| CO is a product of incomplete combustion of fossil fuels.It is a colorless,tasteless and irritating toxic and harmful gas.It is the most widely distributed pollutant in the atmosphere.Therefore,the elimination of CO has become a problem that people pay more and more attention to.At present,the main method to eliminate CO is catalytic oxidation.The key to the realization of catalytic oxidation is to develop a high performance catalyst for catalytic oxidation of CO.As a kind of non noble metal catalyst,Co3O4 has become one of the hot topics in the study of CO catalytic oxidation.Co3O4 has high catalytic activity and is considered to be the most potential non precious metal catalyst.For CO catalysts,the factors such as particle size and distribution,crystallinity,pore structure,specific surface area and dispersity of catalysts have great influence on their properties,and the preparation of materials is one of the key factors that affect these catalysts.In recent years,metal organic frameworks?MOFs?have been developed as precursors to prepare metal oxides and composite metal oxides.Therefore,in this article,metal formate frameworks?MFFs?were used as precursors to prepare Co3O4 with different morphologies and their catalytic properties were studied.Firstly,we have demonstrated a novel method that employs metal-formate frameworks as precursors to prepare Co3O4 catalysts.Metal-formate frameworks[CH3NH3][Co?HCOO?3]and[?CH3?2NH2][Co?HCOO?3]were prepared at room temperature with cobalt nitrate as metal ion and formic acid as ligand,methylamine and dimethylamine as templates,respectively.The Co3O4-MA and Co3O4-DMA were obtained by calcining[CH3NH3][Co?HCOO?3]and[?CH3?2NH2][Co?HCOO?3],respectively.The CO catalytic oxidation performance of Co3O4-MA and Co3O4-DMA was studied.The two catalysts completely achieved transformation of CO at 170oC and showed excellent reaction stability.The as-synthesized Co3O4–MA and Co3O4–DMA,with a porous cubic structure,displayed potential in applications in the environmental protection.Secondly,uniform microcubes of[CH3NH3][Co?HCOO?3]were synthesized by a modified method using C2H5OH as the solvent and reducing the concentration of the reactants.A series of core-shell nanostructure MFF@Co?OH?2 microboxes and hollow Co?OH?2-H were successfully obtained through a reaction between the MFF template and sodium hydroxide?NaOH?combined with different washing processes.Finally,hollow and core-shell nanostructure Co3O4 products were obtained after calcination,which inherited the structures from corresponding precursors.The formation mechanism for hollow and core-shell structures and the catalytic performance of Co3O4 products were studied.Thirdly,preparation of nano-sized[CH3NH3][Co?HCOO?3]and[CH3NH3][Co0.8Cu0.2?HCOO?3]by nonaqueous microemulsionmethod.The nonaqueous microemulsion was composed of methanol as polar phase,n-octane as oil phase,and AEO3 as surfactant.Then nano-sized Co3O4 and Co3O4-Cu obtained by calcinating nano-sized[CH3NH3][Co?HCOO?3]and[CH3NH3][Co0.8Cu0.2?HCOO?3].The two catalysts completely achieved transformation of CO at 130oC. |
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