Role of Copper and Cerium on Core-Shell Al-MCM-41 in NO Reduction via a SCR-CH₄.

Copper species in the structure of Cu/core-shell Al-MCM-41 catalysts prepared by different techniques of Cu loading-substitution (S), ion-exchange (E), and impregnation (I) methods-were tested for NO reduction via a selective catalytic reaction with methane. Cerium was added to enhance the performance of copper. It was found that the 1.5%Ce-SEI-Cu/Al-MCM-41, in which Cu was loaded by all three techniques gave the highest NO conversion of 85% at 500 °C. Based on the results from FT-IR in-situ experiment, the mechanism of SCR-CH4 reaction is proposed. The ion-exchange method gives the best performance of SCR-CH4 reaction when compared with the other methods, because the Cu of reduced catalyst in this method exists in isolated Cu(I), which is an active site of the SCR-CH4 reaction. With H2O in the feed, the NO conversion of 1.5%-Ce-SEI-Cu/Al-MCM-41 catalyst is found to be rather stable.