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  Integrated nox and pm reduction devices for the treatment of emissions from internal combustion enginesUSPTO Application #: 20060179825Title: Integrated nox and pm reduction devices for the treatment of emissions from internal combustion engines Abstract: One concept of the inventors relates to a system and method in which a particulate filter comprises at least about 40% by weight of an NOx adsorbant. The filter can be used as both an NOx trap and a particulate filter. By constructing the filter elements using a substantial amount of NOx adsorbant, a large volume of NOx adsorbant can be incorporated into the particulate filter, which substantially reduces the volume and expense of an exhaust system that includes both a catalytic diesel particulate filter and an NOx trap having a large quantity of NOx adsorbant. In a preferred embodiment, the filter also oxidizes NO to NO2. In another preferred embodiment, an SCR catalyst is position downstream of the filter elements. (end of abstract)
Agent: Paul V. Keller, LLC - South Euclid, OH, US Inventors: Haoran Hu, Subbaraya Radhamohan, Karen Evelyn Bevan, James Edward McCarthy, Johannes W. Reuter, Vishal Singh, Wayne Scott Kaboord, Fred Joseph Begale, Dawn Marie Becher USPTO Applicaton #: 20060179825 - Class: 060297000 (USPTO) Related Patent Categories: Power Plants, Internal Combustion Engine With Treatment Or Handling Of Exhaust Gas, By Means Producing A Chemical Reaction Of A Component Of The Exhaust Gas, Reactor Plus A Washer, Sorber Or Mechanical Separator The Patent Description & Claims data below is from USPTO Patent Application 20060179825. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to the field of pollution control devices for internal combustion engines, especially diesel engines and lean burn gasoline engines. BACKGROUND OF THE INVENTION [0002] NO.sub.x emissions from vehicles with internal combustion engines are an environmental problem recognized worldwide. Several countries, including the United States, have long had regulations pending that will limit NO.sub.x emissions from vehicles. Manufacturers and researchers have put considerable effort toward meeting those regulations. In conventional gasoline powered vehicles that use stoichiometric fuel-air mixtures, three-way catalysts have been shown to control NO.sub.x emissions. In diesel powered vehicles and vehicles with lean-burn gasoline engines, however, the exhaust is too oxygen-rich for three-way catalysts to be effective. [0003] Several solutions have been proposed for controlling NOx emissions from diesel powered vehicles and lean-burn gasoline engines. One set of approaches focuses on the engine. Techniques such as exhaust gas recirculation and homogenizing fuel-air mixtures can reduce NOx emissions. These techniques alone, however, will not solve the problem. Another set of approaches remove NOx from the vehicle exhaust. These include the use of lean-burn NO.sub.x catalysts, lean NO.sub.x traps (LNTs), and selective catalytic reduction (SCR). [0004] Lean-burn NOx catalysts promote the reduction of NO.sub.x under oxygen-rich conditions. Reduction of NOx in an oxidizing atmosphere is difficult. It has proved challenging to find a lean-burn NO.sub.x catalyst that has the required activity, durability, and operating temperature range. Lean-burn NO.sub.x catalysts also tend to be hydrothermally unstable. A noticeable loss of activity occurs after relatively little use. Lean burn NOx catalysts typically employ a zeolite wash coat, which is thought to provide a reducing microenvironment. The introduction of a reductant, such as diesel fuel, into the exhaust is generally required and introduces a fuel economy penalty of 3% or more. Currently, peak NOx conversion efficiency with lean-burn catalysts is unacceptably low. [0005] A lean NOx trap (LNT) is an NOx adsorber combined with a catalyst for NOx reduction. The adsorber removes NOx from lean exhaust. Periodically, the adsorber is regenerated by creating a reducing environment. In the reducing environment, NOx is reduced over the catalyst. The adsorbant is generally an alkaline earth oxide adsorbant, such as BaCO.sub.3 and the catalyst can be a precious metal, such as Ru. [0006] SCR involves the reduction of NOx by ammonia. The reaction takes place even in an oxidizing environment. The NOx can be temporarily stored in an adsorbant or ammonia can be fed continuously into the exhaust. SCR can achieve NOx reductions in excess of 90%, however, there is concern over the lack of infrastructure for distributing ammonia or a suitable precursor. SCR also raises concerns relating to the possible release of ammonia into the environment. [0007] U.S. Pat. No. 6,560,958 describes an LNT system in which hydrogen-rich synthesis gas (syn gas), including H.sub.2 and CO, is used as a reductant to regenerate the adsorbant. The syn gas is produced from diesel fuel in a plasma converter. Periodically, the LNT is taken offline from the exhaust system and supplied with the syn gas. A dual adsorber system is also described. [0008] U.S. Pat. No. 6,732,507 describes a hybrid exhaust treatment system using an LNT and an SCR reactor in series. The SCR reactor captures ammonia produced by the LNT during regeneration and uses the captured ammonia to increase the extent of NOx conversion. [0009] U.S. Patent Application Publication No. 2004/0052699 describes an exhaust treatment device in which the functionalities of a catalytic particulate filter and a NOx adsorber-catalyst are combined into a single device. In one embodiment, a wash coat comprising an NOx adsorbant is applied to a surface of a filter element. [0010] There continues to be a long felt need for reliable, affordable, and effective systems for removing NOx and particulate matter from the exhaust of diesel and lean-burn gasoline engines. SUMMARY OF THE INVENTION [0011] One concept of the inventors relates to a system and method in which a particulate filter comprises at least about 40% by weight of an NOx adsorbant. The filter can be used as both an NOx trap and a particulate filter. By constructing the filter elements using a substantial amount of NOx adsorbant, a large volume of NOx adsorbant can be incorporated into the particulate filter, which substantially reduces the volume and expense of an exhaust system that includes both a catalytic diesel particulate filter and an NOx trap having a large quantity of NOx adsorbant. In a preferred embodiment, the filter also oxidizes NO to NO.sub.2. In another preferred embodiment, an SCR catalyst is position downstream of the filter elements. [0012] The forgoing summary encompasses certain of the inventors' concepts. Its primary purpose is to present these concepts in a simplified form as a prelude to the more detailed description that follows. The summary is not a comprehensive description of what the inventors have invented. Other concepts of the inventors will become apparent to one of ordinary skill in the art from the following detailed description and annexed drawings. Moreover, the detailed description and annexed drawings draw attention to only certain of the inventors' concepts and set forth only certain examples and implementations of what the inventors have invented. Other concepts of the inventors and other examples and implementations of their concepts will become apparent to one of ordinary skill in the art from that which is described and/or illustrated. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a schematic illustration of a particulate filter incorporating an SCR catalyst. [0014] FIG. 2 is a schematic illustration of a particulate filter incorporating an SCR catalyst in a different way. [0015] FIG. 3 is a schematic illustration of a power generation system. [0016] FIG. 4 is a schematic illustration of another power generation system. [0017] FIG. 5 is a schematic illustration of an exhaust treatment system. [0018] FIG. 6 is a schematic illustration of a particulate filter incorporating an SCR catalyst and an NOx adsorbant. [0019] FIG. 7 is a schematic illustration of another particulate filter incorporating an NOx adsorbant. [0020] FIG. 8 is a schematic illustration of another particulate filter incorporating an NOx adsorbant and an SCR catalyst. Continue reading... Full patent description for Integrated nox and pm reduction devices for the treatment of emissions from internal combustion engines Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Integrated nox and pm reduction devices for the treatment of emissions from internal combustion engines patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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