Design of Anodes for IT SOFC: Effect of Complex Oxide Promoters and Pd on Activity
and Stability in Methane Steam Reforming of Ni/YSZ (ScSZ) Cermets
Vladislav A. Sadykov
1
, Natalia V. Mezentseva
2
, Rimma V. Bunina
2
, Galina M. Alikina
2
, Anton I .
Lukashevich
2
, Vladimir A. Rogov
2
, Ella M. Moroz
2
, Vladimir I. Zaikovskii
2
, Arcady Ishchenko
2
,
Oleg F. Bobrenok
3
, Alevtina Smirnova
4
, John Irvine
5
, and Oleksandr Vasylyev
6
1
Heterogeneous catalysis, Boreskov Institute of Catalysis, pr. Lavrentieva, 5, Novosibirsk,
630090, Russian Federation
2
Boreskov Institute of Catalysis, Novosibirsk, 630090, Russian Federation
3
Institute of Thermophysics SB RAS, Novosibirsk, 630090, Russian Federation
4
University of Connecticut, Storrs, CT, 06269
5
University of St Andrews, Fife, KY169ST, United Kingdom
6
Institute for Problems of Materials Science, Kyiv, 03142, Ukraine
ABSTRACT
Effect of fluorite-like or perovskite-like complex oxide promoters and Pd on the performance
of Ni/8YSZ and Ni/ScSZ anode materials in CH
4
steam reforming (SR) or selective oxidation
(SO) by O
2
into syngas was studied. The spatial uniformity of dopants distribution in composites
was controlled by TEM combined with EDX analysis, while the lattice oxygen mobility and
reactivity were estimated by CH
4
and H
2
temperature-programmed reduction (TPR). The oxide
promoters suppress the coke deposition even at stoichiometric H
2
O/CH
4
ratio, while doping by
Pd ensures a good performance at moderate (~550
o
C) temperatures required for the Intermediate
–Temperature Solid Oxide Fuel Cells (IT SOFC) operation.
INTRODUCTION
Design of anode materials for IT SOFC able to efficiently operate in methane/steam feeds
without coking represents important but demanding problem. A promising approach consists in
doping Ni/YSZ (ScSZ) anodes by fluorite-like or perovskite-like oxides with a high oxygen
mobility [1-3], which is expected to suppress coking due to more efficient activation of oxidant
(H
2
O) and a higher oxygen flux from the electrolyte phase to the Ni surface. To increase the
middle-temperature (600-700
o
C) performance of SOFC anodes in CH
4
SR, small amounts of Pt
group metals are added [2]. The effect of these promoters depends on various factors such as the
chemical composition of electrolyte and porosity of NiO/electrolyte composites as precursors
for the cermet anodes. This work presents the results of comparative study of the effect of
perovskite and fluorite oxides doping combined with Pd supporting on the properties of Ni/YSZ
and Ni/ScSZ anode cermet materials.
EXPERIMENTAL DETAILS
Two types of composite powders were used in this study. The Composite I was prepared
from 50 wt. % NiO (Novamet, US) and Sc
0.1
Ce
0.01
Zr
0.89
O
2-y
(DKKK, Japan) powders. Composite
II was comprised of the mixture of NiO (60 wt.%) and Y
0.08
Zr
0.92
O
2-y
(Russian sources).
Mater. Res. Soc. Symp. Proc. Vol. 972 © 2007 Materials Research Society 0972-AA03-06