OxiOrganosolv: A novel acid free oxidative organosolv fractionation for lignocellulose fine sugar streams. (October 2020) - Kalogiannis, Konstantinos G.
Graphical abstract: Highlights: OxiOrganosolv – an acid free agnostic organosolv pretreatment was developed. Up to 97% of lignin was removed both from hardwood and softwood in a single stage. 100% cellulose recovery and high hemicellulose recovery in oligo- and mono-sugars. Close to zero sugar degradation products, pulps enzymatic conversion was 80%. High added value lignin oxidation products vanillin, syringaldehyde were produced. Abstract: The valorization of lignocellulosic biomass towards the production of value-added products requires an efficient pretreatment/fractionation step. In this work we present a novel, acid-free, mildly oxidative organosolv delignification process -OxiOrganosolv- which employs oxygen gas to depolymerize and remove lignin. The results demonstrate that the OxiOrganosolv process achieved lignin removal as high as 97% in a single stage, with a variety of solvents; it was also efficient in delignifying both beechwood (hardwood) and pine (softwood), a task in which organosolv pretreatments have failed in the past. Minimal amounts of sugar degradation products were detected, while cellulose recovery was ~100% in the solid pulp. Enzymatic hydrolysis of pulps showed >80 wt% cellulose conversion to glucose. Overall, the OxiOrganosolv pretreatment has significant advantages, including high delignification efficiency of hardwood and softwood biomass, absence of acid homogeneous catalysis and all corresponding challenges involved, and close to zero losses of sugars to degradation products.