Novel microporous zirconium silicate (K2ZrSi3O9·2H2O) from high temperature phase transformation |
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Authors: | Artur Ferreira Maria R Soares |
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Institution: | a ESTGA, CICECO, University of Aveiro, Apartado 473, 3754-909 Águeda, Portugal b Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal c Central Laboratory of Analyses, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal |
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Abstract: | A new microporous zirconosilicate K2ZrSi3O9·2H2O (AV-15) has been prepared by high-temperature phase transformation at 910 °C. Its structure has been determined ab initio from powder X-ray diffraction data. The unit cell is orthorhombic, space group C2221 (no. 20), Z=4 with cell dimensions: a=8.105(3), b=10.684(5), c=12.030(5) Å, V=1041.76(7) Å3. The framework connection of AV-15 is essentially the same as the previously reported sodium stannosilicate AV-10 while the locations of potassium and water molecules in the former are quite different from those of the sodium and water molecules in AV-10. In AV-10 sodium and water molecules form a sinucoidal chain, while potassium and water molecules build up a linear chain in AV-15. The water molecules in AV-15 are lost on heating with a typical zeolitic behaviour. SEM shows that the particle sizes and habits of AV-15 and parent umbite material are the same. The 29Si MAS NMR spectrum of AV-15 displays two resonances at ca. −89.4 and −90.1 ppm in a 1:2 intensity ratio. Thermogravimetry analysis confirms the existence of water in this material. |
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Keywords: | Zirconosilicate Microporous Ab initio High-temperature phase transformation |
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