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Dosimeter-type NOx sensing properties of KMnO4 and its electrical conductivity during temperature programmed desorption.

Groß A, Kremling M, Marr I, Kubinski DJ, Visser JH, Tuller HL, Moos R - Sensors (Basel) (2013)

Bottom Line: An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed.With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer.The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres.

View Article: PubMed Central - PubMed

Affiliation: Zentrum für Energietechnik, Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95440 Bayreuth, Germany. andrea.gross@uni-bayreuth.de

ABSTRACT
An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT) for NOx storage catalysts (NSC) enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD). The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1) time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2) during the short-term thermal NOx release.

No MeSH data available.


Related in: MedlinePlus

Correlation between electrical responses ΔRrel (during sorption) and FG (upon regeneration) affected by NOx exposure.
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f13-sensors-13-04428: Correlation between electrical responses ΔRrel (during sorption) and FG (upon regeneration) affected by NOx exposure.

Mentions: The equivalency of the two conductivity-related sensor responses ΔRrel and FG of KMnO4/La-Al2O3 as a measure for the cumulated NOx exposure is demonstrated in Figure 13 as a monotone and almost linear correlation, independent of the type of exposed NOx species. Both values can be applied as NOx dosimeter-type sensor responses and correlate linearly with the quantity of sorbed NOx, enabling in-situ monitoring of the loading state, although they are analyzed upon NOx sorption at 380 °C (ΔRrel) and upon NOx release by heating up to 650 °C (FG), respectively. Hence, dependent on the application and the information of interest, two different sensing modes are feasible with the proposed impedimetric NOx dosimeter based on KMnO4. In both cases, NOx is accumulated in the sensitive layer at sorption temperature and thermally released during periodic regeneration intervals. However, in the first method, the change in the conductance during NOx accumulation in the low loading state is monitored as a continuous and linear measure for the cumulated NOx exposure as well as for the amount of sorbed NOx. Concentration information can be obtained time-continuously from the signal derivative. On the contrary, in the second method, the integrated difference between the conductivity during NOx release upon heating and the conductivity in the unloaded state serves as the measurand. Unfortunately, no time-continuous information on the NOx concentration can be obtained.


Dosimeter-type NOx sensing properties of KMnO4 and its electrical conductivity during temperature programmed desorption.

Groß A, Kremling M, Marr I, Kubinski DJ, Visser JH, Tuller HL, Moos R - Sensors (Basel) (2013)

Correlation between electrical responses ΔRrel (during sorption) and FG (upon regeneration) affected by NOx exposure.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3673092&req=5

f13-sensors-13-04428: Correlation between electrical responses ΔRrel (during sorption) and FG (upon regeneration) affected by NOx exposure.
Mentions: The equivalency of the two conductivity-related sensor responses ΔRrel and FG of KMnO4/La-Al2O3 as a measure for the cumulated NOx exposure is demonstrated in Figure 13 as a monotone and almost linear correlation, independent of the type of exposed NOx species. Both values can be applied as NOx dosimeter-type sensor responses and correlate linearly with the quantity of sorbed NOx, enabling in-situ monitoring of the loading state, although they are analyzed upon NOx sorption at 380 °C (ΔRrel) and upon NOx release by heating up to 650 °C (FG), respectively. Hence, dependent on the application and the information of interest, two different sensing modes are feasible with the proposed impedimetric NOx dosimeter based on KMnO4. In both cases, NOx is accumulated in the sensitive layer at sorption temperature and thermally released during periodic regeneration intervals. However, in the first method, the change in the conductance during NOx accumulation in the low loading state is monitored as a continuous and linear measure for the cumulated NOx exposure as well as for the amount of sorbed NOx. Concentration information can be obtained time-continuously from the signal derivative. On the contrary, in the second method, the integrated difference between the conductivity during NOx release upon heating and the conductivity in the unloaded state serves as the measurand. Unfortunately, no time-continuous information on the NOx concentration can be obtained.

Bottom Line: An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed.With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer.The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres.

View Article: PubMed Central - PubMed

Affiliation: Zentrum für Energietechnik, Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95440 Bayreuth, Germany. andrea.gross@uni-bayreuth.de

ABSTRACT
An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT) for NOx storage catalysts (NSC) enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD). The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1) time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2) during the short-term thermal NOx release.

No MeSH data available.


Related in: MedlinePlus