JPS6260141B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides improved retention capacity for metal oxides that have cross-flow effects and that promote catalytic reactions present in the immersed dispersion with an expanded geometric surface area. The present invention relates to an improved catalyst carrier matrix having the following properties.

It consists of layers of heat-resistant and scaling-resistant steel arranged one above the other, each layer having a cross-section projecting from the plane of the smooth sieve cloth at intervals parallel to the direction of the desired flow channel. consisting of a smooth sieve screen cloth with supporting wires woven or bonded to its surface; Layers of cloth alternate with layers of cloth, or layers of smooth or corrugated metal sheets alternate with layers of smooth sieve cloth with support wires suitably woven or bonded to the surface. Support matrices for catalysts have already been proposed.

By the way, if the support wire is constructed as a hollow support profile with a closed cross section or a support profile with an open cross section, it is possible to improve this carrier matrix in terms of weight reduction, increased stability, and pressure loss. It turned out that it was possible. Open support profiles and closed hollow support profiles additionally have the advantage that the geometric surface area of the carrier matrix is enlarged.

In other words, the improved catalyst support matrix according to the invention of the above type comprises layers of heat-resistant and scaling-resistant steel protruding from the plane of a smooth sieve cloth at intervals parallel to the direction of the desired flow grooves. consisting of a smooth sieve cloth, to which a hollow support profile with a closed cross section or a support profile with an open cross section is woven or woven into the surface; The layers alternate with layers of smooth sieve cloth with closed hollow support profiles or open support profiles suitably woven or woven into the surface, or with smooth or corrugated support profiles. Layers of sheet metal sheets alternate with layers of smooth sieve cloth with closed hollow support profiles or open support profiles suitably woven or bonded to the surface, in which case: The sieve cloth is
With a mesh opening of 0.18 to 0.025 mm and a wire thickness of 0.15 to 0.025 mm, and when the metal sheet, sieve cloth and closed hollow supporting profiles or open supporting profiles are iron, chrome, aluminum and It is further characterized in that it is made of an alloy of cerium or yttrium.

This closed hollow support profile can have any cross section, i.e. it can be a tube of round, square, oval, rectangular and flat shape, and this open hollow support profile , may likewise have the abovementioned cross section. This results in a wide gap for advantageous static stability.

A closed hollow support profile refers to a profile that has a closed outer wall but is open at the end faces. The open support profile has an open outer wall and, of course, also open end faces.

Embodiments of the improved matrix can be based on all embodiments according to the proposal.

Correspondingly, the sieve cloth strip with the new closed hollow support profile or the open support profile can be used, if appropriate together with other smooth or corrugated sieve cloth strips or sheet metal strips, in the form of a helical shape. It may be rolled up into a cylindrical body with a number of flow grooves, having a cross section of .

The screen cloth can advantageously be a strip having a mesh opening of 0.1 to 0.05 mm, in particular 0.073 mm, and a wire thickness of 0.1 to 0.05 mm, in particular 0.07 mm.

It has proven advantageous to determine the cross-sectional area of the closed hollow support profile or the open support profile to be less than 5 mm ² , although the respective cross-sectional area to be selected in this case depends on the desired flow groove. It is determined by the size and the thickness of the wire of the sieve cloth.

Furthermore, each flow channel formed by the woven, closed hollow or open support profile creating the spacing has a cross-sectional area of less than 5 mm ² and the support profile is formed of a strip of sieve cloth. It has been found advantageous that they are separated from each other by a minimum of 1 mm and a maximum of 5 mm in the plane of . A carrier matrix consisting of an alloy of 15% by weight chromium, 5% by weight aluminum and the balance iron has been found to be suitable for the catalytic purification of the exhaust gases of internal combustion engines. Also, chromium 15% by weight
Also advantageous are alloys consisting of 0.5 to 12% by weight of aluminum, 0.1 to 3% by weight of cerium or yttrium, and the balance iron. By heating in an oxygen-containing gas, such alloys can be provided with an aluminum oxide surface layer, which in many cases favorably influences the deposition of the catalytic material to be provided.

Other embodiments applicable to the above-mentioned structural form of the carrier matrix according to the invention are that the individual layers are welded to each other circumferentially and/or end-wise point-wise or in their entirety or that the final layer is welded to the preceding layer. This is why arc welding is particularly advantageous.

