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Dehydration Process of Hofmann-Type Layered Solids
Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Unidad Legaria, Instituto Politécnico Nacional, Legaria 694, Colonia, Irrigación, México D.F. 11500, Mexico
Mexican Petroleum Institute, Eje Central 152, México D.F. 07730, Mexico
Center for Research and Advanced Studies of the National Polytechnic Institute, Km 6 Antigua Carretera Progreso, Cordemex, Mérida 97310, Yucatán, Mexico
* Author to whom correspondence should be addressed.
Received: 14 December 2012; in revised form: 8 March 2013 / Accepted: 22 March 2013 / Published: 9 April 2013
Abstract: In the present work the dehydration process of layered solids with formula unit M(H2O)2[Ni(CN)4]·nH2O, M = Ni, Co, Mn; n = 1, 2, 4 is studied using modulated thermogravimetry. The results show that water molecules need to overcome an energetic barrier (activation energy between 63 and 500 kJ/mol) in order to diffuse through the interlayer region. The related kinetic parameters show a dependence on the water partial pressure. On the other hand, X-ray diffraction results provide evidence that the dehydration process is accompanied by framework collapse, limiting the structural reversibility, except for heating below 80 °C where the ordered structure remains. Removal of water molecules from the interlayer region disrupts the long-range structural order of the solid.
Keywords: kinetics parameters; hi-res/modulated-TG; porous lattices; dehydration of lamellar solids
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MDPI and ACS Style
Reyes-Martinez, O.; Torres-García, E.; Rodríguez-Gattorno, G.; Reguera, E. Dehydration Process of Hofmann-Type Layered Solids. Materials 2013, 6, 1452-1466.
Reyes-Martinez O, Torres-García E, Rodríguez-Gattorno G, Reguera E. Dehydration Process of Hofmann-Type Layered Solids. Materials. 2013; 6(4):1452-1466.
Reyes-Martinez, Omar; Torres-García, Enelio; Rodríguez-Gattorno, Geonel; Reguera, Edilso. 2013. "Dehydration Process of Hofmann-Type Layered Solids." Materials 6, no. 4: 1452-1466.