Synthesis of TixSn1-xO2 mixed metal oxide for copper catalysts as high-efficiency NH3 selective catalytic oxidation

A series of y Cu/TixSn1-xO2 catalysts for selective catalytic oxidation (NH3-SCO) were synthesized using TixSn1-xO2 as catalyst support and CuO as active species. Compared with pure TiO2 support, the strong metal-support interaction between Cu active species and TixSn1-xO2 was significantly promoted by the Sn-doping, thereby improving the catalytic activity and N2 selectivity of the catalyst, which meets the demand of diesel vehicles to completely convert NH3. The results of XRD and HRTEM showed that the particle size of 20 Cu/TiSnO2 sample is much more highly dispersed. The results of NH3-TPD and in-situ DRIFTS indicated that the copper species in 20 Cu/TixSn1-xO2 can provide more Lewis acid sites than 20 Cu/TiO2, which is conducive to the adsorption and reaction of NH3. Meanwhile, XPS results proved that adsorbed oxygen on the catalyst surface is the main active oxygen species. Finally, in-situ DRIFTs and kinetic measurements found that the NH3-SCO reaction over 20 Cu/TiSnO2 and 20 Cu/TiO2 follow the i-SCR and imide (–NH) mechanisms, respectively. This catalyst will provide solutions for the future design and application of ammonia slip from mobile and stationary sources.