Tuning the selectivity of NH oxidation via cooperative electronic interactions between platinum and copper sites.

Selective catalytic oxidation (SCO) of NH to N is one of the most effective methods used to eliminate NH emissions. However, achieving high conversion over a wide operating temperature range while avoiding over-oxidation to NO remains a significant challenge. Here, we report a bi-metallic surficial catalyst (PtCuO/AlO) with improved Pt atom efficiency that overcomes the limitations of current catalysts. It achieves full NH conversion at 250 °C with a weight hourly space velocity of 600 ml NH·h·g, which is 50 °C lower than commercial Pt/AlO, and maintains high N selectivity through a wide temperature window. Operando XAFS studies reveal that the surface Pt atoms in PtCuO/AlO enhance the redox properties of the Cu species, thus accelerating the Cu reduction rate and improving the rate of the NH-SCO reaction. Moreover, a synergistic effect between Pt and Cu sites in PtCuO/AlO contributes to the high selectivity by facilitating internal selective catalytic reduction.