Molecular sieve abstract
Disclosed is a method for making molecular sieve catalyst particles.
Dried molecular sieve catalyst particles are used to make the catalyst.
The dried molecular sieve catalyst particles are put into an aqueous
solution and stirred to make a slurry. The slurry is dried to make
the molecular sieve catalyst particles. Optionally, the dried molecular
sieve catalyst particles made from the slurry are calcined.
Molecular sieve claims
What is claimed is:
1. A method of making molecular sieve catalyst particles, comprising
a) providing a first dried molecular sieve catalyst; b) combining
the first dried molecular sieve catalyst with water to form a water-catalyst
composition; c) mixing the water-catalyst composition to form a
slurry; and d) drying the slurry to form particles of a second dried
molecular sieve catalyst.
2. The method of claim 1 wherein the water used in b) comprises
at least 95 wt %, preferably at least 97 wt %, most preferably at
least 98 wt % water.
3. The method of claim 1 wherein the water used in b) is substantially
free of any molecular sieve particle.
4. The method of claim 1 wherein the first dried molecular sieve
catalyst contains template material.
5. The method of claim 4 wherein the template is selected from
the group consisting of triethylamine, cyclohexylamine, piperidine,
dipropylamine, pyridine, isopropylamine, tetraethyl ammonium salts,
and mixtures thereof.
6. The method of claim 1 wherein the first dried molecular sieve
catalyst comprises catalyst particles.
7. The method of claim 6 wherein the water-catalyst composition
is mixed so that the slurry obtained in c) contains particles smaller
than the particles contained in the first dried molecular sieve
composition.
8. The method of claim 1 further comprising e) calcining the particles
of said second dried molecular sieve catalyst.
9. The method of claim 6 wherein the particle size of the first
dried molecular sieve catalyst is such that, after calcination,
10 wt % of the particles have an average particle diameter less
than or equal to 20 .mu.m.
10. The method of claim 1 wherein the water is at a substantially
neutral pH prior to combining with the first dried molecular sieve
catalyst.
11. The method of claim 1 wherein the slurry has a viscosity of
from 100 cP to 9000 cP measured using a Brookfield LV-DVE viscometer
with a No. 3 spindle at 10 rpm.
12. The method of claim 1 wherein the slurry prepared in c) has
a solids content of from 10 wt % to 75 wt %.
13. The method of claim 8 wherein the molecular sieve catalyst
particles obtained in e) have an EMARI of not greater than 1 wt
%/hr, preferably not greater than 0.7 wt %/hr, most preferably not
greater than 0.3 wt %/hr.
14. The method of claim 8 wherein the molecular sieve catalyst
particles obtained in e) have a particle size such that 50% of the
particles have a diameter larger than 30 .mu.m and smaller than
150 .mu.m.
15. The method of claim 1 wherein drying the slurry in d) is by
spray drying.
16. The method of claim 1 wherein the first dried molecular sieve
catalyst comprises a silicoaluminophosphate molecular sieve.
17. The method of claim 16 wherein the silicoaluminophosphate
molecular sieve is selected from the group consisting of SAPO-18
SAPO-34 SAPO-35 SAPO-44 SAPO-56 ALPO-18 and ALPO-34 metal containing
molecular sieves thereof, and mixtures thereof.
18. The method of claim 17 wherein silicoaluminophosphate molecular
sieve is selected from the group consisting of SAPO-18 SAPO-34
ALPO-34 and ALPO-18 metal containing molecular sieves thereof,
and mixtures thereof.
19. The method of claim 18 wherein the silicoaluminophosphate
molecular sieve is selected from the group consisting of silicoaluminphosphate
molecular sieves having CHA, AEI or a combination of CHA and AEI
framework type.
20. The method of claim 1 wherein the first dried molecular sieve
catalyst comprises a binder selected from the group consisting of
hydrated alumina, silicas, and/or other inorganic oxide sol.
21. The method of claim 20 wherein the binder is aluminium chlorohydrate.
22. The method of claim 1 wherein the first dried molecular sieve
catalyst comprises a filler selected from the group consisting of
clays, clay-type compositions and mixtures thereof.
23. A method of recycling molecular sieve catalyst particles having
undesired properties, comprising (i) mixing a composition comprising
molecular sieve, binder and water; (ii) drying the composition to
form a first dried molecular sieve catalyst; (iii) combining at
least a portion of the first dried molecular sieve catalyst with
water to form a water-catalyst composition; (iv) mixing the water-catalyst
composition to form a slurry; (v) drying the slurry to form particles
of a second dried molecular sieve catalyst.
24. The method of claim 23 further comprising (vi) calcining the
particles of said second dried molecular sieve catalyst.
25. The method of claim 24 wherein the molecular sieve catalyst
particles obtained in e) have an EMARI of not greater than 1 wt
%/hr, preferably not greater than 0.7 wt %/hr, most preferably not
greater than 0.3 wt %/hr.
26. The method of claim 24 wherein the molecular sieve catalyst
particles obtained in e) have a particle size such that 50% of the
particles have a diameter larger than 30 .mu.m and smaller than
150 .mu.m.
27. The method of claim 23 wherein drying the slurry in d) is
by spray drying.
28. The method of claim 23 wherein the first dried molecular sieve
catalyst comprises a silicoaluminophosphate molecular sieve.
29. The method of claim 28 wherein the silicoaluminophosphate
molecular sieve is selected from the group consisting of SAPO-18
SAPO-34 SAPO-35 SAPO-44 SAPO-56 ALPO-18 and ALPO-34 metal containing
molecular sieves thereof, and mixtures thereof.
30. The method of claim 28 wherein silicoaluminophosphate molecular
sieve is selected from the group consisting of SAPO-18 SAPO-34
ALPO-34 and ALPO-18 metal containing molecular sieves thereof,
and mixtures thereof.
31. The method of claim 28 wherein the silicoaluminophosphate
molecular sieve is selected from the group consisting of silicoaluminphosphate
molecular sieves having CHA, AEI or a combination of CHA and AEI
framework type.
32. The method of claim 23 wherein the first dried molecular sieve
catalyst comprises a binder selected from the group consisting of
hydrated alumina, silicas, and/or other inorganic oxide sol.
33. The method of claim 32 wherein the binder is aluminum chlorohydrate.
34. The method of claim 23 wherein the first dried molecular sieve
catalyst comprises a filler selected from the group consisting of
clays, clay-type compositions and mixtures thereof.
35. A method of making a molecular sieve catalyst composition,
comprising: providing first dried molecular sieve catalyst particles,
wherein the first dried molecular sieve catalyst particles yield,
upon calcining, a calcined molecular sieve composition having greater
than 5 wt % catalyst particles having an average particle diameter
greater than or equal to 250 microns; combining the dried molecular
sieve catalyst particles with water to form a slurry; and drying
the slurry to form the molecular sieve catalyst composition.
36. The method of claim 35 wherein the provided first dried molecular
sieve catalyst particles contain template material.
37. The method of claim 35 wherein the provided first dried molecular
sieve catalyst particles are mixed with the water so that at least
a portion of the first dried molecular sieve catalyst particles
break apart.
38. The method of claim 35 wherein the provided first dried molecular
sieve catalyst particles yield, upon calcining, a calcined molecular
sieve composition having greater than 10 wt % catalyst particles
having an average particle diameter less than or equal to 10 microns;
39. The method of claim 35 further comprising combining the provided
first dried molecular sieve catalyst particles with water prior
to mixing, wherein the water is at a substantially neutral pH prior
to adding the particles.
