Study On The Performance And Mechanism Of Electrocatalytic Oxidation Of 5-hydroxymethylfurfural Over Transition Metal Catalyst

The electrochemical conversion of biomass into biofuels and high-value-added chemicals is an important direction for the future development of the chemical industry and has great potential.5-hydroxymethylfurfural（HMF）,with its molecular structure containing furan rings,-C=O and-OH groups,is a common biomass platform molecule and is known as the"sleeping giant".The oxidation product of HMF,2,5furandicarboxylic acid（FDCA）,is an important precursor for the synthesis of poly（furane carboxylate）（PEF）,a promising alternative to the petroleum derivative poly（ethylene terephthalate）（PET）.The electrocatalytic preparation of2,5-furandicarboxylic acid（FDCA）from 5-hydroxymethylfurfural has attracted much attention from researchers.Currently,the electrocatalytic oxidation of HMF is mainly focused on the study of non-precious metal catalysts,especially nickel-based metal catalysts,so this project investigated the performance of its HMF oxidation reaction based on the preparation of nickel-based catalysts using a simple in situ synthesis method and studied its reaction mechanism in depth;meanwhile,The MOF-derived non-precious metal nickel-based electrocatalysts are also a hot research topic at present.In this project,the reaction system is extended to Ni-Co bimetallic catalysts on the basis of Ni-based metal catalysts,and the performance of HMF oxidation reaction is attempted to be regulated by modulating the bimetallic catalysts.The main elements are as follows:（1）In this thesis,a nickel-based catalyst NF_a was synthesized using a simple in situ method and applied to the HMF electrocatalytic oxidation reaction（HMF Oxidation Reaction,HMFOR）.The catalytic activity remained stable for five consecutive electrolytic cycles.The mechanism of the reaction was further investigated,and HRTEM and XPS characterization revealed that NF_a first undergoes surface reformation to produce Ni（OH）₂ under alkaline conditions,and in situ EIS and quasi-in situ Raman revealed that Ni（OH）₂ further forms the real active species Ni OOH under the applied external voltage,which further oxidizes with HMF to produce FDCA.It was also found that the dynamic cyclic evolution of Ni（OH）₂to Ni OOH during the HMFOR process allows for the continuous high performance conversion of HMF.（2）The paper synthesizes Co_xNi_y-MOF nanomaterials with different metal ratios by hydrothermal method and then synthesizes bimetallic sulfide Co_xNi_yS catalysts by high temperature calcination method to investigate their application in the electrocatalytic oxidation of HMF.The results showed that the electrochemical oxidation performance of Co_xNi_yS for HMF showed a volcano curve with increasing the ratio of Co during the long time HMFOR.When Co:Ni=2:1,the conversion of HMF reached 84.5%and the yield of the main product FDCA was 54%.Co₂Ni S has a considerable specific surface area,which can provide more reaction sites for HMFOR,and the detection of species valence changes on the catalyst surface after electrolysis using the XPS technique revealed the presence of high-valent nickel species,further demonstrating the Ni OOH presence and activity,and that Co and Ni synergize each other to promote HMF conversion.