JP2004231509A - Production method of multi-metal oxide composition, heterogeneous catalytic partial gas-phase oxidation and/or ammoxidation of saturated and/or unsaturated hydrocarbon and multi-metal oxide composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of a multi-metal oxide composition. <P>SOLUTION: The multi-metal oxide composition is composed of one kind of elements Mo and V, and at least one kind of elements Te and Sb. From a starting compound required for producing the multi-metal oxide composition of elements contained therein, partial solutions with a partial quantity of the starting compound dissolved respectively, are produced, flows of the partial solutions produced therefrom are combined and mixed, a flow of the obtained mixed solution is decomposed to fine liquid particles to be dried with a hot gas and a solid material obtained at this time is treated at a high temperature. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

The present invention provides a stoichiometric formula I:
^{_{Mo 1 V a M 1 b M}} 2 c M 3 d M 4 e O n (I)
(Where
M ¹ is at least one element from the group consisting of Te and Sb;
M ² is at least one element from the group consisting of Nb, Ti, W, Ta, Bi, Zr and Re;
M ³ represents Pb, Ni, Co, Fe, Pd, Ag, Pt, Cu, Au, Ga, Zn, Sn, In, Ce, Ir, Sm, Sc, Y, Pr, at least from the group consisting of Nd and Tb One element,
M ⁴ is at least one element from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, and Ba;
a is 0.01 to 1,
b is a number from 0 to 1;
c is a number greater than 0 and up to 1;
d is a number not less than 0 and not more than 0.5,
e is a number from 0 to 1;
n is a number determined by the valence and frequency of elements other than oxygen in (I))
A method for producing a multimetal oxide composition M represented by the formula: wherein, in a solvent, starting materials necessary for producing the multimetal oxide composition M of the element components contained in the multimetal oxide composition M are mixed in a solvent. The solution is continuously produced, and the mixed solution is continuously supplied to the drying device to remove the solvent, and the obtained solid is heat-treated at a high temperature, and the heat treatment comprises calcination at 200 to 1200 ° C. .

  The multimetal oxide composition of the stoichiometric formula (I) and a method for producing the same are known (for example, Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, Patent Document 6, Patent Document 7, Patent Document 8, Patent Document 9, and Patent Document 10). Said compositions are suitable as catalytically active compositions for heterogeneous catalytic gas-phase partial oxidation and / or ammoxidation of saturated and unsaturated hydrocarbons and lower aldehydes, for example as described in the literature.

  When using propane and / or propene as a hydrocarbon, it is possible to produce, for example, acrolein, acrylic acid and / or acrylonitrile as the target compound. Acrolein can itself be used as a starting compound for preparing the last two compounds. These target compounds are important intermediates used, for example, for producing polymers used as adhesives. Correspondingly, methacrolein and methacrylic acid are obtained from isobutane and isobutene. Methacrolein is a starting compound for producing methacrylic acid. The preparation of the multimetal oxide compositions of the stoichiometric formula I is generally carried out by preparing an intimate dry mixture from the starting compounds containing the elemental components and subjecting it to a heat treatment at an elevated temperature. Sources of possible starting compounds or elemental components are virtually all compounds or sources that can be heated (optionally in air) to form oxides and / or hydroxides. Of course, the oxides and / or hydroxides of the elemental components can be used partially or exclusively as starting compounds.

  First, a partial solution containing at least two spatially separated starting compounds dissolved and prepared from the starting compounds necessary for producing the multimetal oxide composition of the elemental components contained in the multimetal oxide composition is prepared. Describes that the partial solutions are combined with one another, the resulting mixture is dried, the solid obtained by drying is heat-treated, and the method used for the drying can be freely selected ( Patent Documents 5 and 6). Although a rather intimate dry mixture of the source can be produced by means of the partial solution, the disadvantage of the methods described in US Pat. Instead of producing a suspension having a partial amount of the composition as a solid.

  This is disadvantageous because the solids present in the suspension generally have a composition different from that of the material dissolved in the dispersion medium. For this reason, drying of this suspension does not generally result in a chemically uniform solid, but rather a solid whose chemical composition deforms in physical space, which solid is generally no longer complete during subsequent heat treatment. And the catalytic activity of the resulting active composition is reduced.

  An improvement is achieved by using a spray-drying method to dry the suspension (see US Pat. No. 6,037,045), since drying by evaporation results in a material dissolved in the dispersion medium, which material is This is because the solubility additionally precipitates in the form of fragments, which additionally accentuates the aforementioned heterogeneity.

  According to US Pat. No. 6,037,028 and the applicant's own observations, a precipitate forming a suspension occurs during the preparation of the multimetal oxide composition of stoichiometric formula I, with a short delay after combining the partial solutions. This time delay can be increased by the partial solution diluted with solvent and / or cooled. Thus, a sufficiently stable mixed solution can be produced at first according to Patent Document 7, and this mixed solution can be dried by a known method. However, this method has the disadvantage that the use of increasing amounts of solvent increases the energy consumption during drying. Furthermore, the drying time is increased and the danger of fractional sedimentation during drying is increased. Cooling of the partial solution also increases the energy consumption required for drying and, even though this measure slows down the kinetics of the precipitation step, at the same time reduces the solubility in most cases, which is undesirable. It has only limited advantages as it promotes precipitation.

  Similarly, it is recommended to prepare the mixed solution in advance so that the mixed solution can be dried so quickly that the solvent is removed before fractional precipitation occurs (see Patent Document 12).

  However, in the case of pre-made solutions, precipitation generally starts before the entire amount of solution has dried, which results in losses. This is especially the case when industrial-scale batches are required.

  Accordingly, there is a need for a method of continuously producing a mixed solution, feeding the produced mixed solution directly to solvent removal using a pump, and drying the mixture before partial precipitation occurs (Patent Document 12).

  However, a drawback of US Pat. No. 6,077,098 is that this required method cannot be used.

In view of the fact that the method is more or less impossible, the formation of a suspension is unavoidable, so that it is necessary to form the suspension at least continuously and as uniformly as possible (see patent document 13). ).
European Patent (EP-A) 318295 European Patent (EP-A) No. 512846 European Patent (EP-A) 767164 European Patent (EP-A) 895809 European Patent (EP-A) No. 529853 European Patent (EP-A) 608838 German Patent (EP-A) 962253 German Patent (DE-A) 10248584 German Patent (DE-A) 10119933 German Patent (DE-A) 10118814 European Patent (EP-A) No. 603836 JP-A-7-315842 JP-A-11-306228

  It is an object of the present invention to provide a method which meets the requirements set forth in JP-A-7-315842.

The problem is based on the stoichiometric formula I:
^{_{Mo 1 V a M 1 b M}} 2 c M 3 d M 4 e O n (I)
(Where
M ¹ is at least one element from the group consisting of Te and Sb;
M ² is at least one element from the group consisting of Nb, Ti, W, Ta, Bi, Zr, and Re;
M ³ represents at least one consisting of the group of Pb, Ni, Co, Fe, Pd, Ag, Pt, Cu, Au, Ga, Zn, Sn, In, Ce, Ir, Sm, Sc, Y, Pr, Nd and Tb Species element,
M ⁴ is at least one element from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, and Ba;
a is 0.01 to 1,
b is a number from 0 to 1;
c is a number greater than 0 and up to 1;
d is a number not less than 0 and not more than 0.5,
e is a number from 0 to 1 (or from 0 to 0.5);
n is a number determined by the valence and frequency of elements other than oxygen in the formula I), wherein the multimetal oxide composition M A mixed solution is continuously produced in a solvent from a starting compound necessary for producing the multimetal oxide composition M of the elemental component contained in the solvent, and the mixed solution is continuously supplied to a drying device to remove the solvent. This is solved by a method of producing a multi-metal oxide composition M, wherein the obtained solid is heat-treated at a high temperature, and the heat treatment is performed at a temperature of 200 to 1200 ° C. From the starting compounds necessary for the production of the multimetal oxide composition M of the elemental component contained in M, a partial solution containing at least two partial amounts of the necessary starting compounds which are spatially separated, respectively, is first dissolved. Manufactured and two or more partial solutions At least two partial solution streams are produced, and two or more partial solution streams are combined to form a total solution stream, wherein the total solution stream passes through the mixing zone and contains all of the required starting compounds in the mixing zone. A mixed solution stream is formed containing dissolved volume and the mixed solution stream breaks down into fine liquid particles in the mixing zone or discharges the mixed solution stream from the mixing zone and subsequently breaks down into fine liquid particles, The method is characterized in that the fine liquid particles of the mixed solution are dried by contact with a hot gas, and the obtained solid is heat-treated at a high temperature, and the heat treatment comprises firing at 200 to 1200 ° C.

  Unlike the total solution stream, the mixed solution stream has a substantially uniform composition.

  An important difference between the method of the present invention and the method preferred in US Pat. No. 6,026,045 is not a mixed solution stream according to US Pat. To convert to a mixed solution stream and transfer to drying.

  However, it is advantageous according to the invention to convert a partial amount of the partial solution which is present in dissolved form of the required starting compound into a partial solution stream, which is converted according to the invention into a mixed solution stream. The background of this advantageous property is that it is almost always possible to produce stable partial solutions, in particular from the partial amounts of the starting compounds required for producing the multimetal oxide compositions M, whereas A mixed solution having the total amount of starting compounds required to produce the metal oxide composition M is generally thermodynamically unstable, even in a highly diluted state, and a mixed compound which dissolves quickly or slightly later , Which precipitate as a solid until its solubility limit is reached. Thus, the partial solutions can be prepared batchwise discontinuously beforehand in the process of the invention and subsequently converted into suitable partial solution streams or mixed solution streams. Of course, partial solutions can be produced continuously by the method of the present invention.

