Permeability, selectivity, and testing of hydrogen diffusion membranes suitable for use in steam reforming

Three composite hydrogen-permeable membranes were produced by the electrole ss deposition of palladium on macroporous Inconel. The permeability and sel ectivity for hydrogen to argon was assessed over the range 750-850 degreesC using a 156-mum-thick membrane. The permeability coefficient was 1.874 x 1 0(-6) mol/(m s kPa(0.5)), with an activation energy of 22.6 kJ/mol. Membran es produced by the electroless technique exhibited hydrogen/argon molar sel ectivities in the range (336-1187):1. Two membranes were used to assess the effect of hydrogen permeation on the conversion of methane over a 20 wt % Ni/alpha -alumina catalyst in a CREC riser simulator used to model a fast f luidized bed. Hydrogen permeation from the reactor produced conversions in excess of those attainable at equilibrium and favorably modified the compos ition of the synthesis gas.