Abstract: For upgrading heavy slurry oil containing catalyst fines from a catalytic cracking operation, the viscosity of the slurry oil is lowered in a hydrovisbreaking process step. In a preferred embodiment an admixture of the fines containing slurry oil and a metal containing resid oil fraction, resulting from a crude distillation, is passed through the hydrovisbreaker. The hydrovisbreaker effluent is separated into higher and lower boiling fractions with the lower boiling fraction preferably passed through a cracking unit so as to covert the lower boiling fraction to lower molecular weight hydrocarbon products.

Abstract: High octane gasoline and high quality distillate are co-produced by a hydrocracking light cycle oil from a catalytic cracking process under conditions of low to moderate hydrogen pressure and severity to produce a high octane, hydrocracked gasoline. The distillate fraction from the hydrocracker is separated to form a first fraction which boils immediately above the gasoline fraction and a second, higher boiling fraction which is withdrawn as product. The first distillate fraction is recycled, preferably to extinction, to the cracker to increase the paraffinic content of the higher boiling distillate product by removal of the hydroaromatic components in the recycled fraction. The recycled fraction may be mixed with fresh feed to the cracker or may be injected at a higher level in the cracking riser as a secondary feed injection. The paraffinic distillate product has a low sulfur content and a high cetane index and is useful as a road diesel fuel.

Abstract: A fluid catalytic cracking (FCC) process and apparatus which employs relatively more elutriatable catalyst particles comprising intermediate pore zeolite, particularly ZSM-5, and relatively less elutriatable catalyst particles comprising large pore zeolite, preferably zeolite Y. The process and apparatus employ a first stripping vessel which also separates a more elutriatable first portion of catalyst from a less elutriatable second portion of catalyst. The more elutriatable first portion passes to a second stripping vessel, and subsequently recycles to a fluid catalytic cracking reactor riser. The second portion of less elutriatable catalyst passes from the first stripping vessel to a fluid catalytic cracking regenerator vessel and, after being regenerated, recycles to the reactor riser. The more elutriatable first portion contains a higher ratio of intermediate pore catalyst particles to large pore catalyst particles than does the second portion.

Abstract: High octane gasoline and high quality distillate are co-produced by a hydrocracking process in which a catalytic cracking light cycle oil is hydrocracked under conditions of low to moderate hydrogen pressure and severity to produce a high octane, hydrocracked gasoline. The distillate fraction which boils immediately above the gasoline fraction is recycled to the hydrocracker to increase the paraffinic content of this fraction by partial saturation and cracking of the aromatics contained in it so as to form a paraffinic distillate of low sulfur and high cetane index which is useful as a road diesel fuel. A higher boiling distillate fraction of relatively lower aromaticity may also be produced for use as a low sulfur fuel oil. The recycled fraction may be cooled to provide quench for the hydrocracker.

Abstract: A catalytic cracking process is described featuring multiple risers in which a variety of hydrocarbon conversion reactions take place, a stripping unit in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) catalytically cracking a relatively high boiling hydrocarbon charge material in a first riser in the presence of both a first catalyst component which is an amorphous cracking catalyst and/or a large pore crystalline cracking catalyst and a second catalyst component which is selected from zeolite Beta and/or medium pore crystalline silicate zeolite catalyst to provide a variety of products including naphtha and C.sub.3 and/or C.sub.4 olefin;(b) thermally cracking a C.sub.

Abstract: Dewaxing, preferably catalytic dewaxing over zeolite beta or ZSM-5, improves the crackability of a heavy, waxy feed to a catalytic cracking unit. When the catalytic dewaxing occurs at temperatures above about 360.degree. C., using ZSM-5 dewaxing catalyst, high octane gasoline is obtained as a by product of catalytic dewaxing.

Abstract: A catalytic cracking process and apparatus operates with multiple feed injection points to a riser reactor with several enlarged regions. An elutriable catalyst mixture is used, comprising a conventionally sized cracking catalyst and a faster settling, shape selective additive cracking catalyst. Straight run naphtha, and a light, H.sub.2 -rich aliphatic stream are added to the base of a riser reactor. A resid feed is added higher up in the riser, with a gas oil and recycled heavy cycle oil and naphtha streams added even higher up in the riser. The riser has an elutriating base, and an elutriating upper portion, which increase residence time of the shape selective zeolite additive relative to the conventionally sized cracking catalyst.

