Process and compositions for Mn containing catalyst for carbo-metallic hydrocarbons

Abstract

An improved "magnetic hook"-promoted catalytic process, catalyst and method of manufacture for heavy hydrocarbon conversion, optionally in the presence of nickel and vanadium on the catalyst and in the feed stock to produce lighter molecular weight fractions, including more gasoline, lower olefins and higher isobutane than normally produced. This process is based on the discovery that two "magnetic hook" elements, namely manganese and chromium, previously employed as magnetic enhancement agents to facilitate removal of old catalyst, or to selectively retain expensive catalysts, can also themselves function as selective cracking catalysts, particularly when operating on feeds containing significant amounts of nickel and vanadium, and especially where economics require operating with high nickel- and vanadium-contaminated and containing catalysts. Under such conditions, these promoted catalysts are more hydrogen and coke selective, have greater activity, and maintain that activity and superior selectivity in the presence of large amounts of contaminant metal, while also making more gasoline at a given conversion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Cross references to related application, U.S. patent application Ser. No. 08/326,982, filed Oct. 21, 1994 relates to the general field of the present invention.

BACKGROUND OF THE INVENTION

I. Field of the Invention

This invention relates to the field of adding manganese to hydrocarbon cracking catalysts, generally classified in Class 208, subclass 253 of the U.S. and in International Class C10G-29/D4.

II. Description of the Prior Art

U.S. Pat. No. 4,412,914 to Hettinger et al. is understood to remove coke deposits on sorbents by decarbonizing and demetalizing with additives including manganese (claim 4, column 26).

U.S. Pat. No. 4,414,098 to Zandona et al. uses additives for vanadium management on catalysts (column 15, line 6).

U.S. Pat. No. 4,432,890 to Beck et al. mobilizes vanadia by addition of manganese, inter alia, Table A; column 9, line 35-48; column 10, line 40; and column 27, line 3; Table Y; etc.

U.S. Pat. No. 4,440,868 to Hettinger et al. refers to selected metal additives in column 11, line 20, but does not apparently expressly mention Mn.

U.S. Pat. No. 4,450,241 to Hettinger et al. uses metal additives for endothermic removal of coke deposited on catalytic materials and includes manganese as an example of the additive (column 11, Table C).

U.S. Pat. No. 4,469,588 to Hettinger et al. teaches immobilization of vanadia during visbreaking and adds manganese to sorbent materials (column 11, lines 1-13, line 53 and line 65; column 23, line 59 and line 20; claim 1 and claim 17.

U.S. Pat. No. 4,485,184 to Hettinger et al. is understood to teach that trapping of metals deposited on catalytic materials concludes manganese as an additive (column 8, line 32; column 10, line 50, Table A; column 11, line 34; column 29, line 55, Table Z; column 31; column 32; claims 5-9.

U.S. Pat. No. 4,508,839 to Zandona et al. mentions metal additives including manganese at column 17, line 44 for the conversion of carbo-metallic oils.

U.S. Pat. No. 4,513,093 to Beck et al. immobilizes vanadia deposited on sorbent materials by additives, including manganese; column 9, line 35, Table A; column 10, lines 8-9; column 10, line 21.

U.S. Pat. No. 4,515,900 to Hettinger et al. is understood to teach that additives, including Mn, are useful in visbreaking of carbo-metallic oils (column 10, line 64 and column 23, line 52, Table E; column 25, line 13, Table 5.

U.S. Pat. No. 4,549,958 to Beck et al. teaches immobilization of vanadia on sorbent material during treatment of carbo-metallic oils. Additives include manganese mentioned at column 9, line 37, Table A; column 10, line 10; column 10, line 21; column 21, line 27, Table Y; column 21, line 56, Table Z; claim 37-38.

U.S. Pat. No. 4,561,968 to Beck et al. is understood to teach carbo-metallic oil conversion catalyst with zeolite Y-containing catalyst includes immobilization by manganese; column 14, line 43.

U.S. Pat. No. 4,612,298 to Hettinger et al. teaches manganese vanadium getter mentioned at column 14, line 31-32.

U.S. Pat. No. 4,624,773 to Hettinger et al. is understood to teach large pore catalysts for heavy hydrocarbon conversion and mentions manganese at column 18, line 27.

U.S. Pat. No. 4,750,987 to Beck et al. teaches mobilization of vanadia deposited on catalysts with metal additives including manganese; column 9, line 10; column 11, line 6, Table A; column 11, lines 47-49; column 11, lines 67; column 24, lines 14-25; column 28, line 52, Table Y.

U.S. Pat. No. 4,877,514 to Hettinger et al. teaches the incorporation of selected metal additives, including manganese, which complex with vanadia to form higher melting mixtures; column 10, lines 43-49; column 14, lines 34-35; column 29, line 37; claims 2, 10 and 13.

U.S. Pat. No. 5,106,486 to Hettinger teaches the addition of magnetically active moieties, including manganese, for magnetic beneficiation of particulates in fluid bed hydrocarbon processing; column 4, line 64; claims 1, 2, 11, 32, and 44-48.

U.S. Pat. No. 5,198,098 to Hettinger uses magnetic separation of old from new equilibrium particles by means of manganese addition (see claims 1-30).

U.S. Pat. No. 5,230,869 to Hettinger et al. is understood to teach the addition of magnetically active moieties for magnetic beneficiation of particulates in fluid bed hydrocarbon processing; column 5, line 4 and claim 1.

U.S. Pat. No. 5,364,827 to Hettinger et al. teaches the composition comprising magnetically active moieties for magnetic beneficiation of particulates in fluid bed hydrocarbon processing; column 5, line 4 and claim 5.

U.S. Pat. No. 4,836,914 to Inoue et al. mentions magnetic separation of iron content in petroleum mineral oil but is not understood to mention manganese.

U.S. Pat. No. 4,956,075 to Angevine et al. adds manganese during the manufacture of large pore crystalline molecular sieve catalysts and particularly uses a manganese ultra stable Y in catalytic cracking of hydrocarbons.

U.S. Pat. No. 5,358,630 to Bertus et al. mentions manganese in claims 28 and 40, but not in the specification. The patent relates primarily to methods for ". . . contacting . . . catalyst with a reducing gas under conditions suitable countering effects of contaminating metals thereon and employing at least a portion of said reduced catalysts in cracking said hydrocarbon feed" (column 7, lines 10-12).

U.S. Pat. No. 2,575,258 to Corneil et al. mentions manganese as accumulating in the catalysts as a result of erosion of equipment (column 3, line 34).

U.S. Pat. No. 3,977,963 to Readal et al. mentions manganese nitrate and manganese benzoate and other manganese compounds, e.g., in the second paragraph under "Descriptions of Preferred Embodiments" and in the Tables under "Detailed Description" and in claim 4. It is directed to the contacting of catalysts with a bismuth or manganese compound to negate the effects of metals poisoning.

U.S. Pat. No. 4,036,740 to Readal et al. teaches use of antimony, bismuth, manganese, and their compounds convertible to the oxide form to maintain a volume ratio of carbon dioxide to carbon monoxide in the regeneration zone of a fluid catalytic cracker of at least 2.2.

Cimbalo et al., May 15, 1972, teaches the effects of nickel and vanadium on deleterious coke production and deleterious hydrogen production in an FCC unit using zeolite-containing catalyst.

SUMMARY OF THE INVENTION

I. General Statement of the Invention

According to the invention, an improved "magnetic hook"-promoted catalytic process, catalyst and method of manufacture for heavy hydrocarbon conversion, optionally in the presence of nickel and vanadium on the catalyst and in the feedstock to produce lighter molecular weight fractions, including more gasoline and lower olefins and higher isobutane than normally produced has been discovered. This process is based on the discovery that two "magnetic hook" elements, namely manganese and chromium, previously employed as magnetic enhancement agents to facilitate removal of old catalyst, or to selectively retain expensive catalysts, can also themselves function as selective cracking catalysts, particularly when operating on feeds containing significant amounts of nickel and vanadium, and especially where economics require operating with high nickel- and vanadium- contaminated and containing catalysts. Under such conditions, these promoted catalysts are more hydrogen and coke selective, have greater activity, and maintain that activity and superior selectivity in the presence of large amounts of contaminant metal, while also making more gasoline at a given conversion.

II. Utility of the Invention

Table A summarizes approximate preferred, more preferred, and most preferred levels of the more important parameters of the invention. Briefly stated, the invention comprises, improving gasoline selectivity in a process for the conversion of hydrocarbons containing more than 1 ppm of nickel and more than 1 ppm of vanadium to lower molecular weights comprising gasoline by contacting said hydrocarbons with a circulating zeolite-containing cracking catalyst, which is thereafter regenerated and recycled to contact additional hydrocarbons, the improvement comprising in combination the steps of: a) maintaining a catalyst:oil weight ratio of at least about 2; and b) adding to at least a portion of said cracking catalyst from about 0.1 to 20 wt. % of manganese and/or chromium, in the form of a compound, based on the weight of the catalyst; whereby gasoline selectivity is increased by at least 0.2 wt. % points as compared to said process without said manganese or chromium. More preferably the portion of cracking catalyst to which manganese is added comprises from 5-100 wt. % of the total weight of the circulating catalyst. Still more preferably, the portion contains more than 0.5% by weight of sodium. This process and catalyst is especially effective when used in conjunction with a circulating catalyst containing nickel and vanadium and/or when operating at higher steam and/or temperature severity.

