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Abstract A new mixed protonic-electronic conducting material, Nd 5.5 W 0.35 Mo 0.5 Nb 0.15 O 11.25-δ (NWMN), was developed by Nb-doping to improve the hydrogen permeability of Nd 5.5 W 0.5 Mo 0.5 O 11.25-δ (NWM). The hydrogen permeation properties and stability of the NWMN were investigated in details. An enhanced hydrogen permeation flux through the NWMN membrane was achieved, which was about 2.5 times as high as that through the un-doped NWM membrane at 800 °C due to the increased ambipolar conductivity. Moreover, the phase structures of the NWMN powder and membrane remained unchanged after the treatment in pure CO 2 and H 2 -containing atmospheres, respectively, which reveals excellent stability of the NWMN powder in CO 2 and H 2 -containing atmospheres. The remarkable stability and improved hydrogen permeability make NWMN promising for the application of hydrogen separation. Highlights • A new H 2 permeable material, Nd 5.5 W 0.35 Mo 0.5 Nb 0.15 O 11.25-δ (NWMN), was developed. • Nb-doping is applied to enhance H 2 permeability of Nd 5.5 W 0.5 Mo 0.5 O 11.25-δ (NWM). • H 2 flux through NWMN membrane is ∼2.5 times as high as that through un-doped NWM. • The NWMN membrane shows excellent stability in CO 2 atmosphere. [ABSTRACT FROM AUTHOR]

Lanthanum tungstates are the kind of attractive mixed proton-electron conductive (MPEC) oxides, which can be used as the hydrogen permeable membrane with almost infinite hydrogen selectivity in dry hydrogen-containing atmosphere theoretically. A series of lanthanum tungstates with different La/W ratios, La 5.3 WO 11.25-δ (LWO53), La 5.4 WO 11.25-δ (LWO54), La 5.5 WO 11.25-δ (LWO55) and La 5.6 WO 11.25-δ (LWO56), were prepared through a solid-state reaction method and the effect of La/W ratio on the membrane structure, stability and hydrogen permeation properties have been investigated. A pure cubic phase can be formed gradually with the increase in calcination temperature for lanthanum tungstates. The phase formation temperature increases with the increase in the La/W ratio, and a higher oxygen absorption capacity can be achieved in lanthanum tungstate with a higher La/W ratio. The hydrogen permeation flux through the lanthanum tungstate membranes increases slightly with an increase in La/W ratio, while the stability decreases. The lanthanum tungstate membrane with a La/W ratio of 5.5 may be a good candidate for hydrogen separation applications because of its favorable balance between stability and hydrogen permeability. [ABSTRACT FROM AUTHOR]