Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~L~26~6~
The present invention relates to catalytic cracking
catalysts, and more specifically to cracking catalyst
compositions which are particularly effective for the
cracking of residual type hydrocarbon feed stocks.
In recent years, the refining industry has been
required to process ever increasing quantities of
residual type feed stocks. These heavy feed stocks are
frequently contaminated with substantial quantities of
metals such as vanadium, nickel, iron and copper which
adversely affect cracking catalyst used in refinery
operations.
Zealot containing cracking catalysts in particular
are susceptible to deactivation poisoning by vanadium)
and in addition the catalytic selectivity of the
catalyst is adversely affected by the presence of iron,
copper and nickel.
US. 3,835,031 and US. 4,240,899 describe cracking
catalysts which are impregnated with Group IDA metals
for the purpose of reducing sulfur oxide emissions
during regeneration of the catalyst.
US. 3,409,541 describes catalytic cracking
processes wherein deactivation of the catalyst by
contaminating metals is decreased by adding to the
catalytic inventory a finely divided alkaline earth or
I boron type compound which reacts with the metal
contaminants to form an inert product that may be
removed from the catalytic reaction system.
US. 3,699,037 discloses a catalytic cracking
process wherein a finely divided additive such as
calcium and magnesium hydroxides, carbonates, oxides,
dolomite and/or limestone is added to the catalyst
inventory to sorb Six components present in the
regenerator flue gas.
US. 4,198,320 describes catalytic cracking
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~Z~2~9
catalysts which contain colloidal silica and/or alumina
additives that are added for the purpose of preventing
the deactivation of the catalyst when used to process
metals containing feed stocks.
US. 4,222,896 describes a metals tolerant zealot
cracking catalyst which contain a
magnesia-alumina-aluminum phosphate matrix.
US. 4,283,309 and 4,292,169 describe hydrocarbon
conversion catalysts which contain a metals-absorbing
matrix that includes a porous inorganic oxide such as
alumina, titanic, silica, circonia, magnesia and
mixtures thereof.
POT WOW 82/00105 discloses cracking catalysts that
are resistant to metals poisoning which comprise two
particulate size fractions, and an Six absorbing
additive such as aluminum oxide, calcium oxide and/or
magnesium oxide.
While the prior art suggests several catalytic
systems and compositions which are effective in
controlling the adverse poisoning effects of metals
contained in residual type feed stocks or limiting Six
emissions during regeneration of the catalyst, many of
the systems require the use of expensive additives
and/or processing systems and are not particularly cost
effective when operated on a commercial scale.
It is therefore an object of the present invention
to provide improved catalytic cracking catalysts which
are capable of cracking hydrocarbon feed stocks that
contain substantial quantities of metals and sulfur
It is another object to provide fluid cracking
catalysts (FCC) which are resistant to metals poisoning
and which may be recharged and used in large quantities
at reasonable cost.
It is a further object to provide a catalytic
Sue
cracking process which is capable of handling large
quantities of metals, vanadium in particular, without
substantial loss of activity or product yield.
These and still further objects of the present
invention will become readily apparent to one skilled
in the art from the following detailed description and
specific examples.
Broadly, my invention contemplates catalytic
cracking catalysts which include a basic alkaline earth
metal component in amounts ranging from about 5 to 80
weight percent expressed as the oxides, wherein the
catalyst is capable of maintaining a high degree of
activity when associated with substantial quantities of
deactivating metals such as vanadium deposited on the
catalyst.
The alkaline earth metal compound used in the
practice of the invention is selected from group IDA of
the Periodic Table with calcium and magnesium being
preferred. In a particularly preferred embodiment of
the invention the basic alkaline earth metal component
comprises natural or synthetic dolomite which has the
general chemical formula Mica (KIWI.
The fluid catalytic cracking catalysts which are
combined with the basic alkaline earth metal component,
are conventional and well known to those skilled in the
art. Typically, the catalysts comprise amorphous
manganese oxide gels such as silica-alumina hydrogels,
and/or a crystalline zealot dispersed in an inorganic
oxide matrix.
