Degradation Of Several Biomass And Lignin Model With CO₂ Supercritical

Lignin whose structure is far more complex than cellulose is second only to cellulose in biomass as natural polymers and is not fully rational use of renewable resources.It is great significance for the full utilization of renewable resources of various sources of lignin in different environment.This paper studied the degradation lignin,such as sesame straw,and β-O-4 lignin model polymer,via A technology of CO₂ supercritical fluid.The main contents in this paper were as follows:（1）The content of lignin and Cellulose was evaluated through orthogonal experiments via Van Soest method.The results showed that thetemperature is the most important effect on the degradation andremoval behavior of lignin.At a temperature of 200℃,pressures 20 Mpa,added 1.5 ml entrainer（1,4-dioxane）reaction 60 min,delignification rate can reach 80.84%.At the same time using GC-MS of supercritical CO₂ extraction fluid composition was analyzed under different conditions.With the temperature rise will also lead to other carbohydrates,the degradation of cellulose and hemicellulose to generate phenolic,dioxolane ring material.Using scanning electron microscope（SEM）to compare the extraction before and after the supercritical extraction.The results showed that there were many pores and amorpHous substance on the surface of the sample after supercritical treatment,which may be the residual lignin or lignin-carbohydrate complex.（2）The lignin model compounds of hydroxyl-phenyl（H）,guaiacyl（G）and acetosyringone was synthesized,4-hydroxyacetophenone and acetovanillone as initiator.The characterization methods of 1H-NMR and 13C-NMR,IR spectra were used to analysis and confirme the structure of the intermediate products and the target polymer.（3）The supercritical CO₂ fluid extraction technology was used to study the degradation of β-O-4 high-poly lignin model compounds.The extraction and degradation of guaiacyl and hydroxyl-phenyl lignin model compounds were carriedout under supercritical conditions of 160℃,24 Mpa,90min;180℃,24 Mpa,90min and 200℃,24 Mpa,90min respectively.Collect extracts for GC-MS analysis,ethers were no found,it shows that the aryl ether bond has broken before 160℃,With the increase of temperature,polycyclic aromatic hydrocarbons are gradually increasing.（4）The model molecule of acetosyringone was optimized and simulated by molecular quantum chemistry methods of computer simulations in Guassian 03 to analysis and calculate the theoretical value of the different chemical bonds.