Development and Validation of a Multi-Site Kinetic Model for NH3-SCR over Cu-SSZ-13

Rohil  Daya, Isuzu Technical Center of America

A one-dimensional numerical model for a Cu-SSZ-13 SCR catalyst has been developed. This kinetic model is based on microreactor data collected using the latest ORNL SCR protocol, and captures all ranges of operating conditions for temperature, species concentration, space velocity and hydrothermal aging. The model includes H2O storage as well as two-site NH3 storage, and can predict N2O formation through the nitrate decomposition route. By storing the Ammonium Nitrate on a SCR site, the observed hysteresis behavior for Fast and NO2-SCR reactions could also be captured.

The developed model was validated using additional microreactor data at different ANRs, and through steady-state and transient engine dynamometer testing. The final validated model has numerous applications, including assisting in future hardware selection, urea dosing pre-calibration and model-based transient dosing control using virtual sensors. Some of these applications are demonstrated for the developed model. Future work includes extending the model to capture more realistic aging conditions, including sulfur and hydrocarbon poisoning models.

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