Effect of Transient Ammonia Concentrations on PEMFC Performance

Data are shown to indicate the effect of high concentrations on the membrane electrode assembly (MEA) performance in proton exchange membrane fuel cells (PEMFCs). Steady-state tests were performed with different mixtures: 200 ppm 500 ppm and 1000 ppm Also, transient tests were performed with 200 ppm and 1000 ppm and data show that poisoning and recovery rates with are much slower than with CO and that there may be two mechanisms occurring in series during recovery. These slow rates may be exploited to allow for treatments and control schemes that maintain PEMFC performance should the anode stream be exposed to high transient levels of The significant findings include ( i ) the ability of a MEA to recover completely in neat after exposure to 200 ppm for 10 h ( i.e. , exposure); ( ii ) the performance is lower for 1000 than for 500 ppm at the same dosage ( i.e. , exposure) although the cyclic voltammograms CV of the poisoned electrodes are the same; and ( iii ) the observation of a two-step process for recovery of the MEA.