  In principle, all sources which can be heated (optionally in air) to form oxides and / or hydroxides as sources of the elemental components of the multimetal oxide composition M of the process according to the invention It is possible to use Of course, oxides and / or hydroxides of the elemental components can be used as part or all of this starting compound. In addition to oxides and / or hydroxides, possible sources of the elemental components of the process according to the invention are in particular salts of organic and / or inorganic acids. Examples which may be mentioned are halides such as chlorides, formates, acetates, oxalates, carbonates, nitrates, sulphates and sulphite.

Suitable sources of the element Mo for the purposes of the present invention are, for example, molybdenum oxides such as molybdenum trioxide, molybdates such as ammonium heptamolybdate tetrahydrate and molybdenum halides such as molybdenum chloride. . Suitable starting compounds of the element V which can be used according to the invention are, for example, vanadates such as vanadium oxysulphate hydrate, vanadyl acetylacetonate, ammonium metavanadate, vanadyl oxalate, vanadyl sulphate, pentoxide vanadium oxides such as vanadium _(V 2 _{O 5),} vanadium oxy halides such as vanadium halides and VOCl ₃ as vanadium tetrachloride (VCl _4). It is also possible to use vanadium starting compounds in which vanadium is present in the oxidation stage +4.

Tellurium oxides such as tellurium dioxide by the present invention to a suitable source of elemental tellurium include metal tellurium, tellurium acids such as Teruruharogenido and Orutoteruru acid H ₆ TeO ₆ as TeCl _2.

Sources of niobium suitable for the purposes of the present invention include, for example, niobium oxides such as ob (Nb ₂ O ₅ ), niobium oxyhalogenides such as NbOCl ₃ , niobium halogenides such as NbCl ₅ and organic carboxylic acids. Complexes of niobium with acids and / or dicarboxylic acids, such as oxalates, citrates, tartrates, and alkoxides of these ammonium salts, such as ammonium niobate citrate, ammonium niobate oxalate, ammonium niobate tartrate, and the like. Of course, the Nb-containing solution used in EP-A-895809 is also suitable as a niobium source.

  Suitable starting compounds for all other possible elements (especially Pb, Ni, Cu, Co, Fe, Bi, and Pd and alkali and alkaline earth metals) include, in particular, their halides, nitrates, formates, Oxalates, acetates, carbonates and / or hydroxides are included. Other suitable starting compounds often include the oxo compound such as tungstic acid or an acid derived therefrom. Here, ammonium salts are frequently used as starting compounds.

  Other possible starting compounds are Anderson type polyanions, as described, for example, in Polyhedron Vol 6. No. 2213-218, 1987. Another suitable literature source for Anderson-type polyanions is Kinetics and Catalysis, Vol. 40, No. 3, 1999, 401-404.

  Other polyanions suitable as starting compounds are, for example, Dawson-type or Keggin-type polyanions.

  The partial solutions required according to the invention can of course be prepared using complexing agents which evaporate and / or decompose during the heat treatment of the dried solids (for example oxalate, citrate and / or acetyl). Complex formation as acetonate).

  In addition, the acid or base properties of the partial solution can be intentionally altered by the addition of organic and / or inorganic acids or bases in order to adjust the solubility properties intentionally. As another parameter, the temperature during the preparation of the partial solution can be increased or decreased depending on what has a favorable effect on the solubility (which can be determined with some preliminary tests).

  According to the invention, the solvent used is preferably an aqueous solvent or only water. However, it is in principle also possible to use alcohols such as methanol and ethanol and organic and / or inorganic acids, for example acetic acid. Mixtures of the abovementioned solvents, in particular aqueous mixtures, can of course also be used.

  The solids content of the mixed solution produced according to the invention can vary. Expressed as the total content of metals present in the respective mixed solution, the process according to the invention generally comprises at least 0.01% by weight, often at least 0.1% by weight, preferably at least 1% by weight, often at least 5% by weight, Optionally at least 10% by weight. This solids content generally does not exceed 30% by weight. Often not more than 25% by weight or not more than 22% by weight. % By weight relates in each case to the weight of the respective mixed solution or of the respective mixed solution stream. Correspondingly, as well as the solids content of the mixed solution, the corresponding solids content of the partial solution can also be varied, ie the above values apply to the partial solution. In particular, the solids content corresponds to an aqueous partial solution or a mixed solution. The solids content of the mixed solution generally does not exceed the limit of 30% by weight, but solids contents of partial solutions (aqueous and non-aqueous) up to 50% by weight and more are possible. Such a high partial solution solids content is offset by the mixed solution using at least one partial solution having a low solids content that is generally used to form the mixed solution. Of course, various solvents can be used for the partial solutions to be combined according to the invention (for example water for one partial solution and methanol or ethanol or an aqueous alcohol mixture for the other partial solution).

  The temperatures of the partial solution streams combined to form the total solution stream can correspondingly be the same or different in the process of the invention. The temperature of the partial solution stream (especially the water stream) of the process according to the invention is generally between 0 ° C. and 100 ° C., preferably between 5 ° C. and 80 ° C., in particular between 10 ° C. and 60 ° C., particularly preferably above 15 ° C. It is 40 ° C. or lower, and a use range of 20 to 30 ° C. is advantageous.

  In the process according to the invention, the partial solution stream can be conveyed using atmospheric, overpressure or reduced pressure.

  Very generally, for the purposes of the present invention, the term solution means liquid, optically clear (except for the added solid diluent) solids and precipitate-free systems.

  The number of partial solution streams must be at least two in the process according to the invention. However, 3, 4, 5, 6, 7, 8, 9, or 10 may be used. The number of partial solution streams is advantageously less than 5 in the process according to the invention.

  The source of the elemental components of the multimetal oxide composition M, which forms a suitable partial amount of all the starting compounds required for the preparation of the multimetal oxide composition M dissolved in the partial solution, depends on the individual circumstances. It needs to be determined and can be determined by one skilled in the art using some preliminary testing.

  If the multimetal oxide composition M contains the element Nb, it is often advantageous in the process according to the invention to dissolve this element in a separate partial solution. On the other hand, it is generally not difficult to dissolve the elements Mo, V and Te together in one partial solution.

  As required for the purposes of the present invention, for example, the partial solution from at least two containers containing two or more partial solutions is first separated by a suitable number of pumps into a separate line (in the simplest case, a hose or Two or more partial solution streams can be combined by converting them into a spatially separated, continuously flowing partial solution stream carried by a tube.

  In the simplest case, two or more partial solution streams are subsequently conveyed to the two inlets of the Tee (the feed line is preferably narrowed at the inlet of the Tee). Inside the T-tube, the two partial solution streams combine and flow together as a total solution stream to the outlet of the T-tube, through which all the solution flow exits the T-tube.

  After the two partial solution streams have been combined, they mix substantially uniformly while being transported forward as a total solution stream. This mixing is mainly due to the turbulence that occurs, for example, when the partial flows are combined.

  Static mixers (eg one of SMXS from Sulzer Chemtech, D-61239 Ober-Moerlen Ziegenberg) and / or dynamic mixers can be incorporated, for example, in the outlet section, so that the entire solution stream passes through the outlet section. Are discharged as a substantially uniform mixed solution stream. Static and dynamic mixers exist in principle in spaces with static or moving obstacles, which regulate the flow of the mixed solution flow so that turbulence occurs, and To produce a mixed solution stream (the term static mixer is a fixed mixing device, for example a mixer having a flow pin, after which the material to be mixed flows, vortex and other The term dynamic mixer refers to a mixer having an active mixing device, for example in the form of a rotary mixing blade, in which the materials to be mixed mix with each other by an active transport. ).

  It has been found that it is practically effective to assist the mixing in the mixing zone or to perform the mixing exclusively by the action of ultrasound. For example, a rod-shaped ultrasonic probe can be inserted into the mixing zone for this purpose.

  The number of inlets of the T-tube in the illustrated embodiment of the method of the invention described above may be more than two without changing the basic principle of the method.

  The mixed solution stream produced as described above can be subsequently conveyed directly to the atomizer head of the spray dryer (e.g. Niro Atomizer model Minor Hi-Tec Niro Copenhagen, Denmark) by the shortest route and broken down into fine liquid particles, The liquid particles are dried by contact with a hot gas (eg, air or nitrogen or a mixture of air and nitrogen or a noble gas or carbon oxide). In the method of the present invention, the hot gas inlet temperature in the case of the spray dryer may be, for example, 200 to 400C, preferably 310 to 330C. The outlet temperature of the drying gas should be between 100 and 200C, preferably between 105 and 115C according to the invention. The sprayed mixed solution and hot drying gas can be conveyed to the spray dryer in a countercurrent or countercurrent. The size of the liquid particles obtained from the spraying is generally between 5 and 1000 μm, preferably between 10 and 100 μm. The drying time of the liquid particles is less than 1 second with a conventional spray dryer. The spray drying of the process according to the invention can in principle be carried out as described in EP-A-603936.

  Spraying of the whole solution in the process of the invention can be carried out using a nozzle (eg a centrifugal nozzle), using a gas pressure atomizer or using a spray disk or spray basket (often called a rotating nozzle). Spray disks and baskets are advantageous according to the invention. These are more complex in the technical sense and have a higher energy consumption compared to other nozzles, but are less responsive to the solid particles formed. In this sprayer the entire solution generally flows without pressure into the center of the disc or basket, breaks down and is sprayed as a hollow cone from the smooth edge of the disc or the perforated rim of the basket.

