JP2010104957A - Honeycomb structure and honeycomb catalyst body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a honeycomb structure for efficiently removing toxic substances in exhaust gas by carrying a catalyst and for effectively restraining the increase of a pressure loss. <P>SOLUTION: The honeycomb structure is constituted as follows. A partition wall 1 has a porosity of 50-80% and an average pore size of 15-70 μm. A part 4 of a plurality of cells 4 are first cells 4a, the opening of each of which at the inflow-side end is opened and in the opening of each of which at the outflow-side end an open area reducing member 6 is arranged for plugging a part of the opening, and remaining cells 4 are second cells 4b the openings at both ends of each of which are opened. The first cell and the second cell are arranged alternately. A slit 7 is formed on both of the partition wall 1 and the open area reducing member 6 at the outflow-side end of at least one row of rows 5, in each of which the first cell 4a and the second cell 4b are arranged alternately, so that the slit travels the length of the row 5 of the cells. The depth of the slit 7 in the extending direction of the cell is made deeper than that of the open area reducing member 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a honeycomb structure and a catalyst body. More specifically, by supporting the catalyst, carbon monoxide (CO), hydrocarbon (HC) contained in exhaust gas discharged from automobiles, construction machinery, industrial stationary engines, and combustion equipment, etc. A honeycomb structure capable of efficiently purifying harmful substances of nitrogen oxide (NO _x ) and effectively suppressing an increase in pressure loss, and a catalyst supported on the honeycomb structure The present invention relates to a honeycomb catalyst body.

Currently, a honeycomb catalyst body in which a catalyst is supported on a honeycomb structure is used to purify exhaust gas discharged from various engines or the like (see, for example, Patent Document 1). In such a honeycomb catalyst body, fluid (exhaust gas) flows into each cell from the end face on the inflow side, and carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO _X ) contained in the exhaust gas. And other harmful substances are purified with a catalyst.

  Conventionally, a honeycomb structure used for such a honeycomb catalyst body increases the cell density, increases the geometric area on which the catalyst is supported, and improves the exhaust gas purification performance. It was made to increase the contact efficiency.

Japanese Patent Laid-Open No. 07-00766

  However, in the conventional honeycomb structure and honeycomb catalyst body, if the cell density of the honeycomb structure is increased in order to improve the purification performance, the pressure loss when the exhaust gas passes through the cell increases. On the other hand, if it is intended to suppress the increase in pressure loss by thinning the partition walls of the honeycomb structure, the contact efficiency between the exhaust gas and the catalyst is lowered, and the exhaust gas purification performance is lowered.

  Thus, in the conventional honeycomb structure and honeycomb catalyst body, there is a tradeoff between improving the purification performance and reducing the pressure loss, and it is extremely difficult to achieve both. There was a problem.

  The present invention has been made in view of such problems of the prior art, and by carrying a catalyst, it is possible to efficiently purify harmful substances contained in exhaust gas, and pressure loss Is provided, and a honeycomb catalyst body in which a catalyst is supported on the honeycomb structure is provided.

  In order to solve the above-described problems, the present invention provides the following honeycomb structure and honeycomb catalyst body.

[1] A porous partition wall that partitions and forms a plurality of cells serving as fluid flow paths that penetrate from the end surface on the inflow side to the end surface on the outflow side, and the partition wall has a porosity of 50 to 80%, and The average pore diameter is 13 to 70 μm, and some of the plurality of cells have an opening at the end on the inflow side and one opening of the opening at the end on the outflow side. A first cell in which an opening area reducing member is disposed so as to close the portion, and the remaining cell is a second cell in which openings at both ends are opened, and the first cell and the first cell Two cells are alternately arranged, and at the outflow side end of at least one row of cells in which the first cells and the second cells are alternately arranged, the rows of cells are vertically cut. A slit is formed in the partition wall and the opening area reducing member, and the cell extends in the slit. A honeycomb structure in which a depth in a direction is deeper than a depth in the cell extending direction of the opening area reducing member.

[2] The honeycomb structure according to [1], wherein the row of cells in which the slits are formed is a row of a plurality of cells arranged in parallel with each other on an end face on the outflow side.

[3] The row of cells in which the slits are formed is arranged in parallel with each other at the outflow side end surface, and intersects with the row of cells arranged in parallel with each other and the row of cells arranged in parallel with each other. The honeycomb structure according to [1], which is a row of a plurality of cells.

[4] The lower limit of the depth of the slit in the cell extending direction is 1 mm, and the upper limit is 30 mm or 1/2 of the total length in the cell extending direction, whichever is shorter [1] ] The honeycomb structure according to any one of [3].

[5] The honeycomb structure according to any one of [1] to [4], wherein the opening area reducing member is made of a porous body having a porosity of 20 to 80%.

[6] The honeycomb structure according to any one of [1] to [5], and a catalyst supported on the inner surface of the pores of the partition walls of the honeycomb structure and supported on the partition surface. A honeycomb catalyst body having a catalyst loading of 100 to 250 g / L.

  In the honeycomb structure and the honeycomb catalyst body of the present invention, in the honeycomb structure having a porous partition wall having a specific porosity and an average pore diameter, the area of the opening of the cell on the end face on the outflow side of the first cell is open. Since it is reduced by the area reducing member (since the opening of the cell is opened as a slit formed in the opening area reducing member), a part of the fluid flowing into the first cell is transferred to the first cell. Can be permeated through the partition wall forming the partition wall and actively flow out into the adjacent second cell, and the harmful substances contained in the exhaust gas can be efficiently purified.

  In the honeycomb structure and the honeycomb catalyst body of the present invention, the porosity and average pore diameter of the partition walls are in a specific range, and the area of the opening on the outflow side is reduced in the first cell. However, as described above, a part of the fluid can flow out from the reduced opening (slit) and the slit formed in the partition wall (that is, the opening is not completely sealed). Even if the exhaust gas purification efficiency is improved, an increase in pressure loss can be effectively suppressed or the pressure loss can be reduced.

