Catalyst carrier and induction heating catalytic system

Abstract

A catalyst carrier for induction heating, comprising: a honeycomb structure, the honeycomb structure having a columnar honeycomb structure portion having an outer peripheral wall and partition walls, the partition walls being arranged on the inner side of the outer peripheral wall and partitioning into a plurality of compartments, the plurality of compartments extending from the end face on the inlet side in the direction of airflow to the end face on the outlet side to form a flow path; a catalyst, the catalyst being carried inside the partition walls; and a magnetic body, the magnetic body being arranged in the honeycomb structure, the catalyst carrier for induction heating being characterized in that a region A on which no catalyst is carried is provided on at least the end face side on the inlet side in the direction of airflow of the catalyst carrier, and the magnetic body is arranged at least in the region A in the direction of airflow.

Description

Technical Field

[0001] The invention relates to a catalyst carrier and an induction heating catalytic system. Background Art

[0002] Usually, as a result of incomplete combustion, automobile exhaust sometimes contains harmful components such as carbon monoxide, hydrocarbons, and nitrogen oxides. These harmful components are discharged in large quantities during the period when the catalyst temperature is low and the catalytic activity is insufficient, such as just after the engine is started. Therefore, it is possible that the harmful components in the exhaust gas are discharged without being purified by the catalyst before the catalyst activation temperature is reached. In order to meet this demand, it is necessary to minimize the emissions that are discharged without being purified by the catalyst before the catalyst activation temperature is reached. For example, there is a known countermeasure that uses a heating technology for the catalyst carrier.

[0003] As the above-mentioned technology, there is known an induction heating catalytic system, in which a catalyst carrier of a magnetic body is arranged on the wall surface or in the compartment of a honeycomb structure in the exhaust gas flow path of a car, the outer periphery of the catalyst carrier is surrounded by a coil, and the magnetic body is heated by induction heating to make the catalyst carrier generate heat, thereby purifying the exhaust gas.

[0004] Patent Document 1 describes a catalyst carrier having a structure in which metal particles or metal flakes are arranged throughout a plurality of cells of a ceramic substrate, and the metal particles or metal flakes are heated by induction heating.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-188272 Summary of the invention

[0008] The purpose of induction heating is to increase the catalyst temperature when the gas temperature near the gas flow direction inlet of the catalyst carrier is still low, so as to improve the purification rate. However, near the gas flow direction inlet of the catalyst carrier, the gas temperature and the carrier and catalyst temperature are not sufficiently increased by induction heating, and these temperatures gradually increase as they move toward the outlet. At this time, in the technology described in Patent Document 1, even if the metal particles or metal flakes arranged in the entire compartment are heated by induction heating, the temperature near the gas flow direction inlet of the catalyst carrier is not sufficiently increased, so the catalyst arranged in this area is difficult to activate.

[0009] Thus, the effective utilization of the catalyst provided near the inlet in the gas flow direction is insufficient. In particular, when a noble metal such as Pt is used as the catalyst, the disadvantage of the manufacturing cost is great.

[0010] The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to provide a catalyst carrier and an induction heating catalyst system that can effectively utilize a catalyst during induction heating.

[0011] The above-mentioned problems are solved by the following present invention, and the present invention is defined as follows.

[0012] (1) A catalyst carrier for induction heating, comprising:

[0013] A honeycomb structure having a columnar honeycomb structure portion having an outer peripheral wall and partition walls, wherein the partition walls are arranged inside the outer peripheral wall and partition a plurality of cells, and the plurality of cells extend from an end face on an inlet side to an end face on an outlet side in an air flow direction to form a flow path;

[0014] a catalyst supported on the interior of the partition wall; and

[0015] A magnetic body, which is disposed in the honeycomb structure.

[0016] The catalyst carrier for induction heating is characterized in that

[0017] The catalyst carrier has a region A on which the catalyst is not supported on at least the end surface side on the inlet side in the gas flow direction,

[0018] The magnetic body is disposed at least in the region A in the air flow direction.

[0019] (2) An induction heating catalytic system, characterized by having:

[0020] (1) the catalyst carrier for induction heating; and

[0021] The coil is arranged on the outer periphery of the catalyst carrier.

[0022] Effects of the Invention

[0023] According to the present invention, a catalyst carrier and an induction heating catalyst system capable of effectively utilizing a catalyst during induction heating can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic cross-sectional view parallel to the extending direction of the cells of the catalyst carrier in the embodiment of the present invention.

[0025] Figure 2 yes Figure 1 Schematic diagram of the L1-L1 section of the catalyst carrier in FIG.

[0026] Figure 3 It is a schematic cross-sectional view parallel to the extending direction of the cells of the catalyst carrier in the embodiment of the present invention.

[0027] Figure 4 It is a schematic cross-sectional view parallel to the extending direction of the cells of the catalyst carrier in the embodiment of the present invention.

[0028] Figure 5 It is a schematic cross-sectional view parallel to the extending direction of the cells of the catalyst carrier in the embodiment of the present invention.

[0029] Figure 6 yes Figure 5 Schematic diagram of the L2-L2 section of the catalyst carrier.

[0030] Figure 7 It is a schematic cross-sectional view parallel to the extending direction of the cells of the catalyst carrier in the embodiment of the present invention.

[0031] Figure 8 4 is a schematic cross-sectional view parallel to the airflow direction of the induction heating catalytic system in an embodiment of the present invention.

[0032] Fig. 9 is a schematic cross-sectional view parallel to the airflow direction of the induction heating catalytic system in the embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, the implementation modes of the catalyst carrier and the induction heating catalytic system of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to this explanation and various changes, corrections and improvements may be made based on the knowledge of those skilled in the art without departing from the scope of the present invention.

[0034] <Catalyst carrier>

[0035] Figure 1 It is a schematic cross-sectional view parallel to the extending direction of the cells 13 of the catalyst carrier 10 in the embodiment of the present invention. Figure 2 yes Figure 1 Schematic diagram of the L1-L1 cross section of the catalyst carrier 10 in FIG.

[0036] The catalyst carrier 10 has a honeycomb structure 11, a catalyst 12, and a magnetic body 17. The honeycomb structure 11 of the catalyst carrier 10 has a columnar honeycomb structure portion 16 having an outer peripheral wall 14 and a partition wall 15, the partition wall 15 is arranged on the inner side of the outer peripheral wall 14, and is partitioned to form a plurality of compartments 13, and the plurality of compartments 13 extend from the end face on the inlet side to the end face on the outlet side in the air flow direction to form a flow path.

