JP2011230116A - Honeycomb structure and exhaust gas cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure hardly causing electrode disconnection and capable of individually adjusting heat generation amounts of the central part and an outer circumferential part, and to provide an exhaust gas cleaning device including the honeycomb structure.SOLUTION: The honeycomb structure 10 is a cylindrical honeycomb structure 10 in which four honeycomb units 11 having a plurality of through-holes arranged in parallel along a longitudinal direction and including conductive ceramics are bonded via an adhesive layer 12. The honeycomb unit 11 has a sector-like section perpendicular to the longitudinal direction. A pair of electrodes 13 are formed on an outer circumferential surface of the honeycomb unit 11 not facing the adhesive layer 12. The electrode 13 is extended between the honeycomb unit 11 and the adhesive layer 12. The pair of electrodes 13 are formed between the outer circumferential surface of the honeycomb unit 11 and the adhesive layer 12. The pair of electrodes 13 are formed in a region including the center of the sector shape of the section perpendicular to the longitudinal direction of the honeycomb unit 11.

Description

  The present invention relates to a honeycomb structure and an exhaust gas purification device.

  Automobile exhaust gas contains substances such as hydrocarbon compounds, carbon monoxide, and nitrogen oxides. To purify such exhaust gas, a honeycomb structure composed of cordierite is used. Yes. In such a honeycomb structure, a catalyst supporting layer made of alumina is formed on the surface of partition walls separating a plurality of through holes, and a catalyst such as platinum, rhodium, palladium, etc. is supported on the catalyst supporting layer.

  However, when the temperature of the exhaust gas is lowered, there is a problem that the function (activity) of the catalyst supported on the catalyst support layer is not sufficiently exhibited, and the exhaust gas purification ability is reduced.

  Therefore, Patent Document 1 discloses that a heating element such as a silicon carbide material is used as a base material of a honeycomb unit, and a catalyst body having an integral structure consisting of a single honeycomb unit is placed in a catalyst container connected to an exhaust passage. A terminal is joined to the outer periphery of the catalyst body through an insulator, and the catalyst body is heated by energizing the power source from the power source through the terminal only when the catalyst body is in a predetermined temperature condition. A catalytic exhaust gas purification apparatus in an internal combustion engine that is heated is disclosed.

  On the other hand, Patent Document 2 discloses an exhaust gas filter in which a plurality of porous ceramic filters for purifying exhaust gas from an internal combustion engine are combined, and a pair of self-heating electrodes are provided at both ends. Yes.

Japanese Utility Model Publication No. 49-12412 Japanese Patent Laid-Open No. 7-80226

  However, when a pair of self-heating electrodes are formed at both ends of a conventional catalyst body having a single structure composed of a single honeycomb unit described in Cited Document 1, the temperature at the center of the catalyst body decreases, There is a problem that the exhaust gas purification ability tends to decrease. Moreover, when the heat insulation performance of the outer peripheral part of a catalyst body is inadequate, there exists a problem that the temperature of the outer peripheral part of a catalyst body falls and a crack tends to generate | occur | produce.

  The conventional exhaust gas filter described in FIG. 6 of the cited document 2 is a combination of a filter having a substantially square cross section and a filter having a substantially isosceles triangular cross section. Since a heat generating electrode is provided, if the holding sealing material is placed on the outer periphery of the exhaust gas filter and canned to a metal tube, the surface pressure at the corner of the filter increases and the self-heating electrode is disconnected. There is a problem that it becomes easy to do.

  The present invention has been made in view of the above-described problems of the prior art, and it is difficult for the electrodes to be disconnected, and a honeycomb structure capable of individually adjusting the calorific value of the central portion and the outer peripheral portion, and an exhaust gas purification apparatus having the honeycomb structure. The purpose is to provide.

