Reducing NO x in diesel exhausts by SCR technique: Experiments and simulations

Results of experiments are compared to simulations of the performance of V 2 O 5 /γ‐alumina SCR catalyst used to remove nitrogen oxides from diesel exhausts. The kinetic model is based on Eley‐Rideal kinetics. Temperature programmed desorption (TPD) of the ammonia is used to evaluate adsorption/desorption parameters. Stationary experiments on a 3.6‐dm 3 engine with a 4.8‐dm 3 honeycomb catalyst is used to evaluate kinetic rate parameters for the reduction of NO with NH 3 . The desorption activation energy, E a,des , is best fitted as a function of surface coverage yielding E a,des = 240* (I −0.44* θ ) kJ/mol. A dynamic test (FTP) with a 12‐dm 3 engine and24.8‐dm3 honeycomb catalyst is done with astoichiometric injection of ammonia. The NO x conversion is 52%, but during the freeway traffic the conversion reached 72%. The prediction of NO x conversion is good, but there are some deviations for temperature and ammonia slip.