Preparation Of Bifunctional Nanocatalysts And Study On Catalytic Hydrodeoxidation Of Biomass-derivatives

In order to solve the increasingly severe energy crisis and environmental pollution caused by the extensive use of fossil energy,it is urgent to develop sustainable green energy.Renewable biomass has the advantages of abundant reserves,wide distribution and renewable,and the conversion of biomass resources into biofuels and high value-added chemicals has attracted much attention.Vanillin and 5-hydroxymethylfurfural(HMF)are important biomass-based model and platform molecules,which can be converted into a variety of high value-added chemicals and liquid fuels.Because of its high oxygen content,it cannot be used as liquid fuel directly.Selective hydrodeoxygenation(HDO)is an effective way to realize its low oxygen content and high value utilization.Efficient HDO catalyst is the key to achieve selective hydrodeoxidation.In this paper,three kinds of highly dispersed metal-acid bifocals were designed and prepared,in which the active metal site was used to activate hydrogen species,and the acid site was used to promote the C=O bond fracture.The active metal site was used to catalyze the HDO reaction between vanillin and 5-hydroxymethylfurfural,and outstanding catalytic activity and selectivity were obtained.1.The metal-acid bifunctional catalyst Pd-PTA/ZrO2 was obtained by anchoring atomically dispersed Pd with phosphotungstic acid(PTA)modified ZrO2 as the support,which has good catalytic performance for the hydrodeoxidation of lignin derivatives under mild conditions.Vanillin can be efficiently converted to 2-methoxy-4-methylphenol at 1 atm H2 and 80℃ for 90 min,and its catalytic activity is better than most reported catalysts.Its outstanding catalytic activity can be attributed to its large specific surface area,moderate acid strength,synergistic action of active metal and ZrO2 support.2.Anchoring highly dispersed Co onto Ce modified hydroxyapatite(HAP(Ce)),a highly efficient bifunctional catalyst Co/HAP(Ce)was prepared.Co/HAP(Ce)showed excellent catalytic activity for the conversion of HMF to 2,5-dimethylfuran(DMF).At 150℃ and 2 MPa H2 for 5 h,the conversion rate of HMF was up to 99%,and the selectivity of DMF was up to 96%.The synergistic effect between Co and HAP(Ce)was investigated by XRD,TPD,TEM and XPS.It was found that appropriate Ce addition could introduce more acidic sites and enhance the metal-supporter interaction,thus promoting the hydrodeoxidation of HMF.Density functional theory calculation shows that Co/HAP(Ce)is more likely to activate H2.3.The Co/CePO4 bifunctional catalyst was prepared by loading cobalt nanoparticles on CePO4 by precipitation deposition method,and its catalytic performance for selective hydrogenation of HMF to prepare DMF was investigated.It was found that acidic sites and dispersed metal sites could promote the hydrolysis of HMF.Under the optimized reaction conditions(180℃,1.5MPa H2 for 3 h),the DMF yield could reach 99%.