CA1051411A

CA1051411A - Cracking catalyst and cracking process using same

Info

Publication number: CA1051411A
Application number: CA202,263A
Authority: CA
Inventors: Albert B. Schwartz
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1973-09-20
Filing date: 1974-06-12
Publication date: 1979-03-27
Also published as: IT1022123B; DE2444911A1; NL176084C; AU497439B2; AR212419A1; DE2462866C2; GB1481563A; NL176084B; DE2462867C2; JPS5057092A; AU7350774A; NL7412423A; FR2257673A1; DE2444911B2; JPS5415038B2; FR2257673B1

Abstract

CRACKING CATALYST
AND CRACKING PROCESS USING SAME

ABSTRACT OF THE DISCLOSURE
Operation of regenerators of commercial equipment for catalytic cracking of hydrocarbon feedstock, such as gas oil, in the absence of added hydrogen is improved considerably by use of a cracking catalyst which contains a minute amount, as low as fractions of a part per million (ppm), of a metal from periods 5 and 6 of Group VIII of the Periodic Table or rhenium. These powerful dehydrogenation metals, in the amounts here used, do not have serious adverse effect on the cracking operation and reduce CO content of flue gases from the regenerator to negligible amounts.

Description

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1. Field of the Invention The invention is concerned with improving operations in cracking of hydrocarbons in the absence of added hydrogen.
Characteristically, commercial equipment ~or this purpose involves a cracking reactor and a regenerator with continuous circulation of catalyst through the two vessels. Particularly significant advantages are achieved in Fluid Catalytic Cracking (FCC) with zeolitic catalyst. The invention has no applicability to hydrocracking using a fixed bed of catalyst and an excess of added hydrogen.

2. Discussion of the Prior Art Two general types of catalytic cracking process are currently in commercial use. Thermofor C~talytic Cracking (TCC) i5 uses a moving compact bed of catalyst in both reactor and regenerator. Catalyst which has become relatively inactive by deposition of a carbonaceous deposit commonly called "coke"
is continuously withdrawn from the bottom o~ the reactor in .. . .
~ which gas oil is cracked by contact with the catalyst at 2~ elevated temperature. The spent catalyst from the reactor is passed to the top of a regenerator in which activity of catalyst ~1 `; i8 restored by burning the coke in air. Hot regenerated catalyst from tha bottom of the regenerator is continuously .: .
returned to the top of the reactor to repeat the cycle first described.
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In Fluid operations, the catalyst follows a similar c:rculation but is "fluidized" in both reactor and regenerator by upwardly flowing gases in each, hydrocarbon vapor in the reactor and in the regenerator.
The major di~ference in c~talyst f~r the two processes is particle size. Pellets or beads of about 1/8" diameter are employed in TCCo Fine powders, with an average particle size of about 70 microns, are used in FCC.
Both types of process are operated at pressures from 1~ atmospheric to about 40 psig. Hydrogen is produced in small amounts by the cracking reaction, but no hydrogen is added as such to the reactors of TCC and FCC Units. This cracking in the absence of added hydrogen is endothermic, as contrasted with the exothermic character of hydrocracking with a catalyst which contains signi~icant amounts of hydrogenation metal (upwards of 0.5 wt.%) and in the presence of large excess o~
added hydrogen, as described in U.S. 3,173,854.
In general, potent hydrogenation metals are avoided in TCC and FCC catalysts. A serious problem for these catalysts ~20 is recognized in cracking o~ stocks which contain metals.
Particularly disadvantag~sis deposition o~ the Group VIII
metal nickel. Amounts of nickel on the order of 0.03 w~ %
' ~ on catalyst will increase the hydrogen make to a level which ,~ causes severe problems in handling of the dry gas from TCC
.1 ^Z5 and FCC operations.
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The catalysts employed in FCC and TCC have included acid treated clays, amorphous silica-alumina composites and the like. Many variants, such as silica-zirconia, silica-magnesia and other acidic porous solids have been described in the literature.
More recently, very effective catalysts have been prepared by blending a major portion of the older amorphous catalysts with a minor portion of an active crystalline aluminosilicate zeolite. Typical catalysts of this type for FCC and TCC are described in U.S. Patents 3,140,249 and 3,140,253.
In FCC and TCC a problem arises from incomplete combustion, leaving a significant amount of carbon monoxide (CO) in the flue gas. Aside from the undesir-ability of discharge of CO to the atmosphere, such flue gases tend to burn (by reaction of CO with residual ; oxygen in the flue gas) in ducts and flues of the plant, damaging these structures by excessive temperatures.
It has been proposed to alleviate the CO
problem in TCC by adding a small amount of chromic oxide to the catalyst. This causes some impairment of gasoline yield, but that effect is tolerable in combatting the CO problem. See U.S. Patent 2,647,860.
It has also been proposed to incorporate in a cracking catalyst a zeolite containing within its internal pore structure a CO oxidizing catalyst, the pores being too small to admit charge molecules but large enough to admit CO. See U.S. Patent 3,364,136.

