Adsorption of methane and nitrogen on Basolite MOFs: Equilibrium and kinetic studies

Abstract

Abstract The adsorption/desorption behaviour of methane and nitrogen on three different Metal Organic Frameworks (MOFs) was studied in this work. The objective was to obtain new insights into the adsorption process of both molecules, since the similarity in the sizes of methane and nitrogen hinders the methane recovery from lean methane-containing emissions using adsorption technologies. In that way, the capacity of adsorption of methane and nitrogen was measured on Basolite C300, Basolite F300 and Basolite A100, being remarkable the Cu interaction of the Basolite C300 with the methane, as it was deduced from both the capacity and the heat of adsorption. Evaluation of the kinetic models of adsorption leads to observe the best fitting of the Langmuir and the fractional order models. For both adsorbates, the adsorption is easier than desorption on the surface of the three materials. The main differences observed among the adsorbents were the faster adsorption of both gases on Basolite A100, as well as the larger dependence on the occupied adsorption sites. Likewise, different adsorption isotherms were used for modelling the equilibrium results obtained, Freundlich and Sips isotherms providing the best results. These facts highlight the key role of certain surface heterogeneities on the adsorption capacity. Furthermore, parameters of both the adsorption isotherms and the kinetic models could explain the differences among the adsorbents in the adsorption and desorption performance, highlighting the utility of the proposed models.