Non-thermal plasma-enhanced catalytic activation of Mn–Zr–La/Al2O3 catalyst for meta-xylene degradation: Synergetic effects and degradation mechanism

The LaMnO3 catalysts doped with transition metal (Zr, Co, Fe) were prepared. The influencing factors (the catalyst type, the initial concentration, the gas flow, and oxygen content) on the degradation efficiency by the non-thermal plasma synergistic the LaMnO3 catalysts doped with Zr, Co and Fe were investigated systematically. The degradation mechanism of the meta-xylene degradation by the non-thermal plasma synergistic Mn-Zr-La/Al2O3 was researched. The results showed that the Mn-Zr-La/Al2O3 catalyst in the four catalysts had the best degradation efficiency for meta-xylene, which was 99.6% at the applied voltage of 44 kV. The by-product ozone concentration was low, and the NOx was not detected. Meanwhile, the XPS characterization analysis study revealed that the proportion of Mn4+ element and the proportion of Osur in the Zr-doped Mn-Zr-La/Al2O3 catalyst were both the highest. The degradation efficiency decreased with the increasing of the initial concentration and gas flow, but first increased and then decreased with the increasing of oxygen content. The fresh and used Mn-Zr-La/Al2O3 were characterized by SEM, XRD, BET, FT-IR, O2-TPD, and the tail gas was treated by GC-MS. Then synergistic degradation mechanism for the meta-xylene by the non-thermal plasma over the Mn-Zr-La/Al2O3 catalyst are proposed.