Unexplored areas of direct solvolytic liquefaction of lignocellulosic biomass

Most research on direct solvolytic liquefaction (DSL) focuses on hydrothermal liquefaction or organic model solvents and is dominated by catalytic processes. This review highlights the much less understood aspects of non-catalytic DSL including the solvent recycling required for continuous processing. Results from earlier studies indicate both the feasibility of recycling and the non-catalytic suppression of char formation. However, a proof of continuous operation under steady state with a stationary solvent composition and an extensive investigation of process parameters are missing to date.