Interplay between alkali-metal cations and silanol sites in nanosized CHA zeolite: implications for CO2 adsorption
Résumé
Silanols are key players on application performance of zeolites; yet, their localization and hydrogen bonding strength need more studies. The effects of post-synthetic ion-exchange on nanosized chabazite (CHA), focusing on the formation of silanols, was studied. The significant alteration of the silanols of the chabazite nanozeolite upon ion-exchange and their effect on the CO 2 adsorption capacity was revealed by solid-state nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) spectroscopy, and periodic density functional theory (DFT) calculations. Both theoretical and experimental results revealed changing the ratio of extra-framework cations in CHA zeolites changes the population of silanols; decreasing the Cs + /K + ratio creates more silanols. Upon adsorption of CO 2 the distribution and strength of the silanols also changed with increased hydrogen bonding, thus revealing an interaction of silanols with CO 2 molecules. To the best of our knowledge, this is the first evidence of the interplay between alkali-metal cations and silanols in nanosized CHA.
Origine : Fichiers éditeurs autorisés sur une archive ouverte