Comprehensive Analysis of O₂ and N₂ Adsorption on Kaolin-Derived Zeolites: Experimental and Computational Insights

This study investigated the N2 and O2 adsorption behavior on SAPO-34 and 13X zeolites synthesized from kaolin. Molecular dynamics simulations and grand canonical Monte Carlo (GCMC) calculations were used to simulate the adsorption properties of zeolites. The zeolites were synthesized using Iranian kaolin, and their adsorption behavior was studied across a range of temperatures (288–318 K) and pressures (1–9 bar). The highest N2 and O2 adsorption capacities were observed at 288 K and 9 bar, with SAPO-34 reaching 4.9 and 6 mmol g–1 and 13X reaching 6.8 and 5 mmol g–1, respectively. The efficacy of these adsorbents was assessed at 288 K and 9 bar, with a feed composition of O2/N2 (0.5/0.5, %v/v), utilizing the ideal adsorption solution theory (IAST). The findings emphasize the outstanding ability of SAPO-34 to selectively adsorb oxygen over nitrogen with a remarkable selectivity coefficient of 22.57. Furthermore, isotherm, kinetic, and thermodynamic models were used to study the adsorption behavior. The Sips model was identified as suitable, and the adsorption mechanism was suggested to be multilayered. Kinetic models confirmed physisorption occurrence, while thermodynamic analysis indicated an exothermic and spontaneous adsorption mechanism. Zeolite regeneration over five cycles showed a minimal decrease in adsorption efficiency (3–4%, from 100% to 96%), highlighting the method’s promise for eco-friendly and cost-effective adsorbents.