Plasma-treated Ce/TiO2–SiO2 catalyst for the NH3-SCR of NOx
Ce/TiO2–SiO2 catalysts with different Ti/Si molar ratios are prepared by the incipient impregnation method and their NH3-SCR activities are evaluated at 100–500°C on a fixed reactor. The Ce/TiO2–SiO2 (3/1) catalyst, modified by non-thermal plasma (NTP) treatment and then activated by thermal treatment at 500°C for 4 h, exhibits best performance. Comprehensive deNOx performance of the catalyst is evidently improved and its efficiency reaches up to 99.21% at 350°C. NO conversion efficiency of the treated catalyst doped with K remains about 90.23% at 300°C and the catalyst also shows improved activity at lower temperatures. Various characterization methods show that the activity enhancement is correlated only with NTP treatment, as it increases the number of Ce3+ species, which generates more chemisorbed oxygen, leads to improved dispersion of Brønsted and Lewis acidic sites and finally has an inherent etching effect.