ABSTRACT
Increasing demand for energy, the need for energy security, and the need to minimize the impact on the environment related to energy are the major drivers for the research and development of alternative technologies. Due to their high energy efciency and minimal-to-zero greenhouse gas emissions, polymer electrolyte membrane (PEM) fuel cells are considered to be one of the most promising candidates for the future clean power generation. They are electrochemical devices, which convert the chemical energy of hydrogen and oxygen directly and efciently into electrical energy with only waste heat and liquid water as the byproducts. PEM fuel cells operate at a low temperature, use a solid electrolyte, and can obtain a power density competitive with the internal combustion engine [1], thus, PEM fuel cells are very promising for use in the transportation sector. However, many technical hurdles face the commercialization of PEM fuel cells. One such hurdle is the presence of impurities in the anode fuel stream, which inhibit hydrogen oxidation reaction and result in a severe decrease in energy conversion efciency. Some of the most studied impurities, which attack the anode of PEM fuel cells, are carbon monoxide, carbon dioxide, hydrogen sulde, and ammonia. According to the U.S. Department of energy (DOE), the fuel composition should not contain more than 2 μmol/ mol CO2, 0.2 μmol/mol CO, 0.004 μmol/mol sulfur species, and 0.1 μmol/ mol NH4 [2].
