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    尖晶石催化二氧化碳加氢制甲醇研究进展

    Research progress on spinel-catalyzed CO2 hydrogenation to methanol

    • 摘要: 以CO2和绿氢为原料合成绿色甲醇是实现碳资源循环与能源结构转型的重要路径,而高效催化剂仍是制约其工业化的瓶颈。尖晶石(AB2O4)因阳离子可交换、结构稳固与表面酸碱协同,是催化CO2加氢制甲醇的理想材料。系统整理了尖晶石催化剂的构效关系与改性策略的研究进展:首先,深入分析了尖晶石催化CO2加氢制甲醇的反应机理,指出CO2活化机制主要依赖于尖晶石表面氧空位(Ov)介导的电子转移与晶格内固有的Lewis酸碱对(Mn+−O2−)协同作用。同时,H2在尖晶石催化剂上的活化多通过异裂解离途径进行,Ov浓度、金属中心的电子结构以及Mn+−O2−对的协同效应显著影响H2活化能垒。CO2加氢制甲醇的反应路径主要存在2条竞争性路径:甲酸盐路径与逆水煤气变换耦合CO加氢路径(RWGS+CO加氢)。其次,总结了尖晶石催化剂的改性策略,包括氧空位精准调控、配位–电子结构协同优化、活性金属–尖晶石界面协同强化以及尖晶石–分子筛串联催化剂构建。氧空位调控、配位–电子结构改性等通过元素掺杂、还原预处理、晶面暴露等策略实现,高密度表面Ov可显著增强CO2吸附与活化能力,促进甲酸盐路径。活性金属–尖晶石协同作用通过构建强金属–载体相互作用(SMSI),实现H2在金属位点解离、CO2在尖晶石位点活化的空间分区活化,有效抑制副反应。尖晶石催化剂上CO2加氢制甲醇的路径选择并非静态过程,而是受表面组成、缺陷结构、金属协同及反应条件动态调控的结果。尖晶石体系在CO2加氢制甲醇反应中展现出良好的选择性与稳定性优势;然而,其在含杂质气源条件下的长期稳定性有待深入探索,且在温和条件下的时空产率仍是工程化瓶颈。未来研究应聚焦于气源杂质稳定性与抗毒设计、原位/工况表征与微观动力学协同、活性位点/结构定向调控、界面工程的定量化与可逆调控、串联催化与反应工程协同优化等方面,通过“缺陷–配位–界面”核心调控框架,实现尖晶石催化剂在CO2加氢制甲醇反应中的性能突破。该综述旨在从原子尺度阐明催化剂结构与反应路径的构效关系,为高性能尖晶石催化剂设计提供理论指导。

       

      Abstract: The synthesis of green methanol from CO2 and green hydrogen represents a crucial pathway for achieving carbon cycling and energy structure transition. However, high-efficiency catalysts remain the bottleneck hindering its industrialization. Spinel oxides (AB2O4) are ideal materials for catalyzing CO2 hydrogenation to methanol due to their cation exchangeability, structural robustness, and surface acid-base synergy. This review systematically summarizes the research progress on the structure-activity relationships and modification strategies of spinel catalysts. Firstly, the reaction mechanism of CO2 hydrogenation over spinel catalysts is analyzed. It is revealed that the CO2 activation mechanism relies on electron transfer mediated by surface oxygen vacancies (Ov) and the synergistic effect of the inherent Lewis acid-base pairs (Mn+−O2−). Concurrently, H2 activation on spinel catalysts occurs via heterolytic dissociation pathways, with the Ov concentration, electronic structure of the metal centers, and the synergistic effect of Mn+−O2− pairs influencing the H2 activation energy. The reaction pathway mainly involves two competitive routes: the formate pathway and the reverse water-gas shift coupled with CO hydrogenation pathway (RWGS + CO hydrogenation). Secondly, spinel catalysts modification strategies are summarized, including precise regulation of oxygen vacancies, synergistic optimization of coordination-electronic structures, synergistic reinforcement of active metal-spinel interfaces, and the construction of spinel-zeolite tandem catalysts. Ov regulation and coordination-electronic structure modification are achieved through strategies such as element doping, reduction pretreatment, and facet exposure. High-density surface Ov enhances CO2 adsorption and activation, promoting the formate pathway. The synergistic effect between active metals and spinel is realized by constructing a strong metal-support interaction (SMSI), enabling spatial compartmentalization of H2 dissociation at metal sites and CO2 activation at spinel sites, effectively suppressing side reactions. The pathway selection in CO2 hydrogenation to methanol over spinel catalysts is not a static process but is dynamically regulated by surface composition, defect structure, metal synergy, and reaction conditions. Spinel systems exhibit excellent selectivity and stability advantages in the CO2-to-methanol reaction; however, their long-term stability under impurity-containing gas sources requires further exploration, and the space-time yield (STY) under mild conditions remains an engineering bottleneck. Future research should focus on stability against gas impurities and anti-poisoning design, synergy between in situ/operando characterization and micro kinetics, directional regulation of active sites/structures, quantification and reversible control of interface engineering, and synergistic optimization of tandem catalysis and reaction engineering. Through the core regulatory framework of “defect-coordination-interface”, breakthroughs in the performance of spinel catalysts for CO2 hydrogenation to methanol can be achieved. This review aims to elucidate the structure-activity relationships between catalyst structure and reaction pathways at the atomic level, providing theoretical guidance for designing high-performance spinel catalysts.

       

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