Radio-frequency (RF) plasma synthesis of H-ZSM-5 supported MnOx catalysts with high catalytic activity for deNOx-SCR by propylene

Abstract

Traditionally, C3H6-SCR exhibited poor catalytic activity at low temperature (≤300 °C) due to the difficult activation of C3H6. For investigation of the low temperature catalytic behavior of C3H6-SCR, a series of MnOx/ZSM-5 catalysts prepared by coprecipitation method was activated by an efficient H2 RF plasma, and first used for C3H6-SCR. Under the simulated lean burn condition (5% O2) of actual diesel engines, more than 99% NO conversion was observed at 200°C–300 °C with the space velocity of 30000 h−1 on the MnOx/ZSM-5-H2RF-100W catalyst. Characterization results demonstrated that H2 RF plasma activation could facilitate the growth of stronger active Mn2O3 species, and generated more lattice oxygen (Oβ) with a high electron cloud density. Besides, the stable Brönsted acidity from uncoordinated framework Mn (Mn–O–Si), higher surface Mn concentration, good dispersion, and larger pore size caused by H2 RF plasma could be also contribute to excellent low temperature C3H6-SCR catalytic activity. We expect this study to shed more light on the nature of the surface active sites of MnOx/ZSM-5-H2RF-100W in low temperature C3H6-SCR, and the development of novel preparation method for the synthesis highly-active catalysts of low temperature C3H6-SCR.