EP3648884A1 - Nivellement sans contact d'une suspension d'enduction washcoat - Google Patents

Nivellement sans contact d'une suspension d'enduction washcoat

Info

Publication number
EP3648884A1
EP3648884A1 EP18742726.5A EP18742726A EP3648884A1 EP 3648884 A1 EP3648884 A1 EP 3648884A1 EP 18742726 A EP18742726 A EP 18742726A EP 3648884 A1 EP3648884 A1 EP 3648884A1
Authority
EP
European Patent Office
Prior art keywords
washcoat
pressure
gas
suspension
substrate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP18742726.5A
Other languages
German (de)
English (en)
Inventor
Juergen Koch
Astrid Mueller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Umicore AG and Co KG
Original Assignee
Umicore AG and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Umicore AG and Co KG filed Critical Umicore AG and Co KG
Publication of EP3648884A1 publication Critical patent/EP3648884A1/fr
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
    • B05B1/14—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with multiple outlet openings; with strainers in or outside the outlet opening
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1023—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/915—Catalyst supported on particulate filters
    • B01D2255/9155—Wall flow filters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/19—Catalysts containing parts with different compositions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0246—Coatings comprising a zeolite

Definitions

  • the present invention is directed to a method and an apparatus for coating carriers of autocatalysts.
  • the invention describes an improvement in coating processes of this type in which a suspension (washcoat) containing the catalytically active material is applied or applied to such a support (substrate monolith) from above (so-called “metered charge” process).
  • the exhaust gas of internal combustion engines in motor vehicles typically contains the noxious gases carbon monoxide (CO) and hydrocarbons (HC), nitrogen oxides (NO x ) and possibly sulfur oxides (SO x ), as well as particles consisting predominantly of soot residues and optionally adhering organic agglomerates. These are called primary emissions.
  • CO, HC and particulates are products of incomplete combustion of the fuel in the combustion chamber of the engine.
  • Nitrogen oxides are produced in the cylinder from nitrogen and oxygen in the intake air when the combustion temperatures locally exceed 1400 ° C. Sulfur oxides result from the combustion of organic sulfur compounds, which are always present in small amounts in non-synthetic fuels.
  • the flow or wall flow monoliths just described are also referred to as catalyst supports, supports or substrate monoliths since they carry the catalytically active coating on their surface or in the pores forming this surface.
  • the catalytically active coating is frequently applied to the catalyst support in the form of a suspension in a so-called coating process.
  • Many such processes have been published in the past by automotive catalytic converters (EP1064094B1, EP2521618B1, WO10015573A2, EP1 136462B1).
  • a vacuum is used to draw a washcoat suspension from bottom to top through the channels of a substrate monolith.
  • US4609563 describes a process in which a metered charge system is used for the catalytic coating of a substrate.
  • This system comprises a method of coating a ceramic monolithic support with a precisely controlled, predetermined amount of the washcoat suspension using a vacuum (hereinafter "metered charge").
  • the monolithic carrier is immersed in a quantified amount of washcoat suspension. Then the washcoat suspension is pulled through the vacuum into the substrate monolith.
  • the monolithic support it is difficult to coat the monolithic support so that the coating profiles of the channels in the monolithic support are uniform.
  • washcoatsuspension (metered charge) is applied to the top of a vertical substrate monolith, this amount being so large that it is retained almost completely within the intended monolith (US6599570).
  • a vacuum / pressure device acting on one of the ends of the monolith, the washcoat suspension is completely sucked / pressed into the monolith without excess suspension coming out at the bottom of the monolith (WO9947260A1). See also JP5378659B2, EP2415522A1 and JP2014205108A2 from Cataler in this connection.
  • washcoat suspensions which generally also have a high yield point, regularly form an uneven and uneven surface when applied to a vertically oriented catalyst support (substrate monoliths). When sucked into the substrate, this then leads to the fact that no uniform coating front can form and the coating suspension is sucked in different distances in the carrier. Homogeneous distribution is of great importance, in particular in the case of partial coatings for producing zoned products, in order to ensure that a reproducible, uniform catalytic activity is ensured over the entire length and the cross section of the support.