  The honeycomb structure of the present invention has a cylindrical or elliptical columnar honeycomb in which a plurality of through holes are arranged in the longitudinal direction and a plurality of honeycomb units containing conductive ceramics are bonded via an adhesive layer. The honeycomb unit has a fan-shaped or elliptical fan-shaped cross section perpendicular to the longitudinal direction, and a pair of electrodes is formed on an outer peripheral surface of the honeycomb unit not facing the adhesive layer. The pair of electrodes extends between the honeycomb unit and the adhesive layer, and / or a pair of electrodes is formed between the outer peripheral surface of the honeycomb unit and the adhesive layer. The pair of electrodes is formed in a region including a fan-shaped or elliptical fan-shaped center having a cross section perpendicular to the longitudinal direction of the honeycomb unit.

  The pair of electrodes are preferably formed over the entire outer periphery of the honeycomb unit.

  The pair of electrodes are preferably formed on outer peripheral surfaces of both end portions in the longitudinal direction of the honeycomb unit.

  It is desirable that the distance between the pair of electrodes is smaller as the center of the fan shape or elliptical fan shape is closer.

  It is desirable that the central angle of the fan-shaped or elliptical fan-shaped is 90 ° or less.

  The electrodes are preferably band-shaped electrodes having a width of 3 mm or more and 30 mm or less, and the distance between the band-shaped electrodes is preferably adjusted so that the resistance between the band-shaped electrodes is substantially the same.

  The electrode is preferably formed by thermal spraying or sputtering.

  Desirably, a catalyst is supported on the partition walls separating the plurality of through holes, and the catalyst is desirably at least one selected from the group consisting of platinum, rhodium and palladium.

  The conductive ceramic preferably includes silicon carbide.

  The exhaust gas purification apparatus of the present invention has the honeycomb structure of the present invention.

  According to the present invention, it is possible to provide a honeycomb structure and an exhaust gas purification apparatus having the honeycomb structure, in which the electrodes are difficult to be disconnected and the calorific values of the central portion and the outer peripheral portion can be individually adjusted.

It is a perspective view which shows an example of the honeycomb structure of this invention. It is a perspective view which shows the honeycomb unit of FIG. FIG. 2 is a diagram illustrating a surface on which an adhesive layer of the honeycomb unit of FIG. 1 is formed. It is a figure which shows the modification of the honeycomb unit of FIG. It is a figure which shows the modification of the honeycomb unit of FIG. It is a perspective view which shows the modification of the honeycomb structure of FIG. It is a perspective view which shows the modification of the honeycomb structure of FIG. It is sectional drawing which shows an example of the exhaust gas purification apparatus of this invention.

  Next, the form for implementing this invention is demonstrated with drawing.

  FIG. 1 shows an example of the honeycomb structure of the present invention. In the honeycomb structure 10, four honeycomb units 11 (see FIG. 2), in which a plurality of square columnar through holes 11a are arranged in parallel in the longitudinal direction with a partition wall 11b therebetween, are bonded via an adhesive layer 12. It is cylindrical. Moreover, the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is a fan shape having a central angle of 90 °, and the honeycomb unit 11 includes conductive ceramics. Further, a pair of strip electrodes 13 are formed on the entire outer periphery of both end portions in the longitudinal direction of each honeycomb unit 11.

  In the present specification and claims, the end of the honeycomb unit 11 includes the vicinity of the end of the honeycomb unit 11. Further, the vicinity of the end of the honeycomb unit 11 means that the distance from the end surface of the honeycomb unit 11 is 30 mm or less. Furthermore, the outer peripheral surface does not include the end surface.

  The pair of strip electrodes 13 are formed on the outer peripheral surface not facing the adhesive layer 12 of each honeycomb unit 11, and extend between the honeycomb unit 11 and the adhesive layer 12, in addition to the honeycomb unit 11. Is formed between the outer peripheral surface of the honeycomb unit 11 and the adhesive layer 12 and is formed in a region including a fan-shaped center having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11. For this reason, for example, when a voltage is applied between the belt-like electrodes 13 from the automobile battery via a pair of annular conductive members electrically connected to the four pairs of belt-like electrodes 13, the center of the honeycomb unit 11 The current density of the current flowing through the part and the outer peripheral part can be made uniform. As a result, the calorific values of the central part and the outer peripheral part of the honeycomb unit 11 become uniform, and the temperatures of the central part and the outer peripheral part of the honeycomb unit 11 can be made uniform. Moreover, since the same voltage is applied to the four honeycomb units 11, the temperature of the honeycomb structure 10 can be made uniform.

