关键词: 甘油, 氧化, Pt基催化剂, 界面, 分子模拟

Abstract:

The interfacial sites between Pt and promoters are highly conducive to the selective oxidation of glycerol to 1,3-dihydroxyacetone (DHA). In this study, two Pt-based catalysts with different Pt-Bi interfacial structures, Pt/Bi₂O₃-CNTs and PtBi/CNTs, were prepared by using atomic layer deposition and impregnation-reduction method, respectively. The selective oxidation of glycerol on the two catalysts was investigated through a combination of experiments and density functional theory (DFT) calculations. Characterization results show that there is a relatively uniform Pt-Bi₂O₃ interface structure in the Pt/Bi₂O₃-CNTs catalyst, while the PtBi/CNTs catalyst forms a Pt₁Bi₁ intermetallic compound. Both catalysts promote the preferential oxidation of the secondary hydroxyl group in glycerol. Comparatively, the Pt/Bi₂O₃-CNTs catalyst demonstrates superior glycerol oxidation activity due to its smaller particle size and higher Pt⁰ 4f binding energy, whereas the PtBi/CNTs catalyst facilitates the deep oxidation of DHA. Furthermore, DFT calculations reveal that the rate-determining step for the oxidation of the secondary hydroxyl group of glycerol to DHA on both catalysts is C—H bond cleavage, with a relatively lower energy barrier observed on the Pt/Bi₂O₃-CNTs catalyst, resulting in higher reaction activity. On the surface of the PtBi/CNTs catalyst, DHA exhibits greater adsorption affinity, rendering it more susceptible to deep oxidation. The insights provided here could serve as a guide for the design and optimization of Pt-based catalysts for the selective oxidation of glycerol to DHA.

Key words: glycerol, oxidation, Pt-based catalyst, interface, molecular simulation