecular sieve having an average pore size less than
5 .ANG..
[0022] The molecular sieve conveniently comprises a framework including
at least [AlO.sub.4] and [PO.sub.4] tetrahedral units and more particularly
a framework including at least [SiO.sub.4], [AlO.sub.4] and [PO.sub.4]
tetrahedral units, such as a silicoaluminophosphate.
[0023] In one embodiment, the metal oxide includes magnesium oxide.
[0024] In another aspect, the invention resides in a catalyst composition
comprising a molecular sieve and at least one oxide of a metal selected
from Group 2 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 mg/m.sup.2 of the metal oxide.
[0025] Conveniently, the catalyst composition also comprises at
least one oxide of a metal selected from Group 3 of the Periodic
Table of Elements, such as yttrium oxide, lanthanum oxide, scandium
oxide and mixtures thereof.
[0026] In another aspect, the invention resides in a method for
making a catalyst composition, the method comprising physically
mixing first particles comprising a molecular sieve with second
particles comprising at least one oxide of a metal selected from
Group 2 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
mg/m.sup.2 of the metal oxide.
[0027] In another aspect, the invention resides in a method for
making a catalyst composition, the method comprising combining a
silicoaluminophosphate molecular sieve, a binder, a matrix material,
and at least one metal oxide that, when saturated with acetone and
contacted with said acetone for 1 hour at 25.degree. C., converts
more than 25% of the acetone.
[0028] In yet another aspect, the invention resides in a method
of making a catalyst composition, the method comprising (a) combining
a molecular sieve, a binder and a matrix material to produce a catalyst
precursor; and (b) adding to the catalyst precursor a metal oxide
that has been calcined to a temperature in the range of from 200.degree.
C. to 700.degree. C..
[0029] In one embodiment, the metal oxide is magnesium oxide and
is physically mixed with a molecular sieve synthesized from a reaction
mixture comprising at least one templating agent and at least two
of a silicon source, a phosphorous source and an aluminum source.
[0030] In a further aspect, the invention resides in 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 an active metal oxide that,
when saturated with acetone and contacted with said acetone for
1 hour at 25.degree. C., converts more than 80% of the acetone.
[0031] In yet a further aspect, the invention resides in a process
for producing one or more olefin(s), the process comprising:
[0032] (a) introducing a feedstock comprising at least one oxygenate
to a reactor system in the presence of a catalyst composition comprising
a small pore molecular sieve, a binder, a matrix material, a magnesium
oxide having been calcined in the temperature range of from 200.degree.
C. to 600.degree. C., and a Group 3 metal oxide;
[0033] (b) withdrawing from the reactor system an effluent stream
containing the one or more olefins; and
[0034] (c) passing the effluent stream through a recovery system;
and
[0035] (d) recovering at least the one or more olefin(s).
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] Introduction
[0037] The invention relates to a catalyst composition, its synthesis
and its use in the conversion of hydrocarbon feedstocks, particularly
oxygenated feedstocks, into olefin(s). It has been found that combining
a molecular sieve with a particular metal oxide results in a catalyst
composition with a longer catalyst 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 be more propylene selective and to yield lower amounts of unwanted
ethane and propane. The preferred metal oxide is an oxide of a Group
2 metal having an uptake of carbon dioxide at 100.degree. C. of
at least 0.03 mg/m.sup.2 of the metal oxide and/or a metal oxide
that is capable of converting greater than 80% of acetone at room
temperature. In one embodiment, the metal oxide is magnesium oxide
which has a surface area greater than 20 m.sup.2/g and which has
been calcined at temperature greater than 200.degree. C.. This unexpected
result is further enhanced when an oxide of a Group 3 metal (for
example scandium, lanthanum, or yttrium) 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) is combined with the magnesium oxide.
[0038] Molecular Sieves
[0039] Molecular sieves have been classified by the Structure Commission
of the International Zeolite Association according to the rules
of the IUPAC Commission on Zeolite Nomenclature. According to this
classification, framework-type zeolite and zeolite-type molecular
sieves, for which a structure has been established, are assigned
a three letter code and are described in the Atlas of zeolite Framework
Types, 5th edition, Elsevier, London, England (2001), which is herein
fully incorporated by reference.
