A NiMo-YSZ catalyst support layer for regenerable solid oxide fuel cells running on isooctane

Abstract

A catalyst-layer supported single cell consisting of a porous YSZ backbone support and NiMo catalyst is developed for solid oxide fuel cells running on isooctane/air. The reforming and electrochemical performance of the catalyst-layer supported single cell is comparatively studied with conventional anode supported single cell applied with a thin NiMo-YSZ reforming layer. The NiMo-YSZ catalyst support layer could efficiently catalyze the partial oxidation of isooctane in air, producing H2 and CO for the anode electrochemical oxidation. As a result, the single cells display enhanced initial electrochemical performance and performance stability compared with the cell without the catalyst in isooctane/air at 750 °C. On the other hand, carbon species could still be identified in the NiMo-YSZ catalyst after operating the single cells for 12 h, which deteriorates the reforming and electrochemical performance. To improve the electrochemical performance stability, the catalyst layer is in-situly regenerated by redox treatment to burn out the carbon deposits. The conventional Ni metal-based anode supported cell is susceptible to redox condition and the occasional oxidation of the Ni metal containing support results in 37.8 % performance loss only after one redox cycle. By applying the robust catalyst-layer supported cell developed in this work, the cell could maintain over 90 % of its initial electrochemical performance after two redox cycles. Feeding 15 ml min−1 air to the anode channel for 5 min is found to be effective to burn out the carbon species in the catalyst support layer, which suppresses the deterioration of catalytic activity and enhance electrochemical performance stability of the single cell. The results demonstrate the benefits of the catalyst-layer supported single cell design for in-situ catalyst regeneration.