Recent advances on membranes and membrane reactors for hydrogen production

Membranes and membrane reactors for pure hydrogen production are widely investigated not only because of the important application areas of hydrogen, but especially because mechanically and chemically stable membranes with high perm-selectivity towards hydrogen are available and are continuously further improved in terms of stability and hydrogen flux. Membrane reactors are (multiphase) reactors integrating catalytic reactions (generally reforming and water gas shift reactions for hydrogen production) and separation through membranes in a single unit. This combination of process steps results in a high degree of process integration/intensification, with accompanying benefits in terms of increased process or energy efficiencies and reduced reactor or catalyst volume. The aim of this review is to highlight recent advances in hydrogen selective membranes (from palladium-based to silica and proton conductors) along with the advances for the different types of membrane reactors available (from packed bed to fluidized bed, from micro-reactors to bio-membrane reactors). In addition, the application of membrane reactors for hydrogen production from different feedstock is also discussed.