Water Release from Pyrophyllite during the Dehydroxylation Process Explored by Quantum Mechanical Simulations
Metadatos
Afficher la notice complèteAuteur
Molina Montes, María Ester; Donadio, Davide; Hernández Laguna, Alfonso; Parrinello, Michele; Sainz Díaz, Claro IgnacioEditorial
American Chemical Society
Date
2013-03-20Referencia bibliográfica
J. Phys. Chem. C 2013, 117, 15, 7526–7532
Patrocinador
IACTRésumé
We have investigated one of the most controversial aspects of the dehydroxylation–rehydroxylation process of dioctahedral 2:1 phyllosilicates, that is the release of water from the internal structure of the mineral. We simulate the release of water from a periodic crystal model of pyrophyllite by Car–Parrinello molecular dynamics based on Density Functional Theory. The metadynamics algorithm is employed to accelerate activated processes and compute free energy surfaces. We found that, in spite of the strong hydrogen bonds anchoring water molecules in the tetrahedral cavity, the energy barrier for water release is lower than that for the chemical formation of water molecules from the hydroxyl groups. We then conclude that water release is not the rate-limiting step of the dehydration mechanism.