关键词: 直接合成过氧化氢, 限域催化, 密度泛函理论, 溶剂效应, Pd-Sn催化剂

Abstract:

The catalytic mechanism of the Pd-Sn bimetallic catalyst in the direct synthesis reaction of H₂O₂ under the confined solvent effect was systematically studied using the density functional theory (DFT) method. The regulatory mechanisms of the Pd-Sn doping ratio, the hydrogen bonding effect of the solvent molecule (methanol), and the synergistic effect at the catalyst-solvent interface on the reaction pathway and performance were revealed. The influence of the Sn doping ratio on the catalytic performance is remarkable. The appropriate introduction of Sn can effectively enhance the resistance to O poisoning through the electronic effect and geometric effect, and simultaneously reduce the energy barrier of the H₂O₂ synthesis pathway. In addition, the coupling effect of the methanol solvent exhibits a favorable promoting effect on the synthesis of H₂O₂ over the Pd-Sn catalyst. Methanol molecules interact with the reaction intermediate OOH through hydrogen bonding, significantly decreasing the energy barriers for the formation of OOH and H₂O₂. Over the Pd-Sn catalyst, methanol not only serves as a solvent but also actively participates in the catalytic cycle via hydrogen bonding-mediated proton transfer, thereby lowering the activation barriers for OOH and H₂O₂ formation. This work clarifies the microscopic interaction mechanism at the interface, reveals the crucial role of the solid-liquid interface interaction in improving the catalytic efficiency, and provides theoretical guidance for optimizing the production of H₂O₂ through the design of confined catalysts and solvent engineering.

Key words: Direct synthesis of hydrogen peroxide, Confinement effect in catalysis, Density functional theory, Solvent effect, Pd-Sn catalyst