Adsorptive Separation of CO₂ from Multicomponent Mixtures of Flue Gas in Carbon Nanotube Arrays: A Grand Canonical Monte Carlo Study

Grand canonical Monte Carlo (GCMC) simulations have been performed to investigate the adsorption and separation behavior of ternary and quaternary gaseous mixtures of CO₂, along with H₂S, SO₂, and N₂, in bundles of aligned double-walled carbon nanotubes with a diameter of 3 nm and an intertube distance of 0.5 nm. All of the simulations are performed at 303 K and at pressures varying between 0 and 3 bar. The GCMC results are then compared to the ideal adsorbed solution theory (IAST) predictions. For the ternary mixture H₂S–CO₂–N₂, the results show that CO₂ has the highest adsorption among the three components. The IAST predictions agree reasonably well with the GCMC data for the ternary mixture, except for H₂S. For the quaternary mixture H₂S–SO₂–CO₂–N₂, it is observed that initially CO₂ has the highest adsorption up until around 2 bar, whereafter there is a crossover by SO₂ to have the highest adsorption. IAST fails to predict the adsorption behavior of the quaternary mixture involving SO<sub>2