Molecular sieve abstract
This invention provides an attrition resistant metalloaluminophosphate
molecular sieve catalyst composition, methods of making the catalyst
composition and processes for using the catalyst composition. The
metalloaluminophosphate molecular sieve catalyst composition is
highly attrition resistant in dried as well as fully calcined forms.
Molecular sieve claims
We claim:
1. A metalloaluminophosphate molecular sieve catalyst composition
comprising metalloaluminophosphate molecular sieve crystals, clay
and binder, wherein the catalyst has a core clay to alumina ratio
of from 2.2:1 to 2.6:1 a surface clay to alumina ratio of from
1.7:1 to 3.1:1 and an attrition rate index of not greater than
0.5 wt %/hr.
2. The catalyst of claim 1 wherein the catalyst composition has
a core clay to alumina ratio of from 2.3:1 to 2.5:1.
3. The catalyst of claim 3 wherein the catalyst composition has
a surface clay to alumina ratio of from 1.8:1 to 3:1.
4. The catalyst of claim 4 wherein the catalyst composition has
a surface clay to alumina ratio of from 1.9:1 to 2.9:1.
5. The catalyst of claim 5 wherein the catalyst composition has
a surface clay to alumina ratio of from 2:1 to 2.8:1.
6. The catalyst of claim 1 wherein the catalyst composition has
an attrition rate index of not greater than 0.4 wt %/hr.
7. The catalyst of claim 6 wherein the catalyst composition has
an attrition rate index of not greater than 0.3 wt %/hr.
8. The catalyst of claim 1 wherein the catalyst composition has
an apparent bulk density of at least 0.83 g/cc.
9. The catalyst of claim 8 wherein the catalyst composition has
an apparent bulk density of at least 0.84 g/cc.
10. The catalyst of claim 9 wherein the catalyst composition has
an apparent bulk density of at least 0.85 g/cc.
11. The catalyst of claim 10 wherein the catalyst composition
has an apparent bulk density of at least 0.86 g/cc.
12. The catalyst of claim 1 wherein the metalloaluminophosphate
molecular sieve crystals are selected from the group consisting
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 SAPO-47 SAPO-56 AlPO-5 AlPO-11 AlPO-18 AlPO-31 AlPO-34
AlPO-36 AlPO-37 AlPO-46 metal containing molecular sieves thereof,
and mixtures thereof.
13. The catalyst of claim 1 wherein the clay is a natural or synthetic
clay.
14. The catalyst of claim 1 wherein the binder is an inorganic
oxide sol of alumina or silica.
15. The catalyst of claim 1 wherein the catalyst composition is
a spray dried catalyst composition.
16. The catalyst of claim 1 wherein the catalyst composition is
a calcined catalyst composition.
17. A metalloaluminophosphate molecular sieve catalyst composition
comprising metalloaluminophosphate molecular sieve crystals, clay
and binder, wherein the catalyst composition has an apparent bulk
density of at least 0.83 g/cc, and an attrition rate index (ARI)
of not greater than 0.5 wt %/hr.
18. The catalyst of claim 17 wherein the catalyst composition
has an apparent bulk density of at least 0.84 g/cc.
19. The catalyst of claim 18 wherein the catalyst composition
has an apparent bulk density of at least 0.85 g/cc.
20. The catalyst of claim 19 wherein the catalyst composition
has an apparent bulk density of at least 0.86 g/cc.
21. The catalyst of claim 17 wherein the catalyst has a core clay
to alumina ratio of from 2.2:1 to 2.6:1 and a surface clay to alumina
ratio of from 1.7:1 to 3.1:1.
22. A method of making an attrition resistant metalloaluminophosphate
molecular sieve catalyst composition, comprising the steps of: a)
mixing together metalloaluminophosphate molecular sieve crystals,
clay and binder at a breakage energy effective to break apart agglomerates
and aggregates; and b) drying the mixture to produce a dried metalloaluminophosphate
molecular sieve catalyst composition having an attrition rate index
of not greater than 0.5 wt %/hr.
23. The method of claim 22 wherein the mixture is dried by spray
drying.
24. The method of claim 22 wherein the dried metalloaluminophosphate
molecular sieve catalyst composition is calcined to form a calcined
metalloaluminophosphate molecular sieve catalyst having an attrition
rate index of not greater than 0.5 wt %/hr.
25. The method of claim 22 wherein the breakage energy is at least
10.sup.-5 cal cm.sup.-2.
26. The method of claim 25 wherein the breakage energy is at least
5.times.10.sup.-5 cal cm.sup.-2.
27. The method of claim 26 wherein the breakage energy is at least
10.sup.-4 cal cm.sup.-2.
28. The method of claim 27 wherein the breakage energy is not
greater than 10.sup.-1 cal cm.sup.-2.
29. The method of claim 28 wherein the breakage energy is not
greater than 6.times.10.sup.-2 cal cm.sup.-2.
30. The method of claim 29 wherein the breakage energy is not
greater than 5.times.10.sup.-2 cal cm.sup.-2.
31. The method of claim 22 wherein the metalloaluminophosphate
molecular sieve crystals are selected from the group consisting
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 SAPO-47 SAPO-56 AlPO-5 AlPO-11 AlPO-18 AlPO-31 AlPO-34
AlPO-36 AlPO-37 AlPO-46 metal containing molecular sieves thereof,
and mixtures thereof.
32. The method of claim 22 wherein the clay is a natural or synthetic
clay.
33. The method of claim 22 wherein the binder is an inorganic
oxide sol of alumina or silica.
34. The method of claim 22 wherein the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together to
form a mixture having a viscosity of at least 500 cP.
35. The method of claim 22 wherein the mixture is aged prior to
drying.
36. The method of claim 22 wherein the mixture has a solids content
of at least 40 wt %, based on total weight of the mixture.
37. The method of claim 36 wherein the slurry has a solids content
of not greater than 60 wt %.
38. The method of claim 22 wherein the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together at
a binder to molecular sieve weight ratio of at least 0.20:1.
39. The method of claim 38 wherein the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together at
a binder content of at least 5 wt %, based on total weight of the
mixture, excluding liquid.
40. A process for making olefin product from oxygenate, comprising
the steps of: a) introducing a metalloaluminophosphate molecular
sieve catalyst composition comprising metalloaluminophosphate molecular
sieve crystals, clay and binder into a reaction system, wherein
the catalyst has a core clay to alumina ratio of from 2.2:1 to 2.6:1.
a surface clay to alumina ratio of from 1.7:1 to 3.1:1 and an attrition
resistance index of not greater than 0.5 wt %/hr; and b) contacting
the catalyst composition with oxygenate in the reaction system to
form olefin product.
41. The process of claim 40 wherein the catalyst composition has
a core clay to alumina ratio of from 2.3:1 to 2.5:1.
42. The process of claim 41 wherein the catalyst composition has
a surface clay to alumina ratio of from 1.8:1 to 3:1.
43. The process of claim 42 wherein the catalyst composition has
a surface clay to alumina ratio of from 1.9:1 to 2.9:1.
44. The process of claim 43 wherein the catalyst composition has
a surface clay to alumina ratio of from 2:1 to 2.8:1.
45. The process of claim 40 wherein the catalyst composition has
an attrition rate index of not greater than 0.4 wt %/hr.
46. The process of claim 45 wherein the catalyst composition has
an attrition rate e index of not greater than 0.3 wt %/hr.
