Development and Validation of an Oxygen Storage Model for Three Way Catalysts

Due to stringent emissions legislation, the use of three way catalysts is becoming increasingly prevalent in motorcycles and scooters. This paper describes the development, and subsequent validation, of a detailed mathematical model for the oxygen storage processes in three-way catalysts. The model consists of several interdependent sub-models describing the oxidation and reduction processes and their interaction with a kinetic model of the catalyst. The structure and equations of the model are detailed and their significance discussed. For the validation phase of the work a purpose-built miniature catalyst test rig has been assembled and a series of experiments conducted to assess the oxygen storage processes. Analysis of this data also provided values for the controlling constants associated with the oxidation and reduction reactions. These results are included and compared with other published data. The analytical results from the experimental work have been used to provide the model with the important kinetic control factors, which are not readily available from literature. Finally, the experimental results are compared with the model predictions and good agreement is shown.