U.S. patent application number 09/260205 was filed with the patent office on 2002-04-25 for high zeolite content and attrition resistant catalyst, methods for preparing the same and catalyzed processes therewith.
Invention is credited to DEITZ, PHILIP S., ROBERIE, TERRY G., ZIEBARTH, MICHAEL S..
Application Number | 20020049133 09/260205 |
Document ID | / |
Family ID | 22988208 |
Filed Date | 2002-04-25 |
United States Patent
Application |
20020049133 |
Kind Code |
A1 |
ZIEBARTH, MICHAEL S. ; et
al. |
April 25, 2002 |
HIGH ZEOLITE CONTENT AND ATTRITION RESISTANT CATALYST, METHODS FOR
PREPARING THE SAME AND CATALYZED PROCESSES THEREWITH
Abstract
A catalyst composition suitable for reacting hydrocarbons, e.g.,
conversion processes such as fluidized catalytic cracking (FCC) of
hydrocarbons, comprises attrition resistant particulate having a
high level (30-85%) of stabilized zeolites having a constraint
index of 1 to 12. The stabilized zeolite is bound by a phosphorous
compound, alumina and optional binders wherein the alumina added to
make the catalyst is about 10% by weight or less and the molar
ratio of phosphorous (P.sub.2O.sub.5) to total alumina is
sufficient to obtain an attrition index of about 20 or less. The
composition can be used as a catalyst per se or as additive
catalyst to a conventional catalyst and is especially suitable for
enhancing yields of light olefins, and particularly ethylene,
produced during conversion processes.
Inventors: |
ZIEBARTH, MICHAEL S.;
(COLUMBIA, MD) ; ROBERIE, TERRY G.; (ELLICOTT
CITY, MD) ; DEITZ, PHILIP S.; (BALTIMORE,
MD) |
Correspondence
Address: |
CHARLES A CROSS
W R GRACE & CO CONN
7500 GRACE DRIVE
COLUMBIA
MD
210444098
|
Family ID: |
22988208 |
Appl. No.: |
09/260205 |
Filed: |
March 2, 1999 |
Current U.S.
Class: |
502/64 ; 502/67;
502/71; 502/77; 502/79 |
Current CPC
Class: |
B01J 37/0045 20130101;
B01J 2229/42 20130101; B01J 2229/26 20130101; B01J 29/40 20130101;
B01J 27/14 20130101 |
Class at
Publication: |
502/64 ; 502/67;
502/71; 502/77; 502/79 |
International
Class: |
B01J 029/064 |
Claims
What is claimed is:
1. A catalyst comprising (a) about 30 to about 85% by weight
zeolite having a constraint index of 1 to 12, (b) about 6-24% by
weight phosphorus, measured as P2O5, and (c) alumina, wherein added
alumina is present in an amount of less than about 10% and total
alumina is less than about 30%, by weight of the catalyst, said
catalyst further comprising a molar ratio of phosphorous to total
alumina sufficient to obtain a Davison attrition index for the
catalyst equal to or less than about 20.
2. A catalyst according to claim 1 comprising greater than about 60
to about 85% ZSM-5.
3. A catalyst according to claim 2 wherein the phosphorous
(P.sub.2O.sub.5) to total alumina molar ratio is at least 0.2 to
about 1.9.
4. A catalyst according to 3 wherein the catalyst has an attrition
index of about 10 or less.
5. A catalyst according to claim 2 wherein the added alumina (c) is
present in an amount ranging from about 5 to about 10% by
weight.
6. A catalyst according to claim 1 comprising about 30 to about 60%
ZSM-5.
7. A catalyst according to claim 6 wherein the molar ratio of
phosphorous to alumina is about 0.2 to about 1.0.
8. A catalyst according to claim 6 where the added alumina is
present in an amount ranging from about 3 to about 8% by
weight.
9. A catalyst according to claim 8 further comprising clay.
10. A catalyst according to claim 7 wherein the catalyst has an
attrition index of about 10 or less.
11. A process for preparing a catalyst comprising (a) preparing a
slurry comprising zeolite having a constraint index of 1 to 12,
phosphorus-containing compound and alumina, where the alumina is
less than about 10% by weight of the total weight of the zeolite,
phosphorus-containing compound, alumina, and any optional
components, and (b) spray drying and calcining the resulting slurry
to produce particulate having a DI attrition index equal to or less
than 20 and having total alumina content of less than about 30% by
weight.
12. A process according to claim 11 wherein the added alumina is
present in the slurry of (a) in a range of 3-8% by weight.
13. A process according to claim 11 wherein the zeolite is ZSM-5
and is present in the amount of about 30 to about 85% of the total
weight of ZSM-5, the phosphorus compound, alumina, and any other
optional components.
14. The product prepared by the process of claim 11.
15. A process for chemically and catalytically reacting a
hydrocarbon feed comprising contacting the feed at catalytic
reactive conditions with a catalyst comprising (a) about 30 to
about 85% by weight zeolite having a constraint index of 1 to 12,
(b) about 6-24% by weight phosphorus, measured as P.sub.2O.sub.5,
and (c) alumina, wherein added alumina is present in an amount of
less than about 10% and total alumina is less than about 30% by
weight of the catalyst, said catalyst further comprising a molar
ratio of phosphorous to total alumina sufficient to obtain an
attrition index for the catalyst equal to or less than about
20.
16. A process according to claim 15 wherein the catalyst comprises
greater than about 60 to about 85% ZSM-5.
17. A process according to claim 16 wherein the catalyst consists
essentially of (a), (b), and (c).
18. A process according to claim 15 wherein the catalyst comprises
about 60 to about 70% by weight ZSM-5.
19. A process according to claim 15 wherein the catalyst comprises
about 40-60% by weight ZSM-5.
20. A process according to claim 16 wherein the phosphorous to
total alumina ratio is about 0.2 to about 1.9 and the catalyst has
an attrition index of about 10 or less.
21. A process according to claim 18 wherein the phosphorous to
total alumina ratio is at least 0.45 to about 1.0 and the catalyst
has an attrition index of about 10 or less.
22. A process according to claim 19 wherein the phosphorus to total
alumina ratio is about 0.25 to about 0.7 and the catalyst has an
attrition index of about 10 or less.
23. A process according to claim 19 where the added alumina of (c)
is present in an amount ranging from about 3 to about 8% by
weight.
24. A process according to claim 23 wherein the additive further
comprises clay.
25. A process according to claim 15 further comprising recovering
ethylene and/or propylene from said process.
26. A process according to claim 15 wherein the process is
fluidized.
27. A process according to claim 26 wherein the process is
fluidized catalytic cracking of hydrocarbons.
28. A catalyst composition comprising a large pore aluminosilicate
and 0.1 to about 90 weight % additive comprising (a) about 30 to
about 85% by weight zeolite having a constraint index of 1 to 12,
(b) about 6-24% by weight phosphorus, measured as P.sub.2O.sub.5,
and (c) alumina, wherein added alumina is present in an amount of
less than about 10% and total alumina is less than about 30% by
weight of the total additive, said additive further having a molar
ratio of phosphorous to total alumina sufficient to obtain an
attrition index for the additive equal to or less than about
20.
29. A catalyst according to claim 28 wherein the additive comprises
greater than about 60 to about 85% ZSM-5.
30. A catalyst according to claim 29 wherein the additive consists
essentially of (a), (b), and (c).
31. A catalyst according to claim 28 wherein the additive comprises
about 30 to about 60% ZSM-5.
32. A catalyst according to claim 31 wherein the additive comprises
about 3 to about 8% by weight added alumina.
33. A catalyst according to claim 32 wherein the additive has an
attrition index of less than 10.
34. A catalyst according to claim 2 wherein the catalyst consists
of essentially (a), (b) and (c).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an improved catalyst
composition, its manufacture, and a process for reacting
hydrocarbon feed over the improved catalyst.
BACKGROUND OF THE INVENTION
[0002] Processes such as catalytic cracking operations are
commercially employed in the petroleum refining industry to produce
gasoline and fuel oils from hydrocarbon-containing feeds. These
cracking operations also result in the production of useful lower
olefins, e.g., C.sub.3-C.sub.5 olefins, and it has become
increasingly desirable to maximize the yield of such olefins from
conversion process operations in general. Endothermic catalytic
cracking of hydrocarbons is commonly practiced in fluid catalytic
cracking (FCC) processes.
