JP2003227329A - Particulate purifying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particulate purifying device capable of collecting most of particulate (PM) in cell pores by restraining the PM from accumulating on a surface of cell partition walls as a layer. <P>SOLUTION: A gas is blown to the cell partition walls from a downstream side of a diesel particulate filter formed on a coat layer containing a catalyst metal in a pulsing manner for a short period of time to break the PM accumulated on the cell partition walls off the cell partition walls and the removed PM is collected in the cell pores in the cell partition by the pressure of exhaust gas. As the most of PM can be collected in the cell pores in the cell partition, the contacting rate of PM and the catalyst metal and the heat retaining property are high and the oxidative reaction of the PM can smoothly proceed. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate matter contained in exhaust gas from a diesel engine (particulate matter: carbon fine particles, sulfur-based fine particles such as sulfate, high molecular weight carbonized). The present invention relates to a PM purification device that collects hydrogen fine particles and the like (hereinafter, abbreviated as PM) and regenerates the PM by burning and removing the collected PM by the action of a catalyst. [0002] Regarding gasoline engines, harmful components in exhaust gas have been steadily reduced due to strict regulations on exhaust gas and advances in technology capable of responding to the strict regulations. However, with respect to diesel engines, regulations and technological advances are slower than gasoline engines due to the unique circumstances that harmful components are emitted as PM. [0003] As exhaust gas purifying devices for diesel engines that have been developed to date, trap type exhaust gas purifying devices and open type exhaust gas purifying devices are known. Among them, as a trap type exhaust gas purifying device, a plugged honeycomb body made of ceramic (diesel PM filter (hereinafter, referred to as DPF)) is known. In this DPF, the downstream end of the cell on the inlet side of the ceramic honeycomb structure is plugged in a checkered pattern, and the upstream end of the adjacent cell on the outlet side is plugged in a checkered pattern. The exhaust gas is filtered through the pores of the partition walls and the PM is collected on the cell partition walls to suppress the emission. [0004] However, in the DPF, since the pressure loss increases due to the deposition of PM, it is necessary to periodically remove the PM deposited by some means and regenerate it. Therefore, conventionally, when the pressure loss increases, the DPF is regenerated by burning the deposited PM with a burner or an electric heater or the like. However, in this case, as the amount of deposited PM increases, the temperature at the time of combustion rises, and the resulting thermal stress causes D
The PF may be damaged. In recent years, a continuous regeneration type DPF has been developed in which a coat layer is formed from alumina or the like on the cell partition walls of the DPF, and the coat layer carries a catalytic metal such as a platinum group noble metal. According to this continuous regeneration type DPF, the PM trapped in the pores of the cell partition walls is oxidized and combusted by the catalytic reaction of the catalytic metal, so that the DPF is burned simultaneously with or continuously with the trapping. Can be played. Further, since the catalytic reaction occurs at a relatively low temperature and can be burned while the trapping amount is small, there is an advantage that thermal stress acting on the DPF is small and breakage is prevented. As such a continuous regeneration type DPF, for example, Japanese Patent Application Laid-Open No. 9-220423 discloses that the porosity of a cell partition is 40 to 40%.
