JP5486973B2 - Honeycomb catalyst body and exhaust gas purification device - Google Patents

Description

  The present invention relates to a honeycomb catalyst body and an exhaust gas purification device, and more specifically, includes a honeycomb catalyst body that is difficult to decrease in temperature even when the temperature of exhaust gas discharged from an engine is decreased, and such a honeycomb catalyst body. Thus, the present invention relates to an exhaust gas purification device capable of maintaining high exhaust gas purification performance even when the temperature of exhaust gas discharged from an engine is lowered.

  There is a need to improve the fuel efficiency of automobiles from the viewpoint of global environmental protection and resource saving. Therefore, for the purpose of improving the fuel efficiency of gasoline engines and diesel engines for automobiles, increasing the thermal efficiency of the engine has been studied. However, when the thermal efficiency of the engine is increased, there is a problem that the temperature of the exhaust gas of the engine is lowered, the temperature of the exhaust gas purification catalyst is insufficient, and the purification capability is lowered. Therefore, there is a demand for an exhaust gas purification system that has the performance that the catalyst reaches the activation temperature immediately after the engine is started, and the catalyst that has reached the activation temperature is hardly cooled even when low-temperature exhaust gas flows in and maintains the catalytic activity. Yes.

  Conventionally, a method using a liquid heat medium has been proposed as a method for keeping the catalyst temperature high when the temperature of the exhaust gas of the engine decreases (see, for example, Patent Document 1). In this method, when the exhaust gas temperature is high, heat is accumulated in the liquid heat medium via the heat exchanger, and when the exhaust gas temperature becomes low, the heat exchanger through which the heat medium storing the heat flows flows to the exhaust gas temperature. Or to warm the catalyst support.

JP 2004-270487 A

  However, the method of heating exhaust gas and catalyst carrier using the above heat medium requires a system for circulating and controlling the liquid heat medium, which requires a large-scale system, which requires a large mounting space. However, there was a problem that the cost would be high.

  Furthermore, since a liquid is used as the heat medium, there is a problem that the temperature does not become so high and a large temperature difference cannot be obtained when the stored heat is reused.

  The present invention has been made in view of the above-described problems, and includes a honeycomb catalyst body in which the temperature is hardly lowered even when the temperature of exhaust gas discharged from the engine is lowered, and such a honeycomb catalyst body. Thus, an object of the present invention is to provide an exhaust gas purification device capable of maintaining high exhaust gas purification performance even when the temperature of exhaust gas discharged from an engine is lowered.

  In order to solve the above-described problems, the present invention provides the following honeycomb catalyst body and exhaust gas purification device.

[1] A honeycomb part having a partition wall that partitions and forms a plurality of cells extending from one end face to the other end face that serves as a fluid flow path, and a cylinder having a heat storage part arranged so as to surround the outer periphery of the honeycomb part A honeycomb-shaped honeycomb substrate and a catalyst supported on the partition walls of the honeycomb part, and the material properties of the honeycomb substrate are a thermal conductivity of 20 W / mK or more and a heat capacity of 1800 J / m ³ K or more, The thickness of the heat storage part is 0.03 to 0.5 times the diameter of the honeycomb substrate in a cross section perpendicular to the cell extending direction, and the partition wall thickness of the honeycomb part is 0.05. a ～0.3Mm, cell density of 30 to 200 cells / cm ^2, the amount of supported catalyst in the partition walls of the honeycomb unit Ri 60～400G / liter der, the said honeycomb unit heat storage unit Is sintered The honeycomb catalyst body that will be joined by Rukoto.

[2] The honeycomb catalyst body according to [1], wherein a material of the heat storage unit is mainly Si—SiC.
[3] In the cross section perpendicular to the cell extending direction, the honeycomb part is configured by a central part and an outer peripheral part surrounding the central part, and a partition wall thickness of the outer peripheral part is larger than a partition wall thickness of the central part. The honeycomb catalyst body according to [1] or [2] .

[ 4 ] The honeycomb catalyst body according to [ 3 ], wherein the partition wall thickness of the outer peripheral portion is 1.05 to 2.00 times the partition wall thickness of the central portion.

[ 5 ] The honeycomb catalyst body according to any one of [1] to [ 4 ], wherein the thermal conductivity and heat capacity of the heat storage part of the honeycomb base material are larger than the thermal conductivity and heat capacity of the honeycomb part of the honeycomb base material.

[ 6 ] The honeycomb catalyst body according to any one of [1] to [ 5 ], a partition wall that partitions and forms a plurality of cells extending from one end face to the other end face that serve as a fluid flow path, and disposed on the outermost periphery A cylindrical honeycomb substrate having an outer peripheral wall and a catalyst supported on the partition walls, the partition wall thickness is 0.05 to 0.2 mm, and the cell density is 60 to 180 cells / cm. ^{A second} honeycomb catalyst body, and a cylinder having an inlet opening portion at one end and an outlet opening portion at the other end, in which the honeycomb catalyst body and the second honeycomb catalyst body are housed. And the second honeycomb catalyst body is disposed on the inlet opening side of the can body, the honeycomb catalyst body is disposed on the outlet opening side of the can body, and the second honeycomb The catalyst body and the honeycomb catalyst body open the inlet of the can body. As gas flowing from the part passes through the cells of the honeycomb catalyst body after passing through the cells of the second honeycomb catalyst body, the exhaust gas purifying device arranged in series.

[ 7 ] The honeycomb section of the honeycomb catalyst body has a diameter in a cross section perpendicular to the cell extending direction of 0.9% or more of the diameter of the second honeycomb catalyst body in the cross section orthogonal to the cell extending direction. The exhaust gas purifying apparatus according to [ 6 ].

The honeycomb catalyst body of the present invention includes a “honeycomb portion having partition walls that form a plurality of cells and a tubular honeycomb base material having a heat storage portion disposed so as to surround the outer periphery of the honeycomb portion” and “honeycomb The material properties of the honeycomb base material have a thermal conductivity of 20 W / mK or more and a heat capacity of 1800 J / m ³ K or more, and the thickness of the heat storage part is honeycomb base material Since it is 0.03 to 0.5 times the diameter “in the cross section orthogonal to the cell extending direction”, the heat of the exhaust gas can be stored in the heat storage part when used as part of the exhaust gas purification device. Even if the temperature of the exhaust gas discharged from the engine is lowered, the temperature of the catalyst and the temperature of the exhaust gas when passing through the honeycomb part can be kept high by the heat stored in the heat storage part.

  The exhaust gas purifying apparatus of the present invention is provided on the outermost periphery and the partition wall that partition and form “the honeycomb catalyst body of the present invention”, “a plurality of cells extending from one end surface to the other end surface that serve as a fluid flow path”. A cylindrical honeycomb substrate having an outer peripheral wall, and a second honeycomb catalyst body having a catalyst supported on partition walls, and a "honeycomb catalyst body and second honeycomb catalyst body housed inside, at one end portion A cylindrical can body having an inlet opening and having an outlet opening at the other end ”, the second honeycomb catalyst body is disposed on the inlet opening side of the can body, and the honeycomb catalyst body is a can body The second honeycomb catalyst body and the honeycomb catalyst body are arranged so that “the gas flowing in from the inlet opening of the can body passes through the cells of the second honeycomb catalyst body, `` Pass through the cell '' and placed in series Therefore, when purifying the exhaust gas, the heat of the exhaust gas can be stored in the heat storage part of the honeycomb catalyst body, and even if the temperature of the exhaust gas discharged from the engine decreases, the heat stored in the heat storage part Thus, the temperature of the catalyst and the temperature of the exhaust gas when passing through the honeycomb portion can be kept high.

