Method for producing bulk catalyst shaped bodies for gas-phase oxidation of an alkene and / or an alcohol to form an a,b-unsaturated aldehyde and / or an a,b-unsaturated carboxylic acid

Abstract

The present invention relates to a method for producing bulk catalyst shaped bodies for gas-phase oxidation of an alkene and / or an alcohol to form an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein a precursor shaped body with a density of from 1.20 to 1.70 g / cm³ is produced by compression, the precursor shaped body is thermally treated and the weight loss during the thermal treatment is from 25 to 45 wt.%.

Description

Process for the preparation of unsupported catalyst bodies for the gas-phase oxidation of an alkyne and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid The present invention relates to a process for the production of unsupported catalyst bodies for the gas phase oxidation of an alkyne and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein by compaction a precursor body having a density of 1.20 to 1.70 g / cm 3 is produced, the precursor shaped body is thermally treated and the weight loss during the thermal treatment is from 25 to 45 wt.%. Furthermore, the present invention relates to the unsupported catalyst bodies obtainable according to the invention and their use for heterogeneously catalyzed partial gas phase oxidation on a fixed catalyst bed. US 2005 / 0065371 describes shaped catalyst bodies containing at least the elements molybdenum, bismuth and iron for gas phase oxidation. US 2006 / 0036111 discloses a gas-phase oxidation process for producing an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid. The loss on ignition during calcination must be within a defined range. WO 2010 / 000720 teaches a process for producing unsupported catalyst bodies. WO 2013 / 007736 discloses shaped catalyst bodies containing at least the elements molybdenum, bismuth, iron, and cobalt for gas-phase oxidation. The elements bismuth, iron, and cobalt must be present in a defined ratio. WO 2015 / 067659 describes hollow cylindrical shaped catalyst bodies with a defined geometry. The unsupported catalyst bodies exhibit high stability and high product selectivity in the gas-phase oxidation of propene to acrolein and acrylic acid. WO 2021 / 239483 discloses unsupported catalyst bodies with a defined cylindrical structure. These unsupported catalyst bodies enable high packing density and low pressure drop in the fixed catalyst bed. None of the above-mentioned patent applications attaches any importance to the pressure applied in the production of the precursor moldings or to the density of the precursor moldings. The object of the present invention was to provide an improved process for the preparation of unsupported catalysts for the gas-phase oxidation of an acrolein and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid. The catalysts should exhibit improved product selectivity and yield. The term "product of value" is understood to be the sum of acrolein and acrylic acid. The object of the invention is achieved by a process for the production of unsupported catalyst bodies for the gas phase oxidation of an alkyne and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein the unsupported catalyst bodies comprise at least the elements molybdenum, bismuth, iron, cobalt and optionally nickel, wherein a) an aqueous solution or aqueous suspension is produced from at least one source of the elemental constituents molybdenum, bismuth, iron, cobalt and optionally at least one source of the elemental constituent nickel, b) a powder P is produced by drying the aqueous solution or aqueous suspension obtained in a) and optionally comminuting, c) that powder P obtained in b), optionally with the addition of one or more auxiliaries and after uniform mixing and optionally compacting, is compacted to form precursor shaped bodies with a cylindrical structure, and d) the precursor shaped bodies obtained in c) are thermally treated to form the unsupported catalyst shaped bodies, characterized in that the pressure during the compaction in c) is selected such that the density of the precursor shaped bodies is from 1.70 to 2.30 g / cm 3wherein the density of the precursor shaped bodies is the quotient of the mass and the geometric volume, and the weight loss during the thermal treatment in d) is from 25 to 40 wt.%. The geometric volume is the macroscopic volume of the precursor body, including the pores. For the sake of completeness, it is emphasized that the through, essentially circular holes and any surface structures such as grooves, notches, or serrations are not part of the macroscopic volume. A cylindrical structure is a cylindrical body, preferably with at least one circular opening extending longitudinally. In the case of a continuous opening, this is located centrally (hollow cylinder). In the case of multiple through openings, these are evenly distributed across the cross-section of the cylindrical structure. A cylindrical structure with three through openings is described, for example, in WO 2021 / 239483. The thermal treatment includes an optional thermal pretreatment and the actual calcination. The pressure during compaction in c) is selected so that the density of the precursor moldings is preferably from 1.72 to 2.28 g / cm 3 , preferably from 1.74 to 2.26 g / cm 3 , particularly preferably from 1.76 to 2.24 g / cm 3 , most preferably from 1.78 to 2.22 g / cm 3 , most preferably from 1.80 to 2.20 g / cm 3 , amounts. The weight loss during the thermal treatment in d) is preferably from 26 to 39 wt.%, preferably from 27 to 38 wt.%, particularly preferably from 28 to 37 wt.%, very particularly preferably from 29 to 36 wt.%, most preferably from 30 to 35 wt.%. The weight loss during thermal treatment can be adjusted, for example, by using substances that decompose during thermal treatment. Suitable cylindrical structures include cylindrical bodies with a central circular through-opening (hollow cylinder) in the longitudinal direction and cylindrical bodies with three evenly spaced circular through-openings in the longitudinal direction. The latter cylindrical structures are described in WO 2021 / 239483. The shortest distance between the outer wall of the cylindrical body and the next through opening is preferably from 0.75 to 2.5 mm, preferably from 0.8 to 2.0 mm, particularly preferably from 1.0 to 1.8 mm, most preferably from 1.2 to 1.7 mm, most preferably from 1.3 to 1.6 mm. In the case of a hollow cylinder, the shortest distance between the outer wall of the cylindrical body and the nearest through opening corresponds to the wall thickness of the hollow cylinder. The molybdenum content of the unsupported catalyst bodies, calculated as MoOs, is preferably from 45 to 75% by weight, particularly preferably from 50 to 70% by weight, very particularly preferably from 55 to 65% by weight. The bismuth content of the unsupported catalyst bodies, calculated as Bi2Ö3, is from 1 to 20 wt.%, particularly preferably from 2 to 15 wt.%, very particularly preferably from 3 to 10 wt.%. The iron content of the unsupported catalyst bodies, calculated as Fe2O3, is from 2 to 12 wt.%, particularly preferably from 3 to 11 wt.%, very particularly preferably from 4 to 10 wt.%. The content of cobalt and nickel in the unsupported catalyst bodies, calculated as CoO and NiO, is in total from 9 to 30 wt.%, particularly preferably from 12 to 27 wt.%, very particularly preferably from 15 to 24 wt.%. The solid catalyst bodies may additionally contain the elements potassium and / or silicon. A further subject of the present invention are the unsupported catalyst bodies produced according to the process according to the invention having a cylindrical structure for the gas phase oxidation of an aldehyde and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein the unsupported catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, characterized in that the density of the unsupported catalyst body is from 1.20 to 1.70 g / cm 3 where the density of the unsupported catalyst body is the quotient of the mass and the geometric volume, the total pore volume of the unsupported catalyst body is from 0.33 to 0.60 cm 3 / g and the pore volume of the full catalyst body in the range of 0.1 to 1 pm is from 85 to 99% of the total pore volume, wherein the total pore volume and the pore volume in the range of 0.1 to 1 pm are determined by mercury porosimetry. The geometric volume is the macroscopic volume of the solid catalyst body, including the pores. For the sake of completeness, it should be emphasized that the through, essentially circular holes and any surface structures such as grooves, notches, or serrations are not part of the macroscopic volume. The density of the unsupported catalyst body is preferably from 1.22 to 1.68 g / cm 3 , preferably from 1.24 to 1.66 g / cm 3 , particularly preferably from 1.26 to 1.64 g / cm 3 , most preferably from 1.28 to 1.62 g / cm 3 , most preferably from 1.30 to 1.60 g / cm 3 , The total pore volume of the solid catalyst body is preferably from 0.34 to 0.58 cm 3 / g, preferably from 0.35 to 0.56 cm 3 / g, particularly preferably from 0.36 to 0.54 cm 3 / g, most preferably from 0.37 to 0.52 cm 3 / g, most preferably from 0.38 to 0.50 cm 3 / G, The pore volume of the unsupported catalyst shaped body in the range from 0.1 to 1 pm is preferably from 86 to 98%, preferably from 87 to 97%, particularly preferably from 88 to 96%, very particularly preferably from 89 to 95% of the total pore volume. Preferred unsupported catalyst bodies are multielement oxides of the general formula I Moi2BiaFebCOcNidXeYfZgO n (I) with X = K, Cs and / or Rb Y = Ca, Sr, Ba, Li, Na, Cr, W, Mn, Cu, Zn, Ga, P, B, As, Sn, Sb, Te, Nb, Ta, Pb, Ce and / or La Z = Si, Al, Ti, Zr and / or Mg a = 0.2 to 2 b = 1 to 4 c = 3 to 9 d = 0 to 4 c + d = 4 to 9.5 e = 0.01 to 0.5 f = 0 to 10 g = 0 to 10 n = a number determined by the valence and frequency of the elements other than oxygen in the general formula I. The present invention further relates to processes for preparing an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein an alkene and / or an alcohol, in particular propene, is passed with molecular oxygen over a fixed catalyst bed comprising a bed of unsupported catalyst bodies according to the invention, and fixed bed reactors containing a bed of unsupported catalyst bodies according to the invention. The present invention is based on the finding that the pressure applied during the production of the precursor shaped bodies and the weight loss occurring during the thermal treatment have a significant influence on the desired product selectivity and the desired product yield. The production of the full catalyst bodies is described below: The unsupported catalyst bodies obtainable according to the invention are typically formed into geometric shapes, calcined, and used to catalyze the respective heterogeneously catalyzed gas-phase partial oxidation (in particular that of propene to acrolein). In principle, the desired geometry of the unsupported catalysts is not subject to any restrictions. In principle, unsupported catalyst bodies can be produced in a simple manner by producing a dry mixture from suitable sources of their elemental constituents (in particular those other than oxygen) which is as intimate as possible, preferably finely divided, and composed according to the respective stoichiometry of the unsupported catalyst bodies to be produced, and calcining this mixture at temperatures of 350 to 650°C after prior shaping to precursor bodies, which optionally takes place with the use of shaping aids.Calcination can take place under an inert gas or an oxidative atmosphere, such as air (or another mixture of inert gas and molecular oxygen, which may also contain reducing components in comparatively smaller proportions), as well as under a reducing atmosphere (e.g., a mixture of inert gas, NH3, CO, and / or H2, which may also contain oxidizing components in comparatively smaller proportions), or under vacuum. The calcination time can range from a few minutes to a few days and is usually shorter at elevated calcination temperatures. As sources for the elemental constituents of the unsupported catalyst bodies (i.e. as starting compounds which contain at least one elemental constituent (at least one element contained in the unsupported catalyst body) in a chemically bound manner) such Compounds which are already oxides (which are generally in the solid state under standard conditions (1 atm, 0°C)) (for example metal oxides) and / or compounds which can be converted into oxides (which are generally in the solid state under standard conditions) by heating (thermal treatment at elevated temperature), at least in the presence of gaseous oxygen and / or gaseous (for example molecular) oxygen-releasing components. In principle, the oxygen source can be a component of the mixture to be calcined, for example in the form of a peroxide. In general, a starting compound can be the source of several elemental constituents of the shaped catalyst bodies. In addition to the oxides, such starting compounds (sources) are mainly halides, nitrates, formates, acetates, oxalates, citrates, carbonates, ammine complexes, ammonium salts and / or hydroxides as well as hydrates of the aforementioned salts. Compounds such as NH4OH, (NH4)2CO3, NH4NO3, NH4CHO2, CH3COOH, NH4CH3CO2, and / or ammonium oxalate, which decompose and / or decompose essentially completely into gaseous compounds (e.g., ammonia, CO2, CO, H2O, nitrogen oxides) during subsequent calcination, can also be incorporated into the intimate dry mixture. Other suitable substances that decompose during calcination include organic materials such as stearic acid, malonic acid, ammonium salts of the aforementioned acids, starches (e.g., potato starch, corn starch), ground nutshells, and finely divided plastic flour (e.g., polyethylene, polypropylene, etc.). A formation (release) of gaseous compounds during the thermal treatment outlined is normally also present when the element sources with which the most intimate and preferably finely divided dry mixture is produced are partly of an organic nature (for example in the case of acetates, formates, oxalates and / or citrates) or contain hydroxide ions, carbonate ions, hydrogen carbonate ions, ammonium ions, halide ions, hydrogen phosphate ions and / or nitrate ions, which normally decompose during calcination. The intimate mixing of the starting compounds (sources) for the production of unsupported catalyst bodies can be carried out in dry or wet form. If the mixing is carried out in dry form, the starting compounds (sources) are preferably used as finely divided powders and, after mixing and compaction into the geometric precursor body, are subjected to calcination. According to the invention, however, the intimate mixing of the (element) sources preferably takes place in wet form. The starting compounds are mixed together in the form of solutions and / or suspensions, and the resulting wet (preferably aqueous) mixture M is then dried to form an intimate dry mixture. Water or an aqueous solution is preferably used as the solvent and / or suspending agent, with the resulting wet mixture M being an aqueous mixture M. Particularly intimate dry mixtures are obtained in the mixing process described above when the starting material is exclusively from dissolved sources and / or colloidally dissolved sources of the elemental constituents. As already mentioned, a starting compound can be a source of only one or several elemental constituents. Accordingly, a solution or colloidal solution listed above can contain only one or several elemental constituents of the relevant unsupported catalyst body to be produced in dissolved form. As already mentioned, the preferred solvent is water. The resulting aqueous mixtures are preferably dried by spray drying. When this document refers to a solution of a source (starting compound, starting substance) in a solvent (especially water), the term "solution" is used in the sense of a molecular or ionic solution. This means that the largest geometric unit of the dissolved starting substance (source) in the solution necessarily has "molecular" dimensions, and the solution appears "optically empty." In contrast, colloidal solutions represent a bridge between true (molecular and / or ionic) solutions and suspensions. These colloidally dispersed systems contain smaller clusters of molecules or atoms, which, however, are neither visible to the naked eye nor to a microscope. The colloidal solution appears optically completely clear (although often colored), since the particles it contains have a diameter of only 1 to 250 nm (preferably up to 150 nm and especially preferably up to 100 nm). Due to their small size, separation of the colloidally dissolved particles by conventional filtration is not possible. However, they can be separated from their "solvent" by ultrafiltration using membranes of plant, animal, or artificial origin (e.g., parchment, pig bladder, or cellophane). In contrast to "optically empty" true (molecular and / or ionic) solutions, a light beam cannot pass through a colloidal solution without deflection. The light beam is scattered and deflected by the colloidally dissolved particles. To keep colloidal solutions stable and prevent further particle agglomeration, they often contain wetting and dispersing agents, as well as other additives. While elements other than silicon (elemental constituents) of a shaped unsupported catalyst body are preferably introduced from sources present in the form of a solution (particularly preferably dissolved in an aqueous solution) to prepare the wet (preferably aqueous) mixture M, the element silicon is preferably introduced in the form of a silica sol to prepare the wet (preferably aqueous) mixture M. Silica sols are aqueous colloidal solutions of nearly spherical polysilicic acid particles. The diameter of the particles is in the colloidal range and, depending on the type, ranges from 5 to 75 nm. The particles are pore-free. They have a core of SiO2, which is hydroxylated on its surface. The spherical individual particles are not cross-linked. For reasons of stability, a portion of the hydroxyl groups in silica sols is often neutralized with alkali hydroxide and / or ammonium hydroxide. This means that the counterions are sometimes not protons, but alkali ions (e.g., Na + ) and / or NH4 + -cations. The SiO2 content of silica sols suitable for producing a wet (preferably aqueous) mixture M can, for example, be 30% to 60% of the weight of the silica sol. Silica sols are normally water-soluble and contain no sedimentable components. They can often be stored for years without sedimentation. Particularly suitable silicon sources are the LUDOX® silica sols from Grace GmbH & KG, In der Hollerecke 1, D-67545 Worms. Their particles are discrete, uniform spheres of silicon dioxide without an internal surface or detectable crystallinity. Their majority is dispersed in an alkaline medium, which reacts with the hydroxylated surface, producing repulsive negative charges. The particle diameters of suitable silica sols can be very narrow (essentially monodisperse) or very wide (polydisperse). A particularly suitable silica sol for the purposes of the invention (for producing a wet (preferably aqueous) mixture M) is the LUDOX TM50 silica sol from Grace. The LUDOX TM50 silica sol has a largely monodisperse (d = 22 nm) particle diameter distribution. Its pH (1 atm, 25°C) is 9.0. The alkali ion that replaces a portion of the hydroxyl protons is Na +The SiO2 content of LUDOX TM50 is 50% of the weight of this hydrogel. The specific surface area of ​​the colloidally dissolved SiO2 particles in LUDOX TM50 is 140 m 2 / g. The mass density (1 atm, 25°C) of LUDOX TM50 is 1.40 g / cm 3 The titratable alkali content of LUDOX TM50 (calculated as Na2O) is 0.21 wt% (based on the weight of the silica sol). The dynamic viscosity of LUDOX TM50 is 40 mPas (1 atm, 25°C). The Cl' content (calculated as NaCl) of LUDOX TM50 is 0.03 wt.