Influence of BaO in perovskite electrodes for the electrochemical reduction of NOx

Using the point electrode method, the effect of BaO on electrochemical reduction of NO (x) was investigated using the perovskites La0.85Sr0.15MnO3 (LSM15) and La0.85Sr0.15CoO3 (LSCo15) as electrode materials. The experiments were carried out in the temperature range 400-600 degrees C in 1% NO and 10% O-2, respectively. For the LSM15 electrode the ability to reduce NO compared to O-2 was increased when applying 20 wt% BaO in the electrode while the current density of the electrode was decreased approximately a decade. For the pure LSM15 electrode the highest current density ratio of NO and O-2 was obtained at 400 degrees C while the optimal temperature in term of current density ratios was 500 degrees C for the LSM15 + BaO and LSM15 + BaO + Pt electrodes. The activity of the electrode decreases when applying BaO or BaO + Pt to the electrode except for the LSM15 + BaO + Pt electrode at 500 degrees C where the activity is approximately the same as for the LSM15 electrode. The formation of Ba(NO3)(2) was clearly seen when applying 16.7 wt% BaO and 2 wt% Pt to the electrode. Generally it was observed that at 400 degrees C the activity of the electrodes were low, while at 600 degrees C the kinetics favored oxygen reduction compared to reduction of nitric oxide. The LSCO15 electrode containing BaO reacted to form a K2NiF4-structure and was not tested further.