Characteristics of Sr_(0.92)Y_(0.08)Ti_(1-x)Ni_xO_(3-δ) anode for direct internal steam methane reforming in solid oxide fuel cells

摘要

Sr0.92Y0.08Ti1-xNixO3-delta (SYTN) having a perovskite structure was investigated as a direct internal steam methane reforming catalyst for use in solid oxide fuel cells. To analyze the effect of Ni-ion doping, 0, 3, and 5 mol% of Ni is doped at the B-site of Sr0.92Y0.08TiO3-delta (SYT). On doping, each Ni2+ cation substitutes a Ti4+ cation in SYT to form an oxygen vacancy with two electron holes, thus acting as an oxygen-ion conductor. The number of oxygen vacancies increases with increase in Ni-ion doping. In particular, Sr0.92Y0.08Ti0.95Ni0.05O3-delta (SYTN5) shows excellent catalytic activity for steam methane reforming, yielding CH4 conversions of 0.80, 0.96, and 0.99 at 700, 800, and 900 degrees C, respectively, and H-2-to-CO ratios of 3.38, 3.32 and 3.24 at 700, 800, and 900 degrees C, respectively, which are very close to the theoretical values for the steam methane reforming and water gas shift reactions. The excellent electrochemical property and high oxygen-ion conductivity of the SYTN5 anode result in good cell performance.