  In addition, the center part and outer peripheral part of the honeycomb unit 11 mean the area | region of the center side and outer periphery side when the distance to the fan-shaped center and outer periphery of a cross section perpendicular | vertical to the longitudinal direction of the honeycomb unit 11, respectively is divided into two equal parts. To do.

  Further, since the honeycomb structure 10 has a columnar shape, even if the holding sealing material 20 is disposed on the outer periphery of the honeycomb structure 10 and canned to the metal tube 30, the surface pressure of the outer periphery of each honeycomb unit 11 is Is uniform, it is difficult for the strip electrode 13 to be disconnected (see FIG. 8).

  The conductive ceramic is not particularly limited as long as it can generate sufficient heat when a predetermined current is passed through the honeycomb unit 11, and examples thereof include silicon carbide doped with aluminum nitride, aluminum or the like.

The honeycomb unit 11 preferably has a resistance between the strip electrodes 13 of 1 to 1 × 10 ³ Ω. If the resistance between the strip electrodes 13 of the honeycomb unit 11 is less than 1Ω, even if the honeycomb unit 11 is energized, heat is not sufficiently generated due to Joule's law. On the other hand, if the resistance between the strip electrodes 13 of the honeycomb unit 11 exceeds 1 × 10 ³ Ω, for example, even if a voltage is applied between the strip electrodes 13 using a high capacity battery mounted on a hybrid vehicle. The current flowing through the honeycomb unit 11 becomes small, and it becomes difficult to sufficiently heat the honeycomb unit 11.

  When the resistance of the four honeycomb units 11 varies, it is preferable that the distance between the strip electrodes 13 is adjusted so that the resistance between the strip electrodes 13 is substantially the same. Accordingly, when the four honeycomb units 11 are energized, the calorific values of the four honeycomb units 11 can be made substantially the same.

  The honeycomb unit 11 preferably has a porosity of 25 to 50%. When the porosity of the honeycomb unit 11 is less than 25%, the heat capacity of the honeycomb unit 11 is increased and it is difficult to generate heat. On the other hand, when the porosity of the honeycomb unit 11 exceeds 50%, the strength of the honeycomb unit 11 becomes insufficient.

  The porosity of the honeycomb unit 11 can be measured using a mercury intrusion method.

The honeycomb unit 11 preferably has a cross-sectional area of a cross section perpendicular to the longitudinal direction of 5 to 50 cm ² . When the cross-sectional area of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is less than 5 cm ² , the pressure loss of the honeycomb structure 10 increases. On the other hand, when the cross-sectional area of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 exceeds 50 cm ² , the strength against the thermal stress generated in the honeycomb unit 11 becomes insufficient.

  The honeycomb unit 11 preferably has an opening ratio of a cross section perpendicular to the longitudinal direction of 50 to 85%. When the opening ratio of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is less than 50%, the heat capacity of the honeycomb unit 11 increases and it becomes difficult to generate heat. On the other hand, when the aperture ratio of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 exceeds 85%, the strength of the honeycomb unit 11 becomes insufficient.

Density of the through hole 11a of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is preferably 15.5 to 186 cells / cm ^2, more preferably 31 to 155 pieces / cm ^2, 46.5 to 124 pieces / Cm ² is more preferable. When the density of the through-holes 11a having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is less than 15.5 / cm ² , the exhaust gas and the catalyst come into contact when the catalyst is supported on the partition walls 11b of the honeycomb unit 11. The exhaust gas purification rate decreases. On the other hand, when the density of the through holes 11a having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11 exceeds 186 / cm ² , the pressure loss of the honeycomb structure 10 increases.

