Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to the pLeparation of
catalysts and supports therefor and more particularly
to the preparation of dense, hard, particulate
hydrocarbon conversion catalysts which comprise
catalytically active components such as crystalline
zeolites dispersed in an inorganic oxide matrix.
Hydrocarbon conversion catalysts such as fluid
catalytic cracking catalysts (FCC) are typically
manufactured by spray drying aqueous slurries,
catalytically active zeolites and matrix forming
components such as inorganic oxide gels and/or clays.
The resulting catalysts comprise small particles
(microspheres) in which the zeolite crystals are
dispersed throughout a matrix of relatively
catalytically inactive gel or sol binder and clay.
While the inorganic oxide matrix generally has little
catalytic activity, the matrix provides the physical
strength, size and porosity characteristics which are
required to obtain a commercially acceptable catalyst
composition. Furthermore~ since FCC catalysts are
produced and consumed in large quantities, the matrix
components should be relatively inexpensive.
It has been found that clay, particularly kaolin,
due to its reasonable price and availability,
constitutes a particularly suitable FCC catalyst
component. The prior art describes preparation of clay
based hydrocarbon conversion catalysts that have been
both thermally and chemically treated to obtain the
desired characteristics.
U.S. 2,485,6~6 describes the preparation of clay
based cracking catalyst wherein kaolin clay is heat
treated, reacted with acid to remove part of the
alumina component of the clay structure. Subsequently,
the acid treated clay is washed free oE soluble
~.
Z5
com?onents, and finally formed into cat~lyst particles.
U.S. 3,4G6,1?4 describes a method for preparing
catalysts which contain crystalline aluminosilicate
zeolites dispersed in an inorganic oxide matrix. The
matrix contains a clay component which is leached t~,
remove a portion of the alumina of the clay structure
as soluble aluminum saltsO Subsequently the aluminum
salts are precipitated as aluminum hydroxide on the
clay.
While th~ prior art describes ttle preparation of
hydrocarbon conversion catalysts which may comprise or
contain thermally/chemically treated clays, such as
calcined/acid leached kaolin, the refining industry
constantly requires low-cost catalysts which provide a
high degree of activity and selectivity combined with
substantial physical strength and attrition resistance.
It is therefore an object of the present invention
to provide improved catalysts, catalyst supports and
inorganic binders therefor.
It is another object to provide hydrocarbon
conversion catalysts wnich are hard, dense and
relatively inexpensive to manufacture.
It is yet another object to provide a zeolite
containing FCC catalyst which contains substantial
quantities of clay and/or clay derived matrix
components~
These and still further objects of the present
invention will become readily àpparent to one skilled
in the art from the following detailed description and
specific examples.
Broadly, my invention contemplates improved
catalytic compositions (including catalysts, catalyst
supports and inorganic binders) which contain an acid
treated metakaolin that is obtained by heating
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(calcining) kaolin and reactiny the resulting
metakaolin with sufficient acid to react wîth up to
about 25 mol percent of the alumina ~12O3) present
in the kaolin.
More speciically, I have found that dense, hard,
attrition resistant catalystic compositions may be
prepared by combining particulate catalyst components
with an acid treated metakaolin binder which is
obtained by heating (calcining) Icaolin to a t_mperature
of about 700 to 910C, and reacting the resulting
- metakaolin with sufficient acid to react with less than
I about 25 mol percent (and preferably for about 5 to 15
percent), of the structural alumina present in the
metakaolin. The compositions are formed into particles
which are then heat treated (calcined) at a te~perature
of about 300-800C to obtain hard attrition resistant
catalysts or catalyst supports.
While the process is particularly useful for tne
manufacture of zeolite containing FCC catalysts, my
invention also contemplates the preparation of catalyst
~I supports. These catalysts and supports comprise
I inorganic oxide gels and hydrogels such as clay,
alumina, silica, and silica-alumina dispersed in or
combined with a binder which comprises the acid treated
! 25 metakaolin described above.
; The acid treated metakaolin binder is obtained by
first thermally treating kaolin at a temperature of
from about 700 to 310C and preferably 800 to 900 for
a period of from about one-quarter to 8 hours, and
preferably one-quarter to 2 hours. The thermal
treatment or calcination step, which may be conducted
in the presence of air~ converts the raw kaolin into a
reactive form which is characterized as metakaolin.
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~2~ Z~
The metakaolin is then reacted with a quantity of
acid, such as hydrochloric or nitric acid or an acid
salt ~olution thereof such as aluminum chloride,
aluminum nitrate, zirconyl chloride, etc.
The quantity of acid reacted with the metakaolin i5
suf~icient to react with from about 2 to 25 and
preferably from 5 to 15 percent of the alumina
(A12O3) present in the metakaolin. The reaction in
the case of hydrochloric acid proceeds in accordance
~ 10 with the following overall reaction wherein metakaolin
; has the formula 2 SiO2.A12O3.
