Catalyst slurry coating device

Abstract

The present invention relates to a coating device for catalyst slurry. The coating device (10) comprises a supply rack (8) for supplying slurry from one end of a honeycomb substrate (1) to a plurality of flow holes (2) and a blower (7) for evacuating a bellows (12). An annular blocking body (5) is installed at an opening (11b) of the bellows (12), and a honeycomb substrate (1) is arranged above the blocking body (5) via a spacer (6). If the blower (7) is operated to supply slurry, the coating width of the slurry applied to the flow holes (2) located in the peripheral area (2b) of the honeycomb substrate (1) becomes shorter than the coating width of the slurry applied to the flow holes (2) located in the central area (2a) of the honeycomb substrate (1).

Description

[0001] This application is a divisional application of the invention patent application with application number 201680004901.5 (international application number PCT / JP2016 / 057328), application date March 9, 2016, and invention name “Device for coating catalyst slurry”. Technical Field

[0002] The present invention relates to an apparatus for applying a slurry containing a catalytic substance to a honeycomb substrate of a monolithic catalyst for purifying automobile exhaust gas, for example. Background Art

[0003] In the past, as a device for purifying automobile exhaust gas, a purification device using a monolithic catalyst is known. The monolithic catalyst includes a substantially cylindrical honeycomb substrate having a plurality of mutually parallel flow holes for allowing gas to flow in one direction, and a slurry containing a catalytic substance is applied to the inner surface of each flow hole of the honeycomb substrate. In this way, when the exhaust gas passes through the plurality of flow holes of the monolithic catalyst along the axial direction of the honeycomb substrate, the exhaust gas can be purified by a chemical reaction with the catalytic substance.

[0004] Thus, when exhaust gas flows through a cylindrical monolithic catalyst, the flow of exhaust gas in the flow holes near the circumference is generally worse than that in the flow holes located in the center along the radial direction of the monolithic catalyst. Therefore, the exhaust gas purification efficiency near the circumference of the monolithic catalyst is lower than that in the center.

[0005] In order to eliminate the above-mentioned unfavorable conditions, various methods have been considered to improve the purification efficiency of exhaust gas, such as making the coating amount of slurry in the center of the honeycomb substrate greater than that in the periphery during the manufacture of the catalyst. For example, according to the coating device disclosed in Japanese Patent Publication No. 2009-136833, a barrier such as a mesh body or a plate body is arranged on the supply side of the slurry of the honeycomb substrate, so that the flow in the periphery is worse than that in the center, resulting in a difference in the coating amount of the slurry in the center and the periphery. Summary of the invention

[0006] However, if a barrier is arranged on the supply side of the slurry to the honeycomb substrate as in the coating device of Japanese Patent Publication No. 2009-136833, the slurry will adhere to and remain on the barrier, and the consumption of the slurry will increase accordingly. Since the catalytic substance contained in the slurry includes precious metals such as platinum and palladium, if the consumption of the slurry increases, the manufacturing cost of the monolithic catalyst will increase. In addition, if the amount of slurry attached to the barrier is uneven, the amount of slurry applied to the honeycomb substrate will be uneven, thereby causing unevenness in the quality of the monolithic catalyst.

[0007] Furthermore, when the slurry attached to the barrier dries and solidifies, and the dried slurry lumps are mixed into the liquid slurry, the lumps enter the plurality of flow holes of the honeycomb substrate and clog them, thereby reducing the performance and quality of the monolithic catalyst.

[0008] Furthermore, when a barrier is disposed on the supply side of the slurry, the inorganic oxide contained in the slurry acts as an abrasive to cut the barrier, and the barrier needs to be replaced after a while, which increases the manufacturing cost of the monolithic catalyst accordingly.

[0009] An object of the present invention is to provide a coating device for a catalyst slurry capable of producing a monolithic catalyst having good quality and high performance at low cost.

