Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to the preparation of
catalytic compositions, more particularly to the
preparation of dense, hard, particulate hydrocarbon
conversion catalysts which comprise acid reacted
metakaolin.
Hydrocarbon conversion catalysts such as fluid
catalytic cracking catalysts (FCC) are typically
manufactured by spray drying aqueous slurries of
catalytically active zeolites and matrix forming
components such as inorganic oxide gels and/or clays.
The resulting ca*alysts comprise small particles
(microspherec) in which the zeolite crystals are
dispersed throughout a matrix of relatively
catalytically inactive gel or sol binder and clay.
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
thermally and/or chemically treated to obtain the
desired characteristics.
U.S. 2,485,626 describec the preparation of clay
based cracking catalyst wherein kaolin clay is heat
treated and reacted with acid to remove alumina from
the clay structure. The acid reacted clay is washed
Pree of soluble components, and formed into catalyst
particles.
U.S. 3,406,124 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 with
acid to remove a portion of the alumina of the clay
~ ,,'
~2~Z~;~.2
struc~ure as solub~e aluminum salts. The soluble
aluminum salts are precipitated as aluminum hydroxide.
While the prior art describes the preparation of
hydrocarbon conversion catalysts which may comprise or
contain thermally/chemically treated clays, such as
calcined/acid leached kaolin, the refining industry is
constantly searching for low-cost catalysts which
provide an acceptable 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 catalytic compositions.
It is anothèr object to provide hydrocarbon
conversion catalysts which are hard, dense and
relatively ine~pensive to manufacture.
It is yet another object to provide highly active,
cost effective FCC catalysts which comprise
chemically/thermally modified kaolin that may be used
in the catalytic cracking of a wide variety of
hydrocarbon feestocks.
It is a still further object to provide inexpensive
clay-based FCC catalysts which may be blended with more
expensive zeolite containing FCC catalyst and used to
process feedstocks that are heavily contaminated with
metals, sulfur and/or nitrogen compounds.
These and still further objects of the present
invention will become readily apparent to one skilled
in the art ~rom the following detailed description and
specific examples.
Broadly, my invention contemplates improved
catalytic compositions (including catalysts and
catalyst supports) which contain an acid treated
metakaolin that is obtained by heating (calcininy)
kaolin and reacting the resulting metakaolin with
--3--
~zc~z~
sufficient acid to react with up to about 25 mol
percent of the alumina (A12O3) present in the
kaolin.
More specifically I have found that dense, hard,
attrition resistant catalytic compositions may be
prepared from acid treated metakaolin which is obtained
by heating (calcining) kaolin to a temperature of about
700 to 910C, and reacting the resulting metakaolin
with sufficient acid to react with less than about 25
mol percent, and preferably from about 5 to 15 percent,
of the structural alumina present in the metakaolin.
The compositions are formed into particles which may be
then heat treated (calcined) at a temperature of about
300-800C to obtain hard attrition resistant catalysts
or catalyst supports.
The acid treated metakaolin catalysts described
herein have substantially higher activity than the acid
leached clays described in the literature. This low
cost, high activity acid treated metakaolin provides a
significant portion of the total cracking activity of
the c~talyst. Catalysts with substantial matrix
cracking activity are highly desirable for the cracking
o high boiling feedstocks, and for the production of
high octane gasoline.
While the process is particularly useful for the
manufacture of FCC catalysts which may be used to
catalytically crack a wide variety of hydrocarbon
feedstocks my invention also contemplates the
preparation of catalyst supports which are used in the
manufacture of hydroprocessing catalysts such as
hydrocracking, hydrodesulfurization and
hydrodemetallization catalysts.
The reaction metakaolin is obtained by thermally
treating kaolin at a temperature of from about 700 to
910C, and preferably ~00 to gnoo, fv~ a period yreater
than about one-quarter hour, and preferably one~quarter
to 8 hours, and more preferhly from one~half 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.
