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Title: Zeolites Upon Heating: Factors Governing Their Thermal Stability and Structural Chages

Abstract

This paper attempts to review and rationalize the results concerning the zeolite structural changes due to heating treatments. A new parameter, namely the Stability Index, was introduced to quantify the thermal stability of zeolites. Such an index is based on the zeolite breakdown temperatures from X-ray diffraction studies. The correlation between the stability index and the Si/Al ratio confirmed the importance of the latter ratio in controlling thermal stability of zeolites. It was observed that: (i) zeolites with Si/Al{>=}3.80 are very stable; (ii) zeolites with Si/Al{<=}1.28 are quite unstable; and (iii) zeolite stability in the intermediate Si/Al range cannot directly be predicted from the Si/Al ratio. In the present study, the inverse relationship between thermal stability and the ionic potential, (Z/r){sub wt}, was also confirmed: (i) zeolites with (Z/r){sub wt}<0.072 are very stable; (ii) the ones with (Z/r){sub wt}>0.187 are unstable, but (iii) the (Z/r){sub wt} ratio does not allow a discrimination in the intermediate region. The maximum volume contraction of the zeolite unit cell appears to be controlled by the weighted ionic potential. Among different factors related to the framework topology, the expected relationship between the framework density and the Stability Index was not found.

Authors:
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930105
Report Number(s):
BNL-80743-2008-JA
Journal ID: ISSN 0022-3697; JPCSAW; TRN: US200822%%1192
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physics and Chemistry of Solids; Journal Volume: 67
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ZEOLITES; HEAT TREATMENTS; MORPHOLOGICAL CHANGES; THERMODYNAMIC PROPERTIES; SILICON; ALUMINIUM; CONCENTRATION RATIO; national synchrotron light source

Citation Formats

Cruciani,G. Zeolites Upon Heating: Factors Governing Their Thermal Stability and Structural Chages. United States: N. p., 2006. Web. doi:10.1016/j.jpcs.2006.05.057.
Cruciani,G. Zeolites Upon Heating: Factors Governing Their Thermal Stability and Structural Chages. United States. doi:10.1016/j.jpcs.2006.05.057.
Cruciani,G. Sun . "Zeolites Upon Heating: Factors Governing Their Thermal Stability and Structural Chages". United States. doi:10.1016/j.jpcs.2006.05.057.
@article{osti_930105,
title = {Zeolites Upon Heating: Factors Governing Their Thermal Stability and Structural Chages},
author = {Cruciani,G.},
abstractNote = {This paper attempts to review and rationalize the results concerning the zeolite structural changes due to heating treatments. A new parameter, namely the Stability Index, was introduced to quantify the thermal stability of zeolites. Such an index is based on the zeolite breakdown temperatures from X-ray diffraction studies. The correlation between the stability index and the Si/Al ratio confirmed the importance of the latter ratio in controlling thermal stability of zeolites. It was observed that: (i) zeolites with Si/Al{>=}3.80 are very stable; (ii) zeolites with Si/Al{<=}1.28 are quite unstable; and (iii) zeolite stability in the intermediate Si/Al range cannot directly be predicted from the Si/Al ratio. In the present study, the inverse relationship between thermal stability and the ionic potential, (Z/r){sub wt}, was also confirmed: (i) zeolites with (Z/r){sub wt}<0.072 are very stable; (ii) the ones with (Z/r){sub wt}>0.187 are unstable, but (iii) the (Z/r){sub wt} ratio does not allow a discrimination in the intermediate region. The maximum volume contraction of the zeolite unit cell appears to be controlled by the weighted ionic potential. Among different factors related to the framework topology, the expected relationship between the framework density and the Stability Index was not found.},
doi = {10.1016/j.jpcs.2006.05.057},
journal = {Journal of Physics and Chemistry of Solids},
number = ,
volume = 67,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
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