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Keywords:

  • NH3-SCR;
  • NOx reduction;
  • H2;
  • global kinetic model;
  • Ag/Al2O3

A global kinetic model which describes H2-assisted NH3-SCR over an Ag/Al2O3 monolith catalyst has been developed. The intention is that the model can be applied for dosing NH3 and H2 to an Ag/Al2O3 catalyst in a real automotive application as well as contribute to an increased understanding of the reaction mechanism for NH3-SCR. Therefore, the model needs to be simple and accurately predict the conversion of NOx. The reduction of NO is described by a global reaction, with a molar stoichiometry between NO, NH3 and H2 of 1:1:2. Further reactions included in the model are the oxidation of NH3 to N2 and NO, oxidation of H2, and the adsorption and desorption of NH3. The model was fitted to the results of an NH3-TPD experiment, an NH3 oxidation experiment, and a series of H2-assisted NH3-SCR steady-state experiments. The model predicts the conversion of NOx well even during transient experiments. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4325–4333, 2013