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Oxygen storage components (OSC) based on cerium (Ce) were investigated for their ability to reduce the oxidation temperature of diesel particulate matter (DPM). Among the materials investigated, a cerium-praseodymium (Ce-Pr) composite oxide provided the largest reduction in DPM oxidation temperature. Oxygen isotope tracer experiments revealed that oxygen released from the cerium oxidized the DPM at a lower temperature than the oxygen from the exhaust.

A study was performed on a lean NOx trap in which the loading of a ceria-containing mixed oxide in the washcoat was varied. After a mild stabilization of the traps, the time required to purge the NOx trap generally increased with increasing amount of mixed oxide. The purge NOx release also increased with increasing mixed oxide level but was greatly diminished after thermal aging. The sulfur tolerance of the NOx trap improved as the mixed oxide content was increased from 0% to 37%. The sample with 0% mixed oxide was more difficult to desulfate than the other samples due to poor water-gas-shift capability. After thermal aging, the NOx reduction efficiency on a 60 second lean/5 second rich cycle was highest for the samples with 0% to 37% mixed oxide at evaluation temperatures of 400°C to 500°C.