Cracking catalyst

A novel cracking catalyst, a method of preparing same and an improved hydrocarbon cracking process are provided wherein adverse effects of metals such as nickel, vanadium, iron, copper and cobalt in the cracking catalyst are precluded or mitigated by contacting the cracking catalyst with (A) at least one of elemental antimony and compounds thereof and (B) at least one of elemental tin and compounds thereof whereby there is added to said catalyst a modifying amount of each of (A) and (B) with the weight ratio of antimony to tin being such as to provide passivation of the contaminating metals greater than the sum of the passivation effects of each of (A) and (B) individually. In general the ratio will be in the range of from 0.001:1 to 1000:1, and preferably will be in the range of 0.05:1 to 50:1.

Hydrocarbon feedstock containing higher molecular weight hydrocarbons is 
cracked by contacting it at an elevated temperature with a cracking 
catalyst whereby distillates such as gasoline and higher-boiling 
hydrocarbon fuels, e.g., kerosene, diesel fuel, burning oils and the like, 
are produced. However, the cracking catalyst gradually deteriorates during 
this process. One reason for this deterioration is the deposition of 
contaminating metals such as nickel, vanadium, iron, copper and cobalt on 
the catalyst, resulting in increased production of hydrogen and coke and 
decreased catalyst activity for cracking. Furthermore, the conversion of 
hydrocarbons into gasoline and higher-boiling hydrocarbon fuels is reduced 
by these metals. Therefore, there is a need for a cracking process or a 
modified cracking catalyst which will prevent or reduce the deleterious 
effects of these metal contaminants. 
It is thus an object of the present invention to provide an improved 
catalytic cracking process. 
Another object of this invention is to provide a process for the 
passivation of contaminating metals deposited on a cracking catalyst. 
Another object of this invention is to provide a process for restoration of 
used cracking catalyst. 
Another object of this invention is to provide a modified cracking 
catalyst. 
Another object of this invention is to provide a cracking catalyst which 
provides high yields and selectivity for gasoline or higher-boiling 
hydrocarbon fuel, e.g., kerosene, diesel fuel or burning oil. 
Another object of this invention is to provide a novel passivating agent 
for cracking catalyst. 
Other aspects, objects and the several advantages of the invention will be 
readily apparent to one skilled in the art from a reading of the following 
disclosure and the appended claims.

In accordance with this invention, we have found that the adverse effects 
of nickel, vanadium, iron, copper and/or cobalt or other similar 
contaminating metals on cracking catalyst can be precluded or mitigated by 
contacting the cracking catalyst with (A) an amount of at least one of 
antimony and compounds thereof sufficient to provide at least one 
improvement over said cracking catalyst selected from the group consisting 
of an increase in catalyst activity, an increase in yield of liquid fuels, 
a reduction in the production of coke, and a reduction in the production 
of hydrogen and (B) an amount of at least one of tin and compounds thereof 
sufficient to provide an enhancement in said at least one improvement 
which is greater than the same amount of said at least one of tin and 
compounds thereof would provide over said cracking catalyst in the absence 
of antimony and/or compounds thereof. In general, the antimony component 
will be present in such amount as to provide at least 0.0001, more 
generally at least 0.005, preferably at least 0.01, and more preferably, 
at least 0.05, weight percent of antimony in or on the cracking catalyst, 
this percentage being based on the weight of cracking catalyst prior to 
treatment with antimony and tin or compounds thereof. Similarly the amount 
of antimony employed will generally be less than 8, more generally less 
than 2, preferably less than 1, and more preferably less than 0.8 weight 
percent, based on the weight of the cracking catalyst prior to treatment 
with antimony and tin or compounds thereof. In general, the tin component 
will be present in such amount as to provide at least 0.0001, more 
generally at least 0.0005, preferably at least 0.001, and more preferably 
at least 0.005, weight percent, based on the weight of the cracking 
catalyst prior to treatment with antimony and tin or compounds thereof. 
Similarly the amount of tin employed will generally be less than 8, more 
generally less than 2, preferably less than 1, and more preferably less 
than 0.8 weight percent, based on the weight of the cracking catalyst 
prior to treatment with antimony and tin or compounds thereof. Although 
any weight ratio of antimony to tin which provides the enhancement can be 
utilized, generally it will be within the range of about 0.001:1 to about 
1000:1, more generally being within the range of about 0.01:1 to about 
100:1. A weight ratio of antimony to tin in the range of 0.05:1 to 50:1 is 
generally preferred, with a value in the range of 2:1 to 20:1 being more 
preferred, and a value in the range of 5:1 to 15:1 being even more 
preferred. 
By the addition of both antimony and tin in accordance with the present 
invention to the cracking catalyst either prior to, during or after its 
use there are achieved at least one of an increase in catalyst activity, 
an increase in yield of gasoline or higher-boiling hydrocarbon fuels, 
e.g., kerosene, diesel fuel, burning oils or the like, a decrease in the 
production of coke and a decrease in the production of hydrogen. 
In accordance with one embodiment of this invention, a novel cracking 
catalyst is provided that has been prepared by contacting a conventional 
cracking catalyst with both antimony and tin in an amount and in a manner 
as herein described. 
In accordance with another embodiment of this invention, there is provided 
a novel treating agent for cracking catalyst which consists essentially of 
a mixture of antimony and tin, either as the elemental metals or as 
compounds thereof as well as mixtures thereof, wherein the weight ratio of 
antimony to tin is such as to provide a passivation of contaminating 
metals deposited on a cracking catalyst greater than the sum of the 
passivation effects of each of the antimony and tin individually. In 
general, this ratio will be within the range of about 0.001:1 to about 
1000:1, more generally in the range of about 0.01:1 to about 100:1, 
preferably in the range of 0.05:1 to 50:1, more preferably in the range of 
2:1 to 20:1, and even more preferably in the range of 5:1 to 15:1. 
The term "cracking catalyst" as used herein refers to either new or used 
cracking catalyst materials that are useful for crackin hydrocarbons in 
the absence of added hydrogen. The crackin catalyst referred to can be any 
conventional cracking catalyst. The term "unmodified cracking catalyst" as 
used herein means any cracking catalyst which has not been modified by 
contact with either antimony or tin. 
Such cracking catalyst materials can be any of those cracking catalysts 
conventionally employed in the catalytic cracking of hydrocarbons boiling 
above 400.degree. F. (204.degree. C.) for the production of gasoline, 
motor fuel, blending components and light distillates. These conventional 
cracking catalysts generally contain silica or silica-alumina. Such 
materials are frequently associated with zeolitic materials. These 
zeolitic materials can be naturally occurring, or they can be produced by 
conventional ion exchange methods such as to provide metallic ions which 
improve the activity of the catalyst. Zeolite-modified silica-alumina 
catalysts are particularly applicable in this invention. Examples of 
cracking catalysts into or onto which antimony and tin can be incorporated 
include hydrocarbon cracking catalysts obtained by admixing an inorganic 
oxide gel with an aluminosilicate, and aluminosilicate compositions which 
are strongly acidic as a result of treatment with a fluid medium 
containing at least one rare earth metal cation and a hydrogen ion, or ion 
capable of conversion to a hydrogen ion. The unused catalytic cracking 
material employed will generally be in particulate form having a particle 
size principally within the range of about 10 to about 200 microns. 
If desired, the cracking catalyst can contain a combustion promoter such as 
platinum or chromium. 
The unused catalytic crackin material as employed in the present invention 
contains essentially no nickel, vanadium, iron, copper or cobalt. 
Particularly and preferably, the nickel, vanadium, iron and copper metals 
content of the unused catalytic cracking material which constitutes the 
major portion of the unused cracking catalyst of this invention is defined 
by the following limits: 
______________________________________ 
nickel 0 to 0.02 weight percent 
vanadium 0 to 0.06 weight percent 
iron 0 to 0.8 weight percent 
copper 0 to 0.02 weight percent 
______________________________________ 
The weight percentages in this table relate to the total weight of the 
unused catalytic cracking material including the metals nickel, vanadium, 
iron and copper, but excluding the added antimony and tin modifying 
agents. The contents of these metals on the cracking catalyst can be 
determined by standard methods well known in the art, e.g., by atomic 
absorption spectroscopy or by X-ray fluorescence spectroscopy. 
The catalytic cracking materials can vary in pore volume and surface area. 
Generally, however, the unused cracking catalyst will have a pore volume 
in the range of about 0.1 to about 1 ml/g. The surface area of this unused 
catalytic cracking material generally will be in the range of about 50 to 
about 500 m2/g. 
The modified catalyst of this invention consists essentially of a 
conventional cracking catalyst having a modifying or passivating amount of 
both antimony and tin therein or thereon. The quantity of antimony and tin 
is generally such that about 0.0001 to about 8, more generally about 0.005 
to about 2, preferably about 0.01 to about 1, and more preferably about 
0.01 to about 0.8, weight percent antimony and about 0.0001 to about 8, 
more generally about 0.0005 to about 2, preferably about 0.001 to about 1, 
and more preferably about 0.001 to about 0.8, weight percent tin are 
deposited on the catalyst, these percentages being based on the weight of 
crackin catalyst prior to treatment with antimony and tin or compounds 
thereof. The amount of antimony and tin which is most desirable on the 
catalyst will vary according to the effective level of contaminating 
metals on the catalyst, with higher values of antimony and tin being 
desirable for higher effective values of contaminating metals. 
