JP4868714B2 - Exhaust gas purification filter catalyst - Google Patents

Description

  The present invention relates to an exhaust gas purification filter catalyst that collects particulate matter (hereinafter referred to as PM) in exhaust gas from a diesel engine or the like.

  Since exhaust gas from diesel engines, etc. contains PM composed of carbon fine particles, SOF, sulfates, etc., it is necessary to remove PM before discharging to discharge clean exhaust gas. Since it is difficult to remove this PM with a normal oxidation catalyst, a three-way catalyst, etc., a method of removing it by oxidation after collecting it on a filter is common.

  As such a filter, a honeycomb body made of heat-resistant ceramics such as cordierite and having a large number of cells, an inflow side cell clogged at the downstream end, and an upstream end adjacent to the inflow side cell Wall-flow type (DPF) is widely used, which forms outflow side cells clogged with. In this DPF, the exhaust gas flowing into the inflow side cell passes through the cell partition and is discharged from the outflow side cell. However, when the exhaust gas passes through the cell partition, PM is collected in the pores of the cell partition. When PM is collected to some extent, PM collected by heating with a heater is burned to regenerate the filter function.

  However, with such a filter, when the amount of collected PM is large, the amount of heat generated by combustion during regeneration is large, and may be damaged by heat shock. In addition, the manufacturing cost is high. Therefore, in recent years, several metal filter devices have been proposed.

  For example, in Japanese Patent Application Laid-Open No. 09-262414, a corrugated plate made of a thin metal plate and a flat plate made of a metal non-woven fabric are alternately laminated, and an inflow side cell clogged at a downstream end portion is adjacent to the inflow side cell. A filter is described which forms an outflow side cell clogged at an upstream end. Further, JP 2002-113798 A discloses an inflow side cell in which flat plates and corrugated plates made of a metal nonwoven fabric are alternately laminated and clogged at the downstream end, and an upstream end adjacent to the inflow side cell. And a filter formed with an outflow side cell clogged with.

  According to these filters, PM in the exhaust gas is collected in the metal nonwoven fabric. And even if it performs the regeneration process which burns PM by heating, since it is metal, a heat shock is small and damage can be suppressed. However, since both are wall flow type filters, exhaust pressure loss increases as PM is collected. In addition, since PM concentrates and accumulates in the vicinity of the clogging portion of the inflow side cell, there is a problem that exhaust pressure loss increases at a stretch. When importance is attached to engine efficiency or fuel consumption, it is necessary to frequently perform regeneration processing.

  On the other hand, in German utility model 20,117,873 U1, a corrugated plate made of metal foil and a filter layer are alternately laminated to form a plurality of claw-shaped holes having claw-shaped hole heights on the corrugated plate. The inner hole forms a flow path having an inward nail hole and an outward nail hole, the inward nail hole and the outward nail hole are arranged at an angle with each other, and the nail hole height is equal to the structural height. A filter is described which is 100-60% high and guarantees a flow freedom of at least 20%.

  A filter catalyst having a catalytic function has also been developed. For example, Japanese Patent Application Laid-Open No. 09-262415 discloses a three-dimensional network structure porous body made of heat-resistant metal having continuous pores, or a plate made by filling ceramic or metal into pores of the porous body to reduce the substantial pore diameter. A filter element is described in which a filter and a corrugated plate are alternately overlapped and wound, and both ends of the columnar body formed thereby are alternately marked, and a catalyst metal is supported on the corrugated plate or the flat plate element. Has been.

According to this filter element, the PM trap and the catalytic converter can be integrated, which is advantageous in terms of space. Further, since the carrier is a metal, the heat capacity is small and the temperature rise rate of the catalyst metal is increased, and it becomes easy to obtain a temperature necessary for the catalyst metal to work effectively. Further, when carrying _the NO _x storage material such as alkali metal as a catalyst metal is in the case of a substrate made of cordierite reacts is _the NO _x storage material and the substrate, if the metal substrate NO _x Has the advantage of not reacting with the occlusion material.

However, in the technique described in Japanese Patent Application Laid-Open No. 09-262415, since the heat-resistant metal three-dimensional network porous body having continuous pores is used, the pore diameter is random. In order to carry a catalyst, it is effective to form a catalyst layer containing a porous oxide carrying a catalyst metal. However, a uniform catalyst layer is formed on a heat-resistant metal three-dimensional network porous body having random pore sizes. It is difficult to form, and there is a problem that the increase in exhaust pressure loss increases, the activity due to the catalyst metal is not sufficiently obtained, or the activity is lowered due to grain growth of the catalyst metal due to heat during use. It was.
JP 09-262414 A JP 2002-113798 German utility model 20,117,873 U1 JP 09-262415 A

  The present invention has been made in view of the circumstances described above, and solves the problem of collecting PM, allowing the collected PM to be oxidized and burned continuously and efficiently, and suppressing an increase in exhaust pressure loss. It should be a challenge.