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10514~1 It has also been proposed to incorporate in a cracking catalyst a zeolite containing within its international pore structure a CO oxidizing catalyst~
the pores being too small to admit charge molecules but large enough to admit CO. See U.S. Patent 3,364,136.

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SUMMARY OF THE INVENTION
The present invention relates to a cracking catalyst in the form of particles suitable for use in a moving-bed or fluidized-bed cracking unit for use without hydrogen. The catalyst includes at least one component catalytically active for the cracking of mixed hydrocarbon feedstock in the absence of added hydrogen and has an average pore size sufficiently large to admit benzene. According to the novel feature, the catalyst further comprises a metal component which is at least one metal selected from Periods 5 and 6 of Group VIII
of the Periodic Table and rhenium, or a compound of at least one such metal, the metal component being accessible to the feedstock. These powerful dehydrogenation metals in amounts to exert any significant catalytic oxidative effect would be expected to dehydrogenate hydrocarbons, yielding unsaturates which are known to be coke pre-cursors. Surprisingly, when the specified metal components are added to FCC and TCC catalysts in amounts of a trace up to 50 ppm or less of total catalyst weight calculated as metal, coke make is not significantly increased. At the lower levels of metal addition, hydrogen make, as measured by the "hydrogen factor" commonly employed in FCC, is slightly increased. Greater amounts of metal component within the scope of the invention raise the hydrogen factor, but wlthin tolerable limits. Preferable catalysts are produced by addition of 0.1 to 50 ppm of metal component.
For the purpose of this invention, the terms "metal component" or "added metal component" shall mean either the metal itself or a metal ion or a metal compound, such as the oxide, sulfide, halide, sulfate, or other ;

