In situ controlled promotion of catalyst surfaces via solid electrolytes: Ethylene oxidation on Rh and propylene oxidation on Pt

Kaloyannis, Anthony; Pliangos, C.; Yentekakis, I.V.; Vayenas, C.G.

doi:10.1007/bf02388675

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…5 A limited EP study of propene combustion has been reported, using Pt supported on YSZ. 6 However in this case, increasing the catalyst potential under fuel-lean conditions led to rate enhancement. There have been no previous EP studies of propene combustion by sodium.…”

Section: Introductionmentioning

confidence: 89%

“…Furthermore, in the former case poisoning was observed at sufficiently negative catalyst potentials (high Na loadings). , Model studies on the Na/Pt(111) system suggest that this poisoning is due to formation of a surface alkali metal carbonate . A limited EP study of propene combustion has been reported, using Pt supported on YSZ . However in this case, increasing the catalyst potential under fuel-lean conditions led to rate enhancement.…”

Section: Introductionmentioning

confidence: 97%

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A Kinetic and Spectroscopic Study of the in Situ Electrochemical Promotion by Sodium of the Platinum-Catalyzed Combustion of Propene

et al. 1999

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The electrochemical promotion (EP) of propene combustion has been studied over a platinum film catalyst supported on sodium β‘ ‘-alumina. Fully reversible promotion and poisoning are observed as a function of catalyst potential (i.e., sodium coverage), the precise behavior being dependent on reactant partial pressures. A model based on a Langmuir−Hinshelwood mechanism and Na-modified chemisorption of the reactants accounts for all the results: Na enhances the chemisorption of oxygen and inhibits the chemisorption of propene. The formation, chemical identity, stability, and electrochemical decomposition of the Na surface compounds produced in the promoted and poisoned regimes were explored using postreaction XPS, AES, and, for the first time, postreaction Na K edge XAFS. These results indicate that thick layers consisting of sodium carbonate are responsible for catalyst poisoning. The promoter phase consists of smaller amounts of sodium carbonate, and much of this material is present as three-dimensional crystallites. These promoter and poisoning phases are stable at reaction temperature, but rapidly destroyed by electropumping Na away from the catalyst surface. Their direct participation in the electrochemically promoted reaction is thereby demonstrated.

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Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 97%

A Kinetic and Spectroscopic Study of the in Situ Electrochemical Promotion by Sodium of the Platinum-Catalyzed Combustion of Propene

et al. 1999

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“…Using rhodium catalysts, kinetic studies coupled with catalyst potential measurements under electrochemical promotion conditions were reported for the combustion of ethylene [34,36,37]. The reaction exhibited electrophobic behaviour, meaning increasing reaction rate when applying positive potential, and the achieved enhancement was among the highest obtained so far during EPOC experiments, explained with the strong dependence of the reaction rate on the oxidation state of the catalyst.…”

Section: Introductionmentioning

confidence: 99%

“…It has been stated that, in analogy with strong metalsupport interactions [39], electrochemical promotion is due to oxygen back-spillover generated electrochemically at the three-phase boundary. This causes weakening of the chemisorptive bond strength of electron acceptor adsorbates (e.g., oxygen) making easier the reduction of surface oxides to metallic rhodium [34,36,37]. In the present work, the relation between catalyst potential and catalytic performance will be studied under both opencircuit and closed-circuit conditions.…”

Section: Introductionmentioning

confidence: 99%

Relation between potential and catalytic activity of rhodium in propylene combustion

Fóti

Bolzonella

Bachelin

et al. 2004

Journal of Applied Electrochemistry

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The relation between the catalyst potential and the catalytic performance has been investigated in the gas-phase combustion of propylene with oxygen over rhodium catalysts at 375°C. The rhodium catalyst, deposited on yttriastabilized zirconia (YSZ) solid electrolyte, also served as working electrode in the electrochemical cell. Under opencircuit conditions, the measured catalyst potential was found to be a sensitive indicator of the oxidation state of the rhodium catalyst, which influences the catalytic reaction rate dramatically and depends strongly both on the method of catalyst film preparation and on the composition of the reacting gas mixture. In turn, under closed-circuit conditions, the applied catalyst potential is a convenient tool to maintain the catalyst in its more active, reduced form and to control its catalytic performance. The activity of atomic oxygen at the three-phase boundary (tpb) during open-circuit catalytic reaction was estimated from solid electrolyte potentiometric (SEP) measurements, in good agreement with the average surface oxidation state obtained from XRD and XPS analyses. O/Rh atomic ratios higher than stoichiometric were found by XPS at the outer surface of the catalysts suggesting a strong open circuit O 2) spillover due to strong metal support interactions (SMSI) and a concomitant extension of the electric double layer to the gas-exposed catalyst surface, similarly to emersed electrodes in aqueous electrochemistry. Applying potentials up to several hundreds of mV, highly nonfaradaic promotion of propylene combustion was achieved. Electrochemical promotion of catalysis (EPOC) was most efficient at stoichiometric gas composition, that is, close to the limit of surface reduction, and with the catalyst exhibiting the smallest O 2) spillover population at open-circuit conditions.

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Special Catalytic Systems

Göpel¹,

Schierbaum²,

Vayenas³

et al. 1997

Handbook of Heterogeneous Catalysis

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In situ controlled promotion of catalyst surfaces via solid electrolytes: Ethylene oxidation on Rh and propylene oxidation on Pt

Cited by 7 publications

References 22 publications

A Kinetic and Spectroscopic Study of the in Situ Electrochemical Promotion by Sodium of the Platinum-Catalyzed Combustion of Propene

A Kinetic and Spectroscopic Study of the in Situ Electrochemical Promotion by Sodium of the Platinum-Catalyzed Combustion of Propene

Relation between potential and catalytic activity of rhodium in propylene combustion

Special Catalytic Systems

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