Supported bismuth oxide catalysts for the selective reduction of NO with propene in lean conditions

Bi2O3/Al2O3 materials were prepared by impregnation of a γ-Al2O3 support with bismuth citrate and tested as catalysts for the selective catalytic reduction of NO with propene. Under simulated diesel exhaust gas conditions (500 ppm NO, 10% O2, 6% H2O) with 600 ppm propene as reductant, a maximum in NO conversion of 56% was attained at 525 °C and a GHSV of ca. 30,000 h−1. Water significantly inhibited NO reduction by competing for adsorption sites with the propene and/or NO reactants. To correlate NO reduction activity with catalyst composition, the catalysts were characterized using XRD, XPS and N2 physisorption methods.