Extraction, Characterization Of Bagasse Lignin And Its Following Liquefaction

Lignin, along with cellulose and hemicellulose, is a major component of lignocellulosic biomass. As such, lignin is the second most abundant natural polymer on earth. Industrially, however, lignin usually plays a negative role. What’s more, methods for the conversion and application of lignin other than simply burning it for the production of process heat are generally lacking. A major effort is therefore needed to develop new technology for lignin valorization by converting it, at least partly, to value-added chemicals.In this dissertation, liquefaction of bagasse catalyzed by acidic ionic liquids in subcritical water medium was investigated. Unlike cellulose and hemicellulose, lignin is inactive and rich in residue from liquefaction. Therefore, we use acidic ionic liquid catalysts for the extraction of lignin from sugarcane bagasse with ethanol-water solvents and catalytic conversion of cellulose and hemicellulose into value-added biochemicals.Main contents of this dissertation are as follows:(1) Catalytic liquefaction of bagasse for value-added biochemicals was investigated with acidic ionic liquids as catalyst and subcritical water as reaction medium. Results showed that96.1wt%of raw material can be liquefied in the presence of SO3H-functionalized ionic liquid, where more than50.6wt%of it is selectively degraded to low-boiling products. Aromatic lignin derivatives remained in residues;(2) An efficient method for the extraction of lignin from sugarcane bagasse with ethanol-water solvents and acidic ionic liquids catalysts. Physical and chemical proprieties of raw material and products were characterized. Results showed that97.6%lignin extraction to the total lignin in sugarcane bagasse and97.5%degree of liquefaction were achieved under the optimized conditions; the average molecular weight of isolated lignin is relative lower, resulting in its much easier for the further efficient transformation;(3) Catalytic liquefaction of isolated lignin was also investigated, where64.6%degree of liquefaction can be achieved with ionic liquid catalvst.