From Lignin to Jet Fuel: Advancing Selective Cyclohydrocarbon Production Toward Full Compatibility with Aviation Standards

Abstract

Sustainable aviation fuel (SAF) derived from lignocellulosic biomass represents a critical pathway to decarbonizing the aviation sector. As the only abundant, naturally aromatic biopolymer, lignin offers unique potential for producing cyclic hydrocarbons compatible with conventional jet fuels. This review critically examines recent advances in lignin valorization strategies, focusing on two key stages: (i) the depolymerization of lignin into phenolic-rich bio-oils, and (ii) the selective hydrodeoxygenation (HDO) of these intermediates into cycloalkanes and arenes.Emphasis is placed on catalytic design, reaction engineering, and solvent systems that improve product selectivity and mitigate harsh HDO conditions. The conversion of lignin typically begins with the production of bio-oil containing phenolic monomers and dimers, which is then followed by HDO to convert these precursors into cycloalkanes primarily. This review examines and compares various methods for producing lignin bio-oil for jet fuel applications. It then explores strategies to improve the selectivity of cycloalkanes or arenes during the HDO process, highlighting effective approaches to mitigate the challenging reaction conditions associated with HDO. The review further analyzes the structural and physicochemical differences between lignin-derived hydrocarbons and certified jet fuels, underscoring the remaining challenges in achieving full compatibility, such as energy density, volatility, and combustion properties. Despite significant progress, the synthesis of a 100% lignin-based SAF blend remains unachieved, highlighting the need for an integrated framework that couples molecular-level fuel design with comprehensive performance metrics. This roadmap is essential to guide future research and industrial-scale implementation of lignin-based SAF.