Exhaust gas purifying system and catalyst

a technology of exhaust gas purification system and catalyst, which is applied in the direction of physical/chemical process catalyst, metal/metal-oxide/metal-hydroxide catalyst, and separation process, etc. it can solve the problem that the catalytic activity (for oxidation) of platinum and rhodium cannot be sufficiently demonstrated, and the catalyst cannot reduce nox
US20010004832A1Inactive Publication Date: 2001-06-28NISSAN MOTOR CO LTD
0 Cites 27 Cited by

Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
NISSAN MOTOR CO LTD
Publication Date
2001-06-28
Estimated Expiration
Not applicable · inactive patent

Smart Images

  • Figure 1
    Figure 1
Patent Text Reader

Abstract

An exhaust gas purifying system for an automotive internal combustion engine which discharges oxygen-excessive exhaust gas under lean-burn operation. The exhaust gas purifying system comprises a NOx reducing catalyst for reducing NOx in the presence of at least hydrogen serving as reducing agent. The NOx reducing catalyst is disposed in an exhaust gas passageway of the engine. The NOx reducing catalyst includes a porous substrate, and platinum and cesium carried on the porous substrate. A catalyst is disposed in the exhaust gas passageway in order to produce hydrogen so as to enrich the oxygen-excessive exhaust gas with hydrogen before the oxygen-excessive exhaust gas reaches the NOx reducing catalyst. The oxygen-excessive exhaust gas enriched with hydrogen is introduced through the exhaust gas passageway to the NOx reducing catalyst. Here, the oxygen-excessive exhaust gas enriched with hydrogen is brought into contact with the NOx reducing catalyst under a condition in which temperature of at least one of the NOx reducing catalyst and the oxygen-excessive exhaust gas enriched with hydrogen is within a range of from 250 to 600° C.
Need to check novelty before this filing date? Find Prior Art

Description

BACKGROUND OP THE INVENTION

[0001] This invention relates to improvements in an exhaust gas purifying system for purifying exhaust gas discharged from an internal combustion engine, a furnace, a burner or the like, and more particularly to the exhaust gas purifying system for effectively reducing nitrogen oxides (NOx) in oxygen-excessive exhaust gas discharged from the engine under lean-burn operation.

[0002] Hitherto three-way catalysts for simultaneously oxidizing carbon monoxide (CO) and hydrocarbons (HC) and reducing nitrogen oxides (NOx) have been extensively used as exhaust gas purifying catalysts installed to internal combustion engines of automotive vehicles and the like, However, such catalysts cannot reduce NOx particularly when exhaust gas of the engine is oxygen-excessive (i.e., has an air-fuel ratio leaner than stoichiometric value). In this regard, Japanese Patent No. 2600492 discloses a so-called rich spike process as a method of reducing NOx when exhaust gas of the eng...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More