Simulation of CO₂ adsorption-separation from an N₂/CO₂ gas mixture in a fixed Mg-MOF-74 column

A computational study of adsorption-separation of CO₂ from an N₂/CO₂ gas mixture is presented in this paper. A detailed one-dimensional, transient mathematical model has been formulated to include the heat and mass transfer, the pressure drop and multi-component mass diffusion. The model has been implemented on a MATLAB program using second order discretisation. Validation of the model was performed using a complete experimental data set for carbon dioxide separation using activated carbon. Simulation of the adsorption breakthrough experiment on fixed bed has been carried out to evaluate the capacity of Mg-MOF-74 for CO₂ capture with varying feed gas temperature of 301 K, 323 K, 373 K and 423 K. The results show the superiority of MOF adsorbent in comparison to activated carbon. The simulated breakthrough time for CO₂ on Mg-MOF-74 with feed temperature and pressure of 301 K and 1.02 bar respectively is about 500 min as compared to 50 min for activated carbon. The amount of CO₂ adsorbed on Mg-MOF-74 under this condition is 6.43 mole per kilogram of adsorbent. The maximum temperature exhibited in the system is at the bed exit with a value of about 356 K after about 500 min of simulation.