The reactive metakaolln is then reacted with an
acid, such as hydrochloric or nitric acid or an acid
salt solution thereof such as aluminum chloride,
aluminum nitrate, zirconyl chloride, etc~
The quantity of acid reacted with the metakaolin is
sufficient to react with from about 2 to 25 and
preferably from 5 to 15 mol percent of the alumina
(A12O3) present in the metakaolinO The reaction in
the case of hydrochloric acid typically proceeds in
accordance with the followin~ overall reaction wherein
metakaolin has the formula 2 Sio2.Al~O3.
2 SiO Al O + 1 HCl ~ ~2 SiO2.(A12O3)0.9Ho.~] 3
20 HCl
To achieve the desired level of acid treatment, the
quantity of acid used is equal to or less than about
1.5 mols oE acid per mol of alumina present in the
clay. I have found that as little as 0.25 mols of acid
25 per mol of alumina is sufficient to provide the desired
acLd reacted metakaolin product in less than about 24
hours. The most preEerred level of acid is about 0.50
to 1.0 mol of acid per mol alumina in the metakaolin.
The desired ~uantity of acid is combined with
30 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
Erom about 60 to 100~C for a period of from about 1 to
24 hours. The resulting acid/metakaolin reaction
product contains from about S to 50 percent by weight
clay solids admixed with a liquid phase which comprises
an aqueous solution o a complex acid/aluminum reaction
product which has a pH from about 2.0 to 4Ø This
acidic aluminum reaction product solution together with
the acid leached metakaolin solids comprises the binder
or intermediate whlch is used in the preparation of the
catalysts and catalyst supports contemplated herein.
The ratio of the acid leached clay solid to complex
acidic aluminum species in solution is from about 8/1
to 9.8/1, preferably 9/1 to 9.5/1 parts by weight.
To obtain a cracking catalyst which comprises the
acid-metakaolin reaction product described above, the
acid-metakaolin reaction mixture is spray dried or
otherwise formed into particles of desired shape and
size. It is also contemplated that the acid reacted
metakaolin reaction product may be reaated with
sufficient base to raise the pH of the reac~ion mixture
to a level of about 5.0 to 9.0 in order ~o precipitate
the soluble aluminum component prior to forming~
Furthermore, the aLumina components may be
auto-precipitated by holding the reactlon ~ixture fa~ a
period in excess of about 3 haurs at a temperature a
60 to 100C using high clay solids levels.
To prepare fluid cracking cataly~ts (FCC) the acid
rected metakaolin i~ mixed with water to obtain a spray
drier feed slurry which contains from about 20 to 60
percent by weight solidsO The slurry is then spray
dried using conventional techniques to obtain
microspheroidal FCC catalyst partlcle~ which are then
calcined either prior to or during use at a temperature
of ~rom about 300 to 800C. The~e calcined particles
-6-
:~2(~
may then be ion exchanged and/or washed to remove
undesirable soluble salts. The FCC catalysts o the
present invention possess a surface area of abou~ 200
to 600 m ~g~ a denslty of about 0.50 to 0.30 g/cc,
and a microactivity of about 40 to 80 volume percent
conversion after steaming at 1350F with 100 percent
steam for 8 hours (ASTM method D3907). Furthermore,
the catalysts possess a high degree of attrition
resistance as determined by the methods disclosed in
U~S. 4,247,~20.
The FCC catalysts of this invention are
particularly cost effective for the catalytic cracking
of residual hydrocracking feedstocks which contain high
levels of contaminating metals (Ni ~ V), sulfur and/or
nitrogen. The catalysts may be blended with standard
zeolite promoted cracking catalyst of the type
described in U.S. 3,867,308 and 3,957,689. It is
anticipated that physical blends which contain from
about 20 to 80 weight percent zeolite FCC in admixture
with the ~CC catalysts of this invention will be
effective for processing residual ~eeds that cause
rapld deactivation of conventional catalysts by metals
contamination.
