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

Three-dimensionally (3D) ordered macroporous (3DOM) MgO, gamma-Al2O3, Ce0.6Zr0.4O2, and Ce0.7Zr0.3O2 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 (H-2-TPR). It is shown that the as-fabricated MgO, gamma-Al2O3, Ce0.6Zr0.4O2, and samples possessed single-phase polycrystalline structures and displayed a 3DOM architecture; the MgO, Ce0.6Zr0.4O2, and Ce0.6Zr0.3O2 samples exhibited worm-hole-like mesoporous walls, whereas the gamma-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 m(2)/g and 3DOM Ce0.6Zr0.4O2 with a surface area of 100 m(2)/g; With PMMA and F127 in an ethanol-HNO3 solution, one can obtain 3DOM gamma-Al2O3 With a surface area of 145 m(2)/g. The 3DOM MgO and 3DOM gamma-Al2O3 samples showed excellent CO2 adsorption behaviors, whereas the 3DOM Ce0.6Zr0.4O2 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.