Ultra low dosage of platinum and cerium fuel additives in diesel particulate control

The effect of a platinum metal additive on the performance of three commonl y used base-metal fuel additives for the catalytic oxidation of diesel part iculate was studied. Engine experiments using Coming EX80 filters and oxida tion experiments in flow-reactor equipment showed that especially a combina tion of platinum and cerium additives is very active in the catalytic oxida tion of diesel particulates. The additive dose rate can be very low, i.e., about 5 ppm cerium and 0.25 ppm platinum, without loss of effectiveness. NO 2 plays a key role in this process. Platinum accumulated on the filter cata lyses the oxidation of NO to NO2, whereas cerium catalyses the oxidation of particulate with NO2. Copper and it in do not catalyse the latter reaction . An additional effect of this oxidation mechanism is a substantial NO2 red uction.