Highly Selective Molecular-Sieving Membranes by Interfacial Polymerization for H ₂ Purification

Hydrogen purification is challenging due to the high energy consumption of current state-of-the-art pressure swing adsorption and cryogenic partial-condensation processes. Membrane separations have the potential to substantially reduce the energy and operational costs of this process. In this study, molecular-sieving polyamide TFC membranes with outstanding H2 selectivities were fabricated via a simple interfacial polymerization process with a variety of different monomers. These membranes showed a greatly improved degree of cross-linking and exhibited pure-gas H2/N2 and H2/CO2 selectivities of up to 507 and 80, with a H2 permeability/permeance of 26 Barrer/10 GPU at 35 °C, demonstrating significantly higher selectivity than most polymeric membranes. The high gas permeabilities observed are explained theoretically by using extensive all-atom molecular dynamics simulations, followed by grand canonical Monte Carlo and trajectory extending kinetic Monte Carlo simulations. The simple and inexpensive membrane fabrication process and its outstanding selectivity performance show progress of these membranes toward large-scale and cost-effective hydrogen purification.