The manner in which the conventional cracking catalyst is contacted with 
the antimony and tin modifying or treating agents is not critical. For 
example, the agents in finely divided form can be mixed with the 
conventional cracking catalyst in ordinary manner such as rolling, 
shaking, stirring or the like. Alternatively, the treating agents can be 
dissolved or dispersed in a suitable liquid, e.g., water, hydrocarbon or 
aqueous acid, depending in part on the particular modifying agents used, 
and the resulting solution or dispersion can be used to impregnate the 
conventional cracking catalyst, followed by volatilization of the liquid, 
or the modifying agents can be precipitated onto the catalyst from 
solutions of the treating agents in different chemical form, followed by 
solvent removal. If desired, the modifying agents can be dissolved or 
dispersed in the hydrocarbon feedstock to the cracking process, in which 
instance the hydrocarbon feedstock and the treating agents contact the 
cracking catalyst at about the same time. Also, if desired, the cracking 
catalyst can be exposed to the treating agents in vapor form to deposit 
the agents on the catalyst. Of course, combinations of the various methods 
can be employed to achieve modification of the catalyst with the treating 
agents. The modifying agents can be added to the catalyst simultaneously 
or sequentially. The addition of the modifying agents can be continuous or 
intermittent, as desired. The modifying agent can be added to the catalyst 
directly or via the feedstock during a first period of time and the second 
modifying agent can be subsequently added to the catalyst directly or via 
the feedstock during a second period of time. 
Although the ratio of treating agents to conventional cracking catalyst can 
vary over a wide range, depending in part on the concentration of 
contaminating metals on the catalyst and in the hydrocarbon feedstock to 
be cracked, the treating agents generally will be used in an amount such 
as to provide at least about 0.0001, more generally at least about 0.005, 
preferably at least about 0.01, and more preferably at least about 0.05, 
parts by weight of antimony per 100 parts by weight conventional cracking 
catalyst, i.e., including any contaminating metals in the catalyst but 
excluding the treating agents. The treating agents will be used in an 
amount such as to provide generally at least about 0.0001, more generally 
at least about 0.0005, preferably at least about 0.001, and more 
preferably at least about 0.005, parts by weight tin per 100 parts by 
weight of such conventional cracking catalyst. Similarly the treating 
agents will be used in an amount such as to provide generally less than 8, 
more generally less than 2, preferably less than 1, and more preferably 
less than 0.8, parts by weight of each of antimony and tin per 100 parts 
by weight of such conventional cracking catalyst. 
The form in which antimony is present in or on the cracking catalyst or is 
employed in the preparation of the antimony/tin-containing catalysts is 
not critical. Any antimony compound which provides passivation of 
contaminating metals deposited on a cracking catalyst can be utilized. 
Thus, elemental antimony, inorganic antimony compounds, and organic 
antimony compounds as well as mixtures for any two or more thereof are 
suitable sources of antimony. The term "antimony" generally refers to any 
one of these antimony sources. Examples of some inorganic antimony 
compounds which can be used include antimony oxides such as antimony 
trioxide, antimony tetroxide, and antimony pentoxide; antimony sulfides 
such as antimony trisulfide and antimony pentasulfide; antimony selenides 
such as antimony triselenide; antimony tellurides such as antimony 
tritelluride; antimony sulfates such as antimony trisulfate; antimonic 
acids such as metaantimonic acid, orthoantimonic acid and pyroantimonic 
acid; antimony halides such as antimony trifluoride, antimony trichloride, 
antimony tribromide, antimony triiodide, antimony pentafluoride and 
antimony pentachloride; antimonyl halides such as antimonyl chloride and 
antimonyl trichloride; antimonides such as indium antimonide; and the 
like. Of the inorganic antimony compounds, those which do not contain 
halogen are preferred. Although organic antimony compounds for use in the 
preparation of the antimony/tin-containing catalysts preferably contain 
about 3 to about 54 carbon atoms for reasons of economics and 
availability, organic antimony compounds outside this range are also 
applicable. Thus, organic polymers containing antimony can be employed as 
the organic antimony compound. In addition to carbon and hydrogen, the 
organic antimony compound can contain elements such as oxygen, sulfur, 
nitrogen, phosphorus or the like. Examples of some organic antimony 
compounds which can be used in the preparation of the 
antimony/tin-containing catalyst include antimony carboxylates such as 
antimony triformate, antimony trioctoate, antimony triacetate, antimony 
tridodecanoate, antimony trioctadecanoate, antimony tribenzoate, and 
antimony tris(cyclohexenecarboxylate); antimony thiocarboxylates such as 
antimony tris(thioacetate), antimony tris(dithioacetate) and antimony 
tris(dithiopentanoate); antimony thiocarbonates such as antimony 
tris(O-propyl dithiocarbonate); antimony carbonates such as antimony 
tris(ethyl carbonate); trihydrocarbylantimony compounds such as 
triphenylantimony; trihydrocarbylantimony oxides such as triphenylantimony 
oxide; antimony salts of phenolic compounds such as antimony triphenoxide; 
antimony salts of thiophenolic compounds such as antimony 
tris(thiophenoxide); antimony sulfonates such as antimony 
tris(benzenesulfonate) and antimony tris(p-toluenesulfonate); antimony 
carbamates such as antimony tris(diethylcarbamate); antimony 
thiocarbamates such as antimony tris(dipropyldithiocarbamate), antimony 
tris(phenyldithiocarbamate) and antimony tris(butylthiocarbamate); 
antimony phosphites such as antimony tris(diphenyl phosphite); antimony 
phosphates such as antimony tris(dipropyl phosphate); antimony 
thiophosphates such as antimony tris(O,O-dipropyl thiophosphate) and 
antimony tris(O,O-dipropyl dithiophosphate) and the like. The last 
compound is also known as antimony tris(O,O-dipropyl phosphorodithioate), 
and is the presently preferred source of antimony, due in part to its 
solubility in hydrocarbons and its commercial availability. Mixtures of 
any two or more applicable substances comprising antimony can be employed. 
The form in which tin is present in or on the cracking catalyst or is 
employed in the preparation of the antimony/tin-containing catalysts is 
not critical. Any tin compound which promotes the passivation effects of 
antimony can be employed. Thus elemental tin, inorganic tin compounds and 
organic tin compounds as well as mixtures thereof are suitable sources of 
tin. The term "tin" as used herein generally refers to any one of these 
tin sources. Examples of some inorganic tin compounds which can be used 
include tin oxides such as stannous oxide and stannic oxide; tin sulfides 
such as stannous sulfide and stannic sulfide; tin selenides such as 
stannous selenide and stannic selenide; tin tellurides such as stannous 
telluride; tin sulfates such as stannous sulfate and stannic sulfate; 
stannic acids such as metastannic acid and thiostannic acid; tin halides 
such as stannous fluoride, stannous chloride, stannous bromide, stannous 
iodide, stannic fluoride, stannic chloride, stannic bromide and stannic 
iodide; tin phosphates such as stannic phosphate; tin oxyhalides such as 
stannous oxychloride and stannic oxychloride; and the like. Of the 
inorganic tin compounds those which do not contain halogen or silicon are 
preferred as the source of tin. Although organic tin compounds for use in 
the preparation of the antimony/tin-containing catalysts preferably 
contain about 2 to about 48 carbon atoms for reasons of economics and 
availability, organic tin compounds outside this range also are 
applicable. Thus organic polymers containing tin can be employed as the 
organic tin compound. In addition to carbon and hydrogen, the organic tin 
compound can contain elements such as oxygen, sulfur, nitrogen, phosphorus 
or the like. Examples of some organic tin compounds which can be used in 
the preparation of the antimony/tin-containing catalysts include tin 
carboxylates such as stannous formate, stannous acetate, stannous 
butyrate, stannous octoate, stannous decanoate, stannous oxalate, stannous 
benzoate, and stannous cyclohexanecarboxylate; tin thiocarboxylates such 
as stannous thioacetate and stannous dithioacetate; dihydrocarbyltin 
bis(hydrocarbyl mercaptoalkanoates)s such as dibutyltin bis(isooctyl 
mercaptoacetate) and dipropyltin bis(butyl mercaptoacetate); tin 
thiocarbonates such as stannous O-ethyl dithiocarbonate; tin carbonates 
such as stannous propyl carbonate; tetrahydrocarbyltin compounds such as 
tetrabutyltin, tetraoctyltin, tetradodecyltin, and tetraphenyltin; 
dihydrocarbyltin oxides such as dipropyltin oxide, dibutyltin oxide, 
dioctyltin oxide, and diphenyltin oxide; dihyrocarbyltin bis(hydrocarbyl 
mercaptide)s such as dibutyltin bis(dodecyl mercaptide); tin salts of 
phenolic compounds such as stannous thiophenoxide; tin sulfonates such as 
stannous benzenesulfonate and stannous-p-toluenesulfonate; tin carbamates 
such as stannous diethylcarbamate; tin thiocarbamates such as stannous 
propylthiocarbamate and stannous diethyldithiocarbamate; tin phosphites 
such as stannous diphenyl phosphite; tin phosphates such as stannous 
dipropyl phosphate; tin thiophosphates such as stannous O,O-dipropyl 
thiophosphate, stannous O,O-dipropyl dithiophosphate and stannic 
O,O-dipropyl dithiophosphate; dihydrocarbyltin bis(O,O-dihydrocarbyl 
thiophosphate)s such as dibutyltin bis(O,O-dipropyl dithiophosphate); and 
the like. Mixtures of any two or more applicable substances comprising tin 
can be employed. Dibutyltin bis(isooctyl mercaptoacetate) and stannic 
O,O-dipropyl dithiophosphate are the tin-containing substances presently 
preferred, due in part to their solubility in hydrocarbons and their 
compatibility with antimony tris(O,O-dipropyl dithiophosphate). As a 
further advantage, the dibutyltin bis(isooctyl mercaptoacetate) is 
commercially available. 
Since the main purpose of the antimony and tin on the catalytic cracking 
material is to prevent or mitigate the otherwise (without the antimony and 
tin) occurring undesirable effects of contaminating metals, in particular, 
the increased hydrogen and coke production and the reduced yields of 
gasoline or higher-boiling hydrocarbon fuels such as kerosene, diesel 
fuel, and burning oils caused by these contaminating metals, the sources 
of antimony and tin utilized and incorporated into or onto the cracking 
catalyst should be essentially free of such contaminating metals. The 
antimony and tin sources thus should essentially contain no nickel, no 
vanadium, no iron, no copper and no cobalt or other detrimental 
contaminating metal. 
