In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2015-03, No. 1 ( 2015-07-15), p. 389-389
Abstract:
Ammonia (NH 3 ) is attractive as a hydrogen (H 2 ) carrier and a suitable fuel for solid oxide fuel cells (SOFCs) because it has high hydrogen density (17.6 %) and can be easily liquefied at an ambient temperature. However, the activity of conventional Ni cermet anodes of SOFCs for NH 3 oxidation is much lower than that when H 2 is used as a fuel [1]. It is necessarily to improve the anode activity for NH 3 oxidation for realizing NH 3 -fueled SOFCs. We have investigated the activity of anodes prepared with transition metals nickel(Ni), iron (Fe) and their alloy for NH 3 -SOFCs[2,3]. The Fe/Sm-doped ceria (SDC) cermet anode was more active for NH 3 oxidation than Ni/SDC. We also found that the activity of the Ni 40 -Fe 60/ /SDC for NH 3 oxidation was highest by optimizing the metal composition. These results suggested that the rate limiting steps in a direct NH 3 oxidation (or reforming NH 3 ) at the anode were (i) NH 3 adsorption and (ii) N 2 desorption. We concluded that Fe and Ni atoms had the roles of accelerating reactions (i) and (ii), respectively, and the synergetic effect of Fe and Ni resulted in the enhancement of the anode activity for NH 3 oxidation. On the basis of the mechanism of NH 3 oxidation at the anode, we prepared the anode of Ni and Molybdenum (Mo) since Mo has the high ability of NH 3 adsorption, and evaluated their performance for NH 3 -SOFCs. The Ni-Mo/SDC anodes were fabricated by impregnating a MoCl 5 aqueous solution into a Ni/SDC pre-sintered cermet on an electrolyte. It was revealed that the optimum addiction of Mo enhanced the anode activity for NH 3 oxidation. Our experimental results suggested that the anode activity for NH 3 oxidation was determined by a balance between abilities of NH 3 adsorption and N 2 desorption. Acknowledge This work was supported by “Kyoto Environmental Nanotechnology Cluster” and “Kyoto Regional Scientific Innovation Hub” from MEXT in Japan. Reference [1] Q. Ma et al., J. Power Sources 161 (2006) 95. [2] W. Akimoto et al., Solid State Ionics 256 (2013) 1. [3] W. Akimoto et al., ECS Transactions 57 (2013) 1639.
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2015-03/1/389
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2015
detail.hit.zdb_id:
2438749-6
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