Preferred zealots are synthetic faujasite type Y
zealot) and/or shape selective zealots such as
ZSM-5. Type Y zealots which are exchanged with
hydrogen and/or rare earth metals such as HO and RYE,
and those which have been subjected to thermal
~22~2~g
treatments such as calcined, rare-earth exchanged Y
(CRY) and/or ZEUS are particularly suited for
inclusion in fluid cracking catalyst compositions.
Catalytically active zealot components are typically
described in US. patents 3,293,192 and RYE 28,629.
In addition to an active zealot component, the
catalysts contain an inorganic oxide matrix. The
inorganic oxide matrix is typically a silica-alumina
hydrogen, which may be combined with substantial
quantities of clay such as kaolin. In addition, it is
contemplated in catalyst matrix systems which comprise
silica, alumina, silica-alumina sots and gels may be
utilized in the practice of the present invention.
Methods for producing suitable catalyst compositions
are described in So 3,974,099, 3,957,689, 4,226,743,
3,867l308, and 4,247,420.
The basic alkaline earth metal component may be
added to the catalyst composition in the form of a
finely divided particulate solid or the component may
be added in the form of a soluble salt solution which
is subsequently converted to a solid oxide. Magnesium
and calcium oxides, hydroxides, carbonates or sulfates
are particularly suited forms of the basic alkaline
earth metal components which are added to the catalyst
either during or after manufacture. In one preferred
embodiment, the basic alkaline earth containing
component is physically admixed with the particulate
catalyst. In another preferred embodiment, the
alkaline earth metal component is included in the
catalyst composition (matrix) during manufacture. In
order to obtain the maximum degree of metals tolerance
while avoiding undue deactivation of a zealot
component which may be present in the catalyst, the
~L2Z6~6i9
alkaline earth metal component is added to the zealot
containing catalyst in a form that does not ion
exchange with the zealot component.
In a typical FCC catalyst preparation procedure, a
finely divided alkaline earth metal component, such as
dolomite, is blended with an aqueous slurry which
contains silica-alumina hydrogen, optimally a zealot,
and clay to obtain a pump able slurry which is then
spray dried to obtain micro spheroidal particles of
catalyst having a particle size ranging from about 20
to 100 microns. The spray dried catalyst, which
typically contains from about 0 to 35 percent by weight
zealot, 25 to 70 percent by weight clay, and 10 to 50
percent by weight matrix binder, such as silica,
alumina, silica-alumina hydrogen or sol, and from 5 to
80 percent by weight alkaline earth metal component, is
washed and ion exchanged to remove soluble impurities
such as sodium and sulfates. After drying to about
10-30 percent total volatile the catalyst is ready to
be used in conventional catalytic cracking processes.
Typical FCC processes involve contact of the catalyst
with a hydrocarbon feed stock which may contain
significant quantities, i.e. from 1 to 200 Pam of
vanadium and other metals such as nickel, iron and
copper at temperatures on the order of 900 to 1000F to
obtain cracked products of lower molecular weight such
as gasoline and light cycle oil.
It is found that during the catalytic cracking
process, the catalysts contemplated in the present
invention can sorb in excess of 0.1 percent and up to
10 percent by weight of metals, particularly vanadium,
while maintaining an acceptable level of activity and
product selectivity. Typical "conventional" catalysts,
which do not contain the alkaline earth metal component
3l2262~9
contemplated herein, lose substantial activity when the
metals content (vanadium in particular) exceeds about
0.1 weight percent.
Having described the basic aspects of the present
invention, the following examples are given to
illustrate the specific embodiments thereof.
Example 1
Catalyst A was prepared by mixing about 10 percent
by weight calcined rare earth exchanged type Y zealot
(CRY) that has been ammonium sulfate exchanged to
contain 0.6 weight percent NATO and 13 weight percent
ROY with 10 percent by weight dolomite, and 80
percent by weight kaolin clay. The mixture was
combined with small quantities of water and then
lo extruded into one-eighth inch diameter extradites. The
extradites were oven dried, crushed and sized to obtain
a particle size fraction ranging from 60 to 150 mesh
tlO0 to 20Q microns). A comparison Catalyst B was
prepared using a similar technique, however, the
dolomite component was omitted and replaced with clay.
