Alkyl transfer steps in the catalytic alkylation of benzene, toluene, and cyclohexane

Abstract

The rate of the catalytic redistribution of isotopic carbon in binary mixtures of benzene and toluene, benzene and ethylbenzene, toluene and xylene, toluene and ethylbenzene, cyclohexane and methylcyclohexane was investigated over supported Pt, Ir, Ru, and Au. The influence of the following experimental variables was assessed: hydrocarbon partial pressure ratios, 3 x 10-3 to 30; temperature, 185 to 400 [deg]C; catalyst support, A12O3, MgO; catalyst acidity and basicity, and method of catalyst preparation. The results are discussed in the framework of processes of competitive and reactive chemisorption of hydrocarbon mixtures. The dependence of the reaction rate upon the hydrocarbon partial pressure ratio is considered in detail. Displacement effects were found when xylene isomers were present simultaneously. The insight that the carbon redistribution reaction may provide in investigations on the thermodynamic and kinetic aspects of alkyl transfer steps at catalytic surfaces is pointed out.