  The thickness of the partition wall 11b of the honeycomb unit 11 is preferably 0.05 to 0.30 mm. When the thickness of the partition wall 11b is less than 0.05 mm, the strength of the honeycomb unit 11 is lowered. On the other hand, when the thickness of the partition wall 11b exceeds 0.30 mm, the heat capacity of the honeycomb unit 11 is increased and it is difficult to generate heat.

  A catalyst may be supported on the partition walls 11 b of the honeycomb unit 11.

  The catalyst supported on the partition wall 11b is not particularly limited as long as the exhaust gas can be purified. Examples thereof include platinum, rhodium, and palladium.

  Further, it is preferable that a catalyst supporting layer made of γ-alumina is formed on the surface of the partition wall 11b, and the catalyst is supported on the catalyst supporting layer.

  A method for producing the honeycomb unit 11 composed of silicon carbide doped with aluminum nitride is not particularly limited, and examples thereof include a method of firing a molded body formed using a raw material paste containing silicon carbide and aluminum nitride. It is done.

  The content of aluminum nitride in the raw material paste is preferably 0.1 to 30% by mass.

  The raw material paste may further contain an organic binder, a dispersion medium, a molding aid, and the like as necessary.

  Although it does not specifically limit as an organic binder contained in a raw material paste, Methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyethyleneglycol, a phenol resin, an epoxy resin etc. are mentioned, You may use 2 or more types together.

  The content of the organic binder in the raw material paste is preferably 1 to 10% by mass with respect to silicon carbide.

  Although it does not specifically limit as a dispersion medium contained in raw material paste, Organic solvents, such as aqueous solvents, such as water and methanol; benzene, etc. are mentioned, You may use 2 or more types together.

  Although it does not specifically limit as a shaping | molding adjuvant contained in a raw material paste, Ethylene glycol, dextrin, a fatty acid, fatty acid soap, a polyalcohol etc. are mentioned.

  The method for preparing the raw material paste is not particularly limited, and examples thereof include a method of mixing using a mixer and an attritor and a method of kneading using a kneader.

  Although it does not specifically limit as a method to shape | mold using a raw material paste, Extrusion molding etc. are mentioned.

  The dryer used for drying the molded body is not particularly limited, and examples thereof include a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, and a freeze dryer.

  The dried molded body is preferably degreased at 400 ° C. for 2 hours, for example.

  Furthermore, the degreased molded body is preferably fired at 2200 ° C. for 3 hours in an atmosphere of an inert gas such as argon.

  Nitrogen may be introduced at the time of firing, and silicon carbide may be doped with nitrogen.

  Instead of the honeycomb unit 11, a honeycomb unit including a conductive material in pores existing in the base material (aggregate) may be used.

  Although it does not specifically limit as a material which comprises the base material of a honeycomb unit, Silicon carbide, aluminum titanate, cordierite, an alumina, a silica, a zirconia, a zeolite, etc. are mentioned.

  A method for producing a substrate of a honeycomb unit made of silicon carbide is not particularly limited, and examples of the method for producing the honeycomb unit 11 include a method using a raw material paste not containing aluminum nitride.

  The conductive material contained in the pores present in the substrate of the honeycomb unit is not particularly limited as long as it can generate sufficient heat when energized, but silicon; silicides such as nickel silicide, chromium silicide, and iron silicide Etc.

  A method for forming a conductive layer containing silicon as the conductive material is not particularly limited, and examples thereof include a method of impregnating the surface of the honeycomb unit base material with molten silicon or a slurry containing silicon or a silicon precursor.

  In order to easily generate heat at the central part of the honeycomb structure, the central angle of the fan-shaped cross section perpendicular to the longitudinal direction of the honeycomb unit is not particularly limited as long as it is 90 ° or less, and preferably 75 ° or less. 60 ° or less is more preferable.