65%, the average pore diameter is 5 to 35 μm, and the porous oxide constituting the coat layer has a particle diameter smaller than the average pore diameter of the cell partition walls and occupies 90 wt% or more. ing. By coating with such a porous oxide having a high specific surface area, a coat layer can be formed not only on the surface of the cell partition but also on the inner surface of the pores. Further, if the coating amount is constant, the coating thickness can be reduced, so that an increase in pressure loss can be suppressed. [0007] In a situation where PM is trapped in the pores of the cell partition walls, the probability of contact between the PM and the catalyst metal is high and the heat retention is high, so that the oxidation reaction of the PM proceeds smoothly. Further, since the pressure loss increases sensitively with the collection of PM, the amount of accumulated PM can be estimated by detecting the pressure loss. Therefore, when the pressure loss exceeds the reference value, by performing a regeneration process such as flowing high-temperature exhaust gas, PM can be burned with a deposition amount within the reference amount, and the continuous regeneration type DPF becomes hot during combustion. Can be prevented. However, when the temperature is low or when the condition that a large amount of PM is discharged continues, the PM is deposited in a layer along the cell partition. Once the deposition starts, the surface of the deposition layer does not come into contact with the catalytic metal, so that the oxidation rate of PM is reduced and the surface deposition further proceeds, resulting in an extremely large deposition amount. Therefore, when the exhaust gas temperature rises, the accumulated PM
However, there is a problem that the continuous regeneration type DPF is heated at a high temperature and the catalyst metal grows and deteriorates due to grain growth, or melting occurs. On the other hand, P deposited in layers on the surface of the cell partition
Since M is oxidized only at the interface with the cell partition under normal conditions, voids are generated between the deposited layer and the cell partition, and the degree of reduction in pressure loss with an increase in the amount of deposition is small. Therefore, the method of detecting the pressure loss and estimating the amount of accumulated PM has a disadvantage that the difference between the estimated amount of accumulated PM and the actual amount of accumulated PM is large. Japanese Patent Application Laid-Open No. Hei 6-46863 discloses that high-pressure air is injected from the downstream side of a catalyst filter so that P
An exhaust gas purifying apparatus is described in which M is desorbed from a catalyst filter, dropped into a combustion chamber, and incinerated by a heater. Japanese Patent Application Laid-Open No. 7-229417 discloses a filter used in the exhaust gas purifying apparatus, in which the pressure wave of high-pressure air easily enters the cell passage, and the PM is more easily dropped off by the impact of the pressure wave. Is described. However, according to the technology described in the above publication,
Since the PM collected by the filter is collected again in the combustion chamber, a backwash nozzle, a combustion chamber, and a heater are required, and there is a problem that the system is complicated and a large space is required. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses the deposition of PM on the surface of a cell partition in a layered manner, thereby reducing PM in exhaust gas. It is an object of the present invention to allow most of the trapping in the pores of the cell partition. [0013] The PM purifying apparatus of the present invention which solves the above-mentioned problems is characterized in that the cells on the inlet side of the ceramic honeycomb structure are sealed at the downstream end and the inlet. Filter body having an outlet side cell adjacent to the side cell and the upstream end of the cell is plugged, a coat layer made of a porous oxide formed on the cell partition wall, and carried on the coat layer A DPF with a catalyst, which is made of a catalytic metal, passes exhaust gas from the cell on the inlet side to the cell of the cell partition, flows exhaust gas into the adjacent cell on the outlet side, and oxidizes and burns the particulates collected in the cell partition by the catalytic metal. , With catalyst D
Gas supply means for pulsating gas from the downstream side of the PF in a short time to the cell partition to cause PM deposited on the cell partition to float from the cell partition; and It is to collect in the hole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The PM purifying apparatus of the present invention has a DPF with a catalyst and gas supply means. The gas supply means blows the gas from the downstream side of the catalyst-added DPF to the cell partition wall in a pulsed manner for a short time. As a result, the PM deposited on the surface of the cell partition wall rises momentarily from the cell partition wall, and is crushed into a layered PM as discrete PM particles and floats in the cell on the entrance side. When the supply of the gas from the gas supply unit is stopped, the suspended PM is carried into the cell partition by the exhaust gas, and is trapped in the pores of the cell partition. Therefore, according to the PM purifying apparatus of the present invention, most of the PM can be trapped in the pores of the cell partition walls, so that the probability of contact between the PM and the catalytic metal is high and the heat retention is high. Therefore, the oxidation reaction of PM proceeds smoothly. Further, since the pressure loss increases sensitively with the collection of PM, the amount of accumulated PM can be estimated by detecting the pressure loss. Therefore, when the pressure loss exceeds the reference value, by performing a regenerating process such as flowing high-temperature exhaust gas, it is possible to burn PM with a small amount of deposition.
