Recent advances in the development of nanosheet zeolites as heterogeneous catalysts

Abstract

Recently, zeolites with two-dimensional structures, so-called nanosheet zeolites, have been intensively advanced owing to their excellent catalytic performance compared to conventional zeolite. This extremely thin nanosheet structure of zeolite provides more accessible active sites contributing to shortened diffusion pathways and primarily enables bulky molecules to undergo catalytic reactions. Several nanosheet zeolites, such as MFI, FAU, MOR, MWW, TS-1, have been successfully synthesized. Generally, they are obtained by direct synthesis method involving surfactant as structure-directing agent (SDA) and or seed. Interestingly, almost every part of the synthesis parameter conditions can alter the characteristics of this nanosheet zeolite. Thus, 2D zeolites also offer easily tunable characteristics. Up to now, nanosheet zeolites have been extensively studied as a catalyst in methanol conversion, catalytic cracking, isomerization, alkylation, oxidation/reduction, lignocellulose conversion, and other reactions. Furthermore, the modification of nanosheet zeolite could be pursued to enhance its catalytic performance. Pillaring is evidently effective in improving the textural properties of nanosheet zeolite by protecting the mesopore structure during the SDA removal. Herein, we comprehensively present the recent progress on the development of nanosheet zeolites. This review concludes with a summary of a discussion of remaining challenges and outlook for nanosheet catalyst technologies.