Pt/Al2O3 catalysts showing excellent activity and stability have been used in various reactions, including HCHO oxidation. Herein, we prepared Pt-Na/Al2O3 catalysts with a Pt content of 0.05 wt % to reveal the key factors determining the anchoring of Pt as well as the catalytic activity and mechanism of HCHO oxidation. Pt-Na/nano-Al2O3 (denoted as Pt-Na/nAl2O3) catalysts with 0.05 wt % Pt content could completely oxidize HCHO to CO2 at room temperature, which is the lowest Pt content used in HCHO catalytic oxidation to our knowledge. After Na addition, terminal hydroxyl groups (denoted as HO-μter) on nano-Al2O3 were transformed to doubly bridging hydroxyl groups between Na and Al (denoted as HO-μbri(Na-Al)), which atomically dispersed Pt species. Pt anchoring further promoted the regeneration of HO-μbri(Na-Al) by activating O2 and H2O, oxidizing HCHO to CO2 directly by the fast reaction step ([HCOO-] + [OH]a → CO2 + H2O). Our study revealed that the HO-μbri(Na-Al) synergistically generated by HO-μter and Na species provided anchoring sites for Pt species.
Keywords: HCHO oxidation; Pt anchoring; Pt/Al2O3; alkali metal; surface hydroxyl groups.