Simulation of OHC/SCR process over Ag/Al2O3 catalyst for removing NOx from diesel engine

A reaction kinetic model was developed to describe the selective catalytic reduction of NOx over Ag/Al2O3 with ethanol as the reductant, which was then used for numerical simulation and optimization of the deNOx performance of the oxygenated hydrocarbon (OHC)/SCR process. Results of numerical simulation of the one-dimensional pseudo-homogeneous reactor model have demonstrated the capability of the model, describing reasonably well the general trends of the experimental data such as the conversions of NO and C2H5OH as well as the formation of N2, NH3, CO, CH3CHO, CO2, N2O and HOCH2CH2NH2 during the ethanol/SCR process with respect to the reaction temperature, the reactor space velocity and the C1/NOx feed ratio covered in the present study. After successful validation of the reactor model, the axial concentration profiles within the reactor were used for the optimal design of a dual-bed catalyst system to enhance the deNOx performance of the ethanol/SCR by best utilizing the reaction intermediates in the rear bed following the Ag/Al2O3 in the front bed. The methodology developed in this work may provide useful guidance on the design of an OHC/SCR system using ethanol as the reductant, including, but not limited to, the diesel engine operating on E-diesel fuel.

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► A reaction kinetic model was developed for the ethanol/SCR over Ag/Al2O3 catalyst.
► The kinetic model was incorporated into pseudo-homogeneous fixed-bed reactor model.
► Model predictions were in good agreements with experimental data for NO, N2 and NH3.
► The model was applied to optimum design of a dual-bed reactor for enhanced activity.
► The model provides a useful guidance for developing more detailed reaction kinetics.