GB2578239A

GB2578239A - Methods of coating a metal foil flow-through substrate with one or more washcoat slurries

Info

Publication number: GB2578239A
Application number: GB1918831.7A
Authority: GB
Inventors: Kumar Mishra Hemant; Walia Ashish
Original assignee: Johnson Matthey PLC
Current assignee: Johnson Matthey PLC
Priority date: 2019-03-28
Filing date: 2019-12-19
Publication date: 2020-04-22
Also published as: GB201918831D0

Abstract

A method of coating a structured metal foil matrix in a mantle. The mantle has first and second overhangs at opposing ends into which the matrix does not extend. The matrix has a plurality of channels which are coated with wash-coat slurries having a catalyst by: (i) holding the substrate substantially vertically with a first end of the substrate being the upper end and introducing a first pre-determined volume of a first wash-coat slurry onto the substrate via open ends of the channels at an upper end of the matrix; (U) removing blockage from cells and wash-coat from a portion of the mantle, (iii) moving, flipping or inverting the mantle into a vertical position where the second end of the matrix is the upper end and introducing a second pre-determined volume of a wash-coat slurry onto the matrix via open ends of the channels at the upper end of the matrix, and (iv) repeating step (ii). Excess slurry is removed by air-knife. An apparatus for performing this method is also described. The matrix may for use as a catalyst in treatment of vehicle exhausts.

Description

METHODS OF COATING A METAL FOIL FLOW-THROUGH SUBSTRATE WITH ONE OR MORE WASHCOAT SLURRIES

FIELD OF THE INVENTION

The present invention relates to methods of coating a metal foil flow-through substrates comprising a plurality of channels with one or more washcoat slurries comprising one or more catalysts.

BACKGROUND OF THE INVENTION

Large numbers of emissions control devices comprising coated monolithic flow-through substrates are manufactured each year. One of the principal uses of such devices is for the treatment of exhaust gases produced by an internal combustion engine, particularly a vehicular internal combustion engine. These substrates contain a plurality of channels that bring the exhaust gas into contact with a coating on the channel walls within the substrate. This coating may trap, oxidize and/or reduce constituents of the exhaust gas that are hazardous to human health or that are environmentally unfriendly. This is distinct from wall-flow substrates where the gas is required to pass through a channel wall that forms a passage.

Monolithic substrates are made of one of two broad classes of materials: ceramic and metal. Ceramic substrates are most common with wide usages in a variety of vehicles such as cars and trucks. Metal substrates are generally used in special environments, such as in cars, trucks and motorcycles. The properties of the ceramic materials and the metals used to make the substrates are different. This can result in differences in the structure/configuration of the substrates, the compositions and structure of washcoats containing one or more catalysts and the methods of manufacturing washcoated substrates.

The substrate may be provided with a coating, also known as a washcoat, which preferably comprises a catalyst. The coating may be applied to the substrate as a washcoat slurry that is passed through the passages of the substrate and becomes deposited on, an attached to, the walls of the passage. Various methods for applying a washcoat slurry to a substrate are known.

One such method, used with ceramic substrates, involves applying a washcoat slurry to a first face of the substrate (e.g. a lower face) and subjecting an opposite, second face (e.g. a higher face) of the substrate to at least a partial vacuum to achieve movement of the washcoat through the passages in the substrate. Another method applies a washcoat slurry to a first face of the substrate (e.g. an upper face) and allowing gravity to move the slurry down the substrate toward the second face of the substrate (e.g. a lower end). At least a partial vacuum can be used to assist in the movement of the washcoat slurry through the passages in the substrate. In each of these methods, after coating, the substrate can be dried and calcined. In methods where one or more washcoats are applied to part, but not all of a matrix, a substrate can be dried after a first application is made to the substrate and then dried and calcined after a washcoat application to the part of the matrix in the first application.

The method of applying one or more washcoat slurries on a flow-through substrate can depend upon the nature of the catalyst(s) and the required configuration of the catalyst(s) on the substrate. If a substrate having a single zone is desired, a substrate can be coated with a single dose of a washcoat slurry in a single step with the substrate remaining in a single orientation.

When a substrate requires either a single zone, or two zones in series, a coating can be applied to the first face and coat a portion, but not all, of the length of the substrate. The partially coated substrate can then be inverted so that the second face is uppermost and a washcoat slurry can then be applied to the second face in order to coat the portion of the substrate that was uncoated by the first dose. Such a two-dose process can allow different coatings to be applied to each end of the substrate.

To provide the best performance of the substrate, it may be beneficial to ensure that the substrate is fully coated so that the surface area of the coated substrate is maximized. Depending upon the required configuration for a coated substrate, it can also be beneficial to ensure that portions of the substrate are not coated by more than one layer of washcoat (for example, in a two-dose process) as this can lead to increased pressure loss within the substrate. It is therefore desirable that the process of applying the washcoat to substrates achieves reliable and controllable coating profiles of the substrates.

WO 99/47260 describes an apparatus and a general method for coating a monolithic support. The method of coating a monolithic support comprises the steps of: (a) locating a containment means on top of a support, (b) dosing a pre-determined quantity of a liquid component into said containment means, either in the order (a) then (b) or (b) then (a), and (c) by applying pressure or vacuum, drawing said liquid component into at least a portion of the support, and retaining substantially all of said quantity within the support. This method is typically used to apply a washcoat having a relatively high viscosity.

A method for uniformly applying a washcoat slurry onto the walls of a substrate is described in WO 2011/080525. The method described in WO 2011/080525 of coating a honeycomb monolith comprising a plurality of channels with a liquid comprising a catalyst component, comprises the steps of: (i) holding a honeycomb monolith substantially vertically; (ii) introducing a pre-determined volume of the liquid into the monolith via open ends of the channels at a lower end of the monolith; (iii) sealingly retaining the introduced liquid within the monolith; (iv) inverting the monolith containing the retained liquid; and (v) applying a vacuum to open ends of the channels of the monolith at the inverted, lower end of the monolith to draw the liquid along the channels of the monolith.

Apparatus for automatedly coating a honeycomb monolith flow-through substrate is known, for example, from WO 99/47260, W02015/015122 and U.S. Pat. No3. 5,422,138.

US 8,703,236, and US 9,415,365, each of which are hereby incorporated by reference. The latter reference discloses an apparatus comprising means for holding a honeycomb monolith substrate substantially vertically and means for introducing a pre-determined volume of a liquid into the substrate via open ends of the channels at a lower end of the substrate.

SUMMARY OF THE INVENTION

The invention relates to methods of coating a matrix in a mantle with one or more washcoat slurries comprising a catalyst by applying one or more washcoats in one or more passes.

The methods comprise: (a) providing (i) a matrix in a mantle and (ii) a first washcoat slurry, the mantle having an axial length, a first end, a second end, an interior,a first overhang and a second overhang, the matrix having an axial length, a first end and a second end, the matrix comprising a metal foil flow-through monolith comprising metal foil having a structure comprising a plurality of channels which extend longitudinally along the length of the flow-through monolith and the channels have a first end and a second end and the first end and the second end are open and the channels are formed by corrugation of the metal foil, wherein the matrix is connected to the interior of the mantle and the axial length of the mantle is greater that the axial length of the matrix, wherein the mantle comprises a first overhang and a second overhang, wherein the first overhang and the second overhang are each portions of the mantel along the axial length of the mantle, the first overhang is between first end of the mantle and the first end of the matrix and the second overhang is between second end of the mantle and the second end of the matrix, and wherein the difference between the length of the mantle and the length of the matrix is equal to the sum of the height of the first overhang and the height of the second overhang.

