Extraction of ultrapure hydrogen with V-alloy membranes: From laboratory studies to practical applications

The membranes of vanadium alloys can be substantially more productive and much cheaper than the palladium alloy membranes which are widely used for hydrogen separation. However, the insufficient workability of vanadium alloys makes difficult producing the membranes of any shape, except for small thick flat samples, suitable only for laboratory studies, while membranes in the form of thin-walled tubes are most preferable for practical use. Such seamless thin-walled self-maintained membranes of tubular shape, made of V-Pd and V-Fe alloys with a thin Pd-coating on their inner and outer sides and with welded joints to stainless steel on both ends, were fabricated and tested for their throughput, service life, mechanical stability, and capability of hydrogen recovering from WGS mixtures. In view of reliable and highly productive operation of tubular V-alloy membranes as well as of their absolute selectiveness, the assembly from 18 membranes was fabricated to use it in the multi-fuel processor feeding a 1 kW PEM FC and providing up to 16 slpm of ultrapure hydrogen by the steam conversion of light and heavy hydrocarbons including diesel “Euro 5”. A similar assembly made of V-Fe alloy membranes was estimated for hydrogen purification in MOCVD applications.