160 results about "NOx adsorber" patented technology

The invention relates to systems for removing NOx from exhaust. In one aspect of the invention, after adsorption, an NOx adsorber is isolated from the main exhaust flow and desorption induced by raising the temperature. The desorbed NOx is combined with a reductant and reduced over a catalyst. Preferably, the reductant is syn gas produced in an on-board reformer. The catalyst need never be exposed to the main exhaust flow, which is particularly advantageous for catalysts sensitive to water, oxygen, or sulfur. In another aspect of the invention, a recirculating flow is induced through an NOx adsorber during a regeneration cycle. Recirculation can induce greater desorption at a given temperature, provide a source of heat for the adsorber, and allow a higher conversion rate with a fixed amount of catalyst. A further aspect of the invention relates to a vehicle-mounted adsorbers with provisions for heating.

An exhaust system can comprise a NOx adsorber, a reformer disposed upstream of a NOx adsorber and in fluid communication with a fuel source, a first valve for controlling the introduction of the fluid to an exhaust conduit; and a particulate filter disposed upstream and in fluid communication with the NOx adsorber and downstream an in fluid communication with the reformer such that the first valve controls introduction of fluid to the exhaust conduit upstream of the particulate filter. The reformer can be designed to generate a fluid comprising sufficient thermal energy, hydrogen, and carbon monoxide. Optionally, the particulate filter can be designed to be regenerated by the thermal energy and to adsorb a sufficient amount of the thermal energy to reduce the temperature of a gas stream comprising the fluid from a first temperature of about 600° C. to about 1,000° C. to a second temperature of less than or equal to about 500° C.

A NOX abatement system includes a first NOX adsorber capable of being disposed in-line and downstream of and in fluid communication with an engine. The NOX abatement system further includes a selective catalytic reduction catalyst disposed in-line and downstream of, and in direct fluid communication with, the first NOX adsorber. The selective catalytic reduction catalyst is capable of storing ammonia. An off-line reformer is disposed in selective communication with and upstream of the first NOX adsorber and the selective catalytic reduction catalyst. The reformer is capable of producing a reformate that includes primarily hydrogen and carbon monoxide.

In a method of regenerating a NOx adsorber, the NOx adsorber is used to treat exhaust gases created during the combustion of gaseous fuels in general. Methane is introduced into a reformer or exhaust line in which hydrogen generated during reforming is used to regenerate the NOx absorber.

New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

One aspect of the invention relates an exhaust treatment system having an SCR reactor following a NOx adsorber. Syn gas is used to regenerate the NOx adsorber. Another aspect relates to an LNT / SCR provided with an ammonia source separate from the LNT. A further aspect relates to a system comprising first and second LNTs and one or more SCRs downstream of the LNTs. A still further aspect relates to a device comprising first and second NOx adsorbers contained in a single housing. Another aspect relates to coating a surface of a moving part in an exhaust system with an oxidation catalyst to mitigate fouling. Additional aspects of the invention relate to strategies for controlling one or more of the time to initiate a regeneration cycle, the time to terminate a regeneration cycle, and the reductant injection rate during regeneration of LNT / SCR exhaust treatment systems.

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.

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.

The lean NOx trap catalyst composition of the present invention comprises distinct layers, or zone configuration or multi-brick arrangement. The top layer, front zone or front brick is free of any alkali or alkaline earth NOx trapping components. The under layer, rear zone or rear brick may contain any desirable NOx trapping component in contact with a precious metals group catalyst (e.g., Pt). Catalysts of this invention show wide temperature operation window with superior low temperature performance.

The invention provides a NOx adsorber aftertreatment system for internal combustion engines which utilizes a plasma fuel converter operatively coupled to at least one NOx adsorber to aid in the regeneration of the NOx adsorber. Fuel and engine exhaust is injected into a plasma fuel converter upstream of a NOx absorber producing reductant such as H2, and CO, which are inlet into the NOx absorber. Reductants such as H2 and CO acting along and together help to efficiently regenerate the NOx Adsorber which in turn releases exhausts products such as CO2 and N2. Using the reductants generated by the plasma fuel converter NOx adsorbers, catalytic soot filter, and the like can be regenerated at exhaust temperatures less than 250° C. The plasma fuel converter, NOx adsorber regenerating aftertreatment system of the present invention may be used with any suitable control system.