Selective catalytic reduction of NOx with H2 over WO3 promoted Pt/TiO2 catalyst

Pt/TiO2 and WO3 modified Pt/TiO2 catalysts have been investigated for the selective catalytic reduction of NOx by H2 (H2-SCR) in the presence of oxygen. It was found that the addition of WO3 leads to a significant promoting effect on the low-temperature activity of Pt/TiO2 catalyst and the optimal loading is 2%. X-ray absorption near-edge structure (XANES) revealed the electron transfer from WO3 to Pt active sites, leading to the formation of metallic Pt, which is responsible for the low-temperature H2-SCR of NOx. In-situ DRIFTS demonstrated that the introduction of WO3 to Pt catalyst not only contributes to the formation of reactive adsorbed NOx species on the catalyst, but also promotes the formation of NH4+ species. All of these factors, collectively, account for the improved low-temperature activity of Pt-WO3/TiO2 catalyst.