Electrochemical reduction of NO with propene in the presence of oxygen on LSCoM/CGO porous cell stacks impregnated with BaO

Abstract

The electrochemical reduction of NO with propene in the presence of 10 % O2 was studied on a La0.85Sr0.15Co0.03Mn0.97O3-Ce0.9Gd0.1O1.95 11-layer electrochemical reactor. BaO was impregnated into the porous reactor, and electrochemical impedance spectroscopy was used for characterisation in the temperature range of 300–400 °C. They were subjected to different magnitudes of polarisations, and the BaO impregnation was shown to have increased the NO reduction with increasing polarisation in the presence of excess oxygen. At 350 °C, more than 60 % was removed and a current efficiency for the cell stack of up to 30 % was achieved. In the presence of propene, the electrochemical promotion on the NOx conversion decreased and only 13 % was removed. A propene oxidation of 35 % was achieved as the highest at 400 °C. The propene acted as a reducing agent on the barium nitrates and caused a greater reduction of the nitrates and hereby releasing more NO than in the gas without propene. This caused an increase in NO in the outlet gas since not all of it was reduced further to nitrogen. The results indicate that the electrochemical reduction of the nitrates when no propene is present is a surface reaction, whereas the propene enables further reduction of the bulk nitrate.