EP2158037A2

EP2158037A2 - Method for producing a shell catalyst and corresponding shell catalyst

Info

Publication number: EP2158037A2
Application number: EP08758903A
Authority: EP
Inventors: Alfred Hagemeyer; Gerhard Mestl; Peter Scheck; Silvia Neumann
Original assignee: Sued Chemie AG
Current assignee: Sued Chemie AG
Priority date: 2007-05-31
Filing date: 2008-05-30
Publication date: 2010-03-03
Also published as: CN101687179A; WO2008145391A2; US20100190638A1; CN101687179B; WO2008145391A3; DE102007025356A1

Abstract

The invention relates to a method for producing a shell catalyst which comprises a porous molded catalyst support having an outer shell in which at least one transition metal is contained in metallic form. The aim of the invention is to provide a shell catalyst production method which allows production of supported transition metal catalysts in the form of shell catalysts that have a relatively little shell thickness. The method according to the invention makes use of a device (10) which is adapted to cause the molded catalyst supports to circulate by means of a reducing process gas (40). Said method comprises the following steps: a) feeding molded catalyst supports to the device (10) and causing the molded catalyst supports to circulate by means of a reducing process gas (40); b) impregnating an outer shell of the molded catalyst supports with a transition metal precursor compound by spraying the circulating molded catalyst supports with a solution that contains the transition metal precursor compound; c) converting the metal component of the transition metal precursor compound to the metallic form by reduction with the process gas (40); d) drying the molded catalyst supports that are sprayed with said solution.

Description

-5

Process for the preparation of a coated catalyst and

Coated catalyst 0

The present invention relates to a process for the preparation of a coated catalyst comprising a porous catalyst support molding having an outer shell, in which at least one transition metal in metallic form is contained.

Supported transition metal catalysts in the form of coated catalysts and processes for their preparation are known in the art. In shell catalysts, the catalytically active species - often also the promoters - are contained only in a more or less wide outer region (shell) of a catalyst support molding, i. they do not completely penetrate the catalyst support molding 5 (cf., for example, EP 565 952 A1, EP 634 214 A1, EP 634 209 A1 and EP 634 208 A1). With coated catalysts, a more selective reaction is possible in many cases than with catalysts in which the carrier is loaded into the carrier core with the catalytically active species 0 ("impregnated through").

Vinyl acetate monomer (VAM), for example, is currently produced predominantly by coated catalysts in high selectivity. The majority of the currently used 5 coated catalysts for the production of VAM are

Shell catalysts with a Pd / Au shell on a porous amorphous formed as a ball aluminosilicate based on natural phyllosilicates, wherein the carrier with Potassium acetate are impregnated as a promoter. In the Pd / Au system of these catalysts, the active metals Pd and Au are presumably not in the form of metal particles of the respective pure metal, but rather in the form of Pd / Au alloy particles of possibly different composition, although the presence of unalloyed particles is not excluded can be.

VAM shell catalysts are usually prepared by a so-called chemical route in which the catalyst support is reacted with solutions of corresponding metal compounds, for example by immersing the support in the solutions or by the incipient wetness method in which the support has a pore volume corresponding solution volume is loaded, is soaked.

The Pd / Au shell of a VAM shell catalyst is produced, for example, by first impregnating the catalyst support molding in a first step with a Na ₂ PdCl ₄ solution and then, in a second step, impregnating the Pd catalyst.

Component is fixed with NaOH solution on the catalyst support in the form of a Pd hydroxide compound. In a subsequent separate third step, the catalyst support is then impregnated with a NaAuCl ₄ solution and then the Au component is likewise fixed by means of NaOH. For example, it is also possible first to impregnate the carrier with caustic and then to apply the precursor compounds to the carrier pretreated in this way. After fixing the noble metal components on the catalyst support of the loaded catalyst support is then washed largely free of chloride and Na ions, then dried and finally reduced at 150 ⁰ C with ethylene. The generated Pd / Au shell usually has a thickness of about 100 to 500 .mu.m, wherein in As a rule, the smaller the thickness of its shell, the higher the product selectivity of a shell catalyst.

Typically, after the fixation or reduction step, the catalyst support loaded with the noble metals is then loaded with potassium acetate, the loading with potassium acetate not only taking place in the outer shell loaded with precious metals, but rather completely impregnated with the promoter by the promoter.

According to the prior art, the active metals Pd and Au are applied starting from chloride compounds in the region of a shell of the support on the same by means of impregnation. However, this technique has reached the limits as far as minimum shell thicknesses are concerned. The thinnest achievable shell thickness according to VAM catalysts produced is at best about 100 microns and it is not foreseeable that even thinner shells can be obtained by impregnation. In addition, the catalysts produced by means of impregnation have a relatively large average dispersion of the noble metal particles, which may adversely affect, in particular, the activity of the catalyst.

It is an object of the present invention to provide a shell catalyst production process by means of which supported transition metal catalysts in the form of shell catalysts can be prepared which have a relatively small shell thickness.

This object is achieved by a first method using a device which is set up to produce a circulation of catalyst support shaped bodies by means of a reducing process gas, comprising the steps of a) charging the device with Katalysatorträger- moldings and generating a catalyst carrier-shaped body circulation by means of a reducing process gas;

b) impregnating an outer shell of the catalyst support moldings with a transition metal precursor compound by spraying the circulating catalyst support moldings with a solution containing the transition metal precursor compound,

c) converting the metal component of the transition metal precursor compound into the metallic form by reduction by means of the process gas;

d) drying the sprayed with the solution catalyst support moldings.

It has surprisingly been found that shell catalysts with relatively thin shells can be produced by means of the process according to the invention, in particular less than 100 μm.

Furthermore, transition metal shell catalysts having a relatively high metal loading can be produced by means of the process according to the invention, the metal particles of the catalysts having a relatively high average dispersion.

The first method according to the invention is carried out with a reductive-acting process gas. This makes it possible that the metal component of the transition metal precursor compound immediately after the order on the Catalyst carrier is reduced to the metal and thereby fixed to the carrier. During the implementation of the method according to the invention, the reduction of metal component to the metal thus takes place continuously, as long as new metal compound is applied to the carrier.

The drying of the moldings sprayed with the solution takes place in the context of the method according to the invention preferably continuously by means of the process gas. However, it can also be provided that, after impregnation with continuous drying, a separate final drying step is carried out. In the first case, for example, by the temperature of the process gas or the molded body, the drying rate and thus the penetration depth (thickness of the shell) can be set individually, in the second case can be dried by any known to those skilled in drying method.

If the shell-type catalyst to be prepared in the shell contains a plurality of mutually different transition metals, for example a plurality of active metals or an active metal and a promoter metal, the catalyst support molding may be subjected to the process according to the invention frequently, for example. Alternatively, the process of the invention may be carried out with mixed solutions containing transition metal precursor compounds of mutually different metals. Furthermore, the process according to the invention can be carried out by simultaneously spraying the catalyst supports with several solutions of precursor compounds of different metals.

The reductive process gas to be used in the process according to the invention is preferably a gas mixture comprising an inert gas and a reductive component. there can the reduction rate and thus to a certain extent the shell thickness be adjusted, inter alia, on the proportion of the reductively acting component in the gas mixture.

The inert gas used is preferably a gas selected from the group consisting of nitrogen, carbon dioxide and the noble gases, preferably helium and argon, or mixtures of two or more of the aforementioned gases.

The reductive component is generally to be selected depending on the nature of the metal component to be reduced, but preferably selected from the group of gases or vaporizable liquids consisting of ethylene, hydrogen, CO, NH ₃ , formaldehyde, methanol, formic acid and hydrocarbons, or is a mixture of two or more of the aforementioned gases / liquids.

In particular, with regard to precious metals as metal components to be reduced, gas mixtures of hydrogen with

Nitrogen or argon may be preferred, preferably with a hydrogen content between 1 vol .-% and 15 vol .-%. The process according to the invention is carried out, for example, with hydrogen (5% by volume) in nitrogen as process gas at a temperature of about 150 ^° C. over a period of, for example, 5 hours. When the desired amount of transition metal precursor compound solution has been applied to the moldings, the spraying can be stopped and the circulation maintained until complete reduction of the applied metal component. The terms "catalyst support shaped body",

"Catalyst support", "shaped body" and "support" are used synonymously in the context of the present invention.

The above object is further solved by a second method using a device which is adapted to produce a circulation of catalyst support moldings, preferably by means of a process gas, comprising the steps of

a) feeding the device with Katalysatorträger- shaped bodies and generating a catalyst carrier-shaped body circulation, preferably by means of a process gas;

b) impregnating an outer shell of the catalyst support moldings with a transition metal precursor compound by spraying the circulating catalyst support moldings with a solution containing the transition metal precursor compound;

c) transferring the metal component of the transition metal

Precursor compound in the metallic form by means of a reducing agent, which is applied by impregnating at least the outer shell of the catalyst support molded body by spraying the circulating Katalysatorträger- shaped body with a solution containing the reducing agent on the catalyst carrier molded body;

d) drying the catalyst support shaped body. The second method according to the invention has the same

Advantages such as those mentioned above for the first erfindungsgetne method.

The remarks concerning the first method with regard to drying and the production of coated catalysts in whose shells a plurality of mutually different transition metals are contained apply analogously to the second method according to the invention.

Spraying the catalyst support with the solution of

Transition metal precursor compound and with the solution of the reducing agent can be carried out, for example, successively, wherein both the one and the other solution can be sprayed on first. However, it is preferred if the two solutions are sprayed simultaneously onto the catalyst support, preferably with a two-fluid nozzle designed as an annular gap nozzle.

Reducing agents which are preferably used in the second process according to the invention are selected from the group consisting of hydrazine, K formate, Na formate, ammonium formate, formic acid, K hypophosphite, hypophosphorous acid, H ₂ O ₂ and Na hypophosphite ,

For the second method according to the invention, the process gas is preferably selected from the group consisting of air, oxygen, nitrogen and the noble gases, preferably helium and argon.

