Atomic structure of selenium inserted in zeolites of the Na-mordenite type

• Published in: The Journal of physics and chemistry of solids 1996-03, Vol.57 (3), p.251-258
• Main Authors: Khouchaf, L., Tuilier, M.-H., Guth, J.L., Elouadi, B.
• Format: Article
• Language: English
• Subjects: A. microporous materials; Chemistry; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; General and physical chemistry; Inorganic compounds; Ion-exchange; Physics; Salts; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Surface and interface chemistry; Surface physical chemistry; X-ray absorption spectroscopy; zeolites; Zeolites: preparations and properties
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/0022-3697(95)00244-8

The atomic structure of Se incorporated with various amounts in both small and large pore zeolites of the Na-mordenite type is investigated by X-ray absorption spectroscopy (XAS). The results of the EXAFS analysis are compared to those obtained for hexagonal selenium. The distances of Se to its first and second Se neighbors are found to be 2.33 and 3.61 Å, respectively, and attributed to intrachain distances, which are reduced with respect to those of hexagonal selenium. The lack of the Se-Se distance at 3.44 Å confirms the loss of the first interchain bonds present in hexagonal Se and confirms the incorporation of single chains of Se in the channels of the mordenite in agreement with previous results given in the literature. Only small differences in the selenium environment are observed for the various contents of Se in mordenite. The presence of a peak around 4 Å in the Fourier transforms of the EXAFS data of all the analyzed compounds is attributed to the partial overlap of the single Se chains present inside the mordenite channels.