Li Huining, Zhang Lei, Dai Hongxing, He Hong
Laboratory of Catalysis Chemistry and Nanoscience, Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
Inorg Chem. 2009 May 18;48(10):4421-34. doi: 10.1021/ic900132k.
Three-dimensionally (3D) ordered macroporous (3DOM) MgO, gamma-Al(2)O(3), Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) with polycrystalline mesoporous walls have been successfully fabricated with the triblock copolymer EO(106)PO(70)EO(106) (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 (CO(2)-TPD), and hydrogen temperature-programmed reduction (H(2)-TPR). It is shown that the as-fabricated MgO, gamma-Al(2)O(3), Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) samples possessed single-phase polycrystalline structures and displayed a 3DOM architecture; the MgO, Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) samples exhibited worm-hole-like mesoporous walls, whereas the gamma-Al(2)O(3) 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 Ce(0.6)Zr(0.4)O(2) with a surface area of 100 m(2)/g; with PMMA and F127 in an ethanol-HNO(3) solution, one can obtain 3DOM gamma-Al(2)O(3)with a surface area of 145 m(2)/g. The 3DOM MgO and 3DOM gamma-Al(2)O(3) samples showed excellent CO(2) adsorption behaviors, whereas the 3DOM Ce(0.6)Zr(0.4)O(2) 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 CO(2) adsorption.
采用三嵌段共聚物EO(106)PO(70)EO(106)（Pluronic F127）和规则排列的单分散聚甲基丙烯酸甲酯（PMMA）微球作为模板，以镁、铝、铈和锆的硝酸盐或异丙醇铝作为金属源，成功制备了具有多晶介孔壁的三维（3D）有序大孔（3DOM）氧化镁、γ-氧化铝、Ce(0.6)Zr(0.4)O(2)和Ce(0.7)Zr(0.3)O(2)。通过X射线衍射（XRD）、热重分析/差示扫描量热法（TGA/DSC）、傅里叶变换红外光谱（FT-IR）、高分辨率扫描电子显微镜（HRSEM）、高分辨率透射电子显微镜/选区电子衍射（HRTEM/SAED）、BET、二氧化碳程序升温脱附（CO(2)-TPD）和氢气程序升温还原（H(2)-TPR）等技术对合成的金属氧化物进行了表征。结果表明，所制备的氧化镁、γ-氧化铝、Ce(0.6)Zr(0.4)O(2)和Ce(0.7)Zr(0.3)O(2)样品具有单相多晶结构并呈现3DOM结构；氧化镁、Ce(0.6)Zr(0.4)O(2)和Ce(0.7)Zr(0.3)O(2)样品呈现蠕虫状介孔壁，而γ-氧化铝样品呈现3D有序介孔壁。溶剂（乙醇或水）的性质和浓度、金属前驱体、表面活性剂和干燥条件对最终产物的孔结构和表面积有重要影响。在合成体系中引入表面活性剂F127可显著提高3DOM金属氧化物的表面积。在40%乙醇溶液中加入PMMA和F127，可制备出比表面积为243 m(2)/g的排列良好的3DOM氧化镁和比表面积为100 m(2)/g的3DOM Ce(0.6)Zr(0.4)O(2)；在乙醇-硝酸溶液中加入PMMA和F127，可获得比表面积为145 m(2)/g的3DOMγ-氧化铝。3DOM氧化镁和3DOMγ-氧化铝样品表现出优异的CO(2)吸附性能，而3DOM Ce(0.6)Zr(0.4)O(2)样品表现出优异的低温还原性。3DOM和介孔壁共存所具有的独特物理化学性质使这些多孔材料成为多相催化和CO(2)吸附应用的理想候选材料。
