Research On The Dehydration Of Fructose To5-hydroxymethyl Furfural Catalyzed By The Sn/Ge Based Solid Acids

With the continuous depletion of fossil resources and more and more seriousenvironmental pollution, it gradually becomes a hot topic to use the cheap and renewablebiomass resources as raw material to produce chemicals. As the common carbohydratebiomass, fructose can be employed to generate5-hydroxymethylfurfural (5-HMF) viacatalytic dehydration, which is then transformed into polyester monomer, additives andpharmaceutical intermediates, etc. Therefore, the dehydration of fructose to synthesize5-HMF has important scientific significance and application value.In this paper, we prepared four tin-based solid acid catalysts: DZ-1, DZ-2, DZ-05andDZ-03by coprecipitation method, and they were employed to promote the dehydration offructose. It is found that DZ-05is the best catalyst; Further more, through the study of thecalcined, uncalcined, and sulfated DZ-05catalyst, the SDZ-05catalyst is considered veryefficient: for example, the yield of5-HMF can reach75%under120℃,2.5h in DMSO; then,the influence of reaction temperature, time was investigated, and the optimum reactionconditions is100min,150℃. From repeated use of the DZ-05and SDZ-05, it can be seenthat these catalyst are very stable in the dehydration process. We also inversitigated thephysical properties of the catalysts, in which the performance and characteristics of thecatalysts were respectively characterized using BET, XRD, SEM, TEM and TG techniques.In addition, the catalytic activity of the metal germanium of solid acid was also tested inthe dehydration of fructose. When GeO2or Ge3N4is used as the catalyst for the fructosedehydration, a48%or42%yield of HMF is respectively obtained in DMSO solvent.However, the conversion of sucrose is poor. Then the combination of these two materialsunder different time and temperature was researched in the dehydraiton reaction. The obtainedresults showed that the dehydration of fructose could be greatly improved when the dualcatalyst of GeO2and Ge3N4in the ratio of1:1is added into the reaction, and the5-HMF yieldreached61%from the dehydration of fructose in DMSO; meanwhile, the yield of5-HMF was35%from the dehydration of sucrose. The investigations indicated that the yield arrived at66%in the fructose dehydration with the sulfated GeO2as the catalyst.