Abstract: Alkylation of an aromatic is provided in a reactor having a central alkylation zone, and a surrounding transalkylation zone. The reaction mixture flows cocurrently through the alkylation zone and then into the surrounding transalkylation zone, with the mixture flowing in approximate plug flow through the transalkylation zone to the outlet thereof. Polyalkyl aromatics recovered from the effluent are recycled to the inlet end of the transalkylation zone.

Abstract: A new composition of matter, a method for the preparation of a rubidium exchanged Type X structured zeolite and a separation process employing the same. The zeolite adsorbent is prepared by a procedure employing the aqueous ion exchange step and a final activation step including contacting a sodium-X zeolite with a rubidium salt in aqueous solution. The process involves the selective separation of ethylbenzene from a C.sub.8 aromatic isomer mixture containing ethylbenzene and employs the use of the rubidium exchanged type X structured zeolite in an adsorption separation process.

Abstract: Disproportionation of toluene to produce benzene and xylenes rich in the para isomer is accomplished by subjecting toluene to disproportionation conditions in the presence of a catalyst comprising the crystalline aluminosilicate zeolite ZSM-23.

Abstract: A hydrocarbon mixture is fed to a system of adsorbents in a plug flow so as to form at least one displacement boundary in the system to accumulate the composition in the vicinity of the boundary. The process is simple to operate and suitable for separation of a hydrocarbon mixture containing components with similar physical and chemical properties such as a mixture of hydrocarbon isomers.

Abstract: A catalytic process is provided for the selective production of para-xylene by contacting toluene, under methylation conditions, with a methylating agent in the presence of a catalyst comprising a crystalline aluminosilicate zeolite having a silica to alumina ratio of at least about 12, a constraint index, as hereinafter defined, within the approximate range of 1 to 12 and which has combined therewith magnesium in an amount of at least about 0.5 percent by weight.

Abstract: Process for the selective production of para-xylene by methylation of toluene in the presence of a catalyst comprising a crystalline aluminosilicate zeolite, said zeolite having a silica to alumina ratio of at least about 12 and a constraint index, as hereinafter defined, within the approximate range of 1 to 12, which catalyst has undergone prior modification by treatment with an ammonium hydrogen phosphate to deposit at least about 0.5 weight percent of phosphorus thereon.

Abstract: A novel active alumina which has been treated with sulfate ion, is found to be particularly characterized by increased performance when used as a support for catalyst which may be used in hydrocarbon conversion processes such as steam dealkylation.

Abstract: Para-xylene is selectively adsorbed from a C.sub.8 aromatic hydrocarbon feed by a crystalline selective adsorbent, and then the para-xylene is subsequently desorbed by contacting the resulting adsorbent with a 1-(lower alkyl)-4-isopropylbenzene desorbent, wherein the lower alkyl group contains one to two carbon atoms. The desorbent effectively desorbs the para-xylene from the adsorbent, and the para-xylene may be produced as an enriched product.

Abstract: A process for hydrodealkylating alkyl-substituted aromatic hydrocarbons, e.g., toluene, by reaction with hydrogen in the absence of water vapor under relatively mild reaction conditions, and a catalyst therefor are disclosed. The process is effected at a temperature of from about 450.degree. and 650.degree. C., preferably from about 520.degree. to 620.degree. C., and pressures of from about 1 to about 30, preferably from about 5 to about 20 bar, and a liquid hourly space velocity of from about 1 to about 10, preferably from about 3 to about 8, in the presence of a catalyst which comprises a metal combination of rhodium and at least one metal selected from the group consisting of copper, nickel, cobalt, iron, and zinc, and a support comprising activated alumina having a specific surface of between about 100 and about 350 m.sup.2 /g and a total pore volume of from about 0.5 to about 0.8 cm.sup.3 /g.

Abstract: Alkylaromatic hydrocarbons are dealkylated in the presence of a catalyst typically containing oxides of nickel, potassium, and aluminum.

Abstract: A hydrocarbon stream comprising C.sub.2 to C.sub.8 hydrocarbons is stripped at a high temperature to allow passage of the stripper bottoms stream into a reaction zone without further heating, and the effluent of the reaction zone is then heat exchanged against the feed stream to the stripper column to recover heat. Operation of the reaction zone at the desired temperature is achieved by adjusting the amount of the stripper bottoms stream which is split off for cooling by heat exchange against the feed to the stripper column. The cooled split-off portion is then admixed with the remaining high temperature portion. Adjusting the flow rate of the portion of hot reaction zone effluent which is heat exchanged against the stripper feed stream is performed to control either the temperature of the stripper feed stream or the temperature of the reaction zone effluent as it is passed to a downstream operation.

Abstract: A process for the purification of crude alkylate from the Friedel-Crafts alkylation of aromatics comprises introducing anhydrous ammonia under anhydrous conditions into the crude alkylate(a) at a temperature of 40.degree.-70.degree. C, preferably 50.degree.-60.degree. C;(b) to a pH of 7-9, preferably 7.5-8.5; and(c) at a pressure of 0.4-25 bars, preferably 2-5 bars. During the introduction of ammonia, the crude alkylate can be agitated.