In the event the acid treate~ metakaolin
contemplated herein is utilized to prepare supports,
such as used in the preparation o hydroprocessing
catalysts, the acid metakaolin reaction mixture
described above is mixed with mlnor amounts of water
and ~ormed into extrudates, pills or granules using
conventional forminy techni~ues~ ~t is also
conte~plated that the acid reacted metakaolin may be
reacted with a base ~o precipitate alumina priox to
orming the catalyst support~. The re~ultant formed
partlcles are then sub~eated to aalcinati.on either
--7--
~2~Q;~
prior to or during use at a temperature of from about
300 to 800~C to obtain hard attrition resistant
particles. The resulting calcined particles may then
be cornbined with catalytically active metals such as
selected from group VI ancl group VIII of the Periodic
Table to obtain catalysts useful for hydrocracking and
hydrodesulfurization, demetallization and so forth. In
particular, it is anticipated 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
contemplated that from about O.I to 2 weight percent
noble metals such as platinum, palladiu~ and rhodium
may be combined with the supports to obtain useful,
catalytically active products.
Havlng described the basic ~spects of the present
invention, the followlng examples are given to
illustrate the specific embodiments thereof. The
catalytic activity, expressed as volume percent
conversion, of the cracking catalysts de~aribed in the
examples was determined using the procedure of
ASTM-D3907.
Example 1
This example describes preparation of an acid
reacted metalcaolin catalytic cracking catalyst of the
present invention. 67.5 ml of 37~0% ~lCl was diluted to
about 600 ml total volume and 200 g of metakaolin,
which had been prepared by calcining Icaolin about 50
minutes at 840C in a rotary calciner r was added. The
resulting slurry ~a refluxed for 8 hours. The product
was filtered, washed free of Cl , dried in a forced
-8-
1 Z~!Z~ ~
draft oven and groundO This sample had a surface area
of 284 m /gl an alumina content of 38~8% and a
catalytic microactivity of 40~ 7 after an 8 hour, 732C,
100~ steam deactivation.
Example 2
This example uses the same HCl level and
concentration as well as the same metakaolin set Eorth
in Example 1, and demonstrates that a high ~urface area
catalyst is produced when the acid reaction period is
extended to 60 hours. 13.5 ml 37.0% HCl was diluted ~o
12G ml, 40 9 of the metakaolin desc~ibed in Example 1
was added, and the resulting slurry was aged at 107C
in a sealed teflon bottle for 60 hours. The slurry was
then filtered, washed Cl free and oven dried at
15 121~Co The resulting product had a surface area o~
436 m /g, an alumina content of 36.6% and a
microactivity o 39~9 after the steam deactivation.
Example 3
This example indicate~ that higher levels of acid
than used in Examples 1 and 2 also given a high su~face
area catalyst. 59,0 ml of 37.0% HCl was dlluted to 300
ml, and ac~ded 100 g of the same metaka~lln as in
Example 1. The resulting slurry was refluxed about 8
hours, filtered, washed Cl free and oven dried.
This sample had a surface area of 277 m /g~ an
alumina content of 43.8% and a catalytic activity of
34.8% after the steam deactivation.
Example 4
This example and examples 5-7 illustrate that
undesirably hi~h levels of HCl red~ce the alumin~
content of the catalyst produat and ~edua2 its
_9~
~t~
activity~ 202~5 ml 37.0~ EICl diluted to 750 ml, and
200 g of the same metakaolin of Example 1 was added. A
part of the resulting slurry was removed after one-half
hour a~ reflux, filtered, washed Cl free and oven
dried. This sample had a surace area o~ 157 m2/g,
an alumina content of 33.3~ and an activity of 10.7
after steam deactivation.
Exam~le 5
This sample was prepared by the ame procedure as
Example 4, except that 270 ml 37~ HCl wa~ used. The
resulting cataly6t product had a sur~ace area of 232
m /g, an alumina content of 23.64 and an activity of
13~4 after the steam deactivation.
