The influences of the way of preparation of Me-aluminosilicates (Me = Li, Na, K, Rb and Cs) on the products

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• 作者：Cleo Kosanović ; Sanja Bosnar ; Boris Subotić ; Nata&#x161 ; a Novak Tu&#x161 ; ar ; Alenka Ristić ; Roman Gabrov&#x161 ; ek ; Venč ; eslav Kauč ; ič
• 关键词：Aluminosilicates ; Thermal transformations ; Ceramics aluminosilicates
• 刊名：Microporous and Mesoporous Materials
• 出版年：2008
• 期刊代码：78_13871811
• 类别：ch
• 出版时间：1 July 2008
• 卷：112
• 期：1-3
• 页码：542-552
• 文件大小：751 K

摘要

X-ray amorphous Me-aluminosilicates (Me = Li, K, Na, Rb and Cs) were prepared in two ways: (A) by ion-exchange of sodium ions from Na-aluminosilicate gel with other alkaline cations (Li, K, Rb and Cs) resulting in Me-gels(A) and (B) by direct precipitation from the corresponding Me-aluminate and Me-silicate solutions resulting in Me-gels(B). The Me-aluminosilicates prepared by both methods (zeolitic forms) as well as the products of their solid-state, high-temperature transformations (ceramic forms), were characterized by different techniques such as X-ray powder diffraction (XRD), elemental analysis by X-ray dispersive spectroscopy (EDS), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC) and texture analysis (BET method). Elemental analyses of prepared Me-gels(A) have shown that the exchange of sodium cations from the Na-aluminosilicate gel does not considerably change its chemical composition, structural and physical properties. On the other hand, the type of ion-exchanged cations Me⁺ considerably influences the aluminosilicate composition in the Me-gels(B), and thus their skeleton as revealed by XRD analysis. Thermal treatment of Me-gels(A) and the Me-gels(B) (isothermal heating at 925–1250 °C for 3 h) resulted in their transformation into appropriate crystalline aluminosilicate phases having chemical composition MeAlSiO₄ or MeAlSi₂O₆, respectively. All the transformations are accompanied with a drastic decrease in the specific surface area caused by the transition of porous amorphous Me-aluminosilicates into more dense, non-porous crystalline phases.