Vacuum Pressure Swing Adsorption for Hydrogen Purification with Zeolite 5A.

Pressure swing adsorption (PSA) is widely used for gas purification, and its performance depends strongly on the adsorbent properties and the cycle design. This study presents a protocol for hydrogen purification using a two-bed vacuum pressure swing adsorption (VPSA) system with zeolite 5A as the adsorbent. The procedure outlines how breakthrough experiments are conducted to support cycle design and explains the key considerations to ensure reliable operation under non‑isothermal and adiabatic conditions. Both breakthrough and VPSA experiments were performed to evaluate the separation performance of zeolite 5A for a H2/CO2 70/30 vol% gas mixture. The results show clear temperature variations within the adsorbent bed due to the exothermic heat of CO₂ adsorption, confirming the non‑isothermal nature of the process. Data analysis is performed for the last 10 cycles once steady‑state operation is achieved. The results highlight the potential to achieve high‑purity hydrogen when the VPSA cycle is designed correctly. The VPSA cycle performed in this study, with a 150 s adsorption step time and 40 s evacuation and purge step, achieves a 97% H2 purity and 80% H2 recovery. However, achieving high-purity hydrogen requires rigorous regeneration and purge steps, which reduce overall recovery, explaining the typical trade-off between purity and recovery in the PSA system. Overall, this work provides a detailed experimental protocol for VPSA hydrogen purification and emphasizes the importance of integrating adsorbent behavior, breakthrough data, and cycle design when developing adsorption‑based separation processes.