JP2003001067A - Exhaust gas purifying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas purifying apparatus by which particulate (PM) and nitrogen oxides (NOx) in an exhaust gas is removed at a high NOx removal rate while evading sulfur poisoning that is a weak point of NOx storage reduction type catalyst. SOLUTION: In the exhaust gas purifying apparatus provided with a wall flow type filter 4 provided in an exhaust passage 3 of an engine 2 and for purifying the particulate in the exhaust gas G, an oxidation catalytic layer 20 supporting an oxidation catalyst 21 is provided on the upstream part of a porous wall surface 30 of the filter 4 and a nitrogen oxide purifying catalyst layer 40 supporting the nitrogen oxide storage reduction type catalyst 41 containing a nitrogen oxide storage material 41a and an oxidation catalyst 41b is provided on the downstream side part of the porous wall surface 30 of the filter 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas for purifying particulate matter and nitrogen oxides in exhaust gas of a diesel engine or the like with a diesel particulate filter and a nitrogen oxide occlusion reduction type catalyst carried by the filter. The present invention relates to a purification device.

[0002]

2. Description of the Related Art The amount of particulate matter (PM: particulate matter: hereafter PM) emitted from a diesel engine is the amount of nitrogen oxides (hereafter NOx), carbon monoxide (hereafter C).
O) and hydrocarbons (hereinafter referred to as HC), etc., and regulations have been tightened year by year, and it is no longer possible to comply with these regulations only by improving the engine. A technology to reduce these substances by an exhaust gas aftertreatment device has been developed. ing.

For collecting PM, a diesel particulate filter (DPF: Diesel Particulate Fil) is used.
ter: DPF), which collects this PM
Has researched and proposed a wall-flow type filter of a porous cordierite or a monolith honeycomb made of ceramics, a fiber laminated type filter in which ceramics or metals are randomly laminated into fibers.

[0004] In the PM collecting DPF, the clogging progresses as the PM is collected and the exhaust gas pressure (exhaust pressure) rises as the amount of collected PM increases. P
Although it is necessary to remove M, recently, a filter with a catalyst in which an oxidation catalyst that promotes the removal of PM by oxidation is applied on the wall surface of a wall flow type filter is used to collect PM and oxidize the collected PM. A continuous regeneration type diesel particulate filter that continuously removes has been proposed.

The oxidation catalyst carried on this filter is
A catalyst that oxidizes nitric oxide (NO) in exhaust gas to nitrogen dioxide (NO ₂ ) and PM directly from low temperature to oxygen (O 2
_There are PM oxidation catalysts (noble metal oxidation catalysts and oxide oxidation catalysts) that are oxidized in ₂ ).

On the other hand, as for NOx purification, there is a NOx reduction catalyst as one of the means.
No. 82852 discloses an exhaust purification device in which the engine side of the wall surface of a wall flow type filter is coated with a NOx reduction catalyst layer and an oxidation catalyst layer, and an oxidation catalyst on the engine side of the wall surface of the wall flow type filter, and an exhaust outlet side. An exhaust emission control device has been proposed in which each NOx reduction catalyst layer is coated.

In these exhaust emission control devices, a filter, an oxidation catalyst layer such as a noble metal-based catalyst, and NO such as a zeolite-based catalyst are used.
The x reduction catalyst layer is integrated to reduce the size and weight of the device, and by devising the arrangement of the oxidation catalyst layer and the NOx reduction catalyst layer, the combustion of PM by the oxidation catalyst is promoted and NOx due to the adhesion of PM to the NOx reduction catalyst. The reduction in reduction efficiency is avoided, and the thermal effect on the NOx reduction catalyst during PM combustion during filter regeneration is reduced to prevent deterioration of the NOx reduction catalyst.

[0008]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In these exhaust gas purification devices proposed in Japanese Patent Publication No. 000-282852, since a NOx reduction catalyst is used for NOx purification, it is necessary to constantly supply a reducing agent such as hydrocarbon for NOx reduction. Therefore, a reducing agent supply device for supplying this reducing agent is required.

