工业碱木素热化学转化制备酚类化学品

Preparation of phenols using thermal chemical conversion of industrial kraft lignin

引言 工业碱木素是碱法制浆过程中产生的重要副产物之一,其排放污染问题越来越受到关注,目前工业处理方法只是将其浓缩燃烧以回收能源和残碱。

Industrial kraft lignin,a waste produced by kraft-pulping process in the pulp and paper industry,was usually burnt off.Lignin is of aromatic and aliphatic characters and could be used to produce some chemicals.In this paper,phenols were prepared using kraft lignin as material,FeS as catalyst and glycerol as solvent,and the feasibility and technological parameters of chemical conversion of industrial kraft lignin were studied.The results from response surface methodology（RSM）experiments showed that the optimal reaction conditions were catalyst dosage 4%,heating time 1 h,heating temperature 270℃,liquor-solid ratio 5 ml·g-1.Total yield of phenols,obtained from GC-MS quantitative analysis,was up to 55.18%.The main phenols were 2-methoxy-phenol,4-methyl-2-methoxy-phenol and 2,6-dimethoxy-phenol.The test results also indicated that hydrogen free radical provided by hydrogen-donor solvent such as phenol and tetralin could effectively promote the thermal conversion of industrial kraft lignin.In summary,this chemical conversion method of industrial kraft lignin to phenols was feasible and effective.The results of kinetic study showed that the thermal conversion followed first order reaction kinetics,and reaction rate constant was 0.0212 min-1 and activation energy was 35.7251 kJ·mol-1.