[0010] The coating device of the catalyst slurry of the present invention is a device for coating the inner surface of a plurality of flow holes that penetrate a substrate in a first direction and extend adjacent to each other with a slurry containing a catalytic substance, and comprises: a supply mechanism that supplies the slurry to the plurality of flow holes from one end side of the substrate along the first direction; an airflow generating mechanism that generates an airflow that flows through the plurality of flow holes from one end side of the substrate toward the other end side along the first direction, so that the slurry supplied by the supply mechanism from one end side of the substrate is sent to the other end through the plurality of flow holes, so that the slurry reaches the middle of the entire length of the substrate along the first direction from one end of the substrate; and an airflow suppressing mechanism that is spaced apart from the other end of the substrate and is arranged relative to the downstream end of several first flow holes among the plurality of flow holes along the first direction, so that the flow of air flowing through the first flow holes is slower than the flow of air flowing through the other second flow holes. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram which shows the coating apparatus which concerns on embodiment.

[0012] Figure 2 It means investment Figure 1 A perspective view of an example of a coating device for a honeycomb substrate.

[0013] Figure 3 Is installed in Figure 1 A top view of a circular web in a coating device.

[0014] Figure 4 Is installed in Figure 1 A top view of a ring-shaped plate in a coating device.

[0015] Figure 5 It means use Figure 3 The network or Figure 4 The table shows examples of combinations when the thickness of the spacer is changed.

[0016] Figure 6 Is based on Figure 5 The table is a graph showing the relationship between the coating width difference of the slurry.

[0017] Figure 7 It is based on the actual honeycomb substrate. Figure 5 Table Figure 6 A cross-sectional view showing an example of a coating width difference.

[0018] Figure 8 This is a diagram showing changes in the difference in the slurry coating width when the parameters (aperture ratio) of the coating device are changed.

[0019] Fig. 9 This is a diagram showing changes in the difference in the slurry coating width when the parameters of the coating device (diameter of the flow hole) are changed.

[0020] Fig.10 This is a diagram showing changes in the difference in the slurry coating width when the parameters (gap) of the coating device are changed.

[0021] Fig.11 This is a diagram showing changes in the difference in the slurry coating width when the parameters (suction air speed) of the coating device are changed.

[0022] Fig.12 This is a diagram showing changes in the difference in the slurry coating width when the parameters (suction time) of the coating device are changed.

[0023] Fig.13 This is a diagram showing changes in the difference in the slurry coating width when the parameters of the coating device (the viscosity of the slurry) are changed.

[0024] Fig.14 This is a diagram showing changes in the difference in the slurry coating width when the parameters of the coating device (the amount of slurry supplied) are changed.

[0025] Fig.15 It means investment Figure 1 A perspective view of another example of a coating device for a honeycomb substrate.

[0026] Fig.16 It means for Fig.15 A cross-sectional view of the coating shape when the slurry is coated on the honeycomb substrate without providing a barrier.

[0027] Fig.17 It means for Fig.15 A cross-sectional view of the coating shape of a honeycomb substrate when the slurry is coated in a state where a barrier is provided. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

[0029] Figure 11 is a schematic diagram showing an example of a coating device 10 for coating a slurry on the inner surface of a plurality of flow holes of a honeycomb substrate 1. The slurry, for example, contains a catalytic substance for purifying automobile exhaust gas. The catalytic substance contains precious metals such as platinum and palladium. The coating device 10 of this embodiment is a device for manufacturing a monolithic catalyst for purifying automobile exhaust gas.

[0030] For automobile exhaust gas, the flow distribution of exhaust gas flowing through the integral catalyst varies with the type of vehicle, and the flow pattern of exhaust gas also changes with the shape of the catalyst shell and the bending of the piping. Therefore, in order to improve the purification efficiency of exhaust gas, it is preferred to design the coating shape of the slurry on the honeycomb substrate 1 to match the type of vehicle, the installation position of the catalyst, etc. The coating device 10 of this embodiment is a device that can control the coating shape of the slurry on the honeycomb substrate 1.

[0031] The honeycomb substrate 1 is, for example, Figure 2 As shown, the honeycomb has a substantially cylindrical outer shape and has a plurality of flow holes 2 penetrating the honeycomb substrate 1 in the axial direction. Figure 1 In order to make the description easier to understand, a plurality of flow holes 2 that are not actually observed are indicated by solid lines. The plurality of flow holes 2 are arranged to extend parallel to each other and adjacent to each other along the axial direction. In this embodiment, the cross-sectional area of ​​all the flow holes 2 is designed to be the same. The cross-sectional shape of each flow hole 2 can be made into any shape such as a circle or a hexagon. In addition, the honeycomb substrate 1 can be made of ceramics such as cordierite or stainless steel.

