Zeolite-catalyzed alkylation of lignincellulose-derived phenols and furan alcohols for synthesis of sustainable aviation fuel

Abstract

Synthesis of biofuels from lignocellulosic depolymerization products is a promising path. However, the commonly used feedstocks are the downstream depolymerization products of lignocellulose. Here we report an effective method to produce biofuels from upstream depolymerization products of lignocellulose (i.e. lignin derived phenols and holocellulose derived furan alcohols). Phenols and furan alcohols undergo alkylation reaction with zeolite as catalyst, and then alkylation products can be turned into hydrocarbon fuel through hydrodeoxygenation reaction. For alkylation reaction, the key step is the electrophilic substitution reaction of carbocation formed under the catalysis of acid. For furfuryl alcohol with simple structure, the catalyst with large pore size and moderate acid content is sufficient to catalyze the reaction. For 5-hydroxymethylfurfural with higher steric hindrance, more acidic catalyst is required to promote the formation of carbocation. The two alkylation reactions can achieve both high conversion of furfural alcohol and selectivity of alkylation production over 85 %. The branched monocycloalkane fuel obtained by hydrodeoxygenation of alkylation products has a density of 0.807 g/cm³ (20 °C) and a freezing point less than −60 °C, meeting the requirements of RP-3 and is expected to become a main component of aviation jet fuel. This work provides ideas for the direct use of biomass depolymerization products to produce bio-aviation fuels with excellent performance.