Selective Catalytic Reduction (SCR) catalysts are used to reduce NO_x emissions from internal combustion engines in a variety of applications [1,2,3,4]. Southwest Research Institute (SwRI) performed an Internal Research & Development project to study SCR catalyst thermal deactivation. The study included a V/W/TiO₂ formulation, a Cu-zeolite formulation and a Fe-zeolite formulation. This work describes NH₃ storage capacity measurement data as a function of aging time and temperature. Addressing one objective of the work, these data can be used in model-based control algorithms to calculate the current NH₃ storage capacity of an SCR catalyst operating in the field, based on time and temperature history. The model-based control then uses the calculated value for effective DEF control and prevention of excessive NH₃ slip. Addressing a second objective of the work, accelerated thermal aging of SCR catalysts may be achieved by elevating temperatures above normal operating temperatures. Time and temperature correlations use the Arrhenius equation[5], which requires a formulation-specific deactivation energy value (Ed). The NH₃ storage capacity data generated in this work were used to calculate an Ed value for each of the three SCR catalyst formulations.

Presenter
Gordon J. Bartley, Southwest Research Institute