(b) forming a first washcoat on the matrix, wherein forming the washcoat on the matrix comprises: (i) orienting the mantle substantially vertically where the first end of the mantle is the upper end of the mantel, and forming a first washcoat on the matrix, (ii) applying a predetermined amount of a first portion of a first washcoat slurry onto the matrix through the open ends of the channels at the first end of the matrix and (iii) pulling the washcoat slurry through the matrix using a vacuum, wherein forming the first washcoat forms one or both of: ( I) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c) removing at least one of a washcoat layer from the first overhang and blockage from one or more channels at the first end of the matrix, wherein removing at least one of the washcoat layer and blockage comprises air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the mantel is in a vertical position and the first end is the upper end, (d) removing at least one of a washcoat layer from the second overhang and blockage from one or more channels from the second end of the matrix, wherein removing at least one of the washcoat layer and blockage comprises moving the mantle into a vertical position where the second end of the mantel is the upper end and air-knifing the washcoat layer from the second overhang and blockage from the second end of the matrix while the mantel is in a vertical position and the second end is the upper end.

The method further comprises drying the washcoat on the overhang and the matrix and then calcining the washcoat on the matrix.

The method can further comprise forming a second washcoat on the first washcoat, wherein the second washcoat is formed by: I 5 (b2a) applying a predetermined amount of a second portion of a first washcoat slurry onto the matrix through the open ends of the channels at the second end of the matrix, or (b2b) applying a predetermined amount of a second washcoat slurry onto the first washcoat through open ends of the channels at the first end or the second end of the matrix, wherein steps (b2a) and (b2b) further comprise pulling the washcoat slurry 20 through the matrix using a vacuum, and wherein steps (b2a) or (b2b) form: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang. The method can further comprise performing steps (c) and (d) after step (b2a) or (b2b), then drying the washcoat on the overhang and the matrix and calcining the washcoat on the matrix and the overhang.

The method can further comprise forming a third washcoat on the second washcoat, wherein the third washcoat is formed by: (b3a) applying a predetermined amount of a second portion of a second washcoat slurry onto the matrix through the open ends of the channels at the second end of the matrix, or 3 0 (b3b) applying a predetermined amount of a third washcoat slurry onto the second washcoat through open ends of the channels at the first end or the second end of the matrix, wherein steps (b3a) and (b3b) further comprise pulling the washcoat slurry through the matrix using a vacuum, and wherein steps (b3a) or (b3b) form: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang.

The method of can further comprise performing steps (c) and (d) after step (b2a) or (b2b), then drying the washcoat on the matrix and the overhang and calcining the washcoat on the matrix and the overhang.

Step (c) can further comprise providing a secondary vacuum through the matrix at the low end of the mantle after air knifing the first end.

Applying the secondary vacuum can provide increased air flow around the periphery of the matrix relative to the center of the matrix.

Applying the vacuum can provide an increased gas flow around the periphery of the matrix relative to the center of the matrix.

The method can further comprise providing a vacuum through the matrix at the low end of the mantle after air knifing the second end of the matrix.

The matrix can comprise channels at a density of 100 to 900 channels per square inch (cpsi).

The matrix can comprise a corrugated structure.

The corrugated structure can comprise: (a) longitudinal structure design; (b) a transversal structure design; (c) a perforated design; (d) a combined perforated and longitudinal structure design, or Micro Holes, preferably a perforated design.

At least one the first washcoat slurry, the second washcoat slurry and the third washcoat slurry can comprise one or more of a three-way catalyst, a NOx trap, a catalysed soot oxidation catalyst comprising a supported platinum group metal or a N143-SCR catalyst.

At least two the first washcoat slurry, the second washcoat slurry and the third washcoat slurry can comprise one or more of a three-way catalyst, a NO trap, a catalysed soot oxidation catalyst comprising supported platinum group metal or a NHL-SCR catalyst.

Each of the first washcoat slurry, the second washcoat slurry and the third washcoat slurry can comprise one or more of a three-way catalyst, a NO trap, a catalysed soot oxidation catalyst comprising supported platinum group metal or a NHL-SCR catalyst.

The first washcoat slurry and the second washcoat slurry can differ by one or more of the concentrations of catalyst in the washcoat and composition of the catalyst.

The first washcoat slurry can comprise Pd and the second washcoat slurry comprises Rh. In step (b), (b3a) or (b3b), when the first portion of the first washcoat slurry is applied to the matrix, the mantle can be in a vertical orientation where the first end is the upper end and the second end is the lower end.

In step (b2a) or (b2b), when the second portion of the first washcoat slurry is applied to the matrix, the matrix can be in a vertical orientation wherein the second end of the matrix is the upper end and the first end of the matrix is the lower end.

Step (d) can further comprise applying a vacuum to the open ends of the channels at the lower end of the matrix after air knifing to remove material from the periphery of the matrix after air knifing.

The vacuum can be greater at the periphery of the matrix than the central portion of the matrix when a restrictor plate is present within the gas flow resulting from the application of a vacuum when the restrictor plate in located at or under the lower end of the matrix.

An apparatus for dosing one or more washcoats on a metal foil flow-through substrates comprises: (a) a mantel orientation station comprising a mantel holder wherein the mantle holder holds the mantle substantially vertically where the first end of the mantle is the upper end of the mantel, and holds the mantle during application of a washcoat slurry to the matrix, (b) a washcoat slurry dosing station comprising: (1) a washcoat applicator that delivers a predetermined amount of a washcoat slurry to the open ends of the channels at the first end of the matrix, and (2) a vacuum, (c) a doser washcoat removal station comprising an air knife and a secondary vacuum, air knife configured to blow a stream of a gas against a washcoat layer on a first overhang on the mantle and across a first end of a matrix, (d) a mantle flipper station, comprising a flipper (e) a drier washcoat removal station comprising an air knife (f) a secondary vacuum station comprising a vacuum orientation device (g) a drier station comprising an oven and a mantle mover, wherein the mantle mover transports a plurality of mantles through the plurality of heating zones, (h) a calcination oven station having a plurality of heat zones and a mantle mover, wherein the mantle mover transports plurality of mantles through the plurality of heating zones, 5 and (i) a controller linked to more or more of stations, wherein the controller monitors and/or controls one or more of the stations.

The inventors have developed a method of coating metal substrates with washcoat slurries that enables accurate loading of the washcoats while reducing the potential for clogging of cells in the substrate and losses or inefficient use of catalysts.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more fully understood, reference may be made to the description of various substrates and representations portions of method steps of the invention shown in the accompanying drawings.

Figure 1 shows a representation of the mantle and the matrix showing the locations of the overhangs.

Figures 2 shows Figure 3 shows a schematic representation of a 1 dose, 1 pass method.

Figure 4 shows a schematic representation of a 2 dose, 1 pass method.

Figure 5 shows a schematic representation of a 2 dose, 2 pass method.

Figures 6A and 6B are schematic representations of two different 3 dose, 2 pass methods.

Figure 7 shows a schematic representation of a 3 dose, 3 pass method.

Figure 8 shows a schematic representation of two apparatus for coating a matrix in a mantle with a washcoat slurry comprising a catalyst.

DETAILED DESCRIPTION OF THE INVENTION

The current invention relates to methods and apparatus for coating a matrix in a mantle with one or more washcoat slurries comprising a catalyst. The matrix in a mantle and the portions of the mantel, as described herein, is shown in Figure 1.

The mantle is a metallic tube having an axial length, a first end, a second end, an interior, a first overhang and a second overhang. The matrix is located within the interior of the mantle and is attached to the mantle.

The term "matrix" as defined herein refers to a metal foil flow-through substrate which is a flow-through monolith comprising metal foil having a structure comprising a plurality of channels, sometimes referred to as cells, which extend longitudinally along the length of the monolith. The matrix has an axial length, a first end and a second end. The channels are formed by corrugation of the metal foil. The channels can extend the length of the matrix. The channels can also have breaks in the channels. The breaks in the channels can be holes in the metal structure, openings formed by the metal structure or both.

