Unraveling the effect of zeolite topology on the mechanism of furan deoxygenation to aromatics using operando Raman spectroscopy

Catalytic fast pyrolysis (CFP) of biomass has the potential to be a drop-in solution for chemicals and fuels beyond oil. However, understanding the relationship between catalyst structure and function remains a critical challenge hindered by the fast reaction dynamics. Here, we report an operando Kerr-gated Raman study, a powerful yet underexplored technique in catalysis research that allows for real-time monitoring of the different stages of the CFP reaction. In combination with UV-visible (UV-vis) spectroscopy and theoretical calculations, we demonstrate how the zeolite topology governs the chemical pathways and final product selectivity, influencing the type and fate of adsorbed intermediates. In addition to observing early formation of monomeric and dimeric furan, we demonstrate that benzofuran dominates the chemistry of the reaction on ZSM-5, playing a key role in the selective formation of monocyclic aromatic hydrocarbons. Furthermore, a pathway that deems benzofuran directly responsible for generating polyaromatic hydrocarbons is ruled out.