A feature of the exhaust gas purification filter catalyst of the present invention that solves the above-described problem is that a corrugated plate made of a thin metal plate and having a crest and a trough alternately continuous in a direction intersecting the exhaust gas flow direction, and a communication hole penetrating the front and back sides A flat plate made of a metal plate provided, and an exhaust gas purification filter catalyst in which peaks and valleys constitute an exhaust gas flow path, and at least the flat plate constitutes a filter,
The valley has a convex intermediate peak formed by the valley depth being shallow, and the peak has a concave intermediate valley formed by the peak height being reduced,
In the part where the flat plate is laminated on the upper side of the corrugated plate,
The intermediate crest and the crests on both sides adjacent to the crest and the flat plate in contact with the crest form a filter introduction part that blocks the flow path and guides exhaust gas to the filter,
The middle valley portion is composed of a branch portion where the exhaust gas branches off from the adjacent valley portion and can flow in, and an opening communicating with the mountain portion on the downstream side, and branches to the exhaust gas flow channel adjacent to the filter introduction portion. Configure the bypass filter part to bypass,
When the pressure in the filter introduction portion increases, at least a part of the exhaust gas flowing through the valley portion passes from the filter introduction portion to the adjacent peak portion through the filter bypass portion existing on the upstream side of the filter introduction portion. Configured,
The flat plate is formed with a catalyst layer containing a porous oxide on which a catalyst metal is supported, and the communication hole is that the pore diameter is reduced or closed to 200 μm or less by the catalyst layer.

Further, if the characteristics of the exhaust gas purification filter catalyst are expressed from the back side of the corrugated plate, the filter introduction portion in which the flow path is blocked by the intermediate valley portion, the valley portions on both sides adjacent to the intermediate valley portion, and the flat plate in contact with the valley portion. The intermediate peak portion constitutes a filter bypass portion consisting of a branch portion into which exhaust gas branches off from an adjacent peak portion and can flow in, and an opening communicating with the valley portion on the downstream side, and the pressure in the filter introduction portion is When the height increases, at least a part of the exhaust gas flowing through the peak portion is configured to flow from the filter introduction portion to the adjacent valley portion through the filter bypass portion existing on the upstream side of the filter introduction portion .

  In this case, it is desirable that a trough portion of an adjacent corrugated plate exists on the opposite side of the filter introduction portion through the flat plate.

  It is desirable that the intermediate valley portion and the intermediate mountain portion are formed by deforming the mountain portion or the valley portion, and that the upstream end portion is smoothly continuous toward the bottom portion or the top portion, respectively.

  Further, the opening area of the corrugated plate in plan view in the filter introduction portion is preferably 30% or more of the total opening area of the corrugated plate in plan view, and the total volume of the filter introduction portion is the total of the peaks and valleys. It is preferably 50% or more of the total volume.

Another feature of the exhaust gas purification filter catalyst embodying the exhaust gas purification filter catalyst of the present invention is that the corrugated plate and the flat plate are made of a thin metal plate and have a mountain valley portion in which the first mountain portion and the first valley portion are alternately continuous. Are stacked alternately,
A first passage formed by the first peak and the lower flat plate of the corrugated plate;
A first filter introduction portion formed of a second valley portion formed in the first passage and having a downstream side inclined upward and a flat plate on the upper side of the corrugated plate;
A first filter bypass portion comprising a second trough and a flat plate below the corrugated plate;
A second passage formed by a first trough on both sides of the first passage and an upper flat plate of the corrugated plate;
A second filter introduction portion formed of a second peak portion formed in the second passage and having a downstream side inclined downward and a flat plate on the lower side of the corrugated plate;
A second filter bypass portion comprising a second peak and a flat plate on the upper side of the corrugated plate,
The depth of the bottom of the second valley is shallower than the height of the top of the first peak, and the height of the top of the second peak is lower than the depth of the bottom of the first valley, and at least the corrugated plate and the flat plate A through hole is formed through the front and back, and at least a flat plate is formed with a catalyst layer containing a porous oxide carrying a catalyst metal. The communication hole is reduced or blocked to a pore size of 200 μm or less by the catalyst layer. It lies in that it is.

  The exhaust gas purification filter catalyst further has at least one of an opening through which the exhaust gas can flow from the first filter introduction part to the second passage or an opening through which the exhaust gas can flow from the second filter introduction part to the first passage. Is desirable.

  According to the exhaust gas purification filter catalyst of the present invention, the communication hole is reduced or closed by the catalyst layer so that the hole diameter is 200 μm or less, so that PM in the exhaust gas is collected by the catalyst layer formed in the communication hole. can do. Since the catalyst layer is formed on the metal thin plate, the catalyst layer can be formed uniformly, and the catalyst layer is heated uniformly by the exhaust gas and the catalyst metal is also activated uniformly. It can be oxidized and burned efficiently. Further, since the catalyst layer is uniform, its thickness can be reduced, and as a result, an increase in exhaust pressure loss can be suppressed.

  The exhaust gas purification filter catalyst of the present invention has a plurality of exhaust gas passages and a filter installed in the exhaust gas passages, and the exhaust gas passages are adjacent to the filter introduction part for guiding the exhaust gas to the filter and the filter introduction part. And a filter bypass section that branches to the exhaust gas flow path that bypasses the filter introduction section.

  The filter is formed by forming a catalyst layer containing a porous oxide carrying a catalyst metal on a metal plate having communication holes penetrating the front and back, and the communication holes are reduced in diameter to 200 μm or less by the catalyst layer. It is blocked. When the pore diameter is 200 μm, there are some PM that slip through the 200 μm hole in the initial state, but when PM adheres, the pore diameter becomes about 10-50 μm and the PM trapping ability improves, so the pore diameter is set to 200 μm or less. . Since the catalyst layer contains porous oxide powder, pores of about 10 μm are present in the catalyst layer itself, and finer pores are also present in the porous oxide powder. Therefore, even if the communication hole is completely blocked by the catalyst layer, gas diffusibility is ensured, and PM collected in the catalyst layer formed in the communication hole is efficiently oxidized and burned by the catalyst metal.