Example 6
This ~ample was prepared by the same procedure as
Example 4, except that 337.5 ml 37~a~ HCl was used,
Thls product had a ~urface area 337 m2/~, an alumina
content of 14.1% and an aativity ~f 7.~ a~te~ steam
deactivation.
Example 7
This sample prepared by the same procedu~e a~
Example 4, except that 4Q5 ml 37.Q% HCl was used, ~bis
product had a surface area of 48~ m2/9~ and alumin~
content of 6.18% and an actlv~ty ~ 7.0~ afte~ ~team
deactlvation.
Table I below summarlze8 the ~sult~ a~ ~xamples
1-7.
~ln-
TABLE I
Microactivity of Acid Reacted Metakaolin Cracking Catalyst as
Function of Acid Level
~ Stoichiometric Time at Reflux Surface Area ~ R12O3 in
5 Example ~ ~Cl (hr5.) (m /g)Leached Clay Microactivity
1 17 8 284 38.8 40.7
2 17 60 436 36.6 3~.9
3 29 8 277 43.8 34.8
4 50 1/~ 157 33.3 ~0.7 ~1
~7 1/2 232 23.6 13.
6 83 1/2 337 14.1 7.5
7 100 1/2 488 6.18 7.0
1. A~TM-D3907 microactivity test after an 8 hour, 732C, 100% steam deactivation (vol.
conversion).
11 -
~f2~
Example 8
This example shows that the temperature used in the
calcination of the clay to obtain metakaolin affects
the rate of surface area formation. 100 g of a
calcined kaolin prepared by heating kaolin clay for
about 50 minutes at 732C was added to separate
solutions of 37.1 ml 37.0~ HCl diluted to 330 ml. The
resulting mixtures were aged for 16, 44 or 51 hours.
The results summarized in Table II indicate that while
this metakaolin is slower reacting than the metakaolin
(840C) used in Examples 1-7, high surface area
products are obtained when long acid-reaction times are
used.
TABLE II
Surface Area of 17% Stoichiometric HCl Reacted
Metakaolin (50 min. @ 732C)
Time Q 100C Surface Area (m2/g)
16 128
4~ 296
51 303
-12-
Example 9
This example shows the effect of acid solution
volume/concentration on surface area development.
Using the metakaolin of Example 1 33.5 ml quantities of
37 percent HC1 (representing 17 mol % of the acid
required to react with the alumina present in the
metakaolin) were diluted with water to obtain solutions
which ranged from 125 to 300 ml in volume. Table III
se~s forth results for 6 samples. Although all
products have high surface area indicating good
catalytic activity, the third or fourth samples appear
to b timum concentration levels.
\\
\
-13- \
TABLE III
Effect of ~cid Concentration on Surface Area of Reacted Clay Productl
Sample No. Reaction Siurry (Composition) Surface Area (m3~g)
1 . 33.5 ml 37% HCl diluted to 300 ml + 100 g metakaol~n (as per Ex~mple 1~ 386
2 n ~ 250 Ml + " n l~ 319
~ n 200 ml + n ~ 1~ 378
4 n n 175 ml + n n i~ 404
~ ~ n 150 ml + ~ n ~ 315
6 u .- 125 ml f n n ~ 268
1. All preparations were at 17% of stoichiometric HCl, with 60 hr. age at 100C in teflon bottles.
- 14 -
Examp]e 10
This example shows that nitric acid can be used in
the preparation of the products of the present
invention. 19.3 ml concentrated HNO3 was diluted to
5 225 ml, and 75 g metakaolin (calcined 50 minutes at
871C) was added. Three samples of the mixture were
reacted in separate teflon bottles for 4, 6 and 8 hours
at 100C. The results, set forth in Table IV, show
that the high surface area product is formed after
about about 6 hours (Samples 2 and 3).
