Manufacture of aromatic compounds

In a process for isomerizing the xylene content of a charge mixture of eight carbon atoms aromatic hydrocarbon compounds which mixture contains xylene, and ethylbenzene by contact at conversion conditions with a catalyst comprising a zeolite having a silica/alumina ratio greater than 12 and a constraint index of 1 to 12, the improvement resulting in conversion of ethylbenzene to benzene and conversion of higher alkyl benzenes to benzene, toluene and xylene which comprises including in the charge mixture alkyl aromatics of more than eight carbon atoms, maintaining the conversion pressure at less than 100 pounds per square inch and the conversion temperature at about 800.degree. F. to 1000.degree. F. and using such catalyst comprising a zeolite of reduced acid activity such that less than 2 weight percent of xylene is converted to compounds other than xylene when contacted with said catalyst at 900.degree. F. 0 psig and LHSV of 5.

A process for the manufacture of aromatic hydrocarbons which comprises subjecting a hydrocarbon naphtha to catalytic reforming under conditions to convert naphthenes to aromatic hydrocarbons in a reformate reaction product, distilling said reformate to separate compounds of less than eight carbons from a heavy reformate, mixing said heavy reformate with a recycle steam hereafter defined, contacting the resultant mixture at pressure less than 100 pounds per square inch and a temperature of about 800.degree.-1000.degree. F. with a zeolite catalyst having a constraint index of 1 to 12, a silica/alumina ratio above about 12 and reduced acid activity such that less than 2 weight percent of xylene is converted to compounds other than xylene when contacted with said catalyst at 900.degree. F., 0 psig and LHSV of 5, whereby to isomerize xylene content of said mixutre and to convert ethylbenzene and alkylbenzenes of more than eight carbon atoms to benzene, toluene and xylene, distilling the product of said contacting to separate compounds of less than eight carbon atoms and compounds of more than eight carbon atoms from a C.sub.8 fraction, recovering at least one xylene isomer from said C.sub.8 fraction to provide a stream lean in said recovered isomer and mixing said lean stream with said heavy reformate as the recycle steam aforesaid.

In a process for manufacture of a desired xylene isomer which comprises separating the desired xylene isomer from a mixture containing the three xylene isomers, isomerizing the resultant mixture lean in at least one isomer to generate additional amounts of said desired isomer, separating compounds of boiling point higher and lower than xylenes from the isomerization product to provide a recycle stream, mixing said recycle stream with additional aromatic compounds of eight carbon atoms including the three xylene isomers and supplying the resultant mixture to the step aforesaid of separating a desired isomer, the improvement which comprises isomerizing the said mixture lean in a desired isomer at a temperature of about 800.degree.-1000.degree. F., a pressure less than 100 pounds per square inch and a weight hourly space velocity between 1 and about 200 by contact with a zeolite catalyst having a constraint index of 1 to 12, a silica to alumina ratio greater than 12 and a reduced activity such that less than 2 weight percent of xylene is converted to other compounds when contacts with said catalyst at 900.degree. F., 0 psig and LHSV of 5.