1 is a perspective view schematically showing one embodiment of a honeycomb catalyst body of the present invention. It is a schematic diagram which shows the cross section parallel to the cell extending direction of one embodiment of the honeycomb catalyst body of the present invention. It is a schematic diagram which shows the cross section orthogonal to the cell extending direction of one Embodiment of the honeycomb catalyst body of this invention. It is a schematic diagram which shows the cross section orthogonal to the cell extending direction of other embodiment of the honeycomb catalyst body of this invention. FIG. 6 is a schematic view showing a cross section perpendicular to the cell extending direction of still another embodiment of the honeycomb catalyst body of the present invention. It is a schematic diagram which shows the cross section parallel to the direction through which gas flows of one Embodiment of the exhaust gas purification apparatus of this invention. It is a schematic diagram which shows the cross section parallel to the direction through which gas flows of other embodiment of the exhaust gas purification apparatus of this invention. 4 is a graph showing changes in gas (exhaust gas) temperature, honeycomb catalyst body temperature, and second honeycomb catalyst body temperature when exhaust gas flows through the exhaust gas purification apparatus. It is a schematic diagram which shows a pressure loss measuring apparatus.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and those skilled in the art do not depart from the spirit of the present invention. It should be understood that design changes, improvements, and the like can be made as appropriate based on ordinary knowledge.

(1) Honeycomb catalyst body:
In one embodiment of the honeycomb catalyst body of the present invention, as shown in FIGS. 1 to 3, a plurality of cells 2 extending from one end surface 11 to the other end surface 12 which become a flow path of fluid (exhaust gas) are partitioned. A cylindrical honeycomb substrate 5 having a honeycomb portion 3 having partition walls 1 and a heat storage portion 4 disposed so as to surround the outer periphery of the honeycomb portion 3, and a catalyst supported on the partition walls 1 of the honeycomb portion 3. And the material properties of the honeycomb substrate 5 have a thermal conductivity of 20 W / mK or more and a heat capacity of 1800 J / m ³ K or more, and the thickness of the heat storage section 4 is orthogonal to the cell extending direction of the honeycomb substrate 5. 0.03 to 0.5 times the diameter of the cross section to be formed, the thickness of the partition wall 1 of the honeycomb portion 3 is 0.05 to 0.3 mm, and the density of the cells 2 is 30 to ²⁰⁰ cells / cm ² The amount of the catalyst supported on the partition walls 1 of the honeycomb part 3 is It is a 0~400g / liter. Here, the material physical properties mean physical properties of a plate-like sample cut out from the honeycomb substrate. FIG. 1 is a perspective view schematically showing one embodiment of a honeycomb catalyst body of the present invention. FIG. 2 is a schematic diagram showing a cross section parallel to the cell extending direction of one embodiment of the honeycomb catalyst body of the present invention. FIG. 3 is a schematic diagram showing a cross section perpendicular to the cell extending direction of one embodiment of the honeycomb catalyst body of the present invention.

Thus, according to the honeycomb catalyst body 100 of the present embodiment, “the honeycomb part 3 having the partition walls 1 that partition the plurality of cells 2 and the heat storage part 4 disposed so as to surround the outer periphery of the honeycomb part 3”. The honeycomb substrate 5 has a thermal conductivity of 20 W / mK or more and a heat capacity of 1800 J / m ³ K. Since the thickness of the heat storage section 4 is 0.03 to 0.5 times the diameter of the honeycomb substrate 5 "in the cross section perpendicular to the cell 1 extending direction", a part of the exhaust gas purification device When it is used as, it can store the heat of exhaust gas in the heat storage part, and even if the temperature of the exhaust gas discharged from the engine decreases, the heat of the heat storage part passes through the temperature of the catalyst and the honeycomb part Increase the temperature of the exhaust gas when It is possible to equity.

  In the honeycomb catalyst body of the present embodiment, when high-temperature exhaust gas passes through the honeycomb part, the partition walls of the honeycomb part are heated, and the temperature of the partition walls rises. And the heat of a partition is transmitted to a thermal storage part, a thermal storage part is heated, and heat is stored in a thermal storage part. When low-temperature exhaust gas flows through the honeycomb part in a state where the heat storage part is heated, the honeycomb part is deprived of heat by the low-temperature exhaust gas, but the heat stored in the heat storage part is transferred to the honeycomb part by heat conduction in the solid. This is effective in slowing the temperature drop of the honeycomb part. Thereby, even if the temperature of the exhaust gas discharged from the engine is lowered, the temperature of the catalyst and the temperature of the exhaust gas when passing through the honeycomb part can be kept high by the heat stored in the heat storage part.

  In the honeycomb catalyst body 100 of the present embodiment, the heat storage section 4 is disposed on the outer edge portion of the honeycomb base material 5 in a cross section orthogonal to the cell extending direction.

In the honeycomb catalyst body 100 of the present embodiment, the material properties of the honeycomb substrate 5 are “thermal conductivity of 20 W / mK or more and heat capacity of 1800 J / m ³ K or more”, “thermal conductivity of 40 W / mK or more, and The heat capacity is more preferably 2000 J / m ³ K or more, particularly preferably “heat conductivity 70 W / mK or more and heat capacity 3000 J / m ³ K or more”, the heat conductivity 100 W / mK or more, and the heat capacity. 3300 J / m ³ K or more ”is most preferable. The higher the thermal conductivity of the honeycomb substrate, the better, but the upper limit is about 300 W / mK. The higher the heat capacity of the honeycomb substrate, the better, but the upper limit is about 4000 J / m ³ K. The unit “W / mK” means “W / (m · K)”, and the unit “J / m ³ K” means “J / (m ³ · K)”.

If the thermal conductivity of the honeycomb substrate 5 is less than 20 W / mK, the rate of heat storage in the heat storage unit 4 is slow, and further, the rate at which the heat stored in the heat storage unit 4 is transferred to the honeycomb unit 3 is not preferable. . If the heat capacity of the honeycomb substrate 5 is smaller than 1800 J / m ³ K, it is not preferable because sufficient heat cannot be stored in the heat storage section 4. Thus, when the honeycomb substrate 5 has “thermal conductivity of 20 W / mK or more and heat capacity of 1800 J / m ³ K or more”, a large amount of heat can be stored in the heat storage unit 4 in a short time, When the temperature of the exhaust gas decreases, the heat stored in the heat storage unit 4 can be transmitted to the honeycomb unit side in a short time, and the temperature of the catalyst and the temperature of the exhaust gas when passing through the honeycomb unit are kept high. Can do. The heat capacity of the honeycomb part is the heat capacity of the partition walls constituting the honeycomb part.

  Furthermore, in the honeycomb catalyst body 100 of the present embodiment, the partition wall 1 of the honeycomb portion 3 has a thickness of 0.05 to 0.3 mm, preferably 0.05 to 0.2 mm. If the partition wall 1 is thinner than 0.05 mm, it is not preferable because the strength of the honeycomb catalyst body is lowered. Moreover, the heat stored in the heat storage part is not preferable because it is difficult to be transmitted to the catalyst and the exhaust gas through the partition walls of the honeycomb part. If the partition wall thickness is greater than 0.3 mm, the pressure loss when the exhaust gas flows through the honeycomb catalyst body 100 becomes undesirably large.

Furthermore, in the honeycomb catalyst body 100 of the present embodiment, the cell density of the honeycomb portion 3 is 30 to ²⁰⁰ cells / cm ² , and preferably 30 to 95 cells / cm ² . When the cell density is lower than 30 cells / cm ² , the strength of the honeycomb catalyst body decreases, which is not preferable. Moreover, the heat stored in the heat storage part is not preferable because it is difficult to be transmitted to the catalyst and the exhaust gas through the partition walls of the honeycomb part. When the cell density is higher than 200 cells / cm ² , the pressure loss when the exhaust gas flows through the honeycomb catalyst body 100 increases, which is not preferable.

  Furthermore, the honeycomb catalyst body 100 of the present embodiment has a catalyst loading of 60 to 400 g / liter. If it is less than 60 g / liter, the purification performance is lowered, which is not preferable. If it is more than 400 g / liter, the pressure loss when the exhaust gas flows is increased, which is not preferable.

