Studies of Acid Properties of FeSiMCM-41 and LaSiMCM-41 by NH3-microcalorimetric and NH3-TPD Measurements |
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| Authors: | N. He D. Li M. Tu J. Shen S. Bao Q. Xu |
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| Affiliation: | (1) National Laboratory of Molecular and Biomolecular Electronics, Southeast University, Nanjing, 210096, P. R. China;(2) Department of Chemistry, Nanjing University, Nanjing, 210093, P. R. China;(3) Department of Chemistry, Teachers' College of Xiangtan, Xiangtan, 411100, P. R. China |
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| Abstract: | The acidity of mesoporous materials FeSiMCM-41, LaSiMCM-41, SiMCM-41, AlSiMCM-41 and HAlSiMCM-41 has been investigated by microcalorimetric studies of the adsorption of ammonia and temperature programmed ammonia desorption method. In the initial stage, the acid strength sequence is SiMCM-41>HAlSiMCM-41>AlSiMCM-41>FeSiMCM-41>LaSiMCM-41, in agreement with that found for microporous molecular sieves materials. A small number of strong acid sites of SiMCM-41 may result from the aluminum impurity contained in the silica source material. The acid density sequence is HAlSiMCM-41>AlSiMCM-41>FeSiMCM-41>LaSiMCM-41 SiMCM-41 and can be explained by the studies of existing states of trivalent atoms in these samples reported in previous work. Since some NH3-TPD plots of these samples show the profiles that could not be back to baseline at elevated temperature, the technique of microcalorimetric adsorption is preferable in studying these samples.This revised version was published online in November 2005 with corrections to the Cover Date. |
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| Keywords: | acidity mesoporous materials microcalorimetric studies of the adsorption of ammonia TPD of ammonia |
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