DE10048511A1 - Reduction of carbon monoxide, hydrocarbons and soot particles in lean exhaust gas from internal combustion engine, by using particle filter having catalytic coating of oxygen storage component(s) and platinum group metal(s) - Google Patents

Abstract

Carbon monoxide, hydrocarbons and soot particles in the lean exhaust gas are reduced by using a particle filter. The particle filter has a catalytic coating containing a first group of components for reducing the ignition temperature soot and platinum group metal(s) of platinum, palladium or rhodium. The first group comprises oxygen storage component(s). Reduction of carbon monoxide, hydrocarbons and soot particles in the lean exhaust gas from an internal combustion engine involves using a particle filter. The soot particles have a soot ignition temperature. The particle filter is regenerated from time to time by raising the temperature of the particle filter to above the soot ignition temperature and burning the soot particles. The temperature of the filter is increased to the temperature required to initiate soot ignition by burning additional fuel on the catalytic coating when the exhaust gas back pressure reaches a predetermined value. The particle filter has a catalytic coating containing a first group of components for reducing the ignition temperature soot and platinum group metal(s) of platinum, palladium or rhodium. The first group comprises oxygen storage component(s). An Independent claim is also included for a particle filter for use in the above process. The particle filter can be wall flow filter, wire mesh filter, or open pore ceramic or metallic foam filter.

Description

The invention relates to a method for removing carbon monoxide, carbon dioxide substances and soot particles from the lean exhaust gas of an internal combustion engine Use of a particle filter.

Particle filters are able to remove soot particles from the lean exhaust gas from combustion filter out motors and thus prevent their emission into the atmosphere. there various filter concepts are used, such as wall flow filters, Filters made of ceramic fibers or ceramic or metallic foams and filters from wire mesh. This enables filtration levels of well over 95% to be achieved the.

The real difficulty is not the filtration of the soot particles, son in the regeneration of the filters used. Carbon black only burns at Temperatures of around 600 ° C. These temperatures are, for example, from modern diesel engines are generally only achieved at full load. Therefore are additional che, supportive measures for the oxidation of the soot separated from the exhaust gas particles necessary.

A distinction is made between active and passive measures: With the active measure the temperature of the filter was taken, for example, by an electrical heater tion raised above the temperature required to oxidize the soot. Such Measures are always associated with additional fuel consumption. In the passive engaging systems is, for example, by using metal organi fuel additives such as ferrocene or by a catalytic coating of the Filters lowered the soot ignition temperature.

DE 31 41 713 A1 describes a coating which lowers the soot ignition temperature tion, which contains silver vanadate as the active substance. A further education of these Er The invention is described in DE 32 32 729 C2. Then the ignition temperature lowering coating as active substance lithium pentoxide, vanadium pentoxide with Al potassium metal oxide, a vanadate, a perrhenate or a combination of these substances contain.  

DE 34 07 172 describes a device for cleaning the exhaust gases from diesel motors of oxidizable solid, liquid and gaseous pollutants. To this Purpose contains the device in a housing directly or at a distance behind one another arranged filter elements, at least one filter element A, which the lowering the ignition temperature of the soot and promoting its combustion carries and at least one filter element B, which makes the combustion more gaseous Catalyst promoting pollutants carries, alternate several times.

Koberstein et. al. describe in "Use of exhaust gas aftertreatment devices" (VDI reports No. 559; VDI-Verlag 1985, 275-296) a wall flow filter, which a combined coating with ignition catalyst on the channel walls of the gas inlet side and with an oxidation catalyst on the gas outlet side. The function of the It is the oxidation catalyst that is released during the filter regeneration Oxidize hydrocarbons and thus render them harmless.

US 4,510,265 describes a self-cleaning diesel particle filter. The filter is with a catalyst mixture of a platinum group metal and silver vanadate Mistake. The presence of the catalyst mixture reduces the ignition temperature of the Diesel particles.

