Modeling and Performance Analysis of a Field-Aged Fe-Zeolite Catalyst in a Heavy Duty Diesel Engine Application 2016-01-9109

In this study a 1-dimensional computational model of a Fe-Zeolite catalyst, implementing conservation of mass, species and energy for both gas and catalyst surface phases has been developed to simulate emissions conversion performance. It is applied to both a fresh catalyst and one that has been aged through exposure to the exhaust system of a Heavy Duty Diesel engine performing in the field for 376K miles. Details of the chemical kinetics associated with the various NOx reduction reactions in the two Fe-Zeolite configurations have been examined and correlated with data from a synthetic gas rig test bench. It was found that the Standard reaction, (4NH₃ + 4NO + O₂ → 2N₂ + 6H₂O), which is one of the main reactions for NOx reduction, degraded significantly at the lower temperatures for the aged system. Meanwhile the Fast reaction, (4NH₃ + 2NO + 2NO₂ → 4N₂+ 6H₂O), was the least affected and as such became the dominant mechanism for obtaining compliant NOx reduction levels towards the end of the product’s rated life.