Surface modification of carbon fabric for isopropanol removal from gas stream

Reddy, P. Manoj Kumar; Krushnamurty, K.; Subrahmanyam, Ch.

doi:10.1016/j.mee.2014.06.005

Cited by 6 publications

(1 citation statement)

References 33 publications

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“…During isopropanol contamination, the voltage is characterized by rapid fluctuations (Figure 1d), which were not observed for lower isopropanol concentrations [23,31]. These fluctuations are attributed to isopropanol, a surfactant commonly used to disperse Pt/C catalyst particles in solution [32], which adsorbs on carbon materials (gas diffusion layer, catalyst support) [33] and modifies liquid water management (buildup and release of liquid water drops), as previously proposed for acetylene [34]. A higher number of buildup and release events of water drops and a higher voltage fluctuation frequency for the lower catalyst loading ( Figure 1d) may be related to the lower cathode potential (cell voltage compensated by a similar ohmic drop), which leaves a higher proportion of isopropanol surfactant unoxidized (oxidation initiated at a potential above 0.32 V vs. the reversible hydrogen electrode (RHE) [35]) and more hydrophilic carbon surfaces.…”

Section: Cell Voltage Transientsmentioning

confidence: 97%

Impact of the Cathode Pt Loading on PEMFC Contamination by Several Airborne Contaminants

St‐Pierre

Zhai

2020

Molecules

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Proton exchange membrane fuel cells (PEMFCs) with 0.1 and 0.4 mg Pt cm −2 cathode catalyst loadings were separately contaminated with seven organic species: Acetonitrile, acetylene, bromomethane, iso-propanol, methyl methacrylate, naphthalene, and propene. The lower catalyst loading led to larger cell voltage losses at the steady state. Three closely related electrical equivalent circuits were used to fit impedance spectra obtained before, during, and after contamination, which revealed that the cell voltage loss was due to higher kinetic and mass transfer resistances. A significant correlation was not found between the steady-state cell voltage loss and the sum of the kinetic and mass transfer resistance changes. Major increases in research program costs and efforts would be required to find a predictive correlation, which suggests a focus on contamination prevention and recovery measures rather than contamination mechanisms.Molecules 2020, 25, 1060 2 of 15 focusing on the cathode catalyst loading effect were found [19,20]. However, contamination data in [19] are not directly comparable because both the catalyst layer design and catalyst loading were concurrently altered. The authors also refer to 10 ppb SO 2 data obtained by another group that showed more severe fuel cell damage with a catalyst loading decrease from 0.4 to 0.3 mg Pt cm −2 . In contrast, the effect of 2,6-diaminotoluene, a species that leaches out of the fuel cell system balance of plant materials, was more impactful after the Pt catalyst loading was lowered from 0.4 to 0.1 mg Pt cm −2 [20]. In comparison to the anode, the higher cathode potential is expected to affect the contamination mechanism with, for example, a different Pt surface charge, altered contaminant adsorbates and reaction intermediates, catalyst coverage, and cell voltage loss. This situation is exacerbated with a catalyst loading change, which affects the overpotential of the irreversible oxygen reduction reaction and the cathode potential. Information about chemical and electrochemical reactions for specific contaminants may be available in the literature. However, the presence of relevant cathode reactants, oxygen and water, may not be considered. For instance, novel intermediates or products were not detected with chlorobenzene in air [21]. However, the presence of acetylene in air led to small amounts of methane [22] that were not expected based on acetylene chemistry and electrochemistry. Therefore, tests completed under these significantly different operating conditions are needed in part because contaminant reactions are not currently predictable in assessing catalyst coverage and cell voltage loss.This report documents the impact of the cathode Pt catalyst loading effect for PEMFCs contaminated with seven model organic airborne species, which were previously evaluated and selected from a larger pool of 21 contaminants [23]: Acetonitrile (nitrile), acetylene (alkyne), bromomethane (halocarbon), iso-propanol (alcohol), methyl methacrylate (ester), naphthalene (polycyclic ...

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