Beyond Pure-Gas Permeation: Designing an Efficient Two-Stage Membrane Process for Hydrogen Recovery from Reformate Mixtures

This work presents a comprehensive study on hydrogen recovery from a CO2-containing mixture (75/25 mol %) using commercial polymer membranes. The gas transport properties of polyimide (PI), polysulfone (PSF), polyphenylene oxide (PPO), polyetherimide (PEI), and a PEI + PI composite were evaluated. A significant discrepancy was found between single-gas and mixture permeation data, highlighting the necessity of using mixture-based permeance for accurate process design. The PEI membrane demonstrated the optimal combination of H2/CO2 selectivity (5.07) and permeance. An optimized two-stage membrane process with recirculation was developed using Aspen Plus simulation, achieving a hydrogen purity of 95 mol % with 90% recovery. The techno-economic assessment confirmed the process feasibility, demonstrating a lower cost of hydrogen production compared to traditional methods.