Research Of The Novel Metal-organic Frameworks Immobilized Mo-based Catalysts Preparation And Its Catalytic Properties

Metal-organic frameworks（MOFs） is a kind of crystalline material with periodic and infinite network structure, which is usually made of metal ions and organic ligands by coordination bonds or other weak interactions. Because of its larger specific surface area, regular pore structure, adjustable pore size and devisable surface chemical groups, MOFs are widely used in catalytic field. Epoxided soybean oil（ESBO） is acknowledged as an environment friendly plasticizer at present, but its traditional process produced large quantity of waste acid in production, which corrode the equipment and environment damage. With the improvement of people’s awareness of environmental protection, the demand of ESBO is also increasing. Therefore, it is urgently needed a novel catalyst to replace the traditional technology.The MoO₂（acac）₂@HKUST-1 catalyst was prepared by the direct lyophilization method, which showed good catalytic activity in the epoxidation of soybean oil. In the optimal reaction conditions, the highest yield of ESBO reached 44.2%. By the means of FT-IR, XRD, CO-FT-IR and SEM techniques, it was confirmed that MoO₂（acac）₂@HKUST-1 materials synthesized by the lyophilization method were nanosized, having an average particle size of ca. 150 nm. Moreover, the special morphologies and crystalline structure of HKUST-1 could be well kept after MoO₂（acac）₂ were introduced into HKUST-1, which were highly dispersed into the micropous cages of HKUST-1.The MoO₃/Cr₂O₃ catalysts were prepared by the traditional impregnation method using MIL-101 and ammonium molybdate as the precursors. The MoO₃/Cr₂O₃ catalysts were characterized by different means of techniques and their catalytic performance for the epoxidation of soybean oil was studied. All the results show that the MoO₃/Cr₂O₃ catalysts have the stronger L and B acid sites and the active species MoO3 were uniformly distributed in the surface of the support Cr2O3. The calcination temperature has a significant influence on the physical and chemical properties of the catalyst. The higher calcination temperature led to the decrease of the specific surface area and the formation of new species. The 10.0 %（w） MoO₃/Cr₂O₃ catalyst calcined at 600 ℃ has the highest catalytic activity and the yield of ESBO reached 43.3% at the optimal reaction conditions.The MoO₂（acac）₂@MIL-101 catalysts were prepared by the organic solvent-internal reflux method using MIL-101 and MoO₂（acac）₂ as the support and the active species, respectively. From the results of characterizations of the catalysts by XRD, FT-IR, TG and N2 adsorption techniques, it is concluded that the special morphologies and crystalline structure of MIL-101 could be well kept and and its thermal stability was enhanced after MoO₂（acac）₂ were introduced into MIL-101, which is highly dispersed into the mesoporous cages of MIL-101. The 25 %（w） MoO₂（acac）₂@MIL-101 catalyst show good catalytic activity for the epoxidation of soybean oil, which has high specific surface area and pore volume and high dispersed active species MoO₂（acac）₂.