WO2024041907A1

WO2024041907A1 - Applicator for applying coating medium to substrates

Info

Publication number: WO2024041907A1
Application number: PCT/EP2023/072193
Authority: WO
Inventors: Fabian KLOSSNER; Marco Lopez; Stéphane MASSON
Original assignee: Umicore Ag & Co. Kg
Priority date: 2022-08-25
Filing date: 2023-08-10
Publication date: 2024-02-29
Also published as: DE102022121499A1

Abstract

The invention relates to an applicator (1) for coating a substrate (2) with a coating medium (3), wherein the applicator (1) has at least one supply line (4) for the coating medium, an end plate (9) with at least one nozzle (5) for applying the coating medium onto the substrate (2), and a cavity (6) in which the coating medium can be distributed prior to application onto the substrate (2), wherein at least one nozzle (5) is laterally inclined. The invention also relates to applicator systems, devices, methods and uses related to the applicator.

Description

Applicator for applying coating medium to substrates

The present invention relates to an applicator and systems, devices and methods for applying a coating medium to a substrate. The substrates themselves are used, for example, in catalytic exhaust aftertreatment, particularly in the automotive sector.

State of the art

Substrates or substrate monoliths are used as catalyst supports in the chemical industry. They also play an important role in the treatment of car exhaust fumes. To remove emissions that are harmful to the environment and health from the exhaust gases of motor vehicles, a large number of catalytic exhaust gas purification technologies have been developed, the basic principle of which is usually based on the fact that the exhaust gas to be purified passes through a substrate, e.g. a flow-through or a wall-flow honeycomb body or -monoliths (wall-flow) with a catalytically active coating applied to them. The catalyst promotes the chemical reaction of various exhaust gas components to form harmless products such as carbon dioxide and water.

The flow-through or wall-flow monoliths just described are also referred to as catalyst supports, carriers or even substrate monoliths, as they carry the catalytically active coating on their surface or in the pores of the wall that form this surface. The catalytically active coating is generally applied to the catalyst support in a coating process in the form of a suspension (often referred to as a “washcoat” in the case of catalysts for exhaust gas purification). Many such processes have been published in the past by car exhaust catalyst manufacturers (WO9947260A1, EP2521618B1, EP1136462B1, EP1900442A1).

Despite these methods known in the art, it is still a challenge to uniformly coat substrate monoliths. Different amounts of coating should be avoided if possible, for example due to the high costs of precious metals and rare earths. Uniform coatings are also preferable from a catalytic perspective. The dripping of the coating medium after the Application of the same to the substrate represents a challenge for the production of substrates.

An important aspect of such processes is the precise and uniform coating of the insides of the channels of such catalyst supports with the coating medium (washcoat), particularly with regard to, for example, coating length in the openings of the substrate, the amount of coating applied, the uniformity of the coating thickness, the uniformity of the coating length or of coating gradients along the longitudinal axis of the catalyst support, as well as in the production of layered or zoned coating designs.

Producing a precise and uniform coating is particularly challenging because the channels of the catalyst supports into which the coating is evenly applied are very narrow. For example, typical catalyst supports for exhaust gas aftertreatments have approximately 31 and 140 cells/cm ² (200 and 900 cells per square inch, cpsi), so that the openings of the catalyst channels are generally in the tenth of a millimeter range. Uniform coating is made even more difficult because the coating media are suspensions of inorganic particles that generally have a relatively high viscosity. Therefore, in principle and especially with minor process variations, there is a risk that the individual channels will be unevenly loaded with coating medium. This means that the depth of penetration of the coating medium into the catalyst support can vary considerably in local areas. An uneven distribution of the catalytic coating can result in impaired properties of the coated catalyst when used as intended. However, since such coating processes are carried out on an industrial scale with a variety of substrates, high uniformity and precision are required. Since the coatings contain precious metals such as platinum and palladium and rare earths, efficient use is also necessary for cost reasons.

EP2415522A1 shows such a coating process for catalyst supports, in which the coating medium is applied to a substrate from above. The coating medium is guided into a cavity via a feed line via a stamp and then applied to the substrate through the nozzles of an end plate. The entire amount of coating medium for the catalyst support is first introduced into an area above the substrate and then through Applying a negative pressure sucked into the channels. The area above the catalyst support can be limited laterally by a jacket. In order to obtain a large number of uniformly coated substrates in industrial production, it is necessary that exactly the same amount of coating medium is always applied evenly in the area above the substrate.

Another difficulty with such processes is that the coating medium is discharged from the end plate with excess pressure. In this way, a precisely defined amount of the relatively viscous coating medium can be evenly applied and distributed in the area above the substrate. If the pressure is too low, undesirable variations in quantity and distribution would result because, for example, part of the coating medium remains in the nozzles of the end plate, drips in an undesirable manner or can accumulate below the end plate. If, on the other hand, the coating medium is discharged with excess pressure, a defined amount can be precisely dosed and evenly distributed. However, discharge under excess pressure can have the undesirable effect that when the coating medium hits the substrate and then fills the area above the substrate, irregularities can occur, which result in uneven coatings.

Such undesirable effects are particularly problematic on an industrial scale, where a catalyst support is coated within a short time. In practice, such an automated coating process generally takes less than 20 seconds, and often only about 4 to 10 seconds.