  That is, the honeycomb structure and the honeycomb catalyst body of the present invention can simultaneously solve the problems that are difficult to achieve with the conventional techniques, such as improving the purification efficiency of exhaust gas and suppressing the increase in pressure loss. Further, the amount of the supported catalyst can be reduced by improving the purification efficiency.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be specifically described. However, the present invention is not limited to the following embodiment, and is within the scope of the gist of the present invention. Based on this knowledge, it should be understood that design changes, improvements, etc. can be made as appropriate.

[1] Honeycomb structure:
As shown in FIGS. 1 to 3, the honeycomb structure 100 of the present embodiment has a porous structure in which a plurality of cells 4 serving as fluid flow paths penetrating from the end surface 2 on the inflow side to the end surface 3 on the outflow side are formed. The partition wall 1 has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm, and some of the cells 4 in the plurality of cells 4 have end portions on the inflow side. Are the first cells 4a in which the opening area reducing member 6 is disposed so as to block a part of the opening at the opening on the outflow side, and the remaining cells 4 are It is the 2nd cell 4b by which the opening part of the both ends was opened, the 1st cell 4a and the 2nd cell 4b are arrange | positioned alternately, and the 1st cell 4a and the 2nd cell 4b are alternately arranged The partition wall 1 and the opening are formed so as to cut the cell row 5 longitudinally at the outflow side end of at least one row of the “cell row 5”. A slit 7 is formed in the area reducing member 6, and the depth (slit depth) D <b> 1 of the slit 7 in the cell 4 extending direction is the depth of the opening area reducing member 6 in the cell 4 extending direction (opening area reduction). The member depth is deeper than D2. The opening area reducing member 6 disposed in the first cell 4 a has a shape penetrating in the extending direction of the cell 4 by the slit 7. The cell row 5 is a row of cells extending in one row formed by alternately arranging the first cells 4a and the second cells 4b. Here, FIG. 1 is a perspective view schematically showing an embodiment of the honeycomb structure of the present invention, and FIG. 2 schematically shows a part of the embodiment of the honeycomb structure of the present invention. It is a top view seen from the outflow side end surface side shown, and FIG. 3 is a schematic diagram which shows the AA 'cross section of FIG.

The honeycomb structure 100 of the present embodiment can be suitably used as a catalyst carrier of a honeycomb catalyst body for purifying exhaust gas discharged from various engines or the like. More specifically, for example, a honeycomb catalyst body is produced by supporting a catalyst on the inner surface of the pores of the partition walls and the partition surface, and the obtained honeycomb catalyst body is disposed inside the exhaust gas exhaust system, As from the end surface of the inlet side is allowed to flow the fluid (exhaust gas) in each cell, the inflowing exhaust gas, by transmitting the partition, carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO _X ) And other harmful substances are purified with a catalyst.

  In the honeycomb structure 100 of the present embodiment, the partition walls 1 have a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm, and the porosity is higher than that of the honeycomb structure used in the conventional honeycomb catalyst body. The partition wall 1 is formed of a porous body that is high and has a large average pore diameter. For this reason, when a catalyst is supported on a honeycomb structure and used as a honeycomb catalyst body, an increase in pressure loss can be effectively suppressed.

  In this specification, “porosity” refers to a value measured by a mercury porosimeter (mercury intrusion method). The “average pore diameter” is measured by a mercury porosimeter (mercury intrusion method), and the cumulative volume of mercury injected into the porous substrate (ie, the partition wall) is the total fineness of the porous substrate. The pore diameter calculated from the pressure when the pore volume is 50%.

  Further, in the honeycomb structure 100 of the present embodiment, the slits 7 are formed in the partition walls 1 and the opening area reducing member 6 so as to cut the cell rows 5 vertically, so that the gas flow is less disturbed and the pressure loss is increased. There is an advantage that can be suppressed.

  Furthermore, in the honeycomb structure 100 of the present embodiment, the opening area of the opening of the first cell 4a (the area in the cross section perpendicular to the flow path direction of the cell) is reduced by the opening area reducing member 6. Since a part of the fluid can flow out from the reduced opening (that is, the opening of the first cell 4a is not completely sealed), the exhaust gas purification efficiency is improved as described above. While improving, the increase in pressure loss can be suppressed effectively or pressure loss can be reduced.

  Further, in the second cell 4b, the fluid passing through the inside of the second cell 4b is agitated by the fluid flowing through the partition wall 1 from the adjacent first cell 4a, so that the second cell 4b is stirred. The contact efficiency with the catalyst supported on the surface of the partition wall 1 partitioning 4b is improved, and the purification performance can be improved more effectively.

  A honeycomb structure 100 according to the present embodiment includes a porous partition wall 1, and a plurality of cells 4 serving as fluid flow paths penetrating from the end surface 2 on the inflow side to the end surface 3 on the outflow side are partitioned by the partition wall 1. Has been. Note that the honeycomb structure 100 of the present embodiment has an outer peripheral wall 11 disposed so as to surround the outer periphery of the partition wall 1 that defines the cells 4.

  As described above, this partition wall has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm, but the partition wall porosity is preferably 60 to 80%, and preferably 65 to 75. % Is more preferable. With this configuration, the exhaust gas purification efficiency can be improved satisfactorily, the increase in pressure loss can be effectively suppressed, and further the pressure loss can be reduced.

  In addition, when the porosity of the partition is less than 50%, the porosity of the partition is too low, the pore surface area of the partition is reduced, the effect of improving the purification efficiency, and the effect of suppressing the increase in pressure loss It becomes impossible to achieve both. In particular, the exhaust gas purification efficiency is significantly reduced. On the other hand, when the porosity of the partition walls exceeds 80%, the amount (flow rate) of the exhaust gas that permeates the partition walls increases and the exhaust gas purification efficiency is improved, but the mechanical strength of the honeycomb structure is significantly reduced. , Damage and the like are likely to occur, making it difficult to use as a catalyst carrier.

