Design of MFI Zeolite-Based Composites with Hierarchical Pore Structure: A New Generation of Structured Catalysts

Abstract

Zeolite/glass composite materials with hierarchical trimodal pore size distributions have been successfully prepared and subsequently characterized. Starting from glass monoliths having meso- and macropores, additional microporosity was introduced while allowing the growth of zeolite crystals via partial recrystallization of the glass support into ZSM-5 zeolite phase. Structured zeolitic catalytic materials were produced using a combination of supramolecular templating methods to produce the glass support, followed by conventional self-assembly of template cations and silica species. Zeolite crystals are therefore in intimate contact with the glass support, featuring micropores in addition to the mesopores. Hence, these zeolite/glass composites exhibit enhanced diffusional properties in comparison with purely microporous zeolite materials. These enhanced mass transport properties allowed improvement of the selectivity toward light olefins in the important n-hexane cracking reaction.