40. The method of claim 35 wherein the slurry has a viscosity
of from 100 cP to 9000 cP measured using a Brookfield LV-DVE viscometer
with a No. 3 spindle at 10 rpm.
41. The method of claim 35 wherein the slurry has a solids content
of from 10 wt %to 75 wt %.
42. The method of claim 35 further comprising calcining the molecular
sieve catalyst composition formed from drying the slurry.
43. The method of claim 42 wherein the calcined molecular sieve
catalyst particles have an EMARI of not greater than 1 wt %/hr,
preferably not greater than 0.7 wt %/hr, most preferably not greater
than 0.3 wt %/hr.
44. The method of claim 42 wherein the calcined molecular sieve
catalyst particles have a particle size such that 50% of the particles
have a diameter larger than 30 .mu.m and smaller than 150 .mu.m.
45. The method of claim 35 wherein drying the slurry in d) is
by spray drying.
46. The method of claim 35 wherein the provided first dried molecular
sieve catalyst comprises a silicoaluminophosphate molecular sieve.
47. The method of claim 46 wherein the silicoaluminophosphate
molecular sieve is selected from the group consisting of SAPO-18
SAPO-34 SAPO-35 SAPO-44 SAPO-56 ALPO-18 and ALPO-34 metal containing
molecular sieves thereof, and mixtures thereof.
48. The method of claim 46 wherein silicoaluminophosphate molecular
sieve is selected from the group consisting of SAPO-18 SAPO-34
ALPO-34 and ALPO-18 metal containing molecular sieves thereof,
and mixtures thereof.
49. The method of claim 46 wherein the silicoaluminophosphate
molecular sieve is selected from the group consisting of silicoaluminphosphate
molecular sieves having CHA, AEI or a combination of CHA and AEI
framework type.
50. The method of claim 35 wherein the provided first dried molecular
sieve catalyst comprises a binder selected from the group consisting
of hydrated alumina, silicas, and/or other inorganic oxide sol.
51. The method of claim 50 wherein the binder is aluminium chlorohydrate.
52. The method of claim 51 wherein the first dried molecular sieve
catalyst comprises a filler selected from the group consisting of
clays, clay-type compositions and mixtures thereof.
53. A calcined molecular sieve catalyst composition comprising
catalyst particles, wherein the catalyst particles, after being
submitted to calcination, have an EMARI of equal or less than 0.7
wt %/hr, preferably less than 0.3 wt %/hr.
54. A method of making an olefin product, comprising the steps
of contacting a feedstock comprising at least one oxygenate with
molecular sieve particles prepared according to the method of claim
1.
Molecular sieve description
FIELD OF THE INVENTION
[0001] This invention relates to a method of making molecular sieve
catalyst. In particular, this invention relates to a method of making
molecular sieve catalyst from dried molecular sieve catalyst particles.
BACKGROUND OF THE INVENTION
[0002] A molecular sieve is generally a microporous structure composed
of either crystalline aluminosilicate, belonging to a class of materials
known as zeolites, or crystalline aluminophosphates, or crystalline
silicoaluminophosphates. Molecular sieves can be made by hydrothermal
crystallization from a reaction mixture comprising reactive sources
of silicon and/or aluminum and/or phosphorous containing compounds,
usually in the presence of one or several organic amine or quaternary
ammonium salt as structure directing agent, also known as template.
[0003] Molecular sieve catalysts are compositions made of molecular
sieve particles bound together to form particles larger than the
molecular sieve components. The molecular sieve catalyst particles
can also include other components such as binders, fillers, like
clay, and optionally other catalytically active agents such as rare
earth metal oxides, transition metal oxides, or noble metal components.
[0004] Conventional methods of making molecular sieve catalyst
particles include mixing together molecular sieve and binder, as
well as other optional components such as fillers and other catalytic
components. The mixture is typically stirred in solution to form
a slurry, and the slurry is dried to form molecular sieve catalyst
particles. Following drying, the particles are calcined to harden,
as well as activate, the catalyst particles.
[0005] For example, WO 99/21651 describes a method for making molecular
sieve catalyst. The method includes the steps of mixing together
a molecular sieve and an alumina sol, the alumina sol being made
in solution and maintained at a pH of 2 to 10. The mixture is then
spray dried and calcined. The calcined product is reported to be
relatively hard, i.e., attrition resistant.
[0006] U.S. Pat. No. 6153552 describes another method for making
molecular sieve catalyst. The catalyst is made by mixing together
a silicon containing oxide sol as a binder material and a molecular
sieve material. The pH of the mixture is adjusted prior to spray
drying. Following spray drying, the catalyst material is calcined
to form a finished catalyst product, which is reported to be relatively
hard, i.e., attrition resistant.
[0007] During the manufacture of molecular sieve catalyst, catalyst
particles can be made which have undesirable properties such as
undesirable attrition resistance properties or undesirable particle
size properties. Rather than discarding such catalyst particles,
it would be beneficial to find a method that allows for the catalyst
particles to be remanufactured or recycled so as to provide properties
which are acceptable to the user or manufacturer.
SUMMARY OF THE INVENTION
[0008] This invention provides a method for making molecular sieve
catalyst particles from catalyst particles which have certain undesirable
properties. In essence, this invention provides for the remanufacturing
or recycling or re-working of molecular sieve catalyst to provide
properties which are acceptable to the user or manufacturer.
[0009] In one embodiment, there is provided a method of making
molecular sieve catalyst particles, comprising
[0010] a) providing a first dried molecular sieve catalyst;
[0011] b) combining the first dried molecular sieve catalyst with
water to form a water-catalyst composition;
[0012] c) mixing the water-catalyst composition to form a slurry;
and
[0013] d) drying the slurry to form particles of a second dried
molecular sieve catalyst.
[0014] In another embodiment, there is provided a method of recycling
molecular sieve catalyst particles having undesired properties,
comprising
[0015] (i) mixing a composition comprising molecular sieve, binder
and water;
[0016] (ii) drying the composition to form a first dried molecular
sieve catalyst;
[0017] (iii) combining at least a portion of the first dried molecular
sieve catalyst with water to form a water-catalyst composition;
[0018] (iv) mixing the water-catalyst composition to form a slurry;
[0019] (v) drying the slurry to form particles of a second dried
molecular sieve catalyst.
[0020] In yet another embodiment, there is provided a method of
making a molecular sieve catalyst composition, comprising: providing
first dried molecular sieve catalyst particles, wherein the first
dried molecular sieve catalyst particles yield, upon calcining,
a calcined molecular sieve composition having greater than 5 wt
% catalyst particles having an average particle diameter greater
than or equal to 250 microns; combining the dried molecular sieve
catalyst particles with water to form a slurry; and drying the slurry
to form the molecular sieve catalyst composition.
[0021] In all embodiments of the invention, it is preferred that
the water combined with the first dried molecular sieve catalyst
comprises at least 95 wt % water and/or is substantially free of
any molecular sieve particle. Preferably, the water is at a substantially
neutral pH prior to combining with the dried molecular sieve catalyst
particles.
[0022] The first dried molecular sieve catalyst may be uncalcined
and may thus contain template material. Preferably, the template
material is selected from the group consisting of triethylamine,
cyclohexylamine, piperidine, dipropylamine, pyridine, isopropylamine,
tetraethyl ammonium salts, and mixtures thereof.
[0023] It is preferred that the first dried molecular sieve catalyst
and water be mixed so to break apart the particles of the first
dried molecular sieve catalyst.
