Study On The High-value Conversion Of Furfural And Glucose Catalyzed By PdAg/CDs Catalys

In recent decades,the conversion of biomass feedstocks into platform molecules has attracted interest because it is one of the most promising methods for preparing and producing chemicals and biofuels.Furfural and glucose are important biomass derived compounds,which can generate high value-added chemicals through catalytic hydrogenation/hydrogenolysis.Therefore,the development of catalysts with specific catalytic activity plays an important role in the catalytic hydrogenation/hydrogenolysis of furfural and glucose.In this thesis,a novel carbon dots（CDs）material was prepared as a carrier and reducing agent,and a PdAg/CDs composite catalyst was developed for furfural hydrogenation and glucose hydrogenolysis,and the activity and product distribution of the catalyst were studied,which provided a scientific basis for the catalytic high-value conversion of bimetallic carbon dots composite catalyst in biomass-derived compounds.Firstly,using glucose as the carbon source,CDs were prepared by microwave method,and the optimal microwave reaction conditions were obtained by designing orthogonal experiments with a power of 700 W,a reaction time of 15 min20 s,and a yield of 7.7%.The characterization results show that there are a large number of functional groups such as carboxyl,amino and hydroxyl groups on the surface of the prepared CDs,and the shape is spherical and the particle size distribution is uniform.Secondly,PdAg/CDs composite catalysts with three metal molar ratios（1:1,1:2 and1:4）were prepared by reducing Pd²⁺and Ag⁺by photoillumination using the CDs prepared above as carriers and reducing agents.The results show that under 365 nm ultraviolet light,the carbon dots prepared from glucose have strong reducibility,and Ag⁺and Pd²⁺can be reduced to nanometal elements,and the carbon dots constitute a PdAg/CDs composite catalyst.The characteristics were characterized and analyzed by TEM,EDS,XRD,XPS,FT-IR and other methods,and the particle size of PdAg/CDs composite catalyst was mainly distributed between 5～15 nm,and the Pd and Ag mainly existed in the form of 0-valence alloys,loaded on the surface of carbon dots.In addition,in the preparation of PdAg/CDs composite catalysts,the functional groups（C=O,O-H and N-H）on the surface of CDs play an important role in the reduction of Pd²⁺and Ag⁺.Finally,this thesis explores the reaction law of PdAg/CDs composite catalyst catalyzed furfural hydrogenation and glucose hydrogenolysis.The results showed that when the catalyst catalyzed furfural hydrogenation,the main products were cyclopentanone,furfuryl alcohol and tetrahydrofurfuryl alcohol.Under the mass ratio of Pd₁Ag₂/CDs composite catalyst to furfural of 1:5,30 m L H₂O and stirring speed of 500 r/min,the optimal reaction conditions were 2 MPa H₂,the reaction temperature was 200°C,and the reaction time was 4 h,the conversion rate of furfural reached 100%,and the yield and selectivity of cyclopentanone were 93.26%.The results of glucose hydrogenolysis catalyzed by Pd₁Ag₁/CDs composite catalyst showed that under the conditions of 100 mg glucose,25mg catalyst,30 m L H₂O,4 MPa H₂,reaction temperature of 140°C and reaction time of 3h,the catalyst showed good hydrogenolysis activity,the conversion rate of glucose was68.85%,and the yield of the hydrogenolysis product acetol reached 8.36%,and the selectivity was 12.14%.