Quantitative structural characterization and thermal properties of birch lignins after auto-catalyzed organosolv pretreatment and enzymatic hydrolysis

BACKGROUNDTo achieve the goals of economically feasible auto-catalyzed organosolv pretreatments in bioethanol production, chemical conversion of the isolated lignin is needed. However, the structures and properties of lignin molecules produced after pretreatment have not been thoroughly investigated before its effective utilization. RESULTSThe study focused on the auto-catalyzed ethanol-water pretreatment of southwest birch, with the aim to clarify the structural transformations of birch lignin after pretreatment. Chemical structural elucidation of the isolated lignins was performed using multiple NMR methodologies (P-31-, C-13- and 2D-HSQC NMR techniques). Results showed that the amount of -O-4 linkages decreased in the order of AEOL (auto-catalyzed ethanol organosolv lignin)