阅读说明：本技术 排气净化装置的制造方法 (Method for manufacturing exhaust gas purification device ) 是由 城户佑树 松井优 小原惠津子 中田和真 于 2019-11-08 设计创作，主要内容包括：本发明涉及排气净化装置的制造方法,包括从喷头向蜂巢基材的上部提供含催化剂金属溶液的步骤、向所述蜂巢基材涂覆所述溶液的步骤及对由所述溶液涂覆后的蜂巢基材进行烧成的步骤,其中,所述喷头具有用于排出所述溶液的多个排出口及包围所述多个排出口的防护件。(The present invention relates to a method for manufacturing an exhaust gas purifying device, including a step of supplying a solution containing a catalyst metal from a head to an upper portion of a honeycomb base material, a step of applying the solution to the honeycomb base material, and a step of firing the honeycomb base material coated with the solution, wherein the head has a plurality of discharge ports for discharging the solution and a guard surrounding the plurality of discharge ports.)

1. A method of manufacturing an exhaust gas purification device, comprising:

a step of supplying a catalyst metal-containing solution from a nozzle to an upper portion of the honeycomb substrate;

a step of applying the solution to the honeycomb substrate; and

a step of firing the honeycomb substrate coated with the solution,

wherein the head has a plurality of discharge ports for discharging the solution and a guard surrounding the plurality of discharge ports.

2. The method of manufacturing an exhaust gas purification device according to claim 1,

the guard protrudes from the discharge port of the head by a length of 5mm or more.

3. The method of manufacturing an exhaust gas purification device according to claim 1 or 2,

the average distance between the guard and the discharge port closest to the guard is 1mm or more and 20mm or less.

4. The method for manufacturing an exhaust gas purification device according to any one of claims 1 to 3,

the average pore diameter of the discharge port is 0.3mm to 3 mm.

5. The method for manufacturing an exhaust gas purification device according to any one of claims 1 to 4,

the discharge port of the head is in the convex portion of the head.

6. The method for manufacturing an exhaust gas purification device according to any one of claims 1 to 5,

shear rate of the solution 4s^-1The viscosity at that time is 1 mPas or more and 20000 mPas or less.

7. The method for manufacturing an exhaust gas purification device according to any one of claims 1 to 6,

comprising the step of using a guide member for preventing the solution from leaking out from the upper portion of the honeycomb base material when the supply of the solution from the shower head is performed.

Technical Field

The present invention relates to a method for manufacturing an exhaust gas purification device. In particular, the present invention relates to a method for manufacturing an exhaust gas purification apparatus capable of performing uniform coating over a long period of time by preventing occurrence of clogging at a discharge port of a head (nozzle) for supplying a catalyst metal-containing solution.

Background

The exhaust gas purifying device includes, for example, a honeycomb substrate and a catalyst layer formed on the honeycomb substrate. Such an exhaust gas purifying device is manufactured by, for example, "applying a catalyst metal-containing solution for forming a catalyst layer to a honeycomb base material, and then drying and firing (firing) the honeycomb base material.

For example, patent document 1 discloses such an apparatus for applying a catalyst metal-containing solution to a honeycomb substrate. In patent document 1, after a catalyst metal-containing solution is supplied to a solution reservoir at the upper part of a honeycomb substrate, the liquid level of the solution stored in the solution reservoir is made uniform by a uniformizing mechanism. Then, the solution stored in the solution storage unit is sucked from the lower portion side of the honeycomb base material, thereby uniformly applying the solution to the honeycomb base material.

Patent document 2 discloses a head for supplying a highly viscous solution to the upper part of a honeycomb base material. Patent document 2 discloses a head that can reliably discharge a solution from a discharge port located at an end surface portion of the head. By using such a head, the discharged solution can be prevented from accumulating only in the center of the upper part of the honeycomb base material, and thus the solution can be uniformly applied to the honeycomb base material.

The inventions described in patent documents 1 and 2 are mainly suitable for coating a honeycomb substrate with a high-viscosity solution.

Patent document 3 discloses a method for manufacturing an exhaust gas purification device capable of uniformly applying a solution to a honeycomb substrate even when a low-viscosity solution is used.

