Study On The Conversion Of Starch To Pentahydroxymethyl Furfural Catalyzed By Tin Phosphate Tungstate

Biomass has the advantages of wide source,low price and renewable.Its efficient conversion and utilization is one of the effective ways to solve the increasingly serious energy crisis.5-hydroxymethyl furfural?5-HMF?is an important platform compound,which can be converted into liquid fuel and high value-added chemicals.High-efficiency catalytic conversion of biomass to 5-HMF is a new technology to replace traditional fossil fuels.Catalyst is the key factor affecting the conversion of biomass to 5-HMF.Aiming at the problem of high-efficiency conversion of biomass,a new phosphotungstic acid was designed and synthesized.?HPAs?catalyst was used to investigate the effect of HPAs,on the conversion of starch,a selective agent of target product,by catalytic hydrolysis of cassava starch to 5-HMF,in order to obtain new catalysts for directional conversion of controlled substances.1.Keggin heteropoly acid Sn_xH_3-4xPW₁₂O₄₀?X=0.1,0.2,0.3,0.4,0.5,0.75?catalysts were prepared by partial substitution of metal ions for hydrogen ions.The catalysts were characterized by elemental analysis,X-ray diffraction and infrared spectroscopy.The effects of substitution of metal ions on the acid strength and capacity of the catalyst were investigated.The conversion and selectivity of cassava starch to 5-HMF under various reaction conditions such as reaction time,reaction temperature,catalyst concentration and substrate concentration were discussed.The results showed that the optimum conditions for catalytic conversion of cassava starch to 5-HMF were as follows:reaction temperature 160C,reaction time 1 h,catalyst dosage 0.1 mmol,starch mass 0.2 g,starch conversion rate 83%,selectivity and yield of 5-HMF 74.5%and 61.8%,respectively.Under the optimum conditions,the effect of Sn_xH_3-4xPW₁₂O₄₀?X=0.1,0.2,0.3,0.4,0.5,0.75?as catalyst on the yield of 5-HMF was discussed.The results showed that Sn_0.1H_2.6PW₁₂O₄₀ had the best catalytic effect on the conversion of 5-HMF.2.Sn_0.1H_2.6PW₁₂O₄₀ was loaded on the metal skeleton MIL-101 to synthesize a new catalyst.The catalyst was characterized by N₂ adsorption,acid-base titration,X-ray diffraction and infrared spectroscopy.The effects of catalyst loading and reusable times on the yield of 5-HMF were investigated.The results showed that the higher the loading rate was,the better the catalytic effect was.Sn_0.1H_2.6PW₁₂O₄₀@MIL-101 was prepared by one-step method.When the loading rate was 47%,the catalytic efficiency could reach 33.4%.The catalyst was characterized by X-ray diffraction and infrared spectroscopy.The results showed that the structure of the catalyst remained unchanged after five reuses.