In Silico Study of CO, CO₂, and CH₄ Adsorption on M‑MOF-74 (M = Mg, Zn, Cu)

This work uses density functional theory, implemented in the Gaussian 09 and Quantum ESPRESSO software packages, to evaluate the gas adsorption capability of the M-MOF-74 (M = Mg, Zn, Cu) series for carbon-containing gases (CO, CO₂, and CH₄). Gravimetric analysis reveals that Mg-MOF-74 exhibits the highest adsorption capacities, 14.6 mmol/g for CO, 10.9 mmol/g for CO₂ and CH₄. These correspond to mass ratios of 0.41, 0.48, and 0.18, respectively, indicating that a gram of Mg-MOF-74 can adsorb 0.41 g of CO, 0.48 g of CO₂, and 0.18 g of CH₄. Zn-MOF-74 shows moderate performance with adsorption capacities of 12.8 mmol/g for CO and 9.6 mmol/g for both CO₂ and CH₄, corresponding to mass ratios of 0.36, 0.42, and 0.15, respectively. Cu-MOF-74 demonstrates the lowest adsorption capacities, 9.6 mmol/g for CO, and only 3.2 mmol/g for CO₂ and CH₄, corresponding mass ratios are 0.27, 0.14, and 0.05. Additionally, all MOFs show increased structural stability with higher gas adsorption, indicating increased structural stability upon saturation.