CO2电催化还原制高附加值化学品

Electrocatalytic reduction of CO2 is a promising route to produce value-added chemicals under mild conditions. This new process can promote the development of power generation from clean and renewable energies, the cyclic utilization of carbon resource and the reduction of CO2 emission. To avoid the low efficient reduction in aqueous solutions and low value-added chemicals production at high temperatures (>600°C), in this proposal we suggest to build a new electrocatalytic reduction system at 300-450°C. Solid electrolyte membranes made of oxygen ionic (or protonic) conducting oxides will be used to construct continuous-flow electrocatalytic membrane reactors for CO2 reduction to value-added chemicals. In the electrocatalytic membrane reactors, CO2 and steam are the reactants. As a potential is applied on the electrocatalytic membrane reactors, the oxygen (or hydrogen) is driven to anode (or cathode) side, then the resultant active hydrogen species react with the active carbon species to produce value-added chemicals. In this proposal, we suggest that the first problem should be solved is preparing ultrathin electrolyte membranes, and then creating high efficient electrocatalysts for CO2 reduction, building electrocatalytic membrane reactors for the practical applications, investigating the electrocatalytic mechanism by using in-situ characterizations, understanding the surface-interface functions in the electrocatalysis process, analyzing the coupling effects between the electrocatalytic reactions and membrane separation. We wish a new way for high efficient converting CO2 to value-added chemicals can be built basing on the researches of this project.

以可再生能源或核能为电能，在温和条件下将CO2转化为高附加值化学品，是清洁发电技术发展、碳资源循环利用和CO2减排的有效途径之一。为克服传统液相还原效率低和高温（>600°C）气相还原产物附加值低的缺点，本项目旨在发展CO2电催还原反应新体系：建立工作温度在300-450°C的氧离子（或质子）导电氧化物为电解质膜的连续流动式CO2电催化还原膜反应器。以CO2和H2O(气态)为反应物，在外加电压下将氧（或氢）经电解质膜从阴极侧移出（或移入），实现CO2的电催化还原和高附加值化学品合成。本项研究将首先通过方法创新解决困扰300-450°C之间电催化还原CO2超薄电解质膜制备的关键科学问题，然后创制新型高效CO2还原电催化剂，构建面向应用的电催化膜反应器，结合原位动态表征研究电催化反应机理，深入认识电催化反应中的表界面效应，分析电催化反应-膜分离耦合作用，为高效CO2还原制化学品提供新途径。

项目以研究高性能的高温电催化还原CO2催化剂和高效转化CO2为高附加值化学品为主线，通过优化制备方法获得了满足电催化膜反应器还原CO2的电解质膜，筛选、制备与评价了多个CO2电催化还原催化剂体系，包括(La0.75Sr0.25)0.95 Cr0.5Mn0.5O3-δ钙钛矿阴极，LaFeO3-δ基钙钛矿阴极，Sr2.0Fe1.5Mo0.5O6-δ双钙钛矿体系，以及无碱土元素掺杂的钙钛矿体系等，发现可以通过阴极材料的晶体结构、粒径、形貌、界面、表面价态等来改善催化性能。利用多种光谱、阻抗谱、电镜等表征手段，明确了电催化剂结构与活性之间的关系。构建了电催化膜反应器，将CO2电还原和C2H6脱氢制烯烃耦合，阳极生成的氧消耗掉C2H6脱氢反应生成的氢气，拉动反应正向进行，进而使600 oC下C2H6制C2H4反应所需要的总能量减少了172.0%。通过本项目的研究，基本达到了既定目标，已发表研究论文58篇，主要研究工作发表在Energy & Environ. Sci.，Adv. Mater.，Angew. Chem. Int. Ed.，Nano Energy，ACS Catal.，J. Mater. Chem. A，Chem. Sci.，AIChE J.，J. Membr. Sci.，J. Energy Chem.等著名学术期刊上。