Study On Dehydration Of Sugars Into 5-hydroxymethylfurfural Catalyzed By Phosphates In Aqueous Solutions

With the development of economy in the world,the need for fossil fuels have been increasing rapidly,and the burning of fossil fuels have polluted the environment we live and emitted amounts of carbon dioxide which play an important role in greenhouse effect.However,biomass is kind of new energy whose storage is big,which can be recycled and has almost no pollution.So biomass maybe plays an important role in providing man with fuels and chemicals in the future.Most biomass exists in the form of sugars which are synthesized through photosynthesis and its energy comes from sun,so plants biomass has the advantage of infinition.Among the biomass cellulose has the biggest storage.Cellulose is a kind of polymer compound which is polymerized through the dehydration of glucose.Research on the dehydration of sugars into chemicals will contribute to the solution of energy crisis in the future.In this article,we mainly research on the dehydration of fructose into intermediate 5-hydroxymethylfurfural(HMF)catalyzed by the phosphate catalysts.In this article,we start from the chose and preparation,and through different procedures research on the catalysis effect of phosphate.There are two kinds of phosphate catalysts: one phosphate is prepared through directly adding two original chemicals into the solution,and it is kind of white gel;the other type of catalyst's preparation goes through distillation,washing and dry in vacuum again with the catalyst above and this type of catalyst has less water.Moreover,we also checked the effect of valence number of tin,the type of phosphate and the molar ratio of Sn/PO4 on the yield of HMF of the dehydration.Above these,the dehydration of sucrose,glucose into HMF was also checked.Through these experiments,we can find that tin phosphate catalyst has the high activity of dehydration with the HMF yield 43 %,and the reaction condition is such: reaction temperature,reaction time and the optimal catalyst loading are 135 ?,1 h,65 % proportion of DMSO.In addition to this,from the change of HM yield as the temperature,we see that hydrogen phosphate catalyst protected the stability of HMF in some degree.And the HMD yield of glucose dehydration is low,because the isomeration of glucose into fructose normally work in the basic catalyst,and phosphate catalyst just work as the acid catalyst.As shown when solid ZrPO and SnPO was used as catalyst,the activity of these catalysts were much higher than in situ generated catalysts,reaching the HMF yield 52 % and 82 %,and we can see that the best condition: ZrPO: reaction temperature,155 ?,time 7 h,and DMSO proportion 90 %,and SnPO: reaction temperature,135 ?,time 5 h,and DMSO proportion 50 %.