Method for purifying exhaust gases
AssigneesToyota Jidosha Kabushiki Kaisha, Kabushiki Kaisha Toyota Chuo Kenkyusho, Cataler Industrial Co., Ltd., Tosoh Corporation
InventorsKazunobu Ishibashi, Shinichi Matsumoto, Shiroh Kondoh, Yasuhide Utsumi
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Abstract
A method for the catalytic purification of an oxygen-rich exhaust gas, wherein the catalyst comprises: a catalyst support, a zeolyte layer formed on the catalyst support and noble metals such as platinum, palladium and rhodium loaded on the catalyst. The catalyst for purifying the exhaust gas maintains a superior exhaust gas conversion performance over a long period of time.
Claims19
A process for purifying an oxygen rich exhaust gas from an internal combustion engine operating at an air fuel ratio of 18 or more comprising the steps of:
- providing a catalyst consisting essentially of:
- a catalyst support;
- a layer formed on said catalyst support and including zeolite wherein said zeolite is a zeolite selected from the group consisting of analcimes, sodalites, zeolite A, natrolites, mordenites, heulandites, ZSM-5, and a mixture thereof;
- and
- platinum loaded on said layer by 1.3 parts by weight or more with respect to 100 parts of weight of said layer;
- a second step of contacting said catalyst with said oxygen rich exhaust gases containing nitrogen oxides, thereby reducing by catalytic reduction said nitrogen oxides;
- wherein said second step is conducted at a temperature of 120.degree.-450.degree. C.
A process for purifying an oxygen rich exhaust gas from an internal combustion engine operating at an air fuel ratio of 18 or more comprising the steps of:
- providing a catalyst consisting essentially of:
- a catalyst support;
- a layer formed on said catalyst support and including zeolite wherein said zeolite is a zeolite selected from the group consisting of analcimes, sodalites, zeolite A, natrolites, mordenites, heulandites, ZSM-5, and a mixture thereof;
- and
- palladium loaded on said layer by 0.8 parts by weight or more with respect to 100 parts of weight of said layer;
- a second step of contacting said catalyst with said oxygen rich exhaust gases containing nitrogen oxides, thereby reducing by catalytic reduction said nitrogen oxides;
- wherein said second step is conducted at a temperature of 120.degree.-450.degree. C.
A process for purifying an oxygen rich exhaust gas from an internal combustion engine operating at an air fuel ratio of 18 or more comprising the steps of:
- providing a catalyst consisting essentially of:
- a catalyst support;
- a layer formed on said catalyst support and including zeolite wherein said zeolite is a zeolite selected from the group consisting of analcimes, sodalites, zeolite A, natrolites, mordenites, heulandites, ZSM-5, and a mixture thereof;
- and
- rhodium loaded on said layer by 0.7 parts by weight or more with respect to 100 parts of weight of said layer;
- a second step of contacting said catalyst with said oxygen rich exhaust gases containing nitrogen oxides, thereby reducing by catalytic reduction said nitrogen oxides;
- wherein said second step is conducted at a temperature of 120.degree.-450.degree. C.
A process for purifying an oxygen rich exhaust gas from an internal combustion engine operating at an air fuel ratio of 18 or more comprising the steps of:
- providing a catalyst consisting essentially of:
- a catalyst support;
- a layer formed on said catalyst support and including zeolite wherein said zeolite is a zeolite selected from the group consisting of analcimes, sodalites, zeolite A, natrolites, mordenites, heulandites, ZSM-5, and a mixture thereof;
- and
- at least one noble metal loaded on said layer and selected from the group consisting of platinum, palladium, and rhodium wherein said platinum, said palladium and said rhodium are loaded on said layer by 1.3 parts by weight or more, by 0.8 parts by weight or more, and by 0.7 parts by weight or more with respect to 100 parts of weight of said layer respectively;
- a second step of contacting said catalyst with said oxygen rich exhaust gases containing nitrogen oxides, thereby reducing by catalytic reduction said nitrogen oxides;
- wherein said second step is conducted at a temperature of 120.degree.-450.degree. C.
Dependencies are inferred from the claim text.