Selective catalytic reduction of NOx by hydrogen over PtIr/TiO2 catalyst

PtIr/TiO2 catalyst was prepared and investigated for the selective catalytic reduction of NOx by H2 (H2-SCR) in the presence of O2. It was found that PtIr/TiO2 exhibited higher H2-SCR activity as well as wider activity temperature window than Pt/TiO2 and Ir/TiO2 catalysts, and the optimum mass ratio of Pt/Ir was 1:1. Characterization of the catalyst showed that metallic Pt and Ir were generated on PtIr/TiO2, both of which were favorable active sites in H2-SCR process. In situ DRIFTS studies showed that more NOx species, NH3 and NH4+ species were formed on PtIr/TiO2. All of these lead to the superior catalytic activity of PtIr/TiO2 catalyst.