Abstract: A method for injecting ammonia into an exhaust gas stream downstream of a diesel engine includes providing an exhaust gas passageway (11) from the diesel engine to an ambient (14). The exhaust gas passageway (11) includes an NOx Slip Catalyst (NSC) 20 downstream of an NOx Particulate Filter (NPF) 18. The method includes emitting exhaust gas (EG) through the exhaust gas passageway (11), and selectively injecting ammonia (NH3) upstream of the NPF 18, upstream of the NSC (20), both upstream of the NPF and the NSC, or not injecting ammonia, depending on the temperature of the exhaust gas at the NPF and at the NSC.

Abstract: A method for operating an exhaust gas treatment device having at least one heater and at least one supply device for a reducing agent includes initially carrying out a test in order to determine if the reducing agent is to be supplied, and subsequently implementing different heating strategies in each case. In the event that the reducing agent is to be supplied, the exhaust gas treatment device is heated with the heater until a first threshold temperature is reached, if a first temperature lies below the first threshold temperature. In the case when no reducing agent is to be fed, the exhaust gas treatment device is heated with the heater until a second threshold temperature is reached, if a second temperature lies below the second threshold temperature. A motor vehicle having the device is also provided.

Abstract: A method for use with an exhaust gas post-treatment system on an internal combustion engine operated with aft surplus includes reducing nitrous oxides in that an ammonia-separating reducing agent is added to the exhaust gas flow upstream of a catalyst which is charged with a catalyst material for selective catalytic reduction of nitrous oxides. The method further provides that the NH3 to NOx ratio (feed ratio ?) is varied in phases by changing the untreated nitrous oxide emissions of the internal combustion engine such that the feed ratio ? oscillates in phases about a predefined value.

Abstract: The present invention is directed at ketone/water mixtures for treating gas mixtures containing nitric oxides (NOx). The chemical reduction of NOx by the ketone/water mixture affords a relatively less objectionable combustion waste product for discharge into the atmosphere. The gas mixture for treatment of the ketone/water mixture may be preferably regulated to have a level of oxygen of at or below 5.0 vol. %.

Abstract: To overcome the problem of a conventional catalyst and to provide an exhaust gas purifying catalyst that meets the requirement concerning Hg oxidation activity and SO2 oxidation activity; i.e., an exhaust gas purifying catalyst which specifically reduces percent SO2 oxidation, while maintaining percent Hg oxidation at a high level. The invention provides an exhaust gas purifying catalyst which comprises a composition containing oxides of (i) titanium (Ti), (ii) molybdenum (Mo) and/or tungsten (W), (iii) vanadium (V), and (iv) phosphorus (P), wherein the catalyst contains Ti, Mo and/or W, and V in atomic proportions of 85 to 97.5:2 to 10: 0.5 to 10, and has an atomic ratio of P/(sum of V and Mo and/or W) of 0.5 to 1.

Abstract: Systems and methods are provided for determining and controlling an NO2 to NOx ratio reference target in an exhaust conduit between a first SCR catalyst and a second SCR catalyst. The method includes determining a present NO2 to NOx ratio in the exhaust conduit between the first SCR catalyst and the second SCR catalyst, and providing a reductant doser command in response to a deviation of the present NO2 to NOx ratio from the NO2 to NOx ratio reference target.

Abstract: A method for producing a catalyst using an additive layer method includes: (i) forming a layer of a powdered catalyst or catalyst support material, (ii) binding or fusing the powder in said layer according to a predetermined pattern, (iii) repeating (i) and (ii) layer upon layer to form a shaped unit, and (iv) optionally applying a catalytic material to said shaped unit.

Abstract: Catalysts, methods of preparing catalyst, and methods for treating exhaust gas streams are described. In one or more embodiments, a catalyst system includes an upstream zone effective to catalyze the conversion of a mixture of NOx and NH3 to N2, and a downstream zone effective for the conversion of ammonia to N2 in the presence or absence of NOx. In an embodiment, a method for preparing a catalyst system includes: first coating one end of a substrate along at least 5% of its length with an undercoat washcoat layer containing a material composition effective to catalyze the removal of ammonia; second coating with an overcoat layer containing a material composition effective to catalyze the conversion of a mixture of NOx and NH3 to N2.

