Enhancement of the CO2 Retention Capacity of Y Zeolites by Na and Cs Treatments: Effect of Adsorption Temperature and Water Treatment

Adsorption of carbon dioxide on parent and alkaline-modified Y zeolites was investigated by temperature-programmed desorption (TPD) analysis of these materials previously saturated with CO2 at different temperatures (50−200 °C). Parent zeolite was treated with different sodium and cesium aqueous solutions, using both carbonates and hydroxides as precursors. Morphological, crystallographic, and chemical properties of these materials were determined by nitrogen physisorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), and NH3-TPD. Slight desilication phenomena were observed when hydroxides were used as precursors, whereas the treatment with Cs salts leads to higher crystallinity losses. Several successive adsorption−desorption cycles were carried out in order to check the stability of the adsorbents. Both Cs treatments lead to an enhancement of the retention capacity when adsorption is carried out at the highest temperatures (100−200 °C), whereas Na treatments hardly affect adsorption properties of the parent material. The evolution of the retention capacity of carbon dioxide after water adsorption−desorption was also studied. It was observed that water pretreatment enhances the adsorption capacity of the Cs-treated zeolites.