In the first and second processes according to the invention, the circulation of the catalyst support shaped bodies is preferably carried out by producing a fluidized bed or a fluidized bed of catalyst support shaped bodies by means of the process gas accomplished. This ensures a particularly uniform application of the respective solution to the catalyst support.

In the second method according to the invention, the circulation of the catalyst support molded bodies can also be carried out, for example by means of

Drag drums or mixing devices are made.

Accordingly, the first method according to the invention in

Be carried out as a device, while the second method according to the invention also in drag drums, mixers,

Pelleting devices or double cone mixers as

Device can be executed.

Suitable drag drums, fluidized bed plants or fluidized bed plants for carrying out the inventive

Methods according to preferred embodiments are known in the art and are e.g. by the companies Heinrich Brucks GmbH (Alfeld, Germany), ERWEK GmbH (Heusenstamm, Germany), Stechel (Germany), DRIAM Anlagenbau GmbH (Eriskirch, Germany), Glatt GmbH (Binzen, Germany), GS Divisione Verniciatura (Osteria, Italy) , HOFER-Pharma Maschinen GmbH (Weil am Rhein, Germany), LB Bohle Maschinen + Verfahren GmbH (Enningerloh, Germany), Lödige Maschinenbau GmbH (Paderborn, Germany), Manesty (Merseyside, UK), Vector Corporation (Marion, IA, USA ), Aeromatic-Fielder AG (Bubendorf, Switzerland), GEA Process Engineering (Hampshire, UK), Fluid Air Inc. (Aurora, Illinois, USA), Heinen Systems GmbH (Varel, Germany), Hüttlin GmbH (Steinen, Germany), Umang Pharmatech Pvt. Ltd.

(Marharashtra, India) and Innojet Technologies (Lörrach, Germany). Unless otherwise indicated, the following embodiments of methods relate both to the first and second methods according to the invention. Accordingly, an express reference to the first or second method is omitted below, and the term "method" is used in the singular.

According to a particularly preferred embodiment of the method according to the invention, a fluidized bed of catalyst support shaped bodies is produced by means of the process gas in which the shaped bodies rotate elliptically or toroidally, preferably toroidally. As a result, a particularly uniform application of the solutions to be applied is ensured, so that shell catalysts with a particularly uniform shell thickness are obtainable according to this embodiment. It may be preferred that the elliptical or toroidal rotating moldings rotate at a speed of 1 to 50 cm / s, preferably at a speed of 3 to 30 cm / s and preferably at a speed of 5 to 20 cm / s.

In the method according to the invention, a fluidized bed is preferably produced, in which the molded bodies rotate in an elliptical or toroidal manner. In the prior art, the transition of the particles of a bed in a state in which the particles are completely free to move (fluidized bed), as

Loosening point (fluidized point) and the corresponding fluid velocity as loosening speed. It is preferred according to the invention that in the method according to the invention the fluid velocity is up to 4 times the loosening speed, preferably up to 3 times the loosening speed and more preferably up to 2 times the loosening speed. According to an alternative embodiment of the method according to the invention, it may be provided that the

Fluid velocity up to 1.4 times the log of the rate of deceleration, preferably up to 1.3 times the log of the rate of deceleration, and more preferably up to 1.2 times the log of the rate of deceleration.

Fluid bed apparatuses preferred for carrying out the process according to the invention are described, for example, in the documents WO 2006/027009 A1, DE 102 48 116 B3, EP 0 370 167 A1, EP 0 436 787 B1, DE 199 04 147 A1, DE 20 2005 003 791 U1 whose content is incorporated by referencing in the present invention. Particularly preferred for carrying out the process fluid bed devices are distributed by Innojet Technologies under the names Innojet ^® Ventilus or Innojet ^® AirCoater. These devices comprise a cylindrical container with a fixed and immovably installed container bottom, in the middle of which a spray nozzle is mounted. The floor consists of circular lamellae, which are gradually mounted one above the other. The process gas flows in these devices between the individual slats horizontally, eccentrically, with a peripheral flow component to the outside in the direction of the container wall into the container. In the process, so-called air sliding layers form, on which the catalyst carrier shaped bodies are initially transported outwards in the direction of the container wall. Externally on the vessel wall, a vertically aligned process air flow is installed, which deflects the catalyst carriers upwards. Once at the top, the catalyst carriers move back in a more or less tangential path toward the center of the floor, in the course of which they pass the spray of the nozzle. After this Passing the spray begins the described

Motion process again. The process gas guidance described provides the basis for a largely homogeneous toroidal fluidized bed-like circulation movement of the catalyst support.

The interaction of the spraying with the elliptical or toroidal movement of the catalyst carriers in the fluidized bed, in contrast to a conventional fluidized bed, causes the individual catalyst carriers to pass the spray nozzle at approximately the same frequency. In addition, such provides

Umwälzvorgang also ensure that the individual catalyst support perform a rotation about its own axis, which is why the catalyst support can be impregnated particularly uniform.

According to the preferred embodiment of the process according to the invention, the catalyst support shaped bodies run in the fluidized bed elliptically or toroidally, preferably toroidally. To give an idea of how the moldings move in the fluidized bed, it should be understood that the catalyst support moldings, when "elliptical" in the fluid bed, move in a vertical plane on an elliptical orbit of varying major and minor axis sizes. In "toroidal recirculation", the catalyst support moldings in the fluidized bed move in a vertical plane on an elliptical orbit of varying major and minor axis size and in a horizontal plane on a circular orbit of varying radius of radius. On average, in the case of "elliptical circulation", the shaped bodies move in a vertical plane on an elliptical path, in "toroidal circulation" on a toroidal path, ie a shaped body helically moves off the surface of a torus with a vertically elliptical section. To accomplish a catalyst carrier-shaped body fluidized bed, in which the catalyst support moldings elliptical or toroidal circulate in procedurally simple and thus cost-effective manner, is, according to a further preferred embodiment of the invention

Method provided that the device comprises a process chamber having a bottom and a side wall, wherein the process gas through the bottom of the process chamber, which is preferably constructed of a plurality of superposed, overlapping annular guide plates, between which annular slots are formed, with a horizontal, radially outward movement component is introduced into the process chamber.

Characterized in that process gas is introduced with a horizontal, radially outward movement component in the process chamber, an elliptical circulation of the catalyst carrier is effected in the fluidized bed. If the moldings in the fluidized bed are to rotate in a toroidal manner, then the moldings must additionally have a circumferential shape

Movement component are imposed, which forces the moldings on a circular path. This circumferential movement component can be imposed on the moldings, for example, by correspondingly aligned guide rails for deflecting the sidewall

Catalyst supports are arranged. According to a further preferred embodiment of the method according to the invention, however, it is provided that a circumferential flow component is imposed on the process gas introduced into the process chamber. This will cause the generation of the

Catalyst support shaped body fluidized bed in which the catalyst support moldings rotate toroidally, procedurally simple and thus guaranteed cost.

In order to impose the circumferential flow component on the process gas introduced into the process chamber, it can be provided according to a further preferred embodiment of the method according to the invention that appropriately shaped and aligned process gas guide elements are arranged between the annular guide plates. Alternatively or additionally, it can be provided that the process gas introduced into the process chamber, the circumferential

Flow component is imposed by additional process gas is introduced through the bottom, preferably in the region of the side wall of the process chamber, the process chamber with an obliquely upward movement component in the process chamber.

It may be provided that the spraying of the catalyst support shaped bodies with the solution is carried out by means of an annular gap nozzle which sprays a spray cloud, wherein the plane of symmetry of the spray cloud preferably runs parallel to the plane of the device floor. Due to the 360 ° circumference of the spray cloud, the moldings can be sprayed particularly evenly with the solution. The annular gap nozzle, i. whose mouth, preferably completely embedded in the moldings.

According to a further preferred embodiment of the method according to the invention, it is provided that the annular gap nozzle is arranged centrally in the bottom and the mouth of the annular gap nozzle is completely embedded in the circulating catalyst carrier. This ensures that the free path of the droplets of the spray cloud is relatively short until it hits a molded body and according to the drops relatively little time remains to coalesce into larger drops, which could counteract the formation of a largely uniform shell thickness.

According to a further preferred embodiment of the method according to the invention, provision may be made for a gas support pad to be effected on the underside of the spray cloud. The bottom-side pad keeps the bottom surface largely free of sprayed solution, which is why almost all of the sprayed solution is introduced into the revolving moldings, so that hardly

Spraying losses occur, which is particularly important in terms of cost of precious precious metal precursor compounds for cost reasons.

According to a further preferred embodiment of the method according to the invention, it is provided that the catalyst support is spherical. This ensures a uniform rotation of the support about its axis and, consequently, a uniform impregnation of the catalyst support with the solution of the catalytically active species.