  Further, instead of the quadrangular columnar through-hole 11a, through-holes such as a triangular column shape and a hexagonal column shape may be provided in parallel.

  The adhesive layer 12 for bonding the honeycomb unit 11 preferably has a thickness of 0.5 to 2 mm. When the thickness of the adhesive layer 12 is less than 0.5 mm, the adhesive strength of the honeycomb unit 11 becomes insufficient. On the other hand, when the thickness of the adhesive layer 12 exceeds 2 mm, the pressure loss of the honeycomb structure 10 increases.

  The method for adhering the honeycomb unit 11 is not particularly limited, and examples thereof include a method of drying and solidifying after applying the adhesive layer paste.

  Although it does not specifically limit as a paste for contact bonding layers, The mixture of an inorganic binder and an inorganic particle, the mixture of an inorganic binder and an inorganic fiber, the mixture of an inorganic binder, an inorganic particle, and an inorganic fiber etc. are mentioned.

  Although it does not specifically limit as an inorganic fiber contained in the paste for contact bonding layers, Alumina, silica, silicon carbide, silica alumina, glass, potassium titanate, aluminum borate, etc. are mentioned, You may use 2 or more types together. Among these, silica alumina is preferable.

  The inorganic binder contained in the adhesive layer paste is not particularly limited, but includes alumina sol, silica sol, titania sol, inorganic sol of water glass, clay minerals such as white clay, kaolin, montmorillonite, sepiolite, attapulgite, etc. You may use together. Of these, alumina sol, silica sol, and titania sol are preferable.

  Although it does not specifically limit as an inorganic particle contained in the paste for contact bonding layers, Silicon carbide, an alumina, a silica, a titania, a zirconia, a ceria, a mullite etc. are mentioned, You may use 2 or more types together. Among these, silicon carbide is preferable.

  The adhesive layer paste may contain an organic binder.

  Although it does not specifically limit as an organic binder contained in the paste for contact bonding layers, Polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose etc. are mentioned, You may use 2 or more types together.

  Instead of manufacturing the columnar honeycomb structure 10, an elliptical columnar honeycomb structure may be manufactured. At this time, the honeycomb unit constituting the elliptical columnar honeycomb structure has an elliptical fan-shaped cross section perpendicular to the longitudinal direction. In addition, for example, a voltage can be applied between the belt electrode from the automobile battery through a pair of elliptical conductive members electrically connected to the pair of strip electrodes.

  In the present specification and claims, an ellipse and an ellipse in an elliptical sector include a track shape in which two semicircles are connected by two line segments having the same length.

  The strip electrode 13 is preferably made of metal.

  The width of the strip electrode 13 is preferably 3 to 30 mm. If the width of the strip electrode 13 is less than 3 mm, when a voltage is applied between the strip electrodes 13, the strip electrode 13 is easily damaged. On the other hand, if the width of the strip electrode 13 exceeds 30 mm, the volume of the honeycomb unit 11 that generates heat when a voltage is applied between the strip electrodes 13 becomes small, and the honeycomb structure 10 cannot sufficiently purify the exhaust gas.

  The method for forming the strip electrode 13 is not particularly limited, and examples thereof include thermal spraying and sputtering.

  The strip electrode 13 formed between the honeycomb unit 11 and the adhesive layer 12 is formed such that the distance between the pair of strip electrodes 13 is constant with respect to the radial direction of the honeycomb structure 10. However (see FIG. 3), the closer to the center of the honeycomb structure 10, the smaller the distance between the pair of strip electrodes 13 may be (see FIGS. 4 and 5). Thereby, the central portion of the honeycomb structure 10 is more likely to generate heat. 4 and 5 show that the width of the strip electrode 13 is larger as it is closer to the center of the honeycomb structure 10 and the width of the strip electrode 13 is constant with respect to the radial direction of the honeycomb structure 10. It is.

  Further, instead of the strip electrode 13, a wave electrode or a zigzag electrode may be formed.

