DE10359027A1 - Manufacture of multi-metal oxide composition, e.g. for hydrocarbon oxidation, involves preparing solutions containing specific metal complex, forming mixed solution stream, breaking formed stream into droplets, and calcining dried droplets - Google Patents

Abstract

Solution streams are produced from solutions containing partial amounts of starting compounds of elemental constituents of multi-metal oxide composition, and combined to form a total solution stream (S1). S1 is mixed, to form a mixed solution stream (S2). S2 is broken into fine droplets and dried. The solid obtained is calcined at 200-1200[deg]C, to obtain a multi-metal oxide composition. At least two physically separate solutions containing partial amounts of starting compounds of elemental constituents of multi-metal oxide composition in dissolved form are prepared. Solution streams are produced from the obtained solution and combined, to form a total solution stream. The total solution stream is passed through a mixing zone and mixed solution stream comprising the total amount of the required starting compounds in dissolved form is formed. The mix solution stream is broken into fine droplets in the mixing zone or after discharging from the mixing zone. The fine droplets are contacted with hot gas and dried. The solid obtained is treated thermally at elevated temperature to obtain multi-metal oxide composition. The thermal treatment is calcination performed at 200-1200[deg]C. The multi-metal oxide composition has stoichiometry of: Mo1VaM1>bM2>cM3>dM4>eOn. M1>tellurium or antimony; M2>niobium, titanium, tungsten, tantalum, bismuth, zirconium or rhenium; M3>lead, nickel, cobalt, iron, palladium, silver, platinum, copper, gold, gallium, zinc, tin, indium, cerium, iridium, samarium, scandium, yttrium, praseodymium, neodymium or terbium; M4>lithium, sodium, potassium, rubidium, cesium, calcium, strontium or barium; a : 0.01-1; b, c, e : above 0-1; d : above 0-0.5; and n : number determined by the valence and abundance of elements other than oxygen. Independent claims are included for; (1) a multi-metal oxide composition; and (2) A method of heterogeneously catalyzed partial gas phase oxidation and/or ammoxidation of saturated and/or unsaturated hydrocarbon using the multi-metal oxide composition as active composition.

Description

The present invention relates to a process for preparing a multimetal oxide composition M of general stoichiometry I. Mo ₁ V _a M ¹ _b M ² _c M ³ _d M ⁴ _e O _n (I) With
M ¹ = at least one of the elements from the group comprising Te and Sb;
M ² = at least one of the group consisting of Nb, Ti, W, Ta, Bi, Zr and Re;
M ³ = at least one of the group consisting of Pb, Ni, Co, Fe, Pd, Ag, Pt, Cu, Au, Ga, Zn, Sn, In, Ce, Ir, Sm, Sc, Y, Pr, Nd and Tb;
M ⁴ = at least one of the elements selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, Ba;
a = 0.01 to 1,
b = ≥ 0 to 1,
c => 0 to 1,
d = ≥0 to 0.5,
e = ≥ 0 to 1 and
n = a number which is determined by the valency and frequency of the elements other than oxygen in (I),
in which from the required for the preparation of the multimetal oxide M starting compounds of the elemental constituents contained in the M Multimetalloxidmasse in a solvent continuously produces a mixture solution, the mixture solution continuously a drying device for removing the solvent feeds and thermally treated the resulting solid at elevated temperature, said the thermal treatment comprises calcination at 200 to 1200 ° C.

multimetal the general stoichiometry I and methods for their preparation are known (see, for example, EP-A 318295, EP-A 512846, EP-A 767164, EP-A 895809, EP-A 529853, EP-A 608838, EP-A 962253, DE-A 10248584, DE-A 10119933 and DE-A 10118814). They are suitable as catalytically active compositions for heterogeneously catalyzed partial Gas phase oxidations and / or ammoxidations of saturated and unsaturated Hydrocarbons, as well as lower aldehydes, e.g. the aforementioned Describe fonts.

Becomes used as hydrocarbon propane and / or propene can thereby as target compounds e.g. Acrolein, acrylic acid and / or acrylonitrile produced become. Acrolein can also itself starting compound for the production the latter two compounds. Form these target links significant intermediates, e.g. for the preparation of polymers Find use, e.g. can be used as adhesives. In Similarly, iso-butane and iso-butene methacrolein and methacrylic acid available. Methacrolein may also be the starting compound for the production of methacrylic acid. The preparation of multimetal oxide materials of general stoichiometry I usually takes place such that one gets from their elemental constituent-containing starting compounds produces an intimate dry mix and this at elevated temperature thermally treated. As starting compounds or sources for the elementary Constituents are essentially all those considered when heated (optionally in air) oxides and / or hydroxides to be able to form. Of course you can as such starting compounds also already oxides and / or hydroxides co-used with the elementary constituent or used exclusively become.

In EP-A 529853 and in EP-A 608838 this is done so, that from the for the production of a multimetal oxide of the general stoichiometry I needed Starting compounds contained in the multimetal oxide composition elementary constituent first at least two spatially producing separate partial solutions containing dissolved starting compounds, the partial solutions combined, the resulting mixture dries and thermally treated the resulting solids drying, wherein the method to be used for drying is arbitrary. By the way over the partial solutions let yourself while producing a comparatively intimate dry mix of sources, disadvantageous to that described in EP-A 529853 or EP-A 608838 Procedure is, however, that when uniting the partial solutions according to these Fonts usually not a mixture solution but a subset of Constituent is obtained as a suspension containing solids.

This is disadvantageous in that the solid contained suspended in the suspension usually has a different composition than the solute contained in the dispersing medium. When drying egg Therefore, such a suspension normally does not contain a chemically homogeneous solid, but rather a solid whose chemical composition has a certain variance throughout the space, which normally can not be completely eliminated during the subsequent thermal treatment and which reduces the catalytic activity of the resulting active masses ,

A Improvement leaves according to EP-A 603836 achieve that for drying the suspension, the process the spray drying is applied, since drying by evaporation in the dispersion medium dissolved according to the given solubilities additionally fractionally precipitated and additionally emphasize said inhomogeneity becomes.

According to EP-A 962253 and according to own Observations of the applicant sets in the context of the preparation described of multimetal oxide materials of general stoichiometry I in combining the partial solutions the suspension forming precipitation with a certain time delay. This time delay let yourself thereby increase that one the partial solutions with solvent dilute and / or cools. In this way one can according to EP-A 962253 beforehand a sufficiently resistant mixture solution generate and this mixture solution drying in a conventional manner. A disadvantage of this procedure However, any use of an increased amount of solvent requires energy increased during drying. About that extended beyond It is the drying time and therefore the risk of a fractionated precipitation in the context of drying. A cooling of the partial solutions also increases the energy required for drying and is beyond insofar only partially advantageous, as this measure, on the one hand, the Kinetics of the precipitation process delayed on the other hand, however, in the vast majority of cases at the same time solubilities degrades, which is an undesirable precipitation promotes.

In similar For example, JP-A 7-315842 recommends a preliminary preparation of a mixture solution then dry them so fast that the solvent is removed before a fractional precipitation can use.

In However, the rule is in a pre-prepared amount of solution a precipitation before it is dried in its total amount, resulting in losses leads. This is especially true when it comes to large-scale approaches.

In JP-A 7-315842, therefore, the desire for a method is expressed in the mixture solution generated continuously and the generated mixture solution by means of a pump immediately the solvent removal supplied and is dried in this before a partial precipitation can take place.

adversely however, JP-A 7-315842 is not such a desirable method to disposal to make.

The JP-A 11-306228 holds Such a procedure even for more or less impossible and Therefore, it aims to the suspension formation, if they already is unavoidable, at least continuously and as possible to effect homogeneously.

