Inorganic fibre-containing multielement shaped unsupported catalyst body for preparation of unsaturated aldehydes and unsaturated carboxylic acids, process for production thereof, and use thereof in gas phase oxidation

Abstract

The invention relates to a shaped unsupported catalyst body for preparation of unsaturated aldehydes and unsaturated carboxylic acids, wherein the shaped unsupported catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, wherein the shaped unsupported catalyst body comprises inorganic fibres having an average fibre length of 10 µm to 1 mm and an average fibre diameter of 1 µm to 30 µm, and the shaped unsupported catalyst body has a total pore volume of 0.37 to 0.65 ml / g, the total pore volume being determined by mercury porosimetry.

Description

Inorganic fiber-containing multi-element full catalyst molded body for the production of unsaturated aldehydes and unsaturated carboxylic acids; its production process and use in gas-phase oxidation Description The present invention relates to unsupported catalyst bodies for the production of unsaturated aldehydes and unsaturated carboxylic acids, wherein the unsupported catalyst body comprises at least the elements molybdenum, bismuth, iron, and cobalt, and the unsupported catalyst body has inorganic fibers and a total pore volume of 0.37 to 0.65 ml / g. Furthermore, the present invention relates to a process for producing an unsupported catalyst body according to the invention. 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 2015 / 067659 describes hollow cylindrical shaped catalyst bodies with a defined geometry. These 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. EP 0574895, EP 1243331, JP 2011177616, WO 2012 / 036038, WO 2012 / 073584, CN 103861608, WO 2014 / 175113 and JP2019171335 describe the use of fibers in unsupported catalyst moldings. None of the above-mentioned publications attaches any importance to high catalyst activity combined with high mechanical stability. The object of the present invention was therefore to provide improved unsupported catalyst bodies for the production of unsaturated aldehydes and unsaturated carboxylic acids. The catalysts should exhibit high catalytic activity and mechanical stability. Accordingly, a shaped catalyst body for the production of unsaturated aldehydes and unsaturated carboxylic acids is provided, wherein the shaped catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, optionally nickel and potassium, characterized in that the shaped catalyst body contains inorganic fibers with an average fiber length of 10 m to 1 mm and an average fiber diameter of 1 pm to 30 pm and the unsupported catalyst molded body has a total pore volume of 0.37 to 0.65 ml / g, wherein the total pore volume is determined by mercury porosimetry. The unsupported catalyst shaped body preferably has a total pore volume of 0.39 to 0.60 ml / g, preferably of 0.40 to 0.55 ml / g, more preferably of 0.41 to 0.50 ml / g. The inorganic fibers are preferably glass fibers, aluminum oxide fibers, silica fibers, carbon fibers, asbestos, silicon carbide, potassium titanate, or a mixture of the aforementioned fibers. The inorganic fibers are particularly preferably glass fibers. The inorganic fibers preferably have an average fiber length of 25 pm to 750 pm, preferably of 50 pm to 500 pm, more preferably of 75 pm to 400 pm, particularly preferably of 100 pm to 300 pm. The inorganic fibers preferably have an average fiber diameter of 3 pm to 18 pm, preferably of 5 pm to 15 pm, more preferably of 8 pm to 12 pm. Preferably, the composition of the unsupported catalyst body corresponds to the general formula I Moi2Bi a FebCo c NidX e YfZgOn (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, where 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, and n = a number determined by the valence and frequency of the elements other than oxygen in the general formula I. Preferably, in the general formula IX = K, a = 0.4 to 0.8, b = 2.2 to 3.2, c = 4.7 to 7.9, d = 0 to 2.8, c + d = 7.3 to 8.0, e = 0.02 to 0.16, f = 0, g = 0. The unsupported catalyst shaped body preferably contains from 0.1 to 15 wt.%, preferably from 0.5 to 13 wt.%, more preferably from 1.0 to 11 wt.%, particularly preferably from 2 to 10 wt.%, especially preferably from 2.5 to 9 wt.%, particularly preferably from 3 to 8 wt.%, of inorganic fibers, based on the weight of the unsupported catalyst shaped body. Preferably, the pore volume of the unsupported catalyst shaped body is in the range from 0.1 to 1 pim from 85 to 99%, preferably from 86 to 98%, more preferably from 87 to 97%, particularly preferably from 88 to 96%, most preferably from 89 to 95% of the total pore volume, wherein the pore volume in the range from 0.1 to 1 pim is determined by mercury porosimetry. Preferably, the unsupported catalyst body is a tableted unsupported catalyst body. The tableted unsupported catalyst body preferably has a density of 1.20 to 1.45 g / ml, preferably of 1.22 to 1.43 g / ml, more preferably of 1.24 to 1.41 g / ml, particularly preferably of 1.26 to 1.39 g / ml, wherein the density of the unsupported catalyst body is the quotient of the mass and the geometric volume. The geometric volume is the macroscopic volume of the precursor molded 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. The invention further provides a process for producing a shaped unsupported catalyst body for the production of unsaturated aldehydes and unsaturated carboxylic acids, wherein the shaped unsupported catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, optionally nickel and potassium, 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 constituents nickel and potassium, b) a powder P is produced by drying the aqueous solution or aqueous suspension obtained in a) and optionally comminuting it, c) a powder mixture PM is produced by mixing the powder P obtained in b) with inorganic fibers, d) the powder mixture PM obtained in c), optionally with the addition of one or more auxiliaries and after uniform mixing and optional precompacting, is compacted to form precursor shaped bodies having a cylindrical structure, and e) the precursor shaped bodies obtained in d) are thermally treated to form the unsupported catalyst shaped bodies, characterized in that the pressure during the compaction in d) is selected such that the density of the precursor shaped bodies is from 1.65 to 2.20 g / ml, the density of the precursor shaped bodies being the quotient of the mass and the geometric volume, and the weight loss during the thermal treatment in e) is from 15 to 50 wt.%. The geometric volume is the macroscopic volume of the precursor molded 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. Preferably, the pressure during compaction in d) is selected such that the density of the precursor shaped bodies is from 1.70 to 2.15 g / ml, preferably from 1.75 to 2.10 g / ml, more preferably from 1.80 to 2.00 g / ml, particularly preferably from 1.81 to 1.98 g / ml, especially preferably from 1.82 to 1.96 g / ml. The weight loss during the thermal treatment in e) is preferably from 20 to 45 wt.%, preferably from 25 to 40 wt.%, more preferably from 26 to 39 wt.%, particularly 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. Preferably, the mixing carried out in c) is a dry mix. Preferably, the dry powder P and the dry inorganic fibers are mixed together to form the powder mixture PM. Preferably, the compaction carried out in d) is tabletting. 