Hollow fibre membrane reactors for high H2 yields in the WGS reaction

Alumina hollow fibres with narrow pore size distribution and high surface area/volume ratio are presented as a cost-effective alternative support for metallic membranes which can potentially ease the large-scale implementation of membrane reactors. In this article, we demonstrate the formation of a defect-free thin (∼5 μm) Pd/Ag layer over the smooth outer surface of hollow fibres with high H2 permeation fluxes (48.41 L m−2 h−1 at 450 °C and ΔP0.5 of 1.01 atm0.5) and 100% H2 perm-selectivity. Their use in hollow fibre membrane reactors (HFMR) allows the selective extraction of H2 from the reaction medium, especially relevant in H2-formation equilibrium reactions. Thus, the water-gas shift reaction was used as a proof-reaction. When the HFMR is combined with a highly stable and active nanostructured Pt/CeO2 catalyst, enhanced selectivities and activities are achieved as a result of the integration of the reaction and separation steps. The best results were obtained at high temperatures (375–525 °C) where the thermodynamic equilibrium conversion was exceeded by up to 14%.

► Alumina hollow fibres as an alternative support for thin metallic membranes. ► Formation of defect-free highly permeable Pd/Ag layer with 100% H2 selectivity. ► Hollow fibre membrane reactors (HFMR) to overcome thermodynamic limitations.