Non-Faradaic Electrochemical Modification of Catalytic Activity

Kaloyannis, Anthony; Vayenas, C.G.

doi:10.1006/jcat.1997.1775

Cited by 37 publications

(15 citation statements)

References 38 publications

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“…A ''single chamber'' reactor [5,17,20] was used in the case of Pt catalyst-electrodes and a ''fuel cell type'' reactor [5,21] in the case of Rh catalystelectrode. In the ''single chamber'' reactor an YSZ (ZrO 2 8% mol Y 2 O 3 ) disc (Dynamic-Ceramic) of 3/4¢¢ (19 mm) diameter and 1 mm (catalyst Pt1) to 2 mm (catalyst Pt2) thickness, on which were deposited the Pt catalyst-electrode on the one side and two auxiliary Au electrodes on the opposite side, was suspended in the interior of a closed at one end quartz tube of volume approximately 50 cm 3 , where the reaction mixture was fed, via three gold wires mechanically pressed on the YSZ disk.…”

Section: Methodsmentioning

confidence: 99%

“…Electrochemical promotion of alkane combustion has previously been studied in the catalytic systems of methane total oxidation on Pt/YSZ [15] and Pd/YSZ [16], ethane total oxidation on Pt/YSZ [17] and, recently, propane total oxidation on Pt/YSZ [18]. The latter study focused on the comparison of the EP behavior of propane and propene total oxidation reactions between 344 and 365°C and under stoichiometric or fuel-lean gas phase composition.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical promotion of the oxidation of propane on Pt/YSZ and Rh/YSZ catalyst-electrodes

Kotsionopoulos

Bebelis

2005

J Appl Electrochem

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The effect of electrochemical promotion (EP) or non-faradaic electrochemical modification of catalytic activity (NEMCA) was studied in the catalytic reaction of the total oxidation of propane on Pt and Rh films deposited on Y 2 O 3 -stabilized-ZrO 2 (or YSZ), an O 2) conductor, in the temperature range 420-520°C. In the case of Pt/YSZ and for oxygen to propane ratios lower than the stoichiometric ratio it was found that the rate of propane oxidation could be reversibly enhanced by application of both positive and negative overpotentials (''inverted volcano'' behavior), by up to a factor of 1350 and 1130, respectively. The induced rate increase Dr exceeded the corresponding electrochemically controlled rate I/2F of O 2) transfer through the solid electrolyte, resulting in absolute values of the apparent faradaic efficiency K=Dr/(I/2F) up to 2330. The Rh/YSZ system exhibited similar EP behavior. Abrupt changes in the oxidation state of the rhodium catalyst, accompanied by changes in the catalytic rate, were observed by changing the O 2 to propane ratio and catalyst potential. The highest rate increases, by up to a factor of 6, were observed for positive overpotentials with corresponding absolute values of faradaic efficiency K up to 830. Rate increases by up to a factor of 1.7 were observed for negative overpotentials. The observed EP behavior is explained by taking into account the mechanism of the reaction and the effect of catalyst potential on the binding strength of chemisorbed reactants and intermediates and on the oxidative state of the catalyst surface.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrochemical promotion of the oxidation of propane on Pt/YSZ and Rh/YSZ catalyst-electrodes

Kotsionopoulos

Bebelis

2005

J Appl Electrochem

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“…Compared to classical promotion, the coverage of the promoting species on the electrochemical catalysts can be in situ controlled by the polarisation. The electrochemical promotion of CH 4 [3], C 2 H 4 [4,5], C 2 H 6 [6], C 3 H 6 [7,8] and C 3 H 8 [7,9,10] combustion has been investigated on the Pt/YSZ system between 300 and 500°C and for different hydrocarbon/ oxygen ratios. All these studies have been performed with Pt films made from commercial paste, typically 1-10 lm thick and containing about 1 mg cm )2 .…”

Section: Introductionmentioning

confidence: 99%

Electrochemical catalysts for hydrocarbon combustion

Billard¹,

Vernoux

2007

Top Catal

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International audienceTwo series of electrochemical catalysts were prepared from sputtered Pt thin films onto two kinds of electrolyte membranes, 8 mol% Y2O3-stabilized ZrO2 (YSZ), an O2− conducting oxide and Na3Zr2Si2PO12 (NASICON), a Na+ one; respectively. The thickness of the Pt films varied from 8 to 120 nm. Therefore, the Pt loading was extremely low. The catalytic activity of Pt/YSZ and Pt/NASICON systems has been investigated between 200 and 500 °C for propane and propene, respectively. In spite of the low Pt loading, the Pt/YSZ electrochemical catalysts exhibited high activity for propane combustion. Furthermore, the catalytic activity can be in-situ controlled by applying electrical polarisation with high Faradaic efficiency (103). The catalytic rate of propene deep oxidation on Pt/NASICON electrochemical catalyst was found to be limited by the number of active sites, which is low on very thin Pt films. Moreover, initial anodic polarisation indicate that Na+ ions are already present on the top surface of Pt, probably proceeding from the preliminary stabilisation treatment of Pt in the reactive mixture. Nevertheless, polarisation allows the tuning of the catalytic activity of the electrochemical catalysts for propene oxidation. Finally, for both kinds of electrochemical catalysts, our results have evidenced that the measurement of the open-circuit voltage during catalytic process can be an indicator of the hydrocarbon conversion

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“…One can assume that, for propane oxidation, the key factor is not oxygen coverage but the propane one. shown the electrophilic behaviour of propene combustion [7,9] and SCR of NO by propene [10,11].…”

Section: Selective Catalytic Reduction (Scr) Of No By Propene In the mentioning

confidence: 98%

The relationship of the catalytic activity and the open-circuit potential of Pt interfaced with YSZ

Gaillard

Vernoux

2005

Ionics

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Abstract. This study deals with the relationship between open-circuit potential and catalytic activity of the system Pt/YSZ. Temperature-programmed desorption (TPD) of oxygen was carried out in order to investigate the link between the oxygen coverage and the potential. Then, catalytic activity in parallel with the potential value was measured between 200 ~ and 500 ~ for NO oxidation, C3H8 combustion, C3H6 combustion and the selective catalytic reduction (SCR) of NO by C3H6 in the presence of oxygen. It was found that potential measurement can give precious information on the competitive adsorption between oxygen and other reactants. Finally, it seems to be also a good way to anticipate the NEMCA behavior for reactions, which involve oxygen.

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Non-Faradaic Electrochemical Modification of Catalytic Activity

Cited by 37 publications

References 38 publications

Electrochemical promotion of the oxidation of propane on Pt/YSZ and Rh/YSZ catalyst-electrodes

Electrochemical promotion of the oxidation of propane on Pt/YSZ and Rh/YSZ catalyst-electrodes

Electrochemical catalysts for hydrocarbon combustion

The relationship of the catalytic activity and the open-circuit potential of Pt interfaced with YSZ

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