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 nearest 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, very particularly preferably from 1.2 to 1.7 mm, and 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. Preferably, the composition of the unsupported catalyst body obtained by the process according to the invention corresponds to the general formula I Moi2Bi a Fe b Co c NidX e YfZgOn (I) with X = K, Cs and / or Rb, Y = Ca, Sr, Ba, Li, Na, Or, 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, where 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, and n = a number determined by the valence and frequency of the elements other than oxygen in the general formula I. Preferably, in the general formula IX = K, a = 0.4 to 0.8, b = 2.2 to 3.2, c = 4.7 to 7.9, d = 0 to 2.8, c + d = 7.3 to 8.0, e = 0.02 to 0.16, f = 0, g = 0. The invention further provides a process for preparing unsaturated aldehydes and unsaturated carboxylic acids, wherein an alkene and / or an alcohol with molecular oxygen is passed over a fixed catalyst bed comprising a bed of unsupported shaped catalyst bodies according to the invention. A further subject of the invention is a fixed bed reactor containing a bed of unsupported catalyst bodies according to the invention. The invention further relates to the use of unsupported catalyst bodies according to the invention in a gas phase oxidation of an alkyne and / or an alcohol. The features disclosed here for the unsupported catalyst shaped body according to the invention are to be deemed to be disclosed, mutatis mutandis, also for the process according to the invention for producing the unsupported catalyst shaped body, the fixed bed reactor according to the invention and the use of the unsupported catalyst shaped body and vice versa. The present invention is based on the finding that by using inorganic fibers and simultaneously adjusting the total pore volume, precursor molded bodies with high catalytic activity and high mechanical stability can be produced, which are particularly suitable for fillings. 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) that is as intimate as possible, preferably finely divided, and composed according to the respective stoichiometry of the unsupported catalyst bodies to be produced. This mixture, after prior shaping to precursor bodies, which optionally takes place with the use of shaping aids, is calcined at temperatures of 350 to 650°C. The calcination can be carried out both under an inert gas and under 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 (for example a mixture of inert gas, NH3, CO and / or H2, which may also contain oxidizing components in comparatively smaller proportions). active components) or under vacuum. The calcination time can range from a few minutes to a few days and is usually shorter at elevated calcination temperatures. Suitable sources for the elemental constituents of the shaped unsupported catalyst bodies (i.e. starting compounds which contain at least one elemental constituent (at least one element present in the shaped unsupported catalyst body, chemically bound) are compounds which are already oxides (which are generally in the solid state under standard conditions (1 atm-abs, 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 full catalyst bodies. In addition to the oxides, such starting compounds (sources) include, in particular, halides, nitrates, formates, acetates, oxalates, citrates, carbonates, amine complexes, ammonium salts and / or hydroxides as well as hydrates of the aforementioned salts. Compounds such as NH4OH, (NH^COs, 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) at the latest during later calcination, can be additionally incorporated into the intimate dry mixture. 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.) can also be considered as substances that decompose during calcination. A formation (release) of gaseous compounds during the thermal treatment outlined is normally also present when the element sources used to produce the most intimate and preferably finely divided dry mixture 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 sources present in dissolved form and / or from colloidally dissolved sources of the elemental constituents. As already mentioned, a starting compound can be a source of only one or more elemental constituents. Accordingly, a solution or colloidal solution listed above can contain only one or more elemental constituents of the relevant unsupported catalyst body to be produced in dissolved form. The preferred solvent, as already mentioned, 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 meant 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 stability reasons, 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 NH 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 to produce 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-abs, 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 SiO2 particles contained in colloidal solution in LUDOX TM50 is 140 m 2 / g. The mass density (1 atm-abs, 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-abs, 25°C). The CF 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-abs 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 are, for example, ammonium orthomolybdate ((NH^MoO^), ammonium dimolybdate ((NH4)2MO2O2), ammonium tetramolybdate dihydrate ((NH4)2Mo4Oi3 x 2 H2O) and ammonium decamolybdate dihydrate ((NH4)4MOIQO32 x 2 H2O). In principle, molybdenum trioxide can also be used. 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, a solution of elemental Bi in aqueous nitric acid can also be used as a Bi source, 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-abs, 25°C) is low, since this is an undesirable development 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-) / (riBi3+) of the molar amount of NOr (UNO3-) contained in the aqueous solution to the molar amount of Bi3 contained in the aqueous solution + (nßi3+) > 3). Preferred Fe sources are salts of Fe 3+, among which the various iron(II) nitrate hydrates are particularly preferred (see, for example, DE 10 2007 003076 A1). According to the invention, iron(II) 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(III) nitrate. The former 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. Particularly suitable are 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 and the respective hydrates of these salts. Hydrates of nickel(II) nitrate (for example its hexahydrate) are particularly preferred as Ni sources. Of course, a solution of elemental Ni in aqueous nitric acid can also be used as Ni source, in which the nickel is present as Ni. 2+ Such solutions regularly also contain a certain amount of ammonium nitrate. 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, steam, and / or carbon dioxide). According to the invention, the preparation of a wet (e.g., aqueous) mixture M is preferably carried out in air. (the aqueous mixture M is advantageously 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-abs 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-abs 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)eMozO24 x 4 H2O), which is completely soluble in water at 25°C (1 atm-abs) 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. The temperatures of aqueous solution A, aqueous solution B, and the resulting aqueous mixtures are preferably constant throughout the described stirring process. For this purpose, thermostatting can be used, for example, with the aid of a water bath. The working pressure when stirring aqueous solution A into aqueous solution B is advantageously 1 atm-abs (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 the source of the same, whereby water can advantageously be added to this aqueous mixture prior to this stirring in. Advantageously, both the aqueous silica sol and the water can be added at once. be added. 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 expediently 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 wt.%, or 20 to 60 wt.%, or 30 to 60 wt.%, preferably 40 to 60 wt.%, and particularly preferably 45 to 55 wt.% (in each case based on its total weight). Instead of placing the aqueous solution B in a thermostatically controlled stirred vessel and then adding the aqueous solution A while stirring, both the aqueous solution B and the aqueous solution A can be continuously fed into the stirred vessel (for example, through a "3-way T-mixer"). In principle, the aqueous solution B can also be continuously stirred into an 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 + NH^ contained to molar amount of Mo contained); 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 the 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 present in the aqueous mixture M, dissolved in the aqueous medium of the aqueous mixture M, is <90 mol% and particularly preferably <90 mol%, or <70 mol% or <60 mol%. According to the invention, the total content of Bi, Fe, Mo, etc. in the aqueous mixture M to be dried (preferably spray-dried) is expediently 3 to 20 wt.