[0003] Generally, FCC is commercially practiced in a cyclic mode.
During these operations, the hydrocarbon feedstock is contacted
with hot, active, solid particulate catalyst without added
hydrogen, for example, at pressures of up to about 50 psig and
temperatures up to about 650.degree. C. The catalyst is a powder
with particle sizes of about 20-200 microns in diameter and with an
average size of approximately 60-100 microns. The powder is
propelled upwardly through a riser reaction zone, fluidized and
thoroughly mixed with the hydrocarbon feed. The hydrocarbon feed is
cracked at the aforementioned high temperatures by the catalyst and
separated into various hydrocarbon products. As the hydrocarbon
feed is cracked in the presence of cracking catalyst to form
gasoline and olefins, undesirable carbonaceous residue known as
"coke" is deposited on the catalyst. The spent catalyst contains
coke as well as metals that are present in the feedstock. Catalysts
for FCC are typically large pore aluminosilicate compositions,
including faujasite or zeolite Y.
[0004] The coked catalyst particles are separated from the cracked
hydrocarbon products, and after stripping, are transferred into a
regenerator where the coke is burned off to regenerate the
catalyst. The regenerated catalyst then flows downwardly from the
regenerator to the base of the riser.
[0005] These cycles of cracking and regeneration at high flow rates
and temperatures have a tendency to physically break down the
catalyst into even smaller particles called "fines". These fines
have a diameter of up to 20 microns as compared to the average
diameter of the catalyst particle of about 60 to about 100 microns.
In determining the unit retention of catalysts, and accordingly
their cost efficiency, attrition resistance is a key parameter.
While the initial size of the particles can be controlled by
controlling the initial spray drying of the catalyst, if the
attrition resistance is poor, the catalytic cracking unit may
produce a large amount of the 0-20 micron fines which should not be
released into the atmosphere. Commercial catalytic cracking units
include cyclones and electrostatic precipitators to prevent fines
from becoming airborne. Those skilled in the art also appreciate
that excessive generation of catalyst fines increases the cost of
catalyst to the refiner. Excess fines can cause increased addition
of catalyst and dilution of catalytically viable particles.
[0006] Additionally, the catalyst particles cannot be too large in
diameter, or the particles may not be sufficiently fluidized.
Therefore, the catalysts are preferably maintained under 120 to 150
microns in diameter.
[0007] Particulated catalyst additives are also typically included
in the inventory of conventional large pore cracking catalysts for
FCC processes and are therefore subject to the same attrition
issues. These additives are very useful in enhancing the properties
of the resulting gasoline product as well as enhancing octane
numbers of the gasoline product. Such additives also are especially
suitable for enhancing yields of C.sub.3-C.sub.5 olefins. Those
olefins are useful in making ethers and alkylates which are in high
demand as octane enhances for gasoline, as well as useful in making
other chemical feedstocks.
[0008] Particulated catalysts and additives are prepared from a
number of compounds in addition to the primary active catalytic
species. For example, the catalyst compositions can comprise clay
and other inorganic oxides in addition to catalytically active
ZSM-5. Alumina is one particular inorganic oxide other than zeolite
that can be added. EP 256 875 reports that alumina in conjunction
with rare earth compounds improves hydrothermal stability and
selectivity of zeolite Y. Phosphorous also is added to "stabilize"
ZSM-5 containing catalysts. Additives sold as OlefinsMax.TM. by
Grace Davison is an example. Stabilization of a catalyst
composition means stabilizing the activity of the composition to
produce higher yields of light olefins when compared to a
composition which has not been stabilized by phosphorus. This
comparison is normally made after deactivation with steam.
[0009] U.S. Pat. No. 5,110,776 teaches a method for preparing FCC
catalyst comprising modifying the zeolite, e.g., ZSM-5, with
phosphorus. U.S. Pat. No. 5,126,298 teaches manufacture of an FCC
catalyst comprising zeolite, e.g., ZSM-5, clay, and phosphorus. See
also WO 98/41595 and U.S. Pat. No. 5,366,948. Phosphorus treatment
has been used on faujasite-based cracking catalysts for metals
passivation (see U.S. Pat. Nos. 4,970,183 and 4,430,199); reducing
coke make (see U.S. Pat. Nos. 4,567,152; 4,584,091; and 5,082,815);
increasing activity (see U.S. Pat. Nos. 4,454,241 and 4,498,975);
increasing gasoline selectivity (See U.S. Pat. No. 4,970,183); and
increasing steam stability (see U.S. Pat. Nos. 4,765,884 and
4,873,211).
[0010] In U.S. Pat. No. 3,758,403, use of large-pore cracking
catalyst with large amounts of ZSM-5 additive gives only modest
increase in light olefin production. A 100% increase in ZSM-5
content (from 5 wt. % ZSM-5 to 10 wt. % ZSM-5) increased the
propylene yield less than 20%, and decreased slightly the potential
gasoline yield (C.sub.530 gasoline plus alkylate).
[0011] When attempting to improve or enhance the catalytic activity
of these compositions, the amounts of the various components in a
catalyst or catalyst additive and the relevant effect these
components have on attrition have to be taken into account in order
to maximize attrition resistance. The importance of attrition
becomes increasingly acute when, for example, the ZSM-5 content of
a catalyst is increased to enhance the catalyst's activity. In
certain instances, increasing a catalyst's ZSM-5 content results in
the use of less binder and matrix, and as a result, "softer" or
more attrition prone particles can be created. Even though
particles having a ZSM-5 content up to 60% and an attrition index
less than 20 have been reported (U.S. Pat. No. 5,366,948), it has
been difficult to prepare catalysts and additives which contain a
great majority, i.e., greater than 60% of the active component over
the other components in the catalyst. For example, it would be
desirable to increase the amount of ZSM-5 to these high levels in
certain catalysts in order to produce a particle which is more
active in producing C.sub.3-C.sub.5 olefin.
[0012] Refiners, e.g., FCC refiners, DCC (Deep Catalytic Cracking)
refiners, as well as fixed fluidized bed refiners, would also find
it advantageous to enhance ethylene yields in order to maximize the
yield of valuable products from their refinery operations.
Additives or compositions comprising novel catalysts are potential
avenues for enhancing ethylene yields. Using those additives or
compositions, however, without materially affecting the yield of
other olefins can be difficult, especially in light of the other
concerns mentioned above with respect to attrition.
[0013] Therefore, with certain refiners, it would not only be
highly desirable to prepare a catalyst composition having a high
attrition resistance, it would also be desirable to provide
catalyst compositions having improved activity for ethylene
production as well as substantially maintain the compositions'
ability to produce other olefins. Those skilled in the art will
also appreciate that improved attrition resistance as well as
improved activity will translate into reduced catalyst makeup
rates.
[0014] Attrition resistance and high catalyst content would also
benefit processes used to react hydrocarbons other than hydrocarbon
cracking processes. Such processes include hydrocarbon
isomerization, dimerization and the like.
SUMMARY OF THE INVENTION
[0015] It is an object of the present invention to provide an
improved catalyst and an improved process using the same to
chemically react a hydrocarbon feedstock.
[0016] Specifically, the invention is an attrition resistant
zeolite catalyst composition which has high levels of stabilized
zeolite (30-85%) thereby effectively increasing the catalytic
effect in reactions involving hydrocarbon feedstock. It has been
unexpectedly discovered that by limiting the amount of alumina
added to the catalyst to 10% or less by weight of the catalyst and
further maintaining a phosphorous content between about 6 and 24%,
active catalysts containing up to 85% zeolite can be prepared.
Acceptable Davison Attrition Indices of 20 or less are achieved by
further selecting a phosphorus (as P.sub.2O.sub.5) to total alumina
molar ratio sufficient to maintain these attrition indices, while
also maintaining acceptable activity, e.g., olefin yields in FCC.
Suitable attrition properties are reflected by particles having
Davison index attrition numbers of 20 or lower, and preferably less
than 10.