  • US2010221449A1 describes a method for removing unwanted structures and defects from a paint layer applied to a substrate by means of blowing an air stream. The effectiveness of the airflow can be assisted by using ultrasound.
  • the smoothing unit is part of a complex coating system consisting of an application unit (printer), smoothing unit and drying unit. Paper or board with a thin ( ⁇ 1 mm) lacquer layer is coated with this system.
  • the object of the present invention was to provide an improved process and a correspondingly working device for coating substrate monoliths with a washcoat suspension for use as autocatalysts.
  • the process should ensure that in particular zoned coated catalyst can be produced with a uniform zone boundary or as uniform as possible zone profile. Such a process should lead to less rejects and to products that have better performance in exhaust gas purification. Such a process and such a device would therefore be preferred from the economic and ecological point of view.
  • the shearing force required for smoothing in the form of a pressure can preferably be transmitted by an air flow. However, it may also be necessary that other gases be taken for this, such as inert gases or reducing gases. The flow can then be provided by skilled artisans knowledge by means of pressure tanks or bottles with such gases.
  • the shear force is generated in the form of a pressure by a method selected from the group consisting of a continuous gas / air flow or a pulsating gas / air flow, or mixture thereof.
  • the gas / air stream may have a laminar or turbulent character.
  • the method according to the invention therefore dispenses with any further method beyond the inventive measure in order to achieve the leveling of the applied washcoat suspension.
  • the leveling takes place in this case exclusively contactless by the transmission of the shear force by air or a gas by means of a pressure.
  • the present invention is directed to a process for coating substrate monoliths with a washcoat suspension in which the shear force acting on the surface of the applied washcoat suspension by means of a gas, in particular air, is an alternating force. This is meant in the sense that the pressure acting on the surface of the applied washcoat by the gas changes with time in such a way that the pressure is continuously or gradually reduced during the duration of the action.
  • the pressure on the surface of the applied Washcoatsuspension by one or more acoustic or pressure wave generators preferably a high-frequency ultrasonic resonator.
  • the ultrasonic resonator In this case, it does not dive into the suspension but generates sound pressure waves acting on the surface of the liquid at a certain distance from the washcoat surface due to the ultrasonic vibration in the air.
  • a common ultrasound source eg http://www.labo.de/ moduebersichten/ nuuebersicht- labo- nuebersicht-ultrasound-homoQenisatoren.htm
  • the suspension located on the substrate monolith is then exposed to ultrasound for a sufficient time.
  • the shear force is generated by ultrasound at a frequency of about 18,000 to about 90,000 Hz, preferably 18,000-60,000 Hz, and more preferably 19,000-43,000 Hz.
  • the ultrasonic processor by electrical excitation longitudinal mechanical oscillations in the frequency range from 18000 Hz to 90kHz.
  • the vibrations are amplified by the sonotrode and for the most part transmitted via the end face to the surrounding medium (usually a liquid).
  • the mechanical amplitude of the sonotrode can be increased or decreased by installing a booster, wherein the ultrasound power delivered into the medium can be adjusted continuously via the power control of the ultrasound processor.
  • the pressure applied by ultrasound takes place with the energy specified above, it is usually sufficient for about 0.1 to about 60 seconds, preferably 1 to 30 seconds, and very preferably 1 to 10 seconds, to sufficiently level the surface of the applied washcoat suspension , Particularly preferably, the pressure of the air or gas stream directed onto the surface of the washcoat is greater than the flow limit of the washcoat. When the flow limit is exceeded, the pseudoplastic washcoat begins to flow and can thus easily compensate for irregularities in the liquid surface.
  • the shear force acting in the form of a pressure can also be generated by a gas / air flow from a nozzle.
  • gas / air nozzles are known.
  • slit or knife nozzles are preferably used (https://de.wikipedia.org/wiki/Luftklinqe).