% and the SO4 content 2 'of LUDOX TM50 (calculated as Na2SO4) is 0.08 wt.% (each based on the weight of LUDOX TM50). Of course, in a solution to be used to produce a wet (in particular aqueous) mixture M, at least one element source can be molecularly and / or ionically dissolved and one or more than one other element source can be colloidally dissolved side by side. A favorable source of Mo is ammonium heptamolybdate tetrahydrate. This is primarily due to its excellent solubility in water. According to Ullmann's Encyclopedia of Industrial Chemistry, Volume 22, 2003, WILEY-VCH, pages 320 / 321, a solution of ammonium molybdate tetrahydrate in water at 25°C and 1 atm has a saturation solubility of 30 wt% (calculated as an anhydrous salt). Due to manufacturing processes, ammonium molybdate tetrahydrate may be contaminated in small amounts (usually ppm) with water-insoluble isopolymolybdate (due to process parameters not being strictly adhered to during its production). Dissolving contaminated ammonium heptamolybdate tetrahydrate in water produces an aqueous solution that exhibits a certain turbidity due to the small amounts of finely divided isopolymolybdate present in undissolved form.The applicant's own investigations have shown that even ammonium molybdate tetrahydrate contaminated with isopolymolybdate, the solution of which in water (determined as described in WO 2016 / 147324) has a turbidity of 20 NTU, or of 50 NTU, or of 70 NTU, or of 100 NTU, or of 150 NTU, or of 200 NTU, or of 250 NTU, or of 300 NTU, is suitable for producing unsupported catalyst bodies according to the invention without noticeably impairing their performance when used as catalysts for the heterogeneously catalyzed partial gas phase oxidation of propene to acrolein as the main product and acrolein as the by-product. Other suitable Mo sources include ammonium orthomolybdate ((NH4)2MoO4), ammonium dimolybdate ((NH4)2Mo2O7), ammonium tetramolybdate dihydrate ((NH4)2Mo4Oi3 x 2 H2O), and ammonium decamolybdate dihydrate ((NH4)4MoIOOS2 x 2 H2O). However, molybdenum trioxide can also be used in principle. The preferred source of alkali metals in the production of shaped unsupported catalyst bodies is their hydroxides. However, the nitrates of these elements and the hydrates of these nitrates can also be considered as such sources. This means that the preferred potassium source is KOH, but KNO3 or its hydrate can also be used as a potassium source. Bismuth salts are preferably used as a source of Bi, which contains Bi as Bi 3+ Examples of such salts include bismuth(III) oxide, bismuth(III) oxide nitrate (bismuth subnitrate), bismuth(III) halide (e.g. fluoride, chloride, bromide, iodide) and especially bismuth(III) nitrate pentahydrate. Of course, as a Bi source A solution of elemental Bi in aqueous nitric acid can also be used, in which the Bi is present as Bi 3+ In the case of the (inventively preferred) use of an aqueous solution of Bi 3+-Nitrate or its hydrate as a source (such a solution can also be produced by dissolving elemental Bi in aqueous nitric acid), it is advantageous according to the invention if its pH value (1 atm, 25°C) is low, since this prevents undesirable formation of Bi 3+ containing precipitates in the aqueous solution. This pH is preferably < 1, particularly preferably < 0.5. However, this pH is generally > -2, mostly > 0. Such an aqueous solution is expediently nitric acid. This means that its low pH is caused by excess nitric acid (in this case, the molar ratio (HNOS-) / (nßj3+) depends on the molar amount of NO3' (n N os-) to the molar amount of Bi3 contained in the aqueous solution + (nßj3+) > 3). Preferred Fe sources are salts of Fe 3+, among which the various iron(III) nitrate hydrates are particularly preferred (see, for example, DE 10 2007 003076 A1). According to the invention, iron(III) nitrate nonahydrate is particularly preferably used as the Fe source for the aforementioned purpose. Of course, salts of Fe 2+ be used as a Fe source. Advantageously, for the production of the unsupported catalyst bodies, based on the total molar amount of Fe contained therein, at least 50 mol%, better at least 75 mol% and preferably at least 95 mol% or 100 mol% is introduced in the form of an Fe source which contains the Fe as Fe 3+ Fe sources can also be used for this purpose, which contain both Fe 3+ as well as Fe 3+ have. Particularly suitable Co sources are its salts, which contain the Co as Co 2+ and / or Co 3+Examples of such sources include cobalt(II) nitrate hexahydrate, Co3O4, CoO, cobalt(II) formate, and cobalt(II) nitrate. The first of these sources is particularly preferred for the aforementioned purpose. Of course, a solution of elemental Co in aqueous nitric acid can also be used as a Co source, in which the Co is present as Co 2+ is present. In the case of the elemental constituent Ni, Ni 2+ Salts are used. These include, in particular, nickel(II) carbonate, nickel(II) sulfate, nickel(II) oxide, nickel(II) acetate, nickel(II) formate, nickel(II) hydroxide, nickel(II) oxalate, and nickel(II) nitrate, as well as the respective hydrates of these salts. Hydrates of nickel(II) nitrate (for example, its hexahydrate) are particularly preferred as Ni sources. To improve the solubility of, for example, salts of Fe, Co and / or Ni in an aqueous medium, ammonia (also as its aqueous solution) and / or nitric acid (in particular as its aqueous solution) can be added to the respective solution as required. In principle, the preparation of a wet (e.g. aqueous) mixture M can be carried out in a wide variety of gas atmospheres (e.g. air, argon, nitrogen, water vapor and / or carbon dioxide). According to the invention, the preparation of a wet (e.g. aqueous) mixture M is preferably carried out in air (advantageously, the aqueous mixture M is saturated with air). This applies in particular when salts of Co 2+ and salts of Fe 2+ used. Especially when these salts are nitrates and / or their hydrates. As already mentioned, the wet mixture M according to the invention is preferably an aqueous mixture M, which is particularly advantageously prepared in the following manner. An aqueous solution A is prepared from at least one source of the element Fe, from at least one source of the element Bi, from at least one source of the element Co and optionally at least one source of the element Ni, the pH of which is < 3, preferably < 2, particularly preferably < 1 and very particularly preferably < 0 (pH values ​​of aqueous solutions in this document generally refer (unless explicitly stated otherwise) to a measurement with a glass electrode designed as a combination measuring chain at 1 atm and at the temperature at which the respective aqueous solution is prepared; the calibration of the combination measuring chain required in this regard is carried out under the same conditions using aqueous buffer solutions whose pH is known under these conditions and is close to the desired measured value);The Mettler Toledo pH electrode Inpro 4260 / 425 / Pt 100, which is a combination electrode with an integrated Pt 100 temperature sensor for automatic temperature compensation, is particularly suitable for determining such pH values. As a rule, the pH of the aqueous solution A is not less than -2 and is particularly advantageously in the range -1 to 0. Preferably, the aqueous solution A is an aqueous solution of the nitrates or nitrate hydrates of the aforementioned elements. Particularly preferably, the aqueous solution A is an aqueous solution of these nitrates or nitrate hydrates in aqueous nitric acid. Solutions of the relevant elements in aqueous nitric acid are also suitable as element sources, particularly for preparing such a solution. An aqueous solution B is prepared from at least one source of the element Mo and optionally at least one of the sources of an alkali metal. The pH of the aqueous solution B is advantageously (at 1 atm and the temperature at which the solution B is prepared) <7. The pH of the aqueous solution B is particularly preferably <6.5 and very particularly advantageously <6. As a rule, the pH of the aqueous solution B will be >3. Favorable solutions B to be used according to the invention have a pH of 4 to 6. According to the invention, the element hydroxide of an alkali metal (for example, KOH) is preferably used as the source for preparing the aqueous solution B. The preferred Mo source for preparing an aqueous solution B is ammonium heptamolybdate tetrahydrate ((NH4)6Mo?O24 x 4 H2O), which is completely soluble in water at 25°C (1 atm) up to saturation solubility (30 wt. %, calculated anhydrous). According to the invention, the total content of the metal constituents Bi, Fe, Co, Ni, etc. in the aqueous solution A is expediently 5 to 20 wt.%, advantageously 10 to 15 wt.%, based on the total amount of the aqueous solution A. According to the invention, the total Mo content of the aqueous solution B is expediently, based on the total amount of the aqueous solution B, 2 to 25 wt.%, advantageously 3 to 20 wt.% and particularly advantageously 5 to 15 wt.%. Subsequently, the aqueous solution A and the aqueous solution B are suitably mixed together. The procedure is advantageously such that the aqueous solution A is continuously stirred into the aqueous solution B. The aqueous solution B is advantageously stirred intensively. According to the invention, the total content of the metal constituents Bi, Fe, Co, Ni, Mo, etc. in the resulting aqueous mixture of aqueous solution A and aqueous solution B is expediently 3 to 20 wt.%, advantageously 5 to 15 wt.%, based on the total amount of the aqueous mixture. The temperature of the initially introduced aqueous solution B and the temperature during stirring in of the aqueous solution A, as well as the temperature of the aqueous solution A itself, is advantageously (preferably throughout the entire mixing process) < 80°C and > 0°C. Preferably, the aforementioned temperatures are < 75°C and > 30°C, and particularly preferably they are < 70°C and > 50°C, or < 65°C and > 55°C. Advantageously, aqueous solutions A and B, as well as the aqueous mixture resulting from stirring aqueous solution A into aqueous solution B, have the same temperature. This is ideally 60°C. Preferably, the temperatures of aqueous solution A, aqueous solution B, and the resulting aqueous mixtures are constant throughout the described stirring process. For this purpose, thermostatting can be achieved, for example, using a water bath. The working pressure when stirring aqueous solution A into aqueous solution B is advantageously 1 atm (1.01 bar). Preferably, the aqueous solution A is stirred into the initially introduced aqueous solution B within a period of 5 to 60 minutes, particularly preferably within a period of 10 to 30 minutes, and very particularly preferably within a period of 15 to 25 minutes. The resulting aqueous mixture is subsequently stirred, preferably while maintaining the stirring temperature, for 5 to 60 minutes, preferably 10 to 30 minutes, and particularly advantageously 15 to 25 minutes. The pH value of the aqueous mixture of aqueous solution A and aqueous solution B is preferably < 3, better < 2. As a rule, it is > 0. If the unsupported catalyst body contains the elemental constituent Si, then according to the invention, aqueous silica sol is preferably stirred into the aqueous mixture of aqueous solution A and aqueous solution B as a source thereof, it being advantageous to add water to this aqueous mixture prior to this stirring in. Advantageously, both the aqueous silica sol and the water can be added all at once. Both the temperature of the water and the temperature of the aqueous silica sol advantageously correspond to the temperature of the aqueous mixture of aqueous solution A and aqueous solution B. Finally, stirring is advantageously continued for up to 30 minutes. During the stirring, the aforementioned temperature is advantageously maintained. The SiO2 content of the added aqueous silica sol can be 15 to 60% by weight, or 20 to 60% by weight, or 30 to 60% by weight, preferably 40 to 60% by weight.-% and particularly preferably 45 to 55 wt.% (in each case based on its total weight). Instead of placing aqueous solution B in a thermostatically controlled stirred vessel and then adding aqueous solution A while stirring, both aqueous solution B and aqueous solution A can be continuously added to the stirred vessel (for example, through a 3-way T-mixer). In principle, aqueous solution B can also be continuously stirred into an initial aqueous solution A. However, this procedure is less preferred. As a rule, the aqueous mixture M obtainable as described is an aqueous suspension (preferably the ratios V described as advantageous are also present in the aqueous mixture M (total molar amount of NH3 + NH4 contained +to the molar amount of Mo contained therein); moreover, the pH of the aqueous mixture M obtainable as described is advantageously <3, generally 0 to 2). Aqueous mixtures M obtainable as described advantageously contain no more or less than 60 mol% of the total molar amount of Co and / or Ni contained therein in dissolved form in the aqueous medium (at the temperature and working pressure at which the aqueous mixture M was produced). Preferably, the above-mentioned proportion AT of the total molar amount of Co and / or Ni contained in the aqueous mixture M, which is dissolved in the aqueous medium of the aqueous mixture M, is <50 mol% and particularly preferably <40 mol%, or <30 mol% or <20 mol%. The total content of Bi, Fe, Mo, etc. in the aqueous mixture M to be dried (preferably spray-dried) is expediently according to the invention, based on the Amount of the aqueous mixture M: 3 to 20 wt.%, advantageously 5 to 15 wt.%. Generally, AT is > 10 mol% or < 15 mol%. According to the invention, the aqueous mixture M is preferably converted into a finely divided, intimate dry mixture by spray-drying the aqueous mixture M (the drying of the aqueous mixture M preferably takes place as close as possible to its preparation). This means that the aqueous mixture M is first divided into finely divided droplets (sprayed) in a spray dryer and then dried in the spray dryer. Spray-drying preferably takes place in a hot air stream. In principle, however, other hot gases can also be used for the aforementioned spray-drying (e.g., nitrogen or air diluted with nitrogen, as well as other inert gases). Spray drying can occur either in cocurrent or countercurrent flow of the droplets to the hot gas. Typical gas inlet temperatures range from 250 to 450°C, preferably 270 to 370°C. Typical gas outlet temperatures range from 100 to 160°C. Spray drying preferably occurs in cocurrent flow of the droplets to the hot gas. The average particle diameter of the resulting spray powder is typically 10 to 100 pm, preferably 15 to 60 pm and particularly preferably 25 to 50 pm (the diameter is determined according to ISO 13320-1 by means of light scattering on spray powder dispersed in air (dispersion air pressure 1.0 bar). In general, references to a standard in this document refer to the edition of the standard that was in force on the priority date of this patent application and whose publication date (issue date) has the smallest time difference to the priority date of this patent application. The vibratory mass density (25°C, 1 atm) of the spray powder is typically 500 to 1300 g / l and preferably 700 to 1100 g / l. The loss on ignition of the spray powder (3 h at 600°C (powder temperature) under standing, excess air) is typically 20 to 40 wt.%, preferably 25 to 35 wt.% of its initial weight. Until further processing, the spray powder can be stored temporarily, preferably in hermetically sealed containers (e.g., plastic drums). The storage temperature should not exceed 70°C and is preferably < 50°C. As a general rule, the storage temperature should not fall below 10°C. Since the spray powder is generally hygroscopic, extended contact with humid air should be avoided. Contact with humid air can impair the handling properties of the spray powder (e.g., its flowability) and ultimately reduce the catalytic activity of the solid catalyst bodies produced with it. Of course, the aqueous mixture M can also be dried by other drying methods, such as conventional evaporation (preferably under reduced pressure; the drying temperature will generally not exceed 150 °C). In principle, the drying of an aqueous mixture M can also be achieved by freeze-drying or Spin-Flash® drying. The spray powder can be coarsened, for example, by subsequent compaction. If the compaction is carried out dry, fine-particle graphite and / or other shaping aids mentioned in this document (for example, lubricants, reinforcing agents, and / or pore formers) can be mixed into the spray powder prior to compaction (for example, using a rotary mixer). For example, compaction can be carried out using a calender with two counter-rotating steel rollers. The compacted material can then be comminuted to the appropriate particle size for the intended use. This can be achieved very simply, for example, by pressing the compacted material through a sieve with a defined mesh size. In principle, compaction can also be carried out in a wet state. For example, the spray powder can be kneaded with the addition of water. Following kneading, the kneaded mass can be recombined to the desired fineness (see, for example, DE 10049 873 A1) and dried, depending on the subsequent use. From the finely divided precursor mass (from the finely divided intimate dry mixture of the sources of the elemental constituents) precursor shaped bodies of regular or irregular geometry are formed by compression (compression or compaction) and then the full catalyst shaped bodies are produced by thermal treatment.As further fine-particle shaping aids, lubricants such as graphite, carbon black, polyethylene glycol, polyacrylic acid, stearic acid, starch, mineral oil, vegetable oil, water, boron trifluoride and / or boron nitride can be added to the fine-particle precursor mass before and / or during shaping. Reinforcing agents such as microfibers made of glass, asbestos, silicon carbide or potassium titanate can also be considered as shaping aids, which, after the shaping process, have a beneficial effect on the cohesion of the resulting compressed material (the resulting shaped body) through compaction. Pore-forming agents such as ammonium nitrate, ammonium carbonate, water and / or malonic acid can also be considered as shaping aids. The pore-forming agents decompose or evaporate to form pores during the thermal treatment. The use of lubricants in the context of such shaping can be found, for example, inin the documents DE 10 2007 004961 A1, WO 2008 / 087116, WO 2005 / 030393, US 2005 / 0131253, WO 2007 / 017431, DE 102007 005606 A1 and in DE 10 2008 040093 A1. Preferably, only fine-particle graphite is used as a lubricant. In particular, the fine-particle graphites recommended in WO 2005 / 030393, US 2005 / 0131253, WO 2008 / 087116, and DE 10 2007 005606 A1 are suitable. This applies in particular to the graphites used in the examples and comparative examples in these documents. Particularly preferred graphites are Asbury 3160 and Asbury 4012 from Asbury Graphite Mills, Inc., New Jersey 08802, USA, and Timrex®T44 from Timcal Ltd., 6743 Bodio, Switzerland. Based on the weight of the finely divided precursor mass to be formed, this can contain, for example, up to 15 wt.