2 SiO .A1203 ~ 1 HCl~[2 Si2 (A123)o.g 0.6 3
To achieve the desired level o acid treatment, the
quantity of acid used is equal to or less than about
1.5 mols of acid per mol of alumina present in the
clay. I have ound that as little as 0.25 mols of acid
per mol of alumina is sufficient to provide the desired
acid reacted metakaolin product in less than about 24
hours. The most preferred level of acid is about 0.50
to 1.0 mol of acid per mol alumina in the metakaolin.
The desired quantity of acid is combined with
sufficient water to provide from about 2.0 to 20 parts
by weight acid solution per part by weight metakaolin~
The reaction with acid is conducted at a temperature of
from about 60 to 100C for a period of from about 1 to
24 hours. The resulting acid/métakaolin reaction
product contains from about 5 to 50 percent by weigh~
clay solids admixed with a liquid phase w~lich comprises
an aqueous solution of a complex acid/aluminum reaction
product which has a p~ from about 2.0 to 4Ø This
acidic aluminum reaction product solution together witb
,i
2~;
the acid leached metakaolin solids comprises the binder
or intermediate which is used in the preparation of the
catalysts and catalyst supports contemplated Aerein.
The ratio of the acid leached clay solid to complex
acidic aluminum solution i5 from about 8/1 to 9.8/l,
preferably 9/1 to 9.5/l parts by weight.
- To ob-tain a cracking catalyst which contains the
acid-metakaolin reaction product described above, the
acid-metakaolin reaction mixture is admixed with ~he
desired quantity oE catalytic components and/or gelled
with a base and formed into catalyst particles. The
added components typically comprise crystalline
zeolites such as type X, type Y (synthetic faujasite),
ZSM zeolite and/or other desired catalyst components
such as clay, alumina and silica-alumina hydrogels.
Subsequent to mixing the acid reacted metakaolin binder
slurry with the catalyst components, the soluble
aluminum components of the binder may be precipitated
as alumina by the addition of a base such as am~onium
hydroxide, or sodium hydroxide. It is also
contemplated that the acid reacted metakaolin reaction
product may be geiled without added catalyst
ingredients. In the alumina precipitating step,
sufficient base is added to raise the pH of the
reaction mixture to a level of about 5.0 to 9Ø
zeolite components may be initially mixed with the
acid-metakaolin binder slurry in the sodium form, or
the zeolites may be pre-exchanged with hydrogen and/or
stabilizing ions such as rare earth ions. Typical
exchanged/thermally treated zeolites comprise the
calcined rare earth exchanged type X and Y zeolites
(CREX and CREY) described inU.S. Re 28,629. In
addition, the zeolite component may comprise an
lz~ s
ultrastable type zeolite such a~ described in U.S.
3,293,192 and 3,449,070. It is also contemplated that
other catalytically active zeolites s~ch as ZSM 5, 11
and mordenite may be utilized alone or as blends with
the previously mentioned zeolites.
It is generally found that the fluid cracking
catalysts (F~C) prepared herein will comprise from
about 5.0 to 20 parts by weight acid meta-kaolin binder
(dry basis) and from about 9S to 80 parts by weight
solid components such as zeolite, alumina and clays,
(including the base gelled acid leached metakaolin
described herein). The binder is thoroughly admixed
with the solid components to obtain a spray drier feed
slurry which contains from about 20 to 60 percent by
weight solids. ~he ælurry is then spray dried using
conventional techniques to obtain microspheroidal FCC
catalyst particles which are then calcined at a
temperature of from about 300 to 800C. These calcined
particles may then be ion exchanged and/or washed to
remove undesirable soluble salts. Typically, the spray
dried product is contacted with solutions of ammonium
sulfate and/or rare earth chloxide ions.
In the event the acid treated metakaolin binders
contemplated herein are utilized to prepare suppor~s,
such as used in the preparation of hydroprocessing
catalysts, the acid meta~aolin reaction mixture
described above is gelled and/or admixed with the
desired solid components which typically comprise
zeolites, clay and inorganic oxide gels such as
alumina, silica and silica alumina ~including the base
gelled acid reacted metakaolin described herein)~ The
mixtures which comprise from about S to 40 parts acid
; treated kaolin binder and 95 to 60 parts inoryanic
~ ~7~
~z~
solids may be optionally reacted with a base to
precipitate alumina. The mixtures are then formed into
catalyst particles having the desired shape and size.
Typical forming techniques such as pilling, extruding
; 5 and granulating may be utilized. The resultant formed
particles are then subjected to calcination and a
temperature of from about 300 to 800C to o~tain hard
attrition resistant particles. The resulting calcined
particles may then be combined with catalytically
active metals such as selected from group VI and group
VIII of the Periodic Table to obtain catalysts useEul
for hydrocracking and hydrodesulfurization,
demetallization and so forth. In particular, it is
found that from about 1 to 20 weight percent non-noble
metals, such as cobalt, molybdenum, chromium and nickel
may be impregnated or placed upon the catalyst supports
contemplated herein using conventional techniques. In
; addition it is found that from about 0.1 to 2 weight
percent noble metals such as platinum, palladium and
rhodium may be combined with the supports to obtain
useful, catalytically active products.