  The thickness t (see FIG. 2) of the heat storage section 4 of the honeycomb base material 5 is 0.03 to 0 of the diameter D (see FIG. 2) of the honeycomb base material 5 in a cross section orthogonal to the cell 2 extending direction. It is preferably 5 times, more preferably 0.04 to 0.5 times. If the thickness t is thinner than 0.03 times the diameter D, the heat storage effect of the heat storage section 4 is lowered, which is not preferable. If the thickness t is thicker than 0.5 times the diameter D, it may take a long time for heat storage and heat dissipation, and the heat storage and heat dissipation functions of the heat storage section cannot be used in a timely manner with respect to temperature changes of the exhaust gas. is there.

  In the honeycomb catalyst body 100 of this embodiment, the porosity of the honeycomb substrate 5 is preferably 5% or less. That the porosity of the honeycomb substrate 5 is 5% or less indicates that the material of the honeycomb substrate is dense. The porosity of the honeycomb substrate 5 is the porosity of the “partition of the honeycomb part 3” and the heat storage part 4. When the porosity of the honeycomb substrate 5 is 5% or less, the thermal conductivity and heat capacity of the honeycomb substrate 5 can be increased. When the porosity of the honeycomb substrate 5 is larger than 40%, the thermal conductivity and the heat capacity are lowered, which is not preferable. The porosity is a value measured with a mercury porosimeter. The porosity of the honeycomb substrate 5 may be 0%, but substantially the lower limit is about 0.1%.

  In the honeycomb catalyst body 100 of the present embodiment, the average pore diameter of the partition walls 1 of the honeycomb portion 3 is preferably 6 μm or less. When the average pore diameter is larger than 50 μm, the thermal conductivity and heat capacity of the heat storage part may be lowered. The average pore diameter is a value measured with a mercury porosimeter.

  In the honeycomb catalyst body 100 of the present embodiment, the material of the honeycomb part and the heat storage part is mainly composed of silicon carbide, silicon-silicon carbide composite material (silicon carbide particles bonded by silicon) or silicon nitride. It is preferable. Here, the “main component” is a component contained in 90% by mass or more of the whole. Furthermore, the material of the honeycomb part and the heat storage part is dense silicon nitride (porosity 1% or less), dense recrystallized silicon carbide (porosity 1% or less), or dense silicon-silicon carbide composite material (porosity 1). % Or less). In the honeycomb catalyst body 100 of the present embodiment, the material of the honeycomb part and the material of the heat storage part are preferably the same from the viewpoint of preventing a difference in thermal expansion between the honeycomb part and the heat storage part. .

  In the honeycomb catalyst body 100 of the present embodiment, it is preferable that the thermal expansion coefficient of the honeycomb portion and the thermal expansion coefficient of the heat storage portion are close to each other. Thereby, it can prevent that a crack generate | occur | produces with the thermal stress by the thermal expansion difference at the time of a temperature change.

  In the honeycomb catalyst body 100 of the present embodiment, it is preferable that the honeycomb portion and the heat storage portion are joined by sintering. As a result, heat can be efficiently transferred even at the boundary portion between the honeycomb portion and the heat storage portion without being interrupted. When the honeycomb portion and the heat storage portion are joined by sintering, a clear interface is not formed at the boundary portion between the honeycomb portion and the heat storage portion, and the honeycomb portion and the heat storage portion are continuously formed. It is preferable that they are connected.

  In the honeycomb catalyst body 100 of the present embodiment, the shape of the cell 2 in the cross section perpendicular to the extending direction of the cell 2 is not particularly limited, but may be a polygon such as a quadrangle, a hexagon, or an octagon. preferable. By making the cell shape in this way, there is an advantage that the pressure loss when exhaust gas flows is small and the purification performance of the catalyst is excellent.

  The shape of the honeycomb catalyst body 100 of the present embodiment is preferably a cylindrical shape (cylindrical shape) with a circular bottom surface. The honeycomb catalyst body preferably has a bottom diameter of 80 to 200 mm. The length of the honeycomb catalyst body in the central axis direction is preferably 50 to 300 mm. In the honeycomb catalyst body 100 of the present embodiment, it is preferable that the honeycomb portion 3 has a cylindrical shape (cylindrical shape) with a circular bottom surface.

The honeycomb catalyst body 100 of the present embodiment includes a catalyst supported on the partition walls of the honeycomb portion. The catalyst supported can include a three-way catalyst, NO _X purification catalyst, an oxidation catalyst or the like. Examples of the three-way catalyst include those in which noble metals such as Pt, Pd, and Rh are supported on a carrier mainly composed of alumina and ceria. The NO _X purification catalyst includes Pt and “Ba or K as NO _X storage component” supported on a carrier mainly composed of alumina, “Zeolite metal-substituted by Fe or Cu” as a main component. And the like.

  Next, another embodiment of the honeycomb catalyst body of the present invention will be described. As shown in FIG. 4, in another embodiment of the honeycomb catalyst body of the present invention, the honeycomb part 3 includes a central part 3a and an outer peripheral part 3b surrounding the central part 3a in a cross section perpendicular to the cell extending direction. The partition wall thickness of the outer peripheral part 3b is thicker than the partition wall thickness of the central part 3a. Thus, when the partition wall thickness of the outer peripheral part 3b is thicker than the partition wall thickness of the center part 3a, it becomes possible to transmit the heat | fever of waste gas to a heat storage part through a partition in a short time, and also a heat storage part. It is possible to transfer the heat stored in to the partition walls of the honeycomb portion in a short time. In the honeycomb catalyst body 200 of the present embodiment, in the honeycomb part 3, the conditions other than that the partition wall thickness of the outer peripheral part 3b is thicker than the partition wall thickness of the center part 3a are the same as those of the honeycomb catalyst body of the present invention. It is preferable that it is the same as embodiment. FIG. 4 is a schematic view showing a cross section perpendicular to the cell extending direction of another embodiment of the honeycomb catalyst body of the present invention.

  In the honeycomb catalyst body 200 of the present embodiment, the partition wall thickness in the outer peripheral portion is preferably 1.05 to 2.00 times, and 1.1 to 1.5 times the partition wall thickness in the central portion. Is more preferable. If it is thinner than 1.05 times, the speed of heat conduction may be slow, and if it is thicker than 2.00 times, pressure loss may be increased.

  Moreover, it is preferable that the diameter of the center part of the honeycomb part 3 is 0.3 to 0.7 times the diameter of the honeycomb part 3 in the cross section orthogonal to the cell extending direction. If it is less than 0.3 times, the pressure loss may be large, and if it is more than 0.7 times, the heat conduction speed may be slow.

  Next, still another embodiment of the honeycomb catalyst body of the present invention will be described. In the honeycomb catalyst body of the present embodiment, as shown in FIG. 5, in the cross section orthogonal to the cell extending direction, the honeycomb portion 3 is disposed so as to draw a concentric circle on the central portion 3a and the outer periphery of the central portion 3a. The outer peripheral layers 3bα and 3bβ are two layers, and the outer layer is formed thicker in the order of the central portion 3a, the outer peripheral layer 3bβ, and the outer peripheral layer 3bα. In the honeycomb catalyst body 300 of the present embodiment, the outer peripheral portion 3b is constituted by the outer peripheral layers 3bα and 3bβ. As a result, the heat of the exhaust gas can be transmitted to the heat storage section through the partition walls in a shorter time, and further, the heat stored in the heat storage section can be transmitted to the partition walls of the honeycomb section in a short time. It becomes. The honeycomb catalyst body of the present embodiment has two outer peripheral layers. However, the honeycomb catalyst body is not limited to two layers, and may be a plurality of layers as long as the outer layer has a thicker partition wall. The honeycomb catalyst body 300 of the present embodiment is different from the honeycomb catalyst body of the present invention (honeycomb) except that the outer peripheral portion 3b of the honeycomb portion 3 is formed by the outer peripheral layers 3bα and 3bβ. The catalyst body 200 is preferably the same as the catalyst body 200 (see FIG. 4). FIG. 5 is a schematic view showing a cross section orthogonal to the cell extending direction of still another embodiment of the honeycomb catalyst body of the present invention. In FIG. 5, cells and partition walls in the honeycomb portion 3 are omitted.

