Comparative performance of commercial polymeric membranes in the recovery of industrial hydrogen waste gas streams

The application of membrane separation processes to industrial hydrogen-rich waste gases promotes the efficient recovery of this clean fuel. The first step to address and overcome this waste of resources is to assess the real performance of commercially available polymeric membranes for hydrogen separation in terms of hydrogen purity that meets the quality standards to be used in hydrogen-based applications. Therefore, this work makes a comparison of the performance of commercial flat hydrogen-selective membranes based on non-porous polymeric materials through the experimental assessment in a lab-scale set up that contains a gas permeation cell with the aim of recovering hydrogen from the most suitable multicomponent waste gaseous streams. To assess the mixed-gas permeation performance, the influence of the feed gas composition, temperature and pressure was examined. The results of experimental tests indicated that there is a strong dependency of H₂ permeability on CO₂ concentration, that induces a decay of H₂/CO₂ selectivity in mixed-gas experiments for the membranes under study. Accordingly, the permeability-selectivity trade-off in the state-of-the-art membranes defines the balance between H₂ recovery and the product purity. Finally, it is worth noting that although H₂ purities obtained are higher than 98% vol. H₂ for APG and COG mixtures, which may indeed be used as a commodity chemical in many industrial processes, they are still far from fuel cell requirements.