The weight of manganese is maintained at about 0.3 or above times the total nickel-plus-vanadium or total metals or total vanadium on the circulating catalyst. The carbon remaining after regeneration is preferably no more than 0.1% of the weight of the carbon deposited on the catalyst during hydrocarbon conversion. Particularly preferred is a process wherein the fresh catalyst is added over time to the circulating catalyst, particularly where the flesh catalyst comprises 0.1-20 wt. % manganese and/or a similar concentration of chromium. The cracking catalyst added continuously can be the same or different from that circulating and can preferably comprise a paraffin-selective cracking catalyst such as Mobil's ZSM-5. One important advantage of the invention is that the cracking catalyst can be rendered more gasoline selective, coke selective, and hydrogen selective when it contains 0.1-20 wt. % manganese, and is even more selective when contaminated with nickel and vanadium as compared to the selectivity of equivalent catalyst without manganese. The manganese and/or chromium is preferably deposited onto the outer periphery of each microsphere but can be deposited uniformly throughout the microsphere, where the most preferred microspherical catalysts particles are used. Cracking activity can exist in both the zeolite and the matrix. Manganese preferably serves as an oxidation catalyst to accelerate the conversion of carbon to CO and CO.sub.2 and any sulfur in the coke to SO.sub.2, SO.sub.3 or sulfate and can act as a reductant in the conversion reactor to convert greater than 10% of the retained sulfate in the reactor to SO.sub.2, sulfur and H.sub.2 S.

Cracking catalyst can be prepared by incorporating manganese into a microspherical cracking catalyst by mixing with a solution of a manganese salt with a gelled cracking catalyst and spray drying the gel to form a finished catalyst or a solution of manganese salt can be combined with the normal catalyst preparation procedure and the resulting mixture spray-dried, washed and dried for shipment. Manganese can be added to the microspherical catalyst by impregnating the catalyst with a manganese-containing solution and flash drying. Preferred salts of manganese for catalyst preparation include nitrate, sulfate, chloride, and acetate. The selective cracking catalyst can be prepared by impregnating spray-dried catalyst with MMT (methylcyclopentadienyl manganese tricarbonyl) and drying. The MMT can be dissolved in alcohol or other solvent which can be removed by heating. Alternatively, spray-dried or extruded or other catalyst can be impregnated with a colloidal water suspension of manganese oxide or other insoluble manganese compound and dried. The continuous or periodic addition of a water or organic solution of manganese salts with or without methyl cyclopentadienyl manganese tricarbonyl in a solvent can also be employed with the invention. Manganese compounds, preferably MMT or manganese actuate in mineral spirits or a water solution of a manganese salt, can also be added directly to the catalytic cracker feed and subsequently deposited on the circulating catalyst.

The virgin catalysts will preferably possess a magnetic susceptibility of greater than about 1.times.10.sup.-6 emu/g and this can be promoted to a magnetic hook into the range of about 1-40.times.10.sup.-6 emu/g or even greater. (Magnetic hooks are discussed in detail in U.S. Pat. Nos. 5,106,486; 5,230,869 and 5,364,827 to Hettinger et al.) The coke produced in the conversion is burned off by contact with oxygen-containing gas in a conventional regenerator and the manganese can serve as an oxidation catalyst in the regenerator to accelerate the conversion of carbon to carbon monoxide and/or carbon dioxide, enhancing the regeneration process.

As an additional advantage of the invention, the sulfur in some gasolines can be reduced by 10% or even more as compared to gasoline produced without manganese in the catalyst.

A portion of the circulating catalyst can be removed from the process of the invention and treated with nitrogen, steam and greater than 1% oxygen (preferably in the form of air) for 10 minutes to 1 hour or even more at 1200.degree. F., or greater then returned to the process, to effect a partial or complete regeneration of the catalyst.

TABLE A______________________________________PROCESS More MostParameter Units Preferred Preferred Preferred______________________________________V in Feed Wt. ppm 1 or more 10 or more 50 or moreNi in Feed Wt. ppm 1 or more 10 or more 50 or moreNi + V on Wt. ppm above 500 above 1000 above 5000CatalystV on Wt. ppm 100-100,000 above 500 above 1000CatalystMn on Wt. % 0.05-20 0.1-15 0.2-10CatalystCatalyst compos. Zeo- USY- ZSM-5 containing containing containingCat:Oil ratio Wt. 2 or more 2.5-12 3-9Mn/Cr on Wt. % 0.1-20 0.5-15 1-10CatalystMn/Cr any impregna- --Addition Meth. tionGasoline Wt. % +0.2 or +0.4 or +1 orSelectivity .DELTA. more more more"Portion" Wt. % 5-100 10-50 15-25with Mn/CrNa in "Portion" Wt. % more than more than more than 0.5 0.6 0.7Mn:(Ni + V) Wt. ratio above 0.3 above 0.5 above 1on CatalystMn:V on Wt. ratio above 0.3 above 0.5 above 1CatalystCr:(Ni + V) Wt. ratio above 0.3 above 0.5 above 1on CatalystConcarbon in Wt. % above 0.1 above 0.3 1-7feed% of Carbon on % of 0.5 or less 0.1 or less 0.05-0.1Cat. remaining orig.after regen.Zeolite-in- Wt. % 1 or more 5 or more 10 or moreCatalystHydrocarbon Wt. % above 2 above 3 above 4Concarb.S in Hydro- Wt. % above 0.5 above 1.5 above 2carbon feedS retention Wt. % 10 or more 12 or more 15 or moreby Mn% Sulfate in Wt. % above 10 above 12 above 15ReactorConvertedCatalyst Form Form any micro- spray-dried spheres micro- spheresCat. Mag. 10.sup.-6 above 1 2-40 3-40Suscept. emu/gCat. Mag. Hook 10.sup.-6 1-50 2-40 3-40Mag. Suscepti- emu/gbility IncreaseReduction of % 10 or more 12 or more 15 or more50x in Fluegas______________________________________

The present invention is useful in the conversion of hydrocarbon feeds, particularly metal-contaminated residual feeds, to lower molecular, weight products, e.g., transportation fuels. As shown below, it offers the substantial advantages of improving catalyst activity, improving gasoline-, coke-, and hydrogen-selectivity and reducing sulfur content of the products, as well as enhancing regeneration of coked catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of relative activity (by Ashland Oil test, see e.g., U.S. Pat. No. 4,425,259 to Hettinger et al.) versus cat:oil weight ratio for AKC catalyst (the same catalyst except for FIG. 7 used in FIGS. 1-18) with and without manganese. (See Example 1 and Table 1.)

FIG. 2 is a plot of wt. % gasoline selectivity versus wt. % conversion in a typical cracking process and compares catalysts with and without manganese. (See Example 3 and Table 3a. )

FIG. 3 is a plot of gasoline yield versus conversion rate constant and compares catalysts with and without manganese. (See Example 3 and Table 3a.)

FIG. 4 is a plot of gasoline wt. % selectivity versus conversion comparing catalysts with and without manganese and contaminated with 3000 ppm nickel plus vanadium. (See Example 4 and Table 4.)

FIG. 5 is a plot of relative activity versus cat:oil ratio comparing catalysts with and without manganese. (See Example 4 and Table 4.)

FIG. 6 is a plot of wt. % gasoline in product versus conversion rate constant for the catalysts with and without manganese showing the improved gasoline percentage with manganese. (See Example 4 and Table 4.)

FIG. 7 is a plot of gasoline selectivity versus weight ratio of (X) manganese:vanadium, and (O) manganese:nickel+vanadium. (See Example 8 and Table 8.)

FIG. 8 is a plot of relative activity versus cat:oil ratio comparing no manganese with 9200 ppm manganese added by an impregnation technique and with 4000 ppm manganese added by an ion exchange technique. (See Example 10 and Tables 10a, 10b and 10c.)

FIG. 9 is a plot of gasoline selectivity versus conversion comparing no manganese versus 9200 ppm impregnated manganese and 4000 ppm ion exchanged manganese. (See Example 10 and Tables 10a, 10b and 10c.)

FIG. 10 is a plot of Ashland relative activity versus cat:oil ratio comparing catalysts with and without manganese at different levels of rare earth. (See Example 11 and Table 10.)

FIG. 11 is a plot of gasoline selectivity versus gasoline conversion comparing no manganese with impregnated rare earth elements and ion-exchanged manganese, showing manganese, surprisingly, is more effective than rare earths. (See Example 11 and Table 10. )

FIG. 12 is a plot of wt. % isobutane (in mixture with 1-butene/isobutene) versus wt. % conversion for catalysts with no manganese and with 9200 and 4000 ppm manganese. (See Example 12 and Table 10.)

FIG. 13 is a plot of the ratio of C.sub.4 saturates to C.sub.4 olefins versus wt. % conversion comparing manganese at levels of 4000 ppm, 9200 ppm of with no manganese and no manganese plus 11,000 ppm rare earth. (See Example 12 and Table 10.)

FIG. 14 is a plot of the CO.sub.2 :CO ratio versus percent carbon oxidized off during regeneration (See Example 14) with and without manganese.

FIG. 15 is a plot of wt. % gasoline versus wt. % conversion for catalysts with and without manganese and 3200 ppm Ni+V showing improved gasoline yield with manganese. (See Example 15 and Table 12.)

FIG. 16 is a plot of hydrogen-make versus conversion showing the improved (reduced) hydrogen make with manganese being deposited as an additive during cracking. (See Example 15 and Table 12.)

FIG. 17 is a plot of coke-make versus conversion showing the improved (reduced) coke make with manganese being deposited as an additive during cracking. (See Example 15 and Table 12.)

FIG. 18 is a plot of conversion versus cat:oil ratio showing the improved conversion with manganese at cat:oil ratios above about 3. (See Example 15 and Table 12.)

FIG. 19 is a plot of relative activity versus manganese content.

FIG. 20 is a plot of selectivity versus manganese content.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples are presented to illustrate preferred embodiments of the invention, but the invention is not to be considered as limited by the specific embodiments presented herein.

EXAMPLE 1

The Invention with Manganese Additive on Cracking Catalyst

4.54 grams of manganese II acetate tetrahydrate is dissolved in 100 ml. of boiling distilled water. 100 grams of a commercially available low rare earth-containing (less than 1800 ppm) cracking catalyst is also dispersed in 150 ml. of distilled water. The catalyst slurry and the manganese acetate tetrahydrate solution are mixed rapidly and shaken vigorously for 15 minutes at room temperature. This is repeated four to five times over a 24-hour period, and the slurry then allowed to settle for two hours. Excess liquid is poured off, the settled catalyst slurried once with 100 ml. of distilled water and dewatered through a filter. The filter cake is allowed to air dry and then dried in a microwave oven for four minutes at high intensity setting. The dried sample is calcined at 1200.degree. F. in a ceramic crucible for four hours and allowed to cool in air to room temperature.

