Methane Storage in Prussian Blue Analogues and Related Porous Solids: Nature of the Involved Adsorption Forces

Abstract

Abstract Methane adsorption is possible through three types of interactions: (1) dispersive forces (van der Waals type); (2) polarization of its electron cloud by a positive charge center; (3) induced quadrupole moment by perturbation of the molecule electron cloud through the polarization interaction. This induced quadrupole moment is able to interact with the local electric field gradient. Porous Prussian blue analogues and related zeolite‐like zinc hexacyanometallates appear to have unique features for the evaluation of the relative importance of these adsorption forces for the methane storage in molecular porous materials. Methane adsorption isotherms for T 3 [Co(CN) 6 ] 2 ( T = Mn, Co, Ni, Cu, Zn, Cd) and Zn 3 A 2 [Fe(CN) 6 ] 2 ( A = Na, K, Rb, Cs) were recorded and interpreted. From the obtained adsorption data information on the relative contribution of both electrostatic and dispersive interactions to the adsorption forces was obtained.