催化学报 ›› 2023, Vol. 53: 34-51.DOI: 10.1016/S1872-2067(23)64522-X

• 综述 • 上一篇    下一篇

烯烃的选择性电化学氧化: 研究进展与前景

汪晋a,1, 萧祖耀b,1, 徐梽川b,c,*(), 任肖a,*()   

  1. a北京大学化学与分子工程学院, 北京100871, 中国
    b新加坡南洋理工大学材料科学与工程学院, 新加坡
    c新加坡南洋理工大学先进催化科学与技术中心, 新加坡
  • 收稿日期:2023-07-13 接受日期:2023-09-20 出版日期:2023-10-18 发布日期:2023-10-25
  • 通讯作者: *电子信箱: renxiao_@pku.edu.cn (任肖), xuzc@ntu.edu.sg (徐梽川).
  • 作者简介:

    1共同第一作者.

  • 基金资助:
    国家自然科学基金(52202202);新加坡教育部一级资助(RG78/22)

Selective electrochemical oxidation of alkene: Recent progress and perspectives

Jin Wanga,1, Justin Zhu Yeow Seowb,1, Zhichuan J. Xub,c,*(), Xiao Rena,*()   

  1. aBeijing National Laboratory for Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
    bSchool of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
    cCentre for Advanced Catalysis Science and Technology, Nanyang Technological University, Singapore 639798, Singapore
  • Received:2023-07-13 Accepted:2023-09-20 Online:2023-10-18 Published:2023-10-25
  • Contact: *E-mail: renxiao_@pku.edu.cn (X. Ren), xuzc@ntu.edu.sg (Z. J. Xu).
  • About author:Zhichuan J. Xu is a professor at the School of Materials Science and Engieering, Nanyang Technological University, and a fellow of the Academy of Engineering, Singapore. He is a member of the International Society of Electrochemistry (ISE), the Electrochemistry Society (ECS), and a fellow of the Royal Society of Chemistry (FRSC). He serves as the president of ECS Singapore Section. His major research interest is electrocatalysis.
    Xiao Ren is an associate research fellow at Peking University. After receiving his Ph.D. (2017) from the Institute of Physics, Chinese Academy of Sciences, China, Xiao Ren received postdoctoral training at Nanyang Technological University, Singapore (2017-2022). Dr. Ren joined the College of Chemistry and Molecular Engieering of Peking University in 2022. The central paradigm of his research is to develop magnetic materials for electrocatalytic reactions and to study electrochemical reaction processes involving electron spins. The main focus is on the changes in the reaction pathways and the kinetics of chemical reactions in which electron spin is involved.

    1 Contributed equally to this work.

  • Supported by:
    The National Natural Science Foundation of China(52202202);The Singapore MOE Tier 1 grant(RG78/22)

摘要:

烯烃类化合物, 如乙烯和丙烯, 是工业生产的关键原料, 它们可以通过选择性氧化转化为环氧乙烷(EO)和环氧丙烷(PO)等高附加值的化学品. 目前, 烯烃类化合物转化主要通过热化学途径实现, 通常需要高温高压条件, 并可能导致过度氧化生成CO2, 因而选择性较低, 且对经济和环境效益不友好. 与此相对, 电催化反应以电能作为驱动力, 通过优化催化剂、电解液和反应电位等, 有望在相对温和的条件下提高反应的选择性和能量效率, 为高选择性烯烃氧化提供一种潜在策略. 然而, 当前烯烃的电化学选择性氧化的电流密度较低, 整体生产成本相对较高, 因此, 有必要进一步研发高效且稳定的电化学选择性氧化烯烃的体系.

本文综述了近期关于烯烃选择性电化学氧化的研究进展, 研究主要集中在两个方面: 一是烯烃在电极和电解液界面上直接进行电化学氧化的方法; 二是通过电化学反应原位生成氧化剂(如Cl2和H2O2)后, 再对烯烃进行氧化的间接方法. 对于烯烃的直接电化学氧化, 反应的选择性可以通过调控几何效应和电子效应来优化. 具体来说, 通过引入如氯离子这样的物种, 减少催化剂表面的可用活性位点数量, 从而降低烯烃在催化剂表面的双位吸附, 进一步降低过度氧化的可能性. 此外, 通过调整电催化剂的电子结构, 改变其表面氧物种的电子性质, 直接影响烯烃的加氧步骤, 从而实现对反应选择性的精准调控. 烯烃的氧化过程受限于其固有的缓慢反应动力学, 导致直接电氧化所能实现的电流密度有限. 为了提高该过程的速率, 可以引入氧化还原介导物种来实现烯烃的选择性氧化. 近期研究结果表明, 卤素和过氧化氢作为介导物种在烯烃的选择性氧化反应中表现较好. 利用先进的串联反应器技术, 过氧化氢介导乙烯氧化为乙二醇的电流密度已经可以达到500 mA cm-2.

深入探索了烯烃电化学氧化的前沿研究方向. 在烯烃的直接电氧化过程中, 电催化剂的选择和性质对整体反应性能具有决定性影响. 现有催化剂的化学成分、晶体学结构及合成方法上仍有较大的优化空间. 尤为重要的是, 关于烯烃电氧化的中间产物和反应途径, 仍存在诸多争议. 通过结合原位或在线的表征技术与密度泛函理论计算相结合, 对反应机理进行深入探讨, 将为反应体系的进一步完善提供理论支持. 在间接氧化策略方面, 反应器的设计与优化是研究的核心, 旨在提升整体反应效率并确保经济效益. 最后, 进行技术经济分析为确定烯烃电氧化在特定条件下的经济效益提供有力依据.

关键词: 烯烃氧化, 电催化, 过度氧化, 电子结构, 间接氧化

Abstract:

Alkene oxidation is an important industrial process that produces considerable quantities of commodity chemicals, notably ethylene oxide and propylene oxide. However, typical thermal oxidation processes are characterized by harsh reaction conditions and limited selectivity. Thus, electrochemical alternatives with enhanced product selectivity emerge as promising solutions with the possibility of using renewable input energy sources. Herein, we discuss strategies to improve the selectivity of alkene electrooxidation, specifically focusing on the regulation of the geometric and electronic structures of electrocatalysts, as well as the application of mediated indirect oxidation. Furthermore, we also provide an overview of the current challenges and problems requiring further investigation in improving industrial feasibility of electrochemical alkene oxidation.

Key words: Alkene oxidation, Electrocatalysis, Overoxidation, Electronic structure, Indirect oxidation