[0037] The material of the partition wall 15 and the outer peripheral wall 14 of the columnar honeycomb structure part 16 is not particularly limited, and is usually formed of a ceramic material. For example, cordierite, silicon carbide, aluminum titanate, silicon nitride, mullite, alumina, silicon-silicon carbide composite materials, silicon carbide-cordierite composite materials, and especially sintered bodies with silicon-silicon carbide composite materials or silicon carbide as the main component can be cited. In this specification, "silicon carbide system" means that the columnar honeycomb structure part 16 contains more than 50% by mass of silicon carbide of the entire columnar honeycomb structure part 16. The columnar honeycomb structure part 16 is mainly composed of silicon-silicon carbide composite materials, which means that the columnar honeycomb structure part 16 contains more than 90% by mass of silicon-silicon carbide composite materials (total mass) of the entire columnar honeycomb structure part 16. Here, the silicon-silicon carbide composite material contains silicon carbide particles as aggregates and silicon as a bonding material for bonding the silicon carbide particles. Preferably, a plurality of silicon carbide particles are bonded by silicon in a manner that forms pores between the silicon carbide particles. In addition, the columnar honeycomb structure part 16 containing silicon carbide as a main component means that the columnar honeycomb structure part 16 contains 90 mass % or more of silicon carbide (total mass) of the entire columnar honeycomb structure part 16 .

[0038] Preferably, the columnar honeycomb structure part 16 is formed of at least one ceramic material selected from the group consisting of cordierite, silicon carbide, aluminum titanate, silicon nitride, mullite, and alumina.

[0039] The cell shape of the columnar honeycomb structure part 16 is not particularly limited, and in the cross section of the columnar honeycomb structure part 16 orthogonal to the central axis, it is preferably a polygon such as a triangle, a quadrilateral, a pentagon, a hexagon, an octagon, a circle or an ellipse, and may be an irregular shape. Preferably, it is a polygon.

[0040] The thickness of the partition wall 15 of the columnar honeycomb structure part 16 is preferably 0.05 to 0.50 mm, and more preferably 0.10 to 0.45 mm in terms of ease of manufacturing. For example, if the thickness of the partition wall 15 is 0.05 mm or more, the strength of the columnar honeycomb structure part 16 is further improved; if the thickness of the partition wall 15 is 0.50 mm or less, the pressure loss can be reduced. It should be noted that the thickness of the partition wall 15 is an average value measured by a method of microscopic observation of a cross section in the central axis direction.

[0041] The porosity of the partition walls 15 is preferably 20 to 70%. In terms of ease of production, the porosity of the partition walls 15 is preferably 20% or more, and when the porosity is 70% or less, the strength of the honeycomb structure 11 can be maintained.

[0042] The average pore diameter of the partition wall 15 is preferably 2 to 30 μm, more preferably 5 to 25 μm. If the average pore diameter of the partition wall 15 is 2 μm or more, the manufacturing is easy; if the average pore diameter of the partition wall 15 is 30 μm or less, the strength of the honeycomb structure 11 can be maintained. It should be noted that in this specification, "average pore diameter" and "porosity" refer to the average pore diameter and porosity measured by mercury intrusion.

[0043] The cell density of the columnar honeycomb structure part 16 is not particularly limited, but is preferably 5 to 150 cells / cm 2 The range is more preferably 5 to 100 cells / cm 2 The range is more preferably 31 to 80 cells / cm 2 range.

[0044] The outer shape of the columnar honeycomb structure part 16 is not particularly limited, and may be a columnar shape with a circular end face (cylindrical shape), a columnar shape with an oval end face, a columnar shape with a polygonal end face (quadrilateral, pentagon, hexagon, heptagon, octagon, etc.).

[0045] The columnar honeycomb structure part 16 is made as follows, that is, the blank containing ceramic raw material is formed into a honeycomb with a partition forming a plurality of compartments of the next door 15, forming a honeycomb formed body, after the honeycomb formed body is dried, it is fired, and thus a honeycomb structure is made, wherein a plurality of compartments extend from one end face to another end face to form a fluid flow path. Then, in the case where the obtained honeycomb structure is used for the honeycomb structure of the present embodiment, the peripheral wall can be integrally extruded with the honeycomb structure and directly used as the peripheral wall, or after forming or firing, the periphery of the honeycomb structure is ground, set to a specified shape, and the honeycomb structure ground at the periphery is coated with a coating material to form a peripheral coating. It should be noted that in the present embodiment, for example, the outermost periphery of the honeycomb structure can not be ground, but a honeycomb structure with a periphery is used, and the outer peripheral surface of the honeycomb structure with a periphery (that is, the outer side of the periphery of the honeycomb structure) is further coated with the above-mentioned coating material to form a peripheral coating. That is, in the former case, on the outer peripheral surface of the honeycomb structure, only the outer peripheral coating formed by the coating material becomes: the outer peripheral wall located at the outermost periphery. On the other hand, in the latter case, on the outer peripheral surface of the honeycomb structure, there is formed: a two-layer structure outer peripheral wall, which is further laminated with the outer peripheral coating formed by the coating material and is located at the outermost periphery. The outer peripheral wall can also be extruded integrally with the honeycomb structure part, directly fired, and used as the outer peripheral wall without peripheral processing.

[0046] The honeycomb structure 11 is not limited to an integral honeycomb structure having partition walls integrally formed therein, and may be, for example, a honeycomb structure (bonded honeycomb structure) having the following structure: a plurality of columnar honeycomb units are combined with the aid of a bonding material layer, wherein the columnar honeycomb units have ceramic partition walls and a plurality of compartments serving as fluid flow paths are formed by dividing the units into sections through the partition walls.

[0047] The catalyst 12 is supported inside the partition wall 15. The catalyst 12 may be selected from an oxidation catalyst, a three-way catalyst, an NO x Storage reduction catalyst, NO x At least one of the group consisting of a reduction catalyst (SCR catalyst), a hydrocarbon adsorption catalyst, a hydrocarbon and carbon monoxide oxidation catalyst, and an ammonia slip (oxidation) catalyst is selected.