When the fuel for the engine is diverted to the reducing agent, there is a problem that an injection valve and a pipe for injecting the fuel into the exhaust passage are required and that fuel consumption is deteriorated. When using ammonia or urea other than engine fuel, in addition to the injection valve and piping, tanks for these reducing agents are required, and these reducing agents are used as appropriate for reducing agent tanks. There is a problem that it needs to be replenished.

If it is necessary to install the reducing agent supply system to the exhaust passage, the work for mounting the exhaust gas device on an existing vehicle becomes troublesome, so that the cost is increased in terms of the man-hours in terms of the device. Therefore, there is a problem that practical application becomes difficult.

Further, in particular, since the oxidation catalyst is arranged on the upstream side of the NOx reduction catalyst which requires a reducing agent, when the reducing agent is light oil, it is decomposed by the oxidation catalyst and has a low molecular weight with good NOx reduction efficiency. Become hydrocarbons, and also SOF
It is said that (soluble organic components) are also decomposed to effectively reduce NOx as a reducing agent, but when the oxygen concentration in the exhaust gas is high as in the normal combustion state of a diesel engine, it is supplied into the exhaust passage. It is considered that the reduced reducing agent has a high possibility of being oxidized by the oxidation catalyst on the upstream side, the NOx reduction efficiency is lowered, and the fuel efficiency is deteriorated.

On the other hand, one of the catalysts for removing NOx in the exhaust gas is a NOx occlusion reduction type catalyst. This N
The Ox occlusion reduction type catalyst carries an NOx occlusion substance such as barium having an NOx occlusion function and an active catalytic metal (oxidation catalyst) such as platinum having an oxidation catalyst function, and NOx occlusion is performed depending on the oxygen concentration in the exhaust gas. It is a catalyst that fulfills the functions of NOx release and reduction purification.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an oxidation catalyst on the upstream side of the DPF filter and an NOx storage reduction type catalyst on the downstream side. An object of the present invention is to provide an exhaust gas purification device that is capable of purifying PM and NOx in exhaust gas at a high NOx purification rate while avoiding sulfur poisoning, which is a weak point of the NOx storage reduction catalyst. .

[0014]

An exhaust gas purifying apparatus for achieving the above object is constructed as follows.

1) In an exhaust gas purification apparatus provided with a wall flow type filter for purifying particulate matter in exhaust gas, which is provided in an exhaust passage of an engine, an oxidation catalyst is provided on an upstream side portion of a porous wall surface of the filter. And a nitrogen oxide purification catalyst layer supporting a nitrogen oxide occlusion reduction type catalyst containing a nitrogen oxide occlusion substance and an oxidation catalyst is provided on the downstream side portion of the porous wall surface of the filter. Composed.

This wall flow type filter is
Porous ceramic honeycomb channels can be formed with a monolith honeycomb, etc. in which the inlets and outlets of the channels are alternately plugged,
The oxidation catalyst layer supporting the oxidation catalyst is formed by coating platinum (Pt) or cerium oxide (Ce oxide) on the porous catalyst coat layer such as zeolite or alumina coated on the porous wall surface of the filter.
It can be formed by supporting an oxidation catalyst such as O ₂ ).

Further, the nitrogen oxide (NOx) occlusion reduction type catalyst depends on the O ₂ concentration and CO concentration in the exhaust gas.
It has the functions of occlusion and NOx release and reduction / purification, and has NOx occlusion function such as potassium (K), barium (Ba), lanthanum (La), and platinum (Pt) and rhodium (Rh). ) Etc., the NOx purification catalyst layer is formed on a porous catalyst coat layer such as zeolite or alumina coated on the porous wall surface of the filter. It can be formed by carrying, for example.

2) Alternatively, in an exhaust gas purifying apparatus having a fiber laminated type filter provided in an exhaust passage of an engine for purifying particulate matter in exhaust gas, an oxidation catalyst is provided in a fiber layer on an upstream side of the filter. Or laminating an oxidation catalyst layer supporting an oxidation catalyst, and a fiber layer on the downstream side of the filter is loaded with a nitrogen oxide occlusion reduction type catalyst containing a nitrogen oxide occlusion substance and an oxidation catalyst, or A nitrogen oxide purification catalyst layer carrying the nitrogen oxide occlusion-reduction catalyst is laminated.

