Copper-containing mixed metal oxides are one of the most promising catalysts of selective catalytic oxidation of ammonia. These materials are characterized by high catalytic efficiency; however, process selectivity to dinitrogen is still an open challenge. The set of Cu-Zn-Al-O and Ce/Cu-Zn-Al-O mixed metal oxides were tested as catalysts of selective catalytic oxidation of ammonia. At the low-temperature range, from 250 °C up to 350 °C, materials show high catalytic activity and relatively high selectivity to dinitrogen. Samples with the highest Cu loading 12 and 15 mol.% of total cation content were found to be the most active materials. Additional sample modification by wet impregnation of cerium (8 wt.%) improves catalytic efficiency, especially N₂ selectivity. The comparison of catalytic tests with results of physicochemical characterization allows connecting the catalysts efficiency with the form and distribution of CuO on the samples’ surface. The bulk-like well-developed phases were associated with sample activity, while the dispersed CuO phases with dinitrogen selectivity. Material characterization included phase composition analysis (X-ray powder diffraction, UV-Vis diffuse reflectance spectroscopy), determination of textural properties (low-temperature N₂ sorption, scanning electron microscopy) and sample reducibility analysis (H₂ temperature-programmed reduction).

Perovskite materials in the CaTiO₃-SrTiO₃ system doped with different amounts of iron (1, 2 and 5 mol.%) and various Ca/Sr ratios were prepared by the modified citrate method. Additionally, the materials with 0.05 deficiency in strontium/calcium sublattice and 5 mol.% of Fe were also synthesised. The materials were subjected to structural (XRD, XANES) and microstructural (SEM) characterisation, as well as the analysis of susceptibility to reduction/oxidation processes. The structural analysis indicates a lack of iron-containing phases; thus, an incorporation of Fe into the perovskite structure was postulated. Additionally, the oxidation state of iron in the perovskite structure changes with the dopant amount. The temperature-programmed reduction measurements showed partial reversibility of the reduction processes. For the materials with the highest iron amount, the catalytic tests in NH₃-SCO and NH₃-SCR reactions were carried out. The materials showed high catalytic activity and high selectivity to N₂ in the NH₃-SCR process; however, they were inactive in NH₃-SCO.