[0032] The coating device 10 has a support 11 that supports the axial lower end 1b of the honeycomb substrate 1. The interior of the support 11 is a cavity, and the support 11 having the cavity functions as a wind box 12. A circular opening 11b is formed on the upper surface 11a of the support 11 and communicates with the cavity of the wind box 12. In the opening 11b, a Figure 3 The circular ring-shaped net 3 (net-shaped member) shown, or Figure 4 The blocking body 5 (airflow suppression mechanism) such as the circular plate 4 (plate-shaped member) shown in the figure is provided. In addition, in order to arrange the honeycomb substrate 1 at a distance from the blocking body 5 upward as shown in the figure, a circular plate-shaped spacer 6 (adjustment mechanism) is arranged between the blocking body 5 and the lower end 1b of the honeycomb substrate 1. That is, by changing the thickness of the spacer 6, the distance between the blocking body 5 and the lower end 1b of the honeycomb substrate 1 can be changed.

[0033] The coating device 10 further includes a blower 7 (airflow generating mechanism) for evacuating the cavity of the wind box 12. In the present embodiment, the blower 7 is used as the airflow generating mechanism, but the airflow flowing through the plurality of flow holes 2 may be generated by supplying compressed air from the upper end 1a side of the honeycomb substrate 1 to the plurality of flow holes 2.

[0034] When the blower 7 is operated in a state where the honeycomb substrate 1 is placed on the support 11 with the spacer 6 interposed therebetween, the cavity of the wind box 12 is sucked to generate negative pressure at the opening 11b, and an airflow is generated from the upper end 1a of the honeycomb substrate 1 toward the lower end 1b through the plurality of flow holes 2. At this time, if the slurry is supplied via the funnel-shaped supply rack 8 (supply mechanism) mounted on the upper end 1a of the honeycomb substrate 1, the slurry is sucked from the upper end 1a side of the honeycomb substrate 1 into the plurality of flow holes 2, and the slurry is applied to the inner surface of each flow hole 2.

[0035] The supply amount of the slurry is set to an amount that reaches the middle of the entire length of the plurality of flow holes 2 when the entire amount of the slurry supplied at once via the supply rack 8 is applied to the flow holes 2 of the honeycomb substrate 1. That is, according to the coating device 10 of the present embodiment, the slurry does not flow out from the lower end 1b of the honeycomb substrate 1, and the barrier 5 is not wetted by the slurry. Therefore, there is basically no waste of slurry, and the cost can be reduced accordingly.

[0036] The spacer 6 has a circular opening 6a having a diameter substantially the same as the outer diameter of the honeycomb substrate 1. In addition, the support 11 also has a circular opening 11b having a diameter substantially the same as the outer diameter of the honeycomb substrate 1. Therefore, if the blower 7 is operated without the blocking body 5 being installed at the opening 11b of the support 11, the speed of the airflow flowing through all the flow holes 2 of the honeycomb substrate 1 will be the same, and the coating width of the slurry to all the flow holes 2 will be substantially the same. It should be noted that the coating width of the slurry mentioned here is the distance from the upper end 1a of the honeycomb substrate 1 to the position where the slurry reaches.

[0037] On the other hand, if the annular stopper 5 is installed in the opening 11b of the support platform 11 as in the present embodiment ( Figure 1 When the blower 7 is operated in a state of being filled with air (i.e., the slurry is supplied), the suction force for sucking the slurry into the flow holes 2 (first flow holes) in the outer peripheral region 2b located on the radially outer side of the honeycomb substrate 1 is weaker than the suction force for sucking the slurry into the flow holes 2 (second flow holes) in the central region 2a located near the radial center of the honeycomb substrate 1. As a result, a difference is generated between the coating width of the slurry into the flow holes 2 located in the central region 2a of the honeycomb substrate 1 and the coating width of the slurry into the flow holes 2 located in the outer peripheral region 2b.

[0038] That is, the barrier 5 has an opening 5a having a diameter smaller than the outer diameter of the honeycomb substrate 1, and faces the flow holes 2 (first flow holes) located in the radially outer side, that is, the outer peripheral region 2b of the honeycomb substrate 1. Thus, the opening 5a of the barrier 5 faces the flow holes 2 (second flow holes) located in the radially inner side, that is, the central region 2a of the honeycomb substrate 1. As a result, the velocity of the airflow flowing through the flow holes 2 in the outer peripheral region 2b facing the barrier 5 is slower than that of the flow holes 2 in the central region 2a, and the coating width of the slurry is shorter in the outer peripheral region 2b than in the central region 2a.