The Object of the present invention was therefore a the Request the JP-A 7-315842 corresponding method available put.

Accordingly, a process for producing a multimetal oxide composition M of general stoichiometry I has been disclosed Mo ₁ V _a M ¹ _b M ² _c M ³ _d M ⁴ _e O _n (I) With
M ¹ = at least one of the elements from the group comprising Te and Sb;
M ² = at least one of the group consisting of Nb, Ti, W, Ta, Bi, Zr and Re;
M ³ = at least one of the group consisting of Pb, Ni, Co, Fe, Pd, Ag, Pt, Cu, Au, Ga, Zn, Sn, In, Ce, Ir, Sm, Sc, Y, Pr, Nd and Tb;
M ⁴ = at least one of the elements selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, Ba;
a = 0.01 to 1,
b = ≥ 0 to 1,
c = ≥ 0 to 1,
d = ≥0 to 0.5,
e = ≥ 0 to 1 (or ≥ 0 to 0.5) and
n = a number which is determined by the valency and frequency of the elements other than oxygen in (I),
in which from the required for the preparation of the multimetal oxide M starting compounds of the elemental constituents contained in the M Multimetalloxidmasse in a solvent continuously produces a mixture solution, the mixture solution continuously a drying device for removing the solvent feeds and thermally treated the resulting solid at elevated temperature, said the thermal treatment comprises a calcination at 200 to 1200 ° C, found, which is characterized in that from the required for the preparation of the multimetal oxide M starting compounds of the elemental constituents contained in the M Multimetalloxidmasse first at least two spatially separated, each subsets of required Solubilizing starting compounds containing dissolved solutions, produces from the at least two partial solutions at least two partial solution streams, the at least two partial solution streams to a Gesamtlösun gsstrom brings together, the total solution flow through a mixing zone in which a total amount of the required starting compounds dissolved dissolved containing mixture solution flow, the mixture solution stream either already splits in the mixing zone to finely divided droplets or the mixture solution stream out of the mixing zone and then divided into finely divided droplets which finely divided Drying the mixture solution droplets by contact with hot gas and thermally treated the resulting solid at elevated temperature, wherein the thermal treatment comprises a calcination at 200 to 1200 ° C.

in the Difference to the total solution flow indicates the mixture solution stream a substantially homogeneous composition.

One essential difference between the invention and the method intended in JP-A 7-315842 as desired is that according to JP-A 7-315842 not directly a Gemischlösungsstrom but initially only a mixture solution would be generated the then only transferred by means of a pump in a Gemischlösungsstrom and would be transported to the drying.

It is advantageous according to the invention, already the respective subsets of the required starting compounds solved containing partial solutions to convert into partial solution streams and according to the invention in a Mixture solution stream to change. Background of this advantage forms u.a. of the Fact that it is practically always possible to use subsets of for the preparation of the multimetal oxide M required starting compounds stable partial solutions whereas the total amount used to make it the multimetal oxide M required Starting mixture containing mixture solution even in the state of high dilution is normally thermodynamically unstable and earlier or later least soluble Forming mixed compounds that extends to their solubility limit as a solid precipitate. That is, the partial solutions can in the process according to the invention discontinuously prepared beforehand in any batch quantity and subsequently continuously into the corresponding partial solution flows or be transferred into the mixture solution stream. Of course you can in the method according to the invention but also already the partial solutions be generated continuously.

When Sources for the elemental constituents of the multimetal oxide material M come for the inventive method in principle, all those considered when heating (if necessary in air) to form oxides and / or hydroxides. Of course, as such starting compounds also already oxides and / or hydroxides be used in the elementary constituent or used exclusively. In addition to the oxides and / or hydroxides come as sources of elemental Constituents for the inventive method especially salts of organic and / or inorganic acids in Consideration. By way of example, halides such as e.g. chlorides, Formates, acetates, oxalates, carbonates, nitrates, sulfates and sulfites.

Suitable sources for the element Mo according to the 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 for element V which are to be used according to the invention are, for example, vanadium oxysulfate hydrate, vanadyl acetylacetonate, vanadates such as ammonium metavanadate, vanadyl oxalate, vanadyl sulfate, vanadium oxides such as vanadium pentoxide (V ₂ O ₅ ), vanadium halides such as vanadium tetrachloride (VCl ₄ ) and vanadium oxyhalides such as VOCl ₃ . It can also be used as Vanadinausgangsverbindungen those which contain the vanadium in the oxidation state +4.

According to the invention, tellurium oxides such as tellurium dioxide, metallic tellurium, tellurium halides such as TeCl ₂ , but also telluric acids such as orthotelluric acid H ₆ TeO ₆ are suitable as sources for the element tellurium.

Examples of suitable niobium sources are niobium oxides such as niobium pentoxide (Nb ₂ O ₅ ), niobium oxyhalides such as NbOCl ₃ , niobium halides such as NbCl ₅ , but also complex compounds of niobium and organic carboxylic acids and / or dicarboxylic acids such as oxalates, citrates, tartrates and alkoxides or their Ammonium salts such as niobium ammonium citrate, niobium ammonium oxalate, niobium ammonium tartrate, etc. Of course, the niobium sources which can be used are also the Nb-containing solutions used in EP-A 895809.

Regarding all other possible Elements (in particular of the Pb, Ni, Cu, Co, Fe, Bi and Pd as well as the Alkali and alkaline earth metals) come as suitable starting compounds especially their halides, nitrates, formates, oxalates, acetates, Carbonates and / or hydroxides into consideration. Suitable starting compounds are often also their oxo compounds such. Tungstate or the acids derived from these. Often Ammonium salts are also used here as starting compounds.

Further come as starting compounds and polyanions of the Anderson type into consideration, as e.g. in Polyhedron Vol. 6, no. 2, pp. 213-218, 1987 are described. Another suitable source of literature for polyanions Anderson type Kinetics and Catalysis, Vol. 3, 1999, pp. 401 to 404.

Other Polyanions suitable as starting compounds are e.g. such of the Dawson or Keggin type.

Needless to say, can for the preparation of the invention required partial solutions also complexing agents are used, resulting in the thermal Volatilize and / or decompose treatment of the dried solid (e.g., complexing as oxalate, citrate and / or acetylacetonate).

Further can also the acidic or basic character of the partial solutions by Addition of organic and / or inorganic acids or bases can be specifically altered, about the solubility behavior to influence specifically. As another parameter, the temperature in the production of the partial solutions elevated or be degraded, depending on what affects the solubility beneficial effect (leaves to be determined in a few preliminary tests).

According to the invention preferred is used as a solvent an aqueous one solvent or only water used. In principle, but also come alcohols such as methanol and ethanol as well as organic and / or inorganic acids, e.g. Acetic acid, into consideration. Naturally can also mixtures of the abovementioned solvents are used especially aqueous Mixtures.

Of the Solids content of the mixture solution to be prepared according to the invention vary. Indicated as the total content of those contained in the respective mixture solution Metals amounts he in the inventive method normally at least 0.01% by weight, often at least 0.1% by weight, usually at least 1% by weight, often at least 5% by weight, and if possible at least 10% by weight. As a rule, said solids content becomes 30% by weight. do not exceed. Is multiple he at most 25% by weight or at most 20 wt .-% (the weight percentage in all cases refers to the weight of the respective mixture solution (or the respective mixture solution flow)). In a similar manner as the solids content of the mixture solutions also the corresponding solids content of the partial solutions vary. That is, the The aforementioned quantitative information is also valid for the partial solutions. In particular, the abovementioned solids contents apply to aqueous partial solutions or Mixture solutions. While the solids content as defined above with respect to mixture solution usually the 30 wt .-% - limit will not be exceeded, be the less partial solutions (aqueous and not watery) quite corresponding solids contents up to 50 wt .-% and more possible. With regard to the mixture solution become so high solids contents of a partial solution normally by at least one on the mixture solution involved partial solution compensated with lower solids content. Of course, for partial solutions to be combined according to the invention also different solvents used (e.g., for a partial solution Water and for another partial solution Methanol or ethanol or alcoholic aqueous mixtures).

