Study On The New Process Of 5-HMF Preparation By The Dehydration Of Fructose

As one of the most important platform compounds,5-hydroxymethylfurfural?5-HMF?is a key raw material for the preparation of the 2,5-furan dicarboxylic acid?FDCA?which is the essential monomer of biodegradable polyester.Preparation of 5-HMF from hexose and pentose has been extensively studied.Fructose is one of the most selected raw materials as its low cost,easily availability and favorable dehydration.At present,the acid-catalytic dehydration of fructose to 5-HMF is the typical way,the catalysts used included organic acid,inorganic acid,ionic liquid,solid acid and other catalyst systems.However,these systems have some practical problems,such as low selectivity to target products,corrosion of equipment,complex preparation process and high cost of catalysts,and difficulty in separating products from catalysts.Based on the concept of environment-friendly process,and aiming at to improve the fructose selectivity and product yield,this paper designed and proceeded fructose dehydration by deep eutectic solvent?DES?and pressurized CO₂ in bi-phase solvent system,And the influence of process parameters on the yield and selectivity of target product was discussed in detail,and the mechanism of reaction process was suggested.The main research contents and conclusions are as follows:1.Deep eutectic solvent was developed to the dehydration of fructose in H₂O/methyl isobutyl ketone?MIBK?biphasic solvent system.At the optimal conditions of T=140?,t=180min,DES=4.0g,the ratio of choline chloride to sulfamic acid was 1:0.1,MIBK:water=35:5?mL?,the optimal yield of 5-HMF was 90.44%,and the conversion rate of fructose reached 100%.The experimental results show that the efficiency of DES catalytic system is greatly affected by the reaction temperature.2.A new process was developed to prepare 5-HMF by efficient dehydration of fructose in H₂O/methyl isobutyl ketone?MIBK?biphasic solvent system with pressurized CO₂.Under the conditions of t=20min,T=200?,P_CO2=3.0MPa,MIBK:water=10:1,the yield and selectivity of 5-HMF was 85.6%and 89.1%,respectively.It was found that fructose concentration and solvent ratio were the key factors to determine the yield of the target product.The mechanism of reaction process is proposed.3.Compared with the results reported in related literature,these two processes had better 5-HMF yield and higher selectivity,which could be used as potential methods for large-scale production of 5-HMF from fructose.