[0048] The catalyst 12 can be appropriately selected according to the desired exhaust gas purification purpose. The method for supporting the catalyst 12 is not particularly limited, and can be carried out according to a conventional method for supporting a catalyst on a honeycomb structure.

[0049] The catalyst carrier 10 has a region A where the catalyst 12 is not carried at least on the end face side of the inlet side in the gas flow direction. The end face side of the inlet side in the gas flow direction of the catalyst carrier 10 is a low temperature region compared to the end face side of the outlet side, and it is difficult for the catalyst 12 to reach a sufficient activation temperature. Therefore, by setting the low temperature region as the region A where the catalyst 12 is not carried, the catalyst 12 can be effectively used without waste during induction heating, and the manufacturing cost is improved. In particular, when a noble metal such as Pt is used as the catalyst 12, the manufacturing cost advantage is relatively large.

[0050] There is a prior art in which an electric heating carrier (EHC) is arranged in the front half of the catalyst carrier in the direction of gas flow. However, in this technology, the catalyst carrier is heated only by the gas heated by the EHC arranged in the front half in the direction of gas flow. Therefore, there is no path for transferring electric heating energy by heat conduction between individuals, and the temperature rise near the gas flow direction inlet of the catalyst carrier is insufficient. In particular, it is difficult to effectively use the catalyst. In response to this problem, the catalyst carrier 10 of the present invention has a region A where the catalyst 12 is not carried on at least the end face side of the gas flow direction inlet side. Therefore, the catalyst 12 is not carried in the region where the temperature rise is insufficient near the gas flow direction inlet of the catalyst carrier 10, and the catalyst 12 can be effectively used without waste during induction heating.

[0051] In addition, the catalyst carrier 10 is a 3 In the case of a carrier of a type that purifies exhaust gas as a reducing agent, the catalyst carrier 10 has an SCR catalyst. The SCR catalyst has a NH 3Therefore, in the low temperature area near the gas flow inlet of the catalyst carrier 10, NH 3 Adsorption, NH 3 In contrast, the catalyst carrier 10 according to the embodiment of the present invention has a region A without SCR catalyst at least on the end surface side of the inlet side in the airflow direction, which can effectively suppress the NH 3 adsorption, thereby being able to suppress a decrease in exhaust gas purification performance.

[0052] The region A is preferably arranged from the end face of the catalyst carrier 10 on the inlet side in the gas flow direction to a position of 10% to 70% of the length of the catalyst carrier 10. In the position of 10% to 70% of the length of the catalyst carrier 10 from the end face of the catalyst carrier 10 on the inlet side in the gas flow direction, the catalyst 12 may not fully reach the activation temperature. By arranging the region A without carrying the catalyst 12 within this position, the catalyst 12 can be effectively used without waste. The region A is more preferably arranged from the end face of the catalyst carrier 10 on the inlet side in the gas flow direction to a position of 10% to 50% of the length of the catalyst carrier 10, and is further preferably arranged to a position of 10% to 30%.

[0053] A magnetic body 17 is provided in the honeycomb structure 11. The magnetic body 17 is arranged at least in the above-mentioned region A in the airflow direction of the catalyst carrier 10. By arranging the magnetic body 17 in the region A, the vicinity of the airflow direction inlet of the catalyst carrier 10 can be heated. Therefore, the exhaust gas purification performance of the catalyst carrier 10 can be improved.

[0054] like Figure 1 As shown, the magnetic body 17 may be filled in the cells 13 of the honeycomb structure 11. In this case, in the catalyst carrier 10, the cells filled with the magnetic body 17 and the cells carrying the catalyst 12 are of different structures.

[0055] Regarding the cells filled with magnetic bodies 17, for the cells adjacent in the vertical and horizontal directions, they can be arranged every other cell to form a houndstooth pattern, or they can be arranged every other two cells, three cells, or multiple cells, or they can be arranged continuously. There is no limit to the number or arrangement of the cells filled with magnetic bodies 17 (hereinafter also referred to as magnetic body filled cells), and they can be appropriately designed as needed. It can be: at the position close to the outer peripheral wall 14 of the honeycomb structure 11, the interval of the magnetic body filled cells is enlarged and the density of the magnetic body filled cells is reduced, and at the central part of the honeycomb structure 11, the interval of the magnetic body filled cells is reduced. By setting the interval of the magnetic body filled cells in this way, the influence of the magnetic field of the coil is not blocked by the magnetic body near the periphery, but reaches the central part of the honeycomb structure 11, so it is preferred. In addition, the length of the magnetic body filled part of the magnetic body filled cell does not need to be constant. If it is shorter at the position close to the outer peripheral wall 14 and longer in the central part, the influence of the magnetic field of the coil fully reaches the interior of the honeycomb structure, so it is preferred. It should be noted that when the length of the magnetic body filling portion varies depending on the compartment, the region A is defined by the average magnetic body filling length. From the viewpoint of improving the heating effect, it is better to increase the number of compartments filled with the magnetic body 17, but from the viewpoint of reducing the pressure loss, it is better to minimize the number of compartments. Figure 2 As shown, when the honeycomb structure 11 has compartments with smaller cross-sectional areas and compartments with larger cross-sectional areas, from the viewpoint of maintaining the heating performance of induction heating and reducing pressure loss, it is preferred that the magnetic body 17 is filled in the compartments with smaller cross-sectional areas and the magnetic body 17 is not arranged in the compartments with larger cross-sectional areas.

[0056] The magnetic body 17 is a magnetic material that is magnetized by a magnetic field, and the state of magnetization also changes with the strength of the magnetic field. The curve representing this change is the "magnetization curve". Regarding the magnetization curve, sometimes the horizontal axis is scaled by the magnetic field H, and the vertical axis is scaled by the magnetic flux density B (B-H curve). The state in which the magnetic material is not applied with a magnetic field at all is called the demagnetized state, represented by the origin O. When a magnetic field is applied, a curve is drawn starting from the origin O in which the magnetic flux density increases and saturates. This curve is the "initial magnetization curve". The slope of the straight line connecting the points on the initial magnetization curve and the origin is the "magnetic permeability". The magnetic permeability means the penetration of the magnetic field, and is used as a standard for the ease of magnetization of the magnetic material. The magnetic permeability at the point with a smaller magnetic field near the origin is the "initial permeability", and the maximum magnetic permeability on the initial magnetization curve is the "maximum permeability".