Furthermore, the present invention provides a method for preparing catalysts coated with conventional catalytic support materials and directly impregnable with a solution of active catalytic metal.
The present invention relates to a carrier matrix according to the above structure. In this case, the layer is coated on its surface with a carrier material, often a surface metal oxide, which promotes the catalytic reaction. In practical use, the carrier matrix according to the invention coated with this carrier material is preferably mounted as a wound cylinder with a helical cross-section in a steel jacket and/or welded into the jacket. It is located. Another method of fixing the respective layers is to place the cross support member or support web rigidly, for example in the inner diameter of the cylindrical steel jacket or casing or in the body of the converter, i.e. for example in two configurations. Welding with any of the members. This prevents the individual helically wound layers from shifting in the longitudinal direction of their axis.

The production of support matrices which can be directly impregnated with catalytic substances is carried out by applying a strip of sieve cloth with the surface of a smooth layer and a corrugated layer or with closed hollow or open support profiles before winding up into a cylinder. This is carried out by coating with a carrier material that promotes the catalytic reaction.

The provision of the support material which promotes this catalytic reaction is carried out by coating methods known per se. For this purpose, a heat-resistant support material with a relatively large specific surface area, which accelerates the catalytic reaction, is brought into contact with the surface to be coated with an aqueous dispersion of the support material or with a solution of a salt which can be converted into a support material by heat treatment. After drying, removal of excess dispersion or solution and subsequent drying, calcination is carried out, often at temperatures above 450° C., in which case this working step is carried out optionally several times. Initially, all heat-resistant support materials customary for catalysts can be used. Therefore, the surface to be coated with Mg, Ca, Sr, Ba, Al, Sc, Y,
Lanthanide elements, actinide elements, Ga, In,
Tl, Si, Ti, Zr, Hf, Th, Ge, Sn, Pb, V,
It can be contacted with an aqueous dispersion of at least one compound from the group of oxides of Nb, Ta, Cr, Mo, W and carbides, borides and silicides of transition metals. Preferably, such heat-resistant catalyst-support materials are used which synergistically promote the action of the actual catalytically active components. Examples of such substances include active Al ₂ O ₃ ,
Simple or complex oxides such as ZrO ₂ , Ce ₂ O ₃ , CeO ₂ , SiO ₂ or TiO ₂ or silicates such as barium silicate, borosilicate or aluminosilicate, or barium titanate or titanic acid It is a titanate like aluminum.

In practice, heat-resistant carrier materials are used, in particular, activated aluminum oxides of various phases (γ-, η
―, δ―, θ― or ζ―, χ― and κ―Al ₂ O ₃ )
is used. The aluminum oxide can be combined with or doped with certain elements that stabilize its crystal structure or increase the oxygen absorption capacity of the total catalyst. According to an advantageous embodiment of the method of the invention, the surface of the heat-treated structural reinforcement is therefore optionally coated with one or more elements from the periodic system, from the main groups and from the subgroups of the periodic system. contact with an aqueous dispersion of γ-series aluminum oxide or its hydroxide or oxide hydrate precursor containing a salt of However, any other compounds or compound precursors that act synergistically with the catalytically active components can also be provided on the reinforcing material by dispersion.

γ-series aluminum oxide with cerium and/or
Or doping with zirconium element is
For example, in automatic exhaust gas purification systems, this has an advantageous effect on sustained activity and, in addition, results in advantages in the case of simultaneous oxidation or reduction of pollutants of internal combustion engines in a single catalyst layer. To introduce this doping element into the aluminum oxide lattice, an aluminum hydroxide or aluminum oxide hydrate precursor containing the elements cerium and/or zirconium is added to the lattice containing cerium salts, zirconium salts and optionally also aluminum salts. γ-aluminum oxide-
A cerium oxide-zirconium matrix has proven advantageous. Also, Ce ₂ O ₃
or γ-series aluminum oxide containing CeO ₂ and/or ZrO ₂ or trivalent or tetravalent cerium and/or zirconium salts, and at a temperature of 500°C to 900°C before or after providing the catalytically active component. 〓Can be baked. This calcination is advantageously carried out before applying the catalytically active components. Dispersions of heat-resistant carrier substances can be prepared using techniques known per se, such as grinding processes, pH-stabilizing polyethine remin and precipitation prevention methods such as ammonium salts of polymeric carboxylic acids (German Patent No. 2531769). Addition of agents and aging methods are applied.

