Recent advances in engineering montmorillonite into catalysts and related catalysis

ABSTRACT

Montmorillonite, a ubiquitous clay mineral, has been engineered into a variety of porous and nanostructured catalysts, owing to its peculiar layered structure with characteristic surface and intercalation chemistry. Such a class of catalysts have continuously received considerable attention in both science and industry. This review examines recent advance in engineering montmorillonite into metal ion-exchanged montmorillonite catalysts, acid-activated montmorillonite catalysts, organo-montmorillonite catalysts, pillared interlayered montmorillonite catalysts and montmorillonite-supported catalysts. The former two types of montmorillonite-based catalysts have been used in the catalytic cracking, dehydration, hydrolysis, esterification, polymerization, alkylation, and Fischer-Tropic synthesis. The introduction of oxide pillars in the interlayer space of montmorillonite and the immobilization of metal oxides or zero-valent metals on the surface of montmorillonite allow montmorillonite to be used in the catalytic oxidation, reduction, isomerization and coupling reactions. Currently, the role of montmorillonite in acid catalysis, redox catalysis, and free radical catalysis have been partly revealed. The effect of the structures and the active sites of modified montmorillonite on its catalytic performance need to be investigated in more detail. Future work is suggested to focus on solving engineering problems and exploring novel catalytic applications of montmorillonite, in particular exfoliated montmorillonite nanolayers.

KEYWORDS:

• montmorillonite
• layered structure
• porous material
• ion exchange
• pillared clay
• heterostructure

Acknowledgments

This research was financially supported by the National Natural Science Foundation of China (22072136, 41701334), and the funding from Engineering Research Center of Non-metallic Minerals of Zhejiang Province, Zhejiang Institute of Geology and Mineral Resource, China (ZD2020K07). CHZ dedicates this work to the memory of his father JunHai ZHOU (1943.2.22-2021.9.5), who suffered a severe illness in August and passed away on Sunday, September 5, 2021, the period CHZ was discussing with the co-authors and handling the manuscript revision.

Disclosure statement

No potential conflict of interest was reported by the author(s).