If the exact same amount of coating medium is not always used in industrial processes, if it is not evenly sucked into the channels or does not descend evenly within the channels, coated substrates can differ from one another and significant irregularities in the thickness, uniformity and depth of the coating can occur the channels. In practice it has been shown that even with precise control of the dosage of the coating medium, uniform suction and drying, coated substrates with considerable variations in the coating in the channels are obtained. 7 of the present application shows, by way of example, a cross section of a catalyst support that was coated using a typical method according to the prior art. Although the coating medium from the end plate is applied evenly and was sucked into the channels of the substrate, the channels were not evenly coated. So the darker coating medium has penetrated deeply into the channels in some areas, but only a little in other areas, where the bright uncoated areas are much larger. Overall, an irregular zigzag pattern can be seen. As a rule, too much coating medium was introduced into the channels and areas that were coated too deeply. This also means that the thickness of the coating in such channels is greater than intended. The catalyst channels are therefore tapered, which reduces the flow speeds of exhaust gases. Such local variations in catalyst performance and flow lead to reduced catalyst performance when used as intended. The exhaust gases are not sufficiently cleaned in areas of insufficient coating depth, while in areas of excessive penetration the flow is reduced and coating medium, which generally contains rare and expensive metals, is wasted.

Another challenge is that many products require zone coating on both sides of the substrate. For technical reasons, zones with different catalytic coatings must be as close to one another as possible, but at the same time must not overlap. Therefore, flat and straight zone profiles are of particular importance for such multiple coatings.

There is therefore a need for improved devices and methods for coating catalyst supports which overcome the disadvantages described.

Task of the invention

The invention is based on the object of providing devices and methods with which a precise and uniform coating of substrates with coating media can be achieved. In particular, a uniform application of coating media should be achieved in the parallel channels of catalyst supports for exhaust gas purification devices, so that the channels can be coated over a length that is as uniform and defined as possible. The processes should be efficient, quick and can be carried out on an industrial scale with high throughput.

Subject of the invention The object on which the invention is based is achieved by an applicator, methods and uses according to the patent claims. The subject of the invention is an applicator for coating a substrate with a coating medium, the applicator having at least one supply line for the coating medium, an end plate with at least one nozzle for applying the coating medium to the substrate and a cavity in which the coating medium is located before application can distribute the substrate, characterized in that at least one nozzle is inclined laterally.

The coating medium is first introduced into the cavity of the applicator through a supply line and then pressed out of the cavity through the nozzles of the end plate under the influence of pressure. The applicator allows the precise dosage of the coating medium onto a substrate, such as a substrate monolith for car exhaust aftertreatment. The applicator is used to apply a defined amount of the coating medium that is to be applied to a substrate to an area above the substrate. The area above the substrate can, for example, be limited at the bottom by the end face of the substrate (with the openings of the channels) and on the sides by a collar. The coating medium remains in the area above the substrate during discharge from the applicator without applying a negative pressure and sucking in the coating medium. Only when the entire amount of the coating medium with which the substrate is to be coated has been introduced into the area is it sucked from the area into the substrate by applying a negative pressure.

It has proven to be an advantage if the applicator is designed in such a way that it has approximately the diameter and/or shape of the end face of the substrate to be coated. Large diameter substrates require larger applicators than smaller ones. As a rule, the applicator has a diameter in the range of 50 - 400 mm, more preferably 75 - 350 mm.

The cross section of the area preferably corresponds to the cross section of the substrate and that of the end plate. In this way, uniform filling of the area, followed by uniform suction of the coating medium into the substrate, can be achieved.

The end plate preferably has a symmetrical cross section, viewed from the top view in the direction in which the coating medium is discharged becomes. The end plate can, for example, have a circular, oval, trapezoidal, square, rectangular or polygonal, such as hexagonal, cross section. The shape of the connection plate is preferably adapted to the cross section of the catalyst support.

The cross section of the end plate is preferably circular or oval. On the one hand, this is advantageous because catalyst supports often have a circular or oval cross section. In addition, it was found that a particularly uniform application of the coating medium to the catalyst support is made possible with a round end plate which has laterally inclined nozzles. In particular, a particularly uniform, round application pattern can be obtained with a large number of laterally inclined nozzles.

It is preferred that the geometry of the nozzle arrangement essentially corresponds to the cross section of the plate. For example, the nozzles on a circular end plate are preferably arranged in a circular pattern. This is advantageous in order to make maximum use of the space in the applicator and to prevent the coating medium from being applied to partial areas of the catalyst support or only being applied unevenly.

The end plate preferably has a thickness of 2 - 10 mm, more preferably 4 - 5 mm. The end plate preferably has the shape of a disk. The cross section of the end plate is preferably circular, with the shape preferably being cylindrical. Such round configurations enable a particularly uniform or symmetrical arrangement of the nozzles, and thereby a uniform application of the coating medium to the substrate.

The coating medium is discharged from the applicator through the nozzles on the end plate. The end plate preferably has a large number of nozzles. The term nozzle refers to the component of the end plate from which the coating solution is applied to the substrate. The nozzles include flow channels with openings on the inlet side and the outlet side of the end plate. At the inlet side, the coating solution can be pressed from the cavity in the applicator into the channels of the nozzles. The coating medium is discharged at the outlet side and applied to the substrate. According to the invention, at least one nozzle is inclined. “Inclined” means that the nozzle is not arranged at right angles to the end plate, as with conventional plates, but is inclined relative to the end plate. If the plate is not flat, the nozzle is inclined compared to the view of the end plate from the lower side, i.e. the discharge side.