% of finely divided lubricant (e.g., graphite) based on its total weight. However, the lubricant content in the finely divided precursor mass to be formed (in the finely divided, intimate dry mixture) is usually < 9 wt.%, often < 5 wt.%, and frequently < 4 wt.%; this is particularly the case when the finely divided lubricant is graphite. As a rule, the aforementioned added amount is > 0.5 wt.%, usually > 2.5 wt.%. Typically, the compaction of the finely divided precursor mass (the finely divided, intimate dry mixture), optionally containing shaping aids, to the desired geometry of the precursor molded body is achieved by applying external forces (pressure) to the precursor mass. The molding apparatus or method used for this purpose is not subject to any restrictions. For example, compaction can be achieved by tableting. The finely divided precursor mass (the finely divided, intimate dry mixture) is preferably used in a touch-dry state. However, it can still contain up to 10% of its total weight. Substances that are liquid under standard conditions (25 °C, 1 atm (1.01 bar)) may be added. The finely divided precursor mass (the finely divided, intimate dry mixture) may also contain solid solvates (e.g., hydrates) that contain such liquid substances in chemically and / or physically bound form. Of course, the finely divided precursor mass may also be completely free of such substances. The preferred shaping process by compacting the finely divided precursor mass (the finely divided, intimate dry mixture) is tableting. The principles of tableting are described, for example, in "Die Tablette," a manual for development, production, and quality assurance, by W.A. Tschel and A. Bauer-Brandl, 2nd edition, Edition Verlag Aulendorf, 2002, and can be applied in a completely analogous manner to a tableting process according to the invention. Tableting is a process of compression agglomeration. The free-flowing feed mixture is introduced into a compression tool with a die between two punches and compacted by uniaxial compression, forming a solid compacted body. Tableting can be divided into four stages: metered insertion, compaction (elastic deformation), plastic deformation, and ejection. Tableting is carried out, for example, on rotary presses or eccentric presses. The outer surface of the tableted catalyst support consists of a circumferential surface corresponding to the inner wall of the die cavity, and a first end face and a second side face corresponding to the operative heads of the punches. The tableted catalyst support can be flat or have curved ends, i.e., at least one of the first side faces and the second side face are curved. Curved side faces can be obtained, for example, by using a concave lower and / or upper punch. If desired, the upper punch and / or the lower punch can comprise projecting pins to form internal passages. It is also possible to provide the pressing punches with a plurality of pins, so that one punch can be manufactured, for example, with four pins to produce shaped bodies with four holes (passages). Typical design features of such pressing tools can be found, for example, in US Pat. No. 8,865,614. Press tools typically consist of a die, an upper punch, a lower punch, and pins (if the formed body has through holes). Suitable materials for press tools include tool steels, tungsten carbide (WC)-based cemented carbides, and ceramic materials. Tool materials with a hardness greater than 55 on the Rockwell C scale are preferred. Examples of tool steel materials include DIN tool steels 1.2210, 1.2343, 1.2436, 1.2379, 1.2601, 1.2080, and 1.25550, as well as high-speed steels, Vanadis 4 Extra from Uddeholm, D-40549 Düsseldorf, and Vanadis 8 from Uddeholm, D-40549 Düsseldorf. Suitable WC-based materials are described in US Pat. No. 8,865,614. Examples of such WC-based materials are G10-Ni from Hartmetall® Gesellschaft in D70497 Stuttgart and htc-KR17® from Hightech-Cerarn®. Examples of ceramic materials are yttrium-stabilized zirconium oxide (YSZ). WC-based cemented carbides and ceramic materials are particularly suitable for tool use, in which a lined die made of WC-based cemented carbide or ceramic is inserted into a steel housing made of tool steel, e.g. 1.2379. The pressing tool typically has a surface coating to improve surface hardness, corrosion resistance, wear resistance, friction, and anti-adhesion properties. Examples of surface coating types include diamond-like carbon (DLC), boron nitride, titanium nitride, chromium nitride, plasma chrome plating, and hard chrome plating. The coating thickness is 1 to 10 μm, preferably 1 to 5 μm. The surface of compression tools that come into contact with the feed mixture and the resulting tablet preferably has a low surface roughness. The arithmetic mean roughness value Ra according to DIN 4768 of compression tool surfaces should preferably be 0.01 to 0.5 μm, particularly preferably 0.02 to 0.3 μm, even more preferably 0.02 to 0.2 μm, and most preferably 0.02 to 0.1 μm. The length of the tip of the lower punch is preferably 2 to 7 mm, more preferably 2 to 6 mm, and most preferably 2.5 to 5 mm. Excessively high tip lengths can lead to high friction, especially if the precursor mold body sticks. It is preferred that the upper and lower edges of the tip of the lower punch are sharp rather than rounded. The sharp edge mitigates the powder from jamming into the gaps at the punch-to-punch interface and the pin-hole interface (in tablet molds with through holes). Jamming of the powder leads to both sticking and powder leakage. The length of the top straight line of the upper punch is preferably greater than 2 mm and typically ranges from 2 to 10 mm. Unlike the lower punch, a long straight line length does not cause friction problems, as the upper punch is only inserted a few millimeters into the die during tabletting cycles. If the tablet shape has through holes, the lower punch and upper punch have holes to accommodate the pins. The upper punches should have at least one vent hole to allow air to escape from the die cavity during compaction through the upper punch holes to the outside of the upper punch holes. Such upper punches with vent hole(s) are specified in US 2010 / 0010238 (see Figures 4a, 4b, 4c, and 4d). The distance between the nozzle bore and the lower punch outer surface is preferably 3 to 50 pm, more preferably 5 to 35 pm, most preferably 6 to 26 pm. Analogously, the distance between the die hole and the upper punch outer surface is preferably 3 to 50 pm, more preferably 5 to 35 pm, most preferably 6 to 26 pm. The distance is ensured by selecting a suitable combination of the dimensional tolerances of the die and the lower punch. The dimensional tolerance is typically represented according to the ISO shaft tolerance defined in ISO 286-2. Examples of the combinations of the dimensional tolerance of the nozzle bore and the punch outer surface represented in ISO tolerance codes are H6 / f7, H6 / g6, H6 / g7, H7 / g6, H7 / f7, F8 / h6, G7 / h6, F7 / h6 (nozzle bore / lower punch outer surface). In cases where the tablet shape has passages, the compression tool contains pins. The distance between the pin bore of the lower punch and the pin is preferably 3 to 50 μm, more preferably 5 to 35 μm, and most preferably 6 to 26 μm. Analogous to the distance between the die bore and the punch exterior, this distance is ensured by selecting a suitable combination of the dimensional tolerances of the die and the lower punch. The die bore preferably has a slight taper starting from a defined depth towards the die top. The tapered part of the nozzle bore has a gradual increase in bore size towards the die top, creating additional clearance between the nozzle bore wall and the pointed, straight outer side surface of the lower punch. The additional space facilitates the venting of the air contained in the compound feed during compression in the die, thereby mitigating powder blow-off and the resulting unstable tabletting due to poor air venting. Another advantage of conical dies is the ease of ejection after compaction. Compaction into a tablet at the point where the die bore has a taper results in a Tablet with a slightly tapered outer side surface due to the imprinting by the conical die bore. During the ejection phase, when the lower punch pushes the tablet upwards in the die, the tablet is easily ejected from the die wall because a slight lifting of the tablet due to the tapered structure forces the tablet to detach from the die wall. If the die bore has no taper, the tablet does not detach from the die wall, so the entire ejection process (i.e., pushing the tablet up from the depth at which compression occurred to the top of the die) suffers from friction between the outer surface of the tablet and the die wall and between the straight outer surface of the tip and the nozzle wall. This friction results in an unfavorably high ejection force. The depth (i.e., depth from the die top) of the die taper should be selected so that the formed tablet is predominantly located in the conical zone before ejection. To achieve this, the depth of the die taper can be oriented by summing the height of the in-die tablet before elastic recovery (i.e., minimum distance between the upper and lower punches) and the insertion depth of the upper punch. For example, a taper depth of 12 to 15 mm can be used for an in-die tablet height of 12 mm with an insertion depth of 2 mm of the upper punch. The die taper angle is typically 0.1 to 0.6°, and the die bore size increase on the upper side is preferably 0.03 to 0.2 mm, more preferably 0.05 to 0.14 mm. The size increase can be mathematically derived from the taper angle and the taper depth. In cases where the tablet shape has passageways, the compression tool includes pins. The pins are attached to the turret so that the pins are located in the die cavity where the tablet is formed, to exit the tablet's passageways. Analogous to the die, the pins do not move vertically during the tabletting cycle, unlike the upper and lower punches. The vertical plane of the upper end of the pins is equal to or slightly below the level of the upper face of the die. Particularly in cases where the tablet has curved sides, where the lower punching surface has a concave surface, the vertical plane of the upper end of the pin should be slightly below the level of the upper face of the dies to prevent the pins from protruding from the lower punching surface. In cases where the tablet mold has through holes, sticking to the surface of the pins often occurs, leading to disadvantages such as high ejection force due to high friction at the pin-tablet interfaces. This problem is particularly pronounced in multi-threaded molds with multiple pins. Typically, the pins exhibit a higher tendency to stick than the die wall and the tip of the lower punch. In cases where the tablet shape has passages, the pins preferably have a slight taper in the upper area for a defined length. The tapered part of the pins shows a gradual reduction in the pin diameter towards the top of the pin. The main advantage of the tapered pins is the ease of ejection after compaction. Compaction into a tablet at the point where the pins have a taper results in tablet passages with a slightly tapered inner side surface as a result of the imprinting by the tapered pins. The diameters of the tablet passages decrease slightly along the axial axis from bottom to top.During the ejection phase, in which the lower punch pushes the tablet upwards in the die while the pins and die remain vertically stationary, ejection of the tablet from the pins occurs easily because a slight lifting of the tablet forces the detachment of the tablet from the pins due to the tapered structure. If the pins do not have a taper, detachment of the tablet from the pins does not occur, so the entire ejection process (i.e., the... When the tablet is pushed up from the depth at which it was compressed onto the upper face of the die, it suffers from friction at the tablet-pin interfaces, resulting in a high ejection force. The conical pins are particularly advantageous when the tablet has multiple passages. The length of the pin taper should be selected so that the formed tablet is predominantly located in the conical zone before ejection. To achieve this, the length of the pin taper can be adjusted by summing the in-die tablet height before elastic recovery (i.e., the minimum distance between the upper and lower punches) and the insertion depth of the upper punch. For example, a tapered length of 12 to 15 mm can be used for an in-die tablet height of 12 mm with an insertion depth of 2 mm of the upper punch. The die taper angle is typically 0.1 to 0.6°, and the reduction in the pin diameter on the upper side is preferably 0.05 to 0.3 mm, more preferably 0.1 to 0.2 mm. The reduction can be mathematically derived from the taper angle and the taper length. Industrial mass production of tablets is preferably carried out on a rotary tablet press. Commercially available rotary presses can be used for this invention. Examples of rotary tablet presses are the Korsch XT-600 HD, Korsch XT-600, Korsch TPR 700, Korsch TRP 1200, Korsch XL 400 MFP, Kilian RX, and Kilian Synthesis. Rotary presses typically have two compaction rollers to perform a two-stage compaction process, comprising pre-compaction and main compaction. The main compaction pressure is in the range of 5 to 500 MPa, preferably 8 to 400 MPa, more preferably 10 to 300 MPa. The pre-compaction pressure is typically in the range of 5 to 50%, preferably 7 to 40%, more preferably 10 to 35% of the applied main compaction pressure. The compression tool is selected according to the desired geometric dimensions of the compacted body. The size and shape of the compacted body, and thus of the catalyst, are chosen to enable suitable packing of the catalyst bodies obtained from compacted bodies in a reactor tube. The catalysts obtained from the compacted bodies suitable for the catalysts according to the invention are preferably used in reactor tubes with a length of 6 to 14 m and an internal diameter of 20 mm to 50 mm. In general, the support consists of individual bodies with a maximum dimension in the range of 3 to 20 mm, such as 4 to 15 mm, in particular 5 to 12 mm. The maximum dimension is understood to be the longest straight line between two points on the outer circumference of the support. The shape of the compacted bodies is not particularly limited and can be any technically feasible form, depending, for example, on the forming process. For example, the support can be a solid tablet or a hollow tablet, such as a hollow cylinder. In a further embodiment, the support can be characterized by a multi-lobe structure. A multi-lobe structure is intended to refer to a cylinder structure that has a plurality of cavities, e.g., grooves or furrows, that run in the cylinder periphery along the cylinder height. In general, the cavities are arranged substantially equidistantly around the circumference of the cylinder. The compression force during tabletting influences the compaction of the free-flowing feed mixture and thus, for example, the density and / or mechanical stability of the compacted body. In practice, it has proven useful to specifically adjust the lateral compressive strength of the tableted catalyst support by selecting the appropriate compression force and to check it by random sampling. For the purposes of the present invention, the lateral Compressive strength is the force that breaks the tableted catalyst support sandwiched between two flat parallel plates, with the two flat parallel end faces of the catalyst support at right angles to the flat parallel plates. To improve tabletting properties, the free-flowing feed mixture can be subjected to further processing, e.g., sieving, preheating, and / or pregranulation, i.e., precompaction. A roller compactor, such as a Chilsonator® from Fitzpatrick, can be used for pregranulation. Further information on tabletting, particularly on pre-granulation, sieving, lubricants, and tools, can be found in WO 2010 / 000720. Further information on tabletting can be found in Handbook of Powder Technology, Chapter 16: Tabletting, K. Pitt and C. Sinka, Vol. 11, 2007, pp. 735 to 778. Advantageously, tabletting is carried out as described in WO 2005 / 030393, DE 102008 040093 A1, DE 102008 040094 A1, and WO 2007 / 017431. The temperature surrounding the tabletting machine is normally 25 °C. The particle diameters of the precursor mass to be compacted (the finely divided, intimate dry mixture), optionally as a result of pre-coarsening by compaction, are expediently in the range 100 to 2000 pm, preferably 150 to 1500 pm, particularly preferably 400 to 1250 pm, or 400 to 1000 pm, or 400 to 800 pm (shaping aid mixed in prior to compaction is not taken into account). Just as the shaping apparatus to be used for compaction or the shaping method to be applied, the desired geometry of the resulting shaped bodies is not subject to any restrictions in the process according to the invention. A preferred ring geometry (the geometry of an uncalcined green compact and the all-solid catalyst body resulting from it through calcination are normally essentially the same) is 5 mm x 5 mm x 2 mm (outer diameter x height (length) x inner diameter). This is because fixed catalyst beds made up of rings of this geometry result in a particularly low pressure drop in the reaction gas mixture flowing through the fixed catalyst bed (particularly in reaction tubes with an inner diameter of 22 mm to 30 mm). A low pressure drop is particularly advantageous when the partial oxidation catalyzed by the fixed catalyst bed is operated at a high loading of the fixed bed with reaction gas mixture (at a high flow rate of the reaction gas mixture flowing through the fixed catalyst bed).Another preferred ring geometry (it exhibits advantageous bulk behavior, particularly in reaction tubes with a smaller inner diameter (e.g., 20 mm)) is the geometry 5 mm x 3 mm x 2 mm (outer diameter x height (length) x inner diameter). Of course, all geometries disclosed and recommended in WO 02 / 062737 and WO 2015 / 067656 are also possible. Particularly in the case of ring-shaped precursor bodies (precursor bodies are also referred to as green compacts in the literature regardless of their shape), the shaping compaction should advantageously be carried out in such a way that the lateral compressive strength SDF V of the resulting molded body (cf. DE 102008 040093 A1, DE 102008 040094 A1 and WO 2005 / 030393) the relation 5 N < SDF V < 100 N, preferably 8 N < SDF V s 80 N, and particularly preferably 12 N < SDF V < 50 N is met. The experimental determination of the lateral compressive strength is carried out as described in the documents WO 2005 / 030393 and WO 2007 / 017431. Of course, ring-like green compacts, as recommended in DE 102008 040093 A1, are particularly preferred according to the invention. The end faces of ring-shaped or ring-like molded bodies can be used in the described manufacturing process for green compacts according to the invention both or only one of the two end faces) can be flat as well as convex (see in particular DE 102007 004961 A1, EP 0 184 790 A2, DE 102008 040093 A1 (for example its paragraph