The antimony/tin-containing catalyst can be prepared by contacting the 
conventional catalytic cracking material with an admixture comprising an 
antimony treating agent and a tin treating agent, or the conventional 
cracking catalyst can be contacted with the antimony treating agent and 
the tin treating agent individually, in separate steps, with or without an 
intermediate step such as heating or diluent removal. Thus, the 
conventional cracking catalyst can be contacted with both treating agents 
at the same time or first with either treating agent and then with the 
other. Prior to or during use in the cracking process the 
antimony/tin-containing catalyst is heated to an elevated temperature, 
e.g., within the range of about 800.degree. F. (427.degree. C.) to about 
1500.degree. F. (816.degree. C.), in an oxidizing or reducing atmosphere. 
Such heating can occur in the catalytic cracker, in the catalyst 
regenerator, or in a vessel separate from the catalytic cracker or 
catalyst regenerator. Thus, the antimony/tin-containing catalyst can be 
prepared from used or, preferably, new conventional cracking catalyst by 
admixing this conventional catalyst with the antimony treating agent and 
the tin treating agent, separately or as a mixture, in the presence or 
absence of a diluent, with removal of the diluent, if employed, with or 
without heating to an elevated temperature, and the resulting catalyst can 
be added as make-up catalyst for the cracking process, this make-up 
catalyst preferably being added to the catalyst regenerator. In a 
preferred process the antimony treating agent and the tin treating agent, 
in admixture or preferably separately, as such or preferably dissolved or 
dispersed in a suitable liquid, are added to the oil feedstock as the 
feedback is charged to the catalytic cracker, the treating agents being 
added at such a rate as to maintain the concentration of antimony in or on 
the catalyst generally within the range of about 0.0001 to about 8, more 
generally in the range of about 0.005 to about 2, preferably in the range 
of about 0.01 to about 1, and more preferably in the range of about 0.01 
to 0.8 weight percent, these percentages being based on the weight of 
cracking catalyst prior to treatment with the antimony and tin or 
compounds thereof. Similarly the treating agents are added at such a rate 
as to maintain the concentration of tin in or on the catalyst generally 
within the range of about 0.0001 to about 8, more generally in the range 
of about 0.0005 to about 2, preferably in the range of about 0.001 to 
about 1, and more preferably in the range of about 0.001 to about 0.8, 
weight percent, on the same basis as with the antimony. Less preferably, 
the antimony and tin treating agents can be added directly to a stream of 
catalyst in the cracking process. It is presently desirable that the 
cracking catalyst be contacted with the tin source in situ in the cracking 
reactor system. When the tin source component is added to the cracking 
catalyst outside of the cracking reactor system, it is desirable for such 
tin treated catalyst to be employed in the cracking process within a short 
time period, e.g., within five days, to minimize any effects of aging of 
the tin on the cracking catalyst. 
In accordance with a further embodiment of this invention there is provided 
a process for restoring used cracking catalyst by passivating 
contaminating metals selected from the group consisting of nickel, 
vanadium, iron, copper and cobalt which process comprises contacting the 
contaminated cracking catalyst with an antimony treating agent and a tin 
treating agent under elevated temperature. 
The time during which the catalyst is contacted with the two treating 
agents is not critical. Generally the time for a batch treatment of the 
catalyst outside of the reaction is in the range of from 0.1 to 300 
minutes. In a presently preferred embodiment, the two treating agents are 
continuously metered into the cracking reactor via introduction into the 
feedstock. If desired, one treating agent can be applied directly to the 
catalyst and the other treating agent can be introduced via the feedstock. 
As used herein, the term "antimony treating agent" is intended to include 
elemental antimony or a compound thereof as described above. 
Similarly, the term "tin treating agent" is intended to include elemental 
tin or a compound thereof as described above. 
In accordance with a still further embodiment of this invention, there is 
provided an improved cracking process wherein hydrocarbon feestock is 
contacted under cracking conditions with a modified cracking catalyst 
which comprises a modifying amount of both an antimony treating agent and 
a tin treating agent as defined above. For this embodiment, too, the 
preferred details concerning the modified cracking catalyst disclosed 
above apply. Thus, the preferred modified cracking catalyst is one that is 
obtained by mixing a cracking catalyst with both a tin treating agent and 
an antimony treating agent and subjecting the mixture to high temperature 
conditions. Most preferably, the initial high-temperature treatment of the 
cracking catalyst-treating agent mixture is carried out under reducing 
conditions. 
Advantageously, and in accordance with a still further embodiment of this 
invention, the antimony/tin treating agents are added to the feedstock 
entering the cracking zone in which they are contacted with cracking 
catalyst. By this procedure the contacting of the cracking catalyst and 
the treating agents and the initial treatment under elevated temperatures 
are done under the reducing conditions prevailing in the catalytic 
cracker. 
The cracking process in which the antimony/tin-containing cracking catalyst 
is employed is basically an improvement over a conventional cracking 
process which employs a conventional cracking catalyst alone or as 
modified by either antimony or tin. Although the antimony/tin-containing 
cracking catalyst can be employed in a catalytic cracking process 
employing a fixed catalyst bed, it is especially useful in a fluid 
catalytic cracking process. 
A preferred embodiment of the cracking process of this invention utilizes a 
cyclic flow of catalyst from a cracking zone to a regeneration zone. In 
this process, a hydrocarbon feedstock containing contaminating metals such 
as nickel, vanadium or iron is contacted in a cracking zone under cracking 
conditions and in the absence of added hydrogen with an 
antimony/tin-containing cracking catalyst as defined above; a cracked 
product is obtained and recovered; the cracking catalyst is passed from 
the cracking zone into a regeneration zone; and in the regeneration zone 
the cracking catalyst is regenerated by being contacted with a free 
oxygen-containing gas, preferably air. The coke that has been built up 
during the cracking process is thereby at least partially burned off the 
catalyst. The regenerated cracking catalyst is reintroduced into the 
cracking zone. 
Furthermore, it is preferred in carrying out the cracking process of this 
invention to replace a fraction of the total cracking catalyst with unused 
cracking catalyst continuously or intermittently. Generally, about 0.5 to 
about 6 weight percent of the total cracking catalyst is replaced daily by 
fresh cracking catalyst. The actual quantity of the catalyst replaced 
depends in part upon the nature of the feedstock used. The make-up 
quantity of cracking catalyst can be added at any location in the process. 
Preferably, however, the cracking catalyst that is make-up catalyst is 
introduced into the regenerator in a cyclic cracking process. 
Also, it is to be understood that the used cracking catalyst coming from 
the cracking zone, before introduction into the regenerator, is stripped 
of essentially all entrained liquid or gaseous hydrocarbons. Similarly, 
the regenerated catalyst can be stripped of any entrained oxygen before it 
reenters the cracking zone. The stripping is generally done with steam. 
The specific conditions in the cracking zone and in the regeneration zone 
are not critical and depend upon several parameters, such as the feedstock 
used, the catalyst used, and the results desired. Preferably and most 
commonly, the cracking and regeneration conditions are within the 
following ranges: 
______________________________________ 
Cracking Zone 
______________________________________ 
Temperature: 800.degree.-1200.degree. F. (427.degree.-649.degree. C.) 
Time: 1-40 seconds 
Pressure: Subatmospheric to 3000 psig 
Catalyst:oil ratio: 
3:1 to 30:1, by weight 
______________________________________ 
______________________________________ 
Regeneration Zone 
______________________________________ 
Temperature: 1000.degree.-1500.degree. F. (538.degree.-816.degree. 
C.) 
Time: 2-40 minutes 
Pressure: Subatmospheric to 3000 psig 
Air at 60.degree. F. (16.degree. C.) 
100-250 ft.sup.3 /lb. coke 
and 1 atmosphere: 
(6.2-15.6 m.sup.3 /kg coke) 
______________________________________ 
The feedstocks employed in the catalytic cracking process of this invention 
contain metal contaminants such as nickel, vanadium, iron, copper and/or 
cobalt and the like. The feedstocks include those which are conventionally 
utilized in catalytic cracking processes to produce gasoline and light 
distillate fractions from heavier hydrocarbon feedstocks. The feedstocks 
generally have an initial boiling point above about 400.degree. F. 
(204.degree. C.) and include fluids such as gas oils, fuel oils, cycle 
oils, slurry oils, topped crudes, shale oils, oils from tar sands, oils 
from coal, mixtures of two or more of these, and the like. By "topped 
crude" is meant those oils which are obtained as the bottoms of a crude 
oil fractionator. If desired, all or a portion of the feedstock can 
constitute an oil from which a portion of the metal content previously has 
been removed, e.g., by hydrotreating or solvent extraction. 
Typically the feedstock utilized in the process of this invention will 
contain one or more of the metals nickel, vanadium and iron within the 
ranges shown in the following table: 
______________________________________ 
Metal Content 
Metal of Feedstocks, ppm.sup.(1) 
______________________________________ 
Nickel 0.02 to 100 
Vanadium 0.02 to 500 
Iron 0.02 to 500 
Total metals 0.2 to 1100.sup.(2) 
______________________________________ 
.sup.(1) The ppm metal content refers to the feedstock as used. As used i 
this table and throughout the specification, ppm means parts per million, 
by weight. 
.sup.(2) Total metals in this table and elsewhere refers to the sum of th 
nickel, vanadium and iron contents in the feedstock that are effective in 
contaminating the catalyst; the total metals content can be determined in 
accordance with methods well known in the art, e.g., by atomic absorption 
spectroscopy. 
