is an air pollutant harmful to both human health and environment, for which
reason NOx emissions must be lowered. A major source of NOx
emissions is vehicles, and especially for diesel vehicles there is a challenge in
removing NOx efficiently from the exhaust. Electrochemical reduction
of NOx is a novel technology for NOx removal from diesel
exhaust. This technology is based on NOx reduction in a ceramic,
electrochemical cell. However, a major challenge in the development of this
technology is to achieve a sufficiently high selectivity towards NOx conversion
on the electrodes.
Idea: Addition of NOx storage
compounds (e.g. BaO/Ba(NO3)2 or K2O/KNO3)
to the electrodes has been proven to increase the NOx conversion.
This is believed to some extent to be due to NOx getting stored as
nitrate on the electrode surface prior to the electrochemical reduction. Still,
experimental evidence of the NOx storage process on the ceramic
electrodes is missing. Raman spectroscopy is a method which can be used to investigate
the NOx storage and conversion process in situ, i.e. at realistic conditions with respect to temperature,
gas composition and electrical potential. The application of in situ Raman spectroscopy will provide
new insight regarding the NOx storage and conversion processes,
which will be crucial for the further development of this technology
Student task: This project is mainly
experimental. You will prepare electrodes for electrochemical NOx reduction
including adding a NOx storage compound to the electrodes by
infiltration. In our new Raman lab you will conduct in situ experiments, in which you monitor changes in both the
ceramic electrodes and the adsorbed gaseous species during the NOx conversion.
In addition to this the electrodes before and after test will be characterized
by for instance electron microscopy.