Can be prevented from becoming high temperature. The filter body has a downstream end portion of a cell on the inlet side of the ceramic honeycomb structure plugged, and an upstream end portion of an adjacent cell on the outlet side plugged. The cells on the inlet side are plugged on the downstream side, the cells on the outlet side are plugged on the upstream side, and the cells on the inlet side and the cells on the outlet side are adjacent. The cell partition partitions the cell on the entrance side and the cell on the exit side. This filter body can be manufactured from a heat-resistant ceramic such as cordierite. For example, a clay-like slurry containing cordierite powder as a main component is prepared, molded by extrusion or the like, and fired to obtain a honeycomb structure. Instead of the cordierite powder, alumina, magnesia, and silica powders may be blended so as to have a cordierite composition. Thereafter, the cell openings on one end face of the honeycomb structure are plugged in a checkered pattern with a similar clay-like slurry, and the other end face is plugged with a cell opening of a cell adjacent to the cell plugged on one end face. Thereafter, the filter body is manufactured by fixing the plugging material by baking or the like. To form pores in the cell partition walls of the filter body, combustible powders such as carbon powder, wood powder, starch, and resin powder are mixed in the above slurry, and the combustible powder is fired. At times, the pores can be formed by disappearing. The cells on the inlet side and the cells on the outlet side communicate with each other by these pores, and PM is trapped in the pores, but gas can pass through the pores from the inlet side cells to the outlet side cells. A coating layer made of a porous oxide is formed on the cell partition walls of the filter body. This coat layer serves as a carrier for supporting the catalyst metal, and includes Al ₂ O ₃ , Zr
It can be formed from an oxide such as O ₂ , CeO ₂ , TiO ₂ , SiO ₂ or a composite oxide composed of a plurality of these. It is desirable that the coating layer is formed not only on the surface of the cell partition but also on the surface inside the pores. To form the coat layer in this manner, for example,
As described in JP-A-9-220423, it is preferable to use an oxide powder or a composite oxide powder in which particles having a particle size smaller than the average pore diameter of the cell partition occupy 90% by weight or more. When the number of particles having a particle diameter larger than the average pore diameter is more than 10% by weight, it becomes difficult to form a coat layer on the surface in the pores, and it becomes difficult to oxidize and burn PM that has entered the pores. Although the amount of the coating layer depends on the cell diameter of the filter body, it is preferable that the thickness be in the range of 1 to 20 μm or in the range of 60 to 200 g per liter of volume of the filter body. If the formation amount of the coat layer is less than this range, the catalyst metal is supported at a high density, and when exposed to a high temperature, the catalyst metal may grow and the activity may be reduced. On the other hand, if the amount of the coating layer is larger than this range, the pressure loss increases and the diameter and opening area of the pores decrease. In order to form a coat layer, an oxide powder or a composite oxide powder is made into a slurry together with a binder component such as alumina sol and water, and the slurry is applied to the cell partition walls and then fired. A normal dipping method can be used to attach the slurry to the cell partition walls, but it is desirable to remove excess slurry that has entered the pores by air blowing or suction. The catalyst metal is supported on the coat layer.
As the catalyst metal, any metal can be used as long as it promotes the oxidation of PM by a catalytic reaction, but Pt, Rh,
It is particularly preferable to carry one kind selected from platinum group noble metals such as Pd, and one kind or plural kinds selected from Ag or base metal. The amount of catalyst metal carried is determined by the filter body 1
It is preferred to be in the range of 0.5 to 10 g per liter. If the amount is less than this, the activity is too low to be practical, and if the amount is more than this range, the activity is saturated and the cost is increased. Alkaline earth metals such as Ba, Ca, and Sr, alkali metals such as Na, K, Li, and Cs;
Or selected from rare earth elements such as La, Nd, Sc, and Y
It is also preferable to further carry a NOx storage material. _The NO _x storage and release capacity by carrying _the NO _x storage material is expression, improves _the NO _x purification performance. The loading amount of _the NO _x storage material is preferably in the range of 0.01 to 2 mol per filter body liter. If the supported amount is smaller than this, the NO _x storage / release capability is not exhibited, and if the supported amount is larger than this, the catalytic metal such as Pt is covered and the oxidizing capability is reduced. In order to support the catalyst metal and the NO _x storage material,
Using a solution obtained by dissolving such a nitrate of the catalytic metal or _the NO _x storage material, adsorption supporting method, it may be supported on the coat layer, such as by water absorption supporting method. The advance carries a pre-catalytic metal oxide powder or a composite oxide powder may be carrying the _the NO _x storage material after forming the coating layer using the catalyst powder. The gas supply means blows the gas from the downstream side of the DPF with a catalyst in a pulsed manner to the cell partition for a short time, and may supply a gas having a pressure higher than the pressure of the exhaust gas. If the supply of gas is stopped, a gas having a pressure lower than the pressure of the exhaust gas can be supplied. As the supplied gas, compressed air or the like may be used,
Exhaust gas can also be used. In order to pulsately spray the cell partition walls in a short time, a method of controlling an injection nozzle, a method of controlling switching of a valve as described in an embodiment to be described later, or the like can be adopted. The gas is sprayed when a predetermined amount of PM is deposited on the surface of the cell partition.
