The Structure-activity Study Of Pd-Ni Bimetal And MnCe Composite Oxide Catalyzed Selective Oxidation Of 5-hydroxymethylfurfural To 2,5-furandimaldehyde

The widespread use of non-renewable fossil energy such as oil,coal,and natural gas has made great contributions to the rapid development of human economy and society.However,due to its non-renewability and the huge environmental pollution during use,researchers have turned their attention to Cleaner biomass energy.As an important biomass platform compound,5-hydroxymethylfurfural（5-HMF）can produce a series of high value-added chemical products through reaction.2,5-Diformyl furan（DFF）,as its oxidation product,can be used in the synthesis of medicines,antifungal agents,organic conductors,luminous bodies,electronic optical devices,etc.,and has broad application prospects.In this paper,two kinds of catalysts have been developed to address the problems of Low atomic utilization of precious metal catalysts,easy deactivation and poor activity of non-noble metal catalysts in the reaction of preparing DFF from 5-HMF,and harsh conditions for catalytic reactions.Two catalysts have been developed,including Pd and Ni prepared by hydrothermal method.Double single atom catalyst and Mn,Ce metal oxide catalyst prepared by co-precipitation method.Through XPS,XRD,HRTEM,O₂-TPD and other characterization methods,the morphological and structural characteristics of the catalyst were studied,and combined with its catalytic performance,a structure-activity relationship was constructed.Pd and Ni double single-atom catalysts were synthesized by hydrothermal method.Doping an appropriate amount of Ni in the Pd-Mn O₂ catalyst can generate more oxygen-rich vacancies in order to adsorb and activate oxygen molecules.At the same time,the high dispersion of Pd and Ni on the carrier improves the atom utilization rate and facilitates the adsorption of the reactants.Using Pd₁Ni_0.15-Mn O₂ at 120 ^oC and an oxygen pressure of 1.5 MPa for 1 hour can completely convert HMF and obtain a DFF yield of>99%.After 10 repeated experiments,the activity of the catalyst did not decrease significantly;Mn-Ce metal oxide catalyst was synthesized by precipitation method.The Mn CeO_x catalyst has a high specific surface area of114.5 m²/g,which can effectively increase the contact area with the reactants.At the same time,the coexistence of Ce⁴⁺and Ce³⁺as well as Mn⁴⁺and Mn³⁺in the Mn CeO_x catalyst facilitates the electron transfer during the redox reaction,and the abundant oxygen vacancies generated by a large number of Mn³⁺on the surface all contribute to the selective oxidation of HMF to DFF.In addition,the activation energy of Mn-Ce metal oxides prepared by co-precipitation method to catalyze HMF selective oxidation to synthesize DFF is lower than the activation energy value prepared by hydrothermal method,and the reaction rate is higher than that prepared by hydrothermal method.After reacting at 120 ^oC and 1.5 MPa O₂ for 2 hours,a DFF yield of 94%can be obtained,and the catalytic activity did not decrease significantly after 5cycles of experiments.