47. The process of claim 40 wherein the metalloaluminophosphate
molecular sieve crystals are selected from the group consisting
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 SAPO-47 SAPO-56 AlPO-5 AlPO-11 AlPO-18 AlPO-31 AlPO-34
AlPO-36 AlPO-37 AlPO-46 metal containing molecular sieves thereof,
and mixtures thereof.
48. The process of claim 40 wherein the clay is a natural or synthetic
clay.
49. The process of claim 40 wherein the binder is an inorganic
oxide sol of alumina or silica.
50. The process of claim 40 wherein the catalyst composition is
a spray dried catalyst composition.
51. The process of claim 40 wherein the catalyst composition is
a calcined catalyst composition.
52. A process for making olefin product, comprising the steps of:
a) mixing together metalloaluminophosphate molecular sieve crystals,
clay and binder at a breakage energy effective to break apart agglomerates
and aggregates; b) drying the mixture to produce a dried metalloaluminophosphate
molecular sieve catalyst composition having an attrition resistance
index of not greater than 0.5 wt %/hr; c) calcining the dried metalloaluminophosphate
molecular sieve catalyst composition to form a calcined metalloaluminophosphate
molecular sieve catalyst having an attrition rate index of not greater
than 0.5 wt %/hr; and d) contacting the calcined metalloaluminophosphate
molecular sieve catalyst with oxygenate to form olefin product.
53. The process of claim 52 wherein the breakage energy is at
least 10.sup.-5 cal cm.sup.-2.
54. The process of claim 53 wherein the breakage energy is at
least 5.times.10.sup.-5 cal cm.sup.-2.
55. The process of claim 54 wherein the breakage energy is at
least 10.sup.-4 cal cm.sup.-2.
56. The process of claim 55 wherein the breakage energy is not
greater than 5.times.10.sup.-2 cal cm.sup.-2.
57. The process of claim 52 wherein the metalloaluminophosphate
molecular sieve crystals are selected from the group consisting
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 SAPO-47 SAPO-56 AlPO-5 AlPO-11 AlPO-18 AlPO-31 AlPO-34
AlPO-36 AlPO-37 AlPO-46 metal containing molecular sieves thereof,
and mixtures thereof.
58. The process of claim 52 wherein the clay is a natural or synthetic
clay.
59. The process of claim 52 wherein the binder is an inorganic
oxide sol of alumina or silica.
60. The process of claim 52 wherein the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together to
form a mixture having a viscosity of at least 1000 cP.
61. The process of claim 52 wherein the mixture is aged prior
to drying.
62. The process of claim 52 wherein the mixture has a solids content
of at least 40 wt %, based on total weight of the mixture.
63. The process of claim 62 wherein the mixture has a solids content
of not greater than 60 wt %, based on total weight of the mixture.
64. The process of claim 52 wherein the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together at
a binder to molecular sieve weight ratio of at least 0.20:1.
65. The process of claim 52 wherein the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together at
a binder content of at least 5 wt %, based on total weight of the
mixture, excluding liquid.
Molecular sieve description
FIELD OF THE INVENTION
[0001] This invention concerns attrition resistant molecular sieve
catalyst, as well as methods of making the catalyst and processes
for using the catalyst. In particular, this invention concerns methods
of making attrition resistant metalloaluminophosphate, particularly
silicoaluminophosphate, molecular sieve catalyst (e.g., formulated
molecular sieve catalyst), including methods of making the formulated
catalyst and processes for using the formulated catalyst.
BACKGROUND OF THE INVENTION
[0002] Molecular sieve crystals are generally microporous structures
composed of either crystalline aluminosilicate, belonging to a class
of materials known as zeolites, or crystalline aluminophosphates,
or crystalline metalloaluminophosphates such as silicoaluminophosphates.
The crystals are conventionally 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
salts.
[0003] Molecular sieve catalysts are compositions made of molecular
sieve crystal particles bound together to form a formulated catalyst
material. The formulated molecular sieve catalyst composition typically
includes other components such as binders, fillers such as 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 catalysts
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 to activate, the catalyst.
[0005] U.S. Pat. No. 4764269 (Edwards) discloses conventional
methods of making and using SAPO-37 molecular sieve catalyst that
can be used in catalytic cracking operations. The catalyst was found
to be adversely affected by moisture, but the crystalline structure
and activity of the molecular sieve component was preserved by including
a stabilizing amount of the organic template compound used in the
manufacture of the molecular sieve within the pore structure thereof
until such time as the catalyst was thermally activated during use.
[0006] Metalloaluminophosphate molecular sieves, such as the SAPO-37
molecular sieve described by Edwards, have a variety of uses. A
desirable characteristic for many of the metalloaluminophosphate
molecular sieves, regardless of the process of use, is that the
finished or formulated catalyst be attrition resistant, which can
refer to hardness as well as ability to absorb shock, since the
catalyst will typically have to endure severe stress in commercial
scale processes.
[0007] For example, WO 99/21651 describes a method for making molecular
sieve catalyst that is considered relatively hard. 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.
[0008] 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.
[0009] Attrition resistance continues to be a desirable characteristic
in molecular sieve catalysts. As new process systems are developed,
the ability of the catalyst to endure the stress of the process
system is particularly important so as to increase the effective
life of the catalyst in the reaction process. If the catalyst is
not properly attrition resistant, it is likely to break apart at
an early stage, meaning that the catalyst could only be effectively
used for a relatively short period of time. Therefore, obtaining
molecular sieve catalysts that have a high degree of attrition resistance
are still sought.
SUMMARY OF THE INVENTION
[0010] This invention provides molecular sieve catalyst, particularly
metalloaluminophosphate molecular sieve catalyst, that is highly
attrition resistant. Also provided are preferred methods of making
the catalyst and preferred methods of using the catalyst.
[0011] According to one aspect of the invention, a metalloaluminophosphate
molecular sieve is provided, which comprises molecular sieve crystals,
clay and binder. In one embodiment, the catalyst has a core clay
to alumina ratio of from 2.2:1 to 2.6:1. Preferably, the catalyst
composition has a core clay to alumina ratio of from 2.3:1 to 2.5:1.
[0012] In another embodiment, the catalyst has a surface clay to
alumina ratio of from 1.7:1 to 3.1:1. Preferably, the catalyst composition
has a surface clay to alumina ratio of from 1.8:1 to 3:1 more preferably
from 1.9:1 to 2.9:1 and most preferably from 2:1 to 2.8:1.
[0013] In yet another embodiment, the catalyst has an attrition
rate index of not greater than 0.5 wt %/hr. Preferably, the catalyst
composition has an attrition resistance index of not greater than
0.4 wt %/hr, more preferably not greater than 0.3 wt %/hr.
[0014] In another embodiment of the invention, the catalyst composition
has an apparent bulk density of at least 0.83 g/cc. Preferably,
the catalyst composition has an apparent bulk density of at least
0.84 g/cc, more preferably at least 0.85 g/cc and most preferably
at least 0.86 g/cc.
[0015] According to one embodiment of the invention, the metalloaluminophosphate
molecular sieve crystals are selected from the group consisting
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 SAPO-47 SAPO-56 AlPO-5 AlPO-11 AIPO-18 AlPO-31 AlPO-34
AlPO-36 AlPO-37 AlPO-46 metal containing molecular sieves thereof,
and mixtures thereof. Preferably, the clay is a natural or synthetic
clay. A preferred binder is an inorganic oxide sol of alumina or
silica.