[0032] ) and DE 102008 04009 A1 (for example its paragraph

[0074] ) and the embodiments individually presented in these documents). When determining / specifying the height of such geometric shaped bodies, such a convex curvature is generally not taken into account in the present document. Rings or ring-like shaped bodies with convexly curved (curved) end faces (preferably both end faces have the same curvature) are advantageous in that fixed catalyst beds of ring-shaped or ring-like shaped bodies with a convexly curved (curved) end face (with otherwise identical geometry) result in a lower pressure drop in the reaction gas mixture flowing through the fixed catalyst bed (especially in the case of fixed catalyst beds in reaction tubes) than fixed catalyst beds of ring-shaped or ring-like shaped bodies with a flat end face.This is especially true when the ring geometry is 5 mm x 5 mm x 2 mm (outer diameter x height (length) x inner diameter). The radius of such a convex curvature is generally 0.4 to 5 times (e.g. 0.8 to 4 times, or 1.2 to 3 times, or 1.6 to 2.6 times) the outer diameter of the circular cylinder of the catalyst ring. As already mentioned, a fixed catalyst bed resulting in a lower pressure drop is particularly advantageous when the partial oxidation catalyzed by the fixed catalyst bed is operated at a high loading of the fixed bed with reaction gas mixture (at a high current strength of the reaction gas mixture flowing through the fixed catalyst bed). Particularly advantageous ring geometries of shaped bodies obtainable by compacting finely divided precursor mass (finely divided intimate dry mixture) satisfy the condition height (length) / outer diameter = H / A = 0.3 to 1.5 or up to 1.2. H / A = 0.5 to 1.1 or up to 1.0 is particularly preferred. Furthermore, for ring-shaped or ring-like green compacts according to the invention, it is advantageous if the ratio l / A (where l is the inner diameter of the ring geometry) is 0.3 to 1.5, preferably 0.6 to 1.1. The above-mentioned ring geometries are particularly advantageous if they simultaneously have one of the advantageous H / A ratios and one of the advantageous I / A ratios. Such possible combinations are, for example, H / A = 0.3 to 1.5 or up to 1.2 and l / A = 0.3 to 1.5 or 0.6 to 1.1. Alternatively, H / A can be 0.5 to 1.1 or up to 1.0 and l / A can simultaneously be 0.3 to 1.5 or 0.6 to 1.1. Furthermore, it is advantageous for the relevant ring geometries if H is 2 to 7 mm and preferably 2 to 6 mm or 3 to 6 mm. Furthermore, it is advantageous if A for the rings is 4 to 8 mm, preferably 4 to 6 mm. The wall thickness of preferred ring geometries is 1 to 2 mm or up to 1.5 mm. Possible ring geometries according to the invention are thus (A x H x I) 5 mm x 5 mm x 2 mm, or 5 mm x 2 mm x 2 mm, or 5 mm x 3 mm x 2 mm, 5 mm x 5 mm x 2.5 mm, or 5 mm x 3 mm x 2.5 mm, or 5.5 mm x 5.5 mm x 2.5 mm, or 5.5 mm x 5.5 mm x 3 mm, or 5 mm x 3 mm x 3 mm, or 5.5 mm x 3 mm x 3.5 mm, or 6 mm x 3 mm x 4 mm, or 6 mm x 6 mm x 3 mm, or 6 mm x 6 mm x 3.5 mm, or 6.5 mm x 3 mm x 4.5 mm, or 7 mm x 3 mm x 5 mm, or 7 mm x 7 mm x 3 mm, or 7 mm x 3 mm x 4mm, or 7mm x 7mm x 4mm. All information in this document on specific surface areas of solids refers to determinations according to DIN 66131 (Determination of the specific surface area of ​​solids by gas adsorption (N2) according to Brunauer-Emmert-Teller (BET)), unless expressly stated otherwise. All information in this document on total pore volumes and pore diameter distributions on these total pore volumes refer to determinations using the method of mercury porosimetry using the Auto Pore V 9600 device (MicroActive Interactive Dara Analysis Software) from Micromeritics GmbH, D- 52072 Aachen (range: 0.1 - 61000 psi) at 23°C (evaluation with Washburn equation using a mercury contact angle of 140° and a mercury surface tension of 480 mN / m = 480 dyn / cm). According to the invention, precursor moldings advantageously have the lowest possible residual moisture content. This is particularly true when the intimate mixing of the various sources of elemental constituents other than oxygen was carried out wet (especially when it was carried out to form an aqueous mixture M). Preferably, the residual moisture content of advantageous green compacts is < 10 wt.%, better < 8 wt.%, even better < 6 wt.%, and most preferably < 4 wt.% or < 2 wt.% (the residual moisture determination can be carried out as described in “Die Bibliothek der Technik”, Volume 229, “Thermogravimetric Material Moisture Determination”, Fundamentals and Practical Applications, Horst Nagel, Verlag moderne industrie (e.g. using a Computrac MAX 5000 XL from Arizona Instruments)). If the green compacts are based on an aqueous mixture M (so that their residual moisture content consists of water), the residual moisture determination is conveniently carried out using microwaves (e.g. with the microwave system LB 456 from BERTHOLD TECHNOLOGIES). In this method, the microwave radiates very low power (0.1 mW) through the material under investigation (the latter experiences essentially no change in temperature due to the comparatively low power). The material components are thus polarized to varying degrees. In response, the microwave loses speed and energy. The influence of water molecules is significantly greater than the influence of other components, which enables the selective determination of residual water content. This is because water molecules, due to their size and dipole properties, are particularly good at following an alternating electromagnetic field in the microwave frequency range through dipole alignment. In doing so, they absorb energy and modify the alternating electromagnetic field with their electrical properties. The measuring principle is based on this field weakening and field modification.For example, a weak microwave field can be generated over the sensor surface of a planar sensor, and the resonance frequency of the sensor system can be continuously analyzed by scanning the microwave frequency. If a water-containing sample is then placed over the sensor, the resonance frequency shifts and its amplitude is dampened. Both the damping and the resonance frequency shift increase with increasing water quantity, and thus also with increasing bulk density of the sample. However, the ratio of frequency shift to dampening is a density-independent measure of the percentage water content and thus the key to moisture measurement. This ratio forms the so-called microwave moisture measurement value, which represents the total moisture content. Since the microwave resonance method is an indirect moisture measurement method, calibration is necessary.In such a calibration measurement, the sensor measures material samples with a defined moisture content. The linking of the microwave moisture readings with the corresponding defined absolute material moisture content then forms the calibration of the measuring system. The measurement accuracy is typically ± 0.1% moisture (for example, water moisture can be determined using a Sartorius PMD300PA online moisture meter). Against this background, spray drying of a wet (e.g. aqueous) mixture M should be carried out in such a way that the resulting spray powder has the lowest possible residual moisture content. Taking into account the aspect just addressed, the green parts should be stored as far as possible in the absence of ambient air (containing humidity) (Preferably storage until calcination takes place under anhydrous inert gas or under pre-dried air or in hermetically sealed containers). It is advantageous to carry out the forming / shaping and storage of finely divided, intimate dry mixtures under exclusion of ambient air (containing atmospheric humidity) (e.g. under an N2 atmosphere). The calcination of the green compacts normally takes place at temperatures (calcination temperatures) that reach or generally exceed at least 350°C. However, the temperature of 650°C is normally not exceeded during calcination (the term calcination temperature in this document refers to the temperature present in the calcination material (advantageously, the calcination material has a calcination temperature that is as uniform (homogeneous) as possible; this applies accordingly to the other calcination conditions)). Advantageously, the temperature of 600°C is not exceeded during calcination, preferably the temperature of 570°C, and frequently the temperature of 550°C. Furthermore, the temperature of 380°C is preferably exceeded during the above calcination, advantageously the temperature of 400°C, particularly advantageously the temperature of 420°C, and very particularly preferably the temperature of 440°C.The calcination process can also be divided into several stages. Advantageously, prior to calcination, a thermal pretreatment is carried out at temperatures of > 120°C and < 350°C, preferably > 150°C and < 320°C, particularly preferably e 170°C and < 290°C. Such a thermal pretreatment is advantageously carried out until the constituents contained within the mass to be thermally treated, which decompose into gaseous compounds under the conditions of the thermal treatment, have been largely (preferably completely) decomposed into gaseous compounds (the time required in this regard can be, for example, 3 to 15 hours, frequently 4 to 10 hours or 5 to 8 hours).This is generally the case when, on the one hand, the molar amount of cations other than metal ions contained in the mass to be calcined subsequently, based on the total molar amount of cations contained, is < 20 mol-% (preferably < 10 mol-%) and, on the other hand, the molar amount of O contained in the same mass. 2 ' different anions, based on the total molar amount of anions contained, is also < 20 mol-% (preferably < 10 mol-%). Favourable temperature windows for the final calcination temperature are therefore in the temperature range 400 to 600°C, or preferably in the temperature range 420 to 570°C, or particularly preferably in the temperature range 450 to 550°C. The total calcination duration is generally more than 0.5 hours, and frequently more than 2 hours. Calcination durations typically do not exceed 45 hours or 30 hours, respectively. The total calcination duration is often less than 25 hours. Generally, a shorter calcination duration is generally sufficient at higher calcination temperatures than at lower calcination temperatures. In an advantageous embodiment of the calcination according to the invention, 550°C is not exceeded, and the calcination duration in the temperature range > 430°C and < 550°C extends from > 4 to < 25 hours. The entire thermal treatment (including a decomposition phase) of a precursor mass (e.g., a green body) can be carried out under an inert gas or an oxidative atmosphere such as air (or another mixture of inert gas and molecular oxygen) as well as under a reducing atmosphere (e.g., a mixture of inert gas, NH3, CO and / or H2 or under methane). The thermal treatment can also be carried out under vacuum. The atmosphere can also be varied throughout the thermal treatment. The thermal treatment (especially the calcination phase) preferably takes place in an oxidizing atmosphere. For technical application purposes, this consists predominantly of stationary or (preferably) moving air (particularly preferably, the mass to be thermally treated (the calcination material) is flowed through by an air stream). However, the oxidizing atmosphere can also consist of a static or moving mixture of, for example, 25 vol.% N2 and 75 vol.% air, or 50 vol.% N2 and 50 vol.% air, or 75 vol.% N2 and 25 vol.% air (a treatment atmosphere of 100 vol.% N2 is also possible). In principle, the thermal treatment (e.g., calcination) of the precursor mass (e.g., the green compacts) can be carried out in a wide variety of kiln types, such as heatable forced-air chambers (forced-air kilns, e.g., forced-air shaft kilns), tray kilns, rotary kilns, belt calciners, or shaft kilns. According to the invention, the thermal treatment (e.g., calcination) is advantageously carried out in a belt calcining device, as recommended in DE 100 46 957 A1 and WO 02 / 24620. The formation of hot spots within the material to be treated (within the calcination material) is largely avoided by using fans to convey increased volume flows of calcination atmosphere through the calcination material via a gas-permeable conveyor belt carrying the calcination material (this ensures the most uniform calcination temperature possible in the calcination material). During the thermal treatment of the precursor materials (e.g., the green compacts) as described, any shaping aids used can be retained in the resulting shaped catalyst body and at least partially escape from it in gaseous form through thermal and / or chemical decomposition to form gaseous compounds (e.g., CO, CO2). Shaping aids remaining in the shaped catalyst body act, during catalytic use thereof, essentially exclusively as diluting agents for the active material. In principle, the thermal treatment can be carried out as described in US 2005 / 0131253. Typically, the lateral crushing strengths of annular unsupported catalyst bodies obtainable according to the invention as described are 4 to 16 N, frequently 5 to 14 N or 6 to 12 N. The specific (BET) surface area of ​​the solid catalyst body is advantageously 2 to 20 m2 / g or up to 15 m 2 / g, preferably 3 to 10 m 2 / g and particularly preferably 4 to 8 m 2 / g. The corresponding total pore volume (mercury porosimetry) is advantageously in the range of 0.33 to 0.60 cm 3 / g, preferably in the range 0.36 to 0.54 cm 3 / g and particularly preferably in the range 0.38 to 0.50 cm 3 / G. If the pore diameter in pm is plotted on the abscissa and the logarithm of the differential contribution in cm on the ordinate 3 / g of the respective pore diameter to the total pore volume in cm 3 / g, particularly favorable unsupported catalyst bodies according to the invention generally exhibit a substantially monomodal distribution (with only a pronounced maximum). If the contribution of pores with a pore radius < 0.1 pm to the total pore volume is < 0.05 cm 3 / g, particularly good overall target product selectivities result (for example, in the case of a heterogeneously catalyzed partial oxidation of propene to acrolein and / or acrylic acid). In the case that the contribution of such comparatively narrow pores to the total pore volume is > 0.05 cm 3 / g, an advantageous reduction of this contribution can be achieved according to the invention by increasing the calcination time and / or the calcination temperature. Furthermore, it proves to be advantageous for an increased overall target product selectivity if the contribution of pores with a pore radius in the range of 0.1 to 1 pm to the total pore volume, based on the total pore volume, is 85 to 99 vol.%, advantageously 87 to 97 vol.%, particularly preferably 89 to 95 vol.%. Of course, the unsupported catalyst bodies can also be used diluted with inert materials to catalyze heterogeneously catalyzed partial gas-phase oxidations. Suitable inert diluent materials include elemental oxides such as aluminum oxide, silicon dioxide, thorium dioxide, and zirconium dioxide, which are fired at high temperatures and are therefore comparatively low in pores. However, finely divided silicon carbide or finely divided silicates such as magnesium and aluminum silicate or steatite can also be used for the aforementioned purpose. From an application point of view, it is advantageous, for example, to grind the calcined active material into a finely divided powder. This is then mixed with finely divided diluent material, and the resulting mixed powder is formed into a geometric shaped body using a shaping process presented in this document (preferably by tabletting).By subsequent calcination, the latter is then transformed into the corresponding unsupported catalyst body. Of course, the finely divided inert diluent material can also be incorporated, for example, into a wet (e.g., aqueous) mixture M prior to its drying. Furthermore, finely divided inert diluent material can be incorporated into the finely divided dry mixture. However, such procedures are less preferred according to the invention. In particular, shaped catalyst bodies produced according to the described advantageous production processes are characterized by the fact that they essentially have no local centers of elemental oxides. Rather, these elements are largely components of complex, mixed oxomolybdates containing Bi, Fe, and Mo. This has proven advantageous with regard to the inventively sought minimization of undesirable complete combustion of organic reaction gas mixture components during the relevant heterogeneously catalyzed partial oxidations. Furthermore, the procedure for producing full catalysts is as described in WO 2010 / 066645, in order to ensure the most efficient use of materials. Shaped unsupported catalyst bodies according to the invention are suitable not only for catalyzing the heterogeneously catalyzed partial oxidation of propene to acrolein, but generally for catalyzing heterogeneously catalyzed partial gas-phase oxidations of alkanes, alkanols, alkenes, and / or alkenals containing 3 to 6 carbon atoms (partial oxidations are understood in this document to mean, in particular, those reactions of organic compounds under the reactive action of molecular oxygen in which the organic compound to be partially oxidized contains at least one more chemically bonded oxygen atom after the reaction has ended than before the partial oxidation). However, the term partial oxidation is also intended in this document to include oxidative dehydrogenation and partial ammoxidation, i.e., partial oxidation in the presence of ammonia. Unsupported catalyst bodies according to the invention are particularly suitable for catalyzing the heterogeneously catalyzed partial gas phase oxidation of propene to acrolein, of isobutene to methacrolein and for catalyzing the heterogeneously catalyzed partial gas phase ammoxidation of propene to acrylonitrile and of isobutene to methacrylonitrile. As already mentioned, the heterogeneously catalyzed partial gas phase oxidation of propene (iso-butene and / or tert-butanol) to acrolein (methacrolein) forms the first step of a two-step heterogeneously catalyzed partial gas phase oxidation of propene (iso-butene and / or tert-butanol). Butanol) to acrylic acid (methacrylic acid), as described for example in WO 2006 / 42459. The formation of acrylic acid (methacrylic acid) as a by-product in a heterogeneously catalyzed partial gas phase oxidation of propene (isobutene) to acrolein (methacrolein) is therefore generally not undesirable and is normally subsumed under the desired formation of the value product. The above applies in particular to annular shaped unsupported catalyst bodies according to the invention. The heterogeneously catalyzed partial oxidation (in particular that of propene to acrolein) can be carried out, for example, as described in the documents DE 102007 004961 A1, WO 02 / 49757, WO 02 / 24620, DE 102008 040093 A1, WO 2005 / 030393, EP 0 575 897 A1, WO 2007 / 082827, WO 2005 / 113127, WO 2005 / 047224, WO 2005 / 042459, WO 2007 / 017431, DE 102008 042060 A1, WO 2008 / 087116, DE 102010 048405 A1, DE 102009 047291 A1, DE 102008 042064 A1 , DE 10 2008 042061 A1 , WO 2015 / 067656 and DE 10 2008 040094 A1 for similar catalysts (in particular, the procedure can be similar to that described in the exemplary embodiments of these documents). The advantage of shaped catalyst bodies (in particular the ring-shaped ones) obtainable as described also exists when the loading of the catalyst feed of a reactor with propene, isobutene and / or tert. butanol (or its methyl ether) contained in the reaction gas input mixture is > 130 Nl / l catalyst feed • h, or > 140 Nl / l h, or > 150 Nl / l h, or > 160 Nl / l h (pre- and / or post-beds of pure inert material are not considered to be part of the catalyst feed in load considerations in this document; the volume of the catalyst feed (of the fixed catalyst bed) is, moreover, its bulk volume in the reactor). Normally, the above-mentioned catalyst loading will be < 600 Nl / I h, frequently < 500 Nl / I h, often < 400 Nl / I h or < 350 Nl / I h.Loads in the range of > 160 Nl / I h or > 180 Nl / I h to < 300 or < 250 or < 200 Nl / I h are particularly appropriate. In this document, the loading of a fixed catalyst bed with reaction gas input mixture is defined as the amount of reaction gas input mixture in standard liters (= NI; the volume in liters that the corresponding amount of reaction gas input mixture would occupy under standard conditions of 0 °C and 1 atm (1.01 bar)) that is fed to the fixed catalyst bed per hour, based on the volume of its bed (bed sections made of pure inert material are not included), i.e., its bed volume (-> unit = Nl / I h). The standard volume units such as NI or Nm 3 In this document, always refer (unless otherwise expressly stated) to the standard conditions of 0 °C and 1 atm (1.01 bar). The loading can also be based on only one component of the reaction gas input mixture (e.g., only on the organic starting compound to be partially oxidized). In this case, it is the volume of this component (e.g., the organic starting compound of the partial oxidation) that is fed to the fixed catalyst bed (the catalyst feed of the reactor), based on the volume of its bed, per hour. Naturally, unsupported catalyst bodies (for example ring-shaped) obtainable according to the invention can be used as catalysts for the partial oxidation of propene to acrolein or of isobutene and / or tert. butanol (or its methyl ether) to methacrolein The catalyst feed can also be operated advantageously according to the invention at loadings of the starting compound to be partially oxidized of < 130 Nl / l h, or < 120 Nl / l h, or < 110 Nl / l h, or < 100 Nl / l h, or < 90 Nl / l h. However, this loading will generally be at values ​​of > 20 Nl / l h, or > 30 Nl / l h, or > 40 Nl / l h, or > 50 Nl / l h, or > 60 Nl / l h, or > 70 Nl / l h, or > 80 Nl / l h. In principle, the loading of the catalyst feed of a reactor (a fixed catalyst bed) with the starting compound to be partially oxidized (propene, isobutene and / or tert. butanol (or its methyl ether)) can be adjusted via two adjusting screws: a) the loading of the catalyst feed with reaction gas input mixture (the reaction gas mixture that is fed to the fixed catalyst bed), and / or b) the content of the reaction gas input mixture with the starting compound to be partially oxidized. The shaped catalyst bodies (for example, ring-shaped) obtainable according to the invention are particularly suitable when, at loadings of the catalyst charge with the organic compound to be partially oxidized above 130 Nl / l h, the loading is adjusted primarily via the aforementioned adjusting screw a). As a rule, for example, the propene content (isobutene content or tert-butanol content (or the methyl ether content)) in the reaction gas input mixture will be 4 to 10 vol.%, frequently 5 to 9 vol.%, or 5.5 to 8.0 vol.%, or 6.0 to 7.5 vol.% (each based on the total volume (flow) of the reaction gas input mixture flowing into the fixed catalyst bed), essentially independent of the catalyst loading. The gas phase partial oxidation process of the partial oxidation catalyzed with the inventive (for example ring-shaped) unsupported catalyst bodies obtainable as described (essentially independent of the load) will frequently be carried out with an (organic) compound to be partially oxidized (for example propene): oxygen: inert gases (including water vapor) volume ratio in the reaction gas input mixture of 1:(1.0 to 3.0):(5 to 25), preferably 1:(1.5 to 2.3):(10 to 20). Indifferent gases (or inert gases) are understood to be those gases which remain chemically unchanged to at least 95 mol%, preferably to at least 98 mol%, during the partial oxidation when the reaction gas mixture passes through the catalyst bed once. In the reaction gas input mixtures described above, the indifferent gas can be > 20 vol.%, or > 30 vol.%, or > 40 vol.%, or > 50 vol%, or > 60 vol%, or > 70 vol%, or > 80 vol%, or > 90 vol.%, or > 95 vol.% molecular nitrogen. However, at higher loadings of the catalyst feed of the reactor with the organic compound to be partially oxidized (e.g., > 150 Nl / l h), the use of inert diluent gases with increased molar heats and / or thermal conductivities, such as propane, ethane, methane, pentane, butane, CO2, CO, water vapor, and / or noble gases for the reaction gas input mixture is recommended (but not mandatory). Generally, these inert gases and their mixtures can also be used at lower loadings of the catalyst feed with the organic compound to be partially oxidized. Recycle gas can also be used as a diluent. Recycle gas is understood to be the residual gas that remains when The target compound is essentially selectively separated from the product gas mixture of the partial oxidation. It should be noted that the partial oxidations to acrolein or methacrolein with the, for example, ring-shaped, unsupported catalyst bodies obtainable according to the invention can only be the first stage of a two-stage partial oxidation to acrylic acid or methacrylic acid as the actual target compounds, so that the cycle gas formation then usually only takes place after the second stage (typical cycle gas compositions for the case of a heterogeneously catalyzed partial oxidation of propene to acrolein and / or acrylic acid are shown in DE 102 32 482 A1 in its paragraphs