For example, PM deposition amount is 2g per liter of filter body
If the spraying is performed at the time, the amount of PM deposited in a layer on the surface of the cell partition wall is considered to be about 1 g, and the PM can be easily floated by the spraying. It is desirable that the time of spraying be within one second. If the spraying time is longer than this, the lifted PM starts to move upstream in the cell on the inlet side, so it is not necessary to supply the gas so long, and the trouble due to obstruction of the exhaust gas flow increases. I will. Of the gas blown from the downstream side, the gas that has advanced into the outlet side cell and entered the plugged portion on the inlet side end surface enters the inlet side cell from the cell partition wall near the plugged portion. As a result, the PM accumulated outside the opening of the entrance-side cell can also be lifted. Therefore, it is possible to prevent the opening of the entrance-side cell from being closed. When the blowing of the gas is stopped, the PM floating up from the surface of the cell partition and being separated and floating in the cell on the inlet side is transported again by the exhaust gas to the cell partition, and a certain part is removed from the cell partition. , But are mostly trapped in the pores of the cell partition. Therefore, the contact probability with the catalyst metal is increased, and the catalyst metal is easily oxidized and burned. The present invention will be described below in detail with reference to examples. FIG. 1 shows the structure of a PM purifying apparatus according to this embodiment. In this PM purification device, a DPF 1 with a catalyst is disposed in an exhaust gas passage 2 of a diesel engine. The exhaust gas flow path 2 is branched into two flow paths including a first flow path 20 and a second flow path 21 on the upstream side of the DPF 1 with a catalyst, and the DPF 1 with a catalyst is arranged in the first flow path 20. The second flow path 21 is a DPF with a catalyst.
1 and a first flow path 20 downstream of the DPF 1 with a catalyst.
And is connected to the exhaust pipe 22 again. Second flow path 21
The opening at the downstream end of the DPF 1 is opposed to the gas-exiting end face of the DPF 1 with catalyst, and the exhaust gas can be injected toward the gas-exiting end face of the DPF 1 with catalyst. A switching valve 3 is disposed at a branch point between the first flow path 20 and the second flow path 21, and the exhaust gas is switched between the first flow path 20 and the second flow path 21 by a control device (not shown). It is configured to flow. An exhaust brake valve 4 is disposed in the exhaust gas passage 2 on the upstream side of the switching valve 3 to enable a brake operation by an exhaust brake device (not shown). The DPF 1 with a catalyst shown in FIG. 2 has a honeycomb-shaped filter body 10 made of cordierite and having a plurality of cells, and Al ₂ O ₃ formed on the surface of pores 12 of cell partition walls 11 of the filter body 10. Coat layer 13 comprising Pt
It is composed of Further, the filter body 10 has plugging portions 14 alternately plugged at the downstream end of the cell on the inlet side and the upstream end of the cell on the outlet side adjacent thereto. Hereinafter, a method of manufacturing the DPF 1 with a catalyst will be described, and the detailed description of the structure will be replaced. Al ₂ O ₃ powder adjusted to a particle size of 10 to 15 μm,
Using MgO powder and SiO ₂ powder as cordierite (2MgO.2Al ₂
O ₃ · 5SiO ₂ ) The composition is adjusted to have the composition, and the average particle size is 15 μm.
Was added so that the volume of the carbon powder was 25% by volume, and the volume of the carbon powder having an average particle size of 30 μm was 15% by volume, and then water was added and kneaded to prepare a clay-like slurry. This slurry is extruded using a predetermined extrusion fitting to form a honeycomb-shaped formed body.
