Carbon Dioxide and Nitrogen Adsorption on Cation-Exchanged SSZ-13 Zeolites

Samples of high-silica SSZ-13, ion exchanged with protons and alkali-metal cations Li⁺, Na⁺, and K⁺, were investigated using adsorption isotherms of CO₂ and N₂. The results show that Li-, Na-SSZ-13 have excellent CO₂ capacity at ambient temperature and pressure; in general, Li-SSZ-13 shows the highest capacity for N₂, CO₂ particularly in the low-pressure region. The effect of cation type and Si/Al ratio (6 and 12) on the adsorption properties was investigated through analysis of adsorption isotherms and heats of adsorption. The separation of CO₂ in a flue gas mixture was evaluated for these adsorbents in the pressure swing adsorption and vacuum pressure adsorption processes.