초록 ▼

An exhaust gas containing nitrogen oxides and particulate matter is cleaned by using an exhaust gas cleaner including a heat-resistant, porous filter; a porous ceramic powder layer formed on the filter; and a catalyst supported by the ceramic powder layer, the catalyst consisting essentially of (a)

An exhaust gas containing nitrogen oxides and particulate matter is cleaned by using an exhaust gas cleaner including a heat-resistant, porous filter; a porous ceramic powder layer formed on the filter; and a catalyst supported by the ceramic powder layer, the catalyst consisting essentially of (a) at least one of alkali metal elements, (b) cobalt and/or manganese, (c) vanadium, and (d) at least one of rare earth elements, whereby the nitrogen oxides are reduced by the particulate matter in the exhaust gas serving as a reducing agent.

대표청구항 ▼

1. An exhaust gas cleaner comprising a heat-resistant, porous filter, a porous ceramic powder layer formed on said filter in an amount of 3-15 parts by weight per 100 parts by weight of said filter, and a catalyst in an amount of 1-40 weight % based on the ceramic powder layer and supported by said

1. An exhaust gas cleaner comprising a heat-resistant, porous filter, a porous ceramic powder layer formed on said filter in an amount of 3-15 parts by weight per 100 parts by weight of said filter, and a catalyst in an amount of 1-40 weight % based on the ceramic powder layer and supported by said ceramic powder layer, said catalyst consisting essentially of: (a) at least one element selected from the group consisting of K and Cs in an amount of 10-50 weight % based on the total weight of the catalyst on a metal basis; (b) at least one element selected from the group consisting of Co and Mn in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis; (c) V in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis, the total amount of components (b) and (c) being 30-80 weight %; and (d) at least one element selected from the group consisting of Ce and La in an amount of 10-50 weight % based on the total weight of the catalyst on a metal basis. 2. The exhaust gas cleaner according to claim 1, wherein said ceramic powder layer is made of TiO 2 . 3. An exhaust gas cleaner comprising a heat-resistant, porous filter, a first catalyst supported by a ceramic powder carrier formed on said filter in the inlet region of said filter, and a second catalyst supported by a ceramic powder carrier formed on said filter in the outlet region, said first catalyst consisting essentially of: (a) at least one element selected from the group consisting of K and Cs in an amount of 10-50 weight % based on the total weight of the catalyst on a metal basis; (b) at least one element selected from the group consisting of Cu, Co, Mn and Mo in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis; (c) V in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis; and (d) at least one element selected from the group consisting of Ce and La in an amount of 10-50 weight % based on the total weight of the catalyst on a metal basis, said first catalyst being 0.05-6 weight % based on the ceramic powder layer on a metal basis; and said second catalyst consisting essentially of at least one platinum-group element in an amount of 0.1-1 weight % based on the ceramic powder layer on a metal basis. 4. An exhaust gas cleaner comprising a heat-resistant, porous filter, and a catalytic layer formed on said filter, said catalytic layer comprising a uniform mixture of a catalyst and a ceramic powder carrier, said catalyst consisting essentially of: (a) at least one element selected from the group consisting of K and Cs in an amount of 10-50 weight % based on the total weight of the catalyst on a metal basis; (b) at least one element selected from the group consisting of Co and Mn in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis; (c) V in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis, the total amount of components (b) and (c) being 30-80 weight %; and (d) at least one element selected from the group consisting of Ce and La in an amount of 15-65 weight % based on the total weight of the catalyst on a metal basis, said catalyst being 1-20 parts by weight and said ceramic powder carrier being 1-10 parts by weight per 100 parts by weight of said filter. 5. The exhaust gas cleaner according to claim 4, wherein said ceramic powder carrier is made of TiO 2 . 6. The exhaust gas cleaner according to claim 3, wherein said second catalyst further contains Au and/or Ag. 7. The exhaust gas cleaner according to claim 3, wherein said two catalysts are supported by a ceramic carrier powder layer formed on said filter. 8. The exhaust gas cleaner according to claim 6, wherein said two catalysts are supported by a ceramic carrier powder layer formed on said filter.