Comparison of ethanol and methanol crossover through different MEA components and structures by cyclic voltammetry

Longtin, Geoffrey; Savadogo, O.

doi:10.1002/apj.194

Cited by 10 publications

(4 citation statements)

References 22 publications

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“…The loss of catalytic activity of Pt during the electro-oxidation of small organic molecules results in significantly high anode overpotentials and lower fuel cell performances. Moreover, the crossover of relatively small amounts of liquid fuel and/or reaction intermediates to the cathode side of the MEA causes a significant increase in cathode overpotentials and a remarkable lower onset potential for the ORR when Pt-alone cathodes are used [1][2][3][4][5][6][7][8][9]. Recently, the development of alcohol-tolerant cathode electrocatalysts allowed for a reduction in efficiency losses due to the presence of liquid substances in the cathode chamber of DOFCs.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)

Rodríguez-Varela¹,

Luna²,

Savadogo

2009

Energies

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Abstract:Highly selective Pd electrocatalysts were synthesized by the formic acid (FA) method and evaluated as cathodes for DEGFC applications. In rotating disc measurements in acid medium, the Pd/C cathode showed important catalytic activity for the Oxygen Reduction Reaction (ORR). In the presence of ethylene glycol (EG, C 2 H 6 O 2 ), Pd/C exhibited a noteworthy electrochemical behavior and full tolerance to the organic molecule. No current density peaks associated to the EG oxidation reaction emerged and the shift in onset potential for the ORR (E onset ) toward more negative potentials was negligible on this cathode. As a comparison, commercial Pt/C was tested under the same conditions showing a poor selectivity for the ORR when EG was present. The detrimental effect of EG on the Pt electrocatalysts resulted in high intensity current density peaks due to the oxidation of EG and a significant shift in E onset . The evaluation of Pd/C in a DEGFC operating at 80 °C demonstrated its good performance as cathode material. Given these results, it is expected that highly efficient Pd-based cathodes can find application in DEGFCs.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)

Rodríguez-Varela¹,

Luna²,

Savadogo

2009

Energies

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“…Similar decreases are observed in FCs running on liquid fuels [ 39 , 67 ]. The decrease in performance likely arises from ethanol crossing over through the Nafion separator, which produces a mixed potential and lowers performance [ 36 , 68 ]. Overall, these results demonstrate that FCs running on ethanol–water vapor can achieve power densities comparable to those for liquid-fed FCs, over a wide range of ethanol partial pressures.…”

Section: Resultsmentioning

confidence: 99%

Vapor-fed bio-hybrid fuel cell

Benyamin

Jahnke

Mackie

2017

Biotechnol Biofuels

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BackgroundConcentration and purification of ethanol and other biofuels from fermentations are energy-intensive processes, with amplified costs at smaller scales. To circumvent the need for these processes, and to potentially reduce transportation costs as well, we have previously investigated bio-hybrid fuel cells (FCs), in which a fermentation and FC are closely coupled. However, long-term operation requires strictly preventing the fermentation and FC from harming each other. We introduce here the concept of the vapor-fed bio-hybrid FC as a means of continuously extracting power from ongoing fermentations at ambient conditions. By bubbling a carrier gas (N2) through a yeast fermentation and then through a direct ethanol FC, we protect the FC anode from the catalyst poisons in the fermentation (which are non-volatile), and also protect the yeast from harmful FC products (notably acetic acid) and from build-up of ethanol.ResultsSince vapor-fed direct ethanol FCs at ambient conditions have never been systematically characterized (in contrast to vapor-fed direct methanol FCs), we first assess the effects on output power and conversion efficiency of ethanol concentration, vapor flow rate, and FC voltage. The results fit a continuous stirred-tank reactor model. Over a wide range of ethanol partial pressures (2–8 mmHg), power densities are comparable to those for liquid-fed direct ethanol FCs at the same temperature, with power densities >2 mW/cm2 obtained. We then demonstrate the continuous operation of a vapor-fed bio-hybrid FC with fermentation for 5 months, with no indication of performance degradation due to poisoning (of either the FC or the fermentation). It is further shown that the system is stable, recovering quickly from disturbances or from interruptions in maintenance.ConclusionsThe vapor-fed bio-hybrid FC enables extraction of power from dilute bio-ethanol streams without costly concentration and purification steps. The concept should be scalable to both large and small operations and should be generalizable to other biofuels and waste-to-energy systems.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0755-7) contains supplementary material, which is available to authorized users.

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“…When methanol crosses over to the cathode, it undergoes oxidation as a result of the presence of binary catalyst, thereby creating a reverse potential. Hence, it can be concluded that methanol crossover is harmful for two reasons: decreasing the fuel utilization ratio, and also decreasing the cell voltage . Hence, a good DMFC membrane should have as high proton conductivity as possible and as low methanol permeability as possible, while maintaining structural integrity and cost‐effectiveness …”

Section: Introductionmentioning

confidence: 99%

Effect of polymer sulfonation on the proton conductivity and fuel cell performance of polyvinylalcohol‐mordenite direct methanol fuel cell membranes

Üçtuğ

Nijem

2017

Asia-Pacific J Chem Eng

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Sulfonated polyvinylalcohol‐mordenite (SPVA‐MOR) membranes for direct methanol fuel cell use were synthesized and characterized. It had earlier been found out that polyvinylalcohol‐mordenite (PVA‐MOR) membranes, while having excellent methanol permeability and modest proton conductivity values, had inferior direct methanol fuel cell performances than Nafion™. Sulfonating the polyvinylalcohol matrix had been suggested to improve the proton conductivity. In this work, polyvinylalcohol powder was sulfonated by using propane sultone as the sulfonating agent prior to the membrane synthesis. Morphological analyses revealed that the zeolite particles mixed homogeneously within the polymer matrix. Sulfonating the polymer slightly decreased both water and methanol uptakes. Both in PVA‐MOR and SPVA‐MOR membranes, water uptake turned out to be higher than the methanol uptake. SPVA‐MOR membranes were found to have an average proton conductivity of 0.052 S·cm−1 when compared with the 0.036 S·cm−1 of PVA‐MOR membranes, while Nafion™ has a proton conductivity of approximately 0.1 S·cm−1. The increase in the proton conductivity upon sulfonation despite the decrease in water uptake was explained by the dominance of the Grotthuss mechanism over the vehicular mechanism for proton conductivity. Fuel cell test results showed that while SPVA‐MOR membranes cannot outperform Nafion™, they give higher power output than PVA‐MOR membranes, especially at low temperatures and high methanol concentrations. © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

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Comparison of ethanol and methanol crossover through different MEA components and structures by cyclic voltammetry

Cited by 10 publications

References 22 publications

Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)

Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)

Vapor-fed bio-hybrid fuel cell

Effect of polymer sulfonation on the proton conductivity and fuel cell performance of polyvinylalcohol‐mordenite direct methanol fuel cell membranes

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