Reaction behaviors of CH3CN catalytic combustion over CuCeO -HZSM-5 composite catalysts: The mechanism of enhanced N2 selectivity

In this paper, the reaction behaviors of CH3CN catalytic combustion over CuCeOx-HZSM-5 catalysts prepared by the physical mixing and wet impregnation methods were investigated. The experimental results had revealed that the composite catalysts exhibited excellent degradation efficiency and high N2 selectivity: the Cu-Ce oxides ensured the high activity, and the introduction of HZSM-5 limited the formation of NOx. The involved reaction mechanism was then studied by an in situ DRIFT analysis. It could be deduced that different reaction pathways would occur over CuCeOx and HZSM-5. The catalytic reaction over CuCeOx mainly proceeded via an oxidation pathway. The CN group could be converted to isocyanate species [NCO(a)] which would be further oxidized to NOx. Over HZSM-5, CH3CN was mainly hydrolyzed into ammonia. For the CuCeOx-HZSM-5 composite catalysts, the over-oxidation of NCO(a) and NH3 was inhibited, and an internal selective catalytic reduction (SCR) reaction could occur, thereby greatly improving the N2 selectivity.