Synthesis Of Bimetallic MOFs Based On MIL-100?Fe? As Catalyst For Selective Catalytic Reduction With NH₃

Finding effective treatment of NO_x has become one of the main environmental problems that should be solved at this stage.Selective catalytic reduction with ammonia?NH₃-SCR?is the most widely used technology to remove NO_x and has been researched in-depth owning to its low cost and high deNO_x efficiency.The key of SCR technology is the development and selection of the catalyst,which determines the deNO_x efficiency of catalytic reactions.Metal organic skeleton compounds?MOFs?have received extensive attention and application in the field of catalysis owning to its large specific surface area,ordered pore structure and abundant unsaturated metal activity sites.Nowadays,the research on MOFs is no longer focused on the material only with single metal active sites,but to construct MOFs with bimetallic active sites because the synergistic effect between the metal and electronic structure changes can be effective to improve the catalytic performance.So far,there are few reports on the application of MOFs in denitrification field,but MOFs has been considered to be promising catalysts.In this study,MIL-100?Fe-Mn?and Cu⁺/MIL-100?Fe?catalysts were synthesized by solvothermal synthesis and low-temperature loading method on the basis of MIL-100?Fe?for NH₃-SCR reaction,respectively.Through a series of characterization methods,the physical and chemical properties of bimetallic MOFs catalysts are investigated.The results are as follows:?1?MIL-100?Fe-Mn?catalyst was successfully prepared by direct solvothermal synthesis.By optimizing the conditions including solvent,metal ratio,activation temperature,it came to the conclusion that with water as solvent,Fe / Mn ratio of 1: 1,vacuum-activated MIL-100?Fe-Mn?catalyst could obtain the maximum NH₃-SCR efficiency.The NO_x conversion rate in the temperature window from 260 oC to 330 oC can reach more than 90%,with the best NO_x conversion rate up to 98.22%.This result is higher than that of the single metal catalysts.Meanwhile,MIL-100?Fe-Mn?catalyst has good resistance to sulfur and water.The reaction mechanism of NH₃-SCR was proposed in terms of in-situ FTIR technique.?2?The NH₃-SCR reaction over MIL-100?Fe-Mn?catalyst follows the E-R mechanism.First,NH₃ was adsorbed on the surface of the catalyst to form-NH2 species,then the-NH2 species react with gas phase NO over metal active sites to generate unstable intermediate NH2 NO.Finally,NH2 NO decomposed and conversed to non-polluting N2 and H2 O.?3?Cu⁺/ MIL-100?Fe?catalysts were prepared by low temperature loading method.EDX?XPS,et al proved Cu⁺ has been introducted and with the introduction of Cu⁺,the frame structure of the catalysts remain stable.Compared with the sample before loading the NH₃-SCR efficiency was increased by 16%.