[0016] The catalyst composition is in dried form. In one embodiment,
the dried catalyst is a spray dried catalyst composition. In another
embodiment, the catalyst composition is a calcined catalyst composition.
[0017] The invention further provides a method of making an attrition
resistant metalloaluminophosphate molecular sieve catalyst composition.
In general, the method involves mixing together metalloaluminophosphate
molecular sieve crystals, clay and binder at a breakage energy effective
to break apart agglomerates and aggregates and achieving binding
among sieve, binder, and matrix. The mixture is then dried to produce
a dried metalloaluminophosphate molecular sieve catalyst composition.
In one embodiment, the mixture is dried by spray drying. In another
embodiment, spray dried metalloaluminophosphate molecular sieve
catalyst composition is calcined to form a calcined metalloaluminophosphate
molecular sieve catalyst.
[0018] In one embodiment of the method of the invention, the breakage
energy is at least 10.sup.-5 cal cm.sup.-2. Preferably, the breakage
energy is at least 5.times.10.sup.-5 cal cm.sup.-2 more preferably
the breakage energy is at least 10.sup.-4 cal cm.sup.-2.
[0019] In another embodiment of the invention, the breakage energy
is not greater than 10.sup.-1 cal cm.sup.-2. Preferably, the breakage
energy is not greater than 6.times.10.sup.-2 cal cm.sup.-2 more
preferably not greater than 5.times.10.sup.-2 cal cm.sup.-2.
[0020] In another embodiment of the invention, the metalloaluminophosphate
molecular sieve crystals, clay and binder are mixed together to
form a mixture having a viscosity of at least 500 cP measured at
10 RPM using a Brookfield viscometer. In one embodiment, the mixture
is aged prior to drying. Preferably, the mixture has a solids content
of at least 40 wt %, based on total weight of the mixture. In another
embodiment, it is preferred that the slurry has a solids content
of not greater than 60 wt %.
[0021] In another embodiment, the metalloaluminophosphate molecular
sieve crystals, clay and binder are mixed together at a binder to
molecular sieve weight ratio of at least 0.20:1. In still another
embodiment, the metalloaluminophosphate molecular sieve crystals,
clay and binder are mixed together at a binder content of at least
5 wt %, based on total weight of the mixture, excluding liquid.
[0022] The invention further provides a process for making an olefin
product from an oxygenate. In one embodiment, the process includes
introducing a metalloaluminophosphate molecular sieve catalyst composition
comprising metalloaluminophosphate molecular sieve crystals, clay
and binder into a reaction system. The catalyst composition is then
contacted with an oxygenate in the reaction system to form the olefin
product.
[0023] In another embodiment, the invention provides a process
for making olefin product, which includes a step of mixing together
metalloaluminophosphate molecular sieve crystals, clay and binder
at a breakage energy effective to break apart agglomerates and aggregates.
The mixture is dried to produce a dried metalloaluminophosphate
molecular sieve catalyst composition having a low attrition resistance
index. The catalyst, in one embodiment, is then calcined to form
a calcined metalloaluminophosphate molecular sieve catalyst, which
also has a low attrition resistance index. The calcined catalyst
is then contacted with oxygenate to form olefin product.
DETAILED DESCRIPTION OF THE INVENTION
[0024] I. General Description
[0025] This invention provides an attrition resistant metalloaluminophosphate
molecular sieve catalyst composition, methods of making the catalyst
composition and processes for using the catalyst composition. The
metalloaluminophosphate molecular sieve catalyst composition is
highly attrition resistant in dried as well as calcined forms.
[0026] According to this invention, attrition resistant refers
to the ability to resist breaking apart as a result of physical
impact. Since molecular sieve catalysts are often used in fluidized
bed reaction systems or riser type reaction systems, the ability
of such catalysts to avoid physical damage within the reaction systems
is important. The catalyst of this invention is particularly attrition
resistant. Attrition resistance, however, does not necessarily mean
that the catalyst is hard, although hardness is a desirable characteristic.
Attrition resistance can also be obtained through such characteristics
as a catalyst's ability to absorb shock from impact as the catalyst
is circulated through the reaction system. In some sense, the ability
of the catalyst to absorb shock is similar to the ability of a ball
to bounce off a hard surface with deforming the ball.
[0027] The catalyst of this invention exhibits high attrition resistance
as a result of having a core composition that is substantially the
same structure as its external surface. This means that the catalyst
is substantially uniform in composition from the core region to
the external surface of the catalyst. If the surface of the catalyst
is substantially different from that of the core region, then there
will be a tendency for the catalyst to break down or break apart
as a result of physical stress. Thus, a relatively non-uniform catalyst
structure results in a catalyst composition having reduced attrition
resistance.
[0028] A preferred way of measuring surface composition is to measure
the clay to alumina ratio at the surface of the catalyst. This can
be accomplished using energy dispersive spectroscopy (EDS).
[0029] In this invention, EDS was performed using a Hitachi S-4300
scanning electron microscope equipped with a 30 mm.sup.2 PGT Prism
energy dispersive X-ray spectrometer. The following microscope and
collection parameters were used: accelerating voltage=6 kV; objective
aperture=1 (100 .mu.m); C.sub.2 spot size=5; working distance=15
mm; sample-detector distance 25 mm; collection time=100 s; detector
resolution=10 eV/channel; and a detector dead time.apprxeq.10-20%.
Under these collection conditions, the sampling depth for P K.alpha.,
Si K.alpha., Al K.alpha. and O K.alpha. X-rays is between.apprxeq.2.2-2.5
.mu.m (i.e., the maximum escape depth for X-rays) for a formulated
catalyst sample having a bulk density of approximately 0.5 g/cm.sup.3.
This escape depth can be calculated using the Anderson-Hasler X-ray
range equation [1], which requires the average density (0.5 g/cm.sup.3
formulated catalyst) of the sample and the incident accelerating
voltage (6 kV). 1 R X - Ray = 0.064 ( E 0 1.68 - E C 1.68 ) [ 1
]
[0030] In equation [1], E.sub.0 is the incident accelerating voltage,
E.sub.c is the characteristic X-ray energy and p is the sample density.
[0031] Particles>50 .mu.m in diameter were randomly selected
to determine surface clay to alumina ratio. A 6.times.6 .mu.m box
was positioned on the crown of the particle and the beam rastered
for 100 s across the 36 .mu.m.sup.2 region to collect the EDS spectrum.
Typically, a total of 20 particles was analyzed for each sample.
[0032] In order to quantify the composition of EDS spectra from
the 20 particles from each sample, standard spectra were collected
from each of the individual components (molecular sieve, binder
and clay). Using microscope settings and collection conditions indicated
above, 20 individual spectra were collected from each reference
material. A single reference spectra was generated from the 20 individual
spectra by summing the 20 spectra and then dividing by 20 to from
an average spectrum for the reference material.
[0033] A software package (IDL) was used to fit the entire spectra
(0-6 keV) of each of the primary catalyst components (molecular
sieve, binder and clay) against the 20 individual spectra that were
collected from the 20 individual formulated catalyst particles.
This allowed the relative concentrations of each of the three primary
components in each particle to be determined. The fitting routine
output as fractional components the relative contributions of the
three reference spectra to the spectra collected from the particles.