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combined form r~sulting from adding the metal or metal compound to the catalyst.
It is surprising to find that such materials, `
although accessible to char~e stock molecules, exert no adverse effect when used in the quantities prescribed by the invention.
The catalyst of this invention containing the added metal component shows particularly spectacular reductions in CO content of flue gases from FCC units as evidenced by an improved CO2/CO ratio over the cracking catalyst containing no added metal component. The metal components are of particular benefit in catalysts containing silica, alumina, magnesia, zirconia, clay and combinations thereof. They are found to be of particular benefit in a composite catalyst of active crystalline aluminosilicate zeolites in a porous matrix, such as a clay-derived matrix.
Other types of matrices include silica, alumina, magnesia, zirconia, and mixtures of these.
The zeolites employed in such composite catalysts are those capable of admitting the charge stock molecules to be cracked, a condition which is satisff ed by their having pore openings sufficiently large to admit the benzene molecule. The zeolites most widely used for the purpose commercially have been zeolites X and Y, which have pore openings of about 8-9 Angstrom Units. Zeolites having pore openings of less than about 6 Angstrom Units will not admit benzene and are therefore not employed for the conversion of conventional cracking stocks.
According to the present invention, a cracking 3~ catalyst, for use without added hydrogen, comprising one or ~, ~ ~ - 6 -; ' ~
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'105i4~1 more catalytically active components each having a pore size sufficiently large to admit benzene, which catalyst further comprises in association' with at least one of said compounds, at least one metal selected from Periods 5 and 6 of Group VIII of the Periodic Table and rhenium, or a compound of at least one such metal, the quantity of such metal or compound being up to 50ppm of total catalyst weight calculated as metal.
The metal component may be incorporated into the catalyst by impregnation, by ion exchange or by other means by contacting either the catalyst or the component thereof with a solution of a compound of the metal in an appropriate amount necessary to provide the desired concen-centration within the scope of the invention. The metal component may be incorporated either in any step during preparation of the catalyst or after the finished catalyst has been prepared. A preferred manner of incorporation is to ion-exchange a crystalline aluminosilicate and then composit-ing the ion-exchanged product with a porous matrix. Also use~ul is the ion-exchanging or impregnation of siliceous Bolids F cleys. Su~table met~l ~: :
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compounds ~nclude the metal halides, preferably chlorides, nitrates~ ammine halides , oxides, sulfat~s , phosphates and ~:
: other wa~er-soluble inorganic salts; and also th~ met~l -csrboxylates of from 1 to 5 carbon atoms, alcoholates.
Specific examples include palladium chloride, chloroplatinic acid, rutheniwm penta-ammine chloridç, osmium chloride , . perrhenic acid, dioxobis(ethylenediaminè)rhenium(V) chloride, ¦ rhodium chloride and the like.
¦ Alternatively, an oil-solubls or ~il-dispersable ~10 compound o~ the metal may be added in suitable amount to a hydrocarbon feedstock, such as a gas oil charge stock, for ~ incorporation in the catalyst as the cb~rge is cracked. Such 1 compounds include metal diketonates, carbonyls, metallocenes . .olefin complexé$ of 2 to 20 carbons, acetylene complexes, aIk 15 . or aryl phosphine complexes and carboxylates of i to 20 carbons~
Specific examples of these are platinum acetylacetonate, ..
. tris(acetylacetonato)rhodium(III), triiodoiridium(III) . tricarbony~ -cyclopentadienylrhenium(I) tricarbonyl,.
¦ . ruthenocene, ~-cyclopentadienylosmium(I) dicarbonyl dimer, 120 dichloro(ethylene)palladium(II) dimer, .(~-cyclopentadienyl) , . (ethylene)rhodium(I?, diphenylacetylenebis(triphenylphosphino)-~ . . platinum(0), ~romomethylbis(triethylphosphino)palladium(II), i . .
' tetra~is(triphenylphosphino)palladium(0), chlorocarbon~lbis-; (tri~henylphosphino)iridium(I), palladium acetate, and .~, . . .
-l25 - pallad~um naph~henate.

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¦ Regardless of ~he methæ of incorporating the metal component in the catalyst~ impro~d results have been obtained.
The feedstocks which ~ay be cracked using the catalysts of this invention include any conventional hydrocarbon ~tocks, such as naphthas, ~as oil, light and heavy distilla es, residual oils and the like.

¦ 215 cc of an aqueous Pd(N03)2 solution containing 0.0103 g Pd/liter were added to 222 ~, bone dry basis, of a caicined RENaY containin~ 16.1 wt. ~ R ~ 03 and 2.7 wt. % Na to provlde 0.001 wt. % (10 ppm) Pd. The zeolite was calcined at j 1200F. for 1 hour. The zeolite (10 wt~ %) was incorporated in a matrix (90 wt. %) consisting of 40 wt. ~ Georgia kaolin~ 57.4 - wt. % SiO2, o.6 wt. % A1203, and 2 wt. ~ ZrO~ to provide 1 ppm palladlum in the composite catalyst. The matrix was prepared by mixing water, kaolin, Q-Brand sodium-silicate (28.9 wt. %
SiO2, 8.9 wt. % Na20, and 62.2 wt. % H20), aluminum sulfate~
~odium zirconium sulfate, and sulf~ic acid. The mixture was spray dried and the catalyst was exchanged w~th an aqueous - 5 wt. % (NH4)2 S04 solution, washed, and impregnated with an Yl¦ `` a~ueous 7 wt. % REG13-6H20 solution, The catalyst was then ~,~i, dried in an oven at about 250F. and a portion of it wàs ; steamed for 4 ho~rs at 1400 F. and O psig, the heat~ng to 1400F be~ng carried ou~ in a ~2 atmosphere.

