Study On The Depolymerization Characteristics Of Ethanol Organosolv Lignin In Sub-and Subperitical Ethanol

In recent years,efficient conversion of lignin to bio-based fuels and chemicals to replace petrochemical products has aroused widespread concern.In this paper,the bamboo as raw material,by changing the dissolution conditions,the dissolution of the EOL obtained were analyzed at the same time using micro-high temperature and high pressure reactor under supercritical ethanol,EOL depolymerization experiments to study the different dissolution conditions EOL depolymerization characteristics,in order to provide a new theoretical idea for the depolymerization of EOL macromolecular structure preparation of monophenol chemical products.The experimental results show that the dissolution temperature and the acid catalyst have the greatest effect on the yield of EOL and the yield of solid residues,with the values of 39.57% and 59.93%,respectively.The lower temperature is not conducive to the dissolution of EOL,while the excessively high temperature will,to a certain extent On the promotion of EOL depolymerization,the final impact of EOL yield.For EOL depolymerization,the liquid phase yield is higher for supercritical(240 ? / 7.5 MPa)depolymerization EOL than for subcritical(180 ? / 3.2 MPa).Under the condition of supercritical conditions,the rate of depolymerization is higher than that under subcritical conditions.When the milling time is prolonged and depolymerization proceeds under supercritical conditions,the rate of depolymerization increases first with the extension of milling time.After the change of alcohol-water ratio,EOL had the highest depolymerization rate under sub-supercritical conditions.The change of dissolution time had little effect on the depolymerization rate of EOL.The depolymerization rate of EOL-19 had the lowest effect,reaching 43.47 %,and the lowest residual char yield was observed.The solidification product of EOL-9 under supercritical conditions showed the lowest residual char yield of 17.57%.The highest yield of liquid product reached 72.77%.For the depolymerization liquid phase product analysis,it was found that the main component of the EOL-8 depolymerization liquid phase product in the sub / supercritical(180 /240 ?)phenols was 70.00%.In particular,the most important component of the product of depolymerization in the supercritical(240 ?/ 7.5 MPa)condition is 3-hydroxy-4-methoxybenzaldehyde with a relative content of 16.60%;at subcritical(180 ?/ 3.2 MPa)The main components of depolymerization liquid products phenols were 61.01%,the main ingredient is 2,6-dimethoxyphenol,the relative content of 15.57%.EOL-2 in sub / supercritical ethanol depolymerization liquid phase products mainly composed of phenol and p-ethyl phenol.EOL obtained by changing the content of Pd/ C catalyst,the main components of liquid phase depolymerization in supercritical ethanol environment are 4-ethyl-2-methoxyphenol and vinyl guaiacol.Among them,the three EOL depolymerization products relative content there is a big difference.EOL-9 in the supercritical ethanol depolymerization liquid phase products mainly composed of 4-ethylphenol,2,6-dimethoxyphenol,3-hydroxy-4-methoxybenzaldehyde,4-hydroxy-Methoxy-benzoate,4-hydroxy-3-methoxyphenylacetic acid and the like.