In In the same way, in the method according to the invention, the temperature to a total solution flow to merge Partial solution flows equal or be different. Normally, in the method according to the invention the temperature of a partial solution flow (especially an aqueous) ≥ 0 ° C and ≤ 100 ° C, preferably ≥ 5 ° C and ≤ 80 ° C, especially preferably ≥ 10 ° C and ≤ 60 ° C, especially preferably ≥ 15 ° C and ≤ 40 ° C, and application technology Expedient to be 20 ° C to 30 ° C.

The promotion of the partial solution streams can in the process according to the invention under normal pressure, under increased pressure or with reduced pressure.

All In general, the term solution is used in this document System that is liquid, optically transparent and (apart from possibly added solid diluents) free from solids, precipitation is.

The Number of partial solution streams must in the process of the invention at least two. However, it can be three, four, five, or six, seven, eight or nine, or ten. The number is advantageous the partial solution flows at inventive method not more than five.

Which Sources of the elemental constituents of the multimetal oxide material M a suitable, in a partial solution to be solved Part of the total for the preparation of the multimetal oxide M needed Starting connections must be decided on a case-by-case basis and can be determined by the skilled person by means of fewer preliminary experiments.

Contains the multimetal oxide material M the element Nb, it is for the inventive method often appropriate, this Element in its own partial solution to solve. On the other hand, it usually does not cause any difficulties, the elements Mo, V and Te next to each other in a single partial solution to solve.

The required according to the invention together the at least two partial solution streams may be e.g. carried out so that it consists of at least two, containing at least two partial solutions Storage vessels by means a corresponding number of pumps, the standing partial solutions first in spatial separated continuously flowing Partial solution flows, in separate lines (in the simplest case hoses or Pipes) become.

In the simplest case, the at least two partial solution flows are then guided onto the two inputs of a so-called T-piece (preferably the feeders are tapered in the access piece of the T-piece). Inside the T-piece, the two partial solution streams meet and together flow as a total solution stream into the tee's Tee, via which the total solution stream is led away from the tee

To the coincidence of the two partial solution flows takes place in their continuation as Total solution flow their substantially homogeneous mixing, e.g. mainly by bringing them together generated turbulence can be caused.

in the outlet piece but can e.g. additionally a static one (for example SMXS of Sulzer Chemtech, D-61239 Ober-Mörlen-Ziegenberg) and / or a dynamic mixer that integrates the total solution flow flows through and leaves as a substantially homogeneous mixture solution stream. in principle static or dynamic mixers are spaces that contain standing or moving obstacles that are so on the flow the mixture solution stream act, that are generated in the same turbulence, the Mixing to a mixture solution stream effect (under the term "static Mixers "are such to understand the fixed mixing devices such. flow pins contain, where the materials to be mixed flow past and to mix with one another by turbulence and other disturbances; under the term "dynamic Mixers "are such to understand the active mixing devices, e.g. in the form of rotating Mixing blades, contain; with them, the materials to be mixed through active transport mixed together).

In Practice has proven itself the mixing in the mixing zone by the action of ultrasound in addition to support or exclusively to effect. For this, e.g. a rod-shaped ultrasonic probe in the Mixed zone introduced become.

Of course you can the number of inputs the "T-piece" in the aforementioned exemplary embodiment the method according to the invention amount to more than two, without the basic principle of the procedure to change something.

The mixture solution stream produced as described can then be led directly and by the shortest route into the spray head of a spray drier (eg a Minor Hi-Tec Niro atomizer from Niro, Copenhagen, DK) and divided into finely divided droplets which are heated by contact with hot spray Gas (eg air or nitrogen or mixtures of air and nitrogen or noble gases or carbon oxides). In the case of the abovementioned spray drier, in the process according to the invention, the inlet temperature of the hot gas may be, for example, 200 to 400.degree. C., preferably 310 to 330.degree. The outlet temperature of the drying gas according to the invention should be 100 to 200 ° C., preferably 105 to 115 ° C. In the spray dryer, the atomized mixture solution and the hot drying gas can be passed in cocurrent or countercurrent. The droplet size resulting from sputtering is usually 5 to 1000 μm, often 10 to 100 μm. The drying time of such droplets is less than one second in conventional spray driers. In principle, the spray-drying in the process according to the invention can also be carried out as described in EP-A 603836.

The atomization the total solution can in the inventive method both by means of nozzles (e.g. by means of centrifugal force nozzles), by gas pressure sprayer or by means of spray discs or spray baskets (partially also "rotating Nozzles "). spray discs and spray baskets are preferred according to the invention. you need though compared to other nozzles a larger technical Effort at higher Energy demand. They are for it but less sensitive possibly forming solid particles. The overall solution is included They are usually depressurized to the pulp or basket center, distributed and spray as a hollow cone from the smooth edge of the disc or from the perforated rim of the basket from.

The Partial solution streams can during inventive method but also directly a dynamic mixer, as the DE-A No. 10043489 describes micromixers according to DE-A 10041823 or mixing nozzles according to DE-A Supplied 19958355 and mixed in these according to the invention become. As such mixing nozzles can for the inventive method both smooth jet nozzles, Levodüsen, Bosch nozzles or jet dispersants. According to the invention preferred is the use of mixing nozzles, the both the merge the partial solution flows and their Mixing as well as the fragmentation of the resulting mixture stream accomplish. The atomized total solution can then be like in a spray dryer by means of hot Gas in DC or in counter-current dried who the. The advantage the procedure according to the invention builds up the production of stable partial solutions, the continuous flow only located together and mixed, thereby directly and in a minimal amount of time a mixture solution stream produced, with a narrow residence time without loss of time spray dried can be.

In usually claims the inventive method from the date the beginning of the merge the at least two partial solution streams to one Total solution flow until complete separation (atomization) of the mixture solution stream usually less than two minutes, preferably less than one Minute, most preferably less than thirty seconds and application technology appropriately less than twenty or less than ten seconds. When using the micromixer according to DE-A 10041823 this time can be even under five seconds and in favorable make even at values ≤ 2 sec. or ≤ 1 sec. lie.

These periods are usually sufficient to ensure that solids are formed within the mixture solution in advance their perfect atomization omitted.

advance the thermal treatment of the process according to the invention during the drying of the atomized (divided) mixture solution stream this solid may optionally initially tabletted (optionally with the addition of 0.05 to 3 wt .-% of finely divided Graphite) and then thermally treated. After the thermal Treatment can be tableting by grinding or splitting be lifted again.

The thermal treatment can, as in DE-A 19835247, EP-A 529853, EP-A 603836, EP-A 608838, EP-A 895809, DE-A 19835247, EP-A 962253, EP-A 1080784, EP-A 1090684, EP-A 1123738, EP-A 1192987, EP-A 1192986, EP-A 1192982, EP-A 1192983 and EP-A 1192988 respectively.