As a catalyst support in the process according to the invention porous moldings of any shape can be used, wherein the carrier can be formed from all materials or material mixtures. According to the invention, however, preference is given to those catalyst supports which comprise at least one metal oxide or are formed from such a or a metal oxide mixture. Preferably, however, the catalyst support comprises a silica, an alumina, an aluminosilicate, a zirconia, a titania, a niobium oxide or a natural layered silicate, preferably a calcined acid-treated bentonite. The term "natural phyllosilicate", for which the term "phyllosilicate" is used in the literature, is understood to mean untreated or treated silicate mineral originating from natural sources in which SiO ₄ tetrahedra, which form the structural unit of all silicates, are present in Layers of the general formula [Si ₂ O ₅ ] ^{2 '} are crosslinked with each other. These tetrahedral layers alternate with so-called octahedral layers, in which a cation, especially Al ³⁺ and Mg ²⁺ , is octahedrally surrounded by OH or O. For example, two-layer

Phyllosilicates and three-layer Phyllosilikate distinguished. Phyllosilicates preferred in the context of the present invention are clay minerals, in particular kaolinite, beidellite, hectorite, saponite, nontronite, mica, vermiculite and smectites, with smectites and in particular

Montmorillonit are particularly preferred. Definitions of the term "layered silicates" can be found, for example, in "Textbook of Inorganic Chemistry", Hollemann Wiberg, de Gruyter, 102nd Edition, 2007 (ISBN 978-3-11-017770-1) or in "Römpp Lexikon Chemie", 10. Edition, Georg Thieme Verlag under the term "phyllosilicate". Typical treatments to which a natural layered silicate is subjected prior to use as a carrier include, for example, treatment with acids and / or calcining. A particularly preferred natural layered silicate in the context of the present invention is a bentonite. Bentonites are not natural layer silicates in the true sense, but rather a mixture of predominantly clay minerals, in which phyllosilicates are contained. In the present case, therefore, in the case where the natural sheet silicate is a bentonite, it is to be understood that the natural sheet silicate is present in the catalyst support in the form or as part of a bentonite. A catalyst support based on natural sheet silicates, in particular on the basis of an acid-treated calcined bentonite, can be produced, for example, by forming a mixture containing an acid-treated (uncalcined) bentonite as sheet silicate and water while compacting it into a shaped body by means of devices known to the person skilled in the art , such as extruders or tablet presses, molded and then the uncured molded body is calcined to form a stable molded body. The size of the specific surface of the catalyst support depends in particular on the quality of the (bent) bentonite used, the acid treatment process of the bentonite used, ie, for example, the nature and relative to bentonite and the concentration of the inorganic acid used, the acid treatment time and temperature, the compression pressure as well as the calcination time and temperature and the calcination atmosphere.

Acid-treated bentonites can be obtained by treating bentonites with strong acids, such as sulfuric acid, phosphoric acid or hydrochloric acid. A definition of the term bentonite which also applies in the context of the present invention is given in Römpp, Lexikon

Chemie, 10th ed., Georg Thieme Verlag, stated. Bentonites which are particularly preferred in the context of the present invention are natural aluminum-containing sheet silicates which contain montmorillonite (as smectite) as the main mineral. After the acid treatment, the bentonite is usually washed with water, dried and ground to a powder. It has been found that by means of the method according to the invention, relatively large shell thicknesses can also be achieved. Namely, the smaller the surface of the carrier, the larger the achievable thickness of the shell. According to a further preferred embodiment of the method according to the invention, it may be provided that the catalyst support has a surface area of 160 m ² / g or less, preferably one of less than 140 m ² / g, preferably less than 135 m ² / g, more preferably one of less than 120 m ² / g, more preferably one of less than 100 m ² / g, even more preferably one of less than 80 m ² / g and particularly preferably one of less than 65 m ² / g. In the context of the present invention, the term "surface area" of the catalyst support is understood to mean the BET surface area of the support, which is determined by adsorption of nitrogen in accordance with DIN 66132.

According to a further preferred embodiment of the process according to the invention, it is provided that the catalyst support has a surface area of 160 to 40 m ² / g, preferably one of between 140 and 50 m ² / g, preferably one of between 135 and 50 m ² / g , more preferably one of between 120 and 50 m ² / g, more preferably between 100 and 50 m ² / g and most preferably between 100 and 60 m ² / g.

When circulating the carrier in the context of the method according to the invention, the catalyst supports are mechanically stressed, which can lead to a certain abrasion and a certain damage of catalyst supports, in particular in the region of the resulting shell. In particular, in order to keep the abrasion of the catalyst support within reasonable limits, the catalyst support has a hardness of greater than or equal to 20 N, preferably greater than or equal to 30 N, more preferably greater than or equal to 40 N, and most preferably greater than or equal to 50 N. Determination of the hardness is carried out using a 8M tablet hardness tester. Dr. Schleuniger Pharmatron AG at 99 piece moldings as the average determined after drying at 130 ⁰ C for 2 h, where the machine settings are as follows:

Hardness: N

Distance to the molded body: 5.00 mm

Time delay: 0.80 s

Feed type: 6 D

Speed: 0.60 mm / s

The hardness of the catalyst support can, for example, by variation of certain parameters of the process to his

Production, for example, by the selection of the support material, the calcination and / or the calcination temperature of a shaped from a corresponding carrier mixture, uncured molding, or by certain additives such as methyl cellulose or magnesium stearate.

For reasons of cost, air is preferably used as process gas in the process according to the invention. However, if, for example, the catalytically active species or the precursor thereof react with air oxygen to form undesired compounds, it can also be provided that an inert gas is used as the process gas, for example nitrogen, methane, CO ₂ , short-chain saturated Hydrocarbons, one of the noble gases, preferably helium, neon or argon, or a halogenated hydrocarbon.

According to a further preferred embodiment of the method according to the invention, the process gas, especially in the case of expensive gases such. Helium, argon, etc., are recycled by means of a closed circuit in the device.

According to a further preferred embodiment of the method according to the invention, the catalyst support is heated before and / or during the application of the solution, for example by means of a heated process gas. By the degree of heating of the catalyst supports, the rate of drying of the applied solution of the transition metal precursor compound can be determined. For example, at relatively low temperatures, the rate of desiccation is relatively slow, so that, given adequate quantitative coverage, the formation of larger shell thicknesses may occur due to the high diffusion of the metal compound due to the presence of solvent. For example, at relatively high temperatures, the drying rate is relatively high, so that solution coming in contact with the catalyst support dries almost instantaneously, so solution applied to the catalyst support can not penetrate deeply into it. At relatively high temperatures so shells with relatively small thicknesses and high loading of metal can be obtained. According to a further preferred embodiment of the method according to the invention, the process gas is heated, preferably to a temperature of greater than or equal to 40 ⁰ C, preferably to a temperature of greater than or equal to 60 ⁰ C, more preferably to a temperature of greater than or equal to 70 ^° C., and most preferably to a temperature of 60 to 110 ^° C.

By way of the temperature at which the process according to the invention is carried out, the thickness of the shell of the process resulting from the process according to the invention can be determined

Shell catalyst can be influenced. Thinner shells are generally obtained when the process is performed at higher temperatures, while at lower temperatures, thicker shells are typically obtained. According to a further preferred embodiment, it is therefore provided that the process gas is heated, preferably to a temperature between 80 and 200 ⁰ C.

In order to prevent premature drying of droplets of the spray cloud, it may according to a further preferred

Embodiment of the inventive method be provided that the process gas is enriched prior to introduction into the device with the solvent of the solution sprayed into the device, preferably in a range of 10 to 50% of the saturation vapor pressure (at process temperature).

According to a further preferred embodiment of the method according to the invention, the solvent added to the process gas and solvents which originate from the drying of the shaped bodies can be separated off from the process gas by means of suitable cooler units, condensers and separators and returned to the solvent enricher by means of a pump.

Solutions of metal compounds of any transition metals can be used in the process according to the invention. However, it is preferred that the solution of Transition metal precursor compound as a transition metal precursor compound contains a noble metal compound.

According to a further preferred embodiment of the method according to the invention, it is provided that the noble metal compound is selected from the halides, especially chlorides, oxides, nitrates, nitrites, formates, propionates, oxalates, acetates, citrates, tartrates, lactates, hydroxides, bicarbonates, amine complexes or organic complexes, for example triphenylphosphine complexes or acetylacetonate complexes, of the noble metals.

To prepare a shell catalyst for oxidation reactions, it is provided according to a further preferred embodiment of the method according to the invention that the solution of the transition metal precursor compound contains a Pd compound as a transition metal precursor compound.

In order to produce a gold-containing shell catalyst, it is provided according to a further preferred embodiment of the method according to the invention that the solution of the transition metal precursor compound contains an Au compound as the transition metal precursor compound.

In order to produce a platinum-containing shell catalyst, it is provided according to a further preferred embodiment of the method according to the invention that the solution of the transition metal precursor compound contains a Pt compound as the transition metal precursor compound.

For producing a silver-containing shell catalyst, it is according to a further preferred embodiment of the The process according to the invention provides that the solution of the transition metal precursor compound contains, as transition metal precursor compound, an Ag compound.

Accordingly, according to a further preferred embodiment of the process according to the invention for producing a nickel-, cobalt- or copper-containing coated catalyst, it may be provided that the solution of the transition metal precursor compound contains a Ni, Co or Cu compound as the transition metal precursor compound.

Commercially available solutions of the precursor compounds, such as Na ₂ PdCl ₄ , NaAuCl ₄ or HAuCl ₄ solutions, are usually used in the processes described in the prior art for the preparation of Pd-based VAM shell catalysts. The recent literature also uses chloride-free Pd or Au precursor compounds such as Pd (NH ₃ J ₄ (OH) ₂ .Pd (NH ₃ ) ₂ (NO ₂ ) ₂ and KAuO _2.) These precursor compounds react basicly in solution while the classic chloride, nitrate and acetate precursors in solution all react acidically.

In principle, any Pd or Au compound can be used as Pd and Au precursor compounds, by means of which a sufficiently high degree of dispersion of the metal particles can be achieved for VAM synthesis. The term "degree of dispersion" is understood to mean the ratio of the number of all surface metal atoms (of the metal in question) of all metal / alloy particles of a supported metal catalyst to the total number of all metal atoms of the metal / alloy particles In general, it is preferred if the degree of dispersion is relatively high high numerical value, since in this case as many metal atoms for a catalytic reaction freely accessible are. That means that at a relatively high

Degree of dispersion of a supported metal catalyst can be achieved a certain catalytic activity thereof with a relatively small amount of metal used.

