(475b) Distillable Amine-Based Solvent Pretreatment of Woody Biomass for Enzymatic Conversion

The use of distillable solvents for pretreating lignocellulosic feedstocks to improve their enzymatic saccharification holds promise for biorefineries due to its efficiency and solvent recycling capabilities. Here, we examine the enzymatic conversion of woody biomass into fermentable sugars using distillable amine-based solvents. Various solvents, including butylamine, triethylamine, ethanolamine, and ethanolamine acetate, were assessed for the pretreatment of hardwood at 15 wt% solid loading in a pressure tube reactor at 140 °C for 3 hours. Following solvent evaporation in a vacuum oven, the pretreated biomass underwent enzymatic hydrolysis with 15 wt% solids in the same reactor using Cellic® Ctec3 and Htec3 enzymes (9:1 v/v) at 30 mg protein per g biomass. The solvent evaporation study revealed excellent performance of triethylamine and butylamine in solvent removal (100% and 98%, respectively). However, unsatisfactory sugar release was observed with triethylamine (6.85 g/L glucose and 2.32 g/L xylose after 72 hours), whereas butylamine-pretreated hardwood exhibited significantly higher conversion (55.10 g/L glucose and 16.6 g/L xylose). Evaluation of these solvents' presence during enzymatic hydrolysis revealed a notable reduction in enzyme activity, varying with solvent concentration when using pure cellulose and xylan as substrates. Hence, both the ease and effectiveness of solvent removal, along with the solvent's pretreatment efficiency, should be jointly considered for the efficient and profitable biomass deconstruction into fermentable sugars.