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215 cc of an aqueous H2PtC16 solution containing 0.0103 g Pt/liter were added to another 222 g portion of the ~ calcined RENaY cf Example 1 to provide 10 ppm platinum. A
catalyst was then prepared by the same procedure as in Example 1.
The cracking performances of the catalysts of Examples 1 and 2 were determined. A wide-cut Mid-Continent gas oil feedstock was cracked at 925F. at a catalyst-to-oil ratio of 3 by wt., 8.3 WHSV, catalyst residence time 2.4 minutes' the results were:

Ex. Ex.
Catalyst (Example) 1 2 Blank*
Conversion,~vol.74.4 70.7 72.1 C + Gasoline,~vol. 65.o 63.0 64.3 ~tal C4's,S~vol.14.4 12.6 13.3 Dry Gas,7~wt. 6 . 4 5 . 6 5 . 6 Coke,%wt. 2.5 2-.3 2.3 Carbon on Cat.,%wt. 0.-71 o.65 o.65 Hydrogen Factor ** 39 27 30 .. .
* Catalyst without added metal component.
** 100 x [moles H2/moles Cl + C2~
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` The two catalysts were sub~ected to regeneration in two successive stages. The conditions of each stage of ~;~25 regeneration were as follows; Air was passed over the catalyst at a rate of 25 cc/min.~gram of catalyst at 1000F. and - atmospheric pressure for 8 minutes, and the gas was collected.

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The results were as follows:

First Stage Ex. 1 Ex. 2 Blank*
C02, mol ~ 3.5 5.2 4.o C0, mol % 2.7 3.2 C02/CO 1.3 ov 1.3 Inltial Carbon,%wt. 0.71 o.65 Final Carbon,%wt. 0.42 0.43 Second Stage C02, mol % 2.0 2.7 2.~
C0, mol % 1.2 0 1.7 C0~/C0 1.7 ~ 1.4 In~tial Carbon,~wt 0.42 0.43 Final Carbon,%wt. 0.28 0.26 ,, ' .
* Catalyst without metal component.
;f' An RENa~ (222 g) was prepared in the same manner as in Example 1, except that it was uncalcined. Thereafter, 163 cc ;,1! of an aqueous H2PtC16 solution containing 0.0137 g Pt/liter were l added to provide 0.001 wt. % (10 ppm) platinum. A composite f~Z0 catalyst containing 1 ppm platinum was then prepared by the same procedure as in Example 1.
Cracking data, using the same feedstock as in the ` previous examples and under the same conditions, and regeneration data under the same conditi~ns as in the previous examples ~25~ were as follows:

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Catalyst Ex. 3 Blank Conversion, % voL 76.`2 74.4 Coke, % wt. 3.0 2.4 Carbon on Cat.,~w~ o.84 o.69 Hydrogen Factor29 17 P~egenerationStage 1 Stage 1 C02, mol % 8.3 3.3 C0, mol % o.6 3.0 co2/co~ ` 13 1 . 1 Final ~, % wt.o.56 o.56 Stage 2 Stage 2 ; C02, mol ~ ~.7 1.6 C0, mol % ~ 0.1 1.4 C02/C0 ~47 1.1 Final C, % wt. 0.44 , Th~ increased C02/C0 mole ratio with the presence o~ only 1 ppm of platinum clearly illustrates the advantage of the metal component in the catalysts of this invention.
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i EXAMPLE 4 ~20 A rare-earth exchanged zeolite Y (15.8 wt. % RE203, .7% Na) was slurried with an aqueou~ solution containing ~Pt(NH3)6]C14. The resulting platinum-containing zeolite was filtered, dried at 250F., and calcined at 1200~F. for one ~; ` hour. The resulting zeolite was incorporated in a matrix as described in Example 1 to give a finished cracking catalyst containing 10% of the zeolite by weight to which 1 ppm platinum had been added. A blank catalyst ~as prepared similarly, the ~Pt(NH3)6]C14 being eliminated from the zeol~te slurry.

