Highly Selective and Low-Copper-Content-Doped SrTiO3 Catalysts for NH3-SCR and NH3-SCO Processes

The catalytic performance of copper-modified strontium titanate-based materials (SrTi1−xCuxO3, where x = 0.02, 0.04, 0.06, and 0.10) in the NH3-SCR and NH3-SCO processes was studied. The catalytic materials were obtained by the modified Pechini method and characterized in terms of structural properties (XRD, XAS), surface composition (XPS), microstructural properties (SEM/EDS, SSA measurements), and reducibility (TPR). Catalytic activity, selectivity to N2, and long-term stability in the NH3-SCR and NH3-SCO processes were experimentally verified. The catalytic materials consisted of agglomerates of nanocrystalline perovskite grains with homogeneously distributed copper, except for the material with the highest copper content. The catalytic activity of these materials was found to be highly dependent on copper loading, with STO_4Cu emerging as the optimal catalyst—the NO conversion in NH3-SCR on the level of 88% and exceptional N2 selectivity (>98%) was obtained at 275 °C, despite an extremely low Cu content (below 2 wt.%). Lower copper content (STO_2Cu) in catalysts appears to limit the low-temperature activity, which correlates with a higher Cu(I) contribution. On the other hand, the higher copper loading (STO_10Cu) triggers their aggregation. Twelve-hour isothermal stability tests confirmed robust long-term performance and stable N2 selectivity for both the NH3-SCR (at 250 °C) and NH3-SCO (at 375 °C) reactions, demonstrating the potential of finely dispersed, low-loading copper perovskites for environmental catalysis.