ENGINE EMISSIONS NOX REDUCTION

摘要

An engine assembly of the type that includes a conduit (16) extending from the exhaust manifold outlet (14) to the atmosphere (20), an ammonia injection station (22) along the conduit, and a catalytic assembly (24) lying along the conduit and downstream of the ammonia injection station. The catalytic assembly includes a surface wash coat (50) of a nitric-oxide catalyzing material that converts nitric oxide (NO) to nitrogen dioxide (N02), and passages coated with SCR (selective catalyst reduction) catalyst that reacts ammonia with N02 to produce nitrogen and water. The catalytic assembly includes multipie elements such as fibers, coated with the SCR catalyzing material, with the elements lying in a mass and with passages, or pores lying between the elements. The mass lies in a casing (90) of the conduit, and has conical inside and outside surfaces (40, 42) to provide a large area through which gasses flow. A catalyst arrangement 80 such as the honeycomb type with an oxidizing catalyst on the passage walls, can also lie in the casing (90) of the catalytic assembly, but preferably downstream of the nitric oxide and SCR catalysts.