Response characteristics of stable mixed-potential NH₃ sensors in diesel engine exhaust

Journal Article · Thu Oct 20 00:00:00 EDT 2016 · Emission Control Science & Technology

DOI:https://doi.org/10.1007/s40825-016-0050-2· OSTI ID:1357966

Brosha, Eric L. ^[1]; Prikhodko, Vitaly Y. ^[2]; Kreller, Cortney R. ^[1]; Pihl, Josh A. ^[2]; Curran, Scott ^[2]; Park, II, James E. ^[2]; Mukundan, R. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Oak Ridge National Lab. (ORNL), Knoxville, TN (United States). National Transportation Research Center

Here, a mixed-potential, electrochemical sensor platform is extended to NH₃ sensing by the introduction of a new gold alloy working electrode. A planar, pre-commercial NH₃ sensor utilized LANL’s controlled interface approach, and a Pd-Au alloy working electrode was tested in exhaust of a GM 1.9 L diesel engine downstream of a diesel oxidation catalyst through a slipstream arrangement. A fraction of the exhaust was pulled across the sensor with a pump at 20 L/min. In order to simulate NH₃ slip inside of a full SCR emissions control system, NH₃ was injected immediately upstream of the sensor using a calibrated mass flow controller. The sensor response quantitatively tracked the NH₃ as measured via Fourier transform infrared (FTIR) analyzer. A calibration curve was obtained in the exhaust from an ammonia staircase response with the engine running at steady-state engine conditions resulting in low background concentrations of NO_x and HC (<20 ppm) during calibration. Exhaust gas recirculation (EGR) switching and sweeps were used to evaluate the NH₃ sensor response under different amounts of total background NO_x. The calibration curve was used to directly compare the [NH₃] calculated from sensor response to the gas phase composition measured via FTIR. In general, there was excellent quantitative agreement between the sensor response and the actual NH₃ in the exhaust gas, and fast response time such that transients (<5 ppm) could be easily discerned from baseline. A LANL pre-commercial NO_x sensor was tested simultaneously with the NH₃ sensor and the extent of cross-sensitivity between the two sensors will be discussed.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States); National Transportation Research Center (NTRC); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: AC05-00OR22725; AC52-06NA25396
• OSTI ID: 1357966
• Alternate ID(s): OSTI ID: 1406205
• Report Number(s): LA-UR--16-26242; VT0401000; CEVT010
• Journal Information: Emission Control Science & Technology, Journal Name: Emission Control Science & Technology Journal Issue: 1 Vol. 3; ISSN 2199-3629
• Publisher: Springer
• Country of Publication: United States
• Language: English

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Electrochemical
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Mixed-potential
Energy Sciences
ammonia sensor
electrochemical
mixed-potential
sensor