Air Bleeding Strategies to Increase the Efficiency of Proton Exchange Membrane Fuel Cell Stationary Applications Fuelled with CO ppm-levels

Abstract

The use of proton exchange membrane fuel cells (PEMFCs) as efficient electric generators for residential and tertiary sectors to replace conventional internal combustion engines greatly depends on the recent advances in purification technologies. Preferential oxidation and pressure swing adsorption offer reformate hydrogen streams with CO concentrations down to fractional ppm level. However, even small traces of CO cause reversible and irreversible performance losses of the PEMFC stack due to poisoning of the anode Pt catalyst. This work reports the performance loss upon H-2 contamination down to the ppm level and the efficiency gains after applying internal and external air bleeding to the anode of the fuel cell. This work studies both air bleeding strategies under operating conditions typical for stationary applications. By adding solely 1 % of air bleed to a 10 ppm CO contaminated hydrogen stream, it is possible to recover the full performance without compromising the steadiness of the cell. Moreover, a performance loss of < 1 - DOE target value for reformate streams - can be met using Pt-Ru based anode catalysts allied to a minimal air bleed concentration. Long-term experiments, ca. 80 h, were performed to assess the stability of the fuel cells fed with contaminated hydrogen and compare the long-term impacts of both internal and external air bleeding.