Examples of preferred Pd precursor compounds are water-soluble Pd salts. According to a particularly preferred embodiment of the method according to the invention, the Pd precursor compound is selected from the group consisting of H ₂ PdCl ₄ , K ₂ PdCl ₄ , (NH ₄ J ₂ PdCl ₄ , Pd (NH ₃ ) ₄ Cl ₂ , Pd (NH ₃ ) ₄ (HCO ₃ ) ₂ ,

Pd (NH ₃ ) ₄ (HPO ₄ ), ammonium Pd oxalate, Pd oxalate, K ₂ Pd (oxalate) ₂ , Pd-II trifluoroacetate, Pd (NH ₃ ) ₄ (OH) ₂ , Pd (NO ₃ J ₂ , K ₂ Pd (OAc) ₂ (OH) ₂ , Pd (NH ₃ ) ₂ (NO ₂ ) ₂ , Pd (NH ₃ J ₄ (NO ₃ ) ₂ , K ₂ Pd (NO ₂ ) ₄ , Na ₂ Pd (NO ₂ J ₄ , Pd (OAc) ₂ , PdCl ₂ and Na ₂ PdCl ₄ In addition to Pd (OAc) ₂ , it is also possible to use other carboxylates of palladium, preferably the salts of aliphatic monocarboxylic acids having 3 to 5 carbon atoms, for example Propionate or butyrate salt.

According to a further preferred embodiment of the method according to the invention, Pd nitrite precursor compounds may also be preferred. Preferred Pd nitrite precursor compounds are, for example, those obtained by dissolving Pd (OAc) ₂ in a NaNO ₂ or KNO ₂ solution.

Examples of preferred Au precursor compounds are water-soluble Au salts. According to a particularly preferred embodiment of the method according to the invention, the Au precursor compound is selected from the group consisting of KAuO ₂ , NaAuO ₂ , KAuCl ₄ , (NH ₄ ) AuCl ₄ , NaAu (OAc) ₃ (OH), HAuCl ₄ , KAu (NO ₂ ) ₄ , AuCl ₃ , NaAuCl ₄ , KAu (OAc) ₃ (OH), HAu (NO ₃ J ₄ and Au (OAc) _3. It may be advisable to use the Au (OAc) ₃ or the KAuO ₂ by precipitation of the oxide / hydroxide from a

Goldsäure solution, washing and isolation of the precipitate and recording of the same in acetic acid or KOH fresh to each case.

Examples of preferred Pt precursor compounds are water-soluble Pt salts. According to a particularly preferred embodiment of the process according to the invention, the Pt precursor compound is selected from the group consisting of Pt (NH ₃ ) ₄ (OH) ₂ , Pt (NO ₃ J ₂ , K ₂ Pt (OAc) ₂ (OH) ₂ , Pt ( NH ₃ ) ₂ (NO ₂ ) ₂ , PtCl ₄ , H ₂ Pt (OH) ₆ , Na ₂ Pt (OH) ₆ , K ₂ Pt (OH) ₆ , K ₂ Pt (NO ₂ J ₄ , Na ₂ Pt ( NO ₂ J ₄ , Pt (OAc) ₂ , PtCl ₂ , K ₂ PtCl ₄ , H ₂ PtCl ₆ , (NH ₄ J ₂ PtCl ₄ , (NH ₃ ) ₄ PtCl ₂ , Pt (NH ₃ ) ₄ (HCO ₃ ) ₂ , Pt (NH ₃ J ₄ (HPO ₄ ), Pt (NH ₃ J ₄ (NOa) ₂ and Na ₂ PtCl ₄ ) Besides Pt (OAc) ₂ , other carboxylates of platinum may also be used, preferably the salts of the aliphatic ones Monocarboxylic acids having 3 to 5 carbon atoms, for example the propionate or butyrate salt Instead of NH ₃ , it is also possible to use the corresponding complex salts with ethylenediamine or ethanolamine as ligand.

According to a further preferred embodiment of the method according to the invention, Pt nitrite precursor compounds may also be preferred. Preferred Pt nitrite precursor compounds are, for example, those obtained by dissolving Pt (OAc) ₂ in a NaNO ₂ solution.

Examples of preferred Ag precursor compounds are water-soluble Ag salts. According to a particularly preferred embodiment of the method according to the invention, the Ag precursor compound is selected from the group consisting of Ag (NH ₂ ) ₂ (OH) ₂ , Ag (NO ₃ ), K ₂ Ag (OAc) (OH) ₂ , Ag (NH ₃ J ₂ (NO ₂ ), Ag (NO ₂ ), Ag-lactate, Ag-trifluoroacetate, Ag-salicylate, K ₂ Ag (NO ₂ J ₃ , Na ₂ Ag (NO ₂ J ₃ , Ag (OAc), ammoniacal AgCl ₂ solution, ammoniacal Ag ₂ CO ₃ solution, ammoniacal AgO solution and Na ₂ AgCl ₃ . In addition to Ag (OAc), it is also possible to use other carboxylates of silver, preferably the salts of the aliphatic monocarboxylic acids having 3 to 5 carbon atoms, for example the propionate or the butyrate salt.

According to a further preferred embodiment of the method according to the invention, Ag nitrite precursor compounds may also be preferred. Preferred Ag nitrite precursor compounds are, for example, those obtained by dissolving Ag (OAc) in a NaNO ₂ solution.

Suitable solvents for the transition metal precursor compound are pure solvents and solvent mixtures in which the selected metal compound is soluble and, after being applied to the catalyst support, can easily be removed therefrom by drying. Preferred solvent examples of metal acetates as precursor compounds are above all unsubstituted carboxylic acids, in particular acetic acid, ketones such as acetone, and for the metal chlorides especially water or dilute hydrochloric acid.

If the precursor compound is not sufficiently soluble in acetic acid, water or dilute hydrochloric acid or mixtures thereof, other solvents may alternatively or additionally be used in addition to the solvents mentioned. As other solvents here are preferably those solvents which are inert. Preferred solvents which are suitable as an additive to acetic acid are ketones, for example acetone or acetylacetone, furthermore ethers, for example tetrahydrofuran or dioxane,

Acetonitrile, Dirnethylformamid and solvents based on hydrocarbons such as benzene called. As preferred solvents or additives which can be used as

Suitable additions to water are ketones, for example acetone, or alcohols, for example ethanol or isopropanol or methoxyethanol, alkalis, such as aqueous KOH or NaOH, or organic acids, such as acetic acid, formic acid, citric acid, tartaric acid, malic acid, glyoxylic acid,

Glycolic acid, oxalic acid, pyruvic acid or lactic acid.

It is preferred if, in the context of the process according to the invention, the solvent used in the process is recovered, preferably by means of suitable cooler units, condensers and separators.

The present invention further relates to a coated catalyst comprising a porous catalyst support molding having an outer shell, in which at least one transition metal in particulate metallic form is contained, characterized in that the mass fraction of the transition metal on the catalyst more than 0.3 Mass .-% is preferably more than 0.5 mass% and preferably more than 0.8 mass%, and the average dispersion of

Transition metal particles greater than 20%, preferably greater than 23%, preferably greater than 25% and more preferably greater than 27%.

Transition metal shell catalysts having such high metal loadings with simultaneously high metal dispersion are obtainable by means of the process according to the invention. The transition metal dispersion is determined by the DIN standard for the respective metal. By contrast, the dispersion of the noble metals Pt, Pd and Rh is determined by CO chemisorption according to "Journal of Catalysis 120, 370 - 376 (1989)." The dispersion of Cu is determined by means of N ₂ O. According to a preferred embodiment of the coated catalyst according to the invention, the transition metal concentration deviates over a range of 90% of the shell thickness, with the outer shell and inner shell border each spaced apart by 5% of the shell thickness, from the average transition metal concentration of this zone by a maximum of + / - 20% off, preferably by a maximum of +/- 15% and preferably by a maximum of +/- 10%. As a result of the largely uniform distribution of the transition metal within the shell, a largely uniform activity of the catalyst according to the invention across the thickness of the shell is ensured since the concentration of transition metal varies only relatively little over the shell thickness. That is, the profile of transition metal concentration approximately describes a rectangular function across the shell thickness.

To further increase the selectivity of the catalyst according to the invention, it can be provided that, viewed across the thickness of the shell of the catalyst, the maximum

Concentration of transition metal in the area of the outer shell boundary and the concentration falls towards the inner shell boundary. In this case, it may be preferred if the concentration of transition metal steadily decreases in the direction of the inner shell boundary over a range of at least 25% of the shell thickness, preferably over a range of at least 40% of the shell thickness and preferably over a range of 30 to 80% shell thickness.

According to a further preferred embodiment of the catalyst according to the invention, the concentration of transition metal in the direction of the inner shell boundary falls to a concentration of 50 to 90% of the maximum concentration about steadily, preferably to a concentration of 70 to 90% of the maximum concentration.

It is preferred if the transition metal is selected from the group of noble metals.

Preferred catalysts according to the invention comprise two different metals in metallic form in the shell, the two metals being combinations of one of the following pairs: Pd and Ag; Pd and Au; Pd and Pt. Catalysts with a Pd / Au shell are particularly suitable for the production of VAM, those with a Pd / Pt shell are particularly suitable as an oxidation and hydrogenation catalyst and those with a Pd / Ag shell are particularly suitable for the selective hydrogenation of alkynes and Serve in olefin streams, so for example for the production of purified ethylene by selective hydrogenation of acetylene contained in the crude product.

With regard to providing a VAM shell catalyst having sufficient VAM activity, it is preferred that the

Catalyst as precious metals Pd and Au and the proportion of the catalyst in Pd is 0.6 to 2.5 mass%, preferably 0.7 to 2.3 mass% and preferably 0.8 to 2 mass% based on the mass of the loaded with noble metal catalyst support.

Moreover, in the aforementioned context, it is preferable that the Au / Pd atomic ratio of the catalyst is between 0 and 1.2, preferably between 0.1 and 1, preferably between 0.3 and 0.9, and more preferably between 0.4 and 0.8. In the case of a Pd / Au coated catalyst, this preferably contains as promoter at least one alkali metal compound, preferably a potassium, a sodium, a cesium or a rubidium compound, preferably a potassium compound. Suitable and particularly preferred potassium compounds include potassium acetate KOAc, potassium carbonate K ₂ CO ₃ , potassium hydrogen carbonate KHCO ₃ and potassium hydroxide KOH and all potassium compounds which convert to K-acetate KOAc under the particular reaction conditions of VAM synthesis. The potassium compound can be applied both before and after the reduction of the metal components to the metals Pd and Au on the catalyst support. According to a further preferred embodiment of the catalyst according to the invention, the catalyst comprises an alkali metal acetate, preferably potassium acetate. It is to ensure a sufficient

Promoter activity is particularly preferred when the content of the catalyst of alkali metal acetate is 0.1 to 0.7 mol / 1, preferably 0.3 to 0.5 mol / 1.