[0039] In order to control the coating width difference (the difference in coating width of the slurry in the peripheral area 2b and the central area 2a of the honeycomb substrate 1) to a desired value, the inventors of the present application measured the coating width difference when the type of the barrier 5 (net 3 or plate 4) and the thickness of the spacer 6 (the distance between the honeycomb substrate 1 and the barrier 5) were variously changed, and examined the influence of the type of the barrier 5 and the thickness of the spacer 6 on the coating width difference. The combination examples of the type of the barrier 5 and the thickness of the spacer 6 at this time are shown in Figure 5 In addition, the measurement results of the coating width difference at this time are shown in Figure 6 middle.

[0040] In addition, other measurement conditions were set as follows.

[0041] ·Outer diameter of honeycomb substrate 1: 103 mm

[0042] The outer diameter of the blocking body 5 is 103 mm, the inner diameter of the opening 5a is 60 mm

[0043] ·Mesh size of net 3: 250 mesh

[0044] Solid content of slurry: 30%, viscosity: 0.4s-1…4000mPa·s, coating amount: 250g

[0045] · Blower 7 suction time: 5 sec, wind speed: 40 m / s

[0046] The wind speed of the airflow generated by the blower 7 is a value measured before the slurry is added.

[0047] Under the above conditions, after the slurry was applied to the honeycomb base material 1 and dried, the honeycomb base material 1 was cut at the center along the longitudinal direction (first direction) to actually measure the difference in the width of the slurry applied.

[0048] As a result, if Figure 6As shown, in both the case where the plate 4 is provided as the barrier 5 and the case where the net 3 is provided, if the distance (gap) between the lower end 1b of the honeycomb substrate 1 and the barrier 5 (i.e., the thickness of the spacer 6) is reduced, the coating width difference tends to increase, and if the distance between the two is increased, the coating width difference tends to decrease. This is considered to be because, by bringing the barrier 5 close to the honeycomb substrate 1, the flow of the airflow at the outlet of the flow hole 2 in the peripheral area 2b facing the barrier 5 becomes worse.

[0049] In other words, it can be seen that the difference in coating width can be controlled by changing the distance between the lower end 1b of the honeycomb substrate 1 and the barrier 5, that is, the thickness of the spacer 6. That is, in this case, for the flow holes 2 in the central region 2a facing the opening 5a which are not affected by the barrier 5, the coating width of the slurry does not change with the thickness of the spacer 6, and only the coating width in the flow holes 2 in the peripheral region 2b changes according to the thickness of the spacer 6. However, it can be seen that if the barrier 5 is spaced 30 mm or more from the honeycomb substrate 1, there is basically no change compared to the case where the barrier 5 is not provided.

[0050] In addition, when the mesh 3 is used as the barrier 5, the mesh 3 may be arranged in contact with the honeycomb substrate 1 without using the separator 6, but when the plate 4 is used, it is necessary to space it from the lower end 1b of the honeycomb substrate 1. However, even when the mesh 3 is used, it is not preferable to arrange it in contact with the lower end of the honeycomb substrate 1.

[0051] That is, if the net 3 is brought into contact with the lower end 1b of the honeycomb substrate 1, the honeycomb substrate 1 may be broken or damaged. In order to prevent the damage of the honeycomb substrate 1, a method of slowing down the speed of contacting the net 3 when the honeycomb substrate 1 is placed (making it contact slowly) may be considered, but this will result in a longer production cycle and reduced productivity. In addition, a method of making the raw material of the net 3 softer than the honeycomb substrate 1 may also be considered, but the rigidity of the net 3 is reduced and it becomes easy to deform, and there is a possibility that it will not function satisfactorily as the barrier 5.

[0052] Therefore, in the present embodiment, the barrier 5 (even if it is the net 3) is arranged at least at a distance from the lower end 1b of the honeycomb substrate 1. As described above, in order to form the coating width difference, the distance from the lower end 1b of the honeycomb substrate 1 to the barrier 5 is greater than 0 mm and less than 30 mm. However, in practice, if the distance is greater than 15 mm, the coating width difference is less than 10 mm. Therefore, it is preferred that the barrier 5 does not contact the honeycomb substrate 1 and the distance between the two is within 20 mm.