According to the invention, the inclination of the nozzle is lateral. “Sideways” means that the nozzle, when viewed from above the end plate (from below), is not inclined exclusively towards the center of the end plate or away from the center of the end plate (outwards). The lateral direction is therefore the direction that is at right angles to the direction towards the center. The lateral inclination of the nozzle causes the coating medium to be discharged laterally obliquely from the nozzle, at least partially in a direction that does not lead towards or away from the center.

If the end plate has a circular or oval cross-section, "laterally" inclined means that the nozzle, when viewed from above the end plate, is inclined exclusively or, among other things, in a tangential direction. The tangential direction is at right angles to the radial direction of the round or oval end plate.

In a preferred embodiment, the at least one nozzle is essentially inclined laterally. This means that the nozzle is either only inclined laterally (tangentially) or that the inclination deviates only slightly from the only lateral direction (for round or oval plates: the tangential direction), for example by less than 10°, in particular by less than 5 °. This means that the nozzle is not or only slightly inclined towards the center of the plate or outwards (in the radial direction). In these embodiments, the coating medium is essentially or only discharged to the side, but not or only slightly towards the center or the edges of the coating plate. This has the advantage that the coating solution does not accumulate anywhere on the substrate, especially if the majority of the nozzles are aligned in the same way. On the other hand, if the nozzles are inclined towards the center, more coating medium is applied towards the center. If the nozzles are tilted outward, more coating medium is applied toward the outside while less is discharged toward the center. For even application, a slight inclination of the laterally inclined nozzles towards the center can also be advantageous, so that each nozzle is slightly inclined towards the neighboring nozzle. The lateral inclination of the nozzle means that the coating medium is not discharged from the nozzle in a vertical jet from the end plate, but rather diagonally to the side. Surprisingly, it was found that a particularly uniform coating can be obtained if the nozzles of the end plate are inclined laterally. It is assumed that in this embodiment it is particularly advantageous that the coating medium impacts the substrate laterally. On the one hand, this reduces the force of the impact. Applying the coating medium in the form of oblique jets probably also causes it to be distributed more evenly on the substrate. A further advantage appears to be that the coating medium does not penetrate into the channels of the substrate, or only penetrates a little, before it is specifically sucked into the channels with suppression. The laterally inclined nozzles may also cause the coating medium on the substrate to quickly spread in a lateral direction after impact, thereby further weakening the impact force of the jets during the further application process. Overall, with the applicator according to the invention, the individual channels of the substrate can be coated particularly evenly, and in particular a particularly uniform penetration depth can be achieved.

It is not necessary for the nozzle to be tilted sideways along its entire length. It is only necessary that the lower area is inclined towards the outlet opening. For example, a laterally inclined nozzle can consist of a straight hole in the end plate and a laterally inclined nozzle on the outlet side.

In a preferred embodiment, the angle of inclination of the at least one nozzle is 2 and 50°, preferably 10 to 40°, and particularly preferably 15 to 30°. The inclination is defined in relation to a view of the plate from below. It has been found that the advantages in terms of the uniformity of the coated products can be particularly pronounced at such angles of inclination.

The majority of nozzles in the end plate preferably have a lateral inclination. According to the invention, it is preferred that at least 80%, in particular at least 90% or at least 95% of the nozzles in the end plate are inclined laterally. In a preferred embodiment, the nozzles are not or only slightly inclined towards the center or outwards (in the radial direction).

The end plate according to the invention preferably has a large number of nozzles.

The end plate preferably has 10 to 500 nozzles, in particular 60 to 320 nozzles or particularly preferably 95 to 225 nozzles. Such a high number of nozzles enables uniform application of the coating medium and can reduce local variations in the coating.

The nozzles are preferably arranged as uniformly as possible and at the same distance from one another as possible. In a preferred embodiment, all nozzles have the same distances from the neighboring nozzles. Such arrangements are advantageous in order to achieve the most uniform possible introduction of the coating medium and the most uniform possible coating of the substrate.

In a preferred embodiment, the end plate has laterally inclined nozzles and optionally a central nozzle. The central nozzle can be non-slanted or tilted. All nozzles are preferably inclined laterally, with the central nozzle not being inclined. With such an arrangement it can be achieved that the coating medium is applied particularly evenly to the substrate because all nozzles, possibly except for a central nozzle, discharge the coating medium in the form of oblique jets. With this arrangement, particularly uniformly coated substrates can be obtained.

In a further embodiment, the end plate does not have a central nozzle, but rather at least one inclined nozzle, which directs the jet obliquely towards the center of the catalyst carrier (in top view). In this way, the coating medium can be applied evenly, even without a central nozzle in the end plate, and also onto the center of the catalyst support.