One of the most important embodiments of this invention resides in a heavy 
oil cracking process. The known commercial heavy oil cracking process is 
capable of cracking heavy oils having a metals content of up to 80 ppm of 
total effective metals, i.e., metals in any form detrimental to the 
cracking process. Economically marginal results are obtained with oils 
having 40 to 80 ppm of total effective metals. In accordance with this 
invention, heavy oils with a total metals content of about 40 to 100 ppm 
and even those of about 100 to 200 ppm and above of total metals can be 
cracked in a cracking process in the absence of added hydrogen by 
utilizing the cracking catalyst defined above to yield gasoline and other 
fuels and fuel blending components. Thus, known heavy oils with total 
metals contents of from 80 to 300 ppm, that heretofore could not be 
directly used for fuel production and in particular for gasoline or 
higher-boiling hydrocarbon fuels production, in accordance with this 
invention can be cracked to yield gasoline and higher-boiling hydrocarbon 
fuels such as kerosene, diesel fuel and burning oils. Most preferably, the 
concentration of antimony plus tin in or on the antimony/tin-containing 
cracking catalyst used in the process of this invention for cracking these 
heavily metal-loaded oils is related to the average total effective metals 
content of the feedstock as shown in the following table: 
______________________________________ 
Total Effective Metals 
Antimony + Tin Concentration 
in Feedstock (ppm).sup.(2) 
in Catalyst, Weight %.sup.(1) 
______________________________________ 
&lt;1-40 0.0001-0.6 
40-100 0.05-0.8 
100-200 0.1-1 
200-300 0.15-1.5 
300-800 0.2-2 
______________________________________ 
.sup.(1) Based on weight of catalyst prior to addition of antimony and 
tincontaining modifying agents. 
.sup.(2) "Total Effective Metals" as used herein means the sum of the 
vanadium concentration, the catalytic iron concentration, four times the 
nickel concentration, four times the copper concentration, and the 
products of the concentration of any other contaminating metals and their 
respective relative activity. 
The invention will be still more fully understood from the following 
examples, which are intended to illustrate preferred embodiments of the 
invention but not to limit the scope thereof. 
EXAMPLE I 
A commercial cracking catalyst comprising amorphous silica-alumina 
associated with zeolitic material, which had been used in a commercial 
cracking unit and subsequently subjected to regeneration in the 
laboratory, was employed in a series of tests which demonstrated the 
effectiveness of antimony and tin, together, in improving a 
metals-contaminated used cracking catalyst. Properties of the used 
cracking catalyst prior to regeneration in the laboratory are shown in 
Table I. 
TABLE I 
______________________________________ 
Surface area, m.sup.2 /g 
74.3 
Pore volume, ml/g 0.29 
Composition, weight % 
Aluminum 21.7 
Silicon 24.6 
Nickel 0.38 
Vanadium 0.60 
Iron 0.90 
Cerium 0.40 
Sodium 0.39 
Carbon 0.06 
______________________________________ 
The used commercial cracking catalyst having the properties shown in Table 
I was then subjected to regeneration in the laboratory by heating the 
catalyst while fluidized with air to 1200.degree. F. (649.degree. C.) and 
maintaining it at that temperature for about 30 minutes while fluidized 
with air. The catalyst was then cooled to room temperature (about 
25.degree. C.) while fluidized with nitrogen, and the resulting 
regenerated catalyst, herein designated as catalyst O, was employed as 
shown below. 
A portion of catalyst O was used in the preparation of a catalyst 
composition containing 0.5 part by weight antimony and 0.5 part by weight 
tin per 100 parts by weight catalyst O. This was done by dry blending 35.0 
parts by weight catalyst O with 0.367 part by weight dibutyltin oxide 
which previously had been ground until it passed through a 325 mesh 
screen. The resulting blend was then mixed with a solution prepared by 
mixing 27 parts by weight cyclohexane and 1.61 parts by weight of a 
mineral oil solution containing about 80 weight percent antimony 
tris(O,O-dipropyl phosphorodithioate). The mixture was then dried to a 
fine powder by heating to 500.degree. F. (260.degree. C.) on a hot plate. 
The above catalyst comprising antimony and tin was conditioned in the 
following manner. The catalyst was placed in a laboratory-sized, confined 
fluid bed, quartz reactor and heated from room temperature (about 
25.degree. C.) to 900.degree. F. (482.degree. C.) while fluidized with 
nitrogen, then heated from 900.degree. F. (482.degree. C.) to 1200.degree. 
F. (649.degree. C.) while fluidized with hydrogen. While maintained at 
about 1200.degree. F. (649.degree. C.), the catalyst was then fluidized 
with nitrogen for 5 minutes, followed by fluidization with air for 15 
minutes. The catalyst was then aged through 10 cycles, each cycle being 
conducted in the following manner. The catalyst at about 900.degree. F. 
(482.degree. C.) was fluidized with nitrogen for 1 minute, then heated to 
about 950.degree. F. (510.degree. C.) during 2 minutes while fluidized 
with hydrogen, then maintained at about 950.degree. F. (510.degree. C.) 
for 1 minute while fluidized with nitrogen, then heated to about 
1200.degree. F. (649.degree. C.) for 10 minutes while fluidized with air, 
and then cooled to about 900.degree. F. (482.degree. C.) during 0.5 minute 
while fluidized with air. After these 10 aging cycles the catalyst was 
cooled to room temperature (about 25.degree. C.) while fluidized with 
nitrogen to provide a catalyst herein designated as catalyst AT. 
A second portion of catalyst O was used in the preparation of a catalyst 
composition containing 0.63 part by weight tin per 100 parts by weight 
catalyst O. This was done by dry blending 35 parts by weight regenerated 
catalyst O with 0.47 part by weight dibutyltin oxide which previously had 
been ground until it passed through a 325 mesh screen. The blend was then 
conditioned, aged, and finally cooled to room temperature, by the 
procedure shown for catalyst AT, to provide a catalyst herein designated 
as catalyst T. 
A third portion of catalyst O was used in the preparation of a catalyst 
composition containing 0.5 part by weight Sb per 100 parts by weight 
catalyst O. This was done by mixing catalyst O with a cyclohexane-mineral 
oil solution of antimony tris(O,O-dipropyl phosphorodithioate) containing 
0.0147 g antimony per ml solution. The cyclohexane and mineral oil were 
removed by heating on a hot plate, and the resulting blend was 
conditioned, aged, and finally cooled to room temperature, by the 
procedure shown for catlyst AT, to provide a catalyst herein designated as 
catalyst A. 
Catalysts AT, T, A and O were evaluated in four series of cracking 
regeneration cycles using topped West Texas crude oil as the feedstock in 
the cracking step. Except as otherwise noted in Table III, in each cycle 
the cracking step was carried out at 950.degree. F. (510.degree. C.) and 
about atmospheric pressure for 0.5 minute, and the regeneration step was 
conducted at about 1200.degree. F. (649.degree. C.) and about atmospheric 
pressure for approximately 30 minutes using fludizing air, the reactor 
being purged with nitrogen before and after each cracking step. 
Properties of the topped West Texas crude oil used in the cracking steps 
are shown in Table II. 
TABLE II 
______________________________________ 
API gravity at 60.degree. F. (16.degree. C.).sup.(1) 
21.4 
Distillation, .degree.F. (.degree.C.).sup.(2) 
IBP 556 (291) 
10% 803 (428) 
20% 875 (468) 
30% 929 (498) 
40% 982 (528) 
50% 1031 (555) 
Carbon residue, Rams, wt. %.sup.(3) 
5.5 
Elemental analysis 
S, wt. % 1.2 
Ni, ppm 5.24 
V, ppm 5.29 
Fe, ppm 29 
Pour point, .degree.F. (.degree.C.).sup.(4) 
63 (17) 
Kinematic viscosity, cSt.sup.(5) 
at 180.degree. F. (82.degree. C.) 
56.5 
at 210.degree. F. (99.degree. C.) 
32.1 
Refractive index at 67.degree. C..sup.(6) 
1.5 
______________________________________ 
.sup.(1) ASTM D 28767 
.sup.(2) ASTM D 116061 
.sup.(3) ASTM D 52464 
.sup.(4) ASTM D 9766 
.sup.(5) ASTM D 44565 
.sup.(6) ASTM D 174762 Cracking tests conducted with catalysts AT, T, A 
and O are summarized in Table III. 
TABLE III 
__________________________________________________________________________ 
Conversion, 
Yield 
Cracking Catalyst:Oil 
Vol. % Coke, H.sub.2, SCF/bbl 
Gasoline, 
Material 
Test.sup.(1) 
Catalyst 
Wt. Ratio 
of Feed 
Wt. % of Feed 
Feed Converted 
Vol. % of Feed 
Balance, Wt. 
__________________________________________________________________________ 
% 
1 AT 7.5 79.8 14.3 401 68.1 104 
2 AT 7.5 80.3 12.6 341 69.2 101 
3.sup.(2) 
AT 7.6 68.4 10.1 350 57.6 97.7 
4 AT 7.5 75.8 11.6 392 58.2 95.0 
5 AT 8.5 76.9 11.1 340 55.8 92.9 
6 AT 9.3 76.1 12.9 347 59.2 96.7 
7.sup.(3) 
AT 7.7 72.6 12.3 377 56.7 95.9 
8.sup.(3) 
AT 7.4 74.7 12.5 334 61.0 97.4 
1 T 7.4 74.5 14.0 678 55.0 96.5 
2 T 8.6 81.6 15.5 673 55.3 95.0 
1.sup.(4) 
A 7.6 73.4 10.9 371 59.9 96.1 
1.sup.(5) 
A 7.4 75.8 12.1 330 63.4 -- 
1.sup.(6) 
0 7.7 74.9 17.6 895 54.6 100.7 
__________________________________________________________________________ 
.sup.(1) Cracking tests are numbered in the order in which tests were 
conducted for the particular catalyst. 
.sup.(2) Cracking test 3 was conducted about 9 months after cracking test 
2 on catalyst AT. 
.sup.(3) Catalyst regeneration preceding this test was conducted at about 
1300.degree. F. (704.degree. C.) for approximately 15 minutes instead of 
at about 1200.degree. F. (649.degree. C.) for approximately 30 minutes. 
.sup.(4) Although the catalyst used in this test was employed previously 
in 3 cracking tests at other catalyst:oil ratios, this catalyst was 
substantially unchanged in performance after use in such a relatively few 
crackingregeneration cycles. 