[0053] In addition, if Figure 6As shown in FIG. 1 , it can be seen that when the mesh 3 and the plate 4 are used as the barrier 5, if the thickness of the spacer 6 is the same, the coating width difference becomes larger when the plate 4 is used than when the mesh 3 is used. This is considered to be because the mesh 3 allows airflow to pass through, while the plate 4 does not. In other words, it is effective to use the plate 4 as the barrier 5 in order to form a larger coating width difference. For example, in the case of Figure 6 In the example shown in FIG. 1 , in which the plate 4 is arranged 1.8 mm away from the lower end 1b of the honeycomb substrate 1, the difference in coating width is the largest, and the effect of suppressing the flow of the airflow is the largest. The actual coating shape of the honeycomb substrate 1 at this time is shown in FIG. Figure 7 middle.

[0054] On the other hand, Figure 6 As shown, it can be seen that in the example where the coarse 200-mesh net 3 is arranged in contact with the lower end 1b of the honeycomb substrate 1, the coating width difference is less than 5 mm, and the net 3 basically does not function as a barrier 5. That is, the net 3 basically does not function as a barrier 5 unless the net 3 has a mesh size of less than 200 mesh.

[0055] According to the above results, it can be seen that in order to control the difference in coating width, it is only necessary to appropriately select the type of the barrier 5 (including the mesh size of the net) and appropriately set the thickness of the separator 6. In addition, the coating shape of the slurry on the honeycomb substrate 1 can of course be arbitrarily changed by changing the shape of the barrier 5 and the arrangement position of the barrier 5 in the plane direction orthogonal to the axial direction of the honeycomb substrate 1.

[0056] Next, other conditions affecting the difference in coating width are examined. In addition to the gap between the barrier 5 and the honeycomb substrate 1 and the type of the barrier 5, the parameters affecting the difference in coating width include the opening ratio of the barrier 5 (plate 4'), the diameter of the flow hole 2 of the honeycomb substrate 1, the suction wind speed of the blower 7, the suction time, the viscosity of the slurry, the coating amount of the slurry, and the like.

[0057] The following basic conditions were simulated: a honeycomb substrate 1 having an outer diameter of 103 mm and an axial length of 83 mm was placed in a coating device 10, a plate 4' (not shown) having a plurality of openings (0.8 mmφ) was arranged 3 mm apart from the lower end 1b of the honeycomb substrate 1, 180 g of slurry having a viscosity of 130 mPas was supplied, and the blower 7 was operated at a suction wind speed of 40 m / s and a suction time of 3 seconds. In addition, the opening ratio of the plate 4' (the ratio of the total area of ​​the openings to the area of ​​the plate 4' excluding the openings 5a) was set to 30%. The simulation result of the coating width difference when the slurry was coated under the basic conditions was 13.6 mm.

[0058] After that, the above parameters were changed one by one to examine the change in coating width difference. The results are shown in Figure 8 to Figure 14 middle.

[0059] like Figure 8 As shown, if the opening ratio of the plate 4' is reduced (i.e., the number of opening holes is reduced), the airflow through the opening holes of the plate 4' becomes less, and the difference in coating width becomes larger. On the contrary, if the opening ratio of the plate 4' is increased, the airflow through the opening holes of the plate 4' becomes more, and the difference in coating width becomes smaller. In addition, it can be seen that if the opening ratio of the plate 4' is reduced to reduce the flow of airflow through the opening holes, the step shape between the coating part of the slurry to the flow holes 2 in the central area 2a of the honeycomb substrate 1 and the coating part of the slurry to the flow holes 2 in the peripheral area 2b becomes steep, and if the opening ratio of the plate 4' is increased to increase the flow of airflow through the opening holes, the above-mentioned step shape becomes gentle.

[0060] like Fig. 9 As shown, even if the diameter of the opening holes of the plate 4' is changed (the opening ratio is constant), there is basically no change in the difference in the coating width.

