Synthesis of efficient Pt/Al2O3 catalyst for the simultaneous removal of NH3 and CO: Revealing the rate-determining factor

In various industrial processes, particularly iron ore sintering operations, the concurrent use of fossil fuels and selective catalytic reduction by ammonia (NH 3 -SCR) denitrification technology inevitably results in the coexistence of carbon monoxide (CO) and escaped NH 3 in the exhaust gases. While simultaneous catalytic oxidation of CO and NH 3 represents an ideal strategy, it encounters significant challenges due to competition for active centers. Moreover, NH 3 -selective catalytic oxidation (NH 3 -SCO) is potentially inhibited by high CO concentrations. In this investigation, we synthesized a series of Pt/Al-X catalysts (X indicating calcination temperature) that demonstrated inverse activity patterns in independent NH 3 -SCO and CO oxidation reactions. Comprehensive analysis incorporating oxygen activation capacity, reactant adsorption characteristics, reaction kinetics, and in situ diffuse reflection infrared Fourier transform spectrum (DRIFTS) measurements indicated that O 2 activation capacity functioned as the rate-determining factor for NH 3 -SCO, whereas CO adsorption capacity and OH group density predominantly governed CO oxidation. Building on these findings, we engineered a composite catalyst by integrating Pt/Al-600 and Pt/Al-900 catalysts. This novel composite effectively reduced active center competition through strategic combination of functional sites, thereby achieving superior performance in simultaneous CO and NH 3 removal, while maintaining excellent water resistance and operational stability.