Synergistic Effect of Non-thermal Plasma on NOx Reduction by CH4 over an In/H-BEA Catalyst at Low Temperatures

Abstract

The effects of non-thermal plasma on selective catalytic reduction of NOx by CH4 (CH4-SCR) over an In/H-BEA catalyst were investigated over a wide range of reaction temperatures (523–823 K). The significant promotion effect between non-thermal plasma and CH4-SCR was exhibited at low temperatures from 523 to 698 K, while this synergetic effect gradually reduced with the increase of the reaction temperature. The NOx removal efficiency of the non-thermal plasma-facilitated CH4-SCR (PF-CH4-SCR) hybrid system increased at low temperatures because of the promotion of NO oxidation and CO yield by non-thermal plasma. Optimization of CH4 injections was an alternative solution for improving activity of In/H-BEA for the PF-CH4-SCR hybrid system. When 400 and 200 ppm of CH4 were injected into plasma and the SCR reactor, respectively, the PF-CH4-SCR hybrid system showed a wide operation window temperature. Catalyst characterizations showed that addition of non-thermal plasma could promote SO2 and H2O tolerance of In/H...