Fig. 5 shows an example of a method for coating a honeycomb substrate according to the conventional technique. In the method, a solution (20) is supplied from a spray head (10) to an upper portion of a honeycomb base material (30). At this time, the solution (20) is prevented from leaking from the upper part of the honeycomb base material (30) and the solution (20) from flowing down on the outer side surface of the honeycomb base material (30) by using the guide (40) as required. The honeycomb base material (30) is placed on the support body (50), and the duct (60) is connected to the support body (50). The solution (20) is applied to the honeycomb base material (30) by sucking the solution (20) stored on the upper portion of the honeycomb base material (30) through the duct (60). In the method of fig. 5, the step of supplying the solution (20) from the head (10) and the step of sucking the solution (20) through the pipe (60) are performed in the same working place, but these steps may be performed in different working places.

In recent years, it has been studied to use the ceria-zirconia composite oxide particles as the co-catalyst particles not only for the catalyst layer but also for 1 type of the constituent material of the honeycomb substrate. For example, patent document 4 discloses an exhaust gas purification device in which a honeycomb substrate includes ceria-zirconia composite oxide particles.

These documents are incorporated into the present specification by reference thereto. Such a honeycomb substrate and an exhaust gas purifying device are also disclosed in patent documents 5 and 6.

Disclosure of Invention

Problems to be solved by the invention

The prior art has the following problems: if the solution is continuously supplied for a long period of time, the discharge port of the head is clogged, and the solution cannot be supplied from the clogged portion, and as a result, uniform coating on the honeycomb base material cannot be performed.

Accordingly, an object of the present invention is to provide a method for manufacturing an exhaust gas purifying device capable of performing uniform coating over a long period of time.

Means for solving the problems

The inventors of the present application have found that: the present invention having the following configuration can solve the above problems.

Scheme 1

A method of manufacturing an exhaust gas purification device, comprising:

a step of supplying a catalyst metal-containing solution from a nozzle to an upper portion of the honeycomb substrate;

a step of applying the solution to the honeycomb substrate; and

a step of firing the honeycomb substrate coated with the solution,

wherein the head has a plurality of discharge ports for discharging the solution and a guard surrounding the plurality of discharge ports.

Scheme 2

The method of manufacturing an exhaust gas purifying apparatus according to claim 1, wherein the protector protrudes from the discharge port of the head by a length of 5mm or more.

Scheme 3

The method of manufacturing an exhaust gas purification device according to claim 1 or 2, wherein an average distance between the guard and the discharge port closest to the guard is 1mm or more and 20mm or less.

Scheme 4

The method of manufacturing an exhaust gas purification device according to any one of claims 1 to 3, wherein an average pore diameter of the discharge port is 0.3mm or more and 3mm or less.

Scheme 5

The method of manufacturing an exhaust gas purifying apparatus according to any one of claims 1 to 4, wherein the discharge port of the head is located in a convex portion of a surface of the head.

Scheme 6

The method for manufacturing an exhaust gas purifying apparatus according to any one of aspects 1 to 5, wherein the shear rate of the solution is 4s^-1The viscosity at that time is 1 mPas or more and 20000 mPas or less.

Scheme 7

The method of manufacturing an exhaust gas purification device according to any one of claims 1 to 6, including a step of using a guide for preventing leakage of the solution from an upper portion of the honeycomb base material when the supply of the solution from the head is performed.

Drawings

Fig. 1 shows a schematic view of 1 variant of a device for applying a catalyst-containing metal solution to a honeycomb substrate, which is used in the method according to the invention.

Fig. 2(a) shows a bottom view of 1 version of the head used in the manufacturing method of the present invention, and fig. 2 (b) shows a perspective view of the head of fig. 2 (a).

Fig. 3 shows 1 embodiment of the head in which the discharge port used in the manufacturing method of the present invention is present in the convex portion.

Fig. 4 is a schematic view showing an example of a head having a rectifying plate.

Fig. 5 shows a schematic view of 1 option of a previously used device for applying a catalyst metal-containing solution to a honeycomb substrate.

Fig. 6 shows a schematic diagram of an evaluation device used in the examples.

Fig. 7 shows a measurement method of the size of the shield member of the head used in the embodiment.

Detailed Description

The method for manufacturing an exhaust gas purification device of the present invention includes a step of supplying a catalyst-containing metal solution from a nozzle to an upper portion of a honeycomb base material, a step of applying the catalyst-containing metal solution to the honeycomb base material, and a step of firing the honeycomb base material coated with the solution. The head used in the present invention has a plurality of discharge ports for discharging the catalyst metal-containing solution and a guard member surrounding the plurality of discharge ports.

