The Pivotal Role of Critical Hydroxyl Concentration in Si-Rich Zeolites for Switching Vapor Adsorption

M. Lions (1) , Cécile Daniel (1) , B. Coasne , Frédéric Meunier (2) , A. Tuel (1) , D. Farrusseng (1)

1 ING - IRCELYON-Ingéniérie, du matériau au réacteur
2 ATARI - IRCELYON-Approches thermodynamiques, analytiques et réactionnelles intégrées

The design of efficient separation and catalytic processes in nanoporous adsorbents requires to finely tune gas adsorption in their porosity. Here, using a large set of Si-rich zeolites (Silicalite-1, Beta, Chabazite, ITQ-13), we report on an experimental study of vapor adsorption in zeolites showing the pivotal role of the hydroxyl concentration. By studying the adsorption of water and methanol in zeolites assisted with in situ IR and 29 Si NMR measurements, we find that adsorption switches from non-wetting to wetting as the hydroxyl surface density reaches the same critical value ~2.5 OH/nm2. While this hydroxyl concentration-induced crossover is well-known for water, we extend here the concept of a critical concentration by showing that a consistent picture arises when different polar substrates are considered. In particular, by establishing a generic behavior between the two protic substrates (H2O, MeOH), we pave the way for the rational design of hydrophobic adsorbents

Domaines: Catalyse; Environnement et Société

M. Lions, Cécile Daniel, B. Coasne, Frédéric Meunier, A. Tuel, et al.. The Pivotal Role of Critical Hydroxyl Concentration in Si-Rich Zeolites for Switching Vapor Adsorption. Journal of Physical Chemistry C, 2021, 125 (41), pp.22890-22897. ⟨10.1021/acs.jpcc.1c07124⟩. ⟨hal-03420234⟩