Abstract:

Aimed at obtaining economically valuable fuels or chemicals, the chemical conversion of CO₂ provides a renewable utilization route for CO₂, which is one of the ideal solutions to China's current carbon emission issue. Owing to the chemical stability of CO₂ and complicated reaction pathways, however, the conversion and selectivity of reactions that convert CO₂ are relatively low. The reduction reaction and combination reaction are the two major routes to convert CO₂, which either involves the cleavage of C O bond or maintains the original valence state of carbon in CO₂. In terms of bond cleaving reduction, the hydrogenation of CO₂ has been demonstrated with industrially mature catalysts, but the single pass conversion and selectivity are still far from satisfactory, while the photoelectrochemical reduction of CO₂ is still in the stage of laboratory research. In case of combination reactions that utilize CO₂, it is possible to convert CO₂ into carbonates or polycarbonates, as well as mineralization products. Yet the conversion and economic feasibility of these processes still need further improvements. Under this background, the National Key Research and Development Program of China initiates the “Key fundamental aspects in highly efficient CO₂ conversion and utilization” Program. Future research endeavors will include the explanation of microscopic mechanism and energy transfer pathway during CO₂ hydrogenation and photoelectrochemical reduction, and establishing more controllable synthesis methods of catalysts, which may lead to new breakthroughs of CO₂ reduction. In addition, the interaction between CO₂ and ionic liquids, and the associated catalytic process, as well as the agent enhanced reaction-transfer coupling mechanism will be explored. The phase transformation mechanisms during CO₂ mineralization will also be investigated. These research endeavors will provide fundamental guidance for the mass conversion and utilization of CO₂.

Key words: carbon dioxide, photoelectrochemical reduction, hydrogenation, ionic liquid, mineralization

摘要：

CO₂的化学转化以获得具有经济价值的能源或化学品为目标，可实现CO₂的资源化循环利用，是解决中国碳排放问题的理想方式之一。但由于CO₂极其稳定且转化路径复杂，导致其转化率低且产物选择性不佳。开键还原和不变价化合是CO₂化学转化的两条基本路径。在开键还原方面，CO₂加氢还原已有工业示范装置报道，但单程转化率较低且选择性不足；而CO₂光电还原目前尚处于实验室研发阶段。在化合转化方面，可将CO₂转化合成为碳酸酯/聚碳酸酯，或通过矿化过程实现CO₂的转化与利用，但反应系统的转化效率以及转化过程的经济性仍有待提高。在此背景下，科技部2016年启动了“基于CO₂高效转化利用的关键基础科学问题”国家重点研发计划项目。在未来的研究工作中，将阐明CO₂光电还原和加氢还原的微观动力学机制与能量传递路径，建立更加可控的催化剂制备方法，实现CO₂还原新途径与新技术的突破；研究CO₂与离子液体相互作用机制、催化转化过程及介质强化反应-传递耦合规律；揭示非碱性矿活化CO₂过程的相变规律和矿化反应原理，为CO₂转化与利用的大范围推广奠定基础。

关键词: 二氧化碳, 光电还原, 加氢还原, 离子液体, 矿化