Hydrothermal Conversion of Biomass to 5-HMF.

摘要

With more concerns on the depletion of fossil energy and greenhouse gas emission, the production of renewable energy and value-added chemicals from biomass has been attracting worldwide research interest. 5-hydroxymethyl furfural (5-HMF) is a promising and polyfuntional chemical derived from renewable biomass from which alkane bio-oil, as well as other important industrial chemicals can be produced.;The primary results showed that the use of phosphate buffer solutions greatly improved the 5-HMF yields from glucose and cellulose. The highest 5-HMF yield from glucose reached 92%, while the 5-HMF yields from glucose, using HCl and H2SO4 solution, were only 60% and 80%, respectively. When cellulose was used as feedstock, the highest 5-HMF yield was also obtained by using phosphate solutions. The 5-HMF yield followed this order: 35% (phosphate solution) >25% (H2SO4) > 20% (HCl). Although the highest yield of 5-HMF from grass was only 3.4%, the 5-HMF yields in the presence of phosphate solutions increased by 40% when compared with those produced using HCl and H2SO4. Furthermore, the amount of produced 5-HMF in phosphate buffer solutions was stable with time. The 5-HMF yields did not significantly decreas as it was stored at room temperatures or at 4°C for 21 days.;In addition, it was found that when phosphate solutions were used, the formation of levulinic acid from 5-HMF was greatly inhibited. The levulinic acid yields were only 1.5% and 2.0%, as the highest yields of 5-HMF were produced from glucose and cellulose. These results confirmed that the improvement on the 5-HMF yields from biomass by phosphate buffer solutions were mainly attributed to the inhibition of the rehydration of 5-HMF to levulinic acid. Therefore, the results of this thesis research conclude that phosphate buffer solutions are promising reaction media of not only increasing 5-HMF yields from biomass but also improving the purity of 5-HMF.;In my work, acidic phosphate buffer solutions, instead of mineral acids such as HCl and H2SO4, were used to prevent the increase in the acidity of reaction media during conversion such that 5-HMF yield and purity can improve. Glucose, cellulose and grass were served as feedstock to produce 5-HMF.