Performance and endurance of a high temperature PEM fuel cell operated on methanol reformate

Abstract

This paper analyzes the effects of methanol and water vapor on the performance of a high temperature proton exchange membrane fuel cell (HT-PEMFC) at varying temperatures, ranging from 140 C to 180 C. For the study, a H 3 PO 4 e doped polybenzimidazole (PBI) e based membrane electrode assembly (MEA) of 45 cm 2 active surface area from BASF was employed. The study showed overall negligible effects of methanol-water vapor mixture slips on performance, even at relatively low simulated steam methanol reforming conversion of 90%, which corresponds to 3% methanol vapor by volume in the anode gas feed. Temperature on the other hand has significant impact on the performance of an HT-PEMFC. To assess the effects of methanol-water vapor mixture alone, CO 2 and CO are not considered in these tests. The analysis is based on polarization curves and impedance spectra registered for all the test points. After the performance tests, endurance test was performed for 100 h at 90% methanol conversion and an overall degradation rate of À55 mV/ h was recorded.

Fault detection and isolation of high temperature proton exchange membrane fuel cell stack under the influence of degradation

“…For the low hydrogen stoichiometry fault (φ 5 ), the low frequency arch increases, due to mass transport issues and an increase in gas channel oscillations. For the high content of methanol fault (φ 4 ) quite close to the normal operational data (φ 0 ), due to water and methanol 190 vapor mixture has more diluting effect than poisoning effect at these concentrations, which in these experiments causes a slight increase in the intermediate frequency arch due to the diluting effect [33,34].…”

Performance enhancement by optimizing the reformer for an internal reforming methanol fuel cell

“…Slight differences are observed in the semi‐circles (high and low frequencies) further prove a weak influence of CO 2 , CO, and methanol‐water vapor. The same ohmic resistance under methanol feed and under hydrogen feed, respectively, at 0.9 A/cm 2 may be due to the reduction of polycondensation of phosphoric acid at 453 K and poisoning effect of unreacted methanol species on the proton conductivity of the membrane …”

“…The poisoning effect of CO can be further relieved by its lower content in the products. Additionally, the effect of methanol‐water vapor mixture on performance is smaller, which is mainly because the dilution and degrading effects for anodic process are balanced out by the enhanced mass transport according to the research of Samuel Simon Araya et al…”

“…The fast decay is mainly caused by unreacted methanol, since CO content in reformate is less than 0.3%. Mendes et al and Samuel Simon Araya et al reported that methanol has negative effect on anode resistance, cathode resistance, and the ohmic resistances. The cathode resistance increased is mainly due to the methanol crossover from the anode to the cathode.…”

Steam Reforming of Methanol over Nanostructured Pt/TiO2 and Pt/CeO2 Catalysts for Fuel Cell Applications

“…High CO selectivity implies higher activity of these catalysts for the decomposition of methanol or/and the reverse water-gas shift reaction. We should note that in the case of HT-PEMFCs, the employed membrane-electrode-assemblies can tolerate up to 2%, or even higher concentrations of CO, depending on the water and methanol content in the anode feed stream [5,12,[83][84][85] and this is an advantage of this type of fuel cells. Under our experimental conditions, CO selectivity was much higher than its equilibrium value in water-gas shift reaction, suggesting that CO was also a primary product of methanol steam reforming, produced mainly via methanol decomposition, while reverse WGS reaction might also take place, especially at higher temperatures.…”