Influence of Cr doping on hydrogen permeation performance of lanthanum tungstate membrane

A series of La5.5W1-xCrxO11.25-delta (LWCrx, x = 0.1, 0.2, 0.3 and 0.4) powders were successfully synthesized by a traditional solid-state reaction method. The influences of Cr doping on phase structure, microstructure, hydrogen permeation and chemical stability of lanthanum tungstate were investigated in details. The oxygen vacancy concentration in LWCr0.2 was higher than the other three samples. Moreover, the hydrogen permeation fluxes through LWCrx membranes increased with the increase of Cr content when x <= 0.2, and LWCr0.2 exhibited the highest hydrogen permeation flux because of its higher oxygen vacancy concentration. Besides, the hydrogen permeation fluxes through LWCr0.2 membrane were comparable to that through La5.5W0.8Mo0.2O11.25-delta (LWMo0.2) membrane. During a 104 h of hydrogen permeation test, the hydrogen permeation flux and phase structure changed slightly, revealing a good stability of LWCr0.2 membrane.