WO2008009346A1

WO2008009346A1 - Particle separator and method for regenerating a particle separator

Info

Publication number: WO2008009346A1
Application number: PCT/EP2007/005800
Authority: WO
Inventors: Clemens Brinkmeier; Christof SCHÖN; Guido Vent
Original assignee: Daimler Ag
Priority date: 2006-07-15
Filing date: 2007-06-29
Publication date: 2008-01-24
Also published as: DE102006032886A1

Abstract

The invention relates to a particle separator (13) with a functional material coating and to a method for the regeneration of a particle separator (13) of said type. According to the invention, the functional material can, in an exothermic reaction, pass from a first modification into a second modification in such a way that, proceeding from a regeneration start temperature which lies below the soot ignition temperature (Tz), by means of a modification transition of the functional material, an exceedance of the soot ignition temperature (Tz) takes place at least locally such that a burning-off of deposited soot particles is permitted; for the method according to the invention, it is provided that, subsequent to a heating of the particle separator (13) to the predefined regeneration start temperature, a change in the composition of exhaust gas supplied to the particle separator is carried out in such a way that the functional material passes at least partially from a first modification into a second modification with the release of heat energy, and, in the process, the temperature at least in a region which is provided with the coating with the functional material is raised above the soot ignition temperature (Tz).

Description

Particle separator and method for regeneration of a

particle

The invention relates to a particle separator for separating soot particles contained in the exhaust gas of an internal combustion engine, which has a coating with a functional material on surfaces provided for depositing the soot particles, and a method for regenerating such a particle separator according to the preamble of claim 8.

It is known to deposit particles contained in the exhaust gas of internal combustion engines by means of a particle separator. The predominantly in the form of soot particles accumulate here, which affects the function of the Partikelabscheiders over time. For this reason, regeneration of the particle separator is usually carried out from time to time by burning off the separated soot particles. One difficulty is to set the increased temperature required to burn off the soot particles. In order to reduce the associated expense, it is known to reduce the burn-off temperature by means of a catalytically active additive added to the exhaust gas or by means of a catalytic coating for the particle separator. Corresponding methods are disclosed, for example, in Offenlegungsschriften EP 0 334 248 A1 and DE 100 48 511 A1. Setting a so-called Rußzündtemperatur required for igniting Rußabbrands is difficult, however, and there is a risk of an uncontrollable Abklennverlauf due to the catalytic support of Rußabbrands especially at too high heating.

The object of the present invention is to specify a particle separator and a regeneration method for a particle separator, with which an improved regeneration sequence is made possible.

This object is achieved by a particle separator having the features of claim 1 and by a regeneration method having the features of claim 8.

The particle separator according to the invention has a coating with a functional material on surfaces provided for the deposition of the soot particles. The functional material is able to change from a first modification to a second modification in an exothermic reaction, such that at a predetermined regeneration start temperature, which is below a soot ignition temperature required for burning off the separated soot particles, by a modification transition of the so-called Functional material at least locally exceeds the Rußzündtempera- temperature takes place, so that a burning of deposited soot particles is made possible. The decisive for an onset of Rußabbrands reaching or exceeding the Rußzündtemperatur is therefore effected directly on the surface of the particulate filter as a result of the modification transition of the functional material. The heat of conversion or heat of reaction liberated during the modification transition acts directly and directly on the deposited soot and is sufficient to make it over the time required for starting the burning reaction. to heat the Rußzündtemperatur and allow burning of deposited soot particles. The modification transition does not necessarily need to capture all of the functional material to raise the temperature of the coating at least locally above the soot ignition temperature, although this is preferred. Here, the soot ignition temperature is understood to mean a temperature value at which a Rußabbrand start and can proceed automatically without external energy supply from the outside. The coating is preferably carried out in the manner of a so-called washcoat known from heterogeneous catalysis and has a porous structure with a high specific surface area. The functional material is an essential part of the coating. The modification transition is preferably an exothermic change in the chemical structure of the functional material.

