Investigation of the potential application of MgO in Ni-YSZ SOFC anodes

On-anode reforming of methane is a promising method to operate a solid oxide fuel cell, since it can increase efficiency by utilizing the excess heat generated from the electrochemical oxidation of H2 and CO. On-anode reforming can also reduce steam requirements and potentially eliminate an external reformer, thereby reducing capital investment and operating costs. However, the challenges in on-anode reforming include anode deactivation due to the Ni sintering and carbon deposition, and the potential to generate a large endothermic effect at the leading edge of cell due to the fast activity of reforming compared with electrochemical activity. Our work has focused on modification of a conventional Ni-YSZ anode in order to meet the above challenges. MgO has been reported to suppress coke formation and prevent Ni sintering for methane steam reforming reaction over conventional supported nickel catalysts. We investigated the potential for MgO to provide a similar effect with Ni-YSZ. A series of Ni-YSZ compositions containing MgO, prepared via a glycine nitrate synthesis, are investigated in this work with TGA, XRD, TEM and synchrotron-based characterization techniques. These results providing information to support and explain the catalytic effects observed with these materials. The effect of preparation method, calcination temperature, and reduction temperature on the performance of the anode materials will be described for methane steam reforming (MRS) and natural gas steam reforming (NGSR) in powder flow-through tests. The results are compared to those obtained from Ni-YSZ prepared similarly. These preliminary results show that MgO addition inhibits carbon formation and stabilizes the activity of Ni-YSZ even at low steam-to-carbon (S/C) ratios. The implications to Ni-YSZ on-anode reforming will be discussed.