In an advantageous embodiment which favorably influences the deposition of specific support substances which promote the catalytic reaction, a strip of sieve cloth with smooth and corrugated layers or with closed hollow or open support profiles is oxygen-containing. in gas,
It is advantageous to heat under conditions of temperature and time such that a surface layer of aluminum oxide is formed from the aluminum contained in the alloy;
In this case, the strip screen cloth with smooth and corrugated layers or with closed hollow or open support profiles can be further coated by the washcoating process after the formation of the aluminum oxide coating.
It can be coated with other support materials of the same or different composition that promote the catalytic reaction.

However, a strip of sieve cloth with smooth and corrugated layers or closed hollow or open support profiles is first coated with a carrier substance that promotes the catalytic reaction by a washcoating process, and then the coated substance is Heating can also be carried out in an oxygen-containing gas under such time and temperature conditions that aluminum oxide is formed from the aluminum contained in the alloy.

To form the surface layer of aluminum oxide, the aluminum oxide is formed from the alloy by heating in air at a temperature of 750° C. to 1100° C. and in particular for 1 to 7 hours, especially about 4 hours. good.

Strip sieve cloths with coated smooth and corrugated layers or closed hollow or open supporting profiles are
It can be rolled up into a cylinder with a helical cross-section, which can be pressed under initial tension into a steel jacket and optionally welded therein. Therefore, support matrices of cylinders with a helical cross-section, which are adhered and strongly coated with metal oxides which promote the catalytic reaction and are optionally provided with a steel jacket, obtained by the abovementioned means, are also useful in accordance with the invention. It is a target.

Finally, the invention further provides catalysts, in particular noble metals and/or base metals, which are deposited as an intermediate carrier on a support material that promotes the catalytic reaction, in particular for purifying the exhaust gases of internal combustion engines and industrial installations. The present invention relates to the use of said support matrix in the production of catalysts.

Claims (1)