Abstract: The present invention discloses a catalytic cracking operation featuring a single riser in which a variety of hydrocarbon conversion reactions takes place, a stripping unit in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) converting a relatively high boiling charge material introduced to the riser at a lower level thereof in the presence of a first catalyst component which is an amorphous cracking catalyst and/or a large pore crystalline silicate cracking catalyst to provide lighter products including significant quantities of naphtha; and,(b) converting a naphtha charge material introduced to the riser at a higher level thereof in the presence of a second catalyst componet which is a shape selective medium pore crystalline silicate zeolite catalyst to provide a relatively high octane gasoline product.

Abstract: An improved process for stripping, or desorbing, entrained hydrocarbon material and, where present, sulfur-containing material, from a catalyst mixture recovered from a catalytic cracking reaction zone is described which comprises:(a) providing a quantity of catalyst mixture containing entrained hydrocarbon material and, optionally, sulfur-containing material, in at least one stripping zone in which a stripping gas removes said entrained hydrocarbon material and, where present, sulfur-containing material, the catalyst mixture comprising, as a first catalyst component, an amorphous and/or large pore crystalline cracking catalyst and, as a second catalyst component, a shape selective medium pore crystalline silicate zeolite catalyst, said first and second catalyst components being present in admixture within a common stripping zone or segregated into separate stripping zones; and,(b) conducting an exothermic reaction within the common stripping zone or within the separate stripping zone containing segregated se

Abstract: A catalytic cracking process is described featuring multiple risers in which a variety of hydrocarbon conversion reactions takes place, a stripping unit in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) converting a relatively high boiling hydrocarbon charge material in a first riser in the presence of a catalyst mixture comprising, as a first catalyst component, an amorphous cracking catalyst and/or a large pore crystalline cracking catalyst and, as a second catalyst component, a shape selective medium pore crystalline silicate to provide lighter products including naphtha and C.sub.3 and/or C.sub.4 olefin;(b) converting an ethylene-rich charge material introduced to a second riser at a lower level thereof in the presence of said catalyst mixture to provide heavier products and to increase the temperature of the catalyst in said region; and,(c) converting C.sub.3 and/or C.sub.

Abstract: Liquid fuel products are produced at least partially from coal by passing into a progressive flow catalytic cracking zone a mixture stream of coal and carbometallic oil, forming mobile hydrogen within said zone under conditions including vapor residence time of up to about 10 seconds, at 900.degree.-1,400.degree. F., and total pressure of about 10 to about 50 pounds per square inch absolute introducing said mobile hydrogen into said mixture stream; contacting said stream with zeolite cracking catalyst to produce liquid products while laying down coke on said catalyst; and separating said coked catalyst from said liquid products.

Abstract: A catalytic cracking process is disclosed which comprises catalytically cracking a hydrocarbon charge stock in a catalytic cracking unit possessing at least one reaction zone, stripping zone and catalyst regeneration zone to provide a gasiform product employing as catalyst a mixed catalyst system which comprises, as a first catalyst component, particles of a cracking catalyst which requires relatively frequent regeneration and is relatively hydrothermally stable, and as a second catalyst component, particles of a catalyst which requires less frequent regeneration than the first catalyst component, physical characteristic(s) of particles of first catalyst component differing sufficiently from physical characteristic(s) of particles of second catalyst component as to permit their separation in the stripping zone.

Abstract: The present invention discloses a catalytic cracking process featuring at least one riser reactor, at least one stripping unit and at least one regenerator, which comprises:(a) cracking a C.sub.

Abstract: A catalytic cracking process is provided which comprises:(a) cracking a first heavy hydrocarbon feed in a first riser in the presence of a mixed catalyst composition comprising, as a first catalyst component, an amorphous cracking catalyst and/or a large pore crystalline cracking catalyst and, as a second catalyst component, a shape selective medium pore crystalline silicate zeolite, to provide gasoline boiling range material and one or more light hydrocarbons; and,(b) cracking a thermally treated second heavy hydrocarbon feed in a second riser in the presence of said mixed catalyst composition and in admixture with a gasiform material contributing mobile hydrogen species and/or carbon-hydrogen fragments at the reaction conditions employed to provide gasoline boiling range material in increased yield and/or of higher quality.

Abstract: In the catalytic processing of aromatic hydrocarbon compounds, a hydrocarbon oil is successively contacted at aromatic saturation conditions with a catalyst in a first reaction zone and contacted at a lower temperature with a second portion of the catalyst in the same reactor or in multiple reactors.