[0040] Crystalline molecular sieves all have a 3-dimensional, four-connected
framework structure of corner-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-type characteristics include the arrangement
of rings that form a cage, and when present, the dimension of channels,
and the spaces between the cages. See van Bekkum, et al., Introduction
to Zeolite Science and Practice, Second Completely Revised and Expanded
Edition, Volume 137 pages 1-67 Elsevier Science, B. V., Amsterdam,
Netherlands (2001).
[0041] 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, HEU, FER, MEL, MFI, MTW, MTT, TON,
and substituted forms thereof; and the large pore molecular sieves,
EMT, FAU, and substituted forms thereof. Other molecular sieves
include ANA, BEA, CFI, CLO, DON, GIS, LTL, MER, MOR, MWW and SOD.
Non-limiting examples of preferred molecular sieves, particularly
for converting an oxygenate containing feedstock into olefin(s),
include AEL, AEI, AFY, BEA, CHA, EDI, FAU, FER, GIS, LTA, LTL, MER,
MFI, MOR, MTT, MWW, TAM and TON. In one preferred embodiment, the
molecular sieve of the invention has an AEI topology or a CHA topology,
or a combination thereof, most preferably a CHA topology.
[0042] 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
4.3 .ANG..
[0043] Molecular sieves have a molecular framework of one, preferably
two or more corner-sharing [TO.sub.4] tetrahedral units, more preferably,
two or more [SiO.sub.4], [AlO.sub.4] and/or [PO.sub.4] tetrahedral
units, and most preferably [SiO.sub.4], [AlO.sub.4] and [PO.sub.4]
tetrahedral units. These silicon, aluminum, and phosphorus based
molecular sieves and metal containing silicon, aluminum and phosphorus
based molecular sieves have been described in detail in numerous
publications including for example, U.S. Pat. No. 4567029 (MeAPO
where Me is Mg, Mn, Zn, or Co), U.S. Pat. No. 4440871 (SAPO),
European Patent Application EP-A-0 159 624 (ELAPSO where El is As,
Be, B, Cr, Co, Ga, Ge, Fe, Li, Mg, Mn, Ti or Zn), U.S. Pat. No.
4554143 (FeAPO), U.S. Pat. Nos. 4822478 4683217 4744885
(FeAPSO), EP-A-0 158 975 and U.S. Pat. No. 4935216 (ZnAPSO, EP-A-0
161 489 (CoAPSO), EP-A-0 158 976 (ELAPO, where EL is Co, Fe, Mg,
Mn, Ti or Zn), U.S. Pat. No. 4310440 (AlPO.sub.4), EP-A-0 158
350 (SENAPSO), U.S. Pat. No. 4973460 (LiAPSO), U.S. Pat. No. 4789535
(LiAPO), U.S. Pat. No. 4992250 (GeAPSO), U.S. Pat. No. 4888167
(GeAPO), U.S. Pat. No. 5057295 (BAPSO), U.S. Pat. No. 4738837
(CrAPSO), U.S. Pat. Nos. 4759919 and 4851106 (CrAPO), U.S.
Pat. Nos. 4758419 4882038 5434326 and 5478787 (MgAPSO),
U.S. Pat. No. 4554143 (FeAPO), U.S. Pat. No. 4894213 (AsAPSO),
U.S. Pat. No. 4913888 (AsAPO), U.S. Pat. Nos. 4686092 4846956
and 4793833 (MnAPSO), U.S. Pat. Nos. 5345011 and 6156931 (MnAPO),
U.S. Pat. No. 4737353 (BeAPSO), U.S. Pat. No. 4940570 (BeAPO),
U.S. Pat. Nos. 4801309 4684617 and 4880520 (TiAPSO), U.S.
Pat. Nos. 4500651 4551236 and 4605492 (TiAPO), U.S. Pat.