Having described the basic aspects of the present
invention, the following examples are given to
illustrate the specific embodiments thereof.
~
A sample of kaolin clay having a particle size less
than 2.0 microns which possessed the initial chemical
composition 51.8 weight percent sio2, 42.2 percent
A12O3 was calcined for one half hour at 900C~ A
300 g sample of the calcined clay was then added to 3
liters of a solution which contained 102 ml of 37
percent HCl. The resulting slurry was refluxed at a
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~2~
temperature of 100C for 4 hoursO The reaction mixture
was then combined with 500 g o calcined, rare earth
exchanged type Y æeolite (CREY) which contained U.79
percent Na2O, and 2323 g (dry basis) raw kaolin. The
slurry was homogenized and subsequently spray dried.
The physical properties of the resulting catalyst
product are summarized in the Table.
~xample 2
9000 g sample o~ metakaolin, which was obtained
by calcining raw kaolin for one-half hour at 900C, was
admixed with 60 1 of an acid solution which contained
3042 ml of 37~ HCl. This mixture was then boiled under
reflux fGr seven and one-half hours. The slurry p~ was
adjusted to about 6.n by the addi~ion of 30 percent
ammonium hydroxide. The gelled reaction mixture was
then filtered, washed twice with 10 g~l of hot
deionized water, and reslurried in approximately 25 gal
of hot deionized water and recovered by filtration.
450 g D.B. (2074 9 as is) of this filter cake was
dispersed in a blender along with a slurry which
comprised 500 9 o the CREY described in Example 1 and
2175 g (dry basis), 2529 g as is of raw kaolin, and
approximately 8tO00 g of water. The mixture was
homogenized by recirculation through a centrifugal pump
and subsequently spray dried. The physical properties
of the catalyst obtained in this example are set forth
in the Table.
F. ample 3
A 1400 9 sample of the me~akaolin described in
Example 2 was combined with 4.2 1 of a solution which
contained 472.6 ml of 37% HCl dissolved in water. ThiS
mixture was boiled under reflux for 2 hour~. The
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.
~.Z~1~425
reaction mixture was then combined in the blender with
559.4 g CREY and 2120 g (dry basis) kaolin. The slurry
was then thoroughly mixed and spray dried to obtain
microspheroidal particles. The catalyst particles were
then calcined 2 hours at 540C. This sample had the
physical properties described in the Table.
Example 4
~ 6750 g sample of the metakaolin described in
Example 2 was added to 80 1 oE the solution which
contained 2286 ml of 37~ HCl. This mixture was then
boiled under reflux for 7 hours. 6 1 of the resulting
slurry was combined with a 2175 g (dry basis) sample of
raw kaolin and 434 g (dry basis) CREY. The slurry was
then mixed thoroughly, spray dried and calcined 2 hours
at 54~C. The physical propexties of the catalyst
obtained in this example is summariæed in the Table.
Example 5
i This example shows that a portion of the acid
leached clay slurry can be used to bind an ammonium
hydroxide gelled acid leached clay of the type
described in Example 2. 600 g of kaolin was calcined
one-half hour at 900C was added to 6.~ 1 solution
containing 204 ml 37.0% HCl and boiled under reflux for
approximately 4 hours. A blended slurry of 18Q g as is
CREY (0~79% Na2Oj and 2,215 g dry basis (10,889 g as
is) washed am~onium hydroxide gelled acid leached clay
obtained by the procedure set forth in Example 2 was
added. The slurry was thoroughly mixed and spray
dried. The properties of this catalyst sample are set
forth in the Table.
~10
.
S
Example_6
A 5,200 g dry basis sample of the washed ammonium
hydroxide ~elled acid leached metakaolin of Example 2
was slurried in a total of about 30,000 g of water and
spray dried. The properties are set forth in the Table.
~xample 7
450 9 of the calcined clay described in Example 1
was added to 4.5 1 solution containing 153.0 ml conc.
Hcl and boiled 4 hours under reflux. To this slurry
500 g of CREY and 2,529 g (raw) kaolin clay were added,
the slurry briefly homogenized and spray dried. ThiS
sample, of composition 15 percent acid treated clay,
12.5 percent C~EY, 72.5 percent kaolin clay, had the
proper~ies indicated in the Table.
.
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12~425
(1) ~ttrition Resistance measured after calcination
for 2 hours at looooF as determined by the method set
forth in U.S. 4,247,420.
(2) Microactivity volume ~ con~ersion as determined by
S use o~ the test as described by Henderson et al at
900F, 16 ~HSV, 3 c/o after an 8 hour, 1350F, 100
steam deactivation.
*ABD - Apparent Bulk Density (g/cc)
**CD - Compacted Density (g/cc)
The above Bxamples clearly indicate that valuable
catalyst compositions may be obtained usin~ the
teachings Oe my invention.
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