Transient ammonia pulse experiments

PEP experiments are performed using either NHs or [ 0]-02 to obtain further insight in the reaction mechanism and deactivation behaviour. Transient ammonia pulse experiments are performed to study the adsorption and dissociation of ammonia on pure platinum catalysts, followed by the focus on the deactivation of platinum. Finally, we will briefly discuss the influence of the alumina support. 

Fig. 38. Transient SCR microreactor experiments with high frequency NH3 feed pulses (l,000ppm) in flowing NO (l,000ppm) + 02 (2% v/v) and H20 (1% v/v) + He at 180°C, with pulse frequency 5min on/5min off. Symbols outlet concentration of ammonia (circles), NO (squares) and N2 (triangles)—Dotted lines feed ammonia concentration. Solid lines (A) simulation using the MR rate law, (B) simulation using the ER rate law.

The parameter estimates provided by the fit based on MR kinetics were also used to simulate the experiments of Fig. 10.6 pulsed ammonia steps (1,000 ppm) were fed at 200 °C while feeding 1,000 ppm of NO, 2 % O2, 1 % H2O in He with a GHSV of 92,000 h . Two mns were performed with different pulse frequency. Notably, these were particularly demanding conditions with respect to the ammonia inhibition effect. The simulation results are also displayed in Fig. 10.6 (solid fines) it clearly appears that, on a purely predictive basis, the MR rate expression was able to follow the fast transients of these experiments. 

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