JP2017144405A - Honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure capable of early activating a catalyst carried on a partition wall.SOLUTION: The honeycomb structure comprises a columnar honeycomb structural part 4 which has porous partitions 1 partitioning/forming a plurality of cells 2 extending from an inlet end face 11 to an outlet end face. The honeycomb structural part 4 includes a central part 21, a boundary part 22, and a peripheral part 23 in a cross section perpendicular to the direction in which the cells 2 extend. The central part 21 includes the cells 2a located at the central part in the cross section. The boundary part 22 includes the cells 2b located so as to enclose the periphery of the central part 21. The peripheral part 23 includes the cells 2c located outside the boundary part 22. The cells 2b formed in the boundary part 22 includes both-ends sealed cells 32b having openings provided at both ends and sealed with sealing parts 5.SELECTED DRAWING: Figure 2A

Description

  The present invention relates to a honeycomb structure. More specifically, the present invention relates to a honeycomb structure that can activate a catalyst at an early stage when used as a catalyst carrier for supporting a catalyst for exhaust gas purification.

  In recent years, awareness of environmental issues has increased throughout society, and in the technical field where fuel is generated by burning fuel, various technologies for removing harmful components such as nitrogen oxides from exhaust gas generated during the combustion of fuel Has been developed.

  2. Description of the Related Art Conventionally, a honeycomb structure carrying a catalyst is used for purification treatment of harmful substances such as HC, CO and NOx contained in exhaust gas discharged from an engine such as an automobile. As described above, when the exhaust gas is treated with the catalyst supported on the honeycomb structure, it is necessary to raise the temperature of the catalyst to its activation temperature. However, when the engine is started, the catalyst has not reached the activation temperature. There was a problem that it was not purified.

  As described above, in order to purify exhaust gas immediately after starting an internal combustion engine such as an engine, it is necessary to activate the catalyst supported on the honeycomb structure at an early stage, and various studies have been made. For example, a technique is disclosed in which bengara, titanium oxide, zinc oxide, or silicon carbide is blended with inorganic fibers that are main raw materials of a holding material interposed in a gap between a catalyst carrier and a casing (for example, patents) Reference 1). The holding material composed of the raw materials as described above is said to have an excellent heat insulating effect while maintaining the holding performance and the sealing performance.

  Further, the outermost peripheral cell of the cell structure part and a predetermined number of cells located inward from the outer peripheral cell are sealed by the inner peripheral surface of the outer wall at the end and / or intermediate part of at least one of the central axes. A honeycomb structure constituting a cell is disclosed (for example, see Patent Document 2). Since such a honeycomb structure forms the outer wall of the honeycomb structure and seals the end face of the cell at the same time, it is not necessary to separately perform a step of sealing the end face of the cell. For this reason, such a honeycomb structure is excellent in productivity. In addition, since such a honeycomb structure can suppress the escape of heat to the outer wall when the cell structure is heated, the temperature rise time of the cell structure from the start of the engine is shortened, and the catalyst activity is shortened in a short time. Can be high.

  Further, as a holding sealing material for an exhaust gas purification apparatus, a mat-like holding sealing material made of inorganic fibers, in which a heater is disposed on any main surface of the mat constituting the holding sealing material, is disclosed. (For example, see Patent Document 3). When the exhaust gas treating body around which the holding sealing material is wound is housed in a casing and used as an exhaust gas purification device, the holding sealing material includes a heater, and therefore the exhaust gas treating body can be overheated at an arbitrary timing. . Therefore, it is said that the exhaust gas treating body immediately after starting an internal combustion engine such as an engine can be quickly heated to exert its catalytic function.

JP 2003-293753 A JP 2003-284923 A JP 2014-190191 A

  According to the holding material described in Patent Document 1, the heat insulation effect can be enhanced. However, since such a holding material is used in a compressed state in the gap between the catalyst carrier and the casing, the holding material itself is thinned, and the heat insulation effect is not necessarily increased. There has been a problem that a sufficient heat insulating effect may not be exhibited.

  The honeycomb structure described in Patent Document 2 is obtained by sealing the end face of a cell when forming an outer wall. In such a honeycomb structure, since the region for sealing the cells is limited to the outer periphery of the cell structure portion, the heat insulation effect is not necessarily increased, and the sufficient heat insulation effect may not be exhibited. was there.

  In the technique described in Patent Document 3, a holding sealing material provided with a heater is wound around an exhaust gas treatment body, and the heater is heated to rapidly increase the temperature of the exhaust gas treatment body. In such a technique, it is necessary to supply electricity to the holding sealing material in order to heat the heater, and in order to treat exhaust gas discharged from an engine such as an automobile, there is an adverse effect on fuel consumption. There was an inevitable problem. In addition, the holding sealing material described in Patent Document 3 requires a mechanism for controlling the heater, which increases the manufacturing cost.

  The present invention has been made in view of such problems of the prior art. The present invention provides a honeycomb structure capable of activating a catalyst at an early stage when used as a catalyst carrier for supporting a catalyst for exhaust gas purification.

  According to the present invention, the following honeycomb structure is provided.

[1] A columnar honeycomb structure part having a porous partition wall defining a plurality of cells serving as fluid flow paths extending from the inflow end face to the outflow end face is provided, and the honeycomb structure part is orthogonal to the cell extending direction. The cross section includes a central portion, a boundary portion, and an outer peripheral portion, and the central portion is a portion including the cell existing in the central portion of the cross section, and the boundary portion surrounds an outer periphery of the central portion. The outer peripheral part is a part including the cells existing further outside the boundary part, and the cells formed in the boundary part are located on the inflow end face side. A honeycomb structure including a both-end sealed cell in which a plugging portion for sealing an opening of the cell is disposed at an end portion and an end portion on the outflow end face side.

[2] The cell formed on the outermost periphery of the outer peripheral portion includes an incomplete cell in which a part of the partition wall defining the periphery of the cell is missing, and the honeycomb structure portion covers the outer peripheral portion. The honeycomb structure according to the above [1], which has an outer peripheral coating layer disposed on the surface.

[3] In the cell formed on the outermost periphery of the outer peripheral portion, plugging portions for sealing the opening of the cell are disposed at the end portion on the inflow end surface side and the end portion on the outflow end surface side. The honeycomb structure according to [1] or [2], including the outermost peripheral sealed cells.

[4] The outer peripheral portion includes a first outer peripheral portion including the cells existing so as to surround the outer periphery of the boundary portion, and the cells existing so as to further surround the outer periphery of the first outer peripheral portion. Including the outer peripheral portion inner boundary portion and the second outer peripheral portion including the cells existing further outside the outer peripheral portion inner boundary portion, wherein the cells formed in the outer peripheral portion inner boundary portion are arranged on the inflow end face side. Any one of the above [1] to [3], including an outer peripheral end both-end sealed cell in which a plugging portion for sealing the opening of the cell is disposed at an end portion and an end portion on the outflow end face side The honeycomb structure according to 1.

[5] The honeycomb structure according to any one of [1] to [4], wherein an average pore diameter of the partition walls of the honeycomb structure portion is 5 μm or more and 200 μm or less.

[6] The honeycomb structure according to any one of [1] to [5], wherein the partition wall has a porosity of 25% or more and 70% or less.

[7] The honeycomb structure according to any one of [1] to [6], wherein a thickness of the partition wall of the honeycomb structure portion is 0.038 mm or more and 0.500 mm or less.

[8] The honeycomb structure according to any one of [1] to [7], wherein the honeycomb structure has a cell density of 15 cells / cm ² or more and 233 cells / cm ² or less.

[9] The honeycomb structure according to any one of [1] to [8], wherein the honeycomb structure portion has a cell density in the central portion different from a cell density in the outer peripheral portion.

[10] The honeycomb structure according to [9], wherein the honeycomb structure portion has a cell density in the central portion larger than a cell density in the outer peripheral portion.

