Micropore characterization
Texture of divided materials Pore size of nanoporous materials from nitrogen adsorption

To begin with, it should be noted that micropores fill at very low relative pressures, sometimes as low as 10 ^–7 w/w ⁰ , which corresponds to a nitrogen equilibrium pressure of 10 ^–4 mbar. To be able to highlight microporosity, it is therefore necessary to ensure that the apparatus used enables reliable measurements to be made at these low pressures. This requires not only a 0 to 1 mbar pressure gauge, but also a device that is sufficiently tight to obtain a static vacuum for the duration of the measurements. Moreover, the smaller the micropores, the longer it takes to reach equilibrium, since diffusion of nitrogen is...