Preparation and Optimization of Bio-polyols from Sawdust Liquefaction Using Crude Glycerol and Polyethylene Glycol

Abstract

Bio-based polyols derived from lignocellulosic biomass have attracted considerable attention as sustainable alternatives to petroleum-based polyols in polyurethane production. In this study, spruce sawdust was liquefied using pretreated crude glycerol (PCG) and pretreated crude glycerol/polyethylene glycol (PCG/PEG) binary solvent systems under acid-catalyzed conditions to produce bio-polyols. The effects of reaction temperature, reaction time, and solvent composition on biomass conversion, hydroxyl number, acid number, and viscosity of the resulting polyols were systematically investigated using response surface methodology (RSM). Liquefaction experiments were conducted at temperatures ranging from 100 to 180 ºC for PCG and 120 to 200 ºC for PCG/PEG mixtures, with reaction times between 40 and 360 min. The results demonstrated that increasing temperature, reaction time, and PEG content significantly enhanced biomass conversion efficiency. Statistical analysis confirmed that temperature and reaction time were the most influential parameters affecting polyol properties and liquefaction performance. The incorporation of PEG improved biomass conversion and reduced viscosity compared with PCG alone. The obtained bio-polyols exhibited physicochemical characteristics within the range generally considered suitable for rigid polyurethane foam polyol formulations, demonstrating the potential of PCG and lignocellulosic waste as sustainable feedstocks for high-value polyurethane materials.