[0017] The catalyst is especially effective for producing light
C.sub.3-C.sub.5 olefins (propylene and butylene) in hydrocarbon
cracking processes, such as those in a FCC Unit. The quantity of
light olefins produced in a FCC unit is strongly affected by the
amount of stabilized zeolite, e.g., ZSM-5 or ZSM-11, in the unit
and the unit conversion. Conversion is important since the amount
of light olefins produced tends to increase with unit conversion.
The advantage of a catalyst which contains a high level of active
zeolite is: 1) higher absolute amounts of active zeolite can be put
in the unit and/or 2) if the high content catalyst is used as an
additive catalyst at constant ZSM-5 or ZSM-11 level, a lower
quantity of additive is required and as a result there is less
dilution of the standard FCC catalyst, thereby allowing the unit to
operate at higher conversion.
[0018] The invention also provides an improved phosphorus
stabilized catalyst composition having a high content of active
components, and suitable attrition resistance, which is more
selective towards producing ethylene without significantly
affecting total olefin yields exhibited by conventional additives
in FCC units.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIGS. 1-3 illustrates light olefin yields from a FCC process
using several embodiments of the inventive catalyst (40% by weight
zeolite, 10% or less added alumina).
[0020] FIG. 4 illustrates the olefin yield of a FCC process using a
comparison catalyst comprising more than 10% alumina.
[0021] FIG. 5 illustrates the effects of added alumina content on
attrition resistance and propylene yield in a FCC catalyst.
[0022] FIG. 6 illustrates the percent change in olefin yield for
the invention relative to a conventional phosphorus stabilized
ZSM-5 catalyst. These results are taken at 70% conversion of the
hydrocarbon.
[0023] FIG. 7 illustrates total wt. % olefin yield as a function of
carbon number as compared against a conventional catalyst. These
results are shown for 70% conversion level of the hydrocarbon. This
figure as well as FIG. 6 also show the effect the invention has in
increasing ethylene yield.
[0024] FIG. 8 illustrates the invention comprising 80% ZSM-5 and
further illustrates how the molar ratio of phosphorous
(P.sub.2O.sub.5) and alumina affects propylene yield.
[0025] FIG. 9 illustrates the propylene yield of an embodiment
comprising 80% ZSM-5 compared to a conventional catalyst on a ZSM-5
weight basis and catalyst basis.
[0026] FIG. 10 illustrates the ethylene yield for an embodiment
comprising 80% ZSM-5 compared to a conventional catalyst on both a
catalyst and ZSM-5 weight basis.
DETAILED DESCRIPTION
[0027] The catalyst composition of this invention can be used, for
example, as the primary catalyst for a catalyzed reaction involving
hydrocarbon feedstock, as an additive to a fresh catalyst stream,
or as an additive to an existing catalyst inventory. The catalyst
is prepared from zeolite, alumina, phosphorous and optional
additional components.
[0028] Zeolite
[0029] Commercially used zeolites having a Constraint Index of 1-12
can be used for this invention. Details of the Constraint Index
test are provided in J, Catalysis, 67, 218-222 (1981) and in U.S.
Pat. No. 4,711,710 both of which are incorporated herein by
reference.
[0030] Conventional shape-selective zeolites useful for this
purpose are exemplified by intermediate pore (e.g., pore size of
from about 4 to about 7 Angstroms) zeolites. ZSM-5 (U.S. Pat. No.
3,702,886 and Re. 29,948) and ZSM-11 (U.S. Pat. No. 3,709,979) are
preferred. Methods for preparing these synthetic zeolites are well
known in the art.
[0031] Alumina
[0032] The alumina employed to make the invention is referred to
herein as "added alumina". The added alumina component of the
catalyst of the present invention therefore is defined herein as
alumina separately added to the slurry of starting components and
dispersed in the matrix of the catalyst. The alumina primarily
serves to act with phosphorous to form binder for the zeolite.
Added alumina does not include alumina present in the other
components of the additive, e.g., shape selective zeolite or any
clay used to prepare the additive. On the other hand, the term
"total alumina" as used herein refers to added alumina and alumina
present in the other components.
[0033] Suitable added alumina includes particulate alumina having a
total surface area, as measured by the method of Brunauer, Emmett
and Teller (BET) greater than 50 square meters per gram
(m.sup.2/g), preferably greater than 140 m.sup.2/g, for example,
from about 145 to 400 m.sup.2/g. Preferably the pore volume (BET)
of the particulate alumina will be greater than 0.35 cc/g. Such
alumina may comprise a minor amount of silica or other inorganic
oxides such as from about 0.1 to 15 weight percent, preferably from
about 0.1 to 6 weight percent silica, based on the weight of the
alumina component of the particles. The average particle size of
the alumina particles will generally be less than 10 microns,
preferably less than 3 microns. Preferably, the porous alumina will
be bulk alumina. The term "bulk" with reference to the alumina is
intended herein to designate a material which has been preformed
and placed in a physical form such that its surface area and porous
structure are stabilized so that when it is added to an inorganic
matrix containing residual soluble salts, the salts will not alter
the surface and pore characteristics measurably. Suitable
particulate aluminas include, but are not limited to, CP3 from
Alcoa and Catapal B from Condea Vista.
[0034] Other suitable sources of added alumina include colloidal
alumina or alumina sols, reactive alumina, aluminum chlorhydrol and
the like.
[0035] Phosphorus
[0036] Suitable phosphorus-containing compounds include phosphoric
acid (H.sub.3PO.sub.4), phosphorous acid (H.sub.3PO.sub.3), salts
of phosphoric acid, salts of phosphorous acid and mixtures thereof.
Ammonium salts such as monoammonium phosphate
(NH.sub.4)H.sub.2PO.sub.4, diammonium phosphate
(NH.sub.4).sub.2HPO.sub.3 monoammonium phosphite
(NH.sub.4)H.sub.2PO.sub.3, diammonium phosphite
(NH.sub.4).sub.2HPO.sub.3- , and mixtures thereof can also be used.
Other suitable phosphorous compounds are described in WO 98/41595,
the contents of which are incorporated herein by reference. Those
compounds include phosphines, phosphonic acid, phosphonates and the
like.
[0037] Optional Inorganic Oxide
[0038] The catalyst of this invention can include suitable
inorganic oxide matrices, such as non-zeolitic inorganic oxides,
including silica, silica-alumina, magnesia, boria, titania,
zirconia and mixtures thereof. The matrices may include one or more
of various known clays, such as montmorillonite, kaolin,
halloysite, bentonite, attapulgite, and the like. Most preferably,
the inorganic oxide is a clay as described in U.S. Pat. No.
3,867,308; U.S. Pat. No. 3,957,689 and U.S. Pat. No. 4,458,023. The
matrix component may be present in the catalyst in amounts ranging
from about 0 to about 60 weight percent. In certain embodiments,
clay is preferably from about 10 to about 50 wt. % of the total
catalyst composition.
[0039] It is also within the scope of the invention to incorporate
in the catalyst other materials such as other types of zeolites,
clays, carbon monoxide oxidation promoters, etc.
[0040] In general, the catalyst of this invention is manufactured
from a slurry of the components mentioned above. Suitable steps
comprise:
[0041] (a) preparing an aqueous slurry comprising zeolite having a
constraint index of 1 to 12, phosphorus-containing compound,
alumina and optionally, matrix comprising clay, etc., in amounts
which will result in a final dried product of step (b) having from
about 30-85% ZSM-5 or ZSM-11, no more than 10% by weight added
alumina, about 6-24% by weight phosphorous (as measured
P.sub.2O.sub.5) and no more than 30% by weight total alumina;
[0042] (b) spray drying the slurry of step (a) at a low pH, such as
a pH of less than about 3, preferably less than about 2; and
[0043] (c) recovering a spray-dried product having attrition
properties as evidenced by a Davison Index of 20 or less.
[0044] Methods for slurrying, milling, spray drying and recovering
particles suitable as a catalyst or additive are known in the art.
See U.S. Pat. No. 3, 444,097 as well as WO 98/41595 and U.S. Pat.