[0024] A slurry is formed, preferably having a viscosity of from
100 cP to 9000 cP measured using a Brookfield LV-DVE viscometer
with a No. 3 spindle at 10 rpm, and a solids content of from 10
wt % to 75 wt %.
[0025] The slurry is then dried to form particles of a second dried
molecular sieve catalyst. Preferably drying is by spray drying.
[0026] The particles of the second dried molecular sieve catalyst
may be submitted to calcination. Preferably, the molecular sieve
catalyst particles obtained in e) have an EMARI of not greater than
1 wt %/hr, preferably not greater than 0.7 wt %/hr, most preferably
not greater than 0.3 wt %/hr, and/or have a particle size such that
50% of the particles have a diameter larger than 30 .mu.m and smaller
than 150 .mu.m.
[0027] The first dried molecular sieve catalyst preferably comprises
a silicoaluminophosphate molecular sieve, more preferably selected
from the group consisting of SAPO-18 SAPO-34 SAPO-35 SAPO-44
SAPO-56 ALPO-18 and ALPO-34 metal containing molecular sieves
thereof, and mixtures thereof, even more preferably selected from
the group consisting of SAPO-18 SAPO-34 ALPO-34 and ALPO-18 metal
containing molecular sieves thereof, and mixtures thereof. In another
embodiment, the first dried molecular sieve catalyst is selected
from the group consisting of silicoaluminphosphate molecular sieves
having CHA, AEI or a combination of CHA and AEI framework type.
[0028] The first dried molecular sieve catalyst may also comprise
a binder selected from the group consisting of hydrated alumina,
silicas, and/or other inorganic oxide sol and/or a filler selected
from the group consisting of clays, clay-type compositions and mixtures
thereof.
[0029] The present invention also relates to a calcined molecular
sieve catalyst composition comprising catalyst particles, wherein
the catalyst particles, after being submitted to calcination, have
an EMARI of equal or less than 0.7 wt %/hr, preferably less than
0.3 wt %/hr.
[0030] The molecular sieve catalysts prepared by the method of
the present invention are useful catalysts for the conversion of
feedstocks comprising at least one oxygenate into olefins.
DETAILED DESCRIPTION OF THE INVENTION
[0031] This invention provides a method for making molecular sieve
catalyst particles. The method is accomplished by combining a first
dried molecular sieve catalyst with water to make a water-catalyst
composition, making a slurry from the water-catalyst composition,
and drying the slurry to produce a second dried molecular sieve
catalyst. The method particularly provides for the re-manufacturing,
recycling or re-working of dried or substantially dried, or partially
dried molecular sieve catalysts to yield catalyst particles with
properties that are acceptable to the user or manufacturer. Such
properties are usually observed after the dried molecular sieve
catalyst is calcined. These properties include acceptable particle
size, particle size distribution, particle density, and particle
hardness.
[0032] According to the invention, the first dried molecular sieve
catalyst is combined with water to form a water-catalyst composition.
The water with which the first dried molecular sieve is combined
is essentially pure water, that is, water comprising at least 95
wt % water, preferably at least 97 wt % water, more preferably at
least 98 wt % water. The water may optionally contain less than
5 wt %, preferably less than 3 wt %, and more preferably less than
2 wt %, other compounds. Non-limiting examples of such compounds
include alcohols, aldehydes, esters, ethers, salts, soluble carbonates,
oxides, hydroxides, acids, bases, water soluble polymers. Preferably,
though, the water should contain as little as possible of such additional
components. In any event, water with which the first dried molecular
sieve composition is combind is essentially free of any molecular
sieve particle, i.e. the water contains less than 1 wt % molecular
sieve.
[0033] In combining the first dried molecular sieve catalysts with
water, the order of addition is not critical. The first dried molecular
sieve catalyst may be added to water, water may be added to the
first dried molecular sieve catalyst or water and the first dried
molecualr sieve catalyst may be combined simulaneously.
[0034] The water-catalyst composition contains particles of the
first dried molecular sieve catalyst and water. Optionally, other
components may be added to the water-catalyst composition. However,
the water-catalyst composition contains no other molecular sieve
than that originally present in the first dried molecular sieve
catalyst. The process of the present invention thus differs from
other catalyst recycling processes in which the recycled molecular
sieve catalyst particles are mixed with a slurry containing additional
molecular sieve. In such processes, the water-catalyst composition
formed during the recycling process contains additional molecular
sieve, i.e. molecular sieve that was not originally present in the
recycled catalyst particles.
[0035] The first dried molecular sieve catalyst is made of catalyst
particles which contain molecular sieve particles bound together
to form catalyst particles larger than the individual molecular
sieve particles. The molecular sieve catalyst particles can also
include other components such as fillers, like clay, and other catalytically
active agents, for example, metal compounds.
[0036] The first dried molecular sieve catalyst has properties
that make it unsuitable for its intended use. The present invention
provides a method allowing to recycle, or re-work such undesired
molecular sieve catalyst to produce new molecular sieve catalyst
having the desired properties.
[0037] For purposes of this invention, dried means that the mixture
used to form the molecular sieve catalyst has been submitted to
heat in a drying or forming unit but has not been calcined. Dried
also means that at least a portion of the liquid used during the
manufacture, also referred to as formulation, of the catalyst has
been removed. The method of the invention can be used with molecular
sieve catalyst compositions from which the liquid used for manufacture
has been partially, substantially or totally removed.
[0038] After such drying, the molecular sieve may still contain
structure directing molecules (templates) used during the preparation
of the molecular sieve. As used in the present description, drying
does not include calcination. Calcination is essentially a combustion
process that takes place at a higher temperature than that of a
drying process. The calcination process takes place preferably in
the presence of an oxygen-containing gas at a temperature from about
200.degree. C. to about 900.degree. C., preferably from about 250.degree.
C. to about 850.degree. C., and more preferably from about 300.degree.
C. to about 800.degree. C.
[0039] In order to determine whether a dried molecular sieve catalyst
has acceptable or unacceptable properties, it is usually necessary
to calcine a portion of the molecular sieve catalyst to determine
one or more properties. If the portion of calcined catalyst demonstrates
one or more undesirable properties, the dried, but uncalcined, remaining
portion of the catalyst is combined with water to form a water-catalyst
composition. The water-catalyst composition is mixed to from a slurry.
The slurry is then dried to form the so-called second catalyst particles.
A sample of this material can then be calcined and re-tested for
the desired properties. If the desired properties are achieved,
then the remainder of the second dried catalyst may be calcined,
if desired. If one or more properties are still not achieved, the
process steps are repeated until satisfactory testing results are
achieved, and the remainder of dried catalyst can then be calcined,
if desired. The invention is thus extremely useful to monitor and
optimize catalyst manufacturing processes.
[0040] In an embodiment of the invention, the first dried molecular
sieve catalyst contains template material. Template materials, often
also called structure directing agents, are chemical compounds which
are used to make the crystalline molecular sieves. During the formation
of the molecular sieves, a crystalline structure is formed which
essentially wraps around the template material.
[0041] The template may still be present in the first dried catalyst
composition. It will eventually be removed from the second dried
catalyst composition to form a final catalyst composition product.
The template is typically removed by calcination or other chemical
process such as an elution type process, which leaves behind a vast
pore system within the crystalline structure. The pore system is
generally referred to as an intracrystalline pore system.
