Equilibrium CO2 adsorption on zeolite 13X prepared from natural clays

[Display omitted] •Zeolite 13X was successfully synthesized by hydrothermal treatment using natural kaolin, natural bentonite and natural feldspath.•The optimum conditions of synthesis zeolite 13X were found to be NaOH concentration=4M and crystallized at 65°C for 72h after homogenization by agitated at room temperature for 120h.•The prepared zeolite 13X from natural kaolin (13X-K) showed a high BET surface area of 591m2/g and high micropore volume (0.250cm3/g) than other materials in this study.•The adsorption behavior of carbon dioxide and methane on zeolite 13X sample at different temperature from 298K to 328K was investigated.•It was found that the Langmuir–Freundlich model was more suitable than the others for description of CO2 adsorption isotherms. Zeolite 13X was successfully synthesized by hydrothermal treatment using natural clays extracted from Iranian resources. The preliminary natural materials and the final zeolite 13X samples were characterized by X-ray Diffraction (XRD), Fourier-Transfer Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and N2 adsorption–desorption isotherm. The effects of various factors such as NaOH addition amount and aging time on the crystalline products were studied during the synthesis process. The optimum conditions related to the synthesis of zeolite 13X were set. Accordingly, NaOH concentration was equal to 4M. It was further crystallized at 65°C for 72h after its homogenization by agitation at room temperature for 120h. In this study, the zeolite 13X prepared from natural kaolin (13X-K) showed a high BET surface area of 591m2/g with higher micropore volume (0.250cm3/g) than other materials. Adsorption equilibrium isotherms of CO2 were investigated using a static, volumetric method. In addition, pressures for the pure component data extended up to 20bar. The adsorption equilibrium data of CO2 was fitted to Langmuir, Freundlich, Lamgmuir-Freundlich, Toth and BET isotherm models. It was found that the Langmuir-Freundlich model was more suitable than other models for CO2 description. The results showed that the synthetic zeolite has higher equilibrium selectivity for CO2. Also, the CO2 uptake by zeolite 13X-K was equal to 6.9mmol/g.