Degradation Of Glucose To 5-HMF In Biphasic System By Phosphotungstic Acidified Solid Acid Catalyst

It is acknowledged that biomass fuels and platform compounds have emerged as promising alternatives to fossil fuels.Because they can be made from biomass-rich,renewable,carbon neutral and low-pollution biomass resources.5-Hydroxymethylfurfural(5-HMF)is listed as the top value-added bio-based chemicals by the US Department of Energy because of its reactive chemical property.And it is considered to be converted to a variety of value-added compounds.Therefore,the research play an important role in the preparation of 5-HMF from the cheapest and the most abundant monosaccharide glucose.It is found that the catalytic activity of phosphotungstic acid with acid and redox is favorable in the acidification and dehydration reactions.And solid acids are used widely in acid-catalyzed reactions because of its adjustable acidity,good thermal stability,high recycling rate,environment-friendly and other advantages.However,there is a disadvantage that dissolution easily of phosphotungstic acid.In order to overcome the shortcoming,phosphotungstic acid was supported or doped on the surface of the dioxide.In this paper,5-HMF was prepared in saturated NaCl(aq)/THF biphasic system.The main contents are as follows:1.A series supported solid acid catalysts of phosphotungstic acid H3PW12O40(HPA)/TiO2-ZrO2 were synthesized by a method of coprecipitation and equal volume impregnation,the catalytic activity on the degradation of glucose to 5-HMF was investigated.The optimum catalyst was selected as follows:molar ratio of titanium to zirconium was 5:5,calcination temperature of the carrier was 600℃,HPA loading was 5%(mass fraction).The well interaction between HPA and TiO2-ZrO2(TZ)was demonstrated by FT-IR,XRD,XPS and TEM.Reasonable explanation of the effect of acidity and acid density on this reaction by BET and NH3-TPD.At the same time,many factors were investigated on the catalytic performance.The results showed that the optimum reaction conditions were t=4 h,T=160℃,m催:m 葡＝1:5,VNaCl(aq):VTHF=1:5,1200 r/min.Under the optimum conditions,the yield of 5-HMF was 51.3%,the selectivity of 5-HMF was 54.9%and the glucose conversion was 93.4%.In addition,the catalyst circulation experiments showed good thermal stability of the catalyst.2.The doped solid acid catalysts of phosphotungstic acid H3PW12O40(PW12)-TiO2-SiO2 were synthesized by a hydrothermal method.The catalytic activity of the catalyst was evaluated.It was found that the catalyst had the best performance when the molar ratio of titanium to silicon was 9:1 and the doping content of PW12 was 0.006(molar ratio).The well interaction between PW12 and TiO2-SiO2(TS)was demonstrated by FT-IR,XRD and XPS.Reasonable explanation of the effect of acidity and acid density on this reaction by BET and NH3-TPD.At the same time,many factors were investigated on the catalytic performance.The results showed that the optimum reaction conditions were t=3 h,T=160℃,w 催:m葡=1:5,VNaCl(aq):VTHF=1:5,1200 r/min.Under the optimum conditions,the yield of 5-HMF was 57.7%,the selectivity of 5-HMF was 58.5%and the glucose conversion was 98.6%.In addition,the catalyst cycling test showed good thermal stability of the catalyst.