Reduction of NO with Carbonaceous Particulate-Like Materials over Pd or Pt Catalysts Supported on Metal Oxides

NO x and particulate material in diesel exhaust causes a major environmental problem. To remove these compounds simultaneously, catalytic reduction of NO with carbon particulate material to form N 2 and CO 2 was investigated. The catalyst system consisting of Pd, Al 2 O 3 support, and activated carbon (AC) reductant was found to be the most active. The catalytic activity was little affected by SO 2 impurity (SO 3 /NO = 0.1%/0.2%) under the conditions employed. In the presence of O 2 (O 2 /NO = 0.11%/0.15%), however, the N 2 yield was a little less than that without O 2 . During reaction with O 2 , the presence of surface NO 2 species such as bridging and chelating nitrates, and free nitrate was assumed by in situ DRIFT-IR spectra. The catalytic activity was found to increase by addition of K to the catalyst system.