  Further, as still another embodiment of the honeycomb catalyst body of the present invention, in the cross section orthogonal to the cell extending direction, the partition wall of the honeycomb part is formed with the thickest outer peripheral part and the thinnest central part, and from the outer peripheral part. The thing formed so that it may become thin continuously toward a center part can be mentioned. As a result, the heat of the exhaust gas can be transmitted to the heat storage section through the partition walls in a shorter time, and further, the heat stored in the heat storage section can be transmitted to the partition walls of the honeycomb section in a short time. It becomes. In the honeycomb catalyst body of the present embodiment, the partition walls of the honeycomb part are formed such that the outer peripheral part is the thickest, the central part is the thinnest, and the outer peripheral part is continuously thinned from the central part. The other conditions are preferably the same as in the embodiment of the honeycomb catalyst body of the present invention.

  Next, still another embodiment of the honeycomb catalyst body of the present invention will be described. In the honeycomb catalyst body of the present embodiment, the thermal conductivity and heat capacity of the heat storage part of the honeycomb base material are larger than the thermal conductivity and heat capacity of the honeycomb part of the honeycomb base material. Thereby, the thermal storage effect of a thermal storage part can be improved more. The honeycomb catalyst body of the present embodiment is the same as the above-described honeycomb structure of the present invention except that the thermal conductivity and heat capacity of the heat storage part of the honeycomb base material are larger than the thermal conductivity and heat capacity of the honeycomb part of the honeycomb base material. It is preferable that it is the same as that of one embodiment of a catalyst body.

  In the honeycomb catalyst body of the present embodiment, it is preferable that the material of the honeycomb portion is mainly composed of silicon carbide, a silicon-silicon carbide composite material, or silicon nitride. Moreover, it is preferable that the material of a thermal storage part is metal A, such as copper, bronze, aluminum, and silicon. The material for the heat storage part is dense silicon nitride (porosity 1% or less), dense recrystallized silicon carbide (porosity 1% or less), dense silicon-silicon carbide composite (porosity 1% or less). It is preferable that it is ceramic B, such as. Moreover, the composite C of ceramic B and metals, such as copper, bronze, aluminum, and silicon, may be sufficient. Furthermore, as a material for the heat storage part, ceramic particles (for example, zirconia or zirconium phosphate) having a high heat capacity or ceramic fibers (for example, zirconia fiber or zirconium phosphate fiber) having a high heat capacity are mixed into the ceramic B or the composite C. Complex B can be mentioned.

(2) Exhaust gas purification device:
Next, an embodiment of the exhaust gas purification apparatus of the present invention will be described.

As shown in FIG. 6, the exhaust gas purifying apparatus of the present embodiment has one embodiment (honeycomb catalyst body 100) of the honeycomb catalyst body of the present invention and from one end surface serving as a fluid flow path to the other end surface. A partition wall 21 that defines a plurality of extending cells 22, a cylindrical honeycomb substrate 25 having an outer peripheral wall 23 disposed on the outermost periphery, and a catalyst supported on the partition wall 21, the partition wall 21 having a thickness of One end of the second honeycomb catalyst body 24 having a cell density of 0.05 to 0.2 mm and a cell density of 60 to 180 cells / cm ² , and the honeycomb catalyst body 100 and the second honeycomb catalyst body 24 accommodated therein. And a cylindrical can body 33 having an outlet opening 32 at the other end, and the second honeycomb catalyst body 24 is disposed on the inlet opening 31 side of the can body 33. The honeycomb catalyst body 100 is exposed to the can body 33. The second honeycomb catalyst body 24 and the honeycomb catalyst body 100 are arranged on the side of the mouth opening 32, and “the gas G flowing from the inlet opening 31 of the can body 33 passes through the cells 22 of the second honeycomb catalyst body 24. After passing, it is arranged in series so as to pass through the cell 2 of the honeycomb catalyst body 100. FIG. 6 is a schematic diagram showing a cross section parallel to the gas flow direction of one embodiment of the exhaust gas purifying apparatus of the present invention.

  Thus, since the exhaust gas purification apparatus 500 of the present embodiment is configured as described above, when purifying exhaust gas, the heat storage part 4 of the honeycomb catalyst body 100 can store the heat of exhaust gas, Even if the temperature of the exhaust gas discharged from the engine is lowered, the temperature of the catalyst can be kept high by the heat stored in the heat storage section 4. When exhaust gas is allowed to flow through the exhaust gas purification apparatus 500, the “gas (exhaust gas) temperature, the temperature of the honeycomb catalyst body, and the temperature of the second honeycomb catalyst body” are represented by a graph as shown in FIG. 8, for example. FIG. 8 is a graph showing changes in the gas (exhaust gas) temperature, the honeycomb catalyst body temperature, and the second honeycomb catalyst body temperature when the exhaust gas flows through the exhaust gas purification apparatus 500. In FIG. 8, the horizontal axis indicates the time for flowing gas (exhaust gas), and the vertical axis indicates the temperature. In FIG. 8, a straight line drawn in parallel with the horizontal axis indicates “catalytic activity temperature”. When the temperature is higher than the catalytic activity temperature, the catalyst exhibits catalytic activity and exhibits an exhaust gas purification function. In FIG. 8, when the time T1 is passed, the temperature of the honeycomb catalyst body becomes higher than the temperature of the second honeycomb catalyst body. Therefore, after the time T1, the exhaust gas purification by the honeycomb catalyst body is mainly performed. . When the time T2 is exceeded, the temperature of the honeycomb catalyst body is higher than the “catalytic activation temperature”, but the temperature of the second honeycomb catalyst body is lower than the “catalytic activation temperature”. Only the exhaust gas purification is performed.

  The exhaust gas purifying apparatus of the present embodiment is provided with one embodiment of the honeycomb catalyst body of the present invention, but may be provided with the honeycomb catalyst body of the present invention. Any embodiment such as the above embodiments may be provided.

  In the exhaust gas purification apparatus 500 of the present embodiment, the second honeycomb catalyst body 24 is formed by supporting a catalyst on a honeycomb-shaped substrate (honeycomb substrate) having the following cell density and partition wall thickness. A honeycomb catalyst body is used. For example, the following are preferable.

  As described above, the honeycomb catalyst body 24 constituting the exhaust gas purification apparatus 500 of the present embodiment has the partition wall 21 and the outermost periphery that partition and form a plurality of cells 22 extending from one end face to the other end face that serve as a fluid flow path. A cylindrical honeycomb base material 25 having an outer peripheral wall 23 disposed on the surface of the substrate and a catalyst supported on the partition walls 21.

In the second honeycomb catalyst body 24, the cell density of the honeycomb base material 25 is 60 to 180 cells / cm ² , and preferably 60 to 95 cells / cm ² . When the cell density is less than 60 cells / cm ² , the contact efficiency with the exhaust gas is lowered, which is not preferable. When the cell density exceeds 180 cells / cm ² , the pressure loss increases, which is not preferable.

  Furthermore, in the second honeycomb catalyst body 24, the thickness of the partition walls 21 of the honeycomb substrate 25 is 0.05 to 0.20 mm, and preferably 0.05 to 0.16 mm. If the partition wall thickness is less than 0.05 mm, the strength is insufficient and the thermal shock resistance is lowered, which is not preferable. If it exceeds 0.20 mm, the pressure loss increases, which is not preferable.

