Preparation of bio-polyols from lignocellulosic waste by liquefaction

Rigid polyurethane foam (PUF) with desirable properties such as low thermal conductivity, easy production and processing is extensively used in the industrial applications. Currently, the PU industry is heavily petroleum-dependent, because its two major feedstocks, i.e. polyols and isocyanates, are largely petroleum-derived. Due to concerns over the depletion of fossil resources, pollution, there has been a great deal of interest in developing bio-based polyols from renewable resources. Lignocellulosic biomass is considered to be suitable for production of bio-based polyols, having hydroxyl group rich compounds. In bio-refining processes, the lignocellulosic macromolecular are broken down and converted into a viscous liquid using certain solvents. The use of high volumes of liquefaction solvents increases the production cost of bio-polyols. This has led to research on low cost and renewable solvents such as crude glycerol. In this research crude glycerol was used as solvent for liquefaction of sawdust and polyol production. The influence of process variables such as reaction temperature and time on polyol properties, namely biomass conversion ratio, acid number, hydroxyl number and viscosity were measured according to the certain standards. With increasing liquefaction temperature, increased production efficiency and viscosity and acid, hydroxyl number of polyols decreased. Finally, polyol of liquefaction at 180 and 360 min with production efficiency of 51%, acid, hydroxyl number and viscosity of 9/7, 325 mgKOH/g and 18 Pa,s was determinate as optimum polyol.