【摘要】 采用回流法制备了不同Zn掺杂量的CeZn_xO₂催化剂，用于CO₂和甲醇直接合成碳酸二甲酯（DMC），同时结合多种表征技术探究了CeZnxO₂结构与表面性质对其催化性能的影响。结果表明，Zn²⁺进入CeO₂晶格中形成固溶体，Zn/Ce物质的量比对Ce³⁺/Ce⁴⁺氧化还原平衡具有显著的调控作用。随着Zn掺杂量的增加，催化剂表面氧空位含量呈现先增加后减少的趋势，适量Zn掺杂（Zn/Ce=0.5）有利于2Ce⁴⁺+Zn⁰=2Ce³⁺+Zn²⁺反应的发生，显著提高其Ce³⁺比例及氧空位浓度，而过量Zn掺杂（Zn/Ce≥0.75）,Ce³⁺比例下降，氧空位浓度显著降低。结合酸碱位点分析发现，催化剂活性与弱碱位点数量显著正相关，并且与表面氧空位含量呈线性正相关，其中CeZn⁰.5O₂因兼具高氧空位浓度和适宜碱性位点分布而对DMC合成表现出最佳的催化性能。更多还原

【Abstract】 A series of CeZn_xO₂ catalysts with different Zn doping contents were prepared by a reflux method and used in the direct synthesis of dimethyl carbonate（DMC） from CO₂ and methanol; various characterization techniques were employed to investigate the influence of the structure and surface properties on the catalytic performance of CeZnxO₂ in the DMC synthesis. The results demonstrate that Zn²⁺ is incorporated into the CeO₂ lattice, forming a solid solution. The Zn/Ce molar ratio can significantly modulate the Ce³⁺/Ce⁴⁺ redox equilibrium in CeZn_xO₂; with an increase of the Zn doping content, the oxygen vacancy concentration initially rises and then declines. A moderate Zn doping level（Zn/Ce = 0.5） can promote the redox process of 2Ce⁴⁺ + Zn⁰ = 2Ce³⁺ + Zn²⁺, resulting in the highest Ce³⁺ proportion and a substantial increase of the oxygen vacancy concentration. In contrast, excessive Zn doping（Zn/Ce ≥ 0.75） leads to a reduction in both the Ce³⁺ content and oxygen vacancy concentration. There is a strong positive correlation between the catalytic activity and the number of weak base sites, as well as a linear relationship with the surface oxygen vacancy concentration. In particular, CeZn_0.5O₂ with a Zn/Ce molar ratio of 0.5 exhibits the best catalytic performance in the DMC synthesis, owing to its high oxygen vacancy concentration and well-balanced distribution of basic sites.更多还原