Patent Description:
Over the past years, there has been an increased interest in the development of environmentally friendly processes related to the purification of exhaust and flue gas emissions. Various catalyzer devices have been presented over the years, all with the same goal of achieving effective cleaning of pollutants which are hazardous to both human health as well as the environment.

<CIT> describes a catalyser and a method for producing the same, wherein a layer of porous ceramic layer is formed on a mesh substrate by thermal spraying followed by surface area enlargement of the ceramic layer and subsequent impregnation of the surface area enlarged ceramic layer with a catalytically active material. The purification result as well as the method of producing this known catalyzer is sufficient in many applications, but there is room for improvements in the methods of producing catalytically active products as well as for the catalytically active products per se.

One problem of methods for producing catalytically active products according to the prior art is that they are complicated and require expensive equipment.

Another problem of such prior art methods is that they consume considerable amounts of energy.

<CIT> discloses a method for applying a coating of catalytic material onto a metal substrate involving thermal spray deposition of refractory oxide particles directly onto the substrate after which the catalytic material may be applied to the undercoated substrate.

An object of the present invention is to overcome or at least alleviate one or more of the problems described above in relation to prior art and provide an efficient method of producing a catalytically active product and also provide such a product which allows for facilitated production.

The present invention is related to a method of producing a catalytically active product, comprising the steps of:.

The method according to the invention results in an easy and efficient production of the catalytically active product. The present invention makes it possible to produce the catalytically active product without any thermal spraying process. The combination of the first material and the particles result in a safe, reliable and efficient securing of the ceramic layer to the substrate for the production of the catalytically active product.

The method can comprise the step of providing the first material and/or the particles of the second material as one or more suspensions, optionally both are provided in combination as a suspension. Hence, the first material and/or the second material can be deposited on the substrate in an efficient manner, such as by spraying or other coating process, wherein the suspension can be deposited at any suitable temperature, such as at room temperature. Hence, the first material can initially be deposited on the substrate without melting. Then, the method can include the step of heating the substrate with the first material and the particles of the second material thereon in a furnace, such as a vacuum furnace or with reducing or inert gas, for melting the first material only and adhere the first material to the substrate while securing the particles to the first material. Hence, the first material and the particles efficiently form an attachment layer for subsequent fastening of the ceramic layer, which can be produced in an efficient and reliable manner.

After securing the first material to the substrate by melting it, the method can comprise the step of depositing the ceramic layer by providing a ceramic material as a suspension and depositing the suspension onto the first material with the particles, e.g. by spraying. Hence, the ceramic material is formed in an easy manner and partially enclose the particles projecting from the first material to reliably secure the ceramic layer mechanically to the substrate, e.g. by drying and calcination.

The present invention is also related to a catalytically active product, comprising a substrate, a first material, particles of a second material having a higher melting point than the first material, a ceramic layer comprising a ceramic material adhered to the substrate through the first material and particles of a second material being partially embedded in the first material and projecting into the ceramic layer, wherein the ceramic layer is formed with a pore structure provided with a catalytically active material.

The substrate can comprise a metal, such as steel, aluminum, copper or other suitable metal. The substrate can be formed as a sheet or a mesh, such as a wire mesh or a perforated plate or similar, and can optionally be shaped into any suitable shape, including a cylinder shape. The first material can comprise a metal, such as a low melting metal or alloy. The first material can have a lower melting point than the substrate as well as the particles of the second material. The particles of the second material can comprise metal powder, ceramic powder or composites or mixtures thereof. The particles of the second material can have a particle size of <NUM>-<NUM> to provide efficient fastening to the first material and to the ceramic layer. By providing coarse high-melting particles in the layer of the low-melting first material, a larger surface area is created, leading to better adhesion of the ceramic layer to the substrate surface. Hence, the particles provide means for enhanced adhesion of the ceramic layer to the substrate.

Further characteristics and advantages of the present invention will become apparent from the description of the embodiments below, the appended drawings and the dependent claims.

By way of example, embodiments of the present invention will now be described with reference to the accompanying drawings, in which:.