As a result of a typically intimate contact between the functional material and deposited soot, the heat transfer to the soot made possible by the particle separator according to the invention is improved compared to hot exhaust heating and the regeneration process can thus be more reliably and effectively initiated. The decisive heating step from a regeneration start temperature below or below the soot ignition temperature to or above the soot ignition temperature is locally limited directly at the location of the soot deposit. On the one hand, the energy expenditure is therefore reduced by the fact that the particle separator only has to be heated to a regeneration start temperature lying below the soot ignition temperature. On the other hand, an ineffective heating of components can be avoided, which are not affected by the regeneration process. The particle separator can in principle be designed as an electrostatic precipitator or as a cyclone. It is also possible to use a depth filter, for example in the form of a metal or ceramic foam, as well as an insert of a sintered metal filter or a so-called open filter structure. However, it is advantageous if, in an embodiment of the invention, the particle separator is designed as a wall-flowed particulate filter body having a multiplicity of elongate flow channels, wherein the walls of the flow channels, which can be flowed by the exhaust, are at least partially coated with the functional material. For example, for manufacturing reasons, it may be advantageous if in addition to the upstream wall surfaces and the outflow side wall surfaces of the flow channels are coated with the functional material. Such a preferably monolithic particulate filter body may be formed from conventional materials such as silicon carbide, cordierite or aluminum titanate.

In a further embodiment of the invention, the coating with the functional material is provided for all flow channels of the particle filter body and limited in the direction of the longitudinal extent of the particle filter body to a partial area. This results in a disk-shaped region of the particle filter body, which is provided with the coating. Preferably, the coated disk-shaped region is only a small part of the entire particle filter body. Compared with a coating provided over the entire longitudinal extent, functional material is saved by this measure, whereby a locally narrowly limited coating may well be sufficient to initiate the soot erosion. Starting from the areas provided with the coating, the process of soot burn-out is propagated as a result of the associated release of combustion heat out. Starting from the points provided with the coating, the soot burned progressively captures the entire particle separator without further energy being supplied from the outside, although initially this was predominantly at a temperature level below the soot ignition temperature.

In a further embodiment of the invention, the coating is provided for a subset of the flow channels. In particular, it is advantageous if the coating is provided for a subset of the flow channels, which usually have an increased temperature in comparison to the other flow channels. It is particularly advantageous if the coating is limited to a central cross-sectional portion of the particle filter body. In this way naturally occurring radial temperature gradients can be exploited and the regeneration starting temperature can be selected to be particularly low.

In a further embodiment of the invention, the coating is limited to an inflow-side region of the particle filter body. As a result, a usually existing temperature gradient in the exhaust gas flow direction is utilized. A Rußabbrand initiated by the inventive measure in the field of the exhaust gas inlet into the particle filter body can proceed from the outside in the axial direction without further energy from the outside.

In a further embodiment of the invention, the functional material has an oxygen storage capability and the first modification is designed as a low-oxygen modification and the second modification is formed as an oxygen-rich modification with an increased compared to the first modification oxygen content. Particularly preferred as a functional Onsmaterialien with oxygen storage capacity are oxides of rare earths such as cerium oxide and / or praseodymium oxide-based oxides or mixed oxides, which are preferably distributed homogeneously in the coating, so that the coating has an overall oxygen storage capacity. In a modification associated with the storage of oxygen modification transition with a corresponding increase in the oxidation number, a comparatively large exothermic heat of reaction occurs, so that the regeneration start temperature can be chosen particularly low. In general, in addition to the functional material, oxidation-catalytically active metals, preferably the iron-platinum group, in particular cobalt, nickel, platinum, rhodium, osmium, iridium, palladium and furthermore molybdenum, tungsten and / or manganese, may be provided as constituents of the coating. In this way the particle separator is given a particularly oxidation-catalytic effect. To expand the spectrum of action, the functional material may contain further constituents with other, in particular catalytic and / or adsorptive properties. In this context, components such as vanadium or alkaline earth metals, which can support a nitrogen oxide reduction and / or a nitrogen oxide storage, or zeolites, in particular those with an ability to store hydrocarbons, are advantageous. The materials mentioned may also be provided as coating zones spatially separated from the functional material or together with the functional material as a layered coating. In this way, a catalytically and / or adsorptively effective particle separator is obtained, which can be regenerated particularly reliably and gently.

