Improvement of LSM15-CGO10 electrodes for electrochemical removal of NOx by KNO3 and MnOx impregnation

LSM15-CGO10 (La0.85Sr0.15MnO3-Ce0.90Gd0.1O1.95) electrodes were impregnated with either KNO3 or MnOx, and the effect of the impregnations on the activity in NO containing atmospheres was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The electrodes were tested in 1000 ppm NO, 10% O2 and 1000 ppm NO + 10% O2 in the temperature range 300-500 °C and the electrodes were investigated by scanning electron microscopy before and after testing. At 400-450 °C a NOx-storage process was observed on the KNO3-impregnated electrodes, this process appeared to be dependent on preceding catalytically formation of NO2. Despite a marked difference in the microstructure of the impregnated KNO3 and MnOx, both impregnations caused a significant reduction in the polarization resistance of the electrodes, due to a general decrease in resistance of all the identified electrode processes. The effect of the impregnation was strongest at low temperatures, likely because the microstructure of the impregnated compounds changed at higher temperatures. Scanning electron microscopy images revealed a significant change in the microstructure of the impregnated samples after the test.