The thermal treatment (calcination) at temperatures of 200 to 1200 ° C, or 300 to 650 ° C, or 400 to 600 ° C can be carried out in principle under both oxidizing, reducing and under inert atmosphere. As the oxidizing atmosphere, for example, air, air enriched with molecular oxygen, or air depleted of molecular oxygen may be considered. According to the invention, however, the thermal treatment is preferably carried out under an inert atmosphere, ie, for example, under molecular nitrogen and / or noble gas. Usually, the thermal treatment is carried out at atmospheric pressure (1 atm). Of course, the thermal treatment can also be carried out under vacuum or under pressure. Predominantly the temperature during the thermal treatment will not exceed 650 ° C. In particular, when the multimetal oxide However, if M contains the element Cs and / or other alkali or alkaline earth metals, higher temperatures may be advantageous.

He follows the thermal treatment under a gaseous atmosphere, can these both stand and flow. Overall, the thermal Treatment can take up to 24 hours or more. Higher temperatures correlate with shorter ones Treatment periods and vice versa.

Prefers the thermal treatment is initially under oxidizing (oxygen containing) atmosphere (e.g., under air) at a temperature of 100 to 400 ° C and 200, respectively up to 300 ° C (= Pre-decomposition step). Following this, the thermal Treatment appropriate under Inert gas at temperatures of 300 to 650 ° C, or 400 to 600 ° C or 450 up to 600 ° C continued.

The available as described Multimetal oxide M can as such (i.e., as a powder or as a grit) or shaped into shaped articles as catalytic active compounds for the partial gas phase oxidations described at the beginning of this document and / or ammoxidations of saturated and unsaturated Hydrocarbons or lower aldehydes are used. there For example, the catalyst bed may be a fixed bed, a moving bed or a fluidized bed be. The shaping can e.g. by extruding or tableting in the case of solid catalysts or by application to a carrier body (preparation of shell catalysts), as described in DE-A 10118814 or PCT / EP / 02/04073 or DE-A 10051419 is described.

The in the case of coated catalysts for the multimetal oxide compositions of the invention M are to be used carrier body preferably chemically inert. That is, they access the course of the partial catalytic gas phase oxidation or oxidation of the Hydrocarbon (e.g., propane and / or propene to acrylic acid) or Aldehydes which are protected by the novel multimetal oxide materials M is essentially not catalysed.

When Material for the carrier bodies come particularly according to the invention Alumina, silica, silicates such as clay, kaolin, steatite (preferably steatite of the company CeramTec (DE) of the type C-220, or preferably with low water-soluble alkali content), pumice, Aluminum silicate and magnesium silicate, silicon carbide, zirconium dioxide and thorium dioxide.

The surface of the carrier body can be both smooth and rough. Advantageously, the surface of the Carrier body rough, because an increased surface roughness usually an elevated one Adhesive strength of the applied active mass shell conditioned.

Often, the surface roughness R _{z of} the carrier body in the range of 5 to 200 micronsμm, often in the range of 20 to 100 microns (determined according to DIN 4768 sheet 1 with a "Hommel Tester for DIN-ISO Oberflächenmeßgrößen" Fa. Hommelwerke, DE).

Further can the carrier material porous or nonporous be. Conveniently, the carrier material is non-porous (total volume the pores based on the volume of the carrier body ≤ 1 vol .-%).

The Thickness of the shell catalysts of the invention located active oxide mass shell is usually from 10 to 1000 microns. she can but also 50 to 700 μm, 100 to 600 μm or 150 to 400 μm be. Possible Shell thicknesses are also 10 to 500 μm, 100 to 500 μm or 150 up to 300 μm.

in principle come for the inventive method any geometries of the carrier body in Consideration. Your longest stretch is usually 1 to 10 mm. Preferably, however, spheres or cylinders, in particular hollow cylinder, used as a carrier body. Cheap diameter for carrier balls amount 1.5 to 4 mm. If cylinders are used as carrier bodies, then theirs is Length preferably 2 to 10 mm and its outer diameter preferably 4 to 10 mm. In addition, in the case of rings, the wall thickness is usually at 1 to 4 mm. According to the invention suitable annular Carrier body can also a length from 3 to 6 mm, an outside diameter from 4 to 8 mm and a wall thickness of 1 to 2 mm. Is possible but also a carrier ring geometry of 7 mm × 3 mm × 4 mm or 5 mm × 3 mm × 2 mm (Outer diameter × length × inner diameter).

The preparation of the shell catalysts can be carried out in the simplest way so that the present invention Multimetalloxidmassen M vorformet, transferred them into a finely divided form and finally applying with the aid of a liquid binder on the surface of the carrier body. For this purpose, the surface of the carrier body is moistened in the simplest manner with the liquid binder and brought into contact with finely divided active multimetal oxide composition M, a layer of the active composition attached to the moistened surface. Finally, the coated carrier body is dried. Of course you can repeat the process periodically to achieve an increased layer thickness. In this case, the coated base body becomes the new "carrier body" etc ..

The fineness of the catalytically active multimetal oxide composition M of general formula (I) to be applied to the surface of the carrier body is, of course, adapted to the desired shell thickness. For the shell thickness range of 100 to 500 microns z. B. such active mass powder, of which at least 50% of the total number of powder particles pass through a sieve of mesh size 1 to 20 microns and their numerical proportion of particles with a longitudinal extension above 50 microns less than 10%. As a rule, the distribution of the longitudinal extents of the powder particles corresponds to the production of a Gaussian distribution. Often the particle size distribution is as follows:

Here are:
D = diameter of the particle,
x = the percentage of particles whose diameter is ≥ D; and
y = the percentage of particles whose diameter is <D.

For an implementation of the described coating method on an industrial scale recommends z. B. the application of the in DE-A 2909671, as well as in the DE-A 10051419 disclosed method principle. That is, those to be coated Become a carrier body in a preferably inclined (the inclination angle is in the Rule ≥ 0 ° and ≤ 90 °, usually ≥ 30 ° and ≤ 90 °; the angle of inclination is the angle of the rotary container central axis against the horizontal) rotating rotary container (eg turntable or Drumming drum) submitted. The rotating rotary container leads the z. B. spherical or cylindrical carrier body under two at a certain distance successively arranged metering devices therethrough. The first of the two metering devices expediently corresponds to one Nozzle (e.g. a compressed air operated atomizer nozzle) through which the rotating Turntable rolling carrier body with the liquid Binder sprayed and be moistened in a controlled manner. The second metering device is located outside of the atomizing cone of the sprayed liquid Binder and serves to the finely divided oxidic active material feed (e.g., via a vibrating conveyor or a powder screw). The controlled moistened carrier balls take the fed Active powder on, moving through the rolling motion the outer surface of the z. B. cylindrical or spherical Carrier body too a coherent one Compacted shell.

at Needs go through the so-primed carrier body in Course of the next turn turn the spray nozzles, will In doing so, moisturizes controlled to continue in the process of moving on take up a further layer of finely divided oxidic active material to be able to etc. (intermediate drying is usually not required). Finely divided oxidic active material and liquid binder are thereby usually fed continuously and simultaneously.

The removal of the liquid binder may, after completion of the coating z. B. by the action of hot gases, such as N ₂ or air done. It is noteworthy that the coating process described produces both a fully satisfactory adhesion of the successive layers to one another and the base layer on the surface of the support body.

Essential for the above-described coating method is that the moistening of be coating surface of the carrier body is made in a controlled manner. In short, this means that it is advisable to moisten the carrier surface in such a way that, although it has adsorbed liquid binder, no liquid phase as such visually appears on the carrier surface. If the carrier body surface is too moist, the finely divided catalytically active oxide mass will agglomerate into separate agglomerates instead of growing on the surface. Detailed information can be found in DE-A 2909671 and in DE-A 10051419.