[0034] In order to determine the degree of uniformity between the
surface composition and the core composition of the catalyst, the
clay to alumina ratio at the surface of the catalyst and at the
core is compared. The clay to alumina ratio at the core region of
the catalyst is determined by crushing a sample of the catalyst
to form a bulk composition and using EDS to determine the clay to
alumina ratio of the bulk composition in the same manner as for
the surface samples.
[0035] Fractional amounts of crushed catalyst can be compared with
known fractional components to develop a correction factor. For
example, the deviation between measured and known catalyst components
allowed for a X-ray absorption correction factor to be developed
which was then applied to all of the spectra collected from the
surface of the 20 particles analyzed per sample. This absorption
corrected value of the original fractional components was then calculated
and averaged for the 20 particles. The ratio of the average value
measured from 20 particles provided the final clay/alumina ratio.
[0036] The catalyst of this invention is characterized by being
highly uniform in composition, as well as attrition resistant. These
characteristics are exhibited in all dried forms of the fully formulated
catalyst composition, including spray dried forms and calcined forms.
The advantage is that the catalyst does not have to be completely
calcined to be considered attrition resistant, which is particularly
advantageous with regards to shipping or storage. For example, the
catalyst can be dried but not so extensively to remove template
material from the catalyst. Leaving in the template material will
provide increased protection to avoid damage of the catalyst activity
as a result of contact with moisture. Even low levels of moisture
(i.e., water) contacting internal catalyst sites can cause significant
decreases in catalytic activity.
[0037] II. Catalyst Composition Components
[0038] A. Overall Composition
[0039] The catalyst of this invention is a metalloaluminophosphate
molecular sieve catalyst composition, which comprises metalloaluminophosphate
molecular sieve crystals, clay and binder. Such a combination is
generally referred to as a formulated catalyst. In one aspect, the
formulated catalyst composition is characterized by being highly
resistant to attrition.
[0040] B. Molecular Sieve Crystal Component
[0041] The metalloaluminophosphate molecular sieve component can
be represented by the empirical formula, on an anhydrous basis:
mR:(M.sub.xAl.sub.yP.sub.z)O.sub.2
[0042] 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, VIIB 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.
[0043] Examples of metalloaluminophosphate molecular sieves which
can be used in this invention are 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 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), PCT WO 01/62382 published Aug. 30 2001
(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.
[0045] Most preferably, the metalloaluminophosphate molecular sieve
crystals present in the molecular sieve catalyst composition are
selected from the group consisting of silicoaluminophosphate (SAPO)
molecular sieves, aluminophosphate molecular sieves and metal substituted
forms thereof. Non-limiting examples of SAPO and AlPO molecular
sieves that may be present in the molecular sieve catalyst of the
invention include molecular sieves selected from the group consisting
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 SAPO-47 SAPO-56 AlPO-5 AlPO-11 AlPO-18 AlPO-31 AlPO-34
AlPO-36 AlPO-37 AlPO-46 metal containing molecular sieves thereof,
and mixtures thereof. The more preferred molecular sieves include
molecular sieves selected from the group consisting of SAPO-18
SAPO-34 SAPO-35 SAPO-44 SAPO-56 AlPO-18 AlPO-34 metal containing
molecular sieves thereof, and mixtures thereof; even more preferably
molecular sieves selected from the group consisting of SAPO-18
SAPO-34 AlPO-34 AlPO-18 metal containing molecular sieves thereof,
and mixtures thereof; and most preferably molecular sieves selected
from the group consisting of SAPO-34 AlPO-18 metal containing
molecular sieves thereof, and mixtures thereof.
[0046] 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. With
regard to the molecular sieve crystal components of the catalyst,
the term further encompasses physical mixtures of crystalline and
amorphous components, 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.
[0047] In one embodiment, the molecular sieve crystal is an intergrowth
material having two or more distinct phases of crystalline structures
within one molecular sieve composition. In another embodiment, the
molecular sieve crystal 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 crystal comprises a
mixture of intergrown material and non-intergrown material.
[0048] C. Clay Component
[0049] The clay component of the catalyst of this invention can
be a natural or synthetic clay. Naturally occurring clays or modified
natural occurring clays, e.g., partially dried or dehydrated, milled
or micronized, or chemically treated are preferred. Such naturally
occurring clays include clays from the kaolinite group, the mica
group, the smectite group, and the chlorite group. Examples of kaolinite
group clays include kaolinite, dickite and halloysite. Examples
of the mica group clays include muscovite, illite, glauconite and
biotite. Examples of the smectite group include montmorillonite
and vermiculite. Examples of the chlorite group include penninite,
clinochlore, ripidolite and chamosite.
[0050] Mixed layer clays can also be used. These clays are made
of a regular or random stacking of layers composed of members of
one or more groups of clay minerals. Chlorite may be seen as a regular
alternation of mica and brucite layers. Random mixed layering of
three layer clays is common, with examples being mixed layer mica/smectite
and chlorite/vermiculite. In regular mixed layer structures such
as chlorite, the basal spacing is a combination of that of the individual
layers. In random mixed layering there is a non-integral series
of reflections from the basal planes. This is shown as a composite
reflection intermediate in position between those of the individual
layers, or as a spreading of the reflection. Thus, when a significant
amount of smectite is interlayered with mica in a random manner,
the mica peak will not be sharp, but will be spread towards the
lower angle smectite reflection. The amount of spreading depends
on the amount of mixed layering that exists.
[0051] D. Binder Component
[0052] Binders that are used in this invention are materials that
act like glue, binding together the molecular sieve crystals and
other materials, to form a formulated molecular sieve catalyst composition.
Non-limiting examples of binders that can be used in this invention
include various types of inorganic oxide sols such as an inorganic
oxide sol of alumina or silica, and in particular, aluminum chlorohydrate,
hydrated aluminas, silicas, and/or other inorganic oxide sols.
[0053] E. Catalyst Composition Characteristics
[0054] One characteristic of the formulated catalyst composition
of this invention is that it is substantially uniform in composition.
The degree of uniformity from a core region of the catalyst to an
external surface is preferably assessed by comparing the clay to
alumina ratio of the catalyst at the core region and at the surface.
A high degree of uniformity means that there are insubstantial differences
between the clay to alumina ratio at the core and at the surface.
[0055] In one embodiment, the catalyst composition has a core clay
to alumina ratio of from 2.2:1 to 2.6:1. Preferably, the catalyst
composition has a core clay to alumina ratio of from 2.3:1 to 2.5:1.
[0056] In another embodiment, the catalyst composition has a surface
clay to alumina ratio of from 1.7:1 to 3.1:1. Preferably, wherein
the catalyst composition has a surface clay to alumina ratio of
from 1.8:1 to 3:1 more preferably from 1.9:1 to 2.9:1 and most
preferably from 2:1 to 2.8:1.
[0057] Another characteristic of the catalyst of this invention
is that it is highly attrition resistant, as measured by the Attrition
Rate Index (ARI) method. The ARI 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.
[0058] The ARI methodology is similar to the conventional Davison
Index method. The smaller the ARI is, the more resistant to attrition
the catalyst is. The ARI 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 24000 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.
[0059] The nitrogen flow passing through the attrition cup is maintained
for 1 hour. The fines collected in the thimble are removed from
the unit. A new thimble is then installed. The catalyst left in
the attrition unit is attrited for an additional 3 hours, under
the same gas flow and moisture levels. The fines collected in the
thimble are recovered. The collection of fine catalyst particles
separated by the thimble after the first hour are weighed. The amount
in grams of fine particles divided by the original amount of catalyst
charged to the attrition cup expressed on per hour basis is the
ARI, in wt %/hr.