Nos. 4824554 4744970 (CoAPSO), U.S. Pat. No. 4735806 (GaAPSO)
EP-A-0 293 937 (QAPSO, where Q is framework oxide unit [QO.sub.2]),
as well as U.S. Pat. Nos. 4567029 4686093 4781814 4793984
4801364 4853197 4917876 4952384 4956164 4956165
4973785 5241093 5493066 and 5675050 all of which are
herein fully incorporated by reference.
[0044] 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.
[0045] The more preferred molecular sieves include aluminophosphate
(AlPO) molecular sieves and silicoaluminophosphate (SAPO) molecular
sieves and substituted, preferably metal substituted, AlPO and SAPO
molecular sieves. The most preferred molecular sieves are SAPO molecular
sieves, and metal substituted SAPO molecular sieves. In an embodiment,
the metal is an alkali metal of Group 1 of the Periodic Table of
Elements, an alkaline earth metal of Group 2 of the Periodic Table
of Elements, a rare earth metal of Group 3 of the Periodic Table
of Elements, including the Lanthanides lanthanum, cerium, praseodymium,
neodymium, samarium, europium, gadolinium, terbium, dysprosium,
holmium, erbium, thulium, ytterbium 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.
[0046] 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
[0047] wherein R represents at least one templating agent, preferably
an organic templating agent; m is the number of moles of R per mole
of (M.sub.xAl.sub.yP.sub.z)O.sub.2 and has a value from 0 to 1
preferably 0 to 0.5 and most preferably from 0 to 0.3; x, y, and
z represent the mole fraction of Al, P and M as tetrahedral oxides,
where M is a metal selected from one of 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, Fe, Ga, Ge, Mg, Mn, Ni, Sn, Ti, Zn and Zr. In
an embodiment, m is greater than or equal to 0.2 and x, y and z
are greater than or equal to 0.01. In another embodiment, m is greater
than 0.1 to about 1 x is greater than 0 to about 0.25 y is in
the range of from 0.4 to 0.5 and z is in the range of from 0.25
to 0.5 more preferably m is from 0.15 to 0.7 x is from 0.01 to
0.2 y is from 0.4 to 0.5 and z is from 0.3 to 0.5.
[0048] Non-limiting examples of SAPO and AlPO 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 AlPO-5 AlPO-11 AlPO-18 AlPO-31 AlPO-34 AlPO-36
AlPO-37 AlPO-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 AlPO-18 and AlPO-34
and metal containing derivatives thereof, such as one or a combination
of SAPO-18 SAPO-34 AlPO-34 and AlPO-18 and metal containing derivatives
thereof, and especially one or a combination of SAPO-34 and AlPO-18
and metal containing derivatives thereof.
[0049] 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. 7 2001 and International Publication No. WO 98/15496
published Apr. 16 1998 both of which are herein fully incorporated
by reference. For example, SAPO-18 AlPO-18 and RUW-18 have an AEI
framework-type, and SAPO-34 has a CHA framework-type. 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 framework-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.
[0050] In one particular embodiment, the molecular sieve is SAPO-18
SAPO-34 or an intergrowth thereof in which the framework of the
molecular sieves consists essentially of [SiO.sub.4], [AlO.sub.4]
and [PO.sub.4] tetrahedral units and hence is free of additional
framework elements, such as nickel.
[0051] Molecular Sieve Synthesis
[0052] 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.
[0053] Non-limiting examples of silicon sources include silicates,
fumed silica, for example, Aerosil-200 available from Degussa Inc.,
New York, N.Y., and CAB-O-SIL M-5 organosilicon compounds such
as tetraalkyl orthosilicates, for example, tetramethyl orthosilicate
(TMOS) and tetraethylorthosilicate (TEOS), colloidal silicas or
aqueous suspensions thereof, for example Ludox HS-40 sol available
from E.I. du Pont de Nemours, Wilmington, Del., silicic acid or
any combination thereof.
[0054] 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.
[0055] 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 AlPO.sub.4 phosphorus salts,
or combinations thereof. A convenient source of phosphorus is phosphoric
acid, particularly when producing a silicoaluminophosphate.
[0056] 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.
