Energy & Fuels, Vol.29, No.8, 5282-5289, 2015
Synergistic Effect of Non-thermal Plasma on NOx Reduction by CH4
The effects of non-thermal plasma on selective catalytic reduction of NOx by CH4 (CH4-SCR) over an In/H-BRA 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 NO 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 PFCH4-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-BEA, because of the inhibition of SO2 oxidation, InO+ sulfating, and indium oxide agglomeration.