.sup.(5) This test was not an actual run. The values for this test were 
read off of smooth curves for a constant catalyst:oil ratio of 7.4 
produced from values read from smooth curves produced from data obtained 
from multiple runs with varying catalyst:oil ratios. 
.sup.(6) Although the catalyst used in this test was employed previously 
in 9 cracking tests conducted at temperatures of 950.degree.-1020.degree. 
F. (510.degree.-549.degree. C.) at various catalyst:oil ratios, this 
catalyst was substantially unchanged in performance after such limited 
use. 
As indicated in Table III, each of the cracking tests in which the catalyst 
used was modified with both antimony and tin showed this catalyst to 
perform well as a cracking catalyst in the presence of contaminating 
metals. However, particularly outstanding results were obtained with this 
catalyst in the first two cracking tests. In these two tests the extent to 
which the catalyst had been subjected to cracking and regeneration 
conditions after incorporation of antimony and tin into the catalyst was 
not great and was less than in the subsequent tests with this catalyst. In 
these first two tests with the catalyst modified with both antimony and 
tin the conversion of feed was higher than in any other test at comparable 
catalyst:oil ratio, indicating higher catalyst activity, and the yield of 
gasoline was much greater than in any of the other tests. In these same 
two tests hydrogen production and coke production were much lower than in 
the test employing catalyst into which neither antimony nor tin had been 
incorporated. 
As can be seen readily from a study of Table III, of the eight cracking 
tests conducted with the catalyst comprising both antimony and tin, tests 
3-8 provided considerably lower conversion of feed and substantially lower 
yield of gasoline than did tests 1 and 2 of the same series. These lower 
values for conversion and gasoline yield are believed to be due to 
deactivation of the catalyst during the nine months of shelf-aging 
following tests 1 and 2, possibly by interaction of tin with silicon in 
the catalyst. 
EXAMPLE II 
This calculated example is given to indicate how the invention can be 
operated in plant scale. In a commercial cracking unit containing 200 tons 
of cracking catalyst, 24,300 bbl/day of oil having an API gravity of 20.8 
are cracked. In order to build up a level of 0.5 weight percent (based on 
untreated cracking catalyst) of each of antimony and tin on the cracking 
catalyst, antimony tris(O,O-dipropyl phosphorodithioate) and dibutyltin 
oxide are each added in a quantity of 20 ppm of antimony or tin, 
respectively, to the feedstock for 17 days or of 30 ppm of antimony or 
tin, respectively, to the feedstock for 10 days. In order to keep the 
antimony level and the tin level each at 0.5 weight percent, the rate of 
addition has to be 10 ppm of each of antimony and tin in case 8 tons of 
catalyst per day are withdrawn from the reactor and replaced by untreated 
catalyst. In case only 6 tons of catalyst per day are replaced, this 
addition would be sufficient to keep the antimony and tin levels of the 
catalyst system at 0.65 weight percent each. In absolute figures this 
means that 2175 pounds of a mineral oil solution of antimony 
tris(O,O-dipropyl phosphorodithioate), this solution having an antimony 
content of 11 weight percent, and 503 pounds of dibutyltin oxide have to 
be added, per day, to the feedstock for 10 days (1450 pounds and 335 
pounds, respectively, for 17 days), and that 725 pounds of this mineral 
oil solution of antimony tris(O,O-dipropyl phosphorodithioate) and 168 
pounds of dibutyltin oxide have to be added to the feedstock to maintain 
the desired level of each of antimony and tin on the catalyst at 0.5 
weight percent. 
EXAMPLE III 
A commercial cracking catalyst comprising amorphous silica-alumina 
associated with zeolitic material, which had been used in a commercial 
cracking unit and subsequently subjected to regeneration in the 
laboratory, was employed in the preparation of cracking catalysts 
containing varying amounts of antimony, tin, or antimony and tin, the 
source of antimony being antimony tris(O,O-dipropyl phosphorodithioate) 
and the source of tin being dibutyltin oxide previously ground until it 
passed through a 325 mesh screen. Properties of the used cracking catalyst 
prior to regeneration in the laboratory were as shown in Table I in 
Example I. The used commercial cracking catalyst having these properties 
was then subjected to regeneration in the laboratory by heating the 
catalyst while fluidized with air to 1200.degree. F. (649.degree. C.) and 
maintaining it at that temperature for 0.5-2 hours while fluidized with 
air. The catalyst was then cooled to room temperature (about 25.degree. 
C.) while fluidized with nitrogen, and the resulting regenerated catalyst, 
herein designated as catalyst X, was employed as shown below. 
Portions of catalyst X were used in the preparation of catalyst 
compositions containing, per 100 parts by weight catalyst X, 0.05 part by 
weight antimony and 0.05 part by weight tin, 0.10 part by weight antimony 
and 0.01 part by weight tin (two preparations), 0.01 part by weight 
antimony and 0.10 part by weight tin, and 0.50 part by weight antimony and 
0.50 part by weight tin. In each of these five preparations the calculated 
amount of dibutyltin oxide to provide the desired tin content was dry 
blended with catalyst X, after which the calculated amount of a mineral 
oil solution of antimony tris(O,O-dipropyl phosphorodithioate) containing 
10.9 weight percent antimony, together with cyclohexane, was stirred with 
the resulting blend to provide the desired antimony content. The mixture 
was then taken to apparent dryness by heating on a hot plate. 
Other portions of catalyst X were used in the preparation of catalyst 
compositions containing 0.01, 0.1, 0.5, and 1.0 parts by weight tin per 
100 parts by weight catalyst X. In each of these four preparations the 
calculated amount of dibutyltin oxide to provide the desired tin content 
was dry blended with catalyst X, the blend was wetted with cyclohexane, 
and the resulting mixture was taken to apparent dryness by heating on a 
hot plate. 
Still other portions of catalyst X were used in the preparation of catalyst 
compositions containing 0.05, 0.1, 0.25, 0.5, and 1.0 parts by weight 
antimony per 100 parts by weight catalyst X. In each of these five 
preparations the calculated amount of a mineral oil solution of antimony 
tris(O,O-dipropyl phosphorodithioate) containing 10.9 weight percent 
antimony, in cyclohexane, was stirred with catalyst X, and the resulting 
mixture was taken to apparent dryness on a hot plate. 
Each of the 14 catalyst compositions above was conditioned in the following 
manner. The catalyst was placed in a laboratory-sized, confined fluid bed, 
quartz reactor and heated from room temperature (about 25.degree. C.) to 
900.degree. F. (482.degree. C.) while fluidized with nitrogen, then heated 
from 900.degree. F. (482.degree. C.) to 1200.degree. F. (649.degree. C.) 
while fluidized with hydrogen. While maintained at about 1200.degree. F. 
(649.degree. C.), the catalyst was then fluidized with nitrogen for 5 
minutes, followed by fluidization with air for 15-20 minutes. The catalyst 
was then aged through 10 cycles, each cycle being conducted in the 
following manner. The catalyst was cooled, generally to about 900.degree. 
F. (482.degree. C.) during 0.5 minute, while fluidized with air or 
nitrogen, then fluidized with nitrogen while maintained at approximately 
900.degree. F. (482.degree. C.) for about 1 minute, then heated to 
1200.degree. F. (649.degree. C.) during 2 minutes while fluidized with 
nitrogen and hydrogen, then maintained at 1200.degree. F. (649.degree. C.) 
for 1 minute while fluidized with nitrogen, and then maintained at 
1200.degree. F. (649.degree. C.) for 8-94 minutes while fluidized with 
air. After these 10 aging cycles the catalyst was cooled to room 
temperature (about 25.degree. C.) while fluidized with nitrogen. 
The 14 aged catalysts prepared as described above and catalyst X (2 
samples) were evaluated in 15 series of cracking-regeneration cycles, in 
which the cracking step was conducted over a range of catalyst:oil ratios, 
using about 34-40 g of catalyst as a confined fluid bed in a quartz 
reactor and employing a gas oil as the feedstock in the cracking step. In 
each cycle the cracking step was carried out at 950.degree. F. 
(510.degree. C.) and about atmospheric pressure for 0.5 minute, and the 
regeneration step was conducted at 1200.degree. F. (649.degree. C.) and 
about atmospheric pressure for approximately 30 minutes using fluidizing 
air, the reactor being purged with nitrogen before and after each cracking 
step. 
Properties of the gas oil used in this Example are shown in Table IV. 
TABLE IV 
______________________________________ 
API gravity at 60.degree. F. (16.degree. C.).sup.(1) 
25.8 
Specific gravity 0.8996 
BMCI.sup.(2) 41.1 
Distillation, .degree.F. (.degree. C.).sup.(3) 
2% 498 (259) 
5% 529 (276) 
10% 566 (297) 
20% 621 (327) 
30% 669 (354) 
40% 715 (379) 
50% 759 (404) 
60% 799 (426) 
70% 842 (450) 
80% 895 (479) 
90% 973 (523) 
95% 1047 (564) 
Carbon residue, Rams, wt. %.sup.(4) 
0.87 
Sulfur, wt. % 0.40 
Basic nitrogen, wt. % 
0.025 
Total nitrogen, wt. % 
0.07 
______________________________________ 
.sup.(1) ASTM D 28767. 
.sup.(2) V. A. Kalichevsky and K. A. Kobe, "Petroleum Refining with 
Chemicals", Elsevier Publishing Co., New York, N.Y. (1956), p. 56. 
.sup.(3) ASTM D 116061. 
.sup.(4) ASTM D 52464. 
