Performance Regulation Of Pt-based MOF Catalysts And Their Application In CO Oxidation Reaction

Air pollution is one of the top 10 threats to human health.CO is a toxic and harmful air pollutant,mainly derived from the emission of vehicle exhaust,industrial production,and incomplete combustion of fossil fuels.CO not only affects human health but also poses hazards to plant growth and the ecological environment in number of ways.The fuel H₂ of proton exchange membrane fuel cell（PEMFC）contains trace amounts of CO,which can poison the Pt-based electrode,thus reducing the efficiency and lifetime of the fuel cells.Thus,it is crucial to effectively eliminate CO for the sake of humans,animals,plants,the environment,and the development of new energy sources.Among the many elimination methods,CO low-temperature（preferential）oxidation is widely recognized as one of the cleanest,most efficient and simple elimination methods.Pt-supported catalysts have attracted significant attention due to their excellent catalytic activity in CO oxidation reaction.However,these catalysts still face issues such as high cost,poor low-temperature activity,and poor anti-CO poisoning ability,making them unsuitable for industrial production.Therefore,how to design Pt-supported CO oxidation catalysts with high activity,stability,and low cost under low temperature conditions has certain practical value.The choice of catalyst support is closely related to the catalytic activity of Pt catalysts.Metal-organic framework（MOF）materials offer a large specific surface area,pore volume,and a well-developed pore structure,which can highly disperse the active components.MOF materials have shown excellent results in various catalytic reactions and are a promising catalyst support.Among the MOF materials,the MIL（Cr）series of materials have gained extensive attention in the catalysis field due to their high specific surface area,excellent thermal stability,and simple synthesis steps.It is worth noting that MOF-supported catalysts are mainly used in liquid-phase reactions under mild conditions.There are rarely reports on their use in gas-phase CO（preferential）oxidation reactions.Based on this,the classic MIL（Cr）series MOF materials were chosen as the support,and a series of supported Pt_xNi_1-x/MIL（Cr）catalysts were prepared using the double-solvent impregnation method.The study systematically explores the effects of catalyst pretreatment conditions,Pt/Ni molar ratio,support properties,and reduction methods on the catalytic performance of supported Pt_xNi_1-x/MIL（Cr）catalysts.The catalysts were characterized using a variety of techniques,including XRD,FT-IR,N₂adsorption/desorption,TEM,SEM,XPS,TG,TPSR,and In-situ DRIFTS.The study aims to provide a comprehensive understanding of the relationship between the catalysts physical and chemical properties and their catalytic performance in low-temperature CO oxidation and CO preferential oxidation.The main research contents of this paper are as follows:1.MIL-101（Cr）support was prepared using the hydrothermal method,and Pt/MIL-101（Cr）supported catalyst was prepared using the double-solvent impregnation method.The study investigated the effects of different pretreatment atmospheres on the CO oxidation performance of Pt/MIL-101（Cr）catalyst.Results showed that using a reducing atmosphere H₂ pretreatment significantly improved the CO oxidation activity of the catalyst compared to the inert atmosphere Ar and oxidizing atmosphere Air.2.Pt_xNi_1-x/MIL-101（Cr）series supported catalysts were prepared by introducing non-noble metal Ni,and the effect of Pt/Ni molar ratio on CO oxidation reaction activity was investigated.The study found that the catalyst with a Pt/Ni molar ratio of 0.50/0.50exhibited the highest activity in the CO oxidation reaction,and its low-temperature activity was significantly improved compared to the Pt/MIL-101（Cr）catalyst.3.The study compared the catalytic performance of Pt_xNi_1-x/MIL-101（Cr）series catalysts in the preferential oxidation reaction of CO with different Pt/Ni molar ratios.Results showed that the Pt_0.33Ni_0.67/MIL-101（Cr）catalysts exhibited optimal catalytic activity,achieving 100%conversion of CO in a wide temperature range while maintaining a selectivity of about 62%.4.To further enhance the hydrothermal stability of Pt_0.33Ni_0.67/MIL-101（Cr）catalyst,MIL-Z1（Cr）and MIL-53（Cr）were used as catalyst supports.Due to the strong hydrophobicity of MIL-Z1（Cr）and MIL-53（Cr）supports,the stability of Pt_0.33Ni_0.67/MIL-Z1（Cr）and Pt_0.33Ni_0.67/MIL-53（Cr）catalysts in preferential CO oxidation reaction was significantly improved.