摘要:
An exhaust gas purifying catalyst includes a substrate (1) that defines an exhaust gas passage; a lower catalyst layer (2) formed over the substrate, and an upper catalyst layer (3) formed over the lower catalyst layer (2). The lower catalyst layer (2) has a lower catalytic precious metal that contains at least one of Pt and Pd, and a lower-layer carrier that supports the lower catalytic precious metal. The upper catalyst layer (3) has an upper catalytic precious metal that contains Rh, and an upper-layer carrier that supports the upper catalytic precious metal. The upper-layer carrier includes an inorganic mixed oxide that contains Ce, Zr, Al, Nd, and at least one element selected from the group consisting of rare earth elements other than Ce and alkaline earth elements. The Nd is unevenly distributed in covering layers that covers surfaces of interior regions within the inorganic mixed oxide.
摘要:
An exhaust gas purifying catalyst includes a substrate (1) that defines an exhaust gas passage; a lower catalyst layer (2) formed over the substrate, and an upper catalyst layer (3) formed over the lower catalyst layer (2). The lower catalyst layer (2) has a lower catalytic precious metal that contains at least one of Pt and Pd, and a lower-layer carrier that supports the lower catalytic precious metal. The upper catalyst layer (3) has an upper catalytic precious metal that contains Rh, and an upper-layer carrier that supports the upper catalytic precious metal. The upper-layer carrier comprises an inorganic mixed oxide that contains Ce, Zr, Al, Nd, and at least one element selected from the group consisting of rare earth elements other than Ce. The inorganic mixed oxide has interior regions containing a mixed aggregate composed of first particles comprising Ce and Zr in a form of a composite oxide, and second particles comprising Al in a form of alumina, and has cover layers containing Nd that cover surfaces of the respective interior regions. The Nd is unevenly present in the cover layers or the Nd is concentrated in the cover layers.
摘要:
A catalyst for purifying exhaust gases includes a substrate, and a catalytic layer. The catalytic layer includes a lower catalytic layer, a first upper catalytic layer, and a second upper catalytic layer. The lower catalytic layer being loaded with Pd and/or Pt is formed on the substrate. The first upper catalytic layer being loaded with Pd covers an upstream side of the lower catalytic layer, and exhibits a concentration of loaded Pd that falls in a range of from 4.5 to 12% by mass when the entirety of the first upper catalytic layer is taken as 100% by mass. The second upper catalytic layer being loaded with Rh covers a downstream side of the lower catalytic layer.
摘要:
The combustion air-fuel ratio is made leaner than the stoichiometric air-fuel ratio at the time of engine startup and the combustion air-fuel ratio is made richer than the stoichiometric air-fuel ratio and the exhaust downstream part of the three-way catalyst apparatus is raised in temperature when it is judged that just the exhaust upstream part of the three-way catalyst apparatus arranged in the engine exhaust system has been raised to the catalyst activation temperature.
摘要:
The exhaust gas purification catalyst device has catalyst coating layers 10, 20, which extend from the upstream side to the downstream side of the exhaust gas flow. The catalyst coating layers 10, 20 each have at least three zones present in order from the upstream side to the downstream side of the exhaust gas flow, and each of these at least three zones is an oxidation catalyst zone 1, 3, 5 or a reduction catalyst zone 2, 4, 6. In the uppermost layer of an oxidation catalyst zone, the total number of atoms of platinum and palladium is greater than the number of atoms of rhodium; in the upper most layer of a reduction catalyst zone, the number of atoms of rhodium is greater than the total number of atoms of platinum and palladium. The oxidation catalyst zones 1, 3, 5 and the reduction catalyst zones 2, 4, 6 alternate at least twice in the exhaust gas flow direction.
摘要:
An exhaust gas purification catalyst device 10 which comprises: a lower layer 1 which contains metal oxide particles MO, and Pd and Pt supported by the metal oxide particles MO; and an upper layer 2 which contains zirconia-containing metal oxide particles ZrO, and Rh supported by the zirconia-containing metal oxide particles ZrO. This exhaust gas purification catalyst device 10 is configured such that: the lower layer 1 comprises a lower layer first stage part If that is on the exhaust gas upstream side, and a lower layer second stage part 1r that is on the exhaust gas downstream side; the lower layer first stage part 1f contains 1.8 g/L or more of Pd and 0.05 g/L or more of Pt; the lower layer second stage part 1r contains 0.10 g/L or more of Pd, while containing no Pt or 0.10 g/L or less of Pt; the amount of the zirconia-containing metal oxide particles ZrO in the upper layer 2 is from 60 g/L to 140 g/L (inclusive); and the amount of Ce in the upper layer 2 in terms of CeO 2 is 7g/L or less.