NO Inhibition Effects During Oxidation of Propylene on Cu-Chabazite Catalyst: A Kinetic and Mechanistic Study

Abstract

Bench-flow reactor and in situ DRIFTS experiments were carried out to elucidate the features of the propylene + NO + O2 reaction system on Cu–SSZ13 (chabazite) monolithic catalyst. Experiments were conducted under both steady state and transient conditions for application-relevant feed conditions. Steady state conversion data of the C3H6 light-off in the presence of excess O2 (5%) shows inhibition by a much smaller amount of NO (500 ppm). Corresponding data in the presence of NO2 reveals a transition in the C3H6 light-off curve; for temperatures below 350 °C, the C3H6 conversion is higher in the presence of NO2 as compared to O2 whereas above 350 °C the C3H6 conversion in the absence of NO2 is higher. The reduction of NO2 to NO and N2 is enhanced by the addition of C3H6, which facilitates the reduction of Cu sites favorable for the NO2 reduction. Spatially resolved concentration profiles using a series of monolith pieces of different lengths provide insight into the reaction pathways. The spatial profiles...