This fiber laminated type filter is formed by laminating one or several fiber layers of a non-woven fabric in which ceramic fibers such as alumina or metal fibers are randomly laminated, and the laminated body of the fiber layers is made of heat-resistant wire mesh. There is a filter or the like that is sandwiched and bent into a bellows shape to have a hollow cylindrical shape, and exhaust gas is circulated from the outside to the inside to purify the exhaust gas.

The upstream or downstream fiber layer is dipped in a solution of each catalyst to support each catalyst on the surface of the fiber forming the fiber layer. Alternatively, a porous catalyst coat layer carrying an oxidation catalyst is applied to the surface of the fiber layer on the upstream side of the laminated body of the fiber layer of the fiber laminated type filter, and the surface of the fiber layer on the downstream side is similar to the above. NOx
A porous catalyst coating layer carrying an occlusion reduction type catalyst is applied.

With these configurations, the oxidation catalyst is carried on the upstream side of the filter, and the NOx storage reduction catalyst is carried on the downstream side, so that the sulfur oxide (SOx in the exhaust gas (SOx ) Is oxidized and combined with Ca, Zn, Fe, etc. in the exhaust gas to form solid sulfate, which is collected by the filter.
It is possible to prevent the catalyst from reaching the x storage-reduction catalyst and avoid sulfur poisoning of the NOx storage-reduction catalyst.

The NOx occlusion reduction type catalyst has a characteristic of releasing nitrogen dioxide (NO ₂ ) from the NOx occlusion substance in the presence of carbon monoxide (CO), and therefore has a lean NOx occlusion ratio. When operating, CO in the exhaust gas
However, in the exhaust gas purifying apparatus of the present invention, CO in the exhaust gas is oxidized and removed by the oxidation catalyst on the upstream side, so that the NOx storage capacity when the air-fuel ratio is lean. High ability can be maintained.

Also, during regeneration operation with a rich air-fuel ratio, a large amount of C ₂ is present because there is no oxygen (O ₂ ) in the exhaust gas.
Since O is generated, this CO is N from the NOx storage substance.
Since the CO serves as a reducing agent while promoting the release of O _2, the released NO ₂ is efficiently reduced and purified by the oxidation catalyst of the NOx occlusion reduction type catalyst.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Exhaust gas purifying devices according to embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of the exhaust gas purifying apparatus 1 according to the first embodiment.

As shown in FIG. 1, the exhaust gas purifying device 1 is a device provided in the exhaust passage 3 of the diesel engine 2, and the particulate matter (PM) and nitrogen oxides (NOx) in the exhaust gas G. And a wall flow type filter 4 for purifying

As shown in FIG. 2, the wall flow type filter 4 serves as a passage for the exhaust gas G in a carrier 30 of a structural material formed of cordierite, silicon carbide (SiC), stainless steel or the like. It has a large number of polygonal channels (cells) 35, and is formed by a monolith honeycomb or the like in which the inlets and outlets of the channels 35 of a porous ceramic honeycomb are alternately sealed.

Then, as shown in FIGS. 3 and 4, the permeable oxidation catalyst layer 20 carrying the oxidation catalyst 21 is provided on the upstream side portion 30u of the porous wall surface 30 of the filter 4, and the filter 4 Downstream part 3 of porous wall surface 30
Nitrogen oxide storage material (NOx storage material) 41a at 0d
And a nitrogen oxide occlusion reduction type catalyst (N
Ox occlusion reduction type catalyst) 41 carrying ventable NOx
A purification catalyst layer 40 is provided.

The oxidation catalyst layer 20 is formed by coating a porous catalyst coat layer such as zeolite or alumina (Al ₂ O ₃ ) coated on the upstream side portion 30u of the porous wall surface 30 of the filter 4 with platinum (Pt) or the like. And an oxidization catalyst 21 such as cerium oxide (CeO ₂ ) are supported so as to be vented.

Further, the NOx purification catalyst layer 40 is formed by adding NOx to the porous catalyst coating layer such as zeolite or alumina coated on the downstream side portion 30d of the porous wall surface 30 of the filter 2.
It is formed by carrying the NOx storage reduction catalyst 41 composed of the storage material 41a and the oxidation catalyst 41b.