According to a further preferred embodiment of the Pd / Au catalyst according to the invention, the alkali metal / Pd atomic ratio is between 1 and 12, preferably between 2 and 10 and more preferably between 4 and 9. In this case, the alkali metal / Pd atomic ratio is preferably lower, depending smaller is the surface of the catalyst carrier.

It has been found that the smaller the surface area of the catalyst support, the higher the product selectivities of the Pd / Au catalyst according to the invention. In addition, the smaller the surface area of the catalyst support, the greater the thickness of the metal shell may be, without appreciable loss of product selectivity have to. According to a preferred embodiment of the catalyst according to the invention, the surface of the catalyst support therefore has a surface area of less than or equal to 160 m ² / g, preferably less than 140 m ² / g, more preferably less than 135 m ² / g, more preferably one of less than 120 m ² / g, more preferably one of less than 100 τn ² / g, even more preferably one of less than 80 m ² / g and particularly preferably less than 65 m ² / g.

According to a further preferred embodiment of the Pd / Au catalyst according to the invention, it may be provided that the catalyst support has a surface area of 160 to 40 m ² / g, preferably one of between 140 and 50 m ² / g, preferably one of between 135 and 50 m ² / g, more preferably from 120 to 50 m ² / g, more preferably from 100 to 50 m ² / g and most preferably from 100 to 60 m ² / g.

In view of a low pore diffusion limitation, according to a further preferred embodiment of the Pd / Au catalyst according to the invention it can be provided that the catalyst support has an average pore diameter of 8 to 50 nm, preferably one of 10 to 35 nm and preferably one of 11 to 30 nm ,

The acidity of the catalyst support can advantageously influence the activity of the catalyst according to the invention. According to a further preferred embodiment of the catalyst according to the invention, the catalyst support has an acidity of between 1 and 150 μval / g, preferably one of between 5 and 130 μval / g and particularly preferably one of between 10 and 100 μval / g. The acidity of the

The catalyst support is determined as follows: 1 g of the finely ground catalyst support is washed with 100 ml of water (with a pH blank) and extracted with stirring for 15 minutes. It is then titrated with 0.01 N NaOH solution at least until pH 7.0, wherein the titration is carried out stepwise; Namely, 1 ml of the NaOH solution is added dropwise to the extract (1 drop / second), then maintained for 2 minutes, the pH read, again added dropwise 1 ml of NaOH, etc. The

The blank value of the water used is determined and the acidity calculation is corrected accordingly.

The titration curve (ml 0.01 NaOH versus pH) is then plotted and the point of intersection of the titration curve at pH 7 is determined. The molar equivalents are calculated equiv in 10 ^"6 / g of support, resulting from the consumption of NaOH for the intersection at pH. 7

^ .. 10 * ml 0.01 N NaOH _. Total acid: = μval / g

1 carrier

Preferably, the Pd / Au catalyst is formed as a sphere. Accordingly, the catalyst support is formed as a sphere, preferably with a diameter of greater than 1.5 mm, preferably a diameter of greater than 3 mm and preferably with a diameter of 4 mm to 9 mm.

To increase the activity of the Pd / Au catalyst according to the invention, it may be provided that the catalyst support is doped with at least one oxide of a metal selected from the group consisting of Zr, Hf, Ti, Nb, Ta, W, Mg, Re, Y and Fe, preferably with ZrO ₂ , HfO ₂ or Fe ₂ O ₃ . It may be preferred if the proportion of the catalyst support of doping oxide is between 0 and 20% by mass, preferably 1.0 to 10% by mass and preferably 3 to 8% by mass, based on the mass of the catalyst support. According to an alternative embodiment of the catalyst according to the invention, this contains Pd and Ag as noble metals and, in order to ensure sufficient activity of the catalyst, preferably in the hydrogenation of acetylene, the proportion of catalyst in Pd is 0.01 to 1.0 mass%, preferably 0.02 to 0.8 mass% and preferably 0.03 to

0.7% by mass, based on the mass of the noble metal-loaded catalyst support.

Also in order to achieve sufficient activity of the catalyst in the hydrogenation of acetylene, the Ag / Pd atomic ratio of the catalyst is between 0 and 10, preferably between 1 and 5, it being preferred that the thickness of the noble metal shell is less than 60 microns ,

According to a further preferred embodiment of the Pd / Ag catalyst according to the invention, the catalyst support is designed as a sphere with a diameter of greater than 1.5 mm, preferably with a diameter of greater than 3 mm and preferably with a diameter of 2 to 4 mm, or as a cylindrical tablet with dimensions of up to 7x7 mm.

According to a further preferred embodiment of the Pd / Ag catalyst according to the invention, the catalyst support has a surface area of 1 to 50 m ² / g, preferably one of between 3 and 20 m ² / g. Furthermore, it may be preferred that the catalyst support has a surface area of less than or equal to 10 m ² / g, preferably one of less than 5 m ² / g and preferably less than 2 m ² / g.

A preferred oxidation or hydrogenation catalyst according to the invention contains as noble metals Pd and Pt, wherein the proportion of the catalyst in Pd to ensure a sufficient activity is 0.05 to 5 mass%, preferably 0.1 to 2.5 mass% and preferably 0.15 to 0.8 mass%, based on the mass of the noble metal-loaded catalyst support.

According to a preferred embodiment of the Pd / Pt catalyst according to the invention, the Pd / Pt atomic ratio of the catalyst is between 10 and 1, preferably between 8 and 5 and preferably between 7 and 4.

According to a further preferred embodiment of the Pd / Pt catalyst according to the invention, the catalyst support is designed as a cylinder, preferably with a diameter of 0.75 to 3 mm and with a length of 0.3 to 7 mm.

Further, it may be preferred that the catalyst support has a surface area of 50 to 400 m ² / g, preferably one of between 100 and 300 m ² / g.

It may also be preferred that the catalyst contains metallic Co, Ni and / or Cu in the shell as transition metal.

According to a further preferred embodiment of the catalyst according to the invention it is provided that the catalyst support is a carrier based on a

Silica, an alumina, an aluminosilicate, a zirconia, a titania, a niobium oxide or a natural layered silicate, preferably a calcined acid-treated bentonite. The term "on the basis" means that the catalyst support comprises one or more of the materials mentioned. As stated above, is subject to the

Catalyst support of the catalyst of the invention in the catalyst production of a certain mechanical stress. In addition, the catalyst according to the invention can be mechanically stressed during the filling of a reactor, which can lead to an undesirable development of dust and damage to the catalyst support, in particular its located in an outer region, catalytically active shell. In particular, in order to keep the abrasion of the catalyst according to the invention within reasonable limits, the catalyst support has a hardness greater than or equal to 20 N, preferably greater than or equal to 30 N, more preferably greater than or equal to 40 N, and most preferably one of greater than or equal to 50 N. The pressure hardness is determined as described above.

The catalyst according to the invention may preferably comprise as catalyst support a catalyst support based on a natural layered silicate, in particular an acid-treated calcined bentonite. The term "on the base" means that the

Catalyst support comprises the corresponding metal oxide. According to the invention, it is preferred if the proportion of the catalyst support to natural sheet silicate, in particular to acid-treated calcined bentonite, is greater than or equal to 50% by mass, preferably greater than or equal to 60% by mass, preferably greater than or equal to 70% by mass. more preferably greater than or equal to 80% by mass, more preferably greater than or equal to 90% by mass, and most preferably greater than or equal to 95% by mass, based on the mass of the catalyst support.

It could be stated that the product selectivity, in particular of the Pd / Au catalyst according to the invention, is the higher the greater the integral pore volume of the Pd / Au catalyst Catalyst carrier is. According to a further preferred

Thus, according to one embodiment of the catalyst according to the invention, the catalyst support has an integral pore volume to BJH greater than 0.30 ml / g, preferably greater than 0.35 ml / g and preferably greater than 0.40 ml / g.

Further, particularly with regard to the Pd / Au catalyst, it may be preferable that the catalyst carrier has an integral pore volume to BJH of between 0.25 and 0.7 ml / g, preferably between 0.3 and 0.6 ml / g and preferably from 0.35 to 0.5 ml / g.

The integral pore volume of the catalyst support is determined by the method of BJH by means of nitrogen adsorption. The surface of the catalyst support and its integral pore volume are determined by the BET method or by the BJH method. The BET surface area is determined by the BET method according to DIN 66131; a publication of the BET method can also be found in J. Am. Chem. Soc. 60, 309 (1938). To determine the surface area and the integral pore volume of the catalyst support or of the catalyst, the sample can be measured, for example, with a fully automatic nitrogen porosimeter from the company Micromeritics, type ASAP 2010, by means of which an adsorption and desorption isotherm is recorded.

To determine the surface area and the porosity of the catalyst support or of the catalyst according to the BET theory, the data are evaluated in accordance with DIN 66131. The pore volume is determined from the measurement data using the BJH method (E.P. Barret, L.G. Joiner, P.P. Haienda, J. Am.

Chem. Soc. (73/1951, 373)). This procedure also takes into account effects of capillary condensation. Pore volumes of certain pore size ranges are summed up Incremental pore volumes, which are obtained from the evaluation of the adsorption isotherm according to BJH. The integral pore volume according to the BJH method refers to pores with a diameter of 1.7 to 300 nm.

