Ni-BaCe0.95Tb0.05O3-δ cermet membranes for hydrogen permeation

BaCe0.95Tb0.05O3-delta (BCTb) proton conducting perovskite powders were first synthesized via an EDTA-CA complexing method. Ni-BCTb cermet membranes were then fabricated by pressing a mixture of the BCTb and Ni powders in a weight ratio of 1: 1 at 10 MPa, followed by sintering at 1400 degrees C for 10 h. The properties of the BCTb powders and the Ni-BCTb membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and conductivity measurement using a 4-probe method. The electrical conductivity of the Ni-BCTb membranes approaches to 400 S cm(-1) at room temperature but decreases with increasing temperatures. The maximum hydrogen permeation flux through the asymmetric Ni-BCTb membrane with a 90 mu m separation top layer integrated with a porous substrate has reached up to 0.914 mL (STP) cm(-2) min(-1) at 850 degrees C when using the 50% H-2/N-2 mixture feed and He as the sweep gas, respectively. The surface exchange reaction kinetics takes a controlling effect on the hydrogen permeation through the membrane. The long-term operation test indicates that the Ni-BCTb cermet membranes are not sufficiently stable for hydrogen permeation due to the phase decomposition of the BCTb perovskite. (C) 2012 Elsevier B. V. All rights reserved.