  • gas nozzles are exemplified, with which the gas, in particular air can be passed to the surface of the applied Washcoatsuspension.
  • the energy input takes place - as I said - via a continuous or intermittent gas flow, which exerts a pressure on the surface of the pseudoplastic Washcoatsuspension.
  • the force that the gas / air flow thus exerts on the suspension surface, when the yield point is exceeded, leads to a shear and thus to the liquefaction of the washcoat.
  • the following embodiments of the gas / air nozzles or sounders are preferably used.
  • the length of the nozzle (I) is adapted to the diameter of the carrier (d), the nozzle being in the rule is equal to or greater than the diameter of the carrier.
  • nozzles with a nozzle length smaller than the diameter of the carriers can also be used or parts of the carrier surface can be completely or partially sealed off from the gas / air stream by an attached solid or perforated gas / air shield. In this way different areas of the washcoat surface can be leveled.
  • the pressure required for overcoming the flow limit of the washcoat gas / air flow can be adjusted by the skilled person by the choice of the injected gas / air pressure and the opening width of the louver in a suitable manner.
  • the opening width of the slot of the nozzle is 0.1 to 5 mm, preferably slot widths of 0.5 to 1 mm are used.
  • ultrasonic resonators With regard to the use of ultra or infrasound, a permanently mounted strip with several sound or pressure wave generators is recommended, preferably several ultrasonic resonators are used.
  • the leveling unit i. the unit for generating the continuous or pulsating gas / air flow can additionally be movable in the z-direction, whereby the volumetric flow of the gas which impinges on the surface of the washcoat can be regulated, and thus the pressure required to overcome the yield point can be set. As soon as the washcoat begins to flow, the distance of the air nozzle to the surface can be increased, which significantly reduces the risk of splashing.
  • the substrate monoliths to be provided with the washcoat suspension according to the present process are of the flow-through or wall-flow type. As a rule, they are cylindrical support bodies with a cylinder axis, two end faces, a lateral surface and an axial length L. From the first end face to the second end face, these are traversed by a multiplicity of channels.
  • the substrate monoliths are aligned vertically with the cylinder axis and the washcoat suspension is applied to the upper of the two end faces on the substrate monolith.
  • Flow monoliths are conventional catalyst carriers in the art which can be made of metal or ceramic materials. Preference is given to using refractory ceramics such as, for example, cordierite, silicon carbide or aluminum titanate, etc.
  • the number of channels per area is characterized by cell density, which is usually between 300 and 900 cells per square inch (cpsi).
  • the wall thickness of the channel walls is between 0.5 and 0.05 mm for ceramics.
  • Porous wall flow filter substrates of cordierite, silicon carbide or aluminum titanate are preferably used.
  • the outflow-side ends of the inflow passages and the inflow-side ends of the outflow passages are staggered with gas-tight "stoppers."
  • the exhaust gas to be purified which flows through the filter substrate, passes through the inflow passages Due to the porosity, pore / radius distribution, and thickness of the wall, the filtration property can be designed for particulate matter.
  • the catalyst material can be designed in the form of washcoat suspensions in and / or in the form of washcoat suspensions in and / or.
  • Wall flow monoliths extruded directly or with the aid of binders from the corresponding catalyst materials may also be used, that is to say that the porous walls consist directly of the catalyst material, as is the case, for example Fal may be the case of SCR catalysts based on zeolite or vanadium.
  • Such extruded SCR monoliths may additionally be provided with a washcoat suspension in and / or on the porous walls as described above.
  • Preferred substrates to be used can be taken from EP1309775A1, EP2042225A1 or EP1663458A1.
  • the washcoat suspensions used in the present invention are those typically used in the production of automotive exhaust catalysts.
  • the consistency of the washcoat in the context of the present invention should be designed so that they do not run immediately after application in the channels of the substrate monolith. This can be achieved through various measures.