Abstract: A catalytic cracking process is provided featuring multiple risers in which a variety of hydrocarbon conversion reactions take place, a stripping unit in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) converting a relatively high boiling hydrocarbon charge material in a first riser in the presence of a first catalyst component which is an amorphous cracking catalyst and/or a large pore crystalline zeolite cracking catalyst to provide lighter products;(b) converting an ethylene-rich charge material introduced to a second riser at a lower level thereof in the presence of a second catalyst component which is a shape selective medium pore crystalline silicate zeolite catalyst to provide heavier products and to increase the temperature of the catalyst in said region; and,(c) converting a naphtha charge material introduced to the second riser at a higher level thereof in the presence of said second catalyst c

Abstract: A fluid catalytic cracking (FCC) process and apparatus which employs relatively more elutriatable catalyst particles comprising intermediate pore zeolite, particularly ZSM-5, and relatively less elutriatable catalyst particles comprising large pore zeolite, preferably zeolite Y. The process and apparatus employ a first stripping vessel which also separates a more elutriatable first portion of catalyst from a less elutriatable second portion of catalyst. The more elutriatable first portion passes to a second stripping vessel, and subsequently recycles to a fluid catalytic cracking reactor riser. The second portion of less elutriatable catalyst passes from the first stripping vessel to a fluid catalytic cracking regenerator vessel and, after being regenerated, recycles to the reactor riser. The more elutriatable first portion contains a higher ratio of intermediate pore catalyst particles to large pore catalyst particles than does the second portion.

Abstract: An apparatus and process for catalytically upgrading an FCC effluent is described, wherein the FCC effluent is contacted with a shape-selective catalyst at low severity conditions prior to fractionation.

Abstract: There is provided a catalytic cracking operation featuring a single riser reaction zone having a lower and an upper section wherein a variety of hydrocarbon conversion reactions takes place, a stripping zone in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) cracking a C.sub.

Abstract: An improved method which provides for an extended cycle length in catalytic lube dewaxing of residual lube oil feedstocks and easier catalyst regeneration. The method may incorporate catalytically dewaxing a feedstock in a fixed bed reactor with or without product recycle, or a series of reactors with interreactor separation of vapors from liquids. Improved performance is achieved by operating the reactor at a temperature between about 490.degree. and about 620.degree. F., employing a high activity crystalline zeolite catalyst having an alpha value between about 50 and about 900 based on the zeolite and a space velocity sufficiently low to produce a dewaxed effluent of desired pour point and to maintain an average catalyst aging rate of less than about 2.degree. F. per day. This relatively low temperature operation allows catalyst performance to be restored by simple hydrogen reactivation.

Abstract: A moderate pressure hydrocracking process in which a highly aromatic, substantially dealkylated feedstock having a boiling point in the range between 300.degree. and 650.degree. F. is processed directly to high octane gasoline by hydrocracking over a catalyst, preferably comprising a large pore size, crystalline alumino-silicate zeolite hydrocracking catalyst such as zeolite Y together with a hydrogenation-dehydrogenation component. The feedstock which is preferably a light cut light cycle oil has an aromatic content of at least 50, usually at least 60 percent and an API gravity not more than 25. The hydrocracking typically operates at 600-1000 psig at moderate to high conversion levels to maximize the production of monocyclic aromatics which provide the requisite octane value to the product gasoline.

Abstract: The fluidized catalytic cracking process described herein is undertaken in a first and a second riser reaction zone in which a variety of hydrocarbon conversion reactions take place, at least one stripping zone in which entrained hydrocarbon material is removed from catalyst and at least one hydrothermal catalyst regeneration zone in which spent cracking catalyst is regenerated.

Abstract: A moderate pressure hydrocracking process is disclosed in which substantially dealkylated heavy distillate feedstocks are processed directly to high octane gasoline over a catalyst, preferably comprising a crystalline silicate zeolite hydrocracking component having a Constraint Index less than 2. The bottoms fraction produced from the contacting may be passed to an FCC unit for further processing. In another embodiment, the substantially dealkylated heavy distillate feedstock may be fractionated into a lighter boiling stream and a heavier boiling stream for better ease of processing.