  FIG. 6 shows a modification of the honeycomb structure 10. In the honeycomb structure 10 ′, instead of the strip electrode 13, a strip electrode 13 ′ extending between the honeycomb unit 11 and the adhesive layer 12 from the outer peripheral surface not facing the adhesive layer 12 of the honeycomb unit 11 is formed. The structure is the same as that of the honeycomb structure 10 except for the above.

  The pair of strip electrodes 13 ′ is formed on the outer peripheral surface not facing the adhesive layer 12 of each honeycomb unit 11 and extends between the honeycomb unit 11 and the adhesive layer 12. Therefore, for example, when a voltage is applied between the automobile battery and the strip electrode 13 ′ through a pair of annular conductive members electrically connected to the four pairs of strip electrodes 13 ′, the honeycomb unit 11 The current density of the current flowing in the outer peripheral part of the current can be made larger than the current density of the current flowing in the central part. As a result, the calorific value of the outer peripheral part of the honeycomb unit 11 can be made larger than the calorific value of the central part, and the temperature of the outer peripheral part of the honeycomb unit 11 can be made higher than the temperature of the central part. For this reason, when the holding sealing material 20 is disposed on the outer peripheral portion of the honeycomb structure 10 ′, the heat insulating performance of the holding sealing material 20 is insufficient when it can be used as an exhaust gas purification device by canning the metal tube 30. In addition, a decrease in the temperature of the outer peripheral portion of the honeycomb structure 10 ′ can be suppressed. In addition, since the same voltage is applied to the four honeycomb units 11, when the honeycomb structure 10 ′ is used as an exhaust gas purification device, even if the heat insulation performance of the holding sealing material 20 is insufficient, the honeycomb structure Since the temperature drop of the outer peripheral portion of 10 ′ can be suppressed, the temperature of the honeycomb structure 10 ′ can be made uniform, and the occurrence of cracks can be suppressed.

  The strip electrode 13 ′ has the same configuration as the strip electrode 13 except for the shape.

  FIG. 7 shows a modification of the honeycomb structure 10. The honeycomb structure 10 ″ is formed in a region including a fan-shaped center having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11 between the outer peripheral surface of the honeycomb unit 11 and the adhesive layer 12, instead of the band-shaped electrode 13. The structure is the same as that of the honeycomb structure 10 except that the strip electrode 13 ″ is formed.

  The pair of strip electrodes 13 ″ are formed between the outer peripheral surface of the honeycomb unit 11 and the adhesive layer 12 and are formed in a region including a fan-shaped center having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11. For this reason, for example, when a voltage is applied between the strip electrode 13 "from the automobile battery via a pair of annular conductive members electrically connected to the four pairs of strip electrodes 13", the honeycomb unit It is possible to make the current density of the current flowing in the central portion of the core 11 greater than the current density of the current flowing in the outer peripheral portion, and as a result, make the calorific value of the central portion of the honeycomb unit 11 larger than the calorific value of the outer peripheral portion. The temperature of the central part of the honeycomb unit 11 can be made higher than the temperature of the outer peripheral part. With the holding sealing material 20 arranged on the outer peripheral part of the honeycomb structure 10 ″, In the case where the metal tube 30 is used as an exhaust gas purifying device, according to the law of inertia, the closer to the center of the honeycomb structure 10 ″, the higher the flow rate of the exhaust gas, so the temperature tends to decrease. It is possible to suppress a decrease in temperature at the center of 10 ″. In addition, since the same voltage is applied to the four honeycomb units 11, when the honeycomb structure 10 "is used as an exhaust gas purification device, a decrease in temperature at the center of the honeycomb structure 10" can be suppressed. Therefore, the temperature of the honeycomb structure 10 ″ can be made uniform, and the deterioration of the exhaust gas purification ability can be suppressed.

  The strip electrode 13 ″ has the same configuration as the strip electrode 13 except for the shape.

