Effect of support (Degussa P25 TiO₂, anatase TiO₂, Γ-Al₂O₃, and AlOOH) of Pt-based catalysts on the formaldehyde oxidation at room temperature

Different catalyst supports, namely: commercial Degussa P25 TiO₂, anatase TiO₂ (CC), γ-Al₂O₃, and lab-synthesized AlOOH were used to prepare Pt-based catalysts for the room temperature formaldehyde oxidation. XRD, BET and XPS were conducted to characterize the bulk structure of support, the oxidation state of surface elements and the ratio of oxygen in hydroxyls to the total surface oxygen, as well as textural properties of catalysts. For the first time, a long-term activity test at 0% relative humidity was conducted to investigate relationships between the activity of the Pt-based catalysts with Pt dispersion and oxidation state and the relative abundance of surface OH groups. Pt/AlOOH showed the best activity, whereas Pt/P25 TiO₂ gave the worst activity. We consider that both the surface hydroxyl groups and the Pt dispersion are indispensable, and both act synergistically. The specific surface area is not the decisive factor for the present reaction.