Study On Catalysic Hydrolysis Of Lignocelluloses By Heteropoly Acids

Widespread use of lignocelluloses raw materials and cheap corn stalk biomass fuels instead of food production, is not only the research focus on the process of biomass conversion, but also has great significance and broad market prospects for the economic development of our country. In this paper, the cellulose was obtained firstly through the pretreatment of the corn stalk, and then cellulose hydrolysis has been studies using HPA catalyst as to get glucose. The catalyst and as-obtained produces were characterized by XRD, FTIR, SEM and HPLC techniques. The main results are summarized as follows:As the cellulose are tightly encapsulated by lignin and hemicellulose, the effect of direct hydrolysis is not very satisfactory. Thereforce, the pretreatment of corn stalk was deal with formic acid in our experiment. The results showed that:the hemicellulose was hydrolyzed quickly, most of the lignin was dissolved in the solution, and the cellulose, hemicellulose and lignin were extracted form the corn stalk.Solid acid catalysts were prepared H3PW12O40/SBA-15, H3PW12O40/SiO2H3 and H3PW12O40/Al2O3. The hydrolysis of cellulose over various catalysts was investigated in order to obtain glucose. As shown in our study, the main products of cellulose hydrolysis over these catalysts are glucose, fructose formic acid, levulinate and 5-hydroxymethylfurfural (5-HMF). The H3PW12O40/SBA-15 catalyst shows better stability of hydrolysis of cellulose and better selectivity of glucose the cellulose compared with other catalysts. The conversion of cellulose, glucose selectivity, and yield of glucose at 170℃for 40 h was 11.66,48.3% and 5.62%, respectively. Effects of reaction temperature were studied to get higher substrate conversions and product selectivity of glucose.The cellulose hydrolysis over HPA catalysts (H3PW12O40, H4SiW12O40, H6P2W18O60, TBA-y-SiW10 and acidification TBA-γ-SiW10) were investigated under hydrothermal condition. The effect of temperature, reaction time and catalyst amount were determined by HPLC. The results showed that the cellulose conversions was reached 26.52%, selectivity of glucose reached 55.97% and yield of glucose was 14.48% over H4SiW12O40 for 25 h at 180℃.