Catalyst B therefore comprised 10 percent by weight RAY
and 90 percent by weight kaolin. A first set of
samples of each Catalyst A and B was impregnated with a
water solution. A second set of samples of Catalysts
and B were impregnated to a level of 0.67 weight
percent vanadium, using a solution which contained
vandal oxylate dissolved in water. All samples were
then pretreated at 900F for 1 hour and then 2 hours at
1400F to burn off residual organic material. The
catalyst samples were then subjected to a hydrothermal
deactivation treatment which involved contacting the
catalyst with 100 percent steam at a pressure of 2 elm
at 1350F for 8 hours. The catalysts of this Example
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I
(as well as the catalysts evaluated in additional
Examples) were then tested for catalytic cracking
activity using the micro activity test described in ASTM
D-3907. The micro activity (~) of the catalyst samples
is expressed in terms of volume percent (vol. I) of
feed stock converted. The results are summarized in
Table I set forth below.
TABLE I
Catalyst (Sample No.) V Content, wt.% MA, volt%
A (1) 0 60.1
A (2) 0.67 56.1
(1) 0 70.8
B (2) 0.67 13.2
--8--
7~2~ 9
Example 2
A series of catalyst samples was prepared which
contained 10 percent by weight calcined rare earth
exchanged Y CRY) which contained 3.2 percent NATO
and 14.9 percent ROY, a silica-alumina Vogel
which contained 72 percent by weight alumina, and
various quantities of clay and dolomite.
The silica-alumina Vogel component was prepared as
follows: A sodium silicate solution which contained 4
weight percent sodium silicate having the formula 3.3
Sweeney, a 4 weight percent sodium acuminate
solution, and 20 weight percent sulfuric acid solution
were mixed together such that the final pi ox the Vogel
slurry was 10Ø The flow rates of above solutions
were adjusted to give a final product composition of
72% AYE, 28% Sue.
Varying amounts of clay, dolomite, and CRY were
then mixed with the Vogel slurry. The slurry was
filtered, then reslurried with water to 15% solids
content. This slurry was then spray dried to give
micro spheroidal catalyst particles of 12 to 100 microns
(60 microns average. The catalyst was then washed to
remove sodium ions and sulfates, using water, 10
percent ammonium sulfate solution, and then 5 percent
ammonium carbonate solution.
The catalyst samples were then impregnated with
various quantities of water and vanadium and evaluated
using the techniques described in Example 1. The
composition of the catalysts and the micro activity test
results for catalyst samples having various quantities
of vanadium are summarized in Tale II below. In
addition, the quantities of hydrogen (Ho) and coke
(C) produced during the micro activity test were
determined.
I
TABLE II
Catalyst A B C D
Composition, Component, wt.%
Vogel 50 30 30 50
CRY 10 10 10 10
Clay 40 30 20 10
Dolomite 0 10 20 30
Micro activity (vol.%)
V content, wt.%
10 I (74 3) (79 9) (70.2) (68.5)
% Ho/% C .12/3.2 0.11/3.1 .12/2.8 .12/3.2
0.34 (56.6) (70.4) (66.9) (65.0)
% Ho/% C .51/3.2 0.21/2.7 .12/2.9 .13/3.0
0.67 (53.4) (52.2) (70.8) (60.5)
% Ho/% C .65/4.1 0.34/3.6 .13/3.1 .13/3.1
1.34 (20.6) (45.2) (69.3) (65.5)
% Ho/% C .82/4.8 0.38/3.1 .14/2.7 .11/2.6
--10--
~lL2ZÇ;Z69
The data set forth in Tables I and II clearly
indicates that the inclusion of basic alkaline earth
component (dolomite results in catalyst compositions
which are capable of maintaining a high degree of
activity when combined with quantities of vanadium
which significantly deactivate conventional catalysts.