%, advantageously 5 to 15 wt.%, based on the amount of the aqueous mixture M. As a rule, AT is >3 mol% or <50 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 be carried out 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 90 to 160°C. Spray drying preferably occurs in cocurrent flow of the droplets to the hot gas. The mean particle diameter of the resulting spray powder is typically 10 to 100 pim, preferably 15 to 60 pim and particularly preferably 25 to 50 pim (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 which 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-abs) 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 first be coarsened, for example, by subsequent precompacting. "Precompacting" means a preliminary compaction of the powder before subsequent compaction, which produces the precursor molded body. If the precompacting is carried out dry, finely divided graphite, for example, and the dry inorganic fibers and / or other shaping aids mentioned in this document (e.g., lubricants, reinforcing agents, and / or pore formers) can be mixed into the spray powder prior to precompacting. Mixing is carried out using a mixer, for example, a drum mixer, tumbler mixer, ribbon mixer, blade mixer, or intensive mixer, preferably with a mixer with a shearing action, for example, with a chopper. For example, precompaction can be carried out using a calender with two counter-rotating steel rollers. The precompacted material can then be reduced to the appropriate particle size for the intended further use. This can be achieved very simply, for example, by forcing the precompacted material through a sieve with a defined mesh size. In principle, precompacting 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 100 49 873 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 compaction (so-called tabletting) and then the full catalyst shaped bodies are produced by thermal treatment. Further fine-particle shaping aids that can be added to the fine-particle precursor mass before and / or during shaping include lubricants such as graphite, carbon black, polyethylene glycol, polyacrylic acid, stearic acid, starch, mineral oil, vegetable oil, water, boron trifluoride, and / or boron nitride. 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 during the thermal treatment, forming pores. The use of lubricants in the context of a corresponding shaping can be found, for example, in the documents DE 10 2007 004961 A1, WO 2008 / 087116, WO 2005 / 030393, US 2005 / 0131253, WO 2007 / 017431, DE 10 2007 005606 A1 and in DE 10 2008040093 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.%, frequently < 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 tabletting. The finely divided precursor mass (the finely divided intimate dry mixture) is preferably used in a touch-dry state. However, it can, for example, contain up to 10% of its total weight of substances that are liquid under standard conditions (25 °C, 1 atm-abs (1.01 bar)). The finely divided precursor mass (the finely divided intimate dry mixture) can 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 can 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 handbook of 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 include projecting pins to form internal passages. It is also possible to provide the press punches with a plurality of pins, so that one punch, for example, can be manufactured with four pins to produce molded bodies with four holes (passages). Typical design features of such press 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 are 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 sticking of the precursor shaped body occurs. 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 jamming of the powder in the gaps at the punch-die interface and the pin-hole interface (in tablet shapes with passages). 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 die 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 die 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 (die 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 outside of the punch, 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 toward the die top. The tapered portion of the die bore features a gradual increase in bore size toward the die top, creating additional clearance between the die bore wall and the sharp-edged outer side surface of the lower punch. The additional space facilitates the venting of 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 tapered dies is the ease of ejection after compaction.Compaction into a tablet at the point where the die bore is tapered 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, ejection of the tablet from the die wall occurs easily 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, detachment of the tablet from the die wall does not occur, 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 die wall. This friction leads to 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 in-die tablet height 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 punch face 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 punch face. 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, the 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, the detachment of the tablet from the pins does not occur, so the entire ejection process (i.e., pushing the tablet up from the depth at which the Compression on the upper face of the die) suffers from friction at the tablet-pin interfaces, resulting in high ejection forces. 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 oriented by summing the in-die tablet height before elastic recovery (i.e., 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 angle of the die taper 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 angle of the taper and the taper length. Industrial mass production of the 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 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 may 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. Generally, 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 located 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 Fitzpatrick Chilsonator®, 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 the documents WO 2005 / 030393, DE 10 2008040093 A1, DE 10 2008 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 a non-calcined green body and the full catalyst body resulting from it by calcination are normally essentially the same) is the geometry 5 mm x 5 mm x 2 mm (outer diameter x height (length) x inner diameter). This is because fixed catalyst beds made of rings of this geometry have a particularly low pressure drop during the fixed catalyst bed. flowing through the reaction gas mixture (particularly in reaction tubes with an internal 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 current intensity of the reaction gas mixture flowing through the fixed catalyst bed). Another preferred ring geometry (it has advantageous bulk behavior particularly in reaction tubes with a smaller internal diameter (for example 20 mm)) is the geometry 5 mm x 3 mm x 2 mm (external diameter x height (length) x internal diameter). Of course, all those geometries disclosed and recommended in WO 02 / 062737 and WO 2015 / 067656 are also suitable. 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 10 2008 040093 A1, DE 10 2008 040094 A1 and WO 2005 / 030393) the relation 5 N < SDF V s 100 N, preferably 8 N < SDF V 80 N, and particularly preferably 12 N < SDF V s 50 N is fulfilled. 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 10 2008 040093 A1, are particularly preferred according to the invention. The end faces of ring-shaped or ring-like molded bodies can be (both or only one of the two end faces) flat or convex (curved) outwards (cf. in particular DE 10 2007 004961 A1, EP 0 184 790 A2, DE 10 2008 040093 A1 (for example, its paragraph