The finished catalyst is analyzed for manganese content by x-ray fluorescence and found to have 6000 ppm of manganese.

Catalyst cracking activity is evaluated by means of a micro-activity test performed by Refining Process Services of Cheswick, Pa.

The results obtained for this catalyst are shown in Table 1.

TABLE 1__________________________________________________________________________Manganese Addition, Micro-activity Study Base Catalyst Base Catalyst plus ManganeseCatalyst Metal None 6000 ppm__________________________________________________________________________Steaming Temperature (.degree.F.) 1425 1425Steaming Time (hours) 24 24Cat:Oil Ratio 4.60 4.58Reaction Temperature (.degree.F.) 960 960Reaction Time (seconds) 25 25WHSV 31.3 31.5Conversion (wt. %) 67.37 74.64Conversion (vol. %) 69.09 76.60Product Yields (wt. %) on Fresh FeedC.sub.2 and lighter 1.41 1.51Hydrogen 0.11 0.09Methane 0.45 0.47Ethane 0.37 0.41Ethylene 0.48 0.54Carbon 3.64 3.82Product Yields (wt. %) on Fresh FeedTotal C.sub.3 Hydrocarbon 5.36 4.99Propane 0.62 0.83Propylene 4.75 4.16Total C.sub.4 Hydrocarbon 10.54 10.17I-Butane 3.55 4.48N-Butane 0.54 0.82Total Butenes 6.45 4.88Butenes 3.18 2.05T-Butene-2 1.86 1.62C-Butene-2 1.40 1.21C.sub.5 -430.degree. F. Gasoline 46.42 54.15(Vol. %) (56.24) (65.60)430-650.degree. F. LCGO 22.35 18.25650.degree. F. + Decanted Oil 10.28 7.11C.sub.3 + Liquid Recovery 94.95 94.67FCC Gasoline + Alkylate Vol. % 87.4 90.84Isobutane/(C.sub.3 + C.sub.4) Olefin Ratio 0.32 0.50Coke Selectivity 1.64 1.22Weight Balance 99.71 98.52Feed Stock RPS RPS ##STR1## 68.9 72.5 ##STR2## 81.4 85.6 ##STR3## 2.06 2.91__________________________________________________________________________

It will be noted that in this case both activity, a most important economic property; and gasoline selectivity, an even more important economic property; are higher for the catalyst with manganese. These results clearly show the benefit of manganese as a catalyst promoter.

EXAMPLE 2

Effect of Manganese at Higher Levels

Two additional catalyst preparations, using the same procedure as used for the catalyst in Example #1, are made, but at slightly higher levels of manganese. These two samples are labeled AKC #1 and AKC #2. AKC #1 is shown by x-ray fluorescence to have 9200 ppm of manganese and AKC #2 contained, 15,000 ppm of manganese.

AKC #1 and AKC #2 are also submitted for MAT testing, and the results further continued the activity and selectivity results noted in Table 1. See Table 2.

TABLE 2__________________________________________________________________________Manganese Addition Base CatalystCatalyst Metal None AKC #1 AKC #2__________________________________________________________________________Metal Manganese ppm none 9280 15900Steaming temperature (.degree.F.) 1425 1425 1425Steaming Time (hours) 24 24 24Feed Stock RPS RPS RPSCat:Oil Ratio 4.6 4.48 4.51Reaction Temperature (.degree.F.) 960 960 960Reaction Time (seconds) 25 25 25WHSV 31.3 32.1 31.9Conversion (wt. %) 67.37 74.56 74.21Conversion (vol. %) 69.06 76.49 76.15Product Yield, (wt. %) on Fresh FeedC.sub.2 and Lighter 1.41 1.46 1.32Hydrogen 0.11 0.09 0.08Methane 0.45 0.44 0.41Ethane 0.37 0.39 0.36Ethylene 0.48 0.52 0.47Carbon 3.64 4.46 4.73Product Yields (wt. %) on Fresh FeedTotal C.sub.3 Hydrocarbon 5.36 5.25 4.73Propane 0.62 0.75 0.72Propylene 4.75 4.5 4.01Total C.sub.4 Hydrocarbon 10.54 10.79 9.98I-Butane 3.55 4.46 4.35N-Butane 0.54 0.76 0.75Total Butenes 6.45 5.57 4.88Butenes 3.18 2.41 2.03T-Butene-2 1.86 1.8 1.63C-Butene-2 1.4 1.36 1.22C.sub.5 -430.degree. F. Gasoline 46.42 52.60 53.46(Vol. %) (56.24) (63.72) (64.76)430-650.degree. F. LCGO 22.35 18.53 18.72650.degree. F. + Decanted Oil 10.28 6.91 7.07C.sub.3 + Liquid Recovery 94.95 94.08 93.95FCC Gasoline + Alkylate Vol. % 87.4 91.8 89.6Isobutane/(C.sub.3 + C.sub.4) Olefin Ratio 0.32 0.45 0.49Coke Selectivity 1.64 1.44 1.55Weight Balance 99.7 98.63 98.13Option Normal- Normal- ized ized ##STR4## 68.9 70.5 72.0 ##STR5## 81.4 83.3 85.0 ##STR6## 2.06 2.93 2.90__________________________________________________________________________

As can be seen by this data, manganese again greatly increases activity and selectivity, while making much less coke (on a selectivity basis) and hydrogen. Clearly manganese has a markedly beneficial effect on catalyst performance.

EXAMPLE 3

Manganese on Higher Levels of Cat:Oil Ratio

Referring to Table 3, steamed samples of AKC #1 are MAT evaluated at a series of cat:oil ratios, to better define activity and selectivity. Table 3a shows the results of this study, and Table 3b shows the composition of the gas oil used in these tests.

TABLE 3a__________________________________________________________________________Effect of Manganese on Cracking Yields MAT Data on AKC #1Steamed Samples Variation Cat:Oil Ratio Catalyst ID AKC AKC AKC AKC #1 #1 + Mn AKC #1 #1 + Mn AKC #1 #1 + Mn__________________________________________________________________________Steaming Temp (.degree.F.) 1400 1400 1400 1400 1400 1400Steaming Time (hours) 5 5 5 5 5 5Cat:Oil Ratio 2.9 3.1 4.0 4.0 4.8 5.1Temperature (.degree.F.) 915 915 915 915 915 915Catalyst Metals Manganese 0 9200 0 9200 0 9200(ppm)Feed Stock WTGO WTGO WTGO WTGO WTGO WTGOWt. % YieldsConversion 64.9 73.2 74.9 78.8 78.4 81.3Hydrogen 0.05 0.05 0.07 0.07 0.08 0.08Methane 0.30 0.34 0.38 0.44 0.45 0.52Ethane/Ethylene 0.58 0.70 0.73 0.90 0.84 1.02Propane 0.58 0.93 0.78 1.30 0.97 1.65Propylene 3.53 3.55 4.43 3.98 4.70 4.08Isobutane 3.63 5.08 4.63 6.06 5.71 6.821-Butene/Isobutene 2.26 1.76 2.48 1.52 1.46 1.58N-Butane 0.59 1.06 0.79 1.37 1.02 1.65Butadiene 0.00 0.00 0.00 0.00 0.00 0.00Cis-2-Butene 0.99 1.02 1.21 0.99 1.23 0.98Trans-2-Butene 1.36 1.36 1.64 1.32 1.67 1.31CO, CO.sub.2, CO.sub.5, H.sub.2 S 0.33 0.35 0.35 0.33 0.32 0.37C.sub.5 - 430.degree. F. 48.42 53.77 54.28 56.05 55.90 55.96430-630.degree. F. 17.46 16.39 15.82 14.27 14.25 12.96630.degree. F. 17.63 10.41 9.28 6.97 7.38 5.82Coke 2.28 3.23 3.15 4.42 4.02 5.30H.sub.2, SCFB 27 29 38 39 46 47H2:Cl Ratio, Mol:Mol 1.25 1.15 1.39 1.21 1.40 1.22Dry Gas 1.25 1.43 1.52 1.74 1.70 1.99Wet Gas 12.94 14.77 15.96 16.55 16.75 18.07 ##STR7## 74.6 73.5 72.5 71.1 71.3 68.8K = Rate Constant 1.85 2.74 2.98 3.72 3.63 4.35Coke Selectivity % Coke/K 1.23 1.18 1.06 1.19 1.11 1.22H2 Selectivity 0.0270 0.0183 0.0235 0.0188 0.0220 0.0184AOI Relative Activity 35 100 90 162 118 168__________________________________________________________________________ TABLE 3b______________________________________West Texas Gas Oil Metals______________________________________Wt. % Sulfur 0.49 API 28.1 Ni < 1 ppmTotal Nitrogen 330 ppm Ramsbottom Carbon 0.19% V < 1 ppmBasic Nitrogen 213 ppm Na 5 ppm Fe 1 pm______________________________________Chemical Composition Wt. %______________________________________Saturates 67.1Monoromatics 19.5Diaromatics 5.6Greater than Diaromatics 5.6Polars 2.0______________________________________

The results show that manganese greatly increases catalyst activity at all cat:oil ratios, namely a 48% increase at a cat:oil ratio of 3.0; a 25% increase at a cat:oil of 4.0; and a 20% increase at cat:oil of 5.0, using the wt. % conversion rate constant, K, for these comparisons. On Ashland's relative activity basis (see for example U.S. Pat. No. 4,425,259, FIG. 6) it is 186%, 80%, and 42%, respectively. In all cases of cat:oil it is obvious that there is a significant increase in catalyst activity resulting from manganese additive (see FIG. 1).

At first glance, it would appear that in this series of tests, manganese is not superior, selectivity wise, to untreated catalyst. However, this is partially due to the considerable differences in conversions at constant cat:oil testing. FIG. 2 is a plot of wt % gasoline selectivity versus wt % conversion. Here it is quite clear that selectivity is also enhanced. For example, at 75 wt % conversion there is clearly an increase of selectivity from 72.4 wt % to 72.9 wt %. For a catalytic cracker operating at 75 wt % conversion and processing 50,000 bbl/day of gas oil, this selectivity difference amounts to an increased yield of gasoline of approximately 250 barrels/day. At $30/bbl this is equivalent to an additional yield of $7500/day or $2.8 mm/year, a very significant amount. FIG. 3 shows a plot of gasoline yield as related to activity as rate constant which is expressed as wt % conversion divided by (100%-wt % conversion). This plot also shows the advantage of manganese promotion.

