Nanostructured Faujasite Zeolites for Carbon Dioxide Adsorption

Carbon capture is an essential way to reduce greenhouse gas emissions. One way to decrease the emissions is through the use of adsorbents such as zeolites. The experimental nanostructured faujasite (NaX) zeolite received from Dr.Dong-Kyun Seo’s group (School of Molecular Sciences, Arizona State University) has a higher CO₂ capacity, 4.0 mol/kg at 298 K and 0.1 bar, than the conventional NaX zeolite. The new NaX zeolite was characterized and the physisorption properties were determined with ESEM. ASAP 2020 tests of the nano-zeolite pellets at 77K in a liquid N₂ bath determined the BET surface area of 617.0477 m³/mol, the T-plot micropore volume of 0.279146 cm³/g, and the adsorption average pore width of 2.07177 nm. The adsorption isotherm (equilibrium) of CH₄, N₂, and CO₂ were measured at 25ºC. Breakthrough experiments were performed in an alumina fixed, packed bed of a length of 22 inch, 0.5 inch column i.d. at 1 atm and 298 K with nano-zeolite pellets. The gas chromatographer tested and recorded the data every two minutes with a flow rate of 10 cm³/min for N₂ and 10 cm³/min CO₂. breakthrough simulations of the powder and pellet form of the zeolite in an alumina tube fixed bed adsorber column were conducted on MATLAB. A linear isotherm was used for N₂, and CH₄, while the Langmuir and Freundlich adsorption isotherms were used for CO₂. It was found that the Langmuir isotherm was more accurate than the Freundlich isotherm for CO₂. The simulations determined the ideal adsorbed solution theory (ISAT) calculations, and the breakthrough curve at various CO₂, N₂, and CH₄ feed ratios. At 20ºC the zeolite capacity for CO₂ is 5.729 mmol/g, 0.82265 mmol/g for CH₄, and 0.39603 mmol/g for N₂. The new NaX zeolite’s capacity for CO₂ is greater than the conventional NaX zeolite. The nanostructured faujasite zeolite appears to be a very promising adsorbent for CO₂/N2 capture from flue gas, CO₂/CH₄ natural gas purification, and the separation of CO₂/N₂ and CO₂/CH₄ .