| 摘要 |
PURPOSE:To produce a catalyst for purification of exhaust gas from an internal- combustion engine having high purifying performance even under severe conditions in a hot atmosphere while using a small amt. of an oxide. CONSTITUTION:A catalyst layer consisting of a composite obtd. by supporting cerium oxide or the oxide of Ce and one or more among Zr, Nd, La and Al on inorg. fine powder of alumina, etc., having a large specific surface area of 100-300m<2>/g and alumina powder stabilized with a rare earth element contg. one or more kinds of elements of the platinum group selected among Pt, Rh, Pd, Ru and Ir is formed on a honeycomb carrier. At this time, the inorg. fine powder is fluidized, an aq. soln. of a metallic salt such as cerium nitrate is blown into the powder by a smaller amt. than the amt. of water absorbed in the powder and the powder is dried or fired. These processes are repeated until the amt. of the supported metal (expressed in terms of oxide) becomes 30-50wt.% of the amt. of the resulting composite and then firing is carried out at >=600 deg.C. |
