Equilibrium and dynamic adsorption characteristics of zeolite 5A, LiX, 13X and MOF UTSA-16 adsorbents for hydrogen purification

Zeolite materials are widely used as adsorbents in pressure swing adsorption (PSA) technology for hydrogen purification, particularly excelling in removing weakly adsorbed gases such as N2 and CO. The selection of zeolite materials is crucial for enhancing the performance of hydrogen purification. This study investigates the adsorption capacity, selectivity and working capacity of three widely used zeolite adsorbents (5A, LiX and 13X) and a zeolite-like material (UTSA-16) for hydrogen purification from steam methane reforming off-gas (SMROG), composed of H2/CO2/CH4/CO = 73/16/8/3 mol%. The results indicate that, based on adsorption isotherms, Zeolite LiX exhibits the strongest adsorption capacity for CH4 and CO. From the perspective of selectivity, LiX demonstrates the highest S(CO2+CH4+CO)/H2 value, making it preliminarily identified as an ideal adsorbent for hydrogen purification. In terms of working capacity, UTSA-16 shows the highest working capacity for CO2 and CH4, making it more suitable for scenarios involving the removal of CO2 in layered adsorption bed designs, while 13X exhibits the highest working capacity for CO. To further evaluate the dynamic performance of these adsorbents for hydrogen purification, the adsorption, heat and mass transfer model for multi-component gas mixtures was established by Aspen Adsorption software. The simulation results align well with experimental data. In the analysis of the dynamic adsorption characteristics of typical SMROG mixtures, a comparison of the dimensionless breakthrough times (τbreak) for CO and CH4 on various adsorbents reveals the following order: LiX >13X > 5A > UTSA-16. Based on this dynamic performance indicator, Zeolite LiX is regarded as the material with the best overall performance among the four adsorbents. By analyzing the equilibrium and dynamic adsorption characteristics in terms of selectivity, working capacity and dynamic breakthrough curve, this study not only elucidates the adsorption behavior of different adsorbents in multi-component gas separations but also provides theoretical insights and practical guidance for optimizing adsorbent selection in PSA systems.