Comparison of NO conversion over Cu/M (M = TiO2, Al2O3, ZSM-5, carbon nanotubes, activated carbon) catalysts assisted by plasma.

NO conversion using dielectric barrier discharge (DBD) plasma with different catalysts was investigated. Cu/TiO₂, Cu/Al₂O₃, Cu/ZSM-5, Cu/CNTs and Cu/AC catalysts were prepared by incipient wetness impregnation with 4 wt% Cu loaded. BET, SEM, XRD, XPS, H₂-TPR, NH₃-TPD were used to measure and evaluate various catalysts. Compared with the plasma only process, the combination of plasma with different catalysts significant improved the NO conversion rate. The highest NO conversion rate of 76% could be achieved with Cu/ZSM-5 catalyst at the energy density of 184 J/L. The results indicate that Cu species over the support ZSM-5 can produce high concentrations of CuO, largest specific surface area, largest amounts of acidity and lowest reduction temperature (209 °C), these factors conducive to plasma-catalyst reaction. Besides, Cu/TiO₂ and Cu/Al₂O₃ catalysts exhibited excellent NO conversion at the low energy density because of the low thermal stability. After plasma-catalyst reaction, the reducibility of CuO and Cu₂O over supports decreased and the peak position of acid sites shifted to lower temperature. [ABSTRACT FROM AUTHOR]