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 .