NOx selective catalytic reduction over supported metallic catalysts

In this work we present the results obtained with 3 catalysts (Pt, Rh and Ag on alumina) tested in ranges of temperatures and gas hourly space velocities typical of diesel engines in real trucks. NO concentration was 500 ppm, C3H6 ranged between 500 and 2000 ppm, while oxygen was always 5%. All the catalysts were active and showed high conversions. Both Pt and Rh were active at low temperature (T50 = 200–250 °C) but had quite high selectivity towards NO2. Silver was active at higher temperature, but showed very high selectivity towards N2. A strong boosting effect on NO conversion was recorded if H2 was added to the gas mixture.