An experimental approach to investigate the transport of ammonia as a fuel contaminant in proton exchange membrane fuel cells

Abstract

h i g h l i g h t sThe data support a diffusion-solubility mechanism in a N 2 /N 2 system at OCV. Ammonia did not move across the membrane when the feed to both electrodes was dry. With humidified feeds, the ammonia was transported from the anode to the cathode. Diffusion coefficients of NH 3 at 80 C are obtained as~10 À6 cm 2 s À1 at RH ¼ 50 and 80%. a b s t r a c tData are presented for the transport of NH 3 from the anode to the cathode for various inlet conditions in a N 2 /N 2 laboratory-scale fuel cell at open circuit voltage (OCV). The data were obtained with a material balance technique, which uses an ion selective electrode (ISE) to determine the concentration of ammonium ions. The results show that ammonia did not move across the membrane when the feed to both electrodes was dry. However, with humidified feeds on either side, the ammonia was transported from the anode to the cathode. The data include changes in the relative humidity of the anode inlet and the flowrate on the cathode. The data support a diffusion-solubility mechanism in a N 2 /N 2 system at OCV.

The Contamination Mechanism and Behavior of Amide Bond Containing Organic Contaminant on PEMFC

“…The difference in affinities of the ε-caprolactam toward the PEM at different temperatures may indicate a temperature effect on the ring-opening reaction. Figure 6a, the ATR-IR spectrum of the ε-caprolactamabsorbed membrane shows a shift of the SO 3 − stretching peak at 1057 cm −1 because of the electrostatic interactions with the sulfonic group (R-SO 3 − ). This shift is also observed in the spectra of other cationic forms of Nafion membranes.…”

“…In general, three fundamental contamination mechanisms are known: conductivity loss by ion exchange in the membrane/ionomer, Pt contamination by adsorption, and water/mass transport issues induced by changes in the gas diffusion layer (GDL) properties. Alkali, alkaline-earth, or transitional-metal cations such as Li + , Na + , K + , Cs + , Ni 2+ , Cu 2+ , Ca 2+ , and Fe 3+ are well known contaminants that undergo ion exchange [2][3][4][6][7][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] with the proton exchange membrane (PEM) in a PEMFC. Changes in the oxygen reduction reaction (ORR) kinetics at a Pt electrode covered with a Nafion ionomer [20][21][22][23][24] have also been reported.…”

Preparation of Nafion Membranes for Reproducible Ammonia Quantification in Nitrogen Reduction Reaction Experiments

“…A piece of Nafion submerged in the aqueous solution is then exposed to ammonium ions, that are then exchanged with the acid sites of the membrane, in equilibrium with the NH 4 + concentration in the solution. Following the ion exchange, the Nafion adsorbed ammonium ions self‐diffuse into and through the membrane [16] . This brings forth doubts in the actual quantification of the NRR product.…”

“…Following the ion exchange, the Nafion adsorbed ammonium ions self-diffuse into and through the membrane. [16] This brings forth doubts in the actual quantification of the NRR product.…”

The Contamination Behavior of System Derived Organic Model Compounds on PEMFC Based upon Functional Groups

“…[5][6][7] Previous studies [7][8][9][10][11][12][13][14][15][16][17][18][19][20] of contamination in PEMFCs have shown the sensitivity of performance to low levels (ppm) of contamination. For example, fuel cell durability can be affected by contaminants from air impurities 4,[8][9][10][11][12][13][14][15][16][17][18] (e.g., SO 2 , H 2 S, CO, NO x , and bromomethane) and hydrogen fuel impurities [19][20][21][22][23][24] (e.g., NH 3 , CO, hydrocarbons, and alcohols), metal cations [25][26][27][28][29][30][31][32][33][34][35][36][37][38] (e.g., Ca 2+ , Na + , K + , Fe 2+ , Fe…”