In the exhaust gas purifying filter catalyst according to claim 1, the exhaust gas flowing into the flow path formed by the valley portion and the upper flat plate passes through the upper flat plate that collides with the intermediate mountain portion and partitions the filter introduction portion, PM is collected on the flat plate. When the amount of PM trapped on the upper flat plate that partitions the filter introduction portion increases, the pressure in the filter introduction portion increases, so the exhaust gas passes through the branch portion of the filter detour portion on the upstream side from the filter introduction portion, and the peaks on both sides Branch inflows from the middle valley to the peaks on both sides.

And as described in claim 4 , on the back side of the corrugated plate, the back side of the intermediate valley portion is convex to form a filter introduction portion between the peak portion and the lower flat plate, and the upstream valley portion. Since the filter detour part is formed at the intermediate peak of the exhaust gas, the exhaust gas flowing into the flow path formed by the peak and the lower flat plate collides with the intermediate valley and the pressure increases in the filter introduction part From the filter introduction part, it passes through the filter detour part on the upstream side, and branches and flows into the troughs on both sides through the opening of the intermediate peak part of the troughs on both sides.

  This action is continuously repeated from the exhaust gas inflow side end surface to the outflow side end surface.

  That is, since the filter catalyst of the present invention basically has a wall flow structure, the PM collection efficiency is high. Even if the amount of PM trapped on the flat plate in the filter introduction portion increases, the exhaust gas branches off from the upstream filter detour portion and flows into the peak portion or valley portion, which continuously occurs. Therefore, an increase in exhaust pressure loss due to PM accumulation does not occur all at once, and since most of the flat plate can be used for PM collection, an increase in exhaust pressure loss can be effectively suppressed.

  The corrugated plate and the flat plate are formed from a thin metal plate, and the corrugated plate can be manufactured from the flat plate by corrugating or the like. The material is not particularly limited as long as it has heat resistance that can withstand the exhaust gas temperature and heat during regeneration, but a stainless steel material is preferable. For automobiles, the thickness is preferably in the range of 20 to 110 μm, particularly preferably in the range of 40 to 80 μm.

  At least one of the corrugated plate and the flat plate is provided with a communication hole penetrating the front and back. It is preferable that the communication hole has a size of 30 to 500 μm. If the size of the communication hole exceeds 500 μm, it becomes difficult to reduce it to 200 μm or less by the catalyst layer, and if it is less than 30 μm, it is blocked by the catalyst layer. As a result, although gas diffusibility is ensured, exhaust pressure loss tends to increase. The number of communication holes is not particularly limited, but it is preferable to provide as many as possible within a range where the strength can be maintained.

  In order to form a substrate composed of a corrugated plate and a flat plate, the corrugated plate and the flat plate may be alternately stacked and inserted into a predetermined outer cylinder, or a predetermined length of the corrugated plate and the flat plate may be stacked and rolled. What was wound in the shape can also be inserted in a predetermined outer cylinder.

  The catalyst layer is a layer containing a porous oxide on which a catalyst metal is supported, and is preferably formed in an amount of 30 to 200 g per liter of the substrate. If the amount of the catalyst layer is smaller than this, the catalyst metal is supported at a high density, so that grain growth occurs in the catalyst metal or PM collection efficiency decreases. Further, when the catalyst layer is larger than this, the exhaust pressure loss increases. As the porous oxide, it is possible to use at least one selected from alumina, zirconia, titania, ceria, etc., or a composite oxide composed of a plurality of types selected from these. As the catalyst metal, it is preferable to use one or more selected from platinum group noble metals such as Pt, Rh, Pd, Ir and Ru. The amount of catalyst metal supported is preferably 0.1 to 5 g per liter of the substrate. If the loading amount is less than this, the activity is too low to be practical, and if the loading amount exceeds this range, the activity is saturated and the cost is increased.

The catalyst layer preferably contains a NO _x storage material selected from alkali metals, alkaline earth metals, and rare earth elements. When the NO _x storage material is included in the catalyst layer, NO ₂ generated by oxidation with the catalyst metal can be stored in the NO _x storage material, so that the NO _x purification activity is further improved. The amount of NO _x occlusion material supported is preferably in the range of 0.05 to 0.45 mol per liter of substrate. If the supported amount is less than this, the activity is too low to be practical, and if the supported amount is more than this range, the catalyst metal is covered and the activity is lowered.

  In order to form the catalyst layer, the oxide powder or the composite oxide powder is made into a slurry together with a binder component such as alumina sol and water, and the slurry is attached to at least one of the corrugated plate and the flat plate, followed by firing, and then the catalyst metal. May be carried. A slurry can also be prepared from a catalyst powder in which a catalyst metal is previously supported on an oxide powder or a composite oxide powder. A normal dipping method can be used to attach the slurry, but it is possible to forcibly fill the communicating holes with air blow or suction and to remove excess slurry contained in the communicating holes. desirable.