In the manufacturing method of the exhaust gas purifying device according to the related art, if the catalyst metal-containing solution is continuously supplied for a long period of time, the discharge port of the head may be clogged, and in this case, the solution cannot be supplied from the portion where the clogging has occurred, and as a result, uniform coating on the honeycomb base material cannot be performed. In contrast, the inventors of the present application have made various studies on the cause thereof. For example, the time from the supply of a solution to a honeycomb substrate to the supply of a solution to the next honeycomb substrate, the speed of supplying the solution, the composition and viscosity of the solution, the coagulation of the solution, the conditions of suction, the production environment, and the like have been studied.

Among them, the inventors of the present application found that: when the exhaust gas purifying device is manufactured in a low humidity environment, the discharge port of the head is particularly likely to be clogged. Then, the inventors of the present application further studied and found that: by providing the guard surrounding the discharge port in the head, the vicinity of the discharge port is kept in a moisture-retaining environment, and even if the exhaust gas purifying device is manufactured in a low-humidity environment, clogging of the discharge port of the head can be prevented.

In this method, as shown in fig. 1, a guard member (11) is present in a showerhead (10) that provides a catalyst metal-containing solution (20). The solution (20) is supplied from a head (10) having the guard (11) to the upper portion of the honeycomb substrate (30). At this time, the liquid level of the solution (20) is made uniform by using the guide (40) as needed, and/or the solution (20) is prevented from leaking from the upper part of the honeycomb base material (30) and the solution (20) is prevented from flowing down on the outer side surface of the honeycomb base material (30). The honeycomb base material (30) is placed on the support body (50), and the duct (60) is connected to the support body (50). The solution (20) is applied to the honeycomb base material (30) by sucking the solution (20) stored on the upper portion of the honeycomb base material (30) through the duct (60). In the method of fig. 1, the step of supplying the solution (20) from the head (10) and the step of sucking the solution (20) through the pipe (60) are performed in the same working place, but these steps may be performed in different working places.

As shown in fig. 2(a) and (b), the head (10) has a plurality of discharge ports (12) for discharging the solution, and the guard (11) is provided so as to surround the plurality of discharge ports (12).

< nozzle >

In the method of the present invention, a catalyst metal-containing solution is supplied from a spray head to the upper part of a honeycomb substrate. In the head, a plurality of discharge ports for discharging the solution and a shield member surrounding the plurality of discharge ports are present.

The guard preferably protrudes downward from the surface of the head by a length of 5mm or more, 8mm or more, 10mm or more, or 15mm or more. The length of the protrusion may be 100mm or less, 50mm or less, 30mm or less, 20mm or less, or 10mm or less. For example, the length of the protrusion may be 5mm or more and 100mm or less, or 10mm or more and 50mm or less. The length of the protrusion is measured from the discharge port of the head, and when the discharge port is in a convex portion of the surface of the head, the length is measured from the convex tip portion. In the case where the discharge port is a convex portion having various heights, the surface of the head in which the discharge port is located has various heights, and the like, the measurement can be performed from the discharge port located at the top end of the head in principle, but the reference position of the length at which the protector protrudes can be determined in consideration of the essential feature of the present invention that the protector is used to moisturize a large number of discharge ports to prevent uneven coating due to clogging.

If the distance between the guard and the discharge port closest to the guard is small, it is preferable from the viewpoint of making the vicinity of the discharge port a humid environment, but if it is too small, the catalyst metal-containing solution adheres to the guard, and loss of the catalyst metal occurs. For example, the average distance between the guard and the discharge port closest to the guard may be 1mm or more, 3mm or more, or 5mm or more, and may be 20mm or less, 10mm or less, 8mm or less, 5mm or less, or 3mm or less. For example, the average distance may be 1mm or more and 10mm or less, or 4mm or more and 6mm or less. The distance is determined from the closest portion of the guard and the outer periphery of the hole of the discharge port, and the average distance is calculated by considering only the distance from the guard of the discharge port existing on the outermost periphery side of the head among the discharge ports. However, in this regard, the position of the reference of the distance can also be determined in consideration of the essential feature of the present invention that uneven coating due to clogging is prevented by moisturizing a large number of discharge ports using a guard.

