Facile Synthesis and Unique Physicochemical Properties of Three-Dimensionally Ordered Macroporous Magnesium Oxide, Gamma-Alumina, and Ceria−Zirconia Solid Solutions with Crystalline Mesoporous W

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• 作者：Huining Li ; Lei Zhang ; Hongxing Dai ; Hong He
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：May 18, 2009
• 年：2009
• 卷：48
• 期：10
• 页码：4421-4434
• 全文大小：915K
• 年卷期：v.48,no.10(May 18, 2009)
• ISSN：1520-510X

文摘

Three-dimensionally (3D) ordered macroporous (3DOM) MgO, γ-Al₂O₃, Ce_0.6Zr_0.4O₂, and Ce_0.7Zr_0.3O₂ with polycrystalline mesoporous walls have been successfully fabricated with the triblock copolymer EO₁₀₆PO₇₀EO₁₀₆ (Pluronic F127) and regularly packed monodispersive polymethyl methacrylate (PMMA) microspheres as the template and magnesium, aluminum, cerium and zirconium nitrate(s), or aluminum isopropoxide as the metal source. The as-synthesized metal oxides were characterized by means of techniques such as X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), Fourier transform infrared (FT-IR), high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy/selected area electron diffraction (HRTEM/SAED), BET, carbon dioxide temperature-programmed desorption (CO₂-TPD), and hydrogen temperature-programmed reduction (H₂-TPR). It is shown that the as-fabricated MgO, γ-Al₂O₃, Ce_0.6Zr_0.4O₂, and Ce_0.7Zr_0.3O₂ samples possessed single-phase polycrystalline structures and displayed a 3DOM architecture; the MgO, Ce_0.6Zr_0.4O₂, and Ce_0.7Zr_0.3O₂ samples exhibited worm-hole-like mesoporous walls, whereas the γ-Al₂O₃ samples exhibited 3D ordered mesoporous walls. The solvent (ethanol or water) nature and concentration, metal precursor, surfactant, and drying condition have an important impact on the pore structure and surface area of the final product. The introduction of surfactant F127 to the synthesis system could significantly enhance the surface areas of the 3DOM metal oxides. With PMMA and F127 in a 40% ethanol solution, one can generate well-arrayed 3DOM MgO with a surface area of 243 m²/g and 3DOM Ce_0.6Zr_0.4O₂ with a surface area of 100 m²/g; with PMMA and F127 in an ethanol−HNO₃ solution, one can obtain 3DOM γ-Al₂O₃with a surface area of 145 m²/g. The 3DOM MgO and 3DOM γ-Al₂O₃ samples showed excellent CO₂ adsorption behaviors, whereas the 3DOM Ce_0.6Zr_0.4O₂ sample exhibited exceptional low-temperature reducibility. The unique physicochemical properties associated with the copresence of 3DOM and mesoporous walls make these porous materials ideal candidates for applications in heterogeneous catalysis and CO₂ adsorption.