(42h) Temperature-Regulated Gas Adsorption on Zeolite Ltas: Observations of Sorption Isotherms for Methane, Hydrogen, Nitrogen, and Carbon Dioxide

Zeolites, renowned for their high porosity and chemical stability, play a crucial role in pressure/temperature swing adsorption processes. Among these, Zeolite type A (Linde type A or LTA) stands out as a promising candidate for gas separation due to its chemical and thermal stability, versatile structure modifiable via ion exchange, and cost-effectiveness. This study investigates the temperature-regulated gas adsorption of zeolite LTAs with various framework cations, including K⁺ (3A), Na⁺ (4A), and Ca²⁺ (5A). Gas adsorption equilibrium of H₂, CO₂, N₂, and CH₄ on different zeolite LTAs (3A, 4A, and 5A) was explored using the volumetric method under pressures up to 800 kPa and temperatures ranging from 77 K to 363.15 K. The uncertainties associated with these gas adsorption measurements were carefully examined, and the data were fitted to the Toth, Langmuir, and LJM-Toth models. Zeolite 3A exhibited a negligible capacity for larger gas molecules such as CH₄ and N₂, attributed to pore blockage by larger K⁺ cations compared to Na⁺ and Ca²⁺ cations. Additionally, zeolite 3A displayed temperature-dependent adsorption of H₂, wherein gas molecule accessibility to the interior pores decreased at lower temperatures. A similar effect was observed in the adsorption of CH₄ and N₂ on zeolite 4A, where the adsorption of these gases was impacted and eventually ceased upon lowering the temperature. This temperature-regulated adsorption of 3A and 4A zeolites presents an innovative approach for significant gas separation processes, potentially providing an alternative to energy-intensive cryogenic or absorption-based methods.