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

Danai Poulidi, Efstratios Stavrakakis

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Abstract

The combined promotional effect of electrochemically-supplied O2- 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 O2- promoting species to an increased overall promotion of the catalytic rate. At higher sodium coverages, i.e. θNa≥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.

Original languageEnglish
Number of pages4
JournalTopics in Catalysis
Early online date12 Jan 2018
DOIs
Publication statusEarly online date - 12 Jan 2018

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Carbon Monoxide
Oxidation
Catalysts
Sodium
Ions
Oxygen
Oxides
Networks (circuits)

Keywords

  • Electrochemical Promotion
  • CO oxidation
  • Na promotion
  • multiple promoters

Cite this

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title = "Electrochemical Promotion of CO Oxidation on Na-promoted Pt/YSZ: Interaction between Multiple Promoting Species",
abstract = "The combined promotional effect of electrochemically-supplied O2- 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 O2- promoting species to an increased overall promotion of the catalytic rate. At higher sodium coverages, i.e. θNa≥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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Electrochemical Promotion of CO Oxidation on Na-promoted Pt/YSZ: Interaction between Multiple Promoting Species. / Poulidi, Danai; Stavrakakis, Efstratios.

In: Topics in Catalysis, 12.01.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Electrochemical Promotion of CO Oxidation on Na-promoted Pt/YSZ: Interaction between Multiple Promoting Species

AU - Poulidi, Danai

AU - Stavrakakis, Efstratios

PY - 2018/1/12

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N2 - The combined promotional effect of electrochemically-supplied O2- 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 O2- promoting species to an increased overall promotion of the catalytic rate. At higher sodium coverages, i.e. θNa≥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.

AB - The combined promotional effect of electrochemically-supplied O2- 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 O2- promoting species to an increased overall promotion of the catalytic rate. At higher sodium coverages, i.e. θNa≥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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KW - Na promotion

KW - multiple promoters

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