The hole diameter of the discharge port is not particularly limited, but is preferably small so as to avoid the solution from dropping from the discharge port of the head even in the case where the solution is not to be supplied. For example, the pore diameter may be 0.30mm or more, 0.50mm or more, 0.70mm or more, or 0.90mm or more, and may be 3.00mm or less, 2.50mm or less, 2.00mm or less, 1.50mm or less, or 1.30mm or less, as an average pore diameter expressed by an average equivalent diameter. For example, the average pore diameter may be 0.30mm or more and 3.00mm or less, or 0.50mm or more and 1.50mm or less. The "equivalent diameter" in the present specification means a value De represented by the following numerical formula (1).

De＝4Af/Wp (1)

{ in equation (1), De is the equivalent diameter, Af is the cross-sectional area of the discharge port, and Wp is the perimeter length of the discharge port. }

The shape of the hole of the discharge port is not particularly limited. Further, the diameter and shape of the discharge port need not be the same for all the holes, and may be various within a range in which the effects of the present invention can be obtained.

Preferably, the shower head is present directly above the honeycomb base material, and the discharge ports are present at substantially equal intervals over the entire upper surface of the honeycomb base material located below the shower head. In this case, the discharge ports may be arranged substantially uniformly in a grid pattern, or may be arranged substantially uniformly in a concentric circle pattern. Further, for example, the discharge ports may be arranged substantially uniformly in various patterns as described in patent document 2.

The discharge port may be present in a convex portion protruding from the surface of the head. In the case where the discharge port is present in the convex portion, the solution discharged from the discharge port is preferably spread only to the width of the tip of the convex portion, and aggregation of the solutions discharged from the adjacent discharge ports is less likely to occur. For example, as shown in fig. 3, a plurality of projections 15 may be present on the surface of the head 10, and the discharge port 12 may be present substantially in the center of the projections 15. The shape of the convex portion is not particularly limited as long as it is a trapezoidal shape as shown in fig. 3 and can prevent aggregation of discharged solutions.

In order to uniformly discharge the solution from the discharge ports of the head, a rectifying plate (13) as shown in fig. 4 may be provided inside the head. The shape of the flow regulating plate (13) is not limited as long as the solution is uniformly supplied over the entire surface of the honeycomb base material. For example, the rectifying plate (13) may be a plate having holes similar to those of the discharge surface of the head, or may be a deflector described in patent document 2.

< catalyst Metal-containing solution >

The viscosity of the catalyst metal-containing solution used in the method of the present invention is not particularly limited, and is not particularly limited as long as it is a slurry for constituting a catalyst layer of an exhaust gas purification device, a solution for supporting a catalyst metal on a honeycomb substrate of 1 type including ceria-zirconia composite oxide particles as a constituent material, or the like.

The slurry for forming the catalyst layer may be a slurry for forming a catalyst layer for a three-way catalyst device for a gasoline engine, or may be a slurry for forming a known catalyst layer for a purification device for a diesel engine or a lean-burn engine. Such a slurry is usually an aqueous dispersion in which at least an inorganic oxide or inorganic composite oxide support such as alumina, zirconia, ceria, or the like, and catalytic metal particles (platinum, palladium, rhodium, or the like) supported thereon are dispersed.

As the solution for supporting the catalyst metal, a solution including a salt of the catalyst metal can be cited. The salt of the catalyst metal includes a strong acid salt of platinum and/or palladium, and particularly includes a nitrate or sulfate of platinum and/or palladium. When the solution contains a rhodium salt, the same salt can be used. The solution for supporting the catalyst metal may further contain an inorganic oxide or an inorganic composite oxide support contained in the slurry for forming the catalyst layer.

When the viscosity of the catalyst metal-containing solution is low, the discharge port of the head tends to be clogged, but even when the viscosity is high, clogging may occur due to conditions such as humidity. For example, shear rate of catalyst metal-containing solution of 4s^-1The viscosity at the time of curing can be 1 mPas or more, 5 mPas or more, 10 mPas or more, 20 mPas or more, 50 mPas or more, 100 mPas or more, 200 mPas or more, 500 mPas or more, or 1000 mPas or more, 20000 mPas or less, 15000 mPas or less, 10000 mPas or less, 5000 mPas or less, 2000 mPas or less, 1500 mPas or less, 1000 mPas or less, 700 mPas or less, 600 mPas or less, 500 mPas or less, 400 mPas or less, 300 mPas or less, 250 mPas or less, or 200 mPas or less. For example, the shear rate of the catalyst metal-containing solution is 4s^-1The viscosity at this time can be 1 to 20000 mPas, 1 to 2000 mPas, 5 to 1000 mPas, or 10 to 300 mPas. The viscosity was measured using an E-type viscometer (TVE-35H, manufactured by Toyobo industries Co., Ltd.) and using a spindle type: 1 ℃ 34' XR 24 at a measurement temperature of 25 ℃.