The matrix is connected to the interior of the mantle. Preferably the connection is a permanent connection, such as brazing or welding.

The axial length of the mantle is greater that the axial length of the matrix.

The mantle comprises a first overhang and a second overhang, wherein the first overhang and the second overhang are each portions of the mantel along the axial length of the mantle. The first overhang is located between first end of the mantle and the first end of the matrix and the second overhang is located between second end of the mantle and the second end of the matrix. The difference between the length of the mantle and the length of the matrix is equal to the sum of the height of the first overhang and the height of the second overhang.

Matrix In a standard foil matrix, each channel extends the entire length of the matrix. Consequently, exhaust gases entering through a first face of the substrate into a passage pass through the substrate within the same passage until the exhaust gases exit a second face of the substrate. Gas flow in this type of substrate is turbulent at the first face but becomes laminar as gas flow down the passage.

Improvements in matrix design provide turbulent flow of exhaust gases within most of the structure of the substrate. These improvements resulted in changes in the channels where each channel does not run uninterrupted through the length of the matrix, but rather use channels having different types of breaks in the channels. There are two major groups of known metal foil flow-through substrates: corrugated design and perforated foils.

Corrugated design foils use additional corrugation and/or perforation within the channels compared to a standard foil substrate. (Lorenzo Pace and Manuel Presti, Changing the Substrate Technology to met future Emission Limits, SAE International, 2010-01-1550) (Jayat Francois, et al., Application of a LS metal Catalyst Substrate for BS IV Two and Three Wheelers, SAE International, 2015-26-0098) (Held, W., et al., 1994. "Improved Cell Design for Increased Catalytic Conversion", SAE Technical Paper 940932) These designs were developed to induce radial gas flow and increased turbulence through the entire length of the substrate. One type of design is known as transversal structure technology (TSR). Metal foil substrates having a TS design are embossed with secondary micro-corrugations that run at an angle across the direction of the flow. A second type of design is known as longitudinal structure technology (LSR). LS technology consists of a counter corrugation applied on the sinusoidal part of the single channel in order to create some turbulent-like areas. In an LS channel, the laminar flow is broken as a result of the counter corrugation, (also known as a shovel) and a new "turbulent like" zone is created.

The second group of metal foil substrates uses a plurality of holes in one or more portions of the substrate. One type of metal foil substrate, known in the art as a PE flow-through substrate, or perforated substrate, uses standard foil (normal metal foil) with corrugations and make holes in it. (Michael Rice, et al Innovative Substrate Technology for High Performance Heavy Duty Truck SCR Catalyst Systems, SAE International, 2007-01-1577) Other types of metal foil substrates combined a PE structure with other types of structure, such as an LS® structure. Another type of metal foil substrate is known as Micro Holes or an MH substrate. The holes in these substrates are smaller than those in PE substrates, with standard hole diameters ranging from 0.5 mm to 0.9 mm.

Washcoat The term "washcoat", as used herein, refers to a mixture comprising high surface area inorganic oxides (also known as supports) and a catalyst comprising catalytically active metals on the inorganic oxides. A washcoat can further comprise one or more additives selected from the group consisting of adhesion agents, rheology modifiers, defoamers, dispersing agents and surfactants.

The term "washcoat slurry", as used herein, refers to a mixture comprising a liquid, preferably water, and the washcoat. The washcoat slurry is applied to the substrate.

The composition, also known as the formulation, of the washcoat varies widely I 0 depending upon a number of factors including, but not limited to, the catalyst being used, the support on which a catalyst can be placed, the substrate being used, the adhesion agent needed, and the conditions of use of the catalyst. General methods for the development of the washcoat and materials that can be used in the washcoat are known to those skilled in the art and include: aqueous solutions of platinum group metal compounds, such as platinum, palladium and rhodium compounds, aqueous solutions of alkali metal and alkaline earth metal compounds for depositing compounds for absorbing NO on the substrates, and other components such as compounds of transition metals e.g. iron, copper, vanadium, cerium and transition metal catalyst promoter compounds; washcoat slurries including particulate catalyst support materials such as alumina, ceria, titania, zirconia, silica-alumina and zeolites, optionally supporting one or more of the above mentioned platinum group metals or transition metals; and washcoat slurries containing combinations of supported metal compounds and aqueous solutions of the above mentioned metal compounds. The washcoat can also include relevant acids, organic compounds thickeners etc. to improve the catalyst activity, chemistry of the formulation to suit the intended purpose of the resulting catalyst, and/or the viscosity and rheology of the washcoat.

A washcoat slurry applied to the matrix can comprise a three-way catalyst, a NOx trap, an NHL-SCR catalyst, an ammonia slip catalyst (ASC) comprising an ammonia oxidation catalyst and an SCR catalyst, a diesel oxidation catalyst (DOC), a diesel exotherm catalyst (DEC), a catalyst for oxidizing soot, a NOx absorber, a selective catalytic reduction/passive NOx adsorber (SCR/PNA), a cold-start catalyst (CSC), or combinations of one or more of these. The three-way catalyst can comprise two or three different platinum group metals (PGM) in either separate washcoats or with two or more PGMs in a single washcoat.

Generally, the washcoat solids content selected for a given washcoat loading is dependent upon the washcoat loading and the axial length of the coating that needs to be applied. The precise washcoat solids content required can be determined by methods know to one skilled in the art. Typically, however, the washcoat solids content will be in the range of about 5-50% solids. When coating different axial lengths on the matrix with the same washcoat loading, generally, the shorter axial length has a higher the washcoat solids content. When coating substrates used in motorcycles, generally each dose is 100% coat length of the axial length of the motorcycle substrate. However, in some configurations each dose can be coated over less than 100% of the axial length, such as about 50-100% of the axial length, about 75-100% of the axial length or about 50-75% of the axial length.

Two of the washcoats, or washcoat slurries, can comprise the same components where the components have a different loading in the washcoat. When the first two washcoats to be applied differ in the loadings, but not their components, these washcoats are designates as WC 1A and WC1B. When the second and third washcoats to be applied differ in the loadings, but not their components, these washcoats are designated as "WC2A" and "WC2B". The relative loadings of two washcoats that differ in the loadings, but not their components, are A and B, where A + B = 1.

One or more of the washcoats can comprise a single catalyst or a combination of two or more catalysts Air knife The term "air knife" refers to a tool used to remove washcoat slurry from portions of mantle and/or matrix using a controlled stream of air. The term "air knifing" refers to the process of removing the washcoat slurry from mantle and/or matrix using an air knife. The objectives of using the air knife is to: (1) remove washcoat remaining on the overhang of the mantle after dosing and push it down the cells, and (2) avoid any sort of throwback of the washcoat after application of air knife is complete. Both the objectives are satisfied only when the air stream from the air knife is an angular air stream, that is the air stream from the air knife is neither parallel nor perpendicular to the face of the substrate. One skilled in the art would recognize that various factors, such as the composition of the washcoat, the loading of the washcoat on the matrix, the air knife and the air knife nozzle used, the air pressure used by the air knife, and the angle of the air-flow from the air knife relative to either the first end of the mantle or the matrix, affects removal of washcoat from the mantle and the matrix. Such a person would be able to determine the optimal angle to used based on at least these factors. Generally, air knifing can be performed at an angle from 25 to 45 degrees, preferably 30 to 40 degrees, relative to the face of the matrix.

The air pressure used in air knifing can vary according to the air knife used and the material to be removed. Generally, air pressure can range from 0.1 Mpa to 0.5 Mpa, preferably from 0.2 Mpa to 0.4 Mpa.

