A Study On Conversion Of Fructose And Glucose To5-Hydroxymethylfurfural In Ionic Liquids

Biomass is a kind of renewable resources which can be converted into liquid fuel and chemicals.5-Hydroxymethylfurfural (5-HMF) obtained from carbohydrates (such as fructose and glucose) is a new and "green" versatile intermediate. However, the conversion of fructose and glucose to5-HMF often involves environmentally unfriendly solvents, such as strong acid and organic solvents. To solve the problems, environmentally benign solvents, ionic liquids (ILs) and supercritical carbon dioxide (scCO2), were taken into consideration according to their unique properties, and they were used to convert fructose and glucose to5-HMF.This thesis has studied the conversion of fructose and glucose to5-HMF in different ionic liquids. And the effect of reaction temperature, reaction time, types of ILs, types of catalyst, reaction atmosphere and microwave (MW) treatment on the conversion and the yield have been studied. Furthermore, separation of5-HMF from ILs is one of the main obstacles that restrict applications of the technology. In this work, we attempted to use scCO2to separate5-HMF from ILs. The solubilities of5-HMF in scCO2are important data in developing the separation process, so we have studed them in this work. The conclusions are drawn as followes:1. Fructose and glucose can be converted into5-HMF efficiently in ILs-metal choride, the highest conversion of fructose and glucose is100%, and the highest yield of5-HMF is91%. There is synergistic interaction between ILs and catalysts. The reaction temperature has great effect on the conversion and the yield, and there is an optimum temperature between70to160℃for different IL and catalyst systems. The yield of5-HMF increases with increasing time at the beginning, and then keeps a constant value. Among the catalysts used, CuCl2-2H2O shows the greatest effect on the conversion of fructose to5-HMF, and CrCl3-6H2O expresses a greatest effect on the conversion of glucose.2. Protonated titanium nanotubes (PTN) were synthesized by a hydrothermal reaction, yielding PTN of about10nm in outer diameter,8nm in inner diameter, and200nm in length. Glucose can be converted into5-HMF in ILs-PTN. To enhance the reaction rate, MW was used, which could reduce the reaction time to less than1min. The power of MW can effect the yield of5-HMF greatly, and the highest yield is abtained when the power is400W.3. The solubility of5-HMF in scCO2with cosolvent ethanol of (0,0.025, and0.050) mole fractions at temperatures of (314.10,323.98,333.76and343.20) K and pressures ranging from (8.54to19.71) MPa has been measured. The solubility of5-HMF in scCO2increases with the increase of pressure but decreases with the increase of temperature. Besides, the solubility of5-HMF in scCO2with cosolvent ethanol increases with the ethanol mole fraction at fixed temperatures and pressures. Furthermore, the experimental data can be correlated using the Chrastil model and the modified Chrastil model with ARDs less than7.9%. The association of5-HMF and CO2is an endothermic process, and ethanol can reduce the energy of the process. The results demonstrate that5-HMF can dissolve in scCO2, which provide value information for the scCO2extraction of5-HMF.