Note that in all cases, even where metal contaminants are absent hydrogen selectivity is enhanced in the presence of manganese and the olefin content of wet gas is lower, the result of the ability of manganese to transfer hydrogen to olefins, an important property in reducing olefin content of gasoline, so important in reformulated gasoline. Note also that isobutane content at constant conversion is up, providing the refiner with greater alkylate capacity, an equally important property in tomorrow's refinery.

EXAMPLE 4

Metals on Manganese Promoted Cracking Catalyst

Although the results of Examples 1, 2, and 3 conclusively show the benefits of manganese as an additive on catalyst performance, in today's environment, because of the unavailability of low metals containing crude oil and/or the economic necessity to process a greater portion or all of the reduced crude, a catalyst's resistance to metals poisoning, and also its ability to deal with crudes of higher sulfur content are also of great concern. In particular, its abilities to deal with vanadium, a well known hydrogen and coke producer, and a notorious destroyer of catalyst activity, and nickel, a hydrogen and coke producer are of special interest.

To evaluate the benefit of manganese as a metal resistant additive, an aliquot of catalyst is steamed according to standard conditions as described in Example #3, while a second aliquot is impregnated to 3000 ppm of Nickel+Vanadium (1800 ppm vanadium and 1200 ppm nickel) and then steam deactivated at 1400.degree. F. for 5 hours in 3% air, a condition shown to be quite severe, especially for vanadium poisoned cracking catalyst. Table 4 shows the results of these tests at three different cat:oil ratios, similar to Example #3.

TABLE 4______________________________________Effect of Manganese on Cracking Yields MAT Data onAKC #1 3000 ppm Ni + V Samples Catalyst ID AKC AKC AKC AKC #1 + AKC #1 + AKC #1 + #1 Mn #1 Mn #1 Mn______________________________________Steaming 1400 1400 1400 1400 1400 1400Temp (.degree.F.)Steaming 5 5 5 5 5 5Time (hours)Cat:Oil Ratio 3 3.1 4.0 4.1 4.9 5.0Temperature 915 915 915 915 915 915(.degree.F.)Catalyst Metals 3000 3000 3000 3000 3000 3000Total (1800ppm V, 1200ppm Ni)Manganese 0 9200 0 9200 0 9200ppmWt. % YieldsConversion 65.4 70.4 70.7 77.5 74.5 81.1Hydrogen 0.33 0.38 0.43 0.49 0.51 0.61Methane 0.37 0.41 0.48 0.57 0.59 0.73Ethane/ 0.64 0.73 0.74 0.92 0.83 1.08EthylenePropane 0.62 0.99 0.79 1.36 0.93 1.76Propylene 3.41 3.20 3.86 3.62 4.08 3.77Isobutane 3.04 4.25 3.77 5.51 4.33 6.371-Butene/ 2.26 1.46 2.42 1.51 2.35 1.45IsobuteneN-Butane 0.56 0.92 0.70 1.27 0.38 1.61Butadiene 0 0 0 0 0 0Cis-2-Butene 0.96 0.81 1.07 0.89 1.12 0.89Trans-2- 1.30 1.08 1.43 1.21 1.50 1.22ButeneCO, CO.sub.2, 0.38 0.35 0.39 0.37 0.47 0.40CO.sub.5, H.sub.2 SC.sub.5 - 430.degree. F. 48.51 51.15 50.27 53.15 51.27 52.30430-630.degree. F. 18.13 17.09 17.27 14.74 15.48 12.52630.degree. F. 16.45 12.54 11.98 7.76 9.97 6.35Coke 3.05 4.62 4.41 6.62 5.74 8.94H.sub.2, SCFB 191 223 253 286 295 358H2:Cl Ratio, 6.93 7.31 7.22 6.78 6.76 6.67Mol:MolDry Gas 1.72 1.88 2.04 2.35 2.40 2.82Wet Gas 12.14 12.71 14.02 15.37 15.14 17.07AOI Rel 38 74 57 141 81 183ActivityK Rate 1.89 2.38 2.41 3.44 2.92 4.29ConstantSelectivity 74.2 72.7 71.1 68.5 68.8 64.5Wt. %Coke Selec- 1.61 1.94 1.82 1.92 1.96 2.08tivity %Coke/KH2 Selectivity 0.17 0.16 0.18 0.14 0.17 0.14______________________________________

Here the effect of manganese promotion is even more dramatic. FIG. 4 shows selectivity is affected much less in the presence of large amounts of vanadium and nickel when the catalyst is protected with manganese.

For example at 75% conversion FIG. 4 shows that the wt % selectivity of a metal poisoned catalyst drops from 72.4 wt % as shown in Example 3, to 68.0 wt % while the catalyst protected and enhanced by manganese only drops to 70.8 wt %. The gasoline yield difference at constant conversion is 2.8 wt % or 1400 barrels/day or $42,000/day or $15.3 mm/yr increase in income, even without taking into account the much higher catalyst activity, which could reduce fresh catalyst addition rates and reduce overall catalyst costs.

Clearly manganese has further enhanced activity and selectivity differences, as the catalyst is subjected to metal poisoning by two severe catalyst poisons, namely nickel and vanadium. This benefit of manganese is also reported here for the first time.

As noted, this selectivity advantage for manganese is shown at constant conversion. However, FIG. 5 also shows the very significant activity advantage observed for the manganese promoted metal poisoned catalyst, which is equally striking, and the outstanding increase in gasoline yield shown in FIG. 6.

EXAMPLE 5

Impregnation of a Highly Active Reduced Crude Conversion (RCC.RTM.) Type Catalyst at Varying Levels of Manganese Concentration

Table 5a shows the results of manganese on catalyst activity and selectivity as manganese concentrations are increased up to as high as 2% (19,800 ppm) manganese. At constant cat:oil ratio, activity rises some 20-50% and selectivity one-half to twelve and one-half percent as metal increases. (It is well established that selectivity always decreases as conversion increases.) The results clearly show an advantage for manganese as concentrations increase, and while not considered limiting may even indicate an optimum concentration exists. The results also show both the coke and hydrogen factors were significantly improved at all levels of manganese concentrations shown here. Although manganese has been added at levels approaching 2.0% (19,800 ppm), these results confirm that at all levels and up to and including data in Table 5a, that manganese enhances performance, as well as providing protection against contaminating metals.

TABLE 5a______________________________________MAT Test SummaryMn-Impregnated Samples______________________________________Test No. D-2836 D-2835 C-5121 C-5123 E-2853Catalyst ID DZ-40 DZ-40 DZ-40 DZ-40 DZ-40Mn Level (ppm) Basc 2400 7,700 7,700 19,800Recovery (wt. %) 97.0 97.4 98.0 97.9 97.5Mat Conversion 76.9 82.0 85.5 81.2 81.9(vol. %)Normalized Yields(wt. %)Acid Gas (H.sub.2 S, CO, 0.49 0.51 0.46 0.37 0.47CO.sub.2)Dry Gas 2.26 2.40 2.27 1.78 2.42Hydrogen 0.18 0.15 0.11 0.08 0.17Methane 0.63 0.67 0.65 0.51 0.71Ethane + Ethylene 1.46 1.58 1.51 1.18 1.54Wet Gas 18.23 19.56 18.61 15.09 18.92Propane 2.95 3.19 2.68 2.18 2.86Propylene 3.33 3.58 3.58 2.86 3.56Isobutane 7.08 7.72 7.40 6.09 7.321-Butene + 1.27 1.29 1.21 0.94 1.33IsobutyleneN-Butane 2.05 2.18 2.07 1.72 2.12Cis-2-Butane 0.65 0.68 0.71 0.56 0.74Trans-2-Butene 0.89 0.92 0.95 0.75 0.99Gasoline (C.sub.5 - 430.degree.) 45.46 48.58 52.50 53.44 48.86Cycle Oil (430-630.degree.) 14.02 13.20 12.68 14.60 12.88Slurry (630.degree. F.) 11.89 7.98 6.34 7.81 7.90Coke 7.66 7.78 7.15 6.91 8.54Conversion (wt. %) 74.09 78.82 80.98 77.59 79.21Gasoline Selectivity 61.3 61.6 64.8 68.9 61.7(Wt. %)Activity = K 2.86 3.72 4.26 3.46 3.81H.sub.2 Selectivity 0.063 0.043 0.026 0.023 0.045(% H.sub.2 /K)Coke Selectivity 2.68 2.09 1.68 2.00 2.24(% coke/K)______________________________________

Note also that all of the manganese promoted catalysts were much more effective in converting slurry oil to lower molecular weight gasoline and light cycle oil. Table 5b shows that this catalyst contains over 1 wt. % (10,000 ppm) rare earth before promotion with manganese, and yet manganese is able to greatly enhance activity and selectivity over and above a high level of rare earth promotion.

TABLE 5b______________________________________Manganese Catalyst Composition______________________________________(Wt. %)Al.sub.2 O.sub.3 33.0SiO.sub.2 51.2TiO.sub.2 1.14Fe.sub.2 O.sub.3 0.50MnO 1.98Rare Earths ppm MetalNeodymium 2800Praseodymium 830Cerium 1400Lanthanum 5900Total 10930______________________________________

EXAMPLE 6

Impregnation of a Special Paraffin Cracking Catalyst with Manganese at Varying Levels of Manganese from 0.6% to 1.8%

In this series of experiments, a specialty catalyst designed to selectivity crack n-paraffins is impregnated with manganese at various concentrations in a manner identical with preparations for regular cracking catalysts (Table 6). This catalyst contained approximately 8.5 wt % ZSM5 in a binder matrix. Naturally, because this catalyst is designed only to crack n-paraffins, or slightly branched paraffins, conversion is not nearly as high, nor is selectivity expected to be competitive with normal cracking catalysts.