Furthermore, it is noted that the inclusion of dolomite
does not significantly adversely affect the product
distribution, i.e. H2/C production characteristics,
lo of the catalysts.
Example 3
A commercial zealot fluid cracking catalyst was
physically blended with dolomite powder in the
proportions of 90% catalyst with 10% dolomite by weight
to obtain Catalyst A. In Catalyst B the dolomite was
replaced with inert clay (kaolin). Samples of both
Catalysts A and B were impregnated with water/vanadium
as in Example l. Each sample was subjected to a
hydrothermal deactivation by contacting the catalyst to
100% steam at 2 elms. for 8 hours at 1350F. The
samples were then tested for catalytic cracking
activity by the micro activity test. The results are
summarized in Table III.
1L22~Z~9
TABLE III
Catalyst A
% V (wit %) 0 .67~
MA (vol. I) 75.2% 61.0
Ho (vol. I) .050 .072
Coke (wt. I) 2053 2.20
Catalyst B
% Vote. %1 0 67%
MA (vol. %) 69.2 8.5
Ho (vol. %) .044 .275
Coke (wt. I) 2.45 1.28
Example 3 clearly shows that basic alkaline earth
oxides (dolomite) can be physically blended with
standard cracking catalyst to obtain catalytic
compositions which possess good activity when
impregnated with high levels of vanadium.
Example 4
A commercial zealot FCC catalyst was impregnated
to 0.34% V by weight. The catalyst was then screened
to retain particles having a size greater than 63
microns. Dolomite powder was similarly screened,
except the material having a particle size less than 63
microns was retained. The two sized components were
then physically blended together in the proportion of
80% catalyst, 20% dolomite and the blended composition
was subjected to a hydrothermal steam deactivation
treatment as described in Examples 1, 2 and 3, The
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ISLE
steamed sample was then separated by rescreening
through the same screen to separate the FCC catalyst
and dolomite components. Table IV shows the TV before
and after hydrothermal treatment of the separated
components.
TABLE IV
Component V (wt. % before White. % after)
r
FCC Catalyst 0.34 0.30
Dolomite 0.01 0.49
Example 4 clearly shows that the basic alkaline
earth oxide (dolomite) can selectively adsorb vanadium
and effectively remove it from the catalyst in a
hydrothermal environment such as exists in the
regenerator of an FCC process.
The above examples clearly indicate that useful
metals tolerance cracking catalysts may be obtained
using the teachings of the present invention.
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~;~26~;9
SUPPLEMENTARY DISCLOSURE
In accordance with the teachings of the principal
disclosure catalytic cracking catalysts which contain a basic
alkaline earth metal component in amounts greater than 5 per-
cent by weight, expressed as the oxides, are used to crack
hydrocarbon feed stocks that contain substantial quantities of
metals such as vanadium, nickel, copper and iron.
Broadly, the present invention contemplates catalytic
cracking catalysts which include a basic alkaline earth metal
component in amounts ranging from about 5 to 80 weight percent
expressed as the oxides, wherein the catalyst is capable of
maintaining a high degree of activity when associated with
substantial quantities of deactivating metals such as vanadium
deposited on the catalyst.
Now, and in accordance with the present teachings it has
been found that particulate basic alkaline earth metal compost-
lions which have an intra-particle pore structure characterized
by a pore volume of at least 0.1 cc/g in pores having a diameter
of about 200 to 10,000 A, and an average pore diameter (APT)
of greater than about 400 A when determined in the pore size
range of about 200 to 10,000 A diameter using the relationship:
APT - 4 x 10 x PI
SPA
wherein PI pore volume in cc/g in pores ringing from
200-10,000 A diameter in SPA - surface area in mug
in pores ranging from 200-10,000 A diameter, as
determined by mercury porosimetry.
The alkaline earth metal compound used in the
practice of the invention is selected from group IDA of
the periodic Table with calcium and magnesium being
Preferred and magnesium the most preferred. In a
particularly preferred embodiment of the invention the
basic alkaline earth metal component comprises natural
or synthetic dolomite which has the general chemical
formula Mica (KIWI, Moo, or magnesia-silica gels
and a significant pore volume in pores greater than
about 400 A at process temperatures of 1400F or so.