[0057] The magnetic body 17 preferably has a maximum magnetic permeability of 500 or more. According to this configuration, when the honeycomb structure 11 is dielectrically heated, the temperature can be raised to the temperature (about 300° C.) at which the catalyst 12 is activated in a short time.

[0058] The magnetic body 17 preferably has a Curie point of 450°C or higher. The Curie point of the magnetic body 17 refers to the temperature at which the ferromagnetic property is lost. In addition, the magnetic body 17 preferably has a resistance value of 20 μΩcm or higher at 25°C. In addition, the magnetic body 17 preferably has a coercive force of 40 A / m or higher. According to this configuration, the temperature can be raised to the activation temperature of the catalyst 12 (about 300°C) in a short time.

[0059] Examples of the types of the magnetic body 17 include a balance of Co-20 mass % Fe, a balance of Co-25 mass % Ni-4 mass % Fe, a balance of Fe-15 to 35 mass % Co, a balance of Fe-17 mass % Co-2 mass % Cr-1 mass % Mo, a balance of Fe-49 mass % Co-2 mass % V, a balance of Fe-18 mass % Co-10 mass % Cr-2 mass % Mo-1 mass % Al, a balance of Fe-27 mass % Co-1 mass % Nb, a balance of Fe-20 mass % Co-1 mass % Cr-2 mass % V, a balance of Fe-35 mass % Co-1 mass % Cr, pure cobalt, pure iron, electromagnetic soft iron, a balance of Fe-0.1 to 0.5 mass % Mn, a balance of Fe-3 mass % Si, Balance Fe-6.5 mass% Si, balance Fe-18 mass% Cr, balance Fe-16 mass% Cr-8 mass% Al, balance Ni-13 mass% Fe-5.3 mass% Mo, balance Fe-45 mass% Ni, balance Fe-10 mass% Si-5 mass% Al, balance Fe-36 mass% Ni, balance Fe-45 mass% Ni, balance Fe-35 mass% Cr, balance Fe-13 mass% Cr-2 mass% Si, balance Fe-20 mass% Cr-2 mass% Si-2 mass% Mo, balance Fe-20 mass% Co-1 mass% V, balance Fe-13 mass% Cr-2 mass% Si, balance Fe-17 mass% Co-2 mass% Cr-1 mass% Mo, etc.

[0060] The magnetic body 17 can be, for example, a plate-shaped, rod-shaped, ring-shaped, filament-shaped or fibrous magnetic body. It should be noted that in the present invention, regarding the rod-shaped magnetic body and the filament-shaped magnetic body, the shape of the cross section perpendicular to the length direction having a diameter of 0.8 mm or more is set as a rod-shaped, and the shape of the cross section having a diameter of less than 0.8 mm is set as a filament, and a distinction is made. When the magnetic body 17 is filled in the compartment 13, magnetic bodies of these shapes can be appropriately used according to the shape of the compartment 13. A plurality of magnetic bodies 17 can be filled in one compartment, or only one can be filled in one compartment.

[0061] In addition, when the magnetic body 17 is annular, a groove is provided on the end face of the catalyst carrier 10 on the inlet side of the gas flow direction, and an annular magnetic body is embedded in the groove. According to this structure, through electromagnetic induction heating, the current easily flows in a manner surrounding the magnetic body 17 arranged in an annular shape, so that eddy currents are easily generated. Therefore, even at a relatively low frequency of less than tens of kHz, electromagnetic induction heating can be fully performed. In addition, since eddy currents are easily generated by the magnetic body 17 arranged in an annular shape, there is no restriction on the Curie point of the material such as a ferromagnetic body, and the heating speed of the catalyst carrier 10 is good.

[0062] The number of annular magnetic bodies 17 provided on the end surface of the catalyst carrier 10 on the inlet side in the gas flow direction is not particularly limited. For example, a plurality of annular magnetic bodies may be provided on the end surface of the catalyst carrier 10 at intervals.

[0063] The compartment 13 may be filled with a composition obtained by compounding a magnetic body and a bonding material or a bonding material. As the bonding material, for example, a material with metal or glass as the main component may be cited. As the bonding material, a material with silicon dioxide or aluminum oxide as the main component may be cited. In addition to the bonding material or the bonding material, it may further contain organic or inorganic substances.

[0064] The magnetic body 17 filled in the compartment 13 can be as follows Figure 1 As shown, the catalyst carrier 10 is filled from the end surface on the inlet side of the gas flow direction to the end surface on the outlet side. Figure 3 or Figure 4 As shown, the magnetic body 17 is filled from the end surface of the catalyst carrier 10 on the inlet side of the gas flow direction to the middle of the compartment 13. At this time, the coil 19 arranged in a surrounding manner outside the catalyst carrier 10 is set at a position corresponding to the area filled with the magnetic body 17. When the magnetic body 17 is filled from the end surface of the catalyst carrier 10 on the inlet side of the gas flow direction to the middle of the compartment 13, it is preferably as follows Figure 3 or Figure 4 As shown, there is a portion α where the region carrying the catalyst 12 and the region filled with the magnetic body 17 overlap in the airflow direction of the catalyst carrier 20, 30. According to this structure, the heat from the magnetic body generated by induction heating is well transferred to the catalyst 12, so the catalyst 12 can be heated more effectively. If the portion α where the region carrying the catalyst 12 and the region filled with the magnetic body overlap is larger, the catalyst 12 can be heated well accordingly. From this point of view, the length of the overlapping portion α is preferably more than 10% of the region carrying the catalyst 12 in the airflow direction of the catalyst carrier 10 of the compartment 13, more preferably more than 20%, and most preferably 100%.

[0065] In addition, if Figure 5and Figure 5 The schematic diagram of the L2-L2 cross section of the catalyst carrier 40 is Figure 6 As shown, the magnetic body can be contained in the surface layer 18 provided on the partition wall 15 of the honeycomb structure 41. The surface layer 18 includes a fixed adhesive material in which the powder of the magnetic body is dispersed. As the fixed adhesive material, glass, crystallized glass, ceramic containing silicate, boric acid or borosilicate; or glass, crystallized glass, ceramic containing other oxides, etc. can be used. As the glass, it is preferred to use a high melting point glass with a melting point of 900 to 1100°C. By using high melting point glass, the heat resistance of the surface layer 18 is improved.