No. 5,366,948. The catalyst particle size should be in the range of
20-200 microns, and have an average particle size of 60-100
microns.
[0045] As indicated above, the amount of added alumina is 10% or
less by weight of the total components making up the particles,
with particles comprising 3-8% added alumina being most preferable
for FCC processes in terms of the resulting attrition properties
and olefin yield.
[0046] Molar Ratio of Phosphorous (P.sub.2O.sub.5)/Total
Alumina
[0047] The phosphorus/total alumina ratio, wherein the phosphorous
is measured as P.sub.2O.sub.5, is selected to obtain particles that
have an attrition index of about 20 or less. The ratio is also
selected to optimize olefin yield. This ratio is calculated using
standard techniques and is readily calculated from the amounts of
phosphorous added and total alumina present in the additive. The
examples below illustrate methods for obtaining the appropriate
ratios. As indicated earlier, total alumina includes added alumina
and alumina that may be present in other components, i.e.,
non-added alumina. Total alumina can be measured by bulk
analysis.
[0048] Ratios for obtaining suitable attrition resistance and
preferred activity is dependent upon the content of zeolite.
Generally, the higher the zeolite content, the larger the ratio
used. Generally suitable ratios, as well as preferred ratios to
obtain attrition indices of about 10 or less, are indicated below.
All other ranges of ratios within the suitable ranges are also
contemplated, e.g., 0.4 to 1.0, 0.25 to 0.7, etc.
1 Zeolite Content Suitable Ratio Preferred Ratio 30-60% zeolite 0.2
to 1.0 0.25 to 0.70 >60-85% zeolite 0.2 to 1.9 0.45 to 1.0
[0049] In general, the amount of phosphorus is selected to
sufficiently harden the particle without causing a loss in activity
in terms of olefin yield. The sufficient amount of phosphorus for
this purpose is from about 6 to about 24% of the total composition.
The amount of phosphorus can also be in all other ranges contained
within the range of 6-24%, e.g., 7-23%, 7-15%, etc.
[0050] As illustrated in FIG. 5, alumina affects olefin yield and
attrition, and it is shown that 10% or less added alumina provides
a balance of those properties. The ratios above are therefore a
reflection of the effects alumina and phosphorus have on the
resulting particles' properties.
[0051] The Davison Attrition Index is used to measure attrition of
the additive. To determine the Davison Attrition Index (DI) of the
catalysts, 7.0 cc of sample catalyst is screened to remove
particles in the 0 to 20 micron range. Those particles are then
contacted in a hardened steel jet cup having a precision bored
orifice through which an air jet of humidified (60%) air is passed
at 21 liter/minute for 1 hour. The DI is defined as the percent of
0-20 micron fines generated during the test relative to the amount
of >20 micron material initially present, i.e., the formula
below. 1 DI = 100 .times. wt % of 0-20 micron material formed
during test wt. of original 20 microns or greater material before
test
[0052] The lower the DI number, the more attrition resistant is the
catalyst. Commercially acceptable attrition resistance is indicated
by a DI of less than about 20, and preferably less than 10.
[0053] Hydrocarbon Conversion Processes
[0054] As discussed earlier, the invention is suitable for any
chemical reaction involving a hydrocarbon feed requiring catalyst
to facilitate the reaction. Such reactions include hydrocarbon
conversion processes involving molecular weight reduction of a
hydrocarbon, e.g., cracking. The invention can also be employed in
isomerization, dimerization, polymerization, hydration and
aromatization. The conditions of such processes are known in the
art. See U.S. Pat. No. 4,418,235 incorporated herein by reference.
Other applicable processes include upgradings of reformate,
transalkylation of aromatic hydrocarbons, alkylation of aromatics
and reduction in the pour point of fuel oils. For the purposes of
this invention, "hydrocarbon feedstock" not only includes organic
compounds containing carbon and hydrogen atoms, but also includes
hydrocarbons comprising oxygen, nitrogen and sulfur heteroatoms.
The feedstocks can be those having a wide range of boiling
temperatures, e.g., naphtha, distillate, vacuum gas oil and
residual oil. Such feedstocks also include those for making
heterocyclic compounds such as pyridine.
[0055] The invention is particularly suitable for fluidized
processes, e.g., in which catalyst attrition is a factor. The
invention is especially suitable for fluidized catalytic cracking
of a hydrocarbon feed to a mixture of products comprising gasoline,
alkylate, potential alkylate, and lower olefins, in the presence of
conventional cracking catalyst under catalytic cracking
conditions.
[0056] Typical hydrocarbons, i.e., feedstock, to such processes may
include in whole or in part, a gas oil (e.g., light, medium, or
heavy gas oil) having an initial boiling point above about
204.degree. C., a 50% point of at least about 260.degree. C., and
an end point of at least about 315.degree. C. The feedstock may
also include deep cut gas oil, vacuum gas oil, thermal oil,
residual oil, cycle stock, whole top crude, tar sand oil, shale
oil, synthetic fuel, heavy hydrocarbon fractions derived from the
destructive hydrogenation of coal, tar, pitches, asphalts,
hydrotreated feedstocks derived from any of the foregoing, and the
like. As will be recognized, the distillation of higher boiling
petroleum fractions above about 400.degree. C. must be carried out
under vacuum in order to avoid thermal cracking. The boiling
temperatures utilized herein are expressed in terms of convenience
of the boiling point corrected to atmospheric pressure. Resids or
deeper cut gas oils having an end point of up to about 700.degree.
C., even with high metals contents, can also be cracked using the
invention.
[0057] Catalytic cracking units are generally operated at
temperatures from about 400.degree. C. to about 650.degree. C.,
usually from about 450.degree. C. to about 600.degree. C., and
under reduced, atmospheric, or superatmospheric pressure, usually
from about atmospheric to about 5 atmospheres.
[0058] An FCC catalyst (primary or additive) is added to a FCC
process as a powder (20-200 microns) and generally is suspended in
the feed and propelled upward in a reaction zone. A relatively
heavy hydrocarbon feedstock, e.g., a gas oil, is admixed with a
catalyst to provide a fluidized suspension and cracked in an
elongated reactor, or riser, at elevated temperatures to provide a
mixture of lighter hydrocarbon products. The gaseous reaction
products and spent catalyst are discharged from the riser into a
separator, e.g., a cyclone unit, located within the upper section
of an enclosed stripping vessel, or stripper, with the reaction
products being conveyed to a product recovery zone and the spent
catalyst entering a dense catalyst bed within the lower section of
the stripper. After stripping entrained hydrocarbons from the spent
catalyst, the catalyst is conveyed to a catalyst regenerator unit.
The fluidizable catalyst is continuously circulated between the
riser and the regenerator and serves to transfer heat from the
latter to the former thereby supplying the thermal needs of the
cracking reaction which is endothermic.
[0059] Gas from the FCC main-column overhead receiver is compressed
and directed for further processing and separation to gasoline and
light olefins, with C.sub.3 and C.sub.4 product olefins being
directed to a petrochemical unit or to an alkylation unit to
produce a high octane gasoline by the reaction of an isoparaffin
(usually iso-butane) with one or more of the low molecular weight
olefins (usually propylene and butylene). Ethylene would be
recovered in a similar fashion and processed to additional
petrochemical units.
[0060] The FCC conversion conditions include a riser top
temperature of from about 500.degree. C. to about 595.degree. C.,
preferably from about 520.degree. C. to about 565.degree. C., and
most preferably from about 530.degree. C. to about 550.degree. C.;
catalyst/oil weight ratio of from about 3 to about 12, preferably
from about 4 to about 11, and most preferably from about 5 to about
10; and catalyst residence time of from about 0.5 to about 15
seconds, preferably from about 1 to about 10 seconds.
[0061] The catalyst of this invention is suitable as a catalyst
alone, or as an additive to cracking processes which employ
conventional large-pore molecular sieve component. The same applies
for processes other than cracking processes. Cracking catalysts are
large pore materials having pore openings of greater than about 7
Angstroms in effective diameter. Conventional large-pore molecular
sieve include zeolite X (U.S. Pat. No. 2,882,442); REX; zeolite Y
(U.S. Pat. No. 3,130,007); Ultrastable Y (USY) (U.S. Pat. No.
