Exhaust gas purification device for an engine
First Claim
1. An exhaust gas purification device for an internal combustion engine comprising:
- a ratio determining means disposed in an exhaust gas passage of an internal combustion engine for converting substantially all of NOx in the exhaust gas into N2, NH3 and NOx, wherein an amount of NH3 and an amount of NOx generated by the conversion are adjusted so that the amount of NH3 and the amount of NOx are stoichiometrical, and wherein the NOx generated by the conversion is essentially NO2 and a molar ratio of the amount of NO2 generated to the amount of NH3 generated is 3;
4; and
purification means disposed in the exhaust gas passage downstream of the ratio determining means for causing the NH3 generated to react with NOx generated to produce N2 and H2 O components.
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Abstract
In the present invention, the exhaust gas from the engine is divided into a first and a second branch exhaust passages after it passes through a three-way reducing and oxidizing catalyst, and the two branch exhaust passages merge into an exhaust gas outlet passage. In the first branch exhaust passage, an oxidizing catalyst is disposed, and in the exhaust gas outlet passage, a denitrating and oxidizing catalyst is disposed. NOx in the exhaust gas from the engine is all converted to N2 and NH3 by the three-way reducing and oxidizing catalyst and a part of the NH3 generated by the three-way catalyst flows into the first branch exhaust passage and is converted to NOx again by the oxidizing catalyst. The amount of NOx produced by the oxidizing catalyst and the amount of NOx flowing through the second branch exhaust passage is determined by the flow distribution ratio of the first and the second branch exhaust passages. In this invention, the flow ratio is determined in such a manner that the amount of the NOx produced by the oxidizing catalyst and the amount of the NH3 passing through the second branch exhaust passage are stoichiometric to produce N2 and H2 O. Therefore, when these exhaust gases flow into the denitrating and oxidizing catalyst after they mix with each other in the exhaust gas outlet passage, all the NOx and the NH3 are converted to N2 and H2 O by the denitrating and oxidizing catalyst without producing any surplus NOx or NH3.
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Citations
27 Claims
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1. An exhaust gas purification device for an internal combustion engine comprising:
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a ratio determining means disposed in an exhaust gas passage of an internal combustion engine for converting substantially all of NOx in the exhaust gas into N2, NH3 and NOx, wherein an amount of NH3 and an amount of NOx generated by the conversion are adjusted so that the amount of NH3 and the amount of NOx are stoichiometrical, and wherein the NOx generated by the conversion is essentially NO2 and a molar ratio of the amount of NO2 generated to the amount of NH3 generated is 3;
4; andpurification means disposed in the exhaust gas passage downstream of the ratio determining means for causing the NH3 generated to react with NOx generated to produce N2 and H2 O components. - View Dependent Claims (22)
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2. An exhaust gas purification device for an internal combustion engine comprising:
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a ratio determining means disposed in an exhaust gas passage of an internal combustion engine for converting substantially all of NOx in the exhaust gas into N2, NH3 and NOx, wherein an amount of NH3 and an amount of NOx generated by the conversion are adjusted so that the amount of NH3 and the amount of NOx are stoichiometrical, wherein the NOx generated is essentially composed of NO2, and wherein a molar ratio of the amount of NO2 generated to the amount of NH3 generated is 1;
1; andpurification means disposed in the exhaust gas passage downstream of the ratio determining means for causing the NH3 generated to react with NOx generated to produce N2 and H2 O components.
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3. An exhaust gas purification device for an internal combustion engine comprising:
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a ratio determining means disposed in an exhaust gas passage of an internal combustion engine for converting substantially all of NOx in the exhaust gas into N2, NH3 and NOx, wherein an amount of NH3 and an amount of NOx generated by the conversion are adjusted so that the amount of NH3 and the amount of NOx are stoichiometrical, wherein the NOx generated is composed of a mixture of NO2 and NO, and wherein a ratio of total moles of NO2 and NO generated to an amount of moles of NH3 generated is larger than 3/4 and smaller than 1; and purification means disposed in the exhaust gas passage downstream of the ratio determining means for causing the NH3 generated to react with NOx generated to produce N2 and H2 O components.
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4. An exhaust gas purification device for an internal combustion engine comprising:
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a ratio determining means disposed in an exhaust gas passage of an internal combustion engine for converting substantially all of NOx in the exhaust gas into N2, NH3 and NOx, wherein an amount of NH3 and an amount of NOx generated by the conversion are adjusted so that the amount of NH3 and the amount of NOx are stoichiometrical, wherein said ratio determining means comprises; NH3 generating means for converting substantially all of the NOx in the exhaust gas into N2 and NH3 ; and NOx generating means for converting a portion of the NH3 generated by the NH3 generating means into NOx, wherein the amount of NOx generated by the NOx generating means and an amount of NH3 remaining in the exhaust gas are adjusted so that the amount of NOx and the remaining amount NH3 are stoichiometrical; and purification means disposed in the exhaust gas passage downstream of the ratio determining means for causing the NH3 generated to react with NOx generated to produce N2 and H2 O components. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27)
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Specification