Abstract: A process for the conversion of heavy hydrocarbon feedstocks which are characterized by high molecular weight, low reactivity and high metal contents comprising feeding the feedstock to a hydrodemetallization zone where the feedstock is contacted with hydrogen and a catalyst capable of demetallizing organometallic complexes of high molecular weight and cracking resistance, thereafter removing the effluent from the demetallization zone and feeding same to the thermal cracking zone where the effluent is contacted with hydrogen and thereafter feeding the product from the cracking zone to a hydrocarbon conversion zone where the product is contacted with hydrogen and a catalyst capable of cracking molecules of high cracking resistance.

Abstract: A mixture of hydrocarbons consisting of gas oil and residual oil is catalytically cracked in the presence of a fluidized zeolite catalyst. The mixture of hydrocarbons is classified by boiling range as a 550.degree.-1000.degree. F. gas oil and a 1000+.degree. F. vacuum residuum. The gas oil is selectively cracked using a freshly regenerated fluid zeolite catalyst having less than 0.1 wt % residual carbon to give a high yield of desirable liquid hydrocarbon boiling from about 60.degree.-670.degree. F. The vacuum residuum is injected into the riser reactor at a point near the riser outlet to quench the cracking reactions in the gas oil. The vacuum residuum undergoes a small amount of reaction removing undesirable materials and yielding a liquid hydrocarbon boiling up to about 1000.degree. F. The amount of vacuum residuum cracking and overall yield of liquid hydrocarbons are controlled by downstream injection of vacuum residuum into the riser.

Abstract: A process and system for the production of olefins from heavy hydrocarbon feedstocks. A heavy hydrocarbon feed is first pretreated at high pressure and moderate temperatures to preferentially remove coke precursors in a liquid product. The pretreated hydrocarbon is then separated into lighter and heavier fractions; the lighter fraction being further thermally cracked to produce olefins.

Abstract: A novel FCC method and apparatus, wherein a fresh hydrocarbon feed of relatively poor crackability is fed to one riser of a two riser system. The spent catalyst from the other of the two risers is fed to the inlet of the first riser to produce relatively mild cracking conditions. Improved total gasoline plus distillate yields are achieved. The novel two riser system facilitates heat balancing of the system.

Abstract: A three stage catalytic cracking process capable of converting high molecular weight hydrocarbons containing catalyst poisons into products of lower molecular weight by cascading catalyst from a fluid catalytic cracking unit to a reduced crude conversion unit to a metals removal unit is disclosed. Efficiencies in conversion operations are made possible.

Abstract: An aromatic gasoline component is prepared in a multi-step petroleum refining process starting with a heavy carbometallic petroleum fraction which is catalytically cracked to yield a light catalytic cycle oil which, in turn, is mildly hydrogenated to produce a partially saturated bicyclic hydrocarbon fraction which itself is catalytically cracked to yield a monoaromatic hydrocarbon fraction from which is recovered a gasoline product. The bicyclic hydrocarbons are converted to monoaromatics by selective partial saturation and ring scission.

Abstract: Hydrocarbon feedstocks, especially those high in Ramsbottom carbon, are vaporized by contact with a relatively inactive coked cracking catalyst, separating the resulting intermediate into a high and low boiling fraction, and cracking the high boiling fraction in a fluid catalytic cracker containing active cracking catalyst.

Abstract: There is disclosed a process for cracking a metal-containing feed in the presence of a fluid cracking catalyst composition comprising contacting said feed at catalytic cracking conditions with a catalyst composition comprising a zeolitic crystalline aluminosilicate, sepiolite and matrix material, characterized in that the sepiolite is present in non-dispersed form.

Abstract: A two-stage cascade flow fluid catalytic cracking process capable of converting high molecular weight hydrocarbons containing catalyst poisons into products of lower molecular weight with high activity cracking catalyst susceptible to catalyst poisons, the cascade flow process resulting in higher yields of desired motor fuel fractions than those obtainable with conventional riser flow fluid catalytic cracking processes. Catalyst poisons, e.g.

Abstract: A process for economically converting carbo-metallic oils to lighter products. The carbo-metallic oils contain 650.degree. F.+ material which is characterized by a carbon residue on pyrolysis of at least about 1 and a Nickel Equivalents of heavy metals content of at least about 4 parts per million. This process comprises flowing the carbo-metallic oil together with particulate cracking catalyst through a progressive flow type reactor having an elongated reaction chamber, which is at least in part vertical or inclined, for a predetermined vapor riser residence time in the range of about 0.5 to about 10 seconds, at a temperature of about 900.degree. to about 1400.degree. F., and under a pressure of about 10 to about 50 pounds per square inch absolute sufficient for causing a conversion per pass in the range of about 40% to 90% while producing coke in amounts in the range of about 6 to about 14% by weight based on fresh feed, and laying down coke on the catalyst in amounts in the range of about 0.

