Niobium-enabled surface regulation over Cu/ZrO2 catalyst for highly selective ammonia oxidation

Marine NH 3 -fueled engines commonly suffer from ammonia slip, and the ammonia selective catalytic oxidation (NH 3 -SCO) process provides an effective approach to mitigate NH 3 emissions. Nonetheless, developing catalysts that simultaneously exhibit superior low-temperature activity and excellent N 2 selectivity remains a significant challenge. In this work, we report a two-step synthesis strategy to incorporate Nb into Cu/ZrO 2 catalysts, which markedly enhances both N 2 selectivity and NH 3 oxidation activity. The introduction of Nb increased the concentration of surface adsorbed oxygen species and the number of acidic sites, thereby promoting NH 3 activation and oxidation. In addition, the further oxidation of NO was effectively suppressed on Nb-containing catalysts, making it more likely to be reduced by NH 3 or -NH 2 species to form benign N 2 . Consequently, the Nb-modified catalysts demonstrated superior NH 3 conversion and N 2 selectivity. This study elucidates the promotional role of Nb in Cu/ZrO 2 catalysts and offers new insights for designing efficient and low-cost catalysts for the NH 3 -SCO process.