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~(~514~1 Both catalysts were heated to 1400F and steamed as in Example 1, used to crack the feedstock of Example 1 and regenerated under the conditions of Example 2. The results were as follows:
S Ex. 4 Blank Conversion, % vol.76.1 73.9 Coke, % wt. 2.8 2.5 Caxbon on Cat., % wt. 0.82 0.73 Hydrogen Factor 19 16 Reqeneration Staqe 1 Staqe 1 C02, % mol 5.9 3.3 C0, % mol 0.15 1.7 C02/C0 39 1.9 A commercial cracking catalyst consisting of 15% REY
and 85% matrix of 57.4% silica, 0.6% alumina, 40% clay and 2.0% zirconia, which had been spray dried, exchanged with ammonium nitrate and water-washed, was slurried with an - aqueous solution of rare earth chloride and Pt(~H3)4C12 ~ufficient to provide 3% R~203 and 2 ppm platinum to the finished catalyst. The catalyst was spray dried, heated in nitrogen, then steamed for 4 hours at 1400F. A blank catalyst without platinum was prepared and treated similarly, Pt(NH3)4C12 being omitted from the slurry.
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Both catalysts were used to crack the same feedstock ~; as in Example 2 and regenerated under the conditions of Example 2. The results were as follows:

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~Q514~1 Ex. 5 Blank Conversion, ~ vol. 79.5 78.8 Coke, % wt. 3.3 3.1 Carbon on Cat.,~wt 0.945 o.884 Hydrogen Factor 15.8 12.1 i Regeneration Stage 1 Stage 1 C02, mol % 8.2 4.2 C0, mol % 1.2 3.4 C02/C0 6.8 1.2 Stage 2 C02, mol % 5.7 ; C0, mol % 0.25 .
A number of metals of the platinum group and rhenium were used to treat a catalyst containing 15% REY silica-alumina-clay-zirconia matrix (similar to that of Example 5).
Solutions of the metal salts of appropriate concentration were added to the catalyst until it was wet. The finished catalyst was dried at 250F. for 24 hours, heated in nitrogen at ` 1400F. over 3 1/2 hours and steamed ~or 4 hours. The metal salts were the chlorides o~ iridium, osmium and rhodium, and [Ru(NH3)5C12]C12, rhenium di(ethylene di~mine) dioxide chloride, . ,~ ~
Pt(NH3)4C12 and Pd(N03)2. A total amount o~ metal equal to -25 ~ 3 ppm was so supplied. After the cracking of a wide-cut Mid-Continent gas oil ~eed and regeneration studies as in ~ Ex~mple 2, the following results were obtained:

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~, - 14 -,~ . , - lQ514~1 In this example, equili~rium catalyst withdrawn from a commercial FCC unit was used. A wide-cut Mid-Continent gas oil stock was cracked at 929F., 3 catalyst-oil ratio ratio, 2.4 minute catalyst residence time. The catalyst was regenerated in place in 2 stages under the conditions of Example 2. Then, the same gas oil, but now containing platinum acetylacetonate dissolved therein in su~ficient quantity to provide 1 ppm platinum on the catalyst, was int~ duced into the cracker at the same conditions, except slightly higher temperature. The c~talyst was regenerated again. Then the platinum-containing ~eed was again cracked over tne same catalyst, and again the cataly~t was regenerated. The ~ollowing results were obtained:

