Free course

The three-way catalytic converter

Free statement of participation on completion

This free course is concerned primarily with the chemistry that underpins the operation of the three-way catalytic converter that is placed in the exhaust systems of motor vehicles in order to reduce the emissions of primary pollutants: carbon monoxide, oxides of nitrogen and volatile organic compounds, including hydrocarbons. Discussion of the various effects of these pollutants and the consequent introduction and refinement of 'automotive emission regulations' has not been included, nor is there a look forward to future research trends.

Course learning outcomes

After studying this course, you should be able to:

  • discuss how the gas mixture expelled from the engine, and the conversion performance of the three-way catalytic converter, depend on the air/fuel (A/F) ratio
  • list the chemical reactions whereby the three-way catalyst removes carbon monoxide (CO), hydrocarbons and oxides of nitrogen (NOx) from petrol vehicle exhausts
  • interpret the results of experimental studies (involving activity tests, kinetic measurements, adsorption studies and/or various surface science techniques) of the three-way catalyst and appropriate model systems
  • discuss possible mechanisms for the catalytic reactions removing CO, hydrocarbons and NOx from vehicle exhausts
  • outline the modes of deterioration of the three-way catalyst, and comment on the strategies that could be used to reduce H2S emissions.