With respect to <FIG>, a catalytically active product <NUM> is illustrated schematically according to the present invention. The catalytically active product <NUM> is configured to be used for promoting a chemical reaction. For example, the catalytically active product <NUM> is arranged for combustion, purification, catalytic reforming or similar. For example, the catalytically active product <NUM> is arranged for purification of flue gases with respect to carbon monoxide and/or hydrocarbons, such as VOC and PAH. For example, the catalytically active product <NUM> is arranged in a reactor vessel for a chemical reaction. Alternatively, the catalytically active product <NUM> is arranged in a burner for combustion of gaseous fuels, such as natural gas, propane, butylene or similar gases, e.g. for heating purposes.

The catalytically active product <NUM> comprises a substrate <NUM>, a first material <NUM>, particles <NUM> of a second material, a ceramic layer <NUM> comprising a ceramic material with pores <NUM>, and a catalytically active material <NUM>. The first material <NUM> and the particles <NUM> form an attachment layer on the substrate <NUM>. For example, the first material <NUM> is arranged directly on top of the substrate <NUM>, wherein the particles <NUM> are partially embedded in the first material <NUM> and projects from the surface thereof. The ceramic layer <NUM> is arranged on top of the attachment layer formed by the first material <NUM> and the particles <NUM>, wherein the ceramic layer <NUM> engages the particles <NUM>. Hence, the attachment layer formed by the first material <NUM> and the particles <NUM> is arranged between the substrate <NUM> and the ceramic layer <NUM>.

In the illustrated embodiment, the substrate <NUM> has a substantially flat shape. However, the substrate <NUM> may be flat, cylindrical, curved, bent, or have basically any geometrical shape. For example, the substrate <NUM> is formed as a mesh structure, i.e. having a plurality of through holes. According to one embodiment, the substrate <NUM> is formed as a wire mesh. Alternatively, the substrate <NUM> is formed as a continuous sheet, a grid structure or similar. For example, the substrate <NUM> is or comprises a metal or an alloy. According to one embodiment, the substrate is made of steel, such as stainless steel, aluminum or copper. Alternatively, the substrate <NUM> is made of a polymer material, such as polytetrafluoroethylene or similar polymer or composite materials that can withstand relatively high temperatures. In general, the substrate <NUM> should be able to withstand temperatures of at least <NUM>. In some cases, it should be able to withstand temperatures well above this level, such as at least <NUM>, at least <NUM> or at least <NUM>.

On top of the substrate <NUM>, which forms a base structure, the the first material <NUM> is arranged. The substrate <NUM>, or at least a portion or a side thereof, is coated with the first material <NUM>. In the illustrated embodiment, a top surface of the substrate <NUM> is coated with the first material <NUM>. Alternatively, the entire substrate <NUM> is coated with the first material <NUM>. For example, the first material <NUM> is a metal or an alloy. For example, the first material <NUM> is Al or similar metal having a relatively low melting point. Alternatively, the first material <NUM> is an alloy comprising a metal, such as Ni, Cu, Fe and/or steel, and a melting point depressant.

The particles <NUM> are partially embedded in the first material <NUM> and project at least partially from it in a direction away from the substrate <NUM>. The particles <NUM> are made of or comprises a second material having a higher melting point than the first material <NUM>. For example, the solidus temperature of the particles <NUM> of the second material is higher than the liquidus temperature of the first material <NUM>. For example, the particles <NUM> of the second material comprise metal powder, ceramic powder or mixtures thereof. The particles <NUM> may have different shapes and sizes. The particles <NUM> are provided in or on the first material <NUM> to add surface roughness which helps in the adhesion of the ceramic layer <NUM>. For example, the particles <NUM> have a particle size of at least <NUM>, or at least <NUM>, such as <NUM>-<NUM>. For example, the second material has a porosity of at least <NUM>%.