Gas Oil Gas Oil Cracking Feed Gas Oil & Pt & Pt -Cycle 1 2 3 Temperature, F.929 936 926 Conversion, % vol. 56.5 57-.3 50.4 Coke, % wt. 2.3 ~.4 2.~
Carbon on Cat.,%wt o.67 o.67 0.67 Hydrogen Factor25 29 31 Regeneration Sta~e 1 i Co2, % mol 3.2 5.1 5.6 CO, % mol 2.7 0.18 o.lo co2/co 1.2 28 56 ., ~ .
Estimated Pt on Catalyst at end of Cycle~ ppm O 1 2 Ç ~ ~ , ~ ; The catalyst contained rare earth exchanged Y zeolite as the $~ smallest pore-sized ingredient.
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A commercial amorphous silica-alumina fluid cracking catalyst consisting of 13% A1203, ~% SiO2 was impregnated with an aqueous solution of Pt(NH3)~C12, oven-dried at 250F, S then heated and steamed at 1400F as in Example 1. The amount of platinum compound supplied was equivalent to 3 ppm of the metal. The catalyst without metal addition (blank), similarly treated, and the platinum-containing catalyst were used in the fluid cracking of the Mid-Continent gas oil stock, and then regenerated under the conditions of Example 2. The results were as follows:
CatalYst Ex. 8 Blank Conversion, % vol. 35.8 35.6 Coke, % wt. 1.82 1.54 Carbon on Cat., % wt. 0.52 0.44 Regeneration Staqe 1 C02, % mol4.8 2.2 C0, % molc 0.05 1.2 C02/CO ~ 96 1.8 ' EXAMPLE 9 Moving bed catalysts are also improved by the presence of the added metal component of this invention.
(a) A blank catalyst was prepared by incorporating 7.5% of the calcined rare-earth exchanged zeolite Y of Example 4 and ., 0% alumina fines in a silica-alumina matrix (93.6% SiO2, ~.4% A1203) by the bead technique described in U.S. Patent ,. : I
~ 3,140,249. After base-exchange and washing, the hydrogel ,1, 1 .
i~ beads were dxied in pure steam of atmospheric pressure at .

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105i4 'I ~, j 270F. fe; 15 minutes, then at 340 F. for 15 minutes. The dried catalyst ~as finished by a 14-hour steam treatment at , 1290F. wi th lO~,~o steam at atmospheric pressure. This blank catalyst ~las used in static bed cracking of a Mid-Continent ~ gas oil at 875F.~ a liquid hourly ~pace velocity of 3 and ~
¦ catalyst/oil ratio of 2 with 10 minutes on stream. The spent catalyst was regenerated and the C02/CO ratio determined.
(b) Rare-earth exchan~ed zeolite Y rilter cake, 1530.6 g, containing 49.0~ = 750 g of solids, was mulled wlth 160 cc o~ a H2PtC16 solution containing 10.03 mg of Pt until uniform~
- then dried at 250F. and calcined at 1200F. for 3 hours. The product oontained l3.4 ppm of platinum designed to provide : 1 ppm o~ platinum to the catalyst after combination with the . ~ .
matrix. The preparation of the ca~alyst was completed as above.
(c) The blank zeolite-matrix bead hydrogel was treated for i ,........ . ..
hour with sufficient Pt(NH3)4C12 solution to supply l ppm o~
, platin~m based on the finished catalyst.
(d) The calcined ze~lite of para~raph (a) was used to prëpare ' . _. .
a catalyst slmilar to that described in (a) except that the matrix contained about 2200 ppm of cogelled Cr203.
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¦ These catalysts were also used in cracking the said éedstoc~ at the same conditions, and wer~ regenerated at , I .
;~ the conditions of Example 2. The foll~wing results were obta~ned: -1~ . .. . . ,-! 1 -.., ~- - -17- -,. . -' "' , ' . ' . ` ~.
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1(~51411 Catalyst (a) (b) (c) (d) Conversion,~vo~ 68.8 69.3 70.4 70.9 Coke, % wt. 2.9 3.2 3.1 3.2 Regeneration -C02, % mol 5.5 7.3 8.3 5 4 C0, % mol 4.8 0.4 0.2 5 0 C02/C0 1.1 18 42 1.1 A commercial clay-derived aluminosilicate zeolite cracking catalyst, containing about 55~ by weight of alumina and about 45% by weight o~ silica and having an average particle 8~ ze of between 58 and 64 mlcrons, was employed in this example. A 1000 gram sample was mixed with 3500 cc of a ~olution containing 58.4 grams of REC13-6H20 and 2.7 mg of Pt ~s platinum trls(ethylene diamine) tetrachloride. After etirring for 30 minutes at 75C. the catalyst was filtered out, water-washed and dried at 2500F. The catalyst contained 3 ppm p~atinum and 3~ by weight o~ rare earth oxide. Another sample of the same clay-derived catalyst ("Blank") was treated similarly~
~-~20 but without the platinum although with a slightly higher rare earth concentration present in the solution. The final c~talyæt contained 4.2% by weight of rare earth oxide. Both catalysts `~ were steamed and tested for cracking performance as in ~ ~ Example 2.
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A portion of each coked ~atalyst from the test was blended with'uncoked steamed catalyst so that the carbon level o~ the~mixture was o.65% by weight. Regeneration was conducted at 13~0F. and atmospheric pressuring using 1.38 moles of oxygen per le of c~rbon and the gas was collected. The following data ~30 were obtained;