Abstract: The invention provides a process for minimizing the emission of particulate matter and precursors thereof from a flue gas stream of an engine comprising particulate matter and precursors thereof and at least one gaseous component. The process includes the steps of obtaining a flue gas stream of an engine comprising particulate matter and precursors thereof; increasing the moisture content of the stream by contacting it with a first aqueous medium in an amount and at a temperature at which at least 50% of the water content of the first aqueous medium is evaporated; whereby a moisture laden gas stream, optionally containing suspension droplets, is formed; cooling the moisture laden gas stream whereby suspension droplets are formed; and applying a centrifugal force to the moisture laden gas stream and to the suspension droplets to effect the swirling thereof, whereby a treated gaseous stream and an aqueous stream are formed.

Abstract: A mixture of urea, water and ammonium carbamate is formulated for use in the catalytic reduction of oxides of nitrogen in diesel exhaust. The mixtures may be formulated to optimize the amount of reductant in the mixture and the freezing point of the formulation. These formulations are especially useful in combination with Selective Catalytic Reduction systems and are well suited for use on heavy-duty trucks and heavy duty equipment used off-road. Some of these formations include between about 15.0 wt. % to about 40.0 wt. % urea; between about 15.0 wt. % to about 40.0 wt. % ammonium carbamate; and between about 40.0 wt. % to about 60.0 wt. % water. The formulation may be monitored for ammonia content and/or freezing point and the composition of the formulation may be adjusted to optimize the freezing point and ammonia content.

Abstract: A method fluidly coupling components of an exhaust gas treatment system to an exhaust gas system, then injecting gaseous ammonia into the gas treatment system, beginning reaction of gaseous ammonia with exhaust gas at a temperature of less than about 180° C., preferably about 150° C., and then continuing reaction of gaseous ammonia with exhaust gas during operation of the vehicle, is disclosed. The gas treatment system includes a mixing chamber for reacting gaseous ammonia with exhaust gas to reduce NOx in the exhaust gas. Other components of the system include a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a NOx slip catalyst (NSC) canister, wherein the DOC, DPF and NSC are all fluidly coupled together and to the mixing chamber, an injection port for adding gaseous ammonia to the mixing chamber, and a solid ammonia source for supplying gaseous ammonia to the injection port.

Abstract: The present invention relates to a method for the treatment of an exhaust gas comprising NOx, wherein the method comprises the step of subjecting the exhaust gas to an exhaust gas treatment system comprising, in order of the exhaust stream: (a) a first NOx storage catalytic converter (2, 2?); (b) a catalytic converter (3) for selective catalytic reduction (SCR) downstream of the first NOx storage catalytic converter; and (C) a catalytic converter (4) having oxygen storage capacity downstream of the SCR catalytic converter; wherein the exhaust gas treatment system is operated in alternating rich and lean phases, wherein the rich phase is terminated when the amount of reducing components leaving the first NOx storage catalytic converter is at least 0.

Abstract: In a method for monitoring an SCR catalyst, in particular for monitoring the storage capacity of the SCR catalyst for ammonia, superstoichiometric metering (69) of reducing agents into the SCR catalyst is performed for diagnostic purposes, and the storage capacity of the SCR catalyst is inferred in accordance with at least one characteristic value, which is dependent on the nitrogen oxide conversion rate of the SCR catalyst. In this method, a conditioning phase (67) for setting a specifiable operating point (68) is carried out before the superstoichiometric metering (69) of reducing agents.

Abstract: An apparatus is provided for generating mercury (II) sulfide from elemental mercury. Elemental mercury is injected into a heated and sealed reaction vessel containing vaporized sulfur. The elemental mercury reacts with at least a portion of the vaporized sulfur to form the mercury (II) sulfide within the reaction vessel. The formed mercury (II) sulfide is then unloaded from the reaction vessel.

Abstract: Catalyzed soot filters comprising a wall flow monolith having a washcoat comprising an alkali base metal composite disposed on the monolith. Methods of manufacturing and using catalyzed soot filters and diesel engine exhaust emission treatment systems are also disclosed.

Abstract: A device includes an injector for a liquid having at least one pressure sensor, preferably an integrated pressure sensor. The device is used, in particular, for adding liquid reducing agent to an exhaust gas line of a motor vehicle. A configuration having the device and methods of using the device and the configuration are also provided.

Abstract: A method for injecting ammonia into an exhaust gas stream downstream of a diesel engine includes providing an exhaust gas passageway (11) from the diesel engine to an ambient (14). The exhaust gas passageway (11) includes an NOx Slip Catalyst (NSC) 20 downstream of an NOx Particulate Filter (NPF) 18. The method includes emitting exhaust gas (EG) through the exhaust gas passageway (11), and selectively injecting ammonia (NH3) upstream of the NPF 18, upstream of the NSC (20), both upstream of the NPF and the NSC, or not injecting ammonia, depending on the temperature of the exhaust gas at the NPF and at the NSC.

