Temperature-regulated gas adsorption on LTA zeolites: Observation of sorption isotherms for methane, hydrogen, nitrogen and carbon dioxide

[Display omitted] •Adsorption of H2, CO2, N2, and CH4 were investigated with zeolites LTAs.•Zeolite 5A provides the highest uptake H2, N2, and CH4 capacity.•Zeolite 3A exhibits a temperature-dependent behaviour with H2.•Zeolite 4A shows similar temperature-dependent adsorption with N2.•With 3A and 4A, a temperature swing method can be used separate H2/CO2 gas mixtures. Temperature-regulated gas adsorption of various zeolite LTAs with different cations of Cs2+, K+, Na+, and Ca2+ (namely, Cs-A, 3A, 4A, and 5A) was analysed in the presence of different gas molecules of H2, CO2, N2, and CH4 for pressures up to 800 kPa and temperatures ranging from 77.15 to 363.15 K. Over the range of test conditions, zeolite 5A (containing Ca2+ cations) exhibited the highest uptake at 800 kPa for CO2, H2, CH4, and N2, with capacity values of 5.69 mmol.g−1, 1.14 mmol.g−1, 6.60 mmol.g−1, and 6.10 mmol.g−1, at 298.15 K and 201.15 K respectively. Zeolite 4A (containing Na+ cations) exhibited 0.74 mmol.g−1 for H2 adsorption at 201.15 K, and 800 kPa. In contrast, pores were inaccessible to H2 on ion-exchange Cs-A zeolite at a temperature range of 77.15–343.15 K, due to larger cation Cs2+ (CsA) comparison with Na+ (4A). Interestingly, zeolite 3A (containing K+ cations) showed a negligible capacity for the larger gas molecules, CH4 and N2, ascribed to the pore space blocked by the larger K+ cations (relative to the smaller Na+ and Ca2+ cations). Zeolite 3A exhibited a temperature-dependent behaviour (i.e., presumably a “trapdoor” effect) with H2 wherein adsorption was negligible at 77.15 K, but was significant above approximately 200 K. For N2, zeolite 4A exhibits similar temperature-regulated adsorption characteristics (i.e., presumably a “trapdoor” mechanism as well). These zeolite materials used in various temperature swing processes could be particularly beneficial in natural hydrogen production (with H2/N2 separation with 3A), the production of synthetic fuels from CO2/H2 mixtures (with both 3A and 4A), CO2 capture from waste streams, and applications for H2/N2 separation.