The Research On Conversion Of Fructose To5-hydroxymethylfurfural Over Ionic Liquids And Heteropoly Acid

With the rapid consumption of non-renewable resource, the renewable biomass resources, particularly lignocellulosics biomass having received more attention in producing chemicals. Lignocellulose can be converted to bulk chemicals by a hydrolysis reacetion. During hydrolysis, the lignocellulose is cleaved to give monosaccharide, which still can be decomposed into useful chemicals. The results of many researches have showed that the first step(lignocellulose-monosaccharide)was a crucial step and had substantial impact on the selectivity and yield of chemical product. Therefore in this thesis we have carried out the following research work with a view to green low carbon.In this study,1-butyl-3-methylimidazolium chloride (BmimCl),1-(3-sulfonic acid) propylpyridinium hydrogen sulfate ([PSPy][HSO4]),1-(3-sulfonic acid) propylpyridinium toluenesulfonate ([PSPy][TSA]),1-(3-sulfonic acid) propylpyridinium dihydrogen phosphate ([PSPy][H2PO4]), were synthesized and characterized by H-NMR. The acidity of the pyridinium ionic liquids was detected by Hammett method. The synthesis of5-hyroxymethylfurfural (5-HMF) from frutose in BmimCl over pyridinium acid functionalized ionic liquids catalyst, with DMSO as co-solvent. The influence of the concentration of fructose, reaction temperature, reaction time, the amount of catalyst, the amount of additive and the lifetime of catalytic were studied on the yield of5-HMF. The catalytic activity of pyridinium ionic liquids is relevant to their acidity. It is not conducive to the formation of the product with large or too small acidic. The5-HMF yield of88%can be achieved at100℃for120min on60mg catalyst. Catalyst still retain higher activity after being recycled for7times.Heteropoly catalyst was focused on the synthesis of5-hyroxymethylfurfural (5-HMF) from frutose in in N,N-dimethylacetamid. The influence of the different heteropolyacid, the calcination temperature, the concentration of fructose, reaction temperature, reaction time, the amount of catalyst and additive were studied on the yield of5-HMF. The optimum preparation conditions were selected by orthogonal design. The results show that phosphotungstic acid has the best catalytic activity when the calcination temperature is175℃. The5-HMF yield of82%can be achieved at120℃for120min on80mg catalyst. Among them, the temperature is the most important factor for the yield of5-HMF.In order to retrieve heteropoly, HaPW12O40SiO2was prepared with the method of impregnation. The amount of the loaded phosphotungstic acid and the lifetime of catalytic were studied on the yield of5-HMF. The infrared spectrum(IR), X-ray diffraction(XRD), and NH3-TPD were introduced into the structure characterization and the acidity characterization of the supported heteropoly acid. The results show that5-HMF yield of84%can be achieved when the amount of the loaded phosphotungstic acid reach40%. Supported phosphotungstic acid is still a Keggin-type structure, while the strength and quantity of acid of the loaded phosphotungstic acid were less than that of the unloaded.