Effect of Hydroxyl Groups on Metal Anchoring and Formaldehyde Oxidation Performance of Pt/Al₂O₃
2022
Zhang, Zhilin | He, Guangzhi | Li, Yaobin | Zhang, Changbin | Ma, Jinzhu | He, Hong
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.
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