[11] The group of the honeycomb structure portion is a group of silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. The honeycomb structure according to any one of [1] to [10], wherein the honeycomb structure is made of a material including at least one kind of ceramics selected from the above.

[12] The honeycomb structure according to any one of [1] to [11], which is used for exhaust gas purification of an internal combustion engine.

[13] The exhaust gas purifying catalyst is supported on at least one of the surface of the partition walls and the pores of the partition walls of the honeycomb structure part, according to any one of the above [1] to [12]. Honeycomb structure.

  The honeycomb structure of the present invention includes a columnar honeycomb structure portion, and the honeycomb structure portion includes a central portion, a boundary portion, and an outer peripheral portion in a cross section orthogonal to the cell extending direction. And the cell formed in the boundary part includes a both-end sealed cell in which plugging portions for sealing the opening of the cell are disposed at the end portion on the inflow end surface side and the end portion on the outflow end surface side. Therefore, this both-end-sealed cell becomes a heat insulating layer for the central portion. For this reason, when the honeycomb structure of the present invention is used as a catalyst carrier for supporting a catalyst for exhaust gas purification, the catalyst can be activated at an early stage. That is, the honeycomb structure of the present invention has excellent light-off performance at the time of engine cold start.

  Further, the honeycomb structure of the present invention further includes a plug in which cells formed on the outermost periphery of the outer peripheral portion seal the opening of the cell at the end portion on the inflow end surface side and the end portion on the outflow end surface side. An outermost peripheral both-end sealed cell in which a stop portion is disposed may be included. In such a honeycomb structure, the outermost peripheral sealed cells serve as a heat insulating layer for the entire honeycomb structure, and the light-off performance at the time of engine cold start is excellent.

1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. Fig. 2 is a plan view schematically showing an inflow end surface of the honeycomb structure shown in Fig. 1. Fig. 2 is a plan view schematically showing an outflow end surface of the honeycomb structure shown in Fig. 1. It is sectional drawing which shows typically the X-X 'cross section of FIG. 2A. It is a top view which shows typically the inflow end surface of other embodiment of the honeycomb structure of this invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. It is a schematic diagram which shows the state which inserted the honeycomb structure in the can in the thermal cycle test of an Example. It is a schematic diagram which shows the apparatus used in the HC purification test of an Example.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. Therefore, it should be understood that appropriate modifications and improvements can be made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

(1) Honeycomb structure:
As shown in FIGS. 1 to 3, one embodiment of the honeycomb structure of the present invention is a honeycomb structure 100 including a honeycomb structure portion 4 having porous partition walls 1. The porous partition wall 1 partitions and forms a plurality of cells 2 serving as fluid flow paths extending from the inflow end surface 11 to the outflow end surface 12. The honeycomb structure portion 4 has a columnar shape having both the inflow end surface 11 and the outflow end surface 12 as both end surfaces.

  The honeycomb structure part 4 shown in FIGS. 1 to 3 has an outer peripheral wall 3 disposed so as to surround the partition walls 1 that define the cells 2. Here, FIG. 1 is a perspective view schematically showing one embodiment of the honeycomb structure of the present invention. FIG. 2A is a plan view schematically showing an inflow end surface of the honeycomb structure shown in FIG. FIG. 2B is a plan view schematically showing the outflow end face of the honeycomb structure shown in FIG. 1. 3A is a cross-sectional view schematically showing the X-X ′ cross section of FIG. 2.

  The honeycomb structure part 4 constituting the honeycomb structure 100 includes a central part 21, a boundary part 22, and an outer peripheral part 23 in a cross section perpendicular to the extending direction of the cells 2. Here, the central portion 21 is a portion including at least one cell 2a existing in the central portion of the cross section. The boundary part 22 is a part including the cell 2b that exists so as to surround the outer periphery of the central part 21. The outer peripheral part 23 is a part including the cell 2 c existing further outside the boundary part 22. And the cell 2b formed in the boundary part 22 has the plugging part 5 which seals the opening part of the cell 2 at the end part on the inflow end face 11 side and the end part on the outflow end face 12 side. Both-end sealed cells 32b are included. Hereinafter, unless otherwise specified, “the cross section of the honeycomb structure” means a cross section of the honeycomb structure portion orthogonal to the cell 2 extending direction.

  In the honeycomb structure 100 of the present embodiment, the both-end-sealed cells 32b exist so as to surround the outer periphery of the central portion 21, so that the both-end-sealed cells 32b serve as a heat insulating layer for the central portion 21. For this reason, when the honeycomb structure 100 of the present embodiment is used as a catalyst carrier for supporting a catalyst for exhaust gas purification, the catalyst can be activated at an early stage. That is, the honeycomb structure 100 of the present embodiment has excellent light-off performance at the time of engine cold start. The light-off performance means a temperature characteristic that exhibits the purification performance of the catalyst supported on the honeycomb structure 100.

  The cells 2a existing in the central portion 21 are all open at both ends, in which all the cells 2a are not provided with the plugging portions 5 at the end portion on the inflow end surface 11 side and the end portion on the outflow end surface 12 side. It is an open cell 32a.

  The central portion 21 is a portion including at least one cell 2 present in the central portion of the cross section, and is preferably in a range corresponding to 5 to 80% with respect to the cross sectional area of the honeycomb structure portion 4, A range corresponding to 10 to 55% is more preferable. With this configuration, the light-off performance at the central portion 21 of the honeycomb structure portion 4 becomes better.

  The boundary part 22 is a part including the cell 2b that exists so as to surround the outer periphery of the central part 21. In the honeycomb structure 100 shown in FIGS. 1 to 3, all the cells 2b existing in the boundary portion 22 are both-end sealed cells 32b. The “cell 2b existing so as to surround the outer periphery of the central portion 21” includes at least all of the cells 2 adjacent to the cell 2a existing in the central portion 21 and is further adjacent to the adjacent cell 2 2 may be included.

  It is preferable that 10% or more of the cells 2b existing in the boundary portion 22 are 10% or more of the total number of cells 2b adjacent to the cell 2a existing in the central portion 21 are both-end sealed cells 32b. For example, in the honeycomb structure 101 shown in FIG. 4, the cells 2b existing in the boundary portion 22 surrounding the outer periphery of the central portion 21 of the honeycomb structure portion 4 include both-end sealed cells 32b and both-end open cells 32e. Yes. Here, both-end open cells 32e of the boundary portion 22 are cells that are open at both ends, where the plugging portions 5 are not provided at the end portion on the inflow end surface 11 side and the end portion on the outflow end surface (not shown) side. It means 2b. Further, in the honeycomb structure 102 shown in FIG. 5, the cells 2b existing in the boundary portion 22 surrounding the outer periphery of the central portion 21 of the honeycomb structure portion 4 include both-end sealed cells 32b and both-end open cells 32e. Yes. In the honeycomb structure 102 shown in FIG. 5, the both-end sealed cells 32b and the both-end open cells 32e are alternately arranged at the boundary portion 22 so as to surround the outer periphery of the central portion 21. ing.

  Here, FIG. 4 is a plan view schematically showing an inflow end surface of another embodiment of the honeycomb structure of the present invention, and FIG. 5 is an inflow end surface of still another embodiment of the honeycomb structure of the present invention. It is a top view which shows typically. 4 and 5, the same components as those in the honeycomb structure 100 shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof may be omitted.

  Here, in the inflow end surface and the outflow end surface of the honeycomb structure portion, when the shape of the cell opening is a polygon, each of the plurality of cells is adjacent to each other such that the apexes of the polygon face each other. There are two types of adjacency methods: adjoining so as to share one side of the square. Hereinafter, in this specification, two cells may be adjacent to each other such that the vertexes of the polygons face each other, and the two cells may be referred to as “adjacent at a point”. Two cells may be adjacent to each other so as to share one side of the polygon, and two cells may be “adjacent by sides”.