3,449,070); Rare Earth exchanged Y (REY) (U.S. Pat. No. 4,415,438);
Rare Earth exchanged USY (REUSY); Dealuminated Y (DeAl Y) (U.S.
Pat. Nos. 3,442,792 and 4,331,694); Ultrahydrophobic Y (UHPY) (U.S.
Pat. No. 4,401,556); and/or dealuminated silicon-eiriched zeolites,
e.g., LZ-210 (U.S. Pat. No. 4,678,765). Preferred are higher silica
forms of zeolite Y. ZSM-20 (U.S. Pat. No. 3,972,983); zeolite Beta
(U.S. Pat. No. 3,308,069); zeolite L (U.S. Pat. Nos. 3,216,789 and
4,701,315); and naturally occurring zeolites such as faujasite,
mordenite and the like may also be used (with all patents above in
parentheses incorporated herein by reference). These materials may
be subjected to conventional treatments, such as impregnation or
ion exchange with rare earths to increase stability. In current
commercial practice most cracking catalysts contain these
large-pore molecular sieves. The preferred molecular sieve of those
listed above is a zeolite Y, more preferably an REY, USY or REUSY.
Supernova.TM. D Catalyst from Grace Davison is a particularly
suitable large pore catalyst. Methods for making these zeolites are
known in the art.
[0062] Other large-pore crystalline molecular sieves include
pillared silicates and/or clays; aluminophosphates, e.g., ALP04-5,
ALPO.sub.4-8, VPI-5; silicoaluminophosphates, e.g., SAPO-5,
SAPO-37, SAPO-40, MCM-9; and other metal aluminophosphates.
Mesoporous crystalline material for use as the molecular sieve
includes MCM-41. These are variously described in U.S. Pat. Nos.
4,310,440; 4,440,871; 4,554,143; 4,567,029; 4,666,875; 4,742,033;
4,880,611; 4,859,314; 4,791,083; 5,102,643; and 5,098,684, each
incorporated herein by reference.
[0063] The large-pore molecular sieve catalyst component may also
include phosphorus or a phosphorus compound for any of the
functions generally attributed thereto, such as, for example,
attrition resistance, stability, metals passivation, and coke make
reduction.
[0064] As illustrated and described in more detail in the following
examples, it has been discovered that by using 10% or less by
weight of added alumina, one can prepare suitable attrition
resistant and active catalyst particles comprising high content,
i.e., 30-85%, zeolite. The inventive catalysts are also more
selective for ethylene, without substantially reducing the total
light olefin, e.g., propylene, yields from catalysts and additives
being used commercially, e.g., those containing about 25% ZSM-5. n
certain embodiments illustrated below, the olefin yield of the
invention as measured by propylene yield was equal (on a ZSM-5
basis) to that of conventional phosphorus stabilized ZSM-5
catalysts.
[0065] The activity of the invention on a ZSM-5 basis in a FCC
unit, relative to OlefinsMax additive, is in the range of about 40
to 100% in terms of propylene yields per the MAT test of ASTM 3907.
This activity is based on measurements at a constant conversion,
e.g., 70%, and as a catalyst additive to Grace's Supernova D
faujasite catalyst. Preferred catalysts are at least 50% as active,
and more preferably have activity in the range of 70-100% as active
as OlefinsMax. As illustrated in the examples below, the invention
can be as active, or two or three times more active than OlefinsMax
additive on a particle basis.
[0066] Indeed, it is believed that attrition resistant and
phosphorus stabilized active catalysts having such zeolite, e.g.,
ZSM-5 or ZSM-11, contents greater than 60% zeolite, and
particularly up to 85% by weight zeolite, have heretofore not been
made. It is believed that limiting the amount of alumina to 10% or
less and then optimizing the ratio of phosphorus to total alumina
allows one to make such catalysts. In addition to the benefits
already noted above, these high content additives allow one to
supplement existing catalyst inventories with zeolite catalysts
having the desired activity and attrition while at the same time
minimizing the amount of non-zeolite material (such as matrix) to
the catalyst inventory.
[0067] The following examples are provided for illustrative
purposes and are not intended to limit in any way the scope of the
claims appended hereto. Percentages described below are those by
weight (wt.). The ratio of P.sub.2O.sub.5/Al.sub.2O.sub.3 below
reflects the molar ratio of phosphorus to total alumina in the
catalyst. The abbreviations mentioned in the Examples below are
defined as follows.
2 BET Refers to the surface area measured by the Brunauer, Emmett
and Teller method of using nitrogen porosity to measure surface
area Atm Atmosphere Dl Davison Index ICP Inductively Coupled Plasma
LCO Light Cycle Oil HCO Heavy Cycle Oil m meter g gram
EXAMPLES
Example 1
[0068] Preparation of 40% ZSM-5/6.5% A.sub.2O.sub.3 Catalyst
[0069] An aqueous slurry containing 800 g of ZSM-5 (26:1 molar
ratio of SiO.sub.2 to Al.sub.2O.sub.3) (dry basis), 830 g clay (dry
basis), 130 g of Catapal B Al.sub.2O (dry basis) and 357 g of
concentrated H.sub.3PO.sub.4 were blended and mixed at a 45% solids
level. The slurry was then milled in a Drais mill and spray-dried
in a Bowen spray-drier to prepare Sample A. Two additional
preparations were made in the same manner, and were labeled Samples
B and C., where the P.sub.2O.sub.5 and clay levels were varied as
shown below:
[0070] A. 40% ZSM-5/6.5% Catapal B/i1% P.sub.2O.sub.5/42.5%
clay
[0071] B. 40% ZSM-5/6.5% Catapal B/12% P.sub.2O.sub.5/41.5%
clay
[0072] C. 40% ZSM-5/6.5% Catapal B/13.5% P.sub.2O.sub.5/40%
clay
[0073] The resulting materials were then calcined for 2
hours@1000.degree. F. and analyzed by ICP, T-plot surface area, and
DI attrition. The chemical and physical characterization data for
Samples A-C is shown in Table 1 below. The catalysts have DI
attrition numbers between 11 and 15.
3 TABLE 1 Sample A B C Formulation ZSM-5 40 40 40 P.sub.2O.sub.5 11
12 13.5 Al.sub.2O.sub.3 6.5 6.5 6.5 Clay 42.5 41.5 40 Total 100 100
100 Physical Properties 2 hours @ 1000.degree. F. Dl 13 15 11
Al.sub.2O.sub.3 26.14 25.9 25.87 P.sub.2O.sub.5 11.6 11.95 13.6
SiO.sub.2 57.16 56.53 57.39 P.sub.2O.sub.5/Al.sub.2O.sub.3 0.32
0.33 0.38 Total BET Surface 137 132 118 Area
Example 2
[0074] Microactivity Testing of Example 1 Catalysts
[0075] The calcined catalysts in Example 1 were deactivated by
steaming for 4 hours at 1500.degree. F./100% steam in a fluidized
bed steamer. The samples were then blended at a 2.5% additive level
with a steam deactivated Super Nova D (Davison commercial cracking
catalyst, 2.5% Re.sub.2O.sub.3 on catalyst). The admixture was used
to crack Feed A (Properties in Table 2) in a Microactivity Test
(MAT) as set forth in ASTM 3907.
4 TABLE 2 Feed A Feed B API Gravity @ 60.degree. F. 22.5 23.9
Aniline Point, .degree. F. 163 198 Sulfur, wt. % 2.59 0.733 Total
Nitrogen, wt. % 0.086 0.1 Basic Nitrogen, wt. % 0.034 0.042
Conradson Carbon, wt. % 0.25 0.33 ASTM D-2887 Simdist IBP 423 464 5
585 592 10 615 637 20 649 693 30 684 730 40 720 772 50 755 806 60
794 844 70 834 883 80 881 927 90 932 977 95 976 1018 FBP 1027
1152
[0076] The base case catalyst tested with these samples included:
1) steam deactivated Super Nova D.TM. (SND) 96% steam deactivated
SND blended with 4% steam deactivated conventional catalyst
additive available as OlefinsMax.TM. from Davison which contains
25% of a phosphorus stabilized ZSM-5. The OlefinsMax and SND
compositions were steam deactivated separately, each for 4 hours at
1500.degree. F./100% steam in a fluidized bed steamer.