This NOx storage substance 41a is an alkali metal such as potassium (K), barium (Ba), sodium (Na), lithium (Li) and cesium (Cs) having a NOx storage function, and calcium (Ca) and the like. The oxidation catalyst 41b is formed of one or a combination of rare earths such as alkaline earth, lanthanum (La) and yttrium (Y), and the oxidation catalyst 41b is a catalytically active metal such as platinum (Pt) and rhodium (Rh). It is formed.

With this configuration, the NOx occlusion reduction type catalyst 4
As shown schematically in FIG. 9, No. 1 stores NOx in the NOx storage substance 41b when the air-fuel ratio in the exhaust gas is lean (O ₂ concentration is relatively high), and the air-fuel ratio is rich (O 2 ₂ concentration is almost zero), NOx is released by the NOx storage substance 41b, and the released NOx is converted to the oxidation catalyst 41b.
It has a function of reducing and purifying with a reducing agent such as CO or HC by the catalytic action of b.

Next, the exhaust gas purifying apparatus 1A of the second embodiment will be described.

As shown in FIGS. 5 to 7, the exhaust gas purifying apparatus 1A of the second embodiment is similar to the exhaust gas purifying apparatus 1 of the first embodiment and the particulate matter (PM) in the exhaust gas. )
Different types of filters to purify.

The filters 4A, 4 of the second embodiment
As shown in FIGS. 5 to 10, B and 4C are formed of a fiber laminated type filter, and a nonwoven fabric fiber layer 5a in which ceramic fibers such as alumina or metal fibers are randomly laminated.
5d are formed by laminating one to several layers, and this fiber layer 5a
The laminated body 5A, 5B, 5C of 5d is sandwiched between the heat-resistant wire nets 6, 7 and bent into a bellows shape to form a hollow cylinder, and one end side 4a of this hollow cylinder is closed. The exhaust gas G flows from the outside to the inside of the laminated bodies 5A, 5B, 5C of the hollow cylindrical fiber layers 5a to 5d and is purified, and the other end side 4c of the hollow portion 4b.
Is discharged from the outside.

Then, as shown in FIGS. 8 and 9, the surface of the fiber layer 5a on the upstream side of the filters 4A and 4B is coated with the porous catalyst coat layer 20 carrying the oxidation catalyst 21, and also on the downstream side. The porous catalyst coat layer 40 carrying the NOx occlusion reduction type catalyst 41 is applied to the surface of the side fiber layer 5d. FIG. 8 shows the heat-resistant wire mesh 6 side of the fiber layer 5a and the fiber layer 5
An example of a laminate 5A in which the porous catalyst coat layers 20 and 40 are provided on the heat-resistant wire mesh 7 side of d is shown in FIG. 9. FIG. 9 shows a space between the fiber layers 5a and 5b and between the fiber layers 5d and 5c. Laminated body 5B in which porous catalyst coat layers 20 and 40 are provided between
For example:

Alternatively, the upstream or downstream fiber layer 5
a, 5d are dipped in a solution of the respective catalysts 31, 41, then dried and heat-treated to support the respective catalysts 31, 41 on the fiber surfaces forming the fiber layers 5a, 5d,
As shown in FIG. 10, the fiber layers 5a ′ and 5d ′ carrying the catalysts 31 and 41 are replaced with the fiber layers 5 carrying no catalyst.
By laminating on b and 5c, a laminated body 5C is formed. Note that any of the catalysts may be supported on all of the fiber layers 5a to 5d forming the filter 4C, and the fiber layer not supporting the catalyst may be omitted.

According to the exhaust gas purifying apparatuses 1 and 1A having the above-described structure, the exhaust gas G comes into contact with the oxidation catalyst 21 and then passes through the filters 4, 4A to 4C, and further, the NOx occlusion reduction type catalyst 41. Since it is discharged after it comes into contact with, it is efficiently purified by the following process.

First, in a state where the lean air oxygen concentration is relatively high when the air-fuel ratio in which the exhaust gas contains O ₂ is relatively high, as shown in FIG. 11, as in a normal operation of a normal diesel engine or a lean burn gasoline engine, etc. And filters 4, 4A-
In the oxidation catalyst 21 on the upstream side of 4C and the oxidation catalyst 41b of the NOx occlusion reduction type catalyst on the downstream side, NO in the exhaust gas G is oxidized by O ₂ in the exhaust gas G to become NO ₂ .
This NO ₂ is a NOx storage substance 4 such as barium (Ba).
Since 1a occludes in the form of nitrate (for example, Ba (NO ₃ ) ₂ ) or the like, NOx in the exhaust gas G is purified.