[0032] ) and DE 10 200804009 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 flow rate 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) Z 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, it is advantageous for ring-shaped or ring-like green compacts according to the invention 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 regarding total pore volumes and pore diameter distributions based on these total pore volumes is based on determinations using the mercury porosimetry method using the Auto Pore V 9600 instrument (MicroActive Interactive Dara Analysis Software) from Micromeritics GmbH, D-52072 Aachen (range: 0.5 - 60,000) at 23°C (evaluation using the Washburn equation, assuming a mercury contact angle of 140° and a mercury surface tension of 480 mN / m = 480 dyn / cm). The total pore volume here refers to the total pore volume of pores with a diameter of >0.03 to <300 pm. 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 measurements 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, if possible, in the absence of ambient air (containing humidity) (preferably storage takes place until Calcination 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 air humidity) (e.g. under an atmosphere of ^). 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 > 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 time is usually more than 0.5 hours, and frequently more than 2 hours. Calcination times usually do not exceed 45 hours or 30 hours. The total calcination time is often less than 25 hours. Generally, a shorter calcination time is sufficient at higher calcination temperatures than at lower temperatures. Calcination temperatures. In an advantageous embodiment of the calcination according to the invention, 550°C is not exceeded, and the calcination time 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 material (e.g., a green compact) 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 methane). Of course, 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 pim 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 pim 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 pim 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 having 3 to 6 carbon atoms (partial oxidations are to be understood in this document as meaning, 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 to be understood in this document as encompassing 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 (isobutene and / or tert-butanol) to acrolein (methacrolein) forms the first stage of a two-stage heterogeneously catalyzed partial gas phase oxidation of propene (isobutene and / or tert-butanol) to acrylic acid (methacrylic acid), as described by way of 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 10 2007 004961 A1, WO 02 / 49757, WO 02 / 24620, DE 10 2008 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 10 2008 042060 A1, WO 2008 / 087116, DE 10 2010 048405 A1, DE 10 2009 047291 A1, DE 10 2008 042064 A1, DE 10 2008042061 A1, WO 2015 / 067656 and DE 10 2008040094 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 loading of the catalyst feed will be < 600 Nl / l'h, frequently < 500 Nl / l-h, often < 400 Nl / l h or < 350 Nl / l-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 understood to mean 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-abs (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-abs (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. Of course, unsupported shaped catalyst bodies obtainable according to the invention (for example, ring-shaped) can be operated advantageously according to the invention as catalysts for the partial oxidation of propene to acrolein or of isobutene and / or tert-butanol (or its methyl ether) to methacrolein even at velocities of the catalyst charge with 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. As a rule, however, this velocities will be at values ​​> 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 (the fixed catalyst bed) of a reactor 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 (for example, > 150 Nl / l h), the use of diluent gases with higher molar heat capacities 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). In general, however, these gases and their mixtures can also be used at lower catalyst loadings with the organic compound to be partially oxidized. Recycle gas can also be used as a diluent gas. Recycle gas is 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 taken into account 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 0 990 636 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, unsupported 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-g, or preferably from 1.1 or 1.5 to 4 or up to 3 bar-g (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 / l-h, mostly to 1500 to 5000 Nl / l h and often to 2000 to 4000 Nl / l h. 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 tube bundle 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 tube bundle reactors are made of ferritic steel and typically have a wall thickness of 1 to 3 mm. Their inner 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 tube bundle 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. Tube bundle reactors with a number of contact tubes above 45,000 are rather the exception. The contact tubes are normally homogeneously distributed within the vessel. arranged, wherein the distribution is expediently selected such that the distance between the central inner axes of contact tubes closest to one another (the so-called contact tube pitch) is 35 to 45 mm (cf. EP 0 468 290 B1). However, the partial oxidation can also be carried out in a multi-zone (e.g. "two-zone") tube bundle reactor, as recommended in DE 199 10 506 A1, DE 103 13 213 A1, DE 103 13 208 A1 and EP 1 106 598 A2, particularly in the case of increased loading of the catalyst feed of the tube bundle reactor with the organic compound to be partially oxidized. A typical catalyst tube length in the case of a two-zone tube bundle reactor is 3.50 m, 4.00 m or 4.50 m. Everything else essentially applies as described for the single-zone tube bundle reactor. A heat exchange medium is passed around the contact tubes, within which the catalyst feed (the fixed catalyst bed) is located, in each tempering zone (the single-zone tube bundle reactor has only one tempering zone) of the single-zone or multi-zone tube bundle 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 temperature control 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 temperature control zone to the point of exit from the temperature control 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 199 48 523 A1, DE 199 48248 A1, DE 103 13 209 A1, EP 0 700 714 A1, DE 103 13 208 A1, DE 103 13 213 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 tube-bundle 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 conveniently selected so that the ratio of the reaction heat-generating volume to the 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 volume 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 The mixture can be mixed from the split catalyst to the unsupported catalyst bodies. This equalization is preferably carried out homogeneously over the entire length of