[0066] The thickness of the surface layer 18 is preferably 10 to 100 μm. If the thickness of the surface layer 18 is 10 μm or more, more magnetic material can be contained, and the heating efficiency of induction heating is improved. If the thickness of the surface layer 18 is 100 μm or less, the pressure loss can be reduced.

[0067] The honeycomb structure 41 can be a structure in which the two end faces are alternately sealed, in which case the gas passes through the partition 15. At this time, the porosity of the surface layer 18 is preferably 30 to 70%. If the porosity of the surface layer 18 is 30% or more, the compartment 13 provided with the surface layer 18 can be better used as an exhaust gas flow path. If the porosity of the surface layer 18 is 70% or less, the induction heating performance of the catalyst carrier 10 is better. The porosity of the surface layer 18 is more preferably 35 to 65%, and further preferably 40 to 60%. It should be noted that, from the perspective of sample cutting, it is difficult to measure the porosity of the surface layer 18 using the mercury injection method. In this case, it can be measured using image analysis. In the case of a honeycomb structure of a type in which the compartment passes from the inlet to the outlet, the porosity of the surface layer 18 is preferably 10% or more and 40% or less. When the porosity is 10% or more, the water content of the catalyst slurry can be easily absorbed, and the catalyst coating property is good. When the porosity is 40% or less, the strength can be maintained even if the partition wall thickness is thin. The porosity of the surface layer 18 is more preferably 20% or more and 35% or less.

[0068] Regarding the compartment 13 on which the surface layer 18 containing magnetic body is arranged on the next door 15, for the compartments adjacent in the vertical and horizontal directions, it is possible to configure every other compartment to form a houndstooth pattern, or to configure every other two compartments, three compartments or multiple compartments, or to configure continuously. There is no restriction on the number or configuration of the compartments on which the surface layer 18 containing magnetic body is arranged on the next door 15, and it can be appropriately designed as needed. From the viewpoint of improving the heating effect, it is best to increase the number of compartments on which the surface layer 18 containing magnetic body is arranged on the next door 15, but from the viewpoint of reducing the pressure loss, it is best to reduce the number of compartments as much as possible.

[0069] The surface layer 18 including a magnetic substance provided on the partition wall 15 may be as follows. Figure 5 As shown in FIG. 1 , the catalyst carrier 40 is provided from the end surface on the inlet side of the gas flow direction to the end surface on the outlet side. Figure 7 As shown, the catalyst carrier 50 is provided midway from the end surface on the inlet side in the gas flow direction to the compartment 13 .

[0070] When the surface layer 18 including a magnetic body provided on the partition wall 15 is provided from the end surface on the inlet side of the catalyst carrier in the gas flow direction to the middle of the compartment 13, it is preferable as follows Figure 7 As shown in the gas flow direction of the catalyst carrier 50, there is a portion α where the region where the catalyst 12 is provided and the region where the surface layer 18 containing the magnetic body is provided overlap. According to this structure, the heat from the magnetic body generated by induction heating is well transferred to the catalyst 12, so the catalyst 12 can be heated more effectively. If the portion α where the region where the catalyst 12 is provided and the region where the surface layer 18 containing the magnetic body is provided overlap is large, the catalyst 12 can be heated well accordingly. From this point of view, the length of the overlapping portion α is preferably 10% or more of the region where the catalyst 12 is supported in the gas flow direction of the catalyst carrier of the compartment 13, more preferably 15% or more, and further preferably 20%. The upper limit is not particularly limited, and it is 100% or less.

[0071] The magnetic body is preferably formed by dispersing magnetic powder. The magnetic powder may be dispersed and contained in the surface layer 18, or may be directly dispersed and supported on the partition walls 15 of the honeycomb structure 11. The average particle size of the magnetic powder may be 10 to 200 μm. In addition, the dispersibility of the magnetic powder may be non-uniform.

[0072] <Method for producing catalyst carrier>

[0073] Next, the manufacturing method of the catalyst carrier involved in the embodiment of the present invention is described. First, a honeycomb structure having a ceramic partition wall and a plurality of compartments formed by the partition walls is produced. For example, in the case of producing a honeycomb structure formed of cordierite, first, a cordierite raw material is prepared as a blank material. Regarding the cordierite raw material, since each component is combined according to the theoretical composition of cordierite crystals, a silica source component, a magnesium oxide source component, and an alumina source component are combined. Among them, as the silica source component, quartz and fused silica are preferably used. In addition, it is preferred that the particle size of the silica source component is 100 to 150 μm.

[0074] As the magnesium oxide source component, for example, talc, magnesite, etc. can be cited. Among them, talc is preferred. The cordierite raw material preferably contains 37 to 43% by mass of talc. The particle size (average particle size) of talc is preferably 5 to 50 μm, more preferably 10 to 40 μm. In addition, the magnesium oxide (MgO) source component may contain Fe as an impurity. 2 O 3 , CaO, Na 2 O.K 2 O etc.

[0075] As the alumina source component, it is preferred to contain at least one of alumina and aluminum hydroxide in terms of less impurities. In addition, the cordierite forming raw material preferably contains 10 to 30% by mass of aluminum hydroxide and preferably contains 0 to 20% by mass of alumina.

[0076] Next, a material for a blank (additive) to be added to the cordierite forming raw material is prepared. As the additive, at least a binder and a pore former are used. In addition to the binder and the pore former, a dispersant and a surfactant may be used.

[0077] As a pore-forming agent, a substance that can react with oxygen below the firing temperature of cordierite and be oxidatively removed or a low-melting-point reaction substance having a melting point at a temperature below the firing temperature of cordierite can be used. As a substance that can be oxidatively removed, for example, resin (especially granular resin), graphite (especially granular graphite) and the like can be cited. As a low-melting-point reaction substance, at least one metal selected from the group consisting of iron, copper, zinc, lead, aluminum and nickel, an alloy with these metals as the main component (for example, carbon steel, cast iron, stainless steel in the case of iron), or an alloy with two or more as the main components can be used. Among them, the low-melting-point reaction substance is preferably a powdery or fibrous iron alloy. In addition, its particle size or fiber diameter (average diameter) is preferably 10 to 200 μm. Regarding the shape of the low-melting-point reaction substance, spherical, diamond-shaped, and candied sugar-shaped candies can be cited. If these shapes are used, it is easy to control the shape of the pores, so it is preferred.