The method can comprise one or more air knifings, preferably two or more air knifings, preferably the air knifings per washcoat application. The first air knifing can be performed on the end of the matrix where the washcoat was applied, while the second air knifing can be applied to the opposite end of the matrix, that it, to the end of the matrix to which the wash moved after it was applied to one end of the matrix. This can be performed after the matrix has received a washcoat application and is then flipped. The third air knifing can be performed before the drying step, preferably before drying, more preferably while positioning the mantel to enter the drier. If some configurations, the air knifing can be performed in a drying station. While the first two air knifings remove washcoat remaining on the overhang of the mantle after dosing and push it down the cells and washcoat from an end of the matrix, the third air knifing pushes the washcoat inside the matrix but does not remove washcoat from an overhang.

Vacuums Two types of vacuums can be used. The first type of vacuum, herein referred to as "vacuum" is used in the application of the washcoat to the substrate. The second type of vacuum is referred to as a "secondary vacuum". The secondary vacuum refers to a vacuum applied to the matrix after a vacuum is applied to move the washcoat down the matrix from the end where the washcoat is applied.

There are several important factors related to the application of the vacuum. These factors, which can depend upon the properties of the washcoat slurry include the timing of the start of the vacuum, the duration of the vacuum, the strength of the vacuum and the distribution of the vacuum.

The vacuum can be applied during the application of the washcoat to first end of the matrix. Preferably the vacuum is applied after the application of the washcoat to first end of the matrix, where that amount of time can range from about 0. I seconds to about 2 seconds, depending on the washcoat solids content and size of the matrix. However, typically vacuum applications can be of the order of about 1 second. One skilled in the art would understand that I 0 the amount of time the vacuum is applied can depend upon the formulation of the washcoat slurry, the size of the matrix and the amount of vacuum applied. One skilled in the art would recognize that the amount of vacuum applied is a function of both the strength of the vacuum (measured in millimeters of mercury (mmHg) or pascals (Pa) below standard atmospheric pressure) and the capacity of the vacuum system of obtain the strength of the vacuum. The vacuum applied will generally be in the order of -10 kpa to -60 kpa, preferably -10 to -50 kpa, more preferably -20 kpa to -40 kpa.

The duration of the vacuum applied will also depend upon the nature of the washcoat slurry, the length of the coating on the matrix and both the strength of the vacuum (measured in millimeters of mercury (mmHg) or pascals (Pa) below standard atmospheric pressure) and the capacity of the vacuum system of obtain the strength of the vacuum. The duration of the vacuum generally ranges from about 0.1 to about 10 seconds, preferably about 0.1 to about 5 sec, more preferably about 0.1 to about 2 sec.

The vacuum can be applied using a system that can take any suitable form. Preferably a part of the system comprises a funnel shape where the wide end of the funnel is located under the mantel during application of the washcoat and air knifing of at least overhang of the first end that the washcoat is applied to. The narrower end of the funnel is preferably connected to a vacuum source and a trap that recovers washcoat removed from the mantel and matrix during the application portion of the methods described herein. The recovered washcoat can be recycled back into the main washcoat tank during the manufacturing run.

Secondary vacuum The secondary vacuum refers to a vacuum applied to the matrix after a vacuum is applied to move the washcoat down the matrix from the end where the washcoat is applied. A secondary vacuum can be used to pull any material from periphery post air knife application. Secondary vacuum can be used when air knifing each of the overhangs and the corresponding end of the matrix. When the first air knifing is performed after application of the washcoat to the matrix, a slight delay, about 0.1 to about 2 seconds, preferably about 0.5 seconds, between the end of the air knifing and the secondary vacuum is preferred, as this has been found to make air flow through periphery cells more effective. After the first air knifing has been performed, the mantle can be rotated to position the end of the mantle that had been air knifed (the upper end) so that end that was treated becomes the lower end and the new upper end is then air knifed. When the second end is air knifed, preferably the air knifing does not occur with a secondary vacuum. Preferably a secondary vacuum is applied to the matrix before drying of the washcoat(s) on the matrix.

The vacuum is preferably applied with a non-even distribution across the face of the matrix with increased vacuum at the periphery of the matrix. This can be used to assist in minimizing the formation of blockage in the channels in the matrix. A restriction plate located below the matrix and within gas flow towards a vacuum can be configured to have higher air flow in columns in the periphery of the matrix.

A restriction plate can be located within an apparatus that applies a vacuum and a secondary vacuum to collect washcoat removed from the overhang and the end of the matrix on which the washcoat was applied. Preferably the application is made using an application device comprising a cone shape below the mantle. The restriction plate can be a plate located directly below the catalyst where the air flow from the vacuum is increased at the periphery more blockage of the channels can occur relative to the center of the matrix. The restriction plate can facilitate moving at least 50% of the air flow through the peripheral cells while the remaining air flows through the other part of the matrix.

Application of a secondary vacuum along with use of a restriction plate, preferably in a cone in an application device directly under the mantle, can help to achieve the following improvements in coated substrates made by the processes described herein compared to a matrix formed without the use of a secondary vacuum as described above: 1. After dosing, the peripheral channels in the matrix tend to have a thicker washcoat layer than the other channels and this increased thickness tends to create blockage. When the thicker washcoat forms at the periphery, it is often necessary to thin down the washcoat layer, especially when another washcoat application will be made in another pass.

2. Use of the air knife can push washcoat removed from the overhang into the peripheral channels. This can thicken the washcoat layer in the peripheral channels, and, as described above the washcoat may need to the thinned to prevent blockage in another pass.

3. It is important to have minimal blockages of the channels. Minimal means < 5%, < 4%, <3%, < 2%, < 1%, < 0.9%, < 0.8%, < 0.7%, < 0.6%, < 0.5%, < 0.4%, < 0.3%, < 2%, or < 0.1%, preferably < 1%, < 0.9%, < 0.8%, < 0.7%, < 0.6%, < 0.5%, < 0.4%, < 0.3%, < 2%, or < 0.1%, more preferably < 0.5%, < 0.4%, < 0.3%, <2%, or < 0.1%, where the blockages are based on their the total number of cells in the matrix of the number of cells per in' or cm2.

The vacuum can be applied using any number of physical structures. Preferably, when the matrix is in a substantially vertical position and a either a washcoat is being applied to the matrix or portions of the matrix are being air knife, a structure comprising a funnel shape is located under the matrix with the wider end of the funnel shape directed towards the matrix. The term "substantially vertically" used herein with reference to the position of the substrate refers to an arrangement where the central axis of the substrate is ± 5° from the vertical, preferably ± 3° from the vertical, such as ± 0° from the vertical (i.e. perfectly vertical within measurement error).

Washcoat Application A washcoat slurry can be applied to channels in a matrix by depositing a predetermined 30 portion of the washcoat onto the channels. The washcoat can be applied by methods know to one skilled in the art. Preferably, the washcoat is pass through device that enable a uniform distribution of a washcoat across the open channels of the matrix, such as a mini-showerhead, and then deposited on the matrix. A vacuum can be applied to the opposite end of the matrix from where the washcoat slurry is being applied to assist in moving the washcoat through the matrix.

The amount of the washcoat slurry that is applied can be either: sufficient to coat all or almost all of the targeted length of the substrate or be in excess of the amount required to coat the entire length of the matrix. The term "sufficient to coat all or almost all of the targeted length of the substrate" means that at least 90%, preferably at least 95%, more preferably at least 97% of the targeted length of the matrix is coated by the washcoat. In many applications, the amount of washcoat applied is in excess of the amount required to coat the entire length of the matrix.

This can be important in avoiding forming a partial coating on the substrate and having parts of the substrate not receiving a coating. Preferably the excess amount of washcoat is collected and recycled. When the washcoat is applied in excess to the amount required to coat the entire length of the matrix, careful use of the vacuum allows a pre-determined amount of washcoat slurry and catalyst to be retained on the substrate.