[0063] and

[0075] ). In such a two-stage partial oxidation, the product gas mixture of the first stage is generally fed as such, optionally after cooling and / or addition of secondary oxygen (usually as air), to the second partial oxidation stage. In the partial oxidation of propene to acrolein, using the inventive (for example, ring-shaped) unsupported catalyst bodies obtainable as described, a typical composition of the reaction gas input mixture measured at the reactor inlet (regardless of the selected loading) can, for example, contain the following components 6 to 6.5 vol% propene, 1 to 3.5 vol.% H2O, 0.8 to 1.7 vol.% COx, 0.015 to 0.04 vol.% acrolein, 9.4 to 12.3 vol% oxygen and the remainder to 100 vol% molecular nitrogen; or 5.6 vol% propene, 1.4 vol.% H2O. 1.2 vol.% COx, 10.2 vol.% oxygen and the remainder to 100 vol.% molecular nitrogen; The former compositions are particularly suitable for propene loadings of > 130 Nl / I h and the latter composition particularly for propene loadings < 130 Nl / I h, in particular < 100 Nl / I h (for example for commissioning the partial oxidation) of the fixed catalyst bed. Alternatively, reaction gas input mixtures of the composition according to Example 1 of EP 0 990636 A1, or according to Example 2 of EP 0 990 636 A1, or according to Example 3 of EP 1 106 598 A2, or according to Example 26 of EP 1 106 598 A2, or according to Example 53 of EP 1 106 598 A2, or according to the examples of WO 2021 / 013640 can also be used for a propene partial oxidation to acrolein according to the invention. The inventive, for example annular, shaped catalyst bodies obtainable as described are also suitable for the processes of DE 102 46 119 A1 or DE 102 45 585 A1. The reaction temperature for a heterogeneously catalyzed propene partial oxidation to acrolein according to the invention is frequently from 300 to 450°C, or up to 400°C, or up to 380°C when using the inventive (for example, ring-shaped) unsupported catalyst bodies obtainable as described. A particularly preferred reaction temperature window is from 305 to 345°C. The same applies in the case of methacrolein as the target compound. The reaction pressure for the aforementioned partial oxidations is generally from 0.5 to 4 or up to 3 bar, or preferably from 1.1 or 1.5 to 4 or up to 3 bar (unless expressly stated otherwise, absolute pressures are always meant in this document). The total loading of the catalyst feed with reaction gas input mixture in the aforementioned partial oxidations according to the invention typically amounts to 1000 to 10000 Nl / lh, mostly to 1500 to 5000 Nl / lh and often to 2000 to 4000 Nl / lh. The propene to be used in the reaction gas input mixture is primarily polymer grade propene and chemical grade propene, as described, for example, in WO 2004 / 007405. Air (possibly together with recycle gas) is normally used as the oxygen source. The partial oxidation using the inventive (for example the annular) unsupported catalyst bodies obtainable as described can, in the simplest case, be carried out, for example, in a single-zone fixed-bed catalyst tube reactor, as described in DE 44 31 957 A1, EP 0 700 714 A1 and EP 0 700 893 A1. Typically, the contact tubes in the aforementioned shell-and-tube reactors are made of ferritic steel and typically have a wall thickness of 1 to 3 mm. Their internal diameter is generally 20 to 30 mm, frequently 21 to 26 mm. A typical contact tube length is, for example, 3.50 m, 4.00 m, or 4.50 m. The number of contact tubes accommodated in the shell-and-tube vessel is expediently at least 1000, preferably at least 5000. Frequently, the number of contact tubes accommodated in the reaction vessel is between 15,000 and 40,000. Shell-and-tube reactors with a number of contact tubes above 45,000 are rather the exception. Within the container, the contact tubes are normally arranged in a homogeneous distribution, whereby the distribution is expediently selected such that the distance between the central inner axes of the contact tubes closest to each other (the so-called contact tube pitch) is 35 to 45 mm (cf. EP 0 468290 B1).However, the partial oxidation can also be carried out in a multi-zone (e.g., "two-zone") multi-contact tube fixed-bed reactor, as recommended in DE 199 10 506 A1, DE 103 13213 A1, DE 103 13208 A1, and EP 1 106 598 A2, particularly when the catalyst charge of the multi-contact tube reactor is subjected to increased loadings with the organic compound to be partially oxidized. A typical contact tube length in a two-zone multi-contact tube fixed-bed reactor is 3.50 m, 4.00 m, or 4.50 m. Everything else essentially applies as described for the single-zone multi-contact tube fixed-bed reactor. A heat exchange medium is passed around the catalyst tubes, within which the catalyst feed (the catalyst fixed bed) is located, in each tempering zone (the single-zone multi-contact tube reactor fixed bed reactor has only one tempering zone) of the single-zone or multi-zone multi-contact tube fixed bed reactor.Suitable examples include melts of salts such as potassium nitrate, potassium nitrite, sodium nitrite, and / or sodium nitrate, or of low-melting metals such as sodium, mercury, and alloys of various metals. The flow rate of the heat exchange medium within the respective tempering zone is generally selected so that the temperature of the heat exchange medium increases by 0 to 15°C, often 1 to 10°C, or 2 to 8°C, or 3 to 6°C, from the point of entry into the tempering zone to the point of exit from the tempering zone. The inlet temperature of the heat exchange medium, which, viewed across the respective tempering zone, can be conducted in cocurrent or countercurrent to the reaction gas mixture, is preferably selected as recommended in the documents EP 1 106 598 A2, DE 19948 523 A1, DE 19948 248 A1, DE 103 13 209 A1, EP 0 700 714 A1, DE 103 13208 A1, DE 103 13213 A1, WO 00 / 53557, WO 00 / 53558, WO 01 / 36364, WO 00 / 53557 and the other documents cited in these documents as prior art. Within the tempering zone, the heat exchange medium is preferably conducted in a meandering pattern. The difference between the highest and lowest temperature of the heat exchange medium located within a tempering zone should, considered over that longitudinal section of the tempering zone in which a catalytically active (not pure inert) section of the fixed catalyst bed is located, advantageously be > 0°C and < 5°C (preferably this difference is small).Typically, the multi-contact tube fixed-bed reactor also features thermocouples for determining the temperature of the reaction gas in the catalyst bed (both thermocouples and reaction tubes are charged with the same fixed bed). The inner diameter of the thermocouples and the diameter of the thermocouple sleeve (thermocouple sleeve), which is centered inside and runs parallel to the longitudinal axis of the thermocouple, are selected so that the ratio of reaction heat-generating volume to heat-dissipating surface area is the same or only slightly different for the thermocouples and the working tubes. The pressure drop should be the same for working tubes and thermotubes, based on the same GHSV (= the volumetric flow rate of the reaction gas mixture entering the tube divided by the bulk volume of the fixed catalyst bed in the tube). Pressure loss compensation for the thermotube can be achieved, for example, by adding crushed catalyst to the solid catalyst bodies. This compensation is preferably carried out homogeneously over the entire length of the thermotube. Furthermore, the filling of thermotubes can be designed as described in EP 0 873 783 A1. As already mentioned, only unsupported catalyst bodies available as described (e.g., annular) or, for example, largely homogeneous mixtures of unsupported catalyst bodies available as described (e.g., annular) and shaped bodies containing no active material that are essentially inert with respect to the heterogeneously catalyzed partial gas-phase oxidation can be used to prepare the catalyst feed in the catalyst tubes. Suitable materials for such inert shaped bodies include, for example, porous or non-porous aluminum oxides, silicon dioxide, zirconium dioxide, silicon carbide, silicates such as magnesium or aluminum silicate, and / or steatite (e.g., type C220 from CeramTec, Germany). The geometry of such inert diluent bodies is arbitrary. This means that they can be, for example, spheres, polygons, solid cylinders, or even, as in the case of annular catalyst bodies, rings. Inert diluent bodies are often chosen whose geometry corresponds to that of the catalyst bodies to be diluted with them. However, the geometry of the catalyst bodies can also be changed along the catalyst feed, or catalyst bodies of different geometries can be used in a largely homogeneous mixture. In a less preferred procedure, the active mass of the catalyst body can also be changed along the catalyst feed. In general, the catalyst feed is advantageously designed in such a way that the volume-specific activity (i.e., the activity normalized to the unit of volume) in the flow direction of the reaction gas mixture either remains constant or increases (continuously, abruptly or stepwise). A reduction in the volume-specific activity can be achieved in a simple manner, for example, by using a basic amount of The prepared (for example, annular) unsupported catalyst bodies are homogeneously diluted with inert diluent bodies. The higher the proportion of unsupported catalyst bodies, the lower the active mass or catalyst activity contained in a given volume of the feed. However, a reduction can also be achieved by modifying the geometry of the unsupported catalyst bodies obtainable according to the invention such that the amount of active mass contained per unit of internal reaction tube volume becomes smaller. For the heterogeneously catalyzed gas phase partial oxidations with unsupported catalyst bodies (e.g., ring-shaped) obtainable as described, the catalyst feed is preferably either designed uniformly over the entire length with only one type of unsupported catalyst bodies or structured as follows.At the reactor inlet, a substantially homogeneous mixture of (for example annular) unsupported catalyst bodies and inert diluent bodies (where both preferably have substantially the same geometry) is placed over a length of 10 to 60%, preferably 10 to 50%, particularly preferably 20 to 40% and very particularly preferably 25 to 35% (that is to say, for example, over a length of 0.70 to 1.50 m, preferably 0.90 to 1.20 m), in each case of the total length of the catalyst feed, the weight fraction of the diluent bodies (the mass densities of catalyst bodies and of diluent bodies generally differ only slightly) is normally 5 to 40% by weight, or 10 to 40% by weight, or 20 to 40% by weight, or 25 to 35% by weight.Following this first feed section, there is then advantageously located up to the end of the length of the catalyst feed (i.e., for example, over a length of 1.00 to 3.00 m or 1.00 to 2.70 m, preferably 1.40 to 3.00 m, or 2.00 to 3.00 m) either a bed of the same (for example annular) unsupported catalyst bodies obtainable as described, which bed is diluted to only a lesser extent (than in the first section), or, very particularly preferably, a sole (undiluted) bed of the same (for example annular) unsupported catalyst bodies which was also used in the first section. Of course, a constant dilution can also be selected over the entire feed.Also, in the first section, only a (for example, ring-shaped) unsupported catalyst body with a low active mass density based on its space requirement can be charged, and in the second section, a (for example, ring-shaped) unsupported catalyst body obtainable according to the invention with a high active mass density based on its space requirement (for example, 6.5 mm x 3 mm x 4.5 mm [outer diameter x height x inner diameter] in the first section, and 5 x 2 x 2 mm [A x H x I] in the second section). In the flow direction of the reaction gas mixture, upstream of the actual fixed catalyst bed, a bed of inert shaped bodies can be arranged, which, for example, has the purpose of increasing the inlet temperature of the reaction gas mixture to the temperature of the heat exchange medium. Furthermore, according to the teachings of the prior art (for example, WO 2012 / 049246), the catalyst feed (in particular the fresh catalyst feed) of the reactor and the process conditions of the catalyzed partial oxidation in the case of the heterogeneously catalyzed partial oxidation of propene to acrolein (or in the case of a heterogeneously catalyzed partial oxidation for the production of methacrolein) are preferably selected (designed) such that, during partial oxidation operation, the difference between the temperature of this point of the fixed catalyst bed and the temperature of the heat exchange medium at the level of this point is > 120°C at any point in the fixed catalyst bed. This temperature difference is advantageously positive at every point, but < 100°C (in particular 40 to 100°C), particularly advantageously < 90°C (in particular 50 to 90°C). In principle, however, this (positive) temperature difference can also be < 50°C or < 40°C.Furthermore, the design is preferably such that this temperature difference increases by >1°C at any point in the fixed catalyst bed when the temperature of the heat exchange medium increases by 1°C. 0°C but < +9°C, better < +7°C, preferably < +5°C, particularly preferably < +3°C (see also EP 1 106 598 A1). Furthermore, a heterogeneously catalyzed partial oxidation for the production of acrolein (from propene) or of methacrolein (from the C4 precursor compounds mentioned in the present document) can advantageously be carried out using annular unsupported catalyst bodies produced according to the invention in complete accordance with the statements in WO 2015 / 067656. Overall, in a partial oxidation for producing acrolein or methacrolein carried out using the (for example ring-shaped) unsupported catalyst bodies obtainable as described as catalysts, the catalyst feed, the reaction gas starting mixture, the space velocity and the reaction temperature are generally selected such that a single pass of the reaction gas mixture through the catalyst feed results in a conversion of the organic compound to be partially oxidized (propene, isobutene, tert-butanol or its methyl ether) of at least 90 mol%, or at least 92 mol%, preferably of at least 93 mol% or at least 94 mol% or at least 95 mol% or at least 97 mol%, but normally < 99 mol%. The selectivity of the value products (sum of acrolein and acrylic acid or sum of methacrolein and methacrylic acid) will regularly be > 80 mol-%, > 85 mol-% or > 90 mol-%. Finally, it should be noted that the inventive unsupported catalyst bodies obtainable as described also exhibit advantageous fracture behavior during reactor filling. The commissioning of a fresh catalyst feed (catalyst fixed bed) containing unsupported catalyst bodies (for example, annular) obtainable according to the invention can be carried out, for example, as described in DE 103 37 788 A1 or as described in DE 10 2009 047291 A1. The formation of unsupported catalyst bodies obtainable according to the invention can be accelerated by carrying it out at essentially constant conversion under increased loading of the catalyst feed with reaction gas input mixture. Furthermore, unsupported catalysts obtainable according to the invention are generally suitable for catalyzing the gas phase partial (amm)oxidation of an alkanol, alkanal, aiken, alkane and alkenal containing 3 to 6 (i.e. 3, 4, 5 or 6) C atoms to, for example, olefinically unsaturated aldehydes and / or carboxylic acids and the corresponding nitriles, and for gas phase catalytic oxidative dehydrogenations of the aforementioned organic compounds containing 3, 4, 5 or 6 C atoms. The large-scale production of unsupported catalyst shaped bodies according to the invention is advantageously carried out analogously to that described in DE 10 2008 040093 A1 and DE 10 2008 040094 A1 (particularly advantageously as in the exemplary embodiments of these documents). The present application therefore comprises in particular the following embodiments of the invention: The present invention therefore includes in particular the following embodiments of the invention: 1. A process for the preparation of unsupported catalyst bodies for the gas phase oxidation of an alkyne and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein the unsupported catalyst bodies comprise at least the elements molybdenum, bismuth, iron and cobalt, wherein a) an aqueous solution or aqueous suspension is produced from at least one source of the elemental constituents molybdenum, bismuth, iron, cobalt and optionally at least one source of the elemental constituent nickel, b) a powder P is produced by drying the aqueous solution or aqueous suspension obtained in a) and optionally comminuting, c) that powder P obtained in b), optionally with the addition of one or more auxiliaries and after uniform mixing and optionally compacting, is compacted to form precursor shaped bodies with a cylindrical structure, and d) the precursor shaped bodies obtained in c) are thermally treated to form the unsupported catalyst shaped bodies, characterized in that the pressure during the compaction in c) is selected such that the density of the precursor shaped bodies is from 1.70 to 2.30 g / cm 3wherein the density of the precursor shaped bodies is the quotient of the mass and the geometric volume, and the weight loss during the thermal treatment in d) is from 25 to 40 wt.%. 2. Process according to embodiment 1, characterized in that the pressure during compaction in c) is selected such that the density of the precursor shaped bodies is from 1.72 to 2.28 g / cm 3 amounts. 3. Process according to embodiment 1 or 2, characterized in that the pressure during compaction in c) is selected such that the density of the precursor shaped bodies is from 1.74 to 2.26 g / cm 3 amounts. 4. Process according to one of embodiments 1 to 3, characterized in that the pressure during the compaction in c) is selected such that the density of the precursor shaped bodies is from 1.76 to 2.24 g / cm 3 amounts. 5. Process according to one of embodiments 1 to 4, characterized in that the pressure during the compaction in c) is selected such that the density of the precursor shaped bodies is from 1.78 to 2.22 g / cm 3 amounts. 6. Process according to one of embodiments 1 to 5, characterized in that the pressure during compaction in c) is selected such that the density of the precursor shaped bodies is from 1.80 to 2.20 g / cm 3 amounts. 