Nanoporous materials: from their characterization to adsorption or energy storage applications

The use of nanoporous materials is wide and concerns the fields of catalysis, health, energy, environment and sustainable development.
In the case of separation or storage of molecules, the knowledge of the textural characteristics is fundamental. For that, standard technics can be used such as N2 adsorption at 77K or mercury porosimetry to determine the surface area, the pore volume or the pore size distribution.
Adsorption is an important process investigated for gas separation/storage and also for liquid purification. To quantify the phenomenon the adsorption isotherms need to be established. According to the adsorbate phase, different technics are available either manometry/gravimetry for the gas or liquid depletion method for liquid phase.
A better understanding of the mechanism of adsorption is possible by combining these technics with microcalorimetry allowing to measure the energy involved for the interaction between the nanoporous adsorbent and the probe.
Moreover the nanoporous materials may be used as mechanical energy storage systems. When they are submitted to mechanical pressure :

• either the non wetting transmitting pressure fluid may enter into the pore at a defined pressure leading to the intrusion involving a conversion of mechanical energy into interfacial energy
• or the flexible nanoporous material (such as MOFs) undergoes a structural change

According to the reversibility of the phenomenon the material show different mechanical behavior from spring to dumpers.