Xylene isomerization

Abstract

Mixtures of C 8 aromatic hydrocarbons are contacted in vapor phase with acid zeolite ZSM-5. The xylene content is thereby isomerized and the ethyl benzene content of the charge is converted in a manner which results in net increase of aromatic rings.

I claim: 
     
       1. In a process for conversion of a mixture of aromatic compounds having eight carbon atoms, said mixture containing ethyl benzene and xylenes, to isomerize xylenes contained in said mixture and convert at least part of ethyl benzene so contained to xylene or to compounds readily separable by distillation from eight carbon atom aromatics; the improvement which comprises contacting such mixture of eight carbon atom aromatic compounds with a catalyst which comprises acid zeolite of the ZSM-5 type, acid zeolite ZSM-12 .[.or acid zeolite ZSM-21.]. .Iadd., acid zeolite ZSM-35 or acid zeolite ZSM-38 .Iaddend.in vapor phase and in the absence of added hydrogen at a temperature of about 500° F. to about 1,000° F. .Iadd. 2. The process of claim 1 wherein said contacting is effected at a pressure in the range of 0 to about 1000 psig. .Iaddend..Iadd. 3. The process of claim 1 wherein said contacting is effected at atmospheric pressure. .Iaddend..Iadd. 4. The process of claim 1 wherein said contacting is effected at 150 psig. .Iaddend..Iadd. 5. The process of claim 1 wherein said contacting is effected at 200 psig..Iaddend.