In the method according to the invention for the regeneration of a particle separator as described above by burning off of or deposited in the particle separator. In order to initiate the burning off in a first method step, the temperature of the particle separator is raised to a predetermined regeneration starting temperature, which is below a soot ignition temperature required for burning off the separated soot particles. In a second method step, a change in the composition of exhaust gas supplied to the particle separator is made such that the functional material with the release of heat energy at least partially passes from a first modification to a second modification and thereby the temperature at least in a provided with the coating with the functional material area is raised above the soot ignition temperature. In this way, the energy required for heating for the purpose of regeneration is kept small. Exceeding the soot ignition temperature required for onset of soot burn is achieved by the exothermic modification transition of the functional material. In this case, the modification transition in turn is achieved by the change in the exhaust gas composition, which comprises in the embodiment of the method a change from a reducing composition to an oxidizing composition. This is preferably done at most to a slight extent increasing exhaust gas temperature. Thus, the locally localized lifting of the particle separator to or above the soot ignition temperature is not achieved by heat input via the exhaust gas, but as a result of the heat release associated with the modification change of the functional material. The procedure according to the invention makes it possible to achieve a considerable reduction in the energy requirement as well as the expense and procedural effort required to initiate the regeneration of the particle separator. In a further embodiment of the method, the change in the composition of the exhaust gas is at least partially effected by an internal combustion engine operating changeover. The operating changeover can be done by changing one or more operating parameters of the internal combustion engine or of associated components which influence its operation. Preferably, the engine changeover includes a change in the amount of air and / or fuel supplied to the combustion chambers. Also possible is alternatively or additionally a change of exhaust gas recirculation amount, boost pressure, injection timing, valve timing, suction and / or exhaust throttle.

In a further embodiment of the method, the change in the composition of the exhaust gas is at least partially effected by switching on or off a supply of an excipient which can be supplied to the exhaust gas from the outside upstream of the Partikelabscheiders. For example, a change made from an at least temporarily adjusted reducing exhaust gas composition to an oxidizing exhaust gas composition is effected by switching off a fuel supply and / or by switching on a secondary air supply.

Advantageous embodiments of the invention are illustrated in the drawings and described below. In this case, the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination of features, but also in other combinations or alone, without departing from the scope of the present invention.

Showing: 1 is a schematic block diagram of an internal combustion engine with associated exhaust system comprising a particle separator,

FIG. 2 is a graph showing the temperature dependency of the soot burning rate. FIG.

3 shows a diagram to illustrate the energy curve in a Rußabbrandreaktion,

4 shows a first advantageous embodiment of the particle separator according to the invention,

5 shows a second advantageous embodiment of the particle separator according to the invention,

6 shows a third advantageous embodiment of the particle separator according to the invention,

7 shows a fourth advantageous embodiment of the particle separator according to the invention,

Fig. 8 shows a fifth advantageous embodiment of the Partikelabscheiders invention and

9 shows a sixth advantageous embodiment of the particle separator according to the invention.

In Fig. 1, only schematically an internal combustion engine with a particulate separator comprising exhaust gas cleaning device is shown. According to FIG. 1, the internal combustion engine 10 of a motor vehicle, not shown, receives combustion air via an intake air line 11. The combustion exhaust gases are removed via an exhaust gas line 12, in which the particle separator 13 is arranged. In the exhaust pipe 12 further exhaust gas cleaning components are preferably arranged, which is not shown in detail. In particular, it is advantageous if the particle separator 13 is preceded by an oxidation catalytic converter and an SCR catalytic converter is connected downstream, which enables comprehensive exhaust gas purification. The internal combustion engine 10, hereinafter referred to as engine for short, is preferably a diesel engine educated. The particle separator 13 removes during operation of the internal combustion engine 10 particulate components from the exhaust gas supplied to it. In the following, it is assumed that the particle separator 13 is a honeycomb-type particulate filter through which the wall flows. As a result of the deposition or filtering out of particles, a load of the particulate filter 13 that predominantly consists of soot particles is formed. If this load has reached a certain extent, a regeneration of the particulate filter 13 is initiated, which will be discussed in more detail below.