  In the process according to the invention, the partial solution stream is fed to a dynamic mixer as described in DE-A 100 43 489, a fine mixer as described in DE-A 100 41 823, or as a German mixer ( It can be fed directly to the mixing nozzles described in DE-A) 199 58 355 and mixed therein according to the invention. Such a mixing nozzle used in the method of the invention may be a smooth flow nozzle, a revo nozzle, a Bosch nozzle or a jet dispenser. It is advantageous to use a mixing nozzle which combines and mixes the partial solution streams according to the invention and sprays the resulting mixed stream. The whole sprayed solution can then be dried in a spray dryer with hot gas in a countercurrent or countercurrent. The advantage of the process according to the invention is that it is based on the production of a stable partial solution which only binds and mixes when flowing continuously, and consequently has a narrow residence time distribution and can be spray-dried without delay. The stream is produced directly and in a minimum amount of time.

  In general, the process according to the invention generally takes less than 2 minutes, preferably 1 minute, from the time when the joining of the two or more partial solution streams to form the total solution stream to the time when the dispersing (spraying) of the mixed solution stream ends. It takes less than 30 seconds, in particular less than 30 seconds, and is advantageously less than 20 seconds or less than 10 seconds in the range of use. When using a fine mixer described in DE-A 100 41 823, this time may be less than 5 seconds, advantageously less than 2 seconds or less than 1 second. Good.

  These times are generally sufficient to ensure that no solids form inside the mixed solution before the mixed solution is completely sprayed.

  Before heat-treating the solid obtained by drying the mixed (dispersed) solution stream sprayed according to the process of the invention, it is necessary to first form tablets (optionally 0.05 to 3% by weight of finely divided graphite). ), Followed by a heat treatment. After heat treatment, tableting can be reversed with grinding or crushing.

  The heat treatment is carried out in German Patent (DE-A) 198 35 247, European Patent (EP-A) 529853, European Patent (EP-A) 603836, European Patent (EP-A) 608838, European Patent (EP) -A) 895809, European Patent (EP-A) 962253, European Patent (EP-A) 10808084, European Patent (EP-A) 1090684, European Patent (EP-A) 1123938 , European Patent (EP-A) No. 1192987, European Patent (EP-A) No. 1192,986, European Patent (EP-A) No. 1192922, European Patent (EP-A) No. 119,983, and European Patent (EP-). A) It is described in No. 1192988.

  The heat treatment (baking) at 200 to 1200 ° C., 300 to 650 ° C., or 400 to 600 ° C. can be performed in principle in an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere. Possible oxidizing atmospheres are, for example, air, air with accumulated molecular oxygen, or air deficient in molecular oxygen. However, according to the invention, the heat treatment is preferably carried out under an inert atmosphere, for example under molecular nitrogen and / or a noble gas. The heat treatment is generally performed at atmospheric pressure (1 atm). Of course, the heat treatment can be performed under reduced pressure or overpressure. The temperature of the heat treatment generally does not exceed 650 ° C. However, high temperatures are advantageous, in particular if the multimetal oxide composition M contains the element Cs and / or other alkali metals or alkaline earth metals.

  If the heat treatment is performed in a gaseous atmosphere, it may be static or may flow. The heat treatment may take up to 24 hours or even more. High temperatures correlate with short processing times, and short processing times correlate with high temperatures.

  The heat treatment is preferably first carried out in an oxidizing (oxygen-containing) atmosphere (for example under air) at 100 to 400 ° C. or 200 to 300 ° C. (preliminary decomposition step). Subsequently, the heat treatment is preferably continued at 300 to 650 ° C. or 400 to 600 ° C. or 450 to 600 ° C. under an inert gas.

  The multimetal oxide composition M obtained as described above can be used as such (ie as a powder or granules) or after shaping to form a shaped body as a catalytically active composition, after which the saturated hydrocarbons and unsaturated It can be used for partial gas phase oxidation and / or ammoxidation of hydrocarbons or lower aldehydes. In this case, the catalyst bed may be a fixed bed, a moving bed or a fluidized bed. The molding can be carried out, for example, by extrusion or tableting in the case of solid catalysts or by coating on substrates, as described in DE 101 18 814, PCT / EP / 02/04073 or DE 100 51 419. (Production of a catalyst).

  The support used for the multimetal oxide composition M according to the invention in the case of a coated catalyst is advantageously chemically inert, ie it is catalytically activated by the multimetal oxide composition M according to the invention. Does not significantly participate in the partial catalytic gas phase oxidation or ammoxidation of hydrocarbons or aldehydes (eg, producing acrylic acid from propane and / or propene).

  According to the invention, suitable materials for the support are, in particular, aluminum oxide, silicon dioxide, clay, kaolin, steatite (preferably C-220, steatite of the type Ceram Tec (Germany), or preferably low water-soluble alkalis. Silicates such as pumice, aluminum silicate, magnesium silicate, silicon carbide, zirconium dioxide, and thorium dioxide.

  The surface of the support may be smooth or rough. The surface of the support is advantageously rough, since the increased surface roughness generally leads to a firm adhesion of the shell of the coated active composition.

  The surface roughness Rz of the support is in the range from 5 to 200 [mu] m, preferably from 20 to 100 [mu] m (determined according to DIN 4768, part 1 using a Homel Tester for DIN-ISO surface parameters Homelwerke, Germany).

  The support material may be porous or non-porous. The support material is advantageously non-porous (the total volume of the pores with respect to the volume of the support is not more than 1% by volume).

  The thickness of the active oxide composition layer present in the coated catalyst according to the invention is generally between 10 and 1000 μm. However, it may be 50-700 μm, 100-600 μm or 150-400 μm. The thickness of the coating may range from 10 to 500 μm, 100 to 500 μm or 150 to 300 μm.

  In principle, all shapes of the support are possible with the method according to the invention. Its maximum dimension is generally between 1 and 10 mm. However, it is advantageous to use spheres or cylinders, in particular hollow cylinders, as supports. The preferred diameter of the support sphere is 1.5 to 4 mm. If a cylinder is used as support, its length is preferably 2 to 10 mm and its outer diameter is preferably 4 to 10 mm. In the case of rings, the wall thickness is generally between 1 and 4 mm. Ring supports suitable for the purposes of the present invention have a length of 3 to 6 mm, an outer diameter of 4 to 8 mm and a wall thickness of 1 to 2 mm. However, support ring shapes of 7 mm × 3 mm × 4 mm or 5 mm × 3 mm × 2 mm (outer diameter × length × inner diameter) are also possible.

  The preparation of the coated catalyst is most easily carried out by pre-forming the multimetal oxide composition M according to the invention, converting it to the form of fine particles and subsequently coating the surface of the support with a liquid binder. Can be. For this purpose, the surface of the support is most easily wetted with a liquid binder and the layer of active composition is applied to the wet surface by contacting the wet surface with the finely divided active multimetal oxide composition M. Cover. The coated support is finally dried. Of course, the method can be repeated periodically to achieve an increased coating thickness. In this case, the coated support becomes a new support or the like.

  Naturally, the fineness of the catalytically active multimetal oxide composition M of the general formula I coated on the surface of the support is compatible with the desired coating thickness. For a coating thickness in the range of 100 to 500 μm, at least 50% of the total number of powder particles pass through a sieve with mesh openings of 1 to 20 μm and the proportion by the number of particles having the largest dimension larger than 50 μm is Active composition powders that are less than 10% are, for example, suitable. In general, the distribution of the largest dimensions of the powder particles corresponds to a Gaussian distribution as a result of the production. The particle size distribution is often as follows:

In this table,
D is the particle diameter,
x is the percentage of particles having a diameter equal to or greater than D;
y is the percentage of particles having a diameter smaller than D.

  To carry out the coating process on an industrial scale, it is preferable to use the method principles described, for example, in DE-A 29 09 671 or DE-A 100 51 419, ie coating. The support to be provided is preferably inclined (the inclination angle is generally 0 ° or more and 90 ° or less, preferably 30 ° or more and 90 ° or less, and the angle of inclination is the angle of the central axis of the rotating container with respect to the horizontal. ) In a rotating container (eg a rotating pan or a coating drum). The rotating container conveys the support, for example in the form of a sphere or a cylinder, at a certain distance from one another under two successive metering devices. The first of the two dosing devices is preferably a nozzle (eg a spray nozzle operated by compressed air) which sprays a liquid binder onto a rotating support in a rotating vessel and wets it in a controlled manner. Equivalent to. A second dosing device is located outside the spray cone of the liquid binder to be sprayed and is used to introduce the particulate oxide active composition (for example by vibrating tube or powder screw). The support spheres, which are moistened in a controlled manner, take up the active composition which is introduced and which, by means of a rotational movement, consolidate into a shell which is in intimate contact with the outer surface of the support, for example in the form of a cylinder or a sphere. .

  If the support receiving the base coating passes through the spray nozzle again during the subsequent rotation, if necessary in this way, it is moistened in a controlled manner and, during the further movement, the finely divided oxide active composition Other layers can be incorporated, etc. (intervening drying is generally not necessary). The particulate oxide active composition and the liquid binder are generally supplied continuously and simultaneously.

After coating is complete, the liquid binder may be removed by the action of such hot gas, e.g. N ₂ or air. It is important that the coating process result in a sufficiently satisfactory adhesion of the base layers to one another and to the surface of the substrate.

  In said coating method, it is important that the wetting of the surface of the substrate to be coated is performed in a controlled manner. Briefly, this means that the support surface adsorbs the liquid binder, but the support surface is advantageously wetted such that no liquid phase is seen on the support surface. If the support surface is too wet, the particulate catalytically active oxide composition will condense to form another condensate instead of adhering to the surface. Further information on this is given in DE-A 29 06 71 and DE 100 51 419.

  The subsequent removal of the used liquid binder can be effected in a controlled manner, for example by evaporation and / or sublimation. In the simplest case, this can be done by the action of a hot gas having a suitable temperature (preferably 50-300 ° C, especially 150 ° C). However, it is also possible to perform only preliminary drying by the action of hot gas. Subsequent final drying can take place, for example, in any type of drying oven (eg, belt dryer) or reactor. The temperature used is not higher than the firing temperature used to produce the oxide active composition. Of course, drying can be performed exclusively in a drying oven.

