Catalytic conversion of lignin into sustainable aviation fuels

In the context of the decarbonization of aviation sector, the use of sustainable aviation fuels (SAF) is mandatory to finally reach 70% by 2050 according to the ReFuelEU Aviation regulation adopted in October 2023 by the European Union Council. Lignin is the world's largest source of renewable aromatics making it a promising candidate to produce aromatics and cycloalkanes within the range of jet fuels. While already co-produced in the pulp industry, lignin will soon be available in greater quantities through emerging second-generation cellulosic bioethanol technology. Nowadays, lignin is underutilized and is primarily recovered for its heat value. The project OPTISFUEL aims to improve the efficiency and sustainability of second-generation cellulosic bioethanol technology by boosting fermentation yields and carbon conversion within the biorefinery (CO2 and lignin). The main challenge of this work is to depolymerize lignin from enzymatic hydrolysis using bifunctional metal sulfide/acid heterogeneous catalysts to monomers. Those catalysts can lead to C-O and C-C bonds cleavage of inter-linkage units, but also hydrogenation, hydrogenolysis, dehydration and, ring-opening reactions in order to obtain SAF-compatible hydrocarbons i.e., aromatics, naphthenic and linear deoxygenated hydrocarbons.