The removal of pollutants emitted from diesel vehicle has attracted more and more attention and the control of NO_x at the low-temperatures, such as under “cold-start” conditions, is a challenging task in the environmental catalysis. Previous research demonstrated that supported Pt catalyst is active for the selective catalytic reduction (H₂-SCR) of NO_x. In terms of cost, the catalyst with low Pt loading is preferred. For Pt catalyst with low Pt content, its deNO_x activity at low temperatures (<200 ℃) needs to be improved.

A team focused on the air pollution control and environmental catalysis at Beijing University of Chemical Technology has developed an active Pt-WO₃/TiO₂ catalyst for the H₂-SCR of NO_x. The structure of this catalyst has been characterized by X-ray Absorption Fine Structure (XAFS) analysis conducted at Beijing Synchrotron radiation facility (BSRF), Institute of High Energy Physics, Chinese Academy of Sciences. XAFS analysis revealed that the Pt species in Pt/TiO₂ was present in Pt⁴⁺ oxidation state. After doping WO₃ there is synergetic effect between Pt and WO₃. Electron will be transferred to Pt from WO₃, thus leading to part of Pt species over Pt-WO₃/TiO₂ was present in the form of metallic Pt. The metallic Pt is the active sites for the H₂-SCR of NO_x at low temperatures. As a result, Pt-WO₃/TiO₂ catalyst showed high low-temperature activity for the reduction of NO_x.

Their research has been published in Applied Catalysis B in 2016. This research elucidated the relationship between the chemical state of the active sites and the catalytic performance of the deNO_x catalyst. It provides valuable insights into the catalyst design for the control of NO_x.

Article: Zhiming Liu *, Yunan Lu, Lei Yuan, Lingling Ma*, Lirong Zheng, Jing Zhang, Tiandou Hu. Selective catalytic reduction of NO_x with H₂ over WO₃ promoted Pt/TiO₂ catalyst，Applied Catalysis B: Environmental 188 (2016) 189–197.