Evidence for the enhancement of the catalytic action of Zn-ZSM-5-based catalysts for propane aromatization using microwave radiation

Abstract

The behaviour of Zn-ZSM5-based catalysts in the aromatization of propane can be influenced by a pretreatment procedure involving exposure to microwave radiation. The effect is dependent on the zinc content of the samples (varied from 0.9 to 4.4 mass%) being most clearly seen with intermediate Zn loadings (2.2 mass%). The microwave induced effect results in higher BTX (benzene, toluene, xylene) selectivity but lower overall activity. Attempts to induce even more dramatic effects via the use of admixtures of ZnZSM-5 and iron–silica, with the latter incorporated as a microwave absorbing medium, were not successful, though a beneficial effect (higher BTX selectivity) of having iron–silica in the admixture even without microwave radiation was noted. The two beneficial effects are almost certainly due to different changes occurring in the solid catalysts. The microwave induced changes possibly occur due to localized heating effects.