Cataler Corporation

Daihatsu Motor Company, Ltd.

Hokko Chemical Industry Co., Ltd.

Noboru Sato

Hirohisa Tanaka

Hiromasa Suzuki

Kenichi Taki

Keiichi Narita

Isao Tan

Mari Uenishi

Masashi Taniguchi

Nobuhiko Kajita

Yasunori Sato

Mareo Kimura

Sho Hoshino

Kimiyoshi Kaneko

Keisuke Murawaki

Tomohito Mizukami

Senshu Mitachi

An exhaust gas purification underfloor catalyst characterized in having a catalyst layer having a lower layer and an upper layer, the lower layer containing alumina and CeO, the noble metal content of the lower layer being at most 0.5 mass % in relation to the mass of the lower layer, the upper layer containing Rh, alumina, and CeO, the amount of noble metals other than Rh contained being 1 mol % or less in relation to the total amount of noble metals contained in the upper layer, the total amount of CeOcontained in the lower layer and the upper layer being 14 g/L to 30 g/L, the amount of CeOcontained in the upper layer being 7 g/L to 25 g/L, and the amount of CeOcontained in the lower layer being 20% or more of the amount of CeOcontained in the upper layer.

Exhaust gas purification underfloor catalyst and catalyst system

The invention provides an exhaust gas purification catalyst comprising one or more catalyst coating layers having platinum and/or palladium with rhodium supported on a carrier, characterized in that the (platinum and/or palladium)/rhodium weight ratio is 1.0 or less.

Exhaust gas purification catalyst

To provide a method for industrially efficiently producing an exhaust gas purifying catalyst containing a perovskite-type composite oxide which is stable and has a less reduced specific surface area and is also effectively prevented from decreasing in its catalytic performance even in endurance in high temperature oxidative reducing atmospheres, a pre-crystallization composition containing elementary components constituting a perovskite-type composite oxide containing a noble metal is prepared, is mixed with a powder of theta-alumina and/or alpha-alumina to prepare a mixture, and the mixture is heat treated. Thus, the resulting perovskite-type composite oxide supported by the powder of theta-alumina and/or alpha-alumina can keep its thermostability at a sufficient level thereby to effectively prevent the catalytic performance from decreasing. This method can industrially efficiently produce the exhaust gas purifying catalyst.

Method for producing exhaust gas purifying catalyst

To provide a perovskite-type composite oxide which has stable quality in which a solid solution of Pd is formed at a high rate, a method for producing the perovskite-type composite oxide, and a catalyst composition containing the perovskite-type composite oxide, the perovskite-type composite oxide is produced by formulating materials in accordance with each atomic ratio of a perovskite-type composite oxide represented by the following general formula (1):ABPdO&#x2003;&#x2003;(1)wherein A represents at least one element selected from rare earth elements and alkaline earth metals; B represents at least one element selected from transition elements (excluding rare earth elements, and Pd), Al and Si; x represents an atomic ratio satisfying the following condition: 1&#x3c;x; y represents an atomic ratio satisfying the following condition: 0&#x3c;y&#x2266;0.5; and &#x3b4; represents an oxygen excess.

Perovskite-type composite oxide, catalyst composition and method for producing perovskite-type composite oxide

To provide an exhaust gas purifying catalyst which can maintain the catalytic activity at a high level over a long time and can achieve satisfactory emission control performance, an exhaust gas purifying catalyst is prepared so as to contain a noble metal, a perovskite-type composite oxide represented by the following general formula (3), and theta-alumina and/or alpha-alumina:ABNO&#x2003;&#x2003;(3)wherein A represents at least one element selected from rare-earth elements and alkaline earth metals; B represents at least one element selected from Al and transition elements excluding rare-earth elements and noble metals; N represents a noble metal; and m represents an atomic ratio of N satisfying the following relation: 0&#x3c;m&#x3c;0.5.

Catalyst for clarifying exhaust gas

Growing community of inventors

Shizuoka, Japan

Noboru Sato