FR3030618A1 - METHOD FOR MANAGING A METHANE OXIDATION CATALYST AND EXHAUST GAS POST-TREATMENT SYSTEM FOR ITS IMPLEMENTATION - Google Patents

Abstract

A method of managing a methane oxidation catalyst (13) installed in an exhaust aftertreatment system of an internal combustion engine (10). A process characterized in that to increase the activity of the methane oxidation catalyst (13) is exposed to a gas composition acting reactively on the methane oxidation catalyst.

Description

Field of the Invention The present invention relates to a method of managing a methane oxidation catalyst installed in the aftertreatment system of the exhaust gases of an internal combustion engine. The invention also relates to an exhaust gas after-treatment system implementing such a method. State of the art There are known internal combustion engines (also called thermal engines) which operate with a gas containing methane, for example natural gas or methane or a mixture of gas and another fuel for example gas oil . Pure gas engines often derive from gasoline engines or diesel engines and in general the allogeneic ignition to ignite the gas / air mixture is done with spark plugs. In such gas / diesel engines, the engine derives in principle a diesel engine that is suitable both for pure diesel engine operation or mixed operation with diesel and gas. Part of the calorific capacity of the gas oil is then ensured by that of the gas.

The ignition of all the fuel, that is to say the air / gas-gas mixture is via the fuel portion. Gas substitution rates for gas are up to 70%. All proposals that are generally based in part on the combustion of gas containing methane create a difficulty because of the high methane emissions by the engine running in the raw state. Above all for reasons of climate protection, it is necessary to reduce methane emissions as part of the aftertreatment of exhaust gases. Methane oxidation catalysts (also known as MOC catalysts) are known for this, which oxidize the methane contained in the exhaust gases by means of a formulation rich in palladium. For this purpose it is possible to use compositions which have a weight ratio of palladium (Pd) to platinum (Pt) up to, for example, 7: 1 or more. Other methane oxidation catalysts apply only palladium compositions, such as for example Pd / aluminum oxide. In general, with such compositions, it is only above 400 ° C. that a certain transformation of methane is observed. For total oxidation, it is often necessary to have temperatures well above 500 ° C. In a known manner, methane oxidation catalysts, in particular palladium-rich methane oxidation catalysts, are extremely sensitive to sulfur and are ready after a very short operating time. But they exhibit a very notable deterioration of their oxidation action for gas containing sulfur or gas oil. Even in the absence of sulfur in the lean exhaust gases, palladium-rich catalysts, and especially compositions using palladium alone, show a very substantial decrease in their methane oxidation activity (see, for example, M. Lyubovsky, M. and Pfefferle, L. Catalysis Today 47 (1999), pp. 29-44). It is also known that palladium-rich catalysts exhibit oscillatory behavior (see R. Schwidernoch, University of Heidelberg 2005). DE 11 2011 104 327 T5 relates to an exhaust gas system equipped with a diesel oxidation catalyst. Upstream of this oxidation catalyst, a fuel injector is used to inject bursts of fuel directly into the exhaust pipe. The contact of the injected hydrocarbons with the oxide layer of the diesel oxidation catalyst achieves a regeneration effect. DESCRIPTION AND ADVANTAGES OF THE INVENTION The subject of the present invention is a process for the management of a methane oxidation catalyst installed in an exhaust gas after-treatment system of an internal combustion engine, this method being characterized in that to increase the activity of the methane oxidation catalyst, it is exposed to a gas composition acting reactively on the methane oxidation catalyst. In other words, according to the invention, the methane oxidation catalyst is exposed to a reactivation gas composition of the methane oxidation catalyst. This makes it possible to increase the activity of the catalyst. This means decreases the deterioration of the loss of oxidation activity of a methane oxidation catalyst during its operating time or completely avoids such a loss of activity. This ensures that even for a prolonged operating time, the methane oxidation catalyst retains sufficient methane oxidation activity which ensures an optimum aftertreatment of the exhaust gas with respect to the oxidation of the methane. methane. According to a particularly advantageous characteristic, the method according to the invention applies to a system for aftertreatment of the exhaust gases of internal combustion engines which mainly produce lean exhaust gases and which burn at least a part of the methane. , that is to say in particular gas engines or diesel / gas engines. Specifically, such engines or combustion machines generally produce high methane emissions from the engine and must be reduced in the aftertreatment system exhaust. The machine operating mode with an excess of air, that is to say for> 1 (lean mode) generally does not allow optimum operation of the methane oxidation catalyst because generally does not reach the high temperatures necessary for the oxidation of methane. This is why it is particularly advantageous to act against such a negative deactivation of the methane oxidation catalyst. The process according to the invention allows it to expose the methane oxidation catalyst to a reactivation gas composition. In a particularly advantageous manner, the methane oxidation catalyst is periodically exposed to the reactivating gas composition. This makes it possible, in particular, to predict that, after a certain period of time, a lean mode of operation of the methane oxidation catalyst, and for a certain period of time, in particular for a short period of time further described hereinafter in greater detail, it is exposed to the composition of the reaction gas. The term "periodic" means that the gaseous reaction-effect composition is preferably repeated regularly in that the reactivation-effect gas composition is generated after each lean mode of operation phase or each time after a defined period of time. a lean operation phase of the internal combustion engine. The duration of the lean, regular operating mode of the internal combustion engine before the reactivation according to the invention of the methane oxidation catalyst can be variable. The reactivation of the methane oxidation catalyst according to the process of the invention is done regularly but also on demand.