[0078] Examples of binders include hydroxypropylmethylcellulose, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. Examples of dispersants include dextrin and polyols. Examples of surfactants include fatty acid soaps. It should be noted that the additives may be used alone or in combination of two or more.

[0079] Next, a binder, a pore former, a dispersant and water are mixed in a ratio of 3 to 8 parts by mass of a binder, 3 to 40 parts by mass of a pore former, 0.1 to 2 parts by mass of a dispersant and 10 to 40 parts by mass of water to 100 parts by mass of a cordierite forming raw material, and these materials for a blank are kneaded to prepare a blank.

[0080] Next, the prepared blank is formed into a honeycomb shape by extrusion molding, injection molding, compression molding, etc. to obtain a raw honeycomb molded body. Extrusion molding is preferably used because continuous molding is easy, for example, cordierite crystals can be oriented. The extrusion molding method can be performed using a vacuum clay kneader, a drum extruder, a twin-screw continuous extruder, and the like.

[0081] Next, the honeycomb formed body is dried and adjusted to a predetermined size to obtain a honeycomb dried body. The honeycomb formed body can be dried by hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying, etc. It should be noted that, from the perspective of being able to dry the entire body quickly and uniformly, it is preferred to perform drying by combining hot air drying with microwave drying or dielectric drying.

[0082] Next, a magnetic body is placed on the honeycomb dry body. Here, the manufacturing process will be described for each form of the magnetic body.

[0083] (1) The case where the magnetic substance is a magnetic powder contained in the surface layer and the surface layer is provided on the partition wall of the cell.

[0084] First, a slurry for forming a surface layer is prepared by mixing a magnetic powder and a fixing adhesive material composed of glass or the like. Specifically, for example, a magnetic powder and a glass powder are mixed, and a binder, a dispersant, and water are mixed therein to prepare a slurry for forming a surface layer. The mixing ratio of the magnetic powder and the glass powder is 1:1 or more and 20:1 or less by volume.

[0085] Next, a mask is applied to a portion of the cells of the end face on the upstream side of the honeycomb dried body, the end face is immersed in a storage container storing a slurry for forming a surface layer, and the slurry for forming a surface layer is applied to the cells where the mask is not applied. At this time, the slurry for forming a surface layer is applied to the cells in the area of ​​a specified length from one end face of the honeycomb dried body. After that, it is dried to remove the moisture of the slurry for forming a surface layer, and a surface layer is formed on the walls of the cells. The above-mentioned drying conditions can be the same as the conditions for drying the honeycomb formed body. In addition, regarding the above-mentioned firing conditions, when a cordierite raw material is used, it can usually be fired at a temperature of 1410 to 1440°C for 3 to 15 hours in an atmospheric atmosphere. It should be noted that when the surface layer is formed in all the cells of the honeycomb structure, the slurry for forming a surface layer can be applied to the cells without applying a mask to the end face on the upstream side.

[0086] As a method of filling the slurry into the cells, a simple method is to push the paste-like material with a scraper such as a squeegee. It is relatively simple to control the depth by the number of times the squeegee is pushed in.

[0087] (2) The magnetic body is a magnetic powder and is filled in the cell in a state of being contained in a binder or adhesive material.

[0088] A slurry containing magnetic powder and a bonding material mainly composed of metal or glass is flowed into the cells of the honeycomb dry body, and heated at a temperature above the melting point of the metal or the softening point of the glass to solidify. Alternatively, a slurry containing magnetic powder and a bonding material mainly composed of silicon dioxide or aluminum oxide is flowed into the cells of the honeycomb dry body, and heated to solidify the silicon dioxide or aluminum oxide.

[0089] When using a bonding material with metal or glass as the main component, it is necessary to temporarily melt or soften it below the heat resistance temperature of the honeycomb drying body. Therefore, it is preferred to heat it above the melting point or softening point of the bonding material. In addition, since the maximum temperature in the use environment reaches about 700°C, it is more preferred to use a metal or glass with a melting point or softening point above this temperature. As a specific melting point or softening point, for example, it is 800 to 1200°C. On the other hand, when using a bonding material with silica or alumina as the main component, it is preferred that the bonding material be cured by heating and drying during manufacture. As a material that can cure the above-mentioned bonding material by heating and drying, for example, a colloidal dispersion of silica or alumina can be cited, and it can also be a colloidal dispersion containing silica and alumina. In addition, since the maximum temperature in the use environment reaches about 700°C, it is more preferred to use silica or alumina with a heat resistance temperature above this temperature. After the slurry flows into the compartment of the honeycomb drying body, a suction tool is installed at the downstream of the honeycomb drying body to suction from the downstream of the honeycomb drying body, i.e., the other end face side, to remove excess water and fill the material containing the magnetic body. As the conditions for heating the material containing the magnetic body, it is preferred to heat at a temperature of 800 to 1200° C. for 0.5 to 3 hours.

[0090] In the case of using a bonding material with alumina or silica as the main component, the process of flowing the slurry into the compartment can be performed at the stage of honeycomb forming and drying. In this case, after flowing the slurry into the compartment of the honeycomb formed body, the honeycomb formed body is dried, and in the firing process of the honeycomb dried body, the process of fixing the magnetic body to the bonding material is simultaneously performed. Silica or alumina preferably exhibits the effect of solidification due to drying.

[0091] (3) The magnetic body has a plate-like, rod-like, ring-like, filament-like or fiber-like shape and is filled in the cells.

[0092] First, considering the cross-sectional shape of the cells of the honeycomb dried body to be filled with magnetic body and the length of the cells, a prescribed plate-shaped, rod-shaped, filament-shaped or fiber-shaped magnetic body is prepared. Next, the magnetic body is inserted into the prescribed cells of the honeycomb dried body and inserted to a prescribed length from the end face on the upstream side, thereby filling the cells with the magnetic body. In addition, when the magnetic body is annular, the end face on the upstream side of the honeycomb dried body is cut and removed to a prescribed depth in advance to form a groove, and the annular magnetic body is inserted into the groove. Alternatively, a raw honeycomb formed body with a groove formed therein is prepared in advance, dried, and after the honeycomb dried body is prepared, the annular magnetic body is inserted into the groove.