ARI=C/(B+C)/D.times.100%
[0060] wherein
[0061] B=weight of catalyst left in the cup after the attrition
test
[0062] C=weight of collected fine catalyst particles after the
first hour of attrition treatment
[0063] D=duration of treatment in hours after the first hour attrition
treatment.
[0064] In one embodiment, the formulated catalyst composition has
an attrition resistance index of not greater than 0.5 wt %/hr. Preferably,
wherein the catalyst composition has an attrition resistance index
(ARI) of not greater than 0.4 wt %/hr, and more preferably not greater
than 0.3 wt %/hr.
[0065] The catalyst composition of the invention also has a relatively
high density relative to conventional catalysts. In particular,
the catalyst composition of the invention has a relatively high
apparent bulk density (ABD) relative to conventional catalysts.
[0066] According to the invention, one way of measuring ABD was
using the following procedure. A KIMAX graduated cylinder from KAMLE
USA, accurate to 0.05 cc and having a 25 cc capacity, was used to
weigh catalyst. The empty cylinder was weighed and the weight recorded
as Wa. Approximately 25 cc of spray dried and calcined catalyst
was poured into the cylinder, and the cylinder was tapped against
a lab bench surface at a frequency of 160-170 times per minute for
30 seconds to pack the cylinder into the cylinder. The weight of
the packed cylinder was weighed and recorded as W.sub.b. The volume
of the catalyst in the cylinder was determined by reading the level
of the packed catalyst in the cylinder and recorded as V.sub.c.
ABD was then calculated as ABD=(W.sub.b-W.sub.a)/V.sub.c.
[0067] In one embodiment, the catalyst composition has an apparent
bulk density (ABD) of at least 0.83 g/cc. Preferably, the catalyst
composition has an ABD at least 0.84 g/cc, more preferably at least
0.85 g/cc, and most preferably at least 0.86 g/cc. Generally, the
catalyst density is not significantly greater than water. In one
embodiment, the catalyst composition has an ABD not greater than
1 g/cc. Preferably, the catalyst composition has an ABD not greater
than 0.99 g/cc, and more preferably not greater than 0.98 g/cc.
[0068] The catalyst composition of this invention is a dried catalyst
composition. It can be dried so that it retains a template within
the pore structure of the molecular sieve component, such as by
spray drying, or it can be further dried, such as by calcining,
which removes the template from the pore structure. Because the
dried catalyst is attrition resistant, it is not necessary to calcine
the formulated composition prior to use. For example, the dried
composition can be loaded into a reaction system so that conditions
within the system remove the template to activate the catalyst for
use during operation of the reaction process.
[0069] III. Methods of Making Catalyst
[0070] A. Making Molecular Sieve Crystals
[0071] Generally, molecular sieves (i.e., molecular sieve crystals)
are synthesized by the hydrothermal crystallization of one or more
of a source of aluminum, a source of phosphorus, a source of silicon,
water and a templating agent, such as a nitrogen containing organic
compound. Typically, a combination of sources of silicon and aluminum,
or silicon, aluminum and phosphorus, water and one or more templating
agents, is placed in a sealed pressure vessel. The vessel is optionally
lined with an inert plastic such as polytetrafluoroethylene, and
heated under a crystallization pressure and temperature, until a
crystalline material is formed, which can then recovered by filtration,
centrifugation and/or decanting.
[0072] 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 tetraalkylorthosilicates, for example, tetramethylorthosilicate
(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.
[0073] 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.
[0074] 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.
[0075] In general, templating agents or templates include compounds
that contain elements of Group 15 of the Periodic Table of Elements,
particularly nitrogen, phosphorus, arsenic and antimony. Typical
templates 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 templates are 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.
[0076] Non-limiting examples of templates include tetraalkyl ammonium
compounds including salts thereof, such as tetramethyl ammonium
compounds, tetraethyl ammonium compounds, tetrapropyl ammonium compounds,
and tetrabutylammonium compounds, cyclohexylamine, morpholine, di-n-propylamine
(DPA), tripropylamine, triethylamine (TEA), triethanolamine, piperidine,
cyclohexylamine, 2-methylpyridine, N,N-dimethylbenzylamine, N,N-diethylethanolamine,
dicyclohexylamine, N,N-dimethylethanolamine, choline, N,N'-dimethylpiperazine,
14-diazabicyclo(222)octane, N',N',N,N-tetramethyl-(16)hexanediamine,
N-methyldiethanolamine, N-methyl-ethanolamine, N-methyl piperidine,
3-methyl-piperidine, N-methylcyclohexylamine, 3-methylpyridine,
4-methyl-pyridine, quinuclidine, N,N'-dimethyl-14-diazabicyclo(222)
octane ion; di-n-butylamine, neopentylamine, di-n-pentylamine, isopropylamine,
t-butyl-amine, ethylenediamine, pyrrolidine, and 2-imidazolidone.
Preferred templates are selected from the group consisting of tetraethyl
ammonium salts, cyclopentylamine, aminomethyl cyclohexane, piperidine,
triethylamine, cyclohexylamine, tri-ethyl hydroxyethylamine, morpholine,
dipropylamine (DPA), pyridine, isopropylamine, heated degraded forms
thereof, and combinations thereof.
[0077] The pH of the synthesis mixture containing at a minimum
a silicon, aluminum, optionally a 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.
[0078] 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.
[0079] In one embodiment, the synthesis of molecular sieve crystalline
particles is aided by seeds from another or the same framework type
molecular sieve.
[0080] The time required to form the crystalline particles 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.
[0081] One method for crystallization involves subjecting an aqueous
reaction mixture containing an excess amount of a templating agent
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.
[0082] 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 Publication
No. 20020055433 published May 9 2002 (cooling molecular sieve),
U.S. Pat. No. 6448197 (metal impregnation including copper), U.S.
Pat. No. 6521562 (conductive microfilter), and U.S. Patent Application
Publication No. 20020115897 published Aug. 22 2002 (freeze drying
the molecular sieve), which are all herein fully incorporated by
reference.
[0083] 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 particle product, normally termed the
"wet filter cake", may then be washed, such as with water,
and then dried, such as in air, before being formulated into a catalyst
composition. Alternatively, the wet filter cake may be formulated
into a catalyst composition directly, that is without any drying,
or after only partial drying.
[0084] B. Making Formulated Molecular Sieve Catalyst
[0085] 1. Components of Formulated Molecular Sieve Catalyst
[0086] Molecular sieve catalyst, which contains molecular sieve
crystal product, binder and matrix materials, is also referred to
as a formulated catalyst. It is made by mixing together molecular
sieve crystals (which preferably includes template) and a liquid,
with matrix material and binder, to form a slurry. The slurry is
then dried (i.e., liquid is removed), without completely removing
the template from the molecular sieve. Since this dried molecular
sieve catalyst includes template, it has not been activated, and
is considered a preformed catalyst. The catalyst in this form is
resistant to catalytic loss by contact with moisture or water. However,
the preformed catalyst must be activated before use, and this invention
provides appropriate methods of activating, preferably by further
heat treatment, to maintain a low water content within the activated
catalyst.
