1. Elementary processes in a porous particle

Many chemical and physical interactions involve a fluid phase and a solid phase. These interactions are at the origin of separation processes (adsorption, chromatography, ion exchange, drying, filtration, etc.) and/or catalytic or consumable chemical transformation processes. To increase interactions per unit volume or mass of solid, the solid phase must be divided when natural, or made microporous in the case of synthetic solid particles. It is therefore common to have specific surface areas (surface per unit mass) ranging from several square meters per gram to 1,000 to 2,000 m ² /g (in the case of activated carbons).

Obtaining these specific surfaces requires the presence of a microporosity in which diffusional transport of matter is no longer negligible compared with possible convective transfers.

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