Fuel Processing in Direct Methanol and Carbon Deposition Behaviour on Ni/CeO_2-ZnO Anodes for Solid Oxide Fuel Cell

摘要

The activities of cermet catalysts composed of Ni/CeO_2-ZnO anode for steam reforming of methanol were investigated for internal reforming of solid oxide fuel cell. Ni/CeO_2-ZnO anodes with specific percentage of ceria versus zinc were fabricated by wet impregnation method. The catalysts were characterized by X-ray diffraction, Scanning electron microscope and temperature-programmed reduction. Area specific resistance of these anodes was also examined to prove the thermal stability of them, and possible reasons for degradation were analyzed. Furthermore, The promoting effect of zinc metals included a decrease in the reduction temperature of NiO species interacting with the support, due to the hydrogen spillover effect. It was seen that the addition of zinc metal stabilized the Ni sites in the reduced state along the reforming reaction, increasing the methanol conversions and decreasing the coke formation. The maximum power density of the single cell reached 560mW cm"2 and 380mW cm~(-2) at 750°C in hydrogen and methanol steam respectively, and the cell obtained stable output in methanol steam over an operation period of 30 h.