METHOD AND APPARATUS FOR THE PREPARATION OF A SUBSTRATE FOR AN EXHAUST GAS AFTERTREATMENT DEVICE

Abstract

The invention relates to a method for producing a substrate (1) for an exhaust gas aftertreatment device, having the following steps: applying (S1) a coating material (12) on an elastic base (11); dipping or pressing (S2) a surface of the substrate (1), in which inlet openings of through-channels (2) are arranged, through the substrate (1) into the coating material (12); lifting off the coated catalyst element (1); and aftertreating, and in particular drying or calcining (S3), the coating material (12) on the coated substrate (1).

Claims

1. Method for producing a substrate (1) for an exhaust gas aftertreatment device, having the following steps: applying (S1) a coating material (12) on an elastic base (11); dipping or pressing (S2) a surface of the substrate (1), in which inlet openings of through-channels (2) are arranged, through the substrate (1) into the coating material (12); lifting off the coated catalyst element (1); and aftertreating, and in particular drying or calcining (S3), the coating material (12) on the coated substrate (1).

2. Method according to claim 1, wherein the coating material (12) comprises a catalytically-active component, and in particular a precious-metal-containing solution.

3. Method according to claim 1, wherein the surface of the substrate (1) to be coated has a convex or concave or otherwise irregularly-shaped structure with respect to its axial direction.

4. Method according to claim 1, wherein the liquid coating material (12) is applied to the elastic base (11) in a planar manner, and in particular with a constant layer thickness.

5. Method according to claim 1, wherein the coating material (12) is provided with a viscosityin particular, by the use of a gel former, such as polysaccharideso that a uniform layer having, in particular, a layer thickness of 0.2 to 4 mm can be applied to the base.

6. Method according to claim 1, wherein the coating material is shear-thinning, so that the application of the coating material does not lead to film breaks, wherein a viscosity of the coating material at 20? C. of 0.5 to 10 Pa*s, and in particular of 1 to 5 Pa*s, at a shear rate (DIN 53019) between 12 and 20 l/s, and in particular between 14 and 17 l/s, is selected.

7. Method according to claim 1, wherein the base (11) has an elastic plastic or a rubber material, and in particular a foam rubber material, and has a smooth and/or closed surface.

8. Method according to claim 1, wherein the coating material (12) is applied to the base (11) by a doctor blade or by a film applicator on the base or by a slot die (13) on the base (11), which is moved relative to the slot die.

9. Method according to claim 1, wherein the residual coating material (12) of a preceding coating operation remaining before the application of the coating material (12) is removed in particular by scraping.

10. Device (10) for manufacturing a substrate (1) for an exhaust aftertreatment device, comprising: an in particular horizontally-oriented elastic base (11) with a closed surface; an application unit (13) which is configured to apply a liquid coating material (12) to the base (11); a pressing-in unit (16) which is configured to dip or press, after the application of the coating material (12), a substrate (1) to be coated into the coating material (12).

11. Device according to claim 9, wherein a non-elastically-deformable base plate (14) is arranged below the elastic base (11).

12. Substrate (1) produced according to the method according to claim 1.

Description

SHORT DESCRIPTION OF THE DRAWINGS

[0058] Embodiments are explained in more detail below with reference to the accompanying drawings. The following are shown:

[0059] FIG. 1 a perspectival view of a face of a substrate for an exhaust gas aftertreatment device;

[0060] FIG. 2 a cross-sectional view through a substrate, to illustrate an uneven face;

[0061] FIG. 3 a device for applying a coating to a face of a substrate; and

[0062] FIG. 4 a flowchart to illustrate the method for producing a substrate with a face coating.

DESCRIPTION OF EMBODIMENTS

[0063] FIG. 1 shows a perspectival view of a substrate 1 as used in conventional exhaust gas aftertreatment devicesfor example, as a catalyst element. FIG. 2 shows a cross-sectional view through the substrate 1.

