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The Origin of Selective Adsorption of CO 2 on Merlinoite Zeolites
Author(s) -
Choi Hyun June,
Jo Donghui,
Min Jung Gi,
Hong Suk Bong
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202012953
Subject(s) - adsorption , chemistry , zeolite , chemical engineering , inorganic chemistry , catalysis , organic chemistry , engineering
The CO 2 adsorption behavior at 25–75 °C and 0–1.0 bar of various alkali cation‐exchanged forms of merlinoite (framework type MER) zeolites with Si/Al=2.3 and 3.8 is described. The adsorption isotherms at 25 °C on the Na + , K + , Rb + , and Cs + forms of MER zeolite with Si/Al=2.3 are characterized by a clear step, the CO 2 pressure of which differs notably according to the type of their extraframework cations. Structural analysis shows that CO 2 adsorption on the former three zeolites includes the relocation of gating cations with high site occupancy and the remarkable concomitant structural breathing. We define this unusual adsorption phenomenon as a cooperative cation gating‐breathing mechanism. The overall results suggest that the actual mechanism of selective CO 2 adsorption on intermediate‐silica small‐pore zeolites can change from cation gating to cooperative cation gating‐breathing to breathing, depending on a combination of their topological and compositional flexibilities.