Filter catalyst for exhaust gas purification of a diesel engine and its method of production

Abstract

The present invention has as its object the improvement of the efficiency of purification of the hydrocarbons, carbon monoxide, and nitrogen oxides, in particular, particulate matter PM, contained in the exhaust gas of diesel engines; further, the filter catalyst for exhaust gas purification of a diesel engine having a filter structure carrying a precious metal of, the present invention is comprised of a filter structure having-an upstream portion at the side where the exhaust gas flows in, a downstream portion at the side where the exhaust gas flows out, and a midstream portion positioned between the upstream portion and downstream portion, carrying the precious metal at the upstream portion at the side where the exhaust gas flows in at a high concentration, and carrying it at the downstream portion at a low concentration; and the method of production of the present invention has, in particular, a step of immersing the filter structure from the end face of the upstream portion to the downstream portion in a solution of the precious metal and a step of immersing only the upstream portion in a solution of the precious metal.

Dependencies are inferred from the claim text.