Abstract:

In order to increase the utilization value of alkali lignin from bagasse,aluminium silicate was chosen as the catalyst to produce phenolic chemicals from the lignin via a liquefaction process.The reaction conditions including aluminium silicate dosage,heating time,heating temperature and liquid-solid（glycerol-bagasse alkali lignin） ratio were then optimized as follows： an aluminium silicate dosage of 4%（based on the dry bagasse alkali lignin）,a heating duration of 1 h,a heating temperature of 270℃ and a liquid-solid ratio of 6 mL/g（based on the dry bagasse alkali lignin）.In these conditions,phenolic chemicals mainly containing 2,6-dimethoxy-phenol,2-methoxy-phenol and phenol were produced,with a total yield of 54.10%.Moreover,the structures of functional groups of the alkali lignin before and after the liquefaction were analyzed by means of FT-IR and 1H NMR.The results show that,when the heating temperature reaches 270 ℃,the propane units of the phenylpropane separate from benzene units in the presence of aluminium silicate,and the β-ether lingkages（β-O-4） break due to high temperature and the existence of acid.At the same time,few α-ether lingkages（α-O-4） break to produce phenols following the separation of propane units.

Key words: bagasse, alkali lignin, liquefaction, glycerol, phenolic chemical