STUDY ON LIQUEFACTION OF BAGASSE ALKALI LIGNIN FOR THE PRODUCTION OF PHENOLIC CHEMICALS

摘要

Alkali lignin, a waste polymer by-product from kraft-pulping process in the pulp and paper industry, was usually burnt off. Lignin has aromatic and aliphatic characters and can be used to produce small chemicals instead of oil and natural gas. In this paper, bagasse alkali lignin (BAL) was used as material and aluminium silicate was chosen as catalyst for producing phenolic chemicals. The optimum parameters of catalytic liquefaction were aluminium silicate 4% (w/w, based on BAL), heating time 1.0 hour, heating temperature 270°C, solvent glycerol 6 ml/g (v/w, based on BAL). The yield of phenolic compounds approached 54.10%. From the results of HPLC analysis, the main products were 2,6-dimethoxy-phenol (15.73wt%), 2-methoxy-phenol (12.26wt%) and phenol (13.65wt%), based on BAL respectively, and the structural changes of BAL during liquefaction were also discussed by 1H-NMR. First, Cα–C bond of the phenylpropane linkage was broken to produce phenolic chemicals. Second, the α-ether linkages (α-O-4) and the β-ether linkages (β-O-4) were broken to produce alcoholic, esters and ketenes compounds, which came from the condensation and esterification of small products.