Patent•
NOx decreasing apparatus for an internal combustion engine
15 Oct 1992-
TL;DR: In this article, a lean NOx reduction catalyst capable of reducing NOx through reaction of H 2 with NOx at low temperatures below 350°C is installed in a downstream portion of an exhaust pipe of an internal combustion engine in or near a muffler.
Abstract: A lean NOx reduction catalyst capable of reducing NOx through reaction of H 2 with NOx at low temperatures below 350° C. is installed in a downstream portion of an exhaust pipe of an internal combustion engine in or near a muffler. Such an NOx reduction catalyst comprises, for example, Pt/zeolite catalyst. An H 2 generator is installed so as to supply the H 2 to an inlet side of the NOx reduction catalyst. The H 2 generator may include a reforming catalyst for reforming methanol, LPG, or natural gas to generate H 2 . The generated H 2 flows to the NOx reduction catalyst where it reacts with NOx to purify the exhaust gas.
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Patent•
17 Sep 1999TL;DR: In this article, a converter containing a NOx absorbing and reducing catalyst is disposed in the exhaust passage of an internal combustion engine, where the upstream half portion (portion of the inlet side) of the substrate carries the oxygen storage component that absorbs oxygen in exhaust gas and releases the absorbed oxygen when the air-fuel ratio of the exhaust gas flowing in is rich.
Abstract: A converter containing a NOx absorbing and reducing catalyst is disposed in the exhaust passage of an internal combustion engine. The upstream half portion (portion of the inlet side) of the substrate of the NOx absorbing and reducing catalyst in the converter carries the oxygen storage component that absorbs oxygen in the exhaust gas when the air-fuel ratio of the exhaust gas is lean and releases the absorbed oxygen when the air-fuel ratio of the exhaust gas flowing in is rich in addition to carrying the NOx absorbing and reducing catalyst. After NOx is absorbed by the NOx absorbing and reducing catalyst as a result of operating the engine at a lean air-fuel ratio, the engine is operated at a rich air-fuel ratio, so that NOx is released from the NOx absorbing and reducing catalyst and is purified by reduction. Here, oxygen is released from the oxygen storage component carried by the upstream half portion of the substrate and is reacted with the H 2 and CO components in the exhaust gas, so that the temperature of the NOx absorbing and reducing catalyst is raised within short periods of time due to the heat of reaction. Therefore, the catalyst exhibits increased activity and the NOx absorbing and reducing catalyst exhibits improved NOx purification capability.
494 citations
Patent•
17 Nov 2003TL;DR: In this article, a fuel processor that efficiently converts added hydrocarbon fuel to a reducing mixture of H2 and CO is presented. But the added fuel may be a portion of the onboard fuel on a vehicle.
Abstract: The invention provides devices and methods for generating H2 and CO in an O2 containing gas stream. The invention also provides devices and methods for removal of NOX from an O2 containing gas stream, particularly the oxygen-rich exhaust stream from a lean-burning engine, such as a diesel engine. The invention includes a fuel processor that efficiently converts added hydrocarbon fuel to a reducing mixture of H2 and CO. the added fuel may be a portion of the onboard fuel on a vehicle. The H2 and CO are incorporated into the exhaust stream and reacted over a selective lean NOX catalyst to convert NOX to N2, thereby providing an efficient means of NOX emission control.
172 citations
Patent•
02 Jun 2006
TL;DR: An exhaust gas-purifying catalyst includes a substrate, and a catalytic layer formed on the substrate using slurry containing a precious metal, alumina, an oxygen storage material and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle size being obtained by observation using a scanning electron microscope as mentioned in this paper.
Abstract: An exhaust gas-purifying catalyst includes a substrate, and a catalytic layer facing the substrate and including a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope. Another exhaust gas-purifying catalyst includes a substrate, and a catalytic layer formed on the substrate using slurry containing a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope.
170 citations
Patent•
21 Nov 2002
TL;DR: In this paper, an accurate thermodynamic model of an active lean NOx (ALNC) Catalyst is presented, which takes into account hydrocarbon storage and release mechanisms of ALNC, as well as the degradation in the ALNC hydrocarbon conversion efficiency due to ageing, and thus provides a more accurate estimate of an exotherm generated by hydrocarbon combustion.
Abstract: An accurate thermodynamic model of an Active Lean NOx (ALNC) Catalyst is presented. The model takes into account hydrocarbon storage and release mechanisms of the ALNC, as well as the degradation in the ALNC hydrocarbon conversion efficiency due to ageing, and thus provides a more accurate estimate of an exotherm generated by hydrocarbon combustion in the ALNC. The estimated exotherm can them be used to detect system degradation and identify components responsible for the degradation.
