“相同位置-电子显微学方法”用于液相催化加氢反应构效关系研究

The evolution of microstructure, composition, and valence state of a catalyst during liquid-phase reaction is crucial for understanding the reaction mechanism and designing & synthesizing high efficient catalysts. With the development of electron microscopy and spectroscopy, the microstructure feature of catalysts before and after liquid-phase reaction can be revealed. However, these characterization methods are not able to trace the microstructure of a catalyst at identical location at different time during reaction. Therefore, the catalyst microstructure during liquid-phase reaction cannot be accurately uncovered and correlated the corresponding performance in real conditions. Regarding this key issue, this project will focus on accurately studying the catalyst structure during liquid-phase reaction. The characterization platform of “Identical Location Transmission Electron Microscopy” (IL-TEM) will be set up and developed. The oxide supported metal nanoparticles (NPs) and carbon supported metal NPs are as model catalysts, and the selective hydrogenation reactions of aromatic nitro compounds and α,β unsaturated aldehydes and ketones are as probing reactions. The structure features of a catalyst at identical location (e.g., NP aggregation, coalescing and fall-off, the interface variation between NP and support) will be observed and related the performance. This method will be expanded and used in other types reactions (e.g., oxidation reaction and coupling reaction), which will help to identify active sites and establish catalysis mechanism. The results will provide a new example for detecting the structure features of catalysts during liquid-phase reactions and the scientific evidences for designing new-type catalysts with high performance.

液相反应中催化剂的结构特征对理解反应机制、调控合成高性能催化剂具有重要作用。随着电子显微学和谱学表征技术的发展，已经可以揭示液相反应前后催化剂结构特征并关联其性能，但这些表征手段还不能跟踪“同一位置催化剂在反应各个阶段的结构特征”，无法实现“真实催化反应条件下对液相反应过程中催化剂结构进行精准表征并关联性能”。针对这一关键问题，本项目将开展液相催化加氢反应过程中催化剂结构精准表征研究：拟建立和发展“相同位置-电子显微学方法”，以氧化物和纳米碳分别负载金属纳米粒子催化剂为研究对象，芳香硝基化合物和α,β不饱和醛酮的选择性加氢为探针反应，探索催化剂相同位置在反应过程中负载金属粒子凝聚、接合、脱落及与载体表界面结构变化等，关联其对应的性能；并拓展此方法适用的反应类型，如氧化反应、偶联反应等，揭示液相催化中活性位及其演变规律，阐明反应机理。该项目成果将为探索液相反应过程中催化剂精细结构提供新方法。

液相反应中催化剂的结构特征对理解反应机制、调控合成高性能催化剂具有重要作用。随着电子显微学和谱学表征技术的发展，已经可以揭示液相反应前后催化剂结构特征并关联其性能，但这些表征手段还不能跟踪“同一位置催化剂在反应各个阶段的结构特征”，无法实现“真实催化反应条件下对液相反应过程中催化剂结构进行精准表征并关联性能”。针对这一关键问题，本项目开展了液相催化加氢反应过程中催化剂结构精准表征研究：建立并发展了“相同位置-电子显微学方法”，以氧化物和纳米碳分别负载金属纳米粒子催化剂为研究对象，芳香硝基化合物和α,β不饱和醛酮的选择性加氢等为探针反应，探索了催化剂相同位置在反应过程中负载金属粒子凝聚、接合、脱落及与载体表界面结构变化等，关联其对应的性能；并拓展此方法适用的反应类型，如偶联反应等，揭示液相催化中活性位及其演变规律，阐明了反应机理。该项目成果为探索液相反应过程中催化剂精细结构提供了新方法。目前，相关研究成果已经整理总结，发表在国际学术期刊上10余篇，参加学术会议10余次。该项研究为化学环境中准原位探索负载型催化剂结构特征提供新方法，为开发制备新型高效催化剂提供实验依据。