The reactivation gas composition acts in particular by reducing or oxidizing effect on the composition or the material of the methane oxidation catalyst. This makes it possible to reduce at least partially, for example the palladium oxide present in the catalyst, to return to palladium metal, which makes it possible to significantly increase the oxidation activity of the oxidation catalyst. During the operating period of the methane oxidation catalyst thus equipped, particularly in the lean mode of the internal combustion engine, palladium oxide is developed. This palladium oxide may be on the surface of the corresponding noble metal particles of a methane oxidation catalyst or also in the raw material of the palladium of the methane oxidation catalyst. This development of palladium oxide is reversed by the gas composition generated in particular periodically and reactively acting in the exhaust gas conduit.

According to a first principle development of the method of the invention, the reactive gas composition is generated by a rich mode operating mode of the internal combustion engine and in this development of the method of the invention, the composition of the gas has a reducing effect. The rich mode is preferably run for a short time and periodically repeated. For example, after a lean operating mode of the internal combustion engine and which can last for minutes or hours, the methane oxidation catalyst is exposed for a few seconds to a rich exhaust gas composition, functioning overall as a reducing agent. ; this composition of the exhaust gas is obtained in the engine by a rich mode of operation, in short. The rich mode of operation can be applied for example for a duration of about 5 to 60 seconds. The rich operating mode in the motor can be carried out particularly in the context of a accumulation of rich mode times by switching rich mode / lean mode and for example the rich mode will be maintained for about 10 seconds to switch again over a period also limited to a few seconds of lean operating mode. This lean mode / rich mode switching will sometimes be executed so that the sum, for example, the accumulated rich mode protection time duration, may be up to 60 seconds. This mode of operation has the advantage that the polluting emissions (in particular hydrocarbons and carbon monoxide) are not very important downstream of the catalyst and / or that the temperatures are not too high. The rich operating mode inside the engine can be obtained for example by a late post-injection with diesel fuel as internal means to the engine. According to another development of principle of the process of the invention, the reactivating gas composition is injected by the injection of fuel into the aftertreatment system of the exhaust gases, that is to say directly in the exhaust pipe. In particular, the fuel is injected upstream of the methane oxidation catalyst and this injection is directly upstream of the methane oxidation catalyst or even further upstream.

This principle development of the process is particularly advantageous in internal combustion engine systems that are not designed for temperature constraints specific to a rich operating mode. This concerns, for example, gas engines derived from diesel engines. In such engines or internal combustion engines, a rich, short operating mode could possibly result in excessive stress, including temperature constraints, applied to the engine components, for example the turbocharger. To avoid damage to the engine components by high temperatures, it is advantageous to produce the reactive gas composition of the metal oxidation catalyst by injecting fuel into the gas after-treatment system. exhaust. For the implementation of the process, for this development of the process, one or more fuel injectors are required in the exhaust gas line.