[0061] like Fig.10 As shown, if the gap between the lower end 1b of the honeycomb substrate 1 and the plate 4' is reduced, the flow of the airflow in the flow hole 2 opposite to the plate 4' becomes worse, and the difference in coating width becomes larger. On the contrary, if the gap between the lower end 1b of the honeycomb substrate 1 and the plate 4' is increased, the air easily flows through the flow hole 2 opposite to the plate 4', and the difference in coating width becomes smaller. In addition, it can be seen that if the gap between the plate 4' and the honeycomb substrate 1 is reduced, the step shape between the coating part of the slurry to the flow hole 2 in the central area 2a of the honeycomb substrate 1 and the coating part of the slurry to the flow hole 2 in the peripheral area 2b becomes steep, and if the gap between the plate 4' and the honeycomb substrate 1 is increased, the above-mentioned step shape becomes gentle.

[0062] like Fig.11 As shown, if the suction wind speed of the blower 7 is slowed down, the airflow flowing through the flow hole 2 opposite to the opening 5a of the plate 4' also becomes slower, and the difference in coating width becomes smaller. On the contrary, if the suction wind speed of the blower 7 is increased, the airflow flowing through the flow hole 2 opposite to the opening 5a of the plate 4' also becomes faster, and the difference in coating width becomes larger. It can also be seen that if the suction wind speed of the blower 7 is slowed down, the step shape between the coating part of the flow hole 2 of the central area 2a of the honeycomb substrate 1 with the slurry and the coating part of the flow hole 2 of the peripheral area 2b with the slurry becomes gentle, and if the suction wind speed of the blower 7 is increased, the above-mentioned step shape becomes steeper.

[0063] like Fig.12 As shown, if the suction time of the blower 7 is shortened, the amount of airflow (air volume) generated also changes, and the coating width difference becomes smaller. On the contrary, if the suction time of the blower 7 is prolonged, the amount of airflow (air volume) generated also changes, and the coating width difference becomes larger.

[0064] like Fig.13 As shown, if the viscosity of the slurry is reduced, the slurry easily flows through the flow holes 2 opposite to the opening 5a of the plate 4, and the coating width difference becomes larger. On the contrary, if the viscosity of the slurry is increased, the speed at which the slurry flows through the flow holes 2 opposite to the opening 5a of the plate 4 becomes slower, and the coating width difference becomes smaller.

[0065] like Fig.14 As shown, when the supply amount of the slurry is changed, there is basically no change in the coating width difference.

[0066] As described above, according to the present embodiment, after the various parameters of the coating device 10 are set to appropriate values, the difference in coating width between the flow holes 2 in the central region 2a and the peripheral region 2b of the honeycomb substrate 1 can be controlled to a desired value by, for example, adjusting only the thickness of the spacer 6. Thus, a monolithic catalyst with good quality and high performance can be manufactured at a low cost using a simple configuration.

[0067] In the above-mentioned embodiment, since the airflow through the flow holes 2 of the peripheral region 2b of the honeycomb substrate 1 is slower than the airflow through the flow holes 2a of the central region 2a, the coating width of the slurry to the flow holes 2 of the peripheral region 2b is smaller than that of the central region 2a. However, it is effective to preferably make the speed of the airflow through the flow holes 2 of the peripheral region 2b the same as the speed of the airflow through the flow holes 2 of the central region 2a. Therefore, a method of making the diameter of the flow holes 2 of the peripheral region 2b larger than the diameter of the flow holes 2 of the central region 2a can be considered.

[0068] In recent years, monolithic catalysts have been developed in which the diameter of the flow holes 2 in the outer peripheral region 2 b of the honeycomb substrate 1 is larger than the diameter of the flow holes 2 in the central region 2 a.

[0069] Fig.15 An example of a honeycomb substrate 21 is shown in which the diameter of the flow holes 22 located in the central region 2a is small, and the diameter of the flow holes 24 in the outer peripheral region 2b surrounding the outer side of the flow holes 22 is large. The honeycomb substrate 21 has the same structure and the same dimensions as the above-mentioned honeycomb substrate 1, except that the diameters of the flow holes 22 in the central region 2a and the flow holes 24 in the outer peripheral region 2b are different. Specifically, 600 flow holes 22 in the central region 2a are provided in a 1-inch square, and 400 flow holes 24 in the outer peripheral region 2b are provided in a 1-inch square.

[0070] In this way, if the diameter of the flow holes 24 in the peripheral area 2b is made larger than the diameter of the flow holes 22 in the central area 2a, the air flow in the flow holes 24 in the peripheral area 2b can flow easily, and the speed of the air flow flowing through the flow holes 22 in the central area 2a can be made approximately the same as the speed of the air flow flowing through the flow holes 24 in the peripheral area 2b.

