| The dwindling fossil resources have drawn human attention to renewable energy derived from biomass resources.Lignocellulosic is one of the most abundant non-food biomass resource in nature.As its main component,cellulose is considered to be a substitute for fossil resources due to wide sources.Pathways for catalytic conversion of cellulose into ethylene glycol（EG）and 1,2-propylene glycol（1,2-PG）has drawn particular attention due to its high atomic economy and large demand of the products.As high-value chemicals in polymer synthesis such as polyesters and antifreeze,EG and 1,2-PG are widely applied in food,pharmaceutical,plastics and other industries.Metal-organic frameworks（MOFs）are a class of crystalline porous materials,constructed by alternately connecting metal ions or small metal clusters with organic ligands in a 3D porous structure.They are widely used in the field of catalysis.On the one hand,due to the unique characteristics of large surface area and adjustable pore structure,MOFs are used as supports for catalysts.On the other hand,carbon nanomaterials can be obtained by sacrificial template method,which converts metal ions in MOFs into metal nanoparticles or metal nano oxides,and is highly dispersed or embedded in the carbon matrix.In this thesis,MIL-100（Fe）,a MOF material with a 3D mesoporous structure and high loading capacity,is used and modified with phosphotungstic acid（PTA）as a support or precursor for catalytic materials.Using nickel as the active site in the reaction,a series of nickel catalysts based on MOFs were synthesized through two different routes and used in the catalytic conversion of cellulose to EG and 1,2-PG.By systematically examining the influence of preparation process and reaction conditions on the reaction results,the catalytic effect was optimized,and the following results were obtained:（1）By hydrothermal method,a series of phosphotungstic acid-doped MIL-100（Fe）（denoted as PTA/MIL-100（Fe））was synthesized directly in a fluorine-free environment,and its structure,composition,and physical and chemical properties were analyzed and investigated.（2）Using PTA/MIL-100（Fe）as the support and nickel formate as the nickel source,the Ni-PTA/MIL-100（Fe）catalyst was synthesized by the self-decomposition reaction of nickel formate by low temperature calcination after impregnation.By adjusting the ratio of the amount of metal to acid and the reaction conditions,under 245°C and 4 MPa hydrogen pressure for 1hour,the cellulose is completely degraded,and the EG yield is 22.70%,1,2-PG yield is 29.43%.（3）Using nickel nitrate as a nickel source,supported on PTA/MIL-100（Fe）as a catalyst precursor by solution impregnation,and using high temperature calcination method to synthesize Ni-Fe WO4/C catalyst.The catalyst preparation process is adjusted by adjusting the loading of metal and acid,calcination temperature,etc.,and the reaction conditions are adjusted to optimize the catalytic effect.The reaction was carried out at 245°C under a hydrogen pressure of 4 MPa for 2 hours.The cellulose added was completely degraded,and a yield of19.07%ethylene glycol and 24.43%1,2-PG could be obtained.In addition,the reusability of the catalyst was tested to verify that the catalyst can still maintain a high activity after four consecutive uses.While achieving high yields,the catalytic scheme has the advantages of facile material synthesis,low cost,and recoverable catalyst,and has industry application prospects. |