the thermotube. Furthermore, the filling of the 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 homogeneously diluting a basic amount of unsupported catalyst bodies (e.g., annular) produced uniformly according to the invention with inert diluent bodies. The higher the proportion of diluent bodies selected, the lower the active mass or catalyst activity contained in a given volume of the feed. However, a reduction can also be achieved by changing the geometry of the unsupported catalyst bodies obtainable according to the invention such that the amount of active mass contained per unit internal volume of the reaction tube becomes smaller. For the heterogeneously catalyzed gas phase partial oxidations with shaped unsupported catalyst bodies (for example annular) obtainable as described, the catalyst feed is preferably either designed uniformly over the entire length with only one type of shaped unsupported catalyst bodies or structured as follows. At the reactor inlet, over a length of 10 to 60%, preferably 10 to 50%, particularly preferably 20 to 40% and very particularly preferably 25 to 35% (i.e., for example, over a length of 0.70 to 1.50 m, preferably 0.90 to 1.20 m), in each case the total length of the catalyst feed, 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, wherein the weight fraction of the diluent bodies (the mass densities of catalyst bodies and diluent bodies generally differ only slightly) is normally 5 to 40 wt.%, or 10 to 40 wt.%, or 20 to 40 wt.%, or 25 to 35 wt.%.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 that 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 > 0°C but < +9°C, better < +7°C, preferably < +5°C, particularly preferably < +3°C when the temperature of the heat exchange medium increases by 1°C at any point of the fixed catalyst bed (see also EP 1 106 598 A1). Furthermore, a heterogeneously catalyzed partial oxidation for the production of acrolein (from propene) or methacrolein (from the C4 precursor compounds mentioned in the present document) can be carried out with produced annular shaped unsupported catalyst bodies can advantageously be carried out 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 shaped unsupported catalyst bodies according to the invention 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 ones) obtainable according to the invention can be carried out, for example, as described in DE 10337 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 2008040093 A1 and DE 10 2008040094 A1 (particularly advantageously as in the exemplary embodiments of these documents). Examples Production of the solid catalyst bodies K1 to K13: Preparation of the full catalyst body K1, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe3C049Ni26Ko 12Ox. The stirred vessels used were each 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 atm-abs, 1.01 bar-abs). a) Preparation of an aqueous solution B 3.9 kg of demineralized water were placed in a temperature-controlled cylindrical stirred vessel (10 l internal volume) made of stainless steel (EN 1.4541) equipped with an anchor stirrer and heated to 60°C with stirring (150 rpm). Then, while stirring constantly and maintaining the temperature at 60°C, 23.5 g of a 47 wt. % aqueous potassium hydroxide solution (47 wt. % KOH), which had a temperature of 20°C, were added. While maintaining the temperature at 60°C, 1161 g of fine-grained ammonium heptamolybdate tetrahydrate (54.3 wt. % Mo, supplier: NIPPON INORGANIC COLOUR & CHEMICAL CO., LTD.) were then added., 3-14-1 Funado ltabashi-ku Tokyo 174-0041 (JP); it had a turbidity of 219 NTU (determined according to WO 2016 / 147324), which was at a temperature of 25°C, was stirred in portions, and the resulting aqueous solution (it had a slight turbidity due to minimal insoluble isopolymolybdate impurities) was stirred at 60°C for 20 min (150 rpm). b) Preparation of an aqueous solution A. 3765 g of an aqueous nitric acid cobalt(II) nitrate solution (12.6 wt% Co, 27 wt% nitrate (NO3), 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 temperature-controlled cylindrical stirred vessel (5 l internal volume) made of stainless steel (EN 1.4541) equipped with an anchor stirrer and heated to 60°C while stirring (150 rpm). With continued stirring (150 rpm) and continued tempering at 60°C, 1994 g 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 10 min at 60°C (150 rpm). To the resulting aqueous solution, 1856 g of a 60°C warm, aqueous, nitric acid bismuth nitrate solution (11.1 wt.% Bi, 13 wt.% nitrate (NO3), 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 and then stirred for a further 10 min at 60°C (150 rpm). To the resulting aqueous solution, 1817 g of a 60°C warm, aqueous, nitric acid nickel nitrate solution (13.8 wt.% Ni, 0.6 wt.% free nitric acid), prepared by dissolving nickel metal in aqueous nitric acid, were added and then stirred for a further 10 min at 60°C (150 rpm). c) Mixing of the aqueous solution A with the aqueous solution B to obtain an aqueous mixture M The 60°C warm aqueous solution A was metered into the aqueous solution B, which was now kept warm at 60°C, using a peristaltic pump (type: BVP, company: Ismatec SA, Labortechnik-Analytik, Feldeggstrasse 6, CH-8152 Glattbrugg, setting: 320 scale divisions) over a period of 15 minutes continuously using an Ultra-Turrax (company: Janke & Kunkel GmbH & Co. KG - 1 KA-Labortechnik, Janke & Kunkel-Str. 10, DE-79219 Staufen, shaft type: 550KR-G45 fine, shaft tube diameter: 25 mm, stator diameter: 45 mm, rotor diameter: 40 mm, setting: level 5).The aqueous solution A was added at the height of the Ultra-Turax stirrer rotor, offset by approximately 0.5 to 1 cm from the outer edge of the rotor. The resulting aqueous suspension was stirred for a further 15 minutes at 60 °C. d) 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 an anchor stirrer (150 rpm), was spray-dried in a Mobile Minor™ 2000 (MM-I) spray tower from Niro A / S, Gladsaxevej 305, 2860 Soborg, Denmark, using a type F01A centrifugal atomizer and a type SL24-50 atomizer wheel in a hot air cocurrent flow (gas inlet temperature: 350 ± 10 °C, gas outlet temperature: 140 ± 5 °C, throughput: 4.7 kg of aqueous mixture M / h and a hot air flow with a flow rate of 8.5 Nm3 / h). The portion of the aqueous mixture M that had not yet been spray-dried was continuously stirred at 60 °C. The speed of the atomizer wheel was set at 25,000 rpm.The resulting spray powder was stored in hermetically sealed containers (200 l internal volume, 25°C, atmospheric pressure) until further processing (10 calendar days; shorter or longer intermediate storage (up to 30 calendar days) had no influence on the resulting results). The loss on ignition of the resulting spray powder (annealed for 3 h at 600°C (powder temperature) in standing (excess) air) was 32 wt.% of its initial weight. e) Production of ring-like shaped unsupported catalyst precursor bodies. 3 kg of the spray powder were mixed with 3.5 wt.%, based on the weight of the spray powder, graphite (type 3160 from Asbury Graphite Mills Inc., New Jersey 08802) and with 5 wt.%, based on the weight of the spray powder, glass fibers (glass fiber E-Glas type F2F 160 from Profill GmbH Heidelberg, Kichheimerstr. 