In a preferred embodiment, all nozzles of the end plate are arranged symmetrically, in particular rotationally symmetrically. Preferably the laterally inclined nozzles are arranged in concentric circles around the central non-inclined nozzle. The plate preferably comprises a central nozzle and 2 to 9 hole circles, each with 6 to 54 nozzles in the periphery. The nozzles are spaced as evenly apart as possible. The arrangement in concentric circles is particularly advantageous because a uniform distribution of the nozzles can be made possible in a simple structural manner. In a preferred embodiment, the nozzles of a concentric circle are aligned the same. Each nozzle can be tangential in the same way or inclined towards an adjacent nozzle. This achieves a particularly uniform distribution of the coating medium on the substrate. In a preferred embodiment, the nozzles are arranged spirally. The nozzles are aligned spirally from the center of the plate outwards. Even with such an arrangement, a uniform application of the coating medium to the substrate can be achieved.

In a preferred embodiment, the distance between the nozzles is between

4 and 20 mm, preferably between 6 and 10 mm, each with respect to the center of the discharge openings. All distances between the adjacent nozzles in the end plate, in each concentric circle and/or in a spiral arrangement are preferably identical.

The diameter of the discharge opening of the nozzles is preferably between 0.5 and 5 mm, particularly preferably between 1.6 and 3 mm. All nozzles in the plate preferably have discharge openings of the same diameter. This enables particularly even application and coating of the substrate. With such nozzles, coating media can be applied particularly efficiently to substrates that are catalyst supports for exhaust gas purification devices with fine parallel channels.

Alternatively, it is possible that the coating medium is applied unevenly to the substrate. In this way it can be achieved that the coating has a gradient. For special applications, it can be advantageous to set a higher concentration of the catalytic coating in the inner channels or outer channels. A gradient can be achieved, for example, if the outlet openings of the nozzles in partial areas of the plate are different from one another and/or if the inclination of the nozzles is varied so that more coating solutions are discharged in some areas than in other areas.

It is preferred that the nozzles are designed in the shape of a nozzle. This means that they protrude from the end plate towards the discharge side. The design as a socket is advantageous because a lateral inclination can be set in a relatively simple and stable manner and it makes it more difficult to glue the plate from below. The nozzles preferably have a length of 5 mm - 15 mm, more preferably a length of 6 - 8 mm. The height of the elevation above the edge of the end plate is around 0.5 - 2.9 mm, more preferably 1.5 - 2.5 mm. In a preferred embodiment, the nozzles of the nozzle have a concave or countersunk nozzle towards the outflow. The distance between the nozzles is preferably in the range of

5 - 20 mm and most preferably 8 - 14 mm. In another embodiment, you can the nozzles can be channels that do not protrude from the plate, for example in the form of holes.

The preferably nozzle-shaped nozzles in the end plate can have any shape and cross section (e.g. channels, slots, circles, spirals, etc.). In the simplest case, the nozzles are channels with a round cross-section. The nozzles and/or outlet openings of the end plate are preferably the same size.

The cavity, the end plate with their nozzles are preferably coordinated with one another in terms of their dimensions and design, so that there is a homogeneous distribution of the coating medium on the substrate to be coated.

The entire applicator is preferably made of plastic. However, it can also be made entirely of metal. The materials are chosen so that they are compatible with the catalytically active coating for car exhaust aftertreatment. The preferred plastic material used is PE-HD 1000. Metal parts are preferably made of stainless steel equivalent or similar to material number 1.4571 (X6CrNiMoTi17-12-2).

In a preferred embodiment, a baffle plate is arranged in the cavity, which blocks the flow of the coating medium from the supply line to at least one opening. The coating medium is preferably metered into the applicator using a pump. The baffle plate can be arranged statically. The baffle plate can alternatively be reversibly movable. It preferably blocks the flow of the coating medium in the unpressurized state, while when pressure is exerted by the coating medium on the baffle plate, the flow of the coating medium from the supply line to at least one opening is permitted. The pressure that is built up via the coating medium serves to move the impact plate of the applicator so that the path to the end plate opens. The coating suspension can then be pressed into the cavity of the applicator, for example through nozzles in the baffle plate. Due to the baffle plate inside the applicator, which closes in the depressurized state, the coating medium does not drip onto the front side of the substrate. With such a displaceable baffle plate, the accuracy of dosing the coating medium onto the substrate can be increased even further. The applicator and methods can be used to coat a variety of substrates. It is preferred that the interior of the substrate is coated. The substrate preferably has a plurality of channels, which are in particular parallel to one another, and which are specifically loaded with the coating medium from one side, in particular by suction. The substrate is particularly preferably a catalyst support for exhaust gas aftertreatment. The channels are preferably filled in such a way that their insides are coated, but are not completely filled, so that they are still permeable to fluids, such as exhaust gases, after the coating has dried.

It is advantageous to use the applicator to produce a substrate monolith with a catalytically active coating for car exhaust aftertreatment. The coating medium used here is usually a suspension (slurry, washcoat), which may have acidic or basic properties, or at least has a very abrasive effect (see further below). This must be taken into account accordingly in the advantageous design of the applicator according to the invention. The coating media to be used is well known to those skilled in the art.

The substrate is preferably a catalyst support of the wall flow type (wall flow filter) or of the flow type, in particular in the form of a monolith. Flow-through monoliths are catalyst carriers that are common in the prior art and can consist of metal (corrugated carrier, for example WO17153239A1, WO16057285A1, WO15121910A1 and the literature cited therein) or ceramic materials. Fireproof ceramics such as corderite, silicon carbite or aluminum titanate etc. are preferably used. The number of nozzles per area is characterized by the cell density, which is typically between about 1,300 and 5,800 cells/cm ² (200 and 900 cells per square inch, cpsi). The wall thickness of the nozzle walls for ceramics is between 0.5 - 0.05 mm.