According to a further preferred embodiment of the catalyst according to the invention, it may be provided that the water absorbency of the catalyst support is 40 to 75%, preferably 50 to 70% calculated as weight increase by water absorption. The absorbency is determined by soaking 10 g of the carrier sample with deionized water for 30 minutes until no more gas bubbles escape from the carrier sample. Then, the excess water is decanted and the soaked sample is blotted with a cotton cloth to free the sample from adherent moisture. Then the water-loaded carrier is weighed and the absorbency calculated according to:

(Weight (g) - weight (g)) x 10 = water absorbency (%)

According to a further preferred embodiment, in particular of the Pd / Au catalyst, it may be preferred if at least 80% of the integral pore volume of the catalyst support is formed by mesopores and macropores, preferably at least 85% and preferably at least 90%. This counteracts a reduced activity of the catalyst according to the invention caused by diffusion limitation, especially in the case of shells with relatively large thicknesses. In this regard, the terms micropores, mesopores and macropores are understood to mean pores having a diameter of less than 2 nm, a diameter of 2 to 50 nm and a diameter of greater than 50 nm. The catalyst support of the catalyst according to the invention is formed as a shaped body. In this case, the catalyst support can basically take the form of any geometric body on which a corresponding shell can be applied. However, it is preferred if the catalyst support as a ball, cylinder (even with rounded faces),

Punching cylinder (also with rounded faces), trilobus, "capped tablet", tetralobus, ring, donut, star, cartwheel, "inverse" cartwheel, or as a strand, preferably as Rippstrang or star string, is formed.

The diameter or the length and thickness of the

Catalyst support of the catalyst according to the invention is preferably 2 to 9 mm, depending on the geometry of the reactor tube in which the catalyst is to be used.

The product selectivity of the catalyst according to the invention is generally higher, the smaller the thickness of the shell of the catalyst. According to a further preferred embodiment of the catalyst according to the invention, therefore, the shell of the catalyst has a thickness of less than 300 microns, preferably one of less than 200 microns, preferably one of less than 150 microns, more preferably one of less than 100 microns, and more preferably one smaller than 80 μm. The thickness of the shell can be optically measured in the case of supported metal catalysts usually by means of a microscope. The area in which the metals are deposited appears black, while the metal-free areas appear white. The boundary between metal-containing and - free areas is usually very sharp and visually clearly visible. If the aforementioned boundary line is not sharp and accordingly optically not clearly visible or the shell thickness can not be optically determined for other reasons, the thickness of the Shell of the thickness of a shell, measured from the outer surface of the catalyst support, in which 95% of the deposited on the support transition metal are contained.

It has also been found that, in the catalyst according to the invention, the shell can be formed with a relatively large thickness which effects a high activity of the catalyst without causing a significant reduction in the product selectivity of the catalyst according to the invention. For this purpose, catalyst supports having a relatively small surface area are to be used.

According to another preferred embodiment of the catalyst according to the invention, the shell of the catalyst therefore has a thickness of between 200 and 2000 μm, preferably one of between 250 and 1800 μm, preferably one of between 300 and 1500 μm and more preferably one of between 400 and 1200 microns.

The present invention further relates to the use of a device which is adapted to produce by means of a process gas circulation of catalyst support moldings, preferably a fluidized bed or a fluidized bed, preferably a fluidized bed in which the catalyst support moldings elliptical or toroidal, preferably toroidal , for carrying out the process according to the invention or in the preparation of a shell catalyst, in particular a shell catalyst according to the invention. It has been found that can be produced by means of such devices shell catalysts, which have the aforementioned advantageous properties.

According to a preferred embodiment of the use according to the invention, it is provided that the device has a process chamber with a bottom and a Side wall comprises, wherein the bottom of a plurality of superposed, overlapping, annular guide plates is constructed, between which annular slots are formed, is introduced via the process gas with a horizontal, radially outward movement component. As a result, the formation of a fluidized bed is made possible in a procedurally simple manner, in which the molded bodies rotate in a particularly uniformly elliptical or toroidal manner, which is accompanied by an increase in product quality.

In order to ensure a particularly uniform spraying of the moldings, for example with noble metal solutions, can be provided according to a further embodiment that centrally in the bottom of an annular gap nozzle is arranged, whose mouth is formed such that with the nozzle a

Spray cloud is sprayed, whose mirror plane is parallel to the ground plane.

Furthermore, it may be preferred that between the mouth of the annular die and the underlying soil

Outlet openings are provided for support gas to accomplish on the underside of the spray cloud a support cushion. The bottom-side air cushion keeps the bottom surface free of sprayed solution, that is, the entire sprayed solution is introduced into the fluidized bed of the moldings, so that no spray losses occur, which is particularly important in terms of expensive precious metal compounds.

According to a further preferred embodiment of the use according to the invention, the supporting gas is provided by the annular gap nozzle itself and / or by process gas in the device. These measures allow very variable embodiments of the accomplishment of the supporting gas to. It can be provided on the annular nozzle even outlet openings through which a portion of the spray gas exits to contribute to the formation of the supporting gas. Additionally or alternatively, portions of the process gas flowing through the bottom may be directed toward the underside of the spray plume, thereby contributing to the formation of the support gas.

According to a further embodiment of the invention, the annular gap nozzle has a conical head and the mouth extends along a circular conical cutting surface. This ensures that are fed through the cone, the vertically moving from top to bottom moldings evenly and selectively to the spray cloud, which is sprayed from the circular spray gap in the lower end of the cone.

According to a further embodiment of the use, a frusto-conical wall is provided in the region between the mouth and the bottom underneath, which preferably has passage openings for supporting gas. This measure has the advantage that the previously mentioned, harmonic

Deflection on the cone is maintained by the continuation of the truncated cone and can escape in this area supporting gas through the passage openings and provides the appropriate support at the bottom of the spray cloud.

In a further embodiment of the use of an annular slot for the passage of process gas is formed between the underside of the frusto-conical wall. This measure has the advantage that the transition of the moldings to the air cushion of the floor can be controlled particularly well and can be carried out directly in the area starting below the nozzle. In order to enter the spray cloud in the desired height in the fluidized bed, it is preferred that the position of the mouth of the nozzle is adjustable in height.

According to a further embodiment of the inventive use, guide elements are arranged between the annular guide plates, which impose a circumferential flow component on the passing process gas.

The following description of a preferred apparatus for carrying out the method according to the invention and the description of trajectories of Katalysatorträger- shaped bodies is used in conjunction with the drawings to explain the invention. Show it:

Fig. IA is a vertical sectional view of a preferred

Apparatus for carrying out the method according to the invention;

FIG. 1B shows an enlargement of the area framed in FIG. 1A and marked with the reference symbol IB; FIG.

Fig. 2A is a perspective sectional view of the preferred

Device in which the trajectories of two elliptically rotating catalyst carrier moldings are shown schematically;

Fig. 2B is a plan view of the preferred apparatus and trajectories of Fig. 2A;

Fig. 3A is a perspective sectional view of the preferred

Device in which the trajectory of a toroidally encircling catalyst support molding is shown schematically;

Fig. 3B is a plan view of the preferred device and the trajectory of FIG. 3A.

FIG. 1A shows a device, which is designated overall by the reference numeral 10, for carrying out the method according to the invention.

The apparatus 10 includes a container 20 having an upstanding cylindrical side wall 18 enclosing a process chamber 15.

The process chamber 15 has a bottom 16, below which an inflow chamber 30 is located.

The bottom 16 is composed of a total of seven annular, superimposed annular plates as baffles. The seven ring plates are placed one above the other so that an outermost ring plate 25 is a lowermost

Ring plate forms, on which then the other six inner ring plates, each of which is partially overlapping, placed below.

For clarity, only some of the seven ring plates are provided with reference numerals, for example, the two superimposed annular plate plates 26 and 27. By this overlapping and spacing between two annular plates in each case an annular slot 28 is formed by a nitrogen / hydrogen mixture 40 as a process gas with a predominantly horizontally directed component of movement can pass through the bottom 16 therethrough. In the central uppermost inner ring plate 29, an annular gap nozzle 50 is inserted in the central opening from below. The annular gap nozzle 50 has an orifice 55 which has a total of three orifice gaps 52, 53 and 54. All three orifice gaps 52, 53 and 54 are aligned so that they are approximately parallel to the bottom 16, ie horizontally with a

360 ° coverage angle. About the upper gap 52 and the lower gap 54, spray gas is squeezed, through the middle gap 53, the solution to be sprayed.

The annular gap nozzle 50 has a rod-shaped body 56 which extends downwards and contains the corresponding channels and supply lines 80. The annular gap nozzle 50 may, for example, be formed with a so-called rotary annular gap, in which walls of the channel through which the solution is sprayed rotate relative to one another in order to avoid clogging of the nozzle, so that over the 360 ° circumferential angle uniformly Gap 53 can be sprayed out.

The annular gap nozzle 50 has a conical head 57 above the mouth gap 52.

In the area below the mouth gap 54, a frusto-conical wall 58 is present, which has numerous openings 59. As can be seen in particular from FIG. 1B, the underside of the frustoconical wall 58 rests on the innermost ring plate 29 in such a way that a slot 60 is formed between the underside of the frustoconical wall 58 and the underlying, partially overlapping annular plate 29 through which process gas 40 can pass as a support gas. The outer ring 25 is spaced from the wall 18 so that process gas 40 can enter the process chamber 15 in the direction of the arrow labeled 61 with a vertical component and thereby greatly increase the process gas 40 entering the process chamber 15 through the slots 28 gives upward movement component.

In FIG. 1A and in detail in FIG. 1B, it is illustrated which conditions form in a run-in state in the device 10.

