Structure characterization and pyrolysis behavior of organosolv lignin isolated from corncob residue

Abstract

Structural features and pyrolysis behavior of organosolv lignin isolated from corncob residue by THF-H2O solvent were studied. The average molecular weight (Mw) of the organosolv lignin, mainly constituted of p-hydroxyphenyl (H), guaiacyl (G), syringyl (S) and various substructures with β-O-4, β-β bonds, was mainly distributed between 10,000 and 600 g/mol, occupying about 81%. TG/DTG curves of the organosolv lignin showed three maximum weight loss peaks at about 120, 150 and 350 °C, respectively. The pyrolysis of organosolv lignin was performed through two ways, that is, one-step at different temperature (RT-120 °C, RT-150 °C, RT-350 °C) and stepwise (120–150 °C, 150–350 °C) pyrolysis over different temperature range. The results indicated that oligomers with molecular weight between 200 and 500 Da were the main products in bio-oil at the low temperature step, while high temperature step produced certain amount of monomers of phenols, guaiacols and syringols. The variation of structure and molecular weight distribution of pyrolyzed residues was further investigated.