The ceramic layer <NUM> is provided on the attachment layer formed by the first material <NUM> and the particles <NUM> and is secured to it by means of the particles <NUM>. Hence, particles <NUM> are partially embedded in the first material <NUM> and partially embedded in the ceramic layer <NUM> to mechanically fasten the ceramic layer <NUM> to the substrate <NUM>. Hence, the ceramic layer <NUM> is arranged on top of the first material <NUM> and the particles <NUM> projecting from it. The ceramic layer <NUM> may comprise alumina, zirconia, titanium dioxide, silica, tungsten carbides, silicon nitrides or similar ceramics, or mixtures thereof. The ceramic layer <NUM> is formed with pores <NUM> providing an enlarged surface area for depositing the catalytically active material <NUM> therein. Hence, the ceramic layer <NUM> is provided with the catalytically active material <NUM>, wherein catalytically active material <NUM> is arranged inside the pores <NUM> thereof. For example, the catalytically active material <NUM> is a noble metal, a transition metal or a mixture or an oxide thereof. For example, the catalytically active material <NUM> is palladium.

With reference also to <FIG> a method of producing the catalytically active product <NUM> is illustrated schematically according to a first embodiment by means of a series of illustrations. The substrate <NUM> has been described above and is illustrated schematically in <FIG>. The substrate <NUM> is coated with the first material <NUM>, e.g. through a spraying process. The substrate <NUM> with the first material <NUM> is illustrated in <FIG>, wherein the first material <NUM> is provided as a layer on the substrate <NUM>. According to one embodiment, the first material <NUM> is provided as a suspension, wherein the first material <NUM> is provided as particles dispersed in a liquid, such as water. For example, the substrate <NUM> is coated with the first material <NUM> through a spraying process, wherein the first material <NUM> is sprayed onto the substrate <NUM>, e.g. in room temperature. Hence, the first material <NUM> is not heated and is not sprayed at elevated temperatures. Alternatively, the first material <NUM> is applied on the substrate <NUM> by another coating process, such as painting, dipping or similar. Alternatively, the first material <NUM> is provided as a paste, which is applied onto the substrate <NUM> by spreading over the surface of the substrate <NUM>. After applying the first material onto the substrate, the substrate <NUM> with the first material <NUM> is optionally dried, e.g. by heat treatment in an oven.

After coating of the substrate <NUM> with the first material <NUM>, the particles <NUM> comprising the second material is provided on the first material <NUM>, which is illustrated in <FIG>. For example, the particles <NUM> are provided as a suspension, also called slurry, wherein the particles <NUM> are suspended in liquid, such as water. The suspension of the particles <NUM> is applied on the first material <NUM> carried by the substrate <NUM>. For example, the particles <NUM> are applied onto the first material <NUM> through a spraying process, wherein the suspension with the particles <NUM> is sprayed on the first material <NUM>. Hence, the particles <NUM> may be sprayed onto the first material <NUM> at room temperature. After applying the particles <NUM> onto the first material <NUM>, the substrate <NUM> carrying the first material <NUM> and the particles <NUM> may be dried, e.g. in an oven. The substrate <NUM> with the first material <NUM> and the particles <NUM> is then heat treated, e.g. in a furnace, to a temperature, wherein the first material <NUM> is melted and the particles <NUM> of the second material are not melted. Neither is the substrate <NUM> melted. Hence, the first material <NUM> is secured to the substrate <NUM> by melting while securing the particles <NUM> to the first material <NUM>. The particles <NUM> are secured to the first material <NUM> mechanically, wherein the particles <NUM> are partly embedded in the first material <NUM> after melting of the first material <NUM>. The first material <NUM> is also adhered to the substrate mechanically by melting into a roughness of its surface. Particles <NUM> partly embedded in the first material <NUM> and projecting from it are illustrated in <FIG>. For example, the heat treatment for melting the first material <NUM> is performed in a vacuum furnace under vacuum. Alternatively, the heat treatment for melting the first material <NUM> is performed in a furnace with reducing gas or an inert gas.

The substrate <NUM> carrying the first material <NUM> and the particles <NUM> is then provided with the ceramic layer <NUM>, which is illustrated in <FIG>, wherein the ceramic layer <NUM> is provided onto the particles <NUM> and the first material <NUM>, so that the first material <NUM> is arranged between the ceramic layer <NUM> and the substrate <NUM>. For example, the ceramic layer <NUM> is deposited onto the attachment layer <NUM> as a slurry, such as in the form of a water based suspension. The ceramic layer <NUM> may also contain a pore-forming agent which is provided to form a porous structure in the ceramic material. Typically, the thickness of the ceramic layer is in the range of <NUM>-<NUM>, preferably in the range of <NUM>-<NUM>. The ceramic layer <NUM> is surface enlarged by the pores <NUM>, which are configured to hold the catalytically active material <NUM>, which is illustrated in <FIG>.

