Development of a Lean-NOx Catalyst Containing Metal-Ligand Complex Impregnated Molecular Sieves 962050

This paper describes the development and evaluation of an operative catalyst for the reduction of NO_x in lean exhaust. A catalyst that incorporates iron (II)-complex impregnated modified mesoporous molecular sieves (MCM-41) has been synthesized and further treated with [pd(NH₃)₄]Cl₂ [1]. Experimental results suggest a hydrocarbon-independent reduction of NO_x takes place on the iron center, and oxidation of CO is assisted by the palladium ion. The catalytic activity toward HC CO, and NO_x removal was studied with simulated and real engine exhaust in the laboratory and on an engine, respectively. Engine test results demonstrate a reduction of NO_x of up to 10 percent at catalyst inlet temperatures in the range of 260°C to 280°C. In this paper, possible NO_x reduction pathways are also discussed.