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

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.