Rules and Mathematical Modeling of Electrochemical and Chemical Promotion

Vayenas, C.G.; Brosda, S.; Pliangos, C.

doi:10.1006/jcat.2001.3348

Cited by 135 publications

(134 citation statements)

References 101 publications

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“…This behaviour changes at higher temperatures where a rate enhancement is observed for both anodic and cathodic polarization. This behaviour is known as inverted volcano behaviour and according to the recently identified rules of electrochemical promotion [14,33] it is observed when both the electron donor (C 2 H 4 ) and the electron acceptor (O) reactants are absorbed weakly on the catalyst surface, i.e. when they are both present on the catalyst surface at low coverages.…”

Section: Ethylene Oxidationmentioning

confidence: 98%

“…the reaction exhibits purely electrophobic behaviour ð@r=@U > 0Þ [13,14]. According to the recently established rules of electrochemical promotion [14,33] this type of behaviour is obtained when the electron acceptor reactant (O) is more strongly adsorbed on the catalyst surface than the electron donor (C 2 H 4 ) reactant. This behaviour changes at higher temperatures where a rate enhancement is observed for both anodic and cathodic polarization.…”

Section: Ethylene Oxidationmentioning

confidence: 99%

“…Former studies of the same reaction on Rh catalyst films have shown that application of currents or potentials can affect significantly and in a reversible manner the stability limits of surface Rh oxide, thus affecting the catalytic activity in a pronounced manner [14,33,39,40].…”

Section: Ethylene Oxidationmentioning

confidence: 99%

“…Recent work has identified simple and rigorous rules which permit the prediction of the rate dependence on catalyst potential, U WR , and work function F and thus allow for the prediction of the sign of L on the basis of the unpromoted kinetics [14,33].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical promotion of RuO2 catalysts for the combustion of toluene and ethylene

et al. 2005

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The electrochemical promotion of the complete catalytic oxidation of ethylene and toluene on RuO 2 Catalyst films deposited on Y 2 O 3 -stabilized-ZrO 2 (YSZ) has been investigated at temperatures 400 to 500°C. Anodic polarization (1.5 V), i.e. O 2) supply from the YSZ support to the catalyst, is found to enhance the rates of ethylene and toluene oxidation by a factor of 10 and 8 respectively. Cathodic polarization ()1.5 V) i.e. oxygen removal from the catalyst, enhances the oxidation rates by a factor of 3 and 4, respectively. These rate enhancements are strongly nonFaradaic. The kinetics, positive order in both reactants, and the promotional results, inverted-volcano type for both reactions, conform to the recently found rules of electrochemical promotion.

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Section: Ethylene Oxidationmentioning

confidence: 98%

Section: Ethylene Oxidationmentioning

confidence: 99%

Section: Ethylene Oxidationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrochemical promotion of RuO2 catalysts for the combustion of toluene and ethylene

et al. 2005

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“…Depending on the catalytic rate, r, response to changes of catalyst potential, ΔU WR (or ΔΦ), there are four types of behaviours at constant reactive conditions [4]: -Electrophobic, when ∂r/∂Φ > 0. -Electrophilic, when ∂r/∂Φ < 0.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Promotion of CO Oxidation on Na-Promoted Pt/YSZ: Interaction Between Multiple Promoting Species

Stavrakakis

Poulidi

2018

Top Catal

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The combined promotional effect of electrochemically-supplied O 2− and chemically-supplied Na + promoters, was studied for the case of CO oxidation on Pt/YSZ. Four different sodium coverages (0.16, 1.6, 8 and 40%) were loaded onto the catalyst surface and the catalytic behaviour was compared with a nominally 'clean' catalyst under a wide range of reactants' ratios under open-circuit and polarised conditions. Sodium generally increased oxygen adsorption by lowering the work function of the catalyst. However, sodium promoted the catalytic rate only at coverages up to 1.6% and worked synergistically with O 2− promoting species to an increased overall promotion of the catalytic rate. At higher sodium coverages, i.e. θ Na ≥ 8%, the catalytic behaviour was strongly affected by the interactions between the sodium species, the catalyst, the reactants and oxygen ions promoting species. The postulated formation of stable sodium oxide species on the catalyst pores reduced the active catalytic area which resulted in poisoning the catalytic rate and suppressing EPOC effect, respectively. It is suggested that these stable sodium oxide species which also induced a permanent EPOC effect by oxygen storage, were formed by the migrated oxygen ions.

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Heterogeneous Catalysis and High Electric Fields

Kruse

Bocarmé

2008

Handbook of Heterogeneous Catalysis

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Introduction The relationships between high electric fields and heterogeneous catalysis are twofold: First, high electric fields are applied in field emission and field ion microscopes and related methods. These techniques can provide detailed in situ information on catalytic surface processes with a lateral resolution on the atomic scale. Second, high electric fields can affect the surface properties of solids. Electronic and structural parameters are frequently field dependent and influence chemisorption processes of molecules and also catalytic activity and reaction pathways of surface reactions.High electric fields, defined as fields of the order of some tens of volts per nanometer, are what valence electrons in atoms and molecules experience and what these electrons are exposed to on adsorption at solid surfaces. Thus, these fields are ubiquitous in chemistry and form, in the context of this contribution, an intimate part of heterogeneous catalysis. Quantum mechanical aspects of chemical bonding of solid surfaces distinguish between shortrange covalent and long-range electrostatic contributions. These long-range effects create an electrostatic Coulomb potential which causes changes in ionization potentials and electron affinities of adsorbed molecules. As a consequence, catalytic surface reactions may be altered. However, in real catalysts it is sometimes difficult to distinguish between contributions of local binding and long-range electrostatic fields.Long-range fields of the order of 10 V nm −1 are generated in a controlled manner in the field ion microscope, originally developed by Muller [1] for imaging * Corresponding author.

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Rules and Mathematical Modeling of Electrochemical and Chemical Promotion

Cited by 135 publications

References 101 publications

Electrochemical promotion of RuO2 catalysts for the combustion of toluene and ethylene

Electrochemical promotion of RuO2 catalysts for the combustion of toluene and ethylene

Electrochemical Promotion of CO Oxidation on Na-Promoted Pt/YSZ: Interaction Between Multiple Promoting Species

Heterogeneous Catalysis and High Electric Fields

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