Highly efficient and selective Ru and Ce modified ZSM-5 catalysts for catalytic oxidation of toluene

Abstract

Ce/ZSM-5 catalysts with different concentration gradients of Ce were prepared by the impregnation method, and the degradation performance of toluene with different catalysts was investigated. Under the conditions of toluene , concentration= 1000 ppm, N2/O2 volume ratio= 4:1, and space velocity = 60,000 mL/(g·h), Ce(20)/ZSM-5 catalyst was superior to the other Ce/ZSM-5 series in catalytic performance. However, the CO2 selectivity for toluene conversions of 90% was 16%. Ru(1)Ce(20)/ZSM-5 catalyst modified by Ru had completely converted toluene at 245 ℃ without other by-products, and the catalyst maintained good stability. The load of Ru increased the pore volume and average pore diameter of the catalyst, the strong interaction between Ru and Ce, the synergy between Ru-Ce and ZSM-5, the amount of Ce4+ with the strong oxidising ability and the mobility of active oxygen. The mobility of active oxygen was conducive to the destruction of the intermediates produced during the oxidation process. The appropriate density ratio of strong and weak acids formed was also conducive to an enhance performance of the catalytic degradation of toluene.