Synthesis of tungstates/Ni0.5Cu0.5O nanocomposite materials for hydrogen separation cermet membranes

In this work mixed protonic-electronic conducting nanocomposites comprised of Mo or La doped Nd5.5WO11.25-delta and Cu0.5Ni0.5O were prepared by mechanical mixing in a high energy mill and sintering at 1100 degrees C using either conventional thermal sintering in the furnace or hot pressing in argon atmosphere. Their structural features were characterized by XRD, SEM, TEM with EDX analysis, IR and Raman spectroscopy. Electrical conductivity was measured by Van der Pauw techniques varying the temperature in dry and wet atmospheres. The oxygen mobility was studied by the oxygen isotope heteroexchange with (CO2)-O-18. Successful test of membrane with permselective Nd5.5WO11.25-delta + Cu0.5Ni0.5O layer supported on NiAl foam substrate and covered by a porous layer of Ru + Ni/ Sm0.15Pr0.15Ce0.35Zr0.3O2-delta catalyst showing promising performance in hydrogen separation from products of ethanol steam reforming has been carried out. The results indicated that a maximum hydrogen permeation flux of 0.033 ml min(-1) cm(-2) was achieved at 900 degrees C using 10% ethanol with 40% of H2O/Ar as feed gas and dry high purity argon as sweep gas.