Abstract:

Dry reforming of methane can convert two greenhouse gases (CO₂ and CH₄) into syngas, for which traditional supported catalysts suffer from the sintering of metal particles and the carbon deposition, leading to the deactivation. Core-shell structure catalysts can effectively solve the aforementioned problems due to the spatial confinement effect. In this paper, the core-shell structures are classified into three categories, SiO₂ shell layer, Al₂O₃ shell layer and other shell layers, according to the shell type. Current research status is reviewed from the aspects of preparation method, structure-morphology and catalytic characteristic, respectively. The advantages of SiO₂ shell layer are simple preparation, facile adjustment of the thickness and mesoporous structure, and high thermal stability, while Al₂O₃ shell layer can provide alkaline sites to enhance the adsorption and reaction of CO₂ and the CeO₂ shell layer can provide oxygen vacancies to promote the activation of CO₂ and the gasification of accumulated carbon. Finally, this paper proposes several future research directions for core-shell structures, i.e. the expansion and study of shell materials, the investigation of new core-shell structures such as yolk-shell and sandwiches, the precise adjustment of the morphology of core-shell structures and the study of structure-catalysis relationships, and the large-scale preparation for industrial applications.

Key words: catalyst, carbon dioxide, multiphase reaction, syngas, core@shell structure

摘要：

甲烷干重整可以将两种温室气体（CO₂和CH₄）转化为合成气，传统负载型催化剂存在金属烧结、碳沉积的问题，导致失活。核壳结构催化剂具有空间限域效应，能有效解决以上问题。本文根据壳的种类，将核壳结构分为SiO₂壳层、Al₂O₃壳层和其他壳层三类，并分别从制备方法、形貌结构、催化特性的角度介绍了研究现状。文中指出：氧化硅壳层的优势是制备简单，壳层易于调控，热稳定性高；Al₂O₃壳层能够提供碱性位点，增强CO₂吸附与反应；CeO₂壳层则可以提供氧空位，促进CO₂活化和积炭的气化。据此，本文展望了核壳结构在未来的几个研究方向：对壳层材料的拓展与研究；对蛋黄壳、三明治等新型核壳结构的研究；精准调节核壳结构的形态并研究构效关系；大规模制备和工业应用等。

关键词: 催化剂, 二氧化碳, 多相反应, 合成气, 核壳结构