  Conventionally, in a honeycomb structure used as a catalyst carrier, when the mechanical strength is significantly reduced, a large amount (excess) of a catalyst containing a noble metal is supported to increase the mechanical strength of the honeycomb catalyst body. In some cases, the precious metals contained in the catalyst described above are relatively expensive, and there is a problem that the manufacturing cost of the honeycomb catalyst body increases with an increase in the amount of the catalyst used. The honeycomb structure of the present embodiment has a mechanical strength that can withstand use as a catalyst carrier in a necessary and sufficient amount of catalyst supported.

  The average pore diameter of the partition walls of the honeycomb structure is 13 to 60 μm, preferably 15 to 50 μm, and more preferably 18 to 40 μm. With this configuration, the exhaust gas purification efficiency can be improved satisfactorily, the increase in pressure loss can be effectively suppressed, and further the pressure loss can be reduced.

  When the average pore diameter of the partition walls is less than 13 μm, when the catalyst is supported on the inner surface of the partition wall pores and used as a honeycomb catalyst body, the pores are blocked, and the exhaust gas from the inner surface of the pores is blocked. Purification is not performed, and purification efficiency is significantly reduced. On the other hand, if the average pore diameter of the partition walls exceeds 70 μm, the total inner surface area of the partition wall pores decreases, and the exhaust gas purification efficiency decreases.

Cell density of the honeycomb structure of the present embodiment is preferably from 16 to 93 cells ^/ cm 2 ^{(100~600cpsi),} more preferably from 42-62 cells ^/ cm 2 ^{(300~400cpsi).} When the cell density is less than 16 cells / cm ² , the contact efficiency with the exhaust gas is lowered, and the purification efficiency may be lowered. When the cell density is more than 93 cells / cm ² , the pressure loss is increased. Sometimes. “Cpsi” is an abbreviation for “cells per square inch”, and is a unit representing the number of cells per square inch.

  Moreover, it is preferable that the thickness of a partition is 80-450 micrometers, and it is still more preferable that it is 230-330 micrometers. If the partition wall thickness is less than 80 μm, the strength may be insufficient and thermal shock resistance may decrease, and if it exceeds 450 μm, pressure loss may increase. The shape of the cross section perpendicular to the cell flow path direction is not particularly limited, and for example, it is preferable to combine a triangular, quadrangular, or octagonal cell with a quadrangular cell. With this configuration, the opening area reducing members can be arranged in a staggered manner at the end face on the outflow side of the honeycomb structure, and the first cell and the second cell are adjacent to each other with a partition wall therebetween. Can be arranged to do. In one preferred embodiment, the first cell is octagonal and the second cell is square, or the first cell is square and the second cell is octagonal.

  The shape of the cross section perpendicular to the central axis of the honeycomb structure of the present embodiment, that is, the shape of the outer peripheral wall arranged so as to surround the partition wall is not particularly limited, but for example, a circle, an ellipse, an ellipse, a trapezoid , Triangles, squares, hexagons, other polygons, or left-right asymmetrical shapes. Among these, a circle, an ellipse, an ellipse, and a quadrangle are preferable.

  As a material constituting the partition walls of the honeycomb structure of the present embodiment, a material mainly composed of ceramics can be given as a suitable example. Preferred examples of ceramics include silicon carbide, cordierite, aluminum titanate, sialon, mullite, silicon nitride, zirconium phosphate, zirconia, titania, alumina, silica, or a combination thereof. In particular, ceramics such as silicon carbide, cordierite, mullite, silicon nitride, and alumina are preferable from the viewpoint of alkali resistance. Among these, oxide-based ceramics are preferable because of their low cost.

  Note that the outer peripheral wall disposed so as to surround the partition walls may be a molded integrated wall that is formed integrally with the honeycomb structure when the honeycomb structure is formed, or the honeycomb structure having a wall on the outer periphery thereof. Alternatively, the outer peripheral wall of the honeycomb structure may be ground to have a predetermined shape and the outer peripheral wall may be formed of cement or the like. Such an outer peripheral wall can be formed using the material similar to the material which comprises the partition mentioned above, for example.

  In the honeycomb structure of the present embodiment, a plurality of cells penetrating from the end surface on the inflow side to the end surface on the outflow side are partitioned by the porous partition walls. This cell serves as a flow path for fluid, that is, exhaust gas, and a part of the exhaust gas flowing in from the end surface on the inflow side passes through the partition wall that partitions the cell and flows out into the adjacent cell. In addition, harmful substances are purified by the inner surface of the pores of the partition walls and the catalyst supported on the partition surface, and the resulting purified gas can be discharged from the end face on the outflow side.

  In the honeycomb structure of the present embodiment, as shown in FIGS. 1 to 3, some of the cells 4 in the plurality of cells 4 are open at the end on the inflow side and end at the outflow side. Is the first cell 4a in which the opening area reducing member 6 is disposed so as to block a part of the opening, and the remaining cell 4 is the second cell in which the opening at both ends is opened. This is a cell 4b, in which the first cells 4a and the second cells 4b are alternately arranged.

  The opening area reducing member 6 is preferably made of a porous body having a porosity of 20 to 80%. With this configuration, the exhaust gas can permeate through the opening area reducing member 6, so that the exhaust gas can also be purified by the opening area reducing member 6. When the porosity is less than 20%, the exhaust gas does not flow to the second cell, and only about half of the cells are used for purification, and the harmful component emission amount may be greatly increased. If the amount exceeds 80%, the amount (flow rate) of the exhaust gas that permeates the partition wall increases, and the purification performance of the exhaust gas is improved. However, the mechanical strength of the honeycomb structure is reduced, so that damage or the like may easily occur. , It may be difficult to use as a catalyst support.