[0087] The liquid used to form the slurry can be any liquid conventionally
used in formulating molecular sieve catalysts. Non-limiting examples
of suitable liquids include water, alcohol, ketones, aldehydes,
esters, or a combination thereof. Water is a preferred liquid.
[0088] Matrix materials are included in the slurry used to make
the formulated molecular sieve catalyst of this invention. Such
materials are typically effective as thermal sinks assisting in
shielding heat from the catalyst composition, for example, during
regeneration. They can further act to densify the catalyst composition,
increase catalyst strength such as crush strength and attrition
resistance, and to control the rate of conversion in a particular
process. 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.
[0089] One preferred type of matrix material used to make the catalyst
of this invention is clay. Particularly preferred clays include
kaolins such as, for example, Dixie, McNamee, Georgia and Florida
clays. Optionally, the matrix material, preferably any of the clays,
are calcined, acid treated, and/or chemical treated before being
used as a slurry component.
[0090] In a particular embodiment, the clay has a low iron or titania
content, and is most preferably kaolin clay. 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.
[0091] Preferably, the clay has an average particle size of from
about 0.05 .mu.m to about 0.75 .mu.m; more preferably from about
0.1 .mu.m to about 0.6 .mu.m. It is also desirable that the clay
material have a d.sub.90 particle size distribution of less than
about 1.5 .mu.m, preferably less than about 1 .mu.m.
[0092] Binders are also included in the slurry used to make the
formulated molecular sieve catalyst of this invention. In one embodiment
of the invention, the binder is an alumina-containing sol, preferably
aluminium chlorohydrate. Upon calcining, the inorganic oxide sol,
is converted into an inorganic oxide matrix component, which is
particularly effective in forming an attrition resistant molecular
sieve catalyst composition. For example, an alumina sol will convert
to an aluminium oxide matrix following heat treatment.
[0093] 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)
[0094] 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.2-
4Cl.sub.712(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.
[0095] Aluminum chlorohydrate can prepared by dissolving either
metallic aluminum or hydrated alumina in hydrochloric acid under
controlled conditions, and is available commercially in different
forms, such as solid products; for example, the solid of chemical
formula Al.sub.2(OH).sub.5Cl.n(H.sub.2O) or as pre-prepared, commercially
available, aqueous solutions. Other non-limiting examples of useful
aluminum oxide precursors that may be used according to this invention
include aluminum hexahydrate, aluminum pentachlorohydrate (Al.sub.2(OH)Cl.sub.5),
aluminum tetrachlorohydrate (Al.sub.2(OH).sub.2Cl.sub.4), aluminum
trichlorohydrate (Al.sub.2(OH).sub.3Cl.sub.3), aluminum dichlorohydrate
(Al.sub.2(OH).sub.4Cl.sub.2), aluminum sesquichlorohydrate (Al.sub.2(OH).sub.4.5Cl.sub.1.5).
[0096] Other non-limiting examples of binders useful according
to this invention include precursors of aluminum-zirconium oxides.
Such precursors include, but are not limited to, aluminum zirconium
chlorohydrates; for example, aluminum zirconium trichlorohydrate,
aluminum zirconium tetrachlorohydrate, aluminum zirconium pentachlorohydrate,
aluminum zirconium octachlorohydrate, aluminum zirconium chlorhydrex,
aluminum zirconium chlorhydrex glycine complexes (e.g., aluminum
zirconium trichlorohydrex glycine complex, aluminum zirconium tetrachlorohydrex
glycine complex, aluminum zirconium pentachlorohydrex glycine complex,
and aluminum zirconium octachlorohydrex glycine complex). In the
absence of glycine, these materials form gels in aqueous solutions.
Reheis Chemicals Inc., Berkeley Heights, N.J. produces a variety
of aluminum zirconium chlorohydrates. These materials can be prepared
from a variety of zirconium starting materials such as zirconyl
chloride (ZrOCl.sub.2), zirconyl hydroxychloride (ZrO(OH)Cl), zirconium
hydroxy carbonate paste (ZrO(OH)(CO.sub.3).sub.0.5), and combinations
of these zirconium starting materials, with a hydrated aluminum
solution, such as a solution of aluminum chlorohydrate, aluminum
hexahydrate, aluminum sesquichlorohydrate or aluminum dichlorohydrate
solution, or a solution obtained by combining one or several of
these aluminum species solutions.
[0097] In another embodiment, the binders are alumina sols, predominantly
comprising aluminium oxide, optionally including silicon. In yet
another embodiment, the binders are peptised alumina made by treating
alumina hydrates such as pseudobohemite, with an acid, preferably
a non-halogen acid, 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.
[0098] In a preferred embodiment, the amount of binder used to
prepare the molecular sieve catalyst composition is at least 5 wt
%, based on total weight of the material used to make the composition,
excluding liquid (i.e., after drying), particularly excluding water.
Preferably the amount of binder used to prepare the molecular sieve
catalyst is at least 8 wt %, and more preferably at least 10 wt
%, based on total weight of the material used in making the catalyst,
excluding liquid (i.e., after drying). It is also preferred that
the amount of binder used to prepare the molecular sieve catalyst
is not greater than about 50 wt %, preferably not greater than 40
wt %, and more preferably not greater than 30 wt %, based on total
weight of the material used in making the catalyst, excluding liquid
(i.e., after drying).
[0099] 2. Making a Slurry with Molecular Sieve Crystals
[0100] The molecular sieve crystals are mixed with clay and binder,
as well as liquid solvent component, to form a slurry. The components
can be mixed in any order, and the mixture is thoroughly stirred
to form the slurry. The more thorough the stirring, the better the
consistency of the slurry, and the more uniform will be the dried
catalyst composition.
[0101] The molecular sieve crystals, clay and binder are mixed
together at a breakage energy effective to break apart agglomerates
and aggregates, as defined in Practical Dispersion, R. F. Conley,
VCH, New York, p. 213 1996 which is incorporated herein by reference.
Mixers capable of mixing together components at the appropriate
breakage energy include impeller mills, ball mills, stirred media
mills, vibratory mills, multiple roll mills and ultrasonic dispersion
devices. Further description of appropriate mixing equipment is
described in Solid-Liquid Dispersions, B. Dobias et al., pp. 22-27
Marcel Dekker, New York, 1999 which is incorporated herein by reference.
[0102] In one embodiment, the molecular sieve crystals, clay and
binder are mixed together at the appropriate breakage energy using
a bead mill mixer. Preferably, the bead mill mixer incorporates
beads in the mixing portion of the mixer having a relative span
factor (RSF) that is relatively low, meaning that there is small
variation in bead diameter. The RSF is calculated as RSF=(d.sub.90-d.sub.10)/d.sub.50
wherein d.sub.90 refers to particle diameter at 90% particle distribution,
d.sub.10 refers to particle diameter at 10% particle distribution,
and d.sub.50 refers to particle diameter at 50% particle distribution.
Preferably, the beads have a RSF of not greater than 0.2 more preferably
not greater than 0.15 and most preferably not greater than 0.1.
[0103] In one embodiment, the components used to make the molecular
sieve catalyst composition are mixed at breakage energy of at least
10.sup.-5 cal cm.sup.-2. Preferably, the components used to make
the molecular sieve catalyst composition are mixed at breakage energy
of at least 5.times.10.sup.-4 cal cm.sup.-2 and more preferably
at least 10.sup.-4 cal cm.sup.-2.
