COMPARISON OF ACTIVATED CARBON AND ZEOLITE 13X FOR CO2 RECOVERY FROM FLUE-GAS BY PRESSURE SWING ADSORPTION

For the recovery of high purity CO2, two adsorbents, zeolite 13X and a ctivated carbon, are examined. Pressure swing adsorption (PSA) cycle s imulations are performed to compare the performance of different adsor bents in separation from two feed mixtures: 16/84 (v/v) CO2/N-2 and 26 /74 CO2/N-2. Despite high-temperature excursions in the adsorption ste p, zeolite 13X is a better adsorbent than activated carbon in nonisoth ermal, adiabatic PSA process due to favorable isotherm shape and equil ibrium selectivity. Moreover, a higher temperature excursion for 13X d uring the product (CO2) purge step reduces the purge gas amount and th is actually helps PSA performance. High purity of CO2 (over 99%) can b e produced by zeolite 13X at higher recoveries (53% from low-CO2-conce ntration flue gas and 70% from high-CO2-concentration flue gas) and hi gher productivities than carbon. In selecting an appropriate adsorbent , high working adsorption capacity, high equilibrium selectivity, and low purge gas requirement dominate the separation by PSA process where as the heat effects play a secondary role. A simple criterion is propo sed for a priori adsorbent selection.