Solid Oxide Membrane Reactors: Catalyst Development and Testing for Solid Oxide Fuel Cells and Oxidative Coupling of Methane.

Abstract

In this dissertation, solid oxide membrane reactors were fabricated and tested as 1) fuel cells operating directly on ethanol and 2) for the production of ethane and ethylene directly from methane. The first part of this dissertation discusses results from a study where solid oxide fuel cells were fabricated with Ni based anodes and operated directly on ethanol fuel. In this study, small amounts of Sn (1wt% on a metals basis) added to the surface of the Ni anode improved the carbon tolerance of the fuel cells. Improved carbon tolerance of the Sn/Ni alloy electrocatalysts led to enhanced electrochemical stability as well as less carbon deposition within the anode as compared to the monometallic Ni samples. The second part of this dissertation presents an analysis of membrane and packed bed plug flow reactors for the process of oxidative coupling of methane (OCM) using kinetic data from the literature. This analysis demonstrated that the use of membrane reactors for OCM can theoretically result in higher yields of ethane and ethylene products compared to packed bed reactors. The final part of the dissertation presents experimental work directed towards the development of membrane reactors for OCM. This work included a catalyst screening which identified lanthanum gallate doped with strontium and magnesium (La0.8Sr0.2Ga0.8Mg0.2O3-x, LSGM) as a promising catalyst for use in membrane reactors for OCM. Integration of this catalyst into a membrane reactor showed high selectivity to ethane and ethylene, however, due to low membrane surface area, the methane conversion was very small and decreased over time, possibly due to carbon poisoning of the catalyst surface.