By firing at 00 ° C., a honeycomb structure having a cordierite composition was formed. Using a clay-like slurry containing cordierite powder as a main component, the cell openings on one end face of the honeycomb structure are plugged in a checkered pattern, and the cell openings not plugged on one end face are plugged on the other end face. The filter body 10 was prepared by baking it. Next, 48% by weight of Al ₂ O ₃ powder having an average particle size of 1 μm, 40% by weight of TiO ₂ powder having an average particle size of 0.5 μm, and
0.5 μm CeO ₂ powder 10% by weight and alumina sol (Al ₂ O ₃
A slurry containing 20% by weight) was prepared, the filter body 10 was immersed, pulled up, vacuum-sucked to remove excess slurry, dried at 120 ° C and baked at 500 ° C for 60 minutes to form a coat. Layer 13 was formed. About 80 g of the coat layer 13 was formed per liter of the volume of the filter body 10. Then, a predetermined amount of an aqueous solution of dinitrodiammineplatinum having a predetermined concentration was absorbed in the coating layer 13, dried at 120 ° C., and baked at 500 ° C. for 60 minutes to carry Pt. 2 g of Pt was carried per liter of the volume of the filter body 10. DPF with catalyst prepared as described above
1 is disposed in the first flow path 20 as shown in FIG. 1 and the diesel engine is driven so that the temperature of the gas entering the DPF 1 with a catalyst becomes 3
The temperature was adjusted to 50 ° C. It has been found that the amount of PM in the exhaust gas from the diesel engine under this condition is 3.1 g / hr. Under these conditions, under the control of the switching valve 3, the exhaust gas always flows through the first flow path 20, and the switching valve 3 is switched when the amount of accumulated PM reaches 2 g per liter of the volume of the filter body 10. The high-pressure exhaust gas (0.5 MPa) immediately after the release of the exhaust brake was controlled to flow through the second flow path 21 in a pulsed manner for one second. As shown by the arrow in FIG. 1, the exhaust gas flowing through the second flow path 21 is blown toward the outlet side end face of the DPF 1 with catalyst, and is discharged from the outlet side cell to the cell partition 11.
Flows into the inlet-side cell through the fine pores 12. Since PM5 is deposited on the surface of the cell partition 11 as shown in FIG. 3, the layered PM5 is lifted by the high-pressure exhaust gas flowing out of the cell partition 11, and the lifted PM is separated due to the destruction of the layered structure. Float in the outlet cell. After flowing the high-pressure exhaust gas through the second flow path 21 for one second, the switching valve 3 is switched to re-exhaust the exhaust gas into the first flow path 20.
Pour As a result, PM floating in the outlet cell
Enters the pores of the cell partition 11 on the flow of the exhaust gas,
As shown in FIG. 4, it is trapped in the pores 12 of the cell partition 11. PM5 trapped in the pores 12 of the cell partition walls 11 has a high contact probability with Pt carried on the coat layer 13 formed on the peripheral wall of the pores 12, so that it is easily oxidized and burned at the exhaust gas temperature. Is done. After operating continuously for 5 hours under the above conditions, the catalyst-added DPF 1 was taken out and the weight of the deposited PM was measured. Then, the amount of burned PM is calculated from the total amount of PM in the circulated exhaust gas and the weight of the deposited PM, and the PM oxidation rate per liter of volume of the filter body 10 is calculated. The result is shown in FIG. Yes ". The PM oxidation rate was measured in exactly the same manner as described above except that the gas temperature was set at 400 ° C., and the results are shown in FIG. Further, the switching valve 3 was fixed, and the PM oxidation rate at the inlet gas temperatures of 350 ° C. and 400 ° C. was measured in exactly the same manner as above except that the exhaust gas was flown only through the first flow path 20. 5 is also shown as “No reverse injection”. It is apparent from FIG. 5 that the PM oxidation rate is greatly improved by pulsating the high-pressure exhaust gas toward the outflow end face of the DPF 1 with a catalyst. This is probably because PM was trapped in the pores 12 to increase the contact area with Pt. Further, the diesel engine is driven such that the temperature of the gas entering the DPF 1 with the catalyst becomes 300 ° C., and the exhaust gas is always caused to flow through the first flow path 20 by controlling the switching valve 3.