The aforementioned final Removal of the used liquid Binder can in a controlled manner z. B. by evaporation and / or sublimation. In the simplest case, this can be hotter by exposure Gases of appropriate temperature (often 50 to 300, often 150 ° C) take place. By Exposure hotter Gases can also be effected only a pre-drying. The final drying can then, for example, in a drying oven of any kind (eg. B. belt dryer) or in the reactor. The acting temperature should not be above that for the preparation of the oxide active composition applied calcination temperature lie conditions. Of course, can the drying also exclusively carried out in a drying oven become.

When Binder for the coating process can be independent of the type and geometry of the carrier body used are: water, monohydric alcohols such as ethanol, methanol, propanol and butanol, polyhydric alcohols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol or glycerol, mono- or polyvalent organic carboxylic acids such as propionic acid, oxalic acid, malonic, glutaric or maleic acid, Amino alcohols such as ethanolamine or diethanolamine and on or polyfunctional organic amides such as formamide. Cheap binders are also Solutions, consisting of 20 to 90 wt .-% water and 10 to 80 wt .-% of a dissolved in water organic compound, its boiling point or sublimation temperature at atmospheric pressure (1 atm)> 100 ° C, preferably> 150 ° C, is. With Advantage is the organic compound from the above listing potential selected organic binder. Preferably the organic fraction of the aforementioned aqueous binder solutions 10 to 50 and more preferably 20 to 30 wt .-%. As organic Components are also monosaccharides and oligosaccharides such as glucose, fructose, sucrose or lactose and polyethylene oxides and polyacrylates.

When Geometries (for both Full catalysts as well as for Shell catalysts) come here both balls, solid cylinders and Hollow cylinder (rings) into consideration. The longest extent of the aforementioned Geometries is usually 1 to 10 mm. In the case of cylinders is their Length preferably 2 to 10 mm and its outer diameter preferably 4 to 10 mm. In the case of rings, moreover, the wall density is usually at 1 to 4 mm. Suitable annular Full catalysts can also a length from 3 to 6 mm, an outside diameter from 4 to 8 mm and a wall thickness of 1 to 2 mm. Is possible but also a Vollkatalysatorringgeometrie of 7 mm × 3 mm × 4 mm or of 5 mm × 3 mm × 2 mm (outer diameter × length × inner diameter). Of course, come for the geometry of the multimetal oxide active masses M also all those of DE-A 10101695 into consideration.

The specific surface of multimetal oxide compositions M according to the invention (and the multimetal oxide compositions M ', M ") discussed in the further course of this application is often 1 to 40 m ² / g, often 11 or 12 to 40 m ² / g and often 15 or 20 to 40 or 30 m ² / g (determined by the BET method, nitrogen).

According to the invention preferred is the stoichiometric Coefficient a of the invention available Multimetal oxide M, independent from the preferred areas for the other stoichiometric Coefficients of the multimetal oxide M, 0.05 to 0.6, especially preferably 0.1 to 0.6 or to 0.5.

Independent of the preferred areas for the other stoichiometric Coefficients of the multimetal oxide materials M is the stoichiometric coefficient b preferably> 0 or 0.01 to 1, and more preferably 0.01 or 0.1 to 0.5 or to 0.4.

Of the stoichiometric Coefficient c of the invention available Multimetal oxide mass M is, independently from the preferred areas for the other stoichiometric Coefficients of the multimetal oxide M advantageously 0.01 to 1 and particularly preferably 0.01 or 0.1 to 0.5 or 0.4. One most preferred range for the stoichiometric coefficient c, the, independent from the preferred areas for the other stoichiometric Coefficients of the invention available Multimetal oxide M, with all other preferred ranges in this Font is combinable, the range is 0.05 to 0.2.

The stoichiometric coefficient d of the multimetal oxide compositions M obtainable according to the invention is preferably independent of the preferred ranges for the other stoichiometric coefficients Multimetal oxide compositions M, 0.00005 or 0.0005 to 0.5, particularly preferably 0.001 to 0.5, often 0.002 to 0.3 and often 0.005 or 0.01 to 0.1.

Independent of the preferred areas for the other stoichiometric Coefficients of the multimetal oxide M, may be the coefficient e also ≥ 0 to 0.5.

Particularly advantageous are multimetal oxide compositions M obtainable according to the invention, the stoichiometric coefficients a, b, c and d of which lie simultaneously in the following raster:
a = 0.05 to 0.6;
b = 0.01 to 1 (or 0.01 to 0.5);
c = 0.01 to 1 (or 0.01 to 0.5);
d = 0.0005 to 0.5 (or 0.001 to 0.3); and
e = ≥0 to 0.5.

Very particularly favorable are multimetal oxide compositions M obtainable according to the invention, the stoichiometric coefficients a, b, c and d of which lie simultaneously in the following raster:
a = 0.1 to 0.6;
b = 0.1 to 0.5;
c = 0.1 to 0.5;
d = 0.001 to 0.5, or 0.002 to 0.3, and 0.005 to 0.1, respectively; and
e = ≥0 to 0.2.
M ¹ is preferably Te.

All the above is especially true when M ² at least 50 mol% of its total amount Nb and / or Ta and most preferably when M ² to at least 75 mol% of its total amount, or to 100 mol% of its total amount Nb is.

But above all, irrespective of the meaning of M ² , it is also true that M ³ comprises at least one element from the group comprising Fe, Ni, Co, Pd, Ag, Au, Pb and Ga or at least one element from the group Ni, Co, Fe and Pd is.

Above all, however, all of the above applies even if M ^{2 contains} at least 50 mol% of its total amount, or at least 75 mol%, or 100 mol% of Nb and M ^3, at least one element selected from the group consisting of Ni, Co, Fe, Pd, Ag, Au, Pb and Ga.

Above all, however, all the above applies even if M ^{2 is} at least 50 mol%, or at least 75 mol%, or 100 mol% of its total amount of Nb and M ^{3 is} at least one element selected from the group consisting of Ni, Co, Fe and Pd is.

With very particular preference all statements regarding the stoichiometric coefficients apply when M ¹ = Te, M ² = Nb and M ³ = at least one element from the group comprising Ni, Co, Fe and Pd.

Cheap multimetal oxide materials M are those (in particular all of the abovementioned) with e = 0. If e> 0, M ^{4 is} preferably Cs. Preferably, M ^{2 is} then Bi.

Further according to the invention suitable stoichiometries are those in this specification that are suitable for the multimetal oxide materials stoichiometry (I) are disclosed in the cited prior art.

• – der Beugungsreflex h innerhalb des Röntgendiffraktogramms der intensitätsstärkste ist, sowie eine Halbwertsbreite von höchstens 0,5° aufweist,
• – die Intensität P_i des Beugungsreflexes i und die Intensität P_k des Beugungsreflexes k die Beziehung 0,65 ≤ R ≤ 0,85 erfüllen, in der R das durch die Formel R = Pi/(Pi + Pk)definierte Intensitätsverhältnis ist, und
• – die Halbwertbreite des Beugungsreflexes i und des Beugungsreflexes k jeweils ≤ 1° beträgt.

Also preferred according to the invention are multimetal oxide compositions M whose X-ray diffractograms have diffraction reflectances h, i and k whose vertices at the diffraction angles (2θ) are 22 ± 0.5 ° (h), 27.3 ± 0.5 ° (i) and 28.2 ± 0.5 ° (k), where

• The diffraction reflex h within the X-ray diffractogram is the highest intensity, and has a half width of at most 0.5 °,
• The intensity P _{i of} the diffraction reflex i and the intensity P _{k of} the diffraction reflection k satisfy the relationship 0.65 ≤ R ≤ 0.85, in which R is represented by the formula R = P i / (P i + P k ) defined intensity ratio is, and
• - The half-width of the diffraction reflection i and the diffraction reflection k is ≤ 1 °.

