Development of a sensitive and selective mixed-potential ammonia sensor for automotive exhausts - Archive ouverte HAL
Communication Dans Un Congrès Année : 2019

Development of a sensitive and selective mixed-potential ammonia sensor for automotive exhausts

Résumé

One of the most effective technologies in decreasing large-scale NOx emission produced by diesel engine vehicles is Urea-SCR (selective catalytic reduction) system. In order to prevent inducing excessive ammonia to the environment, an NH3 sensor is required at the exit of this system. In this study, highly selective ammonia sensors were developed to detect ammonia emissions from automotive exhaust. The sensors were fabricated with 8-YSZ electrolyte, a platinum reference electrode and a working electrode of Au-V2O5 (mass ratio: 85:15), screen-printed on an alumina supports. A platinum resistor was printed at the backside of the support to control the sensor temperature. The measured sensor response (ΔV) is the potential difference between reference and working electrodes. Figure 1 shows the responses of two identical sensors to 100 ppm CO, NO2, NO and 20 ppm of NH3 at four different temperatures. It can be seen that the sensors respond to all gases at lower temperatures while by increasing temperature to 600 °C the selectivity to NH3 is greatly improved. The selectivity of sensors was also confirmed by testing other possible interfering gases and no responses were observed for 20ppm of H2 and 100ppm of a hydrocarbon mixture. The stability of such sensors was studied at 550 °C and 600 °C. Since sensors showed no long term stability at 600 °C (electrode degradation), but remain stable results at 550 °C, investigations were made to decrease the selective working temperature while maintaining selectivity. After testing different mass percentages of V2O5 in working electrode, we observed that by increasing this value to 50%, the working temperature of selective ammonia sensors could be decreased to 550 °C with stable responses. Further investigations will be performed in order to gain deeper insight in sensing mechanism of V2O5 based working electrodes, which governs the sensor’s performance.
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Dates et versions

hal-02292212 , version 1 (19-09-2019)

Identifiants

  • HAL Id : hal-02292212 , version 1

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Gita Nematbakhsh Abkenar, Jean-Paul Viricelle, Mathilde Rieu, Philippe Breuil. Development of a sensitive and selective mixed-potential ammonia sensor for automotive exhausts. Euromat 2019 - European congress and exhibition on advanced materials and processes, Sep 2019, Stockholm, Sweden. ⟨hal-02292212⟩

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