The ceramic layer <NUM> may be produced according the following process, <NUM>) direct spraying together with secondary surface area enlargement through precipitation, or <NUM>) spraying with simultaneous depositing of ceramic powder, or a combination of methods <NUM>) and <NUM>), followed by coating with a catalytically active material <NUM> through an impregnation process. Alternatively, the pore-forming agent may be a combustible material which may be combusted by heat treatment. Optionally, the pore-forming agent may be a pore-forming polymer material. Alternatively, the ceramic layer <NUM> is a ceramic powder containing particles with a high specific surface. For example, the pores <NUM> are formed in the ceramic layer <NUM> in a conventional manner.

The pores <NUM> of the ceramic layer <NUM> are configured to carry the catalytically active material <NUM>. For instance, the pores <NUM> may be cylindrically shaped. This way, chemicals to be purified can easily reach the catalytically active material <NUM> of the catalytically active product <NUM>. The catalytically active material <NUM> may be deposited in the pores <NUM> of the ceramic layer for instance through a conventional impregnation process. During impregnation, the structure of pores <NUM> of the ceramic layer <NUM> is, e.g. saturated with a solution containing the catalytically active material <NUM>. The catalytically active material <NUM> may include noble metals, transition metals or combinations of these.

With reference to <FIG> an alternative embodiment of the present invention is described, wherein the substrate <NUM> is coated with a mix of the first material and the particles <NUM> of the second material. The substrate <NUM> with the mix of the first material <NUM> and the particles <NUM> is illustrated in <FIG>. For example, also the first material <NUM> is provided as particles, wherein the first material <NUM> and the particles <NUM> of the second material are provided as a mix in a slurry. The slurry comprising both the first material <NUM> and the particles <NUM> of the second material is applied on the substrate <NUM>, e.g. by spraying, as described above. Hence, the slurry may be provided on the substrate by spraying in room temperature. Then, the substrate <NUM> with the slurry is optionally dried. After, coating the substrate <NUM> with the mixture of the first material <NUM> and the particles <NUM>, it is heated to melt the first material <NUM> but not the substrate <NUM> or the second material, wherein the particles <NUM> are adhered to the first material <NUM> and the first material <NUM> is adhered to the substrate <NUM>, as illustrated in <FIG>. Hence, particles <NUM> are partially embedded in the first material <NUM> and project from it in a direction away from the substrate <NUM> to obtain a rough outer surface for securing the ceramic layer <NUM> as describe above. Then, the ceramic layer <NUM>, which may be provided as a slurry, is deposited onto the first material <NUM> and the particles <NUM> as illustrated in <FIG>. For example, the ceramic layer may be deposited by spraying as described above. Then, the ceramic layer <NUM> may be subjected to a surface area enlarging process to form the pores <NUM>, as illustrated in <FIG>. For example, the ceramic layer <NUM> contains a pore-forming agent. Finally, the catalytically active material <NUM> is deposited through for instance impregnation. The catalytically active material <NUM> may be deposited on the surface of the ceramic layer <NUM> and inside the pores <NUM> thereof.

Claim 1:
A method of producing a catalytically active product (<NUM>), comprising the steps of:
a) providing a substrate (<NUM>),
b) depositing a first material (<NUM>) and particles (<NUM>) of a second material on the substrate, wherein the particles (<NUM>) of the second material have a higher melting point than the first material (<NUM>),
c) heating the substrate (<NUM>) with the first material (<NUM>) and said particles (<NUM>) to a temperature where the first material (<NUM>) is melted and the particles (<NUM>) of the second material are not melted and thereby adhering the first material (<NUM>) and the particles (<NUM>) to the substrate (<NUM>), wherein particles (<NUM>) are partly embedded in the first material (<NUM>) and form a rough surface,
d) depositing a ceramic material on the rough surface formed by the particles (<NUM>) to form a ceramic layer (<NUM>) thereon, and
e) adding a catalytically active material (<NUM>) to the ceramic layer (<NUM>).