1 D-69214 Eppelheim, nominal fiber size: 10 pim diameter, 200 pim length, BET surface area 0.4 m 2 / g) in a mixer equipped with a chopper (type L5 / 10 from Gebrüder Lödige Maschinenbau GmbH, Elsener Straße 7-9 33102 Paderborn, Germany) for 10 min, with the chopper blade being used intermittently for a total of 1 min. The powder mixture produced as described was then compacted (tableted) using a Kilian E150+ rotary press (with 21 EURO D dies) under dry air to form ring-like precursor bodies with the dimensions A x H x I = 5 mm x 5 mm x 2 mm and a non-curved (i.e., planar) end face, a mass (MV) of 160 mg (body density 1.94 g / ml). The applied pressing force (P v ) was 1.6 kN. The rotor speed was 15 - 20 rpm. f) Thermal pretreatment and calcination of the ring-like unsupported catalyst precursor bodies produced in e) 1000 g of the prepared full catalyst precursor bodies were evenly distributed on four grids arranged side by side, each with a square 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 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 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, heating took place from 25 °C to 130 °C. This temperature was maintained for 72 minutes and then increased to 190 °C within 36 minutes. The 190 °C was maintained for 144 minutes before the temperature was increased to 220 °C within 36 minutes.The temperature was maintained at 220 °C for 72 minutes before being increased to 380 °C over a period of 93 minutes. The temperature was maintained at 380 °C for 187 minutes before being increased to 430 °C over a period of 93 minutes. The temperature was maintained at 430 °C for 187 minutes before being increased to the final calcination temperature of 500 °C over a period of 93 minutes. This temperature was maintained for 467 minutes. The temperature was then cooled to 25 °C over a period of 12 hours. For this purpose, both the heating of the forced-air shaft kiln and the airflow preheater were switched off (the airflow of 4500 Nl / h was maintained, however; the airflow inlet temperature was then 25 °C). The obtained ring-like unsupported catalyst bodies K1 were stored in an airtight container at a temperature of 25°C and at atmospheric pressure until their use for catalyzing a heterogeneously catalyzed partial oxidation (for example, from propene to acrolein). Preparation of the full catalyst body K2, wherein the active multimetal oxide had the stoichiometry M012BiO 6Fe3C049Ni26Ko 12Ox. K2 was produced analogously to K1. The amount of glass fiber was adjusted to 3 wt.%, based on the weight of the spray powder. Preparation of the full catalyst body K3, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe3C049Ni26Ko 12Ox. K3 was manufactured in the same way as K1. No fiberglass was used. Preparation of the full catalyst body K4, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe3C049Ni26Ko 12Ox. K4 was produced analogously to K1. No glass fiber was used. The powder mixture was compacted (tableted) into ring-like precursor bodies with a mass (MV) of 185 mg (body density 2.24 g / ml). Preparation of the full catalyst body K5, wherein the active multimetal oxide had the stoichiometry Mo12Bi06Fe24Co61Ni16K004Ox. K5 was prepared analogously to K2. The amounts of potassium hydroxide solution, cobalt(II) nitrate solution, iron(III) nitrate nonahydrate melt, bismuth nitrate solution, and nickel nitrate solution were adjusted accordingly to achieve the elemental composition. Preparation of the full catalyst body K6, wherein the active multimetal oxide had the stoichiometry Mo12Bi06Fe24Co61Ni16K004Ox. K6 was manufactured in the same way as K5. No fiberglass was used. Preparation of the full catalyst body K7, wherein the active multimetal oxide had the stoichiometry Mo12Bi06Fe24Co61Ni16K004Ox. K7 was produced analogously to K5. No glass fiber was used. The powder mixture was compacted (tableted) into ring-like precursor bodies with a mass (MV) of 190 mg (body density 2.30 g / ml). Preparation of the full catalyst body K8, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe24C077Ko08Ox. K8 was prepared analogously to K2. The amounts of potassium hydroxide solution, cobalt(II) nitrate solution, iron(III) nitrate nonahydrate melt, bismuth nitrate solution, and nickel nitrate solution were adjusted accordingly to achieve the elemental composition. The final calcination temperature was adjusted to 480 °C. Preparation of the full catalyst body K9, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe24C077Ko 08Ox. K9 was produced analogously to K8. The amount of glass fiber was adjusted to 4 wt.%, based on the weight of the spray powder. The powder mixture was compacted (tableted) into ring-like precursor bodies with a mass (MV) of 150 mg (body density 1.92 g / ml). Preparation of the full catalyst body K10, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe24C07 Ko 08Ox. K10 was manufactured in the same way as K8. No fiberglass was used. Preparation of the full catalyst body K11, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe3C075Ko 14Ox. The preparation of K11 was carried out analogously to K8. The amounts of potassium hydroxide solution, cobalt(II) nitrate solution, iron(II) nitrate nonahydrate melt, and bismuth nitrate solution were adjusted accordingly to achieve the elemental composition. Preparation of the full catalyst body K12, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe3C075Ko 14Ox. K12 was produced analogously to K11. The amount of glass fiber was adjusted to 4 wt.%, based on the weight of the spray powder. The powder mixture was compacted (tableted) into ring-like precursor bodies with a mass (MV) of 150 mg (body density 1.82 g / ml). Preparation of the full catalyst body K13, wherein the active multimetal oxide had the stoichiometry M012Bio6Fe3C075Ko 14Ox. K13 was manufactured in the same way as K11. No fiberglass was used. To determine mechanical stability, the lateral compressive strength (SDF) was measured using a Sotax ST-50 (SOTAX AG, Aesch, Switzerland) at a test speed of 0.1 mm / s. An average of 20 measurements is given. Various production parameters and properties of the full catalyst bodies K1 to K13 are summarized in Table 1. Figure 1: Production parameters and properties of the unsupported catalyst bodies K1-K13. Comparison example PV = total pore volume of pores with a diameter of >0.03 to <300 pm PV (0.01-0.1) = volumetric fraction of pores with a diameter of >0.01 to <0.1 pm in the total pore volume PV (0.1-1) = volumetric fraction of pores with a diameter of >0.1 to <1 pm in the total pore volume PV (1-10) = volumetric fraction of pores with a diameter of >1 to <10 pm in the total pore volume PV (10-300): = volumetric fraction of pores with a diameter of >10 to <300 pm in the total pore volume SDF = lateral compressive strength Catalysis experiments on the selective oxidation of propene to acrolein and acrylic acid Test method 1 : A reaction tube (V2A steel, 21 mm outer diameter, 3 mm wall thickness, 15 mm inner diameter, 120 cm length) was charged from top to bottom (in the later flow direction of the reaction gas mixture) as follows: Section 1 : 10 cm length Steatite spheres (Steatite 0220 from CeramTec) with a diameter of 1.5 to 2.0 mm as pre-fill; Section 2: 71 cm length Homogenized mixture of 10 g of ring-shaped solid catalyst bodies and 135 g of steatite rings with the geometry 5 mm x 5 mm x 2 mm (outer diameter x length x inner diameter); Section s: 10 cm length Steatite spheres (Steatite 0220 from CeramTec) with a diameter of 1.5 to 2.0 mm as a refill. The temperature of the reaction tube was controlled using a salt melt (53 wt.