Study On Hydrolysis Of Cellulose In Supercritical Water For Reducing Sugar

Cellulose is the most abundant biological polysaccharide that all plants and algae have. It exits in municipal solid wastes and agricultural resources, namely biomass resource. With the exhausted of fossil fuels, the development of effective utilization processes of biomass and cellulose has been expected as one of the promissing methods that can solve a food problem caused by the rapid increase in the population worldwide and the energy problem from a lack of fossil fuels.The key of producing bioethanol from lignocelluloses is how to obtain fermentable sugars effectively by hydrolysis of cellulose.Technologies of lignocellulose hydrolysis remain still to be researched. A detailed research of hydrolysis of cellulose for reducing sugar was carried out, which will benefit the utilization of biomass for fuelethanol.First of all, hydrolysis and saccharification of microcrystalline cellulose in supercritical water were focused in this paper. The effect of reaction time, temperature, supercritical water density and solid-to-liquid ratio on saccharification was discussed to determine the optimum of reaction parameters. The yield of reducing sugar was tested by 3,5-Dinitrosalicylic Acid (DNS) method. The distribution of sugar components and other products in the liquid products was analyzed by HPLC. The experiment results showed that there exits hexose, 5-HMF, glyceraldehydes in hydrolysis product, and the contents of degradation products increased constantly with the time being. Furthermore, PH Value of hydrolysates were determined, it showed that there were organic acids in hydrolysates. There were a large number of micro particles and seldom even nano-scale in residue observed by Electron Microscopy (SEM).In order to obtain reducing sugar from biomass which rich in cellulose,we used rice stems, microcrystalline cellulose, absorbent cotton, filter paper and purification rice stems as raw materials, supercritical hydrolysis were carried out respectively in intermittence reaction equipment. The effects of reaction time on hydrolysis of a variety of materials in supercritical fluid was studied and compared with each others. The yield of reducing sugar was tested by 3,5-Dinitrosalicylic Acid (DNS) method. The different hydrolysis processes of different raw materials were analysised.Refer to cellulose hydrolysis model in literaturs, considered the property of cellulose, the process of experiment were simulated by homogeneous consecutive reaction model. The experimental data of cellulose hydrolysis was consonant with the model not very well. We analysed these errors.