Synthesis Of 2,5-diformylfuran From Fructose By Heterogeneous Catalysts

Molybdovanadophsophoric heteropolyacids supported on mesoporous silica and Co contained ceramics(Co-ceramics)were synthesized to catalyze the reaction from fructose to 2,5-diformyfuran(2,5-DFF).Reaction conditions were optimized based on the two catalysts.(1)A Kegin structure molybdovanadophosphoric heteropolyacids(PMoV-HPAs)was developed to be a catalyst for one-pot synthesis of 2,5-DFF form fructose with oxygen as the oxidant under environmentally benign conditions.Mesoporous silica was prepared to be the carrier.The TEM map and other characterizations showed that the PMoV-HPAs was successfully supported on mesoporous silica.Using DMSO as the solvent of the reaction,the optimal reaction temperature was 120? and the best mass ratio of catalyst/fructose/DMSO was 1:10:100.In order to prevent the existence of humins,the first hour of the reaction was protected by nitrogen under atmospheric pressure,and the acidic site(H)offered by the PMoV-HPAs promoted the dehydration of fructose to 5-hydroxymethylfurfural(HMF).During the next three hours,the metallic site(V)catalyzed the aerobic oxidation of HMF to 2,5-DFF under atmospheric pressure of oxygen.Maximum yield of 2,5-DFF was 48.4%.When investigating the recyclability of the catalyst,H4PMo11VO40/SiO2 was observed to be reusable for 5 cycles without significant loss in activity,and it can achieve the best activity after impregnated again.Maximum yield of 2,5-DFF was 74.8% when the reactant was HMF.(2)Co-Ceramics catalyst was developed to be the catalyst for the reaction of fructose-to-2,5-DFF.XRD patten showed the structure of ceramic was successfully formed.Using DMSO as the solvent of reaction and under the optimal temperature of 100?,the yield of 2,5-DFF was achieved to 44.6% after 6 hours reaction(one hour nitrogen and five hours oxygen).Co content was a complex factor to the activity of the catalyst.The activity increased when more Co was put into the Co-ceramics,but with the Co content increased,the ceramics structure became more fragile.After optimization,the best Co content was determined.Co-ceramics catalyst can be reused 9 times without significant loss in activity.Before used again,the Co-ceramics should be treated by ultrasonic waves and be washed by acids to remove the humins that were deposited on the surface of the Co-ceramics.The activity slightly decreased after used 10 times because of the inevitable loss in every treatment.