In order to generate a reactive gas composition, it is generally sufficient for fuel to be injected into the exhaust line only at a very short interval after the lean mode operation of the internal combustion engine.

A few milliseconds for the fuel injection time may be sufficient, for example a time between 20 and 500 ms. If, for example, the injection frequency is of the order of about 1 Hz or less, the fuel injection time of a few seconds is advantageous. The fuel injection according to the method of the invention is preferably in the phases in which the temperature of the exhaust gas is greater than about 350 ° C. This means has the advantage that for such relatively high temperatures ensure that the fuel to be injected will be completely vaporized and will not produce a local fouling of the catalyst.

Fuel injection directly into the exhaust gas duct is advantageously carried out in a multi-step process; first, the oxygen mass flow rate of the exhaust gas is reduced by means applied to the engine before injecting the fuel into the aftertreatment system of the exhaust gas. These engine-specific means for reducing the mass flow rate of oxygen may consist, for example, in throttling the fuel supply or in reducing the Lambda coefficient. In order to burn off the residual oxygen contained in the exhaust gas, the fuel upstream of the methane oxidation catalyst is then sufficiently dosed to have a clean, reducing composition of the exhaust gases in the region of the oxidation catalyst. methane. According to another development of the process of the invention, the composition of the reactivation-effect exhaust gas is also generated by the injection of fuel into the aftertreatment system of the exhaust gases. The injection of fuel into the exhaust pipe is, however, to reach temperatures of 700 ° C or more, or even higher than 800 ° C. These high temperatures are preferably maintained for a few minutes, for example between 2 and 10 minutes. At such high temperatures at which the methane oxidation catalyst is for example exposed for a few minutes, the palladium oxide which has developed during lean mode operation in the methane oxidation catalyst is partially decomposed into metal palladium, which then significantly increases the oxidation activity of the methane oxidation catalyst. Preferably in this development, sufficient fuel is metered upstream of the methane oxidation catalyst so that always up to lean conditions resulting from the combustion of a portion of the residual fuel in the methane oxidation catalyst, temperatures above 700 ° C or above 800 ° C are reached. It is then always lean mode conditions which generally have an oxidizing effect so that the methane oxidation catalyst can again function in its state of activation catalyst. These high temperatures are maintained for a few minutes in the methane oxidation catalyst, for example for a period of between 1 and 10 minutes. It is particularly advantageous in this development of the process that the very high temperatures in the methane oxidation catalyst evacuate a large part of the sulfur accumulated where appropriate in the methane oxidation catalyst in the form of sulfur oxides. This effect also allows a regeneration effect of the methane oxidation catalyst. According to a development of the process, by fuel injection in the exhaust gas pipe, temperatures of 700 ° C or more are achieved which establish lean, clean conditions (oxidizing conditions). According to another development of the process in the context set above, by a rich mode internal to the engine or by the injection of fuel into the exhaust gas duct, clearly reducing conditions are established, sufficient to reactivate the catalyst of the engine. methane oxidation at generally substantially lower, sufficient temperatures of from about 350 ° C to 500 ° C. The fuel metered directly into the exhaust pipe is for example the same fuel used for the operation of the internal combustion engine. In the case of gas engines, pure it is for example natural gas. However, particularly preferably, at least a portion of liquid fuel is injected into the exhaust gas duct as part of the process of the invention, for example gas oil or gasoline or a mixture of a fuel liquid and a fuel in the gaseous state. This also applies to pure gas engines. This solution has the advantage that by injecting at least a fraction of fuel in the liquid state, the ease of reaction of this fuel mixture is generally greater than that of the pure gas because the methane contained in this gas is generally very reactive. In the case of a pure gas engine designed to inject diesel fuel into the combustion chamber to ensure ignition, it is also possible, for example, to inject this gas oil into the exhaust gas duct and to use the process of the invention. 'invention.

