Advanced metal–organic framework materials for efficient CO₂/CH₄ separation using pressure swing adsorption – numerical study

Efficient CO₂ separation from biogas is essential for enhancing methane quality and supporting sustainable energy production. In this study, CO₂/CH₄ separation is investigated using a one-dimensional computational fluid dynamics model implemented in COMSOL Multiphysics and validated against published experimental data for MIL-53(Al). Several metal–organic frameworks, including MOF-303, MIL-160, aluminum fumarate, HKUST-1, and UIO-66, are systematically compared under identical operating conditions. The results demonstrate that MOF-303 exhibits the highest CO₂ selectivity and adsorption capacity, achieving an equilibrium uptake of 12.35 mol/kg at 15 bar and 298 K, significantly outperforming the other investigated materials. Building on this finding, the model is further applied to examine the influence of bed geometry on CO₂ capture using MOF-303. The analysis reveals that increasing bed length while reducing bed diameter substantially enhances adsorption performance, with a maximum uptake of 42.15 kg CO₂ per kg of MOF per day at an optimized geometry. These results demonstrate the combined importance of adsorbent selection and bed design and provide new insights into the optimization of MOF-based PSA systems for high-efficiency biogas upgrading.