Abstract: A method for operating an exhaust gas treatment device having at least one reservoir for a reducing agent and at least one delivery device for a reducing agent, includes at least checking a filling level of the at least one reservoir, checking a current exhaust gas mass flow, and delivering reducing agent if the filling level of the at least one reservoir is below a minimum filling level and the exhaust gas mass flow is in a low-load range. A motor vehicle having the exhaust gas treatment device is also provided.

Abstract: A device, method of making, and method of using, illustratively wherein a container includes an inlet and an outlet; a catalytic converter intermediate in a path between the inlet and the outlet; at least one surface arranged to ensure at least a majority of gas received from the inlet traverses a first portion of the path from the inlet to the catalytic converter and communicates heat from the catalytic converter to the container; and an optical means arranged to transport visible light, emitted from the catalytic converter during reduction of the smog-generating chemical in the gas, to a location outside the container to indicate whether the catalytic converter is functioning properly.

Abstract: A device for the purification of a polluted gas, for example an exhaust gas from a diesel or gasoline engine, comprising, in combination: A honeycomb structure, comprising at least one porous electron-conductive material forming the walls (1) of said structure and an electrochemical system for treating said gas, comprising a layer (7) of an ionically conductive and electronically insulating material D, a reduction catalyst A (9) for reducing the polluting species of the NOx type and an oxidation catalyst B (4) for oxidizing the polluting species of the soot, hydrocarbon HC, CO or H2 type, said electrochemical system being configured in the form of an electrode W and a counterelectrode CE; and means for applying a voltage or a current between said electrode W and said counterelectrode CE.

Abstract: An exhaust gas purification apparatus for an engine is provided with a filter arranged in an exhaust passage of the engine, and a regeneration control unit for regenerating the filter by burning the particulate matters accumulated in the filter. The control unit may include an over-accumulation state determination unit and a switch. The over-accumulation state determination unit determines over-accumulation of the particulate filter in the filter when the particulate matter is over-accumulated in the filter. The switch switches a regeneration temperature for regenerating the filter between a first regeneration temperature at which a normal regeneration is performed and a second regeneration temperature which is lower than the first regeneration temperature. The control unit is connectable to a command unit when the particular matter is over-accumulated in the filter, so that the switch is forcibly operated toward the second regeneration temperature.

Abstract: An engine exhaust gas purification device comprising control unit having successively arranged switching device (1), counter-current heat exchanger (3) and at least one exhaust gas purification component (2). The switching device (1) has a first position where a flow path (6) of the exhaust gas to the exhaust gas purification component (2) is opened and a second position where a flow path (6) of the exhaust gas to the exhaust gas purification component (2) is blocked and the exhaust gas flows along a further flow path (7) where the exhaust gas is heated and conveyed, via a flow path (20) of the exhaust gas purification component (2), and exits the exhaust gas purification unit (5) through outlet channels (4) of the counter-current heat exchanger (3). The switching device, the exhaust gas purification component, the counter-current heat exchanger and the flow paths are integrated in a compact exhaust gas treatment unit.

Abstract: An arrangement for controlling injection of a reducing agent in an exhaust line of a combustion engine (1): An injection system (8-12) injects the reducing agent into the exhaust line (3). A first catalyst (13) reduces the amount of nitrogen oxides in the exhaust gases in the exhaust line (3) using the reducing agent. A second catalyst (14) downstream of the first catalyst (13) in the exhaust line (3) converts ammonia in the exhaust gases to nitrogen gas and nitrous oxide. A nitrous oxide sensor (17) monitors the amount of nitrous oxide in the exhaust line (3) downstream of the second catalyst (14). A control unit (10) of the injection system (8-12) adjusts the amount (q) of reducing agent injected into the exhaust line (3) if the sensor (17) detects that the amount of nitrous oxide is not within a selected range (A).

Abstract: The present invention relates to an organotemplate-free synthetic process for the production of a zeolitic material having a BEA framework structure comprising YO2 and optionally comprising X2O3, wherein said process comprises the steps of (1) preparing a mixture comprising seed crystals and at least one source for YO2; and (2) crystallizing the mixture; wherein Y is a tetravalent element, and X is a trivalent element, wherein the zeolitic material optionally comprises at least one alkali metal M, wherein when the BEA framework additionally comprises X2O3, the mixture according to step (1) comprises at least one source for X2O3, and wherein the seed crystals comprise zeolitic material having a BEA framework structure, preferably zeolite Beta.

