Filter medium for treating an exhaust gas.

摘要

A filter medium for treating exhaust gases which is placed in a passage of an exhaust gas to eliminate impurity gases by contact with the medium, which comprises a porous ceramic substrate, a pre-coat layer of a reaction aid and a layer of a solid material formed on one side of the substrate from which the exhaust gas is charged through the substrate, and a catalyst layer for eliminating nitrogen oxides formed on the other side of the substrate from which the exhaust gas is discharge. The filter medium may have a double-cylinder construction, in which the catalyst layer is formed on at least one side of a inner cylinder and the pre-coat layer and the solid material layer are formed on an outer side of an outer cylinder.