TABLE 6__________________________________________________________________________MAT Test SummaryMn-Impregnated SamplesTest No. E-2824 B-5095 C-5120 B-5096Catalyst II) ZSM-5 ZSM-5 ZSM-5 ZSM-5__________________________________________________________________________Manganese (ppm) Base 6200 13300 17700Recovery (wt. %) 101.6 101.3 101.3 101.9Normalized Yields (wt. %)Acid Gas (H.sub.2 S, CO, CO.sub.2) 0.06 0.16 0.22 0.09Dry Gas 1.10 2.09 2.03 2.08Hydrogen 0.02 0.03 0.03 0.03Methane 0.10 0.15 0.14 0.13Ethane + Ethylene 0.99 1.90 1.85 1.92Wet Gas 10.15 10.99 10.53 11.11Propane 0.79 2.37 2.29 2.25Propylene 4.53 3.39 3.30 3.67Isobutane 0.33 1.61 1.46 1.47l-Butene + Isobutylene 2.43 1.41 1.36 1.56N-Butane 0.49 1.16 1.15 1.10Cis-2-Butane 0.67 0.45 0.42 0.45Trans-2-Butene 0.91 0.60 0.56 0.61Gasoline (C.sub.5 -430.degree.) 6.24 10.64 9.65 8.99Cycle Oil (430-630.degree.) 8.59 8.99 8.47 8.59Slurry (630.degree.+) 73.37 66.69 68.51 68.67Coke 0.48 0.45 0.59 0.46Conversion (wt. %) 18.04 24.32 23.02 22.74Coke Selectivity 2.18 1.41 1.97 1.59 ##STR8## 34.6 43.8 41.9 39.5 ##STR9## 0.22 0.32 0.30 0.29__________________________________________________________________________

Even here manganese is shown to greatly increase cracking activity 30-50% and also selectivity 14-26%. Note again that coke selectivity is greatly improved. Surprisingly, the yield of isobutane is greatly increased almost five-fold, and both propane and n-butane jumped dramatically, showing the ability of manganese to transfer hydrogen directly to olefins. This ability of manganese to hydrogenate in the short resident time in the reactor, is also an important property in catalytically converting sulfate back to SO.sub.2, sulfur and H.sub.2 S in the reactor, another important contribution of manganese. The ability of manganese to oxidize CO to CO.sub.2 and SO.sub.2 to SO.sub.3 for retention in the regenerator is of equal importance, lowering sulfur in the product gasoline by 10-20% is also important.

EXAMPLE 7

RCC.RTM. Catalyst Loaded with High Level of Manganese and Metal Contamination

This example shows the effect of manganese when deposited in higher concentrations on a highly metal contaminated cracking catalyst from commercial operations on reduced crude (RCC.RTM. operation) and then blended in varying amounts of 1 to 99% with the same commercial catalysts.

This example shows that impregnation with manganese at very high levels of a residual catalyst containing metal contaminants and then mixing with no-manganese, but metal-contaminated catalyst, results in considerable improvement in performance. (See Table 7.) In this case, a reduced crude catalyst containing a large amount of contaminant metal, 4800 ppm V, 1700 ppm Ni, 8300 ppm Fe and impregnated with 10% manganese is mixed with nine times its weight of the same catalyst, but not containing any manganese, and then subjected to MAT testing. Results of this experiment are shown in Table 7. When this catalyst is blended with one-tenth times its weight of catalyst containing 10% manganese, there is an overall improvement in performance. This can be attributed to the ability of manganese on one catalyst to selectively treat associated no-manganese but metal-loaded catalyst so as to enhance overall performance. In this case a metal contaminated catalyst is loaded with manganese and mixed with non-manganese containing high metal loaded catalyst and then submitted for testing.

TABLE 7______________________________________Sample ID 90% RCC catalystNI 1700 ppm mixed with 10% RCCV 4800 ppm 100% RCC catalyst containingFe 8300 ppm Catalyst 90,000 ppm Mn______________________________________Temperature (.degree.F.) 915 915Cat:Oil Ratio 3.0 3.0Manganese None 8,900 ppmMAT ActivityConversion vol. % 61.1 60.3H.sub.2 wt. % 0.33 0.21Coke wt. % 2.78 2.47Gasoline vol. % 55.97 55.76Gasoline Selectivity (vol. %) 91.5 92.5Coke Factor 1.4 1.2H.sub.2 Factor 11.2 6.9______________________________________

Table 7 compares MAT testing on this mixed sample as compared with unblended catalyst from the same sample source. Note that although manganese promoted catalyst is only present in 10% concentration, and has not had an impact on activity, all key economic factors, including gasoline selectivity, and hydrogen and coke factors show improvement, selectivity increasing from 91.5 to 92.5 and hydrogen factor dropping from 11.2 to 6.9 and coke factor dropping from 1.4 to 1.2. At present time it is not clear how this effect is manifested. Nevertheless, the presence of a high manganese loaded equilibrium catalyst serves to convey a benefit to all catalysts present, even when the manganese containing catalyst is present in as low a concentration as 10% and this effect is especially significant in the presence of catalysts containing very large amounts of nickel and vanadium.

The process can also be applied to situations where virgin catalyst containing large amounts of manganese as high as to 20 wt. % or more is mixed with equilibrium catalyst from the same operation, containing high levels of vanadium and nickel.

EXAMPLE 8

Magnetic Separation of RCC.RTM. Catalyst Loaded with Manganese and Metal Contamination and Mixed with Similar Catalyst without Manganese

This example demonstrates the effect of manganese when deposited in high concentrations on a highly metal contaminated cracking catalyst from commercial operations, and then separated by magnetic separation into varying fractions for recycle or disposal.

An RCC.RTM. equilibrium catalyst from cracking of reduced crude is impregnated with 8.9% manganese and blended with nine times its weight of an identical untreated catalyst (as in Example 7) and subjected to repeated magnetic separations by means of a rare earth roller, as described in Hettinger patent U.S. Pat. No. 5,198,098, producing seven cuts (see Table 8).

The various magnetic cuts from this separation are then submitted for MAT testing, and compared with untreated catalyst as well as the original blend. The equilibrium catalyst described above, before impregnation, contained 1700 ppm nickel, 4800 ppm vanadium, 8300 ppm iron and 0.74 wt % Na.sub.2 O and had a rare earth composition as follows: lanthanum 5700 ppm, cerium 2100 ppm, praseodymium 800 ppm, and neodymium 2800 ppm.

Table 8 shows the results of MAT testing and the chemical composition of the various cuts in terms of manganese, nickel, iron and vanadium. The data shows again, as previously shown in Example 7, the overriding beneficial effect of manganese in protecting and enhancing catalyst selectivity at all levels of metal poisoning up to and including 20,700 ppm of nickel plus iron plus vanadium. It shows that as long as the ratio of manganese to total metal, or to nickel-plus-vanadium, or to vanadium stays high, selectivity is enhanced. But as this ratio, especially for nickel plus vanadium, or vanadium alone, begins to drop off, selectivity begins to decline, despite the fact that this catalyst contains a very high metal contaminant level.

TABLE 8__________________________________________________________________________MAT Testing of Magnetic Separated Manganese Containing Catalyst 90% RCC 10% RCC 100% 89,000 ppm Blend Blend Blend Blend Blend Blend BlendCatalyst ID RCC Mn Blend Cut 1 Cut 2 Cut 3 Cut 4 Cut 5 Cut 6 Cut__________________________________________________________________________ 7Wt. % 100 100 13.0 15.9 15.7 15.1 14.3 7.9 17.8MAT Conv. vol. % 61.1 60.3 51.2 53.0 57.2 53.8 59.6 60.0 65.3Gasoline vol. % 56.0 55.8 49.6 50.6 54.3 49.7 56.3 56.0 58.9Wt. % Coke 2.78 2.47 2.52 2.68 2.57 2.30 2.36 2.61 2.62Wt. % II.sub.2 0.33 0.28 0.26 0.21 0.21 0.21 0.21 0.20 0.21Gasoline Selectivity 91.5 92.5 93.1 92.0 92.9 93.0 92.7 91.7 89.2(vol. %)Nickel ppm 1700 1700 2300 2400 2200 2000 1700 1700 1300Iron ppm 8300 8300 13300 10200 9200 8600 7700 7600 6500Vanadium ppm 4800 4800 5100 5200 5300 5200 4900 4800 4200Manganese 0 8900 17900 14600 10700 8800 6300 5100 2000Total Ni + Fe + V 14900 14900 20700 17800 16700 15800 14300 14100 12000 ##STR10## 0 1.37 2.42 1.92 1.42 1.22 0.95 0.78 0.36Total Ni + V 6500 6500 7400 7600 7500 7200 6600 6500 5500 ##STR11## 0 1.85 3.50 2.80 2.01 1.69 1.28 1.06 0.48Sodium (wt. %) 0.56 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.57__________________________________________________________________________

FIG. 7 shows a plot of selectivity versus manganese to metal ratio. Note how rapidly selectivity falls off as the ratio of manganese to vanadium drops to one to one, and is unable to protect catalyst against loss in selectivity. It shows the beneficial effect of very high levels of manganese on catalyst performance.

EXAMPLE 9

Selectivity Enhancement with a Second "Magnetic Hook" Additive, Chromium

Table 9 compares the results of MAT a chromium promoted low rare earth containing cracking catalyst. This catalyst was prepared in a manner similar to manganese promoted catalyst in Example 1 and contained 18,300 ppm of chromium. In this test the chromium promoted catalyst had a vol % selectivity of 82.3% compared to 81.4% for the non-promoted catalyst. It also made slightly less hydrogen.

