Patent ID: 6600081
Filing Date: 2003-07-29
Classification: C07C

Abstract:
A process for the manufacture of xylene from 2,2,4-trimethylpentane, comprising:(a) feeding to a reactor a reactor feed comprising 2,2,4-trimethylpentane, and a diluent gas selected from the group consisting of nitrogen, methane, ethane, propane, and mixtures thereof wherein the molar concentration of 2,2,4-trimethylpentane to said diluent gas is about 50% or less; (b) contacting, in the vapor phase, said reactor feed with a catalyst comprising chromium to produce a reactor effluent containing xylene and by-products comprising 2,2,4-trimethylpentene, isobutane, isobutylene, and unreacted 2,2,4-trimethylpentane; (c) separating the isobutane and isobutylene from step (b) and passing said separated isobutane and isobutylene over an acid dimerization catalyst, at a temperature from about 5Â° C. to about 50Â° C., whereby the isobutane and isobutylene are dimerized to produce a mixture consisting essentially of trimethylpentane, trimethylpentene-1, and trimethylpentene-2, and, optionally, recycling said products to the reactor of step (a); and (d) optionally, separating xylene from said by-products, unreacted 2,2,4-trimethylpentane and diluent gas.