Study On Catalytic Oxidation Of Formaldehyde By Silver-based Supported Catalysts

Formaldehyde?HCHO?,which is widely used in construction and decorative materials,is regarded as one of the main air pollutants in the house.Long-term exposure can cause harm to the human body,and it can induce diseases such as leukemia and nasopharyngeal cancer.It is urgent to control formaldehyde.The catalytic oxidation method with mild reaction conditions,low cost,stable operation and no secondary pollution is the most promising methods for formaldehyde purification.The low-temperature reduction performance of the catalyst in the catalytic oxidation of formaldehyde technology,the surface active oxygen species and the price directly affect the promotion of the catalyst,and the silver-based supported catalyst with low cost and excellent catalytic activity has attracted much attention.In this thesis,the carrier of CeO₂ metal oxide and CuO-CeO₂ composite metal oxide was prepared with different methods.The active component Ag and the additive K were supported on the carrier by co-impregnation method to synthesize the load for catalytic oxidation of formaldehyde.Catalysts were used to investigate the effects of active components Ag,auxiliary K and different carriers on the activity of catalytic oxidation of formaldehyde.The structure of the catalyst was characterized by BET,XRD,H₂-TPR and O₂-TPD.The following conclusions:1?The CeO₂ nanorod?CeO₂-r?carrier was prepared by hydrothermal synthesis method.The Ag active component and the K additive were supported on the carrier by co-impregnation method to prepare a series of x%Ag-K/CeO₂-r catalyst,the results show that when the active component Ag content was 4%and the additive K content was 1.3%,the 4%Ag-K/CeO₂-r catalyst could achieve complete oxidation of HCHO at the temperature of 100?.The H₂-TPR and O₂-TPD characterization results showed that the 4%Ag-K/CeO₂-r catalyst had a low reduction temperature and abundant surface active oxygen species,which played an important role in the catalytic oxidation of formaldehyde.2?The CuO-CeO₂ mixed oxide was prepared by precipitation method,and the active component Ag was supported by co-impregnation method to obtain Ag/CuO-CeO₂ catalyst.Compared with Ag/CeO₂ and Ag/CuO,the catalyst Ag/CuO-CeO₂ had the best activity,and HCHO could performed 100%conversion of HCHO to H₂O and CO₂ at 80?.The BET data of CeO₂ and CuO were 64 m²/g and 78 m²/g,respectively.The specific surface area of CuO-CeO₂ increased to 95 m²/g and the pore volume increased to 0.16 cm³/g.It is because of its large specific surface area and pore volume that promotes the high dispersion of the active component Ag,and the synergy between CuO and CeO₂ enhances the low temperature reduction performance of the catalyst.