All in this document on an X-ray diffractogram referenced relate to a using Cu-Kα radiation as X-radiation generated X-ray diffractogram (Siemens Theta-Theta D-5000 diffractometer, tube voltage: 40 kV, tube current: 40 mA, aperture diaphragm V20 (variable), diffuser diaphragm V20 (variable), Sekundärmonochromatorblende (0.1 mm), detector aperture (0.6 mm), measuring interval (2θ): 0.02 °, measuring time each Step: 2.4 s, detector: scintillation counter tube; the definition of intensity a diffraction reflex in the X-ray diffractogram refers in this document to those in DE-A 19835247, DE-A 10122027, as well as those laid down in DE-A 10051419 and DE-A 10046672 Definition; The same applies the definition of the half-width.

According to the invention preferred is 0.67 ≤ R ≤ 0.75 and very particularly preferably R = 0.69 to 0.75 or R = 0.71 to 0.74, or R = 0.72.

In addition to the diffraction reflections h, i and k, the X-ray diffraction pattern of multimetal oxide compositions M preferred according to the invention generally contains further diffraction reflections whose vertices lie at the following diffraction angles (2θ): 9.0 ± 0.4 ° (l), 6.7 ± 0.4 ° (o) and 7.9 ± 0.4 ° (p).

Cheap is it further, if the X-ray diffractogram additionally contains a diffraction reflex, whose vertex is at the diffraction angle (2θ) = 45.2 ± 0.4 ° (q).

Often contains the X-ray diffractogram from cheap Multimetal oxide M even the reflexes 29.2 ± 0.4 ° (m) and 35.4 ± 0.4 ° (n) (vertex positions).

Assigning the intensity 100 to the diffraction reflex h, it is favorable according to the invention if the diffraction reflexes i, l, m, n, o, p, q have the following intensities in the same intensity scale:
i: 5 to 95, often 5 to 80, partly 10 to 60;
1: 1 to 30;
m: 1 to 40;
o: 1 to 30;
p: 1 to 30 and
q: 5 to 60.

Contains the X-ray arctogram the inventively available Multimetal oxide mass M of the aforementioned additional diffraction reflexes, is the half width of the same usually ≤ 1 °. Particularly advantageous available according to the invention Multimetal oxide M, whose X-ray diffractogram additionally to the aforementioned features (individually or together) no diffraction reflex with the vertex position 2θ = 50.0 ± 0.3 °.

The Definition of intensity a diffraction reflex in the X-ray diffractogram refers in this document to the in DE-A 19835247, as well as the definition given in DE-A 10051419 and DE-A 10046672.

That's enough available according to the invention Multimetal oxide materials M are not directly the aforementioned advantageous Requirement profile, so lets this usually generate by the inventively available Multimetal oxide compositions M, e.g. described in DE-A 10254279, with suitable liquids washes. As such liquids come for example organic acids or their aqueous solutions (e.g. oxalic acid, formic acid, Acetic acid, citric acid and tartaric acid) and inorganic acids and their watery solutions (e.g., nitric acid or telluric acid) but also alcohols or hydrogen peroxide and their aqueous solutions in Consideration. Of course can for washing also mixtures of the aforementioned washing liquids be used. Furthermore, JP-A 7-232071 also discloses a suitable washing process.

During washing, multimetal oxide materials M ', whose stoichiometry usually also remains corresponds to general formula (I) and which can be used in the same way as catalytic active compositions as the multimetal oxide M mass. As a rule, the multimetal oxide M 'an advantageous X-ray diffractogram as described.

However, inexpensive multimetal oxide materials (which can be used as multimetal oxide compositions M or multimetal oxide compositions M ') are also multimetal oxide compositions M "which are obtainable from multimetal oxide compositions M obtainable according to the invention or multimetal oxide compositions M' obtainable therefrom whose stoichiometric coefficient d = 0 or <0.5 , for example, by soaking them with solutions (eg aqueous) of elements M ³ (eg by spraying), subsequently drying (possibly at temperatures ≤ 100 ° C) and then thermally treated as the precursors of the multimetal O M (preferably in Inert gas stream; pre-decomposition in air is preferably dispensed with). The stoichiometry of the resulting compositions M "is advantageously chosen in accordance with the general formula I for the multimetal oxide compositions M. The use of aqueous carbonate, bicarbonate, nitrate and / or halide solutions of elements M ³ and / or the use of aqueous solutions in which the elements M ^{3 are} complexed with organic compounds (for example acetates or acetylacetonates) is particularly advantageous for this preparation variant advantageous. The doping of multimetal oxide materials M or M 'with d = 0 or <0.5, but can also be carried out as described in EP-A 1266688 (vapor deposition).

Needless to say, can the inventively available Multimetal oxide materials M also in finely divided, e.g. colloidal essentially only diluting acting materials, such as silica, titania, alumina, Zirconia and niobium oxide more dilute Form can be used as catalytic active compounds.

The Dilution mass ratio can while up to 9 (thinner) : 1 (active mass). That is, possible dilution mass ratio e.g. 6 (thinner) : 1 (active mass) and 3 (thinner) : 1 (active mass). The incorporation of the diluents can be before and / or after Calcination, usually even before drying done. You can even be incorporated into at least a partial solution.

He follows the incorporation before drying or before the calcination, must the thinner to be chosen that in the fluid medium or in the calcination substantially preserved. This is e.g. in the case of at correspondingly high Temperatures of calcined oxides are usually given.

at an incorporation of the diluting Materials (e.g., in the form of their sols) in at least a partial solution the term solution in this document, on the total system minus the added thinning effect Materials, as this usually a finely divided insoluble inert solid is.

The available according to the invention Multimetal oxide M and the masses M 'and M' 'are suitable as such or in a dilute form as just described as active masses for heterogeneously catalyzed partial gas phase oxidations (including oxydehydrogenations) and / or ammoxidations of saturated and / or unsaturated Hydrocarbons and aldehydes.

Such saturated and / or unsaturated Hydrocarbons are in particular ethane, ethylene, propane, propylene, n-butane, iso-butane and iso-butene. Target products are above all Acrolein, acrylic acid, methacrolein, methacrylic acid, Acrylonitrile and methacrylonitrile. They are also suitable for the heterogeneous catalyzed partial gas phase oxidation and / or oxidation of compounds such as acrolein and methacrolein.

But Ethylene, propylene and acetic acid may also be the target product.

A complete oxidation of the hydrocarbon is understood in this document to mean that the total carbon contained in the hydrocarbon is converted into oxides of carbon (CO, CO ₂ ).

All of which various reactions of the hydrocarbon under reactive Influence of molecular oxygen are in this document with subsumed under the term partial oxidation. The additional reactive The action of ammonia characterizes the partial ammoxidation.

The multimetal oxide compositions M, M 'and M "obtainable according to this document are preferably suitable as catalytic active compounds for the conversion of propane into acrolein and / or acrylic acid, from propane to acrylic acid and / or acrylonitrile, from propylene to acrolein and / or acrylic acid, from propylene to acrylonitrile, from isobutane to methacrolein and / or methacrylic acid, from isobutane to methacrylic acid and / or methacrylnit ril, from ethane to ethylene, from ethane to acetic acid and from ethylene to acetic acid.

The execution such partial oxidations and / or ammoxidations (by in in a known manner to be controlled choice of the content of ammonia in the reaction gas mixture, the reaction can be used essentially exclusively as partial oxidation, or only as partial ammoxidation, or as an overlay both reactions are designed; see. e.g. WO 98/22421) is of the multimetal oxide materials of the general stoichiometry I of the prior Technique known per se and can be carried out in completely corresponding manner.