Results of the cracking tests conducted at various catalyst:oil ratios are 
summarized in Table V. All cracking tests caried out with a given catalyst 
are included except those which gave results which obviously were in error 
because of equipment malfunction or human error. Specifically, tests 
having a material balance outside of 100.+-.5% were omitted. Tests with a 
given catalyst were made in the order in which they are listed. In each 
instance in which the catalyst was one which had been treated with tin, 
with the exception of the M, N and O series, not more than 4 days elapsed 
between the time of preparation and conditioning of the catalyst and the 
time the first test was conducted, or between any two tests, including 
tests which were in error for the reasons noted above. In the M, N and O 
series, about 34 days, about 35 days, and about 22 days, respectively, 
elapsed between the time the catalyst was prepared and conditioned and the 
time the first test was conducted. FIGS. 1 through 7 show in graphical 
form comparisons of selected tests given in Table V, a series of at least 
five tests with a given catalyst composition at varying catalyst:oil 
ratios being curve-fitted to provide smooth curves as shown, and two or 
three tests with a given catalyst composition at nearly constant 
catalyst:oil ratios being shown as single points, each of which represents 
the average of the values on which it is based. 
TABLE V 
__________________________________________________________________________ 
Catalyst, Wt. % Conversion, 
Yield 
Cracking 
Element Added 
Catalyst:Oil 
Vol. % Coke, H.sub.2, SCF/bbl 
Gasoline, 
Test.sup.(1) 
Sn.sup.(2) 
Sb.sup.(3) 
Wt. Ratio 
of Feed 
Wt. % of Feed 
Feed Converted 
Vol. % of Feed 
__________________________________________________________________________ 
1A 0 0 6.04 59.0 7.2 700 47.3 
2A 0 0 7.87 66.3 9.2 674 54.3 
3A 0 0 9.51 68.3 9.4 663 52.0 
4A 0 0 7.00 61.1 7.1 616 51.5 
5A 0 0 8.99 69.1 9.4 573 54.6 
6A 0 0 7.07 61.2 7.5 626 53.5 
7A 0 0 9.91 68.9 9.0 662 53.4 
8A 0 0 8.02 62.9 7.5 671 56.8 
9A 0 0 8.02 67.0 8.4 611 55.2 
10A 0 0 9.02 64.2 8.2 668 55.6 
11A 0 0 6.00 59.9 6.7 617 51.9 
1B 0.01 
0 7.71 64.1 10.3 765 49.3 
2B 0.01 
0 9.04 67.2 10.8 800 56.1 
3B 0.01 
0 9.07 70.6 10.1 726 61.3 
4B 0.01 
0 6.50 60.6 7.7 636 50.8 
5B 0.01 
0 9.99 67.0 9.7 684 55.4 
6B 0.01 
0 8.07 62.6 8.3 611 55.9 
7B 0.01 
0 6.99 61.6 6.9 589 54.9 
8B 0.01 
0 6.03 59.8 5.6 555 53.1 
9B 0.01 
0 9.99 62.4 8.2 687 54.9 
10B 0.01 
0 10.17 67.8 9.4 613 50.8 
1C 0.10 
0 7.06 60.8 7.4 569 53.5 
2C 0.10 
0 7.96 61.7 6.8 587 57.3 
3C 0.10 
0 5.94 56.8 6.2 540 51.5 
4C 0.10 
0 9.99 62.3 8.3 618 50.9 
5C 0.10 
0 9.09 65.4 7.8 562 54.4 
1D 0.50 
0 6.94 61.3 6.3 481 52.9 
2D 0.50 
0 7.94 62.7 6.9 474 56.3 
3D 0.50 
0 9.09 65.0 7.5 536 53.5 
4D 0.50 
0 9.98 64.2 8.3 495 53.3 
5D 0.50 
0 6.02 57.8 5.4 452 53.9 
1E 1.00 
0 7.01 56.7 6.3 540 53.4 
2E 1.00 
0 10.06 63.5 7.7 530 54.4 
3E 1.00 
0 9.05 63.5 7.1 504 55.5 
4E 1.00 
0 8.09 62.6 6.9 533 54.8 
5E 1.00 
0 10.64 71.0 8.1 540 55.2 
1F 0 0.05 
9.91 66.0 9.2 608 54.7 
2F 0 0.05 
9.07 67.0 5.6 563 51.9 
3F 0 0.05 
6.54 61.3 7.1 537 52.5 
4F 0 0.05 
7.75 62.6 6.3 514 51.0 
5F 0 0.05 
8.63 67.6 7.6 522 51.7 
1G 0 0.10 
7.61 64.4 6.2 432 52.4 
2G 0 0.10 
10.04 69.8 7.1 416 57.2 
3G 0 0.10 
9.02 72.0 6.2 411 57.2 
4G 0 0.10 
8.33 66.5 6.4 422 58.1 
5G 0 0.10 
6.53 59.3 5.3 385 52.7 
1H 0 0.25 
7.76 64.3 6.4 338 55.3 
2H 0 0.25 
10.06 67.4 6.7 348 56.4 
3H 0 0.25 
11.04 70.9 7.9 336 52.6 
4H 0 0.25 
9.00 66.3 6.6 335 55.0 
5H 0 0.25 
6.50 60.6 5.1 293 53.8 
1I 0 0.50 
10.70 74.8 6.9 307 57.2 
2I 0 0.50 
6.44 66.5 5.8 269 59.7 
3I 0 0.50 
8.50 66.4 6.9 307 55.8 
4I 0 0.50 
9.49 68.7 6.9 341 52.9 
5I 0 0.50 
7.63 62.7 6.1 286 54.1 
1J 0 1.00 
7.72 61.0 9.1 376 51.2 
2J 0 1.00 
6.49 59.2 5.0 395 48.2 
3J 0 1.00 
8.61 60.5 6.6 491 49.1 
4J 0 1.00 
9.53 65.1 6.9 440 49.3 
5J 0 1.00 
10.50 68.5 7.4 431 46.9 
6J 0 1.00 
7.71 58.3 6.5 432 47.3 
7J 0 1.00 
9.03 62.5 7.1 456 50.0 
1K 0.05 
0.05 
7.74 59.1 6.9 565 52.9 
2K 0.05 
0.05 
9.98 65.5 8.1 571 50.9 
3K 0.05 
0.05 
10.51 68.6 8.9 524 52.0 
4K 0.05 
0.05 
8.53 69.0 8.0 485 57.0 
5K 0.05 
0.05 
9.37 75.1 8.3 494 61.2 
6K 0.05 
0.05 
6.56 61.9 6.5 472 54.9 
7K 0.05 
0.05 
10.01 65.4 7.9 545 57.2 
8K 0.05 
0.05 
9.86 69.5 7.9 486 52.8 
9K 0.05 
0.05 
8.97 69.8 7.5 479 58.8 
10K 0.05 
0.05 
7.70 60.9 7.2 494 56.0 
11K 0.05 
0.05 
6.54 65.2 6.1 430 59.3 
12K 0.05 
0.05 
7.50 66.9 6.2 428 62.9 
1L 0.01 
0.10 
10.08 69.5 7.8 474 55.9 
2L 0.01 
0.10 
9.10 68.5 7.4 447 56.4 
3L 0.01 
0.10 
6.44 68.8 5.8 356 62.3 
4L 0.01 
0.10 
7.65 70.7 6.2 376 63.6 
5L 0.01 
0.10 
8.50 74.6 7.3 347 63.4 
6L 0.01 
0.10 
5.89 67.5 6.2 377 63.6 
lM 0.01 
0.10 
7.71 70.5 7.2 444 59.5 
2M 0.01 
0.10 
7.70 70.9 7.7 449 58.8 
1N 0.10 
0.01 
7.72 60.4 7.5 548 52.8 
2N 0.10 
0.01 
7.70 65.9 8.3 566 56.3 
3N 0.10 
0.01 
7.73 65.4 8.3 567 55.5 
1O 0.50 
0.50 
7.75 66.8 6.3 305 58.2 
2O 0.50 
0.50 
7.68 63.0 6.0 338 53.3 
3O 0.50 
0.50 
7.74 65.5 6.9 320 56.4 
__________________________________________________________________________ 
.sup.(1) Tests 1A through 5A were conducted with one catalyst sample, and 
tests 6A through 11A were carried out with another catalyst sample. 
.sup.(2) Based on weight of catalyst prior to addition of tin as 
dibutyltin oxide and prior to addition of antimony, if any. 
.sup.(3) Based on weight of catalyst prior to addition of antimony as 
antimony tris(0,0dipropyl phosphorodithioate) and prior to addition of 
tin, if any. 
As can be seen by an analysis of the results shown in FIGS. 1 through 7, 
the advantages of using tin and antimony, in combination, as constituents 
of a cracking catalyst vary considerably, depending, for example, on the 
concentrations of tin and antimony, the ratio of tin to antimony, and the 
catalyst:oil ratio. FIG. 1 depicts most clearly the unexpectedly good 
conversion of feed throughout a range of catalyst:oil weight ratios of 
less than 6 to about 10 when a catalyst comprising both tin and antimony 
was used. Not only is the positive improvement in conversion contributed 
by the combination of antimony and tin greater than the algebraic sum of 
the positive contribution of antimony and the negative contribution of tin 
throughout the catalyst:oil weight ratio range of 6 to 10, the combination 
provides a definite enhancement of the positive contribution of antimony 
throughout the range of about 6 to about 9 for the catalyst:oil weight 
ratio. FIGS. 1 and 5 show best the surprisingly good yields of gasoline 
obtained at catalyst:oil weight ratios such as from about 6 to about 9.5 
in FIG. 1 and from about 6 to about 8.4 in FIG. 5, when catalysts 
containing both tin and antimony were employed. FIG. 6 shows clearly the 
unexpectedly low production of hydrogen at a catalyst:oil weight ratio of 
about 7.7 when a catalyst containing both tin and antimony was used. 
To further illustrate the advantages of having both tin and antimony in a 
cracking catalyst, shown in Table VI are conversion and yield results at a 
catalyst:oil weight ratio of 7.7:1, the values having been determined 
graphically from the appropriate curves in FIGS. 1 through 7, with the 
exception of cracking tests 13, 14 and 15, the values for which represent 
averages of the appropriate values shown for the M, N, and O series of 
tests, respectively, shown in Table V. Thus each of the cracking tests 
shown in Table VI is not an individual test which was actually carried out 
but instead is based on a series of tests which were conducted. 