  Further, the strip-like electrode 13 ″ may be extended on the outer peripheral surface that does not face the adhesive layer 12 of each honeycomb unit 11. This facilitates electrical connection to the annular conductive member.

  FIG. 8 shows an example of the exhaust gas purifying apparatus of the present invention. The exhaust gas purification apparatus 100 is obtained by canning the metal tube 30 in a state where the holding sealing material 20 is disposed on the outer peripheral portion of the honeycomb structure 10 described above. In addition, an automobile battery (not shown) is connected to the strip electrode 13 of the honeycomb structure 10. For this reason, when a voltage is applied between the four strip electrodes 13 using an automobile battery, the honeycomb structure 10 can generate heat.

  As described above, since the honeycomb structure of the present invention has a columnar shape or an elliptical column shape, the electrode is not easily disconnected. In the honeycomb structure of the present invention, the honeycomb unit has a fan-shaped or elliptical fan-shaped cross section perpendicular to the longitudinal direction, and a pair of band-shaped electrodes are formed on the outer peripheral surface that does not face the adhesive layer of the honeycomb unit. And / or extending between the honeycomb unit and the adhesive layer and / or formed between the outer peripheral surface of the honeycomb unit and the adhesive layer and having a cross section perpendicular to the longitudinal direction of the honeycomb unit. Since it is formed in a region including the center of the shape, the amount of heat generated at the center and the outer periphery can be individually adjusted.

DESCRIPTION OF SYMBOLS 10, 10 ', 10 "honeycomb structure 11 Honeycomb unit 11a Through-hole 11b Partition 12 Adhesive layer 13, 13', 13" Band electrode 20 Holding sealing material 30 Metal pipe 100 Exhaust gas purification apparatus

Claims (12)

A cylindrical or elliptical columnar honeycomb structure in which a plurality of through holes are arranged in parallel in the longitudinal direction and a plurality of honeycomb units containing conductive ceramics are bonded via an adhesive layer,
The honeycomb unit has a fan-shaped or elliptical fan-shaped cross section perpendicular to the longitudinal direction,
A pair of electrodes is formed on the outer peripheral surface of the honeycomb unit that does not face the adhesive layer, and the pair of electrodes extends between the honeycomb unit and the adhesive layer, and / or A pair of electrodes is formed between the outer peripheral surface of the honeycomb unit and the adhesive layer, and the pair of electrodes has a fan-shaped or elliptical fan-shaped center in a cross section perpendicular to the longitudinal direction of the honeycomb unit. A honeycomb structure formed in a region containing   The honeycomb structure according to claim 1, wherein the pair of electrodes are formed over the entire outer periphery of the honeycomb unit.   The honeycomb structure according to claim 1 or 2, wherein the pair of electrodes are formed at both ends in the longitudinal direction of the honeycomb unit.   The honeycomb structure according to any one of claims 1 to 3, wherein a distance between the pair of electrodes is smaller as it is closer to a center of the fan-shaped or elliptical fan-shaped.   The honeycomb structure according to any one of claims 1 to 4, wherein a central angle of the fan-shaped or elliptical fan-shaped is 90 ° or less.   The honeycomb structure according to any one of claims 1 to 5, wherein the electrode is a strip electrode having a width of 3 mm to 30 mm.   The honeycomb structure according to claim 6, wherein the distance between the strip electrodes is adjusted so that the resistance between the strip electrodes is substantially the same.   The honeycomb structure according to any one of claims 1 to 7, wherein the electrode is formed by thermal spraying or sputtering.   The honeycomb structure according to any one of claims 1 to 8, wherein a catalyst is supported on partition walls separating the plurality of through holes.   The honeycomb structure according to claim 9, wherein the catalyst is at least one selected from the group consisting of platinum, rhodium and palladium.   The honeycomb structure according to any one of claims 1 to 10, wherein the conductive ceramic includes silicon carbide.   An exhaust gas purification apparatus comprising the honeycomb structure according to any one of claims 1 to 11.

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