Pd–Ag membrane reactors for water gas shift reaction

Abstract Pd–Ag thin wall permeators have been obtained by coating ceramic porous tubes with thin Pd–Ag metal foils (50 μm). A procedure of cold rolling and annealing has been used for producing thin metal foils. These membranes and membrane reactors have been proposed to recover hydrogen (and its isotopes) from tritiated water by using the water gas shift reaction, and by the reverse reaction (CO 2 conversion) for applications in the fusion reactor fuel cycle. The rolled membranes have been tested at 135–360 °C with a hydrogen transmembrane pressure in the range 130–180 kPa and hydrogen flow rates up to 1.02×10 −4  mol s −1 . Both a complete hydrogen selectivity and a good chemical and physical stability have been observed through long-term tests. The tests on the membrane reactors have been carried out at the temperature of 325–330 °C with a feed pressure of 100 kPa; in particular, reaction conversion values close to 100% (well above the equilibrium value, about 80%) have been attained with the water gas shift reaction. These tests have demonstrated their applicability to the fusion fuel cycle as well as to the hydrogenation or dehydrogenation processes involving the use or the production of highly pure hydrogen.