Abstract: A catalytic process is provided for the selective production of the para isomer of the compound: ##STR1## WHERE N IS 1 OR 2 BY CONTACTING A HYDROCARBON PRECURSOR SELECTED FROM THE GROUP CONSISTING OF ETHYLBENZENE AND MIXTURES OF ETHYLBENZENE OR TOLUENE WITH ETHYLENE, UNDER CONVERSION CONDITIONS, WHICH ENTAIL DISPROPORTIONATION OF THE ETHYLBENZENE OR ALKYLATION OF THE ETHYLBENZENE OR TOLUENE WITH ETHYLENE, IN THE PRESENCE OF A CATALYST COMPRISING A CRYSTALLINE ALUMINOSILICATE ZEOLITE, CHARACTERIZED BY A SILICA TO ALUMINA RATIO OF AT LEAST ABOUT 12, A CONSTRAINT INDEX, AS HEREINAFTER DEFINED, WITHIN THE APPROXIMATE RANGE OF 1 TO 12 AND A MINIMUM CRYSTAL DIMENSION GREATER THAN ABOUT 0.5 MICRON, WHICH ZEOLITE HAS UNDERGONE PRIOR SEQUENTIAL TREATMENT INCLUDING:(1) steaming at a temperature of between about 250 and about 1000.degree. C for a period of at least 0.5 hour;(2) impregnation with at least about 0.25 weight percent of phosphorus oxide;(3) impregnation with at least about 0.

Abstract: A process is provided for the selective production of para dialkyl substituted benzenes wherein the alkyl group contains from 1 to 4 carbon atoms which comprises contacting, under conversion conditions, a hydrocarbon precursor selected from the group consisting of mono alkyl-substituted benzenes having 1-4 carbon atoms in the alkyl substituent and a mixture of said precursor or benzene with an alkylating agent containing from 1 to 4 carbon atoms with a catalyst comprising a porous crystalline aluminosilicate zeolite having deposited thereon a coating of silica which extensively covers and resides substantially exclusively on the external surface thereof, said zeolite being characterized by an activity, in terms of alpha value, of between about 2 and about 5000, a xylene sorption capacity greater than 1 gram/100 grams of zeolite and an ortho xylene sorption time for 30 percent of said capacity greater than 10 minutes, said sorption capacity and sorption time being measured at 120.degree. C and a pressure of 4.

Abstract: A process for the conversion of aromatic hydrocarbons is disclosed which is especially useful for reaction of an alkylating agent, preferably propylene, with an aromatic hydrocarbon. Novel feature is use of a catalyst system comprising TiCl.sub.4 and a Group III-A metal oxide.

Abstract: An improved method for the concentration of a slurry containing a solid particulate component is described. In the method, the slurry is contacted with a rotatable filtration assembly and some liquid is withdrawn from the slurry. When the rotational velocity of the unit is sufficient to develop a substantial centrifugal force at the periphery of the assembly, the process is continuous. The method is especially useful for the concentration of a p-xylene slurry.

Abstract: A process for the conversion of aromatic hydrocarbons is disclosed which is especially useful for reaction of an alkylating agent, preferably propylene, with an aromatic hydrocarbon. Novel feature is use of a catalyst system comprising TiCl.sub.4 and a Group III-A metal oxide.

Abstract: Process for the conversion of aromatic hydrocarbons. Especially useful for reaction of an alkylating agent, preferably propylene, with an aromatic hydrocarbon. Novel feature is use of a catalyst system comprising TiF.sub.4 and a metal oxide which possesses surface hydroxyl groups.

Abstract: Process for the conversion of aromatic hydrocarbons. Especially useful for reaction of an alkylating agent, preferably propylene, with an aromatic hydrocarbon. Novel feature is use of a catalyst system comprising TiF.sub.4 and a metal oxide which possesses surface hydroxyl groups.

Abstract: A C.sub.8 -aromatic hydrocarbon mixture containing para-xylene is subjected to adsorption-separation in contact with a crystalline aluminosilicate adsorbent which selectively retains para-xylene. Raffinate therefrom, being a para-xylene deficient C.sub.8 -aromatic concentrate, is isomerized in contact with a catalytic composite containing a Group VIII noble metal component to form additional para-xylene. Isomerization conditions employed to produce the para-xylene, also effect the formation of olefinic material. To prevent the adverse effect which olefins exhibit toward the efficiency and capacity of the zeolitic adsorbent, the isomerization effluent is subjected to hydrotreating at conditions which provide a liquid-phase operation and saturate olefins without saturation of the C.sub.8 -aromatics. The hydrotreating is effected in contact with a substantially non-acidic catalytic composite comprising a Group VIII noble metal component.