[0042] Representative templates which can be included in the first
dried catalyst particles include tetraethyl ammonium salts, cyclopentylamine,
aminomethyl cyclohexane, piperidine, triethylamine, cyclohexylamine,
tri-ethyl hydroxyethylamine, morpholine, dipropylamine (DPA), pyridine,
isopropylamine and combinations thereof. Preferred templates are
triethylamine, cyclohexylamine, piperidine, pyridine, isopropylamine,
tetraethyl ammonium salts, dipropylamine, and mixtures thereof.
The tetraethylammonium salts include tetraethyl ammonium hydroxide
(TEAOH), tetraethyl ammonium phosphate, tetraethyl ammonium fluoride,
tetraethyl ammonium bromide, tetraethyl ammonium chloride, tetraethyl
ammonium acetate.
[0043] The first dried molecular sieve catalyst used to make the
catalysts of this invention can include any of a variety of molecular
sieve components. The components include zeolites or non-zeolites,
preferably non-zeolites. In one embodiment, the molecular sieves
are small pore non-zeolite molecular sieves having an average pore
size of less than about 5 angstroms, preferably an average pore
size ranging from about 3 to 5 angstroms, more preferably from 3.5
to 4.2 angstroms. These pore sizes are typical of molecular sieves
having 8 membered rings.
[0044] Conventional crystalline aluminosilicate zeolites having
catalytic activity are desirable molecular sieves that can be used
in making the catalyst of this invention. Examples of such zeolite
materials are described in U.S. Pat. Nos. 3660274 and 3944482
both of which are incorporated herein by reference. Non-limiting
examples of zeolites which can be employed in the practice of this
invention, include both natural and synthetic zeolites. These zeolites
include zeolites of the structural types included in the "Atlas
of Zeolite Framework Types" edited by Ch. Baerlocher, W. M.
Meier, D. H. Olson, Fifth Revised edition, Elsevier, Amsterdam,
2001 he descriptions of which are incorporated herein by reference.
[0045] Zeolites typically have silica-to-alumina (SiO.sub.2/Al.sub.2O.sub.-
3) mole ratios of at least about 2 and have uniform pore diameters
from about 3 to 15 Angstroms. They also generally contain alkali
metal cations, such as sodium and/or potassium and/or alkaline earth
metal cations, such as magnesium and/or calcium. In order to increase
the catalytic activity of the zeolite, it may be desirable to decrease
the alkali metal content of the crystalline zeolite to less than
about 5 wt. %, preferably less than about 1 wt. %, and more preferably
less than about 0.5 wt. %. The alkali metal content reduction, as
is known in the art, may be conducted by exchange with one or more
cations selected from the Groups IIB through VIII of the Periodic
Table of Elements (the Periodic Table of Elements referred to herein
is given in Handbook of Chemistry and Physics, published by the
Chemical Rubber Publishing Company, Cleveland, Ohio, 45th Edition,
1964 or 73rd Edition, 1992), as well as with hydronium ions or basic
adducts of hydronium ions, e.g., NH.sub.4.sup.+, capable of conversion
to a hydrogen cation upon calcination. Desired cations include rare
earth cations, calcium, magnesium, hydrogen and mixtures thereof.
Ion-exchange methods are well known in the art and are described,
for example, in U.S. Pat. No. 3140249; U.S. Pat. No. 3142251
and U.S. Pat. No. 1423353 the teachings of which are hereby incorporated
by reference.
[0046] Examples of zeolites suitable for use in this invention
include large pore zeolites, medium pore zeolites, and small pore
zeolites. A large pore zeolite generally has a pore size of >7
.ANG. and includes zeolite types such as MAZ, MEI, FAU, EMT. Examples
of large pore zeolites include zeolite L, zeolite Y, zeolite X,
offretite, omega, Beta, mordenite, ZSM-3 ZSM-4 ZSM-18 and ZSM-20.
A medium pore size catalyst generally has a pore size <7 .ANG.,
preferably from about 5 .ANG. to about 6.8 .ANG.; and generally
the pore apertures consist of about 10 to 12 preferably about 10
membered ring structures and include MFI, MEL, MTW, EUO, MTT, HEU,
FER, and TON. Examples of medium pore zeolite include ZSM-34 ZSM-38
and ZSM-48. A small pore size zeolite has a pore size from about
3 .ANG. to about 5.0 .ANG.. Generally, the pore apertures of the
structure consist of from about 8 to 10 preferably about 8 membered
ring structures and include CHA, ERI, KFI, LEV, and LTA. Examples
of small pore zeolite include ZK-4 ZK-5 zeolite A, zeolite T,
gmelinite, chinoptilolite, chabasite and erionite. The zeolites
can also comprise gallosilicates and titanosilicates.
[0047] Non-zeolite molecular sieves can also be included in the
first dried molecular sieve catalyst particles used to make the
catalysts of this invention. Preferred non-zeolite molecular sieves
include metalloaluminophosphate molecular sieves.
[0048] The metalloaluminophosphate molecular sieve may be represented
by the empirical formula, on an anhydrous basis:
mR:(M.sub.xAl.sub.yP.sub.z)O.sub.2
[0049] wherein R represents at least one templating agent, preferably
an organic templating agent; m is the number of moles of R per mole
of (M.sub.xAl.sub.yP.sub.z)O.sub.2 and m has a value from 0 to 1
preferably 0 to 0.5 and most preferably from 0 to 0.3; x, y, and
z represent the mole fraction of Al, P and M as tetrahedral oxides,
where M is a metal selected from one of Group IA, IIA, IB, IIIB,
IVB, VB, VIB, VIIB, VIIIB and Lanthanide's of the Periodic Table
of Elements, preferably M is selected from one of the group consisting
of Si, Ge, Co, Cr, Cu, Fe, Ga, Ge, Mg, Mn, Ni, Sn, Ti, Zn, Zr and
mixtures thereof. 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.
[0050] Examples of metalloaluminophosphate molecular sieves which
may be present in the first dried molecular sieve catalysts 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.
[0051] Other metalloaluminophosphate molecular sieves include those
described in EP-0 888 187 B1 (microporous crystalline metallophosphates,
SAPO.sub.4 (UIO-6)), U.S. Pat. No. 6004898 (molecular sieve and
an alkaline earth metal), U.S. patent application Ser. No. 09/511943
filed Feb. 24 2000 (integrated hydrocarbon co-catalyst), PCT WO
01/64340 published Sep. 7 2001(thorium containing molecular sieve),
and R. Szostak, Handbook of Molecular Sieves, Van Nostrand Reinhold,
New York, N.Y. (1992), which are all herein fully incorporated by
reference.
[0052] Most preferably, the molecular sieves present in the first
dried molecular sieve catalyst are silicoaluminophosphate (SAPO)
molecular sieves, aluminophosphate molecular sieves and metal substituted
forms thereof.
[0053] Non-limiting examples of SAPO and ALPO molecular sieves
that may be present in the first dried molecular sieve catalyst
of the invention include one or a combination of SAPO-5 SAPO-8
SAPO-11 SAPO-16 SAPO-17 SAPO-18 SAPO-20 SAPO-31 SAPO-34 SAPO-35
SAPO-36 SAPO-37 SAPO-40 SAPO-41 SAPO-42 SAPO-44 (U.S. Pat.
No. 6162415), SAPO-47 SAPO-56 ALPO-5 ALPO-11 ALPO-18 ALPO-31
ALPO-34 ALPO-36 ALPO-37 ALPO-46 and metal containing molecular
sieves thereof. The more preferred molecular sieves include one
or a combination of SAPO-18 SAPO-34 SAPO-35 SAPO-44 SAPO-56
ALPO-18 and ALPO-34 even more preferably one or a combination of
SAPO-18 SAPO-34 ALPO-34 and ALPO-18 and metal containing molecular
sieves thereof, and most preferably one or a combination of SAPO-34
and ALPO-18 and metal containing molecular sieves thereof.
