Electrochemical reduction of NOx - DTU Orbit

3 Experimental
3 Experimental
In this chapter an overview is given of the experiments conducted to investigate the effect of NOx
storage compounds on electrochemical deNOx. The overview includes the different test set-ups
used for the electrochemical characterisation of the electrodes, the fabrication of the electrodes
including addition of the NOx storage materials to the electrodes and the experimental techniques
used to characterise the electrodes.
3.1 Test set-ups for electrochemical characterisation
Three different test-set-ups were used for electrochemical testing of the electrodes. The test-set-
ups were:
1) Symmetric cell test set-up
2) Porous cell stack test set-up
3) 3-electrode pellet (3EP) test set-up
In general it applies for all the set-ups they can be used for electrochemical testing of solid oxide
electrodes at temperatures up to 500 °C in atmospheres containing NOx gases, oxygen and argon
in various proportions.
3.1.1 Symmetric cell test set-up
In Figure 1a a sketch of a symmetric cell mounted for electrochemical testing is shown, and Figure
1b shows the set-up used for simultaneous testing of 4 symmetric cells. The set-up is placed inside
a raku furnace and sealed; whereafter testing can be performed at elevated temperatures in
controlled atmospheres. The advantage of the symmetric cell test set-up is it allows for
simultaneous test of 4 cells, and since the symmetric cells are fairly easy to fabricate, the
symmetric cell test set-up allows for fast screening of many electrode materials. The disadvantage
of the symmetric cell test set-up is it is not suitable for gas analysis, which means any conversion
of NOx during the measurements is not detected, and the set-up can only be used for
electrochemical characterisation of electrodes without use of a reference electrode.
16