  The cell 2b existing at the boundary part 22 may be a set of cells adjacent at a point, a set of cells adjacent at a side, or adjacent at a side to a cell adjacent at a point. It may be an aggregate in which cells are mixed.

  The both-end sealed cells present at the boundary may be two-end sealed cells adjacent to each other at points or sides, and sandwich both-end open cells 32e as shown in FIGS. It may exist. When the two sealed cells at both ends are adjacent to each other at the sides, the heat insulating effect at the center is further increased. When the two sealing cells at both ends are adjacent to each other at a point, the number of sealing cells at both ends is geometrically smaller than when adjacent to each other at the side, so that the pressure loss of the honeycomb structure 100 tends to be small. . For example, in the honeycomb structure 103 illustrated in FIG. 6, the both end sealed cells 32b are adjacent to each other at a part of the boundary part 22 and the both end sealed cells 32b are dots at the other part of the boundary part 22. Adjacent. On the other hand, in the honeycomb structure 104 shown in FIG. 7, the sealing cells 32b at both ends are adjacent to each other in the entire boundary portion 22. When the honeycomb structure 103 shown in FIG. 6 is compared with the honeycomb structure 104 shown in FIG. 7, the honeycomb structure 104 shown in FIG. 7 has a larger number of both-end-sealed cells 32 b in the boundary portion 22. 6 and 7, the number of cells 2 formed in the honeycomb structure portion 4 is the same, and the size of the central portion 21 is also the same.

  Here, FIGS. 6 and 7 are plan views schematically showing the inflow end face of still another embodiment of the honeycomb structure of the present invention. 6 and 7, the same components as those in the honeycomb structure 100 shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof may be omitted.

  The boundary portion is an annular region formed by a portion including cells that surround the outer periphery of the central portion. The width of the boundary portion in the cross section of the honeycomb structure portion is preferably 0.5 to 20%, more preferably 0.9 to 18% of the length of the outer diameter of the cross section. The “outer diameter of the cross section” is the length from one point on the outer periphery of the cross section of the honeycomb structure portion to the other point on the outer periphery of the cross section through the center of the cross section. For example, when the cross-sectional shape of the honeycomb structure portion is a circle, the “outer diameter of the cross section” is the diameter of the circle. When the width of the boundary portion is less than 0.5% of the length of the outer diameter of the cross section, the heat insulating effect at the center portion may not be sufficiently exhibited. Here, the term “less than 0.5%” includes, for example, a case where the plugged portion is disposed only in a part of the opening of one cell and the opening of the cell is not completely plugged. Is intended. On the other hand, when the width of the boundary portion exceeds 20% of the length of the outer diameter of the cross section, the pressure loss of the honeycomb structure may increase.

  The shape of the boundary portion in the cross section of the honeycomb structure portion is not particularly limited. In the honeycomb structure 100 shown in FIGS. 1 to 3, the shape of the boundary portion 22 is a circular ring shape that is close to the similar shape of the outer peripheral shape of the honeycomb structure portion 4. In addition, since the boundary part 22 is an area including the polygonal cell 2 partitioned by the partition wall 1, as shown in FIGS. 2A and 2b, the circular ring does not exhibit a strict circular shape. There is. Regarding the shape of the boundary portion described below, the shape of the boundary portion does not need to exhibit the shape to be described strictly, and includes all shapes similar to the shape.

  Hereinafter, another example of the shape of the boundary portion in the honeycomb structure of the present embodiment will be described. In the honeycomb structure 105 shown in FIG. 8, the shape of the boundary portion 22 is an elliptical ring shape. In the honeycomb structure 106 shown in FIG. 9, the boundary portion 22 has a quadrangular annular shape. In the honeycomb structure 107 shown in FIG. 10, the shape of the boundary portion 22 is a rectangular ring shape. In the honeycomb structure 108 shown in FIG. 11, the shape of the boundary portion 22 is a triangular ring shape. In the honeycomb structure 109 shown in FIG. 12, the boundary portion 22 has a pentagonal annular shape. Thus, the shape of the boundary part in the honeycomb structure of the present embodiment can take various shapes. 8 to 12 show an example in which all the cells 2b existing at the boundary portion 22 are both-end sealed cells 32b, but a part of the cells 2b existing at the boundary portion 22 is Both-end open cells 32e as shown in FIGS. 4 and 5 may be included. Further, the method of adjoining the both-end sealed cells 32b in FIGS. 8 to 12 is not limited to the illustrated example. For example, in the illustration, a portion adjacent by a point is adjacent by a side. It may be changed or vice versa.

  Here, FIGS. 8 to 12 are plan views schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. 8 to 12, the same components as those in the honeycomb structure 100 shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof may be omitted.

  There is no restriction | limiting in particular about the length from the inflow end surface and outflow end surface of a plugging part in a both ends sealing cell. For example, the ratio of the length of the plugged portion from each end face to the length from the inflow end face to the outflow end face of the both-end sealed cell is preferably 1 to 30%, and preferably 2 to 20%. Is more preferable, and 5 to 10% is particularly preferable. If the ratio of the length of the plugged portion from each end face is less than 1%, the plugged portion may easily fall off from the both-end sealed cells. On the other hand, if the ratio of the length of the plugged portion from each end surface exceeds 30%, the honeycomb structure portion may be easily damaged due to thermal expansion of the plugged portion. In addition, the volume of the plugged portion in the both-end sealed cell is increased, and the heat capacity of the both-end sealed cell is increased, so that the heat of the heated central portion may be taken away by the both-end sealed cell. . Therefore, it is preferable that both ends of the sealing cell are hollow except for the plugged portions at both ends.

  As shown in FIGS. 1 to 3, the outer peripheral portion 23 is a portion including the cell 2 c existing further outside the boundary portion 22. In the honeycomb structure 100 of the present embodiment, the cell 2c formed on the outermost periphery of the outer peripheral portion 23 seals the opening of the cell 2c at the end on the inflow end surface 11 side and the end on the outflow end surface 12 side. It is preferable that the outermost peripheral both-end sealed cell 32d provided with the plugging portion 5 to be included is included. In the honeycomb structure 100 shown in FIG. 1 to FIG. 3, among the cells 2 c existing in the outer peripheral portion 23, the cells 2 c other than the outermost peripheral both-end sealed cells 32 d are both open-ended cells 32 c that are open at both ends. It has become.

  The honeycomb structure 100 of the present embodiment has the highest heat insulation effect in the central portion 21 and is particularly excellent in light-off performance at the time of engine cold start of the central portion 21. When used as a catalyst carrier for supporting a catalyst for purifying exhaust gas, the central portion 21 has a high exhaust gas flow rate, and the light-off performance of the central portion 21 is further improved to effectively improve the purification performance of the catalyst. It can be demonstrated. Further, in the honeycomb structure 100 of the present embodiment, when the outermost peripheral both-end sealed cells 32d exist on the outermost periphery of the outer peripheral portion 23, the outermost peripheral both-end sealed cells 32d serve as the heat insulating layer of the entire honeycomb structure 4. It becomes. For this reason, the honeycomb structure 100 in which the outermost peripheral both-end sealed cells 32d exist in the outermost periphery of the outer peripheral portion 23 is inferior to the central portion 21, but the outer peripheral portion 23 also has the light-off performance at the time of engine cold start. It can be improved effectively.

