Highly efficient electro-reductive conversion of lignin into aromatics and cyclohexenes

Abstract

The catalytic upgrading of biomass into value-added molecules is a key strategy for achieving sustainable biorefinery, which is central to transitioning from fossil-based resources to sustainable bio-based alternatives. Herein, we propose an innovative approach involving the electrocatalytic conversion of lignocellulose biomass and diaryl ethers over 5 wt% Pd/C under mild reaction condition. The electrocatalytic hydrogenolysis of 4–O–5 and α–O–4 diaryl ethers was performed in a HClO4 buffer at a constant current density of 50 mA cm−2 and 70 °C. We achieved 100 % conversion of diaryl ethers in 90 min with high selectivity of the corresponding monomers. The influence of temperature, solvent environment, current density, and reaction time on the efficiency of the hydrogenolysis of C–O bond was investigated using diphenyl ether and phenyl tolyl ether as 4–O–5 and benzyl phenyl ether as α–O–4 models of lignin-based dimers. Moreover, we achieved 19.6 C% lignin-derived phenolic monomers yield from birch wood biomass using 0.5 M acetate buffer at 70 °C, with a high selectivity (41.6 %) for 4-n-propanol syringol.