Résumé
This study examines the adsorption properties of MIL-120(Al) for pure vapour-phase sorbates (water and methanol) and their mixtures, with a particular focus on the material's selectivity influenced by relative pressure. The selected MOF presents 1-D channels of ∼3.5 × 6 Å2 aperture, associated with a specific surface area of 350 m2/g and a pore volume of 0.26 cm3/g. Adsorption isotherms at 25 °C, supported by Grand Canonical Monte Carlo (GCMC) simulations, revealed a high affinity of MIL-120(Al) for water and methanol at relative pressures lower than 0.2. However, methanol was identified as the preferred adsorbate at these low relative pressures in water-methanol mixtures. This selectivity, confirmed by GCMC, showed that the composition of the adsorbed phase was made of 90 % of methanol, regardless of the equilibrium vapour phase composition. In contrast, at higher relative pressures, the selectivity of MIL-120(Al) shifted markedly towards water, thereby highlighting the sensitivity of MIL-120(Al) to relative pressure in competitive adsorption scenarios. At high relative pressure, the composition of the adsorbed phase was found to be more than 95 % molar of water, even for vapours mixtures made of 50 % methanol. These findings contribute valuable insights into the design of pressure-sensitive adsorption systems for industrial applications such as sorption enhanced reaction production (SERP) technology.
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•MIL-120(Al) shows a high affinity for water and methanol.•There is an affinity switch triggered by the pressure of humid methanol.•Methanol can be selectively adsorbed at low pressure.•GCMC shows different adsorption sites for water and methanol.•MIL-120(Al) is a strong candidate for Sorption Enhanced Reaction Production.