TRANSPORT-PROPERTIES OF SRCE0.95Y0.05O3-DELTA AND ITS APPLICATION FORHYDROGEN SEPARATION

Transport properties of SrCe0.95Y0.05O3-delta were studied by impedanc e spectroscopy and by measuring open-cell voltage (OCV) and gas permea tion. Ionic transference numbers were determined by measuring the OCV of concentration cells and water vapor evolution of an O-2/H-2 fuel ce ll. We observed interfacial polarization on the basis of the I-V curve s obtained by discharging a hydrogen concentration cell or an O-2/H-2 fuel cell. The observed high protonic conductivity (high proton and lo w oxide ion transference numbers) makes SrCe0.95Y0.05O3-delta a potent ial material for hydrogen separation. From proton conductivity measure ments, under a given hydrogen partial pressure difference of 4%/0.48&% , the hydrogen permeation rate (of a dense membrane with 0.11 cm in th ickness) was calculated to be approximate to 0.072 cm(3) (STP) cm(-2) min(-1) at 800 degrees C, whereas the permeation rate calculated from shea-circuit current measurements was, approximate to 0.023 cm(3) (STP ) cm(-2) min(-1) at 800 degrees C. The difference between calculated a nd observed permeation rates is probably due to interfacial polarizati on. (C) 1998 Published by Elsevier Science B.V. All rights reserved.