  The opening area reducing member 6 has a length from an end face (outlet side end face) in the outflow side opening to an opposite end face in the cell flow path direction (cell extending direction), that is, the opening area reducing member depth D2. Is preferably 0.3 to 10 mm, and more preferably 0.5 to 5 mm. If the opening area reducing member depth D2 is less than 0.3 mm, the mechanical strength of the plugged portion is reduced, and a sufficient bonding force between the plugged portion and the partition wall cannot be obtained, and the exhaust gas. The plugging portion may be easily damaged by the pressure or vibration from the outside. When the opening area reducing member depth D2 exceeds 10 mm, the effective area of the partition wall through which the exhaust gas permeates decreases, and sufficient purification efficiency may not be obtained. The opening area reducing member depth D2 of all the opening area reducing members is preferably the same, but may be different.

  The difference between the slit depth D1 and the opening area reducing member depth D2 is a minimum value of 1 mm, a maximum value of 30 mm, or 1/2 of the total length in the cell extending direction of the honeycomb structure, whichever is shorter Preferably, the minimum value is 5 mm, the maximum value is 15 mm, or 1/4 of the total length in the cell extending direction of the honeycomb structure, whichever is shorter, and the minimum value is It is more preferable that the value is 8 mm, the maximum value is 10 mm, or 1/5 of the total length in the cell extending direction of the honeycomb structure, whichever is shorter. If the difference between the slit depth D1 and the opening area reducing member depth D2 is larger than 30 mm or 1/2 of the total length in the cell extending direction of the honeycomb structure, whichever is shorter, the exhaust gas passing through the slit Since the amount of exhaust gas increases and the amount of exhaust gas that permeates through the partition walls decreases, sufficient purification efficiency may not be obtained.

  As the material constituting the opening area reducing member 6, those mentioned as the material of the partition walls of the honeycomb structure can be preferably used, and more preferably the same as the material of the partition walls.

  As shown in FIGS. 1 to 3, the honeycomb structure of the present embodiment has a cell row 5 at the outflow side end portion of the cell row 5 in which the first cells 4 a and the second cells 4 b are alternately arranged. A slit 7 is formed in the partition wall 1 and the opening area reducing member 6 so as to be longitudinally cut. The row 5 of cells in which the slits 7 are formed is preferably the row 5 of cells extending between the cells including the outer peripheral wall 11. In this case, the cells 4 and 4 positioned at both ends of the cell row 5 become the cells 4 positioned at the outermost periphery of the honeycomb structure 100, and the slits 7 are also formed in the outer peripheral wall 11. The slits 7 are preferably formed in all the cell rows 5 of the honeycomb structure 100, but are preferably formed in 25% or more of the number of cell rows 5 and formed in 50% or more. More preferably. The width of the slit 7 is preferably 30 to 90% of the width of the cell 4, and more preferably 40 to 80%. The width of the cell 4 is the length of one side of the flow path in the cross section orthogonal to the cell extending direction (the partition wall thickness is not included). If it is narrower than 30%, the pressure loss when the exhaust gas passes may increase, and if it is larger than 90%, the purification efficiency may decrease. The widths of all the slits are preferably the same, but may vary depending on the site. For example, in a preferred embodiment, the slit width is narrowed at the central portion where the exhaust gas flow rate is large, and the slit width is widened at the outer peripheral portion where the exhaust gas flow rate is small. The slit 7 is preferably formed so as to cut the center of the cell 4. As shown in FIG. 2, the cell row 5 in which the slits 7 are formed intersects with the plurality of cell rows 5 a arranged in parallel to each other and the plurality of cell rows 5 a arranged in parallel on the end surface 3 on the outflow side. It is preferable that it is the row | line | column 5b of several other cells located in parallel with each other. When the cross-sectional shape of the cell 4 perpendicular to the cell extending direction is a quadrangle, the cell row 5a and the cell row 5b are orthogonal to each other.

  The lower limit value of the depth D1 of the slit 7 in the cell extending direction is 1 mm, and the upper limit value is 30 mm or 1/2 of the total length in the cell extending direction of the honeycomb structure, whichever is shorter. It is preferable. If it is shorter than 1 mm, the pressure loss may be difficult to reduce. If it is longer than 30 mm or 1/2 of the total length in the cell extending direction of the honeycomb structure, whichever is shorter, exhaust gas purification efficiency may be reduced. The slit depths D1 of all the slits are preferably the same, but may be different. The width and depth of the slit are measured with a caliper, and the value of the narrowest portion is defined as the width and depth.

  In the honeycomb structure of the present embodiment, since the slits are formed in both the opening area reducing member and the partition wall at the end portion on the outflow side, the flow is disturbed as compared with the case where it is formed on one side, thereby purifying. There is an advantage that the performance is improved.

  In a cross section orthogonal to the cell extending direction, the ratio of the opening area (slit area) of the opening area reducing member 6 disposed in the first cell 4a to the opening area of the second cell 4b (slit opening ratio). ) Is preferably 25 to 100%, more preferably 30 to 90%. If it is less than 25%, the pressure loss when the exhaust gas passes may increase, and if it exceeds 90%, the purification performance may deteriorate.

  In the cross section orthogonal to the cell extending direction, the total area of the slits formed in the opening area reducing member 6 is 25 to 100% with respect to the total area of the cells in which the opening area reducing member 6 is disposed. Is more preferably 30 to 90%. If it is less than 25%, the pressure loss when the exhaust gas passes may increase, and if it exceeds 90%, the purification performance may deteriorate.

  Among the cells in which the opening area reducing member is provided, the number of cells in which the opening area reducing member in which the slit is formed is provided is the number of all cells in which the opening area reducing member is provided. It is preferable that it is 90% or more. If it is less than 90%, the pressure loss may increase. Here, the opening area reducing member in which no slit is formed is the same as the plugging member that completely closes the opening of the cell.