  Regardless of the type and shape of the support, the following can be used as the binder for the coating method. Water, monohydric alcohols such as ethanol, methanol, propanol, and butanol, polyhydric alcohols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or glycerin, monobasic or polybasic organic carboxylic acids Acids such as propionic acid, oxalic acid, malonic acid, glutaric acid or maleic acid, amino alcohols such as ethanolamine or diethanolamine, and mono- or polyfunctional organic amides such as formamide. Suitable binders comprise from 20 to 90% by weight of water and from 10 to 80% by weight of organic compounds dissolved in water having a boiling point and a sublimation temperature above 100 ° C., preferably above 150 ° C., at atmospheric pressure (1 atm). Solutions are also included. The organic compound is advantageously selected from the above list of possible organic binders. The proportion of organic components in the aqueous binder solution is preferably from 10 to 50% by weight, in particular from 20 to 30% by weight. Possible organic components also include monosaccharides and oligosaccharides such as glucose, fructose, saccharose, or lactose, and also polyethylene oxides and polyacrylates.

  Possible shapes (for both solid and coated catalysts) are spheres, solid cylinders and hollow cylinders (rings). The maximum dimension of the shape is generally between 1 and 10 mm. In the case of a cylinder, its length is preferably 2 to 10 mm and its outer diameter is preferably 4 to 10 mm. In the case of a ring, the wall thickness is generally between 1 and 4 mm. Suitable ring-shaped solid catalysts can have a length of 3-6 mm, an outer diameter of 4-8 mm and a wall thickness of 1-2 mm. However, solid catalyst ring shapes of 7 mm × 3 mm × 4 mm or 5 mm × 3 mm × 2 mm (outer diameter × length × inner diameter) are also possible. Of course, all the configurations described in DE-A-101 1695 are also possible for the active multimetal oxide composition M.

The specific surface area of the multimetal oxide composition M according to the invention (and the multimetal oxide compositions M ′, M ″ described hereinafter) is often from 1 to 40 m ² / g, preferably from 11 or 12 to 40 m ² / g and in particular 15 or 20 to 40 or ^{30 m} 2 / g is a (BET method, was determined by nitrogen).

  According to the invention, the stoichiometric coefficient of the multimetal oxide composition M obtained according to the invention is 0.05, irrespective of the advantageous range of the other stoichiometric coefficients of the multimetal oxide composition M. -0.6, especially 0.1-0.6 or 0.5.

  Regardless of the advantageous range of the other stoichiometric coefficients of the multimetal oxide composition M, the stoichiometric coefficient b is preferably greater than 0 or 0.01 to 1, in particular 0.01 or 0.01. 1 to 0.5 or 0.4.

  The stoichiometric coefficient c of the multimetal oxide composition M obtained according to the invention is advantageously between 0.01 and 1 irrespective of the advantageous range of the other stoichiometric coefficients of the multimetal oxide composition M. And especially 0.01 or 0.1 to 0.5 or 0.4. Regardless of the advantageous range of the other stoichiometric coefficients of the multimetal oxide composition M obtained according to the invention, in particular of the stoichiometric coefficient c combined with all other advantageous ranges of this specification An advantageous range is between 0.05 and 0.2.

  The stoichiometric coefficient d of the multimetal oxide composition M obtained according to the invention is preferably 0.0005 or irrespective of the advantageous range of the other stoichiometric coefficients of the multimetal oxide composition M. 0.0005 to 0.5, especially 0.001 to 0.5, particularly preferably 0.002 to 0.3, especially 0.005 or 0.01 to 0.1.

  Regardless of the advantageous range of other stoichiometric coefficients of the multimetal oxide composition M, the coefficient e may be greater than or equal to 0 and up to 0.5.

Particularly advantageous multimetal oxide compositions M obtained according to the invention are those in which the stoichiometric coefficients a, b, c and d are simultaneously in the following ranges:
a is 0.05 to 0.6,
b is 0.01 to 1 (or 0.01 to 0.5);
c is 0.01 to 1 (or 0.01 to 0.5);
d is 0.0005 to 0.5 (or 0.001 to 0.3) and e is a number from 0 to 0.5.

Particularly advantageous multimetal oxide compositions M obtained according to the invention are those in which the stoichiometric coefficients a, b, c and d are simultaneously in the following ranges:
a is 0.1 to 0.6,
b is 0.1 to 0.5,
c is 0.1 to 0.5,
d is 0.001 to 0.5 or 0.002 to 0.3 or 0.005 to 0.1, and e is a number from 0 to 0.2.

  M1 is advantageously Te.

All that is previously described, in particular at least 50 mol% of Nb and / or Ta in the total amount of ^{M 2,} particularly preferably 100 mol% of 75 mole percent or ^{M 2} the total amount of the total amount of ^{M 2} has Nb Applies if

Meaning regardless of M ^2, particularly ^{M 3} is Fe, Ni, Co, Pd, Ag, Au, at least one element or Ni from the group consisting of Pb and Ga, Co, from the group consisting of Fe and Pd It is also applied when it is at least one element.

All that is previously described, in particular at least 50 mol% of the total amount of ^{M 2,} or at least 75 mole%, or 100 mol% Nb of ^{M 2, M 3} is Ni, Co, Fe, Pd, Ag, Au , Pb and Ga are applied when they are at least one element from the group consisting of:

All that is previously described, in particular at least 75 mol%, or 100 mol% Nb of the total amount of at least 50 mol% or M2 of the total amount of ^{M 2,} from the ^{group M 3} is made of Ni, Co, Fe and Pd It is applied when it is at least one kind of element.

Everything stated for the stoichiometric coefficients when M ¹ is Te, M ² is Nb and M ³ is at least one element from the group consisting of Ni, Co, Fe and Pd It is particularly advantageously applied.

Advantageous multimetal oxide composition M is up to 0.1, e is 0 or more, the composition M ⁴ is preferably Cs (especially all compositions of the), M ² in this case Preferably it is Bi.

  Other stoichiometries suitable for the purposes of the present invention are the corresponding stoichiometries described in the state of the art cited for stoichiometric multimetal oxide compositions of the formula I.

According to the invention, the X-ray diffraction pattern shows the reflections h, i and k, the diffraction angles (2θ) 22 ± 0.5 ° (h), 27.3 ± 0.5 ° (i) and 28.2 ± 0. Preference is given to a multimetal oxide composition M whose maximum is present at 0.5 ° (k),
The reflection h is the maximum intensity in the X-ray diffraction pattern, has a half width of 0.5 ° or less,
The intensity P _i of the reflection _i and the intensity P _{k of the} reflection k are in accordance with a relational expression of 0.65 ≦ R ≦ 0.85, and R is an expression R = P _i / (P _i + P _k ).
Is the intensity ratio determined by
The half widths of the reflection i and the reflection k are each 1 ° or more.

All numerical values set forth in this specification with respect to X-ray diffraction pattern based on X-ray diffraction pattern obtained using Cu-K _alpha radiation as the X-ray (Siemens diffractometer, Theta-ThetaD-5000, tube voltage 40 kV, Tube current 40 mA, aperture V20 (variable), collimator V20 (variable), second monochromator aperture (0.1 mm), detector aperture (0.6 mm), measurement interval (2θ) 0.02 °, measurement time per step 2.4 seconds, detector: scintillation counter). The determination of the reflection intensity of the X-ray diffraction pattern in this specification is based on German Patent (DE-A) 198 35 247, German Patent (DE-A) 10122027 or German Patent (DE-A) 100 51 419 and German Patent (DE-A) 100 51 419. DE-A) No. 10046672, the same applies to the definition of the half width.

  According to the invention, R according to the relation 0.67 ≦ R ≦ 0.75 is preferred, wherein R is in particular 0.69 to 0.75 or 0.71 to 0.74 or R is 0.72. It is.

The X-ray diffraction pattern of the multimetal oxide composition M, which is advantageous according to the invention, shows, besides the reflections h, i and k, generally also those reflections for which a maximum exists at the following diffraction angles (2θ):
9.0 ± 0.4 ° (l)
6.7 ± 0.4 ° (o) and 7.9 ± 0.4 ° (p).

  An X-ray diffraction pattern which additionally shows the reflection where the maximum exists at a diffraction angle (2θ) = 45.2 ± 0.4 ° (q) is advantageous.

  The X-ray diffraction pattern of the preferred multimetal oxide composition M often has reflections of 29.2 ± 0.4 ° (m) and 35.4 ± 0.4 (n) (position of maximum).

When the reflection h has an intensity of 100, it is preferable that the reflections i, l, m, n, o, p, and q have the following intensity on the same intensity scale.
i: 5-95, preferably 5-80, especially 10-60,
1: 1 to 30,
m: 1 to 40,
o: 1 to 30,
p: 1 to 30 and q: 5 to 60.

  If the X-ray diffraction pattern of the multimetal oxide composition M obtained according to the invention additionally has any of the aforementioned additional reflections, the half-width of this reflection is generally greater than or equal to 1 °. The multimetal oxide composition M obtained according to the invention, whose X-ray diffraction pattern does not exhibit a reflection having a maximum at 2θ = 50.0 ± 0.3 °, in addition to the above values (individually or together), is It is particularly advantageous.

  The determination of the reflection intensity in the X-ray diffraction pattern according to the invention is described in DE-A-198 35 47, DE-A 100 51 419 and DE-A 100 46 672. It is a decision.