[0093] After the magnetic body is provided, the catalyst is loaded in the predetermined cells of the honeycomb dried body. The method for loading the catalyst is not particularly limited, and the catalyst loading method can be performed using a conventional method for producing a catalyst carrier. In this way, the catalyst carrier according to the embodiment of the present invention can be produced.

[0094] <Induction Heating Catalytic System>

[0095] Figure 8 2 shows a schematic cross-sectional view parallel to the gas flow direction of the induction heating catalytic system 100 according to the embodiment of the present invention. The induction heating catalytic system 100 includes a catalyst carrier 10 according to the embodiment of the present invention and a coil 19 provided on the outer periphery of the catalyst carrier 10.

[0096] The coil 19 is spirally wound around the outer circumference of the catalyst carrier. The coil 19 can be arranged at a position corresponding to the area where the magnetic body is arranged in the airflow direction of the catalyst carrier. For example, Figure 3 , Figure 4 , Figure 7 The catalyst carrier shown is provided with coils 19 in a manner corresponding only to the region where the magnetic body is provided in the gas flow direction of the catalyst carrier. Thus, the heating efficiency of the catalyst carrier is improved, and the induction heating catalytic system 100 can be simplified. The induction heating catalytic system 100 can be provided with a metal tube 23 that holds the catalyst carrier 10 and the coils 19 by sandwiching an inorganic gasket 22.

[0097] In the induction heating catalytic system 100, the alternating current flowing through the coil generates a change in the magnetic field. The magnetic body generates heat in accordance with the change in the magnetic field, and the catalyst carrier is heated by the heat. As a result, the temperature of the catalyst increases, and the catalytic reaction is promoted. Depending on the type of catalyst, carbon monoxide (CO), nitrogen oxides (NO x ), hydrocarbons (CH) are oxidized or reduced to carbon dioxide (CO 2 ), nitrogen (N 2 ), water (H 2 O). The above functions are exerted to purify the exhaust gas passing through the catalyst carrier. As described above, the catalyst carrier of the induction heating catalytic system 100 has a region A where no catalyst is carried at least on the end face side of the inlet side in the airflow direction. The end face side of the catalyst carrier on the inlet side in the airflow direction is a low-temperature region, and it is difficult for the catalyst to reach a sufficient active temperature. Therefore, by setting the low-temperature region as the region A where no catalyst is carried, the catalyst can be effectively used without waste during induction heating, thereby reducing the amount of catalyst used, and therefore, the manufacturing cost of the induction heating catalytic system 100 is reduced.

[0098] Example

[0099] Hereinafter, examples are described for better understanding of the present invention and its advantages; however, the present invention is not limited to the examples.

[0100] (Example 1)

[0101] Fig. 9 : A schematic cross-sectional view parallel to the airflow direction of the induction heating catalytic system prepared in Example 1 is shown. Fig. 9 In the text, "SCR" stands for selective reduction catalyst, "DOC" stands for oxidation catalyst, "DPF" stands for diesel particulate filter, "CC-" stands for directly under the engine, and "UF" stands for underfloor.

[0102] As the configuration conditions of the catalyst carrier during the simulation, Fig. 9 As shown, the following conditions are set, namely, in the air flow direction, CC-SCR61 is arranged at a position 200 mm away from the inlet of the metal pipe 67 serving as the exhaust gas flow path of the diesel engine, DOC62 / DPF63 is arranged at a position 400 mm away from CC-SCR61, mixer 64 is arranged at a position 250 mm away from DPF63, and UF-SCR65 is arranged at a position 250 mm away from the mixer 64.

[0103] The CC-SCR was carried out under the following conditions: 200 g / L of SCR catalyst was supported on a cordierite carrier (diameter 267 mm, rib thickness 0.076 mm, cell density 93 cells / cm) with a length of 152.4 mm in the cell extension direction. 2 ) in a compartment. In Example 1, the area where the SCR catalyst is provided is set as the area within 50 mm from the end face on the outlet side of the cordierite carrier in the air flow direction in the compartment (the area of ​​50 mm in the second half). That is, the area within 102.4 mm from the end face on the inlet side of the cordierite carrier in the air flow direction is set as area A where the catalyst is not loaded. This area A is the position from the inlet side end face of the cordierite carrier to 67% of the length of the cordierite carrier. In addition, the CC-SCR of Example 1 has a compartment filled with a magnetic body from the end face on the inlet side of the cordierite carrier in the air flow direction to the end face on the outlet side. The magnetic body is set to the following conditions, that is, a material obtained by mixing Fe-Cr particles with a particle size of 20 μm and glass on a volume basis of Fe-Cr particles: glass = 8:2 at a configuration of 100 g / L.

[0104] Using this induction heating catalyst system as an application example of CC-SCR for a diesel engine (displacement 10L), the analysis software Exothermia suite 2019.2 was used to simulate the NO emission of the US exhaust gas restriction mode (FTP) for the first 500 seconds (power: 30kW) under the following initial conditions, power-on conditions, and exhaust gas supply conditions.x emission.

[0105] <Initial conditions>

[0106] Honeycomb structure temperature: 300K

[0107] Initial ammonia absorption capacity: 0g / L for CC-SCR and UF-SCR

[0108] <Electrification conditions>

[0109] Dielectric heating method: Heat equivalent to 30kW of dielectric heating is evenly supplied to the entire CC-SCR area

[0110] Power-on time: 500 seconds from the start of FTP driving mode

[0111] <Exhaust gas supply conditions>

[0112] ·NH 3 Concentration: Press to enter gas NO x Supply at 1.5 times the concentration for 0 to 500 seconds

[0113] (Comparative Example 1)

[0114] As Comparative Example 1, simulation was performed under the same conditions as in Example 1 except that the CC-SCR catalyst arrangement region was set to the entire region from the end surface on the inlet side to the end surface on the outlet side of the cordierite carrier in the gas flow direction.

[0115] (Reference Example 1: Standard value)

[0116] As Reference Example 1, the same structure as Comparative Example 1 was adopted except that no magnetic body was arranged in the CC-SCR, no coil was arranged around the CC-SCR, and no induction heating was performed. x Emissions were set to a baseline value of 100%.

[0117] The above test conditions and simulation results are shown in Table 1. x The emission (relative value %) is given as a relative value relative to the reference value of Reference Example 1 of 100%.