TABLE VI 
__________________________________________________________________________ 
Catalyst, Wt. % 
Conversion, 
Yield 
Cracking 
Element Added 
Vol. % Coke, H.sub.2, SCF/bbl 
Gasoline 
Test Sn.sup.(1) 
Sb.sup.(2) 
of Feed 
Wt. % of Feed 
Feed Converted 
Vol. % of Feed 
__________________________________________________________________________ 
1 0 0 64 8.0 640 53.3 
2 0.01 
0 62 7.8 638 52.7 
3 0.1 0 61.4 7.2 578 54.1 
4 0.5 0 62 6.6 480 54.6 
5 1.0 0 60.1 6.6 530 53.9 
6 0 0.05 
64 6.1 530 52.5 
7 0 0.1 64.8 6.0 410 55.0 
8 0 0.25 
63.8 5.9 320 55.1 
9 0 0.5 66 6.3 295 56.1 
10 0 1.0 61 6.8 390 50.0 
11 0.05 
0.05 
64.2 6.9 475 56.8 
12 0.01 
0.10 
69.8 6.6 385 61.1 
13 0.01 
0.10 
70.7 7.5 446 59.1 
14 0.10 
0.01 
65.5 8.3 565 56.5 
15 0.50 
0.50 
65.1 6.4 320 56.0 
__________________________________________________________________________ 
.sup.(1) Based on weight of catalyst prior to addition of tin as 
dibutyltin oxide. 
.sup.(2) Based on weight of catalyst prior to addition of antimony as 
antimony tris(0,0dipropyl phosphorodithioate) and prior to addition of 
tin, if any. 
As shown in Table VI, the feed conversions and usually the gasoline yields 
are surprisingly high in cracking tests 11 through 15 employing catalysts 
within the scope of this invention when compared with the feed conversions 
and gasoline yields in cracking tests 1 through 10 conducted with 
catalysts outside the scope of this invention. For example, the feed 
conversion and gasoline yield in each of tests 12 and 13 are far higher 
than would be predicted on the basis of changes in these characteristics, 
based on results in control test 1 where neither antimony nor tin is 
present, in test 2 where tin is present in the absence of antimony, and in 
test 7 where antimony is present in the absence of tin, if such changes 
are additive. Thus, based on the results of tests 1, 2, and 7, the feed 
conversion in tests 12 and 13 would be predicted to be 
64+(62-64)+(64.8-64)=62.8 volume percent, and the gasoline yield in tests 
12 and 13 would be predicted to be 53.3+(52.7-53.3)+(55.0-53.3)=54.4 
volume percent of the feed. Each of these predicted values is decidedly 
inferior to the values for the corresponding characteristics as shown for 
tests 12 and 13. On a similar basis, the feed conversion and gasoline 
yield in test 14 are surprisingly high when compared with these 
characteristics for catalysts in tests 1, 3, and 6, interpolation being 
used to estimate the values for a catalyst having the antimony content of 
the catalyst in test 14 but containing no tin. Also, on a similar basis, 
the feed conversion and gasoline yield in test 11 are higher than would be 
predicted upon consideration of the values in tests 1, 2, 3, and 6, with 
the aid of interpolation, and the feed conversion in test 15 is higher 
than would be predicted upon consideration of the values in tests 1, 4, 
and 9. Furthermore, the feed conversion and gasoline yield obtained with 
the catalyst in test 11 are higher than the average of the values for the 
corresponding characteristic as determined in tests 3 and 7, in which the 
catalyst contains antimony or tin, in the absence of the other, in a 
concentration equal to the sum of the concentrations of antimony and tin 
in the catalyst in test 11. Actually, the gasoline yield in test 11 is 
higher than that in either of tests 3 and 7. Similarly, the feed 
conversion and gasoline yield obtained with the catalyst in test 15 are 
higher than the average of the values for the corresponding characteristic 
as shown for tests 5 and 10 and, in fact, are higher than either of the 
values for the corresponding characteristic as shown for tests 5 and 10. 
Also, similarly, the feed conversions and gasoline yields obtained with 
the catalyst in tests 12, 13, and 14 are higher than either value, as well 
as higher than the average of the values, for the corresponding 
characteristic for a catalyst containing antimony or tin, in the absence 
of the other, in a concentration equal to the sum of the concentrations of 
antimony and tin in the catalyst shown for any one of tests 12, 13, and 
14, the values for the catalysts containing antimony or tin, in the 
absence of the other, being obtained by interpolation between values shown 
for tests 3 and 4 and between values shown for tests 7 and 8. 
A comparison of test 12, in which a catalyst was used which has undergone 
no prolonged shelf-aging, with test 13, in which a like catalyst was 
utilized which has stood for about 34 days after it was prepared and 
conditioned before it was used in a cracking test, indicates that although 
the catalyst used in each of the two tests is very good, the overall 
effect of prolonged shelf-aging is deleterious. Thus, although the feed 
conversion in test 13 is better than in test 12, in test 13 the coke and 
hydrogen produced are greater than in test 12 and the gasoline yield is 
lower. 
EXAMPLE IV 
A commercial cracking catalyst comprising amorphous silica-alumina 
associated with zeolitic material, which had been used in a commercial 
cracking unit and subsequently subjected to regeneration in the 
laboratory, was employed in the preparation of cracking catalysts 
containing varying amounts of antimony, tin, or antimony and tin, the 
source of antimony being antimony tris(O,O-dipropyl phosphorodithioate) 
and the source of tin being dibutyltin bis(isooctyl mercaptoacetate). This 
compound has the formula: (n--C.sub.4 H.sub.9).sub.2 Sn(SCH.sub.2 CO.sub.2 
C.sub.8 H.sub.17 --iso).sub.2. Properties of the used cracking catalyst 
prior to regeneration in the laboratory are shown in Table VII. 
TABLE VII 
______________________________________ 
Surface area, m.sup.2 /g 
89.2 
Pore volume, ml/g 0.30 
Composition, weight % 
Silicon 26.5 
Aluminum 19.7 
Calcium 0.037 
Sodium 0.49 
Potassium 0.076 
Lithium 0.005 
Phosphorus 0.09 
Cerium 0.60 
Nickel 0.038 
Vanadium 0.11 
Iron 0.62 
Titanium 0.77 
Carbon 0.17 
______________________________________ 
The used commercial cracking catalyst having the properties shown in Table 
VII was then subjected to regeneration in the laboratory by heating the 
catalyst while fluidized with air to 1200.degree. F. (649.degree. C.) and 
maintaining it at that temperature for about 1 hour while fluidized with 
air. The catalyst was then cooled to room temperature (about 25.degree. 
C.) while fluidized with nitrogen, and the resulting regenerated catalyst, 
herein designated as catalyst Y, was employed as shown below. 
Portions of catalyst Y were used in the preparation of catalyst 
compositions containing, per 100 parts by weight catalyst Y, 0.01 part by 
weight antimony and 0.001 part by weight tin, and 0.02 part by weight 
antimony and 0.002 part by weight tin. The composition of lower antimony 
and tin concentration was prepared by adding, with stirring, to catalyst Y 
two cyclohexane solutions, one of which contained the calculated amount of 
dibutyltin bis(isooctyl mercaptoacetate) and the other of which contained 
the calculated amount of a mineral oil solution of antimony 
tris(O,O-dipropyl phosphorodithioate) containing 10.9 weight percent 
antimony, after which the resulting mixture was taken to apparent dryness 
on a hot plate. The composition of higher antimony and tin concentration 
was prepared by stirring with catalyst Y a cyclohexane solution of the 
calculated amount of dibutyltin bis(isooctyl mercaptoacetate), drying the 
mixture on a hot plate, stirring the resulting dried mixture with a 
cyclohexane solution containing the calculated amount of a mineral oil 
solution of antimony tris(O,O-dipropyl phosphorodithioate) containing 10.9 
weight percent antimony, and taking the resulting mixture to apparent 
dryness on a hot plate. 
Other portions of catalyst Y were used in the preparation of catalyst 
compositions containing 0.002 and 0.011 parts by weight tin per 100 parts 
by weight catalyst Y. In each of these two preparations a solution of the 
calculated amount of dibutyltin bis(isooctyl mercaptoacetate) in 
cyclohexane or toluene was stirred with catalyst Y, and the resulting 
mixture was taken to apparent dryness on a hot plate. 
Yet other portions of catalyst Y were used in the preparation of catalyst 
compositions containing 0.011 and 0.02 parts by weight antimony per 100 
parts by weight catalyst Y. In each of these two preparations the 
calculated amount of a mineral oil solution of antimony tris(O,O-dipropyl 
phosphorodithioate) containing 10.9 weight percent antimony, in 
cyclohexane, was stirred with catalyst Y, and the resulting mixture was 
taken to apparent dryness on a hot plate. 
Each of the six catalyst compositions above was conditioned in the 
following manner. The catalyst was placed in a laboratory-sized, confined 
fluid bed, quartz reactor and heated from room temperature (about 
25.degree. C.) to 900.degree. F. (482.degree. C.) while fluidized with 
nitrogen, then heated from 900.degree. F. (482.degree. C.) to 1200.degree. 
C.) while fluidized with hydrogen. While maintained at about 1200.degree. 
F. (649.degree. C.), the catalyst was then fluidized with nitrogen for 5 
minutes, followed by fluidization with air for 15 minutes. In one 
instance, the catalyst was again fluidized with nitrogen for 5 minutes 
while maintained at 1200.degree. F. (649.degree. C.). The catalyst was 
then aged through 10 cycles, each cycle being conducted in the following 
manner. The catalyst was cooled to about 900.degree. F. (482.degree. C.) 
during 0.5-1 minute, while fluidized with air, then fluidized with 
nitrogen while maintained at approximately 900.degree. F. (482.degree. C.) 
for about 1 minute, then heated to 1200.degree. F. (649.degree. C.) during 
2 minutes while fluidized with nitrogen and hydrogen, then maintained at 
1200.degree. F. (649.degree. C.) for 1 minute while fluidized with 
nitrogen, and then maintained at 1200.degree. F. (649.degree. C.) for 10 
minutes while fluidized with air. After these 10 aging cycles the catalyst 
was cooled to room temperature (about 25.degree. C.) while fluidized with 
nitrogen. 