[0104] The breakage energy should high enough to obtain the desired
characteristics of the invention. However, the breakage energy should
not be so high as to break apart chemical bonds. In another embodiment,
the components used to make the molecular sieve catalyst composition
are mixed at breakage energy of not greater than 10.sup.-1 cal cm.sup.-2.
Preferably, the components used to make the molecular sieve catalyst
composition are mixed at breakage energy of not greater than 6.times.10.sup.-2
cal cm.sup.-2 and more preferably not greater than 5.times.10.sup.-2
cal cm.sup.-2. Bead mills typically generate a breakage energy of
6.times.10.sup.-5 to 6.times.10.sup.-2 cal cm.sup.-2 whereas impeller
mills typically generate a breakage energy of 10.sup.-5 to 2.times.10.sup.-4
cal cm.sup.-2 and ball mills generate a breakage energy of 10.sup.-5
to 6.times.10.sup.-3 cal cm.sup.-2.
[0105] In one embodiment, the slurry has a viscosity of at least
400 cP (0.4 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 at least 500 cP (0.5 Pa/sec), more preferably at least 600 cP
(0.6 Pa/sec), and most preferably at least 700 cP (0.7 Pa/sec),
as measured using a Brookfield LV-DVE viscometer with a No. 3 spindle
at 10 rpm. It is also preferred that the slurry have a viscosity
that is not greater than 12500 cP (12.5 Pa/sec), as measured using
a Brookfield LV-DVE viscometer with a No. 3 spindle at 10 rpm. Preferably,
the slurry has a viscosity not greater than 11000 cP (11 Pa/sec),
and more preferably not greater than 10500 cP (10.5 Pa/sec), as
measured using a Brookfield LV-DVE viscometer with a No. 3 spindle
at 10 rpm.
[0106] In another embodiment, the slurry has a solids content of
at least 40 wt %, based on total weight of the slurry mixture. Preferably,
the slurry has a solids content of at least 41 wt %, more preferably
at least 42 wt %, and most preferably at least 42.5 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. It is also preferred that the slurry
have a solids content of not greater than 60 wt %, based on total
weight of the slurry. Preferably, the slurry has a solids content
of not greater than 58 wt %, more preferably not greater than 56
wt %, and most preferably not greater than 54 wt % based on total
weight of the slurry.
[0107] In another embodiment of the invention, the molecular sieve
crystals, clay and binder are mixed together to form a slurry mixture
at a binder to molecular sieve weight ratio of at least 0.20:1.
Preferably, the molecular sieve crystals, clay and binder are mixed
together at a binder to molecular sieve weight ratio of at least
0.22:1 more preferably at least 0.24:1 and most preferably at
least 0.25:1. It is also preferred that the crystals, clay and binder
be mixed together at a binder to molecular sieve weight ratio of
not greater than 0.8:1 preferably not greater than 0.6:1.
[0108] In another embodiment, the molecular sieve crystals, clay
and binder are mixed together to form a slurry mixture at a binder
content of at least 5 wt %, preferably at least 8 wt %, and more
preferably at least 10 wt %, based on total weight of the mixture,
excluding liquid (e.g., water). It is also preferred in an embodiment
that the molecular sieve crystals, clay and binder are mixed together
to form a slurry mixture at a binder content of not greater than
30 wt %, preferably not greater than 25 wt %, based on total weight
of the mixture, excluding liquid (e.g., water).
[0109] In one embodiment of the invention, the slurry is aged prior
to drying. In this embodiment, aging means submitting the catalyst
formulation slurry to a mild thermal treatment, with or without
agitation and/or stirring and/or mixing. The duration of the thermal
treatment should be sufficient to allow the generation of the reactive
ionic species at a sufficient rate and in an amount sufficient to
allow the best attrition resistance properties in the catalyst particles.
[0110] Conditions of duration and temperature that achieve this
result include: maintaining the catalyst formulation slurry at a
temperature of from 0.degree. C. to 100.degree. C., preferably of
from 10.degree. C. to 90.degree. C., more preferably of from 15.degree.
C. to 80.degree. C., most preferably of from 20.degree. C. to 70.degree.
C. The duration of this mild thermal treatment can vary, depending
on various factors such as the type of inorganic oxide precursor,
the concentration of the inorganic precursor and the temperature.
The higher the temperature and the lower the concentration in inorganic
oxide precursor, the less time will be required to achieve the proper
level of aging of the catalyst formulation slurry according to the
invention. Periods of aging will typically be at least 2 hours,
preferably at least 4 hours, more preferably at least 5 hours, and
most preferably at least 6 hours. In a preferred embodiment, aging
of the catalyst formulation slurry is performed for not more than
150 hours, preferably not more than 120 hours, most preferably not
more than 100 hours. If aging takes place at a temperature of from
30.degree. C. to 50.degree. C., aging of the catalyst formulation
preferably takes place for a period of from 4 hours to 80 hours,
preferably of from 5 hours to 75 hours, more preferably of from
5.5 hours to 50 hours, most preferably of from 6 hours to 36 hours.
[0111] 3. Drying the Slurry
[0112] In one embodiment, the slurry of the molecular sieve, binder
and matrix materials is fed to a forming unit that produces a dried
molecular sieve catalyst composition. Non-limiting examples of forming
units include 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 (e.g., water) from the slurry.
[0113] When a spray dryer is used as the forming (or drying) unit,
typically, the slurry of the molecular sieve, matrix material and
binder, is co-fed to the drying unit with a drying gas. In one embodiment
the drying unit has an average inlet temperature ranging from 150.degree.
C. to 550.degree. C., and an average outlet temperature ranging
from 100.degree. C. to about 250.degree. C.
[0114] In one embodiment, the slurry is passed through a nozzle
distributing the slurry into small droplets, resembling an aerosol
spray, into a drying chamber. Atomization is achieved by forcing
the slurry through a single nozzle or multiple nozzles with a pressure
drop in the range of from 100 psia to 1000 psia (690 kPaa to 6895
kpaa). In another embodiment, the slurry is co-fed through a single
nozzle or multiple nozzles along with an atomization fluid such
as air, steam, flue gas, or any other suitable gas.
[0115] 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.
[0116] An example of a spray drying process that may be used to
dry the slurry is disclosed in U.S. Pat. No. 4946814 the description
of which is incorporated herein by reference.
[0117] In another embodiment of the invention, the slurry is dried
in a drying unit and then calcined. In one embodiment, the slurry
is dried to form a dried molecular sieve catalyst composition, and
the dried catalyst composition is calcined. In general, calcination
further hardens and/or activates the dried molecular sieve catalyst
composition. An acceptable 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.
[0118] The dried or formulated molecular sieve catalyst composition
can be calcined in many types of devices, including but not limited
to, 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.
[0119] In a preferred embodiment, the molecular sieve catalyst
composition is heated in nitrogen at a temperature of from about
600.degree. C. to about 700.degree. C. Heating is carried out for
a period of time typically from 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.
[0120] Other methods for calcining or 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.degree.
C.), and PCT WO 00/75072 published Dec. 14 2000 (heating to leave
an amount of template), which are all herein fully incorporated
by reference
[0121] IV. Methods of Using Catalyst
[0122] The molecular sieve catalyst product made according to this
invention is 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; hydrodecyclization; disproportionation
of, for example, toluene to make benzene and paraxylene; oligomerization
of, for example, straight and branched chain olefin(s); and dehydrocyclization.
