Electrochemical promotion of methane oxidation on Pd catalyst-electrodes deposited on Y2O3-stabilized-ZrO2

The catalytic activity of Pd/YSZ and Pd-CeO2/YSZ catalysts prepared via organometallic paste calcination or via wet impregnation has been investigated under conditions of excess in oxygen and at temperatures from 250 to 450 °C. The catalyst-electrodes were characterized via XRD, SEM, in situ electrical conductivity measurements, electrochemical current–potential curves and catalytic kinetic measurements. The impregnated Pd films were found to be more active with light-off temperatures of 270 °C vs. 320 °C for metal paste catalysts. Only the impregnated catalyst could be electropromoted at temperatures above 320 °C. The Pd-CeO2/YSZ catalyst exhibited high catalytic activity but could not be electropromoted.Co-feeding of ethylene or pre treatment in oxidizing ethylene–oxygen gas mixtures enhances the rate of methane conversion in comparison to non-treated samples and allows electrochemical promotion of the methane oxidation at temperatures as low as 320 °C. The reason for this behavior is discussed in view of detailed pre and post surface characterization and in situ electrochemical measurements.

Graphical abstractElectrochemical promotion of methane oxidation on impregnated Pd/YSZ under oxidizing conditions and low operating temperatures. Transient response of the catalytic CO2 formation rate and of the catalyst potential upon application of (a) I = 100 μA at 350 °C and (b) I = 400 μA at 400 °C. Experimental conditions: PCH4=1.3 kPaPCH4=1.3 kPa, PO2=4.5 kPaPO2=4.5 kPa, F = 200 ml/min.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Electrochemical promotion of Pd/YSZ catalyst achieved under oxidizing conditions. ► Ceria interlayer enhances the catalytic activity of Pd/YSZ catalysts. ► Oxidation state of working Pd catalyst monitored via conductivity measurements.