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The overall target of this project, called Bioforest, is to develop an economic process for the production of commodity chemicals from mixed forest biomass, consisting of logging residues of hardwoods (HW) and softwoods (SW) and also from recycled fibers. The aim is to dissolve the biomass lignin and to produce monosugars based on hemicelluloses and hydrolyzed cellulose in high yield. The hydrolyzate could subsequently be converted into chemicals by modified acetone-butanol-ethanol fermentation. Here, the total mass balances of SO2-ethanol-water fractionation of different types of biomass feedstocks, such as SW and HW biomass, and deinked pulp are presented. Chemical composition of the feedstocks, solid residues (pulps) and spent liquors of fractionation were analyzed to gain more understanding about the fractionation procedure. The analysis was focused on carbohydrates, lignin, ash, acetyl groups and sugar degradation products. It was also examined if all feedstocks could be treated simultaneously in one digester because a larger feedstock supply within an economic transport radius improves the viability of the process. The fractionation approach was successful and it can be concluded that the method presented is very versatile for future applications in lignocellulosic biorefineries. [ABSTRACT FROM AUTHOR]

A mixture of US southern hardwood chips was treated with aqueous acetic and formic acid (FA) solutions in a modified Dionex ASE100 extractor. The amount and selectivity of hemicelluloses dissolution increase at higher acetic acid (AA) and FA concentrations, but cellulose remains intact in the residual wood. Even at the highest AA concentration of 100 g l-¹, the dissolved hemicellulose fragments are still oligomeric except for arabinose. The formation of lignin-like condensation products (LCPs) and decomposition of dissolved mannose, arabinose, and galactose were observed at the highest AA concentration. Sugar hydrolysis is more pronounced with the addition of FA at increasing temperature. The concentration of xylose in the FA extract is approximately the same as that of xylooligomers at 160°C. Formation of LCPs is only observed at 170°C during 10 g l-¹ FA treatment. The concentrations of dissolved wood components increase linearly with increased recycling of the FA extract. [ABSTRACT FROM AUTHOR]