[0077] The propylene yield (wt. % of feed) as a function of wt. %
conversion is shown in FIG. 1. The data shows that on an equal
ZSM-5 level (1% ZSM-5), the propylene yield of the catalyst
containing Example 1, Sample B, is equal to the sample containing
OlefinsMax.
Example 3
[0078] Preparation of 40% ZSM-5/8% Al.sub.2O.sub.3 Catalysts
[0079] Catalysts were prepared in the same manner as Example 1
except with the following compositions:
[0080] D. 40% ZSM-5/8% Catapal B/11.5% P.sub.2O.sub.5/40.5%
clay
[0081] E. 40% ZSM-5/8% Catapal B/13% P.sub.2O.sub.5/39% clay
[0082] F. 40% ZSM-5/8% Catapal B/14.5% P2Os/37.5% clay
[0083] The resulting samples were calcined for 2 hours@1000.degree.
F. and analyzed by ICP, T-plot surface area, and DI attrition. The
chemical and physical characterization data is shown in Table 3.
The catalysts have DI attrition numbers between 8 and 9.
5 TABLE 3 Sample D E F Formulation ZSM-5 40 40 40 P.sub.2O.sub.5
11.5 13 14.5 Al.sub.2O.sub.3 8 8 8 Clay 40.5 39 37.5 Total 100 100
100 Physical Properties 2 hours @ 1000.degree. F. Dl 9 8 8
Al.sub.2O.sub.3 27.57 27.64 26.81 P.sub.2O.sub.5 12.4 13.62 14.72
SiO.sub.2 57.57 56.24 57.8 P.sub.2O.sub.5/Al.sub.2O.sub.3 0.32 0.35
0.38 Total BET Surface 126 125 118 Area
Example 4
[0084] Microactivity Testing of Example 3 Catalysts
[0085] The calcined catalysts in Example 3 were deactivated by
steaming for 4 hours at 1500.degree. F./100% steam in a fluidized
bed steamer. The material was then blended at a 2.5% additive level
with a steam deactivated Super Nova.RTM. D cracking catalyst, 2.5%
Re.sub.2O.sub.3 on catalyst. The admixture was used to crack Feed A
in a Microactivity Test (MAT) as set forth in ASTM 3907. The base
case catalysts tested with these samples included: 1) steam
deactivated SND and 2) 96% steam deactivated SND blended with 4%
steam deactivated OlefinsMax. The OlefinsMax and SND catalysts were
steam deactivated separately, each for 4 hours at 1500.degree.
F./100% steam in a fluidized bed steamer.
[0086] The propylene yield (wt. % of feed) as a function of wt. %
conversion is shown in FIG. 2. The data shows that when compared on
an equal ZSM-5 basis (1% ZSM-5), the catalysts containing Sample D
and Sample E produce 85% of the propylene produced using OlefinsMax
additive. Sample F produces 80% of the propylene of OlefinsMax.
Example 5
[0087] Preparation of 40% ZSM-5/10% Al.sub.2O.sub.3 Catalyst
[0088] Catalysts were prepared in the same manner as Example 1
except with the following compositions:
[0089] G. 40% ZSM-5/10% Catapal B/13% P.sub.2O.sub.5/37% clay
[0090] H. 40% ZSM-5/10% Catapal B/14% P.sub.2O.sub.5/36% clay
[0091] I. 40% ZSM-5/10% Catapal B/i 5% P.sub.2O.sub.5/35% clay
[0092] The resulting materials were calcined for 2
hours@1000.degree. F. and analyzed by ICP, T-plot surface area, and
Davison index attrition. The chemical and physical characterization
data is shown in Table 4. The catalysts have DI attrition numbers
between 2 and 3.
6 TABLE 4 Sample G H I Formulation ZSM-5 40 40 40 P.sub.2O.sub.5 13
14 15 Al.sub.2O.sub.3 10 10 10 Clay 37 36 35 Total 100 100 100
Physical Properties 2 hours @ 1000.degree. F. Dl 2 2 3
P.sub.2O.sub.5/Al.sub.2O.sub.3 0.33 0.36 0.39 Total BET Surface 141
134 131 Area
Example 6
[0093] Microactivity Testing of Example 5 Catalysts
[0094] The calcined catalysts in Example 5 were deactivated by
steaming for 4 hours at 1500.degree. F./100% steam in a fluidized
bed steamer. The material was then blended at a 2.5% additive level
with a steam deactivated Super Nova.RTM. D cracking catalyst, 2.5%
Re.sub.2O.sub.3 on catalyst. The admixture was used to crack Feed A
in a Microactivity Test (MAT) as set forth in ASTM 3907. The base
case catalysts tested with these samples included: 1) steam
deactivated SND and 2) 96% steam deactivated SND blended with 4%
steam deactivated OlefinsMax additive. The OlefinsMax and SND
catalysts were steam deactivated separately, each for 4 hours at
1500.degree. F./100% steam in a fluidized bed steamer.
[0095] The propylene yield (wt. % of feed) as a function of wt. %
conversion is shown in FIG. 3. The data shows that when compared on
an equal ZSM-5 basis (1% ZSM-5), the catalysts containing Sample I
produces 75% of the propylene of OlefinsMax. Sample G and Sample H
produce 70% of the propylene of OlefinsMax.
Example 7
[0096] Preparation of 40% ZSM-5/20% Al.sub.2O.sub.3 Catalysts
(Comparison)
[0097] Catalysts were prepared in the same manner as Example 1
except with the following compositions:
[0098] J. 40% ZSM-5/20% Al.sub.2O.sub.3/20% P.sub.2O.sub.5/20%
clay
[0099] K. 40% ZSM-5/20% Al.sub.2O.sub.3/28% P.sub.2O.sub.5/12%
clay
[0100] L. 40% ZSM-5/20% A1.sub.2O.sub.3/35% P.sub.2O.sub.5/5%
clay
[0101] The resulting materials were calcined for 2 hours@
1000.degree. F. and analyzed by ICP, T-plot surface area, and DI
attrition. The chemical and physical characterization data is shown
in Table 5. The catalysts have DI attrition numbers between 5 and
9.
7 TABLE 5 Sample J K L Formulation ZSM-5 40 40 40 P.sub.2O.sub.5 20
28 35 Clay 20 12 5 Al.sub.2O.sub.3 20 20 20 Total 100 100 100
Physical Properties Dl 7 9 5 Al.sub.2O.sub.3 29.85 26.9 24.41
P.sub.2O.sub.5 20.53 27.97 34.26 SiO.sub.2 49.07 43.1 41.74
P.sub.2O.sub.5/Al.sub.2O.sub.3 ratio 0.49 0.75 1.01 Total BET
Surface 147 112 44 Area
Example 8
[0102] Microactivity Testing of Example 7 Comparison Catalysts
[0103] The calcined catalysts in Example 7 were deactivated by
steaming for 4 hours at 1500.degree. F./100% steam in a fluidized
bed steamer. The material was then blended at a 4% additive level
with a steam deactivated Super Nova.RTM. D cracking catalyst, 2.5%
Re.sub.2O.sub.3 on catalyst. The admixture was used to crack Feed A
in a Microactivity Test (MAT) as set forth in ASTM 3907. The base
case catalysts tested with these samples included: 1) steam
deactivated SND and 2) 93.6% steam deactivated SND blended with
6.4% steam deactivated OlefinsMax additive. The OlefinsMax and SND
catalysts were steam deactivated separately, each for 4 hours at
1500.degree. F./100% steam in a fluidized bed steamer.
[0104] The propylene yield (wt. % of feed) as a function of wt. %
conversion is shown in FIG. 4. While the additive has suitable
attrition resistance, the data shows that for these catalysts when
compared on an equal ZSM-5 basis (1.6% ZSM-5), were relatively less
active than those of Examples 1, 3, and 5 which contained added
alumina of 6.5, 8 and 10% by weight, respectively.