  The partition walls 21 of the honeycomb substrate 25 may be dense or porous. When the partition wall 21 is porous, the catalyst can be supported in the pores of the partition wall, and the amount of the catalyst supported can be increased. When the partition wall 21 is porous, the average pore diameter of the partition wall 21 is preferably 0.5 to 6 μm. The average pore diameter of the partition wall is a value measured by a mercury porosimeter (mercury intrusion method). Moreover, when the partition 21 is porous, it is preferable that the porosity of the partition 21 is 0.01 to 5%. The average pore diameter of the partition wall is a value measured by a mercury porosimeter (mercury intrusion method).

  The material of the honeycomb substrate 25 constituting the second honeycomb catalyst body 24 is preferably a material mainly composed of ceramics. Preferred examples of ceramics include silicon carbide, silicon-silicon carbide composite material, cordierite, alumina titanate, sialon, mullite, silicon nitride, zirconium phosphate, zirconia, titania, alumina, silica, or a combination thereof. Can be mentioned. In particular, ceramics such as silicon carbide, silicon-silicon carbide composite material, cordierite, mullite, silicon nitride, and alumina are preferable in terms of alkali resistance. Among these, oxide-based ceramics are preferable because of their low cost.

  The shape of the cross section perpendicular to the central axis of the second honeycomb catalyst body 24 (honeycomb substrate 25) is not particularly limited, and examples thereof include a circle, an ellipse, an oval, a quadrangle, a hexagon, and the like. Of these, a circular shape is preferable. In addition, the shape of the cross section of the second honeycomb catalyst body 24 (honeycomb substrate 25) perpendicular to the central axis is preferably the same as the shape of the cross section of the honeycomb catalyst body 100 perpendicular to the central axis.

  The size of the second honeycomb catalyst body 24 (honeycomb substrate 25) is not particularly limited, but the bottom diameter is preferably 80 to 200 mm. The length of the second honeycomb catalyst body 24 (honeycomb substrate 25) in the central axis direction is preferably 50 to 300 mm.

  Further, as in the exhaust gas purification apparatus 600 shown in FIG. 7, the diameter of the bottom surface of the honeycomb portion 3 of the honeycomb base material 5 of the honeycomb catalyst body 100 is 0 of the diameter of the bottom surface of the second honeycomb catalyst body 24 (honeycomb base material). It is preferably 9 times or more, and more preferably 0.9 to 0.98 times. Thereby, the fall of the pressure loss at the time of gas passing through the honeycomb catalyst body 24 can be prevented. FIG. 7 is a schematic view showing a cross section parallel to the gas flow direction of another embodiment of the exhaust gas purifying apparatus of the present invention.

  In the exhaust gas purification apparatus 500 of the present embodiment shown in FIG. 6, the distance between the honeycomb catalyst body 100 and the second honeycomb catalyst body 24 is preferably 1 to 50 mm. If it is shorter than 1 mm, the honeycomb catalyst body 100 and the second honeycomb catalyst body 24 may come into contact with each other and be damaged during use. When it is longer than 50 mm, heat may easily escape from between the honeycomb catalyst body 100 and the second honeycomb catalyst body 24.

  The exhaust gas purifying apparatus 500 of the present embodiment has the inlet opening 31 at one end and the outlet opening 32 at the other end, in which the honeycomb catalyst body 100 and the second honeycomb catalyst body 24 are housed. A cylindrical can body 33 is provided. The second honeycomb catalyst body 24 is disposed on the inlet opening 31 side of the can body 33, the honeycomb catalyst body 100 is disposed on the outlet opening 32 side of the can body 33, and the second honeycomb catalyst body 24 and the honeycomb are disposed. The catalyst body 100 is connected in series so that "the gas G flowing from the inlet opening 31 of the can body 33 passes through the cells 2 of the honeycomb catalyst body 100 after passing through the cells 22 of the second honeycomb catalyst body 24". Has been placed. The second honeycomb catalyst body 24 is disposed on the upstream side when the gas G flows from the inlet opening 31 of the can body 33, and the honeycomb catalyst body 100 flows the gas G from the inlet opening 31 of the can body 33. In this case, it is arranged on the downstream side. Further, in the exhaust gas purifying apparatus 500 of the present embodiment, the second honeycomb catalyst body and the honeycomb catalyst body are such that one end face of the second honeycomb catalyst body 24 faces the inlet opening 31 side of the can body 33, and The other end face of the catalyst body 24 and one end face of the honeycomb catalyst body 100 face each other, and the other end face of the honeycomb catalyst body 100 faces the outlet opening 32 side of the can body 33 and is disposed in the can body 33. It can also be said.

  In the exhaust gas purifying apparatus 500 of this embodiment, the can 33 has a cylindrical shape having the inlet opening 31 at one end and the outlet opening 32 at the other end. The shape of the can 33 can be appropriately determined according to the shapes of the honeycomb catalyst body and the second honeycomb catalyst body. For example, the length of the can 33 in the gas flow direction is 1.1 to 1.5 of the sum of the length of the honeycomb catalyst body in the cell extending direction and the length of the second honeycomb catalyst body in the cell extending direction. It is preferable that it is double. If it is shorter than 1.1 times, it may be difficult to accommodate the honeycomb catalyst body and the second honeycomb catalyst body. If it is longer than 1.5 times, the exhaust gas purification device may become too large. The diameter of the cross section perpendicular to the central axis of the portion of the can 33 where the honeycomb catalytic body is inserted is 1.05 to 1.1 times the diameter of the cross section perpendicular to the central axis of the honeycomb catalytic body. Preferably there is. The diameter of the cross section perpendicular to the central axis of the portion of the can 33 where the second honeycomb catalyst body is inserted is 1.1 to 1 of the diameter of the cross section perpendicular to the central axis of the second honeycomb catalyst body. .3 times is preferable.

  The material of the can 33 is not particularly limited, and examples thereof include iron and stainless steel.

  In the exhaust gas purifying apparatus 500 of the present embodiment, the honeycomb catalyst body 100 and the second honeycomb catalyst body 24 are accommodated in the cylindrical body 33 with the filler 35 disposed on the outer periphery. The honeycomb catalyst body 100 and the second honeycomb catalyst body 24 are preferably accommodated in the cylindrical body 33 in a state where the filler 35 is compressed. Although it does not specifically limit as the filler 35, A heat resistant inorganic insulation mat etc. can be mentioned. Further, the honeycomb catalyst body 100 and the second honeycomb catalyst body 24 are fixed so as not to move in the cylindrical body 33 by a fastener 34 “attached to the inside of the can body 33 so as to protrude toward the inside”. It is preferable. The material of the fastener 34 is not particularly limited, and examples thereof include iron and stainless steel.

(3) Manufacturing method of honeycomb catalyst body:
Next, a manufacturing method of one embodiment of the honeycomb catalyst body of the present invention will be described.

  First, it is preferable to prepare a forming raw material by adding metal silicon powder (metal silicon), a binder, a surfactant, water, or the like to silicon carbide powder (silicon carbide). It is preferable that the mass of the metal silicon is 10 to 30% by mass with respect to the total of the mass of the silicon carbide powder and the mass of the metal silicon. The raw material to be used can be appropriately determined so that the honeycomb base material of the honeycomb catalyst body to be manufactured is a desired material. For example, when the material of the honeycomb base material is silicon nitride Instead of silicon carbide powder and metal silicon powder, silicon nitride powder is used.

  Examples of the binder include methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. The content of the binder is preferably 1 to 10 parts by mass when the total of the mass of the silicon carbide powder and the mass of the metal silicon is 100 parts by mass.

  The water content is preferably 20 to 35 parts by mass when the total of the mass of the silicon carbide powder and the mass of metal silicon is 100 parts by mass.

  As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type. The content of the surfactant is preferably 0.1 to 5 parts by mass when the total of the mass of the silicon carbide powder and the mass of the metal silicon is 100 parts by mass.

  Next, the forming raw material is kneaded to form a clay. There is no restriction | limiting in particular as a method of kneading | mixing a shaping | molding raw material and forming a clay, For example, the method of using a kneader, a vacuum clay kneader, etc. can be mentioned.