US 4,849,399 also describes a catalyst composition for reducing the ignition temperature of diesel soot. The composition contains sulfur resi Stent inorganic oxides from the group titanium oxide, zirconium oxide, silicon dioxide, aluminum minium silicate and aluminum oxide as well as catalytically active on the oxide ve components from the group of platinum, palladium and rhodium.

According to US 5,100,632, the ignition temperature of diesel soot can also be with a cat Analyzer composition can be reduced, which is a platinum group metal and an earth contains alkali metal. In particular, a catalyst composition made of magne silicon oxide and platinum and / or rhodium are proposed.

US 5,758,496 describes a particle and exhaust gas purification system, which one Contains particle filter, whose porous walls directly with a catalytically active metal coated for the oxidation of carbon monoxide and unburned hydrocarbons is. To reduce the ignition temperature of the diesel soot deposited on the filter an additive is added to the fuel. This additive consists of an organome tall compound in a liquid carrier medium. In particular, the Organometallic compounds around copper, nickel or ceroctoate.  

US 5,792,436 describes a process for the removal of nitrogen oxides and Sulfur oxides from the lean exhaust gas of internal combustion engines. For this, the Exhaust gases passed through a catalyzed trap, which is a combination of a nitrogen oxide and contains sulfur oxide absorbing material and an oxidation catalyst. The absorbent material can be regenerated by increasing the temperature of the trap become. For this purpose, the exhaust gas flow during the regeneration phase combustible components added, which are burned on the oxidation catalyst and the temperature of the trap to the desorption temperature for nitrogen oxides and welding increase field oxides. Suitable absorber materials are oxides, carbonates, hydroxides or mixed oxides of magnesium, calcium, strontium, barium and lanthanum as well Oxides of cerium, praseodymium and oxides of elements with atomic numbers from 22 to 29. The oxidation catalyst consists of at least one platinum group metal. from sorbent material and oxidation catalyst are in the form of a coating for example on a honeycomb body with parallel, freely flowable Channels or applied to spherical or tablet-shaped support bodies, which in one Are arranged.

US 6,023,928 describes a method for simultaneous reduction in the Exhaust gas from a diesel engine contains soot particles, unburned hydrocarbons and carbon monoxide. The process uses a platinum-catalyzed particle filter Combination with a cerium-containing fuel additive to adjust the ignition temperature of the To reduce soot.

The lowering of the soot ignition temperature by a soot ignition coating or by a fuel additive is generally unable to regenerate the filter to ensure even at low load points, so that nowadays a com combination of active and passive measures is used.

The combination of an oxidation catalyst in verbin has proven particularly useful with a particle filter. The oxidation catalyst is in front of the particle filter arranged in the exhaust system. By post-injection or other motor Actions put unburned fuel and carbon monoxide on the oxida tion catalyst and are converted there catalytically to carbon dioxide and water. With the help of the released heat of reaction, the exhaust gas and thus that downstream particle filter heated. Such a system describes, for example GB 2 134 407 A. In connection with a kata that lowers the soot ignition temperature lytic coating of the filter or fuel additives can reduce the amount of  Post-injection of fuel is reduced and the filter at every operating point of the Motors are regenerated.

EP 0 341 832 B1 takes a different route. It describes a procedure for Treatment of exhaust gas from heavy goods vehicles. The exhaust gas is first filtered passed over an oxidation catalyst to the nitrogen monoxide contained in it to oxidize to nitrogen dioxide. The exhaust gas containing nitrogen dioxide is then used to burn the particles deposited on a downstream filter, wherein the amount of nitrogen dioxide is sufficient to the combustion of the on the Fil ter deposited particles at a temperature of less than 400 ° C. This should enable a continuous regeneration of the particle filter without a periodic post-injection of fuel to increase the exhaust gas temperature is required.

EP 0 835 684 A2 describes a method for treating the exhaust gas from light trucks and passenger cars. According to this process, the exhaust gas is passed over two series-connected catalysts, the first of which oxidizes the nitrogen monoxide contained in the exhaust gas to nitrogen dioxide, which oxidizes soot particles which have been deposited on the second catalyst to CO ₂ .

