Demonstration of a Catalytic Converter Using a Lawn Mower Engine

Catalytic conversion is an important tool in environmental-remediation strategies and source removal of pollutants. Because a catalyst is regenerated, the chemistry can be extremely effective for conversion of undesirable pollutant species to less harmful products in situations where the pollutants have accumulated or are being continuously produced. An important and well-known application is the catalytic converter in the exhaust system of an automobile. We have developed a laboratory experience that qualitatively demonstrates the use of a catalytic converter to decrease emissions from the exhaust of a small internal-combustion engine taken from a lawn mower. The experiment involves a flow-reactor system with an integrated mass spectrometer to monitor the flow-stream composition in real time. In addition to the techniques employed, the laboratory serves to highlight aspects of surface science and heterogeneous catalysis and also illustrates a significant problem associated with catalytic converters.