Further, the upstream side oxidation catalyst 21 oxidizes and purifies HC and CO in the exhaust gas G to prevent the NOx occlusion reduction type catalyst 41 from deteriorating the NOx occlusion ability. In addition, PM such as soot (soot) is filtered by filters 4 and 4.
It is collected by the porous wall surfaces 30 of A to 4C and the laminated bodies 5A to 5C of fibers.

However, if this state continues, all the NOx storage substances 41a having the NOx storage function change to nitrates and the like and lose the NOx storage function. Therefore, the operating state of the engine is changed to change the theoretical air-fuel ratio. And rich combustion, which is an air-fuel ratio close to the stoichiometric air-fuel ratio, for a short time (for example, about 0.1
Performed only during the second order of 5 seconds), referred to as rich spike gas and the O ₂ in the exhaust gas to generate hot exhaust gases to substantially zero, sent to the NOx occlusion reduction type catalyst 41,
Play back.

Then, when the air-fuel ratio rich oxygen concentration for regenerating the NOx occlusion reduction type catalyst 41 is almost zero,
Since there is almost no O ₂ on the upstream side of the filters 4, 4A to 4C, HC and CO pass through to the downstream side without being oxidized, and since there is almost no O ₂ on the downstream side, as shown in FIG. , Nitrates (barium nitrate) and the like of the NOx storage substance 41a that have stored NOx return to the original state (barium) and release the stored NO ₂ .

At the time of this regeneration, since there is much CO, NOx
Since the release of NO ₂ from the storage substance 41a and the reduction purification can be promoted, the time required to regenerate the NOx storage capacity can be shortened.

The released NO ₂ is O in the exhaust gas.
_{Since 2} does not exist, CO, HC, H _{2 and the} like in the exhaust gas that has passed through the porous wall surface 30 and the laminated bodies 5A to 5C of the fiber due to the catalytic action of the oxidation catalyst 41b is reduced to nitrogen N ₂ . It is then purified and discharged together with H ₂ O and CO ₂ . Further, PM such as soot is collected by the porous wall surface 30 and the fiber laminated bodies 5A to 5C.

Then, the sulfur oxide (SO
x) can be oxidized by the oxidation catalyst 31 on the upstream side and can be combined with Ca, Zn, Fe, etc. in the exhaust gas to form a solid sulfate, which is a porous wall surface 30.
Since it can be collected by the laminated bodies 5A to 5C of fibers and fibers, the contact of SOx with the NOx occlusion reduction type catalyst 41 is prevented, and NOx
It is possible to avoid sulfur poisoning of the storage reduction catalyst 41.

[0046]

As described above, according to the exhaust gas purifying apparatus of the present invention, the following effects can be obtained.

Without supplying a reducing agent for NOx reduction at all times, a filter carrying an oxidation catalyst and a NOx occlusion reduction type catalyst can collect and oxidize PM in the exhaust gas to purify it, and at the same time, can remove PM in the exhaust gas. Since NOx can be efficiently purified by occluding, releasing and reducing NOx occluding and reducing catalysts, a reducing agent supply device becomes unnecessary.
It is possible to prevent deterioration of fuel efficiency.

With the structure in which the oxidation catalyst is arranged on the upstream side of the filter and the NOx storage reduction catalyst is arranged on the downstream side, the sulfur oxide (SOx) in the exhaust gas is discharged by the oxidation catalyst on the upstream side. Oxidize the exhaust gas to produce Ca, Z in the exhaust gas
It is possible to prevent SOx in the exhaust gas from reaching the NOx occlusion reduction type catalyst by combining with n, Fe, etc. to form a solid sulfate that can be trapped by the filter, and to collect it with the filter. It is possible to avoid sulfur poisoning of the catalyst.