  In the outer peripheral part 23, it is preferable that 10% or more of the cells 2c of the total number of the cells 2c formed on the outermost peripheral part of the outer peripheral part 23 are the outermost peripheral sealed cells 32d. Here, the cells 2 c formed on the outermost periphery of the outer peripheral portion 23 include incomplete cells in which the periphery of the cell 2 c is partitioned by the outer peripheral wall 3 of the honeycomb structure portion 4. Further, the outermost peripheral sealing cell 32d may be constituted by not only the cell 2c formed on the outermost periphery of the outer peripheral portion 23 but also another cell 2c adjacent to the cell 2c formed on the outermost periphery on the side. Good. For example, the cell 2c that can be the outermost peripheral sealed cell 32d is adjacent to the cell 2c formed on the outermost periphery and the sides of the cells 2c formed on the outermost periphery from the two or less sides toward the center of the honeycomb structure portion. The cell 2c is preferable. By comprising in this way, the heat insulation effect of the honeycomb structure part 4 can be improved, and the light-off performance at the time of engine cold start can be improved.

  The honeycomb structure part 4 shown in FIGS. 1 to 3 has an outer peripheral wall 3 disposed so as to surround the partition walls 1 that define the cells 2. The honeycomb structure part 4 configured as described above can be manufactured by, for example, drying and firing a formed body obtained by forming a forming raw material by extrusion molding or the like. That is, the honeycomb structure portion 4 shown in FIGS. 1 to 3 has a single structure with no boundary between the porous partition wall 1 and the outer peripheral wall 3 and is integrally formed.

  In the honeycomb structure of the present embodiment, although illustration is omitted, the honeycomb structure portion may have an outer peripheral coat layer disposed so as to cover the outer periphery thereof. For example, after the outer peripheral wall 3 of the honeycomb structure part 4 as shown in FIGS. 1 to 3 is once removed by grinding or the like, an outer peripheral coating material is applied to the outer periphery of the honeycomb structure part from which the outer peripheral wall has been removed, You may arrange | position the outer periphery coating layer which covers the outer periphery of a honeycomb structure part.

  As described above, when the outer peripheral wall of the honeycomb structure portion is removed by grinding or the like, the outermost periphery of the honeycomb structure portion includes incomplete cells in which a part of the partition walls that partition the cell is missing. Will be. Therefore, when the outer peripheral coat layer is disposed on the honeycomb structure portion having the incomplete cells, the outer peripheral coat layer may enter at least a part of the incomplete cells. In such a honeycomb structure part, the incomplete cell which the outer periphery coating layer penetrate | invaded can be utilized as a heat insulation layer of a honeycomb structure part. Furthermore, in addition to the incomplete cells into which the outer peripheral coat layer has entered, the outermost peripheral both-end sealed cells can be further present on the outermost periphery of the outer peripheral portion of the honeycomb structure portion. In this case, the cell existing one inside from the incomplete cell into which the outer peripheral coat layer has entered may be the outermost peripheral cell of the honeycomb structure portion. The presence of the outermost peripheral sealed cells at the outer peripheral portion of the honeycomb structure portion can further improve the heat insulating effect of the entire honeycomb structure portion.

  Further, the honeycomb structure of the present embodiment may be configured as a honeycomb structure 110 shown in FIG. In the honeycomb structure 110 shown in FIG. 13, the outer peripheral portion 23 includes a first outer peripheral portion 123, an outer peripheral inner boundary portion 223, and a second outer peripheral portion 323. Here, FIG. 13 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention.

  The first outer peripheral portion 123 is a portion including the cell 2 c that exists so as to surround the outer periphery of the boundary portion 22. In the first outer peripheral portion 123, all the cells 2c are both-end open cells 32c.

  The outer peripheral part inner boundary part 223 is a part including the cell 2 c that exists so as to further surround the outer periphery of the first outer peripheral part 123. The cell 2c formed in the outer peripheral inner boundary 223 has a plugging portion 5 for sealing the opening of the cell 2c at the end on the inflow end surface 11 side and the end on the outflow end surface (not shown) side. The outer peripheral portion both-end sealing cell 32f provided is included. In addition, the outer peripheral part inner boundary part 223 may be comprised only by the outer peripheral part both ends sealing cell 32f, and may contain the both-ends open cell (not shown) other than the outer peripheral part both ends sealing cell 32f. .

  The second outer peripheral portion 323 is a portion including the cell 2 c existing further outside the outer peripheral inner boundary portion 223. In the honeycomb structure 110, the second outer peripheral portion 323 has both end open cells 32 c that are open at both ends and the outermost peripheral both end sealed cells 32 d.

  In the honeycomb structure 110 shown in FIG. 13, the boundary portion 22 including both end-sealed cells 32b, the outer periphery inner boundary portion 223 including the outer periphery both-end sealed cells 32f, and the outer periphery including the outermost peripheral both-end sealed cells 32d. This is a triple heat insulation structure with the outermost periphery of 23.

  The outer peripheral part inner boundary part 223 can adopt the same configuration as the boundary part 22 (for example, see FIG. 2A) in the honeycomb structure part 4 described so far. Also in the honeycomb structure 110 shown in FIG. 13, the honeycomb structure portion 4 is large and can be classified into a central portion 21, a boundary portion 22, and an outer peripheral portion 23. Therefore, the outer peripheral part inner boundary part 223 is a heat insulating layer for expressing the same effect as the boundary part 22 in the outer peripheral part 23. The outer peripheral part inner boundary part 223 can adopt the same configuration as the boundary part 22 described so far (for example, see FIG. 2A). For example, the outer peripheral portion inner boundary portion 223 may be constituted only by the outer peripheral portion both-end sealed cell 32f, or may include both-end open cells (not shown) in addition to the outer peripheral portion both-end sealed cell 32f. . The same configuration as that of the boundary portion 22 described so far can also be adopted for the width of the inner peripheral portion 223 and the like.

  Moreover, although illustration is abbreviate | omitted, for example, it has the 2nd outer peripheral part inner boundary part containing an outer peripheral part both ends sealing cell on the outer side of a 2nd outer peripheral part, and further of this 2nd outer peripheral part inner boundary part You may have a 3rd outer peripheral part on the outer side. Thus, it may be a four or more heat insulation structure by having two or more boundary portions in the outer peripheral portion in the outer peripheral portion.

  The average pore diameter of the partition walls of the honeycomb structure portion is preferably 5 μm or more and 200 μm or less, and more preferably 10 μm or more and 100 μm or less. When the average pore diameter of the partition walls is less than 5 μm, the light-off performance of the catalyst component in the catalyst may be deteriorated. When the average pore diameter of the partition wall exceeds 200 μm, the strength of the partition wall may decrease.

  The porosity of the partition walls of the honeycomb structure portion is preferably 25% or more and 70% or less, and more preferably 35% or more and 65% or less. When the porosity is less than 25%, the partition walls themselves of the honeycomb structure part are dense, which is not preferable because it is difficult to support the catalyst on the surface of the partition walls of the honeycomb structure part. On the other hand, if the porosity exceeds 70%, the strength of the honeycomb structure portion is not preferable. Let the average pore diameter and porosity of a partition be the value measured by the mercury porosimeter (Mercury porosimeter). An example of the mercury porosimeter is Autopore 9500 (trade name) manufactured by Micromeritics.

  The partition wall thickness of the honeycomb structure portion is preferably 0.038 mm or more and 0.500 mm or less, and more preferably 0.050 mm or more and 0.300 mm or less. In the honeycomb structure of the present embodiment, the thickness of the partition walls as described above is preferable in terms of suppressing damage to the honeycomb structure and suppressing pressure loss. For example, if the partition wall thickness is less than 0.038 mm, the partition wall may be easily damaged. When the partition wall thickness exceeds 0.500 mm, the pressure loss of the honeycomb structure may increase. The thickness of the partition wall is a value measured by observing the shape of the cross section of the honeycomb structure with a scanning electron microscope (SEM).

The cell density of the honeycomb structure portion is preferably 15 cells / cm ² or more and 233 cells / cm ² or less, and more preferably 30 cells / cm ² or more and 186 cells / cm ² or less. When the cell density is less than 15 cells / cm ² , the honeycomb structure may have insufficient strength. When it exceeds 233 pieces / cm ² , the pressure loss of the honeycomb structure increases, and when the catalyst is loaded, the loaded catalyst may cause clogging of the cell.