The processes described in the last two patents set high standards Proportion of nitrogen oxides in the untreated exhaust gas of the diesel engine ahead. It is ever but generally not sufficiently so.

In a press release dated April 15, 1999, PSA Peugeot Citroën for Die selmotoren a particle filter system with periodic regeneration of the particle filter presented by burning off the soot particles deposited on the filter. The one on the Soot particles deposited in the filter only burn in the presence of oxygen a temperature of 550 ° C. To the regeneration of the particle filter also during Operating conditions of the diesel engine with exhaust gas temperatures of only 150 ° C (for the game while driving in the city), several measures are taken dripped. On the one hand, the exhaust gas temperature is raised to 450 ° C by active measures increased. On the other hand, a cerium-containing additive is added to the fuel natural combustion temperature of the soot particles is reduced to 450 ° C. To increase the exhaust gas temperature to 450 ° C during the expansion phase fuel in the Injected cylinder. This process is referred to as post-injection in the following net. The associated post-combustion increases the exhaust gas temperature by 200 raised to 250 ° C. In addition, there is another afterburning of unburned ones  Hydrocarbons resulting from the post-injection on one in front of the filter arranged oxidation catalyst. This increases the exhaust gas temperature by another 100 ° C.

A disadvantage of the known methods and exhaust systems that reduce the Soot ignition temperature additive to the fuel is the fact that the Additive after regeneration of the particle filter in the form of an ash, for example Cera accumulated in the filter. There is also an ash from the combustion of the with the Exhausted lubricating oil (oil ash). Cerash and oil ash form a powder shaped, flaky composition that remains as a residue after burning the soot remains in the filter. After a certain period of operation of the internal combustion engine Depending on the size of the engine, several hundred grams of ash accumulate in the filter and increase the exhaust gas back pressure. The filter is therefore usually lengthened This operating time is freed from this ash by washing with water.

Against the background of the prior art presented, it is the task of the present Invention, a method for reducing carbon monoxide, kohlwas to specify materials and soot particles in the lean exhaust gas of internal combustion engines, which has a reduced energy requirement for the regeneration of the soot filter and also the interval between two washes of the filter to remove accumulated ashes extended. Further objects of the invention are a particle Filters for use in the method according to the invention and a drive unit a motor vehicle from a diesel engine in combination with the particle filter.

This object is achieved by a method for reducing carbon monoxide, hydrocarbons and particles in the lean exhaust gas of internal combustion engines using a particle filter, the soot particles having a soot ignition temperature T _Z and the particle filter from time to time by raising the temperature of the particle filter above the soot ignition temperature and Burning the soot particles is regenerated. The method is characterized in that the particle filter is provided with a catalytic coating, which contains both an ignition temperature T _{Z of} the soot-reducing component and a component for the oxidation of carbon monoxide and hydrocarbons, the temperature of the filter when Errei chen a predeterminable exhaust gas back pressure is increased by burning additional fuel on the catalytic coating to the temperature required for ignition of the soot combustion.

Under a particle filter in the context of this invention, a fine-pored, open-pore ger understood body that is able, for example, the soot particles in the exhaust gas Diesel engine with a particle size in the range between 0.1 and 10 µm to more than 80, preferably more than 90%, to be mechanically filtered out of the exhaust gas stream. For the So-called depth filters made of ceramic fibers or wire are suitable weave. Ceramic or metallic foams can also be used far so that the required degrees of filtration can be achieved. So-called are preferred called wall flow filters used, with which degrees of filtration over 95% are obtained. Wall flow filters are set up like normal honeycomb bodies for automotive exhaust gas catalysts builds. The filter bodies have a generally cylindrical shape and are of an inlet end surface to the outlet end surface of flow channels for the exhaust gas traversed. In contrast to normal catalytic converters, the channels are the Wall flow filter on the end faces mutually clogged so that the exhaust gas is at The path from the entry face to the exit face is forced to be porous To flow through channel walls. Here, the soot particles from the exhaust gas flow filtered out.

