Cobalt-based Oxide Synthesized With Small Molecule Intercalation And Its Selective Oxidation Performance Of Benzyl Alcohol

Cobalt oxide has redox and semiconductor properties,and is widely used in catalytic fields such as catalytic oxidation,photocatalysis and electrocatalysis.However,improving the pore structure of cobalt oxide has become an important challenge for researchers.In the process of catalytic reaction,the open pore structure and high specific surface can promote the diffusion of reactant molecules and expose more active sites,thereby improving the reaction activity of the catalyst.The template method is used to synthesize porous transition metal oxides,but the metal oxides are easy to sinter when the template is removed,resulting in the pore structure collapses and the nanoparticles agglomerate.In order to solve the problem,this work attempts to use volatile small molecules to intercalate and control the morphology of metal oxides,and cobalt oxide is synthesized by solid-phase method,and cobalt-aluminum spinel is synthesized by reconstruction method.This research studies the effects of different modifiers on the surface properties of the catalysts,the formation mechanism of the pore structure,and the structure-activity relationship between the surface properties and the selective oxidation performance of benzyl alcohol.First of all,this subject adopts the solid-phase method to intercalate the modifier into the Co₃O₄ lattice to synthesize the precursor,which is decomposed to obtain Co₃O₄ after calcination.The specific surface of Co₃O₄ is doubled compared to commercial alumina.On the basis of the similar pore structure,the selective oxidation performance of benzyl alcohol was compared from Co₃O₄ synthesized with different modifiers.XPS analysis shows that the surface of Co₃O₄modified by ammonium carbonate with abundant Co³⁺species content and surface active oxygen has the best selective oxidation performance of benzyl alcohol.Co₃O₄ synthesized by different small molecules has the problem of excessive oxidation or insufficient oxidation ability,and has poor thermal stability.In order to solve the above problems,Co was loaded on the AACH whose crystals were destroyed by high temperature by the memory effect of basic aluminum ammonium carbonate by the reconstruction method.The Co clusters will be confined inside the crystal defects,and form a supported catalyst with strong metal-support interaction after calcination.The oxidation capacity of the catalyst is adjusted by adjusting the metal loading,so as to obtain a new type of catalyst with adjustable oxidation capacity.By adjusting the metal-support interaction,the conversion rate of benzyl alcohol and the selectivity of benzaldehyde were adjusted,and the yield of benzaldehyde was increased to62.0%.Therefore,this thesis is devoted to synthesizing cobalt oxide with large pore volume and high surface area,and studying the influences of the morphology and pore structure of the catalyst on its reaction performance.Porous cobalt oxide is prepared by intercalation of small molecules,which solved the problem of pore structure collapse and particle agglomeration during template removal and firing.This method can also be extended to other metal oxides（such as Mg,V,Ni,Fe,Mo,etc.）,providing a new strategy for the synthesis of porous metal oxides.