Study On Conversion Of Monosaccharide To 5-HMF

5-hydroxymethylfurfural (5-HMF), which can be obtained from monosaccharide, is believed to be a very important bio-chemical raw material. Early studies showed that 5-HMF can be obtained from monosacchride using liquid acids as catalysts. There are many shortages in this pathway, such as drawbacks in separation and recycling and equipment corrosion. In this article, ionic liquids, salts of phosphotungstic acid were prepared; the process of monosacchride to 5-HMF by ionic liquids, phosphotungstic acid as catalysts was studied. The influences of some factors such as solvent, reaction time and temperature, heating methods have been investigated.Three kinds of ionic liquids ([BMIM]Cl, [BMIM]Br, [EMIM]Br) and six kinds of salts of phosphotungstic acid (CePW12O40, Cs2.5PW12O40, Mi1.5PW12O40, Cu1.5PW12O40, Zn1.5PW12O40, BiPW12O40) were first synthesized. The structures of catalysts were characterised by FT-IR and XRD. The results showed that the salts of phosphoyungsic acid have the structure of Keggin, which is feature structure of phosphoyungsic acid. The reaction of monosaccharide to 5-HMF catalyzed by salts of phosphotungstic acid and the influences of reaction conditions to the yield of 5-HMF were investigated. The result showed:(1) In series of salts of solid acid catalysts, the catalytic performance of Cs2.5PW12O40 and CePW12O40 are better than the others. (2) It was advantageous for high yield of 5-HMF to increase reaction temperature, or to prolonging reaction time; high concentration of reactant and catalyst can make side reaction increase and low selectivity. (3) Under the conditions (CePW12O40 as catalyst,140℃,10% (wt%) of reactant concentration, DMSO as solvent), the yield of 5-HMF was 98.44%. (4) Compared with conventional heating, microwave heating had remarkable effect on accelerating reaction rate and improving the yield of 5-HMF.The reaction of monosaccharide to 5-HMF catalyzed by ionic liquids was investigated. The result showed:(1) Compared with the yield of 5-HMF catalysted by three kind of ionic liquids, [BMIM]Cl>[BMIM]Br>[EMIM]Br. (2) In various kinds of metal chlorides, CuCl2 is better than the others; we can have the high yield of 5-HMF by addition of inorganic acids additive; (3) Side effects were inhibited by addition of organic solvents, such as DMSO; (4) It was advantageous for high yield of 5-HMF to prolonging reaction time, suitable reaction temperature and reantants concentration are also important; (5) Under the conditions ([BMIM]Cl as catalyst,2-butanol as organic solvent (8g), MIBK (8g) and DMSO (2.75g) were also acceded, HCl as inorganic acids additive (0.5g), R is 6.4,140℃,2 hours), the yield of 5-HMF was 32.54%.