815 results about "Reduced nitrogen" patented technology

An exhaust aftertreatment system comprises an injector for injecting urea water into an exhaust duct, and a denitration catalyst disposed downstream of the injector with respect to a flow of exhaust gas. The exhaust aftertreatment system reduces nitrogen oxides in the exhaust gas by the denitration catalyst while using ammonia produced from the urea water injected from the injector. The urea water is injected along a direction of the flow of the exhaust gas within the exhaust duct, and a porous plate is disposed in multiple stages in a space of the exhaust duct such that droplets of the injected urea water impinge against the porous plate before reaching a wall surface of the exhaust duct. A surface of the porous plate subjected to the impingement of the droplets is arranged to face downstream with respect to the flow of the exhaust gas. Deposition of the urea water is prevented by causing film boiling when the droplets impinge against the porous plate, and the urea water reflected by the porous plate is uniformly dispersed into the exhaust gas. Thus, the urea water is uniformly dispersed into the exhaust gas without increasing a pressure loss of the exhaust gas. The urea water is prevented from depositing on the wall surface and producing a precipitate in the form of a solid.

A catalyst system and a method for reducing nitrogen oxides in an exhaust gas by reduction with a hydrocarbon or oxygen-containing organic compound reducing agent are provided. The catalyst system contains a silver catalyst and a modifier catalyst, where the modifier catalyst contains a modifier oxide, where the modifier oxide is selected from the group consisting of iron oxide, cerium oxide, copper oxide, manganese oxide, chromium oxide, a lanthanide oxide, an actinide oxide, molybdenum oxide, tin oxide, indium oxide, rhenium oxide, tantalum oxide, osmium oxide, barium oxide, calcium oxide, strontium oxide, potassium oxide, vanadium oxide, nickel oxide, tungsten oxide, and mixtures thereof. The modifier oxide is supported on an inorganic oxide support or supports, where at least one of the inorganic oxide supports is an acidic support. The catalyst system of the silver catalyst and the modifier catalyst provides higher NO_x conversion than either the silver catalyst or the modifier catalyst alone.

A combustion control system allows the dramatic reduction of NOx emission levels from industrial combustion processes without having recourse to expensive flue gas clean up methods. The system combines the technique of oscillating combustion with an adapted system for post combustion burn out of the excess of CO resulting from the low-NOx combustion zone. A process for fuel combustion includes generating an oscillating combustion zone by oscillating at least one of the fuel flow and the oxidant flow to achieve a reduced nitrogen oxide emission, selecting oscillating parameters and furnace operating parameters to maximize nitrogen oxide reduction efficiency to the detriment of carbon monoxide production, and combusting carbon monoxide downstream of the oscillating combustion zone by injecting a post combustion oxidant.

A method is provided for producing ammonia (NH₃) and introducing the produced ammonia (NH₃) into an exhaust gas stream as a reduction means for selectively catalytically reducing nitrogen oxides contained in the exhaust gas stream, which is an exhaust stream generated by the combustion process of a motor, a gas turbine, or a burner. The method comprises feeding dry urea from a supply container in a controlled amount to reactor and subjecting the dry urea in the reactor to a sufficiently rapid thermal treatment such that a gas mixture comprising the reaction products of ammonia (NH₃) and isocyanic acid (HCNO) is created. Also, the method comprises immediately catalytically treating the thus produced gas mixture in the presence of water such that the isocyanic acid (HCNO) resulting from the rapid thermal treatment is converted, via quantitative hydrolysis treatment, into ammonia (NH₃) and carbon dioxide (CO₂).

A DPF with an SCR catalyst and a method for selectively reducing nitrogen oxides with ammonia, filtering particulates, and reducing the ignition temperature of soot on a DPF are provided. The catalyst includes a first component of copper, chromium, cobalt, nickel, manganese, iron, niobium, or mixtures thereof, a second component of cerium, a lanthanide, a mixture of lanthanides, or mixtures thereof, and a component characterized by increased surface acidity. The catalyst may also include strontium as an additional second component. The catalyst selectively reduces nitrogen oxides to nitrogen with ammonia and oxidizes soot at low temperatures. The catalyst has high hydrothermal stability.

