New Biorefinery Strategy for High Purity Lignin Production

Due to their aromatic nature, lignins are of particular interest for chemical conversions of lignocellulosic resources. Organosolv pulping processes generally provide higher purity lignins, with lower sugar and ash contents than is the case with conventional pulping technologies (kraft, sulfite or soda). The strategy for new organosolv biorefinery presented here was to sequentially remove the extractives before pulping. The products obtained from organosolv pulping of aspen wood with a Lewis acid catalyst were compared to those from processes performed with the same wood and solvent system, but without or with mineral acid as catalyst. The new strategy with Lewis acid catalyst developed in this study proved to allow more efficient recovery of high purity lignin, which was determined to have a high Klason, low sugars, volatiles and ash contents, while preserving a good portion of β-O-4 moieties (31P and HSQC NMR), typical for native lignin. The thermal properties of this lignin were determined to be favorable to its transformation by electrospinning. It was successfully spun without need for any additives or modifications before electrospinning experiments.