7. Process according to one of embodiments 1 to 6, characterized in that the weight loss during the thermal treatment in d) is from 26 to 39 wt.%. 8. Process according to one of embodiments 1 to 7, characterized in that the weight loss during the thermal treatment in d) is from 27 to 38 wt.%. 9. Process according to one of embodiments 1 to 8, characterized in that the weight loss during the thermal treatment in d) is from 28 to 38 wt.%. 10. Process according to one of embodiments 1 to 9, characterized in that the weight loss during the thermal treatment in d) is from 29 to 37 wt.%. 11. Process according to one of embodiments 1 to 10, characterized in that the weight loss during the thermal treatment in d) is from 30 to 35 wt.%. 12. The method according to any one of embodiments 1 to 11, characterized in that the cylindrical structure is i) a cylindrical body with a circular through-opening located centrally in the longitudinal direction or ii) a cylindrical body with three circular through-openings uniformly arranged in the longitudinal direction. 13. The method according to any one of embodiments 1 to 12, characterized in that the cylindrical structure is a hollow cylinder. 14. Process according to one of embodiments 1 to 13, characterized in that the molybdenum content of the unsupported catalyst bodies, calculated as molybdenum, is from 45 to 75 wt.%. 15. Process according to one of embodiments 1 to 14, characterized in that the molybdenum content of the unsupported catalyst shaped bodies, calculated as molybdenum, is from 50 to 70 wt.%. 16. Process according to one of embodiments 1 to 15, characterized in that the molybdenum content of the unsupported catalyst bodies, calculated as molybdenum, is from 55 to 65% by weight. 17. Process according to any one of embodiments 1 to 16, characterized in that the bismuth content of the unsupported catalyst bodies, calculated as Bi2O3, is from 1 to 20 wt.%. 18. Process according to any one of embodiments 1 to 17, characterized in that the bismuth content of the unsupported catalyst bodies, calculated as Bi2O3, is from 2 to 15 wt.%. 19. Process according to any one of embodiments 1 to 18, characterized in that the bismuth content of the unsupported catalyst bodies, calculated as Bi2Ö3, is from 3 to 10 wt.%. 20. Process according to any one of embodiments 1 to 19, characterized in that the iron content of the unsupported catalyst bodies, calculated as Fe2O3, is from 2 to 12 wt.%. 21. Process according to any one of embodiments 1 to 20, characterized in that the iron content of the unsupported catalyst bodies, calculated as Fe2O3, is from 3 to 11 wt.%. 22. Process according to any one of embodiments 1 to 21, characterized in that the iron content of the unsupported catalyst bodies, calculated as Fe2O3, is from 4 to 10 wt.%. 23. Process according to any one of embodiments 1 to 22, characterized in that the content of cobalt and nickel, calculated as CoO and NiO, in the unsupported catalyst bodies is in total from 9 to 30 wt.%. 24. Process according to any one of embodiments 1 to 23, characterized in that the content of cobalt and nickel, calculated as CoO and NiO, in the unsupported catalyst bodies is in total from 12 to 27 wt.%. 25. Process according to any one of embodiments 1 to 24, characterized in that the content of cobalt and nickel, calculated as CoO and NiO, in the unsupported catalyst bodies is in total from 15 to 24 wt.%. 26. Process according to one of embodiments 1 to 25, characterized in that the unsupported catalyst bodies additionally contain the elements potassium and / or silicon. 27. A shaped unsupported catalyst body having a cylindrical structure for the gas phase oxidation of an aldehyde and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, obtainable by a process of embodiments 1 to 26, wherein the shaped unsupported catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, wherein the density of the shaped unsupported catalyst body is from 1.20 to 1.70 g / cm 3 where the density of the unsupported catalyst body is the quotient of the mass and the geometric volume, the total pore volume of the unsupported catalyst body is from 0.33 to 0.60 cm 3 / g and the pore volume of the full catalyst body in the range of 0.1 to 1 pm is from 85 to 99% of the total pore volume, wherein the total pore volume and the pore volume in the range of 0.1 to 1 pm are determined by mercury porosimetry. 28. Unsupported catalyst shaped body according to embodiment 27, wherein the density of the unsupported catalyst shaped body is from 1.22 to 1.68 g / cm 3 amounts. 29. Unsupported catalyst shaped body according to embodiment 27 or 28, wherein the density of the unsupported catalyst shaped body is from 1.24 to 1.66 g / cm 3 amounts. 30. Unsupported catalyst shaped body according to any one of embodiments 27 to 29, wherein the density of the unsupported catalyst shaped body is from 1.26 to 1.64 g / cm 3 amounts. 31. Unsupported catalyst shaped body according to any one of embodiments 27 to 30, wherein the density of the unsupported catalyst shaped body is from 1.28 to 1.62 g / cm 3 amounts. 32. Unsupported catalyst shaped body according to one of embodiments 27 to 31, wherein the density of the unsupported catalyst shaped body is from 1.30 to 1.60 g / cm 3 amounts. 33. Unsupported catalyst shaped body according to any one of embodiments 27 to 32, wherein the total pore volume of the unsupported catalyst shaped body is from 0.34 to 0.58 cm 3 / g. 34. Unsupported catalyst shaped body according to any one of embodiments 27 to 33, wherein the total pore volume of the unsupported catalyst shaped body is from 0.35 to 0.56 cm 3 / g. 35. Unsupported catalyst shaped body according to any one of embodiments 27 to 34, wherein the total pore volume of the unsupported catalyst shaped body is from 0.36 to 0.54 cm 3 / g. 36. Unsupported catalyst shaped body according to any one of embodiments 27 to 35, wherein the total pore volume of the unsupported catalyst shaped body is from 0.37 to 0.52 cm 3 / g. 37. Unsupported catalyst shaped body according to any one of embodiments 27 to 36, wherein the total pore volume of the unsupported catalyst shaped body is from 0.38 to 0.50 cm 3 / g. 38. Unsupported catalyst shaped body according to any one of embodiments 27 to 37, wherein the pore volume of the unsupported catalyst shaped body is in the range from 0.1 to 1 pm from 86 to 98% of the total pore volume. 39. Unsupported catalyst shaped body according to any one of embodiments 27 to 38, wherein the pore volume of the unsupported catalyst shaped body is in the range from 0.1 to 1 pm from 87 to 97% of the total pore volume. 40. Unsupported catalyst shaped body according to any one of embodiments 27 to 39, wherein the pore volume of the unsupported catalyst shaped body is in the range from 0.1 to 1 pm from 88 to 96% of the total pore volume. 41. Unsupported catalyst shaped body according to any one of embodiments 27 to 40, wherein the pore volume of the unsupported catalyst shaped body is in the range from 0.1 to 1 pm from 89 to 95% of the total pore volume. 42. Unsupported catalyst shaped body according to any one of embodiments 27 to 41, wherein the cylindrical structure is i) a cylindrical body with a circular through-opening centrally arranged in the longitudinal direction or ii) a cylindrical body uniformly notched three times in the longitudinal direction and having three circular through-openings uniformly arranged in the longitudinal direction. 43. Unsupported catalyst shaped body according to embodiment 42, wherein the shortest distance between the outer wall of the cylindrical body and the nearest through opening is from 0.75 to 2.5 mm. 44. Unsupported catalyst shaped body according to embodiment 42 or 43, wherein the shortest distance between the outer wall of the cylindrical body and the nearest through opening is from 0.8 to 2.0 mm. 45. Unsupported catalyst shaped body according to any one of embodiments 42 to 44, wherein the shortest distance between the outer wall of the cylindrical body and the nearest through opening is from 1.0 to 1.8 mm. 46. ​​Unsupported catalyst shaped body according to any one of embodiments 42 to 45, wherein the shortest distance between the outer wall of the cylindrical body and the nearest through opening is from 1.2 to 1.7 mm. 47. Unsupported catalyst shaped body according to any one of embodiments 42 to 46, wherein the shortest distance between the outer wall of the cylindrical body and the nearest through opening is from 1.3 to 1.6 mm. 48. Unsupported catalyst shaped body according to any one of embodiments 27 to 42, wherein the cylindrical structure is a hollow cylinder. 49. Unsupported catalyst shaped body according to embodiment 48, wherein the wall thickness of the hollow cylinder is from 0.75 to 2.5 mm. 50. Unsupported catalyst shaped body according to embodiment 48 or 49, wherein the wall thickness of the hollow cylinder is from 0.8 to 2.0 mm. 51. Unsupported catalyst shaped body according to any one of embodiments 48 to 50, wherein the wall thickness of the hollow cylinder is from 1.0 to 1.8 mm. 52. Unsupported catalyst shaped body according to one of embodiments 48 to 51, wherein the wall thickness of the hollow cylinder is from 1.2 to 1.7 mm. 53. Unsupported catalyst shaped body according to any one of embodiments 48 to 52, wherein the wall thickness of the hollow cylinder is from 1.3 to 1.6 mm. 54. Unsupported catalyst shaped body according to any one of embodiments 27 to 53, wherein the unsupported catalyst shaped body comprises a multielement oxide of the general formula I Moi2BiaFe b COcNidXeY f Z g On (I) with X = K, Cs and / or Rb Y = Ca, Sr, Ba, Li, Na, Cr, W, Mn, Cu, Zn, Ga, P, B, As, Sn, Sb, Te, Nb, Ta, Pb, Ce and / or La Z = Si, Al, Ti, Zr and / or Mg a = 0.2 to 2 b = 1 to 4 c = 3 to 9 d = 0 to 4 c + d = 4 to 9.5 e = 0.01 to 0.5 f = 0 to 10 g = 0 to 10 n = a number determined by the valence and frequency of the elements other than oxygen in the general formula I. 55. A process for preparing an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein an alkene and / or an alcohol is passed with molecular oxygen over a fixed catalyst bed comprising a bed of unsupported shaped catalyst bodies according to any one of embodiments 27 to 54. 56. Process according to embodiment 55, characterized in that the propene is used as alkene. 57. Fixed-bed reactor comprising a bed of unsupported catalyst bodies according to any one of embodiments 27 to 55. Examples Production of the solid catalyst bodies K1 to K10: Example 1 Preparation of the full catalyst precursor body K1 , wherein the active multimetal oxide had the stoichiometry Mo^CoyFesBio.eSii.ßKo.osOx. The stirred vessels used were filled in the presence of ambient air. During stirring / mixing, they were sealed hermetically with a lid that had a pressure relief valve to the atmosphere (1.01 bar). a) Preparation of an aqueous solution B In a temperature-controlled cylindrical stirred vessel (1.75 m 3 430 kg of demineralized water were placed in a stainless steel (EN 1.4541) (internal volume, 1.3 m diameter) and heated to 60°C while stirring (70 rpm). Subsequently, 0.61 kg of an aqueous potassium hydroxide solution (47.5 wt.% KOH) at a temperature of 20°C was added over one minute while stirring continuously and maintaining a temperature of 60°C. While maintaining the temperature at 60°C, 136.2 kg of fine-grained ammonium heptamolybdate tetrahydrate (54.3 wt.% Mo, supplier: NIPPON INORGANIC COLOUR & CHEMICAL CO., LTD., 3-14-1 Funado ltabashi-ku Tokyo 174-0041 Japan) at a temperature of 25°C were stirred in portions while stirring continuously. The resulting aqueous solution (slightly turbid due to minimal insoluble isopolymolybdate impurities) was stirred at 60°C for 60 minutes (70 rpm). b) Preparation of an aqueous solution A In a temperature-controlled cylindrical stirred vessel (1.75 m 3212 kg of an aqueous nitric acid cobalt(II) nitrate solution (12.5 wt% Co, 27 wt% nitrate, prepared by dissolving cobalt metal from MFT Metals % Ferro-Alloys Trading GmbH, D-41474 Viersen, purity > 99.6 wt% Co, < 0.3 wt% Ni, < 100 mg / kg Fe, < 50 mg / kg Cu ​​in aqueous nitric acid) were placed in a stainless steel (EN 1.4541) (internal volume, 1.3 m diameter) and heated to 60°C while stirring (70 rpm). With continued stirring (70 rpm) and continued tempering at 60°C, 78 kg of a 60°C warm iron(III) nitrate nonahydrate melt (13.8 wt% Fe, <0.4 wt% alkali metals, <0.01 wt% chloride, <0.02 wt% sulfate, from Dr. Paul Lohmann GmbH, D-81857 Emmerthal) were added and stirred for 30 minutes at 60°C (70 rpm). 72.6 kg of a 60°C warm, aqueous, nitric acid bismuth nitrate solution (11.1 wt.% Bi, 13 wt.% nitrate, prepared by dissolving bismuth metal from Sidech SA, BE-1495 Tilly, purity > 99.997 wt.% Bi, < 7 mg / kg Pb, < 5 mg / kg each of Ni, Ag, Fe, < 3 mg / kg each of Cu, Sb and < 1 mg / kg each of Cd, Zn in aqueous nitric acid) were added to the resulting aqueous solution while maintaining the temperature at 60°C and continuing to stir (70 rpm). c) Mixing of aqueous solution A with aqueous solution B The 60°C warm aqueous solution A was continuously added over 15 minutes to the intensively stirred (70 rpm) 60°C warm aqueous solution B. The resulting aqueous suspension was stirred for a further 15 minutes at 60°C. d) Addition of a silica sol to obtain an aqueous mixture M After stirring was complete, 12.6 kg of silica gel heated to 60°C from Grace GmbH & KG, In der Hollerecke 1, D-67545 Worms, type LUDOX TM50 (47.5 wt% SiO2) were immediately added to the aqueous mixture obtained in c). e) Spray drying of the aqueous mixture M The aqueous mixture M was spray-dried immediately after its preparation. The aqueous mixture (suspension) M, which was continuously stirred at 60°C (also during spray-drying) using a stirrer (40 rpm), was spray-dried in a spray tower (type S-50-N / R from Niro A / S, made of stainless steel 1.4541) with a centrifugal atomizer type FS-15 and an atomizer wheel type AM8-150 in hot air cocurrent (gas inlet temperature: 350 ± 10°C, gas outlet temperature: 140 ± 5°C, gas flow rate: 2200 ± 100 Nm 3 / h, speed of the atomizer wheel: 20000 rpm). The resulting spray powder was stored in hermetically sealed containers (200 l or 1000 l internal volume, 25°C, atmospheric pressure) for 10 calendar days until further processing; shorter or longer intermediate storage (up to 30 calendar days) had no effect on the resulting results. The loss on ignition of the resulting spray powder (calcined for 3 h at 600°C (powder temperature) in stagnant, excess air) was 31 ± 2 wt.% of its initial weight. The spray powder had a D50 of 35 ± 10 pm (D50 means that 50% of the particles are smaller than the specified value) at a dispersion pressure of 2.0 bar absolute. f) Production of ring-like precursor molded bodies 100 kg of spray powder and 1 kg of graphite (grade 3160 from Asbury Graphite Mills Inc., New Jersey 08802) were then placed in an inclined mixer (type VIL, filling volume: 200 l, Aachener Misch- und Knetmaschinenfabrik) with mixing and cutting blades (speed of mixing blades: 39 rpm, speed of cutting blades: 3000 rpm) and premixed for 5 minutes. The resulting mixture was then compacted in a K200 / 100 compactor from Hosokawa Bepex GmbH with concave, grooved smooth rollers (roll diameter 100 mm, roll length 200 mm, gap width: 2.8 mm, roll speed: 5 rpm, press force target value: 80 kN, length-specific press force target value: 8 kN / cm). A compact with a particle size mostly between 200 pm and 1.5 mm was isolated using integrated vibrating screens from Allgaier (oversize screen size: 1.5 mm, undersize screen size: 200 pm) with ball screen aids (diameter 22 mm). For tabletting, an additional 2.5 wt.% of graphite (grade 3160 from Asbury Graphite Mills Inc., New Jersey 08802) was added to the compact within 2 minutes in a Drais turbulent mixer. The produced granules were then milled using a Korsch XT-600 rotary runner (with 65 EURO B dies) under a dry air atmosphere to form ring-like precursor bodies of geometry A x H x I = 5 mm x 5 mm x 2 mm with a non-curved (i.e. planar) end face of a mass (M v ) of 188 mg. The applied pre-compression force was 0.7 kN, the applied main compression force was 2.7 kN. The rotor speed was 40 rpm. The side crushing strength (SDF V ) of the resulting ring-like precursor bodies was 23 N. g) Thermal pretreatment and calcination of the ring-like precursor bodies produced in f) The formed rings were placed on the belt of a belt calciner (as described in WO 2002 / 024620) with eight chambers (chamber width 100 cm, chamber length 150 cm). Chambers 1 to 8 each had a fan to generate air circulation and were thermostatted at 150°C, 190°C, 220°C, 265°C, 380°C, 430°C, 520°C, and 520°C, respectively. Heated air was metered into each chamber. The amount of supply air to chambers 1 to 8 was 90 Nm each. 3 / h, 130 Nm 3 / h, 255 Nm 3 / h, 90 Nm 3 / h, 150 Nm 3 / h, 90 Nm 3 / h, 90 Nm 3 / h and 140 Nm 3 / h. Exhaust air was removed from each chamber using a fan. The amount of exhaust air to chambers 1 to 8 was 130 Nm each. 3 / h, 290 Nm 3 / h, 305 Nm 3 / h, 144 Nm 3 / h, 135 Nm 3 / h, 80 Nm 3 / h, 80 Nm 3 / h and 130 Nm 3 / h. The bed height of chambers 1 to 4 was 40 mm. The bed height of chambers 5 to 8 was 75 mm. Within the chambers, the temporal and spatial temperature deviation from the setpoint was always < 10°C. The belt speeds were such that the residence time in the first four chambers was 105 minutes each and in the fifth to eighth chambers was 270 minutes each. In this way, 2.6 t of full catalyst moldings K1 were produced. Example 2 (not according to the invention) Preparation of the full catalyst body K2, wherein the active multimetal oxide had the stoichiometry Mo^CoyFesBio.eSii.ßKo.osOx. The preparation of the unsupported catalyst bodies K2 was carried out in the same way as the preparation of the unsupported catalyst bodies K1 with a modification in f). The precursor bodies were heated to a mass (M v) of 220 mg. The applied pre-compression force (compression force) was 1.3 kN, the applied main compression force (compression force) was 6.8 kN. The lateral crush strength (SDF V ) of the resulting ring-like precursor bodies was 48 N. Example 3 Preparation of the full catalyst body K3, wherein the active multimetal oxide had the stoichiometry Mo^CoyFesBio.eSii.