Kinetic modeling of NOxNOx storage and reduction with different reducing agents (CO, H2, and C2 H4) on a Pt–Ba/γγ-Al2O3 catalyst in the presence of CO2 and H2O

In this paper a global reaction kinetic model is used to understand and describe the NOxNOx storage/reduction process in the presence of CO2 and H2O. Experiments have been performed in a packed bed reactor with a Pt–Ba/γγ-Al2O3 powder catalyst (1 wt% Pt and 30 wt% Ba) with different lean/rich cycle timings at different temperatures (200, 250, and 300∘C) and using different reductants (H2, CO, and C2H4). Model simulations and experimental results are compared. H2O inhibits the NO oxidation capability of the catalyst and no NO2 formation is observed. The rate of NO storage increases with temperature. The reduction of stored NO with H2 is complete for all investigated temperatures. At temperatures above 250∘C, the water gas shift (WGS) reaction takes place and H2 acts as reductant instead of CO. At 200∘C, CO and C2H4 are not able to completely regenerate the catalyst. At the higher temperatures, C2H4 is capable of reducing all the stored NO, although C2H4 poisons the Pt sites by carbon decomposition at 250∘C. The model adequately describes the NO breakthrough profile during 100 min lean exposure as well as the subsequent release and reduction of the stored NO. Further, the model is capable of simulating transient reactor experiments with 240 s lean and 60 s rich cycle timings.