Abstract: An exhaust gas after-treatment system includes at least first and second substrates. The first substrate has a first region and a second region circumferentially surrounding the first region. The first region of the first substrate has a higher average cell density than the average cell density of the second substrate. The system can also include at least a third substrate.

Abstract: The present invention consists of an absorption process with a chemical reaction to capture acid gases such as carbon dioxide, sulphur dioxide and nitrogen dioxide from the ambient air and from combustion gases from burners and internal combustion engines using fossil fuels; the aim of the invention being the acquisition of carbon credits in accordance with the “Kyoto protocol on climate change”. The process is carried out in a horizontal spray absorber using an 8% solution of sodium hydroxide as absorption liquid, obtaining sodium carbonate, sodium sulphite, sodium nitrite and nitrate as byproducts. These byproducts are converted into commercial products such as calcium carbonate, barium sulphate and ammonium nitrate; for which purpose both the sodium sulphite and the sodium nitrite must previously be converted into sodium sulphate and nitrate by means of an oxidizing agent.

Abstract: A method for controlling a selective catalytic reduction system (SCR) exploiting a set of predetermined trigger events (101) and a set point for the NOx concentration (102). At the occurrence of a trigger event (104), NOx concentration measurement downstream from the catalyst elements (2) is started (105) and the difference between the measured concentration and the set point is determined (106). If the difference is negative, the dosing of the reducing agent is decreased (107) and a new trigger event is waited for (103). If the difference is positive, the dosing of the reducing agent is increased (108). After system stabilization (109), anew measurement is started (110) and the concentration is compared to the result of the previous measurement (111). If the measured value is below the previous measured value, the same dosing is maintained (112). If the measured value is above the previous measured value, the dosing is decreased with an amount greater than the increase after the previous measurement (113).

Abstract: A SCR catalyst system, comprising a first SCR catalyst (1) and a second SCR catalyst (2) which is disposed in the exhaust gas tract downstream of the first SCR catalyst (1). At least one metering device (12) for metering in a reducing agent solution is disposed in the exhaust gas tract upstream of a first SCR catalysis element (13) of said first SCR catalyst (1). The SCR catalyst system does not require a device for metering a reducing agent solution into a second SCR catalysis element (21) of the second SCR catalyst (2).

Abstract: Systems and methods are disclosed that include an exhaust gas stream produced by an engine and an aftertreatment system including an SCR catalyst element receiving at least a portion of the exhaust gas stream. An exhaust outlet flow path has an inlet fluidly coupled to the exhaust gas stream at a position downstream of at least a portion of the SCR catalyst element that bypasses at least a portion of exhaust gas stream to provide for compositional measurement of the exhaust gas with a compositional sensor located downstream of a diagnostic catalyst positioned in the exhaust outlet flow path.

Abstract: Utilizing the finding that the state of adsorption of NH3 on a selective reduction type NOx catalyst includes a weakly adsorbed state in which the adsorbed NH3 is useful for a reduction reaction of NOx and a strongly adsorbed state in which the adsorbed NH3 is not useful for the reduction reaction of NOx unless the state of adsorption is changed into the weakly adsorbed state, the apparatus of the invention includes an actual weakly-adsorbed amount-calculation NH3 that is adsorbed on the selective reduction type NOx catalyst in the weakly adsorbed state, and a dispensation control portion that performs a dispensation control of the reductant dispensed by a reductant-dispensation portion, according to the actual weakly adsorbed amount calculated by the actual weakly adsorbed amount calculation portion.

Abstract: Systems and method are disclosed in which a portion of an exhaust gas stream is received into an exhaust outlet flow path downstream of a first selective catalytic reduction (SCR) catalyst and upstream of a second SCR catalyst. The removed portion is treated with a diagnostic SCR catalyst element and an NH3 concentration composition of the treated removed portion is determined. The NH3 concentration is used to control injection of reductant upstream of the first SCR catalyst.

Abstract: The present disclosure relates to a method for controlling an injection device for feeding an ammonia-releasing reducing agent into an exhaust-gas purification system of an internal combustion engine for the purpose of reducing the nitrogen oxide emissions, wherein the exhaust-gas purification system comprises at least one SCR catalytic converter with n cells which are arranged in series in the exhaust-gas throughflow direction and in which ammonia can be stored.

