157 results about "NOx adsorber" patented technology

A NOx abatement system comprising: a first NOx adsorber (18) capable of being disposed in-line and downstream of and in fluid communication with an engine (12); a selective catalytic reduction catalyst (20) disposed in-line and downstream of and in direct fluid communication with the first NOx adsorber (18), wherein the selective catalytic reduction catalyst (20) is capable of storing ammonia; and an off-line reformer (24) disposed in selective communication with and upstream of the first NOx adsorber (18) and the selective catalytic reduction catalyst (20), wherein the reformer (24) is capable of producing a reformate comprising primarily hydrogen and carbon monoxide.

The invention provides a controller and cylinder deactivation system to regenerate an exhaust aftertreatment device for a multicylinder engine that operates primarily at an air/fuel ratio that is lean of stoichiometry. The invention uses the cylinder deactivation system to control temperature and air/fuel ratio of an exhaust gas feedstream going into an aftertreatment device. The invention also increases the amount of fuel delivered to each non-deactivated cylinder by an amount sufficient to maintain operating power of the engine. The regeneration action includes desorbing NOx from a NOx adsorber catalyst, desulfating the NOx adsorber catalyst, and purging a diesel particulate trap.

A catalyst article comprises an SCR catalyst and a NOx adsorber catalyst, where each of these catalysts comprise a metal molecular sieve, each with a different metal. The catalyst article can be close coupled with other components to give a NO_X performance advantage from cold start to a combined DOC and SCRF system. Higher NO_X conversion is also shown in under-floor location due to NOx storage before SCR light off and selective NH₃ slip control, allowing higher NH3 fill levels. Systems comprising the catalyst article and methods of using the catalyst article to give improved hydrocarbon and carbon monoxide control, as well as ammonia slip control, are described. The systems can include flow-through or wall-flow monoliths.

A passive NO_x adsorber is disclosed. The passive NO_x adsorber is effective to adsorb NO_x at or below a low temperature and release the adsorbed NO_x at temperatures above the low temperature. The passive NO_x adsorber comprises a noble metal and a small pore molecular sieve. The small pore molecular sieve has a maximum ring size of eight tetrahedral atoms. The invention also includes an exhaust system comprising the passive NO_x adsorber, and a method for treating exhaust gas from an internal combustion engine utilizing the passive NO_x adsorber.

An oxidation catalyst for treating an exhaust gas from a diesel engine and an exhaust system comprising the oxidation catalyst are described. The oxidation catalyst comprises: a first washcoat region for adsorbing NO_x, wherein the first washcoat region comprises a zeolite catalyst, wherein the zeolite catalyst comprises a noble metal and a zeolite; a second washcoat region for oxidising nitric oxide (NO), wherein the second washcoat region comprises platinum (Pt) and a support material; and a substrate having an inlet end and an outlet end.

Partial denitrations are made practical by an SCR catalyst placed downstream of a NOx adsorber. The SCR catalyst permits partial denitrations to be extended to where a favorable fuel penalty rate presented by driving conditions can be utilized to a sufficient extent that the benefit of the favorable conditions is not offset by the increased start-up fuel penalty associated with conducting opportunistic partial denitrations. Regenerations, including both denitration and desulfations, can be initiated selectively based on a fuel penalty calculation. Examples of such calculations lead to methods in which opportunistic regenerations are based on low oxygen concentrations, condition existing while shifting gears, and throttling events for a diesel engine with a throttled air supply. The methods flexibly take advantage of driving conditions to reduce fuel penalties associated with regenerations. In one embodiment, driving conditions include future conditions predicted based on GPS and map data.

The invention relates to the modification technology of natural zeolite material and aims to provide a nitrogen oxide adsorbent prepared through ion exchange modification of the natural zeolite. The adsorbent is prepared through the following step: adding the natural zeolite after dealumnization processing and ammonium exchange processing into metal salt aqueous solution to be subjected to metal ion exchange; and washing, drying and then roasting at the high temperature of 300-600 DEG C for 1-5 hours to obtain the nitrogen oxide adsorbent of modified natural zeolite containing corresponding metal elements, wherein the metal salt is any one of hydrochloride, nitrate, sulfate or oxalate of Na, Ca, K, Ba, Ti, Mn, Ni or Cu. The nitrogen oxide adsorbent prepared through modification of the natural zeolite can be used as an environment function material for adsorbing and purifying the industrial tail gas, flue gas and automobile exhaust containing nitrogen oxide. The nitrogen oxide adsorbent is low in production cost and large in adsorption quantity, and has a broad market prospect as the environment function material.