  In another embodiment of the honeycomb structure of the present invention, as shown in FIG. 4, the cell row 5 in which the slits 7 are formed is a plurality of cell rows 5 c arranged in parallel to each other on the end surface 3 on the outflow side. . The other configuration is the same as that of the embodiment of the honeycomb structure of the present invention. Even when only the parallel slits 7 are formed as in the honeycomb structure 200 of the present embodiment, the exhaust gas can be efficiently purified and the increase in pressure loss can be effectively suppressed. Is possible. Fig. 4 is a plan view schematically showing a part of another embodiment of the honeycomb structure of the present invention as seen from the outflow side end face side.

[2] Manufacturing method of honeycomb structure:
Next, the manufacturing method of one embodiment of the honeycomb structure of the present invention will be specifically described.

  The method for manufacturing a honeycomb structured body of the present embodiment includes a step (1) of obtaining a columnar honeycomb formed body having partition walls that form a plurality of cells serving as fluid flow paths by forming a ceramic forming raw material. The opening of a predetermined cell (first cell) on one end surface (outflow side end surface) side of the formed honeycomb molded body is filled with plugging slurry, and the opening at the outflow side end of the predetermined cell A step (2) of obtaining a plugged honeycomb formed body plugged with a portion, and forming a slit at an outflow side end (one end face side end) of the obtained plugged honeycomb formed body The step (3) of obtaining an opening area-reduced honeycomb formed body in which the area of the opening of a predetermined cell is reduced on one end face (end face on the outflow side), and firing the obtained open-area reduced honeycomb formed body And a step (4) for obtaining a honeycomb structure. It is a manufacturing method.

  Hereinafter, the manufacturing method of the honeycomb structure of the present embodiment will be described in more detail for each step.

[2-1] Step (1):
Step (1) is a step of forming a ceramic forming raw material containing a ceramic raw material to obtain a honeycomb formed body having partition walls that partition and form a plurality of cells serving as fluid flow paths. This step (1) can be performed according to a conventionally known method for manufacturing a honeycomb structure.

[2-2] Step (2):
In the step (2), the plugging slurry is filled in the opening of a predetermined cell (first cell) on one end face (end face on the outflow side) of the obtained honeycomb formed body, and the first cell This is a step of obtaining a plugged honeycomb formed body in which a plugged portion is formed in the opening at the outflow side end of the plug. The first cells filled with the plugging slurry and the second cells not filled with the plugging slurry are alternately arranged.

  In the method for manufacturing a honeycomb structure of the present embodiment, the end portion on the outflow side of the remaining cells (second cells) that do not form plugged portions is covered with a mask, and only the first cells are plugged slurry. Fill.

  The method for disposing the mask in the second cell is not particularly limited. For example, an adhesive film is attached to the entire one end face (outflow end face) of the honeycomb formed body, and the adhesive film is used. And a method of forming a hole at a position corresponding to the opening of the “first cell without mask”. More specifically, after sticking an adhesive film to one whole end face of the honeycomb formed body, a portion of the adhesive film corresponding to a cell (first cell) in which a plugging portion is to be formed. For example, a method of making a hole with a laser can be suitably used. As an adhesive film, what applied the adhesive to one surface of the film which consists of resin, such as polyester, polyethylene, a thermosetting resin, etc. can be used conveniently.

  Examples of the plugging slurry for forming the plugging portion include a slurry in which the above ceramic raw material and additive are blended. It is preferable to adjust the viscosity to 200 to 400 dPa · s by mixing water, a binder, a pore former, a surfactant or the like as an additive.

  In addition, after forming the plugged portions with the plugging slurry in this way, the obtained plugged honeycomb formed body may be further dried.

[2-3] Step (3):
In the step (3), a slit is formed in the outflow side end portion (one end surface side end portion) of the obtained plugged honeycomb formed body, and a predetermined end is formed on the one end surface (outflow side end surface) side. An opening area reduced honeycomb formed body in which the area of the cell opening is reduced is obtained. The slits may be formed in such a manner that the cell rows 5 in which the slits 7 are formed intersect each other as in the honeycomb structure 100 shown in FIG. 2, or the honeycomb structure 200 shown in FIG. As described above, the cell rows 5 in which the slits 7 are formed may be parallel to each other.

  The method for forming the slit is not particularly limited. For example, it is preferable to form the slit by spraying a fluid onto a honeycomb structure which is an unfired ceramic molded body or a fired ceramic fired body. Examples of the fluid to be sprayed include compressed air. In addition, cutters are also a simple slit forming means. In the unfired stage, shipping and the like are also preferably used.

[2-4] Step (4):
Step (4) is a step of firing the obtained aperture area-reduced honeycomb formed body to obtain a honeycomb structure. In this way, the honeycomb structure of the present embodiment can be manufactured easily and at low cost. This step (4) can be performed according to a conventionally known method for manufacturing a honeycomb structure.

[3] Honeycomb catalyst body:
Next, an embodiment of the honeycomb catalyst body of the present invention will be specifically described. The honeycomb catalyst body of the present embodiment is supported on the inner surfaces of the pores of the partition walls of the honeycomb structure of the present invention described above (the honeycomb structure 100 shown in FIGS. 1 to 3) and the honeycomb structure. And a catalyst supported on the partition wall surface.

Such a honeycomb catalyst body allows exhaust gas discharged from automobile, construction machine, and industrial stationary engines, combustion equipment, and the like to flow into each cell from the end face on the inflow side, While purifying with the catalyst on the partition wall surface, it allows the partition wall to permeate and purifies harmful substances such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO _x ), etc. with the catalyst. The permeated fluid (purified gas) that has passed through the partition walls flows out from the opening on the end face on the outflow side of an adjacent cell.

