Lignocellulosic biomass to glycols: Simultaneous conversion of cellulose, hemicellulose and lignin using an organic solvent

This study investigates the simultaneous conversion of holocellulose and lignin fractions during the catalytic hydrogenolysis of biomass to glycols, focusing on how different organic solvents, necessary to keep the lignin soluble, impact the conversion of non-delignified and deashed biomass, as well as the ethylene glycol production and lignin behavior. Although the catalyst amounts used were low, the cellulose and hemicellulose were converted into ethylene glycol, propylene glycol, sugar alcohols, and glycerol, yielding about 40 wt%. This is slightly lower than the benchmark process (acidified water and de-ashed biomass), which had a total yield of around 50 wt%. A noticeable difference between using organic solvents and water was found in the behavior of depolymerized lignin. When using an organic solvent, up to 63 % of the lignin could be extracted from the biomass and kept soluble, compared to only 15 % when using acidified water. The molecular weight distribution of solubilized lignin was similar for all organic solvents (Mw = 833-1190 g/mol), but it was significantly different from the benchmark experiment with acidified water (Mw = 423 g/mol).