Ideal Adsorbed Solution Theory (IAST) of Carbon Dioxide and Methane Adsorption Using Magnesium Gallate Metal-Organic Framework (Mg-gallate)

Ideal Adsorbed Solution Theory (IAST) is a predictive model that does not require any mixture data. In gas purification and separation processes, IAST is used to predict multicomponent adsorption equilibrium and selectivity based solely on experimental single-component adsorption isotherms. In this work, the mixed gas adsorption isotherms were predicted using IAST calculations with the Python package (pyIAST). The experimental CO(2) and CH(4) single-component adsorption isotherms of Mg-gallate were first fitted to isotherm models in which the experimental data best fit the Langmuir model. The presence of CH(4) in the gas mixture contributed to a lower predicted amount of adsorbed CO(2) due to the competitive adsorption among the different components. Nevertheless, CO(2) adsorption was more favorable and resulted in a higher predicted adsorbed amount than CH(4). Mg-gallate showed a stronger affinity for CO(2) molecules and hence contributed to a higher CO(2) adsorption capacity even with the coexistence of a CO(2)/CH(4) mixture. Very high IAST selectivity values for CO(2)/CH(4) were obtained which increased as the gas phase mole fraction of CO(2) approached unity. Therefore, IAST calculations suggest that Mg-gallate can act as a potential adsorbent for the separation of CO(2)/CH(4) mixed gas.