[0057] 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)oct- ane ion; di-n-butylamine,
neopentylamine, di-n-pentylamine, isopropylamine, t-butyl-amine,
ethylenediamine, pyrrolidine, and 2-imidazolidone.
[0058] 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.
[0059] 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..
[0060] In one embodiment, the synthesis of a molecular sieve is
aided by seeds from another or the same framework type molecular
sieve.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] Metal Oxides
[0068] The 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 benefits in
catalytic conversion processes. In particular, the metal oxides
useful herein are oxides of Group 2 metals, either alone or in combination
with Group 3 metal oxides, which 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 0.35 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.
[0069] In order to determine the carbon dioxide uptake of a metal
oxide, the following procedure is adopted using a Mettler TGA/SDTA
851 thermogravimetric analysis system under ambient pressure. A
sample of the metal oxide is 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] Suitable metal oxides are those metal oxides that have a
surface area greater than 20 m.sup.2/g, that have been calcined
to greater than 200.degree. C., and are capable of converting greater
than 25%, such as greater than 50%, for example greater than 80%
of acetone at room temperature.
[0071] The most preferred Group 2 metal oxide is a magnesium oxide
(MgO). Suitable Group 3 metal oxides include yttrium oxide, lanthanum
oxide, scandium oxide and mixtures thereof.
[0072] In one embodiment, the active metal oxide, preferably the
MgO, even more preferably the combination of the MgO and a Group
3 metal oxide, has a surface area as measured in accordance with
the method of Brunauer, Emmett, and Teller (BET) published as ASTM
D 3663 of greater than 20 m.sup.2/g, such as greater than 50 m.sup.2/g,
for example greater than 80 m.sup.2/g, and even greater than 200
m.sup.2/g.
[0073] In another embodiment, the metal oxide, preferably the magnesium
oxide, even more preferably the MgO and a Group 3 metal oxide, is
calcined at a temperature in the range of from 200.degree. C. to
700.degree. C., such as from about 250.degree. C. to 650.degree.
C., for example in the range of from 300.degree. C. to 600.degree.
C., and typically from 350.degree. C. to about 550.degree. C..
[0074] In one embodiment, the magnesium metal oxide has a surface
area of about 250 m.sup.2/g, and/or the magnesium oxide is calcined
to about 550.degree. C..
[0075] In an embodiment, the active metal oxide, when saturated
with acetone and contacted with said acetone for 1 hour at room
temperature (about 25.degree. C.), converts greater than 80% of
the acetone, for example greater than 85%, such as greater than
90%, and in some cases greater than 95%. There are a variety of
methods for determining the conversion of acetone, and one such
method is the use of .sup.13C solid state NMR. In this method, the
metal oxide is first dehydrated under vacuum while being heated
by the use of a stepwise temperature program. Typically, the highest
temperature used in the dehydration procedure is 400.degree. C..
The metal oxide is then saturated with acetone-2-.sup.13C at room
temperature (ca. 25.degree. C.) by the use of conventional vacuum
line technique. The metal oxide with adsorbed acetone-2-.sup.13C
is transferred into a 7-mm NMR rotor without any contact with air
or moisture. Quantitative .sup.13C solid state NMR spectra with
Magic Angle Spinning are acquired to determine the conversion of
acetone after the sample has been kept at 25.degree. C. for 1 hour.
[0076] The active metal oxides can be prepared using a variety
of methods. The active metal oxides can be made from active metal
oxide precursors, such as metal salts, preferably Group 2 or Group
3 metal salt precursors. Other suitable sources of the Group 2 metal
oxide include compounds that form these metal oxides during calcination,
such as oxychlorides and nitrates. A further suitable source of
the Group 2 or Group 3 metal oxides include salts containing the
cation of the Group 2 or Group 3 metals, such as halides, nitrates,
and acetates. Alkoxides are also sources of the Group 2 or Group
3 metal oxides.
[0077] In one method, the active metal oxide is prepared by the
thermal decomposition of metal-containing compounds, such as magnesium
oxalate and barium oxalate, at high temperatures, such as 600.degree.