  Since the honeycomb catalyst body of the present embodiment is one in which the catalyst is supported on the honeycomb structure of the present invention, the area of the cell opening on the outflow side end face of the first cell is reduced by the opening area reducing member. Therefore, a part of the fluid that has flowed into the first cell can permeate through the partition wall that defines the first cell, and can actively flow out into the adjacent second cell. The contained harmful substances can be efficiently purified.

  Further, in the honeycomb catalyst body of the present embodiment, the porosity and average pore diameter of the partition walls are in a specific range, and in the first cell, although the area of the opening is reduced, it is reduced. Since a part of the fluid can flow out from the opening (that is, the opening is not completely sealed), the exhaust gas purification efficiency is improved and the increase in pressure loss is effective as described above. Can be suppressed or pressure loss can be reduced.

  That is, the honeycomb catalyst body of the present embodiment can simultaneously solve the problems that are difficult to achieve with the conventional techniques, such as improving the purification efficiency of exhaust gas and suppressing the increase in pressure loss.

The catalyst used in the honeycomb catalyst body of the present embodiment is not particularly limited as long as it can purify harmful substances contained in the exhaust gas. For example, platinum (Pt) and rhodium (Rh) are used as noble metals. And further containing activated alumina and ceria as an oxygen storage agent are preferred. Such a catalyst is particularly effective for purification of harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO _x ).

  The amount of catalyst supported varies depending on the type of catalyst, the size and cell structure of the honeycomb structure used as the catalyst carrier, and the type and amount of exhaust gas to be purified. For example, per 1 L of the honeycomb structure volume Further, it is preferable that 100 to 250 g of catalyst is supported. By comprising in this way, the purification | cleaning efficiency of exhaust gas can be improved and the increase in pressure loss can be suppressed effectively. The catalyst loading is more preferably 150 to 200 g, and particularly preferably 160 to 180 g, per liter of the honeycomb structure volume.

  The amount of the catalyst supported on the inner surface of the pores of the partition walls is preferably equal to or greater than the amount of the catalyst supported on the partition surface. If the catalyst supported on the inner surface of the pores of the partition walls is not equal to or greater than the amount of the catalyst supported on the partition surface, the surface area in the pores cannot be used effectively and the purification rate may deteriorate.

[3-1] Manufacturing method of honeycomb catalyst body:
Next, an example of a method for manufacturing the honeycomb catalyst body of the present embodiment will be described. Note that the method for manufacturing the honeycomb catalyst body of the present embodiment is not limited to the following method.

  First, a honeycomb structure constituting the catalyst carrier of the honeycomb catalyst body of the present embodiment is manufactured. In the honeycomb catalyst body of the present embodiment, since the honeycomb structure of the present invention described so far is used, the honeycomb structure according to one embodiment of the method for manufacturing the honeycomb structure of the present invention described above is used. Can be manufactured.

  Next, the catalyst is supported on the partition wall surfaces of the obtained honeycomb structure and the inner surfaces of the pores of the partition walls. The catalyst loading method is not particularly limited, and the catalyst can be loaded according to a method used in a conventionally known honeycomb catalyst body manufacturing method. For example, after the honeycomb structure is wash-coated with a catalyst solution containing a catalyst component, it can be heat treated at a high temperature and baked.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. Each physical property was measured by the following method.

[Average pore diameter (μm)]: The pore diameter was measured by a mercury porosimeter (mercury intrusion method), and the cumulative volume of mercury injected into the porous substrate is the total pore volume of the porous substrate. It means the pore diameter calculated from the pressure when it becomes 50%. As the mercury porosimeter, the product name: Auto Pore III Model 9405 manufactured by Micromeritics was used.

[Porosity (%)]: Similar to the pore diameter, a mercury porosimeter was used.

[Catalyst loading (g / L)]: The catalyst loading (g / L) per liter of the volume of the honeycomb structure as the catalyst carrier was calculated.

[Platinum group metal loading (g / L)]: The platinum group metal loading (g / L) contained in the catalyst per 1 L volume of the honeycomb structure as the catalyst carrier was calculated. The platinum group metal is configured such that the ratio of platinum (Pt) to rhodium (Rh) (Pt: Rh) is 5: 1.

[Aperture ratio of slit]
In the cross section orthogonal to the cell extending direction, the opening area (slit area) of the opening area reducing member disposed in the first cell and the opening area of the second cell are measured by image analysis. As an application range of the image analysis, an end surface center portion of 5 × 5 cells or more is set as an analysis range, and a portion having the narrowest opening area of the introduction area of the opening area reducing member is measured. Then, the ratio of the “opening area of the opening area reducing member” to the “opening area of the first cell” (opening ratio of the through hole) is calculated. Then, the ratio of the “opening area of the opening area reducing member” to the “opening area of the second cell” (opening ratio of the slit) is calculated.

[Pressure loss (kPa)]: A measurement gas (air) at 25 ° C. and 1 atm was passed through the honeycomb catalyst body to measure the pressures at the end face on the inflow side and the end face on the outflow side. The pressure difference was defined as pressure loss (kPa). Measurements of the pressure, the flow rate of the measurement gas, up to 0.92 nm ³ / min 9.91Nm ³ / min, to increase the flow rate by about 1 Nm ³ / min, was measured a total of 10 times.