The process uses active and passive measures to reduce the particle content and also the concentration of hydrocarbons and carbon monoxide in the exhaust gas of a diesel engine. The process is divided into a filtration phase and a regeneration phase, which are repeated cyclically. During the filtration phase, the soot particles are filtered out of the exhaust gas stream and deposited on the filter. At the same time, the oxidative component of the catalytic coating converts carbon monoxide and hydrocarbons to a large extent to carbon dioxide and water. Because of the low content of these oxidizable exhaust gas components in the exhaust gas, the exotherm released during the reaction is not sufficient to heat the filter to the regeneration temperature. With increasing soot deposition, the exhaust gas back pressure of the filter increases and impairs the performance of the internal combustion engine. Therefore, the regeneration of the filter must be initiated when a predetermined exhaust gas back pressure is reached. For this purpose the hydrocarbon content of the exhaust gas is increased by supplying additional fuel. The additional fuel burns on the oxidative component of the catalytic coating and increases the temperature of the filter to such an extent that the ignition temperature T _{Z of} the soot is exceeded and the soot burns off. The supply of additional fuel is then stopped and the filtration phase starts again.

Due to the component of the catalytic loading which lowers the ignition temperature of the soot Layering the particle filter becomes less additional for the regeneration of the filter Fuel consumes than without this component. Another advantage is the direct one Burning the additional fuel on the filter. This will make more Fuel saved by using a separate oxidation unit connected upstream of the filter would be necessary to the oxidation catalyst itself and possibly long exhaust tract between the oxidation catalytic converter and the particle filter on the Regenera heating temperature of the filter.

Another advantage of the invention over that known from the prior art The most common method of reducing the soot ignition temperature with fuel additives is The fact that no ash from the additives can collect in the filter. It finds single Lich, as with the other processes, oil ash is deposited instead. The Maintenance interval for removing such ashes from the filter by appropriate Rinsing or washing with water can therefore be essential compared to the process can be extended with fuel additives. As appropriate experiments have shown is the catalytic coating of the filter against such washing processes constantly.

To reduce the ignition temperature of the soot, the catalytically active Be contains Layering the filter at least one oxygen storage component and Oxidation of carbon monoxide and hydrocarbons at least one of the platinum group metals platinum, palladium and rhodium, the oxygen-storing Component at least one material from the group cerium oxide, cerium / zirconium mixed oxide and manganese oxide or mixtures thereof. One with zirconium oxide is preferred Stabilized cerium oxide used, which is 10 to 30 wt .-% zirconium oxide, based on the total weight of the stabilized material.

In particular, the thermally stabilized, oxygen-storing are for the invention Suitable materials according to DE 197 14 707 A1. It is oxygen storage materials with high temperature stability on the basis of cerium oxide, the at least one stabilizer from the group praseodymium oxide, lanthanum oxide, yttrium contain oxide and neodymium oxide, the stabilizer or stabilizers and optionally Cerium oxide in highly dispersed form on the specific surface of a high surface area Carrier material from the group aluminum oxide, zirconium oxide, titanium oxide, silicon dioxide, Cerium oxide and mixed oxides thereof, in particular on the cerium / zirconium Mixed oxide.  

It has been shown that multi-component coatings of the particle filter synergi have an influence on the lowering of the soot ignition temperature. During a loading Layering of cerium oxide only lowers the soot ignition temperature by around 30 to 40 ° C and with a coating of pure manganese oxide, there is hardly any reduction in ignition temperature is detectable, a mixture of cerium oxide and manganese oxide causes a Lowering the ignition temperature by about 60 to 70 ° C. A Mi is preferred used in a weight ratio of 1: 1. However, mixtures with Weight ratios between cerium oxide and manganese oxide from 1: 5 to 5: 1 used become. A further reduction in the ignition temperature is obtained from the Beimi creation of an alkaline earth metal oxide, in particular calcium oxide. By a Be Layering of cerium oxide, manganese oxide and calcium oxide in a weight ratio of 4: 4: 2 the ignition temperature of the soot particles could be reduced by 110 ° C, for example become.