  • the viscosity of the washcoat suspension can be adjusted in such a way (for example by additives such as thixotropic agents (eg as in WO2016023808A1) or by adjusting the concentration of the constituents or amount of the solvent used, by setting a certain temperature, etc.), that this only penetrates into the channels upon application of a negative pressure at the lower end side and / or an overpressure on the upper end side of the substrate monoliths.
  • means such as those contemplated in WO9947260A1 may be used to help prevent the washcoat from infiltrating the substrate monolith (eg, a closed iris or a permeable membrane).
  • the suspensions considered here are structurally viscous (https: //de.wikipeidia.org/wiki/Strukturviskosit%C3%A4t), have solids and contain the catalytically active components or their precursors as well as inorganic oxides such as alumina, Titanium dioxide, zirconium oxide, cerium oxide or combinations thereof, wherein the oxides may 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 , Ytterbium or combinations thereof.
  • noble metals such as platinum, palladium, gold, rhodium, iridium, osmium, ruthenium and combinations thereof can be used as catalytically active components.
  • metals may also be present as alloys with one another or with other metals or as oxides.
  • the metals may also be present as precursors, such as nitrates, sulfites or organyls of said noble metals and mixtures thereof, in particular palladium nitrate, palladium sulfite, platinum nitrate, platinum sulfite or Pt (NH 3 ) 4 (NO 3) 2 can be used.
  • Pt (NH 3 ) 4 (NO 3) 2 can be used.
  • the pseudoplastic coating medium often has a solids content of between 35 and 52% by weight.
  • the viscosities of the washcoat suspension are generally between 0.015 and 100 Pa * s, preferably 0.1-50 Pa * s and more preferably 1-50 Pa * s (viscosity: DIN EN ISO 3104: 1999-12).
  • different washcoats have different flow limits.
  • the yield point is the shear stress above which the sample behaves like a liquid. The yield point is thus the force that is needed to destroy the rest structure of a substance and to allow it to flow like a liquid.
  • these suspensions often have different high flow limits of 0.1 to more than 100 Pa.
  • the substrate monoliths are loaded from above with the coating suspension.
  • the substrate monoliths from above ie the upper end face is poured from above with the Washcoatsuspension.
  • a possible method can be taken from eg EP2415522A1.
  • the washcoat is soaked in and / or pressed into the substrate monolith.
  • the substrate monoliths are previously either wrapped with a protective cover or provided from above with a shape adapted to the shape of the end faces of the substrates vessel, so that the outer surfaces of the support body are not contacted with the coating suspension (see, eg, EP1900442A1).
  • the layer of the washcoat to be treated in the context of the present invention should not be too thick after application to the substrate monolith, nor should it be too thin.
  • the layer thickness of the suspension on the substrate monolith after leveling in the range of 0.5 to 15 cm, preferably 1 to 10 cm and more preferably 2 to 8 cm move, the thickness of the applied Washcoattik from the for coating the Channel walls of the carrier required amount of the suspension and its density and the size of the upper end surface of the substrate results.
  • the amount of coating in turn depends on the surface of the surface to be coated and the desired layer thickness on the support.
  • Also subject of the present device is one for coating a substrate monolith of the flow or wall flow type with a washcoat suspension.
  • the device makes it possible to successfully carry out the above-mentioned process.
  • the device it is necessary according to the invention that the device: a unit for locking the substrate monolith in an upright position;
  • the unit for locking the substrate monolith is known to the person skilled in the art.
  • Such a unit may, for example, be taken from EP2415522A1 already mentioned above.
  • the contactless leveling of an irregularly shaped washcoat surface preferably takes place via a laminar or turbulent, continuous or periodically intermittent air / gas flow.
  • the generation of the continuous gas flow can be achieved by overpressure. It is then steered onto the surface of the thick washcoat layer for leveling by means of a rotatable or horizontally movable gas / air nozzle (air knife, air brush).
  • a periodically occurring air / gas flow can be generated by a sound or pressure wave generator. Sound wave generators in the infra and ultrasonic range can be used here.
  • the periodically occurring air / gas streams are preferably generated by a high-frequency ultrasonic resonator, which is advantageously permanently mounted centered over the substrate monolith or freely movable in the plane or height.