Alternatively, one can also use gasoline. In the case of pure gas engines in which it is not intended to inject liquid fuel for the operation of the internal combustion engine, there is provided an additional tank containing liquid fuel which will be dosed in the gas line of exhaust in the context of the process of the invention, that is to say for example a fuel tank or gas oil associated with the aftertreatment system exhaust gas. In mixed engines or gas engines with gasoil ignition, diesel is preferably used for fuel injection downstream of the engine in the exhaust gas line. The use of gas oil for this purpose is particularly advantageous in general because the ignition temperature of the gas oil in the methane oxidation catalyst is at about 300 ° C. and the temperature is thus significantly lower than the temperature. ignition of the methane oxidation catalyst for operation with methane (this temperature is between about 450 and 550 ° C). The invention also relates to an exhaust gas post-treatment system for an internal combustion engine, this system having at least one methane oxidation catalyst. According to the invention, fuel is injected upstream of this methane oxidation catalyst. This system is particularly suitable for carrying out the process described above with brief periodic fuel injections in the exhaust gas pipe of the methane oxidation catalyst for a reactivating gas composition producing regenerating or increasing the activity of the methane oxidation catalyst. This overcomes a deterioration in the activity of the methane oxidation catalyst. As a catalyst for the oxidation of methane, a catalyst whose palladium constitutes the main component of the composition is preferably used. This composition will have for example a mass part of palladium which dominates and a subordinate part of platinum and / or rhodium. As a support material for the methane oxidation catalyst, a ceramic, for example aluminum oxide or mixed oxides such as, for example, barium titanate, is particularly advantageously used. The methane oxidation catalyst may also have a composition with only palladium. According to a particularly preferred development, the methane oxidation catalyst contains at least one material that accumulates oxygen, in particular zirconium oxide and / or lantane oxide and / or a ceroxide and / or a praseodymium oxide and / or a neodymium oxide or mixtures thereof. The oxygen-accumulating material corresponds in particular to zirconium oxides and / or lantane oxides and / or ceroxides and / or praseodymium oxides and / or neodymium oxides or mixtures thereof. The accumulation of oxygen in the methane oxidation catalyst by such materials reduces or prevents the passage of hydrocarbons over the methane oxidation catalyst. Thus, the use of such a methane oxidation catalyst is particularly advantageous if, according to the process of the invention, fuel is injected upstream, especially directly upstream of the methane oxidation catalyst in the process. exhaust gas conduit and thus establishes a composition of the exhaust gas globally rich, that is to say, reducing effect periodically applied to the methane oxidation catalyst. According to another development of the exhaust aftertreatment system of the invention, the system comprises in particular a reservoir for liquid fuel, especially gasoline or gasoline. The reservoir then supplies the liquid fuel intended for injecting the fuel downstream of the engine into the exhaust gas duct according to a preferential development of the process of the invention. Such a reservoir is particularly advantageous in systems of pure gas engines in which there is no injection of gat, for example in the combustion chamber of the internal combustion engine, to ensure 'ignition. According to another development of the exhaust aftertreatment system of the invention, the system comprises a sulfur adsorption plant. This sulfur adsorption plant may be upstream of the methane oxidation catalyst. Alternatively, it is also possible to integrate the sulfur adsorption plant into the methane oxidation catalyst. The sulfur adsorption plant functions as a sulfur trap to avoid deterioration of the effectiveness of the palladium containing methane oxidation catalyst by the sulfur contained in the exhaust gas. The sulfur adsorption plant may be a sulfur oxide adsorption plant, preferably a sulfur oxide storage facility. The material for the sulfur oxide storage plant is, for example, based on magnesium-spinel aluminates. The formulation of the sulfur adsorption plant may also be based on the usual composition of a nitrogen oxide storage catalyst. The process according to the invention as well as the aftertreatment system of the exhaust gas is particularly suitable for pure gas engines or for diesel / gas engines which operate at least from time to time with an excess of air , that is to say for A> 1, and which burn at least partly methane-containing gas or a gas mixture containing methane and for example gas oil (mixed fuel). In addition to gas or diesel / gas engines, or capable of operating in lean mode, the method according to the invention and the aftertreatment system of the exhaust gases according to the invention are in principle also suitable for other internal combustion, for example for usual diesel engines, to ensure the aftertreatment of the exhaust gases. The subject of the invention is also a computer program for implementing this method as well as a machine readable medium containing the computer program and also an electronic control device for carrying out the method. of the invention. The implementation of the method according to the invention as a computer program or as a control program has the advantage of being able to carry out the method according to the invention in a simple manner by applying it even to existing systems, for example motor vehicles. , as long as the system is equipped with the corresponding components in the aftertreatment system. Drawings The present invention will be described hereinafter in more detail with the aid of exemplary embodiments of the invention shown in the accompanying drawings in which: FIG. 1 is a schematic representation of the components of a system of the exhaust gas after-treatment according to the invention applied to an internal combustion engine, FIG. 2 is a schematic representation of the components of another embodiment of an exhaust aftertreatment system. according to the invention, FIG. 3 is a schematic representation of the components of another embodiment of an exhaust aftertreatment system according to the invention, and FIG. 4 is a schematic representation of the components of another embodiment of an exhaust aftertreatment system according to the invention. DESCRIPTION OF EXEMPLARY EMBODIMENTS FIG. 1 schematically shows a device formed of components of an exhaust gas after-treatment system according to the invention in the exhaust gas duct of an internal combustion engine 10. The internal combustion engine 10 is in particular a gas engine likely to operate in lean mode or a diesel / gas engine operating with a mixture of gas and gas oil.