  If the multimetal oxide composition M obtained according to the invention does not directly correspond to the above-mentioned advantageous properties, the multimetal oxide composition M obtained according to the invention can be prepared, for example, according to DE-A 10 254 279. This can be accomplished by washing with a suitable liquid as described in the item. Possible liquids for this purpose are, for example, organic acids or aqueous solutions thereof (eg oxalic acid, formic acid, acetic acid, citric acid and tartaric acid) and inorganic acids and aqueous solutions thereof (eg nitric acid or telluric acid) or alcohols or hydrogen peroxide and It is an aqueous solution. Of course, it is also possible to use a mixture of the aforementioned cleaning liquids for the purpose of cleaning. Further, Japanese Patent Application Laid-Open No. Hei 7-232701 describes a suitable cleaning method.

  After washing, there remains a multimetal oxide composition M ′ whose stoichiometry generally also corresponds to formula I and can be used as a catalytically active composition in the same way as multimetal oxide composition M. In general, the multimetal oxide composition M 'has an advantageous X-ray diffraction pattern of the type described above.

An advantageous multimetal oxide composition (which can be used similarly to multimetal oxide composition M or multimetal oxide composition M ′) further comprises multimetal oxide composition M ″, which is from multimetal oxide composition M or multi-metal oxide compositions obtained therefrom M 'obtained by the invention, for example (for example by spraying) solution (e.g., aqueous solution) of the elements M ³ impregnated and then dried ( (Optionally at a temperature below 100 ° C.) and subsequently heat-treated in the same way as the precursor composition of the multimetal oxide composition M (preferably in a stream of inert gas, preferably without air, omitting any previous decomposition). Wherein the stoichiometric coefficient d is 0 or less than 0.5. The stoichiometry of the resulting composition M ″ is represented by the general formula I of the multimetal oxide composition M It is advantageously selected to correspond. Carbonates of the elements M ^3, bicarbonates, nitrates and / or use and / or elemental M ³ is an organic compound of an aqueous solution of a halide using an aqueous solution which is present as a complex with (e.g., acetate or acetylacetonate) this It is particularly advantageous in manufacturing variants. However, as described in EP-A-1266688 (vapor phase deposition), doping of the multimetal oxide composition M or M 'with d equal to or less than 0.5 is carried out. You can also.

  Of course, the multimetal oxide compositions M obtained according to the invention can also be diluted with fine particles, such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide and niobium oxide, for example with colloidal materials, which are substantially dilute. Act only as a diluent and are used in diluted form as a catalytically active composition.

  The dilution mass ratio may be up to 9 (diluent): 1 (active composition), ie possible dilution mass ratios are for example 6 (diluent): 1 (active composition) and 3 (diluent). : 1 (active composition). The diluent can be compounded before and / or after calcination, but is generally compounded before drying. The diluent can be included in at least one part of the solution.

  If the compounding occurs before drying or calcining, the diluent must be selected so that the diluent is maintained substantially in the liquid medium or during calcining. This is the case, for example, in the case of oxides which are generally calcined at a suitably high temperature.

  Where the diluent material is formulated into at least one part of the solution (eg, in the form of a sol), the term solution for the purposes of the present invention includes all systems except for the diluent material added. It is also a generally particulate, insoluble, inert solid.

  The multimetal oxide compositions M and the compositions M 'and M "obtained according to the invention can be used as such or in the diluted form just described, for the heterogeneous contacting of saturated and / or unsaturated hydrocarbons and aldehydes. Suitable as active composition for gas phase oxidation (including oxydehydrogenation) and / or ammoxidation.

  These saturated and / or unsaturated hydrocarbons are in particular ethane, ethylene, propane, propene, n-butane, isobutane and isobutene. The desired products are in particular acrolein, acrylic acid, methacrolein, methacrylic acid, acrylonitrile and methacrylonitrile. However, the multimetal oxide compositions are also suitable for heterogeneous catalytic partial gas phase oxidation and / or ammoxidation of compounds such as acrolein and methacrolein.

  However, ethylene, propylene and acetic acid may also be target products.

Complete oxidation of hydrocarbons for the purposes of the present invention is that all of the carbon present in the hydrocarbons are converted to oxides of carbon (CO, CO _2).

  All other reactions of molecular oxygen with hydrocarbons are included in the term partial oxidation in the present invention. The additional participation of ammonia in the reaction characterizes partial ammoxidation.

  The multimetal oxide compositions M, M 'and M "obtained as described in this specification are preferably the propane to acrolein and / or acrylic acid, the propane to acrylic acid and / or acrylonitrile, and the propylene to acrolein. And / or convert acrylic acid, propylene to acrylonitrile, isobutane to methacrolein and / or methacrylic acid, isobutane to methacrylic acid and / or methacrylonitrile, ethane to ethylene, ethane to acetic acid and ethylene to acetic acid. As a catalytically active composition.

  Carrying out these partial oxidations and / or ammoxidation (the reaction is carried out substantially only as a partial oxidation or only as a partial ammoxidation or in a manner known per se as an overlap of the two reactions by the choice of the ammonia content of the reaction mixture) For example, see WO 98/22421) are known per se from the prior art stoichiometric I multimetal oxide compositions and the reaction can be carried out in a substantially similar manner.

  If crude propane or crude propylene is used as hydrocarbon, it preferably has the composition described in DE 10246119 or DE 10118814 or PCT / EP / 02/0473. The methods described therein are likewise advantageously used.

  Partial oxidation of propane to acrylic acid carried out using a multimetal oxide active composition M (or M 'or M ") as catalyst is described, for example, in EP 608838, WO0029106, JP 10-36311. And EP 112987.

  As a source of the required molecular oxygen, it is possible to use, for example, air, oxygen-accumulated air or oxygen-deficient air or pure oxygen.

The process is advantageous when the starting mixture of the reaction gas does not contain a noble gas, especially helium, as an inert diluent gas. Furthermore, the reaction gas starting mixture can, of course, contain inert diluent gases such as N ₂ , CO and CO _{2 in} addition to propane and molecular oxygen. According to the invention, steam is preferred as a component of the reaction gas mixture.

In this case, for example, the multimetal oxide active compositions M, M obtained according to the invention at a reaction temperature of 200 to 550 ° C. or 230 to 480 ° C. or 300 to 440 ° C. and a pressure of 1 to 10 bar or 2 to 5 bar The reaction gas starting mixture passing through the 'or M "can have, for example, the following composition:
1 to 15% by volume of propane, preferably 1 to 7% by volume,
44-99% by volume of air and 0-55% by volume of steam.

  Preference is given to a reaction gas starting mixture with water vapor.

Other possible compositions of the reaction gas starting mixture are:
70-95% by volume of propane,
5-30% by volume of molecular oxygen and 0-25% by volume of steam
It is.

It is self-evident that the process results in a product gas mixture that does not consist solely of acrylic acid. Not rather only product gas mixture further unreacted propane, propene, _{acrolein, CO 2, CO, H 2} O, acetic acid, has a secondary component such as propionic acid, to be separated acrylic acid therefrom No.

  This can be carried out in a known manner from heterogeneous catalytic gas-phase oxidation of propene to acrylic acid.

  In this separation, the acrylic acid present in the product gas mixture is absorbed by water or a high boiling inert hydrophobic organic solvent (e.g., diphenyl ether and difil, which can further contain additives such as dimethyl phthalate). (Mixture). The resulting mixture of absorption medium and acrylic acid can subsequently be treated in a manner known per se by rectification, extraction and / or crystallization to give pure acrylic acid. Alternatively, a basic separation of acrylic acid from the product gas mixture can be carried out by fractional condensation, as described, for example, in DE-A-199 24 532.

  The aqueous acrylic acid condensate obtained from said condensation can subsequently be further purified, for example, by fractional crystallization (eg, suspension crystals and / or layer crystals).

  The residual gas mixture remaining after the basic separation of acrylic acid consists in particular of unreacted propane, which is preferably recycled to the gas-phase oxidation. For this purpose, some or all of the unreacted propane can be separated from the residual gas mixture, for example by fractional pressure rectification, and subsequently recycled to the gas-phase oxidation. However, it is more preferred to contact the residual gas with a hydrophobic organic solvent which can advantageously absorb propane in the extractor (eg by passing the gas through the solvent).

  The propane absorbed is liberated again by subsequent desorption and / or stripping with air and can be recycled to the process according to the invention. Thus, an economical overall propane conversion can be achieved. The propene formed as a secondary component, as with other separation methods, generally does not separate from propane or only incompletely separates from propane and is circulated with propane. This is also the case for other homologous saturated and olefinic hydrocarbons. In particular, this applies generally to the heterogeneous catalytic partial oxidation and / or ammoxidation of saturated hydrocarbons according to the invention.

  In these cases, the advantage is that the multimetal oxide compositions M, M 'and M "obtained according to the invention can heterogeneously catalyze the partial and / or ammoxidation of homologous olefinic hydrocarbons which give the same end products. Is recognized.

  Thus, the multi-components obtained according to the invention as active compositions using molecular oxygen as described in DE-A 101 188 814 or PCT / EP / 02/04073 or JP-A-7-53448. The metal oxide composition M, M ′ or M ″ can be used to produce acrylic acid by heterogeneous catalytic partial gas phase oxidation of propene.

  This means that a single reaction zone A is sufficient to carry out the method. The only catalytically active composition present in this reaction zone is the multimetal oxide catalyst M, M 'and / or M "obtained according to the invention.

  This is striking because heterogeneous catalytic gas-phase oxidation of propene to acrylic acid generally occurs in two steps that follow one another in time. In the first step, propene is generally oxidized to mainly acrolein, and the acrolein formed in the first step is generally oxidized to acrylic acid in the second step.

  Thus, conventional methods of heterogeneous catalytic gas phase oxidation of propene to acrylic acid generally use a particular catalyst type adapted to the oxidation step corresponding to each of the two oxidation steps described above.