[0071] However, if the honeycomb substrate 21 is placed in the coating device 10, and the blocking body 5 is not used, so that the airflow is generated in all the flow holes 22 and 24 to supply the slurry, the flow of the slurry in the flow holes 24 of the outer peripheral area 2b becomes better than that in the flow holes 22 of the central area 2a. Fig.16 As shown, the coating width of the slurry in the flow holes 24 of the outer peripheral region 2b is larger than the coating width of the slurry in the flow holes 22 of the central region 2a.

[0072] In contrast, if Fig.15 The honeycomb substrate 21 is placed in the coating device 10, the barrier 5 is installed in the device to supply the slurry, and the blower 7 is operated to perform suction. Fig.17 As shown, the coating width of the slurry in the flow holes 22 located in the central area 2a and the coating width of the slurry in the flow holes 24 located in the peripheral area 2b can be made to be approximately the same length. In other words, after the above-mentioned various parameters of the coating device 10 are set to appropriate values, for example, only by adjusting the thickness of the spacer 6, the coating width of the slurry can be made the same in the central area 2a and the peripheral area 2b. In this embodiment, the cross-sectional area of ​​the flow holes 24 in the peripheral area 2b is designed to be about 1.5 times the cross-sectional area of ​​the flow holes 22 in the central area 2a so that the coating width of the slurry is the same in all the flow holes 22 and 24, but the optimal area ratio varies depending on the opening rate of the barrier 5 and the thickness of the spacer 6.

[0073] In addition, as other integral catalysts, catalysts in which different types (or the same type) of slurries are applied from both ends of the honeycomb substrate in the axial direction are becoming popular. The coating device 10 of the present embodiment is also useful as a manufacturing device for such integral catalysts. That is, in the case of manufacturing such integral catalysts, since the coating width of the slurry applied from one end side of the honeycomb substrate and the coating width of the slurry applied from the other end side are related to each other, it is effective to control the coating width.

[0074] The above-mentioned embodiment does not limit the present invention, but is given as an example, and does not limit the scope of the invention. Therefore, the above-mentioned embodiment can be variously modified within the scope not departing from the gist of the invention.

[0075] For example, in the above-mentioned embodiment, a case where a barrier such as a mesh or a plate is provided at intervals from the downstream side of the honeycomb substrate along the supply direction of the slurry so that the speed of the airflow passing through the flow hole is different is described, but it is not limited to this, and any method can be used as long as it is a method that can suppress the airflow of the flow hole without contacting the slurry. In addition, in the above-mentioned embodiment, a case where a circular barrier is made to face the honeycomb substrate is described, but the shape of the barrier can be any shape as long as it is set to face the flow hole intended to reduce the coating width of the slurry.

Claims

1. A coating device for coating a slurry containing a catalytic substance onto the inner surfaces of a plurality of flow holes of a substrate having a plurality of flow holes penetrating in the axial direction, wherein: The cross-sectional area of ​​the flow holes in the outer peripheral region of the plurality of flow holes is larger than the cross-sectional area of ​​the flow holes in the central region, The coating device has: a supply mechanism for supplying a predetermined amount of slurry from one end surface of the substrate orthogonal to the axial direction to the plurality of flow holes, wherein the predetermined amount refers to an amount of slurry that reaches halfway along the entire length of the plurality of flow holes when the entire amount of slurry supplied at one time is applied to the inner surfaces of the plurality of flow holes; an airflow generating mechanism for generating an airflow from the one end surface of the substrate toward the other end surface through the plurality of flow holes, so that the slurry is coated on the inner surfaces of the plurality of flow holes; an annular member, which is arranged opposite to the outer peripheral area of ​​the other end surface at a distance from the other end surface of the substrate and has a plurality of opening holes, wherein the flow of air flowing through the flow holes in the outer peripheral area is made slower than the flow of air flowing through the flow holes in the central area, thereby making the slurry coating width along the axial direction of the inner surface of the flow holes in the outer peripheral area the same as the slurry coating width along the axial direction of the inner surface of the flow holes in the central area; and The adjusting mechanism is used to change the distance between the other end surface of the substrate and the annular member.

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