Hydrogen sulfide tolerance of palladium–copper catalysts for PEM fuel cell anode applications

The H2S-tolerance of Palladium–Copper nanoparticle catalysts supported on carbon black employed on PEMFC anodes operating on H2S-contaminated anode feeding streams is described. The anode feeding consists of 80% H2, ∼20% N2 (in vol.), and 8 ppm H2S. Catalyst performances were evaluated by estimating the cell potential reduction due to H2S contamination through lifetime tests. It is found that the H2S-tolerance of PdCu catalysts depends on the concentration of copper, as confirmed by a catalyst pre-leaching procedure. This methodology is employed in order to remove copper atoms from the catalyst surface, which is confirmed by energy dispersive X-ray spectroscopy and X-ray diffraction techniques. This method generates catalysts with lower copper content and higher susceptibility to H2S. Moreover, it is proposed a new and effective catalytic activity recovering technique to restore the performance of PdCu catalysts after H2S exposure.

Lifetime plots of X-anode-based PEMFCs (X = catalyst) depicting them overpotential during the exposure to 8 ppm H2S in the fuel stream. Cell current density: 370 mA cm−2, cell temperature: 80 °C, membrane Nafion™: N117.Figure optionsDownload as PowerPoint slideHighlights
► New PEMFC anode catalysts are synthesized based on PdCu.
► Catalysts present tolerance to hydrogen sulfide.
► H2S-tolerance depends on catalyst copper concentration.
► Noble metal surface-enriched catalysts are more susceptible to H2S.
► H2S-contaminated PdCu-based PEMFC recovers its performance through air cleaning.