[0054] As used herein, the term mixture is synonymous with combination
and is considered a composition of matter having two or more components
in varying proportions, regardless of their physical state. In particular,
it encompasses physical mixtures as well as intergrowths of at least
two different molecular sieve structures, such as for example those
described in PCT Publication No. WO 98/15496. In an embodiment,
the molecular sieve is an intergrowth material having two or more
distinct phases of crystalline structures within one molecular sieve
composition. In another embodiment, the molecular sieve comprises
at least one intergrown phase of AEI and CHA framework-types. For
example, SAPO-18 ALPO-18 and RUW-18 have an AEI framework-type,
and SAPO-34 has a CHA framework-type. In a further embodiment the
molecular sieve comprises a mixture of intergrown material and non-intergrown
material.
[0055] The first dried molecular sieve catalyst compositions may
also contain binder. Non-limiting examples of binders that may be
present alone or in combination include various types of hydrated
aluminas, silicas, and/or other inorganic oxide sols. One preferred
alumina containing sol is aluminium chlorohydrate. The inorganic
oxide sol acts like glue binding the molecular sieve and other materials
that may also be present in the catalyst composition such as a matrix
or filler together, particularly after thermal treatment. Upon heating,
the inorganic oxide sol, is converted into an inorganic oxide matrix
component. For example, an alumina sol will convert to an aluminium
oxide matrix following heat treatment.
[0056] Aluminium chlorohydrate, a hydroxylated aluminium based
sol containing a chloride counter ion also known as aluminium chlorohydrol,
has the general formula 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 Elsevier, Amsterdam, 1993
which is herein incorporated by reference. In another embodiment,
one or more binders are present in combination with one or more
other non-limiting examples of alumina materials such as aluminium
oxyhydroxide, .gamma.-alumina, boehmite and transitional aluminas
such as .alpha.-alumina, .beta.-alumina, .gamma.-alumina, .delta.-alumina,
.epsilon.-alumina, .kappa.-alumina, and .rho.-alumina, aluminium
trihydroxide, such as gibbsite, bayerite, nordstrandite, doyelite,
and mixtures thereof.
[0057] In another embodiment, the binders are alumina sols, predominantly
comprising aluminium oxide, optionally including some silicon. In
yet another embodiment, the binders are peptised alumina made by
treating alumina hydrates such as pseudobohemite, with an acid,
preferably an acid that does not contain a halogen, to prepare sols
or aluminium ion solutions. Non-limiting examples of commercially
available colloidal alumina sols include Nalco 8676 available from
Nalco Chemical Co., Naperville, Ill., and Nyacol available from
the Nyacol Nano Technology Inc., Boston, Mass.
[0058] The first dried molecular sieve may also comprise one or
more matrix or filler material(s). Matrix materials are typically
effective in reducing overall catalyst cost, act as thermal sinks
assisting in shielding heat from the catalyst composition for example
during regeneration, densifying the catalyst composition, increasing
catalyst strength such as crush strength and attrition resistance,
and to control the rate of conversion in a particular process.
[0059] Non-limiting examples of matrix materials include one or
more of: rare earth metals, metal oxides including titania, zirconia,
magnesia, thoria, beryllia, quartz, silica or sols, and mixtures
thereof, for example silica-magnesia, silica-zirconia, silica-titania,
silica-alumina and silica-alumina-thoria. In an embodiment, matrix
materials are natural clays such as those from the families of montmorillonite
and kaolin. These natural clays include kaolins known as, for example,
Dixie, McNamee, Georgia and Florida clays. Non-limiting examples
of other matrix materials include: halloysite, kaolinite, dickite,
nacrite, or anauxite. In one embodiment, the matrix material, preferably
any of the clays, are subjected to well known modification processes
such as calcination and/or acid treatment and/or chemical treatment
before being used in catalyst formulation processes.
[0060] In one preferred embodiment, the matrix material is a clay
or a clay-type composition, preferably 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
solid content slurry; it has a low fresh surface area, and it packs
together easily due to its platelet structure. A preferred average
particle size of the matrix material, most preferably kaolin, is
from about 0.1 .mu.m to about 0.6 .mu.m with a d.sub.90 particle
size distribution of less than about 1 .mu.m.
[0061] The first dried molecular sieve catalyst composition is
typically prepared by mixing the molecular sieve, the binder and
the matrix materials in the presence of a liquid to form a slurry,
and drying the slurry to form first dried molecular sieve catalyst
particles.
[0062] The amount of binder used to prepare the first dried molecular
sieve catalyst typically ranges from about 2% by weight to about
30% by weight, preferably from about 5% by weight to about 20% by
weight, and more preferably from about 7% by weight to about 15%
by weight, based on the total weight of the binder, the molecular
sieve and matrix material, excluding the liquid (after calcination).
[0063] In another embodiment, the weight ratio of the binder to
the matrix material used in the formation of the first dried molecular
sieve catalyst composition is from 0:1 to 1:1 preferably 1:15 to
1:2 more preferably 1:10 to 1:2 and most preferably 1:6 to 1:1.
[0064] The liquid used to form the first dried molecular sieve
catalyst can be any liquid known in the art of formulating catalysts.
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.
[0065] The molecular sieve and matrix material, and the optional
binder, used in making the first dried catalyst composition may
be combined in the same or different liquid, and may be combined
in any order, together, simultaneously, sequentially, or a combination
thereof. In the preferred embodiment, the same liquid, preferably
water, is used.
[0066] In one embodiment, the slurry of the molecular sieve, binder
and matrix materials used to make the first dried catalyst composition
is mixed or milled to achieve a uniform slurry of sub-particles
of the molecular sieve catalyst composition; the slurry is then
fed to a forming unit that produces the first dried molecular sieve
catalyst composition. The forming unit may be any known unit, such
as spray dryers, pelletizers, extruders, etc. 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.
[0067] When a spray dryer is used as the forming (or drying) unit,
typically, the slurry of the molecular sieve 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 150.degree.
C. to 550.degree. C., and a combined outlet temperature ranging
from 100.degree. C. to about 250.degree. C.
[0068] During spray drying, the slurry is passed through a nozzle
distributing the slurry into small droplets, resembling an aerosol
spray into a drying chamber. Atomization is achieved by forcing
the slurry through a single nozzle or multiple nozzles with a pressure
drop in the range of from 100 psia to 1000 psia (690 kpaa to 6895
kpaa). In another embodiment, the slurry is co-fed through a single
nozzle or multiple nozzles along with an atomisation fluid such
as air, steam, flue gas, or any other suitable gas.
[0069] In yet another embodiment, the slurry described above is
directed to the perimeter of a spinning wheel that distributes the
slurry into small droplets, the size of which is controlled by many
factors including slurry viscosity, surface tension, flow rate,
pressure, and temperature of the slurry, the shape and dimension
of the nozzle(s), or the spinning rate of the wheel. These droplets
are then dried in a co-current or counter-current flow of air passing
through a spray drier to form a partially, substantially or totally
dried molecular sieve catalyst composition.
[0070] An example of spray drying process that may be used to prepare
the first dried molecular sieve catalyst composition is disclosed
in U.S. Pat. No. 4946814 the description of which is incorporated
herein.
