Palladium based cermet composite for hydrogen separation at elevated temperature

A cermet composite consisting of palladium and BaCe_0.4Zr0_.4Gd_0.1Dy_0.1O_3-x (BCZGD) is fabricated by mixing palladium and BCZGD powders in a ball mill, followed by pressing and sintering at 1450 °C for 24 h in air. The Pd-BCZGD cermet demonstrates impressive hydrogen permeation flux in a mixture of hydrogen and carbon dioxide at elevated temperature, in which the palladium plays the predominant role of facile transport in the hydrogen atoms whereas the BCZGD provides channels for proton conduction. Material characterization including scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermo-gravimetric analysis (TGA) are performed. XRD patterns indicate pure phases of fcc palladium and perovskite BCZGD. SEM images and element mapping suggest a homogeneous mixture of cermet without noticeable defect and phase segregation. TGA results confirm stability of the cermet against carbon dioxide without chemical decomposition. The hydrogen permeation flux is determined via a gas chromatography from 400 to 700°C at various hydrogen concentration gradients. We record a hydrogen flux of 1.25 cm³ min^-1 cm^-2 in 50% hydrogen and 50% carbon dioxide at 700°C, with a selectivity of H₂/CO₂ approaching infinity.