  Further, the honeycomb structure portion may have a cell density in the central portion and a cell density in the outer peripheral portion different from each other. Moreover, it is preferable that the cell density of the center part of the honeycomb structure part is larger than the cell density of the outer peripheral part. In the honeycomb structure portion, the cell density at the center may be smaller than the cell density at the outer periphery.

  The partition walls of the honeycomb structure portion are preferably made of a material containing ceramics. Furthermore, the material constituting the partition wall preferably contains at least one kind of ceramic selected from the following “material group”. The “material group” is a group including silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate.

  The shape of the cell in the cross section orthogonal to the cell extending direction is not particularly limited. For example, “a polygon such as a triangle, a quadrangle, a pentagon, a hexagon, a heptagon, an octagon”, a circle, an ellipse, and the like can be given. Moreover, the aspect which combined several of these shapes is also a preferable aspect. Moreover, in a square, a square or a rectangle is preferable. Further, the shape of the cell may be different between the central portion and the outer peripheral portion of the honeycomb structure portion. The shape of the cell at the boundary may be the same as or different from the shape of the cell at the center or the outer periphery.

  There is no particular limitation on the overall shape of the honeycomb structure. For example, the overall shape of the honeycomb structure may be a columnar shape such as a circular shape, an elliptical shape, or a polygonal shape of the inflow end surface and the outflow end surface. The shape of the inflow end surface and the outflow end surface may be an indeterminate column shape. The size of the honeycomb structure is not particularly limited, but the length from the inflow end surface to the outflow end surface is preferably 25 to 350 mm. Moreover, when the whole shape of a honeycomb structure is a column shape, it is preferable that the diameter of each end surface is 30-500 mm.

  The plugging portion is preferably made of a material containing ceramics. The material constituting the plugging portion preferably contains at least one kind of ceramics selected from the “material group” suitable for the material constituting the partition wall described above.

  The honeycomb structure of the present embodiment can be suitably used as a member for exhaust gas purification of an internal combustion engine. In particular, it can be suitably used as a catalyst carrier for supporting a catalyst for exhaust gas purification. The honeycomb structure of the present embodiment may be one in which a catalyst for exhaust gas purification is supported on at least one of the surface of the partition walls of the honeycomb structure portion and the pores of the partition walls.

  The supported amount of the catalyst is preferably 10 to 400 g / liter, and more preferably 50 to 200 g / liter. If the supported amount of the catalyst is less than 10 g / liter, the exhaust gas purification performance may be lowered. When the amount of the catalyst supported is more than 400 g / liter, the pressure loss may increase. Here, the catalyst loading (g / liter) is a value obtained by dividing the total mass of the catalyst supported on the surfaces of the partition walls and the pores by the volume of the honeycomb structure. The volume of the honeycomb structure means the total volume of partition walls, plugging portions, and cell spaces. That is, when the entire honeycomb structure has a columnar shape, the volume of the columnar shape is the volume of the honeycomb structure.

  Examples of the catalyst include conventionally known catalysts for automobile exhaust gas. For example, “three-way catalyst based on a noble metal such as Pt, Pd, Rh”, oxidation catalyst, deodorizing catalyst, “base metal catalyst such as Mn, Fe, Cu” and the like can be mentioned.

(2) Manufacturing method of honeycomb structure:
Next, the manufacturing method of the honeycomb structure of the present invention will be described.

  When manufacturing the honeycomb structure of the present invention, first, a forming raw material for forming the honeycomb formed body is prepared. The forming raw material preferably contains a ceramic raw material.

As the ceramic raw material contained in the forming raw material, for example, at least one kind of ceramic selected from the following “raw material group” is preferable. “Raw material group” includes silicon carbide, silicon-silicon carbide based composite material, cordierite forming raw material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. A group. By using these raw materials, a honeycomb structure excellent in strength and heat resistance can be obtained. The cordierite forming raw material is a ceramic raw material blended so as to have a chemical composition that falls within a range of 42 to 56% by mass of silica, 30 to 45% by mass of alumina, and 12 to 16% by mass of magnesia. And the cordierite-forming raw material is fired to become cordierite. Examples of the raw material component serving as the silica source include quartz and fused silica. As a raw material component used as an alumina source, since there are few impurities, it is preferable to use at least one of aluminum oxide and aluminum hydroxide. Examples of the raw material component that becomes a magnesia source include talc and magnesite. Talc as a magnesia source preferably has an average particle size of 10 to 30 μm. Further, the magnesia source component may contain Fe ₂ O ₃ , CaO, Na ₂ O, K ₂ O and the like as impurities.

  The forming raw material is preferably prepared by mixing the ceramic raw material with a pore former, a binder, a dispersant, a surfactant, a dispersion medium and the like.

  Examples of the pore former include graphite, wheat flour, starch, foamed resin, water-absorbing polymer and the like. Examples of the pore former include synthetic resins such as phenol resin, polymethyl methacrylate, polyethylene, and polyethylene terephthalate. These synthetic resins may be hollow particles or solid particles having no hollow part. The added amount of the pore former is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  Examples of the binder include hydroxypropyl methylcellulose, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. It is preferable that the addition amount of a binder is 1-10 mass parts with respect to 100 mass parts of ceramic raw materials.

  Examples of the dispersant include dextrin and polyalcohol.

  Examples of the surfactant include ethylene glycol and fatty acid soap. The addition amount of the surfactant is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  As the dispersion medium, water is preferable. The amount of the dispersion medium is preferably 30 to 150 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  When forming a honeycomb formed body using a forming raw material, it is preferable to first knead the forming raw material into a kneaded material, and shape the obtained kneaded material into a honeycomb shape.

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

  The method for forming a kneaded clay to form a honeycomb formed body is not particularly limited, and a molding method such as an extrusion molding method, an injection molding method, or a press molding method can be used. Since continuous molding is easy and, for example, cordierite crystals can be oriented, it is preferable to employ an extrusion molding method. The extrusion molding method can be performed using an apparatus such as a vacuum kneader, a ram type extruder, a twin screw continuous extruder or the like. Moreover, it is preferable to perform extrusion molding by attaching a die that becomes a honeycomb molded body having a desired partition wall thickness, cell pitch, cell shape and the like to an apparatus used for extrusion molding. As the material of the die, stainless steel, cemented carbide, etc., which are difficult to wear, are preferable.

  It is preferable to dry the obtained honeycomb formed body after forming the honeycomb formed body. The drying method is not particularly limited, and examples thereof include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying. Among these, since the entire honeycomb formed body can be dried quickly and uniformly, it is preferable to perform dielectric drying, microwave drying, or hot air drying alone or in combination. Further, the drying conditions can be appropriately determined depending on the drying method.

  The plugging portion is preferably formed of ceramics having excellent heat resistance and corrosion resistance, like the honeycomb formed body. As the ceramic for forming the plugged portion, cordierite can be cited as a preferred example in consideration of heat insulation and thermal expansion. The method for forming the plugged portion in the opening of a predetermined cell can be performed in accordance with a conventionally known method for manufacturing a honeycomb filter using a honeycomb structure. However, when the honeycomb structure of the present invention is manufactured, plugged portions are formed at both ends of the cells which are the boundary portions of the honeycomb structure portion.

  The following method can be mentioned as an example of the method of forming a plugging part. First, a film is attached to one end face of the dried honeycomb formed body. Next, a hole is opened with, for example, a laser at a size and a position that match the shape of the plugged portion to be formed of the attached film. Next, the end face of the honeycomb formed body is dipped in a plugging slurry obtained by slurrying a material to be a plugging portion with the film attached. By doing in this way, the plugging slurry is filled in the cells to be plugged through the holes formed in the film. As for the other end face of the honeycomb formed body, the plugging slurry is filled in the cells to be plugged in the same manner as described above. After filling the plugging slurry, the honeycomb formed body may be dried again.