  The corrugated plates may be laminated so that all the layers have the same direction and the same phase, or can be laminated so that the directions are alternately different by 180 degrees or the phases are different. However, it is desirable that a concave portion of an adjacent corrugated plate exists on the opposite side of the filter introduction portion through the flat plate. As a result, the PM collection efficiency can be further improved and the increase in exhaust pressure loss can be further suppressed without impeding the flow of the exhaust gas that has permeated the flat plate.

  In addition, the recessed part of an adjacent corrugated board refers to a peak part when an adjacent corrugated board is located upward, and refers to a trough part when an adjacent corrugated board is located below.

  The intermediate valley portion or the intermediate mountain portion is formed by deforming the mountain portion or the valley portion, and it is desirable that the upstream end portion is smoothly continuous toward the bottom portion or the top portion, respectively. That is, it is preferable that the height is gradually reduced toward the upstream side, or is blocked by a slope that becomes higher. By doing in this way, since the vector which goes to the flat plate which partitions a filter introduction part produces | generates in the exhaust gas in a filter introduction part, PM collection efficiency improves further.

  The opening area of the corrugated plate in plan view in the filter introduction part is desirably 30% or more of the total opening area of the corrugated plate in plan view. When the opening area of the corrugated plate in plan view at the filter introduction portion is less than 30% of the total opening area, the use area of the flat plate is reduced and the PM collection efficiency is reduced. The total volume of the filter introduction part is preferably 50% or more of the total volume of the peak part and the valley part. When this ratio is less than 50%, the PM collection efficiency decreases.

  Also, the longer the distance from the filter introduction part to the upstream branch part, the better the PM collection efficiency, but the exhaust pressure loss tends to increase. Therefore, there is an optimum value for the distance.

Moreover, the corrugated board and flat plate which are made of a thin metal plate and have a crest and a trough where the first crest and the first trough are alternately arranged are alternately laminated,
A first passage formed by the first peak and the lower flat plate of the corrugated plate;
A first filter introduction portion formed of a second valley portion formed in the first passage and having a downstream side inclined upward and a flat plate on the upper side of the corrugated plate;
A first filter bypass portion comprising a second trough and a flat plate below the corrugated plate;
A second passage formed by a first trough on both sides of the first passage and an upper flat plate of the corrugated plate;
A second filter introduction portion formed of a second peak portion formed in the second passage and having a downstream side inclined downward and a flat plate on the lower side of the corrugated plate;
A second filter bypass portion comprising a second peak and a flat plate on the upper side of the corrugated plate,
The depth of the bottom of the second valley may be smaller than the height of the top of the first peak, and the height of the top of the second peak may be lower than the depth of the bottom of the first valley. Specifically, the corrugated plates used are the same as those described in German utility model 20,117,873 U1. The German utility model No. 20,117,873 U1 does not have a description regarding the communication hole.

  In this case, the corrugated plates may be laminated so as to have the same direction and the same phase in all layers, or can be laminated so as to be alternately different by 180 degrees or in different phases. That is, when cut in a cross section perpendicular to the exhaust gas flow direction, each of the first and second passages may be at the same cross-sectional position or at different cross-sectional positions. However, it is desirable that a concave portion of an adjacent corrugated plate exists on the opposite side of the filter introduction portion through the flat plate. As a result, the PM collection efficiency can be further improved and the increase in exhaust pressure loss can be further suppressed without impeding the flow of the exhaust gas that has permeated the flat plate.

  The concave portion of the adjacent corrugated plate refers to one of the first peak portion and the second peak portion when the adjacent corrugated plate is positioned above, and is first when the adjacent corrugated plate is positioned below. One of the valley and the second valley.

  The corrugated plate has a crest portion in which the first crest portion and the first trough portion are alternately continued in a direction substantially perpendicular to the exhaust gas flow direction, and the crest portion is the second trough portion or the second crest portion in the exhaust gas flow direction. A plurality are formed with a gap therebetween. A second trough is formed on the downstream side of the first peak, and the first passage and the first filter introduction part are continuous in series. A second peak portion is formed in the first valley portion downstream of the second valley portion, and the second passage and the second filter introduction portion are continuous in series.

  The first filter bypass unit is connected in series with the first passage in parallel with the first filter introduction unit. The second filter bypass unit is connected in series with the second passage in parallel with the second filter introduction unit.

The upstream side of the first filter introducing portion communicates with the first passage, and the downstream end portion is narrowed. Although this throttling can be performed by clogging or the like, it is desirable that the first end is formed by deforming the first peak and the downstream end is smoothly continuous with the top of the first peak. That is, it is preferable that the surface is squeezed on a slope whose height gradually increases toward the downstream side. By doing in this way, since the vector which goes to the upper flat plate which exists in a filter introduction part produces | generates in the exhaust gas which flows through a 1st filter introduction part, PM collection efficiency improves further. Furthermore, NO in the exhaust gas is oxidized in the catalyst layer formed on the corrugated plate, and it passes through the flat plate as NO ₂ with high oxidation activity. Therefore, oxidation combustion of PM collected in the flat catalyst layer is further accelerated. Is done.