A method for the anodic electrochemical synthesis of ammonia gas. The method comprises providing an electrolyte between an anode and a cathode, providing nitrogen and hydrogen gases to the cathode, oxidizing negatively charged nitrogen-containing species and negatively charged hydrogen-containing species present in the electrolyte at the anode to form adsorbed nitrogen species and adsorbed hydrogen species, respectively, and reacting the adsorbed nitrogen species with the adsorbed hydrogen species to form ammonia. Nitrogen and hydrogen gases may be provided through a porous cathode substrate. The negatively charged nitrogen-containing species in the electrolyte may be produced by reducing nitrogen gas at the cathode and/or by supplying a nitrogen-containing salt, such as lithium nitride, into the molten salt electrolyte. Similarly, the negatively charged hydrogen-containing species in the electrolyte may be produced by reducing hydrogen gas at the cathode and/or by supplying a hydrogen-containing salt, such as lithium hydride, into the molten salt electrolyte.

A fuel cell system with fuel processor for integration with a marine vessel propulsion system. The system includes an auto thermal reactor that is the fuel processor for producing hydrogen from a fuel source. The fuel source is preferably ethanol or biodiesel or a mixture thereof, but can also be a sulfur containing fuel like petrodiesel of JP-8. The system further includes a gas-water shift reactor for further production and concentration of the hydrogen from the auto thermal reactor output. The system also includes a hydrogen permeable membrane separator for generating suitable quantities of essentially pure hydrogen to the fuel cell. The system also includes an oxygen permeable membrane separator for concentrating oxygen and reducing nitrogen to improve the partial pressure of hydrogen in subsequent fuel processing steps. The system contemplates the use of a Polymer Electrolyte Membrane (PEM) fuel cell. The system minimizes preheating of catalysts or other components to the extent just needed to initiate the fuel processor. To that end, heat sources and sinks of the system and associated usage systems are matched so as to minimize heat collection, storage and distribution systems. Water is recycled within the system to the extent necessary to maintain a water balance in the fuel processor and the fuel cell stack(s). The system includes cooling of the fuel cell stack(s) and integrated heat recovery with exothermic and endothermic catalysts. The fuel processor/fuel cell system components are configured to conform to and take advantage of the available space and limitations, such as the space constraints and opportunities associated with a marine vessel.

Example embodiments of this invention relate to a coated article including an infrared (IR) reflecting layer of a material such as silver or the like, for use in an insulating glass (IG) window unit for example. In certain example embodiments, the coating is a single-silver type coating, and includes an overcoat including an uppermost layer of or including silicon nitride and a layer of or including tin oxide immediately under and contacting the silicon nitride based overcoat. In certain example embodiments, the thicknesses of the silicon nitride based overcoat and the tin oxide based layer are balanced (e.g., substantially equal, or equal plus/minus about 10%). It has surprisingly been found that such balancing results in an improvement in thermal cycling performance and improved mechanical durability. In certain example embodiments, the coating may realize surprisingly good substantially neutral film side reflective coloration, and may achieve an improved visible transmission, SHGC ratio and low U-values. Moreover, in certain example embodiments, stress in the overcoat of the coating may be reduced by reducing nitrogen gas flow (N₂ ml/kW) and cathode power during a sputter-deposition process, thereby further improving thermal cycling performance.

The invention relates to a low-vanadium denitration catalyst and a preparation method and application thereof, and belongs to the technical fields of environmental materials, environmental catalysis and environmental protection. The catalyst is prepared by a co-immersion method by adopting anatase titanium dioxide as a carrier, vanadium pentoxide as a main active component and tungstic oxide and cerium oxide as minor active components. Moreover, the low-vanadium denitration catalyst is characterized in that the catalyst reduces both the dosage of highly toxic vanadium and cost, and also has a conversion rate of NOx higher than 90 percent within a temperature range from 200 to 450 DEG C. The method provided for reducing nitrogen oxide comprises the following steps: putting the catalyst in a fixed bed reactor and controlling the reaction temperature between 200 and 500 DEG C; and taking NH3 as a reducing agent and controlling air speed at 28,000h and total gas flow at 300ml/min. The low-vanadium denitration catalyst still maintains high conversion rate of NOx in the presence of water and sulfur dioxide, and is suitable for treating NOx in exhaust gases discharged from thermal power plants, smelting plants, oil plants, and the like.

