Experimental characterization of a microtubular solid oxide fuel cell fueled with hydrogen, methane and hydrogen sulfide

Abstract

A characterization of a microtubular-type Solid Oxide Fuel Cell (SOFC) has been performed using an electrochemical approach. Hydrogen and methane (both pure and diluted with argon) were used as fuels for the fuel cell, and also some preliminary results of hydrogen sulfide contamination were performed. These are important experiments to determine if this kind of fuel cells is suitable to be used with alternative and renewable fuels such as coal gas or biomass gas. The methods included analysis of transitory response, polarization curves, electrochemical impedance spectroscopy, outlet gas composition analysis by means of a mass spectrometer and electrochemical reaction analysis. The results show that methane could be used as a fuel for this kind of fuel cells as long as the fuel cell is not kept at open circuit potential, given that no cell degradation was observed under those conditions. The results with hydrogen sulfide showed an irreversible performance decrease at the first stages of contamination. After this initial performance decrease no further degradation was observed which indicates that this kind of fuel cells could be a suitable way of energetically use some alternative and renewable gases. These results constitute an important step to determine the tolerance levels of this kind of fuel cells towards methane and hydrogen sulfide and contribute to the investigation line that tries to determine the required fuel quality for this kind of fuel cell in terms of the admissible content of each contaminant. In addition to this, the use of electrochemical techniques to analyze the behavior of a Solid Oxide Fuel Cell constitutes a real innovation since the traditional approaches for this type of fuel cells were based on material science. …………………………………… La caracterización de una pila de combustible de Óxido Sólido de tipo microtubular ha sido llevada a cabo usando un enfoque electroquímico. Se usó hidrógeno y metano como combustibles puros y diluidos con argón, y también se obtuvieron unos resultados preliminares de contaminación con ácido sulfhídrico. Estos experimentos son importantes para determinar si este tipo de pilas son adecuados para el aprovechamiento energético de combustibles renovables y alternativos como el gas procedente de la gasificación de biomasa o carbón.