What should people do with the huge amount of CO₂ captured? CO₂ to CO is a promising way for using carbon resources because CO is one component of syngas for the production of many important synthesis intermediates such as dimethyl oxalate (DMO). Hydrogenation of DMO provides an economical and eco-friendly approach for the synthesis of methyl glycolate, ethylene glycol (EG), and ethanol, which is often determined by the reaction conditions and catalysts with different active sites. Thus, DMO or EG is also an important carbon carrier or CO₂ utilization product. Also, DMO hydrogenation is a representative reaction for studying the structure–activity relationship in C═O/C–O bond hydrogenation. Therefore, this work provides a comprehensive review of the progress in DMO hydrogenation from the perspective of constructing and stabilizing the active sites. The silver and copper based catalysts with different structures and morphologies used for DMO hydrogenation have been discussed with regard to their catalytic performance and reaction mechanism. The synergy of Cu⁰ and Cu⁺ in DMO hydrogenation has been questioned, and new active sites are proposed with more experimental evidence. New reaction routes, hybrid active sites, and the effect of catalyst structure on the active sites for DMO hydrogenation have been achieved and reviewed. Moreover, a strategy of introducing organic additives to improve EG yield and stabilize copper species has been described. This work may help advance the understanding of active sites in DMO hydrogenation and guide the future rational design and fabrication of highly stable and low-cost DMO hydrogenation catalysts.

中文翻译：

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草酸二甲酯加氢活性位点及催化剂设计的展望

人们应该如何处理捕获到的大量CO ₂？将CO ₂转化为CO是一种使用碳资源的有前途的方法，因为CO是用于生产许多重要的合成中间体（例如草酸二甲酯）的合成气的一种组分。DMO的氢化为乙醇酸甲酯，乙二醇（EG）和乙醇的合成提供了一种经济，环保的方法，这通常取决于反应条件和具有不同活性位点的催化剂。因此，DMO或EG也是重要的碳载体或CO ₂利用产品。同样，DMO加氢是研究C═O/ C-O键加氢中结构与活性关系的代表反应。因此，这项工作从建设和稳定的活动站点的角度提供了对DMO加氢进展的全面回顾。讨论了用于DMO加氢的具有不同结构和形态的银和铜基催化剂的催化性能和反应机理。Cu ⁰和Cu ⁺的协同作用在DMO氢化中的应用受到质疑，并提出了具有更多实验证据的新活性位点。已经实现并审查了新的反应路线，杂化活性位点以及催化剂结构对DMO加氢活性位点的影响。此外，已经描述了引入有机添加剂以提高EG产率和稳定铜种类的策略。这项工作可能有助于增进对DMO加氢反应中活性位点的理解，并指导未来合理设计和制造高度稳定且低成本的DMO加氢催化剂。