Example 9
[0105] Effect of Added Al.sub.2O.sub.3 on Propylene Yield
[0106] The data from Examples 1-8 illustrate a correlation between
the amount of added Al.sub.2O.sub.3 in the ZSM-5 (40% by weight)
catalyst and the relative propylene yield. The propylene yield is
measured as a percent of propylene produced relative to OlefinsMax
(equal ZSM-5 level) at 70% conversion. 2 Relative Propylene Yield =
100 % .times. [ Propylene ( Example ) - Propylene ( SND Base
Catalyst ) ] [ Propylene ( OlefinsMax ) - Propylene ( SND Base
Catalyst ) ]
[0107] The propylene yield data for each catalyst used in the
correlation was based on the best performance achieved for that
catalyst (optimized P.sub.2O.sub.5 level). The correlation is shown
in FIG. 5 which indicates that as the added Al.sub.2O.sub.3 in the
catalyst decreases, the propylene yield increases. At added
Al.sub.2O levels below 10%, the propylene yield increases
dramatically. At matrix Al.sub.2O.sub.3 levels between 3 and 8%,
the 40% ZSM-5 catalyst becomes equal in activity to OlefinsMax when
compared on an equivalent ZSM-5 basis.
[0108] Also shown in FIG. 5 are the DI attrition numbers for the
catalyst as a function of added Al1.sub.2O.sub.3. The data shows
that the attrition numbers tend to increase as the added
Al.sub.2O.sub.3 content decreases. However, it was discovered that
if the amount of alumina added to the slurry of starting components
for the catalyst was such that the final catalyst had less than 10%
by weight added alumina, acceptable propylene and low attrition
numbers were produced.
Example 10
[0109] Selectivity of Invention for Ethylene.
[0110] The calcined material in of Sample B (Example 1) was
deactivated by steaming for 4 hours at 1500.degree. F. in a
fluidized bed steamer. The material was then blended at a 10 (4%
ZSM-5), 20 (8% ZSM-5) and 32% (12.8% ZSM-5) additive level with an
equilibrium catalyst (ECAT). The admixture was then used to crack
Feed B (properties in Table 2) in a Microactivity (MAT) test as set
forth in ASTM 3907. OlefinsMax deactivated in the identical manner
and mixed with the same ECAT, was tested at the 16% (4% ZSM-5) and
32% (8% ZSM-5) additive levels as a comparison. The cracking
temperature used in this experiment was 1050.degree. F. instead of
the standard 980.degree. F. A sample containing 100% ECAT was also
tested as a control. The analysis of the ECAT appears below.
8 ECAT Analyses Al.sub.2O.sub.3, wt. % 44.4 Na.sub.2O, wt. % 0.37
RE.sub.2O.sub.3, wt. % 0.83 V, ppm 1892 Ni, ppm 2788 Unit Cell
Size, .ANG. 24.25 BET Surface Area, m.sup.2/g 171
[0111] The interpolated hydrocarbon yields at 70% conversion are
shown in Table 6. At equal ZSM-5 levels, the 40% additive increases
the amount of ethylene, shows relatively equal propylene and lower
C4-olefins as compared to OlefinsMax. An analysis of
C.sub.2-C.sub.9 olefins in the samples indicates that there was
some decrease in C olefins (FIGS. 6 and 7).
9TABLE 6 Constant Conversion Table Feed B; 1050.degree. F.
Conversion: 70% 16% 10% 32% 20% 32% Olefins Inven- Olefins Inven-
Inven- Additive ECAT Max tion Max tion tion ZSM-5, Wt. % 0 4 4 8 8
12.8 (Example 1, Sample B) Cat/oil 3.4 3.9 3 8 4.4 3.8 4.2 Hydrogen
0.18 0.17 0.18 0.17 0.18 0.17 Methane 0.82 0.81 082 0.81 0.87 0.84
Tot C1 + C2 2.47 3.73 4.02 4.73 5.18 5.80 C2= 0.99 2.22 2.48 3.20
3.55 4.19 Dry Gas 2.67 3.96 426 5.00 5.46 6.11 C3= 5.57 12.88 12.86
14.25 13.97 14.17 C3 0.93 1.73 1.89 2.09 2.40 2.66 Total C3's 656
14.61 14.75 16.29 16.39 16.83 Total C4= 7.04 10.78 10.39 11.19
10.68 10.70 iC4 3.34 4.52 4.63 4.38 5.10 4.58 nC4 0.68 093 098 103
1.21 1.24 Total C4s 11.13 16.23 1612 16.66 16.87 16.48 Light Gas
20.30 3457 3492 37.89 38.54 39.22 C5 + Gaso 46.78 3282 31.52 29.02
28.77 27.57 LCO 20.78 19.83 1964 19.71 20.18 1938 HCO 9.22 10.17
1032 10.26 9.82 10.58 Coke, wt. % 2.72 2.60 3 19 2.80 2.87 275
Example 11
[0112] very High (80%) ZSM-5 Content Catalysts
[0113] Catalysts having the composition indicated in Table 7 for
Samples M-P were prepared in the same manner as in Example 1. As
with the other examples, the resulting materials were calcined for
two hours at 1000.degree. F. and analyzed for ICP, T-plot surface
area, and DI attrition. This data is also reflected in Table 7,
below.
[0114] This example illustrates that very high ZSM-5 content
catalysts which are relatively attrition resistant can be made
according to the invention. The following Example 12 shows that the
activity of the catalyst can be optimized with suitable phosphorus
to total alumina ratio.
10TABLE 7 Physical and Chemical Properties of 80% ZSM-5 Catalyst
Sample M N 0 P ZSM-5 80 80 80 80 P.sub.2O.sub.5 11.6 12.5 12.9 13.2
Aluminum chlorhydrol 8.4 7.5 7.1 6.8 Total 100 100 100 100 Physical
Properties 2 hours @ 1000.degree. F. P.sub.2O.sub.5/Al.sub.2O.sub.3
0.67 0.78 0.83 0.88 Dl 21 5 3 3 Total BET Surface Area, m.sup.2/g
318 316 287 276
Example 12
[0115] Microactivity Testing for Very High ZSM-5 Content
Catalysts
[0116] The calcined catalysts in Example 11 were deactivated as
with the other examples by steaming for four hours at 1500.degree.
F./100% steam in a fluidized bed steamer. The samples were then
blended at a 2.5% additive level with a steam deactivated Super
Nova.RTM. D cracking catalysts, 2.5% Re.sub.2O.sub.3 on catalysts
and used to crack Feed A. The feed was tested as set forth in ASTM
3907. The activity results from these tests on a ZSM-5 basis (1%
ZSM-5) are in FIG. 8.
[0117] As illustrated by the propylene yields (as a weight
percentage of feed) in FIG. 8, the phosphorous to total alumina
ratio for the invention can be modified to obtain the desired
propylene yields from the very high ZSM-5 content catalyst, i.e.,
80% ZSM-5.
Example 13
[0118] Activity of High Zeolite Content Catalysts on Catalyst
Basis
[0119] A catalyst having the composition indicated in Table 8 below
was prepared in the manner described in Example 1 and was tested
for activity to illustrate the activity on a catalyst particle
basis. The previous examples illustrated the activity on a zeolite
basis.
11TABLE 8 Physical and Chemical Properties of 80% ZSM-5 Catalyst
Sample Q ZSM-5 79 P.sub.2O.sub.5 14 Al.sub.2O.sub.3 2 Clay 0
Aluminum chlorhydrol 5 Total 100 Physical Properties 2 hours @
1000.degree. F. Dl 9 Al.sub.2O.sub.3, wt. % 11.5 P.sub.2O.sub.5,
wt. % 14.23 SiO.sub.2, wt. % 76.06 P.sub.2O.sub.5/Total
Al.sub.2O.sub.3 0.89 Total BET Surface Area, m.sup.2/g 263
[0120] FIG. 9 illustrates that the high content catalyst (Catalyst
Q in Table 8) on an equal catalyst (=Cat) basis is more active than
the prior art OlefinMax (OMax) additive. As mentioned earlier,
suitable catalysts (Cat) having a higher activity on a catalyst
basis have been difficult to make because of increased attrition
occurring in additives containing more than 25% ZSM-5. The data
illustrated in FIG. 9 is found in Table 9 below. An equilibrium
catalyst (ECAT) was also tested as a comparison base catalyst. ECAT
is the same equilibrium catalyst referred to earlier in Example
10.