161 citations
Patent•
03 Apr 2002
TL;DR: In this paper, an exhaust gas purifying system capable of forcibly regenerating DPF by efficiently raising the temperature of exhaust gas even when the exhaust gas temperature is very low at low load and low engine speed such as an idling operation is presented.
Abstract: To provide an exhaust gas purifying system capable of forcibly regenerating DPF by efficiently raising the temperature of exhaust gas even when an exhaust gas temperature is very low at the time of low load and low engine speed such as an idling operation. In an exhaust purifying system (1) having an exhaust throttling valve (31) and a DPF (3) in an exhaust passage and having regeneration control means (P1) for regenerating the DPF (3), the regeneration control means (P1) is provided with an exhaust gas temperature detection means (P22), a fuel injection control means (P11), and an exhaust throttling control means (P12) and includes regeneration control for performing the exhaust gas temperature raising control through the multistage delay injection by the fuel injection control means (P11) and through the exhaust throttling of the exhaust throttling valve (31).
149 citations
References
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Patent•
22 May 1992TL;DR: In this paper, an 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 exhaust without impairing the good fuel economy of those engines.
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.
186 citations
Patent•
22 Jun 1981TL;DR: In this article, a method and apparatus for efficiently reducing the amount of nitrogen oxides contained in a combusted gas stream from an engine combustion chamber was described, where ammonium is reliably and instantaneously metered to the combusted gaseous gas stream conduit in a preselected proportion to the fuel mass flow rate and only in response to the sensed temperature of the gas stream in the reactor.
Abstract: A method and apparatus is disclosed for efficiently reducing the amounts of nitrogen oxides contained in a combusted gas stream from an engine combustion chamber (14). Ammonia is reliably and instantaneously metered to the combusted gas stream conduit (24) in a preselected proportion to the fuel mass flow rate and only in response to the sensed temperature of the combusted gas stream in the reactor (26) being within a preselected range.
77 citations
Patent•
22 Mar 1976TL;DR: In this article, a hydrogen generator contains a catalyst which must be heated to a pre-determined temperature before it can react properly, and to simplify the process of heating up the catalyst at start-up time, either some of the engine such as engine exhaust gas, or electrical energy produced by the engine, or the engine exhaust gases may be used to heat up air which is then used to Heat the catalyst.
Abstract: A hydrogen generator provides hydrogen rich product gases which are mixed with the fuel being supplied to an internal combustion engine for the purpose of enabling a very lean mixture of that fuel to be used, whereby nitrous oxides emitted by the engine are minimized. The hydrogen generator contains a catalyst which must be heated to a pre-determined temperature before it can react properly. To simplify the process of heating up the catalyst at start-up time, either some of the energy produced by the engine such as engine exhaust gas, or electrical energy produced by the engine, or the engine exhaust gas may be used to heat up air which is then used to heat the catalyst.
72 citations
Patent•
05 Nov 1991
TL;DR: In this article, a high-silica zeolite having a Si/Al ratio of 40 or more has been subjected to ion exchange with at least one metal selected from Pt, Pd, Rh, Ir and Ru.
Abstract: A catalyst composition for purification of exhaust gas, comprises (a) high-silica zeolite having a Si/Al ratio of 40 or more which has been subjected to ion exchange with at least one metal selected from Pt, Pd, Rh, Ir and Ru, and (b) a heat-resistant oxide containing at least one metal selected from Pt, Pd, Rh, Ir and Ru. The catalyst composition is supported on a monolith carrier as a single layer or with the two components (a) and (b) as separate layers. The catalyst has high activity for exhaust gas purification even when it contains Rh, which is an expensive catalyst component, in a very small amount.
70 citations
Patent•
04 Apr 1990
TL;DR: In this paper, a method for removing nitrogen oxides from exhaust gases containing oxygen and moisture, which comprises bringing the exhaust gas into contact with hydrogenated zeolite catalysts or hydrogenated catalysts impregnated with one or more kinds of metals selected from the group consisting of copper, zinc, vanadium, chromium, manganese, iron, cobalt, nickel, rhodium, palladium, platinum, and molybdenum, in the presence of organic compounds, was proposed.
Abstract: A method for removing nitrogen oxides from exhaust gases containing oxygen and moisture, which comprises bringing the exhaust gas into contact with hydrogenated zeolite catalysts or hydrogenated zeolite catalysts impregnated with one or more kinds of metals selected from the group consisting of copper, zinc, vanadium, chromium, manganese, iron, cobalt, nickel, rhodium, palladium, platinum, and molybdenum, in the presence of organic compounds. The zeolite should be a zeolite having a silica/alumina ratio of 5 or above. The zeolite may be any one of zeolite of Y type, zeolite of L type, zeolite of offretite-erionite mixed crystal type, zeolite of ferrierite type, zeolite of mordenite type, zeolite of clinoptilolite type, and zeolite of ZSM-5 type.
55 citations