C., in flowing air. Thus prepared metal oxides usually have low
BET surface area, e.g., less than 30 m.sup.2/g.
[0078] In another method, the active metal oxide is prepared by
the hydrolysis of metal-containing compounds followed by dehydration
and calcination. For example, MgO is hydroxylated by mixing the
oxide with deionized water, forming a white slurry. The slurry is
slowly heated to dryness on a heating plate to form white powder.
The white powder is further dried in a vacuum oven at 100.degree.
C. for at least 4 hrs, such as for 12 hrs. The dried white powder
is then calcined in air at a temperature of at least 400.degree.
C., such as at least 500.degree. C., and typically at least 550.degree.
C.. Thus-prepared active metal oxides generally have higher BET
surface area (between 30 to 300 m.sup.2/g) than that prepared by
thermal decomposition of the active metal oxide precursors.
[0079] In yet another method, the active metal oxide is prepared
by the so-called aerogel method (Koper, O. B., Lagadic, I., Volodin,
A. and Klabunde, K. J. Chem. Mater. 1997 9 2468-2480). In this
method, Mg powder is reacted under nitrogen purge with anhydrous
methanol to form Mg(OCH.sub.3).sub.2 solution in methanol. The resultant
Mg(OCH.sub.3).sub.2 solution is added to toluene. Water is then
added dropwise to the Mg(OH).sub.2 solution in methanol-toluene
under vigorous stirring. The resultant colloidial suspension of
Mg(OH).sub.2 is placed in an autoclave, pressurized to 100 psig
(690 kPag) with dry nitrogen, and heated slowly to a final pressure
of about 1000 psig (6895 kpag). The supercritical solvent is vented
to produce a fine white powder of Mg(OH).sub.2. Nanocrystalline
MgO is obtained by heating the fine white powder at 400.degree.
C. under vacuum. Such prepared active metal oxides have the highest
BET surface area, generally greater than 300 m.sup.2/g.
[0080] Various methods exist for making mixed metal oxides from
Group 2 and Group 3 metal oxide precursors, e.g., wet impregnation,
incipient wetness and co-precipitation.
[0081] In one embodiment, mixed metal oxides are prepared by impregnating
a Group 3 metal oxide precursor onto a Group 2 metal oxide. In a
typical preparation, a Group 3 metal oxide precursor such as La(acetylacetonate).sub.3
is dissolved in an organic solvent such as toluene. The amount of
solvent used is enough to fill the mesoporous and macroporous volume
of the Group 2 metal oxide. The Group 3 metal oxide precursor solution
is added dropwise to the Group 2 metal oxide. The wet mixture is
dried in a vacuum oven for 1 to 12 hours to remove the solvent.
The resulting solid mixture is then calcined at a temperature, e.g.,
400.degree. C., high enough to decompose the Group 3 metal oxide
precursor into an oxide.
[0082] In another embodiment, a mixed oxide is prepared by the
incipient wetness technique. Typically, a Group 3 metal oxide precursor
such as lanthanum acetate is dissolved in deionized water. The solution
is added dropwise to a Group 2 metal oxide. The mixture is dried
in a vacuum oven at 50.degree. C. for 1 to 12 hours. The dried mixture
is broken up and calcined at 550.degree. C. in air for 3 hours.
[0083] In yet another embodiment, a mixed metal oxide is prepared
by co-precipitation. An aqueous solution comprising Group 2 and
Group 3 metal oxide precursors is subject to conditions sufficient
to cause precipitation of a hydrated precursor of the solid oxide
materials, such as by the addition of sodium hydroxide or ammonium
hydroxide. The temperature at which the liquid medium is maintained
during the co-precipitation is typically from about 20.degree. C.
to about 100.degree. C. The resulting gel is then hydrothermally
treated at temperatures between 50 and 100.degree. C. for several
days. The hydrothermal treatment typically takes place at greater
than atmospheric pressure.
[0084] The resulting material is then recovered, for example by
filtration or centrifugation, and washed and dried. The resulting
material is then calcined at a temperature of greater than 200.degree.
