Date of Graduation

2014

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

John W Zondlo

Committee Co-Chair

Edward Sabolsky

Committee Member

Dushyant Shekhawat

Committee Member

Charter Stinespring

Abstract

A solid oxide fuel cell (SOFC) is a device capable of converting chemical energy from gaseous fuels into useable electrical energy at high efficiencies. Since the United States transportation sector infrastructure is currently based on liquid fuels, this opens up a large market for alternative power units utilizing SOFC technology for liquid fuels. In this work, a novel rhodium and strontium-substituted lanthanum zirconate pyrochlore (LSRZ) catalyst developed by the U.S. Department of Energy's National Energy Technology Laboratory (NETL) was utilized in a reforming reactor to convert low-sulfur liquid hydrocarbon fuels to syngas for direct use in a SOFC. The SOFC was performance tested on the reformate from the reactor. A main aspect of this work was the design, construction, integration, and testing of a continuous flow system consisting of a fuel vaporization system, fuel reforming reactor, and a high-temperature SOFC. The liquid fuels tested include n-tetradecane, a fatty-acid methyl ester (FAME) mixture, two different ultra-low-sulfur diesel (ULSD) fuels, and a desulfurized version of the military logistic fuel JP-8. It was found that the reformer/SOFC system could be operated on the low-sulfur liquid fuels using the new LSRZ catalyst developed by the NETL. The sulfur-free compound n-tetradecane was successfully reformed multiple times for periods of up to 50 hours with no pressure increases in the reactor or deterioration of fuel cell performance. The sulfur-free FAME mixture was successfully reformed and continuously operated in the SOFC for 100 hours. The desulfurized JP-8 containing 11.7 ppm of thiophenic sulfur was successfully reformed and utilized continuously in the SOFC for a total time of 93 hours. Both diesel fuels caused pressure increases in the reforming reactor and this required system shut down within 30 hours of operation. It was found that the application of a thin layer of the LSRZ catalyst on top of the SOFC anode using a Ni-based paste reduced carbon formation on the anode caused by gaseous hydrocarbons left over from the reforming process. This new application for the LSRZ catalyst promoted in-situ reforming on the SOFC anode, allowing the cell to operate more consistently throughout the experiments.

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