(403d) Enhancing the Physicochemical Properties of Zeolites through Facile Post-Synthesis Treatments

Zeolites are nanoporous aluminosilicates that are widely-used commercial catalysts owing to their shape-selectivity and tunable physicochemical properties, which can be tailored for different processes. Recent efforts to optimize zeolite catalyst performance tend to focus on new approaches to reduce mass transport restrictions. Two of the most effective approaches to address these synthetic challenges are the synthesis of nanosized zeolites and the introduction of mesopores and/or macropores (i.e., hierarchical zeolites). The latter has been demonstrated by Jain et al. [1] using a one-pot synthesis method wherein zeolite seeds are used to generate intergrown nanosheets of two pentasil zeolites (five-membered ring MFI and MEL types). These self-pillared pentasil (SPP) zeolites have been shown to exhibit superior catalytic performance compared to traditional zeolite ZSM-5 (MFI) counterparts. Here, we will describe various post-synthesis treatments that can be used to reduce defects and enhance the hydrothermal stability and catalytic performance of SPP materials beyond those of conventional analogues. Notably, we will describe the nature of defects that are prevalent in ZSM-5 catalysts and the most effective ways to mitigate their deleterious effects. Examples include the use of passivated siliceous exterior surfaces that improve mass transport properties and eliminate non-selective reactions on the exterior surfaces of zeolite catalysts. Comparisons will be made for several classes of nano-sized and hierarchical materials to demonstrate the superiority of SPP zeolite catalysts.

References:

[1] Jain, R., Chawla, A., Linares, N., Garcia Martinez, J., Rimer, J.D.: “Spontaneous Pillaring of Pentasil Zeolites” Adv. Mater.33 (2021) 2100897