From the mouth gap 53 exits a spray cloud 70 whose horizontal mirror plane is parallel to the ground plane. Support gas passing through the openings 59 in the frusto-conical wall 58, which may be, for example, process gas, forms a spray cloud 70 on the underside of the spray cloud

Support gas flow 72 out. The process gas 40 passing through the numerous slots 28 forms a radial flow in the direction of the wall 18, from which the process gas 40 is deflected upwards, as shown by the arrows indicated by the reference numeral 74. From the deflected process gas 40, the moldings are guided in the wall 18 upwards. The process gas 40 and the catalyst carrier moldings to be treated then separate from one another, wherein the process gas 40 is discharged through outlets, while the moldings move radially inwardly according to the arrows 75 and vertically downward in the direction of the conical head 57 of the annular gap nozzle 50. There, the moldings are deflected, passed to the top of the spray cloud 70 and treated there with the sprayed medium. The sprayed moldings then move again in the direction of the wall 18 and thereby away from each other, since after leaving the spray cloud 70 at the annular orifice gap 53 the moldings a circumferentially larger space is available. In the area of the spray cloud 70, the moldings to be treated meet with liquid particles and are moved away from each other in the direction of movement of the wall 18, thereby being treated very evenly and harmoniously with the process gas 40 and thereby dried.

In FIG. 2A, two possible trajectories of two elliptically encircling catalyst carrier shaped bodies are shown by means of the curve courses indicated by the reference symbols 210 and 220. The elliptical trajectory 210 has relatively large changes in major and minor axis size as compared to an ideal elliptical trajectory. The elliptical trajectory 220, in contrast, has relatively small changes in the size of the major and minor axes and describes nearly an ideal elliptical trajectory without any circumferential (horizontal) motive component, as shown in FIG. 2B.

In FIG. 3A, a possible trajectory of a toroidally encircling catalyst carrier shaped body is shown by means of the curve course indicated by the reference numeral 310. The toroidal trajectory 310 describes a section of the surface of a nearly uniform torus whose vertical section is elliptical and whose horizontal section is annular. FIG. 3B shows the movement path 310 in plan view.

Claims

claims

A process for producing a coated catalyst comprising a porous catalyst support molded body having an outer shell in which at least one transition metal is contained in metallic form, the process being carried out using a device (10) arranged by means of a reducing process gas (40) to produce a circulation of Katalysatorträger- shaped bodies, comprising the steps of

a) feeding the device (10) with Katalysatorträger- moldings and generating a catalyst carrier-shaped body circulation by means of a reducing process gas acting (40);

c) converting the metal component of the transition metal precursor compound into the metallic form by reduction by means of the process gas (40);

d) drying the sprayed with the solution catalyst support moldings.

2. The method according to claim 1, characterized in that the process gas (40) is a gas mixture comprising an inert gas and a reductively acting component.

3. The method according to claim 2, characterized in that the inert gas is selected from the group consisting of nitrogen, carbon dioxide and the noble gases, preferably helium and argon, or a mixture of two or more of the aforementioned gases.

4. The method according to claim 2 or 3, characterized in that the reductive component is selected from the group consisting of ethylene, hydrogen, CO, NH ₃ , formaldehyde, methanol and hydrocarbons, or a mixture of two or more of the aforementioned compounds ,

A process for producing a coated catalyst comprising a porous catalyst support molded body having an outer shell in which at least one transition metal in metallic form is contained, the process being carried out by using a device (10) arranged to circulate of catalyst support moldings, preferably by means of a process gas (40), comprising the steps of

a) feeding the device (10) with Katalysatorträger- shaped bodies and generating a catalyst carrier-shaped body circulation, preferably by means of a process gas (40);

b) impregnating an outer shell of the catalyst support moldings with a transition metal precursor compound by spraying the circulating catalyst support moldings with a solution containing the transition metal precursor compound; c) transferring the metal component of the transition metal

d) drying the catalyst support shaped body.

6. The method according to claim 5, characterized in that the reducing agent is selected from the group consisting of hydrazine, K formate, Na formate, ammonium formate, formic acid, K-hypophosphite, hypophosphorous acid, H ₂ O ₂ and Na Hypophosphite.

7. The method according to claim 5 or 6, characterized in that the process gas (40) is selected from the group consisting of air, oxygen, nitrogen and the noble gases, preferably helium and argon.

8. The method according to any one of claims 1 to 7, characterized in that by means of the process gas (40), a fluidized bed or a fluidized bed of Katalysatorträger- molded bodies is generated, in which / which the shaped bodies are circulated.

9. The method according to claim 8, characterized in that by means of the process gas (40) a fluidized bed of catalyst support moldings is produced, in which the moldings elliptical or toroidal circulate, preferably toroidal.

10. The method according to any one of claims 1 to 9, characterized in that the device (10) has a process chamber

(15) having a bottom (16) and a side wall (18), wherein the process gas (40) through the bottom (16) of the process chamber (15), which preferably consists of a plurality of superimposed, overlapping annular guide plates (25, 26, 27, 29), between which annular slots (28) are formed, with a horizontal, radially outwardly directed component of motion is introduced into the process chamber (15) to produce a catalyst carrier-shaped body fluidized bed.

11. The method according to claim 10, characterized in that in the process chamber (15) introduced process gas (40) a circumferential flow component is imposed.

12. The method according to claim 11, characterized in that in the process chamber (15) introduced process gas (40), the circumferential flow component is imposed by means of guide elements, which are arranged between the annular guide plates (25, 26, 27, 29).

13. The method according to claim 11 or 12, characterized in that in the process chamber (15) introduced process gas (40), the circumferential

Flow component is imposed by passing through the ground

(16) the process chamber (15) additional process gas (61) is introduced with an obliquely upward movement component in the process chamber (15), preferably in the region of the side wall (18) of the process chamber (15).

14. The method according to any one of claims 10 to 13, characterized in that the spraying of the catalyst carrier Molded body is carried out by means of an annular gap nozzle (50) which sprays a spray cloud (70) which is parallel to the plane of the bottom (16).

15. The method according to claim 14, characterized in that the annular gap nozzle (50) is arranged centrally in the bottom (16) and the mouth (55) of the annular gap nozzle (50) is embedded in the circulating catalyst carrier molded body.

16. The method according to claim 14 or 15, characterized in that on the underside of the spray cloud (70) a Gasstützpolster (72) is accomplished.

17. The method according to any one of claims 1 to 16, characterized in that the catalyst support molding on the basis of a silica, alumina,

Zirconia, titanium oxide, niobium oxide or a natural layered silicate, especially a calcined acid-treated bentonite.

18. The method according to any one of claims 1 to 17, characterized in that the catalyst carrier molded body has a surface area of less than / equal to 160 m ² / g, preferably a smaller than 140 m ² / g, preferably a smaller than 135 m ² / g, more preferably one of less than 120 m ² / g, more preferably one of less than 100 m ² / g, even more preferably one of less than 80 m ² / g and particularly preferably less than 65 m ² /G.

19. The method according to any one of claims 1 to 18, characterized in that the catalyst support has a surface area of 160 to 40 m ² / g, preferably one of between 140 and 50 m ² / g, preferably one of between 135 and 50 m ² / g, more preferably one of between 120 and 50 m ² / g, more preferably one of between 100 and 50 m ² / g, and most preferably between 100 and 60 m ² / g.

20. The method according to any one of claims 1 to 19, characterized in that the catalyst support has a hardness of greater than or equal to 20 N, preferably one of greater than / equal to 30 N, more preferably one of greater than / equal to 40 N and most preferably one greater than or equal to 50 N.

21. The method according to any one of claims 1 to 20, characterized in that the process gas (40) is heated, preferably to a temperature of greater than or equal to 40 ⁰ C, preferably to a temperature of greater than or equal to 60 ⁰ C, more preferably on a temperature of greater than or equal to 70 ⁰ C, and most preferably to a temperature of 60 to 110 0C.

22. The method according to any one of claims 1 to 21, characterized in that the process gas (40) is enriched prior to introduction into the process chamber (15) with the solvent of the solution, preferably in a range of 10 to 50% of the saturation vapor pressure.

23. The method according to any one of claims 1 to 22, characterized in that the solution of the transition metal precursor compound as a transition metal precursor compound contains a noble metal compound.

24. The method according to claim 23, characterized in that the solution of the transition metal precursor compound as a transition metal precursor compound contains a Pd compound.

25. The method according to claim 23 or 24, characterized in that the solution of the transition metal precursor compound as a transition metal precursor compound contains an Au compound.

26. The method according to any one of claims 23 to 25, characterized in that the solution of the transition metal precursor compound as a transition metal precursor compound contains an Ag compound.

27. The method according to any one of claims 23 to 26, characterized in that the solution of the transition metal precursor compound as a transition metal precursor compound contains a Pt compound.

28. The method according to any one of claims 1 to 22, characterized in that the solution of the transition metal precursor compound as a transition metal precursor compound contains a Ni, Co and / or Cu compound.

29 coated catalyst, comprising a porous

Catalyst support molding having an outer shell, in which at least one transition metal in particulate metallic form is contained, characterized in that the mass fraction of the transition metal on the catalyst is more than 0.3 mass% and the average dispersion of the transition metal particles greater than 20% is, preferably greater than 25% and preferably greater than 27%.

A catalyst according to claim 29, characterized in that over a range of 90% of the shell thickness, with the outer and inner shell boundary area being spaced by 5% of the shell thickness from the average transition metal concentration of that area, the maximum +/- 20%, preferably by a maximum of +/- 15% and preferably by a maximum of +/- 10%.

31. Catalyst according to one of the preceding claims, characterized in that seen across the thickness of the shell of the catalyst away the maximum concentration of transition metal in the region of the outer shell boundary and the concentration decreases in the direction of the inner shell boundary.

32. Catalyst according to claim 31, characterized in that the concentration of transition metal in the direction of the inner shell boundary steadily decreases over a range of at least 25% of the shell thickness, preferably over a range of at least 40% of the shell thickness and preferably over a range of 30 up to 80% of the shell thickness.

33. A catalyst according to claim 32, characterized in that the concentration of transition metal in the direction of the inner shell boundary to a concentration of 50 to 90% of the maximum concentration steadily decreases, preferably to a concentration of 70 to 90% of the maximum concentration.

34. Catalyst according to one of the preceding claims, characterized in that the transition metal a

Precious metal is.

