| As economy development, the demand of resources of mankind is increasing. Development of new energy is becoming more and more important due to the limited fuel energy and its pollution during application. Biomass is a kind of clean renewable energy resource with the advantage of low pollution and high amount for utilization. Biomass has drawn more and more attention of researchers. This study focuses on effects of various factors on lignin abstracting yield and its separation process from pine wood.Firstly, the effects of temperature, the ratio of liquid to solid, constant temperature holding time, alcohol fraction, acid fraction and alcohol type on lignin abstracting were investigated under high pressure condition via orthogonal experiments. Glycol was finally selected as proper solvent. The effects of various factors on lignin abstracting in glycol as well as in mixture of glycol and ethanol were investigated and the product obtained was characterized with UV and FT-IR. Solvents reusing was also initially attempted. The results show that glycol is effective solvent for lignin abstracting and solvent reusing is possible.Secondly, the effects of various factors on lignin yield were investigated under condition of mixture solvent of glycol and water with microwave heating. The results were compared with the above conventional experiment and it shows that microwave can increase yield of lignin and the reaction time can be shortened greatly. The series reaction model was established for lignin abstracting process under microwave heating condition and the model can describe the process well.Finally, the pyrolysis characteristics of the obtained lignin were analyzed and the kinetic parameters (pre-exponent factors and activation energy) were calculated according to TG curves and the pyrolysis mechanism functions for different phase were determined.The experiments show that the lignin abstracting yield is up to49.12%when glycol is used as solvent and the repeating use of the solvent for three times can still lead to similar results as those from the fresh solvent. Fourier transform infrared and ultraviolet and visible spectra show that the acquired lignin structure contains a lot of phenyl-propane units and ether bonds and carbon-carbon bonds. Dynamics calculations of the lignin activation energy is68.314KJ/mol.Fig [21] Table[22] Reference[51]... |
