Preparation, characterisation and catalytic performance for soot oxidation of copper-containing ZnAl2O4 spinels Original Research Article

Copper-containing ZnAl2O4 catalysts have been properly prepared by the glycothermal method, with copper loaded within the mixed oxide structure (catalyst Zn0.95Cu0.05Al2O4) or impregnated in the previously prepared support ZnAl2O4 (catalyst 5%Cu/ZnAl2O4). The samples were characterised by XRD, HRTEM, SEM-EDAX, N2 adsorption at −196 °C, FT-IR, and H2-TPR, and the catalytic combustion of soot under NOx/O2 was tested. The mixed oxides, with confirmed spinel structure, consist of nanoparticles with around 5–12 nm. The impregnated catalyst is more active for soot combustion than both the bare support and the substituted catalyst, which is attributed to the proper reducibility of copper that catalyses the NO oxidation to NO2. This catalyst is also highly selective towards CO2 formation as soot combustion product.