Study On The Mesoporous Co₃O₄-Supported Pt Catalysts For The Oxidative Removal Of Acetylene

Acetylene as a part of volatile organic compounds?VOCs?is one of the air pollutants,and it is mainly emitted from vehicle exhausts and petrochemical processing.It enhances the photochemical reaction and promotes the formation of secondary organic aerosols?SOAs?and ozone.Catalytic oxidation is one of the most effecitive pathways to eliminate air pollution,in which the key issue is the development of the catalytic materials.Thus,it is very significant to explore a high performance catalyst for removing acetylene.Three-dimensional ordered mesoporous metal oxides possess high surface area,large pore volume and controllable pore diameter.It could reduce reaction diffusion resistance and improve the effective contact between acetylene and catalyst.Noble metal nanoparticles are favorable for the adsorption and activation of molecular oxygen and increase the redox ability of the catalyst,which improve the catalytic oxidation activity of acetylene.In this thesis,the ordered mesoporous Co₃O₄ is synthesized.Meanwhile,it is chosen as support and Pt is the active component.There are two ways to further improving the activity and stability of the catalyst involving the design of ordered mesoporous Co₃O₄-supported Pt nanoparticles.Various characterization methods are used to study the relationships among catalyst structure,physicochemical properties and catalytic activity.KIT-6 mesoporous zeolite is prepared by hydrothermal method with a three-dimensional bicontinuous cubic structure.Ordered mesoporous Co₃O₄ is successfully synthesized by using hard templating method from metal nitrate and KIT-6hard template.Based on the results of XRD and TEM,Co₃O₄ has ordered mesoporous structure.The average pore diameter of mesoporous Co₃O₄ is 8.4 nm.Mesoporous Co₃O₄ sample shows higher catalytic activity for acetylene oxidation due to enhanced contact efficiency between acetylene and catalyst.Mesoporous Co₃O₄-supported Pt catalysts are prepared by the method of reduction-deposition method.All the catalysts form mesoporous structure and possess high surface area of 110-111.5 m²/g.The catalytic activity evaluation results demonstrate that the loading of Pt can enhance the catalytitc activity of mesoporous Co₃O₄-supported Pt catalysts.0.6Pt/meso-Co₃O₄ catalyst gives the lowest temperature of 120^oC for acetylene oxidation.Based on the results of characterization and catalytic activity test,it is concluded that ordered mesoporous structure,plenty of structure defects,good low-temperature reducibility and high concentration of activity oxygen species are responsible for the excellent catalytic performance of 0.6Pt/meso-Co₃O₄.