In addition to the materials mentioned, the catalytic coating can also be used at least one oxidic support material from the group active aluminum oxide, silici contain dioxide, titanium oxide and zirconium oxide or mixed oxides thereof.

Various types of filters are suitable for the process, such as wall flow filters, filters made of ceramic fibers or ceramic or metallic foams as well Wire mesh filters. Wall flow filters made of silicon carbide, Cor dierite or sodium zirconium phosphate used. With these filters only the entrance side with the catalytic coating. The concentration of the coating is between 20 and 150 g / l filter body, while the concentration of the Platinum group metals is 0.5 to 10 g / l filter body.

The additional fuel can be used to initiate the regeneration of the particle filter Exhaust gas flow must be added before the particle filter. It is preferred for heating Particulate filter needed additional fuel during the expansion onsphase injected into the cylinders of the internal combustion engine. By in the cylin The afterburning process already increases the exhaust gas temperature about 150 to 200 ° C. Afterburning does not result in the entire post-injection Fuel burned, but there is a certain amount of unburned coal into the exhaust gas and is directly on the filter by the oxidative components of the burned catalytic coating.

The catalytically coated filter is able to remove a large part of the Internal combustion engine emitted hydrocarbons and carbon monoxide to carbon dioxide  and implement water, so that for most operating phases of burning engine no additional catalyst for exhaust gas purification is necessary. For further Improve conversion rates for carbon monoxide and hydrocarbons can the particle filter in a particularly advantageous embodiment of the method an oxidation catalytic converter in the position close to the engine, which dimen is based on the fact that it is used for the regeneration of the fuel during a post-injection Filters only convert a small portion of the fuel, so most of the fuel too additional fuel gets on the filter and can be implemented there. Important Influencing factors for the design of this oxidation catalyst are its volume and its content of catalytically active components. These two factors can can be optimized in a simple manner by a person skilled in the art according to the intended purpose.

The method according to the invention is preferably used for exhaust gas purification of vehicles with diesel engines. The drive unit of such a motor vehicle contains a diesel engine and an exhaust gas purification system with a particle filter for carrying out the method according to the invention, wherein the exhaust gas temperature of the engine for regeneration of the particle filter can be increased by post-injection of fuel into the cylinders of the diesel engine during the expansion phase. The particle filter of this drive unit is provided with the catalytic coating already described, which contains both a component that reduces the ignition temperature T _{Z of} the soot and a component for the oxidation of carbon monoxide and hydrocarbons. A particularly advantageous embodiment of this drive unit contains an oxidation catalytic converter in the position close to the engine in front of the particle filter, which is dimensioned such that it converts only a small part of the fuel when fuel is subsequently injected. This oxidation catalytic converter is preferably inserted in front of or just behind the turbocharger in the exhaust line of the diesel engine. Due to its position close to the engine, it reaches its operating temperature very quickly and can thus reduce some of the CO and HC emissions during the cold start. Because of its small volume, however, it can no longer convert the hydrocarbons that are additionally introduced and not completely burnt during a regeneration of the particle filter by post-injection, so that the majority of the subsequently injected fuel reaches the particle filter and there by contact with the oxidation function of the catalytic converter Coating is burned.

To produce the catalytic coating of the filter, the described, Oxygen-storing materials to form a preferably aqueous coating suspension sion processed. The filters are then on the later entry side for the exhaust gas  coated with this suspension using known methods. The Suspen sion is then dried and calcined. The platinum group metal or metals can do this even before preparing the coating suspension on the oxygen storing material are deposited or in the form of soluble precursor compound Cations of the aqueous coating suspension are added. Alternatively, the platinum group metals only after the coating has been completed by a subsequent impregnation with a solution of the precursor compounds in the Be layering. After impregnation, the filter body be dried again and calcined.