[0071] In addition, the first dried molecular sieve catalyst composition
used in the method of the present invention may comprise one or
several other catalytically active materials, besides the molecular
sieve(s). As a result, these other catalytically active materials
are incorporated as a part of the first dried catalyst composition.
[0072] According to the present invention, the first dried molecular
sieve catalyst is combined with water to form a water-catalyst composition,
which is mixed to form a slurry. Preferably, the mixing is sufficient
to break the larger particles added to the solution. In general,
the more vigorous the mixing, the smaller the particles formed in
the slurry. Mixing using high-shear mixers is preferred. In general,
these are mixers which are capable of rotating at speeds of at least
about 3000 rpms laboratory scale equivalent.
[0073] The particle size of the slurry can be indirectly assessed
by measuring the viscosity of the slurry. In general, the higher
the viscosity, the smaller the particle size in the slurry. The
viscosity of the slurry should not be too high so that mixing is
not effective in breaking apart large particles or too low so that
drying will not produce acceptable particle formation. In one embodiment
of the invention, the slurry has a viscosity of from about 100 cP
(0.1 Pa/sec) to about 9500 cP (9.5 Pa/sec), as measured using a
Brookfield LV-DVE viscometer with a No. 3 spindle at 10 rpm. Preferably
the slurry has a viscosity of from about 200 cP (0.2 Pa/sec) to
about 8500 cP (8.5 Pa/sec), and more preferably from about 350
cP (0.375 Pa/sec) to about 8000 cP (8 Pa/sec), as measured using
a Brookfield LV-DVE viscometer with a No. 3 spindle at 10 rpm.
[0074] In another embodiment the slurry has a solids content of
from about 10 wt % to about 75 wt %. Preferably the slurry has a
solids content of from about 15 wt % to about 70 wt %, more preferably
from about 20 wt % to about 65 wt %, based on the total weight of
the slurry. The solids content can be measured using any conventional
means. However, a CEM MAS 700 microwave muffle furnace is particularly
preferred to give results consistent with the values recited herein.
[0075] If desired, the pH of the slurry can be adjusted before
or during the mixing step.
[0076] The slurry can be dried using any conventional drying method
to form a second dried molecular sieve catalyst composition. All
the methods described earlier in this document to prepare the first
dried molecular sieve catalyst composition are equally suitable
to produce the second dried molecular sieve catalyst composition.
[0077] In one embodiment, the second dried molecular sieve catalyst
composition is calcined. Calcination further hardens and/or activates
the second dried molecular sieve catalyst composition. A conventional
calcination environment is air that typically includes a small amount
of water vapour. Typical calcination temperatures are in the range
from about 400.degree. C. to about 1000.degree. C., preferably
from about 500.degree. C. to about 800.degree. C., and most preferably
from about 550.degree. C. to about 700.degree. C., preferably in
a calcination environment such as air, nitrogen, helium, flue gas
(combustion product lean in oxygen), or any combination thereof.
[0078] In one embodiment, calcination of the formulated molecular
sieve catalyst composition is carried out in any number of well
known devices including rotary calciners, fluid bed calciners, batch
ovens, and the like. Calcination time is typically dependent on
the degree of hardening of the molecular sieve catalyst composition
and the temperature.
[0079] In a preferred embodiment, the molecular sieve catalyst
composition is heated in nitrogen at a temperature of from about
600.degree. C. to about 700C. Heating is carried out for a period
of time typically from 30 minutes to 15 hours, preferably from 1
hour to about 10 hours, more preferably from about 1 hour to about
5 hours, and most preferably from about 2 hours to about 4 hours.
[0080] Other methods for activating a molecular sieve catalyst
composition are described in, for example, U.S. Pat. No. 5185310
(heating molecular sieve of gel alumina and water to 450 C), PCT
WO 00/75072 published Dec. 14 2000 (heating to leave an amount
of template), which are all herein fully incorporated by reference
[0081] The process of the present invention provides methods to
produce molecular sieve catalyst compositions containing particles
with properties that make them suitable for catalytic use. They
can be used, for example, to dry gases and liquids; for selective
molecular separation based on size and polar properties; as an ion-exchanger;
as a catalyst in hydrocarbon cracking, hydrocracking, disproportionation,
alkylation, isomerization, oxidation, and conversion of oxygenates
to hydrocarbons; as a chemical carrier; in gas chromatography; and
in the petroleum industry to remove normal paraffins from distillates.
The catalysts are particularly suited for use as catalysts in cracking,
hydrocracking, disproportionation, alkylation, isomerization, oxidation,
and conversion of oxygenates to hydrocarbons. More particularly,
the molecular sieve catalysts of this invention are suited for use
as a catalyst in the conversion of oxygenates to hydrocarbons.
[0082] In its most desired embodiment, the molecular sieve catalyst
compositions made by the method of the invention can be used as
a catalyst in the conversion of oxygenates to hydrocarbons. Hence,
the present invention also encompasses a method for producing light
olefins by contacting a feedstock comprising at least one oxygenate
with a dried or calcined molecular sieve composition prepared by
the method of the present invention.
[0083] In this embodiment, a feed containing an oxygenate is contacted
in a reaction zone of a reactor apparatus with the molecular sieve
catalyst composition at process conditions effective to produce
light olefins, i.e., an effective temperature, pressure, WHSV (weight
hour space velocity) and, optionally, an effective amount of diluent,
correlated to produce light olefins. These conditions are described
in detail below. Usually, the oxygenate feed is contacted with the
catalyst when the oxygenate is in a vapor phase. Alternately, the
process may be carried out in a liquid or a mixed vapor/liquid phase.
When the process is carried out in a liquid phase or a mixed vapor/liquid
phase, different conversions and selectivities of feed-to-product
may result depending upon the catalyst and reaction conditions.
As used herein, the term reactor includes not only commercial scale
reactors but also pilot sized reactor units and lab bench scale
reactor units.
[0084] Olefins can generally be produced at a wide range of temperatures.
An effective operating temperature range can be from about 200.degree.
C. to 700.degree. C. At the lower end of the temperature range,
the formation of the desired olefin products may become markedly
slow. At the upper end of the temperature range, the process may
not form an optimum amount of product. An operating temperature
of between about 300.degree. C. and 500.degree. C. is desired.
[0085] The process can be carried out in a dynamic bed system or
any system of a variety of transport beds rather than in a fixed
bed system. It is particularly desirable to operate the reaction
process at high space velocities and in a fluidized bed system.
[0086] The conversion of oxygenates to produce light olefins may
be carried out in a variety of large scale catalytic reactors, including,
but not limited to, fluid bed reactors and concurrent riser reactors
as described in Fluidization Engineering, D. Kunii and O. Levenspiel,
Robert E. Krieger Publishing Co. New York, 1977 incorporated in
its entirety herein by reference. Additionally, countercurrent free
fall reactors may be used in the conversion process. See, for example,
U.S. Pat. No. 4068136 and Fluidization and Fluid-Particle Systems,
pages 48-59 F. A. Zenz and D. F. Othmo, Reinhold Publishing Corp.,
New York, 1960 the descriptions of which are expressly incorporated
herein by reference.
[0087] Any standard commercial scale reactor system can be used,
including fixed bed or moving bed systems. The commercial scale
reactor systems can be operated at a weight hourly space velocity
(WHSV) of from 1 hr.sup.-1 to 1000 hr.sup.-1. In the case of commercial
scale reactors, WHSV is defined as the weight of hydrocarbon in
the feed per hour per weight of molecular sieve content of the catalyst.
