Selectivity descriptors of the catalytic n-hexane cracking process over 10-membered ring zeolites

Abstract

Zeolite-mediated catalytic cracking of alkanes is pivotal in the petrochemical and refining industry, breaking down heavier hydrocarbon feedstocks into fuels and chemicals. Its relevance also extends to emerging technologies such as biomass and plastic valorization. Zeolite catalysts, with shape selectivity and selective adsorption capabilities, enhance efficiency and sustainability due to their well-defined network of pores, dimensionality, cages/cavities, and channels. This study focuses on the alkane cracking over 10-membered ring (10-MR) zeolites under industrially relevant conditions. Through a series of characterizations, including operando UV-vis spectroscopy and solid-state NMR spectroscopy, we intend to address mechanistic debates about the alkane cracking mechanism, aiming to understand the dependence of product selectivity on zeolite topologies. The findings highlight topology-dependent mechanisms, particularly the role of intersectional void spaces in zeolite ZSM-5, influencing aromatic-based product selectivity. This work provides a unique understanding of zeolite-catalyzed hydrocarbon conversion, linking alkane activation steps to the traditional hydrocarbon pool mechanism, contributing to the fundamental knowledge of this crucial industrial process.