Becomes used as hydrocarbon crude propane or crude propylene this is preferred as in DE-A 10246119 or DE-A 10118814 or PCT / EP / 02/04073. Likewise, it is preferred proceed as described there.

A with multimetal oxide M (or M 'or M '') - active composition catalysts to be performed partial oxidation of propane to acrylic acid may e.g. as in EP-A No. 608838, WO 0029106, JP-A 10-36311 and EP-A 1192987 carried out become.

When Source for the needed molecular oxygen can e.g. Air, oxygenated or oxygen depleted air or pure oxygen become.

Such a method is also advantageous if the starting reaction gas mixture contains no noble gas, in particular no helium, as an inert diluent gas. Incidentally, in addition to propane and molecular oxygen, the reaction gas starting mixture may of course comprise inert diluent gases such as N ₂ , CO and CO ₂ . Water vapor as reaction gas mixture component is advantageous according to the invention.

That is, the starting reaction gas mixture with which the present invention multimetal oxide active material M, M 'or M''at reaction temperatures of eg 200 to 550 ° C or 230 to 480 ° C and 300 to 440 ° C and pressures of 1 to 10 bar, or 2 to 5 bar, for example, may have the following composition:
From 1 to 15, preferably from 1 to 7,% by volume of propane,
44 to 99 vol .-% air and
0 to 55% by volume of water vapor.

Prefers are water vapor-containing reaction gas starting mixtures.

Other possible compositions of the reaction gas starting mixture are:
70 to 95% by volume of propane,
5 to 30% by volume of molecular oxygen and
0 to 25% by volume of water vapor.

Of course, in such a process, a product gas mixture is obtained which does not consist exclusively of acrylic acid. Rather, the product gas mixture in addition to unreacted propane contains secondary components such as propene, acrolein, CO ₂ , CO, N ₂ O, acetic acid, propionic acid, etc., of which the acrylic acid must be separated.

This can be done as it is by the heterogeneously catalyzed gas phase oxidation from propene to acrylic acid is known.

that is, from the product gas mixture, the acrylic acid contained by Absorption with water or by absorption with a high-boiling inert hydrophobic organic solvents (e.g., a mixture from diphenyl ether and diphyl which may also contain additives such as Dimethyl phthalate may be included). The resulting Mixture of absorbent and acrylic acid can subsequently in a manner known per se, rectificative, extractive and / or crystallisative to pure acrylic acid be worked up. Alternatively, the basic separation of the acrylic acid the product gas mixture also be carried out by fractional condensation, as it is e.g. is described in DE-A 19 924 532.

The resulting aqueous Acrylic acid condensate can then be e.g. by fractional crystallization (e.g., suspension crystallization and / or layer crystallization).

The in the basic separation of the acrylic acid remaining residual gas mixture contains in particular unreacted propane, which is preferably in the Gas phase oxidation is recycled. It can for this purpose from the residual gas mixture, e.g. by fractional pressure rectification partially or fully separated and then in the gas phase oxidation be returned. better However, it is the residual gas in an extraction device with a hydrophobic organic solvent to be brought into contact with (e.g., passing through) the Propane prefers to absorb.

By subsequent desorption and / or stripping with air can absorb the absorbed Propan released again and in the process of the invention be returned. In this way, total economic propane conversion rates can be achieved. Propene formed as a minor component is thereby, as well as in other separation processes, usually not from propane or not Completely separated and led with this in a circle. This also applies in the case saturated by other homologous and olefinic hydrocarbons. Above all, it is generally true for heterogeneous according to the invention catalyzed partial oxidations and / or ammoxidations of saturated Hydrocarbons.

there makes it advantageous that the inventively available Multimetal oxide materials M, M 'and M '' also the partial Oxidation and / or oxidation of the homologous olefinic hydrocarbon to catalyze the same target product heterogeneously.

So can with the inventively available Multimetal oxide materials M, M 'or M '' as active compounds acrylic acid by heterogeneously catalyzed partial gas phase oxidation of propene with molecular oxygen as in DE-A 10118814 or PCT / EP / 02/04073 or JP-A 7-53448.

that is, a single reaction zone A is for the implementation of the Procedure sufficient. In this reaction zone are as catalytically active compositions exclusively available according to the invention Multimetal oxide composition M, M 'and / or M '' - catalysts.

This is unusual extends the heterogeneously catalyzed gas-phase oxidation of propene to acrylic acid generally in two successive steps. The first step is usually propene essentially oxidized to acrolein and in the second step is usually Acrolein formed in the first step is oxidized to acrylic acid.

conventional Process of heterogeneously catalyzed gas phase oxidation of propene to acrylic acid therefore usually for each the two aforementioned oxidation steps a special, on tailoring the oxidation step, Type of catalyst.

that is, the conventional methods of heterogeneously catalyzed gas phase oxidation from propene to acrylic acid work in contrast to the method according to the invention with two reaction zones.

Needless to say, may be in the process of Propenpartialoxidation in one Reaction zone A only one or more than one obtainable according to the invention Multimetal oxide composition M, M 'and / or M '' - catalyst are located. Naturally can the catalysts to be used are diluted with inert material, as in this document, for example, as a carrier material was recommended.

Along the a reaction zone A can in the process of Propenpartialoxidation only one or even one along the reaction zone A changing Temperature of a heat carrier for Temperature control of the reaction zone A prevail. This temperature change can be increasing or decreasing.

Becomes the inventive method Propenpartialoxidation carried out as a fixed bed oxidation takes place the implementation in an appropriate manner in a tube bundle reactor, whose catalyst tubes are charged with the catalyst. To the contact tubes is normally used as a heat transfer medium Liquid, usually a salt bath.

Several Temperature zones along the reaction zone A can then be realized in a simple manner that along the Contact tubes in sections more than a salt bath around the contact tubes to be led.

The reaction gas mixture is considered in the catalyst tubes over the reactor either in cocurrent or in countercurrent to the salt bath. The salt bath itself can perform a pure parallel flow relative to the contact tubes. Of course, this can also be superimposed on a cross flow be. Overall, the salt bath around the catalyst tubes can also perform a meandering flow which, viewed only over the reactor, is conducted in cocurrent or countercurrent to the reaction gas mixture.

The Reaction temperature may be in the process of propene partial oxidation along the entire reaction zone A 200 ° to 500 ° C. Usually it will be 250 to 450 ° C be. Preferably, the reaction temperature is 330 to 420 ° C, especially preferably 350 to 400 ° C be.

Of the Working pressure can be during the process of propene partial oxidation both 1 bar, less than 1 bar or more than 1 bar. Typical according to the invention working pressures are 1.5 to 10 bar, often 1.5 to 5 bar.

At that for be the process of Propenpartialoxidation to be used propene no particularly high standards in terms of its purity.

b) Chemical grade Propylen:

As propene can for such a method, as already said and as for all one or two-stage process of heterogeneously catalyzed gas phase oxidation of propene to acrolein and / or acrylic acid in general, for example, propene (also called crude propene) of the following two specifications completely easily be used: a) polymer grade propylene:

b) Chemical grade propylene:

Of course, everyone can aforementioned possible But companion of Propens but also in the two to tenfold the said individual amount contained in the crude propene, without the usability of the raw propene for the process or for the known Process of one- or two-stage heterogeneously catalyzed gas phase oxidation from propene to acrolein and / or acrylic acid in general.

