The Degradation Of Carbohydrate To 5-hydroxymethylfurfural Over Solid Acid Microspheres

The utilization of biomass resources is an important research field for catalysis and energy science.Cellulose,as main ingredients of biomass,is a hotspot of current research which can be used to produced platform compounds.At present,the traditional degradation of biomass by acid catalysts to produce 5-HMF is the most widely used in industrial.5-HMF as an important chemical precursor,molecular structure contains various active group,which can be converted into a variety of medical-polymer and fuel alternatives through oxidation,hydrogenation.In recent years,most of studies have shown that biomass degradation depends on the acid catalyst,especially the isomerization and dehydration of carbohydrate in the process of degradation.As the new type of green low pollution acid catalyst,solid acid has been widely studied.This work mainly describe that the composite oxide solid acid Ti/Al/Si(TASO)microspheres and the acid resin microspheres(SMF).It can be mainly divided into two parts in the following:1.A series of different element ratios of Ti/Al/Si microspheres(TASO)solid acid catalyst were synthesized by the sol-gel method,the performance of catalysts on the conversion of glucose into 5-HMF was investigated.The effects of catalysts and possible mechanism were analyzed.Catalyst phy-chemical properties have been characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscope(SEM)and transmission electron microscopy(TEM),etc..Surface acidity of solid acid was obtained by the NH3-TPD.The acid type of the catalyst would be gotten by Pyridine adsorption IR(Py-IR)and In situ infrared(In-situ IR).In the conversion progress of glucose into 5-HMF,reaction temperature,water content and catalyst element ratio were investigated.The yield of ca.73%can reach when the TASO as catalyst,m catalyst/m glucose ?1:5,under 423 K,3 h reaction time in the degradation experimental.Characterization data indicated that the surface acid density of TASO-343 is 0.71 ?mol/m2.Lewis acid sites may lead to isomerization of glucose into fructose,Bronsted acid promote molecular dehydration in decomposition process.2.With melamine and formaldehyde as raw material,the solid acid melamine resins(SMF-TiO2)were synthesized by Mannich reaction,sulfonic acid treatment and crosslinking TiO2 on the surface.Using thermogravimetric analysis(TG)and Fourier transform infrared(FT-IR)spectrum,the chemical group of resin microspheres was analyzed.And the resin surface micro-structure was displayed by scanning electron microscope(SEM).In the degradation of cellulose into 5-HMF,the efficiency of catalyst was analyzed in the single ionic liquid phase system and bi-phase system.In addition,experiment investigated the effects of reaction temperature,water content on the yield.In the single-phase system,chloride-1-butyl-3-methylimidazole([BMIM]C1)as solvent,m SMF-TiO2/m cellulose =1:5,4 h under 453 K,the yield of 5-HMF can reach 21%.The research showed that the catalytic efficiency of SMF-TiO2 is obviously better compared with SMF.It is found that organic phase can greatly improve the the yield of 5-HMF.