An exhaust gas treatment system for an internal combustion engine is provided, and includes an exhaust gas conduit, an upstream selective catalytic reduction (“SCR”) device, an electrically heated catalyst (“EHC”) device, an oxidation catalyst (“OC”) device, a downstream SCR device, and a control module. The EHC device is in fluid communication with the exhaust gas conduit and is configured to receive the exhaust gas. The EHC device is located downstream of the upstream SCR device and is selectively activated to produce heat. The OC device is in fluid communication with the exhaust gas conduit, and is selectively heated by the EHC device. At least one of the EHC device and the OC device have a NO_x adsorber catalyst disposed thereon for selectively adsorbing NO_x below a threshold temperature and substantially releasing NO_x above the threshold temperature.

The present invention provides for an NOx adsorber aftertreatment system for internal combustion engines which utilizes a parallel arrangement of an adsorber catalyst and a bypass. The exhaust flow from the engine is routed through the adsorber during lean operation. At a predetermined regeneration time (for example, when the adsorber catalyst is 20% full), the exhaust gas flow is reduced through the parallel leg that contains the adsorber catalyst to be regenerated (e.g., 20% through the catalyst leg, 80% of the flow to the bypass leg). A quantity of hydrocarbon is injected into the reduced-flow catalyst leg in order to make the mixture rich. Since the flow has been reduced in this leg, only a small fraction of the amount of hydrocarbon that would have been required to make the mixture rich during full flow is required. This will result in a substantial reduction in the fuel penalty incurred for regeneration of the adsorber catalyst. Once the leg has been regenerated, the exhaust flow is switched to flow 100% through the adsorber leg.

The invention provides a NOx adsorber aftertreatment system for internal combustion engines which utilizes at least one precat operatively coupled to at least one NOx adsorber to aid in the regeneration of the NOx adsorber. Fuel is injected into a precat located upstream of a NOx absorber producing heat, H₂O, and reductants such as CO, HC, and volatile hydrocarbons, which are input into the NOx absorber. The combination of heat, water, and reductants help to efficiently regenerate the NOx Adsorber which in turn releases exhausts products such as CO₂ and N₂. Regeneration of a NOx adsorber can be performed during periods of reduced exhaust gas flow lowering the fuel penalty associated with NOx adsorber regeneration. The pre-cat, NOx adsorber regenerating aftertreatment system of the present invention may be used with any suitable control system.

An active system for regenerating a NO_X adsorber and a particulate filter, the system comprising a fuel source, a reformer for generating hydrogen and carbon monoxide in fluid communication with the fuel source, a first valve, a second valve, and a third valve in fluid communication with the reformer, an oxidation catalyst, a NO_X adsorber located downstream from the oxidation catalyst, a particulate filter located downstream from the NO_X adsorber; and wherein the first valve, the second valve, and the third valve control fluid flow from the reformer to the oxidation catalyst, the NO_X adsorber, and the particulate filter.

In one embodiment, the method for operating an exhaust system can comprise determining a stream temperature of an exhaust stream, and desulfating the NOx adsorber. Desulfating the NOx adsorber can comprise determining an amount of oxygen needed to increase an initial temperature of a NOx adsorber to a desulfation temperature of greater than or equal to about 600° C., producing reformate comprising hydrogen and carbon monoxide in an on-board reformer, introducing the amount of oxygen to the NOx adsorber, and introducing a sufficient amount of reformate to the NOx adsorber to attain an air to fuel ratio that is less than a combustion stoichiometric A/F ratio.

In an exhaust aftertreatment system comprising a NOx adsorber-catalyst followed by an SCR catalyst, means are provided for preventing the SCR catalyst from becoming heated to near the same peak temperatures as the NOx adsorber-catalyst during desulfation. In one embodiment, the means is a thermal mass between the NOx adsorber-catalyst and the SCR catalyst. In another embodiment, the means is a valve configured to selectively divert exhaust leaving the NOx adsorber-catalyst from the SCR catalyst. In a method of the invention, the NOx adsorber-catalyst temperature is cycled during desulfation. The peaks of the cycles are within an appropriate temperature range for desulfating the NOx adsorber-catalyst, but the average temperature is below the temperature range at which the SCR catalyst is damaged. The temperature peaks are damped as they travel from the NOx adsorber-catalyst to the SCR, whereby the SCR experiences much lower peak temperatures than the NOx adsorber-catalyst.

A method and system for passively regenerating particulate filters, catalyze soot filters and NOx adsorber catalysts for a vehicle having a compression ignition engine having an engine control module (ECM) including an integrated engine and emission system map, and an integrated starter/alternator/flywheel/retarder assembly, comprising sensing the condition of the particulate filters, catalyzed soot filters, and NOx adsorber catalysts and generating an initiate cleaning cycle signal upon sensing that the filters and catalysts require cleaning, monitoring operation of the engine and vehicle to determine the engine speed and vehicle speed and generating an engine speed/vehicle speed operating signal, receiving the initiate passive cleaning engine cycle signal and the engine speed vehicle speed operating signal, and initiating engine control parameter adjustments to modify engine operation to promote passive regeneration of the filters.