N2O decomposition over ZrO2 - An in-situ DRIFT, TPR, TPD and XPS study

Abstract

The adsorption and decomposition of N2O over ZrO2 are studied using in-situ DRIFT, TPD, TPR and XPS. N2O is found to be reversibly and molecularly adsorbed on the surface. The dissociation of N2O into adsorbed dinitrogen and oxygen can take place on Ar-pre-purged ZrO2. The adsorbed dinitrogen, which produces an IR band at 2360 cm-1 as detected by in-situ DRIFT, can be easily removed from the surface by Ar-purge or heating to high temperatures. The adsorbed oxygen, which is identified by the IR band at 810 cm-1, is strongly bonded to surface Zr ions and remain at the surface at high temperatures. TPR shows that the decomposition of N2O into N2 and O2 over ZrO2 becomes significant only at temperatures higher than 750 K, especially after the evolution of dioxygen (the desorption of adsorbed oxygen). The mechanism of decomposition is discussed.