SELECTIVE DISPROPORTIONATION OF TOLUENE OVER RARE EARTH MODIFIED HZSM-5 ZEOLITE TO PRODUCE BENZENE AND p-XYLENE

Abstract

The modification of H-ZSM-5 was carried out by the impregnation of rare earth ions to make 6% La!H-ZSM-5, 6%Ce/H-ZSM-5, 6%La-Ce/H-ZSM-5 (3%Ce, 3%La). The pore size of HZSM- 5 is ideal to selectively produce p-xylene among its other isomers. The activity and selectivity for toluene disproportionation to produce p-xylene and benzene was tested in a continuous flow fixed bed reactor in the reaction temperature range 350 to 500°C. The impregnation caused modifications in pore size, the physicochemical properties were tested using XRD, BET, TPD, TGA, SEM and TEM. Rare earth exchanged H-ZSM-5 showed better selectivity for p-xylene with toluene conversion higher than the thermal equilibrium • concentration. Cerium was found to be most suitable for p-xylene selectivity, whereas, bimetallic La-Ce!H-ZSM-5 was found to be good for p-xylene selectivity as well as for toluene conversion