C., preferably greater than 300.degree. C., and more preferably
greater 400.degree. C., and most preferably greater than 450.degree.
C.
[0085] Molecular Sieve Composition
[0086] The catalyst composition of the invention includes any one
of the molecular sieves previously described and one or more active
metal oxides described above, optionally together with a binder
and/or matrix material different from the active metal oxide(s).
Typically, the weight ratio of the active metal oxide(s) to the
molecular sieve in the catalyst composition is in the range of from
about 1 weight percent to about 800 weight percent, such as from
about 5 weight percent to about 200 weight percent, particularly
from about 10 weight percent to about 100 weight percent.
[0087] 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.
[0088] 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.
[0089] 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.
[0090] 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.
[0091] 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.
[0092] 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.
[0093] 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.
[0094] 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.
[0095] 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.
[0096] Method of Making The Catalyst Composition
[0097] In making the catalyst composition, the molecular sieve
is first formed and is then physically mixed with the Group 2 metal
oxide described above, or with a mixture of Group 2 and Group 3
metal oxides, 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.
[0098] 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.
[0099] 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.
[0100] 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.
[0101] 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.
[0102] When a spray drier is used as the forming unit, typically,
the slurry of the molecular sieve composition and 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.
[0103] 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.
[0104] 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 1000.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.
[0105] 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.
[0106] Process for Using the Molecular Sieve Catalyst Compositions
[0107] 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.
[0108] 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.
[0109] 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.
[0110] 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.
[0111] 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.
[0112] 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.
[0113] 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.
[0114] 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.
[0115] 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.
[0116] 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.
[0117] 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).
[0118] 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.
[0119] 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.
[0120] 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.
[0121] 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.
[0122] 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.sup.-1 to about 5000 hr.sup.-1 such as from about
2 hr.sup.-1 to about 3000 hr.sup.-1 for example from about 5 hr.sup.-1
to about 1500 hr.sup.-1 and conveniently from about 10 hr.sup.-1
to about 1000 hr.sup.-1. In one embodiment, the WHSV is greater
than 20 hr.sup.-1 and, where feedstock contains methanol and/or
dimethyl ether, is in the range of from about 20 hr.sup.-1 to about
300 hr.sup.-1.
[0123] 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.
[0124] 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.
[0125] 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.
[0126] 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.
[0127] 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.
[0128] 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.
[0129] 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.
[0130] 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.
[0131] 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.
[0132] 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.
[0133] Non-limiting examples of suitable regeneration media include
one or more of oxygen, O.sub.3 SO.sub.3 N.sub.2O, NO, NO.sub.2
N.sub.2O.sub.5 air, air diluted with nitrogen or carbon dioxide,
oxygen and water (U.S. Pat. No. 6245703), carbon monoxide and/or
hydrogen. Suitable regeneration conditions are those capable of
burning coke from the coked catalyst composition, preferably to
a level less than 0.5 weight percent based on the total weight of
the coked molecular sieve catalyst composition entering the regeneration
system. For example, the regeneration temperature may be in the
range of from about 200.degree. C. to about 1500.degree. C., such
as from about 300.degree. C. to about 1000.degree. C., for example
from about 450.degree. C. to about 750.degree. C., and conveniently
from about 550.degree. C. to 700.degree. C. The regeneration pressure
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).
[0134] 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.
[0135] 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.
[0136] 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).
[0137] 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.
[0138] 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.
[0139] 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.
[0140] 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.
[0141] 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. 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.
[0142] Other recovery systems that include purification systems,
for example for the purification of olefin(s), are described in
Kirk-Other 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.
[0143] 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.
[0144] 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.
[0145] Typically, in converting one or more oxygenates to olefin(s)
having 2 or 3 carbon atoms, a minor amount hydrocarbons, particularly
olefin(s), having 4 or more carbon atoms is also produced. The amount
of C.sub.4+ hydrocarbons is normally less than 20 weight percent,
such as less than 10 weight percent, for example less than 5 weight
percent, and particularly less than 2 weight percent, based on the
total weight of the effluent gas withdrawn from the process, excluding
water. Typically, therefore the recovery system may include one
or more reaction systems for converting the C.sub.4+ impurities
to useful products.