[0123] 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.
[0124] 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.
[0125] 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.
[0126] 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.
[0127] 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.
[0128] 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.
[0129] 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.
[0130] 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.
[0131] 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 75 weight percent. In
one embodiment, the amount of ethylene and/or propylene produced
based on the total weight of hydrocarbon product produced is greater
than 65 weight percent, such as greater than 70 weight percent,
for example greater than 75 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 30 weight percent, such as greater than
35 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 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.
[0132] 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.
[0133] 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.
[0134] 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.
[0135] 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.
[0136] 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.
[0137] 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.
[0138] 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.
[0139] 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.
[0140] 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.
[0141] 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.
[0142] In such a process the reactor system conveniently includes
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.
[0143] 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.
[0144] 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.
[0145] 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.
[0146] 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.
[0147] 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).
[0148] 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.
[0149] 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 in
disclosed U.S. Pat. No. 6290916 (controlling moisture), which
is herein fully incorporated by reference.
[0150] The regenerated catalyst composition withdrawn from the
regeneration system, preferably from the catalyst cooler, is combined
with a fresh molecular sieve catalyst composition and/or re-circulated
molecular sieve catalyst composition and/or feedstock and/or fresh
gas or liquids, and returned to the riser reactor(s). In 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).
[0151] 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.
[0152] 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.
[0153] 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.
[0154] Non-limiting examples of these towers, columns, splitters
or trains used alone or in combination include one or more of a
demethanizer, preferably a high temperature demethanizer, a dethanizer,
a depropanizer, a wash tower often referred to as a caustic wash
tower and/or quench tower, absorbers, adsorbers, membranes, ethylene
splitter, propylene splitter and butene splitter.
[0155] Various recovery systems useful for recovering olefin(s),
such as ethylene, propylene and/or butene, are described in U.S.
Pat. No. 5960643 (secondary rich ethylene stream), U.S. Pat. Nos.
5019143 5452581 and 5082481 (membrane separations), U.S.
Pat. No. 5672197 (pressure dependent adsorbents), U.S. Pat. No.
6069288 (hydrogen removal), U.S. Pat. No. 5904880 (recovered
methanol to hydrogen and carbon dioxide in one step), U.S. Pat.
No. 5927063 (recovered methanol to gas turbine power plant), and
U.S. Pat. No. 6121504 (direct product quench), U.S. Pat. No. 6121503
(high purity olefins without superfractionation), and U.S. Pat.
No. 6293998 (pressure swing adsorption), which are all herein
fully incorporated by reference.
[0156] Other recovery systems that include purification systems,
for example for the purification of olefin(s), are described in
Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, Volume
9 John Wiley & Sons, 1996 pages 249-271 and 894-899 which
is herein incorporated by reference. Purification systems are also
described in for example, U.S. Pat. No. 6271428 (purification
of a diolefin hydrocarbon stream), U.S. Pat. No. 6293999 (separating
propylene from propane), and U.S. patent application Ser. No. 09/689363
filed Oct. 20 2000 (purge stream using hydrating catalyst), which
are herein incorporated by reference.
[0157] 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.
[0158] 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.
[0159] 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.
[0160] 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 fully herein incorporated
by reference.
[0161] 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.
[0162] 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.
[0163] 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.
[0164] 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.
[0165] 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.
[0166] 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.)
[0167] 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.
[0168] 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.
[0169] 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.
V. EXAMPLES OF METHODS OF MAKING CATALYST
Example 1
[0170] A slurry containing 45 wt % solid was prepared as follows:
(a) adding 154.5 g of aluminum chlorohydrate (ACH) MicroDry (loss
on ignition (LOI): 50.6%; from Reheis Inc., Berkeley Heights, N.J.)
to 675.6 g of deionized water and mixing at 700 rpm for 10 minutes
using a Yamato Model 2100 homogenizer (Yamato Scientific America
Inc., Orangeburg, N.Y.) to give a solution having pH of 4.02 at
23.7.degree. C.; (b) adding 349.9 g of molecular sieve 70V that
was dried at 120.degree. C. for 19 hrs (LOI of 17.69%) to the solution
from step (a) and mixing at 700 rpm for 15 minutes using the Yamato
homogenizer Model 2100 used in step (a), the slurry thus obtained
having a pH of 3.72 measured at 28.6.degree. C.; (c) adding 420
g of ASP Ultrafine kaolin clay (LOI: 15.31%, Engelhard Corporation,
Iselin, N.J.), while mixing at 700 rpm using the Yamato Model 2100
homogenizer for 15 minutes, the resulting slurry having a pH of
3.63 at 30.8.degree. C.; (d) passing the slurry from step (c) through
a bead mill, Eiger mini bead mill model M250 (Eiger Machinery, Inc.,
Grayslake, Ill.) having a ceramic chamber and using a high density
and high purity yttria-stabilized zirconia microbeads of 0.65 mm
at 3000 rpm for a single pass, the slurry produced having a pH of
3.48 measured at 23.degree. C. This slurry contained 45.35 wt %
solids, the solids being comprised of 40% SAPO-34 sieve, 10.6% Al.sub.2O.sub.3
and 49.4% clay.
[0171] 750 g of the slurry were then spray dried to produce a spray
dried catalyst using a Yamato DL-41 spray dryer (Yamato Scientific
America, Orangeburg, N.Y.). The spray dryer operated in a down spray
mode using a 1 mm atomization nozzle. The spray drying conditions
were: feed rate: 23-25 g/min; inlet temperature: 350.degree. C.;
atomization pressure: 1 bar; carrier gas (nitrogen) flow at 60%
of full setting. Spray dried products were collected in a cyclone,
and calcined in a muffle furnace at 650.degree. C. in air for 2
hours. The calcined samples were used for attrition and particle
size analysis. Attrition resistance of the calcined spray dry product
was determined using the ARI method. Surface and core clay to alumina
ratios were calculated using the EDS method described herein, with
the average core clay to alumina ratio being 2.4. Various results
are shown in Table 1.
Example 2
[0172] A slurry containing 45 wt % solid was prepared according
to the following procedure: (a) adding 231.7 g of aluminum chlorohydrate
(ACH) MicroDry (LOI: 50.6%; from Reheis Inc., Berkeley Heights,
N.J.) to 643.4 g of deionized water and mixing at 700 rpm for 10
minutes using a Yamato Model 2100 homogenizer (Yamato Scientific
America Inc., Orangeburg, N.Y.) to give a solution having pH of
3.79 at 24.6.degree. C.; (b) adding 350.0 g of molecular sieve 70V
dried at 180.degree. C. for 96 hrs (LOI: 17.71%) to the solution
from step (a) and mixing at 700 rpm for 15 minutes using the Yamato
homogenizer Model 2100 used in step (a), the slurry thus obtained
having a pH of 3.56 measured at 27.8.degree. C.; (c) adding 374.9
g of ASP Ultrafine kaolin clay (LOI: 15.31%, Engelhard Corporation,
Iselin, N.J.), while mixing at 700 rpm using the Yamato Model 2100
homogenizer for 15 minutes, the resulting slurry having a pH of
3.58 at 26.6.degree. C.; (d) passing the slurry from step (c) through
a bead mill, Eiger mini bead mill model M250 (Eiger Machinery, Inc.,
Grayslake, Ill.) having a ceramic chamber and using a high density
and high purity yttria-stabilized zirconia microbeads of 0.65 mm
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