All ceramic materials customary in the prior art can be used as wall flow monoliths or wall flow filters. Porous wall flow filter substrates made of corderite, silicon carbide or aluminum titanate are preferably used. These wall flow filter substrates have inflow and outflow openings, with the outflow ends of the inflow openings and the inflow ends of the outflow openings offset from one another with gas-tight “plugs”. Here, the exhaust gas to be cleaned, which flows through the filter substrate, is forced to pass through porous wall forced between inflow and outflow openings, which results in an excellent particle filter effect. The filtration properties for particles can be designed through the porosity, pore/radius distribution, and thickness of the wall. The porosity of the uncoated wall flow filters is usually more than 40%, generally from 40% to 75%, especially from 50% to 70% (measured according to DIN 66133 - latest version on the filing date). The average pore size (diameter) of the uncoated filters is at least 7 pm, e.g. B. from 7 pm to 34 pm, preferably more than 10 pm, particularly more preferably from 10 pm to 25 pm or very preferably from 15 pm to 20 pm (measured according to DIN 66134 latest version on the filing date).

The coating medium is preferably a suspension. The solvent is preferably water. Such coating media are referred to in the technical field as washcoats. The coating medium is preferably structurally viscous (https://de.wikipedia.org/wiki/Structuralviskosit%C3%A4t). The viscosity is preferably from 1.0087 - 1000 mPas, preferably 100 - 780 mPas, at a shear rate of 100 1/s. The viscosity can be measured, for example, with a viscometer according to EN ISO 3219. The coating media, in particular in the form of washcoats, have solids and contain the catalytically active components or their precursors as well as inorganic oxides such as aluminum oxide, titanium dioxide, zirconium oxide, cerium oxide or combinations thereof, whereby the oxides can be doped with, for example, silicon or lanthanum. Oxides of vanadium, chromium, manganese, iron, cobalt, copper, zinc, nickel or rare earth metals such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium can be used as catalytically active components , ytterbium or their combinations can be used. Precious metals such as platinum, palladium, gold, rhodium, iridium, osmium, ruthenium and combinations thereof can also be used as catalytically active components. These metals can also exist as alloys with each other or other metals or as oxides. In the liquid coating medium, the metals can also be present as precursors, such as nitrates, sulfites or organyls of the noble metals mentioned and mixtures thereof, in particular palladium nitrate, palladium sulfite, platinum nitrate, platinum sulfite or Pt(NH3)4(NOs)2 can be used. The catalytically active component can then be obtained from the precursor by calcination at about 400 ° C to about 700 ° C.

Metal ions from the group of platinum metals, in particular platinum, palladium and rhodium, for example, have proven suitable for the oxidation of hydrocarbons crystallized out, while, for example, the SCR reaction has proven to be most effective with zeolites or zeotypes (molecular sieves with other or additional elements as cations in the framework compared to zeolites) that are exchanged with iron and / or copper ions. The material causing the catalytic activity (washcoat) can therefore also contain zeolites or zeotypes. In principle, all types or mixtures of these that are suitable for the relevant area of application can be used as zeolites or zeotypes. These include naturally occurring, but preferably synthetically produced zeolites. These can have framework types, for example, from the group consisting of Beta, Ferrierite, Y, USY, ZSM-5, ITQ. Examples of synthetically produced small-pore zeolites and zeotypes in question here are those that have the structure types ABW, AGO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATN, ATT, ATV, AWO, AWW, BIK, BRE, CAS, ODO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, ESV, GIS, GOO, IHW, ITE, ITW, JBW, KFI, LEV, LTA, LTJ, MER, MON, MTF, NSI, OWE, PAU, PHI, RHO, RTE, RTH, SAS, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG and ZON. Preference is given to using those of the small-pore type, which are derived from a structure type from the group consisting of CHA, LEV, AFT, AEI, AFI, AFX, KFI, ERI, DDR. Particularly preferred here are those which are derived from the CHA, LEV, AEI, AFX, AFI or KFI framework. A zeolite of the AEI or CHA type is particularly preferred in this context. Mixtures of the species mentioned are also possible. The SAR value of the zeolite or the corresponding value for the zeotype (eg SAPO -> (AI+P)/2Si) should be in the range from 5 to 50, preferably 10 to 45 and most preferably 20 to 40. For a correspondingly good activity, for example in the SCR reaction, it is necessary that the zeolites or zeotypes and in particular those of the small-pore type are exchanged with metal ions, in particular transition metal ions. Here the person skilled in the art can use the metal ions, in particular copper ions, which can preferably be used for the corresponding reaction. The person skilled in the art knows how such an ion exchange can take place (e.g. WO2008/106519A1). The degree of exchange (number of ions at exchange sites/total number of exchange sites) should be between 0.3 and 0.5. The exchange sites here are those where the positive ions compensate for negative charges on the lattice. Further non-exchanged metal ions, in particular Fe and/or Cu ions, can preferably also be present in the final SCR catalyst. The ratio of exchanged to non-exchanged ions is >50:50, preferably 60:40 - 95:5 and most preferably 70:30 - 90:10. The ions sitting on exchange sites are visible in electron spin resonance analysis and can be determined quantitatively (Quantitative EPR, Gareth R. Eaton, Sandra S. Eaton, David P. Barr, Ralph T. Weber, Springer Science & Business Media, 2010). All non-ion-exchanged cations are located elsewhere inside or outside the zeolite/zeotype. The latter do not compensate for the negative charge of the zeolite/zeol-type framework. They are invisible in the EPR and can therefore be calculated from the difference between the total metal loading (e.g. determined by ICP) and the value determined in the EPR. The addition of the corresponding ions to the coating mixture is controlled so that the total amount of metal ions, in particular Fe and / or Cu ions in the final total catalyst is 0.5 - 10% by weight, preferably 1 - 5% by weight of the coating amount lies.

