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Investigation of catalytic phenomena for solid oxide fuel cells and tar removal in biomass gasifiers

Kuhn, John
http://rave.ohiolink.edu/etdc/view?acc_num=osu1186755244

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Chemical Engineering.
Solid oxide fuel cells (SOFCs) show promise for generating clean power from a variety of fuels. The major roadblocks to their implementation are a large cathodic resistance, which causes insufficient power densities and high fabrication costs, and anodic deactivation caused by carbon-based fuels such as coal and biomass-derived gases and their sulfur impurities. The large cathodic resistance is caused by slow oxygen activation kinetics and oxide ion transport of the current manganite-based cathode. At the anode, deactivation occurs through the conventional nickel-based material’s poor sulfur tolerance and tendency to form carbon fibers. Thus, the development of catalytically active materials suitable for use as electrodes is needed to help SOFCs realize their full potential. Replacing manganite with reducible transition metals (e.g., cobalt) leads to mixed (electronic and ionic) conductivity and improved performance through the enlargement of the electrochemically active area. However, further improvements are limited because the oxygen reduction kinetics and oxygen-surface interactions are poorly understood. The present work examines the catalytic phenomena of doped-lanthanum ferrites for use as cathode materials in intermediate temperature (500 and 800°C) applications. The kinetics and energetics of the oxygen reduction reaction is related to surface and bulk structural changes that occur as a function of environment and dopant levels. The current research also focuses on understanding deactivation of conventional anode materials in the presence of carbon fuels with sulfur impurities. The results show formation of adsorbed sulfur and surface sulfides even when the bulk phase is stable. The use of this information to modify conventional anode materials is still an active area of research. Characterization is performed by XRD, XPS, and vibrational spectroscopy to complement the oxidation results. Since gasification of biomass takes place in a fluidized bed reactor, attrition resistance is important to eliminate the loss of catalyst. Dolomite catalysts have been tried, but generally are not attrition resistant. With our collaborators, the use of Ni-doped olivine catalysts is examined. These catalysts have proved to be attrition resistant and possess adequate reforming activity.
Umit Ozkan (Advisor)
338 p.
solid oxide fuel cell; perovskite; Ni-YSZ; biomass gasification; tar removal; Ni-olivine

Recommended Citations

Citations

  • Kuhn, J. (2007). Investigation of catalytic phenomena for solid oxide fuel cells and tar removal in biomass gasifiers [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1186755244

    APA Style (7th edition)

  • Kuhn, John. Investigation of catalytic phenomena for solid oxide fuel cells and tar removal in biomass gasifiers. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1186755244.

    MLA Style (8th edition)

  • Kuhn, John. "Investigation of catalytic phenomena for solid oxide fuel cells and tar removal in biomass gasifiers." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1186755244

    Chicago Manual of Style (17th edition)

osu1186755244
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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.