Journal of Power Sources 182 (2008) 496–502 Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour Steam reforming on Ni-samaria-doped ceria cermet anode for practical size solid oxide fuel cell at intermediate temperatures Mitsunobu Kawano a,b,∗ , Toshiaki Matsui a , Ryuji Kikuchi a , Hiroyuki Yoshida b , Toru Inagaki b , Koichi Eguchi a a Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan b Energy Use R&D Center, The Kansai Electric Power Co., Inc., 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974, Japan article info Article history: Received 21 March 2008 Received in revised form 11 April 2008 Accepted 14 April 2008 Available online 22 April 2008 Keywords: Solid oxide fuel cell Methane Steam reforming Ni-samaria-doped ceria Intermediate temperature abstract Direct internal and external reforming operations on Ni-samaria-doped ceria (SDC) anode with the practi- cal size solid oxide fuel cell (SOFC) at intermediate temperatures from 600 to 750 ◦ C are carried out to reveal the reforming activities and the electrochemical activities, being compared with the hydrogen-fueled power generation. The cell performance with direct internal and external steam reforming of methane and their limiting current densities were almost the same irrespective of the progress of reaction in the methane reformate at 700 and 750 ◦ C. The durability test for 5.5 h at 750 ◦ C with direct internal reforming operation confirmed that the cell performance did not deteriorate. The operation temperature of the cell controlled the reforming activities on the anode, and the large size electrode gave rise to high conversion due to the slow space velocity of the steam reforming. Direct internal steam reforming attained sufficient level of conversion for SOFC power generation with methane at 700 and 750 ◦ C on the large Ni-SDC cermet anode. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Intermediate temperature solid oxide fuel cells (SOFCs) oper- ated at temperatures between 600 and 800 ◦ C have been drawing a great deal of attention because it offers sev- eral advantages. The Kansai Electric Power Co., Inc. and Mitsubishi Materials Corp. have been jointly developing inter- mediate temperature SOFCs since 2001. At present, this devel- opment is the practical phase such as 10 kW-class SOFC power generation system [1]. In this development, electrolyte- supported planar-type cells with large electrode (120mm Ø) are used as a single cell fabricated from microstructure- optimized Ni-samaria-doped ceria (Ce 1 - x Sm x O 2 - 0.5x ; SDC) cer- met anode. On the other hand, among various kinds of hydrocarbon fuels, methane is a typical fuel which is an abundant component in nat- ural gas. Steam reforming of methane on the anode in the SOFC chamber can be carried out along different process routes [2–5]. In this case, steam reforming reaction of methane proceeds with ∗ Corresponding author. Energy Use R&D Center, The Kansai Electric Power Co., Inc., 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974, Japan. Tel.: +81 6 6494 9715; fax: +81 6 6494 9705. E-mail address: kawano.mitsunobu@e2.kepco.co.jp (M. Kawano). water-gas shift reaction followed by electrochemical oxidation of hydrogen and carbon monoxide. For the reforming reaction system, three types of operation systems can be considered [6]. They are external, direct inter- nal and indirect internal reforming operation. External reforming operation separates the reforming reaction and the electro- chemical oxidation. Then, gaseous species reformed at various extents in the temperature-controllable pre-reformer can be sup- plied to the anode. In the case of direct internal reforming, on the other hand, methane fuel is directly introduced to the fuel cell chamber. This mode is expected to simplify the overall system design. In this case, reforming reaction and electro- chemical oxidation reaction simultaneously proceed at the same anode. Progress of reforming reaction and the consumption of fuels should be different depending on cell size, cell configuration and the operation temperature. Investigation on the characteristics of power generation using electrolyte-supported planar-type cell with large electrode at various operation temperatures is requested to clarify the reforming activities and electrochemical activities at the anode. Moreover, the adaptability of SOFC to methane fuel can be evaluated by supplying various extents of reformed methane to the anode under direct internal reforming and temperature- controllable external reforming conditions. Thus, comparison of these operation modes is beneficial to optimize the system. 0378-7753/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2008.04.030