TABLE IV
Dilute NHO3 Reacting of Metakaolin
Sample No. Hot Age Time (hrs.) Surface Area (m /g)
1 4 11
2 6 236
3 8 314
-15-
12~
Example 11
This example shows that selected calcination
conditions reduce the reaction time required to obtain
hlgh surface area products. Separate samples of kaolin
were put into a hot furnace at temperatures ranging
from 650 to 927C for one hour. S0 g samples o each
of the above calcined clays were slurried in 150 ml
H2O containing 16.9 ml concentrated HCl. The 50 g
samples were divided into 3 separate samples and
reacted in teflon bottles for 4, 8 or 16 hours. The
results, given in Table V, indicate the most effective
calcination temperature is 850 to 875C. Clays
calcined at 927C exhibited much lower reactivi~y.
\
\
\
~ \
-lb -
~ABLE V
Product Surface Area 2S a Function of Calcination
Temperature and Reaction Time
Calcination Temp. (C) 650 732 788 843 871 899 927
5Reaction Time, 4 hrs. 87 31 28 184 126 148 25
n n 8 hrs. 25 18 25 340 338 219 28
n 16 hrs. 24 47 36 296 457 220 36 p~
1. .~11 kaolin calcined 1 hour at the indicated ~emperature.
- 17 -
~z~ z
Example 12
This example shows that low acid levels can be used
to obtain the product of this invention. 225 9 of
calcined kaolin (calcined either one-half hour at
899C, 1 hour at 871C or 1 hour at 843C) was slurried
in 675 ml solution containing 19.2 ml concentrated
HCl. The resulting slurries were boiled 16 hours under
reflux. Each slurry sample was filtered, washed to
remove CL and oven dried. The results, given in
Table VI, indicate substantial surface area development
even at this relatively low acid level.
\
\
~18-
TABLE VI
Use of 1/24 Stoichiometric HCl on Various Metakaolins
Clay Calcination Conditions Reaction Time (~rs.) Surface Area (m /g)
1/2 hr. @ 899C 8 206
5 I~ n 12 287
D n 14 300
16 338
hr. @ 843C 8 198
n n 12 231
lC n n 14 251
~I n 16 2 51
1hr~ ~ 871~C 8 196
n n lQ 252
u n 12 270
1~ ~ n 14 278
Example 13
This example shows that a salt which can generate
H via hydrolysis can be used in place of mineral
acids. 75 g portions of metakaolin (calcined 1/2 hr.
5 at 900C) were added to 900 ml solutions containing
varying amounts of AlC13.6H2O. The slurries were
refluxed, the pH adjusted to 7.0 with lg~ NH~OH,
filtered, washed Cl free and oven dried. The
results, given in Table VII, c].early show the
development of very high surface area materials even at
low AlC13.6H2O levelsO
\\
-20-
TABLE VII
Effect of Level of AlC13 6~2O on Rate of Surface Area Development
g AlCl3 6E2O/75 g Metakaolin Time at Reflux (Hrs.~ Surface Area (m /9)2
75.3 5 l/2 278
37.7 8 333
37.7 16 418
25.1 8 313
25.1 16 390
18.9 8 305
lO18.9 l~ 428
12.6 8 256
12.6 16 410
- 21 -
~2(~ZfJ~
Example 14
This ex~mple shows that ammoniation of the acid
reacted clay slurry just prior to filtration enhances
activity. A reacted clay slurry was prepared and
reacted as in Example 1 except that after reacting the
slurry pH was adjusted to 6.0 with 14% NH40H prior to
filtration. The surface area was 326 m2/g and the
activity was 49.2, which is substantially higher than
the 40.7 observed for the product obtained in ~xample 1.
Example 15
This example shows that enhan_ed activity can be
obtained by precipitating alumina in the presence of
acid reacted metakaolin. 5,400 ml concentrated HCl was
diluted to about 48 1 with water and 16,000 g
metakaolin (calcined 1 hour at 732C) was added. The
resulting mixture was reacted under reflux for 48
hours, filtered, washed 2 times with 10 gallons hot
H2O. This product had a surface area of 2a3 m2/g.