% potassium nitrate, 40 wt.% sodium nitrite, and 7 wt.% sodium nitrate) bubbled with molecular nitrogen. The salt bath (the salt melt) was located in a cylindrical casing with an inner diameter of 11 cm. The cylindrical casing had the same length as the reaction tube. The reaction tube was guided from top to bottom within the cylindrical casing so that the two axes of symmetry coincided. The nitrogen flow bubbled into the salt bath at a temperature of 25°C from below was 40 Nl / h (standard conditions = 1.01 bar, 0°C). The heat losses from the salt bath to the environment were greater than the reaction heat released by the tubular reactor to the salt bath during partial oxidation. The salt bath was therefore heated to its temperature T by means of electrical heating. SB(°C). This ensured that the outer wall of the reaction tube always maintained the corresponding temperature T SB (°C). T SB was set to a temperature of 380°C. The reaction tube was continuously fed with a reaction gas input mixture having the following composition: 5 vol.% propene (polymer grade), 9.5 vol% molecular oxygen, and 85.5 vol% molecular nitrogen. The flow rate of the reaction gas mixture fed into the reaction tube at a temperature of 150 °C was always 70 Nl / h. The pressure at the inlet to the reaction tube was 1.6 bar absolute in all cases (a control valve was located at the reaction tube outlet to adjust the inlet pressure). The composition of the reaction gas mixture was determined online by gas chromatography at both the inlet and outlet of the reaction tube. The propene conversion (U p (mol-%)) was calculated from the molar content C Pein of the reaction gas mixture of propene at the reaction tube inlet and the molar content C Paus of the reaction gas mixture of propene at the reaction tube outlet is determined as follows: U p (mol-%) = 100 x (C Pein - C Paus ) / C Pei ". From the molar content of the reaction gas mixture of acrolein (C Aaus ) at the reaction tube outlet, the molar content of the reaction gas mixture of acrylic acid (C Saus ) at the reaction tube outlet and from C Pein and C Paus The selectivity of acrolein formation (SA (mol-%)) and acrylic acid formation (S s (mol-%)) is determined as follows: S A (mol-%) = 100 x (C Aaus / (C Pei " - C Paus )) ; S s (mol-%) = 100 x (C Saus / (C Pei " - C Paus )) . The selectivity of the total value product formation S wp (mol-%) is calculated as the sum S A (mol%) + S s (mol%). The catalytic activity (propene conversion, selectivity, yield) measured during 7 consecutive days of testing are shown in Table 2. Test method 2: The reactor test facility used in Test Method 1 was used. Section 1 : 10 cm length Steatite spheres (Steatite C220 from CeramTec) with a diameter of 1.5 to 2.0 mm as pre-fill; Section 2: 40 - 47cm length 50 g of pure annular solid catalyst body; Section 3: 70 cm length Steatite rings with dimensions 5 mm x 5 mm x 2 mm (outer diameter x length x inner diameter). The flow rate of the reaction gas mixture was 100 Nl / h. The pressure at the inlet to the reaction tube was 1.2 bar absolute in all cases (a control valve was located at the reaction tube outlet to adjust the inlet pressure). The reaction tube was continuously fed with a reaction gas input mixture having the following composition: 5 vol.% propene (polymer grade), 9.5 vol% molecular oxygen, and 85.5 vol% molecular nitrogen. T SB was varied accordingly to achieve a propene conversion of 95%. In detail: T SBwas set to a temperature of 325°C at the beginning of each partial oxidation experiment with a fresh fixed bed feed. For the first time after an operation time of 2 h at T SB = 325°C and subsequently until a total operating time of 72 h was reached, the propene conversion U present in each case was determined every 2 h on the basis of gas chromatographic analysis of the composition of the resulting product gas mixture and the reaction gas input mixture fed into the reaction tube. p and the resulting selectivity of the value product formation S wp (both based on a single passage of the reaction gas mixture through the reaction tube) and then the value of T SB , based on its then-current amount, is increased or decreased so that the propene turnover U p , based on a single passage of the reaction gas mixture through the reaction tube, at the newly set value of TSB (Immediately after the new hiring of T SB ) was 95 mol% each. The newly set value for T SB was then kept unchanged for an operating time of 2 h. The arithmetic mean of the last 12 (i.e., in the interval of the total operating time from 48 h to 72 h) for a propene conversion U p (based on a single passage of the reaction gas mixture through the reaction tube) of 95 mol-% respectively required values ​​of T SB (°C) is the value T SBend (°C). This indicates the activity of the respective catalyst. The arithmetic mean of the last 12 (i.e., in the interval of the total operating time from 48 h to 72 h) for the desired product selectivity S wp certain values ​​(based on a single passage of the reaction gas mixture through the reaction tube) the value S WPendThis indicates the selectivity of the formation of the desired product on the respective catalyst. The catalytic activity (T SB , propene conversion, selectivity) are summarized in Table 3. Table 2: Catalytic activity according to test method 1. Cat amount of fiberglass SDF (N) (Wt.% in solid catalyst PV Propene conversion Selectivity Yield density (g / ml) (ml / g) (%) (mol%) (mol%) K1 7.1 1.35 0.42 12.7 86.7 96.3 83.5 K3*) 0 1.29 0.41 9.1 86.0 96.4 82.9 K4*) 0 1.49 0.36 9.2 88.1 93.6 82.5 K5 4.3 1.36 0.41 13.6 87.5 97.2 85.0 K6*) 0 1.36 0.42 9.3 88.1 96.6 85.2 K7*) 0 1.58 0.33 9.8 84.2 96.6 81.4 Comparative example PV total pore volume of pores with a diameter of >0.03 to <300 pm SDF lateral compressive strength Selectivity Value product selectivity (acrolein + acrylic acid) Yield Value product yield (acrolein + acrylic acid) The unsupported catalyst bodies according to the invention show a high yield with simultaneously high mechanical stability. Table 3: Catalytic activity according to test method 2. Cat Amount of SDF (N) Full catalytic Fiberglass pro- torformkör- PV selectivity (Wt% in pen) Bulk density (ml / g) (°C) (mol%) Full catalyst rate (%) (g / mi) molded body) 8 4.3 1.38 0.41 14.7 328 95 97.3 9 5.6 1.30 0.46 14.2 324 95 97.2 10*) 0 1.36 0.41 10.2 325 95 97.3 11 4.2 1.38 0.41 13.7 315 ​​95 95.7 12 5.6 1.30 0.45 14.3 315 95 96.0 13*) 0 1.36 0.41 10 314 95 95.8 2 4.4 1.35 0.42 12.5 319 95 96.8 5 4.3 1.36 0.41 13.6 314 95 97.0 *) Comparative example PV = total pore volume of pores with a diameter of >0.03 to <300 pm SDF = lateral compressive strength Selectivity Value product selectivity (acrolein + acrylic acid) The unsupported catalyst bodies according to the invention show a high yield with simultaneously high mechanical stability.