Abstract: A fluid catalytic cracking process and apparatus in which a plurality of hydrocarbon feedstocks including at least one normally gaseous paraffinic hydrocarbon feedstock and at least one normally liquid hydrocarbon feedstock are subjected to cracking reaction conditions in a common transport type reaction zone in the presence of a zeolite cracking catalyst. Fresh hot regenerated catalyst is first contacted with a normally gaseous paraffinic hydrocarbon under dehydrogenation reaction conditions effecting conversion to normally gaseous olefins, and fresh normally liquid cracking charge stock is contacted in the reaction zone under cracking reaction conditions with the gaseous paraffinic and olefinic hydrocarbons.

Abstract: Conversion of a hydrocarbon feed containing a catalyst-deactivating component in a riser FCC cracking system can be increased by employing a baffle in the lower part of the riser to exclude a portion of the upwardly flowing catalyst from initial contact with feed hydrocarbons containing the catalyst-deactivating component. Part of the catalyst flowing upwardly through the riser thereby is excluded from contact with the catalyst-deactivating component until the catalyst-deactivating component has been at least partially removed from the resulting hydrocarbonaceous vapor by deposition on another portion of the upwardly flowing catalyst.

Abstract: A process is disclosed for upgrading a hydrocarbon oil feed having a significant content of metals, especially vanadium, to provide a higher grade of oil products by contacting the feed under sorbing conditions in an upgrading zone with a high surface area, high pore volume sorbent material containing an added alkaline metal to neutralize acidic cracking sites. Upgrading conditions are such that coke and metals are deposited on the sorbent in the upgrading zone. Coked sorbent is regenerated by contact with an oxygen containing gas under regeneration conditions to remove the coke, and regenerated sorbent is recycled to the upgrading zone for contact with fresh feed. The added alkaline metal is present on the sorbent in an amount sufficient to neutralize substantially all of the acidic cracking sites and provide a sorbent material having a MAT relative activity in the range of about 0 to about 1 percent.

Abstract: A catalytic conversion process wherein a slowly deactivating catalyst contained in a multiplicity of fixed bed is operated in a serial fashion whereby the operating temperature of each catalyst bed is higher than the preceeding bed and the last catalyst bed in the series is removed from operation when a predetermined operating temperature is reached, the catalyst in the removed bed is reactivated or replaced and the reactivated or fresh bed is returned to service as the first bed in the series of fixed catalyst beds.

Abstract: An apparatus for the fluidized catalytic cracking of hydrocarbon feedstocks. The apparatus accomplishes the separate and simultaneous contacting of two fluid streams, at least one of which is a hydrocarbon feedstock, with cracking catalyst followed by the removal of the vaporous products therefrom with minimal commingling. The apparatus comprises multiple riser reactors, a partition positioned in the disengaging vessel separating the dilute phase into two regions, and a control system for controlling the direction and volume of flow between the two dilute phase regions at a desired point. The apparatus is particularly suitable for use in the simultaneous fluidized catalytic cracking of dissimilar hydrocarbon feedstocks with minimal commingling of the products therefrom.

Abstract: A process for the production of highly aromatic petroleum fractions from various petroleum feedstocks suitable for catalytic cracking in a fluidized catalytic cracking unit wherein heavy gas oil from a first fluidized catalytic cracking unit is subjected to further catalytic cracking in a separate fluid catalytic cracking unit at temperatures in the range of 565.degree. to 650.degree. C. producing light olefins and a heavy gas oil consisting of essentially aromatic components suitable for the production of needle coke, and the method of producing needle coke from various hydrocarbon cracking stocks.

Abstract: This invention comprises a process for cracking a hydrocarbon charge stock using a used FCC catalytic composite comprising a zeolitic crystalline aluminosilicate dispersed in a porous inorganic matrix. Particles of zeolitic crystalline aluminosilicate having diameters less than the diameters of the pores of the composite are impregnated into the composite preferably by contacting the composite with an aqueous slurry of the particles and the evaporating off the water of the slurry.