Various apparatus and methods of dosing a predetermined amount of the coating media (which could be washcoat slurry) are known in the art. Some of these apparatus and method relate to the application of washcoat on an upper (top) face of a matrix, where a washcoat slurry dispensed on the top face of the monolith moves into the channels of the matrix using vacuum.

The volume and composition of the washcoat slurry, along with various process parameters, such as vacuum strength, are selected to ensure that a pre-determined amount of washcoat is retained on the substrate.

Drying After the matrix has received a washcoat, it can be dried. Drying typically involves heating the washcoat coated substrate in air at a temperature of 80 to 150° C., preferably about 100° C., until dry. Dryness is defined as the state in which at least 90%, preferably at least 95 %, more preferably 95-100% of the moisture has been removed from the coated substrate.

Calcining The method can further comprise the step of calcining the washcoated substrate. As used herein, the term "calcine", "calcining" or "calcination", means heating the material in air, oxygen or an inert atmosphere. This definition is consistent with the IUPAC definition of calcination.

(IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.) Calcination is performed to decompose a metal salt and promote the exchange of metal ions within the zeolite and also to adhere the zeolite to a substrate. The temperatures used in calcination depend upon the components in the material to be calcined and generally are between about 300° C. to about 900° C, preferably about 400° C to about 800° C, more preferably about 400° C to about 600° C. Calination can be performed for about 5 minutes to about 8 hours, preferably about 5 minutes to about 4 hours, more preferably about 5 minutes to about 1 hour, even more preferably about 5 minutes to about 30 minutes.

One measure of the acceptability of the coated catalyst article, which regard to channel blockage, is the aperture rate of the catalyst. The aperture rate of the catalyst is defined as the difference between the aperture rate of the inlet and the aperture rate of the outlet, which can be expressed as: Aperture Rate of catalyst = Aperture Rate of Inlet -Aperture Rate of Outlet' The aperture rate of the inlet (or outlet) is defined as the % area of the open portion. These values can be obtained by taking an image of the inlet end and the outlet end and using a digital camera and image analysis software.

The production of an article comprising a wash-coated substrate generally involves two major types of interrelated processes: dosing (or dose) and passes (pass). Dosing relates to the process of applying a material onto the substrate. Each time a material is applied to the substrate, is considered to be a dose. The term "pass" refers to the number of times the substrate passes through a series of processes comprising applying a washcoat, removing washcoat from overheads and one or more ends of the matrix, drying the matrix comprising a washcoat slurry and calcining the washcoat before it can be classified as a finished good. Only when the substrate has completed going through all passes is the substrate a finished good. Until all of the passes have been completed, the substrate is only an intermediate good. In the methods described below, the steps of drying and calcining are shown.

In the description of the methods below, the following variables are used: Variables Related to Application of Washcoat Volumes

Variable Description Units

X Amount of Washcoat 1 (WC 1) to be coated on substrate Gel or g/1 V Amount of Washcoat 2 (WC 2) to be coated on substrate Gel or g/1 A Relative Amount of X or Y, where X + Y =1 none B Relative Amount of X or Y, where X + Y =1 none A method for applying a washcoat onto a matrix using a 1 Dose -1 Pass procedure is described below.

1 Dose -1 Pass Coating Washcoat Washcoat Pass Loading Identity

V X WC I

A single washcoat is applied onto the matrix. The resulting matrix can be dried and calcined. The washcoat can comprise a single catalyst or a combination of two or more catalysts.

Methods for applying two washcoats onto a matrix using a 2 Dose -1 Pass procedure are described below.

2 Dose -1 Pass Coating Washcoat Washcoat Washcoat Washcoat Dose Identity Length % Dose Identity Length % I WC I X 1sr WC I X 2nd WC I I 00-X 2"6 WC2 I00--X A first washcoat is applied to a portion (X), but not all of the length of the matrix from a first end of the matrix. The resulting matrix can then be dried. A second dose is applied to the portion of the matrix that did not receive the first dose (100-X). The washcoat applied in the second dose can be the same or different than that applied in the first dose. The resulting matrix with the two washcoats can then be dried and calcined.

One or more of the washcoats can comprise a single catalyst or a combination of two or more catalysts.

Methods for applying two washcoats onto a matrix using a 2 Dose -2 Pass procedure are described below.

2 Dose -2 Pass Coating Washcoat Washcoat Washcoat Washcoat Pass Identity Loadino Pass Identity Loading 1 WC IA A 14 WC1 - 2rid WC1B B 2"6 WC2 Two different types of coatings on a matrix are possible.

In the first type of coating, two washcoats with different relative amounts of the washcoat loadings, A and B, are applied onto the matrix using two separate applications. The first application has a relative washcoat loading of A. After the first application been made, the washcoated matrix is dried and calcined, and then a second application using a washcoat with a relative washcoat loading of B is made onto the matrix having the washcoat loading of A. The resulting matrix with the two washcoats can then be dried and calcined.

In the second type of coating, a first washcoat is applied onto the matrix, which is then dried and calcined. A single application of the second washcoat is then applied onto the matrix over the first washcoat, and then the resulting matrix can then be dried and calcined.

Methods for applying three washcoats onto a matrix using a 3 Dose -2 Pass procedure are described below. .3 Dose -2 Pass Coating Washcoat Washcoat Washcoat Washcoat Dose Pass Identity Length % Dose Pass Identity Length % 14 14 WC1 X 14 1c' WC1 Entire 2th 14 WC2 100-X 2th 2th WC2 X 3rd ri WC3 All or part 3rd 2nd WC3 100-X Two different types of coatings on a matrix are possible.

In the first type of coating, a first washcoat is applied to a portion (X), but not all of the length of the matrix from a first end of the matrix. The first washcoat applied then can be dried. A second dose is applied to the portion of the matrix that did not receive the first dose (100-X). The washcoat applied in the second dose can be the same or different than that applied in the first dose. The resulting matrix with the two washcoats can then be dried and calcined. A third washcoat is then applied over all or a portion of the second washcoat. The resulting matrix can then be dried and calcined.

In the second type of coating, a first washcoat is applied to the entire length of the matrix. The resulting matrix can then be dried and calcined. A second washcoat is applied to a portion (X), but not all of the length of the matrix from a first end of the matrix. The resulting matrix can be dried. A third washcoat is applied to the portion (100-X) of the matrix that did not receive the second washcoat. Each of the washcoats can be the same or different than the other washcoats. The resulting matrix with the two washcoats can then be dried and calcined.

Method for applying three washcoats onto a matrix using a 3 Dose -3 Pass procedure are described below.

3 Dose -3 Pass Coating Washcoat Washcoat Washcoat Washcoat Washcoat Pass Identity Loading Identity Loading Identity 1' WC 1 A A W Cl WC1 2' WC I B B WC2A A WC2 3rd WC2 WC2B B WC3 Three different types of coatings on a matrix are possible.

In the first type of coating, two washcoats with different relative amounts of the washcoat loadings, A and B, are first applied onto the matrix using two separate applications. The first application has a relative washcoat loading of A. After the first application been made, the washcoated matrix is dried and calcined, and then a second application using a washcoat with a relative washcoat loading of B is made onto the matrix having the washcoat loading of A. The resulting matrix with the two washcoats is then be dried and calcined. Then the second washcoat is applied is applied onto the matrix coated with two washcoats with different relative amounts of the washcoat loadings, A and B. The resulting matrix can then be dried and calcined.

In the second type of coating, a single application of the first washcoat is applied onto the matrix, which is then dried and calcined. Then two of the second washcoats with different relative amounts of the washcoat loadings, A and B, are applied onto the matrix using second and third applications. The second application has a relative washcoat loading of A. After the second application been made, the washcoated matrix is dried and calcined, and then a third application using a washcoat with a relative washcoat loading of B is made onto the matrix having the first washcoat and a second washcoat having a loading of A. The resulting matrix is then be dried and calcined.

