Introduction: CO₂ capture from post-combustion flue gas mixture is challenging and requires adsorbents with high capacity and high selectivity toward CO₂. Zeolites are nanoporous inorganic materials with a regular and open microporous structure composed of a three-dimensional network of [SiO4]4- and [AlO4]5- tetrahedra. It has a great potential for industrial applications due to its possessing excellent properties such as adsorption, ion exchange and catalytic processes.

Methods and Results: Here we report a simple and economical method to synthesis zeolite NaA and zeolite NaX using a hydrothermal method without using any organic template. The molar ratio of about 3.165Na₂O:Al₂O₃:1.926SiO₂:128H₂O and 16Na₂O:Al₂O₃:4SiO₂:325H₂O have been used to prepare for the zeolite NaA and zeolite NaX hydrogel respectively. The crystallinity of the synthesized materials was found to be a cubic structure for both synthesized zeolite hydrogel has been confirmed by X-ray diffraction (XRD). Fourier Transform Infrared Spectroscopy (FTIR) analysis shows the band at 550 cm^-1 and 462 cm^-1 corresponds to the Double four rings (D4R) and Double six ring (D6R) of the synthesized materials. Field Emission Scanning Electron Microscope (FESEM)  morphology revealed the cubic and layer like octahedral of the synthesized samples. The composition of the synthesized material has been identified using Energy Dispersive X-Ray Spectroscopy (EDAX)  which also confirms the purity of the sample and the Si:Al ratio also found to be ~1. The N₂ nitrogen adsorption/desorption shows the type IV adsorption isotherm using Brunauer–Emmett–Teller (BET) method which also confirms the mesoporous nature of the materials. From the adsorption studies, the surface area was found to be 13.158 m²/g and 545.939 m²/g respectively. The pore size of the samples found to be 3.0 nm  and16.5 nm has been obtained using the Barrett-Joyner-Halenda (BJH) analysis. Due to these various properties studied above the zeolite NaA and zeolite NaX materials, it is found to be a suitable candidate for the applications of CO₂ Adsorption. The CO₂ adsorption studies were carried out and they were found to be type I isotherm according to the IUPAC classification criteria.

Keywords: Zeolite NaA: Zeolite NaX; Hydrothermal; CO2 adsorption.