TABLE 9______________________________________"Magnetic Hook" Study Base Catalyst Base CatalystCatalyst Metal None Chromium______________________________________Steaming Temperature (.degree.F.) 1425 1425Steaming Time (hours) 24 24Feed Stock RPS RPSCat:Oil Ratio 4.60 4.51Reaction Temperature (.degree.F.) 960 960Reaction Time (seconds) 25 25Conversion (wt. %) 67.37 66.26Conversion (vol. %) 69.09 67.87C5 - 430.degree. F. Gasoline 46.42 (56.24) 46.15 (55.92)430-650.degree. F. LCGO 22.35 (21.95) 23.18 (22.88)650.degree. F. + Decanted Oil 10.28 (8.96) 10.56 (9.25)Hydrogen Wt. % 0.11 0.10Wt. % Selectivity 68.9 69.7Vol. % Selectivity 81.4 82.4______________________________________

EXAMPLE 10

Impregnation Versus Ion Exchange of Manganese in Catalyst Preparation

Base catalyst, a low rare earth-containing catalyst of 0.15 wt. % rare earth oxide, is impregnated with manganese as described in Example 2, and compared with an ion exchange manganese-containing catalyst using a solution of 2N, MnSO.sub.4 The final manganese sulfate ion exchanged catalyst contains 4100 ppm of manganese. Samples of base catalyst, along with these two catalysts, are MAT tested at 3, 4 and 5 cat:oil ratios, and the results are shown in Table 10.

TABLE 10a______________________________________Effect of Manganese on Cracking YieldsMAT Data on AKC #1 AKC #1 Mn Mn ReCatalyst ID Base Impreg Exch Impreg______________________________________Cat:Oil Ratio 2.9 2.9 3.0 3.0Temperature .degree.F. 915 915 915 915Weight % YieldsAOI Relative Activity 35 100 127 34Conversion 64.9 73.2 75.0 65.4Hydrogen 0.05 0.05 0.06 0.04Methane 0.30 0.34 0.35 0.25Ethane/Ethylene 0.58 0.70 0.80 0.54Propane 0.58 0.93 1.00 0.52Propylene 3.53 3.55 4.05 3.47Isobutane 3.63 5.08 5.00 3.551-Butene/Isobutene 2.26 1.76 1.86 2.30N-Butane 0.59 1.06 0.94 0.55Butadiene 0.00 0.00 0.00 0.00Cis-2-Butene 0.99 1.02 1.02 1.03Trans-2-Butene 1.36 1.36 1.38 1.41CO, CO.sub.2, COS, H.sub.2 S 0.33 0.35 0.29 0.30C.sub.5 -430.degree. F. 48.42 53.77 54.97 49.21430.degree.-630.degree. F. 17.46 16.39 15.85 18.11630.degree. F. 17.63 10.41 9.19 16.45Coke 2.28 3.23 3.24 2.26Wt. % Selectivity 74.6 73.7 73.2 75.2Wt. % isobutane + 1- 5.89 6.84 6.86 5.85butene/isobutene ##STR12## 1.61 2.89 2.69 1.54______________________________________ TABLE 10b______________________________________Effect of Manganese on Cracking YieldsMAT Data on AKC #1 AKC #1 Mn Mn ReCatalyst ID Base Impreg Exch Impreg______________________________________Cat:Oil Ratio 4.0 4.0 3.9 4.1Temperature .degree.F. 915 915 915 915Weight % YieldsAOI Relative Activity 90 162 167 59Conversion 74.9 78.8 78.9 71.3Hydrogen 0.07 0.07 0.07 0.05Methane 0.38 0.44 0.46 0.32Ethane/Ethylene 0.73 0.90 0.97 0.67Propane 0.78 1.30 1.36 0.73Propylene 4.43 3.98 4.37 4.05Isobutane 4.63 6.06 6.16 4.711-Butene/Isobutene 2.48 1.52 1.82 2.36N-Butane 0.79 1.37 1.32 0.78Butadiene 0.00 0.00 0.00 0.00Cis-2-Butene 1.21 0.99 1.08 1.15Trans-2-Butene 1.64 1.32 1.47 1.57CO, CO.sub.2, COS, H.sub.2 S 0.35 0.33 0.35 0.36C.sub.5 -430.degree. F. 54.28 56.05 55.35 51.56430.degree.-630.degree. F. 15.82 14.27 13.90 17.08630.degree. F. 9.28 6.97 7.32 11.63Coke 3.15 4.42 4.09 2.98Wt. % Selectivity 72.5 71.1 70.1 72.3Wt. % isobutane + 1- 7.11 7.58 7.98 7.07butene/isobutene ##STR13## 1.87 3.98 3.38 1.99______________________________________ TABLE 10c______________________________________Effect of Manganese on Cracking YieldsMAT Data on AKC #1 AKC #1 Mn Mn ReCatalyst ID Base Impreg Exch Impreg______________________________________Cat:Oil Ratio 4.8 5.1 5.2 5.1Temperature .degree.F. 915 915 915 915Weight % YieldsAOI Relative Activity 118 168 146 75Conversion 78.4 81.3 80.4 75.5Hydrogen 0.08 0.08 0.08 0.07Methane 0.45 0.52 0.56 0.40Ethane/Ethylene 0.84 1.02 1.12 0.78Propane 0.97 1.65 1.68 0.91Propylene 4.70 4.08 4.24 4.49Isobutane 5.71 6.82 6.48 5.251-Butene/Isobutene 1.46 1.58 1.45 2.32N-Butane 1.02 1.65 1.53 0.95Butadiene 0.00 0.00 0.00 0.00Cis-2-Butene 1.23 0.98 0.90 1.23Trans-2-Butene 1.67 1.31 1.21 1.63CO, CO.sub.2, COS, H.sub.2 S 0.32 0.37 0.33 0.36C.sub.5 -430.degree. F. 55.90 55.96 55.0 53.22430.degree.-630.degree. F. 14.25 12.86 13.03 15.41630.degree. F. 7.38 5.82 6.53 9.10Coke 4.02 5.30 5.85 3.88Wt. % Selectivity 71.3 68.8 68.4 70.4Wt. % isobutane + 1- 7.17 8.40 7.93 7.57butene/isobutene ##STR14## 3.91 4.32 4.47 2.26______________________________________

FIG. 8 is a plot of activity versus cat:oil and shows that the ion exchanged manganese-containing catalyst is as active as the manganese impregnated catalyst, with only 4000 ppm of manganese. Selectivity plotted versus wt. % conversion in FIG. 9 further confirms manganese's ability to enhance selectivity even when present at a low of 4000 ppm concentration.

EXAMPLE 11

Comparison of Manganese Versus Rare Earth Ion Exchange AKC #1)

The low rare earth containing catalyst (0.15 wt. %) is treated by a similar ion exchange method with a solution of rare earth so as to increase rare earth content in order to compare the effect of manganese ion exchange catalyst compared with that of high rare earth containing catalyst. Rare earths have been used since the early 1960s to enhance cracking catalyst activity. After ion exchange, the rare earth content increases almost ten fold from 0.15 wt. % to 1.11 wt. %, or 1500 ppm to 11,000 ppm. All samples begin with 1500 ppm rare earths (RE).

Data shown in Table 10 also contain data from the rare earth promoted catalyst. FIG. 10 also shows the activity of high rare earth promoted catalyst versus the untreated AKC catalyst and the two manganese-containing catalysts. It shows that the rare earths, as compared to manganese, actually lower activity significantly as compared to manganese and the untreated catalyst. Selectivity-wise, the results show that the rare earths are actually detrimental as shown in FIG. 11. These results further demonstrate the unique ability of manganese to enhance both activity and selectivity.

EXAMPLE 12

Increased Production of Isobutane and Lower Olefins

The results of experiments presented in Table 10 also demonstrate that manganese changes the cracking characteristics of these catalysts in a way not previously reported. Previously, the rare earths, as also demonstrated here, were able to transfer hydrogen to olefins and reduce olefin content of the finished product. Unfortunately, as a result, because of the high octane value of olefins, octane numbers drop. It now appears that manganese changes the acidic properties sufficiently so as to increase isomerization before cracking and isobutane production after cracking, while also acting to reduce olefin content. FIG. 12 presents the yield of isobutane versus wt. % conversion and shows manganese significantly changes the yield of isobutane at constant conversion by 10-13% at 75 wt. % conversion. This demonstrates a distinctly different cracking behavior. Plotting the ratio of total C.sub.4 saturates divided by the total C.sub.4 olefins, shown in FIG. 13 further demonstrates manganese's unique ability to transfer hydrogen to olefins. Note that both low rare earth and high rare earth catalysts do not show this ability to any degree compared to the manganese supported catalysts, thus demonstrating manganese's high hydrogenation activity.

EXAMPLE 13

Effect of High Levels of Manganese on Catalyst Performance

Three catalysts were impregnated with very high levels of manganese by the following procedure. A finished catalyst containing 16.4 wt. % of manganese is prepared as follows: 36.4 grams of manganese acetate hydrate is dissolved in 26 ml of hot distilled water and heated to boiling for complete solution. This is mixed with 40 grams of DZ-40 dispersed in 50 ml of boiling water. The solution slurry mixture is kept at boiling temperature for two hours after which it is allowed to air dry, and then placed in an oven at 110.degree. C. until drying is complete. This sample is then placed in an Erlenmeyer flask and slowly raised to 1200.degree. F. where it is calcined for four hours. It is then cooled and submitted for MAT testing and chemical analysis.

All other samples listed in Table 11 were prepared and treated in the same way.