The hydrocarbon content will be oxygenate and any hydrocarbon which
may optionally be combined with the oxygenate. The molecular sieve
content is intended to mean only the molecular sieve portion that
is contained within the catalyst. This excludes components such
as binders, diluents, inerts, rare earth components, etc.
[0088] The pressure also may vary over a wide range, including
autogenous pressures. Desired pressures are in the range of about
0.5 kPa to about 5 MPa. The foregoing pressures refer to the partial
pressure of the oxygenate compounds and/or mixtures thereof.
[0089] One or more inert diluents may be present in the feedstock,
for example, in an amount of from 1 molar percent to 99 molar percent,
based on the total number of moles of all feed and diluent components
fed to the reaction zone (or catalyst). Typical diluents include,
but are not necessarily limited to helium, argon, nitrogen, carbon
monoxide, carbon dioxide, hydrogen, water, paraffins, alkanes (especially
methane, ethane, and propane), alkylenes, aromatic compounds, and
mixtures thereof. The desired diluents are water and nitrogen. Water
can be injected in either liquid or vapor form.
[0090] The process may be carried out in a batch, semi-continuous
or continuous fashion. The process can be conducted in a single
reaction zone or a number of reaction zones arranged in series or
in parallel.
[0091] The level of conversion of the oxygenates can be maintained
to reduce the level of unwanted by-products. Conversion can also
be maintained sufficiently high to avoid the need for commercially
undesirable levels of recycling of unreacted feeds. A reduction
in unwanted by-products is seen when conversion moves from 100 mol
% to about 98 mol % or less. Recycling up to as much as about 50
mol % of the feed is commercially acceptable. Therefore, conversions
levels which achieve both goals are from about 50 mol % to about
98 mol % and, desirably, from about 85 mol % to about 98 mol %.
However, it is also acceptable to achieve conversion between 98
mol % and 100 mol % in order to simplify the recycling process.
Oxygenate conversion may be maintained at this level using a number
of methods familiar to persons of ordinary skill in the art. Examples
include, but are not necessarily limited to, adjusting one or more
of the following: the reaction temperature; pressure; flow rate
(i.e., WHSV); level and degree of catalyst regeneration; amount
of catalyst re-circulation; the specific reactor configuration;
the feed composition; and other parameters which affect the conversion.
[0092] If regeneration is required, the molecular sieve catalyst
can be continuously introduced as a moving bed to a regeneration
zone where it can be regenerated, such as for example by removing
carbonaceous materials or by oxidation in an oxygen-containing atmosphere.
In a desired embodiment, the catalyst is subject to a regeneration
step by burning off carbonaceous deposits accumulated during the
conversion reactions.
[0093] The oxygenate feedstock comprises at least one organic compound
which contains at least one oxygen atom, such as aliphatic alcohols,
ethers, carbonyl compounds (aldehydes, ketones, carboxylic acids,
carbonates, esters and the like). When the oxygenate is an alcohol,
the alcohol can include an aliphatic moiety having from 1 to 10
carbon atoms, more preferably from 1 to 4 carbon atoms. Representative
alcohols include but are not necessarily limited to lower straight
and branched chain aliphatic alcohols and their unsaturated counterparts.
Examples of suitable oxygenate compounds include, but are not limited
to: methanol; ethanol; n-propanol; isopropanol; C.sub.4-C.sub.20
alcohols; methyl ethyl ether; dimethyl ether; diethyl ether; di-isopropyl
ether; formaldehyde; dimethyl carbonate; dimethyl ketone; acetic
acid; and mixtures thereof. Desired oxygenate compounds are methanol,
dimethyl ether, or a mixture thereof.
[0094] The method of making the desired olefin product in this
invention can include the additional step of making these oxygenates
from hydrocarbons such as oil, coal, tar sand, shale, biomass and
natural gas. Methods for making the compositions are known in the
art. These methods include fermentation to alcohol or ether, making
synthesis gas, then converting the synthesis gas to alcohol or ether.
Synthesis gas can be produced by known processes such as steam reforming,
autothermal reforming and partial oxidization.
[0095] The olefins produced using the catalysts of this invention
can be polymerized to form polyolefins, particularly polyethylene
and polypropylene. Conventional processes for forming polyolefins
from olefins can be used. Catalytic processes are desired. Particularly
desired are metallocene, Ziegler/Natta and acid catalytic systems.
See, for example, U.S. Pat. Nos. 3258455; 3305538; 3364190;
5892079; 4659685; 4076698; 3645992; 4302565; and 4243691
the catalyst and process descriptions of each being expressly incorporated
herein by reference. In general, these methods involve contacting
the olefin product with a polyolefin-forming catalyst at a pressure
and temperature effective to form the polyolefin product.
[0096] A desired polyolefin-forming catalyst is a metallocene catalyst.
The desired temperature of operation is from 50.degree. C. to 240.degree.
C. and the reaction can be carried out at low, medium or high pressure,
being anywhere from about 1 bar to 200 bars. For processes carried
out in solution, an inert diluent can be used, and the desired operating
pressure is from 10 bars to 150 bars, with a desired temperature
range of from 120.degree. C. to 230.degree. C. For gas phase processes,
it is desired that the temperature generally from 60.degree. C.
to 160.degree. C., and that the operating pressure from 5 bars to
50 bars.
[0097] In addition to polyolefins, numerous other olefin derivatives
may be formed from the olefins produced by the catalysts of this
invention. These include, but are not limited to, aldehydes, alcohols,
acetic acid, linear alpha olefins, vinyl acetate, ethylene dichloride
and vinyl chloride, ethylbenzene, ethylene oxide, cumene, isopropyl
alcohol, acrolein, allyl chloride, propylene oxide, acrylic acid,
ethylene-propylene rubbers, and acrylonitrile, and trimers and dimers
of ethylene, propylene or butylenes.
[0098] In the catalytic processes using the molecular sieve catalyst
compositions produced according to the present invention, catalyst
particles must meet certain particle requirements, including particle
size, particle size distribution, particle density, and particle
hardness. Examples of molecular sieve catalyst particle properties
that have proved useful in catalytic processes include the following
non-limiting examples.
[0099] After calcination, the particles of the second dried molecular
sieve catalyst may have a particle size distribution such that not
greater than about 10 wt % of the catalyst particles have an average
diameter less than or equal to 20 .mu.m; preferably not greater
than about 5 wt % of the catalyst particles have an average diameter
less than or equal to 20 .mu.m, and more preferably not greater
than about 2 wt % of the catalyst particles have an average diameter
less than or equal to 20 .mu.m. In another embodiment, the catalyst
composition is comprised of catalyst particles, wherein, after calcination
of the catalyst composition, not greater than about 10 wt % of the
catalyst particles have an average diameter greater than or equal
to about 250 .mu.m; preferably not greater than about 5 wt % of
the catalyst particles have an average diameter greater than or
equal to about 250 .mu.m, more preferably not greater than about
2 wt % of the catalyst particles have an average diameter greater
than or equal to 250 .mu.m.
[0100] In another embodiment of the invention, the calcined catalyst
particles made according to the process of the invention have a
particle distribution such that the catalyst composition is particularly
suited for use in fluidized bed reaction systems. In one embodiment,
the calcined catalyst has a particle distribution in .mu.m of 2<d.sub.10<50;
30<d.sub.50<120; and 50<d.sub.90<250 wherein d.sub.10
is the average diameter in which the cumulative volume of the sample
reaches 10% of the total, d.sub.50 is the average diameter in which
the cumulative volume of the sample reaches 50% of the total, and
d.sub.90 is the average diameter in which the cumulative volume
of the sample reaches 90% of the total. Preferably the calcined
catalyst has a particle distribution in .mu.m of 5<d.sub.10<45;
40<d.sub.50<100; and 70<d.sub.90<200 more preferably
a particle distribution in .mu.m of 10<d.sub.10<40; 50<d.sub.50<100;
and 90<d.sub.90<150.