To increase the power of the internal combustion engine 10, a turbocharger 11 is associated with it. The exhaust gas of the internal combustion engine 10 first arrives in the exhaust gas pipe through a sulfur adsorption plant 12. Downstream of the sulfur adsorption plant 12, a catalyst Methane oxidation 13 oxidizes the methane contained in the exhaust gas. The sulfur adsorption plant 12 upstream prevents the efficiency of the oxidation of methane from being impaired by the sulfur-containing components in the exhaust gas. The system further comprises an SCR catalyst 16 for reducing the mass fraction of the nitrogen oxides contained in the exhaust gas. The reactive agent required for the catalytic reaction in the SCR catalyst 16 is, for example, an aqueous urea solution which is injected into the exhaust gas line at the metering point upstream of the SCR catalyst 16. This system example The aftertreatment of the exhaust gas further comprises a catalytic particle filter 14 installed upstream of the SCR catalyst 16. Upstream of the methane oxidation catalyst 13 and at the same time upstream of the plant. sulfur adsorption 13, there is a fuel injector 17. The injector 17 periodically injects fuel directly into the exhaust pipe according to the method of the invention. These fuel injections create in the region of the methane oxidation catalyst 103 conditions for reactivation or regeneration of the methane oxidation catalyst 13. In particular, a reducing or oxidizing gas composition is produced which By reducing or decomposing the palladium oxide which has developed during the operation of the methane oxidation catalyst 13, the oxidizing activity of the methane oxidation catalyst 13 is thereby restored. fuel injector and generating the reactivation gas composition in the region of the methane oxidation catalyst by means internal to the engine. The periodic establishment, that is to say, repeated reactivation gas composition can however be done every few minutes after a few minutes of a lean mode of operation. For the reactivation gas composition, it is possible in particular to use a net reducing gas composition, that is to say slightly rich (À <1) while being close to 1, so as to maintain the catalyst for oxidizing methane in a partially reducing state and thus activating the catalyst. In general, it is sufficient to have an exhaust gas composition that is rich, clearly reducing for a few seconds. The fuel injection necessary for this purpose in the exhaust gas duct may last, for example, a few milliseconds, for example in the range between 20 and 500 ms. The duration of the lean-phase mode of operation, i.e., the normal mode of operation of the system may depend on the degree of oxidative deactivation of the methane oxidation catalyst. The duration of the lean phase is for example of the order of a few minutes up to a few hours. For the regeneration of the methane oxidation catalyst by means internal to the engine, that is to say by a short operation in the rich mode of the internal combustion engine, the lean phase time may have a longer period if necessary. long. Short periods which are of interest, especially for regeneration from fuel injection in the exhaust pipe, have the advantage that the average methane oxidation efficiency of the methane oxidation catalyst is ultimately superior to that of the variant with longer periods.

