title: New insights in the formation of silanol defects in silicalite-1 by water intrusion under high pressure.
abstract: The "water-silicalite-1" system is known to act as a molecular spring. The successive intrusion-extrusion cycles of liquid water in small crystallites (6 × 3 × 0.5 μm(3)) of hydrophobic silicalite-1 were studied by volumetric and calorimetric techniques. The experiments displayed a decrease of the intrusion pressure between the first intrusion-extrusion cycle and the consecutive ones, whereas the extrusion pressures remained unchanged. However, neither XRD studies nor SEM observations revealed any structural and morphological modifications of silicalite-1 at the long-range order. Such a shift in the value of the intrusion pressure after the first water intrusion-extrusion cycle is attributed to the creation of silanol groups during the first water intrusion. Detailed FTIR and solid-state NMR spectroscopic characterizations provided a molecular evidence of chemical modification of zeolite framework with the formation of local silanol defects created by the breaking of siloxane bonds.
authors.affiliation: Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 5209 CNRS, Université de Bourgogne, 9 Av. A. Savary, BP 47870, F-21078 Dijon, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Karbowiak
authors.forename: Mohamed-Ali
authors.initials: MA
authors.lastname: Saada
authors.forename: Séverinne
authors.initials: S
authors.lastname: Rigolet
authors.forename: Anthony
authors.initials: A
authors.lastname: Ballandras
authors.forename: Guy
authors.initials: G
authors.lastname: Weber
authors.forename: Igor
authors.initials: I
authors.lastname: Bezverkhyy
authors.forename: Michel
authors.initials: M
authors.lastname: Soulard
authors.forename: Joël
authors.initials: J
authors.lastname: Patarin
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bellat
mesh_terms: D002151:Calorimetry; D003460:Crystallization; D011312:Pressure; D012821:Silanes / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry
chemical_list: D012821:Silanes; D017640:Silicates; D014867:Water; C082343:silanol; D017641:Zeolites