TABLE 11__________________________________________________________________________High Manganese Catalyst PerformanceMAT Test 915.degree. F. 3.0 Cat:Oil Ratio Catalyst ID IC IA IB 2C 2A 2B 3C 3A 3B__________________________________________________________________________Catalyst DZ-40 DZ-40 DZ-40 RCC RCC RCC RPS-F RPS-F RPS-FWt. % Mn 0 10.3 16.4 0 10.1 18.9 0 6.6 17.1ppm Mn 0 103,000 164,000 0 101,000 189,000 0 66,000 171,000ppm Fe 4554 4209 4437 9600 8970 7866 3180 2900 2760ppm Ni 50 41 38 2072 1914 1662 43 39 32ppm V 58 44 38 4169 3820 3348 116 107 88MAT Vol % Conv 79.8 71.1 62.6 60.3 31.5 25.8 93.7 88.6 76.2AOI RA 172 64 24 19.1 0.7 0.4 830 466 114Corrected and Normalized YieldWt. % C.sub.5 - 430.degree. F. 46.1 48.8 45.2 46.3 26.9 20.7 42.7 51.8 51.6Vol C.sub.5 - 430.degree. F. 56.9 59.4 54.9 56.0 32.6 25.2 53.4 63.9 62.9Wt. % Coke 7.2 4.59 4.26 2.78 3.30 5.12 16.31 10.83 7.15Wt. % conv of 430.degree. F. 77.1 68.4 62.0 59.9 35.6 31.0 91.0 85.4 73.7Vol % conv of 430.degree. F. 78.6 70.2 63.5 61.1 36.1 31.3 92.8 87.6 75.6Wt. % C5-430.degree. F. select 59.7 71.3 72.9 77.3 75.6 66.9 46.9 60.7 70.1Vol % C5-430.degree. F. select 72.4 84.5 86.4 91.5 90.4 80.3 57.5 72.9 83.2Wt. % Hydrogen 0.15 0.10 0.08 0.33 0.18 0.13 0.18 0.18 0.12__________________________________________________________________________

These three catalysts are: 1) a virgin Davison catalyst DZ-40, developed jointly by Ashland Petroleum Company and Davison, division of W. R. Grace & Co., for resid cracking, and covered by U.S. Pat. Nos. 4,440,868; 4,480,047; 4,508,839; 4,588,702; and 4,612,298 and described in a publication "Development of a Reduced Crude Cracking Catalyst" by W. P. Hettinger, Jr.; Catalytic; Chapter 19, pages 308-340; In Fluid Cracking ACS Symposium Series 375; M. Occelli, Editor 1988; 2) a second catalyst is an equilibrium catalyst taken from the regenerator of the original residual cat cracker, the extensively patented RCC.RTM. unit invented by Ashland Petroleum Company and first placed in operation in Catlettsburg, Ky., in 1983. This is labeled RCC.RTM. equilibrium catalyst; 3) the third catalyst is a resid type virgin catalyst obtained from Refining Process Services and labeled RPS-F.

Table 11 presents the results of tests on these three catalysts when containing intermediate and very high levels (164,000-189,000 ppm) (16.4-18.9 wt. %) of manganese. It will be noted that although such high levels of manganese began to reduce activity, production of gasoline is actually greater in many cases, again confirming that even at very high levels of manganese, (16.4-18.9 wt. %) some significant activity is still maintained, and more importantly, selectivity is generally enhanced.

For example, for DZ-40 at 10.3 wt. % manganese, the yield of gasoline is 59.4 vol. %; a very high liquid recovery, and much greater than the 56.9 vol. % gasoline when manganese is absent. Volume % selectivity for 16.4 wt. % Mn is 86.4, a very high value compared with 72.4 vol. % for untreated catalyst.

Volume % selectivity is exceptionally high for RCC.RTM. catalyst containing manganese. Even though conversion fell off with high levels of metal present in this catalyst, selectivity (vol. %) remained at one of the highest levels, 90.4 vol. %, demonstrating that even at contaminating levels as high as 6200 ppm of Ni+V and 9600 ppm for iron, manganese still has a unique impact on gasoline selectivity while limiting the behavior of nickel and vanadium.

Finally, in the third series, manganese has a very positive impact on gasoline, amounting to 62.9 vol. % gasoline when the catalyst contained 17.1 wt. % of manganese, and 63.9 vol. % yield at 6.6 wt. % of manganese.

This confirms that catalyst containing manganese at levels as high as 18.9 wt. % can maintain a superior selectivity for making gasoline with metals on catalyst as high as 2072 ppm of Ni, 4169 ppm of vanadium, 9600 ppm of iron, and 5500 ppm (0.55 wt. %) of sodium.

EXAMPLE 14

Carbon and Carbon Monoxide Oxidation Promotor

In carrying out regeneration of spent catalysts from catalytic cracking, the ability of a catalyst to enhance the burning rate of coke to carbon monoxide and convert to carbon dioxide is a key property. In particular, the ability to quickly convert CO to CO.sub.2 and rapidly establish equilibrium between, oxygen, carbon monoxide and carbon dioxide is desirable. An even more critical characteristic of an oxidation catalyst is how quickly it can establish this equilibrium so that heat balance and temperature control are easily maintained. Great fluctuations in burning rate which can occur in pockets of the regenerator can cause very large temperature rises. FIG. 14 shows that manganese incorporated cracking catalyst, in addition to its other unique properties, is a superior oxidative catalyst.

Samples of the commercial catalyst AKC #1 with and without 9200 ppm of manganese are steamed for 5 hours at 788.degree. C. with 100% steam.

For carbon oxidation testing, the steamed catalysts with and without manganese are further impregnated with about 0.30 wt. % Ni, using nickel octoate. The impregnated samples are then coked at 500.degree. C. using isobutylene to 2.5-3.5 wt. % carbon. Carbon burning rate is then determined by passing air over the catalyst samples at 718.degree. C. with a flow of 0.25 SCF/hr/g of catalyst.

FIG. 14 shows that burning of carbon to high ratios of CO.sub.2 over CO occurs very quickly over the manganese containing catalyst, rising to a ratio of CO.sub.2 :CO of 2.0 after 10% has been burned, and remains at 2:1 after 50% has been removed. This relative burning rate of up to 3:1 or greater compared with non-manganese containing catalyst confirms the efficiency of manganese promoted catalysts as also superior oxidation catalysts.

EXAMPLE 15

Superior Manganese Supported Cracking Catalyst Prepared by On-Stream Deposition and in the Presence of Nickel and Vanadium

A catalyst containing 1100 ppm nickel and 2100 ppm vanadium is prepared by spiking an RCC LCO with nickel octoate and vanadyl naphthanate and depositing the metals over 10 cycles of cracking and regeneration in a fixed-fluidized bed. This catalyst, however, is a moderate rare earth containing catalyst, 1.23 wt. %, and has been steam treated in a fixed-fluidized bed prior to impregnation with metals. A second sample is prepared by depositing manganese octoate dispersed in RCC.RTM. light cycle oil along with nickel octoate and vanadyl naphthahate on a second aliquot of the steam treated catalyst. As with the base, no-manganese sample, the metals are cracked onto the catalyst over 10 reaction/regeneration cycles in a fixed-fluidized bed. Total manganese deposited on the catalyst is 2000 ppm. The two catalysts (with and without manganese) are then submitted to MAT testing at 2.5, 3 and 4 cat:oil ratio (see Table 12).

TABLE 12__________________________________________________________________________MAT Test Summary No Manganese With 2000 ppm Manganese__________________________________________________________________________MAT Test No. B-6025 B-6026 B-2858 C-5176 B-4049 B-6060 B-6070Cat:Oil Ratio 2.5 3.0 4.1 2.6 2.9 3.0 3.9Conversion (wt. %) 67.8 71.2 74.2 66.1 70.8 71.1 75.5Yields (wt. %)Dry Gas 1.87 2.34 2.21 1.49 1.82 1.98 2.32Hydrogen SCFB 339 432 414 257 368 356 414Hydrogen 0.58 0.74 0.71 0.44 0.63 0.61 0.71Methane 0.43 0.56 0.54 0.33 0.40 0.45 0.55Ethane + Ethylene 0.86 1.04 0.96 0.72 0.79 0.92 1.06Wet Gas 12.06 13.70 13.97 11.33 12.30 12.18 14.23Propane 0.80 0.99 1.23 0.81 0.81 0.97 1.29Propylene 3.16 3.63 3.36 2.95 3.25 3.17 3.46Isobutane 3.71 4.36 4.81 3.64 3.79 3.92 4.921-Butene + Isobutylene 1.68 1.76 1.49 1.46 1.64 1.47 1.47N-Butane 0.72 0.87 1.10 0.68 0.76 0.78 1.08Butadiene 0.00 0.00 0.00 0.00 0.00 0.00 0.00Cis-2-Butane 0.85 0.89 0.85 0.76 0.88 0.79 0.85Trans-2-Butene 1.14 1.20 1.13 1.03 1.17 1.08 1.16Gasoline (wt. %) 48.89 48.72 50.00 48.27 51.45 51.00 51.35Cycle Oil (wt. %) 18.96 16.65 16.46 19.26 17.91 17.79 15.65Slurry (wt. %) 13.19 12.17 9.34 14.66 11.34 11.06 8.85Coke (wt. %) 4.83 6.23 7.94 4.62 5.02 5.78 7.49Selectivity (wt. %) 72 68 67 73 73 72 68__________________________________________________________________________

FIG. 15 shows the yield of gasoline as a function of wt. % conversion. At 72 wt. % conversion, for example, there is 2 wt. % increase in gasoline. As pointed out in earlier examples, such an increase has a very major impact on income. In addition to this appreciable selectivity enhancement, FIG. 16 shows the reduction in hydrogen production amounting to an 8-17% reduction over a conversion of 68-74 wt. %. Coke reduction also is significant, amounting to 14% at 73 wt. % conversion.

This example clearly demonstrates that as little as 2000 ppm of manganese offsets the effect of nickel and vanadium in terms of gasoline yield, coke and hydrogen. (See FIGS. 15-17) It also demonstrates that a manganese-promoted catalyst can be realized by deposition on a circulating catalyst to reach a concentration appropriate for feedstocks with varying metal levels.

EXAMPLE 16

Magnetic Hook Properties of These Selective Cracking Catalysts

All of the catalysts used in preceding examples, possess among other attributes, highly magnetic properties. While it is only possible to speculate at this time, it may be that the unusual properties of "magnetic hook" promoted catalysts can be attributed to the unimpaired electrons associated with "magnetic hook" elements. It seems quite likely that they may provide an environment which changes in a very subtle, but beneficially significant way, the nature of the cracking mechanism.

Table 13 shows the magnetic properties of catalysts cited in previous examples. It is apparent that all "magnetic hook" promoted catalysts, showing the unusual selectivity properties of the invention have a magnetic susceptibility value greater than 1.0.times.10.sup.-6 emu/g, or in the case of metal contaminated catalysts, an increase in magnetic susceptibility greater than 1.0.times.10.sup.-6 emu/g, when incorporated as a "magnetic hook" promoter.