In addition to the components just discussed, the coating medium can also contain other components. These components can further support the catalytic function of the catalytically active material, but do not actively intervene in the reaction themselves. Materials used here include so-called binders. The latter ensure, among other things, that the materials and components involved in the reaction can adhere sufficiently firmly to the corresponding substrate. Binders selected from the group consisting of aluminum oxide, titanium dioxide, zirconium dioxide, silicon dioxide or their oxide hydroxides (for example boehmite) or mixtures thereof have proven to be advantageous components in this context. High-surface aluminum oxides are advantageously used here. The binder is used in the coating in a certain amount. Based on the solid material used in the coating suspension, the further component, for example the binder, is used in an amount of max. 25% by weight, preferably max. 20% by weight and most preferably in an amount of 5% by weight. - 15% by weight used.

The substrate monoliths produced in this way, which are catalytically active in the exhaust gas aftertreatment, can in principle be used in all exhaust gas aftertreatments known to those skilled in the automotive exhaust sector. The catalytic coating of the substrate monolith can preferably be selected from the group consisting of three-way catalyst, SCR catalyst, nitrogen oxide storage catalyst, oxidation catalyst, soot ignition coating. With regard to the individual catalytic activities in question and their explanation, reference is made to the statements in WO2011151711 A1. The invention also relates to a method for coating a substrate with a coating medium using an applicator according to the invention, comprising the steps:

(a) applying the coating medium to the substrate through the nozzles of the end plate, and

(b) sucking the coating medium into the substrate.

The application of the coating medium in step (a) takes place in an area above the substrate. Because of the at least partially oblique arrangement of the nozzles, the coating medium is applied to the substrate in an oblique jet, which leads to a particularly uniform coating. Only when the complete amount of the coating medium for the substrate has been fed into the area is the coating medium sucked into the substrate in step (b). The suction is carried out by applying a negative pressure, in particular a vacuum. In step (a), the coating medium is preferably applied by pressure, for example between 0.3 and 10 bar, in particular between 1.5 and 3.5 bar. In step b), the suction is preferably carried out with negative pressure, for example between 10 and 500 mbar, in particular between 50 and 200 mbar. With such settings, particularly efficient and rapid production of the coated substrate can be achieved.

The process is preferably automated and carried out with high throughput, preferably in a continuous process for a defined number of pieces. In automated processes, the coating medium is applied in step (a) at high speed, for example within a period of 200 ps to 6 s, in particular between 500 ps and 3 s. The suction in step (b) preferably takes place in a period of 10 ps to 10 s, especially between 20 ps and 2.5 s.

The advantage of the method according to the invention is that a particularly uniform coating of the fine channels of a catalyst support can be achieved. Since the penetration depth of the coating medium into the catalyst substrate is particularly uniform, the process is particularly suitable for automated production in which a large number of substrates are coated in rapid succession.

In a preferred embodiment, the method applies two or more coatings to the same substrate, typically in defined directions Subareas (zones) with different catalytic effects. In the prior art, it is particularly complex to provide a catalyst substrate with several coatings in partial areas. Particular care must be taken to ensure that the zones are relatively clearly located. Since precise control of the penetration depth is possible with the method according to the invention, the method is particularly suitable for applying and combining zones. For example, a catalyst substrate can be equipped from one side with a zone of a first coating medium with a penetration depth of, for example, 10 to 90% of the channel length, after which a second coating medium is applied from the other side of the catalyst substrate in a second zone, for example also with a penetration depth of 10 to 90% of the channel length. Such zones can be applied in different areas of the substrate and/or one above the other in order to optimize specific catalytic reactions.

The invention also relates to an applicator system for coating a substrate with a coating medium, comprising an applicator according to the invention and a control unit through which a defined amount of coating medium can be discharged from the applicator. The control unit can preferably be set to repeatedly discharge the same defined amount of coating medium. The system preferably includes means for dosing, such as a tank, supply lines and valves. This means that a series of similar substrates can be coated in the same way in an automated process. The defined amount of coating medium is selected and adjusted, for example, with regard to the dimensions of the substrate and the channels as well as the desired coating. It is, for example, between 20 ml and 5000 ml, in particular between 60 ml and 1500 ml, particularly preferably between 120 ml and 800 ml. The applicator system can contain other common means, such as a tank for coating medium, a positive displacement pump, valves and a control unit to monitor the process.

The invention also includes a device for coating a substrate with a coating medium

(i) an applicator and/or an applicator system according to the invention,

(ii) means for fixing the substrate below the applicator,

(iii) an area above the fixed substrate for introducing the coating medium from the applicator, and (iv) Means for sucking the coating medium into the substrate.