The six aged catalysts prepared as described above and catalyst Y were 
evaluated in seven series of cracking-regeneration cycles, in which the 
cracking step was conducted over a range of catalyst:oil ratios, using 
about 35-37 g of catalyst as a confined fluid bed in a quartz reactor and 
employing as the feedstock in the cracking step a blend consisting of 
68.12 parts by weight gas oil, 11.98 parts by weight heavy cycle oil, and 
19.87 parts by weight slurry oil. In each cycle the cracking step was 
carried out at 950.degree. F. (510.degree. C.) and about atmospheric 
pressure for 0.5 minute, and the regeneration step was conducted at 
1200.degree. F. (649.degree. C.) and about atmospheric pressure for 
approximately 30 minutes using fluidizing air, the reactor being purged 
with nitrogen before and after each cracking step. 
The feedstock blend used in the cracking step had an API gravity at 
60.degree. F. (16.degree. C.), determined as shown in Table II, of 25.4. 
The values for API gravity at 60.degree. F. (16.degree. C.), determined by 
the same method, for the gas oil component, the heavy cycle oil component, 
and the slurry oil component of the feedstock blend were 27.3, 17.5, and 
2.2, respectively. Analysis of the gas oil component showed it contained 
0.99 weight percent sulfur and 0.133 weight percent nitrogen. 
Results of cracking tests conducted at various catalyst:oil ratios are 
summarized in Table VIII. All cracking tests carried out with a given 
catalyst are included except those which gave results which obviously were 
in error because of equipment malfunction or human error. Specifically, 
tests having a material balance outside of 100+5% were omitted. Tests with 
a given catalyst were made in the order in which they are listed. In each 
instance in which the catalyst was one which had been treated with tin, 
not more than 6 days elapsed between the time of preparation and 
conditioning of the catalyst and the time the first test was conducted, or 
between any two tests, including tests which were in error for the reasons 
noted above. FIGS. 8 and 9 show in graphical form comparisons of selected 
tests given in Table VIII, a series of at least five tests with a given 
catalyst composition at varying catalyst:oil ratios being curve-fitted to 
provide smooth curves as shown, and a pair of tests with a given catalyst 
composition at nearly constant catalyst:oil ratio being shown as single 
points, each of which represents the average of the values on which it is 
based. 
TABLE VIII 
__________________________________________________________________________ 
Catalyst, Wt. % Conversion, 
Yield 
Cracking 
Element Added 
Catalyst:Oil 
Vol. % Coke, H.sub.2, SCF/bbl 
Gasoline, 
Test Sn.sup.(1) 
Sb.sup.(2) 
Wt. Ratio 
of Feed 
Wt. % of Feed 
Feed Converted 
Vol. % of Feed 
__________________________________________________________________________ 
1A 0 0 7.01 54.0 5.5 163 44.9 
2A 0 0 6.07 52.7 4.7 156 45.0 
3A 0 0 4.98 47.8 5.0 140 42.0 
4A 0 0 9.02 57.6 7.0 159 49.9 
5A 0 0 5.07 51.7 4.8 112 44.4 
6A 0 0 4.55 48.2 4.4 113 41.7 
1B 0.002 
0 5.49 48.7 6.2 107 42.9 
2B 0.002 
0 5.51 50.4 6.6 111 46.6 
1C 0.011 
0 5.50 48.4 5.1 102 43.4 
2C 0.011 
0 5.50 47.1 5.3 126 43.0 
3C 0.011 
0 4.50 44.7 5.2 100 39.4 
4C 0.011 
0 5.00 51.6 4.6 123 44.6 
5C 0.011 
0 6.24 52.0 5.5 148 47.0 
6C 0.011 
0 5.00 48.9 5.9 135 43.5 
7C 0.011 
0 6.97 56.1 6.5 170 47.4 
8C 0.011 
0 7.98 61.0 7.8 111 46.1 
9C 0.011 
0 8.98 61.1 7.6 135 50.3 
10C 0.011 
0 4.51 47.4 4.5 113 41.6 
1D 0 0.011 
5.50 51.2 5.0 84 45.6 
2D 0 0.011 
8.03 56.6 6.4 120 50.3 
3D 0 0.011 
7.01 52.8 5.8 127 45.3 
4D 0 0.011 
6.24 55.3 5.1 125 46.9 
5D 0 0.011 
5.00 45.8 4.9 96 41.8 
6D 0 0.011 
4.50 45.7 4.4 79 39.6 
7D 0 0.011 
5.00 48.6 5.3 80 44.1 
8D 0 0.011 
8.99 59.8 7.1 111 50.0 
9D 0 0.011 
7.00 54.8 6.0 94 44.1 
10D 0 0.011 
5.49 49.5 5.3 82 46.0 
11D 0 0.011 
6.22 55.4 5.5 80 47.6 
1E 0 0.02 
5.58 52.2 5.0 88 43.2 
2E 0 0.02 
5.46 54.4 4.6 73 45.1 
1F 0.001 
0.01 
5.53 54.3 5.2 131 48.6 
2F 0.001 
0.01 
5.48 47.9 4.0 103 43.8 
3F 0.001 
0.01 
8.02 58.4 7.3 80 51.2 
4F 0.001 
0.01 
7.02 58.7 5.3 107 51.6 
5F 0.001 
0.01 
8.98 58.6 7.7 75 49.5 
6F 0.001 
0.01 
6.24 56.7 6.7 82 46.0 
7F 0.001 
0.01 
5.00 47.7 5.1 73 44.6 
8F 0.001 
0.01 
5.00 49.5 4.9 95 45.6 
9F 0.001 
0.01 
5.49 50.9 6.2 64 43.1 
10F 0.001 
0.01 
6.01 52.2 5.9 61 46.2 
11F 0.001 
0.01 
4.48 46.0 5.2 78 39.3 
1G 0.002 
0.02 
6.99 53.6 4.9 123 43.8 
2G 0.002 
0.02 
5.49 48.2 4.7 103 44.6 
3G 0.002 
0.02 
6.23 50.5 5.4 104 46.6 
4G 0.002 
0.02 
8.03 57.1 7.2 158 47.7 
5G 0.002 
0.02 
9.02 59.4 6.5 115 50.0 
__________________________________________________________________________ 
.sup.(1) Based on weight of catalyst prior to addition of tin as 
dibutyltin bis(isooctyl mercaptoacetate) and prior to addition of 
antimony, if any. 
.sup.(2) Based on weight of catalyst prior to addition of antimony as 
antimony tris(0,0dipropyl phosphorodithioate) and prior to addition of 
tin, if any. 
On the basis of the same reasoning applied in Example III. FIG. 8 shows 
that the catalyst containing 0.002 part by weight tin and 0.02 part by 
weight antimony per 100 parts by weight catalyst prior to treatment with 
the tin and antimony compounds produces a surprisingly low level of coke 
at a low catalyst:oil weight ratio, e.g., 5.5:1. Much more strikingly, 
FIG. 9 shows that the catalyst containing 0.001 part by weight tin and 
0.01 part by weight antimony per 100 part by weight catalyst prior to 
treatment with the tin and antimony compounds produces a surprisingly high 
yield of gasoline at catalyst:oil weight ratios of about 5 to about 9, an 
unexpectedly high conversion of feed at intermediate catalyst:oil weight 
ratios, and a surprisingly low level of hydrogen at catalyst:oil weight 
ratios in the range of 6 to 9. 
EXAMPLE V 
This calculated example is given to indicate how the invention can be used 
on a plant scale in a presently preferred embodiment. In a commercial 
cracking unit containing 200 tons of cracking catalyst, 24,300 bbl/day of 
oil having an API gravity of 20.8 are cracked. To build up on the cracking 
catalyst levels of 0.15 weight percent antimony and 0.015 weight percent 
tin, based on untreated cracking catalyst, antimony tris(O,O-dipropyl 
phosphorodithioate) is added to the feedstock in an amount such as to 
provide 6 ppm antimony, and dibutyltin bis(isooctyl mercaptoacetate) is 
added to the feedstock in an amount such as to provide 0.6 ppm tin, each 
for 17 days. Alternatively, for 10 days to the feedstock are added 
antimony tris(O,O-dipropyl phosphorodithioate) in an amount such as to 
provide 9 ppm antimony and dibutyltin bis(isooctyl mercaptoacetate) in an 
amount such as to provide 0.9 ppm tin. To keep the antimony level at 0.15 
weight percent and the tin level at 0.015 weight percent, addition of the 
antimony and tin compounds to the feedstock then has to be maintained at 
rates such as to provide a feedstock containing 3 ppm antimony and 0.3 ppm 
tin, if 8 tons of catalyst per day are withdrawn from the cracking reactor 
system and replaced by untreated catalyst. If only 6 tons of catalyst per 
day are replaced, this addition would be sufficient to keep the antimony 
and tin levels of the catalyst system at 0.195 weight percent and 0.0195 
weight percent, respectively. This means that 652.5 pounds of a mineral 
oil solution of antimony tris(O,O-dipropyl phosphorodithioate), this 
solution having an antimony content of 11 weight percent, and 39.65 pounds 
of commercial dibutyltin bis(isooctyl mercaptoacetate) having a tin 
content of 18.1 weight percent have to be added, per day, to the feedstock 
for 10 days (435 pounds and 26.41 pounds, respectively, for 17 days) to 
achieve the specified levels of antimony and tin on the catalyst. In order 
to maintain these specified levels, 217.5 pounds of this mineral oil 
solution of antimony tris(O,O-dipropyl phosphorodithioate) and 13.26 
pounds of the commercial dibutyltin bis(isooctyl mercaptoacetate) have to 
be added, per day to the feedstock. 
Reasonable variations and modifications, which will be apparent to those 
skilled in the art, can be made in this invention without departing from 
the spirit and scope thereof.