NO Oxidation and NO2 Decomposition

Inlet feed 500 ppm NO, 5 % O2, 0 or 2 or 5 % H2O. Total flow 1,000 seem, Balance gas Ar. b Steady-state conversion of NO2 versus catalyst temperature during its decomposition. Feed  

Space velocity 57,000 Balance gas Ar. (Adapted from Metkar et al. [42] and used with permission.) 

The selective catalytic reduction of NOx by ammonia on Fe-zeolite catalysts displays interesting performance trends over a range of temperatures and NO/NO2 feed ratios. Feeds containing various NOa/NOx inlet ratios (0-1) provide insight into the effect of NO2 which can be appreciable on Fe-exchanged catalysts. 

The features of the standard SCR reaction (Rl) system (feed devoid of NO2) are first highlighted. A typical temperature sweep experiment (Fig. 11.4a) shows the changes in the effluent concentrations as a function of temperature when a dry feed containing equal concentrations of NO and NH3 (NO = NH3 = 500 ppm) in excess O2 was passed over an Fe-ZSM-5 catalyst. Negligible NO conversions ( 20 %) were observed up to 250 °C. At a temperature of about 300 °C there is a nonlinear increase in NO conversion, which approaches 91 % at 450 °C. The NH3 

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