Study On The Preparation Of 5-[(formyloxy)methyl]furfural And Its Catalytic Conversion

As an important renewable resource,biomass has the property of completely replacing petrochemical resources to produce chemicals and enormous potential applications in energy,chemical and pharmaceutical.The conversion of biomass through platform molecules to high value-added chemicals is the key point for efficient utilization of the biomass resource,which has become the focus of current research at home and abroad.In this thesis,fructose was taken as the raw material and the chemical catalytic transformation was used as the main research method.5-[(formyloxy)methyl]furfural(FMF),a novel platform compound,was prepared from fructose and its catalytic conversion to 2,5-dimethylfuran(DMF)were also carried out and some satisfied results were achieved.Firstly,FMF was produced from fructose by one-pot conversion in pure formic acid media.When the reaction was carried out without catalyst in the pure formic acid solvent(140 ?,2 h),the conversion rate of fructose and yield of FMF can be reached with 100%and 43.9%,respectively.An in-situ extraction reaction system of fructose/choline chloride(ChCl)deep eutectic solvents(DES)was established and a two-step preparation of FMF through HMF and following esterification with formic acid was developed.A favorable FMF yield of 63.2%was reached by two-step process.In addition,the effects of reaction parameters,such as temperature and acidity,on preparing FMF from fructose were systematically investigated.The dehydration of fructose to HMF was confirmed as the reaction controlling step.To make the produced HMF stable in reaction system was the key question for the efficient preparation of FMF.The two-step preparation was more conducive to the formation of HMF and can effectively improve the yield of FMF.Secondly,based on the characteristics of the target FMF and reaction pathway,a separation and purification method for the FMF products was developed,and the stability of FMF was studied.In order to separate and purify the target product FMF effectively,the processes including extraction,vacuum distillation and washing are combined.The purified FMF is a pale-yellow liquid and has a purity of more than 98%through the GC detection.Moreover,the molecular structure of the target product was confirmed by the 1H NMR and 13C NMR methods.This study provides a complete technical approach about the preparation of FMF from fructose,the purification and purification of FMFNext,Ni-Cu/SBA-15 bimetallic supported catalysts were prepared by incipient wetness impregnation using molecular sieve SBA-15 as carrier and Ni and Cu as active metals.The catalytic transfer hydrogenation/hydrogenolysis of FMF to DMF over Ni-Cu bimetallic catalyst with formic acid as hydrogen donor was carried out.The catalysts were also deeply characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),BET analysis,and H2 temperature-programmed reduction(H2-TPR).The results showed that a Ni-Cu alloy was formed during the preparation of the bimetallic catalyst,and the metal is uniformly distributed on the carrier SBA-15 in the form of particles.The effect of two series of Ni-Cu/SBA-15 catalysts with different Cu/Ni ratio and different total metal contents and recaction conditions on catalyst activity were studied.In addition,the 36Ni-12Cu/SBA-15 catalyst showed high activity and excellent recyclability in the conversion of FMF to DMF that a favorable FMF conversion rate of 100%and DMF yield of 71.0%were obtained at 220 ? for 5 h under self-generated pressure,and the DMF yield remined favorable after reused six times.Finally,the conversion mechanism of FMF transfer hydrogenation into DMF was proposed that formic acid was first decomposed to produce active hydrogen by the copper-nickel-supported catalyst,and catalyzes the cleavage of the formyloxy group of FMF to form a methyl-generating intermediate compound 5-MF through transfer hydrogenation.Then 5-MF was hydrogenated into 5-MFA,following deoxygenated into DMF.The hydrolysis and esterification balance between FMF and HMF existed in the solution,and 5-MF and 5-MFA were the intermediates during the conversion of HMF into DMF.In the process of catalytic transfer hydrogenation,copper and nickel played a significant synergistic role.Both Cu and Ni had the ability to decompose formic acid to produce hydrogen and the unique ability to dimethoxy and hydrogenation of formyl group.Moreover,Cu almost could not achieve dehydroxylation,while Ni had the ability to hydrodeformyloxy and dehydroxylation.The synergistic role between Cu and Ni in different step enhanced the selectivity of DMF from FMF,which was more advantageous than HMF.At the same time,FMF has a furan ring,a formyl group,and a formyloxy group.Compared to HMF,the substitution of hydroxyl group results in a change in the physical properties of the FMF.FMF is more hydrophobic than HMF and less polar.In addition,FMF has a higher thermal stability and a lower boiling point that make the separation easier and more stable.Thus,FMF exhibits the excellent potential as a platform molecule.