| For the purpose of broadening lignin comprehensive utilization, three kinds of lignin thermogravimetric analysis coupled with Fourier transform infrared spectroscopy(TG-FTIR) and lignin acetylating modification were conducted in this project.With sulfonated lignin, acid precipitation lignin, alkali lignin as substrate, using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy techniques(TG-FTIR), to study the mechanism of action and the way of each substance generate from the lignin pyrolysis of at different heating rates. The application of differential method and integration method to derive pyrolysis kinetic parameters, and zoom through a fluidized bed pyrolysis experiments to verify. The results showed that: Sulfonated lignin is similar to alkali lignin, the weight loss peaks are dispersed, and the peak of acid precipitation lignin focused on two temperature ranges of the whole weightlessness.Lignin pyrolysis process can be subdivided into three stages.The first stage was a loss in weight upon drying the sample, and mainly moisture was released at this stage. The second stage was fast thermal decomposition and weight loss occurred mainly in this temperature range. The main weight loss is about 60-70%.The last stage was high temperature charring of the residue and the weight loss was much smaller. Still, there remained little residue at 950℃, i.e., about 20 wt% of original weight,corresponding to the release of different substances. Combined with three-dimensional infrared spectra,it is obtained the law of CO, CO2, CH4, H2 O absorbance changes with time to further srudy the pyrolysis mechanism of three lignin.Selecting Sulfonated lignin to pyrolysis in the fluid bed, using Py-GC / MS to analysis the researved liquid bio-oil.The liquid product contained in the main component of ketones, phenols,sugars, etc., where in the phenol content greater. According to TG curves of the three lignin,using kissinger, Ozawa method and the derivative method of KAS, FWO modified kinetic study. The kinetic parameters of the four methods for same lignin calculated anastomosis, proofing methods are feasible. Determine the kinetic parameters of the three lignin, that is sulfonated lignin E =123.74 kJ/mol, lnA = 18.74 min-1;acid precipitation lignin E = 178.94kJ/mol,lnA =23.88min-1;alkali lignin E =169.27 kJ/mol, lnA =25.63min-1.The order of the activation energy from small to large and the pyrolysis reaction from easy to difficult is sulfonated lignin,alkali lignin, acid precipitation lignin.With ligin as substrate and acetic anhydride as acetylating reagent,lignin modification experiments using liquid-phase. This paper explores the best of lignin acetylation process condition for short reaction time, high yield, low production cost, and evaluatesthe overall performance of acetylated lignin. The results show that: both lignin acetylation for best effects that the actual amount: theoretical amount is 3: 1, reaction temperature is 90℃, reaction time is 3h. The acetylation conversion gradually increased with the elevation of reaction temperature and reaction time, after reaching the highest point it’s in the fall. The acetylation conversion of sulfonated lignin and alkali ligin can reach to 47.71% and 53.56%.In addition, IR spectra of the acetylated lignin indicated that the amount of hydroxy group significantly reduced, while the intensity of acyl group characteristic absorption peak largely increased, which was in accordance with excellent acetylation results for lignin acetylation process. The test of scanning electron microscopy showed that the structure of the lignin change from the original ball to cube and gather into a ball, showed that acetylation is better; After the test of oil absorption, acetylated lignin performance improvement.The higher acetylation conversation, the better acetylation effect, the acetyl group substituted with more hydroxyl group, the better hydrophobic and higher oil-absorbing amount. These show that the above properties of acetylated lignin had been improved significantly. |
