Catalytic decomposition of N 2 O over Cu-Al-O x mixed metal oxides

Abstract

Cu-Al-O x mixed metal oxides with intended molar ratios of Cu/Al = 85/15, 78/22, 75/25, 60/30, were prepared by thermal decomposition of precursors at 600 °C and tested for the decomposition of nitrous oxide (deN 2 O). Techniques such as XRD, ICP-MS, N 2 physisorption, O 2 -TPD, H 2 -TPR, in situ FT-IR and XAFS were used to characterize the obtained materials. Physico-chemical characterization revealed the formation of mixed metal oxides characterized by different specific surface area and thus, different surface oxygen default sites. The O 2 -TPD results gained for Cu-Al-O x mixed metal oxides conform closely to the catalytic reaction data. In situ FT-IR studies allowed detecting the form of Cu + ...N 2 complexes due to the adsorption of nitrogen, i.e. the product in the reaction between N 2 O and copper lattice oxygen. On the other hand, mostly nitrate species and NO were detected but those species were attributed to the residue from catalyst synthesis.