An internal combustion engine, with an engine regulating device and an exhaust gas aftertreatment device with an SCR catalytic converter for the reduction of at least one NO.sub.x component, and with a catalytic converter regulating device, wherein the engine regulating device is prescribed a target value for an NO.sub.x mean value of the NO.sub.x component of the exhaust gases, which mean value results at an outlet point of the exhaust gas aftertreatment device in relation to a predefinable time period, and the engine regulating device is configured at least in one operating mode to continuously calculate an NO.sub.x reference value for the catalytic converter regulating device with consideration of No.sub.x components which have already been emitted and the predefined target value, which reference value is selected in such a way that the predefined target value results at the outlet point of the exhaust gas aftertreatment device at the end of the predefinable time period when the calculated NO.sub.x reference value of the catalytic converter regulating device is fed as NO.sub.x setpoint value to the regulating means.

A method for ascertaining an exhaust gas composition of an exhaust gas of an internal combustion engine with regard to an ammonia fraction and a nitrogen oxides fraction in an exhaust gas system including an SCR catalytic converter. The method includes detecting, using a sensor, a first signal whose magnitude is a function of the nitrogen oxides fraction of the exhaust gas upstream from the SCR catalytic converter, detecting using a sensor a second signal whose magnitude is a function of the ammonia fraction and the nitrogen oxides fraction of the exhaust gas downstream from the SCR catalytic converter, storing the two signals over an observation period, and ascertaining the ammonia fraction and optionally the nitrogen oxides fraction of the exhaust gas downstream from the at least one SCR catalytic converter using a calculation rule that uses the two signals during the observation period as input variables.

A method of treating exhaust gas from an internal combustion engine as the exhaust gas passes through an exhaust gas pathway includes injecting reductant into the exhaust gas pathway with a reductant injector, filtering particulate matter from the exhaust gas with a first treatment element located downstream of the reductant injector, oxidizing soot on the first treatment element with ozone, and converting nitrogen oxides (NOx) from the exhaust gas with a second treatment element located downstream of the reductant injector.

A method for monitoring a gas sensor (14) which comprises two electrochemical measuring cells (20, 30) and which is arranged in an exhaust tract (10) of an internal combustion engine (11), wherein the sensor elements (20, 30) exhibit a substantially identical sensitivity towards a first gas component and a different sensitivity towards a second gas component and are insensitive towards further gas components. In an operating state in which an exhaust gas stream at the gas sensor (14) contains less of the second gas component than of the first gas component a concentration of the first gas component is calculated from each of the sensor signals from the sensor elements (20, 30) and a defect in a sensor element (20, 30) is deduced from the concentrations of the first gas component.

Methods and systems for improving NOx conversion efficiency of a selective catalytic reduction catalyst are described. In one example, an amount of NH.sub.3 stored in a SCR is adjusted after stopping an engine so that a desired amount of NH.sub.3 may be stored within the SCR when the engine is restarted.

The present invention relates to an apparatus for reducing greenhouse gas emission in a vessel and a vessel including the same, which are capable of constantly maintaining a concentration of a greenhouse gas absorbing liquid to prevent a decrease in absorption performance of an absorption tower, and applying a pressurization system to prevent the loss of an absorbent liquid due to the natural evaporation of a high-concentration absorbent liquid. Or which are capable of cooling exhaust gas with fresh water by a heat exchange method, thereby preventing a decrease in concentration of an absorbent liquid, and controlling the concentration of the absorbent liquid to constantly maintain the concentration of the absorbing liquid, thereby preventing a decrease in absorption performance.

The present invention relates to a composition comprising platinum supported on titanium oxide, the platinum particles having an average particle diameter of 50-200 nm. The composition has a surprisingly low light-off temperature for the ammonia oxidation and a high selectivity for oxidation to N2.

A method of treating exhaust gas from an internal combustion engine as the exhaust gas passes through an exhaust gas pathway includes injecting reductant into the exhaust gas pathway with a reductant injector, filtering particulate matter from the exhaust gas with a first treatment element located downstream of the reductant injector, oxidizing soot on the first treatment element with ozone, and converting nitrogen oxides (NOx) from the exhaust gas with a second treatment element located downstream of the reductant injector.

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.

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.