Preferably, a determination of the loading state of the particulate filter 13 takes place continuously or at short time intervals. This is preferably done by detecting and evaluating a differential pressure across the particulate filter 13, for which purpose a first pressure sensor 14 is provided on the input side and a second pressure sensor 15 on the output side of the particulate filter 13. Further, not shown sensors such as temperature and exhaust gas sensors are preferably provided in addition to the monitoring and control of the emission control system. The signals of the sensors 14, 15 and optionally further sensors are passed via signal lines 16 to an electronic control unit 17. The control unit 17 has an arithmetic unit for processing the received data and a memory unit in which calculation routines, data, characteristics and characteristic maps are stored, with the aid of which the calculations provided for determining the loading state can be carried out. The electronic control unit 17 is also able to control the operation of the engine 1 and the entire exhaust gas purification device in response to the signals. Representing the existing control lines, a motor control line 18 is shown for controlling the engine operation. If a critical load is determined by the model based simulation and / or by evaluation of the corresponding sensor signals from the control unit, the regeneration of the particulate filter 4 is initiated by thermal Rußabbrand as soon as a suitable for this purpose and recognized by the control unit 17 as permitted engine operating condition.

Hereinafter, referring to FIG. 2 and FIG. 3, the thermodynamic and reaction kinetic phenomena of soot burning involved in the invention will be described. For this purpose, the dependence of the reaction rate v _R of Rußabbrands of the temperature T is shown schematically in the diagram of FIG. 2. As indicated by the course of the curve 20, the reaction rate v _R of Rußabbrands is negligibly small at low temperatures. Only when a characteristic soot ignition temperature T ₂ is exceeded does v _R assume values for a noticeable soot burn-off, with increasing temperature T the velocity v _{R of} the soot burn-up increasing drastically, typically exponentially.

The energetic relationships corresponding to this situation are shown schematically in the diagram of FIG. 3, in which the dependence of the potential energy E of the Rußabbrandreaktion on the reaction coordinate R is represented by the course of the curve 21. Starting from an energy Ei of the initial state requires applying the activation energy E _{A to} start the burning. The activation energy E _A can thus be considered as an energy barrier, which must be overcome for a start or an ignition of Rußabbrandreaktion. At the end of the burning reaction, the potential energy E decreases to the value E ₂ , which is opposite to the initial value Egg is reduced by the amount of energy released in the exothermic reaction.

The amount of energy required to start the Rußabbrandreaktion to overcome the energy barrier is typically applied by thermal means, ie by a temperature increase above the Rußzündtemperatur T ₂ . According to the invention, this takes place decisively in that an exothermic modification conversion is brought about for a functional material with which the particle filter 13 is coated. As a result of the heat released during the modification conversion, starting from a regeneration start temperature lying below the soot ignition temperature T _z , the soot ignition temperature T _{z is} exceeded at least locally on the particle filter, so that the soot combustion reaction is initiated. As a result of a derivative of the heat released during Rußabbrand the Rußabbrandvorgang propagates starting from the point of its origin and detects the entire particle filter 13 so that it is regenerated as a whole. As a functional material as an essential component of the coating of the particulate filter 13, a material is preferably provided which can undergo an exothermic structural transformation in a chemical reaction with an exhaust gas component, in which it passes from a first modification to a second modification. To initiate the Rußabbrands enriched from the regeneration start temperature and a first modification of the functional material, the exhaust gas supplied to the particulate filter with the serving as a reaction partner for the functional material exhaust gas component, so that the reaction can proceed. As a result of the modification of the functional material taking place with the run-off, the latter, which is in heat-transfer contact, deposits on the particle filter 13 Soot heated to or above the Rußzündtemperatur T ₂ and the Rußabbrand allows.