  • the leveling of the liquid surface can also be carried out by combining the two methods.
  • the energy introduced can be reduced continuously or stepwise, either by increasing the distance of the smoothing unit to the surface or by reducing the air pressure or the resonator output.
  • the device has a unit which is capable of forming a collar around the substrate monolith such that no washcoate suspension can run downwardly on the substrate monolith during the application of the shear force in the form of a pressure.
  • the device according to the invention also provides a possibility to convey the applied and leveled washcoat suspension into the substrate monolith. This is done by a further suction or pressure unit on the device according to the invention. It is also possible and preferred to simultaneously convey the washcoat suspension into the substrate monolith by both means. This leads to a more uniform formation of the coating profile in the substrate monolith.
  • suction and pressure units are well known to those skilled in the art (see literature in the introduction).
  • a vacuum can preferably be applied to the lower end faces of the substrate monolith by, for example, opening a valve to an evacuated vacuum container.
  • the coated substrate monolith and the washcoat suspension to inert gas e.g. Nitrogen the upper end surface are supplied pressure.
  • this feed can also be changed one or more times or reversed, which according to US7094728B2 causes a more uniform coating of the channels in the support bodies.
  • an overpressure can also be applied (“blowing out” of the substrate monoliths).
  • air or another, the coated substrate monoliths and the Washcoatsuspension over inert gas such as nitrogen of the upper or lower end surface is supplied under pressure.
  • a negative pressure vacuum
  • air / gas pressure should not be applied from the opposite sides to ensure a flow rate sufficient to remove excess washcoat slurry from the channels of the substrate monoliths.
  • the overpressure can be supplied alternately from the upper and lower end faces.
  • the substrate monoliths can also be coated several times with washcoat suspensions. This can in principle be done before or after the calcination of the previously applied washcoat suspension, or else after a drying process. tion thereof by flowing gas, the latter being preferred.
  • the coating suspension may have the same or a different composition than the previously applied washcoat suspension in the case of several successive coating steps.
  • the support bodies are dried and then subjected to a heat treatment (calcination).
  • the essence of the present invention is that the leveling of the applied Washcoatsuspension prior to coating as completely as possible without contact and thus contamination or a change of the Washcoatsuspension can be completely excluded.
  • the force is applied according to the invention only on the near-surface layers of the washcoat and not in the complete suspension. By this procedure it is achieved that the rheological properties of the suspension only change near the surface, so that only at the surface a liquefaction of the material takes place by overcoming the yield point. This successfully prevents the entire amount of washcoat applied from being liquefied by the shear thinning and from entering the catalyst carrier in an uncontrolled manner before the application of the pressure pulse.
  • the method is additionally characterized by the fact that it requires no complex mechanics for rotating or vibrating the substrate.
  • the method according to the invention and the device according to the invention guarantee a homogeneous coating of the substrate monoliths and thus enable a more uniform catalytic activity of the finished catalysts.
  • the straight finish of the coating front enables a clearly defined zone boundary, which may possibly have a positive effect on the pressure loss.
  • the procedure according to the invention offers increased security against the local, uncontrolled escape of the coating suspension during the coating process. Leveling can prevent the washcoat from penetrating, which in turn reduces the reject rate in a metered batch process.
  • Leveling is the compensation of larger height differences within the thick washcoat layer as opposed to surface smoothing of thin layers to achieve a high quality, defect free surface of the finished product.
  • the sketches in Fig. 1 a-d represent various embodiments of a centrally rotatable gas / air nozzle again.
  • the length of the gas / air nozzle (flat nozzle, knife nozzle) is adapted to the diameter of the carrier.
  • the type of gas / air flow can be influenced by the type and shape of the outlet opening.
  • a laminar flow may be created by a continuous slot having a width of 0.5 to 5 mm, while a plurality of small exit holes rather than the through slot creates a turbulent flow.