[0146] 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.
[0147] 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.
[0148] 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.
[0149] 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.
[0150] 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.
[0151] 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.
[0152] 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.)
[0153] 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-Natta, Phillips-type, metallocene, metallocene-type
and advanced polymerization catalysts, and mixtures thereof.
[0154] 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.
[0155] 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
[0156] In order to provide a better understanding of the present
invention including representative advantages thereof, the following
examples are offered.
Example A
[0157] Preparation of a Molecular Sieve
[0158] A silicoaluminophosphate molecular sieve, SAPO-34 designated
as MSA, was crystallized in the presence of tetraethyl ammonium
hydroxide (RI) and dipropylamine (R2) as the organic structure directing
agents or templating agents. A mixture of the following mole ratio
composition:
[0159] 0.2 SiO.sub.2/Al.sub.2O.sub.3/P.sub.2O.sub.5/0.9 R1/1.5
P2/50 H.sub.2O.
[0160] 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
[0161] Conversion Process
[0162] All catalytic or conversion data presented were 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 is fed. The methanol conversion reactions were
preformed at 475.degree. C., 25 psig (172 kPag) and 100 WHSV (with
respect to the amount of SAPO-34). The typical charge of formulated
SAPO 34 described in Example A was 95 mg and the reactor bed was
diluted with 1 gram of quartz sand to minimize the reaction exotherm
in the reactor. In particular, for the catalyst composition of the
invention, the molecular sieve and metal oxide, a physical mixture
of the MSA molecular sieve of Example A and the active metal oxide
was used.
[0163] The effluent from the reactor was collected in a 15-sample
loop Valco valve. The collected samples were analyzed by on-line
gas chromatography (Hewlett Packard 6890) equipped with a flame
ionization detector. The chromatographic column used was a Q-column.
The response factors used are listed in the following Table 1.
1TABLE 1 C.sub.1 C.sub.2 = C.sub.2.sup.o C.sub.3 = C.sub.3.sup.o
CH.sub.3OH (CH.sub.3).sub.2O C.sub.4's C.sub.5's C.sub.6's C.sub.7's
1.103 1.000 1.070 1.003 1.052 3.035 2.639 0.993 0.999 1.006 1.000
[0164] The terms "C.sub.4's, C.sub.5+, etc." refer to
the number of carbons in the hydrocarbon. Note that the selectivity
designated as "C.sub.5+'s" consist of the sum of C5'S,
C.sub.6's and C.sub.7's. The weighed averages (selectivity) were
calculated based on the following formula, x.sub.1*y.sub.1+(x.sub.2-x.sub.1)*(y.sub.1+y.sub.2)/2+(x.sub.3-x-
.sub.2)*(y.sub.2+y.sub.3)/2+ . . . , where x.sub.1 and y.sub.1 are
yield and g methanol fed/g molecular sieve, respectively. Lifetime
of catalysts (g methanol/g molecular sieve) reported is methanol
that was cumulatively converted. Note that both the lifetime and
WHSV were reported based on the weight of the SAPO-34 sieve. Methanol
converted at less than 10 weight percent conversions was not counted
in the calculations. Dimethyl ether was not counted as product,
instead it was treated as unreacted methanol in calculating selectivity
and conversions.
Example 1
[0165] Control Experiment
[0166] In this Example 1 the catalyst composition consisted of
a molecular sieve, designated as MSA as described in Example A.
The catalyst was diluted with quartz to form the reactor bed. The
results of this experiment in the reactor and conditions discussed
above in Example B are shown in Table 2.
