Catalytic Fast Pyrolysis of Biomass over Microporous and Hierarchical Zeolites: Characterization of Heavy Products

The conversion of lignocellulosic biomass by catalytic fast pyrolysis (CFP) is a promising route to producing green aromatics and sustainable biofuels. The zeolite catalysts present a strong ability to produce light aromatics but also heavy products. In this work, these heavy products are monitored by a well-established petroleomic approach. The selectivity toward the heavy bio-oil components of both a common HZSM-5 zeolite and a hierarchical zeolite was investigated. Part of the molecular species from lignin derivatives is still present in the upgraded bio-oils. Deoxygenation and aromatization are the main modifications of the heavy compounds caused by zeolites, especially for the sugar derivatives. These effects are stronger for the hierarchical zeolite for which numerous heavy hydrocarbons (not oxygenated) are generated due to enhanced mass transfers within the crystallites. Moreover, this catalyst demonstrates a better stability upon an increase in the biomass-to-catalyst ratio.