As a functional material, a material is preferably provided which is capable of gas storage by a chemical reaction with an exhaust gas component. As an example, here a nitrogen oxide storage material can be cited, which is present in the initial state, for example, as carbonate and merges with a storage of nitrogen oxides contained in the exhaust gas in a nitrate form as a second modification. Likewise, a chemical structural change takes place in the storage of oxygen in an oxygen storage material such as cerium oxide or a mixed oxide containing cerium oxide, which on oxygen absorption changes into an oxygen-rich modification of higher chemical valence. However, it may also be a modification change in the form of formation of a chemisorption bond of the functional material with a gas, in which the chemical structure of the functional material remains substantially unchanged, but the stored gas is bound by weak chemical bonds to the functional material. An example of this is the adsorption of hydrocarbons in suitable storage materials such as zeolites.

Without restricting generality, it is assumed below that the functional material is a rare-earth oxide, in particular a cerium- and / or praseodymium-based oxide or mixed oxide, which undergoes heat emission by reaction with oxygen contained in the exhaust gas oxygen-poor first modification into an oxygen-rich, second modification can proceed.

To carry out a regeneration of the particulate filter 13 is first changed by the control unit 7, the engine operation such that there is an increased temperature of the inflowing into the particulate filter 4 exhaust gas. According to the invention, it is provided to heat the particle filter 13 to a regeneration starting temperature which is below the soot ignition temperature T _z required for initiation of the soot burn-off. Depending on the type and amount of the functional material provided as a coating, the regeneration can Starttempe- temperature about 50 ⁰ C to 150 ⁰ C below the soot ignition temperature T _z are. Typically, the regeneration start temperature is about 550 ^° C. To generate a superheated exhaust gas, with which the particle filter 13 is heated to the regeneration start temperature, known measures such as intake air throttling, late fuel post injection, fuel afterburning can occur at one upstream of the particulate filter Oxidation catalyst and the like are taken.

If the functional material is not already present in its first, low-oxygen modification, heating with the regeneration start temperature or after reaching the same, generates an oxygen-poor, in particular reducing, exhaust gas and, by its action, brings the functional material into its first, low-oxygen modification , Typically, an exposure time of the oxygen-lean exhaust gas from about 10 seconds to 30 seconds is sufficient for this purpose. To generate the low-oxygen or reducing exhaust gas, the engine 10 may be operated with air deficiency and / or the exhaust gas, for example, fuel may be supplied as a reducing component. It is envisaged that in this process, the particulate filter 13 at least approximately at the predetermined regeneration start temperature below the Rußzündtemperatur T _z remains or has been reached by this time at the latest.

To initiate Rußabbrands an oxygen-enriched, in particular an oxidizing exhaust gas is generated in a subsequent step and brought by the action of the functional material in its second, oxygen-rich modification. The thus released heat of transformation heated at least locally with the functional material in heat transfer contact soot deposits on the Rußzündtemperatur T _z so that the Rußabbrand and thus the actual regeneration process can be started. To generate the oxygen-enriched or reducing exhaust gas, the engine 10 can be operated with excess air and / or the exhaust gas, for example, secondary air can be supplied as oxidizing component.

Preferably, the generation of the oxygen-enriched exhaust gas is maintained at least until the Rußabbrandvorgang has spread throughout the particulate filter 13 and the regeneration is completed. During this time, an overheated exhaust gas is preferably still generated, it being possible to provide control of the course of the soot combustion by changing the exhaust gas temperature and / or the exhaust gas composition. In this way, on the one hand too rapid burning with an undesirably large heat release and on the other hand premature extinguishment of Rußabbrands avoided. If the termination of Rußabbrandvorgangs determined by expiration of a predetermined period of time or by evaluation of sensor signals, the engine is switched back to normal operation and stops the generation of a superheated exhaust gas. In order to ensure the most uniform and reliable Rußabbrand throughout the particulate filter 13, a coating may be provided with the functional material on its entire surface. However, it is advantageous for reasons of material savings to provide the coating with the functional material only in sections on the walls of the flow channels of the particulate filter 13. In the following, advantageous embodiments will be discussed with reference to FIGS. 4 to 9.