  Next, the kneaded material is extruded to form a honeycomb formed body. In extrusion molding, it is preferable to use a die having a desired overall shape, cell shape, partition wall thickness, cell density and the like. As the material of the die, a cemented carbide which does not easily wear is preferable. The honeycomb formed body has a structure having porous partition walls that define and form a plurality of cells serving as fluid flow paths and an outer peripheral wall located at the outermost periphery.

  The partition wall thickness, cell density, outer peripheral wall thickness, and the like of the honeycomb formed body can be appropriately determined according to the structure of the honeycomb catalyst body of the present invention to be manufactured in consideration of shrinkage during drying and firing. For example, it is preferable to form a honeycomb formed body having a portion corresponding to the honeycomb portion and a portion corresponding to the heat storage portion.

  Moreover, you may form the honeycomb molded object provided only with the part corresponded to a honeycomb part. In the case where a honeycomb molded body having only a portion corresponding to the honeycomb portion is formed, a portion corresponding to the heat storage portion is separately formed, and a portion corresponding to the heat storage portion is provided with a portion corresponding to the honeycomb portion. It is preferable that the honeycomb formed body is wound and then fired. In this case, the part corresponding to the heat storage part is preferably formed by an extrusion molding method.

  The obtained honeycomb formed body is preferably dried before firing. The drying method is not particularly limited, and examples thereof include an electromagnetic heating method such as microwave heating drying and high-frequency dielectric heating drying, and an external heating method such as hot air drying and superheated steam drying. Among these, the entire molded body can be dried quickly and uniformly without cracks, and after drying a certain amount of moisture with an electromagnetic heating method, the remaining moisture is dried with an external heating method. It is preferable to make it. As drying conditions, it is preferable to remove moisture of 30 to 99% by mass with respect to the amount of moisture before drying by an electromagnetic heating method, and then to make the moisture to 3% by mass or less by an external heating method. As the electromagnetic heating method, dielectric heating drying is preferable, and as the external heating method, hot air drying is preferable.

  Next, when the length of the honeycomb formed body in the central axis direction is not a desired length, it is preferable to cut both end faces (both end portions) to a desired length. The cutting method is not particularly limited, and examples thereof include a method using a circular saw cutting machine.

  Next, the honeycomb fired body is preferably fired to produce a honeycomb fired body. In order to remove the binder or the like before firing, it is preferable to perform temporary firing. Pre-baking is preferably performed at 400 to 500 ° C. for 0.5 to 20 hours in an air atmosphere. The method of temporary baking and baking is not particularly limited, and baking can be performed using an electric furnace, a gas furnace, or the like. Firing conditions are preferably 1450 to 1550 ° C. for 1 to 20 hours in an inert atmosphere such as nitrogen or argon.

  Next, it is preferable to form a honeycomb catalyst body by supporting a catalyst on the obtained honeycomb fired body. The method for supporting the catalyst is not particularly limited, and the catalyst can be supported by a known method. For example, first, a catalyst slurry containing a predetermined catalyst is prepared. Next, the catalyst slurry is coated on the partition wall surfaces of the honeycomb fired body by a method such as a suction method. Then, a honeycomb catalyst body can be obtained by drying at room temperature or under heating conditions. The slurry concentration of the catalyst slurry is preferably 10 to 50% by mass.

  The catalyst supported on the honeycomb fired body is preferably a catalyst that is considered preferable in one embodiment of the honeycomb catalyst body of the present invention.

(4) Manufacturing method of exhaust gas purification device:
(4-1) Honeycomb catalyst body;
The honeycomb catalyst body constituting the exhaust gas purification device is preferably produced by the method for manufacturing a honeycomb catalyst body of the present invention.

(4-2) Second honeycomb catalyst body;

  First, it is preferable to prepare a forming raw material by adding a ceramic raw material, a binder, a surfactant, a pore former, water and the like. Ceramic raw materials include silicon carbide, silicon-silicon carbide composite material, cordierite forming raw material, cordierite, alumina titanate, sialon, mullite, silicon nitride, zirconium phosphate, zirconia, titania, alumina, silica, and LAS (lithium). Aluminum silicate) or a combination thereof can be mentioned as a suitable example. Here, the cordierite forming raw material means a raw material that becomes cordierite by firing, and a chemical composition in which silica is in a range of 42 to 56 mass%, alumina is in a range of 30 to 45 mass%, and magnesia is in a range of 12 to 16 mass%. It is a ceramic raw material blended so that. Specific examples include those containing a plurality of inorganic raw materials selected from talc, kaolin, calcined kaolin, alumina, aluminum hydroxide, and silica in a proportion such that the above chemical composition is obtained.

  Examples of the binder include methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. The binder content is preferably 1 to 10 parts by mass when the ceramic raw material is 100 parts by mass.

  As the pore former, any material that can be scattered and disappeared by the firing process may be used, and an inorganic substance such as coke, a polymer compound such as foamed resin, an organic substance such as starch, etc. may be used alone or in combination. Can do. The pore former content is preferably 1 to 10 parts by mass when the ceramic raw material is 100 parts by mass.

  The water content is preferably 20 to 35 parts by mass when the ceramic raw material is 100 parts by mass.

  As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type. The content of the surfactant is preferably 0.1 to 5 parts by mass when the ceramic raw material is 100 parts by mass.

  Next, the forming raw material is kneaded to form a clay. There is no restriction | limiting in particular as a method of kneading | mixing a shaping | molding raw material and forming a clay, For example, the method of using a kneader, a vacuum clay kneader, etc. can be mentioned.

  Next, the kneaded material is extruded to form a second honeycomb formed body. In extrusion molding, it is preferable to use a die having a desired overall shape, cell shape, partition wall thickness, cell density and the like. As the material of the die, a cemented carbide which does not easily wear is preferable. The second honeycomb formed body has a structure having partition walls for partitioning and forming a plurality of cells serving as fluid flow paths and an outer peripheral wall located at the outermost periphery.

  The partition wall thickness, cell density, outer peripheral wall thickness, and the like of the second honeycomb molded body can be appropriately determined in accordance with the structure of the second honeycomb catalyst body to be manufactured in consideration of shrinkage during drying and firing. .

  The obtained second honeycomb formed body is preferably dried before firing. The drying method is not particularly limited, and examples thereof include an electromagnetic heating method such as microwave heating drying and high-frequency dielectric heating drying, and an external heating method such as hot air drying and superheated steam drying. Among these, the entire molded body can be dried quickly and uniformly without cracks, and after drying a certain amount of moisture with an electromagnetic heating method, the remaining moisture is dried with an external heating method. It is preferable to make it. As drying conditions, it is preferable to remove moisture of 30 to 99% by mass with respect to the amount of moisture before drying by an electromagnetic heating method, and then to make the moisture to 3% by mass or less by an external heating method. As the electromagnetic heating method, dielectric heating drying is preferable, and as the external heating method, hot air drying is preferable.

  Next, when the length of the second honeycomb formed body in the central axis direction is not a desired length, it is preferable to cut both end faces (both end portions) to a desired length. The cutting method is not particularly limited, and examples thereof include a method using a circular saw cutting machine.

  Next, it is preferable to fabricate the second honeycomb fired body by firing the second honeycomb formed body. In order to remove the binder or the like before firing, it is preferable to perform temporary firing. Pre-baking is preferably performed at 400 to 500 ° C. for 0.5 to 20 hours in an air atmosphere. The method of temporary baking and baking is not particularly limited, and baking can be performed using an electric furnace, a gas furnace, or the like. The firing conditions are preferably 1400 to 1500 ° C. for 1 to 20 hours in an inert atmosphere such as nitrogen or argon.

  Next, it is preferable to form a second honeycomb catalyst body by supporting the catalyst on the obtained second honeycomb fired body. The method for supporting the catalyst is not particularly limited, and the catalyst can be supported by a known method. For example, first, a catalyst slurry containing a predetermined catalyst is prepared. Next, the catalyst slurry is coated on the partition wall surfaces of the second honeycomb fired body by a method such as a suction method. Thereafter, the second honeycomb catalyst body can be obtained by drying at room temperature or under heating conditions. The slurry concentration of the catalyst slurry is preferably 10 to 50% by mass.

