Pre-treatment of lignocellulosic feedstocks using biorenewable alcohols : towards complete biomass valorisation

NJW would like to acknowledge the EPSRC grants EP/J018139/1 and EP/K00445X/1 for funding and PJD and KB would like to acknowledge the European Union (Marie Curie ITN ‘SuBiCat’ PITN-GA-2013-607044) for funding. CSL and IP would like to thank the Engineering and Physical Sciences Research Council [EPSRC Doctoral Prize Fellowship to CSL] and CRITICAT Centre for Doctoral Training for financial support [Ph.D. studentship to IP; Grant code: EP/L016419/1].Here, we report on the ability of the biomass derived solvents ethanol and, in particular, n-butanol to fractionate lignocellulose into its main components. An organosolv system consisting of n-butanol containing 5% water and 0.2 M HCl at reflux was found to remove effectively the lignin and hemicellulose components of lignocellulosic biomass leaving a cellulose pulp suitable for enzymatic hydrolysis to simple sugars. Using a hardwood beech pulp as an example, essentially complete conversion of the cellulose component to reducing sugars was achieved with a cellulase loading of 22 FPU per g. Analysis of the solubilised hemicellulose fractions revealed that they consist almost exclusively of alkyl xylosides and mannosides which could serve as valuable synthetic building blocks. Additionally, the mild conditions (