Improved Conversion Efficiency of Lignin-to-Fuel Conversion by Limiting Catalyst Deactivation

Abstract Herein, the lignin-to-fuel conversion process was studied using real lignin as feedstock. Unlike model compounds, real lignin poisons the catalyst, causing rapid deactivation. The problem of catalyst deactivation was analyzed in detail for improving the conversion efficiency. We found that heavy carbonaceous deposits on the inner surface of the catalyst were responsible for the fast deactivation encountered in the conventional one-step reaction process. Moreover, the ester structures in lignin, which have previously been neglected in research, were confirmed to considerably worsen catalyst deactivation because they induce easier polymerization and hinder lignin conversion. Based on these points, we developed a three-step method that eliminates serious catalyst deactivation in the lignin-to-fuel conversion process, involving depolymerization of lignin, extraction of lignin monomers and hydrodeoxygenation of lignin monomers. The fuel production was 8.1–17.6-times more efficient using this three-step method than using the one-step batch reaction.