Prediction of Binary Adsorption Isotherms of Carbon Dioxide and Methane from Pure Adsorption Data

In the area of adsorption, experimental multicomponent data possess challenges in comparison to pure components. By solely relying on the pure adsorption experiment, a model known as Ideal Adsorbed Solution Theory (IAST) can predict binary adsorption isotherms without requiring any experimental multicomponent data. According to our previous work, Co-gallate exhibited higher CO2 uptakes than CH4 based on pure adsorption isotherms. However, there is a lack of study on the equilibrium isotherms of binary adsorption calculated by IAST for multi CO2/CH4 compositions at different temperature conditions. Therefore, the experimental CO2 and CH4 pure adsorption isotherms were fitted with six analytical models, in which Langmuir model yielded the highest goodness-of-fit. IAST calculations via the Python package were employed to predict the equilibrium isotherms of binary CO2/CH4 adsorption at different compositions and temperatures. The predicted binary adsorption isotherms revealed that CO2 adsorption was more favourable on the surface of Co-gallate than CH4, even though those uptakes were lower than pure adsorption data due to competitive co-adsorption behaviours. Moreover, IAST selectivity suggested that CO2/CH4 separation performed better as the CO2/CH4 compositions approached unity and at lower temperature condition. IAST approach evaluated that Co-gallate can be a promising solid material for CO2/CH4 mixed gas separations.

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