50 g (dry basis, 104.2 g as is) of this filter cake was
20 dispeesed in 1/2 1 H2O containing 26.3 g
AlC13.6H2O. The pH adjusted to 6.0 with 14%
N~140H to precipitate alumina and the product was
filtered, washed 2 times with 1/2 1 hot ~12 and dried
at 120C. The alumina treated sample had an activity
25 of 45.6 versus 36.1 for the untreated sample.
Example 16
This example shows the preparation of a gelled acid
treated metakao]in of the present invention. 150 g of
kaolin clay calcined 1/2 hour at 900C was added to 1.0
30 1 of solution containin~ 50.7 ml of 37% HCl. Half the
slurry boiled under reflux for 4 hours and the other
-22-
~2~ .Z
hal~ was boiled for about 8 hours. Both samples were
briefly cooled, the pH adjus~ed to 6.0 with 14% NH40H
to gel the alumina components, the slurry filtered and
washed 2 times with 1/2 1 hot deionized H2O and oven
dried. The surface areas of the 4 and B hour refluxed
samples were 295 and 402 m /g. The catalytic
activity of the 4 and 8 hour refluxed samples were 46.4
and 50.5 respectively following the procedure o
ASTM-D3907.
Example l?
This examplè shows that signi~icant enhancement in
activity is observed by addition of boehmite to the
gelled acid treated metakaolin of the present
invention. 200 g kaolin clay calcined 1/2 hour at
900C was added to 2.0 1 solution containing 67.9 ml
37% HCl and boiled under reflux for 24 hours. To four
separate cooled samples of the above slurry, varying
amounts of boehmite were added the p~l was adjusted to
7.0 with 14% NH40H, the slurry filtered and the
~ilter cake washed 2 times with 1/2 1 hot deionized
H2O. The samples were dried and the cracking
catalytic activity of each sample was determined. The
activity data, summarized in Table VIII shows that
boehmite addition to the gelled acid treated metakaolin
results in significant activity improvement.
-23-
TABLE VIII
fect of Added Boehmite on Gelled Acid Reacted Me~akaoli~ Catalysts
Added Bcehmite Yol. ~ Conversionl
50~0 t~ypical)
59.9
17.5 60.0 ~
20.0 59.0 Pa
22.5 - ~9.3
1. ASTM-D3907 Volume ~ conversion measured at 499C J 16 WHSV, 3 C/O
after an 8 hour, 732C~ 1OO~ steam treatment.
- 24 -
~ ` ~
~.2~
E~ample 1~
Samples of hydrothermally acid treated metakaolin
were prepared by adding 25 g kaolin (calcined l/2 hour
at 900C) to 125 ml ~2 containing 8.5 ml 37~ HCl and
heating for the time/temperature indicated in Table IX
in teflon lined hi.gh pressure reactors. The slurries
were cooled, diluted with water to make a stirrable
slurry, the pH adjusted to 7.0 with 14~ NH40H,
filtered, washed 2 times with l/2 1 hot H20 and oven
dried at 120C~ The activity of the hydrothermally
acid treated metakaolin is significantly increased
relative to the lOO~C refl~xed sampleu
\
-25-
TABLE IX
Effect of ~igh Temperature Acid Treatment
Reaction Temp. Reaction Time Surface Area Activity
(C) (~rs.) (~2~gl~ (Vol.~ Cov.)
100 (Typical) 4-~4 400 5Q (Typical)
140 ~ 413 57.9 ~
~3
140 ~8 526 59.2 ~~
165 6 - 392 58.0
1. Surface area measured after a 1 hour at 593C thermal treatment.
2. ASTM-D3907 volume ~ conversion measured after an 8 hour, 732C, 100% steam
treatment.
- 26 -
~'J~?f~
The above Example~ cl.early in~icate that valuable
catalyst compositions may be obtained using the
teachings of my invention.
-27-
