Recent advances in catalysts, palladium alloys and high temperature WGS membrane reactors: A review

• The evolution of catalysts for the WGS reaction in membrane reactors is analyzed.
• The inhibition and poisoning effects on H2 permeation through Pd membranes are reviewed.
• Reactors with tubular non-catalytic and planar catalytic membranes are compared.

There is an increasing demand for pure H2 (CO < 10 ppm) to be used in low temperature PEM fuel cells. This puts pressure on the development of alternative routes to purify the hydrogen that is produced in reformers using feedstocks such as natural gas and ethanol. A good option is the water gas shift reaction conducted in a membrane reactor to obtain ultrapure hydrogen. This contribution critically reviews the developments that took place in this decade concerning more efficient, selective, long-lasting catalysts that do not catalyze the formation of methane, graphitic and carbonaceous residues. The membranes, highly selective to hydrogen with high permeability and resistant to poisonous gases, particularly H2S, are also critically reviewed. Also included in this analysis are the different types of membrane reactors most commonly used.