In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies

Initial studies on aging detection of three way catalysts with a microwave cavity perturbation method were conducted. Two physico-chemical effects correlate with the aging state. At high temperatures, the resonance frequencies for oxidized catalysts (λ = 1.02) are not influenced by aging, but are significantly affected by aging in the reduced case (λ = 0.98). The catalyst aging state can therefore potentially be inferred from the resonance frequency differences between reduced and oxidized states or from the resonance frequency amplitudes during lambda oscillations. Secondly, adsorbed water at low temperatures strongly affects the resonance frequencies. Light-off experiment studies showed that the resonance frequency depends on the aging state at temperatures below the oxygen storage light-off. These differences were attributed to different water sorption capabilities of differently aged samples due to a surface area decrease with proceeding aging. In addition to the aging state, the water content in the feed gas and the temperature affect the amount of adsorbed water, leading to different integral electrical material properties of the catalyst and changing the resonance properties of the catalyst-filled canning. The classical aging-related properties of the catalyst (oxygen storage capacity, oxygen storage light-off, surface area), agreed very well with data obtained by the microwave-based method.

[1]  Ralf Moos,et al.  Direct Catalyst Monitoring by Electrical Means: An Overview on Promising Novel Principles , 2009 .

[2]  James E. Parks,et al.  Loading and Regeneration Analysis of a Diesel Particulate Filter with a Radio Frequency-Based Sensor , 2010 .

[3]  Martin Votsmeier,et al.  Microwave Cavity Perturbation as a Tool for Laboratory In Situ Measurement of the Oxidation State of Three Way Catalysts , 2013, Topics in Catalysis.

[4]  S. C. Parker,et al.  Water Adsorption and Its Effect on the Stability of Low Index Stoichiometric and Reduced Surfaces of Ceria , 2012 .

[5]  D. Pozar.  Microwave Engineering , 1990 .

[6]  Sung Bong Kang,et al.  Activity Function for Describing Alteration of Three-Way Catalyst Performance over Palladium-Only Three-Way Catalysts by Catalyst Mileage , 2011 .

[7]  Ralf Moos,et al.  Detection of the ammonia loading of a Cu Chabazite SCR catalyst by a radio frequency-based method , 2014 .

[8]  Ralf Moos,et al.  Microwave-Based Catalyst State Diagnosis - State of the Art and Future Perspectives , 2015 .

[9]  G. Grundmeier,et al.  Water adsorption on the a-Al_{2}O_{3}(0001) surface , 2009 .

[10]  Thomas O. Mason,et al.  Electrical and oxygen storage/release properties of nanocrystalline ceria-zirconia solid solutions , 2002 .

[11]  Harry L. Tuller,et al.  Defect Structure and Electrical Properties of Nonstoichiometric CeO2 Single Crystals , 1979 .

[12]  L. Gladden,et al.  Assessing the surface modifications following the mechanochemical preparation of a Ag/Al2O3 selective catalytic reduction catalyst , 2014 .

[13]  Gunter Hagen,et al.  TWC: Lambda Control and OBD without Lambda Probe - An Initial Approach , 2008 .

[14]  Lino Guzzella,et al.  Is oxygen storage in three-way catalysts an equilibrium controlled process? , 2009 .

[15]  Clemens Brinkmeier,et al.  Automotive three way exhaust aftertreatment under transient conditions : measurements, modeling and simulation , 2006 .

[16]  R. Moos,et al.  Replacing the lambda probe by radio frequency-based in-operando three-way catalyst oxygen loading detection , 2012 .

[17]  R. K. Nahar,et al.  A study of capacitance and resistance characteristics of an Al2O3 humidity sensor , 1982 .

[18]  Ralf Moos,et al.  A Laboratory Test Setup for in Situ Measurements of the Dielectric Properties of Catalyst Powder Samples under Reaction Conditions by Microwave Cavity Perturbation: Set up and Initial Tests , 2014, Sensors.

[19]  Michael Winkler,et al.  Gasoline engine combustion development for EU 6c emission legislation , 2014 .

[20]  Lingling Wang,et al.  High performance humidity sensors based on CeO2 nanoparticles , 2015 .

[21]  Jan-Dierk Grunwaldt,et al.  Abgasnachbehandlung in mobilen Systemen: Stand der Technik, Herausforderungen und Perspektiven , 2013 .

[22]  Corning,et al.  Vehicular Emissions in Review , 2012 .

[23]  Gunter Hagen,et al.  Combination of Wirebound and Microwave Measurements for In Situ Characterization of Automotive Three-Way Catalysts , 2011, IEEE Sensors Journal.

[24]  Ralf Moos,et al.  Catalyst State Observation via the Perturbation of a Microwave Cavity Resonator , 2008 .

[25]  Martin Votsmeier,et al.  SI-Engine Control With Microwave-Assisted Direct Observation of Oxygen Storage Level in Three-Way Catalysts , 2014, IEEE Transactions on Control Systems Technology.

[26]  Martin Votsmeier,et al.  Effect of propene, propane, and methane on conversion and oxidation state of three-way catalysts: a microwave cavity perturbation study , 2015 .