Electrocatalytic Oxidation Of 5-hydroxymethylfurfural To 2,5-furandicarboxylic Acid And Maleic Acid

Biomass is a rich and renewable source of chemicals.5-Hydroxymethylfurfural（HMF）is a biomass-based platform compound derived from lignocellulose,and its oxidation products 2,5-Furandicarboxylic acid（FDCA）and Maleic acid（MA）are important high value-added chemicals.Electrocatalytic oxidation is an effective method for converting HMF.Under alkaline conditions,nickel-based catalysts can convert HMF to FDCA with high selectivity,but at present,there are problems such as high onset oxidation potential of HMF,harsh preparation conditions,poor scale and versatility.Under acidic conditions,HMF can be converted to MA,but catalysts have been reported to be unsatisfactory in terms of catalytic activity and selectivity.In response to the above problems,the following research is carried out in this paper:1.Ultra-thin porous Ni（OH）₂ nanosheets（Ni（OH）₂/CB）loaded with carbon black（CB）were prepared by acetylacetonate salinization at room temperature and pressure.In 1 M KOH+10 m M HMF,Ni（OH）₂/CB showed good catalytic activity and selectivity,and the HMF conversion rate and FDCA yield could reach 100%and98.1%,respectively.Further,a self-supporting Ni（OH）₂ electrode was prepared using the above method using three-dimensional porous carbon felt and nickel foam as the substrate,which was used for anode of the anion exchange membrane electrolytic cell.The electrolyzer can continuously electrolyze HMF for up to 80 hours,and the relative FDCA content remains at 80-100%.The performance of the catalyst and electrode after scale-up was investigated,which proved that the acetylacetonate salinization method had the potential to prepare Ni（OH）₂ on a large scale.In addition,nickel-cobalt bimetallic hydroxides with HMF initiation oxidation potential lower than Ni（OH）₂ were prepared by this method,and exhibited higher FDCA yields at low potentials.2.MnO_x,SnO_x and Pb₂O₃ were prepared by electrodeposition using carbon paper（ACP）as the substrate,and applied to HMF electrocatalytic oxidation under acidic conditions.The results showed that the main product of MnO_x oxidation of HMF was maleic acid（MA）,but the final yield was less than 40%;SnO_x catalyzes the conversion of HMF to MA and fumaric acid,but the yield of both is less than 30%;The yield of Pb₂O₃ oxidized HMF to MA can reach 60%.Furthermore,Pb₂O₃ was prepared by electrodeposition using titanium mesh as the substrate,and the HMF conversion rate and MA yield could reach 100%and 94.2%,respectively.By reducing the concentration of acid,the Pb dissolution of Pb₂O₃ can be reduced,and after three cycles,the MA yield decreases by 17%.