Solid Electrolyte Potentiometry Aided Studies of Oxidic Catalysts

Estenfelder, M.; Hahn, Thomas; Lintz, H.‐G.

doi:10.1081/cr-120027048

Cited by 11 publications

(8 citation statements)

References 55 publications

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“…The other electrode is exposed to the air and serves as a reference electrode. It has been shown that when certain requirements are fulfilled [17,18,20,21], the thermodynamic activity of atomic oxygen adsorbed on the catalyst surface is given by the equation:…”

Section: Electrochemical Techniques and Measurementsmentioning

confidence: 99%

Electrochemical promotion in O2− cells during propane oxidation

Kokkofitis¹,

Karagiannakis²,

Stoukides³

2007

Top Catal

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The catalytic oxidation of propane was studied in an oxygen ion conducting solid electrolyte cell at 623-773 K and atmospheric total pressure. Three catalyst-electrodes were tested, Pt, Pd and Ag. Under open circuit, the technique of Solid Electrolyte Potentiometry (SEP) was used to monitor the thermodynamic activity of oxygen adsorbed on the catalyst surface during reaction. Under closed circuit, the effect of electrochemical promotion was investigated. On Pt and Pd, the promoting effect was of the ''inverted volcano'' type. On Pt, the reaction exhibited a strong NEMCA effect; the closed circuit rate exceeded the open circuit rate by more than three orders of magnitude. On Pd, on the other hand, the effect was hardly Faradaic. On Ag, a moderate NEMCA behavior was observed and the promoting effect was purely electrophobic. Both open and closed circuit results obtained with these three catalyst-electrodes, are evaluated and compared to each other.

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Section: Electrochemical Techniques and Measurementsmentioning

confidence: 99%

Electrochemical promotion in O2− cells during propane oxidation

Kokkofitis¹,

Karagiannakis²,

Stoukides³

2007

Top Catal

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“…In the present case, the 1st product of the partial oxidation is strongly interacting and therefore less stable than the reactant propane. Similar measurements had been made in the partial oxidation of propene to acrolein and of acrolein to acrylic acid on industrial catalysts [2]. In both cases the partially oxidized products interact less with the catalyst than the reactant itself leading to the high product stability aimed at.…”

Section: Resultsmentioning

confidence: 70%

“…In this context we may remember that the SEP aided study of propene oxidation on copper oxides had shown that at CuO (oxygen activities above 10 À9 bar) mainly CO x was formed and that the existence of CU 2 O (a 2 O < 0 À9 bar) was necessary to the formation of acrolein [2]. Thus, the question arises if these results are significant and if the selectivity to partially oxidized compounds and the oxygen activity in the catalyst are related.…”

Section: Resultsmentioning

confidence: 87%

“…Measurements on metallic catalysts were summarized recently [1]. The benefits and limits of simultaneous kinetic and potentiometric measurements on oxides have equally been discussed [2]. In course of the study of the partial oxidation of propane to acrylic acid on MoVTeNb mixed oxide catalyst, the results of the kinetic investigation have been published elsewhere [3,4], we have shown the principle applicability of SEP measurements in this system.…”

Section: Introductionmentioning

confidence: 97%

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Potentiometric Measurements in the Partial Oxidation of Propane at a Mo?V?Te?Nb Oxide Catalyst

2004

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“…a Mars-van Krevelen mechanism or ionic reoxidation,w have been proposed for this type of catalytic reaction over oxide catalysts. 21,22 In some semiconducting catalysts, bulk oxygen is partially eliminated in the complete bulk to form lower oxides. 23 The participation of bulk oxygen in the reaction may be promoted if the semiconductor can accommodate large oxygen non-stoichiometry, d. In the case of SrTi 1Àx Fe x O 3Àd , the oxidation reaction most likely is not limited solely to adsorbed oxygen species, and also involves the bulk of the semiconductor.…”

Section: (A) General Modeling Approachmentioning

confidence: 99%

Modeling of hydrocarbon sensors based on p-type semiconducting perovskites

Sahner

Moos

2007

Phys. Chem. Chem. Phys.

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In the scope of the present contribution, perovskite SrTi(1-x)Fe(x)O(3-delta) was investigated as a model material for conductometric hydrocarbon sensing at intermediate temperatures between 350 and 450 degrees C. To explain the observations made during sensor optimization in a quantitative way, a novel sensor model was proposed. At the microscopic scale, the local gas concentration affects local conductivity of the gas sensitive material. In the case of n-type tin oxide sensors, this interaction is commonly attributed to a redox reaction between the reducing analyte gas and adsorbed oxygen. In contrast, a reduction process affecting the entire bulk was assumed to govern gas sensitivity of SrTi(1-x)Fe(x)O(3-delta) films. Although very few variables needed to be assumed or fitted, the present bulk-type model was found to represent well sensor functionality of p-type conducting SrTi(0.8)Fe(0.2)O(3-delta) films. In addition to the temperature dependence of sensor response, the hydrocarbon sensitivity, m, was predicted with good accuracy. The different sensor responses towards hydrocarbons with a different chemical reactivity and other cross-interfering species, such as NO, was explained as well as the dependence on film thickness for screen printed films.

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Solid Electrolyte Potentiometry Aided Studies of Oxidic Catalysts

Cited by 11 publications

References 55 publications

Electrochemical promotion in O2− cells during propane oxidation

Electrochemical promotion in O2− cells during propane oxidation

Potentiometric Measurements in the Partial Oxidation of Propane at a Mo?V?Te?Nb Oxide Catalyst

Modeling of hydrocarbon sensors based on p-type semiconducting perovskites

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