  The catalyst supported on the second honeycomb fired body is preferably one that is preferable as a catalyst supported on the second honeycomb catalyst body constituting one embodiment of the exhaust gas purification apparatus of the present invention.

(4-3) Exhaust gas purification device;
By filling the honeycomb catalyst body and the second honeycomb catalyst body with the filler, and compressing the filler, the honeycomb catalyst body and the second honeycomb catalyst body are accommodated in the can body, whereby the exhaust gas as shown in FIG. It is preferable to obtain the purification device 500. It is preferable that the can body and the filler are preferable as the can body and the filler constituting one embodiment of the exhaust gas purification apparatus of the present invention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
(1) Honeycomb catalyst body:
As a ceramic raw material, silicon carbide (SiC) powder and metal silicon (Si) powder are mixed at a mass ratio of 80:20, and strontium carbonate as a sintering aid and hydroxypropylmethylcellulose as a binder are added thereto. Water was used as a forming raw material, the forming raw material was kneaded, and a columnar clay was prepared with a vacuum kneader. The binder content is 7 parts by mass with respect to 100 parts by mass of the ceramic raw material, the strontium carbonate content is 1 part by mass with respect to 100 parts by mass of the ceramic raw material, and the water content is with respect to 100 parts by mass of the ceramic raw material. It was 42 parts by mass. The average particle diameter of the silicon carbide powder was 20 μm, and the average particle diameter of the metal silicon powder was 6 μm. The average particle diameter of silicon carbide and metal silicon is a value measured by a laser diffraction method.

  The obtained columnar kneaded material was formed using an extrusion molding machine to obtain a honeycomb formed body. The obtained honeycomb formed body was a formed body provided with a portion corresponding to the honeycomb portion and a portion corresponding to the heat storage portion of the honeycomb base material constituting the honeycomb catalyst body to be manufactured. The obtained honeycomb formed body was dried by high-frequency dielectric heating and then dried at 120 ° C. for 2 hours using a hot air dryer, and both end surfaces were cut by a predetermined amount.

  The obtained honeycomb formed body was degreased at 550 ° C. for 3 hours using an air furnace equipped with a deodorizing apparatus in an air atmosphere, and then fired at about 1450 ° C. for 2 hours in an Ar inert atmosphere. Oxygenation treatment was performed at 1 ° C. for 1 hour. A dense honeycomb fired body in which SiC crystal particles were bonded with Si was obtained.

  A catalyst was supported on the obtained honeycomb fired body to obtain a honeycomb catalyst body. The method for supporting the catalyst on the honeycomb fired body was as follows. First, a catalyst slurry containing a catalyst was prepared. As the catalyst, a three-way catalyst in which 1 g of noble metal was supported on 150 g of support was used. As the noble metal, Pt and Rh were used, and the mass ratio was set to “Pt: Rh = 5: 1”. As the carrier, a mixed material of alumina and ceria mixed with “alumina: ceria = 5: 1 (mass ratio)” was used. Next, the catalyst slurry was coated on the partition wall surfaces of the honeycomb fired body by a suction method. Then, the honeycomb catalyst body was obtained by drying at room temperature. The amount of catalyst was 150 g / liter (150 g per liter of honeycomb catalyst body).

The porosity of the “honeycomb partition walls” and the heat storage portion of the obtained honeycomb catalyst body was 3%. The porosity is a value measured with a mercury porosimeter. The honeycomb catalyst body (honeycomb portion) had a partition wall thickness of 0.2 mm and a cell density of 93 cells / cm ² . The shape of the bottom surface of the honeycomb catalyst body was a circle having a diameter of 100 mm, and the length of the honeycomb catalyst body in the cell extending direction was 80 mm. In addition, the value of the ratio of the thickness t (see FIG. 2) of the heat storage portion 4 of the honeycomb base material 5 to the diameter D (see FIG. 2) of the honeycomb base material 5 in a cross section orthogonal to the cell 2 extending direction (see FIG. 2). t / D) was 0.04. Further, the heat capacity of the honeycomb substrate constituting the honeycomb catalyst body was 2000 J / (m ³ · K), and the thermal conductivity was 40 W / (m · K). The heat capacity of the honeycomb portion and the heat capacity of the heat storage portion were the same value, and the heat conductivity of the honeycomb portion and the heat conductivity of the heat storage portion were the same value.

(2) Second honeycomb catalyst body:
As a ceramic raw material, a cordierite forming raw material was used. A pore former, a binder, a surfactant and water were added to the cordierite forming raw material to obtain a molding raw material. As the cordierite forming raw material, talc, kaolin, calcined kaolin, alumina, aluminum hydroxide, and silica, the chemical composition of which is SiO ₂ ; 42 to 56% by mass, Al ₂ O ₃ ; 30 to 45% by mass, And MgO; those prepared at a predetermined ratio so as to be 12 to 16% by mass. Graphite was used as the pore former, and 5 parts by mass was added to 100 parts by mass of the ceramic raw material. As a binder, methylcellulose was used and 10 mass parts was added with respect to 100 mass parts of ceramic raw materials. As the surfactant, ethylene glycol was used, and 0.5 part by mass was added to 100 parts by mass of the ceramic raw material. 30 parts by mass of water was added to 100 parts by mass of the ceramic raw material.

  The forming raw material was kneaded, and a columnar clay was prepared with a vacuum kneader. The obtained columnar kneaded material was formed using an extrusion molding machine to obtain a honeycomb formed body. The obtained honeycomb formed body was dried by high-frequency dielectric heating and then dried at 120 ° C. for 2 hours using a hot air dryer, and both end surfaces were cut by a predetermined amount.

  The obtained honeycomb formed body was degreased at 550 ° C. for 3 hours in an air atmosphere using an air furnace equipped with a deodorizing device, and then fired at about 1420 ° C. for 5 hours to obtain a honeycomb fired body.

  A catalyst was supported on the obtained honeycomb fired body to obtain a honeycomb catalyst body. The method for supporting the catalyst on the honeycomb fired body is as follows. First, a catalyst slurry containing a catalyst was prepared. As the catalyst, a three-way catalyst in which 1 g of noble metal was supported on 150 g of support was used. As the noble metal, Pt and Rh were used, and the mass ratio was set to “Pt: Rh = 5: 1”. As the carrier, a mixed material of alumina and ceria mixed with “alumina: ceria = 5: 1 (mass ratio)” was used. Next, the catalyst slurry was coated on the partition wall surfaces of the honeycomb fired body by a suction method. Then, the honeycomb catalyst body was obtained by drying at room temperature. The amount of catalyst was 150 g / liter (150 g per liter of honeycomb catalyst body).

The porosity of the partition walls of the obtained honeycomb catalyst body was 35%. The porosity is a value measured with a mercury porosimeter. The honeycomb catalyst body had a partition wall thickness of 0.05 mm and a cell density of 180 cells / cm ² . The shape of the bottom surface of the honeycomb catalyst body was a circle having a diameter of 100 mm, and the length of the honeycomb catalyst body in the cell extending direction was 80 mm.

(3) Exhaust gas purification device:
A filler is wound around the obtained honeycomb catalyst body and the second honeycomb catalyst body, and the honeycomb catalyst body and the second honeycomb catalyst body are accommodated in the can body in a state where the filler is compressed, as shown in FIG. An exhaust gas purification apparatus 500 was obtained. A heat resistant inorganic insulating mat was used as the filler. The material of the can was stainless steel. Moreover, the shape of the can body was made into the cylindrical shape by which the both ends were narrowed like the can body 33 shown by FIG. The diameter of the inlet opening and the outlet opening of the can body was 55 mm. Further, the diameter of the cross section perpendicular to the central axis of the portion of the can where the honeycomb catalyst body and the second honeycomb catalyst body are inserted was set to 108 mm.

