Boosting the activity of In-H-SSZ-13 via tuning acid sites for synergistic abatement of NOx and CH4

Abstract

Selective catalytic reduction of NO by CH4 (CH4-SCR) is a desirable denitration technology for liquefied natural gas (LNG)-powered vehicles and ships, and efficient catalysts have been explored. However, enhancement of the catalytic performance via tuning acid sites of the zeolites is rarely reported. In this work, In-H-SSZ-13 catalysts were prepared via ion exchange method, and the acid sites in the catalysts were adjusted through pre-treatment process of (NH4)2SO4. The activity of the catalyst boosted with improvement of the acid sites in the catalysts, and the activation energy of the reaction decreased from 82.1 to 63.9 kJ/mol over the catalysts. In situ DRIFTS analysis confirmed that more acid sites could facilitate the adsorption and activation of CH4, and R-NCO was a vital intermediate product in the CH4-SCR reaction. The effects of In loading and reaction conditions on the performance of the catalysts were also investigated, and the NO and CH4 conversions reached 75 % and 99 % at 505 °C with a high gas hourly space velocity (GHSV) of 80,000 h−1 over the optimized In-H-SSZ-13 catalyst, respectively.