A kinetic model of NH3-SCR catalytic reaction over Fe-zeolite catalyst was established to predict the NOx reduction performance of the catalyst and to investigate the axial species distribution during SCR reaction.The model is composed of NH3 adsorption and desorption,NH3 oxidation,NO oxidation,NOx reduction and N2O formation reactions.The results show that the model can predict the variation of species concentration in axial space.It was found that the Fe-zeolite catalyst is sensitive to molar ratio of n(NO2)/n(NOx),and the optimal n(NO2)/n(NOx)is 0.5.Because of the NH3 inhibition effect,the SCR activity is low at the temperature lower than 300℃,while high at the temperature above 400℃.In addition,the SCR reaction of Fe-zeolite occurs mainly in the inlet and middle segments of the catalyst.At the temperature of 300℃and the space velocity of 60000 h-1,up to 90% NOx conversion could be achieved in the front half of the catalyst.The utilization rate of the catalyst is low at the outlet segment of the catalyst.Furthermore,the transient performance of the model was investigated,and it is found that the transient response of Fe-zeolite catalyst was improved with the temperature increasing.
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