In the third type of coating, a single application of the first washcoat is applied onto the matrix, which is then dried and calcined. Then a single application of the second washcoat is applied onto the first coating on the matrix, which is then dried and calcined. Then a single application of the third washcoat is made onto the second coating on the matrix. The resulting matrix is then be dried and calcined.

Figure 2 is a flowchart providing an overall description of the various processes. The left columns relate to the first application, the central columns relate to a second application and the right columns relate to a third application.

Detailed description of these methods is provided below.

In each of the processes described below, the matrix in a mantle that is provided in step (a) has the following elements: the mantle has an axial length, a first end, a second end, an interior, a first overhang and a second overhang, the matrix has an axial length, a first end and a second end, wherein the matrix comprises a metal foil flow-through monolith comprising metal foil having a structure comprising a plurality of channels which extend longitudinally along the length of the flow-through monolith, the channels have a first end and a second end, and the first end and the second end are open and the channels are formed by corrugation of the metal foil, the matrix is connected to the interior of the mantle and the axial length of the mantle is greater that the axial length of the matrix, the mantle comprises a first overhang and a second overhang, wherein the first overhang and the second overhang are each portions of the mantel along the axial length of the mantle, the first overhang is between first end of the mantle and the first end of the matrix and the second overhang is between second end of the mantle and the second end of the matrix, and the difference between the length of the mantle and the length of the matrix is equal to the sum of the height of the first overhang and the height of the second overhang.

A 1 pass, 1 dose method is shown schematically in Figure 3. In this method: 3 0 (a) provided is (i) a matrix in a mantle and (ii) a first washcoat slurry, where the matrix in the mantel is a described herein above; (b) the mantle is oriented substantially vertically where the first end (the inlet side) of the mantle is the upper end of the mantel. A first washcoat is formed on the matrix by applying a predetermined amount of a first washcoat slurry onto the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c) the washcoat layer is removed from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

(d) The mantle can be flipped and orienting substantially vertically where the second end of the mantle (outlet end) is the upper end of the mantle. The washcoat layer can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix.

The washcoated matrix can then be dried, preferably with the removal of at least 85% of the moisture.

The dried washcoated matrix can then be calcined, preferably with the second end of the mantel being above the first end of the mantle.

A 2 dose -1 pass method is shown schematically in Figure 4. The method can comprise applying a first dose of a first washcoat to a portion, but not the entire length of the matrix followed by drying and then flipping the mantle and apply a second dose of a first washcoat or a dose of a second washcoat to the portion of the matrix that did not receive the first dose.

This method comprises: (a) providing: (i) a matrix in a mantle and (ii) a first washcoat slurry, where the matrix in the mantel is a described herein above; (b 1) orienting the mantle substantially vertically where the first end (the inlet side) of the mantle is the upper end of the mantle. A first washcoat is formed on the matrix by applying a predetermined amount of all or a portion of a first washcoat slurry onto a portion of, but not the entire length of the matrix, through the open ends of the channels at the first end of the matrix. The washcoat slurry can be pulled through the portion of the length of the matrix using a vacuum. During the process the first washcoat forms one or both of (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on the first overhang, (c1) removing the washcoat layer from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing followed by drying. In a 2 dose 1 pass method, the uncoated portion is preferably dosed only after the coated portion is dried, which is before the half-coated substrate is flipped.

(d) The mantle can be flipped and orienting substantially vertically where the second end of the mantle (outlet end) is the upper end of the mantle.

(b2) An additional portion of the first washcoat, or a second washcoat, is applied to the portion of the matrix that did not receive a washcoat.

(c2) The washcoat layer can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the second overhang and blockage from one or more channels by air knifing. In a 2 dose 1 pass method, the uncoated portion is preferably dosed only after the coated portion is dried, which is before the half-coated substrate is flipped.

A 2 dose -2 pass method is shown schematically in Figure 5. The method can comprise either: (1) applying a first dose of a first washcoat followed by a second dose of a first washcoat; or (2) applying a dose of a first washcoat followed by a dose of a second washcoat.

The method comprises: (a) providing: (i) a matrix in a mantle and (ii) a first washcoat slurry, where the matrix in the mantel is as hereinbefore described; (61) orienting the mantle substantially vertically where the first end (the inlet side) of the mantle is the upper end of the mantle. A first washcoat is formed on the matrix by applying a predetermined amount of all or a portion of a first washcoat slurry onto the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of: ( I) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the I 0 first overhang and the second overhang, (c I) removing the washcoat layer from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

(b2) The mantle comprising the calcined washcoated matrix can be orienting substantially vertically where the second end (the outlet side) of the mantle is the upper end of the mantel. An additional washcoat is formed on the matrix by applying a predetermined amount of: a second washcoat slurry, when the entire first washcoat was present on the calcined matrix; or a second portion of the first washcoat slurry, where the application of the washcoat slurry is applied onto the matrix through the open ends of the channels at the second end of the matrix.

The washcoat slurry is pulled through the matrix using a vacuum. During the process the additional washcoat forms one or both of (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c2) The additional washcoat slurry formed after the second application can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix while the tube is in a vertical position and the second end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the second overhang and blockage from one or more channels by air knifing.

(d) The mantle can be flipped and orienting substantially vertically where the first end of the mantle (inlet end) is the upper end of the mantle. The additional washcoat layer can be removed from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix.

The dried washcoated matrix can then be calcined, preferably with the first end of the mantel being above the second end of the mantle.

3 dose -2 pass methods are shown in Figures 6A and 6B. The method can provide a full dose over the entire length of a matrix and two doses each applied over a portion, but not the entire length of the matrix.

One method comprises: (a) providing: (i) a matrix in a mantle and (ii) a first washcoat slurry, where the matrix in the mantel is a described herein above; (b I) orienting the mantle substantially vertically where the first end (the inlet side) of the mantle is the upper end of the mantel. A first washcoat is formed on the matrix by applying a predetermined amount of-a first washcoat slurry onto a portion (X), but not the entire length of the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c1) removing the washcoat layer from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing followed by drying.

(b2) The mantle can then be orienting substantially vertically where the second end (the outlet side) of the mantle is the upper end of the mantel. A second washcoat is formed on the matrix by applying a predetermined amount of a second washcoat slurry onto a portion (100-X), but not the entire length of the matrix through the open ends of the channels at the second end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of: ( I) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c2) The additional washcoat slurry formed after the second application can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix while the tube is in a vertical position and the second end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the second overhang and blockage from one or more channels by air knifing.

(b3) The mantle comprising the calcined washcoated matrix having two washcoat applications can be orienting substantially vertically where the first end (the intlet side) of the mantle is the upper end of the mantel. A third washcoat is formed on the matrix by applying a predetermined amount of the third washcoat the entire portion of matrix, where the application of the washcoat slurry is applied onto the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the further washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c3) The third washcoat slurry formed after the third application can be removed from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

The mantle can be flipped and orienting substantially vertically where the second end of the mantle (outlet end) is the upper end of the mantel. The further washcoat layer can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix.

A second method comprises: (a) providing: (i) a matrix in a mantle and (ii) a first washcoat slurry, where the matrix in the mantel is a described herein above; (b t) orienting the mantle substantially vertically where the first end (the inlet side) of the mantle is the upper end of the mantel. A first washcoat is formed on the matrix by applying a predetermined amount of-a first washcoat slurry onto the entire length of the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c1) removing the washcoat layer from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

The mantle can be flipped and orienting substantially vertically where the second end of the mantle (outlet end) is the upper end of the mantel. The washcoat layer can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix.

