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.