According to a development of the method of the invention, the fuel injection is to arrive periodically after a lean period, by fuel injection in the exhaust gas pipe, at very high temperatures in the oxidation catalyst. methane 13, that is to say in particular temperatures above 700 ° C or above 800 ° C. These high temperatures are preferably maintained for a few minutes and the palladium oxide formed in the methane oxidation catalyst 13 is at least partially decomposed to palladium metal which restores the oxidation activity of the oxidation catalyst of methane. In this embodiment sufficient fuel is metered into the exhaust line so that lean mode conditions are always established by burning some of the residual oxygen until the high temperatures are established. in the methane oxidation catalyst. For a periodic injection of fuel to generate very high temperatures by lean exhaust gas, it generates and oxidizing conditions, net in the methane oxidation catalyst which then returns to its activated catalyst state. FIG. 2 schematically shows a system similar to that of FIG. 1 with, in this development, a sulfur adsorption plant integrated in the methane oxidation catalyst 23. In a detailed manner, a turbocharger 21 is associated with the engine. 20. The exhaust gas of the internal combustion engine 20 passes through the exhaust gas conduit through the combined catalyst plant 23, which corresponds to a methane oxidation catalyst incorporating a combustion engine. sulfur adsorption to some extent an integrated sulfur trap. After the oxidation of methane, the exhaust gas passes over a catalytic particulate filter 24 before arriving in an SCR catalyst 26. Upstream of the SCR catalyst 26 via a dosing point 25 for the solution of the catalyst agent. reaction necessary for the catalytic operation of the SCR catalyst 26. Upstream of the methane oxidation catalyst 23 with an integrated sulfur trap, there is the injection plant 27 for injecting the fuel.

The production of the exhaust aftertreatment system with a sulfur adsorption plant 12 (FIG. 1) or a methane oxidation catalyst 23 with an integrated sulfur adsorption plant (FIG. 2) presents particular advantages for the rich, periodic mode of operation according to the invention of the methane oxidation catalyst. The sulfur of the sulfur adsorption plant 12 or the methane oxidation catalyst 23 is so solidly combined that in the case of a short atmosphere of "cold" rich gases which corresponds to a temperature below 500-550 ° C. C, defensive palladium sulfites are not formed. If there were no sulfur adsorption plant, it could be assumed that the methane oxidation catalyst has at least some fraction of the bound sulfur oxides, for example in the form of palladium sulfates. and which should be retransformed if necessary into sulphites of palladium. This would be a disadvantage from the point of view of the activity of the methane oxidation catalyst. The sulfur adsorption plant in the exhaust gas duct makes it possible to reduce the frequency of the reactivation according to the invention of the methane oxidation catalyst because it would prevent further deterioration of the activity, independent of the foregoing. - emitting palladium oxides because of the sulfur-containing components in the exhaust gas. The removal of sulfur necessary to regenerate a sulfur adsorption plant generally requires a lot of energy and a high temperature. In the system presented here, the removal of sulfur is independent of the "cold" periodic enrichment according to the invention. The enrichment according to the invention is used exclusively for the non-sulfur conditioned reactivation of the methane oxidation catalyst.

According to another development of the exhaust aftertreatment system, a particulate filter with a coating and an SCR catalyst in a component in the form of a "filtered SCR catalyst" (also called SCRoF : "SCR on filter"). Such embodiments are shown in Figures 3 and 4.

