Adsorption equilibria and kinetics of CO 2 and N 2 on activated carbon beads

Abstract

Knowledge of adsorption equilibria and kinetics of pure gases is required for designing an adsorption process for a new material that can be scaled-up to large amounts. In this work, adsorption equilibrium data of CO 2 and N 2 on pitch-based activated carbon (AC) beads at 303, 333, 363, 393, and 423 K ranging from 0 to 100 kPa and at 303, 333 K ranging from 0 to 4000 kPa were presented. The adsorption capacity is 1.918 mol/kg for CO 2 and 0.270 mol/kg for N 2 at 303 K and 100 kPa. The full set of data was fitted with both Virial adsorption equation and multisite Langmuir model. The diffusion of single gases in the microporous structure of AC beads was studied by diluted breakthrough experiments performed over the same temperature range of 303–423 K. A mathematical model was employed in the simulation of breakthrough curves. It was determined that for CO 2 and N 2, the controlling mechanism is micropore diffusion. The micropore diffusivity constant ( D c / r c 2 ) for carbon dioxide and nitrogen obtained at 303 K is 1.058 × 10 −2 and 7.185 × 10 −2 s −1, respectively. The data reported in this work allows modeling of any adsorption processes with this new material.