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

• Published in: Applied catalysis. B, Environmental Environmental, 2012-11, Vol.128, p.48-54
• Main Authors: Jiménez-Borja, C., Brosda, S., Matei, F., Makri, M., Delgado, B., Sapountzi, F., Ciuparu, D., Dorado, F., Valverde, J.L., Vayenas, C.G.
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Catalytic activity; CeO2 interlayer; Deposition; Electrochemical promotion; Methane oxidation; Palladium; Pastes; Pd catalyst-electrode; Resistivity; YSZ; Yttria stabilized zirconia
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2012.02.011

Electrochemical 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=100μA at 350°C and (b) I=400μA at 400°C. Experimental conditions: PCH4=1.3 kPa, PO2=4.5 kPa, F=200ml/min. [Display omitted] ► 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. 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.