Utilization Of Lignin

In this paper,we researched the dissolution,regeneration,cracking and micro process of lignin in[Emim]Br,which is a kind of ionic liquid,and we also studied the preparation of lignin derivatives-acyl compounds and sulfonated sustances.Firstly,the dissolution of lignin in[Emim]Br was studied,and the effects of dissolution temperature,ratio of solid to liquid and dissolution time on the dissolution rate were investigated respectively.The range of process parameters was inquiried through single factor experiment,and then we choose several main parameters to conduct orthogonal experiment and get suitable process conditions:the dissolution temperature was 130?,the ratio of solid to liquid was 1:10 and the dissolution time was 3h.The experimental results showed that the dissolution rate of lignin was stable at 37.67%.By FT-IR analysis,the stretching vibration peak of hydrogen bonds between the molecular chains of the regenerated lignin was transferred from 3397cm-1 to 3431cm-1,and the absorption peak of hydrogen bond was blue shifted,that is to say,it moved 34cm-1 to high frequency.FT-IR and XRD analysis showed that the structure of lignin before and after regeneration had not changed,which indicated that the dissolution of lignin in ionic liquid was physical dissolution,and was in line with EDA theory.Secondly,the study of lignin derivatives' preparation was conducted.Acyl compound was prepared with raw materials of lignin ionic liquid and glacial acetic acid.The effects of reaction time,temperature and liquid to solid ratio on the formation of acyl compound was explored,and the contact angle of the generated acyl compound was measured.Through orthogonal test,the best experimental conditions were as follows:the reaction temperature was 120?,the reaction time was 2h,the ratio of lignin and ice acetic acid was 1:7.Repeated experiment showed that the yield was stable at 67%,and the contact angle was 105°,larger than 90°,which indicated that the hydrophobic group existed in the structure of acyl compound.And the change of C=O could be seen from the FT-IR spectra.The experimental results showed that this method could be used to prepare acylate of lignin.The preparation of lignin sulfonate was with lignin and sulfuric acid.The effects of reaction time,sulfuric acid concentration and dosage on the sulfonation of lignin was investigated.The optimized experimental conditions was obtained through orthogonal experiments:grinding time was 50 min,concentration of sulfuric acid was 18.4mol/L,solid to liquid ratio is 1:2.25.According to FT-IR analysis,the infrared spectrum of the lignin sulfonate we prepared was basically consistent with that of the infrared spectrum of purchased sodium lignin sulfonate;and the properties of the lignin sulfonate were preliminarily analyzed.Then,the better experimental conditions of the dissociation of lignin in ionic liquid were cracking temperature of 260? and cracking time of 3h through the research of pintsch process of lignin.The effects of KCl,MgCl2,ZnCl2 and other alkali metal on the lignin cracking were studied.GC-MS and FT-IR analysis showed that the main ingredients of pyrolysis oil obtained by cracking of lignin in ionic liquids were ketones,phenols,alcohols and other oxygenated compounds.Finally was the study of the fine of lignin.Through the single factor experiment,with the index of lignin content in filtrate using membrane with the aperture of 220nm,we explored the optimum conditions of lignin micronized in ionic liquid,and concluded that the dispersion agent was 3‰,mass ratio of ionic liquid and dispersion medium was 1:7,static set time was 24h,dispersion time was 30min and dispersion temperature was 80?.Through observation by optical microscope,the size of the most micronized lignin was about 10 ?m.