-SD 14-
Jo
~22~i2~;~
in a particularly preferred embodiment a magnesium
oxide containing component such as a magnesia-silica
gel (MgO.SiO2) is prepared in a particulate form
wherein the particle has a substantial pore volume in
pores having a diameter of greater than about 4009~.
The resulting MgO.SiO2 composition is included in a
~CC catalyst composition either as an integral
component of the FCC catalyst particle or more
preferably as a separate particulate additive in
amounts ranging from about 2.5 to 40 by weight of the
composition.
The preferred MgO.SiO2 Mel has the overall weight
composition of 30-~0~ Moo, and a pore volume in pores
greater than about AYE diameter of at least 0.1 cc/g
and preferably from about 0.2 to 1.0 cc/g. Where the
MgO.SiO2 gel is added to a FCC catalyst as a separate
particulate additive, the particle size and density of
the additive is preferably similar to that of the ~CC
catalyst, i.e. particle size range of about 40 to 80
microns and an average bulk density of 0.5 to 1.0 gag
A preferred MgO.SiO2 gel is prepared by reacting
aqueous sodium silicate and magnesium chloride
solutions at a temperature of about 15 to 50C to form
a precipitate gel which is recovered by filtration,
reslurried in water and spray dried at a temperature of
about 330 to 500C. Furthermore, particulate Moo can
be added to the MgOoSiO2 gel to give composition of
30-80% Moo to the final product.
As indicated above, the Moo containing catalyst
component must have the optimized pore structure
described above in order to be effective for vanadium
scavenging. This is due to the fact that partial molar
volume of magnesium vendetta is greater than magnesium
oxide. It is relieved that the vanadium poisoning of
cracking catalysts is caused by the poison precursor
H3V04 which is formed in the regeneration step from
the reaction of VOW and steam (for vapor pressure
-SD 15-
- I
~2~26~
data sex LEN. Yannopoulos, J. Pays. Chum. 72, 3293
~1968). Ho VOW is isoelectronic with H3PO4 and
is most probably a strong acid. H3VO4 therefore
destroys the zealot crystallanity and activity by acid
hydrolysis of the Swahili framework of the
zealot. As H3VO4 reacts with Moo and forms
(MgO)2V2O5 on the surface of pore, the surface of
the pore will well due to larger molar volume of
(MgO)2V2O5. If the pore is too small, blocking
will occur readily and thereby inhibit the further
reaction with H3V04. We have experimentally
determined that the average pore diameter must be
greater than AYE or Jo to be effective. This effect
has been extensively studied with similar reaction:
Coo + SO > Casey
(see S. K. Bush and D. D. Perlmutter Ache J. 27, 266
and 29, 79).
As indicated above, Moo is the preferred oxide over
the other alkaline earths when used in conjunction with
FCC catalysts. This is due to the presence of sulfur
oxides in the flue gases of the regenerator, which can
compete with H3V04 forming alkaline earth Swiss
as shown by a consideration of the equilibrium
constants for the reactions of McCoy and Casey with
vanadic acid. Assuming a worst case test in which all
of the Six is assumed to be SO at a typical level
of 2000 Pam in the regenerator, 20% HO, 1.07 Pam
H3V04 and a temperature of 970K ~1285F) a
calculated equilibrium constant assuming unit activity
for the condensed phases from the regenerator
conditions above can be compared to the equilibrium
constant for the two reactions from thermochemical data
as follows:
-SD 16-
3l2262~9
Casey 2H3V04(91 - (Cove)
+ 2S03(9) + rug X (970K) - 472.75
McCoy + 2H3V04(g) - (M90)2 2 5 5
2S03(9) 3H20(9) X(970K) 6.675 x lo
K 2 3
gala ~~S03] I
thieve
~2.215 x 105
or the case of calcium the calculated equilibrium
from regenerator conditions is much greater than the
equilibrium constant for the reaction. By the lo
Chatlier's principle the reaction will favor the left
hand side of reaction with calcium. the opposite is
true for the case with Moo. If calcium is used Casey
will be preferentially formed over the vendetta, the
opposite is true for magnesium.
lo The fluid catalytic cracking catalysts which are
combined with the basic alkaline earth metal component,
are conventional and well known to those skilled in the
art. Typically, the catalysts comprise amorphous
inorganic oxide gels such as silica-alumina hydrogels,
end/or a crystalline zealot dispersed in an inorganic
oxide matrix.