The device can be used to carry out the coating process described above. The means for fixing the substrate are preferably a holder into which the substrate can be picked up, fixed and removed again after coating, preferably in an automated process. The area (iii) can be formed temporarily after the substrate has been fixed, for example by attaching a jacket to the upper edge of the substrate, which prevents the coating medium from flowing off to the side. The means for suction can be a vacuum pump, which is connected to the substrate from below via a pipeline. The device can preferably coat a large number of substrates one after the other in an automated manner, without external intervention in the process.

The invention also relates to the use of an applicator, applicator system and/or the device according to the invention for producing a substrate monolith with a catalytically active coating for car exhaust aftertreatment.

The invention also relates to the use of the applicator, applicator system and/or device according to the invention to increase the uniformity of the coating in a substrate monolith.

In the methods and uses mentioned, the applicator of the invention, as described above, is preferably used.

Figures 1 to 8 show schematically and by way of example embodiments of the invention as well as objects according to the prior art for comparison.

Fig. 1 shows schematically and by way of example a device for coating substrates with an applicator according to the invention in cross section.

Fig. 2 shows an example and schematically of the lower side view of the end plate of an applicator according to the invention.

Fig. 3 shows the cross section through an end plate with a laterally inclined nozzle.

Fig. 4 shows the top view of the discharge side of the end plate according to Fig. 2.

Fig. 5 shows the top view according to Fig. 4, in which the concentric circles of the nozzles and the radial direction of the plate are identified. Fig. 6 shows a detail of the cross section of an end plate with a laterally inclined and a vertical nozzle and jets of coating medium that impinge on a substrate.

Figure 7 is a photograph of the cross-section of a catalyst support coated in a conventional manner with an end plate having vertical nozzles.

Fig. 8 is a photograph of a catalyst carrier coated according to the invention, which was coated according to the invention with an end plate with obliquely inclined nozzles. The photo shows a direct comparison to Fig. 7 from the same series of tests

Below, exemplary embodiments of the invention and for comparison according to the prior art are explained using the figures.

Figure 1 shows, by way of example and schematically, the cross section of a device for coating a substrate 2 with an applicator 1 according to the invention. The substrate 2 to be coated is fixed with means 15, such as a holder, for a coating process. The coating medium is metered onto the end face of a substrate 2, which is a catalyst support with a plurality of fine parallel channels 14. A type of collar 11 is placed/inserted around this end face, which prevents the coating medium from running down from the end face to the sides of the substrate 2. The end face of the substrate 2 and the collar 11 delimit an area 10 into which the coating medium is introduced before the substrate 2 is coated. The coating medium is first added via the feed line 4 into a cavity 6 above the end plate 9. The end plate 9 has a plurality of laterally inclined nozzles 5. The coating medium is introduced from the cavity 6 into the area 10 above the substrate 2 through the nozzles. The exact amount of coating medium required to coat the specific substrate is entered. After the coating medium has been introduced, a negative pressure is applied below the substrate 2 using means 13, such as a pump, whereby the coating medium is sucked into the parallel channels 14 from above. The amount, thickness and depth of penetration of the coating medium can be controlled, among other things, via the amount and viscosity of the coating medium, the structure of the substrate 2 and the suppression. The method can be adjusted so that the coating penetrates into the channels 14 up to a zone boundary 16. The coating medium can be entered up to a zone boundary 16. This means that the procedure is carried out in such a way that Coating medium is applied only above the zone boundary 16, so that the catalyst support 1 is only coated on one side. The zone boundary 16 is shown as a line and thus shows an ideal course. In practice the zone boundary is irregular. The uniformity can be significantly improved with the applicator 1 according to the invention (see Figures 7 and 8).

2, 3 and 5 show schematically and by way of example an applicator 1 according to the invention with an end plate 9 which has a plurality of laterally inclined nozzles 5. 2 shows a side bottom view of the applicator 1, FIG. 4 shows a top view from below and FIG. 5 shows a top view according to FIG. 4 with concentric circles of the nozzles and the radial direction from the center of the plate to the outside. The end plate 9 is round, which allows the nozzles 5 to be arranged in concentric circles at even distances. The inclination of the nozzles 5 in the concentric circles is exclusively lateral and tangential, as can also be seen in FIG. 5 with the concentric circle patterns. This means that the nozzles 5 in the concentric circles are not inclined inwards or outwards in the indicated radial direction. This enables the coating medium to be applied evenly. The nozzles 5 have a regular arrangement and equal distances from one another. This enables the coating medium to be distributed evenly into an area 10 above the substrate. The nozzles 5 in each concentric circle are essentially inclined towards the adjacent nozzle. This creates a regular discharge pattern. In addition, it is prevented that the jets of the coating medium from the nozzles 5 hit the substrate perpendicularly and that the coating medium undesirably penetrates into channels before the suppression is applied. The nozzles in FIGS. 2 to 5 have connectors 12 which protrude from the end plate. Fig. 3 shows a cross section of the end plate 9 with a laterally inclined nozzle 5 with a nozzle 12.