A catalyst and a method for selectively reducing nitrogen oxides (“NO_x”) with ammonia are provided. The catalyst includes a first component comprising a zeolite or mixture of zeolites selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, MCM-zeolites, mordenite, faujasite, ferrierite, zeolite beta, and mixtures thereof; a second component comprising at least one member selected from the group consisting of cerium, iron, copper, gallium, manganese, chromium, cobalt, molybdenum, tin, rhenium, tantalum, osmium, barium, boron, calcium, strontium, potassium, vanadium, nickel, tungsten, an actinide, mixtures of actinides, a lanthanide, mixtures of lanthanides, and mixtures thereof; optionally an oxygen storage material and optionally an inorganic oxide. The catalyst selectively reduces nitrogen oxides to nitrogen with ammonia at high temperatures. The catalyst has high hydrothermal stability. The catalyst has high activity for conversion of low levels of nitrogen oxides in exhaust streams. The catalyst and the method may have special application to selective reduction of nitrogen oxides in exhaust gas from gas turbines and gas engines, although the catalyst and the method have broad application to a wide range of gas streams that have excess oxygen and high temperatures. The temperature of exhaust gas from gas turbines and gas engines is high. Both the high temperature and the low levels of inlet NO_x are challenging for selective catalytic reduction (SCR) catalysts.

The invention herein relates to controlling the nitrogen content in silicon carbide crystals and in particular relates to reducing the incorporation of nitrogen during sublimation growth of silicon carbide. The invention controls nitrogen concentration in a growing silicon carbide crystal by providing an ambient atmosphere of hydrogen in the growth chamber. The hydrogen atoms, in effect, block, reduce, or otherwise hinder the incorporation of nitrogen atoms at the surface of the growing crystal.

The use of organic waste/mineral by-product mixtures as raw materials in the manufacture of cement clinker; as alternative or supplemental fuel sources for heating a kiln used in a cement clinker manufacturing process; and, to reduce nitrogen oxide (NO_x) emissions generated during cement manufacturing processes are disclosed.

Systems and methods of removing at least nitrogen oxides from an exhaust fluid generally include introducing a first reducing agent and a hydrogen gas co-reductant agent into the exhaust fluid upstream of a catalyst bed optimized for a hydrocarbon selective catalytic reduction process to reduce nitrogen oxides present in the exhaust fluid and then reacting residual nitrogen oxides in a second catalytic bed optimized for an ammonia selective catalytic reduction process. The use of hydrogen gas permits efficient reduction of nitrogen oxides over a wide temperature range, which is minimally affected by the presence of sulfur dioxide in the exhaust fluid.

The invention relates to a honeycomb metal network carrier catalyst for catalyzing and reducing nitrogen oxide, and relative preparation, used in vehicle tail gas purification technique. The invention comprises metal carrier and catalyst, characterized in that the catalyst is load-type catalyst, the catalyst carrier is honeycomb metal network carrier carrying gamma-Al2O3 coat, referring coat mass, the content of TiO2 is 14.0-20.0wt% and the content of CeZrO is 3.0-6.0wt%, and referring to catalyst mass, the content of active component palladium is 0.1-1.0wt%, and the preparation comprises that preparing TiO2 gel, preparing TiO2 coat at the face of carrier, loading cerium zirconium oxide on carrier, leading in catalyst active component palladium. The invention has the advantages that the invention can improve mass transfer and heat transfer in catalyst, the catalyst has higher catalysis activity in low-temperature oxygen-abundant condition, wide active temperature window, simple preparation and low cost.

