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 (similar to 5 mu m) Pd/Ag layer over the smooth outer surface of hollow fibres with high H-2 permeation fluxes (48.41 L m(-2) h(-1) at 450 degrees C and Delta P-0.5 of 1.01 atm(0.5)) and 100% H-2 perm-selectivity. Their use in hollow fibre membrane reactors (HFMR) allows the selective extraction of H-2 from the reaction medium, especially relevant in H-2-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 degrees C) where the thermodynamic equilibrium conversion was exceeded by up to 14%. (C) 2012 Elsevier B. V. All rights reserved.