Studies On Extraction Of Phenolic Compounds And Hydro-thermal Treatment Of Biomass Gasification Tar

Biomass gasification tar which contains abundant phenolic compounds and hydrocarbons is a byproduct in gasification, and can be the raw material of high value-added phenolic organic matter by extraction or liquid fuels by hydro-thermal treatment. In this study, the main contents and achievments were summarized as following:(1) Firstly, The basic properties of biomass gasification tar were analyzed, while group composition was obtained by using column chromatography method. The separated fractions were characterized to obtain the relatively complete data. The results show that the biomass gasification tar has some special properties (high water content, high viscosity, and high heteroatom content) and has complex chemical composition of valuable compounds (n-alkanes, n-alkenes, phenols, acid and pyrazine et al).(2) Extraction processes of phenolic compound and optimum process parameters were investigated. The results show that the optimal process was firstly to get rich phenolic fraction, then crude phenols was obtained by alkali and acid washing. The fraction of 110～180℃ as raw material might be appropriate for extraction of phenolic compound. The optimum process parameters were alkali concentration of 20%, reaction time of 5 minutes, reaction temperature of 50℃, acid concentration of 20%, reaction time of 30 minutes and reaction temperature of 22℃. The yield of crude phenols reaches 50.24%(mass percentage of rich phenolic fractions) under optimal process conditions. GC/MS of crude phenols shows that the content of phenolic compounds and low-rank phenols was 98.49% and 73.90%, respectively; In low-rank phenols, the 4-ethylphenol had the highest content of 16.50%.(3) Hydro-thermal treatment of tar were investigated. Hydro-thermal treatment of tar can improve the content of oil, H/C atom ratio of oil, and the high heat value of oil. The yield of oil increases 24.26%, the yield of asphaltene and preasphaltene decrease 20.93%, and the yiel d of residue decreases 5.81% with the optimum conditions (CO atmosphere,375 ℃,60min, addition of Na2CO3).