Investigation of Filtration Phenomena of Air Pollutants on Cathode Air Filters for PEM Fuel Cells

Abstract

Filtration of cathode air is one of the challenges in operating proton-exchange membrane (PEM) fuel cells. The poisoning with air contaminants can lead to rapid performance degradation and initiate an aging process of the fuel cell. Various commercially available cathode filters are being tested in a laboratory gas test bench within the research project X-EMU (03B10502B and 03B10502B2). A literature review of harmful gas contaminants in the air used for the oxygen reduction reaction (ORR) on the cathode side was conducted. Experimental investigations took place at 40 °C with synthetic humid air containing low concentration contaminants such as ammonia, nitrogen dioxide, carbon monoxide, sulfur dioxide, hydrogen sulfide, and toluene. Test durations varied from 3 to 24 h depending on the filtration efficiency. Each gas contaminant showed different reactions with the investigated filters. The filters did not let sulfur-containing components pass. However, carbon monoxide could not be filtrated by any of the tested filters. The filtration of nitrogen oxides was not efficient for all tested filters, while additional filter materials were essential for a successful filtration of ammonia. Comparative results lead to a discussion of possible effects on a fuel cell with an outlook on optimization of the filtration behavior.