[0118] [Table 1]

[0119]

[0120] As shown in Table 1, compared with Comparative Example 1 in which the catalyst is provided in the entire area of ​​the CC-SCR, Example 1 is considered to be able to effectively suppress the NH3 on the inlet side of the CC-SCR in the air flow direction because the catalyst is provided only in the area of ​​50 mm in the rear half of the CC-SCR. 3 Furthermore, it is considered that Example 1 does not support the catalyst in a region where the temperature rise is insufficient near the airflow inlet of the CC-SCR, and can effectively utilize the catalyst without waste during induction heating.

[0121] (Example 2)

[0122] As Example 2, relative to Example 1, the cordierite carrier of the CC-SCR is divided into a front half and a rear half at the same distance in the gas flow direction, and the same magnetic body and coil as in Example 1 are provided only in the front half, and the catalyst is supported only in the rear half.

[0123] That is, the cordierite carrier of Example 2 is the same as the cordierite carrier of Example 1, and the length in the extension direction of the compartment is 152.4 mm. In addition, the length in the extension direction of the compartment of the catalyst configuration area in the second half is 76.2 mm. The area A where the magnetic body is configured in the airflow direction is configured from the end face of the cordierite carrier on the inlet side in the airflow direction to a position of 50% of the length of the cordierite carrier. In this way, in the airflow direction of the cordierite carrier of the CC-SCR of Example 2, there is no portion α where the area where the catalyst is provided and the area where the magnetic body is provided overlap.

[0124] In addition, the power during induction heating was set to 10 kW. A simulation was performed under the same conditions as in Example 1 except for the above.

[0125] (Example 3)

[0126] As Example 3, with respect to Example 2, in the airflow direction of the cordierite carrier of the CC-SCR, the area where the magnetic body and the coil are arranged is extended by 22.9 mm toward the catalyst arrangement area, so that the portion α where the catalyst arrangement area and the area where the magnetic body are arranged overlaps is 30% of the entire catalyst arrangement area, and otherwise the simulation is performed under the same conditions as Example 2. At this time, the area A where the magnetic body is arranged in the airflow direction is arranged from the end surface of the cordierite carrier on the airflow direction inlet side to a position of 65% of the length of the cordierite carrier.

[0127] (Example 4)

[0128] As Example 4, with respect to Example 2, in the airflow direction of the cordierite carrier of the CC-SCR, the area where the magnetic body and the coil are arranged is extended by 38.1 mm toward the catalyst arrangement area so that the portion α where the catalyst arrangement area and the area where the magnetic body are arranged overlaps is 50% of the entire catalyst arrangement area, and otherwise the simulation is performed under the same conditions as Example 2. At this time, the area A where the magnetic body is arranged in the airflow direction is arranged from the end surface of the cordierite carrier on the airflow direction inlet side to a position of 75% of the length of the cordierite carrier.

[0129] (Example 5)

[0130] As Example 5, with respect to Example 2, in the airflow direction of the cordierite carrier of the CC-SCR, the area where the magnetic body and the coil are arranged is extended by 60.96 mm toward the catalyst arrangement area, so that the portion α where the catalyst arrangement area and the area where the magnetic body are arranged overlaps is 80% of the entire catalyst arrangement area, and otherwise the simulation is performed under the same conditions as Example 2. At this time, the area A where the magnetic body is arranged in the airflow direction is arranged from the end surface of the cordierite carrier on the airflow direction inlet side to a position of 90% of the length of the cordierite carrier.

[0131] The above test conditions and simulation results are shown in Table 2. x The emission (relative value %) is given as a relative value relative to the reference value of Reference Example 1 of 100%.

[0132] [Table 2]

[0133]

[0134] As shown in Table 2, it is known that if the overlap portion α between the region where the catalyst is provided and the region where the magnetic body is provided is large, the catalyst can be heated well accordingly, thereby improving the exhaust gas purification performance.

[0135] Explanation of symbols

[0136] 10, 20, 30, 40, 50…catalyst carrier

[0137] 11, 21, 31, 41, 51…honeycomb structure

[0138] 12…Catalyst

[0139] 13…Compartment

[0140] 14…Outer wall

[0141] 15…Next door

[0142] 16…Columnar honeycomb structure

[0143] 17…Magnetic body

[0144] 18…Surface layer

[0145] 19…Coil

[0146] 22…Inorganic gasket

[0147] 23…Metal pipe

[0148] 61…CC-SCR

[0149] 62…DOC

[0150] 63…DPF

[0151] 64…Mixer

[0152] 65…UF-SCR

[0153] 66…Inorganic gasket

[0154] 67…Metal pipe

[0155] 68…Coil

[0156] 100…Induction Heating Catalytic System

Claims

1. A catalyst carrier for induction heating, characterized in that: have: A honeycomb structure having a columnar honeycomb structure portion having an outer peripheral wall and partition walls, wherein the partition walls are arranged inside the outer peripheral wall and partition a plurality of cells, and the plurality of cells extend from an end face on an inlet side to an end face on an outlet side in an air flow direction to form a flow path; A catalyst supported inside the partition wall; as well as A magnetic body, which is disposed in the honeycomb structure. The catalyst carrier has a region A on which the catalyst is not supported on at least the end surface side on the inlet side in the gas flow direction, In the airflow direction, the magnetic body is arranged at least in the region A. The magnetic body is annular, and a groove is provided on an end surface of the catalyst carrier on the inlet side in the gas flow direction, and the annular magnetic body is buried in the groove.

2. The catalyst carrier for induction heating according to claim 1, characterized in that: The region A is arranged from the end surface of the catalyst carrier on the inlet side in the gas flow direction to a position that is 10% to 70% of the length of the catalyst carrier.

3. The catalyst carrier for induction heating according to claim 1, characterized in that: In the direction of gas flow, there is a portion where the region where the catalyst is supported and the region where the magnetic body is provided overlap.

4. The catalyst carrier for induction heating according to any one of claims 1 to 3, characterized in that The catalyst is an SCR catalyst.

5. The catalyst carrier for induction heating according to any one of claims 1 to 3, characterized in that The magnetic body is formed by dispersing magnetic powder.

6. An induction heating catalytic system, characterized in that: have: The catalyst carrier for induction heating according to any one of claims 1 to 5; and The coil is arranged on the outer periphery of the catalyst carrier.

7. The induction heating catalytic system according to claim 6, characterized in that: The coil is provided at a position corresponding to a region where the magnetic body is provided in the air flow direction of the catalyst carrier.

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