An exhaust system includes a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst, and an ammonia slip catalyst. The SCR catalyst is configured to reduce nitrogen oxide in exhaust gas produced by a diesel engine. The diesel oxidation catalyst is configured to reduce particulate matter, hydrocarbon, and carbon monoxide in the exhaust gas. The diesel oxidation catalyst is disposed downstream of the first SCR catalyst. The ammonia slip catalyst is configured to reduce ammonia in the exhaust gas. The ammonia slip catalyst is disposed downstream of the first SCR catalyst and upstream of the first diesel oxidation catalyst.

An exhaust gas purifying system for an engine includes a three-way catalyst, a particulate filter, an ammonia sorbent unit, an exhaust gas purifying catalyst unit, and a gas injection component including an oxygen-containing gas, all coupled to an exhaust line. Methods for purifying exhaust gas from an engine include exposing the exhaust gas to a three-way catalyst and a particulate filter, thus generating ammonia. The ammonia may be stored in an ammonia sorbent unit during a cold start condition. An oxygen-containing gas may be injected into the exhaust line. Once the ammonia sorbent has reached a desorption temperature, the ammonia may be released into the exhaust line and exposed to an exhaust gas purifying catalyst unit. The exhaust gas purifying catalyst partially oxidizes the ammonia to nitrous oxides (NOx) and subsequently catalyzes a reaction between the remaining ammonia and the nitrous oxides to give nitrogen gas and water.

A method for diagnosing an exhaust component in an exhaust passage for an internal combustion engine of a vehicle. In the method, operating parameters of the internal combustion engine are monitored and recorded by a control unit while the internal combustion engine is running. If a predefined emission threshold for the exhaust component for compliance with emissions is found to have been exceeded, the current operating parameters of the internal combustion engine are stored in a control unit. The operating state of the internal combustion engine when the predefined emission threshold is exceeded is reproduced on a vehicle test bench using the stored operating parameters. The diagnosis of the exhaust component is carried out based on a comparison between the current measured value from the exhaust component and the current measured value from an emission measuring device and/or the predefined emission threshold.

A method of calculating a nitrogen oxide (NOx) mass reduced from a lean NOx trap (LNT) during regeneration includes calculating a C3H6 mass flow used to reduce the NOx among a C3H6 mass flow flowing into the LNT of an exhaust purification device, calculating a NH3 mass flow used to reduce the NOx among a NH3 mass flow generated in the LNT, calculating a reduced NOx mass flow based on the C3H6 mass flow used to reduce the NOx and the NH3 mass flow used to reduce the NOx, and calculating the reduced NOx mass by integrating the reduced NOx mass flow over a regeneration period.

Systems are provided including a selective catalytic reduction catalyst structured to receive first exhaust gas from a first fuel source of a dual fuel engine system and second exhaust gas from a second fuel source of the dual fuel engine system, a first fuel of the first fuel source differing from a second fuel of the second fuel source, an ammonia slip catalyst positioned downstream of the selective catalytic reduction catalyst to receive a flow of exhaust gases from the selective catalytic reduction catalyst without an intervening catalyst, and an oxidation catalyst positioned downstream of the ammonia slip catalyst to receive the flow of exhaust gases from the ammonia slip catalyst without an intervening catalyst.

An improved NO.sub.x sensor with an NH.sub.3 oxidation catalyst. A sensor module may include a support component, a NO.sub.x sensing material positioned on the support component, and an NH.sub.3 oxidation catalyst. The NH.sub.3 oxidation catalyst may be layered on top of the NO.sub.x sensing material or the NH.sub.3 oxidation catalyst may be positioned upstream of the NO.sub.x sensing material such that the NH.sub.3 oxidation catalyst selectively converts NH.sub.3 to N.sub.2 while permitting NO.sub.x through to the NO.sub.x sensing material.

An exhaust system includes a diesel oxidation catalyst (DOC) device mounted to an exhaust pipe for exhausting an exhaust gas of an engine and purifying hydrocarbon (HC) and carbon monoxide (CO) among the exhaust gas, an urea injector positioned at a rear of the diesel oxidation catalyst device for injecting an urea aqueous solution to an inside of the exhaust pipe, a mixer positioned at the rear of the urea injector, a diesel particulate matter filter (DPF) positioned at the rear of the mixer and coated with a catalyst devoid of a noble metal or a hydrolysis catalyst that does not oxidize ammonia and hydrolyzes the injected urea to reduce a particulate material of the exhaust gas, and a selective catalytic reduction (SCR) device positioned at the rear of the diesel particulate matter filter.

An internal combustion engine has an exhaust gas aftertreatment system comprising in the given order in the flow direction of the exhaust gas: a device for metering ammonia and/or a compound that can be decomposed to form ammonia into the exhaust gas to be cleaned, as a reducing agent; one or more SCR catalysts, which form a first SCR unit; one or more SCR and/or ammonia oxidation and/or ammonia slip catalysts, which form a second SCR unit; and a NO.sub.x sensor in the exhaust gas tail pipe. An amount, to be metered into the exhaust gas, of ammonia and/or of the decomposable compound is set using the nitrogen oxide concentration in the exhaust gas tail pipe that is determined by the NO.sub.x sensor, and the occurrence or non-occurrence of an ammonia excess in the region of the NO.sub.x sensor can be determined from the sensor signal of the NO.sub.x sensor by evaluating said sensor signal.

A catalyst article having an extruded support having a plurality of channels through which exhaust gas flows during operation of an engine, and a single layer coating or a bi-layer coating on the support, where the extruded support contains a third SCR catalyst, the single layer coating and the bilayer-coating contain platinum on a support with low ammonia storage and a first SCR catalyst. The catalytic articles are useful for selective catalytic reduction (SCR) of NOx in exhaust gases and in reducing the amount of ammonia slip. Methods for producing such articles are described. Methods of using the catalytic articles in an SCR process, where the amount of ammonia slip is reduced, are also described.

Disclosed is a gas sensor element having an electrode containing a first metal as a predominant component and a lead containing a second metal as a predominant component. The electrode and the lead are connected directly at a connection boundary thereof, or connected indirectly via a connection joint. The connection boundary or joint includes a component region where either one of the first and second metals lower in specific gravity than the other of the first and second metals is contained in an amount ranging between those in the electrode and the lead.