The catalyst metal-containing solution may contain a thickener in an amount of 1.0 wt% or less, 0.5 wt% or less, 0.3 wt% or less, or 0.1 wt% or less for the purpose of adjusting the viscosity. Examples of the thickener include water-soluble organic polymers.

< Honeycomb substrate >

The honeycomb substrate used in the method of the present invention is not particularly limited as long as it is a honeycomb substrate for an exhaust gas purifying device known in the art. Specifically, as the honeycomb substrate, a honeycomb substrate having many cells, for example, cordierite (2MgO · 2 Al) can be used₂O₃·5SiO₂) A ceramic material having heat resistance such as alumina, zirconia, or silicon carbide, or a metal material made of a metal foil such as stainless steel.

Further, as the honeycomb substrate used in the method of the present invention, 1 kind of honeycomb substrate including ceria-zirconia composite oxide particles as a constituent material may be used. Such a honeycomb substrate is disclosed in, for example, patent documents 4 to 6, unlike the honeycomb substrate made of cordierite and the like currently used.

The honeycomb substrate may be a wall-flow honeycomb substrate or a flow-through honeycomb substrate. Further, the opening diameters of the cells on the front side (engine side) of the honeycomb base material and the opening diameters of the cells on the rear side may be different. The method of the present invention is particularly advantageous in that, when an exhaust gas purification device is produced using a honeycomb substrate of wall flow type using a catalyst metal-containing solution of low viscosity, the pressure loss of the exhaust gas purification device obtained is reduced.

The cell number of the honeycomb substrate may be, for example, 300 cells/in²500 cells/in above²Above, 800 cells/in²Above 1000 cells/in²Above or 1200 cells/in²Above, can be 2000 cells/in²1500 cell/in²Following, 1200 cell/in²Below, 1000 cells/in²The following or 800 cells/in²The following.

< Process for providing catalyst Metal-containing solution >

The step of supplying the catalyst metal-containing solution is performed in accordance with the features of the present invention as described above, but the step can be performed in the same manner as in the conventional technique with respect to the portions not related to the features of the present invention. For example, patent document 2 can be referred to for portions that are not related to the features of the method of the present invention.

In the step of supplying the catalyst metal-containing solution, a guide may be used in order to prevent the solution from leaking from the upper portion of the honeycomb substrate and flowing down on the outer side surface of the honeycomb substrate, and/or in order to make the liquid level of the solution supplied to the upper portion of the substrate uniform. Such a guide may be the same as the guide disclosed in patent document 2. Therefore, the step of mounting the guide to the honeycomb substrate can be performed before the step of supplying the catalyst metal-containing solution, which can be performed in a stage different from the stage on which the step of supplying the catalyst metal-containing solution is performed.

< coating Process of solution >

In the step of applying the solution supplied to the upper portion of the honeycomb substrate to the honeycomb substrate, as described in patent documents 1 and 2, the solution can be sucked from the lower portion side of the honeycomb substrate to accelerate the flow of the solution. However, when a low-viscosity catalyst metal-containing solution is used, the suction may not be performed.

In the case of performing the suction, the suction may be performed in a stage different from the supplying step of the catalyst metal-containing solution. In this case, the honeycomb base material holding the solution by the guide is moved from the stage performing the solution supply step to the stage performing the suction.

< firing Process >

The conditions for firing the substrate coated with the catalyst metal-containing solution are not particularly limited, depending on the composition of the catalyst metal-containing solution used, but firing is carried out at about 400 to 1000 ℃ for about 1 to 4 hours, for example. The drying may be carried out before firing, and the conditions thereof are not particularly limited, depending on the composition of the catalyst metal-containing solution used, but the drying may be carried out at a temperature of, for example, 80 to 300 ℃ for about 1 to 12 hours.

The present invention will be further specifically described with reference to the following examples, but the present invention is not limited thereto.