Preferred zealots are synthetic faujasite (type Y
zealot) and/or shape selective zealots such as
ZSM-5. Type Y zealots which are exchanged with
hydrogen Andre rare earth petals such as HO and RAY,
and those which have been subjected to thermal
treatments such as calcined, rare-earth exchanged Y
(CRY) Andre Zl4US are particularly suited for
inclusion in fluid cracking catalyst compositions.
-SD 17-
3L2;~62~;9
Catalytically active zealot components are typically
described in US. patents 3,293,192 and RYE 28,629.
In addition to an active zealot component, the
catalysts contain an inorganic oxide matrix. The
inorganic oxide matrix is typically a silica-alumina
Harley, which may be combined with substantial
quantities of clay such as kaolin. In addition, it is
contemplated in catalyst matrix systems which comprise
silica, alumina, ~ilica-alumina owls and gels may be
utilized in the practice of the present invention.
Methods for producing suitable catalyst compositions
are described in US. 3,974,099, 3,957,689, 4,226,743,
3,B67,30B, 4,247,4~0.
The following additional examples act to further
illustrate the present teachings:
Example 5
This example shows the preparation and use of large
and small pore Moo based vanadium scavenging additives. A
magnesia-silica gel was prepared by mixing a 3.62% Sue and
10.87% Noah aqueous solution with 13.28% McCoy aqueous soul-
lion at equal flow rates through a mix pump to form a
MgO.SiO2 gel with composition 60 White Moo 40 wt.% Sue. The
temperature of the reaction mixture was 30C for
example A to make smaller pore diameters, end 20C for
example B for larger pore diameters. The resultant gel
in both cases was filtered, reslurried in water to ~10
solids and spray dried at 330C. The spray dried
material was washed with 70C HO to remove Nail.
Figure 1 shows the Hug pore size diameter for both preps
after calcination for 2 hours at 53BC. Analytical
data in Table shows the two Samples have similar
properties except that the metals tolerance of an 80~
commercial FCC catalyst (Super D) 20% additive (either
A or B) was dramatically improved for example B. This
example clearly demonstrates the importance of the
-SD lo-
~22~2~g
larger pyre volume end APT for vanadium scavenging
effectiveness,
TABLE V
Analytical and Metals Data for Two Moo Additives
Theoretical Composition
60% Moo
40~ Sue
(AYE) AYE)
Run-off Temp. 30C 20C
Moo 64.07 62.58
Sue 38.40 36.41
PI ~20-10,000) cc2/g .06~ .19
APT (20-10l000) A 703 624
Metals impregnation of 80% Super D, 20~ Additive with
.67% V. S-13.5 steam.
My (F) .30 .16
C (F) 2.10 1.65
Example 6
. . .
This example again shows the use of high pore
volume and low pore volume Moo. Catalyst A is a blend
of ~04 Super D, 20~ commercially available high pore
volume Moo (from Martin Marietta grade Maxim
Catalyst B it a blend of 80~ Super D, 20~ commercially
available low pore volume Moo (from Martin Marietta
grade Maxim 10). Both catalysts are impregnated by
the procedure in Example 1. table VI shows the
micro activity results.
-SD 19-
~2~2~g
TABLE VI
Catalyst A Catalyst B
PI (20-10,000) m2tg .821 ,065
APED (20-10,000) A 1,266 3,466
Ox VIA 67 67
H2/C .06/2.30 .04/1.73
,67~ VIA 55 13
H2/C ,08/1.82 .06/.75
101.34% VIA 38 11
I .11/1.51 ,091
-SD 20-
:,
, .~.
