Towards a comprehensive understanding of mesoporosity in zeolite Y at the single particle level

Abstract

A full understanding of zeolite mesoporosity is not trivial and yet is necessary to understand and optimize the catalytic performance of zeolites. The present work reports an integrated approach for the comprehensive study of zeolite mesoporosity. The comprehensiveness and effectiveness of the methodology are exemplified by the characterization of hierarchical zeolite Y samples prepared by NH₄F etching. In the present work, usually lacking information of mesopore morphology, connectivity and spatial location was obtained by the ultra-high-resolution FE-SEM imaging of the zeolite cross-section after surface coating with osmium (Os). The ultrahigh-resolution SEM study allowed both: (i) the macroscopic documentation of the interconnecting channel-like porosity separating intergrown crystals; and (ii) the nano-scale resolving of mesopore spatial distribution within an individual crystal. In addition, the combination of NH₄F etching with the state-of-the-art ultra-high-resolution FE-SEM imaging technique proved as a powerful methodology to reveal otherwise inaccessible information regarding the mesopore formation mechanism. The hierarchical pore structure analysis of zeolite Y was combined with catalytic testing in the dealkylation of 1,3,5 tri-isopropylbenzene for deeper understanding of its physicochemical properties.