Effects of cerium addition on the CO$z.sbnd;NO reaction kinetics over alumina-supported rhodium catalysts

Abstract

Laboratory reactor experiments have shown that the addition of cerium to a low-loaded Rh/Al₂O₃ catalyst gives rise to the following changes in the CONO reaction kinetics: suppression of N₂O formation, decreased apparent activation energy, and a shift to a positive-order dependence of the rate on NO partial pressure. These cerium-induced modifications of the kinetics lead to enhancement of the NO reduction activity at low temperatures. A simple kinetic analysis and temperature-programmed desorption experiments suggest that higher rates for both the NO dissociation and the low-temperature N₂ desorption steps in the presence of Ce may be responsible for the changes in the CONO reaction kinetics observed here.