A catalytic NOx reduction system using periodic steps, lean and rich operations

Catalytic lean NO reduction system in periodic two steps, lean/rich operations has been investigated over Rh-based catalysts. The investigation was done using a pulse reaction. In the reaction, after H2 or CO was pulse-injected for a moment to achieve reducing conditions, the highly dispersed Rh catalyst could catalyze NO reduction at 200 400 °C in lean conditions for 1 min. Furthermore, NO was effectively reduced over the highly dispersed Rh/-zeolite after exposure to the gas composed of 3% of O2, 40 ppm of SO2 and balance of He at 300 and 400 °C for 24 h.