Synthesis of Monolithic Al2O3 with Well-Defined Macropores and Mesostructured Skeletons via the Sol−Gel Process Accompanied by Phase Separation
Synthesis of Monolithic Al2O3 with Well-Defined Macropores and Mesostructured Skeletons via the Sol−Gel Process Accompanied by Phase Separation
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DOI：
10.1021/cm063051p
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发表时间：
2007-06
影响因子：
8.6
通讯作者：
Yasuaki Tokudome;K. Fujita;K. Nakanishi;K. Miura;K. Hirao
中科院分区：
文献类型：
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作者：
Yasuaki Tokudome;K. Fujita;K. Nakanishi;K. Miura;K. Hirao
在环氧丙烷和聚环氧乙烷(PEO)存在下，铝盐的水溶液和乙醇溶液通过自发路线合成了具有规整的大孔和中观骨架的氧化铝(Al_2O_3)单块。在起始溶液中加入环氧丙烷控制了凝胶的形成，而加入PEO则导致了相分离。选择合适的起始组成，使相分离和凝胶共存，可以制备大尺寸(10×10×10 mm~3)的双连续大孔Al_2O_3整体。根据起始溶液中PEO含量的不同，大孔的大小可控制在400 nm到1.8mPEO的范围内。干凝胶为非晶态，800℃以上加热可形成晶相而不破坏大孔形貌；800℃时析出纳米γ-Al_2O_3,1000℃时α-Al_2O_3开始形成，并完全转变为α-Α_2O_3。
Alumina (Al2O3) monoliths with well-defined macropores and mesostructured skeletons have been synthesized via a spontaneous route from the aqueous and ethanolic solution of aluminum salts in the presence of propylene oxide and poly(ethylene oxide) (PEO). The addition of propylene oxide to the starting solution controls the gelation, whereas the addition of PEO induces the phase separation. Appropriate choice of the starting composition, by which the phase separation and gelation concur, allows the production of bicontinuous macroporous Al2O3 monoliths in large dimensions (10 × 10 × 10 mm3). The size of macropores is controlled in the range of 400 nm to 1.8 μm, depending on the PEO content in starting solutions. The dried gel is amorphous, whereas heating at temperatures above 800 °C leads to the formation of crystalline phases without spoiling the macroporous morphology; nanocrystalline γ-Al2O3 is precipitated at 800 °C, α-Al2O3 starts to form at 1000 °C, and complete transformation into α-Αl2O3 is achiev...