  Next, the honeycomb formed body is fully fired to produce a honeycomb structure. “Main firing” means an operation for sintering and densifying the forming raw material constituting the honeycomb formed body to ensure a predetermined strength.

  In addition, it is preferable to calcine the honeycomb molded body before the main firing of the honeycomb molded body. The calcination is performed for degreasing, and the method is not particularly limited, and it is sufficient that organic substances such as a binder, a dispersant, and a pore former in the honeycomb formed body can be removed. Generally, the combustion temperature of an organic binder is about 100-300 degreeC. The combustion temperature of the pore former varies depending on the type, but is about 200 to 1000 ° C. Therefore, it is preferable to heat at about 200 to 1000 ° C. for about 3 to 100 hours in an oxidizing atmosphere as a condition for calcination.

  Since the firing conditions in the main firing differ depending on the type of the forming raw material, appropriate conditions may be selected according to the type. Here, the firing conditions are various conditions for firing such as firing temperature, firing time, firing atmosphere and the like. For example, when a cordierite forming raw material is used, the firing maximum temperature is preferably 1410 to 1440 ° C. In addition, the maximum temperature holding time during firing is preferably 3 to 15 hours.

  As described above, the honeycomb structure of the present invention can be manufactured. Note that a catalyst may be supported on the manufactured honeycomb structure.

  There are no particular restrictions on the catalyst loading method. For example, the catalyst can be supported on the honeycomb structure according to a method used in a conventionally known method for manufacturing a honeycomb structure. As an example, when a noble metal such as Pt, Pd, or Rh is supported as an automobile exhaust gas catalyst, it can be supported as follows. First, the honeycomb structure subjected to the acid treatment and the heat treatment is immersed in a slurry of γ-alumina containing “a noble metal catalyst component such as a chloroplatinic acid aqueous solution” and “rare earth oxide such as CeO 2”. After a certain period of time, the honeycomb structure is taken out from the slurry. After taking out the honeycomb structure, excess slurry adhering to the honeycomb structure may be removed with air or the like. Then, by drying the honeycomb structure taken out from the slurry, a honeycomb structure on which a catalyst is supported can be obtained. In addition, you may obtain a honeycomb structure by baking the honeycomb structure taken out from the slurry at the temperature of 500-600 degreeC.

  Examples of the catalyst supported on the honeycomb structure include “three-way catalyst based on a noble metal such as Pt, Pd, Rh”, oxidation catalyst, deodorizing catalyst, “base metal catalyst such as Mn, Fe, Cu”, and the like. it can. As another example of the method for supporting the catalyst, the catalyst is supported on the surface of the partition walls of the honeycomb structure formed of cordierite having a high specific surface area after the acid treatment, and then heat-treated at 600 to 1000 ° C. The method of performing can be mentioned.

Example 1
Talc, kaolin, alumina, silica, and aluminum hydroxide were prepared and mixed to obtain a cordierite forming raw material. Cordierite forming raw material, its chemical composition, SiO ₂ is 42 to 56 wt%, _Al 2 _{O 3} is 30 to 45 mass%, and as MgO is 12 to 16 wt%, talc, kaolin, alumina, Silica and aluminum hydroxide are blended at a predetermined ratio.

  Next, a pore former, methyl cellulose as a binder, and water as a dispersion medium were added to the obtained cordierite forming raw material, and these were mixed to obtain a forming raw material. The pore former was added in an amount of 10 parts by mass with respect to 100 parts by mass of the cordierite forming raw material. 30 parts by mass of the binder was added to 100 parts by mass of the cordierite forming raw material. 50 parts by mass of the dispersion medium was added to 100 parts by mass of the cordierite forming raw material. As the pore former, a material obtained by mixing two types of graphite having different average particle diameters at a predetermined ratio was used. As the graphite, graphite having an average particle diameter of 10 μm and graphite having an average particle diameter of 50 μm were used.

  Next, the obtained forming raw material was kneaded to obtain a clay for forming a honeycomb formed body.

  Next, the obtained clay is extruded using a predetermined die, and a honeycomb structure part having partition walls that form a plurality of cells and an outer periphery arranged so as to surround the outer periphery of the honeycomb structure part And a honeycomb formed body provided with a wall. The overall shape of the honeycomb formed body was a columnar shape. The shape of the cell formed in the honeycomb formed body was a square. The cell shape is a cell shape in a cross section perpendicular to the cell extending direction.

  Next, a plugging slurry was prepared using a cordierite forming raw material prepared in the same manner as that used for the forming raw material. Next, after a film was attached to one end face of the honeycomb formed body, holes were opened with a laser at a size and a position corresponding to the shape of the plugged portion to be formed. A cell present at a position where a hole is formed by a laser is a cell for plugging. As the cells to be plugged, cells that were present so as to surround the central portion of the honeycomb formed body and each cell was adjacent in a ring shape were selected. In addition, as the cells existing so as to surround the central portion, from the cell located at the center of the end face of the honeycomb formed body, the tenth cell is present in each radial direction, and the set of these cells has an annular shape. It will be presented.

  Next, one end face of the honeycomb formed body to which the film is attached is immersed in a plugging slurry, and the plugging slurry is filled into the cells to be plugged through the holes formed in the film. .

  Next, on the other end face of the honeycomb formed body, the plugging slurry was filled into the cells to be plugged in the same manner as the one end face.

  Next, the honeycomb molded body in which the plugging slurry was filled in the cells was dried with hot air at 120 ° C., and then fired at a temperature of 1400 to 1430 ° C. for 10 hours to obtain the honeycomb structure of Example 1. Produced.

The honeycomb structure of Example 1 had a cylindrical shape with an end face diameter of 143.8 mm and a length in the cell extending direction of 100 mm. The cell density of the honeycomb structure was 62 cells / cm ² , and the partition wall thickness was 0.11 mm. The thickness of the partition wall was measured by observing the shape of the cross section of the honeycomb structure with a scanning electron microscope (SEM).

The honeycomb structure of Example 1 had a partition wall bulk density of 0.3 g / cm ³ and a partition wall porosity of 35%. The bulk density porosity of the partition walls was measured using a mercury porosimeter (Autopore 9500 (trade name)) manufactured by Micromeritics.

  In the honeycomb structure of Example 1, the cells formed at the boundary portion of the honeycomb structure portion were provided with plugging portions on both end faces. The honeycomb structure configured as described above is referred to as “both end faces” in the column “placement portion of plugging portion” in Table 1.

  In Example 1, as described above, since the plugged portion is formed in the tenth cell in each radial direction from the cell located at the center of the end face, the shape of the boundary portion Was in an annular range. The honeycomb structure configured as described above is described as “ring-shaped” in the column “plugging portion arrangement shape” in Table 1. Moreover, when the distance from the center of an end surface to the both ends sealing cell of a boundary part was measured, the distance from the center of an end surface was 36 mm. In the column of “disposition distance of plugged portion at end face” in Table 1, the distance from the center of the end face to the cell where the plugged portion is provided is shown.

  In the honeycomb structure of Example 1, the both-end-sealed cells at the boundary were adjacent at the sides. The honeycomb structure configured as described above is referred to as “adjacent on the side” in the “array of plugging portions” column of Table 1. When the both-end sealed cells at the boundary are adjacent at points, they are described as “adjacent at points” in the “array of plugged portions” column of Table 1. In addition, when the both-end sealed cells at the boundary part are a mixture of cells that are adjacent at a point and those that are adjacent at a side, in the column of “array of plugged portions” in Table 1, “ "Mixed point and side".