(b2) The mantle can then be orienting substantially vertically where the second end (the outlet side) of the mantle is the upper end of the mantel. A second washcoat is formed on the matrix by applying a predetermined amount of a second washcoat slurry onto a portion (X), but not the entire length of the matrix through the open ends of the channels at the second end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of: ( I) blockage of one or more channels of the matrix, and I 5 (2) a washcoat layer on second overhang, (c2) The additional washcoat slurry formed after the second application can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix while the tube is in a vertical position and the second end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the second overhang and blockage from one or more channels by air knifing.

(b3) The mantle comprising the calcined washcoated matrix having two washcoat applications can be orienting substantially vertically where the first end (the intlet side) of the mantle is the upper end of the mantel. A third washcoat is formed on the matrix by applying a predetermined amount of the third washcoat to a portion (100-X) of the matrix, where the application of the washcoat slurry is applied onto the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the further washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (c3) The third washcoat slurry formed after the third application can be removed from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

A 3 dose -3 pass method is shown schematically in Figure 7. The method can comprise: (1) applying a dose of a first washcoat followed by two applications of a second washcoat; (2) applying two doses of a first washcoat followed by a dose of a second washcoat or (3) applying a dose of a first washcoat followed by an application of a second washcoat and then an application of a third dose.

The method comprises: (a) providing: (i) a matrix in a mantle and (ii) a first washcoat slurry, where (b 1) orienting the mantle substantially vertically where the first end (the inlet side) of the mantle is the upper end of the mantel. A first washcoat is formed on the matrix by applying a predetermined amount of all or a portion of a first washcoat slurry onto the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the first washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (dl) removing the washcoat layer from the first overhang and blockage from one or 30 more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

(b2) The mantle comprising the calcined washcoated matrix can be orienting substantially vertically where the second end (the outlet side) of the mantle is the upper end of the mantel. An additional washcoat is formed on the matrix by applying a predetermined amount of: a portion of a second washcoat slurry, when the entire first washcoat was present on the calcined matrix; or a second portion of the first washcoat slurry, where the application of the washcoat slurry is applied onto the matrix through the open ends of the channels at the second end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the additional washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (d2) The additional washcoat slurry formed after the second application can be removed from the second overhang and blockage from one or more channels by air knifing the washcoat layer from the second overhang and blockage from the second end of the matrix while the tube is in a vertical position and the second end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the second overhang and blockage from one or more channels by air knifing.

The mantle can be flipped and orienting substantially vertically where the first end of the mantle (inlet end) is the upper end of the mantel. The additional washcoat layer can be removed from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix.

(b3) The mantle comprising the calcined washcoated matrix having two washcoat applications can be orienting substantially vertically where the first end (the intlet side) of the mantle is the upper end of the mantel. An further washcoat is formed on the matrix by applying a predetermined amount of: (i) a second portion of a second washcoat slurry, when a first portion of the second washcoat is present on the calcined matrix; (ii) the entire portion of the second washcoat slurry, or (iii) the third washcoat slurry, where the application of the washcoat slurry is applied onto the matrix through the open ends of the channels at the first end of the matrix. The washcoat slurry is pulled through the matrix using a vacuum. During the process the further washcoat forms one or both of: (I) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, (d3) The further washcoat slurry formed after the further application can be removed from the first overhang and blockage from one or more channels by air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the tube is in a vertical position and the first end is the upper end. A secondary vacuum can be used to facilitate removal of washcoat that had been removed from the first overhang and blockage from one or more channels by air knifing.

Apparatus The invention also relates to an apparatus for coating a matrix in a mantle with one or more washcoat slurries using one or more washcoat applications and one or more passes. The apparatus comprises a plurality devices for coating a matrix in a mantle with a washcoat slurry comprising a catalyst.

The apparatus can comprise: (a) a mantel orientation device; (b) a washcoat slurry doser; (c) a vacuum and a supplemental vacuum; (d) at least two, preferably three air knives; (e) a mantle flipper device; (f) a drier; (g) a calcination oven and (i) a controller.

These devices can be arranged in stations wherein a station can comprise one or more devices and a matrix in a mantle is transferred between stations.

The mantel orientation station comprises a mantel orientation device, preferably a robotic device, that holds and orients a matrix in a mantel in a vertical position. The term vertical means that the upper face of the matrix is within 5°, preferably within 4°, more preferably within 3° of vertical, most preferably within 0° of vertical.

While the mantle can be manually inserted into the holding means, it is preferred to use a robotic "pick-and-place" device in order to increase the automation of the method as a whole. The mantel orientation device, after orienting the matric in a mantel in a vertical position can either position the mantel in a washcoat slurry doser or transfer the mantel to a different device that positions the mantel in a washcoat slurry doser. The washcoat slurry doser comprises a device, such as a showerhead, that applies the washcoat onto an end of the mantel.

The washcoat slurry doser comprises a connection to a device that provides a vacuum an pulls the washcoat from an end of the matrix towards the other end of the matrix. The washcoat doser preferably comprises a cone shaped region below the lower end of the mantle when the mantel is in a vertical position in the doser. A restriction plate can be located in the cone below the catalyst where the air flow from the vacuum is increased at the periphery more blockage of the channels can occur relative to the center of the matrix. The washcoat slurry doser preferably comprises a connection to a supplemental vacuum. Preferably the connection is in fluid communication with a portion of the cone shaped region. The washcoat slurry doser is preferably part of a dosing station further comprising an air knife, where the air knife is positioned to remove washcoat from an overhang and an end of the matrix A mantle flipper device can be located on the dosing station or on another station, such as a drier washcoat removal station, which comprises a drier and preferably comprises an air knife before, or preferable at an entrance to the drier. The drier is in mechanical communication with a calcining oven. One or more, preferably all of these devices are in communication with a controller that directs the operations of one or more of the above devices.

The apparatus can comprise: (a) a mantel orientation station comprising a mantel holder wherein the mantle holder holds the mantle substantially vertically where the first end of the mantle is the upper end of the mantel, and holds the mantle during application of a washcoat slurry to the matrix, (b) a washcoat slurry dosing station comprising: (I) a washcoat applicator that delivers a predetermined amount of a washcoat slurry to the open ends of the channels at the first or second end of the matrix, and (2) a vacuum, (c) a doser washcoat removal station comprising an air knife and a secondary vacuum, air knife configured to blow a stream of a gas against a washcoat layer on a first overhang on the mantle and across a first end of a matrix, (d) a mantle flipper station, comprising a flipper (e) a drier washcoat removal station comprising an air knife (f) a secondary vacuum station comprising a vacuum orientation device (g) a drier station comprising an oven and a mantle mover, wherein the mantle mover transports a plurality of mantles through the plurality of heating zones, (h) a calcination oven station having a plurality of heat zones and a mantle mover, wherein the mantle mover transports plurality of mantles through the plurality of heating zones, (i) a controller linked to more or more of stations, wherein the controller monitors and/or controls one or more of the stations.

The apparatus can be configured in a radial or linear configuration, or a combination thereof, depending upon the specific equipment in each of the stations. (Figure 8) The entire content of each patent document referenced in this specification is incorporated herein by reference in its entirety.

