Combined fast selective reduction using Mn-based catalysts and nonthermal plasma for NOx removal.

In this study, the concept of fast SCR for NO reduction with NH3 as reducing agent is realized via the combination of nonthermal plasma (NTP) with Mn-based catalyst. Experimental results indicate that 10% wt. Mn-Ce-Ni/TiO2 possesses better physical and chemical properties of surface, resulting in higher NO removal efficiency if compared with 10% wt. Mn-Ce/TiO2 and 10% wt. Mn-Ce-Cu/TiO2. Mn-Ce-Ni/TiO2 of 10% wt. achieves 100% NOx conversion at 150 °C, while 10% wt. Mn-Ce/TiO2 and 10% wt. Mn-Ce-Cu/TiO2 need to be operated at a temperature above 200 °C for 100% NOx conversion. However, NO conversion achieved with 10% wt. Mn-Ce-Ni/TiO2 is significantly reduced as H2O(g) and SO2 are introduced into the SCR system simultaneously. Further, two-stage system (SCR with DBD) is compared with the catalyst-alone for NOx conversion and N2 selectivity. The results indicate that 100% NOx conversion can be achieved with two-stage system at 100 °C, while N2 selectivity reaches 80%. Importantly, NOx conversion achieved with two-stage system could maintain >95% in the presence of C2H4, CO, SO2, and H2O(g), indicating that two-stage system has better tolerance for complicated gas composition. Overall, this study demonstrates that combining NTP with Mn-based catalyst is effective in reducing NOx emission at a low temperature (≤200 °C) and has good potential for industrial application.