The amount of deposited PM is 4 per liter of volume of the filter body 10.
The switching valve 3 was switched at the time when the pressure became g and 6 g, and the high-pressure exhaust gas (0.5 MPa) immediately after the release of the exhaust brake was pulsed through the second flow path 21 for 1 second. And D with catalyst
The differential pressure of the exhaust gas on the upstream side and the downstream side of the PF1 is continuously measured, and the result is shown in FIG. 6 as a pressure loss. Switching valve 3
, And the differential pressure was measured in the same manner except that the exhaust gas was allowed to flow only through the first flow path 20, and the results are shown in FIG. 6 as pressure loss. As shown in FIG. 6, when exhaust gas flows only through the first flow path 20, the pressure loss is saturated at a relatively low value. However, when the high-pressure exhaust gas is blown in a pulsed manner toward the outflow end face of the DPF 1 with a catalyst, it is presumed that the pressure loss sharply decreases with each blow, and the PM deposited in a layer form floats. Then, as the amount of trapped PM increases, the pressure loss increases sensitively without saturating, and the pressure drop detection sensitivity is improved. Therefore, the amount of deposited PM can be estimated by detecting the pressure loss. When the pressure loss exceeds the reference value, by performing a regeneration process such as flowing high-temperature exhaust gas, the PM can be reduced with a small amount of deposited PM. Can be burned. Thus, it is possible to prevent the continuous regeneration type DPF from becoming high temperature during combustion. According to the PM purifying apparatus of the present invention, most of the PM in the exhaust gas can be collected in the pores of the cell partition. Therefore, the contact area with the catalyst metal supported on the coat layer on the peripheral wall of the pores increases, and the PM combustion efficiency is improved. Therefore, deterioration of the catalyst metal due to rapid combustion of a large amount of PM can be prevented, and the filter body can be prevented. Can be reliably prevented from being damaged or melted. Further, since the pressure loss detection sensitivity is improved, the regeneration of the DPF with a catalyst can be performed more reliably.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a configuration of a PM purification device according to one embodiment of the present invention. FIG. 2 is a sectional view of a main part of a DPF with a catalyst used in a PM purification device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view of a main part showing a state in which PM is deposited in a layer on a DPF with a catalyst used in the PM purification device according to one embodiment of the present invention. FIG. 4 is a cross-sectional view of a main part showing a state in which PM is trapped in pores of a DPF with a catalyst used in the PM purification device of one embodiment of the present invention. FIG. 5 is a graph showing a PM oxidation rate in the PM purification device of the embodiment. FIG. 6 is a graph showing a pressure loss change in the PM purification device of the example. [Explanation of Signs] 1: DPF with catalyst 2: Exhaust gas flow path 3: Switching valve 10: Filter body 11: Cell partition 12: Pores 13: Coating layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B01D 46/42 B01D 53/36 103C F-term (reference) 3G090 AA03 BA01 CA01 CA04 CB23 CB24 DA04 4D048 AA14 AB01 BA03X BA14Y BA15Y BA19X BA30X BA31Y BA33Y BA41X BB02 BB14 CC16 CC25 CC26 CD05 EA04 4D058 JA32 JB06 MA15 MA44 SA08 4G069 AA03 BA01A BA01B BA13A BA13B BB02A BB02CA03BCA BCA BCBC BCA BCBC BC BC BC BC BC

Claims (1)

Claims: 1. An inlet cell having a downstream end plugged with a ceramic honeycomb structure cell, and an upstream end of the cell adjacent to the inlet cell being plugged. A filter body having an outlet-side cell formed thereon, a coat layer made of a porous oxide formed on the cell partition wall, and a catalyst metal supported on the coat layer. A DPF with a catalyst that allows exhaust gas to flow through the pores of the cell partition and flows into the adjacent cell on the outlet side and oxidizes and burns the particulates collected by the cell partition with the catalyst metal; and from the downstream side of the DPF with the catalyst Gas supply means for pulsating gas in a short period of time onto the cell partition walls to cause the particulates deposited on the cell partition walls to float from the cell partition walls, and the floating particulates are discharged at a pressure of the exhaust gas. Purifying the particulates apparatus characterized by collecting in the pores of the cellular walls.