Effect of Air-Fuel Ratio Modulation on Conversion Efficiency of Three-Way Catalysts

Kaneko, Yasuo; Kobayashi, Hideo; Komagome, R.; Hirako, Osamu; Nakayama, Osamu

doi:10.4271/780607

Cited by 19 publications

(7 citation statements)

References 6 publications

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“…That is, the range of feedstream stoichiometry over which a given conversion (say, 50%) is achieved is broader when the feedstream composition oscillates. This has been reported for actual exhaust streams as well (Adawi et al, 1977; Kaneko et al, 1978).…”

Section: Frequency Effectssupporting

confidence: 74%

“…This cycling en-vironment has been shown to widen the range of engine air/fuel ratios (that is, the operating "window") over which a catalyst can yield a specified degree of conversion (Adawi et al, 1977). On the other hand, the peak catalyst efficiency under cycling conditions is lower than under steady-state conditions (Kaneko et al, 1978). Clearly there are tradeoffs made in formulating three-way catalysts and in establishing operating conditions in order to optimize the overall control system performance.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory reactor system for three-way automotive catalyst evaluation

Schlatter¹,

Sinkevitch²,

Mitchell³

1983

Ind. Eng. Chem. Prod. Res. Dev.

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The exhaust composition in closed-loop emission control systems typically oscillates about the stoichiometric set point. We describe herein the laboratory system we developed to investigate catalyst behavior in such an environment. The design is such that the frequency, amplitude, and average composition of the oscillations can be varied independently of one another. In laboratory testing of a platinum-rhodium catalyst it was demonstrated that the "window" for three-way conversion could be Improved via oscillations of low frequency or large amplitude, but peak conversion efficiencies were sacrificed in the process. On samples aged in engine exhaust or at high temperature, cycling effects were most evident under near-stoichiometric conditions.

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Section: Frequency Effectssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Laboratory reactor system for three-way automotive catalyst evaluation

Schlatter¹,

Sinkevitch²,

Mitchell³

1983

Ind. Eng. Chem. Prod. Res. Dev.

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show abstract

“…[Though not shown here, net reducing conditions increase the selectivity of NO reduction to ammonia which is not the preferred reduction product (Taylor, 197511. Greater NO removal under net oxidizing conditions with cycled than with steady feed composition has been described in the literature as a "widening of the window" of operation (Schlatter et al, 1981;Gandhi et al, 1976;Kaneko et al, 1978;Falk and Mooney, 1980) and has been examined as a function of cycling frequency and amplitude. The influence on catalyst performance of asymmetric vs. sym- 1 1 .…”

Section: Catalyst Performance At 550 "C With Cycled Feedsmentioning

confidence: 97%

“…This cycling enCatalytica Associates, Inc., 3255 Scott Blvd., Suite 7-E, Santa Clara, CA 95051. vironment has been shown to widen the range of engine &/fuel ratios (that is, the operating "window") over which a catalyst can yield a specified degree of conversion (Adawi et al, 1977). On the other hand, the peak catalyst efficiency under cycling conditions is lower than under steady-state conditions (Kaneko et al, 1978). Clearly there are tradeoffs made in formulating three-way catalysts and in establishing operating conditions in order to optimize the overall control system performance.…”

Section: Introductionmentioning

confidence: 99%

Behavior of automobile exhaust catalysts with cycled feedstreams

Taylor¹,

Sinkevitch²

1983

Ind. Eng. Chem. Prod. Res. Dev.

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The response of an exhaust-aged three-way catalyst to perturbations in the feedstream stoichiometry was examined in laboratory experiments. The air-fuel ratio was perturbed using both symmetric and asymmetric cycling and a range of net stoichiometries. The conversions of NO and CO were determined using the cycled feeds and steady feeds of equivalent net stoichiometry. At 550 O C cycling the feed benefited conversion at average air-fuel ratios away from the stoichiometric composition. This effect was more pronounced with asymmetric than symmetric cycles. Cycling the air-fuel ratio of the simulated exhaust gas during warm-up of the catalyst did not significantly benefit either NO or CO conversion.

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“…Integration of cost-effective computational power and sensing technologies provided dramatic improvements to performance and operation while complying with new emissions regulations through active engine management and three-way catalyst functionality (Kummer, 1980). Research began to illustrate that improvements to engine operation could occur with technologies, such as active spark control (Kraus et al, 1978), air-fuel-ratio control (Rivard, 1973;Zechnall et al, 1973;Holl, 1980), and advances in catalyst operation and conversion efficiency at stoichiometric operation (Kaneko et al, 1978;Hegedus et al, 1979;Kummer, 1980). Although reduced AKI of unleaded gasoline and a lack of maturity in emissions catalyst proved to be detrimental to engine compression ratio during the regulatory age, new engine management features and controls were found to enable increases in knock tolerance and associated compression ratio and performance without changes to fuel AKI.…”

Section: Digital Agementioning

confidence: 99%

A Historical Analysis of the Co-evolution of Gasoline Octane Number and Spark-Ignition Engines

2016

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In this work, the authors reviewed engine, vehicle, and fuel data since 1925 to examine the historical and recent coupling of compression ratio and fuel antiknock properties (i.e., octane number) in the U.S. light-duty vehicle market. The analysis identified historical time frames and trends and illustrated how three factors-consumer preferences, technical capabilities, and regulatory legislation-affect personal mobility. Data showed that over many decades these three factors have a complex and time-sensitive interplay. Long-term trends in the data were identified where interaction and evolution between all three factors were observed. Specifically, transportation efficiency per unit power (gal/ton-mi/hp) was found to be a good metric to integrate technical, societal, and regulatory effects into the evolutional pathway of personal mobility. From this framework, discussions of future evolutionary changes to personal mobility are also presented, with a focus centered on how increasing fuel octane number can help to enable sustained improvement in transportation efficiency per unit power.

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Effect of Air-Fuel Ratio Modulation on Conversion Efficiency of Three-Way Catalysts

Cited by 19 publications

References 6 publications

Laboratory reactor system for three-way automotive catalyst evaluation

Laboratory reactor system for three-way automotive catalyst evaluation

Behavior of automobile exhaust catalysts with cycled feedstreams

A Historical Analysis of the Co-evolution of Gasoline Octane Number and Spark-Ignition Engines

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