As for the 2nd filter introducing | transducing part formed with a 2nd peak part and a lower flat plate, the upstream is connected to a 2nd channel | path, and the downstream edge part is restrict | squeezed. Although this throttling can be performed by clogging or the like, it is desirable that the first end is formed by deforming the first trough and the downstream end is smoothly continuous with the bottom of the first trough. In other words, it is preferably narrowed down on a slope whose height gradually decreases toward the downstream side. By doing in this way, since the vector which goes to a lower flat plate produces | generates in the waste gas which flows through a 2nd filter introducing | transducing part, PM collection efficiency improves further. In addition, NO in exhaust gas is oxidized by the catalyst layer formed on the corrugated plate and passes through the flat plate as NO ₂ having high oxidation activity, so that oxidation combustion of PM collected in the flat catalyst layer is further promoted. The

  The opening through which the exhaust gas can flow from the first filter introduction part to the second passage may form a communication hole in the peripheral wall of the second valley part, but is lower than the height of the first peak part on both sides of the second valley part. It is desirable to form sidewalls. In addition, it is desirable that the opening through which the exhaust gas can flow from the second filter introduction part to the first passage has a side wall shallower than the depth of the first valley part on both sides of the second peak part. By doing in this way, a corrugated board can be easily formed by corrugating from one metal thin plate.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
FIG. 1 is a perspective view of an exhaust gas purification filter catalyst of the present embodiment, FIG. 2 is an enlarged perspective view of an essential part thereof, an oblique perspective view of an essential part of a corrugated plate used in FIG. The figure is shown. This filter catalyst is composed of a stainless steel corrugated plate 1 having a thickness of 50 μm and a stainless steel plate 50 having a thickness of 50 μm alternately laminated and welded to each other, and an outer cylinder in which the base is press-fitted and held. 3. The substrate has a diameter of 130 mm and a volume of 2 L, and the number of cells is 200 cells / inch 2. The corrugated plate 1 and the flat plate 2 are each provided with a communication hole 4 having a diameter of 0.2 mm every 0.2 mm. . Further, catalyst layers (not shown) are formed on the front and back surfaces of the corrugated plate 1 and the flat plate 2, respectively.

  This catalyst layer is composed of alumina powder supporting Pt, and is fired after a wash coat using a slurry. The catalyst layer has pores having an average pore diameter of 10 μm, 150 g is formed per liter of the substrate, and 2 g of Pt is supported per liter of the substrate. Further, the diameter of the communication hole 4 is reduced by the catalyst layer to about 100 μm.

  In the corrugated plate 1 shown in FIG. 3, the crests 10 and the troughs 11 are alternately continued in a direction orthogonal to the exhaust gas flow direction. In the peak portion 10, a plurality of concave intermediate valley portions 12 are formed in parallel to the exhaust gas flow direction and spaced from each other. The intermediate valley portion 12 gradually decreases in height from the upstream side to the downstream side of the exhaust gas, and the tip thereof is cut away to form an opening 13 communicating with the mountain portion 10 again. The depth of the bottom of the intermediate valley 12 is the same as the position of the bottom of the valley 11.

  In the valley portion 11, a plurality of convex intermediate mountain portions 14 are formed in parallel to the exhaust gas flow direction and spaced from each other. The intermediate mountain portion 14 is disposed between the two intermediate valley portions 12 in the exhaust gas flow direction, and the height thereof is the same as the height of the mountain portion 10.

  In the corrugated plate 1, the peak portion 10 is a valley portion and the valley portion 11 is a peak portion on the back surface. The intermediate valley portion 12 constitutes a convex intermediate mountain portion on the back side, the intermediate mountain portion 14 constitutes a concave intermediate valley portion, and an opening 15 is formed at the tip of the intermediate mountain portion 14.

  As shown in FIG. 4, the plurality of corrugated plates 1 are laminated so that the phases of the intermediate valley portion 12 and the intermediate mountain portion 14 are the same in the exhaust gas flow direction and in the direction perpendicular to the exhaust gas flow direction. In the cross section cut at right angles to the exhaust gas flow direction, the intermediate valley portion 12 and the intermediate mountain portion 14 are arranged at the same position. The peak portion 10 is in contact with the upper flat plate 2, and the valley portion 11 is in contact with the lower flat plate 2. Since FIG. 4 is a schematic diagram, there is a gap between the flat plate 2 and the intermediate valley portion 12 and the intermediate mountain portion 14, but on the upstream end surface, a laminated structure of the ball portion 10 and the valley portion 11 and the flat plate 2. It becomes a body and there is no gap, so there is no problem.

  In this filter catalyst, as shown in FIGS. 5 to 8, on the surface side of the corrugated plate 1, a filter is introduced in which the flow path is blocked by the peak portions 10 on both sides adjacent to the intermediate peak portion 14 and the upper flat plate 2. Part 100 is formed. Further, on the back side of the corrugated plate 1, a filter introduction portion 101 is formed in which the flow path is closed by the valley portions 11 on both sides adjacent to the intermediate valley portion 12 and the lower flat plate 2. On the upstream side of the filter introduction part 100, the height of the peak part 10 is reduced at the position of the intermediate valley part 12, and the opening 13 is formed. It is possible to flow into the mountain portion 10, and the filter bypassing portion 200 is formed in that portion. Further, on the back side, the depth of the valley portion 11 becomes shallower and the opening 15 is formed at the intermediate peak portion 14 on the upstream side of the filter introduction portion 100, so that the exhaust gas flowing through the peak portion 10 is opened on the openings 15 on both sides. Can flow into the valleys 11 on both sides, and the filter bypassing part 201 is also formed there.

