The Study On Preparation Of Levulinic Acid By High Pressure-Acid Hydrolysis

Levulinic acid has superior physical and chemical property and could take place estenfy,substituted, condensation and neutralization reaction, so it was potential to be a new basedcompound. It can be obtained by catalytic hydrolysis of furfuralcohol, cellulose,monosaccharide and polysaccharide. The research hotspot was using material with abundantstart and cellulose to prepare levulinic acid. This paper used sodium hydroxide to extractpolyxylose from the straw, and then studied the method of high-pressure and acid hydrolysis toproduce levulinic acid.Sodium hydroxide extracted the straw. It investigated the influence of sodium hydroxidecondensation, reaction temperature, solid-liquid ratio, extract time and extract temperature onthe field of polyxylose in the single factor experiment. The results showed the optimizationcondition: when the sodium hydroxide condensation was 10%, the solid-liquid ratio was 1:10,the extract time was 3h and the extract temperature was 80℃and the field of polyxylose was13.71%. Most substances except cellulose were eliminated and the residue was cellulose withthe content 78.37%, fitting to prepare the levulinic acid.Using the method of high-pressure and acid hydrolysis to prepare levulinic acid from thestraw pretreated by sodium hydroxide and concluded the reaction degree by detecting thecontent of sugar. The influences of the reaction temperature, reaction time, acid concentrationand solid-liquid ratio were investigated in the single factor experiment. The better hydrolysiscondition at the 1.6MPa pressure were reaction temperature 170℃, reaction time 60min,solid-liquid ratio 1:10, acid concentration 5% and the field of levulinic was high as 24.33%.When the pressure was 1.6MPa, the reaction time was 30rain, the acid concentration was 3%,the solid-liquid was 1:20, the reaction temperature was 130℃, the glucose from cellulosehydrolysis can be entirely degradation. The infrared spectrogram showed the main componentof the residue was lignin.Extracting and refining levulinic acid from the hydrolysis liquid. It investigated theintluences of secoctyl alcohol, aether, ethyl acetate on the field of levulinic acid and got theoptimization condition. The extract liquid was distilled by vacuum distillation and froze to getlevulinic acid. The structure of the product was confirmed by FTIR and the purity of the crystalwas determined by HPLC. The results showed ethyl acetate to extract levulinic acid was betterand got the optimization condition: the time was 10min, the extractant-hydrolysis liquid ratiowas 3:1. the extraction temperature was 30℃, extraction time was 3 and the extraction field ofthe levulinic acid was 85.3%. The purity of the product was 97.31% determined by HPLC.