FIG. 3 shows a system with a methane oxidation catalyst 33 preceded by a sulfur adsorption plant 32. FIG. 4 shows a system in which the sulfur adsorption plant is integrated in the catalyst of FIG. Methane oxidation 43. In a manner comparable with the systems of FIGS. 1 and 2, the internal combustion engine 30, 40 that is to say in particular a gas engine running at a low engine speed or a gas / diesel engine. operating in lean mode, is equipped with a turbocharger 31, 41. With reference to FIG. 3, the exhaust gases of the internal combustion engine 30 pass through the sulfur adsorption plant 32 before arriving at the methane oxidation catalyst 33. Downstream of this catalyst 33 is the component (filter SCR) 36 which incorporates an SCR catalyst on a filter. Downstream of the catalyst SCR on filter 36 is a metering point for the reagent in the liquid state, necessary for the catalytic reaction in the SCR component on filter 36. With reference to FIG. The exhaust of the combustion engine 40 passes through the methane oxidation catalyst 43 incorporating the sulfur adsorption plant. Then the exhaust gases pass through the "filter SCR" component 46 and upstream of the SCR filter 46 there is a dosing point 45 for the reaction agent in the liquid state necessary for the catalytic reaction in the "SCR" component. on filter 46. Upstream of the sulfur adsorption plant 32 and at the same time upstream of the methane oxidation catalyst 33 (FIG. 3) or downstream of the methane oxidation catalyst 43 with the installation of integrated sulfur adsorption, there is each time a fuel injector 37, 47. These systems are also suitable for carrying out the method of the invention according to which periodically after the lean mode operation of the internal combustion engine 30, 40 fuel is injected to create a gas composition at the level of the methane oxidation catalyst 33, 43 which acts in the sense of reactivation, on the methane oxidation catalyst 33, 43.30 NOMENCLATURE OF THE MAIN ELEMENTS 10 Mote Internal Combustion System 11 Turbocharger 12 Sulfur Adsorption Plant 13 Methane Oxidation Catalyst 14 Particulate Catalyst 15 Dosing Point 16 SCR Catalyst 17 Fuel Injector 20 Internal Combustion Engine 21 Turbo Compression 23 Oxidation Catalyst of methane 24 Particulate catalytic filter 25 Dosing point 26 SCR Catalyst 27 Fuel injection system 30 Internal combustion engine 31 Turbo compressor 32 Sulfur adsorption plant 33 Methane oxidation catalyst 36 Filter 40 Internal combustion engine 43 Methane Oxidation Catalyst 45 Dosing Point 46 "SCR on Filter" Component 47 Fuel Injector30

Claims (6)

CLAIMS 1 °) Process for the management of a methane oxidation catalyst (13; 23; 33; 43) installed in an aftertreatment system of the exhaust gases of an internal combustion engine (10; 20; 40), characterized in that to increase the activity of the methane oxidation catalyst (13; 23; 33; 43) it is exposed to a gas composition acting reactively on the oxidation catalyst of methane. Process according to claim 1, characterized in that the methane oxidation catalyst (13; 23; 33; 43) is periodically exposed to the reactivation gas composition. 3) Method according to claim 1 or claim 2, characterized in that the gas composition is a reducing or oxidizing composition. Method according to claim 1, characterized in that the reactivation effect gas composition is obtained by operation in rich mode internally to the internal combustion engine (10; 20; 30; 40). Process according to Claim 1, characterized in that the reactivation-reactive gas composition is generated by the injection of fuel, including the aftertreatment system of the exhaust gases, by injecting the fuel upstream of the fuel. methane oxidation catalyst (13; 23; 33; 43). Process according to Claim 5, characterized in that, in a multi-stage process, the mass flow rate of oxygen in the exhaust gases is reduced by means applied in the engine before injecting fuel into the post-combustion system. exhaust gas treatment. 70) A method according to claim 5 or claim 6, characterized in that by the injection of fuel into the aftertreatment system exhaust gas temperatures of 700 ° C or more are generated in the region of the catalytic converter. methane oxidation (13, 23, 33, 43). 8 °) A method according to claim 5, characterized in that the fuel injected is liquid fuel, including gas oil or gasoline or a mixture of a fuel in the liquid state with a fuel in the gaseous state. 9 °) system for the aftertreatment of the exhaust gases of an internal combustion engine (10, 20, 30, 40) which comprises at least one methane oxidation catalyst (13, 23, 33, 43), characterized in that upstream of the methane oxidation catalyst there is at least one fuel injection plant (17, 27, 37, 47). 10 °) exhaust gas aftertreatment system according to claim 9, characterized in that the methane oxidation catalyst (13, 23, 33, 43) comprises at least one material that accumulates oxygen, in particular zirconium oxide and / or Lanthanum oxide and / or ceroxyd and / or praseodymium oxide and / or neodymium oxide or mixtures thereof. 11 °) exhaust gas after-treatment system according to claim 9, characterized in that at least one liquid fuel tank is associated with the aftertreatment system of the exhaust gases, in particular for diesel or gasoline. 12 °) exhaust gas after-treatment system according to claim 9, characterized in that the exhaust gas aftertreatment system comprises a sulfur adsorption plant (12; 32); sulfur adsorption plant being installed upstream of the methane oxidation catalyst (13; 33) or in the methane oxidation catalyst (23; 43). 13) A computer program comprising program code instructions for performing the steps of the method according to any one of claims 1 to 8 when the program is run on a computer.