Claims

Claims The invention claimed is: 1. A method of coating a matrix in a mantle with a washcoat slurry comprising a catalyst, the method comprising: (a) providing (i) a matrix in a mantle and (ii) a first washcoat slurry, the mantle having an axial length, a first end, a second end, an interior, a first overhang and a second overhang, the matrix having an axial length, a first end and a second end, the matrix comprising a metal foil flow-through monolith comprising metal foil having a structure comprising a plurality of channels which extend longitudinally along the length of the flow-through monolith and the channels have a first end and a second end and the first end and the second end are open and the channels are formed by corrugation of the metal foil, wherein the matrix is connected to the interior of the mantle and the axial length of the mantle is greater that the axial length of the matrix, wherein the mantle comprises a first overhang and a second overhang, wherein the first overhang and the second overhang are each portions of the mantel along the axial length of the mantle, the first overhang is between first end of the mantle and the first end of the matrix and the second overhang is between second end of the mantle and the second end of the matrix, and wherein the difference between the length of the mantle and the length of the matrix is equal to the sum of the height of the first overhang and the height of the second overhang.(b) forming a first washcoat on the matrix, wherein forming the washcoat on the matrix comprises: (i) orienting the mantle substantially vertically where the first end of the mantle is the upper end of the mantel, and forming a first washcoat on the matrix, (ii) applying a predetermined amount of a first portion of a first washcoat slurry onto the matrix through the open ends of the channels at the first end of the matrix and (iii) pulling the washcoat slurry through the matrix using a vacuum, wherein forming the first washcoat forms one or both of: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang, removing at least one of a washcoat layer from the first overhang and blockage from one or more channels at the first end of the matrix, wherein removing at least one of the washcoat layer and blockage comprises air knifing the washcoat layer from the first overhang and blockage from the first end of the matrix while the mantel is in a vertical position and the first end is the upper end, (d) removing at least one of a washcoat layer from the second overhang and blockage from one or more channels from the second end of the matrix, wherein removing at least one of the washcoat layer and blockage comprises moving the mantle into a vertical position where the second end of the mantel is the upper end and air-knifing the washcoat layer from the second overhang and blockage from the second end of the matrix while the mantel is in a vertical position and the second end is the upper end.
2. The method of claim I, the method further comprising drying the washcoat on the matrix and overhang and then calcining the washcoat on the matrix and overhang, wherein drying the washcoat on the matrix and overhang comprises air-knifing an end of the matrix and then heating the matrix.
3. The method of claim 2, further comprising forming a second washcoat on the first washcoat, wherein the second washcoat is formed by: (b2a) applying a predetermined amount of a second portion of a first washcoat slurry onto the matrix through the open ends of the channels at the second end of the matrix, or (b2b) applying a predetermined amount of a second washcoat slurry onto the first washcoat through open ends of the channels at the first end or the second end of the matrix, wherein steps (b2a) and (b2b) further comprise pulling the washcoat slurry through the matrix using a vacuum, and wherein steps (b2a) or (b2b) form: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang.5. The method of claim 4, further comprises performing steps (c) and (d) after step (b2a) or (b2b), then drying the washcoat on the matrix and overhang and calcining the washcoat on the matrix and overhang, wherein drying the washcoat on the matrix comprises air-knifing an end of the matrix and then heating the matrix.6. The method of claim 6, further comprising forming a third washcoat on the second washcoat, wherein the third washcoat is formed by: (b3a) applying a predetermined amount of a second portion of a second washcoat slurry onto the matrix through the open ends of the channels at the second end of the matrix, or (b3b) applying a predetermined amount of a third washcoat slurry onto the second washcoat through open ends of the channels at the first end or the second end of the matrix, wherein steps (b3a) and (b3b) further comprise pulling the washcoat slurry through the matrix using a vacuum, and wherein steps (b3a) or (b3b) form: (1) blockage of one or more channels of the matrix, and (2) a washcoat layer on one or both of the first overhang and the second overhang.8. The method of claim 7, further comprises performing steps (c) and (d) after step (b2a) or (b2b), then drying the washcoat on the matrix and overhang and calcining the washcoat on the matrix and overhang, wherein drying the washcoat on the matrix comprises air-knifing an end of the matrix and then heating the matrix.9. The method of any one of the previous claims, wherein step (c) further comprises providing a secondary vacuum through the matrix at the low end of the mantle after air knifing the first end.11. The method of claim 9, wherein applying the secondary vacuum provides increased air flow around the periphery of the matrix relative to the center of the matrix.12. The method of claim 11, wherein applying the vacuum provide an increased gas flow around the periphery of the matrix relative to the center of the matrix.13. The method of any one of the previous claims, the method further comprising providing a vacuum through the matrix at the low end of the mantle after air knifing the second end of the matrix.14. The method of any one of the previous claims, wherein the matrix comprises channels at a density of 100 to 900 channels per square inch (cpsi).15. The method of any one of the previous claims, wherein the matrix comprises a corrugated structure.16. The method of claim 13, wherein the corrugated structure comprises (a) longitudinal structure design; (b) a transversal structure design; (c) a perforated design; (d) a combined perforated and longitudinal structure design, or (e) Micro Holes, preferably a perforated design.17. The method of any one of the previous claims, wherein at least one the first washcoat slurry, the second washcoat slurry and the third washcoat slurry comprises one or more of a three-way catalyst, a NO trap, a catalysed soot oxidation catalyst comprising a supported platinum group metal or a Nth-SCR catalyst.18. The method of any one of the previous claims, wherein at least two the first washcoat slurry, the second washcoat slurry and the third washcoat slurry comprises one or more of a three-way catalyst, a NO trap, a catalysed soot oxidation catalyst comprising supported platinum group metal or a NH3-SCR catalyst.19. The method of any one of the previous claims, wherein each of the first washcoat slurry, the second washcoat slurry and the third washcoat slurry comprises one or more of a three-way catalyst, a NO trap, a catalysed soot oxidation catalyst comprising supported platinum group metal or a NI-13-SCR catalyst.20. The method of any one of the previous claims, where the first washcoat slurry and the second washcoat slurry differ by one or more of the concentration of catalyst in the washcoat and composition of the catalyst.21. The method of any one of the previous claims, where the first washcoat slurry comprises Pd and the second washcoat slurry comprises Rh.22. The method of any one of the previous claims, wherein in step (b), (b3a) or (b3b), when the first portion of the first washcoat slurry is applied to the matrix, the mantle is in a vertical orientation where the first end is the upper end and the second end is the lower end.23. The method of any one of the previous claims, wherein in step (b2a) or (b2b), when the second portion of the first washcoat slurry is applied to the matrix, the matrix is in a vertical orientation wherein the second end of the matrix is the upper end and the first end of the matrix is the lower end.24. The method of any one of the previous claims, wherein step (d) further comprises applying a vacuum to the open ends of the channels at the lower end of the matrix after air knifing to remove material from the periphery of the matrix after air knifing.25. The method of any one of the previous claims, wherein the vacuum is greater at the periphery of the matrix than the central portion of the matrix.26, An apparatus for dosing one or more washcoats on a metal foil flow-through substrates comprises: (a) a mantel orientation station comprising a mantel holder wherein the mantle holder holds the mantle substantially vertically where the first end of the mantle is the upper end of the mantel, and holds the mantle during application of a washcoat slurry to the matrix, (b) a washcoat slurry dosing station comprising: (I) a washcoat applicator that delivers a predetermined amount of a washcoat slurry to the open ends of the channels at the first end of the matrix, and (2) a vacuum, (c) a doser washcoat removal station comprising an air knife and a secondary vacuum, air knife configured to blow a stream of a gas against a washcoat layer on a first overhang on the mantle and across a first end of a matrix, (d) a mantle flipper station, comprising a flipper (e) a drier washcoat removal station comprising an air knife (f) a secondary vacuum station comprising a vacuum orientation device (g) a drier station comprising an oven and a mantle mover, wherein the mantle mover transports a plurality of mantles through the plurality of heating zones, (h) a calcination oven station having a plurality of heat zones and a mantle mover, wherein the mantle mover transports plurality of mantles through the plurality of heating zones, and (i) a controller linked to more or more of stations, wherein the controller monitors and/or controls one or more of the stations.27. The apparatus of claim 26, further comprising at least one of a laser marking station and an arrow marking detection station.