The invention discloses a technique for treating the tail gas of an acrylonitrile device, which is suitable for treating acrylonitrile tail gas discharged by the acrylonitrile device. The technique is characterized in that: after free water is separated out by a gas-liquid separator, the acrylonitrile tail gas is mixed with air, a noble metal monolithic catalyst is taken as a catalyst and catalytic oxidation reaction is carried out to turn harmful volatile organic compounds into carbon dioxide and water; then a selective reduction monolithic catalyst is taken as a catalyst and selective catalytic reduction reaction with added ammonia is carried out to reduce nitrogen oxide in the tail gas into nitrogen and water. The technique has the advantages of simple technique, turning the harmful volatile organic compounds and nitrogen oxide in the tail gas into carbon dioxide, nitrogen and water, without secondary pollution, the test results totally meeting the environmental protection control requirements of the State Standard of China, adopting a tail gas heat exchanger to recycle reaction heat to heat input tail gas, needing no additional fuel during the normal operation process, small system resistance and low operation cost.

A method for producing ammonia suitable for use as a reductant in a combustion exhaust gas treatment system is provided that includes the electrolytic hydrolysis of urea under mild conditions. The ammonia generator, which includes an electrolysis apparatus including an electrolytic flow cell, an alkaline electrolyte composition, and a recirculation system, may be operatively coupled to an exhaust gas treatment system to provide an apparatus for reducing nitrogen oxides (NO_x) and/or particulate in exhaust gases.

A catalyst and a method for selectively reducing nitrogen oxides with ammonia are provided. The catalyst includes a first component of copper, chromium, cobalt, nickel, manganese, iron, niobium, or mixtures thereof, a second component of cerium, a lanthanide, a mixture of lanthanides, or mixtures thereof, and a zeolite. The catalyst may also include strontium as an additional second component. The catalyst selectively reduces nitrogen oxides to nitrogen with ammonia at low temperatures. The catalyst has high hydrothermal stability. The catalyst has high activity for conversion of nitrogen oxides in exhaust streams, and are not significantly influenced by the NO/NO₂ ratio. The catalyst and the method may have special application to selective reduction of nitrogen oxides in exhaust gas from diesel vehicles, although the catalyst and the method have broad application to a wide range of gas streams that contain nitrogen oxides. The temperature of exhaust gas from diesel vehicles is low, and the exhaust gas generally has a high NO/NO₂ ratio. Both the low temperature and the high NO/NO₂ ratio are challenging for selective catalytic reduction (SCR) catalysts.

An exhaust gas purifying catalyst for purifying exhaust gas discharged from an automotive internal combustion engine. The exhaust gas purifying catalyst comprises a monolithic substrate. A HC adsorbing layer for adsorbing hydrocarbons (HC) is formed on the monolithic substrate. The HC absorbing layer contains zeolite. A catalytic layer for producing hydrogen (H₂) and reducing NOx is formed on the HC adsorbing layer. The catalytic layer functions to produce hydrogen (H₂) from at least one of hydrocarbons and carbon monoxide (CO) and to reduce nitrogen oxides (NOx) with the produced hydrogen and at least one of hydrocarbons and carbon monoxide in exhaust gas.

The present invention is directed to a process for treating, reducing, and/or stabilizing various wastes or flue gases. In one embodiment, the process is directed to treatment of alkali bearing wastes that include nitrate and/or nitrite-rich wastes. Optionally, the disclosed method can be utilized for treatment of hazardous wastes, including radioactive hazardous waste compounds. In general, the present invention includes processing a waste or gaseous stream with the addition of suitable carbon-containing additives to treat and reduce nitrogen-containing compounds in the waste. Additives may be gaseous, liquid or solid reduction-promoting agents, catalysts, and the like. The reaction products obtained from the process of the invention include mainly alkali carbonate, nitrogen, hydrogen, carbon monoxide and carbon dioxide.

A pressure swing adsorption process for the separation of nitrogen and/or CO₂ from natural gas utilizes two separate pressure swing adsorption stages, the first containing a hydrocarbon-selective adsorbent and the second containing a nitrogen- and/or CO₂-selective adsorbent. In the process, the product stream from the first pressure swing adsorption unit contains a natural gas stream having a reduced hydrocarbon content and the product stream from the second pressure swing adsorption unit is a natural gas stream having a reduced nitrogen and/or CO₂ concentration. An intermediate pressure stream containing methane from the second pressure swing adsorption unit is used to desorb the hydrocarbons from the first pressure swing adsorption unit. The C₃+ hydrocarbons can be separated as liquids from the methane.