Dealumination of hexagonal polytype of faujasite by treatments with silicon tetrachloride vapour

Autor:	Mark E. Davis, Michael J. Annen, Juan P. Arhancet, Hong-Xin Li, Cong-Yan Chen
Rok vydání:	1991
Předmět:	Hexagonal crystal system Inorganic chemistry Analytical chemistry General Chemistry Faujasite engineering.material Ammonia chemistry.chemical_compound Adsorption chemistry Desorption Materials Chemistry Silicon tetrachloride engineering Ammonium Material properties
Zdroj:	Journal of Materials Chemistry. 1:79
ISSN:	1364-5501 0959-9428
DOI:	10.1039/jm9910100079
Popis:	The hexagonal polytype of faujasite with Si/Al ratio of 3.26 is synthesized according to the procedure outlined by Delprato et al.(Zeolites for the Nineties—Recent Research Reports, 8th IZC, Amsterdam, July, 1989, 127). This material is dealuminated with silicon tetrachloride vapour at temperatures between 573 and 823 K to give a series of crystalline materials with framework Si/Al ratios ranging from 4.76 to 26.43. After subsequent washing and ammonium exchange, the solids are extensively characterized using a variety of physicochemical methods. The dealumination with SiCl4 does not produce observable losses in structural integrity. Unit-cell dimensions decrease from a= 17.326 A and c= 28.323 A for the as-synthesized material to a= 17.067 A and c= 27.885 A for the most highly dealuminated sample. Continuous changes in material properties at different degrees of dealumination are observed by 29Si MASNMR, IR, ammonia temperature-programmed desorption, and Ar adsorption measurements.
Databáze:	OpenAIRE
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