[0121] FIG. 10 illustrates the specific activity of Catalyst Q for
producing ethylene compared to the 25% ZSM-5 additive. FIG. 10
illustrates that the high zeolite content catalyst not only has
substantially the same activity for producing ethylene on an equal
ZSM-5 (=ZSM) basis, but also has higher activity for ethylene on a
catalyst basis. These figures indicate that the high zeolite
content catalysts offer significant advantages for refiners seeking
to enhance ethylene yields.
12TABLE 9 Interpolated Yields from Catalyst Q Compared to
OlefinsMax on an Equal ZSM-5 and Equal Catalyst Basis Additives
Blended with ECAT at a 1% ZSM-5 level and a 4% Additive level;
SIHGO Gas Oil Catalyst Q Catalyst Q Conversion 70 ECAT OMAX (=ZSM)
(=CAT) Catalyst to Oil Ratio 4.49 4.35 4.44 4.16 Hydrogen 0.30 0.28
0.30 0.27 Methane 0.74 0.65 0.67 0.64 Ethylene 0.74 1.18 1.05 1.65
Tot C1 + C2 2.08 2.37 2.27 2.84 Dry Gas 2.37 2.65 2.57 3.11
Propylene 4.27 8.77 7.69 9.84 Propane 0.95 1.54 1.39 1.96 Total
C3's 5.22 10.31 8.98 11.80 1-Butene 1.28 1.63 1.50 1.64 Isobutylene
1.35 254 2.15 3.15 Trans-2-butene 1.65 2.10 1.96 2.12 Cis-2-butene
1.30 1.66 1.54 1.66 Total C4 = s 5.58 7.93 7.15 8.58 IsoButane 3.92
579 5.34 6.50 n-C4 0.82 1.02 0.96 1.21 Total C4s 10.31 14.73 13.46
16.28 Wet Gas 17.91 27.69 25.02 31.19 Gasoline 47.10 37.07 39.34
33.18 LCO 24.88 24.49 24.65 24.18 Bottoms 512 5.51 5.35 5.82 Coke
4.98 5.24 5.64 5.62
Example 14
[0122] Attrition and Activity Versus Molar Ratio of Phosphorus
(P.sub.2O.sub.5) and Total Alumina
[0123] Additives were prepared according to the invention using the
amounts of components indicated in Tables 10, 11, and 12. The
additives were prepared using the preparation methods described in
Example 1. As indicated in the tables, the molar ratio of
phosphorus (measured as P.sub.2O.sub.5) to total alumina was varied
for additives comprising 60, 70 and about 80% ZSM-5.
[0124] Catalyst R-W comprising the components indicated in Table 10
below comprise 60% by weight ZSM-5 and either 7% added alumina or
9% added alumina. Catalysts X-Z are comparison catalysts which
comprise more than 10% added alumina, i.e., 15% by weight added
alumina. The propylene yields for each of the above-mentioned
catalysts were measured. These results show that even though the
comparison catalysts had suitable DI attrition numbers, they did
not benefit from the invention's higher activities. These examples
illustrate the advantage of catalysts comprising about 10% or less
added alumina.
[0125] Catalysts AA-CC of Table 11 comprise 70% by weight ZSM-5.
These examples illustrate modifying the molar ratio of phosphorus
to total alumina in order to obtain suitable Dl attrition, as well
as maximize activity for the particle.
[0126] Catalysts DD-GG are additional examples of the invention
comprising about 75-80% by weight ZSM-5.
13 TABLE 10 Invention Invention Comparison Formulation R S T U V W
X Y Z ZSM-5 60 60 60 60 60 60 60 60 60 P.sub.2O.sub.5 12 14.5 16 14
16 18 15 18 21 Al.sub.2O.sub.3 2 2 2 2 2 2 2 2 2 Clay 21 18.5 17 17
15 13 10 7 4 Aluminum chlorhydrol 5 5 5 7 7 7 13 13 13 Total 100
100 100 100 100 100 100 100 100 Physical Properties 2 hrs @
100.degree. F. DI 11 8 4 10 4 7 7 9 2 Al.sub.2O.sub.3, wt % 18.73
17.80 17.13 19.48 18.62 17.79 21.49 20.82 20.07 P.sub.2O.sub.5, wt
% 12.10 14.67 16.20 14.25 16.14 18.08 15.60 18.08 21.78 SiO.sub.2,
wt % 67.41 65.86 65.11 64.78 63.85 62.71 60.31 61.03 57.96
P.sub.2O.sub.5/Total Al.sub.2O.sub.3 0.46 0.59 0.68 1.10 1.26 1.42
0.52 0.62 0.78 SA, m.sup.2/g 219 199 174 224 200 177 238 237 243
Propylene Yield Relative to 76% 86% 62% 45% 68% 45% 24% 21% 24%
Olefins Max Compared on an Equal ZSM-5 Level
[0127]
14 TABLE 11 AA BB CC Formulation ZSM-5 70 70 70 P.sub.2O.sub.5 9 11
13 Al.sub.2O.sub.3 2 2 2 Clay 13 11 9 Aluminum chlorhydrol 6 6 6
Total 100 100 100 Physical Properties 2 hrs @ 1000F. Dl 40 16 7
Al.sub.2O.sub.3, wt % 21.34 19.02 17.93 P.sub.2O.sub.5, wt % 11.51
11.79 14.22 SiO.sub.2, wt % 65.83 67.46 80.88 Molar
P.sub.2O.sub.5/Total Al.sub.2O.sub.3 0.39 0.45 0.57 SA, m.sup.2/g
217 238 234 Propylene Yield Relative to 48% 63% 63% Olefins Max
Compared on an Equal ZSM-5 Level
[0128]
15 TABLE 12 DD EE FF GG Formulation ZSM-5 79.5 78 76.5 79
P.sub.2O.sub.5 12.5 14 15.5 14 Al.sub.2O.sub.3 3 3 3 2 Aluminum
chlorhydrol 5 5 5 5 Total 100 100 100 100 Physical Properties 2 @
1000 Dl 0 3 0 0 Al.sub.2O.sub.3, wt % 14.42 13.38 12.64 11.42
P.sub.2O.sub.5, wt % 13.96 14.53 15.54 14.67 SiO.sub.2, wt % 67.88
71.05 67.42 69.6 Molar P.sub.2O.sub.5/Total Al.sub.2O.sub.3 0.70
0.78 0.88 0.92 SA, m.sup.2/g 246 248 221 243 Propylene Yield
Relative to -- -- -- 100% Olefins Max Compared on an Equal ZSM-5
Level
Example 15
[0129] Attrition of Prior Art Additive
[0130] An example of a catalyst described in WO 98/41595 was
reproduced to determine its attrition.
[0131] To an aqueous slurry containing 1,497 g of ZSM-5 (26:1 molar
ratio of SiO.sub.2 to Al.sub.2O.sub.3) (dry basis) and 5,533 g of
water was added 1,122 g of clay (dry basis), 449 g of phosphoric
acid (86.2% H.sub.3PO.sub.4), 823 g of an aqueous alumina slurry
containing 12.4% by weight alumina (Condea) with 0.2 parts formic
acid added per part alumina, and 2,498 g of a 40% Nalco silica sol.
The resulting slurry was mixed until smooth and homogeneous. The
slurry was then spray dried in a Bowen spray-drier at an outlet
temperature of 350.degree. F. The resulting spray dried product was
then air calcined for two hours at 1000.degree. F. and analyzed for
ICP, t-plot surface area and DI attrition.
16 Physical Properties 2 hrs. @ 1000.degree. F. Dl 61
Al.sub.2O.sub.3, wt. % 17 05 P.sub.2O.sub.3, wt. % 7.33 SiO.sub.2,
wt. % 73.74 Total Surface Area 152
[0132] The results above indicate the difficulty in obtaining
suitable attrition resistant materials when preparing zeolite
content catalysts.
* * * * *