2TABLE 2 C.sub.1 C.sub.2 = C.sub.2.sup.o C.sub.3 = C.sub.3.sup.o
C.sub.4s C.sub.5.sup.+s C.sub.2+3 = Lifetime g/g 1.77 37.65 0.29
39.80 0.63 13.04 6.82 77.45 16.34
Example 2
[0167] Preparation of MgO and Acetone Conversion Measurement
[0168] The MgO was prepared as follows. 5.0 g of MgO (98%, ACS
reagent grade from Aldrich) was mixed with 150 ml of deionized water
to form a white slurry. The white slurry was slowly heated to dryness
on a heating plate. The dried cake was broken into pieces and was
ground to a fine powder. The powder was further dried in an oven
at 120.degree. C. for 12 hrs. The white powder was then calcined
at 550.degree. C. in air for 3 hrs. Thus the prepared active metal
oxide, MgO, has a relatively high surface area (BET area of about
250 m.sup.2/g). The MgO powders were sieved to get particles of
various sizes. Particle sizes between 75 to 150 micron were used
in a conversion process as described in Example B.
[0169] 0.25 g of this prepared MgO was loaded into a glass tube,
and the tube was connected to a vacuum line via a 9-mm O-ring joint.
The MgO was then heated to 450.degree. C. and kept at 450.degree.
C. for 2 hrs under vacuum to remove water from the oxide. After
cooling down to room temperature, 25.degree. C., the MgO was saturated
with acetone-2-.sup.13C. The MgO with adsorbed acetone-2-.sup.13C
was then loaded into a 7-mm NMR rotor without any contact with air
or moisture. The sample was allowed to stay at room temperature
(about 25.degree. C.) for 1 hour prior to NMR measurement of acetone
conversion. .sup.13C NMR experiments were performed on a 200 MHz
solid state NMR spectrometer with Magic Angle Spinning. Cross polarization
spectra were acquired using 1-s pulse delay, 2-ms contact time and
2000 scans. Quantitative single pulse spectra were acquired using
15-s pulse delay and 400 or more scans. The test was repeated and
results of the .sup.13C NMR revealed that, on average, after 1 hour
more than 80% of acetone had been consumed.
Example 3
[0170] Molecular Sieve and MgO
[0171] In this Example 3 the molecular sieve catalyst composition
consisted of 33.6 wt % of MSA, 50.4 wt % of binder and 16 wt % MgO
as described in Example 2 above. The catalyst composition was well
mixed, and then diluted with quartz to form the reactor bed. The
results of this experiment in the reactor and conditions discussed
above in Example B are shown in Table 3. The data in Table 2 and
Table 3 illustrate that by constituting 16 wt % of the catalyst
composition loading with the MgO, the lifetime of the SAPO-34 molecular
sieve has increased to 31.66 g/g molecular sieve from 16.34 g/g
molecular sieve, an increase of 94%.
3TABLE 3 Lifetime C.sub.1 C.sub.2 = C.sub.2.sup.o C.sub.3 = C.sub.3.sup.o
C.sub.4s C.sub.5 + s C.sub.2+3 = g/g 1.73 36.86 0.27 40.74 0.53
14.01 5.87 77.59 31.66
Example 4
[0172] Mixing MgO with a Group 3 Metal Oxide (5 wt % La.sub.2O.sub.3)
[0173] The loading of a Group 3 metal oxide where the metal is
La onto the high surface area MgO was achieved via incipient wetness.
0.2261 g of Lanthanum acetate was dissolved in ca. 1.9 ml of deionized
water. The solution was added drop-wise to 2.0146 g of MgO. The
mixture was dried in a vacuum oven at 50.degree. C. for 1 hr. The
dried mixture was broken up and calcined at 550.degree. C. in air
for 3 hrs. The wt % of La.sub.2O.sub.3 is about 5%. The metal oxides
powders were sieved to get particles of various sizes. Particle
sizes between 75 to 150 micron were used in a conversion process.
Example 5
[0174] Molecular Sieve and a Mixed Metal Oxide: La.sub.2O.sub.3
(5 wt %)/MgO
[0175] In this Example 5 the catalyst composition consisted of
33.6 wt % of MSA, 50.4 wt % of binder and 16 wt % of MgO containing
5 weight percent of a Group 3 metal oxide wherein the metal is La,
as described in Example 4 above. The catalyst composition was well
mixed, and then diluted with quartz to form the reactor bed. The
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