35. A catalyst according to claim 34, characterized in that the catalyst contains one, two or more different noble metals in the shell, in particular the

Precious metals of one of the following combinations: Pd and Ag; Pd and Au, - Pd and Pt.

36. Catalyst according to claim 34 or 35, characterized in that the catalyst contains Pd and Au as noble metals and the proportion of the catalyst in Pd is 0.6 to 2.5 mass%, preferably 0.7 to 2.3 mass .-% and preferably 0.8 to 2 Mass .-% based on the mass of the loaded with noble metal catalyst support.

37. A catalyst according to claim 36, characterized in that the Au / Pd atomic ratio of the catalyst is between 0 and 1.2, preferably between 0.1 and 1, preferably between 0.3 and 0.9 and particularly preferably between 0, 4 and 0.8.

38. A catalyst according to claim 36 or 37, characterized in that the catalyst comprises an alkali metal acetate, preferably potassium acetate.

39. A catalyst according to claim 38, characterized in that the content of the catalyst of alkali metal acetate is 0.1 to 0.7 mol / 1, preferably 0.3 to 0.5 mol / 1.

40. Catalyst according to claim 38 or 39, characterized in that the alkali metal / Pd atomic ratio is between 1 and 12, preferably between 2 and 10 and preferably between 4 and 9.

41. A catalyst according to any one of claims 36 to 40, characterized in that the catalyst support has a surface area of less than or equal to 160 m ² / g, preferably one of less than 140 m ² / g, preferably one of less than 135 ro ² / g, more preferably one of less than 120 m ² / g, more preferably one of less than 100 m ² / g, even more preferably one of less than 80 m ² / g and particularly preferably one of less than 65 m ² / g ,

42. A catalyst according to any one of claims 36 to 41, characterized in that the catalyst support has a surface area of 160 to 40 m ² / g, preferably one of between 140 and 50 m ² / g, preferably one of between 135 and 50 m ² / g, more preferably one of between 120 and 50 m ² / g, more preferably between 100 and 50 m ² / g and most preferably between 100 and 60 m ² / g.

43. Catalyst according to one of claims 36 to 42, characterized in that the catalyst support has a bulk density of more than 0.3 g / ml, preferably one of more than 0.35 g / ml and more preferably a bulk density of between 0, 35 and 0.6 g / ml.

44. Catalyst according to one of claims 36 to 43, characterized in that the catalyst support has a middle

Pore diameter of 8 to 50 nm, preferably one of 10 to 35 nm, and preferably one of 11 to 30 nm.

45. Catalyst according to one of claims 36 to 44, characterized in that the catalyst support has an acidity of between 1 and 150 μval / g, preferably one of between 5 and 130 μval / g and particularly preferably one of between 10 and 100 μval / G.

46. A catalyst according to any one of claims 36 to 45, characterized in that the catalyst support is formed as a ball with a diameter of greater than 1.5 mm, preferably with a diameter of greater than 3 mm and preferably with a diameter of greater than 4 mm.

47. Catalyst according to one of claims 36 to 46, characterized in that the catalyst support is doped with at least one oxide of a metal selected from the Group consisting of Zr, Hf, Ti, Nb, Ta, W, Mg, Re, Y and Fe, preferably with ZrO ₂ , HfO ₂ or Fe ₂ O ₃ .

48. A catalyst according to claim 47, characterized in that the proportion of the catalyst support of doping oxide is between 0 and 20 mass%, preferably 1.0 to 10 mass% and preferably 3 to 8 mass%.

49. A catalyst according to claim 34 or 35, characterized in that the catalyst contains as noble metals Pd and Ag and the proportion of the catalyst to Pd 0.01 to

1.0% by mass, preferably 0.02 to 0.8% by mass and preferably 0.03 to 0.7% by mass, based on the mass of the noble metal-laden catalyst support.

50. A catalyst according to claim 49, characterized in that the Ag / Pd atomic ratio of the catalyst is between 0 to 10, preferably between 1 and 5, wherein it is preferred that the thickness of the noble metal shell is less than 60 microns.

51. A catalyst according to claim 49 or 50, characterized in that the catalyst support is formed as a sphere with a diameter of greater than 1.5 mm, preferably with a diameter of greater than 3 mm and preferably with a diameter of 2 to 4 mm, or as a cylindrical tablet.

52. A catalyst according to any one of claims 49 to 51, characterized in that the catalyst support has a surface area of 1 to 50 m ² / g, preferably one of between 3 and 20 m ² / g.

53. A catalyst according to any one of claims 49 to 52, characterized in that the catalyst support has a surface area of less than or equal to 10 m ² / g, preferably one of less than 5 ra ² / g and preferably less than 2 m ² / G.

54. Catalyst according to claim 34 or 35, characterized in that the catalyst contains Pd and Pt as noble metals and the proportion of the catalyst in Pd is 0.05 to 5 mass%, preferably 0.1 to 2.5 mass. % and preferably 0.15 to 0.8 mass%, based on the mass of the catalyst support loaded with noble metal.

55. A catalyst according to claim 54, characterized in that the Pd / Pt atomic ratio of the catalyst is between 10 and 1, preferably between 8 and 5 and preferably between 7 and 4.

56. Catalyst according to claim 54 or 55, characterized in that the catalyst support is formed as a cylinder, preferably with a diameter of 0.75 to 3 mm and with a length of 0.3 to 7 mm, or as a ball with a diameter of 2 to 7 mm.

57. A catalyst according to any one of claims 54 to 56, characterized in that the catalyst support has a surface area of 50 to 400 m ² / g, preferably one of between 100 and 300 m ² / g.

58. A catalyst according to any one of claims 29 to 33, characterized in that the catalyst is a transition metal Co,

Contains Ni and / or Cu.

59. Catalyst according to one of the preceding claims, characterized in that the catalyst support molded body based on a silicon oxide, alumina, zirconia, titanium oxide, niobium oxide or natural phyllosilicate, in particular a calcined acid-treated bentonite is formed.

60. Catalyst according to one of the preceding claims, characterized in that the catalyst support has a hardness of greater than or equal to 20 N, preferably one of greater than or equal to 30 N, more preferably one of greater than or equal to 40 N and most preferably one of greater / equal to 50 N.

61. Catalyst according to one of the preceding claims, characterized in that the proportion of the catalyst support of natural layered silicate, in particular of calcined acid-treated bentonite, greater than or equal to 50% by mass, preferably greater than or equal to 60% by mass, preferably greater / is equal to 70% by mass, more preferably greater than or equal to 80% by mass, more preferably greater than or equal to 90% by mass, and most preferably greater than or equal to 95% by mass, based on the mass of the catalyst support.

62. Catalyst according to one of the preceding claims, characterized in that the catalyst support has an integral pore volume to BJH of greater than 0.30 ml / g, preferably one of greater than 0.35 ml / g and preferably one of greater than 0, 40 ml / g.

63. Catalyst according to one of the preceding claims, characterized in that the catalyst support has an integral pore volume to BJH of between 0.25 and 0.7 ml / g, preferably one of between 0.3 and 0.6 ml / g and preferably one of 0.3 to 0.5 ml / g.

64. Catalyst according to one of the preceding claims, characterized in that at least 80% of the integral pore volume of the catalyst support of mesopores and

Macropores are formed, preferably at least 85% and preferably at least 90%.

65. Catalyst according to one of the preceding claims, characterized in that the shell of the catalyst has a thickness of less than 300 microns, preferably one of less than 200 microns, preferably one of less than 150 microns, more preferably one of less than 100 microns and more preferably one smaller than 80 μm.

66. A catalyst according to any one of claims 25 to 64, characterized in that the shell of the catalyst has a thickness of between 200 and 2000 microns, preferably one of between 250 and 1800 microns, preferably one of between 300 and 1500 microns, and more preferably one from between 400 and 1200 μm.

67. Use of a device (10) which is set up by means of a process gas (40) to produce a circulation of catalyst support shaped bodies, preferably a fluidized bed or a fluidized bed, preferably a fluidized bed, in which the catalyst support shaped bodies rotate in an elliptical or toroidal manner, preferably toroidal, for performing a method according to any one of the preceding claims or in the preparation of a shell catalyst, in particular a shell catalyst according to any one of the preceding claims.

68. Use according to claim 67, characterized in that the device (10) comprises a process chamber (15) having a bottom (16) and a side wall (18), wherein the bottom (16) of a plurality of superimposed, overlapping each other , ring-shaped guide plates (25, 26, 27, 29) is constructed, between which annular slots (28) are formed, via the process gas (40) with a horizontal, radially outwardly directed component of motion is insertable.

69. Use according to claim 68, characterized in that centrally in the bottom (16) an annular gap nozzle (50) is arranged, the mouth (55) is designed such that with the nozzle (50) a spray cloud (70) can be sprayed, the runs parallel to the ground plane.

70. Use according to claim 69, characterized in that between the mouth (55) of the annular gap nozzle (50) and the underlying bottom (16) outlet openings (59) are provided for supporting gas to at the bottom of the spray cloud (70) a support cushion to accomplish.

71. The use according to claim 70, characterized in that the supporting gas can be provided by the annular gap nozzle (50) itself and / or by the process gas (40).

72. Use according to one of claims 69 to 71, characterized in that the annular gap nozzle (50) has a conical head (57), and in that the mouth (55) runs along a circular conic circumferential line.

73. Use according to one of claims 69 to 72, characterized in that in the region between the mouth (55) and the underlying bottom (16) is a frusto-conical wall (58) is arranged, which preferably has passage openings (59) for the supporting gas.

74. Use according to claim 73, characterized in that between the underside of the frusto-conical wall (58) and the underlying bottom (16) an annular slot (60) for the passage of process gas (40) is formed.

75. Use according to one of claims 69 to 74, characterized in that the position of the mouth (55) of the nozzle (50) is adjustable in height.

76. Use according to one of claims 68 to 75, characterized in that between the annular guide plates (25, 26, 27, 29) guide elements are arranged, which impose a circumferential flow component to the passing process gas.