(453b) NiMo-Ceria-Zirconia Catalyst for Inert-Substrate-Supported Tubular Solid Oxide Fuel Cells Running on Model Gasoline

NiMo-ceria-zirconia
catalyst for inert-substrate-supported tubular solid oxide fuel cells running
on model gasoline

Kai Zhao^a,
Qusay Bkour^a, M. Grant Norton^b*, Su Ha^a*

^aVoiland School of Chemical Engineering
and Bioengineering, Washington State University,
Pullman, WA, 99164, USA

^bSchool
of Mechanical and Materials Engineering, Washington
State University,
Pullman, WA, 99164, USA

* E-mail: suha@wsu.edu

Solid oxide fuel cells (SOFCs)
are electrochemical energy devices offering a high efficiency route for
converting chemical energy in fuels into electricity. Typically, SOFCs work in
a temperature range of 600-1000 degree
C. The high
operation temperature enables the electrochemical oxidation of not only small
molecules (such as hydrogen, carbon monoxide and methane), but also complex
hydrocarbon fuels, such as liquid hydrocarbon fuels and synthetic liquid
biofuels.

Nickel-based cermets, such as
Ni-yttria-stabilized zirconia (Ni-YSZ), and Ni-samarium-doped ceria (Ni-SDC),
are widely used as anode supporters for SOFC single cells running on hydrogen
because of the high catalytic activity of nickel, and a good electronic-ionic
mixed conductivity of the cermet. However, when using complex hydrocarbons as
fuels, a severe carbon deposition on the Ni deactivates the electrochemical
properties of the anodes for the fuel oxidation, and the chemical reaction
between Ni and carbon deposits leads to the structure instability of the anodes
and cracking of the single cell. To address these problems, it is necessary to
apply active catalysts in SOFC single cells to effectively reform the complex hydrocarbon fuels into simple synthesis gas (a mixture of
hydrogen and carbon monoxide), and suppress the carbon deposition.

In our previous work, we have
successfully synthesized a novel NiMo-ceria-zirconia catalyst that shows a high
reforming activity toward liquid hydrocarbons (e.g., isooctane) and an
excellent coking tolerance. In this work, we applied the
NiMo-ceria-zirconia as an internal reforming catalyst for a tubular SOFC single
cell running on the isooctane/air mixture. Fig. 1 shows
the configuration of the tubular single cell. It has a porous YSZ supporter,
Ni-SDC anode, YSZ/SDC bilayer electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-d (LSCF) cathode. The NiMo-ceria-zirconia catalyst was packed
into the tubular channel of the single cell as the internal
reforming unit. With application of the catalyst in the tubular cell, the
mixture of isooctane and air can be efficiently reformed into the simple synthesis gas (a mixture of hydrogen and carbon
monoxide) at 750 degree C. Compared to electrochemical
performance of the single cell without the packed catalyst, applying the packed
catalyst increased the maximum power density of the single cell from 240 to 306
mW cm^-2 using the model gasoline. Furthermore, the tubular cell with
the packed catalysts exhibited significantly improved stability using the model
gasoline. The results suggest the feasibility of applying the
NiMo-ceria-zirconia catalyst into the tubular single cell design and operating
it under the direct feed condition of liquid logistic fuels.

Fig. 1 Schematic diagram
of the tubular single cell with NiMo-ceria-zirconia catalyst.