Abstract: Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to aluminum ratio from about 0.25:1 to about 1:1.

Abstract: Embodiments for injecting reducing agents are provided. In one example, an injection device for feeding reducing agents into an exhaust-gas purification system of an internal combustion engine for reduction of nitrogen oxide emissions comprises an injector, and an evaporation device for evaporating first and second reducing agents, the injection device connected to in each case one storage vessel for the first reducing agent and a storage vessel for the second reducing agent, the first and second reducing agents liquid at room temperature.

Abstract: An exhaust gas conversion system includes an oxide catalyst, a filter, a selective catalytic reduction catalyst and an ammonia supplying device. The filter has a honeycomb structural body including a honeycomb unit. The selective catalytic reduction catalyst has a honeycomb structural body including a honeycomb unit. The oxide catalyst, the filter and the selective catalytic reduction catalyst are sequentially arranged in a direction in which an exhaust gas flows. A ratio of an area of a cross section of the selective catalytic reduction catalyst perpendicular to a longitudinal direction of the selective catalytic reduction catalyst with respect to an area of a cross section of the filter perpendicular to a longitudinal direction of the filter is approximately 0.55 or more and approximately 0.90 or less. The area of the cross section of the filter is approximately 300 cm2 or more and approximately 1000 cm2 or less.

Abstract: The present invention relates to a process for the preparation of a zeolitic material having a structure comprising YO2 and optionally comprising X2O3, preferably comprising YO2 and X2O3, wherein said process comprises the steps of (1) providing a mixture comprising one or more ammonium compounds of which the ammonium cation has the formula (I): [R1R2NR3R4]+??(I) and further comprising one or more sources for YO2 and one or more sources for X2O3; (2) crystallizing the mixture provided in (1); wherein Y is a tetravalent element, and X is a trivalent element, and wherein in formula (I) R1 and R2 are independently from one another derivatized or underivatized methyl, and R3 and R4 are independently from one another derivatized or underivatized (C3-C5)alkyl, and wherein the molar ratio of ammonium cation having the formula (I) to Y in the mixture provided in step (1) and crystallized in step (2) is equal to or greater than 0.25.

Abstract: A method of injecting a reagent into a stream of exhaust output from an engine to change the composition of the exhaust includes obtaining a target reagent injection rate. A calculation period is set to a time greater than one second. The target injection rate is multiplied by the time of the calculation period to determine an amount of reagent to be injected during the calculation period. An injection duty cycle is set. An injection duration is determined to inject the determined amount of reagent based on the injection duty cycle. The reagent is injected at the duty cycle for the injection duration.

Abstract: A technique that, in an exhaust gas purification apparatus of an internal combustion engine, can avoid a decrease in a NOx purification rate by adding a reducing agent as continuously as possible, while avoiding NH3 from passing through a selective reduction type NOx catalyst to a downstream side thereof. The selective reduction type NOx catalyst has an active spot which purifies NOx by the use of NH3, and an adsorption site which adsorbs NH3, wherein a vicinity site, which is located in the vicinity of the active spot, and a distant site, which is located distant from the active spot, exist in the adsorption site. The addition of the reducing agent from the reducing agent addition part is controlled based on the desorption rate of NH3 in the vicinity site so as to continue to cause the NH3 adsorbed to the vicinity site to exist.

Abstract: An exhaust gas after-treatment system includes at least first and second substrates. The first substrate has a first region and a second region circumferentially surrounding the first region. The first region of the first substrate has a higher average cell density than the average cell density of the second substrate. The system can also include at least a third substrate.

Abstract: An exhaust gas post treatment system for, in particular, a self-igniting internal combustion engine including a catalytic converter that is arranged in an exhaust gas line, a fine particle filter and an introduction device for a reduction agent arranged upstream of the catalytic converter in the direction of the flow of the exhaust gas, and to a method for operating said type of exhaust gas post treatment system. An exhaust gas post treatment system and a method for operating said type of system that is simple to use and compact. This is achieved by virtue of the fact that the catalytic converter is a reductively or oxidatively operated catalytic converter, or that the introduction device, the catalytic converter, that can be operated reductively or oxidatively, and the fine particle filter are arranged in said sequence and in the exhaust line in the direction of flow.

Abstract: The invention relates generally to molecular sieve SSZ-28 and its use in the reduction of oxides of nitrogen in a gas stream such as the exhaust from an internal combustion engine.

Abstract: The invention relates generally to molecular sieve SSZ-25 and its use in the reduction of oxides of nitrogen in a gas stream such as the exhaust from an internal combustion engine.

