Plasma-catalysis of metal loaded SBA-15 for toluene removal: Comparison of continuously introduced and adsorption-discharge plasma system

Abstract

The destruction of low concentrations of toluene using two non-thermal plasma catalytic systems has been investigated in this study. Metals (Ag, Mn and AgMn) loaded SBA-15 catalysts were prepared by an impregnation method and further characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherm and H2-temperature-programmed reduction (H2-TPR). In our research, two types of plasma catalytic system, including continuously introduced and adsorption-discharge plasma system, were studied. The results showed that the loaded metals retained the highly ordered mesopore structure of SBA-15. The activities of as-prepared catalysts for the toluene conversion and carbon balance in both catalytic systems decreased in the following order: AgMn/SBA-15>Ag/SBA-15>Mn/SBA-15>SBA-15, which were consistent with the ozone decomposition activities. Compared to traditional continuously introduced plasma system, the adsorption-discharge plasma system slightly increased toluene conversion and significantly improved the carbon balance. The reaction intermediates and products in two plasma systems were detected by the GC–MS and in situ FT-IR analyses. The results showed that the types of organic byproducts detected in the adsorption-discharge system greatly decreased compared to continuously introduced system. Moreover, the different mechanisms of two systems were discussed.