Method and apparatus for reducing nitrogen oxides from internal combustion engine

An apparatus for reducing nitrogen oxides from exhaust gases including nitrogen oxides and an oxygen gas from an internal combustion engine, said apparatus comprising:

• 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.degree. C.

An apparatus for reducing nitrogen oxides from exhaust gases including nitrogen oxides and an oxygen gas from an internal combustion engine, said apparatus comprising:

• 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.degree. C.;
• and
• said 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.

An apparatus for reducing nitrogen oxides from exhaust gases including nitrogen oxides and an oxygen gas from an internal combustion engine, said apparatus comprising:

• 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.degree. C.