In Fig. 4, a wall-flowable particulate filter 13 is shown in honeycomb structure schematically in longitudinal section. The particle filter 13 is traversed by a plurality of flow channels 2, which are bounded by porous gas-permeable walls 3. The flow channels 2 are mutually provided at their inlet-side and outlet-side ends with closure plugs 7. As a result, exhaust gas flowing into inlet side open flow channels 2 is forced to pass through the walls 3, with particulate constituents being filtered out and depositing on the surfaces of the walls 3 which have been flown on. For the sake of clarity, the closure plug 7 present in usually all flow channels 2 is shown only in the case of two flow channels 2. With regard to the exhaust gas flow direction indicated by the arrow 4, at least the upstream wall surfaces of the flow channels 2 of the particle filter 13 are provided with a functional material coating in the rear part region 5 thereof. On the other hand, in the clearly shorter inlet-side partial area 6, the particle filter 13 is designed free of a functional material coating. This avoids that the functional material is exposed to the usually in the entrance area of the particulate filter 13 particularly high temperatures. Advantageously, an approximately 5 mm to 50 mm, or about 5% to 50% of its total Length free of a coating with the functional material executed on the input side portion 6 of the particulate filter 13. The input-side portion 6 may be performed completely uncoated or have another, preferably catalytically active coating. From a manufacturing point of view, it is preferred if coatings on the walls 3 of the flow channels 2 are applied approximately uniformly and encompass the entire cross section of the particle filter 13.

5 shows a second advantageous embodiment of a particulate filter 13 designed according to the invention. In contrast to the embodiment of FIG. 4, only one input-side subregion 5 is provided with the functional material coating. This embodiment is particularly recommended for a high temperature resistant functional material. With regard to the propagation of Rußabbrands this embodiment is advantageous because it propagates in particular in the exhaust gas flow direction and therefore a reliable regeneration is possible. Since the input side usually has elevated temperatures, the regeneration start temperature can be chosen to be comparatively low. Advantageously, a partial region 5 of the particle filter 13 provided with the functional material coating is approximately 5 mm to 50 mm, or approximately 5% to 50% of its total length, on the input side.

FIG. 6 shows a third advantageous embodiment of a particulate filter 13 embodied according to the invention. In contrast to the embodiment of FIG. 4, an input-side subregion 5 'as well as a rear subregion 5 are provided with a functional material coating. The middle subregion 6, which is made free of a functional material coating, preferably makes about 20% to 30%. the total length of the particulate filter 13 from. Compared to a continuous coating can also achieve a saving of material, the ignition of the Rußabbrands in the input-side portion 5 ^V first, later also rear portion 5 occurs. By thermal conduction, the central region 6 can also pass over the Rußzündtemperatur, so that here too the Rußabbrand can run. FIG. 7 shows a further advantageous embodiment of the particle filter 13 according to the invention. In this embodiment, only a central portion 5 of a functional material coating is provided. As a result, an input side and an output side directly adjacent portion are kept free for other, especially catalytically active coatings. Preferably, the middle portion 5 makes up about 20% to 60% of the total length of the particulate filter 13. However, for a reliable ignition of Rußabbrands also a narrow disc-shaped portion of the particulate filter 13 of less than 10% of the total length with a functional material coating sufficient.

In the further advantageous embodiment shown in FIG. 8, subregions 5, 5 ^V , 5 ^λ \ 5 ^{λ VX provided} with a functional material coating alternate with subregions without functional material coating. In this way, a reliable ignition of Rußabbrands in a plurality of areas of the particulate filter 13 is ensured.

FIG. 9 shows a particle filter 13 which is provided with a functional material coating only on the inflow side in a radially central subregion 5. In this case, on the one hand, a longitudinal sectional view and on the other hand, a view of the input-side end face are shown. Since in the front central region of the particulate filter 13 usually the highest temperatures are encountered, can still be reliably initiated here with a comparatively low regeneration start temperature Rußabbrand.