  Therefore, according to the exhaust gas purification filter catalyst of the present embodiment, as shown in FIG. 5, the exhaust gas flowing through the flow path formed between the valley portion 11 and the upper flat plate 2 collides with the intermediate peak portion 14, In a state where the amount of PM trapped on the upper flat plate 2 is small, most of the exhaust gas passes through the communication hole 4 of the upper flat plate 2 and flows into the trough 11 of the corrugated plate 1 existing on the opposite side of the flat plate 2. Most of the PM is collected by the flat plate 2.

  When the amount of collected PM increases and the pressure of the exhaust gas at the filter introduction part 100 increases, the exhaust gas passes through the opening 13 from the intermediate valley part 12 in the filter bypass part 200 existing upstream as shown by the dotted line in FIG. Then, it branches and flows into the adjacent mountain portion 10. Therefore, an increase in exhaust pressure loss is suppressed.

  Similarly, the exhaust gas flowing through the flow path formed between the peak portion 10 and the lower flat plate 2 collides with the intermediate valley portion 12 as shown in FIG. 7, and the amount of PM trapped on the lower flat plate 2 is small. In the state, most of the exhaust gas passes through the communication hole 4 of the lower flat plate 2 and flows into the valley 11 of the corrugated plate 6 on the opposite side of the flat plate 2, and most of PM is collected by the flat plate 2. Is done.

  When the amount of collected PM increases and the pressure of the exhaust gas at the filter introduction part 101 increases, the exhaust gas passes through the opening 15 from the intermediate peak part 14 in the filter bypass part 201 existing upstream as shown by the dotted line in FIG. Then, it branches and flows into the adjacent valley portion 11. Therefore, an increase in exhaust pressure loss is suppressed.

  According to the filter catalyst of the present embodiment, PM is collected on the flat plate 2 in the filter introduction portions 100 and 101 by continuously repeating the above-described cycle from the exhaust gas inflow side end surface toward the outflow side end surface. Since a large number of filter introduction parts 100 and 101 are formed, PM is uniformly dispersed and collected throughout the flat plate 2, and the collection efficiency is improved and PM is collected. Exhaust pressure loss is unlikely to rise. That is, the improvement of the PM collection efficiency and the suppression of the increase of the exhaust pressure loss are compatible.

  Furthermore, in the filter catalyst of the present embodiment, the opening area of the corrugated plate 1 in the plan view in the filter introducing portions 100 and 101 occupies about 40% of the total opening area of the corrugated plate 1 in the plan view. The total volume of 101 occupies about 50% of the total volume of the peak 10 and the valley 11. Thereby, the utilization area of the flat plate 3 is large, the PM collection efficiency is high, and the increase in exhaust pressure loss is suppressed.

This filter catalyst was attached to the exhaust pipe of a diesel engine, and the PM reduction rate in 11 Lap mode and the exhaust pressure loss in the latter period of operation were measured. The PM reduction rate was calculated by measuring the PM amount (P ₁ ) in the exhaust gas that passed through the filter catalyst and calculating the PM amount (P ₀ ) discharged from the diesel engine in advance by the following equation.

PM reduction rate (%) = 100 x (P ₀ -P ₁ ) / P ₀
The exhaust pressure loss was measured by measuring the difference between the pressure of the gas containing the filter catalyst and the pressure of the gas output from the filter catalyst when the vehicle traveled 1000 km in 11 Lap mode. The results are shown in Table 1.

(Example 2)
Example 1 is the same as Example 1 except that the communication hole 4 is not formed in the corrugated plate 1. For the filter catalyst of this example, the PM reduction rate and the exhaust pressure loss were measured in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
The same as Example 1 except that the communication hole 4 was not formed in the corrugated plate 1 and that a metal fiber mat having a thickness of 0.3 mm and a porosity of 80% was used instead of the flat plate 2. Using this filter catalyst, the PM reduction rate and the exhaust pressure loss were measured in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
Example 1 is the same as Example 1 except that the communication hole 4 is not formed in the corrugated plate 1 and the flat plate 2. Using this filter catalyst, the PM reduction rate and the exhaust pressure loss were measured in the same manner as in Example 1. The results are shown in Table 1.

  <Evaluation>

  From a comparison between Example 2 and Comparative Example 1, the filter catalyst of Example 2 is superior to Comparative Example 1 in PM trapping ability and has low exhaust pressure loss. In Example 2, since the catalyst layer was formed on the corrugated plate and the flat plate made of a thin metal plate, the catalyst layer was uniformly formed as compared with Comparative Example 1 in which the catalyst layer was formed on the fiber mat, and Pt was also uniformly distributed. Effect.

  In addition, the filter catalysts of Examples 1 and 2 are superior in PM trapping ability and have low exhaust pressure loss as compared with Comparative Examples 1 and 2. This is because the effect due to the formation of the communication hole is expressed.

(Example 3)
The communication hole 4 was not formed in the corrugated plate 1, the amount of the catalyst layer formed was 200 g per liter of the substrate, and Li, Ba and K were added to the catalyst layer in addition to Pt and 0.2 mol per liter of the substrate. , Except that 0.1 mol and 0.1 mol were supported.

An endurance test was conducted in which the filter catalyst of Example 3 was held at 700 ° C. for 50 hours. After the endurance test, the filter catalyst was mounted on the exhaust system of a diesel engine, the engine speed was 2900 rpm, the inlet gas temperature was 300 ° C., every second by spraying 0.1 seconds a / F was measured _the NO _x purification rate under conditions of operating while controlling so as to 14.2. The results are shown in Table 2.

