Exhaust emission control catalyst
AssigneeToyota Jidosha Kabushiki Kaisha
InventorYoshihide Segawa
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Abstract
An exhaust emission control catalyst disclosed herein is equipped with a rhodium catalytic layer and a platinum catalytic layer, and is characterized in that a relationship between a mole average (X) of a Pauling's electronegativity that is calculated as to elements included in the rhodium catalytic layer except platinum group elements and oxygen and a mole average (Y) of a Pauling's electronegativity that is calculated as to elements included in the platinum catalytic layer except platinum group elements and oxygen is 1.30≦X≦1.45 and 1.47≦Y≦2.0. According to this exhaust emission control catalyst, an interlayer transfer of platinum and/or rhodium and the alloying of platinum and/or rhodium are suppressed during use of the catalyst, and high exhaust gas purification performance can be exerted.
Claims10
An exhaust emission control catalyst comprising:
- a substrate;
- and
- a catalytic layer that is formed on a surface of the substrate, wherein
- the catalytic layer comprises a rhodium catalytic layer, which includes a first carrier and rhodium supported on the first carrier, and a platinum catalytic layer, which includes a second carrier and platinum supported on the second carrier,
- the first carrier in the rhodium catalytic layer includes CeO2, ZrO2 and Al2O3 and
- a relationship between a mole average (X) of a Pauling's electronegativity that is calculated as to elements included in the rhodium catalytic layer except platinum group elements and oxygen and a mole average (Y) of a Pauling's electronegativity that is calculated as to elements included in the platinum catalytic layer except platinum group elements and oxygen is
- 1.30≦X≦1.45 and 1.47≦Y≦2.0.
Dependencies are inferred from the claim text.