Improvement of direct liquefaction of technical alkaline lignin pretreated by alkaline hydrogen peroxide

Technical alkaline lignin was first pretreated with alkaline hydrogen peroxide and then liquefied using methanol-water mixture or methanol solvents. When the technical lignin was pretreated by 0.5% H2O2 at 80 C, the liquid yield of the liquefaction in methanol-water mixture and methanol increased from 84.2% to 93.5% and from 79.2% to 90.5%, respectively. The alkaline lignin (AL), pretreated lignin (PL) and resulting liquid (RL) were characterized by using GPC, FT-IR, and H-1 NMR methods. The GPC results illustrated that the pretreatment by 0.5% H2O2 could decrease the weight average (Mw) and number average (Mn) molecular weight from 1692 to 1354 g/mol and from 1376 to 1207 g/mol, respectively. The FT-IR and 1H NMR results confirmed that some phenols were oxidized to quinone or aliphatic chain structures, and parts of side chains were separated from lignin. (C) 2016 Elsevier B.V. All rights reserved.