TABLE 13______________________________________CatalystAll virgin catalysts after calcination Magnetic Susceptibilityat 1200.degree. F. for 4 hours Xg .times. 10.sup.-6 emu/g______________________________________Example 1No "Magnetic Hook" 0.60Magnetic Hook Catalyst 2.67Example 2AKC No. 1 3.00AKC No. 2 4.21Example 5No Magnetic Hook 0.60Low Magnetic Hook 1.16Intermediate Magnetic Hook 4.23High Magnetic Hook 4.97Example 6No Magnetic Hook 0.82Low Magnetic Hook 2.46Intermediate Magnetic Hook 4.07High Magnetic Hook 4.55Example 7No Magnetic Hook 35.6Plus Magnetic Hook 45.7Increase with Magnetic Hook 10.1Example 918,200 ppm chromium 1.63Example 13Catalyst A no Magnetic Hook 0.49103,000 ppm Magnetic Hook 19.5 .DELTA. Increase 19.0 emu/gm164,000 ppm Magnetic Hook 33.00 .DELTA. Increase 32.5 emu/gmCatalyst B no Magnetic Hook 36.3101,000 ppm Magnetic Hook 53.8 .DELTA. Increase 17.5 emu/gm189,000 ppm Magnetic Hook 56.5 .DELTA. Increase 20.2 emu/gmCatalyst C no Magnetic Hook 0.3966,000 ppm Magnetic Hook 17.7 .DELTA. Increase 17.3 emu/gm171,000 ppm Magnetic Hook 24.62 .DELTA. Increase 24.2 emu/gm______________________________________

FIG. 19 shows the steam stability enhancement of activity of various manganese contents.

FIG. 20 shows the effect of manganese content on selectivity, weight percent selectivity versus various manganese contents.

Modifications

Specific compositions, methods, or embodiments discussed are intended to be only illustrative of the invention disclosed by this specification. Variation on these compositions, methods, or embodiments are readily apparent to a person of skill in the art based upon the teachings of this specification and are therefore intended to be included as part of the inventions disclosed herein.

Reference to documents made in the specification is intended to result in such patents or literature being expressly incorporated herein by reference.

Claims

1. In a process for improving the gasoline selectivity, conversion, olefin hydrogenation and/or coke-make for the conversion of hydrocarbons to lower molecular weight products comprising gasoline by contacting said hydrocarbons with a circulating zeolite-containing cracking catalyst in a riser containing hydrogen, which is thereafter regenerated to remove at least a portion of carbon-on-catalyst, the improvement comprising in combination the steps of:

a) maintaining a catalyst:oil weight ratio of at least about 3; and

b) adding to at least a portion of said cracking catalyst at least 2400 ppm of manganese and/or chromium, based on the weight of the catalyst;

whereby gasoline selectivity is increased by at least 1.0 wt. % (measured at 75 weight % conversion) and conversion is increased by at least 2 wt. %; both as compared to said process without said manganese or chromium.

2. A process according to claim 1 wherein Ni+V on catalyst is at least about 2000 ppm and the gasoline selectivity is increased by at least 1.5 wt. %.

3. A process according to claim 1 wherein said portion comprises from about 5-100 wt. % of the total weight of the circulating catalyst.

4. A process according to claim 1 wherein said portion contains more than 0.5% by weight of sodium.

5. A process according to claim 1 additionally comprising c) maintaining the weight ratio of manganese to total nickel-plus-vanadium on said circulating catalyst above about 0.3.

6. A process according to claim 1 additionally comprising c) maintaining the weight ratio of manganese to total metals on said circulating catalyst above about 0.3.

7. A process according to claim 1 additionally comprising c) maintaining the weight ratio of manganese to total vanadium on said circulating catalyst above about 0.3.

8. A process according to claim 1 additionally comprising c) maintaining the carbon remaining when said catalyst is regenerated to between about 0.05 to 0.2 wt. %.

9. An improved selectivity, improved activity, reduced coking process for conversion of hydrocarbon feed containing more than 1 ppm of nickel and 1 ppm of vanadium comprising contacting said hydrocarbons with a circulating cracking catalyst containing at least 2400 ppm of manganese under cracking conditions to produce products having lower average molecular weight than said feed.

10. A process according to claim 9 wherein the circulating catalyst comprises greater than 0.5 wt % sodium.

11. A process according to claim 9 wherein the circulating catalyst comprises greater than 5 wt % zeolite, and greater than 500 ppm by weight total metals.

12. A process according to claim 9, wherein the circulating catalyst comprises greater than 500 ppm of total nickel plus vanadium.

13. A process according to claim 9 wherein the circulating catalyst comprises greater than 500 ppm of vanadium.

14. A process according to claim 9 wherein the circulating catalyst comprises vanadium in concentration of 100 to 100,000 ppm.

15. A process according to claim 9 wherein the circulating catalyst comprises 2400 ppm to 20 weight percent manganese.

16. A process according to claim 9 wherein said hydrocarbon feed has a Conradson Carbon content greater than 0.3 wt. %.

17. A process according to claim 9 wherein the hydrocarbon feed comprises greater than 1% sulfur.

18. A process according to claim 9 wherein fresh catalyst is added over time to the circulating catalyst and wherein the fresh catalyst comprises manganese in concentration of 2400 ppm to 20 wt %.

19. A process according to claim 9 wherein coke produced in conversion is burned off in a regenerator and where the manganese serves as an oxidation catalyst so as to accelerate the conversion of sulfur in the coke to SO.sub.2 and SO.sub.3.

20. A process according to claim 19 wherein the manganese serves to retain at least 10% of the SO.sub.3 formed in regeneration and to convey it into the reactor as sulfate.

21. A process according to claim 20 wherein the manganese acts as a reductant in the reactor to convert greater than 10% of sulfate in the reactor to SO.sub.2, sulfur and/or H.sub.2 S.

22. A process according to claim 9 wherein the coke produced in conversion is burned off in a regenerator, and where manganese serves as an oxidation catalyst so as to accelerate the conversion of nitrogen in the coke to NO.sub.x.

23. A process according to claim 9 wherein the hydrocarbon comprises more than 2 ppm of nickel and 2 ppm of vanadium.

24. A process according to claim 9 wherein ZSM-5 or other paraffin-selective cracking catalyst and manganese are added to the circulating catalyst.

25. A process for conversion of hydrocarbons containing more than 1 ppm of nickel and 1 ppm of vanadium comprising contacting said hydrocarbons with a circulating cracking catalyst which is gasoline-, coke-, and hydrogen-selective containing 2400 ppm to 20 wt % manganese, having a selectivity advantage as compared to an equivalent catalyst without manganese.

26. A process according to claim 25 wherein the catalyst comprises 0.1 to 20 wt % rare earth and wherein the zeolite content is greater than 5%.

27. A process according to claim 25 and wherein the zeolite content is greater than 5%, and the rare earth content less than 0.1%.

28. A process according to claim 9 wherein the catalyst, when promoted with a magnetic hook, has a magnetic susceptibility increase of about 1 to 40.times.10.sup.-6 emu/g.

29. A process according to claim 9 wherein the virgin catalyst possesses a magnetic susceptibility of about 2 to 40.times.10.sup.-6 emu/g.

30. A process according to claim 9 wherein an operating equilibrium catalyst has an increase of about 1 to 40.times.10.sup.-6 emu/g when promoted with a magnetic hook additive.

31. A process according to claim 9, wherein coke produced in conversion is burned off in a regenerator, and where the manganese accelerates the conversion of carbon to carbon monoxide and carbon dioxide.

32. A process according to claim 9, wherein the sulfur in gasoline is reduced 10% or more as compared to sulfur in gasoline produced without manganese in the catalyst.

33. A process according to claim 9, wherein the ratio of manganese to nickel-plus-vanadium in the circulating catalyst is greater than 0.5.

34. A process according to claim 9, wherein the weight ratio of manganese to nickel-plus-vanadium in the circulating catalyst is maintained at greater than 1.

35. A process for conversion of hydrocarbons containing more than 1 ppm of nickel and 1 ppm of vanadium utilizing a circulating equilibrium cracking catalyst comprising 2000 ppm to 20 wt. % chromium.

36. A process according to claim 12, wherein a portion of circulating catalyst is removed from the process and treated with N.sub.2, steam, and greater than 1% air for one hour or more at 1200.degree. F. or more, and then returned to the process.

37. A process according to claim 9 wherein the yield of isobutane is increased by at least 10 wt. %, measured at 75 wt. % conversion.

38. In a process for improving conversion, gasoline selectivity, increasing coke selectivity, reducing the sulfur in gasoline, and promoting the direct hydrogenation of olefins while converting hydrocarbons to lower molecular weight products by contacting hydrocarbons to be converted in the riser with a circulating zeolite-containing cracking catalyst, which is thereafter regenerated to remove at least a portion of carbon-on-catalyst; the improvement comprising utilizing a catalyst which has been impregnated (during manufacture) with about 9200 ppm to 20 wt. % of manganese, based on the weight of the catalyst;

whereby gasoline selectivity is increased by at least 0.2 wt. % (measured at 75 wt. % conversion) as compared to said process utilizing a catalyst without said manganese.

39. A process according to claim 1 wherein said catalyst contains at least about 90,000 ppm Mn.

40. A process according to claim 1 wherein the catalyst has a magnetic susceptibility value greater than 1.0.times.10.sup.-6 emu/g, exclusive of any metal contaminants on the catalyst.

41. In a process for improving the gasoline selectivity, conversion, coke selectivity, the sulfur in gasoline, and/or direct hydrogenation of olefins while converting hydrocarbons to lower molecular weight products by contacting hydrocarbons to be converted in the riser with a circulating zeolite-containing cracking catalyst, which is thereafter regenerated to remove at least a portion of carbon-on-catalyst;

a) the improvement comprising utilizing a catalyst which has been impregnated (during manufacture) with about 9200 ppm to 20 wt. % of manganese or manganese compound, based on the weight of the catalyst; and

b) maintaining a sodium content of more than of about 0.5% by weight, based on the weight of the catalyst;

whereby gasoline selectivity is increased by at least 0.2 wt. % (measured at 75 wt. % conversion) as compared to said process utilizing a catalyst without said manganese.