  About the obtained exhaust gas purification apparatus, "pressure loss (pressure loss)", "purification performance", and "durability" were evaluated by the following methods. The results are shown in Table 1. In Table 1, the column “Comprehensive Judgment” of “Evaluation Result” is “A” when all evaluations of “pressure loss (pressure loss)”, “purification performance” and “durability” are “A”, If there is even one “B”, it is set to “B”. “A” is acceptable and “B” is unacceptable.

(Pressure loss)
Using a pressure loss measuring device 40 as shown in FIG. 9, the pressure loss (pressure loss) when a gas is passed through the measurement sample 44 is measured. The pressure loss measuring device 40 uses the exhaust gas purifying device as a measurement sample 44, and “measures the difference (differential pressure) between the pressure immediately before the measurement sample 44 flows in and the pressure immediately after the measurement sample 44 flows out”. , And a blower 43 “attached to the outflow side of the measurement sample 44 to allow the gas G1 to flow through the measurement sample 44”, and each connected by a pipe. And the pressure loss (pressure loss) when gas is flowed through the measurement sample 44 is measured using the pressure loss measuring device 40. In the pressure loss measuring device 40 shown in FIG. 9, valves, measuring devices (except for the differential pressure gauge), bypasses, and the like are omitted.

Specifically, first, an inflow side pipe and an outflow side pipe are attached to the inflow side end and the outflow side end of the measurement sample 24, and the gas G1 is measured by the blower 43 at room temperature. Shed. Then, the pressure loss (pressure loss) when the gas G1 is caused to flow through the measurement sample 44 is measured by a differential pressure gauge while the gas G1 is allowed to flow. Here, the flow rate of the gas G1 is 10 Nm ³ / min. FIG. 9 is a schematic diagram showing a pressure loss measuring apparatus. The case where the pressure loss is 6 kPa or less is “A”, and the case where the pressure loss exceeds 6 kPa is “B”. “A” is acceptable and “B” is unacceptable.

(Purification performance)
The exhaust gas purification device is attached to the exhaust system of a vehicle equipped with a 2 liter gasoline engine, the US regulated operation mode LA-4 is operated on the chassis dynamo, and carbonized using an emission measurement method that complies with the US exhaust gas regulations. Measure hydrogen emissions. The case where the hydrocarbon discharge amount is 0.02 g / km or less is “A”, and the case where the hydrocarbon discharge amount exceeds 0.02 g / km is “B”. “A” is acceptable and “B” is unacceptable.

(durability)
The combustion gas of the burner test apparatus is flowed to the exhaust gas purification apparatus by the following method, and the presence or absence of subsequent cracks is observed. As a method of flowing the combustion gas to the exhaust gas purifying apparatus (flowing method), the temperature of the combustion gas is changed in a cycle of “900 ° C. for 10 minutes and then 200 ° C. for 10 minutes” (one cycle). A method of performing a cycle is used. As the burner test apparatus, an apparatus capable of changing the gas temperature transiently by controlling the ratio of the combustion gas of the gas burner using propane as fuel and the diluted air was used. The case where there is no crack is “A”, and the case where a crack is generated is “B”. “A” is acceptable and “B” is unacceptable.

(Examples 2-16, Comparative Examples 1-14)
Exhaust gas purification devices were produced in the same manner as in Example 1 except that the production conditions were changed as shown in Table 1. In the same manner as in Example 1, “pressure loss (pressure loss)”, “purification performance”, and “durability” were evaluated by the above method. The results are shown in Table 1.

From Table 1, the honeycomb substrate has a thermal conductivity of 20 W / mK or more and a heat capacity of 1800 J / m ³ K or more, and the thickness of the heat storage part is “in a cross section perpendicular to the cell extending direction” of the honeycomb substrate. It turns out that it is excellent in a pressure loss, purification performance, and durability as it is 0.03-0.5 times the diameter.

  The honeycomb catalyst body of the present invention can be suitably used as a catalyst body for purifying exhaust gas discharged from an internal combustion engine in various fields such as chemistry, electric power, and steel. And the exhaust gas purification apparatus of this invention can be utilized suitably as an exhaust gas purification apparatus carrying the said catalyst body.

DESCRIPTION OF SYMBOLS 1,2: Partition, 2,22: Cell, 3: Honeycomb part, 3a: Center part, 3b: Outer part, 3bα, 3bβ: Outer layer, 4: Heat storage part, 5: Honeycomb base material, 11: One end face , 12: the other end surface, 21: partition walls, 22: cells, 23: outer peripheral wall, 24: second honeycomb catalyst body, 25: honeycomb substrate, 31: inlet opening, 32: outlet opening, 33: can body 34: Fastener, 35: Filler, 40: Pressure loss measuring device, 42: Differential pressure gauge, 43: Blower, 44: Measurement sample, 100, 200, 300: Honeycomb catalyst body, 500, 600: Exhaust gas purification device, G, G1: Gas, T1, T2: Time.

Claims (7)

Cylindrical honeycomb having a honeycomb part having partition walls for partitioning and forming a plurality of cells extending from one end face to the other end face as a fluid flow path, and a heat storage part arranged to surround the outer periphery of the honeycomb part A substrate;
A catalyst supported on the partition walls of the honeycomb part,
The material properties of the honeycomb substrate have a thermal conductivity of 20 W / mK or more and a heat capacity of 1800 J / m ³ K or more,
The thickness of the heat storage part is 0.03 to 0.5 times the diameter of the honeycomb substrate in a cross section perpendicular to the cell extending direction,
The honeycomb part has a partition wall thickness of 0.05 to 0.3 mm, a cell density of 30 to ²⁰⁰ cells / cm ² ,
The amount of supported catalyst in the partition walls of the honeycomb unit 60～400G / liter der is,
The honeycomb catalyst body in which the heat storage unit and the honeycomb unit is Ru are joined by being sintered. The honeycomb catalyst body according to claim 1, wherein a material of the heat storage unit is mainly Si-SiC. In the cross section perpendicular to the cell extending direction, the honeycomb part is composed of a central part and an outer peripheral part surrounding the central part,
The honeycomb catalyst body according to claim 1 or 2 , wherein a partition wall thickness in the outer peripheral portion is larger than a partition wall thickness in the central portion. The honeycomb catalyst body according to claim 3 , wherein the partition wall thickness of the outer peripheral portion is 1.05 to 2.00 times the partition wall thickness of the central portion. The honeycomb catalyst body according to any one of claims 1 to 4 , wherein a thermal conductivity and a heat capacity of the heat storage part of the honeycomb base material are larger than a thermal conductivity and a heat capacity of the honeycomb part of the honeycomb base material. A honeycomb catalyst body according to any one of claims 1 to 5 ,
A partition for partitioning a plurality of cells extending from one end face to the other end face to be a fluid flow path, a cylindrical honeycomb substrate having an outer peripheral wall disposed on the outermost periphery, and a catalyst supported on the partition A second honeycomb catalyst body having a partition wall thickness of 0.05 to 0.2 mm and a cell density of 60 to 180 cells / cm ² ;
The honeycomb catalyst body and the second honeycomb catalyst body are housed inside, and includes a cylindrical can body having an inlet opening at one end and an outlet opening at the other end,
The second honeycomb catalyst body is disposed on the inlet opening side of the can body, the honeycomb catalyst body is disposed on the outlet opening side of the can body, and the second honeycomb catalyst body, the honeycomb catalyst body, However, the exhaust gas purification apparatus arranged in series so that the gas flowing in from the inlet opening of the can passes through the cells of the honeycomb catalyst body after passing through the cells of the second honeycomb catalyst body. The diameter of the honeycomb section of the honeycomb catalyst body in a cross section perpendicular to the cell extending direction is 0.9 times or more of the diameter of the second honeycomb catalyst body in a cross section orthogonal to the cell extending direction. 6. The exhaust gas purifying apparatus according to 6 .

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