Further, in the NOx occlusion operation where the air-fuel ratio is lean, the oxidation catalyst on the upstream side of the filter uses C in the exhaust gas.
Since O is oxidized and removed, deterioration of NOx storage capacity due to CO can be prevented and a high purification rate can be maintained, and CO generated due to the absence of O ₂ in the exhaust gas during regeneration operation with a rich air-fuel ratio. The release of NO ₂ from the NOx storage substance and reduction purification can be promoted, and the time required for regeneration of the NOx storage capacity can be shortened.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of an exhaust gas purifying apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration of a wall flow type filter of the exhaust gas purifying apparatus according to the first embodiment of the present invention.

FIG. 3 is an enlarged view of the filter of FIG.

4 is a partially enlarged view of the filter of FIG.

FIG. 5 is a diagram showing a configuration of a fiber laminated type filter of an exhaust gas purifying apparatus according to a second embodiment of the present invention.

6 is a diagram showing a flow of exhaust gas in the filter of FIG.

7 is a partially enlarged view of FIG.

8 is a diagram showing a first example of a laminated structure of the filter of FIG.

9 is a diagram showing a second example of the laminated structure of the filter of FIG.

10 is a diagram showing a third example of the laminated structure of the filter of FIG.

FIG. 11 is a schematic diagram showing the mechanism of NOx purification by the NOx occlusion reduction type catalyst, showing a state in which exhaust gas with a lean air-fuel ratio such as normal combustion is being supplied.

FIG. 12 is a schematic diagram showing a mechanism of NOx exhaust gas purification by a NOx occlusion reduction type catalyst, showing a state in which exhaust gas having a rich air-fuel ratio is being supplied.

[Explanation of symbols]

1, 1A, 1B, 1C Exhaust gas purifying device 2 Engine 3 Exhaust passage 4 Wall flow type filter 4A, 4B, 4C Fiber laminated type filter 4a Upstream fiber layer 4d Downstream fiber layer 20 Oxidation catalyst layer (perforated Quality catalyst coating layer) 21 oxidation catalyst 30 porous wall surface 40 nitrogen oxide purification catalyst layer (porous catalyst coating layer) 41 nitrogen oxide storage reduction catalyst (NOx storage reduction catalyst) 41a nitrogen oxide storage material (NOx storage) Substance) 41b Oxidation catalyst G Exhaust gas

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[Procedure amendment]

[Submission date] August 8, 2001 (2001.8.8)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/02 301 F01N 3/24 C 3/10 E 3/24 3/28 301E 301P 3/28 301 B01D 53/36 103C 103B ZAB F-term (reference) 3G090 AA02 EA01 3G091 AA18 AB02 AB06 AB13 BA11 BA14 GA02 GB03Y GB04Y GB05W GB06W GB09X GB10W GB17X HA15 HA16 4D019 AA01 BA02 BA05 BB03 BC07 CA01 CA02 CA03 CB04 4D048 AA06 AA14 AB01 AB02 AB07 BA03X BA06X BA10X BA11X BA14X BA15X BA18X BA19X BA30X BA33X BA39X BA41X BA45X BB02 BB14 BB16 CD05 EA04

Claims (2)

[Claims] 1. An exhaust gas purifying apparatus comprising a wall flow type filter provided in an exhaust passage of an engine for purifying particulate matter in exhaust gas, wherein an oxidation catalyst is provided on an upstream side portion of a porous wall surface of the filter. In addition to providing an oxidation catalyst layer carrying a nitrogen oxide purification catalyst layer carrying a nitrogen oxide storage reduction type catalyst containing a nitrogen oxide storage substance and an oxidation catalyst in the downstream side portion of the porous wall surface of the filter. An exhaust gas purification device characterized by the above. 2. An exhaust gas purifying apparatus comprising a fiber laminated type filter provided in an exhaust passage of an engine for purifying particulate matter in exhaust gas, wherein an oxidation catalyst is carried on a fiber layer on an upstream side of the filter. Or laminating an oxidation catalyst layer supporting an oxidation catalyst, and supporting a nitrogen oxide storage reduction catalyst containing a nitrogen oxide storage substance and an oxidation catalyst on the fiber layer on the downstream side of the filter, or the nitrogen. An exhaust gas purification device comprising a stack of nitrogen oxide purification catalyst layers carrying an oxide occlusion reduction type catalyst.