GB786305A - A process for isomerizing dialkyl benzenes in the liquid phase - Google Patents

Abstract

Diisopropyl benzene or a mixture of diisopropyl benzene isomers is isomerized by passing in the liquid phase over an aluminium silicate catalyst at 100-300 DEG C. The catalyst may consist of silicates formed from silica and smaller amounts of alumina and of oxides of other metals such as iron, zirconium, magnesium, calcium, sodium and potassium, and of oxides of hydrogen, carbon and sulphur. The catalyst may consist of 85-90 per cent SiO2 and 15-10 per cent Al2O3. The catalyst preferably contains less than 3.5 per cent of water. The process may be carried out at a pressure of 10-80 atm. and preferably less than 5 parts by volume of liquid reactants are passed through each part of the reaction zone per hour. The process may be carried out by alkylating benzene, cumene or mixtures thereof with propene, distilling from the reaction mixture the fraction containing o- and m-diisopropyl benzene and isomerizing this fraction to obtain benzene, cumene, o-, m- and p-diisopropyl benzenes and higher alkylates. The o-isomer is practically completely converted and the m-and p-isomers can be separated by distillation. The benzene and cumene formed may be recycled to the alkylation process; the higher alkylates may either be dealkylated or trans-alkylated with benzene and cumene and the p-isomer separated from the diisopropyl benzenes formed in each case. Specifications 749,186 and 749,187 are referred to.