To study the energetic performance of the 1D 12-membred-ring pure silica ITQ-4 zeolite (IFR topology), a high-pressure water intrusion-extrusion isotherm at room temperature was performed. The pressure-volume diagram indicates an irreversible phenomenon, water molecules remaining confined in ITQ-4 micropores. Therefore, the "water-ITQ-4" system appears to behave as a bumper. The water intrusion pressure and intruded volume are of 42 MPa and 0.136 mL/g, respectively. Investigations on the ITQ-4 samples by 29 Si and 1 H solid-state NMR spectroscopy and powder X-ray diffraction have confirmed the existence of a small amount of silanol defects in the nonintruded sample and an increase of these defects after the water intrusion-extrusion experiment. It appears clearly that one of the crystallographic silicon sites of the porous framework is particularly affected after such a treatment, leading to the creation of Si-OH groups by the breaking of siloxane bonds, these silanols being strongly hydrogen bonded with water molecules.

The energetic performance of two microporous siliceous materials, RUB-41 (RRO structure type) and S-SOD (SOD structure type) possessing medium-sized and very small pore openings, respectively, were studied using high-pressure water intrusion-extrusion experiments at room temperature. The pressure-volume diagrams of the RUB-41 material indicate a partly reversible phenomenon showing a slight hysteresis at the extrusion stage, which reveals that the water-RUB-41 system displays a shock-absorber behavior. Moreover, a shift toward the low pressure range was detected between the first cycle of water intrusion and the second one, indicating the creation of new defect sites in the inorganic framework after the intrusion process. Several investigations, mainly by 29 Si solid-state NMR spectroscopy, confirm this observation. For the S-SOD material, no water intrusion was observed after three water intrusion-extrusion cycles. The highly hydrophobic character of the S-SOD material with its small pore opening or the value of the capillary pressure, which exceeds that tolerated by the instrument, are probably the two reasons for this result.