Adsorption Selectivity of CO2 and CH4 on Novel PANI/Alkali-Exchanged FAU Zeolite Nanocomposites

Adsorption capacity and selectivity of carbon dioxide (CO2) and methane (CH4) in faujasite (FAU)-type zeolites NaX and NaY have been studied by employing a volumetric measurements at 298, 323, and 348 K and a pressure range up to 5 bar. Ion exchange was performed on FAU zeolites with alkali metal cations Li+ and K+. The alkali-exchanged zeolitic adsorbents were characterized by scanning electron microscopy, X-ray diffraction and N-2 adsorption/desorption isotherms. CO2 is highly adsorbed than CH4 on alkali-exchanged zeolites. The adsorption capacity of CO2 in alkali-exchanged zeolites decreases with increase in the cationic radius, while for CH4 the adsorption capacity increases with increase in the extra framework cationic radius. The novel zeolitic nanocomposites (Li-FAU) were prepared by adding polyaniline (PANI) to the LiX and LiY with different weight percentages p% (p = 10, 20, 30 and 40%). The PANI/Li-FAU zeolite nanocomposites show higher adsorption capacity for CO2 and selectivity of CO2/CH4 against the Li-FAU zeolites at different pressures. The maximum selectivity was observed at lower pressures at 298 K for LiX/PANI-40.