Catalytic decomposition of NO over Cu-Al-O mixed metal oxides.

Cu-Al-O 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 (deNO). Techniques such as XRD, ICP-MS, N physisorption, O-TPD, H-TPR, 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-TPD results gained for Cu-Al-O mixed metal oxides conform closely to the catalytic reaction data. FT-IR studies allowed detecting the form of Cu⋯N complexes due to the adsorption of nitrogen, the product in the reaction between NO 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.