Production Of Small Molecular Organic Acids By Open-system Degradation Of Cellulose In It' Homogeneous Solution At Low Temperature

In recent decades, as we all know, the serious energy crisis, environment pollution and greenhouse effect have gained more and more attention with the expansion of the demand for energy and chemicals. Therefore, the conversion of biomass is becoming increasingly attractive as renewable feedstock for the production of chemicals and fuels. Cellulose is the most abundant renewable biomass, and which can be converted to the value-added fuels and platform molecules such as sorbitol, formic acid, lactic acid, levulinic acid and 5-hydroxymethyl furfural. And cellulose is a water-insoluble polymer, which is composed of ?-D-glucopyranose linked by ?-1,4-glycosidic bonds. Most of the cellulose degradation reactions are heterogeneous under high temperature and high pressure because of its insolubility. Therefore, the Chapter 1 of the thesis not only describes the structure and properties of cellulose, but also reviews the dissolution of cellulose and the preparation of small molecule organic acids from cellulose. At the same time, the structure, properties and applications of glucose is also briefly sketched. In order to overcome the high energy consumption problem brought by the cellulose degradation reaction under high temperature and high pressure, we conceived a new method to degrade cellulose in its homogeneous solution to organic acids under open system with low temperature via the two-step method. In this scheme, our experiment is mainly divided into two chapters.In Chapter 2, we introduce production of small molecular organic acids by open-system degradation of cellulose at low temperature. In this part of the experiment, cellulose was dissolved in sodium hydroxide solution by a freezing-thawing process and the homogeneous aqueous solution of cellulose are obtained. And then the well-dispersed cellulose chains were degraded to intermediates, for instance low molecular weight sugars, aldehyde and acid at mild temperature, which were finally oxidized to formic acid and oxalic acid by H2O2 as only oxidant at low temperature. It is noteworthy that two steps are all conducted under the open system. Through the study of the effect of the reaction time, reaction temperature and amount of H2O2, the optimal conditions were obtained:the homogeneous cellulose was reacted at 110? for 3 h and then reacted with H2O2 at 50? for 4 h, and the yield of organic acids were 32.8%(formic acid),11.6%(lactic acid) and 2.3% (lactic acid).In Chapter 3, we introduce production of formic acid, lactic acid by open-system degradation of glucose at low temperature. Inspired by the experiment in the last chapter, we also designed the open-system catalytic conversion of glucose to lactic acid and formic acid at low temperature via two-step method. The optimum condition of the yield of lactic acid was acquired by study of the effect of reaction temperature, reaction time and NaOH amount in in the first-step pretreatment reaction. The optimum condition of the yield of formic acid was determined by the study of the effect of reaction temperature, reaction time and H2O2 amount in in the second-step oxidation reaction. Finally, the optimum conditions were as follows:0.15 g glucose in 4.8 g 5.26wt%NaOH solution was reacted under 100? for 5 min and then reacted with H2O2 at 50? for 4 h, and the maximum yield of lactic acid(75.1%) and formic acid(15.2%) were achieved. The experiment in Chapter 3 can be classified as the supplement and extension of the second chapter. We believe this new strategy can be applied in other conversion of sugarsThe last chapter is the summary of this experimental research. The content, results and research significance of the experiment are briefly summarized, the advantage and innovation points of the experiment are also introduced, and the unsolved problems and the insufficiency of the experiment are finally described in Chapter 4. In summary, the open-system degradation of carbohydrate, which produced small molecular organic acids via two-step method, effectively solved the high energy consumption problems from such reactions under high temperature and high pressure.