[Scope of Claims] 1. Consisting of superposed layers of heat-resistant and scaling-resistant steel, with a cross-flow effect and an enlarged geometrical surface area and a catalytic reaction present in the immersion dispersion. An improved catalyst support matrix having an improved retention capacity for metal oxides promoting catalytic flow, wherein the layers protrude from the plane of the smooth sieve cloth at intervals parallel to the direction of the desired flow channels. consisting of a smooth sieve cloth, to which a hollow support profile with a closed cross section or a support profile with an open cross section is woven or woven into the surface; The layers alternate with layers of smooth sieve cloth with closed hollow support profiles or open support profiles suitably woven or woven into the surface, or with smooth or corrugated support profiles. Layers of sheet metal sheets alternate with layers of smooth sieve cloth with closed hollow support profiles or open support profiles suitably woven or bonded to the surface, in which case: Sieve cloth has a mesh size of 0.18~0.025mm and 0.15~
have a wire thickness of 0.025 mm and that the metal sheets, sieve cloth and closed hollow support profiles or open support profiles consist of an alloy of iron, chromium, aluminum and optionally also cerium or yttrium; An improved catalyst carrier matrix characterized by: 2 Numerous sieve cloth strips with closed hollow support profiles or open support profiles, optionally other smooth or corrugated sieve cloth strips or sheet metal strips with a helical cross-section A carrier matrix according to claim 1, which is rolled up into a cylindrical body having flow grooves. 3. The sieve cloth according to claim 1 or 2, wherein the sieve cloth is a strip having an opening of 0.1 to 0.05 mm, particularly 0.073 mm, and a wire thickness of 0.1 to 0.05, particularly 0.07 mm. carrier matrix. 4. The cross-sectional area of the closed hollow support profile or the open support profile is determined to be less than 5 mm ² , in which case the respective cross-sectional area to be selected depends on the desired dimensions of the flow channel and the thickness of the wire of the sieve cloth. determined by
A carrier matrix according to any one of claims 1 to 3. 5. Claims 1 to 5, in which each flow groove formed by a woven, closed hollow or open support profile creating a spacing has a cross-sectional area of less than or equal to 5 mm ² 4. The carrier matrix according to any one of items 4 to 4. 6 Closed hollow support profiles or open support profiles with a minimum of 1 mm and a maximum of 5 mm in the plane of the strip of sieve cloth.
6. A carrier matrix according to claim 1, wherein the carrier matrices are spaced apart from each other. 7. The carrier matrix according to claim 1, wherein the alloy consists of 15% by weight of chromium, 5% by weight of aluminum, and the remainder iron. 8 Alloys up to 15% by weight of chromium, aluminum
0.5-12% by weight, cerium or yttrium 0.1-
Claim 1 consisting of 3% by weight of remaining iron.
The carrier matrix described in Section 1. 9. Any of claims 1 to 6, in which the individual layers are welded to each other circumferentially and/or end-wise pointwise or in their entirety, or the final layer is welded to the preceding layer. The carrier matrix according to item 1. 10. A carrier matrix according to claim 9, wherein the 10 layers are arc welded. 11. A carrier matrix according to any one of claims 1 to 6, wherein the layer is coated on its surface with a carrier material that promotes the catalytic reaction. 12. According to any one of claims 1 to 9, which is arranged as a rolled-up cylinder with a helical cross-sectional area in a steel jacket and/or welded therein. The carrier matrix described. 13. Any of claims 1 to 12, in which the individual helically wound layers are made secure against displacement by means of a cross support rigidly arranged on the end face of the steel jacket. 2. The carrier matrix according to item 1. 14. Consisting of superposed layers of heat-resistant and scaling-resistant steel, with a cross-flow effect and an enlarged geometric surface area and metal oxides promoting catalytic reactions present in the immersion dispersion. In a method for producing an improved support matrix for catalysts, the surface of which is smooth and corrugated, or which has closed hollow support profiles or open support profiles. An improved method for producing a support matrix for a catalyst, characterized in that the fabric is coated with a support material that promotes the catalytic reaction before being rolled up into a cylinder. 15 A strip of sieve cloth with smooth and corrugated layers or with closed hollow or open support profiles is heated in an oxygen-containing gas with a surface layer consisting of aluminum oxide from the aluminum contained in the alloy. 15. The method of claim 14, wherein the method is heated under conditions of temperature and time such that formation occurs. 16 The strip screen cloth with smooth and corrugated layers or with closed hollow or open support profiles is coated with identical or 16. A method according to claim 15, comprising coating with other carrier materials of different chemical composition. 17. A strip of sieve cloth with smooth and corrugated layers or with closed hollow or open support profiles is first coated with a carrier substance promoting the catalytic reaction by the washcoating process and then coated 15. The method of claim 14, wherein the material is heated in an oxygen-containing gas under conditions of time and temperature such that aluminum oxide forms and separates from the aluminum contained in the alloy. 18 From alloy to 750℃~1100℃, especially 900℃~1000℃
18. The aluminum oxide is formed and separated by heating in air at a temperature of 1 to 7 hours, in particular about 4 hours. the method of. 19. A strip of sieve cloth with smooth and corrugated layers or with closed hollow or open support profiles is rolled up into a cylinder with a helical cross-section and this cylinder is placed under initial tension in a steel jacket. Push it inside,
19. The method as claimed in claim 14, optionally by welding into the jacket. 20 strongly coated with metal oxides that promote catalytic reactions, optionally with a steel jacket;
20. The method as claimed in claim 14, wherein a cylindrical support matrix with a helical cross section is obtained. 21 A method for producing a catalyst deposited as an intermediate carrier on a carrier material that promotes a catalytic reaction, in which layers of heat-resistant and scaling-resistant steel are arranged one on top of the other, and the layers form a desired flow channel. A smooth sieve cloth on which hollow support profiles of closed cross section or support profiles of open cross section project from the plane of the smooth sieve cloth at intervals parallel to the direction of Smooth sieves with closed hollow supporting profiles or open supporting profiles, which are made of solid sieve screen cloth or in which a layer of smooth sieve screen cloth is suitably woven or bonded to the surface. alternating with layers of mesh fabric or layers of smooth or corrugated metal sheets with closed hollow support profiles or open support profiles suitably woven or bonded to the surface; appear alternating with layers of smooth sieve cloth, where the sieve cloth
It has a mesh opening of 0.18-0.025 mm and a wire thickness of 0.15-0.025 mm, and the metal sheet, sieve cloth and closed hollow supporting profile or open supporting profile are made of iron, chrome, aluminum and the like. Further consisting of an alloy of cerium or yttrium, it has a cross-flow effect, as well as an enlarged geometrical surface area and an improved retention capacity for the metal oxides present in the immersion dispersion that promote the catalytic reaction. A method for producing a catalyst for purifying waste gas, characterized by using an improved catalyst carrier matrix.