Catalytic decomposition of N2O over Cu–Al–Ox 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 (deN₂O). Techniques such as XRD, ICP-MS, N₂ physisorption, O₂-TPD, H₂-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 O₂-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⁺⋯N₂ complexes due to the adsorption of nitrogen, i.e. the product in the reaction between N₂O 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.