Thermal Decomposition of NH4-Analcime Full article
Journal |
Physics and Chemistry of Minerals
ISSN: 0342-1791 , E-ISSN: 1432-2021 |
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Output data | Year: 2004, Volume: 31, Number: 5, Pages: 306-312 Pages count : 7 DOI: 10.1007/s00269-004-0388-9 | ||||
Tags | Ammonium analcime, De-ammoniation, Dehydroxylation, Gas chromatography, IR spectroscopy | ||||
Authors |
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Affiliations |
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Funding (2)
1 | Russian Foundation for Basic Research | 02-05-65313 |
2 | Russian Foundation for Basic Research | 04-05-64351 |
Abstract:
The thermal decomposition of ammonium-exchanged natural analcime is characterized by gas chromatography, IR spectroscopy and X-ray diffraction. The de-ammoniation and dehydroxylation proceed in parallel throughout the decomposition, which evidences the instability of the protonated analcime framework. The mechanism of degassing of NH4-analcime changes throughout its decomposition. At the initial step, the mechanism of de-ammoniation consists in thermal dissociation of NH4+ molecule onto NH3 and proton (framework OH group) and diffusion of NH3 out of the structure. Subsequent decomposition and removal of the OH groups lead to a progressive loss of crystallinity. At this step, an apparent activation energy for NH3 desorption is estimated to be 145(±13) kJ mol−1. This value is within the upper limit of the activation energy characteristic for the NH3 desorption from proton centres in large-pore zeolites. At the final step, the adsorption of NH3 and protons onto the defect centres in the amorphosed aluminosilicate framework results in a significant increase of an apparent activation energy for the de-ammoniation and dehydroxylation up to 270(±20) kJ mol−1.
Cite:
Likhacheva A.Y.
, Veniaminov S.A.
, Paukshtis E.A.
Thermal Decomposition of NH4-Analcime
Physics and Chemistry of Minerals. 2004. V.31. N5. P.306-312. DOI: 10.1007/s00269-004-0388-9 WOS Scopus РИНЦ
Thermal Decomposition of NH4-Analcime
Physics and Chemistry of Minerals. 2004. V.31. N5. P.306-312. DOI: 10.1007/s00269-004-0388-9 WOS Scopus РИНЦ
Dates:
Submitted: | Apr 11, 2003 |
Accepted: | Feb 3, 2004 |
Published print: | Jun 1, 2004 |
Identifiers:
Web of science | WOS:000221785000005 |
Scopus | 2-s2.0-3242794449 |
Elibrary | 13449333 |
Chemical Abstracts | 2004:446809 |
Chemical Abstracts (print) | 141:193098 |
OpenAlex | W167483278 |