6 shows, by way of example and schematically, how coating medium 3 is discharged from a laterally inclined nozzle 7 and, for comparison, from a vertical nozzle 8 into the area 10 above the substrate 2. An oblique jet is generated from the laterally inclined nozzle 7, whereby the effect of the impact on the upwardly open fine channels 14 of the substrate 2 is weakened. In this way, unwanted penetration of the coating medium 3 into the channels 14 before suction can be prevented or at least significantly reduced, which leads to a more homogeneous coating. Figures 7 and 8 show photographs of cross sections of coated catalyst supports and illustrate the advantages of the invention. Figure 7 shows the cross-section of a prior art coated catalyst carrier made with an outlet plate applicator with vertical nozzles. The upper coated zone is dark and the lower uncoated zone is lighter. The coating has penetrated the channels irregularly. Significant and random fluctuations can be seen over larger domains. Smaller areas in which the coating medium has undesirably penetrated relatively deeply into the channels are particularly noticeable. Fig. 8 shows the cross section of a catalyst support coated according to the invention. The carrier and resolution correspond to Figure 7, so the products are comparable. In Fig. 8 it can be seen that the zone boundary between the dark coated zone and the light uncoated zone is uniform and straight. Significant irregularities, as in Fig. 7, are not present. It should be noted that the slightly darker tone in some sections below the zone boundary is not caused by the penetration of the coating medium, but by shadows. The loose components, which can only be seen in FIG. 8, are caused by the splitting process and are also not relevant for comparing the coatings. The comparison of Figures 7 and 8 shows that a significant improvement in the uniformity of the coating can be achieved with the applicator according to the invention with laterally inclined nozzles.

The applicator according to the invention, the applicator system, the device, the methods and the uses solve the problem on which the invention is based. According to the invention, it is possible to coat substrates, such as catalyst supports for exhaust gas purification devices, with high precision. This is made possible by a simple design measure, so that the process can be carried out efficiently, quickly and on an industrial scale with high throughput. In particular, it is possible to coat the fine channels of catalyst supports for exhaust gas purification devices with high precision, with clearly defined zones being able to be obtained. This enables significant savings in expensive catalytic materials, in particular precious metals or rare earths, and the provision of particularly powerful exhaust gas purification devices and other catalytic devices. Reference character list:

1 applicator

2 substrate to be coated 3 coating medium

4 supply area within the applicator (1)

5 Nozzle in the end plate (9)

6 cavity within the applicator (1)

7 inclined nozzle 8 straight nozzle

9 end plate

10 area above the substrate

11 collar that delimits the area (10).

12 nozzle 13 means for sucking in the coating medium

14 parallel channels in the substrate (2)

15 Means for fixing the substrate

16 zone boundary

Claims

Patent claims

1 . Applicator (1) for coating a substrate (2) with a coating medium (3), the applicator (1) having at least one supply line (4) for the coating medium, an end plate (9) with at least one nozzle (5) for applying the coating medium on the substrate (2), and a cavity (6) in which the coating medium can be distributed before application to the substrate (2), characterized in that at least one nozzle (5) is inclined laterally.

2. Applicator (1) according to claim 1, characterized in that the angle of inclination of the laterally inclined nozzle is 2 to 50 °, preferably 15 to 30 °.

3. Applicator (1) according to at least one of the preceding claims, characterized in that the end plate (9) has a circular or oval cross section.

4. Applicator (1) according to claim 3, characterized in that the at least one nozzle (5) is not inclined significantly inwards or outwards in the radial direction.

5. Applicator (1) according to at least one of the preceding claims, characterized in that the nozzles are arranged at equal distances from one another.

6. Applicator (1) according to at least one of the preceding claims, characterized in that the end plate (9) has a plurality of laterally inclined nozzles and a central nozzle.

7. Applicator (1) according to at least one of the preceding claims, characterized in that laterally inclined nozzles (5) are arranged in concentric circles around a central nozzle.

8. Applicator (1) according to claim 7, characterized in that the nozzles (5) in each concentric circle are aligned and / or inclined in the same way.

9. Applicator (1) according to at least one of the preceding claims, characterized in that the nozzles (5) are arranged spirally.

10. Applicator (1) according to at least one of the preceding claims, characterized in that a baffle plate in the cavity (6) blocks the flow of the coating medium (3) from the supply line (4) to at least one nozzle (5) in the unpressurized state and Pressure through the coating medium (3) on the baffle plate allows the flow of the coating medium (3) from the supply line (4) to at least one nozzle (5).

11. Applicator system for coating a substrate (2) with a coating medium (3), comprising an applicator (1) according to at least one of the preceding claims and a control unit which is adjustable to discharge a defined amount of coating medium (3) from the applicator (1).

12. Device for coating a substrate (2) with a coating medium (3), comprising

(i) an applicator (1) and/or an applicator system according to at least one of the preceding claims,

(ii) means for fixing the substrate (2) below the applicator (1),

(iii) an area (10) above the fixed substrate (2) for introducing the coating medium (3) from the applicator (1), and

(iv) Means for sucking the coating medium (3) into the substrate (2).

13. A method for coating a substrate with coating medium using an applicator (1), an applicator system and / or a device according to at least one of the preceding claims, comprising the steps:

(a) applying the coating medium (3) to the substrate (2) through the nozzles (5) of the end plate (9), and

(b) sucking the coating medium (3) into the substrate (2).

14. Use of an applicator (1), an applicator system and / or a device according to one of claims 1 to 12 for producing a substrate monolith with a catalytically active coating for car exhaust aftertreatment.