Preparation Of MOF-derived Alloy Nanoparticles And Their Catalytic Performance For CO₂ Hydrogenation

It is well known that 80% of the greenhouse gases in the atmosphere consist of CO₂.Therefore,reducing CO₂ is essential for sustainable development.CO₂ hydrogenation can produce a variety of chemicals,including hydrocarbons,higher alcohols and liquid fuels.Metal-organic frameworks have shined in the field of catalysis due to their outstanding properties.Derivatives based on metal-organic framework precursors have been favored by researchers.Among them,metal al oy nanoparticles,especially high-entropy al oys,exhibit unique properties due to their variable composition that can tune the electronic structure of the material and the adsorption force with species.Therefore,based on the metal-organic framework,a series of alloy catalysts were derived in this thesis and applied to the catalytic hydrogenation of CO2.1)Based on metal-organic frameworks rich in Fe,Co,Ni and other components,a series of transition metal nanoparticles were prepared,and the catalysts were characterized by XRD,SEM,TEM and other characterization methods,and the different metal components and Influence of different ligands on CO₂ hydrogenation reduction performance.XRD and SEM&TEM confirmed that the MOFs precursors were carbonized at elevated temperature to form the al oy structure of nanoparticles,and all series of catalysts showed good catalytic activity at 500°C:single metal Ni-MOF had 78.52%CO₂ at 350°C High conversion and close to 100%CH₄ selectivity;the bimetallic Ni Co-MOFs formed by the addition of Co exhibit excel ent CO₂ hydrogenation performance compared to the other two bimetallic MOFs,and the CO₂ conversion at 350°C is 61.6%,CH₄ selectivity is also close to 100%;trimeta llic Ni₄Co₄Fe₂-MOFs are good materials for obtaining advanced products,the selectivity of C ₂H₆is close to 10%,and the selectivity of CH₃OH is also close to 5%.2)Based on metal-organic frameworks containing five or more metals,high-entropy alloy nanoparticles were prepared by high-temperature pyrolysis.The materials were characterized by means of XRD,SEM and TEM.Since the outer layer of the synthesized particles is covered with a layer of carbon,the catalytic hydrogenation performance of CO₂ is not ideal,but this provides a new theoretical support for the preparation of MOFs alloy derivatives and high-entropy al oy nanoparticles.3)Based on metal-organic frameworks containing five or more metals,ultrafine high-entropy al oy nanoparticles were prepared by a low-temperature and fast plasma treatment method.The materials were characterized by XRD,SEM and TEM,and it was confirmed that the MOF decomposed metal remixing under the treatment of argon plasma.Represented by five-membered Fe Co Ni Cu Ru,its CO₂ conversion at 350°C reaches the maximum of 70.41%,and the CH₄ selectivity is close to 100%.Change.