The AlkaPolP process: Fractionation of various lignocelluloses and continuous pulping within an integrated biorefinery concept

The implementation of a lignocellulose-based biorefinery requires an efficient fractionation of its raw material. For this purpose a comprehensive biorefinery concept has been developed based on alkaline polyol pulping (AlkaPolP). It exhibits a high degree of flexibility with respect to the extent of fractionation by adjusting easily controllable process parameters. As shown in this contribution, the AlkaPolP process can be successfully applied for a wide range of lignocellulosic biomass including hardwood, softwood, bark and grasses, all of which yielding high quality product fractions. With essentially complete delignification the obtained pulp fraction is easily degraded by cellulases. The produced hydrolysates are free of inhibitors and can be used as substrates for a variety of fermentation processes. Without further modification, the AlkaPolP lignin fraction can be readily applied as high value substrate for various processes as confirmed by extensive characterisations in industrial and research laboratories (Dynea, Fraunhofer Institute). The remaining product fraction resulting from the degradation of various polysaccharides is being recovered as carboxylic acids. Based on extensive experimental results up to mini-plant scale, an integrated biorefinery concept has been developed including a continuous pulping stage and a full scale recycling of process chemicals thus allowing operations in environmentally sensitive rural areas. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.