resumo
A new microporous zirconosilicate K2ZrSi3O9 center dot 2H(2)O (AV-15) has been prepared by high-temperature phase transformation at 910 degrees C. Its structure has been determined ab initio from powder x-ray diffraction data. The unit cell is orthorhombic, space group C222(1) (no. 20), Z=4 with cell dimensions: a=8.105(3), b=10.684(5), c= 12.030(5) angstrom, V=1041.76(7) angstrom(3). 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 Si-29 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. (c) 2010 Elsevier Inc. All rights reserved.
palavras-chave
INITIO STRUCTURE DETERMINATION; POWDER DIFFRACTION DATA; STRUCTURAL-CHARACTERIZATION; AB-INITIO; FRAMEWORK ZIRCONIUM; ION-EXCHANGE; STANNOSILICATE; K2TISI3O9-CENTER-DOT-H2O; TRISILICATE; ZIRCONOSILICATES
categoria
Chemistry
autores
Ferreira, A; Lin, Z; Soares, MR; Rocha, J
nossos autores
Artur Jorge Faria Ferreira
Professor Coordenador
João Rocha
Prof. Catedrático
Maria do Rosário Teixeira Soares
Técnico de Laboratório
Zhi Lin
Investigador Principalagradecimentos
We greatly appreciate the financial support from FCT, POCI2010, PTDC, FSE, and FEDER.