ßKo.osOx. The preparation of the unsupported catalyst bodies K3 was carried out in the same way as the preparation of the unsupported catalyst bodies K1 with modifications in f) and g). The produced granulate was formed in f) using a Kilian E150+ rotary press (with 21 EURO D dies) under dry air atmosphere to form ring-like precursor bodies of geometry A x H x I = 5 mm x 3 mm x 2 mm with a non-curved (i.e. planar) end face of a mass (M v) of 90 mg. The rotor speed was 25 rpm. The lateral crushing strength (SDFv) of the resulting ring-like precursor bodies was 6 N. 1000 g of the precursor molded bodies produced in f) were evenly distributed among four adjacent grids, each with a base area of ​​150 mm x 150 mm (piling height: 15 mm), placed in a forced-air shaft furnace (Nabertherm GmbH, D-28865 Lilienthal; furnace model S60 / 65A) through which 4500 Nl / h of previously dried air (which had an inlet temperature of 140 °C) flowed (the forced-air furnace was located in an environment with a temperature of 25 °C). Subsequently, while maintaining the air flow (including its inlet temperature), the temperature in the forced-air shaft furnace was varied as follows (the temperature data refer to the temperature in the respective applied bulk material; this was determined using four thermocouples, each located in the geometric center of the four grids in the center of the bulk material applied to the respective grid; one of the thermocouples provided the actual value for temperature control of the (The temperature was measured using a conventional forced-air shaft furnace; the other thermocouples confirmed that the temperatures were identical within the interval ± 0.1 °C.) The temperature increases were essentially linear over time. Heating took place from 25 °C to 130 °C within 72 minutes. 130 °C was held for 72 minutes before the temperature was increased to 190 °C within 36 minutes. 190 °C was held for 72 minutes before the temperature was increased to 220 °C within 36 minutes. 220 °C was held for 72 minutes before the temperature was increased to 265 °C within 36 minutes. 265 °C was held for 72 minutes before the temperature was increased to 380 °C within 93 minutes. 380 °C was held for 187 minutes before the temperature was increased to 430 °C within 93 minutes. The temperature was maintained at 430°C for 187 minutes before being increased to the final calcination temperature of 500°C within 93 minutes. This temperature was maintained for 463 minutes.The furnace was then cooled to 25°C within 12 hours. For this purpose, both the heating of the forced-air shaft furnace and the air flow preheater were switched off (however, the air flow of 4500 Nl / h was maintained; the inlet temperature of the air flow was then 25°C). Example 4 (not according to the invention) Preparation of the full catalyst body K4, wherein the active multimetal oxide had the stoichiometry Mo^CoyFesBio.eSii.ßKo.osOx. The preparation of the unsupported catalyst bodies K4 was carried out in the same way as the preparation of the unsupported catalyst bodies K3 with a modification in f). The precursor bodies were heated to a mass (M v ) of 122 mg. The lateral crushing strength (SDFv) of the resulting ring-like precursor bodies was 22 N. Example 5 Preparation of the full catalyst body K5, where the active multimetal oxide has the stoichiometry Moi2Co8.3Fe2.iBio,6Sii,6Ko,o80 x had. The stirred vessels used were filled in the presence of ambient air. During stirring / mixing, they were sealed hermetically with a lid that had a pressure relief valve to the atmosphere (1.01 bar). a) Preparation of an aqueous solution B In a temperature-controlled cylindrical stirred vessel (1.75 m 3 654 kg of demineralized water were placed in a stainless steel (EN 1.4541) (internal volume, 1.3 m diameter) and heated to 60°C while stirring (70 rpm). Subsequently, 0.36 kg of an aqueous potassium hydroxide solution (47.5 wt.% KOH) at a temperature of 20°C was added over one minute while stirring continuously and maintaining a temperature of 60°C. 80.4 kg of fine-grained ammonium heptamolybdate tetrahydrate (54.3 wt.% Mo, supplier: NIPPON INORGANIC COLOUR & CHEMICAL CO., LTD., 3-14-1 Funado ltabashi-ku Tokyo 174-0041 Japan), at a temperature of 25°C, were stirred in portions while stirring continuously and the resulting aqueous solution (slightly turbid due to minimal insoluble isopolymolybdate impurities) was stirred at 60°C for 60 minutes (70 rpm). b) Preparation of an aqueous solution A In a temperature-controlled cylindrical stirred vessel (1.75 m 3148.4 kg of an aqueous nitric acid cobalt(II) nitrate solution (12.5 wt% Co, 27 wt% nitrate, prepared by dissolving cobalt metal from MFT Metals % Ferro-Alloys Trading GmbH, D-41474 Viersen, purity > 99.6 wt% Co, < 0.3 wt% Ni, < 100 mg / kg Fe, < 50 mg / kg Cu ​​in aqueous nitric acid) were placed in a stainless steel (EN 1.4541) (internal volume, 1.3 m diameter) and heated to 60°C while stirring (70 rpm). With continued stirring (70 rpm) and continued tempering at 60°C, 32.3 kg of a 60°C warm iron(III) nitrate nonahydrate melt (13.8 wt% Fe, <0.4 wt% alkali metals, <0.01 wt% chloride, <0.02 wt% sulfate, from Dr. Paul Lohmann GmbH, D-81857 Emmerthal) were added and stirred for 30 minutes at 60°C (70 rpm). To the resulting aqueous solution, 42.8 kg of a 60°C warm, aqueous, nitric acid bismuth nitrate solution (11.1 wt.% Bi, 13 wt.% nitrate (NO 3- ), prepared by dissolving bismuth metal from Sidech SA, BE-1495 Tilly, purity > 99.997 wt.% Bi, < 7 mg / kg Pb, < 5 mg / kg each of Ni, Ag, Fe, < 3 mg / kg each of Cu, Sb and < 1 mg / kg each of Cd, Zn in aqueous nitric acid) and then stirred for a further 30 minutes at 60°C (70 rpm). c) Mixing of aqueous solution A with aqueous solution B The 60°C warm aqueous solution A was continuously added over 15 minutes to the intensively stirred (70 rpm) 60°C warm aqueous solution B. The resulting aqueous suspension was stirred for a further 15 minutes at 60°C. d) Addition of a silica sol to obtain an aqueous mixture M After stirring was complete, 7.4 kg of LUDOX TM50 silica gel (47.5 wt% SiO2) heated to 60°C from Grace GmbH & KG, In der Hollerecke 1, D-67545 Worms, Germany, were immediately added to the aqueous mixture obtained in c). e) Spray drying of the aqueous mixture M The aqueous mixture M was spray-dried immediately after its preparation. The aqueous mixture (suspension) M, which was continuously stirred at 60°C (also during spray-drying) using a stirrer (40 rpm), was spray-dried in a spray tower (type S-50-N / R from Niro A / S, made of stainless steel 1.4541) in a hot air cocurrent flow (gas inlet temperature: 350 ± 10°C, gas outlet temperature: 140 ± 5°C, gas flow rate: 2200 ± 100 Nm³). 3 / h, speed of the atomizer wheel: 20000 rpm). The resulting spray powder was stored in hermetically sealed containers (200 l or 1000 l internal volume, 25°C, atmospheric pressure) for 10 calendar days until further processing; shorter or longer intermediate storage (up to 30 calendar days) had no effect on the resulting results. The loss on ignition of the resulting spray powder (calcined for 3 h at 600°C (powder temperature) in stagnant, excess air) was 31 ± 2 wt.% of its initial weight. The spray powder had a D50 of 35 ± 10 pm (D50 means that 50% of the particles are smaller than the specified value) at a dispersion pressure of 2.0 bar absolute. f) Production of ring-like precursor molded bodies 100 kg of spray powder and 1 kg of graphite (grade 3160 from Asbury Graphite Mills Inc., New Jersey 08802) were then mixed in an inclined mixer (type VIL, filling volume: 200 l, Aachener Misch- und Kneading Machine Factory) with mixing and cutting blades (speed of mixing blades: 39 ll / min, speed of cutting blades: 3000 ll / min) and premixed for 5 minutes. The resulting mixture was then compacted in a K200 / 100 compactor from Hosokawa Bepex GmbH with concave, grooved smooth rollers (roll diameter 100 mm, roll length 200 mm, gap width: 2.8 mm, roll speed: 5 l / min, press force target value: 80 kN, length-specific press force target value 8 kN / cm). A compact with a particle size mostly between 200 pm and 1.5 mm was isolated using integrated vibrating screens from Allgaier (oversize screen size: 1.5 mm, undersize screen size: 200 μm) with ball sieving aids (diameter 22 mm). For tabletting, an additional 2.5 wt.% of graphite (grade 3160 from Asbury Graphite Mills Inc., New Jersey 08802) was added to the compact within 2 minutes in a Drais turbulent mixer. The granules produced as described were then compacted (tableted) using a Kilian E150+ rotary runner (with 21 EURO D dies) in a dry air atmosphere to form ring-like precursor bodies with the dimensions A x H x I = 5 mm x 3 mm x 2 mm and a non-curved (i.e., planar) end face with a mass (Mv) of 102 mg. The rotor speed was 25 rpm. The lateral crushing strength (SDF) V ) of the resulting ring-like precursor bodies was 12 N. g) Thermal pretreatment and calcination of the ring-like precursor bodies produced in f) 1000 g of the produced precursor molded bodies were evenly distributed onto four adjacent grids each with a base area of ​​150 mm x 150 mm (piling height: 15 mm) in a forced-air shaft furnace (Nabertherm GmbH, D-28865 Lilienthal; furnace model S60 / 65A) through which 4500 Nl / h of previously dried air (which had an inlet temperature of 140°C) flowed (the forced-air furnace was located in an environment with a temperature of 25°C).Subsequently, while maintaining the air flow (including its inlet temperature), the temperature in the forced-air shaft furnace was varied as follows (the temperature specifications refer to the temperature in the respective applied bulk material; this was determined using four thermocouples, each located at the geometric center of the four grids in the center of the bulk material applied to the respective grid; one of the thermocouples provided the actual value for temperature control of the forced-air shaft furnace; the other thermocouples confirmed that the temperatures were identical within the interval ± 0.1 °C). The temperature increases occurred essentially linearly over time. Within 72 minutes, the temperature increased from 25 °C to 130 °C. The 130 °C was maintained for 72 minutes before the temperature was increased to 190 °C within 36 minutes.The 190°C was held for 72 minutes before the temperature was increased to 220°C within 36 minutes. The 220°C was held for 72 minutes before the temperature was increased to 265°C within 36 minutes. The 265°C was held for 72 minutes before the temperature was increased to 380°C within 93 minutes. The 380°C was held for 187 minutes before the temperature was increased to 430°C within 93 minutes. The 430°C was held for 187 minutes before the temperature was increased to the final calcination temperature of 500°C within 93 minutes. This was maintained for 463 minutes. Then the temperature was cooled to 25°C within 12 hours. For this purpose, both the heating of the circulating air shaft furnace and the air flow preheater were switched off (however, the air flow of 4500 Nl / h was maintained as such; the inlet temperature of the air flow was then 25°C). Example 6 (not according to the invention) Preparation of the full catalyst body K6, where the active multimetal oxide has the stoichiometry Moi2Co8.3Fe2.iBio,eSii,6Ko,o80 x had. The preparation of the unsupported catalyst bodies K6 was carried out in the same way as the preparation of the unsupported catalyst bodies K5 with a modification in f). The precursor bodies were heated to a mass (M v ) of 119 mg. The lateral crushing strength (SDFv) of the resulting ring-like precursor bodies was 26 N. Example 7 Preparation of the full catalyst body K7, where the active multimetal oxide has the stoichiometry Moi2Co8.3Fe2.iBio,eSii,6Ko,o80 x had. The preparation of the unsupported catalyst bodies K7 was carried out in the same way as the preparation of the unsupported catalyst bodies K5 with a modification in f). The resulting granules were compacted (tableted) in step f) using a Korsch PH 865 rotary press (with 65 dies) under dry air to form ring-like precursor bodies with a geometry of A x H x I = 5 mm x 5 mm x 2 mm and a non-curved (i.e., planar) end face with a mass (Mv) of 166 mg. The rotor speed was 40 rpm. The lateral compressive strength (SDFv) of the resulting ring-like precursor bodies was 10 N. Example 8 Preparation of the full catalyst body K8, where the active multimetal oxide has the stoichiometry Moi2Co8.3Fe2.iBio,eSii,6Ko,o80 x had. The preparation of the unsupported catalyst bodies K8 was carried out in the same way as the preparation of the unsupported catalyst bodies K7 with a modification in f). The precursor molded bodies were heated to a mass (M v ) of 185 mg. The lateral crush strength (SDF V) of the resulting ring-like precursor bodies was 16 N. Example 9 (not according to the invention) Preparation of the full catalyst body K9, where the active multimetal oxide has the stoichiometry Moi2Co8.3Fe2.iBio,eSii,6Ko,o80 x had. The preparation of the unsupported catalyst bodies K9 was carried out in the same way as the preparation of the unsupported catalyst bodies K7 with a modification in f). The precursor bodies were heated to a mass (M v ) of 205 mg. The lateral crushing strength (SDFv) of the resulting ring-like precursor bodies was 26 N. Example 10 (not according to the invention) Preparation of the full catalyst body K10, where the active multimetal oxide has the stoichiometry [Bi2W20g 2WO5]o.4o x [Moi2Co5,4Fe3,iSii,5Ko,o80 x ]i. The preparation of the unsupported catalyst bodies K10 was carried out according to Example I of WO 2010 / 000720. The ring-like precursor bodies of geometry A x H x I = 5 mm x 5 mm x 2 mm with non-curved (i.e. planar) end face had a mass (Mv) of 129 mg. Testing of the prepared ring-shaped catalysts K1 to K10 for a heterogeneously catalyzed partial oxidation of propene to acrolein and acrylic acid: For the all-solid catalyst bodies K1 to K6, a reaction tube (stainless steel type 1.4541 (EU standard number EN 10088-3); 33.7 mm outer diameter; 2 mm wall thickness; 29.7 mm inner diameter; 400 cm length, 4 mm thermal sleeve) was used. For the all-solid catalyst bodies K7 to K10, a reaction tube (stainless steel type 1.4541 (EU standard number EN 10088-3); 30 mm outer diameter; 2 mm wall thickness; 26 mm inner diameter; 400 cm length, without thermal sleeve) was used. The respective reaction tube was loaded from bottom to top as follows: Section 1 : 60 cm length Pre-filling of steatite rings with a geometry of 7 mm x 3 mm x 4 mm (outer diameter x length x inner diameter; Steatite C220 from CeramTec); Reaction zone: consisting of 2 sections (see Table 3; zone 1 is closest to the reactor inlet) Section 2: 30 cm length Refill from the same steatite rings as in section 1 ; Section 3: Empty pipe The structure of the reaction zone is shown in Table 3. To adjust the relative volume-specific catalyst activity, solid catalyst bodies were diluted with inert steatite rings of the geometry 5 mm x 3 mm x 2 mm (outer diameter x length x inner diameter, C220 steatite from CeramTec) or the geometry 5 mm x 5 mm x 2 mm (outer diameter x length x inner diameter, C220 steatite from CeramTec). A reaction gas mixture containing the following contents was passed through the reaction tube charged as described above, flowing from top to bottom: 5.8 to 6.4 vol% propene, 1.5 to 3 vol% H2O, 0.2 to 0.5 vol% CO, 0.6 to 1.0 vol.% CO2, 0.02 to 0.05 vol% acrolein, 10.2 to 11.7 vol.% O2 and the remainder to 100% molecular nitrogen. The reaction tube was surrounded along its length by a stirred and externally electrically heated salt bath (mixture of 53 wt.% potassium nitrate, 40 wt.% sodium nitrite and 7 wt.% sodium nitrate; 50 kg molten salt) (the flow velocity at the tube was 3 m 3 / h (in the plane perpendicular to the longitudinal axis of the pipe)). The temperature in the catalyst bed of the full catalysts K1 to K6 was measured by a thermocouple, which was placed in a thermowell located inside the reactor tube and pushed from the bottom to the top in the reactor bed by means of a traction machine. was measured continuously. The maximum temperature of this measurement corresponded to the hot spot temperature T H . The drop test in this document is carried out as follows: 50 g of unsupported catalyst bodies are dropped through a 3.5 m long vertical tube with a clear diameter of 23 mm. The unsupported catalyst bodies fall into a porcelain bowl positioned directly below the tube and are separated from the dust and debris generated upon impact. The intact unsupported catalyst bodies, separated from the dust and debris, are weighed. The proportion of broken unsupported catalyst bodies is determined by comparing the mass determined in this way with the mass of the unsupported catalyst bodies used. The proportion of broken unsupported catalyst bodies is a measure of the mechanical strength of the unsupported catalyst bodies. In this document, the selectivity of the formation of the desired product (S (mol%)) is understood as: Number of moles of propene converted to acrolein and acrylic acid x 100 S = - Total number of moles of propene converted (the conversion figures are based on a single pass of the reaction gas mixture through the fixed catalyst bed). A comparison of the respective example pairs E1 / E2, E3 / E4, and E5 / E6, as well as a comparison of examples E7 and E8 with examples E9 and E10, reveals significantly higher desired product selectivity and a significantly higher desired product yield (with lower catalyst mass) of the unsupported catalyst bodies according to the invention. At the same time, the unsupported catalyst bodies according to the invention exhibit sufficient mechanical stability. Table 1: Precursor molded body / full catalyst molded body ) Comparative example weight loss Weight loss during thermal treatment DFv Lateral compressive strength Table 2: Solid catalyst moldings ) Comparison example ET = BET surface area V = total pore volume of pores with a diameter of >0.03 to <300 pm V (0.01-0.1) = volumetric proportion of pores with a diameter of >0.01 to <0.1 pm in the total pore volume V (0.1-1) = volumetric proportion of pores with a diameter of >0.1 to <1 pm in the total pore volume V (1-10) = volumetric proportion of pores with a diameter of >1 to <10 pm in the total pore volume V (10-300): = volumetric proportion of pores with a diameter of >10 to <300 pm in the total pore volume Table 3: Filling of the reaction tubes ) Comparison example Table 4: Reaction conditions / yield ) Comparison example Pipe load Quotient of propene flow rate (Nl / h) and empty pipe volume of the reaction zone (I) selectivity Selectivity of the valuable product (acrolein + acrylic acid) Yield Yield of the valuable product (acrolein + acrylic acid)