1~514~l1 .1 ¦ Regenerat~oll _Y~. 10 Blflnk C~2, ~ mol 9.1 7.6 ! . CO~ ,~> .. iC~ I O.3 3.6 ,I, , , C02/C0 3 2.1 !
'5 EXAMPLE 11 The catalyst of Example 4, containing 1 ppm of platinum was calcined at 1200F. in N2 for 3 hours. A
, wide-cut Mid-Continent gas oil feedstock was cracked over this - catalyst at 910F. at a catalyst to oil ratio of 2.0 by weight, lo 12.5 WHSV and catalyst residence time of 2.4 m1nutes.
The coked catalyst from this run was blended in ~ari,ous con~entratlons with an equilibrium commercial zeolitic , .- .... . .. .. . ..
, ~, cataly~t withdrawn from a commercial FCC unit. This catalyst I " ' ' . .
wh~ch contained no platinum had been regenerated and then ' ~5 ' used to crack the same gas oil feedstock as in -Example 1 under ~, , 'the ~ame conditions. ` ' ' , ' The variously blended coked catalysts were , regenerated under the same conditions as in Example 2. The ' results are as follows: - ' ' Pt-Containing , ~ `' Ca,talyst Estimated in Blend, Pt in C02 C0 . % by wt. , Blend, ppm % mol % mol C02/C0 ' , 0 o 5.7 5.0 1.1 "~ 1 0.01 4.6 2.4 ''1.8 - ; 2 0.02 4.8 2.4 1.9 ' 4 o.o4 4.4 2.3 1-9' ' . 20 0.20 6.7 o.6 11 ~ 5 0.50 6.1 o.68 9.0 'J~,,30 ', 100 1.0 8.1 1.3 ~.2 '' The catalyst contained rare earth exchanged Y zeolite as the ~ i m smallest pore-sized ingredient.