[0064] The substrate 1 is preferably formed from a porous and in particular ceramic substrate material. The substrate 1 has through-channels 2 running parallel to one another, the inner walls 3 of which are coated with a catalyst material in a manner known per se. Such a catalyst material can have catalytically-active components such as precious metals, and in particular platinum, palladium, rhodium, or also base metals such as Cu, Fe, Mn, V, Co, Ni. The catalytically-active component can be present in dissolved form, e.g., dissolved salt, in the liquid or can be bound beforehand to a carrier oxide. A plurality of materials are known, e.g., aluminum oxide, silicon oxide, titanium oxide, cerium oxide, zirconium oxide in pure form, doped, e.g., with lanthanum, silicon, cerium, magnesium, or barium, or in combination with one another.

[0065] The through-channels 2 can have a round, hexagonal, or square cross-section, or a cross-section shaped in some other way. The through-channels 2 end at a face 4 of the substrate 1 so that the face 4 of the substrate 1 has inlet openings 5 for the through-channels 2.

[0066] As shown in the sectional view through the substrate in FIG. 2, the face, apart from the inlet openings of the through-channels (i.e., over the entire extension of the face), is not flat, but can be deformed in the axial direction and can have a concave and/or convex and/or otherwise uneven structure. The through-channels 2 are separated from one another in the substrate material of the substrate 1 by intermediate walls 6 which, at the face, lead to web-like structures between the inlet openings 5 of the through-channels 2.

[0067] In the following, a device and a method are described by means of which a coating can be applied to the face of the substrate 1, which coating serves to prevent face plugging. Suitable materials for such a coating are a precious-metal-containing solution, which can differ with respect to composition and materials from the layer material, which is applied to the inner walls of the through-channels before or after the coating of the faces.

[0068] FIG. 3 shows a schematic illustration of a device 10 for applying a coating to the face of a substrate 1. In conjunction with the schematic illustrations of FIG. 4, a process sequence for the production of the substrate 1 with a coating for preventing face plugging is described.

[0069] FIG. 3 shows a device 10 with an elastic base 11 onto which a coating of a liquid coating material 12 can be applied by means of an application unit 13.

[0070] The base 11 can correspond to a foam material having a smooth and closed surface. The closed surface prevents the penetration of the coating material into the foam material, and thereby ensures less material loss. In order to guarantee the most uniform possible exertion of pressure, the base 11 is supported by a fixed, non-elastically-deformable base plate 14.

[0071] The coating material can be a material with a viscosity such that it can be applied with a layer thickness between 0.2 and 3 mm on a flat surface of the base 11 so that it forms a closed surface.

[0072] The coating material 12 can be applied by means of an application unit 13. In particular, the coating material 12 can be applied by placing the coating material on the elastic base 11 and distributing it by means of a doctor blade or an application using a film applicator (as an application unit).

[0073] Alternatively, as sketched in FIG. 3, in step S1, the coating material 12 can be applied via a slot die 13 (as an application unit), which moves in a translatory manner relative to the base 11 at a constant distance and at the same time releases the liquid coating material 12. The coating material 12 can a precious-metal-containing solution which, with the aid of a gelling agent, is increased in viscosity to such an extent that a coherent wet film of constant thickness can be applied to the base 11.

[0074] The base moved relative to the slot die can have a moving plate or a conveyor belt, so that a very precisely adjustable layer thickness, and thereforeparticularly in connection with the closed surfacea reproducible and defined material transfer to the substrate.

[0075] After the application of the coating material 12, in step S2, the face of the substrate 1 to be coated is pressed into the material by means of a pressing-in unit 16in particular, perpendicularly to the surface direction of the base 11. In the process, the base 11 deforms due to its elasticity, so that the web-shaped surfaces come into contact with the coating material 12 even in the case of an uneven face. It is thereby possible to wet a complete coating of all surface portions of the face of the substrate 1, which are formed by the web-like walls between the through-channels 2, with the coating material, in order to thereby reduce or prevent face plugging over the entire face.

[0076] After the lifting off of the substrate 1 in from the base, in step S3, the substrate 1 wetted with the coating material 12 is lifted off from the base and can then, if necessary, be fed to a separate thermal treatment to dry or calcine the applied coating material.

[0077] Subsequently, in step S4, the coating material 12 is removed from the base 11, e.g., by means of a scraper 15, and the base is thus again prepared for a subsequent coating of a substrate 1 with a constant wet film thickness.