Abstract: The invention relates generally to molecular sieve SSZ-23 and its use in the reduction of oxides of nitrogen in a gas stream such as the exhaust from an internal combustion engine.

Abstract: A catalytic converter apparatus for use in an exhaust system of an internal combustion engine includes a housing having a gas inlet and a gas outlet, and at least one catalytic substrate element disposed in the housing. The at least one substrate element is divided into a plurality of zones or sections, the zones at least partially separated from one another to inhibit heat flow. The zones can be at least partially separated with walls. The walls can include insulating material for reducing the mobility of heat radially outwardly. Each of the zones defines a generally separate flow passage connecting the inlet and outlet in fluid communication. The apparatus can heat more rapidly from a cold start compared with conventional catalytic converters.

Abstract: A mixture of urea, water and ammonium carbamate is formulated for use in the catalytic reduction of oxides of nitrogen in diesel exhaust. The mixtures may be formulated to optimize the amount of reductant in the mixture and the freezing point of the formulation. These formulations are especially useful in combination with Selective Catalytic Reduction systems and are well suited for use on heavy-duty trucks and heavy duty equipment used off-road. Some of these formations include between about 15.0 wt. % to about 40.0 wt. % urea; between about 15.0 wt. % to about 40.0 wt. % ammonium carbamate; and between about 40.0 wt. % to about 60.0 wt. % water. The formulation may be monitored for ammonia content and/or freezing point and the composition of the formulation may be adjusted to optimize the freezing point and ammonia content.

Abstract: The present invention relates to a method for exhaust gas after-treatment for essentially lean-burn internal combustion engines and also a corresponding advantageous exhaust gas after-treatment system. In particular, the present invention relates to reducing the proportion of the greenhouse gas N20 in the total exhaust gas from a corresponding internal combustion system using at least one NOx storage catalyst as exhaust gas purification element. The objective of the invention is to operate the N20 depletion catalyst located downstream of the NOx storage catalyst under lambda=<1 conditions when the N20 formed by the NOx storage catalyst reaches the N20 depletion catalyst.

Abstract: The invention relates to systems and methods for heating a solid or liquid reducing material such as an urea-containing material for NOx selective catalytic reduction (‘SCR’) using a heat stored in a thermal energy storage material, such as a phase change material. The stored heat may be heat from an exhaust waste, such as from an exhaust gas of an internal combustion engine. The reducing material may be a solid reducing material. Other reducing materials include aqueous solutions such as an aqueous solution containing, consisting essentially of, or consisting of urea and water. In one aspect, the process may include a step of evaporating an aqueous solution of urea for immediate urea hydrolysis.

Abstract: A NOx selective reduction catalyst for reducing NOx by the ammonia adsorbed is disposed in an engine exhaust gas passage. As states of adsorption of ammonia by the catalyst, there are a first adsorption state of ammonia that occurs when the ammonia is adsorbed during low temperature and a second adsorption state of ammonia that occurs when the ammonia is adsorbed or has already been adsorbed during high temperature. The amount of adsorbed ammonia in the first state is restricted to control concentration of the ammonia that is in the first state and desorbed when the temperature of the catalyst increases so as to be not higher than an allowable concentration, and that in the second state is restricted to control concentration of the ammonia that is in the second state and desorbed when the temperature of the catalyst increases so as to be not higher than an allowable concentration.

Abstract: An exhaust gas aftertreatment installment and associated exhaust gas aftertreatment method utilizes a nitrogen oxide storage catalytic converter and an SCR catalytic converter. A particulate filter is provided upstream of the nitrogen oxide storage catalytic converter or between the latter and the SCR catalytic converter or downstream of the SCR catalytic converter. The time of regeneration operating phases of the nitrogen oxide storage catalytic converter can be determined as a function of the nitrogen oxide content of the exhaust gas downstream of the nitrogen oxide storage catalytic converter or of the SCR catalytic converter and/or as a function of the ammonia loading of the latter. Moreover, a desired ammonia generation quantity can be determined for a respective regeneration operating phase. The installation and method are adopted for use for motor vehicle internal combustion engines and other engines which are operated predominantly in lean-burn mode.

Abstract: Systems and methods are provided for reducing NOx emissions from a vehicle including an engine having an exhaust. In one example, the system comprises a NOx reducing system coupled to the engine exhaust including a base metal zeolite, said NOx reducing system including a first layer with a first pore size and a second layer with a second pore size, said first pore size being smaller than said second pore size.