Spinels for use as Methane Reforming Catalysts in Fuel Flexible Solid Oxide Fuel Cells
Date
2014-11
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Abstract
Several compositions of Ni- and Co- containing aluminate spinels have been
synthesized in a reproducible manner, each of which are potential catalyst materials for
methane reforming in-situ during SOFC operation. Reduction and reoxidation cycles can
be performed at or below typical intermediate temperature SOFC operating temperatures.
The defect spinel structure remains intact if a zirconia stabilizer is used. The
microstructure of the defect spinel support following reduction varies depending on
calcination temperature. The faceted microstructure of the defect spinel support and the
metallic particles contributes to the excellent catalytic activity of the material.
NiAl2O4 and Ni0.5Co0.5Al2O4 catalysts had nearly 100% CH4 conversion over 16 hours at
GHSV=60,000hr-1, with the Co-containing sample losing some activity over the test
period. H2 and CO selectivities remained around 80% throughout the test. Less faceted
defect spinel catalyst conversion percentages increased with reactor temperature,
indicating further reduction of metal from the defect spinel support during testing. Using
methane fuel containing 20ppm H2S, conversion and CO selectivity dropped to 0% after
6 and 12 hours in less faceted and more faceted defect spinels, respectively. The spinels
can be reduced in methane but acquire a significant amount of carbon buildup with low
concentrations of CO. The spinels have been incorporated into a Ni/YSZ cermet anode
in 10 and 20 weight percent quantities to study the effect of the spinels on the cell
performance and microstructure. Peak power densities in H2 fuel were 0.0153, 0.0076,
0.0025, and 0.0153 W/cm2 for samples containing NiAl2O4, Ni0.5Co0.5Al2O4, CoAl2O4,
and no spinel, respectively. In CH4 fuel, peak power densities were 0.0115, 0.0089,
0.0089, and 0.0127 W/cm2 for samples containing NiAl2O4, Ni0.5Co0.5Al2O4, CoAl2O4,
and no spinel, respectively. Increasing Co content reduces peak power density values,
with the NiAl2O4-containing sample having a similar peak power density to the control
Ni/YSZ sample.
Description
Advisory committee members: William Carty, Yiquan Wu. Dissertation completed in partial fulfillment of the requirements for the degree of Masters of Science in Ceramic Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis