Adsorption and Desorption of Carbon Dioxide and Nitrogen on Zeolite 5A

The adsorption equilibrium data of CO2 and N2 at (303, 333, 363, 393, 423) K ranging 0-1bar on zeolite 5A is reported. The pressure and temperature range covers the operating pressure in adsorption units for CO2 capture from power plants. Experimental data were fitted by the multi-site Langmuir model. The adsorbent is much more selective to CO2: loading at 303K and 100kPa is 3.38mol/kg while loading of N2 at the same pressure is 0.22mol/kg. The Clausius-Clapeyron equation was employed to calculate the isosteric enthalpy of adsorption. The fixed-bed adsorption and desorption of carbon dioxide and nitrogen on zeolite 5A pellets has been studied. A model based on the bi-LDF approximation for the mass transfer, taking into account the energy and momentum balances, had been used to describe the adsorption kinetics of carbon dioxide and nitrogen. The model predicted satisfactorily the breakthrough curves obtained with carbon dioxide-nitrogen mixtures. Desorption process (consisting of depressurization, blowdown, and purge) was also performed. Following the feasibility of concentration and capture of carbon dioxide from flue gases by Pressure Swing Adsorption (PSA) process was simulated. A CO2 recovery of 91.0% with 53.9% purity was obtained using a five-step Skarstrom-type PSA cycle.