(Comparative Example 3)
A cordierite DPF having a thickness of 0.3 mm and 200 cells / inch ² was prepared, and the same catalyst layer as in Example 3 was formed thereon. In order to obtain the same PM collection rate as that in Example 3, 20% of all plugs on the outer peripheral portion were removed.

For this filter catalyst, the NO _x purification rate was measured in the same manner as in Example 3, and the results are shown in Table 2.

From Table 2, the filter catalyst of Example 3 shows a higher NO _x purification performance than that of Comparative Example 3, which uses a corrugated plate and a flat plate made of a thin metal plate, and a substrate having a large number of filter introduction portions. This is the effect of using it. That is, in the filter catalyst of Example 3, NO in exhaust gas was efficiently oxidized to NO ₂ by the catalyst layer formed in the filter introduction part, and it was efficiently stored in the NO _x storage material. It is considered that the NO _x storage material does not react with the NO _x storage material and that the NO _x storage material does not disappear, and the synergistic effect of these results improves the NO _x purification rate. In addition, the mechanical strength of the substrate is prevented from being lowered.

Example 4
The filter catalyst of this example was inverted so that the exhaust gas inlet side of the filter catalyst of Example 1 was the exhaust gas outlet side, the height of the second peak was low, and the depth of the second valley was shallow. The same is true, and the catalyst layer is not shown.

  The corrugated plate 5 shown in FIG. 9 includes a mountain valley portion 52 in which first mountain portions 50 and first valley portions 51 are alternately continued, and a second valley portion that is continuous with the first mountain portion 50 on the downstream side of the mountain valley portion 52. 53, a second peak portion 52 continuous to the second valley portion 53, a second peak portion 54 continuous to the first valley portion 51 on the downstream side of the second peak portion 52, and a second peak portion 54 On the downstream side, second second valley portions 53 continuous with the first mountain portion 50 of the second mountain valley portion 52 are alternately formed in this order in parallel with the exhaust gas flow direction. The height of the top of the second peak 54 is lower than the depth of the bottom of the first valley 51, and the depth of the bottom of the second valley 53 is shallower than the height of the top of the first peak 50.

  The second valley portion 53 has an inclined surface 55 inclined upward on the downstream side, and the inclined surface 55 is smoothly continuous with the top of the next first mountain portion 50. Further, side walls 56 extending upward in the figure are formed on both sides of the second valley portion 53. Further, the second peak portion 54 has a slope 57 inclined downward on the downstream side, and the slope 57 is smoothly continuous with the bottom of the next first valley portion 51. Side walls 56 extending downward in the figure similar to the second trough portion 53 are formed on both sides of the second peak portion 54.

  The plurality of corrugated plates 5 are laminated such that the phases of the mountain valley portion 52, the second valley portion 53 group, and the second mountain portion 54 group are the same in the exhaust gas flow direction and in the direction perpendicular to the exhaust gas flow direction. In the cross section cut at right angles to the flow direction, the mountain valley portion 52, the second valley portion 53 group, and the second mountain portion 54 group are arranged to be at the same position. The first peak portion 50 and the second peak portion 54 are in contact with the upper flat plate 2, respectively, and the first valley portion 51 and the second valley portion 53 are in contact with the lower flat plate 2, respectively.

  According to this filter catalyst, as shown in FIGS. 10 to 12, the exhaust gas flowing through the first passage 60 formed between the first peak 50 and the lower flat plate 2 flows into the second trough 53 and the upper side. Most of the liquid flows into the first filter introduction portion 65 formed between the flat plate 2 and the flat plate 2. The exhaust gas that has flowed into the first filter introduction portion 65 is narrowed at the downstream end surface by the inclined surface 55 inclined upward, and is guided to the upper flat plate 2 side, and PM is collected on the flat plate 2. The collected PM is oxidized and purified by the catalyst metal supported on the catalyst layer. Even when the amount of collected PM increases, the exhaust gas can flow through the first filter bypass portion formed between the second trough portion 53 and the lower flat plate 2, so that the exhaust gas flow path is completely blocked. Never happen. Moreover, it can distribute | circulate through the opening to the 2nd channel | path of both sides.

  Similarly, the exhaust gas flowing through the second passage 62 formed between the first valley portion 51 and the upper flat plate 2 is the second filter formed between the second peak portion 54 and the lower flat plate 2. Most of it flows into the introduction part 66. The exhaust gas that has flowed into the second filter introduction part 66 is narrowed down by the inclined surface 57 inclined downward and guided to the lower flat plate 2 side, and PM is collected on the flat plate 2. The collected PM is oxidized and purified by the catalyst metal supported on the catalyst layer. Even when the amount of collected PM increases, the exhaust gas can flow through the second filter bypass portion formed between the second peak portion 54 and the upper flat plate 2, so that the exhaust gas flow path is completely blocked. There is nothing.

  Since a large number of filter introduction portions are formed, PM is uniformly dispersed and collected throughout the flat plate 2, improving the collection efficiency and reducing the exhaust pressure loss even if PM is collected. It is hard to rise. That is, the improvement of the PM collection efficiency and the suppression of the increase of the exhaust pressure loss are compatible.

