Kinetic studies of selective catalytic reduction of nitric oxide by propylene on Pt/MCM-41 catalyst

Reaction kinetics for selective catalytic reduction (SCR) of nitric oxide ( NO) over 1% Pt/MCM-41 catalyst has been investigated at temperatures rangin g 150-500 degreesC under steady and transient state conditions. The reducti on of NO is found to be promoted by a small amount of oxygen when the conce ntration of oxygen is less than that of the critical oxygen concentration r equired for stoichiometric oxidation of C3H6. Above the critical oxygen con centration, an optimal reaction temperature for optimal NO conversion is ob served and the optimal NO conversion decreases with the increase of oxygen concentration. Two distinct kinetic regions are observed: one at the reacti on temperature below and the other one above that required for optimal NO c onversion. The NO reduction rate is suggested to be controlled by the activ ation rate of C3H6 at low temperatures and by the external diffusion rate o f reactants at high temperatures. (C) 2001 Elsevier Science B.V. All rights reserved.