Disclosed is a method for diagnosing a first exhaust treatment component for treatment of an exhaust gas stream comprising means for oxidizing nitric oxide into nitrogen dioxide. A first reduction catalytic converter is arranged upstream said means for oxidizing nitric oxide into nitrogen dioxide, and a second reduction catalytic converter is arranged downstream said means. A reagent is for reduction of nitrogen oxides in said first catalytic converter, and a first sensor measures an occurrence of nitrogen oxide downstream said means but upstream said second reduction catalytic converter. The method comprises: causing a supply of reagent upstream said first reduction catalytic converter to an extent exceeding the extent to which reagent is consumed by the first reduction catalytic converter, determining a first measure of the occurrence of reagent downstream said means for oxidizing, and diagnosing said means for oxidizing nitric oxide into nitrogen dioxide based on said first measure.

Disclosed is a method for diagnosing a first exhaust treatment component for treatment of an exhaust gas stream comprising means for oxidizing nitric oxide into nitrogen dioxide. A first reduction catalytic converter is arranged upstream said means for oxidizing nitric oxide into nitrogen dioxide, and a second reduction catalytic converter is arranged downstream said means. A reagent is for reduction of nitrogen oxides in said first catalytic converter, and a first sensor measures an occurrence of nitrogen oxide downstream said means but upstream said second reduction catalytic converter. The method comprises: causing a supply of reagent upstream said first reduction catalytic converter to an extent exceeding the extent to which reagent is consumed by the first reduction catalytic converter, determining a first measure of the occurrence of reagent downstream said means for oxidizing, and diagnosing said means for oxidizing nitric oxide into nitrogen dioxide based on said first measure.

To provide a reducer supply device that can be made compact and has excellent maintainability. The reducer supply device includes a nozzle unit that adjusts a flow rate of a reducer which is to be supplied to a NOx purification catalyst device; and a pump unit that supplies the reducer to the nozzle unit. The nozzle unit and the pump unit are arranged at positions offset from each other in top view.

A method and system for mitigating a urea deposit within an SCR system that includes determining a mass of an accumulated urea deposit present within the SCR catalyst and SCR piping, comparing the mass of the accumulated urea deposit with a deposit upper threshold limit, and initiating an SCR regeneration event when the mass of the accumulated urea deposit is greater than the deposit upper threshold limit. The method further includes determining an amount of NH.sub.3 passing through the SCR catalyst downstream of the urea deposit, comparing the amount of NH.sub.3 passing through the SCR catalyst with an NH.sub.3 regeneration threshold limit, and terminating the SCR regeneration event when the level of NH.sub.3 passing through the SCR catalyst is less than the SCR NH.sub.3 regeneration threshold.

Provided is a catalyst carrier module for a large-capacity catalyst reactor, which can be assembled in a large-capacity structure by laminating a flat plate and a wave plate to be fixed in a can without brazing the flat plate and the wave plate constituting a cell forming body, for use in a catalytic reactor requiring a large-capacity exhaust gas treatment. The catalyst carrier module (or block) includes: a can of a rectangular tube shape having an inlet and an outlet; at least one cell forming body in which a plurality of hollow cells are formed by alternately laminating a wave plate and a flat plate which are coated with a catalyst on a surface thereof and inserted into the can; and a fixing unit installed at the inlet and the outlet of the can to prevent the at least one cell forming body from detaching from the can.

Described are SCR catalyst systems comprising a first SCR catalyst composition and a second SCR catalyst composition arranged in the system, the first SCR catalyst composition promoting higher N.sub.2 formation and lower N.sub.2O formation than the second SCR catalyst composition, and the second SCR catalyst composition having a different composition than the first SCR catalyst composition, the second SCR catalyst composition promoting lower N.sub.2 formation and higher N.sub.2O formation than the first SCR catalyst composition. The SCR catalyst systems are useful in methods and systems to catalyze the reduction of nitrogen oxides in the presence of a reductant.

A method and system for mitigating a urea deposit within an SCR system that includes determining a mass of an accumulated urea deposit present within the SCR catalyst and SCR piping, comparing the mass of the accumulated urea deposit with a deposit upper threshold limit, and initiating an SCR regeneration event when the mass of the accumulated urea deposit is greater than the deposit upper threshold limit. The method further includes determining an amount of NH.sub.3 passing through the SCR catalyst downstream of the urea deposit, comparing the amount of NH.sub.3 passing through the SCR catalyst with an NH.sub.3 regeneration threshold limit, and terminating the SCR regeneration event when the level of NH.sub.3 passing through the SCR catalyst is less than the SCR NH.sub.3 regeneration threshold.

Provided is a catalyst carrier module for a large-capacity catalyst reactor, which can be assembled in a large-capacity structure by laminating a flat plate and a wave plate to be fixed in a can without brazing the flat plate and the wave plate constituting a cell forming body, for use in a catalytic reactor requiring a large-capacity exhaust gas treatment. The catalyst carrier module (or block) includes: a can of a rectangular tube shape having an inlet and an outlet; at least one cell forming body in which a plurality of hollow cells are formed by alternately laminating a wave plate and a flat plate which are coated with a catalyst on a surface thereof and inserted into the can; and a fixing unit installed at the inlet and the outlet of the can to prevent the at least one cell forming body from detaching from the can.

A nitrous oxide (N.sub.2O) removal catalyst composite is described, which includes: a N.sub.2O removal catalytic material on a carrier, wherein the catalytic material comprises a platinum group metal (PGM) component on a ceria-containing support having a single phase, cubic fluorite crystal structure. The catalytic material is effective to decompose nitrous oxide (N.sub.2O) to nitrogen (N.sub.2) and oxygen (O.sub.2) and/or to reduce N.sub.2O to N.sub.2 and water (H.sub.2O) and/or (CO.sub.2) under conditions of an exhaust stream of an internal combustion engine operating under conditions that are stoichiometric or lean with periodic rich transient excursions. Methods of making and using the same are also provided.

A method and system for mitigating a urea deposit within an SCR system that includes determining a mass of an accumulated urea deposit present within the SCR catalyst and SCR piping, comparing the mass of the accumulated urea deposit with a deposit upper threshold limit, and initiating an SCR regeneration event when the mass of the accumulated urea deposit is greater than the deposit upper threshold limit. The method further includes determining an amount of NH.sub.3 passing through the SCR catalyst downstream of the urea deposit, comparing the amount of NH.sub.3 passing through the SCR catalyst with an NH.sub.3 regeneration threshold limit, and terminating the SCR regeneration event when the level of NH.sub.3 passing through the SCR catalyst is less than the SCR NH.sub.3 regeneration threshold.