  In other words, the conventional method of heterogeneous catalytic gas-phase oxidation of propene to acrylic acid differs from the method of the present invention and uses two reaction zones.

  Of course, it is possible that only one or more polymetal oxide catalysts M, M 'and / or M "obtained according to the invention are present in a single reaction zone A of the partial oxidation step of propene. The catalyst used can, of course, be diluted with, for example, the inert materials suggested as support materials for the present invention.

  In the method of partial oxidation of propene, the temperature may be constant along single reaction zone A, or may vary along single reaction zone A, regulated by a heating medium. If the temperature fluctuates, the temperature can increase or decrease.

  If the process according to the invention for the partial oxidation of propene is carried out as a fixed-bed oxidation, it is preferably carried out in a shell and tube reactor in which the tubes are loaded with catalyst. A liquid heating medium, typically a salt bath, generally passes around the catalyst tube.

  Subsequently, a plurality of temperature zones along the reaction zone A can be realized in a simple manner by passing one or more salt baths through a section along the catalyst tube around the catalyst tube.

  Viewing the reactor as a whole, the reaction gas mixture passes through the catalyst tubes in a countercurrent or countercurrent to the salt bath. The salt bath itself can have a flow that is purely parallel to the catalyst tube. However, this may, of course, overlap with the traversing flow. Overall, the salt bath may have a meandering flow around the catalyst tube, which may be present in a countercurrent or countercurrent to the reaction gas mixture when the reactor is viewed as a whole.

  In the method of partial oxidation of propene, the reaction temperature may be 200-500 ° C. along the entire reaction zone A. Generally, it is 250-450 ° C. The temperature is preferably from 330 to 420 ° C, particularly preferably from 350 to 400 ° C.

  The working pressure of the process for the partial oxidation of propene may be 1 bar, less than 1 bar or greater than 1 bar. Typical working pressures according to the invention are between 1.5 and 10 bar, often between 1.5 and 5 bar.

  The propene used in the method of partial oxidation of propene does not have to meet particularly high purity requirements.

  As the propene of the process described above, and as generally applicable to all one-step or two-step methods of heterogeneous catalytic gas-phase oxidation of propene to acrolein and / or acrylic acid, for example, It is possible to use propene which has one of the standards (known as crude propene) without problems.

  Of course, all of the aforementioned possible components of propene are generally disadvantageous for the process of one- or two-stage heterogeneous catalytic gas-phase oxidation of propene to acrolein and / or acrylic acid or the use of crude propene in known processes. In each case from 2 to 10 times the above individual amounts of crude propene.

  This is especially the case when the entrained components are compounds which are present, as well as saturated hydrocarbons, in either case as steam, carbon oxides or molecular oxygen, as inert diluent gas or as reactants of the process in considerable amounts. Corresponds to. Crude propene is generally used as it is with circulating gas, air and / or molecular oxygen and / or dilution air and / or inert gas for use in the process of heterogeneous catalytic gas phase oxidation of propene to acrolein and / or acrylic acid. Mix.

  As propene source for the process according to the invention, it is possible to use propene which is formed as a by-product in a manner different from the process according to the invention and contains, for example, up to 40% by weight of propane. The propene may be additionally associated with other accompanying components that do not significantly interfere with the method of the present invention.

  As oxygen source for the method of partial oxidation of propene, it is possible to use pure oxygen or air or air with accumulated oxygen or air deficient in oxygen.

In addition to molecular oxygen and propene, the reaction gas starting mixture used in the process for the partial oxidation of propene generally further contains at least one diluent gas. Possible diluent gas is nitrogen, carbon oxide, noble gases and methane, ethane, lower hydrocarbons such as propane (higher hydrocarbons, for example C ₄ - should hydrocarbon avoid). Water vapor is often used as a diluent gas. Mixtures of gases selected from the aforementioned gases are often used as diluent gases in the process of partial oxidation of propene.

  The heterogeneous catalytic partial oxidation of propene is preferably carried out in the presence of propane.

The reaction gas starting mixture for the propene oxidation process typically has the following composition (molar ratio):
Propene: oxygen; water: other diluent gas = 1: (0.1 to 10): (0 to 70): (0 to 20).

  The ratio is preferably 1: (1-5) :( 1-40) :( 0-10).

  If propane is used as the diluent gas, part of the propane can be advantageously oxidized to acrylic acid as described above.

According to the invention, the reaction gas starting mixture advantageously has as diluent gas molecular nitrogen, CO, CO ₂ , steam and propane.

  The propane: propene molar ratio may be from 0 to 15, often from 0 to 10, preferably from 0 to 5, in particular from 0.01 to 3, in the propene oxidation step.

  The space velocity of propene on the catalyst charge of the partial oxidation of propene may be, for example, 40-250 standard l / lh. The space velocity of the reaction gas starting mixture on the catalyst is often between 500 and 15000 standard l / l.h, preferably between 600 and 10000 standard l / l.h, in particular between 700 and 5000 standard l / l.h.

It is clear that the method of partial oxidation of propene to acrylic acid results in a product gas mixture that does not consist solely of acrylic acid. Rather a product gas mixture further unreacted propane and propane, _{acrolein, CO, CO 2, H 2} O, acetic acid, a secondary component such as propionic acid, must be separated acrylic acid from these.

  This can be carried out as is generally known from a two-step heterogeneous catalytic gas-phase oxidation of propene to acrylic acid (performed in two reaction zones).

  In this separation, the acrylic acid present in the product gas mixture is absorbed by water or a mixture of diphenyl ether and difil, which may further contain additives such as high boiling inert hydrophobic organic solvents (eg dimethyl phthalate). ) Can be separated by absorption. The resulting mixture consisting of the absorption medium and acrylic acid can subsequently be processed in a known manner by rectification, extraction and / or crystallization to give pure acrylic acid. Alternatively, the basic separation of acrylic acid from the product gas mixture can be carried out by fractional condensation, for example as described in DE 199 24 532.

  The aqueous acrylic acid condensate obtained by said condensation can subsequently be further purified, for example, by fractional crystallization (eg, suspension crystals and / or layer crystals).

  The residual gas mixture remaining after the basic separation of the acrylic acid has in particular unreacted propene (and optionally propane). It can be separated from the residual gas mixture, for example, by fractional pressure rectification and subsequently recycled to the gas-phase oxidation according to the invention. However, it is more preferred that the residual gas is contacted with a hydrophobic organic solvent which can advantageously absorb propene (and optionally propane) in the extraction device (eg by passing the gas through the solvent).

  The absorbed propene (and optionally propane) is liberated again by subsequent desorption and / or stripping with air and can be recycled to the process according to the invention. Thus, an economical overall propene conversion can be achieved. If the propene is partially oxidized in the presence of propane, the propene and propane are advantageously separated off and recycled together.

  The multimetal oxides M, M 'and / or M "obtained according to the invention can be used as catalyst for the partial oxidation of isobutane and / or isobutene to methacrylic acid in a completely similar manner.

  The oxides may be used for the ammoxidation of propane and / or propene, as described, for example, in EP 529853, DE 2351151, JP-A-6-166668 and JP-A-7-232701. Can be.

  The oxide can be used for ammoxidation of n-butane and / or n-butene as described in JP-A-6-212767.

  The oxides can be used in oxydehydrogenation of ethane to ethylene or further in the reaction to give acetic acid as described in US Pat. No. 4,250,346 or EP 261264.

  Said oxides can be used for the partial oxidation of acrolein to acrylic acid as described in DE 10261186.

  The multimetal oxide compositions M, M 'and / or M "obtained according to the invention can be combined with other multimetal oxide compositions (for example by mixing their finely divided powders and, if appropriate, pressing And can be calcined or mixed as a (preferably aqueous) slurry, dried and calcined (e.g. a polymetallic oxide of stoichiometric formula I with d = 0 as described in EP 529853). Once again, the calcination is preferably carried out under an inert gas.

  The resulting multimetal oxide composition (hereinafter referred to as total composition) is advantageously at least 50% by weight, preferably at least 75% by weight, in particular at least 90% by weight, or at least 95% by weight according to the invention. The resulting multimetal oxide compositions M, M ′ and / or M ″ are likewise suitable for the partial oxidation and / or ammoxidation described herein.

  All compositions advantageously do not show a reflection with a maximum at 2θ = 50.0 ± 3.0 ° in the X-ray diffraction pattern.

  If the total composition shows a reflection with a maximum at 2θ = 50.0 ± 3.0 °, the mass proportion of the multimetal oxide compositions M, M ′ and / or M ″ obtained according to the invention is 80%. Advantageously, it is at least 90% by weight, or at least 90% by weight, or at least 95% by weight, for example by washing which is not carried out quantitatively in the process of the invention for producing the multimetal oxide composition M '. A composition is obtained.

  The entire composition is advantageously shaped into bodies of the shape described for the multimetal oxide compositions M, M 'and / or M "according to the invention.

  The advantage of the multimetal oxide compositions M, M 'and / or M "obtained according to the invention is that they generally have an improved activity when used as active compositions for the partial or ammoxidation described herein. And / or based on its relatively uniform structure resulting in selectivity.

  For the purpose of heterogeneous catalytic partial gas phase oxidation of propane to acrylic acid, the multimetal oxide compositions M, M 'and / or M "and the multimetal oxide compositions or catalysts in which they are present are advantageous. As described in German Patent No. 101 22027.

