Methane Adsorption on Fе–BDC Metal–Organic Porous Structures at High Pressures

Abstract

The isotherms of absolute methane adsorption in an Fe–BDC metal–organic porous structure after long-term storage were measured at a pressure as high as 40 MPa and the temperatures of 303, 313, 323, and 333 K. The dependences of differential molar isosteric heats of adsorption and entropies of adsorption on methane uptake were calculated. It was shown that taking into account the nonideality of a gaseous phase and steepness of the isotherm of adsorption leads to a temperature dependence of thermodynamic functions of adsorption. Both a sharp drop in the heat of adsorption and a local maximum of the entropy at the maximum values of methane uptake are indicative of rearranging the adsorbate structure and the probable formation of molecular methane associates in micropores.