Equilibrium Adsorption Study of CO₂ and N₂ on Synthesized Zeolites 13X, 4A, 5A, and Beta

This study focused on comprehensive synthesis and analysis for CO₂ adsorption of the widely used zeolites 13X, 4A, 5A, and beta. Zeolites were synthesized utilizing the hydrothermal method. We paid special attention to the characterization of synthesized zeolites. The most common instrumental analysis techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), differential thermal gravimetry (DTG), differential thermal analysis (DTA), and X-ray fluorescence (XRF), were utilized in this study. All results indicated the successful synthesis of these types of zeolites. The CO₂ /N₂ system was considered for the investigation of adsorption and separation of CO₂. The adsorption equilibrium data of CO₂ and N₂ on pelletized zeolites were taken at temperatures of 283, 303, and 323 K and pressures up to 1.6 bar utilizing a volumetric method. The highest adsorption capacity was obtained for zeolite 13X and the lowest for zeolite beta. The Sips and Langmuir isotherm models were used for matching adsorption isotherm data. Experimental data showed the best correlation with the Sips model with six parameters. The isosteric heats of adsorption for CO₂ and N₂ on all the studied adsorbents were evaluated utilizing the pure adsorption isotherms data at studied temperatures by the Clausius-Clapeyron equation. Also, binary adsorption data and selectivities of CO₂ over N₂ on all adsorbents were determined by ideal adsorbed solution theory (IAST). It can be concluded from all the obtained results that the studied zeolites, especially zeolite 13X, can be promising adsorbents to capture CO₂ in practical applications.