EXAMPLES AND COMPARATIVE EXAMPLES A) Preparation of Coated Catalyst S1 with Multimetal Oxide Composition M Obtained According to the Invention To prepare the partial solution A, 4000 ml of water were first heated to 80 ° C. in a glass vessel. While maintaining the temperature at 80 ° C., 706.2 g (= 4 mol of Mo) of ammonium heptamolybdate having a MoO ₃ content of 81.53% by weight, HC Starck, Goslar (Germany) were dissolved therein with stirring. Also at 80 ° C., 141.0 g (= V1.2 mol) of ammonium metavanadate having a V ₂ O ₅ content of 77.4% by weight, HC Starck, Goslar (Germany) were stirred into the resulting clear solution. Then put in and melted in this. Again at 80 ° C. 211.28 g of Te (OH) ₆ Fluka Chemie, Buchs (Switzerland) with a Te (OH) ₆ content of 99% or more, Buchs (Switzerland), were stirred into the resulting clear solution at 211.28 g. Put it in and melt it. The resulting reddish solution was cooled to 25 ° C. and water with a temperature of 25 ° C. was added with stirring, resulting in a clear and transparent partial solution A having a total volume of 4500 ml.

  To prepare the partial solution B, 221.28 g of ammonium niobium oxalate having an Nb content of 20.1% by weight (Nb 0.48 mol), HC Starck, Goslar (Germany) are added to 1000 ml of water heated to 80 ° C. Melted. The resulting clear, clear solution was cooled to 25 ° C. and water, also having a temperature of 25 ° C., was added, resulting in a clear, clear, partial solution B having a total volume of 1500 ml.

  The two stable aqueous solutions A and B are subsequently fed into two inlet sections of a Y-shaped plastic tee via two separate plastic hoses by means of two ProMinent laboratory dosing pumps, type gamma g / 4a. Transported to The three tubular sections of the Tee (two inlets and one outlet) each had an inner diameter of 5 mm and a length of 38 mm. Solution A was transported at a flow rate of 1500 ml / h, and solution B was transported at a flow rate of 500 ml / h. The two solution streams A and B were combined inside the T-tube, giving a total solution flow of 2000 ml / h, which flowed to the outlet of the T-tube. A static mixer model SMXS, Sulzer Chemtech, Obermoerlen-Ziegenberg (Germany) was placed in the discharge section. The diameter of the static mixer was 4.8 mm and the length of the mixer rod was 35 mm. The end of the outlet of the Tee is connected directly to the spray head of a spray dryer (Niro Atomizer, model Minor Hi-Tec Niro, Copenhagen, Denmark), which sprays the supplied mixed solution stream (liquid particles). Size of about 30 μm). Inside the nebulizer head, which is arranged in the center of the hot air distributor mounted on the head of the spray dryer, the mixed solution stream is rotated at 30,000 rpm via a 15 cm long connecting line having an inner diameter of 6 mm with a spray disk ( Channel disc). The obtained spray mist was dried by a flow of hot air (forward flow, inlet temperature 320 ° C, outlet temperature 105 ° C). A total of 6000 ml of the total solution stream could be spray-dried for 3 hours.

From a total solution flow rate of 2000 ml / h, the internal diameter of the discharge section of the T-tube and the length of the static mixer cross-section of 35 mm, the combined partial solution streams A and B are converted into a substantially uniform mixed solution stream. It is possible to calculate a time t ^{1 of} .2 seconds. If the transfer of the mixed solution streams to the position of the spray from the discharge part of the static mixer via a connection line of 15 cm length into a sprayer head having an inner diameter of 6 mm is additionally taken into account, the flow of the solution streams A and B is taken into account. coupled from the time less than 9 seconds to spray the mixed solution flow time T ² is calculated. If it contains a drying time of less than 1 second, the time t ³ from binding of the solution to a dry powder is less than 10 seconds. Mo ₁ V is added to the spray-dried powder from which the elements Mo, V, Nb and Te are obtained, corresponding to the stoichiometry of solutions A and B derived from the weighed amounts and the selected partial solution streams (3: 1). Present at a molar stoichiometry of _0.3 Nb _0.12 Te _0.23 (the clear section of a 15 cm long clear plastic hose with an inner diameter of 6 mm, with the outlet of the Tee not directly connected to the sprayer head of the spray dryer) Is connected to the end of the discharge section of the tee and through which the mixed solution stream is conveyed to the collecting vessel located below, the mixed solution stream is deposited over the entire length of the plastic hose. And a clear test showed that it was all clear and clear when it reached the collection container. Filtration tests on the mixed solution flowing from the plastic hose confirmed that it was free of solids).

  150 g of the spray-dried powder obtained are heated at room temperature (25 ° C.) at a heating rate of 5 ° C./min in air (10 standard l / h) in a rotating spherical furnace, as shown in FIG. 1 of DE 101 18 814. ) To 275 ° C. Immediately thereafter, the powder was heated from 275 ° C. to 650 ° C. at a heating rate of 2 ° C. per minute in a stream of molecular nitrogen (10 standard l / h), and this temperature was maintained for 6 hours while maintaining the flow of nitrogen. . Subsequently, the powder was naturally cooled to 25 ° C. while maintaining a nitrogen flow. A black fired multimetal oxide active composition M was obtained.

The calcined material was ground in a Retsch mill (centrifugal mill, model ZM100, Retsch GmbH, Germany) (particle size 0.12 mm or less). 162 g of a spherical support having a diameter of 2.2 to 3.2 mm was coated with 75 g of the obtained powder (R _z = 45 μm, support material = Steatite C220, Ceramtec, Germany), the total pore volume of the support was Not more than 1% by volume relative to the total volume of the body). For this purpose, the support sphere was placed in a coating drum having an internal volume of 2 liters (the inclination of the center axis of the drum with respect to the horizontal was 30 °). The drum was rotated at 25 rpm. Nebulizer nozzle operated using 300 standard l / h of compressed air over a period of 60 minutes on a support sphere initially charged with a mixture of glycerin and water (mass ratio of glycerin: water = 1: 3) for a total of 30 ml And sprayed uniformly. The nozzles were arranged such that the spray cone moistened the support by means of a conveyor projection on the drum, which was transported to the highest position of the inclined drum in the upper half of the rolling surface. The active composition powder was introduced into the drum using a powder screw, the introduction position of the powder being located inside the rolling surface or below the spray cone. As a result of the cyclic repetition of wetting and powder coating, the first coated substrate itself became the substrate over a subsequent period of time.

  After the coating was completed, the coated support was dried at 120 ° C. for 16 hours in a conventional drying oven (Binder, Germany, 53 liters internal volume). Glycerin was removed by a subsequent heat treatment at 150 ° C. for 2 hours in air.

A coated catalyst S1 having an active composition content of 32% by weight was obtained.
B) Preparation of Coated Catalyst S2 with Multimetal Oxide Composition M Obtained According to the Invention The method used for A) is repeated, but the partial solution stream A is 3000 ml / h (instead of 1500 ml / h) , Partial solution stream B was 1000 ml / h (instead of 500 ml / h). Further, the inlet temperature of the spray dryer was set to 400 ° C instead of 320 ° C.

^{T 1} is the approximately 0.6 seconds in this case, ^{t 2} is as 4.5 seconds, ^{t 3} is calculated as 5.5 seconds. 6000 ml of the total solution stream were spray-dried over a period of 1.5 hours. The stoichiometry of the spray-dried powder was similarly Mo ₁ V _0.3 Nb _0.12 Te _0.23 . The resulting coated catalyst was coated catalyst S2.
C) Production of coated catalyst S3 having multimetal oxide composition M 'obtained from multimetal oxide composition M obtained according to the invention, multimetal oxide obtained as described in A) after calcination 100 g of the composition M was added to 500 g of a 20% by mass aqueous nitric acid solution.

The obtained aqueous suspension was stirred at 70 ° C. for 7 hours under reflux. It was subsequently cooled to 25.degree. The solids present in the black suspension were separated from the aqueous phase by filtration, washed free of nitrate with water and subsequently dried in a convection oven at 120 ° C. overnight. The dried material is subsequently ground in a Retsch mill in a manner analogous to step A) (particle size 0.12 mm or less), and the powder obtained is further processed as described under A) to give the coated catalyst S3. Was.
D) Preparation of coated catalyst S4 having multimetal oxide composition M ′ obtained from multimetal oxide composition M obtained according to the invention, multimetal oxide obtained as described in B) after calcination 100 g of the composition M were treated with an aqueous nitric acid solution as described under C) and the remaining solids were further treated as described under C) to give the coated catalyst S4.
E) Preparation of coated catalyst CS5 with multimetal oxide composition obtained by a method not according to the invention As described in A), 4500 ml of partial solution A and 1500 ml of partial solution B were each produced at a temperature of 25 ° C. Subsequently, 1500 ml of the partial solution B was stirred into the partial solution A within about 3 seconds. This gave a clear reddish mixed solution C having a temperature of 25 ° C. Immediately thereafter, the continuously stirred mixed solution C was supplied at a volume flow of 2000 ml / h through a plastic hose using a ProMinent experimental metering pump, model gamma g / 4a, while maintaining the temperature at 25 ° C. , Continuously transferred to the sprayer head of the spray dryer used in A), sprayed here as described in A) and dried in a stream of hot air (inlet temperature 320 ° C., outlet temperature 105 ° C.) ).

Mixed solution C was still clear and clear for the first 2 minutes, but noticeable turbidity was observed after only 2.5 minutes. After 5 minutes a significant amount of reddish solids precipitated and after 1 hour a completely opaque reddish aqueous suspension had formed. A homogeneous spray-dried powder was therefore still obtained from the clear transparent solution at the beginning of the spray-drying, but a heterogeneous spray-dried powder having an increasing proportion of precipitated reddish solids after further spray-drying Was obtained, the composition of which was weighed and deviated significantly from the amount initially dissolved to form a mixed solution C (stoichiometry based on the weighed amounts was Mo ₁ V _0.3 Nb _0.12 Te _0.23 The elemental composition of the solid separated by filtration after 1 hour was Mo ₁ V _0.3 Nb _0.6 Te _0.4 The X-ray diffraction pattern of the reddish solid was 5 to 65 °. 3 shows a very broad peak in the 2θ range, which has a maximum amplitude at about 28 °).