Further, in the filter introduction part, the exhaust gas collides with the slopes 55 and 57, and Pt carried on the catalyst layer 7 becomes NO ₂ with high oxidation activity, and the exhaust gas containing NO ₂ passes through the flat plate 2. Therefore, the oxidation of PM collected on the flat plate 2 is promoted, and the exhaust pressure loss is further reduced.

  In this filter catalyst, although the closed filter introduction parts 100 and 101 are not formed as in the first embodiment, a vector traveling in the direction passing through the flat plate 2 is generated by the force with which the exhaust gas collides. It can be collected by the flat plate 2. Therefore, although not as in Example 1, the improvement in PM collection efficiency and the suppression of the increase in exhaust pressure loss are compatible.

It is a perspective view of the filter catalyst of one Example of this invention. It is a principal part expansion perspective view of the filter catalyst of one Example of this invention. It is a principal part expansion perspective view of the corrugated board used for the filter catalyst of one Example of this invention. It is a principal part expanded sectional view of the filter catalyst of one Example of this invention. It is a principal part expanded sectional view of the filter catalyst of one Example of this invention. It is a principal part expanded sectional view of the filter catalyst of one Example of this invention. It is a principal part expanded sectional view of the filter catalyst of one Example of this invention. It is a principal part expanded sectional view of the filter catalyst of one Example of this invention. It is a principal part expansion perspective view of the corrugated board using the filter catalyst of the 4th Example of this invention. It is a principal part expanded sectional view of the filter catalyst of the 4th Example of this invention. It is a principal part expanded sectional view of the filter catalyst of the 4th Example of this invention. It is a principal part expanded sectional view of the filter catalyst of the 4th Example of this invention.

Explanation of symbols

1: Corrugated plate 2: Flat plate 3: Outer cylinder 4: Communication hole 65, 66: Filter introduction part 100, 101: Filter introduction part

Claims (6)

A corrugated plate made of a thin metal plate, with ridges and valleys alternately alternating in the direction intersecting the exhaust gas flow direction, and a flat plate made of a metal plate with a communication hole penetrating the front and back are alternately laminated. The peak portion and the valley portion constitute an exhaust gas flow path, and at least the flat plate constitutes a filter.
The valley has a convex intermediate peak formed by a shallow valley depth, the peak has a concave intermediate valley formed by a low peak height,
In the portion where the flat plate is laminated on the upper side of the corrugated plate,
A flow path is blocked by the intermediate crests and the crests on both sides adjacent to the intermediate crests and the flat plate in contact with the crests to constitute a filter introduction part that guides exhaust gas to the filter;
The intermediate valley portion includes a branch portion into which exhaust gas branches off from the adjacent valley portion, and an opening communicating with the peak portion on the downstream side, and branches into the exhaust gas flow channel adjacent to the filter introduction portion. A filter bypass unit that bypasses the filter introduction unit,
When the pressure in the filter introduction part increases, at least a part of the exhaust gas flowing through the valley part passes through the filter bypass part existing upstream from the filter introduction part and is adjacent to the mountain. Configured to flow into the
An exhaust gas characterized in that a catalyst layer containing a porous oxide carrying a catalyst metal is formed on the flat plate, and the communication hole is reduced or closed to a pore size of 200 μm or less by the catalyst layer. Purification filter catalyst.   The exhaust gas purification filter catalyst according to claim 1, wherein the communication hole penetrating the front and back is also formed in the corrugated plate.   2. The exhaust gas purification filter catalyst according to claim 1, wherein the peak portion of the adjacent corrugated plate is present on the opposite side of the filter introduction portion through the flat plate. The said intermediate | middle valley part and the said intermediate | middle peak part are formed by deform | transforming the said peak part or the said valley part, respectively, and each upstream end part is continuing smoothly toward the bottom part or the top part. Exhaust gas purification filter catalyst. A corrugated plate and a flat plate having a crest and a valley where the first crests and the first troughs are alternately made of a thin metal plate are alternately laminated,
  A first passage formed by the first peak and a lower flat plate of the corrugated plate;
  A first filter introduction portion formed in the first passage, the second trough portion having a downstream side inclined upward and a flat plate on the upper side of the corrugated plate;
  A first filter bypass portion comprising the second trough and the lower plate of the corrugated plate;
  A second passage formed by the first valley on both sides of the first passage and the flat plate on the upper side of the corrugated plate;
  A second filter introduction portion formed of a second peak portion formed in the second passage and having a downstream side inclined downward, and a flat plate on the lower side of the corrugated plate;
  A second filter bypass portion comprising the second peak and the upper plate of the corrugated plate,
  The depth of the bottom of the second valley is shallower than the height of the top of the first peak, and the height of the top of the second peak is lower than the depth of the bottom of the first valley,
  At least the flat plate of the corrugated plate and the flat plate is formed with a communicating hole penetrating the front and back, and at least the flat plate is formed with a catalyst layer containing a porous oxide carrying a catalytic metal, and the communicating hole is formed. Is an exhaust gas purification filter catalyst characterized in that the pore diameter is reduced or closed to 200 μm or less by the catalyst layer. 6. The apparatus according to claim 5, further comprising at least one of an opening through which exhaust gas can flow from the first filter introduction part to the second passage, or an opening through which exhaust gas can flow from the second filter introduction part to the first passage. Exhaust gas purification filter catalyst.

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