FTIR as a simple tool to quantify unconverted lignin from chars in biomass liquefaction process: Application to SC ethanol liquefaction of pine wood

Lignin in solid residues produced from wood liquefaction can be quantified by FTIR analysis. This is applied to investigate pine wood liquefaction in supercritical ethanol in comparison with model lignin and cellulose in order to achieve a thorough description of wood liquefaction in SC ethanol. The proportions of lignin, hemicelluloses, cellulose and chars in the solid residue were quantified by compositional analysis based on acid hydrolysis combined to the quantitative FTIR analysis of the νCC vibration of lignin at 1514 cm− 1. It was shown that SC ethanol is an efficient medium for an easy liquefaction of lignin and hemicellulose from pine wood. Native cellulose in pine wood was only slightly attacked by contrast to microcrystalline cellulose. From pine wood, gas production is limited to 3 wt.% and total yields in liquid products achieved 45 wt.% but only one fourth of liquid products were eluted by GC-MS.