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This experiment indicates that even at concentrations as low as 0.01 ppm of added metal component, the C02/C0 ratio is increased during regeneration.
The catalyst with added metal component may even contain an amount of metal component greater than that of the ultimate cracking catalyst mixture, such as for example but not necessarily 100 ppm, provided that either in the use of the catalyst for cracking or in the regeneration of used catalyst it is blended with cracking catalyst containing less or no metal com~onent at sufficient concentrations to reduce the total added metal component to a concentration ; below 100 ppm.
It may thus be seen from the results of the cracking operations and subsequent regeneration data that the catalysts of this invention are just as effective in hydrocarbon con-version as conventional cracking catalysts. However, in the regeneration step, the C02/C0 effluent ratios are extra-~' ordinarily higher than catalysts without the added metal ~i~ component. The type of catalyst, feedstock or manner of introducing the new component do not destroy the effective-ness in regeneration efficiency.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A cracking catalyst in the form of particles suitable for use in a moving-bed or fluidized-bed crack-ing unit for use without added hydrogen, comprising at least one component catalytically active for the cracking of a mixed hydrocarbon feedstock in the absence of added hydrogen and having an average pore size suf-ficiently large to admit benzene, which catalyst further comprises a metal component which is at least one metal selected from Periods 5 and 6 of Group VIII of the Periodic Table and rhenium, or a compound of at least one such metal, the quantity of such metal or compound being from a trace amount up to 50 ppm of total catalyst weight calculated as metal, said metal component being accessible to said feedstock.

2. The catalyst of claim 1, wherein the quantity of said metal or compound is from 0.1 ppm to 20 ppm.

3. The catalyst of claim 1 wherein the quantity of said metal or compound is from 0.1 to 15 ppm.

4. A catalyst according to claim 1, 2 or 3, which comprises the metal component and a silica in com-bination with at least one of alumina, magnesia, zirconia, and clay.

5. A catalyst according to claim 1, which comprises the metal component and a crystalline alumino-silicate zeolite in a matrix of at least one of silica, alumina, magnesia, zirconia, and clay.

6. A catalyst according to Claim 5, wherein the said zeolite and the matrix are both derived from a clay.

7. A catalyst according to Claim 5, wherein the metal component is platinum, palladium or a compound of either.

8. A catalyst according to claim 5, 6 or 7, wherein the crystalline aluminosilicate has been exchanged with ions of at least one rare earth metal.

9. A catalyst according to claim 1, wherein the metal component has been incorporated by ion-exchange.

10. A catalyst according to claim 9, wherein the metal component has been incorporated by ion-exchange in a crystalline aluminosilicate zeolite and the resulting exchanged product is combined with a porous matrix.

11. A catalyst according to claim 1, wherein the metal component has been incorporated by impregnation with a solution of a compound of the metal.

12. A catalyst according to claim 1, wherein the metal component has been deposited on the catalyst from a hydrocarbon feedstock being subjected to cracking conditions.

13. A process for the cracking of a mixed hydrocarbon feedstock which comprises subjecting said feedstock to cracking conditions in the absence of added hydrogen in the presence of particles of a moving-bed or fluidized-bed cracking catalyst comprising at least one component catalytically active for the cracking of a mixed hydrocarbon feedstock in the absence of added hydrogen and having an average pore size sufficiently large to admit benzene, which catalyst further comprises a metal component which is at least one metal selected from Periods 5 and 6 of Group VIII of the Periodic Table and rhenium, or a compound of at least one such metal, the quantity of such metal or compound being from a trace amount up to 50 ppm of total catalyst weight calculated as metal, said metal component being accessible to said feed-stock.

14. A process according to claim 13,in which the catalyst is fluidized.

15. A process according to claim 13, in which the catalyst is in the form of a moving bed.

16. A process according to claim 13, wherein the catalyst has been formed by deposition from a hydrocarbon feedstock of a metal compound soluble or dispersible in the hydrocarbon feedstock, on particles of a cracking catalyst in use in a fluidized-bed or moving-bed cracking unit.

17. A process according to claim 16, wherein said metal compound is selected from metal diketonates, metal carbonyls, metallocenes metal-olefin complexes of 2 to 20 carbon atoms, metal acetylene complexes, metal complexes of alkyl or aryl phosphines and metal carboxylates having from 1 to 20 carbon atoms.

18. A process according to claim 16 or 17 wherein the metal compound is platinum acetylacetonate.