[0101] In another embodiment of this invention, the catalyst composition
made from the method of this invention comprises particles which
are highly attrition resistant. Such particles are particularly
suited for use in fluidized catalytic systems.
[0102] In this invention, attrition resistance, or catalyst hardness,
is measured using an ExxonMobil Attrition rate Index (EMARI). The
EMARI is used over other measurement methods, since many other methods
are not sufficient to measure very highly attrition resistant molecular
sieve catalysts such as those made according to this invention.
[0103] The EMARI methodology is similar to the conventional Davison
Index method. The smaller the EMARI, the more resistant to attrition,
hence the harder, is the catalyst. The EMARI is measured by adding
6.0.+-.0.1 g of catalyst having a particles size ranging from 53
to 125 microns to a hardened steel attrition cup. Approximately
23700 scc/min of nitrogen gas is bubbled through a water-containing
bubbler to humidify the nitrogen. The wet nitrogen passes through
the attrition cup, and exits the attrition apparatus through a porous
fiber thimble. The flowing nitrogen removes the finer particles,
with the larger particles being retained in the cup. The porous
fiber thimble separates the fine catalyst particles from the nitrogen
that exits through the thimble. The fine particles remaining in
the thimble represent catalyst that has broken apart through attrition.
[0104] The nitrogen flow passing through the attrition cup is maintained
for 1 hour. The fines collected in the thimble are removed from
the unit. A new thimble is then installed. The catalyst left in
the attrition unit is attrited for an additional 3 hours, under
the same gas flow and moisture levels. The fines collected in the
thimble are recovered. The collection of fine catalyst particles
separated by the thimble after the first hour are weighed. The amount
in grams of fine particles divided by the original amount of catalyst
charged to the attrition cup expressed on per hour basis is the
EMARI, in wt %/hr.
EMARI=C/(B+C)/D.times.100%
[0105] wherein
[0106] B=weight of catalyst left in the cup after the attrition
test
[0107] C=weight of collected fine catalyst particles after the
first hour of attrition treatment
[0108] D=duration of treatment in hours after the first hour attrition
treatment.
[0109] The calcined molecular sieve catalyst particles which are
made from the method of this invention desirably have an EMARI of
not greater than about 1 wt %/hr. Preferably the calcined molecular
sieve catalyst particles have an EMARI of not greater than about
0.7 wt %/hr, more preferably not greater than about 0.3 wt %/hr.
[0110] The present invention thus also encompasses a calcined molecular
sieve catalyst containing catalyst particles having an EMARI of
not greater than about 1 wt %/hr, preferably of not greater than
about 0.7 wt %/hr, more preferably of not greater than about 0.3
wt %/hr.
[0111] This invention will be better understood with reference
to the following examples, which are intended to illustrate specific
embodiments within the overall scope of the invention as claimed.
EXAMPLE 1
[0112] Dried molecular sieve catalyst compositions A1 A2 A3 (first
dried molecular sieve catalyst compositions in the context of the
present invention) were prepared according to the following procedure:
[0113] A slurry was made by mixing together water and a solid composition
comprising 40 wt % SAPO-34 10.6 wt % alumina derived from aluminum
chlorohydrate (Reheis Chemicals Inc., Berkeley Heights, N.J.), and
49.4 wt % kaolin clay (Engelhard Corporation, Gordon, Ga.). The
slurry was comprised of 45 wt % of the solid composition. The slurry
was then dried in a spray dryer to yield first dried molecular sieve
catalyst compositions A1 A2 and A3.
EXAMPLE 2
[0114] Slurries were made from each of the dried molecular sieve
catalyst composition prepared in Example 1 by adding a portion of
each of the first dried molecular sieve catalyst composition to
deionized water to form a composition containing 45 wt % solids.
The composition was initially stirred using a spatula. Then the
composition was mixed using a Yamato DL-2100 mixer (Yamato Scientific
America Inc., Orangeburg, N.Y.) at 600 rpm for 5 minutes, then at
2400 rpm for 5 minutes.
[0115] The slurries obtained in this fashion from catalyst compositions
A1 A2 A3 will be hereinafter referred to as Slurry 1 Slurry 2
and Slurry 3 respectively.
EXAMPLE 3
[0116] A portion of Slurry 1 and Slurry 2 obtained in Example 2
was further mixed using a Silverson SR4 high-shear mixer (Silverson
Machines, Inc., Massachusetts) at 6500 rpm for 3 minutes. The slurries
obtained with high shear mixing will be hereinafter referred to
as Slurry HS 1 and Slurry HS2 respectively.
EXAMPLE 4
[0117] Slurry 1 prepared at example 2 and Slurry HSI prepared at
example 3 were compared for viscosity. Each of the slurries were
tested for viscosity using a Brookfield LV-DVE viscometer with a
No. 3 spindle at various rpms. The results are shown in Table 1.
1TABLE 1 Re-worked Slurry Viscosity Viscosity (cP) at Different
rpms Slurry 100 rpm 60 rpm 30 rpm 20 rpm 10 rpm Slurry 1 309 456
753 1044 1838 Slurry HS1 338 510 880 1202 2112
[0118] The data in Table 1 indicate that the slurry made using
high-shear mixing has a higher viscosity. This is an indication
that the higher the viscosity the smaller the particle size of the
solids in the slurry.
EXAMPLE 5
[0119] Portions of samples A1 A2 and A3 prepared in Example 1
were calcined in a muffle furnace at 650.degree. C. in air for 2
hours. This yielded samples A1calc, A2calc and A3calc, respectively.
The attrition resistance of these samples was determined using the
EMARI test described in the specification. The results are shown
in Table 2.
EXAMPLE 6
[0120] Portions of Slurry 2 and Slurry 3 prepared in Example 2
were spray dried using a Yamato DL-41 spray dryer, operating in
a down spray mode using a 1 mm atomization nozzle. The spray drying
conditions were: 40 g/min feed rate; 350.degree. C. inlet temperature;
1 bar atomization pressure; 60% gas flow carrier setting. This yielded
second dried molecular sieve compositions B2 and B3 respectively.
[0121] The spray dried products were collected in a cyclone, and
calcined in a muffle furnace at 650.degree. C. in air for 2 hours.
This yielded samples B2calc and B3calc, respectively. The attrition
resistance of these samples was determined using the EMARI test
described in the specification. The results are shown in Table 2.
EXAMPLE 7
[0122] Portions of Slurry HS1 and Slurry HS2 prepared at example
3 were spray dried using a Yamato DL-41 spray dryer, operating in
a down spray mode using a 1 mm atomization nozzle. The spray drying
conditions were: 40 g/min feed rate; 350.degree. C. inlet temperature;
1 bar atomization pressure; 60% gas flow carrier setting. This yielded
second dried molecular sieve samples C1 and C2 respectively. The
spray dried products were collected in a cyclone, and calcined in
a muffle furnace at 650.degree. C. in air for 2 hours. This yielded
samples C1calc and C2calc, respectively. The attrition resistance
of these samples was determined using the EMARI test described in
the specification. The results are shown in Table 2. |