Synthesis of hollow Y zeolite for catalytic applications

Abstract

SSCI-VIDE+ING+CPG:DFA:ATUInternational audienceMainly motivated by catalytic applications, the design of zeolites with diverse and well controlled morphologies remains a topic of intense research and development. In this sense, it is worth highlighting FAU-type materials that are extensively used in industrial catalytic and adsorption processes. The design of multimodal pore Y zeolite materials have been then emerging in order to combine the catalytic features of the zeolite and improved transport properties. In the literature, we can distinguish between two different approachesfor multimodal pore systems: creation of hierarchical structures with intraparticle mesopores and synthesis of nanocrystals (< 100 nm) with interparticle mesopores. Both approaches yield Y zeolite materials with smaller zeolite domains and concomitant larger external surface area.Here, we propose an alternative approach that consists in synthesizing a new class of crystalline materials: hollow Y zeolite crystals which possess a large central cavity and similar size and shape to the parent crystals. In contrast to classical hierarchical zeolite materials, following this procedure, it can be obtained a smaller zeolite domain, i.e. the walls are thinner while the external surface remains approximatively the same. So far,hollow single crystals have mainly been created from MFI-type zeolites thanks to a natural gradient of composition. The dissolution/recrystallization approach cannot be directly applied to as-synthesized Y zeolites, because the homogeneous distribution of aluminum throughout the crystals prevents a preferential dissolution of the core as opposed to the surface.We report for the first time, a top-down pathway for the synthesis of original hollow Y zeolite from parent crystals in which a gradient of composition has been artificially created. Materials were obtained by a three-step process based on successive dealumination/realumination reactions followed by a selective dissolution of crystal cores.See this article for further informations : Pagis et al., CrystEngComm, 2018, 20, 1564 - 157