Sui Ruohong, Rizkalla Amin S, Charpentier Paul A
Department of Chemical and Biochemical Engineering, Faculty of Engineering, University of Western Ontario, London, Ontario, Canada N6A 5B9.
Langmuir. 2006 Apr 25;22(9):4390-6. doi: 10.1021/la053513y.
The objective of the present study was to synthesize porous ZrO2 aerogels with a nanostructure via a direct sol-gel route in the green solvent supercritical carbon dioxide (scCO2). The synthesis involved the coordination and polycondensation of a zirconium alkoxide using acetic acid in CO2, followed by scCO2 drying and calcination. Either a translucent or opaque monolith was obtained, which was subsequently characterized by electron microscopy, X-ray diffraction, thermal analysis, N2 physisorption, and infrared spectroscopy analysis. The electron microscopy results showed that the translucent monolithic ZrO2 exhibited a well-defined mesoporous structure, while the opaque monolith, formed using added alcohol as a cosolvent, was composed of loosely compacted nanospherical particles with a diameter of ca. 20 nm. After calcination at 400 and 500 degrees C, X-ray diffraction results indicated that the ZrO2 exhibited tetragonal and/or monoclinic phases. In situ infrared spectroscopy results showed the formation of a Zr-acetate coordinate complex at the initial stage of the polycondensation, followed by further condensation of the complex into macromolecules.
本研究的目的是通过在绿色溶剂超临界二氧化碳（scCO2）中采用直接溶胶-凝胶法合成具有纳米结构的多孔ZrO2气凝胶。合成过程包括在二氧化碳中使用乙酸使锆醇盐进行配位和缩聚，随后进行scCO2干燥和煅烧。获得了半透明或不透明的整块材料，随后通过电子显微镜、X射线衍射、热分析、N2物理吸附和红外光谱分析对其进行表征。电子显微镜结果表明，半透明的整块ZrO2呈现出明确的介孔结构，而使用添加的醇作为共溶剂形成的不透明整块材料则由直径约为20 nm的松散压实的纳米球形颗粒组成。在400和500摄氏度煅烧后，X射线衍射结果表明ZrO2呈现四方相和/或单斜相。原位红外光谱结果表明，在缩聚初始阶段形成了Zr-乙酸酯配位络合物，随后该络合物进一步缩聚成大分子。