Abstract: An apparatus for the fluidized catalytic cracking of hydrocarbons comprising two independent transfer line reactors, each of which is associated with an independent cyclone separation system and wherein the cyclone separation systems are located within a common reactor vessel. The apparatus is suitable for use in the simultaneous fluidized catalytic cracking of dissimilar hydrocarbon feedstocks without commingling either the feedstocks or the products therefrom.

Abstract: An improved fluid catalytic cracking process providing improved product yield and selectivity and reduced catalyst deactivation which employs a split flow of catalyst to the reactor riser.

Abstract: An improved fluid catalytic cracking process providing improved product yield and selectivity which employs a split flow of recycled, regenerated catalyst to the reactor riser. Process operating temperatures control the flow rates of the recycled, regeneration catalyst.

Abstract: A riser cracking operation is described for the production of gasoline and distillate material by the combination of cracking fresh gas oil charged to the base of a riser cracking zone for admixture with freshly regenerated catalyst to form a suspension thereof at an elevated cracking temperature, a second hydrocarbon fraction of more difficult cracking characteristics is charged to the suspension rising in the riser cracking zone at a point selected from 10 to about 30 feet above the riser bottom and the riser inlet temperature is restricted to be within the range of 900.degree. to 1000.degree. F.

Abstract: Metals such as nickel, vanadium and iron contaminating a cracking catalyst are passivated by contacting the contaminated catalyst with a passivating agent dissolved in a secondary feedstock stream having a temperature sufficiently low to avoid or minimize decomposition of the passivating agent.

Abstract: Used cracking catalyst fines from a cracking process wherein antimony or a compound thereof is used as a metals passivation agent are used as an efficient passivation agent in a cracking process.

Abstract: The fluid catalytic cracking of a residual oil fraction comprising metal contaminants and/or asphaltene type coke formers is processed by injecting the oil into the upper portion of a riser cracking operation under conditions to effect partial conversion thereof over a catalyst inactivated by carbonaceous deposits. A 650.degree.0 F. plus product of the low severity cracking is passed in contact with freshly regenerated catalyst under conditions of high conversion severity in the lower portion of the riser.

Abstract: An improvement in the fluid cracking process is obtained by contacting the hydrocarbon feed in a riser reaction zone first with a recycled coke-containing spent catalyst and then contacting the resultant mixture with freshly regenerated catalyst to produce the desired conversion of the hydrocarbon feed and a coke-containing spent catalyst, a portion of the spent catalyst being recycled without regeneration to the inlet of the reaction zone and the remainder being regenerated and returned to an intermediate point in the reaction zone. The recycled coke-containing spent catalyst has sufficient activity so that the highly reactive nitrogen and carbon residue containing hydrocarbon contaminants in the oil feed will deposit on the spent catalyst and thus minimize the deactivation of the freshly regenerated catalyst used in the subsequent cracking of the oil feed.

Abstract: A process for producing gasoline which comprises cracking of a heavy petroleum feedstock in the presence of an alumino-silicate zeolite-containing catalyst maintained in a condition of an ascending flow at a temperature ranging from 480.degree. to 520.degree. C. and a mass velocity of said feedstock of from 6 to 40 hr.sup.-1 in the direction of said ascending flow with the formation of a reaction mixture containing gasoline, a fraction with a specific gravity of from 0.75 to 0.85 and a fraction with a specific gravity of from 0.85 to 0.95; the resulting reaction mixture is isolated from the catalyst and subjected to separation; said separated fractions are employed as recycle. The fraction with a specific gravity of from 0.75 to 0.85 is subjected to cracking in the presence of said catalyst which is in a condition of an ascending flow at a temperature of from 460.degree. to 520.degree. C. and a mass velocity of said fraction of from 6 to 40 hr.sup.-1 in the direction of said ascending flow.

Abstract: A method for catalytically cracking an isolated reactant feed, 80-100 volume percent of which is a substantially mono-aromatic hydrocarbon fraction boiling in the boiling range of heavy gasoline and the remainder of which is a vaporizable hydrocarbon fraction, under effective cracking conditions of cracking temperature, catalyst composition, catalyst activity, catalyst-to-feed weight ratio, and weight hourly space velocity, to produce an isolated product having increased low molecular weight olefin and low molecular weight mono-aromatic contents and a reduced sulfur content and having a high octane rating.