The present disclosure provides catalyst compositions capable of reducing nitrogen oxide (NO.sub.x) emissions in engine exhaust. The catalyst compositions include metal ion-exchanged zeolites having a domain size of less than about 1500 Ångstroms (Å), a crystallographic strain of less than about 0.7%, or both. Further provided are catalyst articles coated with such compositions, processes for preparing such catalyst compositions and articles, an exhaust gas treatment system including such catalytic articles, and methods for reducing NO.sub.x in an exhaust gas stream using such catalytic articles and systems.

The present invention relates to a catalyst for the selective catalytic reduction of nitrogen oxide, the catalyst comprising a first coating comprising a 12-membered ring pore zeolitic material comprising a first metal which is one or more of copper and iron, and a second coating comprising an 8-membered ring pore zeolitic material comprising a second metal which is one or more of copper and iron.

This disclosure features a urea conversion catalyst located within a urea decomposition reactor (e.g., a urea decomposition pipe) of a diesel exhaust aftertreatment system. The urea conversion catalyst includes a refractory metal oxide and a cationic dopant. The urea conversion catalyst can decrease the temperature at which urea converts to ammonia, can increase the urea conversion yield, and can decrease the likelihood of incomplete urea conversion.

A system for treating engine exhaust gas, which engine exhaust gas has a temperature of between T1 and T2, comprises a SCR reactor for converting NOx in a medium containing the engine exhaust gas into N2 and H2O. The SCR reactor has an inlet for receiving the medium and an outlet for outputting the NOx reduced medium. A first boiler unit has an outlet for outputting boiler exhaust gas (temperature greater than T3, T3>T1) from the first boiler unit. A mixing unit mixes the engine exhaust gas with the boiler exhaust gas to produce the medium. The mixing unit has a first inlet communicating with the engine for receiving the engine exhaust gas, a second inlet communicating with the outlet of the first boiler unit for receiving the boiler exhaust gas and an outlet for outputting the medium. The mixing unit outlet communicates with the inlet of the SCR reactor.

A partitioning wall is provided in a fluid space formed between a cover member and a body member, which surrounds a forward end of a fluid injection valve. The partitioning wall divides the fluid space into an inlet-side fluid space and an outlet-side fluid space in a circumferential direction of the fluid injection valve. A forward-end space, which is formed at a bottom of the fluid space, is communicated to the inlet-side and the outlet-side fluid spaces, so that cooling water flows from the inlet-side fluid space to the outlet-side fluid space through the forward-end space. The cooling water circulates in the forward-end space surrounding the forward end of the fluid injection valve to effectively cool down the fluid injection valve.

An aftertreatment system comprises a housing having an inlet, an outlet and a sidewall. The housing defines an internal volume structured to receive an exhaust gas via the inlet. The sidewall defines an access opening. An access panel is operatively coupled to the sidewall and covers the access opening. The access panel defines a plurality of throughholes. Each of the plurality of throughholes are configured to receive a fastener therethrough for removably coupling the access panel to the sidewall. An injection port is also defined in the access panel. An injector is positioned on the access panel. The injector is removably coupled to the access panel via a coupling assembly so that the injector is in fluidic communication with the internal volume via the injection port. A SCR system is disposed in the internal volume and includes at least one catalyst formulated to decompose constituents of the exhaust gas.

The boiler (1) has side tubed walls (2) enclosing an inner space (3) and a device for selective non catalytic reduction (7). The device for selective non catalytic reduction (7) has a lance (8) carrying a hose (9) having at least a nozzle (10) and a hose drive mechanism (11) for driving the hose within the lance. The lance (8) protrudes into the inner space (3) from a side tubed wall (2) of the boiler (1).

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.

A pressure-releasing breather hose 1 mounted on a urea water tank 2 is dividably constituted by a flexible joint portion 1a with an end capable of being fitted over a hose joint 3 on the tank 2, and a vertical portion 1b connected to the other end of the joint portion 1a and suspending downward along a side surface of the tank 2. The joint and vertical portions 1a and 1b are constituted by a rubber hose made of ethylene propylene diene terpolymer (EPDM) and a polyethylene pipe (resin pipe) made of high density polyethylene (HDPE), respectively.

An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NO.sub.x trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction catalyst. The modified LNT comprises a first layer and a second layer. The first layer comprises a NO.sub.x adsorbent component and one or more platinum group metals. The second layer comprises a diesel oxidation catalyst zone and an NO oxidation zone. The diesel oxidation catalyst zone comprises a platinum group metal, a zeolite, and optionally an alkaline earth metal. The NO oxidation zone comprises a platinum group metal and a carrier. The modified LNT stores NO.sub.x at temperatures below about 200° C. and releases at temperatures above about 200° C. The modified LNT and a method of using the modified LNT are also disclosed.