  In the honeycomb structure of Example 1, the both-end-sealed cells at the boundary portion were such that all the both-end-sealed cells were adjacent at the sides. The honeycomb structure thus configured is described as “100%” in the “connection of plugging portions” column of Table 1. In addition, in the column of “connection of plugged portions” in Table 1, the ratio of the number of both-end sealed cells adjacent at a side or point to the total number of both-end sealed cells in the boundary portion is shown. For example, in the column of “connection of plugging portions” in Table 1, when 50% is described, the number of both-end sealed cells corresponding to 50% of all the both-end sealed cells in the boundary portion. That is, the stop cells are adjacent at sides or points.

  In addition, a column of “ratio of the width of the boundary portion to the diameter” in Table 1 shows a percentage value of the ratio of the width of the boundary portion to the diameter of the end face of the honeycomb structure portion. In Example 1, it was 0.9%.

Table 2 shows the cell densities of the central portion and the outer peripheral portion of the honeycomb structure portion. As described above, in Example 1, the cell density of the honeycomb structure was 62 cells / cm ² in both the central portion and the outer peripheral portion.

  In Example 1, the obtained honeycomb structure was loaded with a catalyst containing a catalyst component and a high specific surface area material. As the catalyst component, palladium, platinum and rhodium were used. As the high specific surface area material, γ-alumina was used. Details of the catalyst loading method will be described below.

  First, palladium, platinum, rhodium, γ-alumina and water were mixed to obtain a catalyst slurry. The mass ratio of palladium, platinum and rhodium was 15: 1: 1 (palladium: platinum: rhodium = 15: 1: 1). The amount of γ-alumina in the catalyst slurry was 20 times the mass of “total mass of palladium, platinum and rhodium”.

  The obtained catalyst slurry was put in a container, and the honeycomb structure of Example 1 was immersed in the catalyst slurry in the container. Thereafter, the honeycomb structure was taken out from the catalyst slurry, excess catalyst slurry was removed with air, and the honeycomb structure was dried at 120 ° C. Air was used as the air. The immersion in the catalyst slurry and the drying were repeated until a predetermined amount of catalyst was supported on the honeycomb structure. After a predetermined amount of catalyst was supported on the honeycomb structure, the honeycomb structure was fired at 550 ° C. in a nitrogen atmosphere. In this way, a honeycomb structure carrying a catalyst was obtained. Here, the “predetermined amount of catalyst” is a catalyst for a honeycomb structure obtained from the total mass of the total mass of palladium, platinum and rhodium which are catalyst components and the mass of γ-alumina which is a high specific surface area material. It is a supported amount, and the “predetermined amount of catalyst” in the present embodiment is an amount at which the supported catalyst amount is 30 g / liter.

  In addition, the “thermal cycle test” and the “HC purification test” were performed on the honeycomb structure of Example 1 by the following method. The results are shown in Table 2.

(Thermal cycle test)
As shown in FIG. 14, the honeycomb structure 100 was mounted in a test can 400 made of stainless steel. Then, using a gas burner tester (not shown), the combustion gas was caused to flow through the honeycomb structure 100 at a flow rate of 1.0 Nm ³ / min. At this time, propane was used as the fuel. The honeycomb structure 100 was heated to 1100 ° C. in 240 seconds and held at 1100 ° C. for 240 seconds, and then a gas at 25 ° C. was flowed at 0.9 Nm ³ / min for 5 minutes. Then, assuming that “from the start of flowing the combustion gas to the end of flowing the gas at 25 ° C.” is one cycle, the cycle was repeated five times. Thereafter, the honeycomb structure 100 was taken out from the test can body 400, and the end face of the honeycomb structure 100 was observed using a microscope to confirm the presence or absence of cracks. When cracks are confirmed by observing the end face of the honeycomb structure 100, “cracked” is written in the “thermal cycle test” column of Table 2. On the other hand, when cracks are not confirmed by observing the end face of the honeycomb structure 100, “no crack” is written in the “thermal cycle test” column of Table 2. FIG. 14 is a schematic diagram illustrating a state in which the honeycomb structure is inserted into the can body in the thermal cycle test of the example. Moreover, in FIG. 14, the arrow shown by the code | symbol 401 has shown the flow direction of combustion gas and 25 degreeC gas.

(HC purification test)
The HC purification test is a test for evaluating the purification performance of hydrocarbon (HC) in exhaust gas. Specifically, first, an exhaust system (Manifold System) as shown in FIG. 15 was produced. An exhaust system 500 shown in FIG. 15 includes a gasoline engine 501 and a catalytic converter 502 equipped with a honeycomb structure (not shown) as an evaluation sample from upstream. As the gasoline engine 501, a 2000 cc gasoline engine was used, and power was absorbed by a dynamometer. Using such an exhaust system 500, an HC purification test was conducted. Here, FIG. 15 is a schematic diagram showing an apparatus used in the HC purification test of the example. Hereinafter, the test method of the HC purification test will be described in more detail.

  In the HC purification test, first, the gasoline engine 501 was started, operated at 3000 rpm for 10 minutes, and then the gasoline engine 501 was stopped. Thereafter, the entire test apparatus as the exhaust system 500 was left at 20 ° C. for 10 hours. As a result, the entire test apparatus was placed in a so-called cold state. The cold state refers to a state in which the gasoline engine body, cooling water, exhaust pipe, and the like are at the same temperature as 20 ° C., which is room temperature.

  Next, in the HC purification test, the gasoline engine is started again from this cold state. After starting, the engine is operated at idling for 10 seconds, and then the gasoline engine 501 is operated at 2000 rpm for 130 seconds or more. At this time, the amount of hydrocarbon in the gas discharged from the catalytic converter 502 is measured until 140 seconds have elapsed after the gasoline engine 501 is started. The “HC ratio” is shown in the “HC purification test” column of Table 2. The “HC ratio” shown in Table 2 can be obtained by the following method. First, without mounting the honeycomb structure carrying the catalyst in the catalytic converter 502 of the exhaust system 500, the HC purification test described so far is performed to measure the amount of hydrocarbon. Next, the honeycomb structure carrying the catalyst is mounted in the catalytic converter 502 of the exhaust system 500, the same HC purification test is performed, and the amount of hydrocarbon is measured. The value of the ratio of the amount of hydrocarbon when the honeycomb structure is attached to the amount of hydrocarbon when the honeycomb structure is not attached is “HC ratio” shown in Table 2. It can be said that the smaller the “HC ratio”, the better the honeycomb structure is in the light-off performance that is the ignition performance of the catalyst.

(Examples 2 to 17)
The honeycomb structures of Examples 2 to 17 were manufactured by changing the structure of the honeycomb structure and the structure of the plugging portions as shown in Tables 1 and 2. In Example 2, the honeycomb structure of Example 1 was changed so that the both-end-sealed cells at the boundary were adjacent to each other at points. In Example 3, the honeycomb structured body of Example 1 was changed so that both-end-sealed cells at the boundary part were mixed at the points and at the sides.

  In Examples 4 to 7, with respect to the honeycomb structure of Example 1, the ratio of the width of the boundary portion to the diameter was changed as shown in Table 1. In Examples 8 to 12, the connection of the plugged portions was changed as shown in Table 1 with respect to the honeycomb structure of Example 1.

In Example 13, the cell structure at the center of the honeycomb structure was changed so that the cell density at the center was 93 cells / cm ² . In Example 14, the cell structure of the outer peripheral part of the honeycomb structure part was changed so that the cell density of the outer peripheral part was 93 cells / cm ² .

  In Example 15, when forming the plugged portion, the cells to be plugged exist so as to surround the central portion of the honeycomb formed body, and each cell is adjacent to the ring, and the honeycomb A cell existing on the outermost periphery of the molded body was selected. In the honeycomb structure of Example 15, the plugged portions are arranged on both side end surfaces of the cells formed at the boundary portion of the honeycomb structure portion and the cells formed at the outermost periphery of the outer peripheral portion of the honeycomb structure portion. It was what was done. In “Disposition distance of plugging portion on end face” in Table 1, the distance indicated by “36 mm from center of end face” indicates the disposition distance of plugging portion in the boundary portion. On the other hand, in the “disposition distance of the plugging portion on the end face” in Table 1, the distance indicated by “72 mm from the center of the end face” indicates the disposition distance of the plugging portion on the outermost periphery of the outer peripheral portion.