  • a rotatably mounted flat nozzle can easily be set into rotary motion by a gas / air flow emerging perpendicularly to the axis of rotation through a separate opening mounted at the end of the nozzle.
  • other electrical or mechanical drives can be used to rotate the nozzle.
  • FIG. 2 shows schematic diagrams of a gas / air nozzle which is guided over the carrier in the x-direction for the smoothing process. Also, this flat nozzle may have a continuous slot or a plurality of individual air outlet holes.
  • the sketch shows a gas / air brush, which in its size and shape (round, oval, angular) corresponds to the geometry of the carrier used.
  • the gas / air flow exits through openings in the bottom plate whose size and number are selected so that the resulting air flow can exert sufficient pressure on the washcoat surface to overcome the yield point.
  • a pseudoplastic washcoat having a viscosity of 370 mPa * s at a shear rate of 150 / s and a solids content of 42% are presented in a dish. Due to the flow limit of the washcoat, an irregular surface forms during pouring.
  • an ultrasonic generator with a frequency of 20 KHz and a power of 4 KW is used. The sound generation and transmission to the ambient air via a circular sonotrode with a face of 3.8 cm 2 . After switching on the ultrasonic generator, the distance between the sonotrode and the surface of the washcoat is continuously reduced until at a distance of 1 to 2 cm the sound pressure of the air waves generated by the ultrasonic vibration produces a smoothing of the surface.
  • the sound pressure required for smoothing can also be adjusted by the control of the ultrasonic power itself.
  • Example 1 The washcoat of Example 1 is presented in a dish. Due to the pronounced yield strength of the washcoat used (about 100 Pa), an uneven surface forms during filling in the shell. A flat die with a slit width of 1 mm and a slit length of 6 cm is attached over the surface of the washcoat. The knife nozzle is connected to a compressed air supply and operated with an air pressure of 6 bar. By lowering the nozzle to the surface of the ceramic suspension, the flow limit of the washcoat is overcome at a distance of 10 cm from the surface by the generated pressure of the air flow, and the liquid surface levels out. Through a linear movement of the nozzle, the entire surface can be smoothed.
  • the person skilled in the art can choose the power of the generated laminar air flow so that the pressure exerted on the liquid surface can be adjusted specifically to the flow limit of the particular washcoat used.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Catalysts (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

La présente invention concerne un procédé et un dispositif de revêtement de supports de catalyseurs de gaz d'échappement d'automobile. L'invention concerne en particulier une amélioration de ce type de processus de revêtement, laquelle consiste en ce qu'une suspension contenant un matériau à effet catalytique (washcoat) est appliquée ou distribuée (processus dit « metered charge ») sur un support de ce type (monolithe de substrat).
EP18742726.5A 2017-07-06 2018-07-05 Nivellement sans contact d'une suspension d'enduction washcoat Pending EP3648884A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102017115138.9A DE102017115138A1 (de) 2017-07-06 2017-07-06 Kontaktlose Nivellierung einer Washcoatsuspension
PCT/EP2018/068199 WO2019008082A1 (fr) 2017-07-06 2018-07-05 Nivellement sans contact d'une suspension d'enduction washcoat

Publications (1)

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KR (1) KR102513068B1 (fr)
CN (1) CN111148570B (fr)
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CA (1) CA3068945A1 (fr)
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WO2024179974A2 (fr) 2023-03-01 2024-09-06 Umicore Ag & Co. Kg Dispositif d'application de revêtement

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CN111148570A (zh) 2020-05-12
US11590484B2 (en) 2023-02-28
WO2019008082A1 (fr) 2019-01-10
JP2020527100A (ja) 2020-09-03
BR112020000065A2 (pt) 2020-07-14
CA3068945A1 (fr) 2019-01-10
KR102513068B1 (ko) 2023-03-24
DE102017115138A1 (de) 2019-01-10
KR20200026875A (ko) 2020-03-11
JP7184823B2 (ja) 2022-12-06
US20200215523A1 (en) 2020-07-09
CN111148570B (zh) 2023-05-30

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