Exhaust gas purification system for an internal combustion engine
First Claim
1. An exhaust gas purification system for an internal combustion engine comprising:
- the internal combustion engine being capable of fuel combustion at lean air-fuel ratios, the engine having an exhaust manifold and an exhaust conduit connected to the manifold;
a catalyst installed in the exhaust conduit of the engine and constructed of zeolite carrying at least one kind of metal selected from transition metals and noble metals, said catalyst being employed to reduce nitrogen oxides included in exhaust gas from the engine under oxidizing conditions and in the presence of hydrocarbons;
an HC producing means for producing hydrocarbons of low boiling points from fuel for combustion in the engine by subjecting at least a portion of the fuel for combustion to a process selected from the group including cracking and fractional distillation; and
an HC supply means for supplying the hydrocarbons of low boiling points produced by the HC producing means to the exhaust conduit upstream of the catalyst.
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Accused Products
Abstract
An exhaust gas purification system for an internal combustion engine includes an engine 1 capable of fuel combustion at lean air-fuel ratios, a lean NOx catalyst 3 installed in an exhaust conduit 16 of the engine, an HC producing means for producing hydrocarbons of low boiling points utilizing fuel for the engine, and an HC supply means for supplying the hydrocarbons of low boiling points to the exhaust conduit upstream of the lean NOx catalyst 3. NOx reduction reaction needs hydrocarbons of low boiling points. The HC producing means produces hydrocarbons of low boiling points from diesel oil by cracking, fractional distillation, or both cracking and fractional distillation. The cracked and/or distilled fuel includes a large amount of hydrocarbons of low boiling points and increases NOx purification rate of the lean NOx catalyst when the hydrocarbons of low boiling points are introduced into the exhaust conduit by the HC supply means.
125 Citations
12 Claims
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1. An exhaust gas purification system for an internal combustion engine comprising:
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the internal combustion engine being capable of fuel combustion at lean air-fuel ratios, the engine having an exhaust manifold and an exhaust conduit connected to the manifold; a catalyst installed in the exhaust conduit of the engine and constructed of zeolite carrying at least one kind of metal selected from transition metals and noble metals, said catalyst being employed to reduce nitrogen oxides included in exhaust gas from the engine under oxidizing conditions and in the presence of hydrocarbons; an HC producing means for producing hydrocarbons of low boiling points from fuel for combustion in the engine by subjecting at least a portion of the fuel for combustion to a process selected from the group including cracking and fractional distillation; and an HC supply means for supplying the hydrocarbons of low boiling points produced by the HC producing means to the exhaust conduit upstream of the catalyst. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification