The Use of NOx Adsorber Catalysts on Diesel Engines

NOx adsorber catalysts (NACs) can be applied in lean-burn gasoline and diesel engines to reduce NOx emissions. Typically NACs are formulated using platinum as an oxidation catalyst, barium as a storage component and rhodium for NOx reduction. There has been intense research to optimise these catalysts for use on diesel engines aimed at increasing their efficiency, durability, sulfur tolerance and operating temperature window. This paper describes these developments and outlines the current level of knowledge of NOx adsorber catalyst systems using results from small-scale laboratory tests as well as engine-bench work.