The following examples and Fig. 1 serve for further explanation . Fig. 1 shows a cross section through a wall flow filter ( 1 ). The exhaust gas enters at the inlet end face ( 2 ) of the filter and exits again at the outlet end face ( 3 ). The filter is traversed from the inlet end surface to the outlet end surface by parallel flow channels ( 6 ) and ( 7 ) for the exhaust gas, which are delimited by porous channel walls ( 4 ). The channels are mutually closed by plugs ( 5 ). The channels ( 7 ) are closed on the entry side and the channels ( 6 ) on the exit side. The exhaust gas enters the channels ( 6 ) and is forced to pass through the porous channel walls into the adjacent channels ( 7 ). The filter is coated on the inlet side with the catalytic coating, ie the coating ( 8 ) is located on the channel walls of the channels ( 6 ). The channel walls of the channels ( 7 ) have no coating.

The filter inlet temperature is measured in the following examples. For this purpose, a thermocouple ( 9 ) is brought into a flow channel ( 7 ) from the gas outlet side of the filter from behind to a sealing plug ( 5 ).

example 1

The lowering of the soot ignition temperature was investigated by means of various catalytic coatings. For the investigations, cylindrical wall flow filters according to FIG. 1 made of silicon carbide with a cell density (number of flow channels per cross-sectional area of the filter) of 31 cm ^-2 , a length of 15.2 cm and a diameter of 14.4 cm (volume approx . 2.5 l) used.

The coatings contained platinum as an oxidation-active component. The Beschich tion concentration was 50 g / l filter body and the platinum concentration each because 5.3 g / l. Coatings made of stabilized cerium oxide, calcium oxide, Manganese oxide and from the oxide mixtures cerium oxide / manganese oxide (1: 1) and  Cerium oxide / manganese oxide / calcium oxide (4: 4: 2) examined. The oxidic materials were the first by impregnating with hexachloroplatinic acid with the necessary men Platinum coated, dried and calcined in air at 500 ° C. To coat the Filter bodies, the catalyzed oxide powders were suspended in an amount of water, that corresponded to the previously determined water absorption capacity of the filter body. This Suspensions were carefully ground and then over the entry face of the Cast filter body. The filter bodies were then dried and calcined.

Instead of the soot ignition temperature, the filter inlet temperature at the start of soot burn-up was determined on the filters thus prepared. For this purpose, a thermocouple ( 9 , Fig. 1) was pushed from behind into a flow channel sealed on the inlet side behind the sealing plug. In addition, the exhaust gas back pressure of the filter was monitored.

Each filter was first used on a 2.2 l diesel engine (with direct injection) Load defined operating conditions with about 8 g of soot. Then the Regenera tion of the filter by enriching the exhaust gas stream with hydrocarbons tet. By burning these hydrocarbons on the catalytic coating the temperature of the filter rose. At the same time increased by the increasing temperature also the exhaust gas back pressure. When a certain one is reached The soot burn-off started at the filter inlet temperature, which could be seen from the fact that the exhaust backpressure went through a maximum and then to the value before the Filters with soot fell back. The filter inlet temperature at the time of passage fens the maximum of the exhaust gas back pressure was registered and is for the various filter coatings listed in Table 1 below.

Table 1

Filter inlet temperatures at the start of soot burn-up

Example 2

The conversion for carbon monoxide CO, hydrocarbons HC and nitrogen oxides NOx and its filtration efficiency for PM particles were also determined in an MVEG test on the filter coated with Pt / CeO ₂ . The results are shown in Table 2. The second line of Table 1 shows the engine's raw emissions. Line 3 shows the emissions by particle filter and line 4 contains the calculated degrees of implementation for these pollutants.

Table 1

With the particle filter catalyzed according to the invention it is possible to both coal monoxide, hydrocarbons and also the soot particles to a considerable extent duce.