For a reduction of the activation energy E _A for igniting the Rußabbrands may additionally be provided using a catalytically active component with respect to Rußabbrands. This enables a reduction in the regeneration start temperature, which in turn achieves a reduction in the energy required to heat the particulate filter 13 to the regeneration start temperature. The catalytic component may be admixed as an additive to the exhaust gas. For this purpose, it is expedient to provide a fuel and / or an oil additive. The catalytically active components passes via combustion of fuel or oil into the exhaust gas on the particle filter and can develop their catalytic effect there. A direct feed of the catalytically active component into the exhaust gas can also take place.

However, the catalytically active component can also be present as a constituent in the functional material coating of the particle filter 13 or be applied as a separate coating locally separated from the functional material coating on the particle filter 13. Also possible is a formation of a double-layer coating, preferably with the functional material coating as the upper layer. Additionally or alternatively, a coating may be provided which acts catalytically with respect to a reaction of gaseous exhaust gas constituents such as hydrocarbons, carbon monoxide or nitrogen oxide. In this way, the functionality of the particulate filter 13 can be expanded. As a result of the procedure according to the invention, the temperature load of the particulate filter 13 during regeneration is low, while less temperature-stable catalyst materials such as vanadium pentoxide-containing catalyst materials can be used, the use of which is otherwise not possible.

Claims

claims

1. Particle separator for the deposition of exhaust gas in an internal combustion engine (10) contained soot particles, which has on coated for deposition of the soot particles surfaces having a coating with a functional material that can pass in an exothermic reaction of a first modification in a second modification, such that at a predetermined regeneration start temperature, which is below a required for burning the deposited soot particles Rußzündtemperatur (T _z ), at least locally exceeding the Rußzündtemperatur (T _z ) by a modification transition of the functional material, so that burning off of deposited soot particles is made possible.

2. Particle separator according to claim 1, characterized in that the particle separator (13) is designed as a wall-flowed particulate filter body with a plurality of elongated flow channels (2), wherein the exhaust gas flows from the walls (3) of the flow channels (2) at least partially with the functional material coated are executed.

3. particle separator according to claim 2, characterized in that the coating with the functional material for all

Flow channels (2) of the particulate filter body is provided and in the direction of the longitudinal extension of the particle filter body to a portion (5; 5 ^λ ; 5 ' ¹ ) is limited.

4. particle separator according to claim 2 or 3, characterized in that the coating for a subset of the flow channels (2) is provided.

5. Particle separator according to one of claims 2 to 4, characterized in that the coating is limited to a central cross-sectional portion of the particulate filter body.

6. Particle separator according to one of claims 2 to 5, characterized in that the coating is limited to an inflow-side portion of the particulate filter body.

7. Particle separator according to one of claims 1 to 6, characterized in that the functional material has an oxygen storage capacity and the first modification is formed as a low-oxygen modification and the second modification as an oxygen-rich modification with respect to the first modification increased oxygen content.

8. A method for regenerating a particle separator according to any one of claims 1 to 7 by burning off on or in the Partikelabscheider (13) deposited soot, wherein to initiate the burning in a first method step, the temperature of the Partikelabscheiders (13) is raised to a predetermined regeneration start temperature, which is below a required for burning the deposited soot particles Rußzündtemperatur (T ₂ ), characterized in that in a second process step, a change the composition of the exhaust gas supplied to the particle separator is made such that the functional material with release of heat energy at least partially passes from a first modification to a second modification and thereby the temperature at least in a provided with the coating with the functional material area above the Rußzündtemperatur (T ₂ ) is raised.

9. The method according to claim 8, characterized in that the change in the composition of the exhaust gas comprises a change from a reducing composition to an oxidizing composition.

10. The method according to claim 8 or 9, characterized in that the change in the composition of the exhaust gas is at least partially effected by an internal combustion engine operating.

11. The method according to any one of claims 8 to 10, characterized in that the change in the composition of the exhaust gas is at least partially effected by switching on or off a supply of an excipient upstream of the Particle separator (13) can be supplied to the exhaust gas from the outside.