A NO.sub.x trap catalyst is disclosed. The NO.sub.x trap catalyst comprises a noble metal, a NO.sub.x storage component, a support, and a first ceria-containing material. The first ceria-containing material is pre-aged prior to incorporation into the NOx trap catalyst, and may have a surface area of less than 80 m.sup.2/g. The invention also includes exhaust systems comprising the NO.sub.x trap catalyst, and a method for treating exhaust gas utilizing the NO.sub.x trap catalyst.

An engine system comprising an internal combustion engine operated by a fuel and lubricated by a lubrication oil comprising at least one additive that renders ash formed by combustion of the lubrication oil ammonia-soluble ash; an exhaust gas system for cleaning an exhaust gas flow from the internal combustion engine , the exhaust gas system comprising a diesel particulate filter to capture particulate matter from the exhaust gases, wherein the particulate matter comprises the ammonia-soluble ash; an exhaust gas conduit to lead exhaust gases from the internal combustion engine through the exhaust gas system; and an injection device to add a solvent comprising ammonia or an ammonia-forming compound into the exhaust gas flow upstream of the diesel particulate filter, wherein the exhaust gas conduit collects the solvent and lead the solvent through the diesel particulate filter, thereby dissolving and thus removing the ammonia-soluble ash from the diesel particulate filter.

Systems and methods to determine the pressure differential for selective catalytic reduction systems includes a first sensor coupled to an inlet of a selective catalytic reduction system, a second sensor coupled to an outlet of the selective catalytic reduction system, and a controller communicatively coupled to the selective catalytic reduction system. The controller is configured to interpret a first parameter indicative of a first pressure amount of the selective catalytic reduction system measured by the first sensor, interpret a secondary parameter indicative of a secondary pressure amount of the selective catalytic reduction system measured by the second sensor, determine a plurality of operating parameters based, at least in part, on the interpretation of the first parameter and the secondary parameter, and generate a selective catalytic reduction command based, at least in part, on the determination of the plurality of operating parameters.

Selective catalytic reduction filter (SCRF) devices and systems incorporating the same are provided. Systems can include an exhaust gas source, an exhaust gas conduit capable of receiving an exhaust gas stream from the exhaust gas source, and an SCRF device in fluid communication therewith. The SCRF device can include a filter, a selective catalytic reduction (SCR) catalyst disposed on at least portion of the filter, and a NO.sub.x storage coating on at least a portion of the filter. The NO.sub.x storage coating can include one or more of palladium, barium, or cerium. The NO.sub.x storage coating can be biased towards the upstream side of the filter. The NO.sub.x storage coating can overlap a portion of the SCR catalyst. The system can further include a water-absorbing alkali oxide. The water-absorbing alkali oxide can be disposed within the SCRF device, the exhaust gas conduit, or in an upstream oxidation catalyst device.

Provided are emissions treatment systems for an exhaust stream having an ammonia-generating component, such as a NOx storage reduction (NSR) catalyst or a lean NOx trap (LNT) catalyst, and an SCR catalyst disposed downstream of the ammonia-generating catalyst. The SCR catalyst can be a molecular sieve having the CHA crystal structure, for example SSZ-13 or SAPO-34, which can be ion-exchanged with copper. The LNT can be layered, having an undercoat washcoat layer comprising a support material, at least one precious metal, and at least one NOx sorbent selected from the group consisting of alkaline earth elements, rare earth elements, and combinations thereof and a top washcoat layer comprising a support material, at least one precious metal, and ceria in particulate form, the top washcoat layer being substantially free of alkaline earth components. The emissions treatment system is advantageously used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines.

Systems, apparatus and methods are provided for reducing reductant consumption in an exhaust aftertreatment system that includes a first SCR device and a downstream second SCR device, a first reductant injector upstream of the first SCR device, and a second reductant injector between the first and second SCR devices. NOx conversion occurs with reductant injection by the first reductant injector to the first SCR device in a first temperature range and with reductant injection by the second reductant injector to the second SCR device when the temperature of the first SCR device is above a reductant oxidation conversion threshold.

An exhaust gas purification material according to the present invention is provided with a particulate filter 10 that traps particulate matter in exhaust gas and contains an SCR catalyst for adsorbing ammonia and reducing NOx in the exhaust gas. A maximum allowable adsorption amount of ammonia adsorbable by the filter 10 differs between an upstream portion 10a of the filter 10 including an exhaust gas inlet-side end 10c, and a downstream portion 10b of the filter 10 including an exhaust gas outlet-side end 10d. The SCR catalyst contained in the upstream portion 10a and the SCR catalyst contained in the downstream portion 10b are qualitatively different. A ratio (B/A) of a maximum allowable adsorption amount of ammonia A in the upstream portion 10a and a maximum allowable adsorption amount of ammonia B in the downstream portion 10b satisfies the relationship 1.1(B/A)2.

A method for controlling regeneration a catalyst by an exhaust gas purification device includes: measuring a temperature of exhaust gas flowing into a first catalyst unit; estimating a NO.sub.x amount loaded into the first catalyst unit and a slip amount of NO.sub.x of the first catalyst unit by using the temperature and an amount of the exhaust gas of the first catalyst unit; calculating a temperature of a second catalyst unit by using the temperature of the first catalyst unit; and estimating a NO.sub.x amount flowing into the second catalyst unit by using at least one of the slip amount of NO.sub.x of the first catalyst unit and the temperature of the second catalyst unit.

Zoned diesel oxidation catalysts containing a higher precious metal loading in the inlet zone that the outlet zone and an equal or shorter length inlet zone are described. Emission treatment systems and methods of remediating nitrogen oxides (NOx), particulate matter, and gaseous hydrocarbons using zoned diesel oxidation catalysts are also described.

Zoned diesel oxidation catalysts containing a higher precious metal loading in the inlet zone that the outlet zone and an equal or shorter length inlet zone are described. Emission treatment systems and methods of remediating nitrogen oxides (NOx), particulate matter, and gaseous hydrocarbons using zoned diesel oxidation catalysts are also described.