Abstract:

CO₂ is main greenhouse gas. In recent years, with the vigorous development of industry, CO₂ emissions are rapidly increasing and seriously affecting our living environment.CO₂ conversion into valuable chemical products has attracted extensive attention in the field of research. The synthesis of dimethyl carbonate (DMC) from CO₂ and methanol can not only reduce CO₂ emissions but also produce valuable green products of DMC. In this paper, the factors effecting on CO₂ conversion are summarized as follows: thermodynamic constraints and difficulty in CO₂ activation. The common metal oxides of ZrO₂, CeO₂ and composite metal oxides with acid-base active centers are significantly introduced from the catalytic performance and reaction mechanism. The main reasons of affecting the catalytic activity are analyzed, which originated from Lewis acid-base sites and Br?nsted acid sites. The future research directions for developing efficient metal oxide catalysts are proposed: adjusting the crystal phase and morphology of catalysts, increasing oxygen vacancies and hydroxyl functional groups, doping alkaline or acidic species, and adding dehydrating agents to the catalytic system. At last, it is pointed out that the stability of CO₂ molecule is difficult to be activated, and the mechanism of activation of CO₂ molecule should be further studied to improve the conversion of CO₂.

Key words: carbon dioxide, catalysis, synthesis, metal oxides, reactivity

摘要：

CO₂是主要的温室气体。近年来随着工业的大力发展，CO₂的排放量迅猛增加，严重影响着人类的生存环境。将CO₂转化成有价值的化工产品，受到了研究领域的广泛关注。其中将CO₂与产能过剩的甲醇作为原料，生产碳酸二甲酯（DMC），既能减少CO₂排放，又能产生有价值的绿色产品DMC。本文简述了影响CO₂转化的因素，即受热力学限制和CO₂活化困难；重点介绍了具有酸碱活性中心的金属氧化物ZrO₂、CeO₂以及复合金属氧化物催化剂的催化性能和反应机理，并分析了影响催化活性的主要原因：表面酸碱性能决定了催化活性；进一步分析了催化剂表面的酸碱性来源于Lewis酸碱位和Br?nsted酸性位。对于开发高效的金属氧化物催化剂未来的研究方向提出了展望: 通过调控催化剂的晶相和形貌、增加氧空位和羟基官能团、掺杂碱性或者酸性物种来改变催化剂表面的酸碱性，并且向催化系统中添加脱水剂。最后指出了由于CO₂分子的稳定性很难被活化，需进一步深入研究其活化CO₂的机理，提高CO₂的转化率。

关键词: 二氧化碳, 催化, 合成, 金属氧化物, 活性