Pressure swing adsorption for CO2/N2 and CO2/CH4 separation: Comparison between activated carbons and zeolites performances

Objectives of this work are to evaluate performances of low cost CO2 adsorbents: such as selectivity, adsorption capacity and reusability. Various samples of activated carbons (ACs) and zeolites were bought and tested for the study of CO2 adsorption by pressure modulation. Comparison between these materials was made based on the following criteria: adsorption equilibrium, regeneration capacity and aging. Adsorption of pure CO2 was tested first. Adsorption equilibrium was determined in a temperature range of [0 degrees C-75 degrees C] and a pressure range of [0.4 bar-8 bar]. In a second part gas, binary mixtures containing CO2 were tested: N-2-CO2 80%-20% and CH4-CO2 50%-50%. Cycle repetition and material aging were studied during separation process. The main advantage of ACs is its full reversibility after regeneration by pressure modulation. At pressure above 4 bars, the adsorption capacities of ACs are greater than those of zeolites. In the case of gas separation, results indicate that it is possible to obtain a fairly pure gas during the adsorption phase for the two studied mixtures. In particular it was observed that for the CH4-CO2 mixture the adsorption yielded an efficient separation with a concentration of more than 95% of CH4 in the purified gas. (C) 2015 Elsevier B.V. All rights reserved.