Method and apparatus for reducing nitrogen oxides from internal combustion engine
First Claim
1. A method for reducing nitrogen oxides in exhaust gases from an internal combustion engine, comprising the steps of:
- supplying a hydrogen gas from a hydrogen generator for mixing into exhaust gases including nitrogen oxides and oxygen gas at an upstream position of the catalyzer and in a muffler or a downstream position of said muffler, said muffler being positioned close to said catalyzer, said catalyzer and muffler being provided in an exhaust line, said hydrogen generator producing said hydrogen gas by electrolysis of water or water vapor and said catalyzer causing a catalytic reaction between the hydrogen gas and nitrogen oxides to decompose into nitrogen gas and water vapor; and
directly reducing said nitrogen oxides in said exhaust gases with said hydrogen gas under a low temperature atmosphere of not higher than 350°
.
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Abstract
Hydrogen gas from a hydrogen generator which creates hydrogen gas by the electrolysis of water or water vapor is supplied at the entrance to a catalyzer provided in an exhaust line. The catalyzer performs a catalytic reaction between hydrogen gas and nitrogen oxides to achieve decomposition into nitrogen gas and water vapor in the exhaust from an internal combustion engine. The nitrogen oxides are directly reduced with said hydrogen gas in a low temperature atmosphere not higher than 350° C. to achieve efficient reduction in the nitrogen oxides. The improved method and apparatus provide a catalytic system with which the nitrogen oxides in the exhaust from a lean burnt engine or a diesel engine can be effectively reduced irrespective of the concentration of oxygen gas in the exhaust without impairing the good fuel economy of those engines.
284 Citations
20 Claims
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1. A method for reducing nitrogen oxides in exhaust gases from an internal combustion engine, comprising the steps of:
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supplying a hydrogen gas from a hydrogen generator for mixing into exhaust gases including nitrogen oxides and oxygen gas at an upstream position of the catalyzer and in a muffler or a downstream position of said muffler, said muffler being positioned close to said catalyzer, said catalyzer and muffler being provided in an exhaust line, said hydrogen generator producing said hydrogen gas by electrolysis of water or water vapor and said catalyzer causing a catalytic reaction between the hydrogen gas and nitrogen oxides to decompose into nitrogen gas and water vapor; and directly reducing said nitrogen oxides in said exhaust gases with said hydrogen gas under a low temperature atmosphere of not higher than 350°
.
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2. An apparatus for reducing nitrogen oxides from exhaust gases including nitrogen oxides and an oxygen gas from an internal combustion engine, said apparatus comprising:
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a catalyzer for reducing said nitrogen oxides into a nitrogen gas and water vapor by a catalytic reaction between a hydrogen gas and nitrogen oxides, said catalyzer being provided in an exhaust line; a muffler located upstream and close to said catalyzer, said muffler being provided in said exhaust line; and a hydrogen generator for producing the hydrogen gas by the electrolysis of water or water vapor, thereby supplying said hydrogen gas into said exhaust gases at an upstream position of said catalyzer and in said muffler or a downstream position of said muffler; whereby said nitrogen oxides are directly reduced with said hydrogen gas from said hydrogen generator under a low temperature atmosphere of not higher than 350°
C. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for reducing nitrogen oxides from exhaust gases including nitrogen oxides and an oxygen gas from an internal combustion engine, said apparatus comprising:
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a catalyzer for reducing said nitrogen oxides into a nitrogen gas and water vapor by a catalytic reaction between a hydrogen gas and nitrogen oxides, said catalyzer being provided in an exhaust line; and a hydrogen generator for producing the hydrogen gas by the electrolysis of water or water vapor, thereby supplying said hydrogen gas into said exhaust gases at an upstream position of said catalyzer; wherein; said nitrogen oxides are directly reduced with said hydrogen gas from said hydrogen generator under a low temperature atmosphere of not higher than 350°
C.; andsaid hydrogen generator is provided with a mixer for mixing uniformly said hydrogen gas into said exhaust gas, in which said mixer consists of a flared diameter portion of said exhaust pipe and an injecting nozzle having a few orifices. - View Dependent Claims (19)
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20. An apparatus for reducing nitrogen oxides from exhaust gases including nitrogen oxides and an oxygen gas from an internal combustion engine, said apparatus comprising:
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a catalyzer for reducing said nitrogen oxides into a nitrogen gas and water vapor by a catalytic reaction between a hydrogen gas and nitrogen oxides, said catalyzer and being provided in an exhaust line; a muffler located upstream and close to said catalyzer, said muffler being provided in said exhaust line; and a hydrogen generator for producing the hydrogen gas by the electrolysis of an aqueous methanol or a vapor of a mixture of methanol and water, thereby supplying said hydrogen gas into said exhaust gases at an upstream position of said catalyzer and in said muffler or a downstream position of said muffler; and whereby said nitrogen oxides are directly reduced with said hydrogen gas from said hydrogen generator under a low temperature atmosphere of not higher than 350°
C.
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Specification