[Hazardous component emission (g / mile)]: The measurement of the harmful component emission was performed by disposing the honeycomb catalyst body of each example or comparative example in the exhaust system of a gasoline engine vehicle having a displacement of 2 liters. The engine vehicle was operated in the FTP (US federal regulation, LA-4) operation mode, and the emission amount (g) of harmful components contained in the exhaust gas discharged per mile of the mileage was measured. As harmful components, the amount (g) of hydrocarbon (HC) in the exhaust gas (HC emission amount) and the amount of nitrogen oxide (NO _X ) (g) (NO _X emission amount) were measured. The amount of harmful component discharge was measured when the platinum group metal loading was 1 g / L and when the platinum group metal loading was 2 g / L. In addition, the platinum group metal supported amount of the honeycomb catalyst body of the example is 2 g / L, and the platinum group metal supported amount of the honeycomb catalyst body of the comparative example is 2.5 g / L. In addition, in the honeycomb catalyst bodies of the examples and comparative examples, the platinum group metal loadings were 1 g / L (for the comparative examples, 1 g / L and 2 g / L) were measured and measured.

Example 1
Talc, combined kaolin, calcined kaolin, alumina, aluminum hydroxide, and a plurality from among silica, the chemical _composition, SiO 2: 42 to 56 _{wt%, Al} 2 O 3: _30~45 wt%, and MgO: 10 to 20 parts by mass of graphite was added as a pore former to 100 parts by mass of the cordierite forming raw material prepared at a predetermined ratio so as to be 12 to 16% by mass. Furthermore, after adding appropriate amounts of methyl cellulose and surfactant, the prepared clay was vacuum degassed, and then extrusion molded to obtain a honeycomb formed body. The honeycomb molded body has a partition wall thickness of 200 μm (8 mil) and a cell density of 62 cells / cm ² (400 cpsi). Note that “1 (mil)” is 1/1000 inch, and “cpsi” is “cell / square inch”. The obtained honeycomb formed body includes partition walls that partition and form a plurality of cells.

  Next, a plugged portion (opening area reducing member) was formed in the opening of the end portion on the outflow side of the first cell of the obtained honeycomb formed body to obtain a plugged honeycomb formed body. As the plugging slurry for forming the plugging portion, a slurry in which the cordierite forming raw material and an additive were blended was used. The viscosity of the slurry was adjusted to 180 to 350 dPa · s by preparing the additive. The length of the plugging portion (opening area reducing member) in the cell extending direction (opening area reducing member depth) was 3 mm. The first cells in which the plugged portions are formed and the second cells in which the plugged portions are not formed are alternately arranged.

  Next, parallel slits as shown in FIG. 4 were formed at the end portion on the outflow side of the obtained plugged honeycomb molded body to obtain an aperture area-reduced honeycomb molded body. In this example, the slit was formed so that the aperture ratio (%) of the slit of the opening area reducing member of the first cell was 25%.

Next, the obtained opening area-reduced honeycomb formed body was fired to manufacture a honeycomb structure. Table 1 shows the partition wall thickness (μm), cell density (cell / cm ² ), average pore diameter (μm), and porosity (%) of the honeycomb structure.

Next, a catalyst containing a platinum group metal prepared so that the ratio (Pt: Rh) of platinum (Pt) and rhodium (Rh) is 5: 1 is added to the obtained honeycomb structure. A honeycomb catalyst body was manufactured by supporting the catalyst so that the amount was 160 g / L (Example 1). As the promoter of the supported catalyst, cerium (Ce) oxide (CeO ₂ ) and zirconium (Zr) oxide (ZrO ₂ ) were used. The platinum group metal loading is 2 g / L.

  With respect to the honeycomb catalyst body of Example 1, the above-described opening ratio of the through holes was measured, and the pressure loss and the harmful component discharge amount were measured. Table 1 shows the measurement results of the opening ratio of the through holes, Table 2 shows the measurement results of the pressure loss, and Table 3 shows the measurement results of the harmful component discharge amount.

(Examples 2 and 3)
Except for changing the aperture ratio of the slits as shown in Table 1, a honeycomb structure having the same structure as in Example 1 was manufactured, and the obtained honeycomb structure was subjected to a catalyst by the same method as in Example 1. And honeycomb catalyst bodies were manufactured (Examples 2 and 3). The honeycomb catalyst bodies of Examples 2 and 3 were measured for the aperture ratio of the slit, the pressure loss, and the harmful component discharge amount. The results are shown in Tables 1-3.

(Comparative Example 1)
The honeycomb structure has the partition wall thickness (μm), cell density (cell / cm ² ), average pore diameter (μm), and porosity (%) as shown in Table 1, and penetrates the plugging portion. A honeycomb structure without pores was manufactured, and the resulting honeycomb structure was loaded with a catalyst so that the catalyst loading was 200 g / L, as shown in Table 1, and a honeycomb catalyst body was manufactured ( Comparative Example 1). The platinum group metal loading was 2.5 g / L. The honeycomb catalyst body of Comparative Example 1 was measured for the pressure loss and the harmful component discharge amount. The results are shown in Tables 2 and 3.

(Comparative Examples 2 and 3)
Except for changing the aperture ratio of the slits as shown in Table 1, a honeycomb structure having the same structure as in Example 1 was manufactured, and the obtained honeycomb structure was subjected to a catalyst by the same method as in Example 1. To produce a honeycomb catalyst body (Comparative Examples 2 and 3). The honeycomb catalyst bodies of Comparative Examples 2 and 3 were measured for the aperture ratio of the slit, the pressure loss, and the harmful component discharge amount. The results are shown in Tables 1-3.

(Result 1)
From Tables 2 and 3, it can be seen that the honeycomb catalyst bodies of Examples 1 to 3 have good purification efficiency and small pressure loss. On the other hand, it can be seen that the honeycomb structure of Comparative Example 2 has a large pressure loss because no slit is formed. Further, it can be seen that the honeycomb structure of Comparative Example 3 does not have the opening area reducing member, and therefore the pressure loss is small, but the purification efficiency is low.

(Examples 4 to 6, Comparative Examples 4 and 5)
A honeycomb structure manufactured in the same manner as in Example 2 (aperture ratio of slit 50%) except that the average pore diameter (μm) was changed as shown in Table 4 was obtained. The catalyst was supported on the body by the same method as in Example 1 to produce honeycomb catalyst bodies (Examples 4 to 6, Comparative Examples 4 and 5). With respect to each of the honeycomb catalyst bodies of Examples 4 to 6 and Comparative Examples 4 and 5, the above-described pressure loss measurement and harmful component discharge amount were measured. The results are shown in Tables 5 and 6.