The spray-dried powder obtained after spray-drying all solutions / suspensions was mixed homogeneously as described in A), heat-treated (calcined) and further processed to give the coated catalyst CS5.
F) Preparation of coated catalyst CS6 having a multimetal oxide composition obtained from a multimetal oxide composition obtained by a method not according to the invention The multimetal oxide obtained after calcining with E) is described in C) The remaining solids were further treated as described under C) to give the coated catalyst CS6.
G) Test of Coated Catalysts S1 to CS6 Coated catalysts corresponding to V2A steel reaction tubes (length 140 cm, outer diameter 60 mm, inner diameter 8.5 cm) were respectively loaded. The length of the catalyst bed was adjusted to 52 cm (adapted to the center of the reaction tube). A pre-bed made of steatite (C220 CeramTec, diameter 2.2-3.2 mm) having a length of 30 cm was used for preheating the reaction gas mixture. The reaction tube downstream of the catalyst zone was subsequently filled with the same steatite spheres. The reaction tube was externally heated by an electric heating mat over the entire length. The mat temperature was set at 340 ° C. The reaction was carried out at a pressure of 2 bar absolute, a residence time of 2.4 seconds (relative to the catalyst bed), using a feed (reaction gas starting mixture) having a molar composition of propane: air: water = 1: 15: 14. . The selectivity S (mol%) of acrylic acid formation in a single pass through the reaction tube was determined by gas chromatography analysis of the product gas stream. The results shown in the table below were obtained for the coated catalyst used.

  The propane conversion C (mol%) and the selectivity for acrylic acid formation are respectively arbitrary values when the coating catalyst S1 is set to 100.

Ｈ）特開平１１−３０６２２８号からの錯体金属酸化物（１）の製造の本発明による繰り返し
水２９.２１リットルを８０℃に加熱した。８０℃の温度を維持しながら、パラモリブデン酸アンモニウム四水和物（（＝七モリブデン酸アンモニウム）、Ｈ.Ｃ.Ｓｔａｒｃｋ、Ｇｏｓｌａｒ（ドイツ）ＭｏＯ_３含量８１.５３質量％を有する）７.０９ｋｇ、メタバナジン酸アンモニウム（Ｈ.Ｃ.Ｓｔａｒｃｋ、Ｇｏｓｌａｒ（ドイツ）Ｖ_２Ｏ_５含量７７.４質量％を有する）１.４１ｋｇおよびテルル酸（Ｆｌｕｋａ Ｃｈｅｍｉｅ社、Ｂｕｃｈｓ（スイス）Ｔｅ（ＯＨ）_６含量９９％以上を有する）２.１２ｋｇを引き続き相次いでこれに溶解した。得られた溶液に、ＳｉＯ_２含量２０質量％を有するシリカゾル５ｋｇ（ＬｕｄｏｘＡＳ−４０ コロイダルシリカ２.５ｋｇ、水中の４０質量％懸濁液、ＤｕＰｏｎｔ Ｐｒｏｄｕｃｔ、Ａｌｄｒｉｃｈ Ｃｈｅｍ.Ｃｏｍｐ.Ｉｎｃ.Ｍｉｌｗａｕｋｅｅ、米国および水２.５ｋｇから製造した）を最後に添加し、溶液を５０℃に冷却して部分溶液Ａが得られた。

H) Repeat according to the invention for the preparation of the complex metal oxide (1) from JP-A-11-306228 29.21 l of water were heated to 80 ° C. 7.09 kg of ammonium paramolybdate tetrahydrate ((= ammonium heptamolybdate), HC Starck, Goslar (Germany) with a MoO ₃ content of 81.53% by weight, while maintaining a temperature of 80 ° C.) , Ammonium metavanadate (HC Starck, Goslar (Germany) having a V ₂ O ₅ content of 77.4% by weight) and telluric acid (Fluka Chemie, Buchs (Switzerland) Te (OH) ₆ content 99 %), Which were subsequently dissolved one after the other. 5 kg of silica sol with a SiO ₂ content of 20% by weight (2.5 kg of LudoxAS-40 colloidal silica, 40% by weight suspension in water, DuPont Product, Aldrich Chem. Comp. Inc. Milwaukee, USA and water) (Prepared from 2.5 kg) was added lastly and the solution was cooled to 50 ° C. to give a partial solution A.

  2.16 kg of ammonium niobium oxalate (HC Starck, Goslar (Germany) having an Nb content of 20.1% by weight) were dissolved in 8.66 l of water heated to 80 ° C. The solution was subsequently cooled to 50 ° C., and a partial solution B was obtained.

  Partial solutions A and B were combined, mixed at a temperature of 50 ° C. respectively, and spray-dried as described under A) (partial solution stream A: 1570 ml / h, partial solution stream B: 430 ml / h). .

  Tests similar to A) showed that the mixed solution stream was free of sediment until the time it was spray-dried (the sol used was also clear and transparent).

Claims (21)

Stoichiometric formula I:
^{_{Mo 1 V a M 1 b M}} 2 c M 3 d M 4 e O n (I)
(Where
M ¹ is at least one element from the group consisting of Te and Sb;
M ² is at least one element from the group consisting of Nb, Ti, W, Ta, Bi, Zr and Re;
M ³ represents Pb, Ni, Co, Fe, Pd, Ag, Pt, Cu, Au, Ga, Zn, Sn, In, Ce, Ir, Sm, Sc, Y, Pr, at least from the group consisting of Nd and Tb One element,
M ⁴ is at least one element from the group consisting of Li, Ns, K, Rb, Cs, Ca, Sr, and Ba;
a is 0.01 to 1,
b is a number from 0 to 1;
c is a number greater than 0 and up to 1;
d is a number not less than 0 and not more than 0.5,
e is a number from 0 to 1;
n is a number determined by the valence and frequency of elements other than oxygen in (I))
Is a method for producing a multimetal oxide composition M represented by the formula: mixing in a solvent a starting compound necessary for producing the multimetal oxide composition M of the element components contained in the multimetal oxide composition M Since the solution is continuously produced, the mixed solution is continuously supplied to the drying device to remove the solvent, and the obtained solid is heat-treated at a high temperature, and the heat treatment is performed at 200 to 1200 ° C. In the method for producing the multimetal oxide composition M, at least two spatially separated starting compounds required for producing the multimetal oxide composition M of the elemental components contained in the multimetal oxide composition M First, a partial solution is prepared, which contains each of the required partial amounts of the starting compounds dissolved therein, at least two partial solution streams are produced from the two or more partial solutions, and the two or more partial solution streams are combined. To form a total solution stream and mix Through the zone, a mixed solution stream is formed containing the entire amount of the required starting compound dissolved in the mixing zone, and the mixed solution stream breaks down into fine liquid particles in the mixing zone or The mixed solution stream is discharged, and subsequently decomposed into fine liquid particles, and the fine liquid particles of the mixed solution are dried by contact with hot gas, and the obtained solid is heat-treated at a high temperature. A method for producing a multimetal oxide composition M, which comprises sintering at a temperature of from 1,200 ° C to 1,200 ° C.   2. The process according to claim 1, wherein the solids content of the mixed solution stream, expressed as the total metal content, is from 1 to 30% by weight.   2. The process according to claim 1, wherein the solids content of the mixed solution stream, expressed as the total content of metals contained, is between 5 and 20% by weight.   4. The method according to claim 1, wherein an aqueous solvent is used as the solvent.   5. The process according to claim 1, wherein the temperature of the two or more partial solution streams is between 15 and 40.degree.   5. The method according to claim 1, wherein the temperature of the two or more partial solution streams is between 20 and 30.degree.   7. The method according to claim 1, wherein the number of partial solutions is from 2 to 5.   8. The process according to claim 1, wherein the process from the time when the joining of the two or more partial solution streams to form the total solution stream starts to the time when the mixed solution stream completely decomposes takes less than 2 minutes. The method of claim 1.   8. The process according to claim 1, wherein the process from the time when the joining of the two or more partial solution streams to form the total solution stream starts until the mixed solution stream completely decomposes takes less than 30 seconds. The method of claim 1.   8. The process according to claim 1, wherein the process from the time when the joining of the two or more partial solution streams to form the total solution stream starts until the mixed solution stream completely decomposes takes less than 20 seconds. The method of claim 1.   The method according to any one of claims 1 to 10, wherein a is from 0.05 to 0.6.   The method according to any one of claims 1 to 11, wherein b is from 0.01 to 1.   The method according to any one of claims 1 to 12, wherein c is from 0.01 to 1.   14. The method according to claim 1, wherein d is between 0.0005 and 0.5.   a is 0.1 to 0.6, b is 0.1 to 0.5, c is 0.1 to 0.5, d is 0.001 to 0.5, and e 15. The method according to any one of claims 1 to 14, wherein is a number from 0 to 0.5. Any one method according to at least 50 mole% of the total amount of M ² from claim 1 is Nb and / or Ta to 15. M ³ is Ni, Co, any one process of claim 1 is at least one element from the group consisting of Fe and Pd to 16. M ¹ is Te, ^{M 2} is Nb, ^{M 3} is Ni, Fe, method of any one of claims 1 is at least one element from the group consisting of Co and Pd to 17 .   19. The method according to claim 1, wherein the at least one partial solution further comprises at least one fine particle-diluting material from the group consisting of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide and niobium oxide. The method of claim 1.   20. Heterogeneous catalytically active saturated and / or unsaturated hydrocarbons, characterized in that the multimetal oxide composition M obtained by the process according to claim 1 is used as an active composition. Phase partial oxidation and / or ammoxidation.   20. A multimetal oxide composition M obtained by the method according to any one of claims 1 to 19.