Claims

Patent claims 1. A process for the production of unsupported catalyst bodies for the gas-phase oxidation of an aldehyde and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein the unsupported catalyst bodies comprise at least the elements molybdenum, bismuth, iron, and cobalt, wherein a) an aqueous solution or aqueous suspension is produced from at least one source of the elemental constituents molybdenum, bismuth, iron, cobalt, and optionally at least one source of the elemental constituent nickel, b) a powder P is produced by drying the aqueous solution or aqueous suspension obtained in a) and optionally comminuting, c) the powder P obtained in b), optionally with the addition of one or more auxiliaries and after uniform mixing and optionally compacting, is compacted to form precursor bodies with a cylindrical structure,and d) the precursor shaped bodies obtained in c) are thermally treated to form the unsupported catalyst shaped bodies, characterized in that the pressure during the compaction in c) is selected such that the density of the precursor shaped bodies is from 1.70 to 2.30 g / cm, 3 wherein the density of the precursor shaped bodies is the quotient of the mass and the geometric volume, and the weight loss during the thermal treatment in d) is from 25 to 40 wt.%.

2. Method according to claim 1, characterized in that the cylindrical structure is i) a cylindrical body with a circular through-opening in the center of the longitudinal direction or ii) a cylindrical body with three circular through-openings uniformly arranged in the longitudinal direction.

3. Process according to claim 1 or 2, characterized in that the molybdenum content of the unsupported catalyst bodies, calculated as molybdenum, is from 45 to 75% by weight.

4. Process according to one of claims 1 to 3, characterized in that the bismuth content of the unsupported catalyst bodies, calculated as Bi2O3, is from 1 to 20 wt.%.

5. Process according to one of claims 1 to 4, characterized in that the iron content of the unsupported catalyst bodies, calculated as Fe2O3, is from 2 to 12 wt.%.

6. Process according to one of claims 1 to 5, characterized in that the content of cobalt and nickel, calculated as CoO and NiO, in the unsupported catalyst bodies is in total from 9 to 30 wt.%.

7. A shaped catalyst body having a cylindrical structure for the gas phase oxidation of an aldehyde and / or an alcohol to an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, obtainable by a process according to claims 1 to 6, wherein the shaped catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, wherein the density of the shaped catalyst body is from 1.20 to 1.70 g / cm 3 where the density of the unsupported catalyst body is the quotient of the mass and the geometric volume, the total pore volume of the unsupported catalyst body is from 0.33 to 0.60 cm 3 / g and the pore volume of the full catalyst body in the range of 0.1 to 1 pm is from 85 to 99% of the total pore volume, wherein the total pore volume and the pore volume in the range of 0.1 to 1 pm are determined by mercury porosimetry.

8. The unsupported catalyst molded body according to claim 7, wherein the cylindrical structure is i) a cylindrical body having a circular through-opening located centrally in the longitudinal direction or ii) a cylindrical body having three circular through-openings uniformly arranged in the longitudinal direction.

9. The unsupported catalyst body according to claim 8, wherein the shortest distance between the outer wall of the cylindrical body and the nearest through opening is from 0.75 to 2.5 mm.

10. Unsupported catalyst body according to one of claims 7 to 9, wherein the density of the unsupported catalyst body is from 1.35 to 1.55 g / cm 3 amounts.

11. Unsupported catalyst body according to one of claims 7 to 10, wherein the total pore volume of the unsupported catalyst body is from 0.36 to 0.45 cm 3 / g.

12. Unsupported catalyst body according to one of claims 7 to 11, wherein Unsupported catalyst body according to one of claims 7 to 9, wherein the pore volume of the unsupported catalyst body is in the range of 0.1 to 1 pm from 88 to 96% of the total pore volume 13. A process for preparing an α,β-unsaturated aldehyde and / or an α,β-unsaturated carboxylic acid, wherein an alkene and / or an alcohol is passed with molecular oxygen over a fixed catalyst bed comprising a bed of unsupported catalyst bodies according to one of claims 7 to 12.

14. Process according to claim 13, characterized in that the propene is used as alkene.

15. Fixed-bed reactor containing a bed of unsupported catalyst bodies according to one of claims 7 to 12.

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