  In Example 16, the shape of the boundary portion was a triangular ring shape. The honeycomb structure configured as described above is described as “triangular” in the column “Arrangement shape of plugging portions” in Table 1. Moreover, in Example 17, the shape of the boundary portion was a quadrangular annular shape. The honeycomb structure configured as described above is referred to as “square shape” in the column “arrangement shape of plugging portions” in Table 1.

(Comparative Examples 1-6)
The honeycomb structures of Comparative Examples 1 to 6 were manufactured by changing the structure of the honeycomb structure and the structure of the plugging portions as shown in Tables 1 and 2. In the honeycomb structure of Comparative Example 1, no plugging portions were provided for all cells. In the honeycomb structures of Comparative Examples 2 to 4, plugging portions were provided only on one end face of the honeycomb structure.

  For the honeycomb structure of Comparative Example 5, plugging portions were disposed only in the outermost peripheral cells of the outer peripheral portion of the honeycomb structure portion without disposing the plugging portions at the boundary portion of the honeycomb structure portion. It was supposed to be. In Comparative Example 5, plugging portions were provided on both end faces of the honeycomb structure for the outermost peripheral cell of the outer peripheral portion.

  In the honeycomb structure of Comparative Example 6, no plugging portion was disposed at the boundary portion of the honeycomb structure portion. In Comparative Example 6, after the outer peripheral wall disposed outside the outer peripheral portion of the honeycomb structure portion was removed by grinding, an outer periphery coating material was applied to the outer periphery of the honeycomb structure portion, and the outermost periphery of the honeycomb structure portion was An outer peripheral coating layer was formed on the substrate. In the column of “placement of plugged portions” in Table 1, the honeycomb structure of Comparative Example 6 is described as “no plugged portion (only outer peripheral coat layer)”.

  For the honeycomb structures of Examples 2 to 17 and Comparative Examples 1 to 6, “thermal cycle test” and “HC purification test” were performed in the same manner as in Example 1. The results are shown in Table 2.

(result)
As shown in Table 2, the honeycomb structures of Examples 1 to 17 have a lower “HC ratio” as a result of the HC purification test than the honeycomb structures of Comparative Examples 1 to 6. That is, the honeycomb structures of Examples 1 to 17 were able to activate the catalyst at an early stage, and were excellent in light-off performance at the time of engine cold start. In addition, as shown in Table 1, the “disposition shape of plugging portions”, “array of plugging portions”, “connection of plugging portions”, and “ratio of the width of the boundary portion to the diameter” are changed. As a result, the “HC ratio”, which is the result of the HC purification test, varies, but when compared with the honeycomb structures of Comparative Examples 1 to 6, all obtain good results for the light-off performance. I was able to. Further, as in Comparative Example 5, even if the cells plugged at both end faces are present only on the outermost periphery of the honeycomb structure portion, the “HC ratio” as a result of the HC purification test is lowered. I couldn't. Further, even if the outer peripheral portion of the honeycomb structure portion is ground and the outer peripheral coat layer is disposed on the outermost periphery of the honeycomb structure portion as in Comparative Example 6, the “HC ratio” as a result of the HC purification test is reduced. I couldn't.

  The honeycomb structure of the present invention can be used as a catalyst carrier that supports a catalyst for purifying exhaust gas discharged from a gasoline engine, a diesel engine, or the like.

1: partition wall, 2: cell, 2a: cell (cell existing in the central part), 2b: cell (cell existing in the boundary part), 2c: cell (cell existing in the outer peripheral part), 3: outer peripheral wall, 4 : Honeycomb structure part, 5: plugging part, 11: inflow end face, 12: outflow end face, 21: center part, 22: boundary part, 23: outer peripheral part, 32a: open cell at both ends, 32b: sealed cell at both ends, 32c: Opening cell at both ends, 32d: Opening cell at both ends of the outermost periphery, 32e: Opening cell at both ends, 32f: Sealing cell at both ends of the outer periphery, 110: honeycomb structure, 123: first outer peripheral portion, 223: outer peripheral inner boundary portion, 323: second outer peripheral portion, 400: test can body, 401: gas flow direction, 500: exhaust system, 501: Gasoline engine 502: Medium converter.

Claims (13)

A columnar honeycomb structure having a porous partition wall that defines a plurality of cells serving as fluid flow paths extending from the inflow end surface to the outflow end surface;
The honeycomb structure part includes a central part, a boundary part, and an outer peripheral part in a cross section orthogonal to the cell extending direction,
The central portion is a portion including the cell present in the central portion of the cross section,
The boundary part is a part including the cell that exists so as to surround the outer periphery of the central part,
The outer peripheral portion is a portion including the cells existing further outside the boundary portion,
The cell formed at the boundary portion is a both-end sealed cell in which plugging portions for sealing the opening of the cell are disposed at the end portion on the inflow end surface side and the end portion on the outflow end surface side. A honeycomb structure. The cell formed on the outermost periphery of the outer peripheral portion includes an incomplete cell in which a part of the partition wall defining the periphery of the cell is missing,
The honeycomb structure according to claim 1, wherein the honeycomb structure portion includes an outer peripheral coat layer disposed so as to cover the outer peripheral portion.   The cell formed on the outermost periphery of the outer peripheral portion is provided with a plugging portion that seals an opening of the cell at an end portion on the inflow end surface side and an end portion on the outflow end surface side. The honeycomb structure according to claim 1 or 2, comprising a peripheral both-end sealed cell. The outer periphery is
A first outer peripheral portion including the cells present so as to surround the outer periphery of the boundary portion;
An outer periphery inner boundary including the cells present so as to further surround the outer periphery of the first outer periphery;
And a second outer peripheral portion including the cells existing further outside the outer peripheral inner boundary portion,
The cell formed at the inner peripheral boundary portion is an outer peripheral portion in which a plugging portion for sealing an opening of the cell is disposed at an end portion on the inflow end surface side and an end portion on the outflow end surface side. The honeycomb structure according to any one of claims 1 to 3, comprising a both-end sealed cell.   The honeycomb structure according to any one of claims 1 to 4, wherein an average pore diameter of the partition walls of the honeycomb structure portion is 5 µm or more and 200 µm or less.   The honeycomb structure according to any one of claims 1 to 5, wherein a porosity of the partition walls of the honeycomb structure portion is 25% or more and 70% or less.   The honeycomb structure according to any one of claims 1 to 6, wherein a thickness of the partition wall of the honeycomb structure portion is 0.038 mm or more and 0.500 mm or less. The honeycomb structure according to any one of claims 1 to 7, wherein the honeycomb structure has a cell density of 15 cells / cm ² or more and 233 cells / cm ² or less.   The honeycomb structure according to any one of claims 1 to 8, wherein the honeycomb structure portion has a cell density in the central portion and a cell density in the outer peripheral portion different from each other.   The honeycomb structure according to claim 9, wherein the honeycomb structure portion has a cell density in the central portion larger than a cell density in the outer peripheral portion.   The partition walls of the honeycomb structure part are selected from the group of silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. The honeycomb structure according to any one of claims 1 to 10, wherein the honeycomb structure is made of a material containing at least one kind of ceramic.   The honeycomb structure according to any one of claims 1 to 11, which is used for exhaust gas purification of an internal combustion engine.   The honeycomb structure according to any one of claims 1 to 12, wherein an exhaust gas purifying catalyst is supported on at least one of a surface of the partition wall and a pore of the partition wall of the honeycomb structure part.

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