Modeling the selective catalytic reduction of NOx by ammonia over a Vanadia-based catalyst from heavy duty diesel exhaust gases

A numerical simulation for prediction of NOX conversion over a commercial V2O5 catalyst with NH3 as a reductant was performed for a heavy duty diesel engine applications. The chemical behaviors of the SCR reactor are described by using the global NOX kinetics including standard, fast, and NH3 oxidation reactions with the Langmuir–Hinshelwood (LH) mechanism incorporated into the commercial Boost code. After introducing mathematical models for the SCR reaction with specific reaction parameters, the effects of various parameters such as space velocities, the O2, H2O, NO2, and NH3 concentrations on the NOx conversion are thoroughly studied and validated by comparing with the experimental data available in the literature. It is found that NOX conversion increases with decreasing space velocity, H2O concentration, and NH3/NOX ratio, and increasing O2 concentration and NO2/NOX ratio. The study shows that not only is the present approach adopted is flexible in treating performance of the commercial V2O5 based SCR catalyst, it is also accurate and efficient for the prediction of NOX conversion in diesel exhaust environments.