Studies on Mesoporous Self-Organizing Aluminosilica |
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Authors: | Hong-Ping Lin Chung-Yuan Mou |
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Institution: | (1) Institute of Atomic and Molecular Science, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan;(2) Department of Chemistry, National Taiwan University, Taipei, Taiwan |
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Abstract: | A detailed study on the preparation of highly ordered MCM-41 molecular sieves based on our new delayed neutralization process is presented. The rate of acidification does not have an apparent effect on the XRD patterns of MCM-41 but affects the morphology. The synthesized products give a thicker constant wall thickness (about 1.70 nm) of mesopore and a sharp pore size distribution. However, the structural order depends on the carbon chain length, the amount of alcohols as cosurfactants, and the synthetic temperature. A tubular morphology of the MCM-41 material, with hollow tubules 0.3 to 3 m in diameter, can be obtained by careful control of the surfactant–water content and the rate of condensation of silica under high-alkalinity conditions. In tubules-within-a-tubule, the wall of the tubule consists of coaxial cylindrical pores of nanometers characteristic of MCM-41. The hierarchical order structure takes place through a liquid crystal phase transformation mechanism in which an anisotropic membrane-to-tubule phase change is involved. |
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Keywords: | M41S MCM-41 mesoporous molecular sieves delayed neutralization hierarchical order tubules |
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