Impact of operation parameters and lambda input signal during lambda-dithering of three-way catalysts for low-temperature performance enhancement

Hodonj, Daniel; Borchers, Michael; Zeh, Lukas; Hoang, Gia Trung; Tischer, Steffen; Lott, Patrick; Deutschmann, Olaf

doi:10.1016/j.apcatb.2023.123657

Cited by 4 publications

(3 citation statements)

References 76 publications

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“…With regard to secondary emission formation that is typically provoked by rich conditions and which may even occur as a consequence of hydrocarbon–NO x interactions over oxidation catalysts in lean conditions, 40,83 NH 3 evolution is most relevant, whereas only very minor amounts of N 2 O form in the absence of oxygen ( c.f. ESI† Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Coated honeycombs were tested under static and dynamic conditions in an in-house built catalyst testing bench described elsewhere. 40–43 The monolithic catalyst sample was wrapped in quartz glass wool and mounted between two thermocouples (TC direct; 1 mm outer diameter, type N) that were held in the middle of the quartz glass tubular reactor (1.6 cm inner diameter) by inert honeycombs (1.0 cm in length) within the reactor for temperature control. In addition to lambda ( λ ) sensors (LSU 4.9, Bosch) installed at the inlet and outlet of the reactor, the concentrations of the gas stream exiting the reactor were analyzed in a Fourier-transform infrared (FTIR) spectrometer (MG2030, MKS Instruments).…”

Section: Methodsmentioning

confidence: 99%

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Spatiotemporal insights into forced dynamic reactor operation for fast light-off of Pd-based methane oxidation catalysts

Keller,

Hodonj,

Zeh

et al. 2024

Catal. Sci. Technol.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Spatiotemporal insights into forced dynamic reactor operation for fast light-off of Pd-based methane oxidation catalysts

Keller,

Hodonj,

Zeh

et al. 2024

Catal. Sci. Technol.

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“…Moreover, using ceria (CeO 2 ), zirconia (ZrO 2 ), or tin oxide (SnO 2 ) as support material was reported to reduce the negative impact of water (Ciuparu et However, choosing appropriate engine operation strategies can signi cantly contribute to maintaining high pollutant conversion rates as well. For instance, high-frequency lean-rich cycling, so-called dithering, can enhance pollutant conversion particularly in the low-temperature regime -a concept that is known for stoichiometric applications since decades (Hegedus et al 1980, Muraki andFujitani 1986) and that currently enjoys growing popularity again (Deka et al 2023, Roger et al 2023, Hodonj et al 2024). Similarly, periodic cycling between lean and short rich exhausts can increase the CH 4 oxidation activity of lean-operated Pd catalysts in humid exhausts, presumably by decomposition of adsorbed hydroxyl species during the rich phase along with an optimization of the oxidation state and morphology of the noble metal particles (Bounechada et al 2012, Ferri et al 2018, Karinshak et al 2020, Franken et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Innovative Engine Test Bench Setup for Testing of Exhaust Gas Aftertreatment and detailed Gas Species Analysis for CNG-SI-Operation

Tomin,

Keller,

Wagner

et al. 2024

Preprint

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For an efficient reduction of methane slip, a precise understanding of exhaust gas aftertreatment under real conditions is essential. Since it is not possible to produce catalytic converters in near-series geometry on a laboratory scale, it is necessary to resort to significantly smaller sample catalysts. Therefore, an engine test bench was designed to ensure real operating conditions for such samples with the help of space velocity and temperature control. A comparison between the actual and reference values of the space velocity results in a small deviation of 0.1% on average. Furthermore, the pressure conditions at the catalyst have been measured showing a propagation of pressure oscillations from the engine outlet which in combination with the space velocity regulation show that real conditions could be applied to the catalyst sample. Subsequently the exhaust gas concentrations were monitored with a Fourier transform infrared spectrometer. The catalyst material used is Pd on Al2O3 common for methane oxidation. The measurements show that the CH4 conversion is higher under lean conditions, but is below complete conversion. In a final comparison between purely stoichiometric operation and dithering, the course of the CH4 conversion rate over the test period is examined more closely. In addition to sampling pre- and post-catalyst, the exhaust gas composition is measured spatially resolved within a catalyst channel using special measurement technology. In the temporal course of the CH4 emissions, a stabilising effect due to the change of the operating mode can be seen showing that dithering seems to prevent further deactivation.

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Innovative engine test bench set-up for testing of exhaust gas aftertreatment and detailed gas species analysis for CNG-SI-operation

Tomin,

Keller,

Wagner

et al. 2024

Automot. Engine Technol.

View full text Add to dashboard Cite

For an efficient reduction of methane slip, a precise understanding of exhaust gas after treatment under real conditions is essential. Since it is not possible to produce catalytic converters in near-series geometry on a laboratory scale, it is necessary to resort to significantly smaller sample catalysts. Therefore, an engine test bench was designed to ensure real operating conditions for such samples with the help of space velocity and temperature control. A comparison between the actual and reference values of the space velocity results in a small deviation of 0.1% on average. Furthermore, the pressure conditions at the catalyst have been measured showing a propagation of pressure oscillations from the engine outlet which in combination with the space velocity regulation show that real conditions could be applied to the catalyst sample. Subsequently, the exhaust gas concentrations were monitored with a Fourier transform infrared spectrometer. The catalyst material used is PdO on Al2O3, common for methane oxidation. The measurements show that the CH4 conversion is higher under lean conditions, but is below complete conversion. In a final comparison between purely stoichiometric operation and dithering, the course of the CH4 conversion rate over the test period is examined more closely. In addition to sampling pre- and post-catalyst, the exhaust gas composition is measured spatially resolved within a catalyst channel using special measurement technology. In the temporal course of the CH4 emissions, a stabilizing effect due to the change of the operating mode can be seen, showing that dithering seems to prevent further deactivation.

show abstract

Impact of operation parameters and lambda input signal during lambda-dithering of three-way catalysts for low-temperature performance enhancement

Cited by 4 publications

References 76 publications

Spatiotemporal insights into forced dynamic reactor operation for fast light-off of Pd-based methane oxidation catalysts

Spatiotemporal insights into forced dynamic reactor operation for fast light-off of Pd-based methane oxidation catalysts

Innovative Engine Test Bench Setup for Testing of Exhaust Gas Aftertreatment and detailed Gas Species Analysis for CNG-SI-Operation

Innovative engine test bench set-up for testing of exhaust gas aftertreatment and detailed gas species analysis for CNG-SI-operation

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