(Result 2)
From Tables 5 and 6, the honeycomb catalyst bodies of Examples 4 to 6 and Comparative Examples 4 and 5 did not have a large difference in pressure loss, but the harmful component discharge amount was the honeycombs of Examples 4 to 6. It can be seen that the amount of harmful components discharged from the structure is small, and the honeycomb structures of Examples 4 to 6 are excellent.

(Examples 7 to 9, Comparative Examples 6 and 7)
Except for changing the average pore diameter (μm) as shown in Table 7, a honeycomb structure having the same structure as in Example 2 (slit opening ratio 50%) was manufactured, and the resulting honeycomb structure was obtained. The catalyst was supported on the body by the same method as in Example 1 to produce honeycomb catalyst bodies (Examples 7 to 9, Comparative Examples 6 and 7). With respect to each of the honeycomb catalyst bodies of Examples 7 to 9 and Comparative Examples 6 and 7, the above-described pressure loss measurement and harmful component discharge amount were measured. The results are shown in Table 8 and Table 9.

(Result 3)
From Tables 8 and 9, the honeycomb catalyst bodies of Examples 7 to 9 and Comparative Examples 6 and 7 did not have a large difference in pressure loss, but the amount of harmful components discharged was the honeycomb of Examples 7 to 9. It can be seen that the honeycomb structure of Examples 7 to 9 is excellent because the amount of harmful component emission from the structure is small.

(Example 10)
Like the honeycomb structure 100 shown in FIG. 2, a honeycomb structure configured in the same manner as in Example 1 except that slits in two orthogonal directions were formed, and the resulting honeycomb structure was A catalyst was supported by the same method as in Example 1 to produce a honeycomb catalyst body (Example 10). Conditions such as the partition wall thickness are shown in Table 1. With respect to the honeycomb catalyst body of Example 10, the above-described pressure loss measurement and harmful component discharge amount measurement were performed. The results are shown in Tables 2 and 3.

(Result 4)
From Tables 2 and 3, when comparing the honeycomb catalyst body of Example 1 and the honeycomb catalyst body of Example 10, the honeycomb catalyst body of Example 10 in which slits are formed in the vertical and horizontal directions (two directions orthogonal). It can be seen that the purification performance is good because the flow flows evenly through the partition walls.

The honeycomb structure according to the present invention supports carbon monoxide (CO) and hydrocarbons contained in exhaust gas discharged from automobiles, construction machines, industrial stationary engines, combustion equipment, and the like by supporting a catalyst. (HC) and nitrogen oxides (NO _x ) can be efficiently purified, and an increase in pressure loss can be effectively suppressed, which can be suitably used as a catalyst carrier of a honeycomb catalyst body. it can.

Moreover, the honeycomb catalyst body of the present example is a carbon monoxide (CO), hydrocarbon (HC) contained in exhaust gas discharged from automobiles, construction machinery, industrial stationary engines, combustion equipment, and the like. It can be suitably used to purify harmful components such as nitrogen oxides (NO _x ).

1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. Fig. 3 is a plan view schematically showing a part of one embodiment of the honeycomb structure of the present invention as seen from the outflow side end face side. It is a schematic diagram which shows the A-A 'cross section of FIG. Fig. 5 is a plan view schematically showing a part of another embodiment of the honeycomb structure of the present invention as seen from the outflow side end face side.

Explanation of symbols

1: partition wall, 2: end face on the inflow side, 3: end face on the outflow side, 4: cell, 4a: first cell, 4b: second cell, 5, 5a, 5b, 5c: row of cells, 6: Opening area reducing member, 7: slit, 11: outer peripheral wall, 100, 200: honeycomb structure, D1: slit depth, D2: opening area reducing member depth.

Claims (6)

Comprising a porous partition wall defining a plurality of cells that serve as fluid flow paths penetrating from the end surface on the inflow side to the end surface on the outflow side;
The partition wall has a porosity of 50 to 80% and an average pore diameter of 13 to 70 μm,
In some of the plurality of cells, an opening area reducing member is formed so that an opening at an end portion on an inflow side is opened and a part of the opening portion is blocked by an opening at an end portion on an outflow side. The first cell disposed, the remaining cell is a second cell having openings at both ends,
The first cells and the second cells are alternately arranged,
A slit is formed in the partition wall and the opening area reducing member so as to cut the cell row vertically in at least one outflow side end portion of the cell row in which the first cells and the second cells are alternately arranged. Formed,
A honeycomb structure in which a depth of the slit in a cell extending direction is deeper than a depth of the opening area reducing member in a cell extending direction.   The honeycomb structure according to claim 1, wherein the row of cells in which the slits are formed is a row of a plurality of cells arranged in parallel with each other on an end face on the outflow side.   The row of cells in which the slits are formed is parallel to each other on the end surface on the outflow side, and the other plurality of cells that are parallel to each other and intersect the row of the plurality of cells arranged in parallel. The honeycomb structure according to claim 1, which is a row of   The lower limit of the depth of the slit in the cell extending direction is 1 mm, and the upper limit is 30 mm or 1/2 of the total length in the cell extending direction, whichever is shorter. The honeycomb structure according to any one of the above.   The honeycomb structure according to any one of claims 1 to 4, wherein the opening area reducing member is made of a porous body having a porosity of 20 to 80%. A honeycomb structure according to any one of claims 1 to 5, and a catalyst supported on the inner surface of the pores of the partition walls of the honeycomb structure and a catalyst supported on the partition wall surfaces,
A honeycomb catalyst body having a catalyst loading of 100 to 250 g / L.

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