Claims (21)

1. A method for reducing carbon monoxide, hydrocarbons and soot particles in the lean exhaust gas of an internal combustion engine using a particle filter, wherein the soot particles have a soot ignition temperature T _Z and the particle filter from time to time by raising the temperature of the particulate filter above the soot ignition temperature and burning the soot particles is regenerated, characterized in that the particle filter is provided with a catalytic coating, which probably contains a component that reduces the ignition temperature T _{Z of} the carbon black and a component for the oxidation of carbon monoxide and hydrocarbons, the temperature of the filter being reached when a Predeterminable exhaust gas back pressure is increased by burning additional fuel on the catalytic coating to the temperature necessary for the ignition of the soot combustion. 2. The method according to claim 1, characterized, that to reduce the ignition temperature of the soot at least one oxygen storage component and for the oxidation of carbon monoxide and carbon Hydrogen at least one of the platinum group metals platinum, palladium and Rhodium is present in the catalytic coating. 3. The method according to claim 2, characterized, that the oxygen-storing component at least one material from the Group cerium oxide, cerium / zirconium mixed oxide and manganese oxide or mixtures thereof contains. 4. The method according to claim 3, characterized, that the catalytic coating additionally contains an alkaline earth metal oxide.   5. The method according to claim 4, characterized, that the catalytic coating additionally has at least one oxidic support material from the group active aluminum oxide, silicon dioxide, titanium oxide and Contains zirconium oxide or mixed oxides thereof. 6. The method according to claim 1, characterized, that the catalytic coating in a concentration of 20 to 150 g / l Fil body is present and the concentration of the platinum group metal or metals 0.5 up to 10 g / l filter body. 7. The method according to claim 6, characterized, that the particle filter is a wall flow filter made of silicon carbide, Cor dierite or sodium zirconium phosphate. 8. The method according to claim 7, characterized, that only the inlet side of the wall flow filter with the catalytic coating is provided. 9. The method according to claim 1, characterized, that the additional fuel required for heating the particle filter Exhaust gas stream is added before the particle filter. 10. The method according to claim 1, characterized, that the additional fuel required to heat the particulate filter inserted into the cylinders of the internal combustion engine during the expansion phase is injected. 11. The method according to claim 10 characterized, that the particle filter an oxidation catalyst in the engine near position is switched, which is dimensioned so that it only a small part of the additional injected fuel converted.   12. Particulate filter for the reduction of soot particles in the lean exhaust gas from internal combustion engines, which have an ignition temperature T _Z , characterized in that the particle filter is provided with a catalytic coating, which is probably an ignition temperature T _{Z of} the soot reducing component as well as a Contains component for the oxidation of carbon monoxide and hydrocarbons. 13. Particulate filter according to claim 12, characterized, that to reduce the ignition temperature of the soot at least one oxygen storage component and for the oxidation of carbon monoxide and carbon Hydrogen at least one of the platinum group metals platinum, palladium and Rhodium is present in the catalytic coating. 14. Particulate filter according to claim 12, characterized, that the oxygen-storing component at least one material from the Group cerium oxide, cerium / zirconium mixed oxide and manganese oxide or mixtures thereof contains. 15. Particulate filter according to claim 14, characterized, that the catalytic coating additionally contains an alkaline earth metal oxide. 16. Particulate filter according to claim 15, characterized, that the catalytic coating additionally has at least one oxidic support material from the group active aluminum oxide, silicon dioxide, titanium oxide and Contains zirconium oxide or mixed oxides thereof. 17. Particulate filter according to claim 12, characterized, that the catalytic coating in a concentration of 20 to 150 g / l Fil body is present and the concentration of the platinum group metal or metals 0.5 up to 10 g / l filter body.   18. Particulate filter according to claim 12, characterized, that the particle filter is a wall flow filter made of silicon carbide, Cor dierite or sodium zirconium phosphate. 19. Particle filter according to claim 18, characterized, that only the inlet side of the wall flow filter with the catalytic coating is provided. 20. Drive unit for a motor vehicle containing a diesel engine and an exhaust gas purification system with a particle filter, the exhaust gas temperature of the engine for regeneration of the particle filter can be increased by post-injection of fuel into the cylinder of the diesel engine during the expansion phase, characterized in that the particle filter with a catalytic Coating is provided, which contains a component that reduces the ignition temperature T _{Z of} the soot and also a component for the oxidation of carbon monoxide and hydrocarbons. 21. Drive unit according to claim 20, characterized, that the particle filter an oxidation catalyst in the engine near position is switched, which is dimensioned so that it is with post-injection of fuel only a small fraction of the fuel is converted.