Pure silica chabazite molecular spring: a structural study on water intrusion-extrusion processes.
Water intrusion-extrusion isotherms performed at room temperature on hydrophobic pure silica chabazite show that the water-Si-CHA system displays real spring behavior. However, differences in pressure-volume diagrams are observed between the first and the other intrusion-extrusion cycles, indicating that some water molecules interact with the inorganic framework after the first intrusion. (29)Si and especially (1)H solid-state NMR showed the creation of new defect sites upon the intrusion-extrusion of water and the existence of two kinds of water molecules trapped in the supercage of Si-CHA: a first layer of water strongly hydrogen bonded with the silanols of the framework and a subsequent layer of liquidlike physisorbed water molecules undergoing interaction with the first layer. This hydrogen bonding scheme is also supported by X-ray powder diffraction.
Trzpit
Mickaël
M
Laboratoire de Matériaux à Porosité Contrôlée, UMR CNRS 7016, ENSCMu, UHA, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France.
Rigolet
Séverinne
S
Paillaud
Jean-Louis
JL
Marichal
Claire
C
Soulard
Michel
M
Patarin
Joël
J