Claims

Patent claims 1. A shaped unsupported catalyst body for producing unsaturated aldehydes and unsaturated carboxylic acids, wherein the shaped unsupported catalyst body comprises at least the elements molybdenum, bismuth, iron and cobalt, characterized in that the shaped unsupported catalyst body contains inorganic fibers having an average fiber length of 10 pim to 1 mm and an average fiber diameter of 1 pim to 30 pim and the shaped unsupported catalyst body has a total pore volume of 0.37 to 0.65 ml / g, wherein the total pore volume is determined by mercury porosimetry.

2. Unsupported catalyst body according to claim 1, characterized in that the unsupported catalyst body has a total pore volume of 0.39 to 0.60 ml / g.

3. Unsupported catalyst molded body according to claim 1 or 2, characterized in that the inorganic fibers are glass fibers, aluminum oxide fibers, silica fibers or carbon fibers.

4. Unsupported catalyst shaped body according to one of claims 1 to 3, characterized in that the inorganic fibers have an average fiber length of 50 pim to 500 pim and an average fiber diameter of 5 pim to 15 pim.

5. Unsupported catalyst body according to one of claims 1 to 4, characterized in that the composition of the unsupported catalyst body corresponds to the general formula I Moi2Bi a FebCo c NidX e YfZgOn (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, where 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, and n = a number determined by the valence and frequency of the elements other than oxygen in the general formula I.

6. Unsupported catalyst shaped body according to claim 5, characterized in that in the general formula IX = K, a = 0.4 to 0.8, b = 2.2 to 3.2, c = 4.7 to 7.9, d = 0 to 2.8, c + d = 7.3 to 8.0, e = 0.02 to 0.16, f = 0, g = 0.

7. Unsupported catalyst shaped body according to one of claims 1 to 6, characterized in that the unsupported catalyst shaped body contains from 0.1 to 15 wt.% of inorganic fibers, based on the weight of the unsupported catalyst shaped body.

8. Unsupported catalyst shaped body according to one of claims 1 to 7, characterized in that a pore volume of the unsupported catalyst shaped body in the range from 0.1 to 1 pim is from 85 to 99% of the total pore volume, wherein the pore volume in the range from 0.1 to 1 pim is determined by mercury porosimetry.

9. Unsupported catalyst shaped body according to one of claims 1 to 8, characterized in that the unsupported catalyst shaped body is a tableted unsupported catalyst shaped body.

10. Unsupported catalyst shaped body according to claim 9, characterized in that the tableted unsupported catalyst shaped body has a density of 1.20 to 1.45 g / ml, wherein the density of the unsupported catalyst shaped body is the quotient of the mass and the geometric volume.

11. A process for producing a shaped unsupported catalyst body for the production of unsaturated aldehydes and unsaturated carboxylic acids, wherein the shaped unsupported catalyst body comprises 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 it, c) a powder mixture PM is produced by mixing the powder P obtained in b) with inorganic fibers, d) the powder mixture PM obtained in c), optionally with the addition of one or more auxiliaries and after uniform mixing and optional precompacting, is compacted to form precursor shaped bodies having a cylindrical structure, and e) the precursor shaped bodies obtained in d) are thermally treated to form the unsupported catalyst shaped bodies, characterized in that the pressure during the compaction in d) is selected such that the density of the precursor shaped bodies is from 1.65 to 2.20 g / ml, the density of the precursor shaped bodies being the quotient of the mass and the geometric volume, and the weight loss during the thermal treatment in e) is from 15 to 50 wt.%.

12. Process according to claim 11, characterized in that the pressure during compaction in d) is selected such that the density of the precursor shaped bodies is from 1.75 to 2.10 g / ml and the weight loss during the thermal treatment in e) is from 25 to 40 wt.%.

13. Process according to claim 11, characterized in that the mixing carried out in c) is a dry mix.

14. Process according to one of claims 11 to 13, characterized in that the compaction carried out in d) is tabletting.

15. A process for the preparation of unsaturated aldehydes and unsaturated carboxylic acids, wherein an alkene and / or an alcohol with molecular oxygen is passed over a fixed catalyst bed comprising a bed of unsupported catalyst bodies according to any one of claims 1 to 10.

16. Fixed-bed reactor containing a bed of unsupported catalyst bodies according to one of claims 1 to 10.

17. Use of unsupported catalyst bodies according to one of claims 1 to 10 in a gas phase oxidation of an alkyne and / or an alcohol.

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