(436e) Development of MOF-74@Zeolite-5A Composite Adsorbents for H2 Purification

Hydrogen is considered as one of the most important clean and renewable energy sources for a sustainable energy future. However, its efficient and cost-effective purification still remains challenging. In this work, we report the development of novel MOF@Zeolite composites comprised of MOF-74 and Zeolite-5A with core-shell structure for efficient purification of H₂. The composites were synthesized hydrothermally through the addition of Zeolite particles with and without carboxyl functional groups to the MOF synthesis solution. The MOF:Zeolite weight ratio was varied systematically to find the optimum composition based on the adsorption performance. The formation of MOF@Zeolite composites was confirmed by various characterization techniques. Single-component adsorption isotherms of CO₂, CH₄, H_2, CO, and N₂ were measured at 298 K and in the pressure range of 0 to 25 bar. The dynamic adsorption measurements were also performed using binary gas mixtures of CO₂/H₂, CH₄/H₂ and N₂/H₂. The selectivity values were estimated using ideal adsorbed solution theory (IAST) and also from breakthrough profiles. The MOF-74@Zeolite-5A with weight ratio of 95:5 exhibited a similar morphology to that of pristine MOF-74 but with a more ordered crystalline structure and higher surface area. Moreover, this composite showed 20-25% increase in CO₂, CH₄, CO, and N₂ uptake and higher selectivity values in comparison to the bare MOF and Zeolite which could be attributed to the formation of new micropores at the MOF-Zeolite interface and also to the enhanced surface dispersive forces of the composite. The experimental adsorption isotherms were well fitted with single-site Langmuir-Freundlich model. Overall, the findings of this study suggest that the MOF-74@Zeolite-5A composites with core-shell structure are promising candidates for industrial H₂ purification processes.