Gas phase recovery of hydrogen sulfide contaminated polymer electrolyte membrane fuel cells

• Published in: Journal of power sources 2014-04, Vol.252, p.317-326
• Main Authors: Kakati, Biraj Kumar, Kucernak, Anthony R.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cleaning; Contamination; Cyclic voltammetry; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrochemical surface area; Electrodes; Electrolytes; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Gas phase recovery; H2S contamination; Hydrogen sulfide; Membranes; Ozone; Polymer electrolyte membrane fuel cell; Recovery
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.11.077

The effect of hydrogen sulfide (H2S) on the anode of a polymer electrolyte membrane fuel cell (PEMFC) and the gas phase recovery of the contaminated PEMFC using ozone (O3) were studied. Experiments were performed on fuel cell electrodes both in an aqueous electrolyte and within an operating fuel cell. The ex-situ analyses of a fresh electrode; a H2S contaminated electrode (23 μmolH2S cm−2); and the contaminated electrode cleaned with O3 shows that all sulfide can be removed within 900 s at room temperature. Online gas analysis of the recovery process confirms the recovery time required as around 720 s. Similarly, performance studies of an H2S contaminated PEMFC shows that complete rejuvenation occurs following 600-900 s O3 treatment at room temperature. The cleaning process involves both electrochemical oxidation (facilitated by the high equilibrium potential of the O3 reduction process) and direct chemical oxidation of the contaminant. The O3 cleaning process is more efficient than the external polarization of the single cell at 1.6 V. Application of O3 at room temperature limits the amount of carbon corrosion. Room temperature O3 treatment of poisoned fuel cell stacks may offer an efficient and quick remediation method to recover otherwise inoperable systems. [Display omitted] •Recovery of H2S contaminated PEMFC is studied via external polarization and O3 cleaning.•The room temperature O3 cleaning process completely rejuvenates the H2S contaminated fuel cell in 600-900 s.•O3 cleaning at room temperature avoids excessive carbon corrosion as seen by low CO2 generation.•The in-situ O3 cleaning process proceeds through both a chemical and electrochemical route.