This especially if it is like the saturated ones Hydrocarbons, the water vapor, the carbon oxides or the anyway, are molecular compounds, either as inert diluent gases or increased as a reactant in Participate in the above processes in the reaction process. Normally, the crude propene as such with recycle gas, air and / or molecular oxygen and / or dilute air and / or inert gas mixed for the process of heterogeneously catalyzed gas phase oxidation of Propene used to acrolein and / or acrylic acid.

When Propene Source comes for the inventive method but also propene, which is part of a process according to the invention different process is formed as a by-product and e.g. up to 40% of its weight contains propane. This Propen can be additionally still others, the inventive method substantially not disturbing, Accompanying components are accompanied.

When Oxygen source can for the process of propene partial oxidation both pure oxygen as well as air or oxygen enriched or depleted Air to be used.

In addition to molecular oxygen and propene, a reaction gas starting mixture to be used for the process of propene partial oxidation usually also contains at least one diluent gas. As such, nitrogen, carbon oxides, noble gases and lower hydrocarbons such as methane, ethane and propane come into consideration (higher, eg C ₄ hydrocarbons should be avoided). Frequently, steam is also used as diluent gas. In many cases, mixtures of the aforementioned gases form the diluent gas for the partial propene oxidation process.

Advantageous the heterogeneously catalyzed partial oxidation of the propene takes place in the presence of propane.

Typically, the reaction gas starting mixture for the propene oxidation process is follows composed (molar ratios):
Propene: oxygen: H ₂ O: other diluent gases
= 1: (0,1 - 10): (0 - 70): (0: 20).

Preferably is the aforementioned ratio 1: (1 - 5) : (1 - 40) : (0 - 10).

Becomes Propane as a diluent gas used, this may, as described, advantageous in part also to acrylic acid be oxidized.

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

The molar ratio of Propane: Propene may occur during the propene oxidation process Take values: 0 to 15, often 0 to 10, often 0 to 5, suitably 0.01 to 3.

The Loading the catalyst charge with propene can be during the process the partial propene oxidation e.g. 40 to 250 Nl / l · h. The load with reaction gas starting mixture is often in Range from 500 to 15,000 Nl / l · h, often in the range 600 to 10,000 Nl / l · h, often 700 to 5000 Nl / l · h.

Of course, in the process of propene partial oxidation to acrylic acid, a product gas mixture is obtained which does not consist exclusively of acrylic acid. Rather, the product gas mixture in addition to unconverted propene secondary components such as propane, acrolein, CO ₂ , CO, H ₂ O, acetic acid, propionic acid, etc., of which the acrylic acid must be separated.

This can be done as it is from the heterogeneously catalyzed two-stage (carried out in two reaction zones) Gas phase oxidation of propene to acrylic acid is well known.

that is, from the product gas mixture, the acrylic acid contained by Absorption with water or by absorption with a high-boiling inert hydrophobic organic solvents (e.g., a mixture from diphenyl ether and diphyl which may also contain additives such as Dimethyl phthalate may be included). The resulting Mixture of absorbent and acrylic acid can subsequently in a manner known per se, rectificative, extractive and / or crystallisative to pure acrylic acid be worked up. Alternatively, the basic separation of the acrylic acid the product gas mixture also be carried out by fractional condensation, as it is e.g. is described in DE-A 19 924 532.

The resulting aqueous Acrylic acid condensate can then be e.g. by fractional crystallization (e.g., suspension crystallization and / or layer crystallization).

The in the basic separation of the acrylic acid remaining residual gas mixture contains in particular unconverted propene (and optionally propane). This can be made from the residual gas mixture, e.g. by fractional pressure rectification separated and then be recycled to the gas phase oxidation according to the invention. better However, it is the residual gas in an extraction device with a hydrophobic organic solvent to be brought into contact with (e.g., passing through) the Propene (and optionally propane) is preferred to absorb.

By subsequent desorption and / or stripping with air can absorb the absorbed Propene (and possibly propane) released again and in the inventive method be returned. In this way, economic Gesamtpropenumsätze be achieved. When propene is partially oxidized in the presence of propane, propene becomes and propane preferably separated and recycled together.

In completely in a corresponding manner, the inventively available Multimetal oxides M, M 'and / or M '' as catalysts for the Use partial oxidation of isobutane and / or isobutene to methacrylic acid.

Your Use for the ammoxidation of propane and / or propene can e.g. like in the EP-A 529853, DE-A 2351151, JP-A 6-166668 and JP-A 7-232071 described described.

Your Use for the ammoxidation of n-butane and / or n-butene can as in JP-A 6-211767 described.

Your Use for the oxydehydrogenation of ethane to ethylene, or the further reaction to acetic acid, can be as described in US-A 4250346 or as described in EP-B 261264 respectively.

Your Use for the partial oxidation of acrolein to acrylic acid can be as described in DE-A 10261186 respectively.

The available according to the invention Multimetal oxide materials M, M 'and / or M '' but you can also be incorporated into other multimetal oxide compositions (e.g. mix finely divided masses, optionally compress and calcine, or as muds (preferably aqueous) mix, dry and calcine (e.g., as described in EP-A 529853 for multimetal oxide compositions the general stoichiometry I with d = 0 describes)). Preference is again calcined under inert gas.

The thereby resulting Multimetalloxidmassen (hereinafter total masses called) contain preferably ≥ 50 Wt .-%, more preferably ≥ 75 Wt .-%, and most preferably ≥ 90 wt .-% or ≥ 95 wt .-% to inventively available Multimetal oxide materials M, M 'and / or M '' and are for in this Script discussed partial oxidations and / or ammoxidations also suitable.

Prefers Also, the total masses at 2θ = 50.0 ± 3.0 ° do not contain a diffraction-reflex vertex position.

Contains the total mass at 2θ = 50.0 ± 3.0 ° a diffraction reflex vertex position, is it cheap if the proportion by weight of the multimetal oxide compositions obtainable according to the invention M, M 'and / or M' '≥ 80% by weight, or ≥ 90 Wt .-%, or ≥ 95 Wt .-% is. Such total masses are e.g. obtainable by the fact that in the production process according to the invention for the Multimetal oxide M 'not is washed out quantitatively.

The Geometric shaping takes place in the total masses in an appropriate manner as for the inventively available Multimetal oxide materials M, M 'and / or M '' described.

The Advantageousness of the multimetal oxide materials obtainable according to the invention M, M 'and / or M "is comparatively homogeneous Structure justified, the usually improved activity and / or selectivity in their Use as active masses for the mentioned in this document partial oxidations or -ammoxidationen conditionally.

To the Purpose of heterogeneously catalyzed partial gas phase oxidation from propane to acrylic acid are the inventively available Multimetal oxide materials M, M 'and / or M '' and containing them Multimetal oxide materials or catalysts are preferred as in DE-A 10122027 described put into operation.

Examples and Comparative Examples

A) Preparation of a coated catalyst S1, which is a obtained according to the invention Multimetal oxide mass M contributes

To prepare a partial solution A, initially 4000 ml of water were heated to 80 ° C. in a glass vessel. In it, while maintaining the 80 ° C and with stirring 706.2 g of ammonium heptamolybdate from. HC Starck, Goslar (DE) with a MoO ₃ content of 81.53 wt .-% (= 4 moles Mo) was dissolved. 141.0 g of ammonium metavanadate from HC Starck, Goslar (DE) having a V ₂ O ₅ content of 77.4% by weight (= 1.2 mol of V) were likewise introduced into the resulting clear solution at 80 ° C. stirred and dissolved. 211.28 g of Te (OH) ₆ from Fluka Chemie GmbH, Buchs (CH) with a Te (OH) ₆ content of ≥ 99% (= 0.92.) Were likewise introduced into the resulting clear solution at 80 ° C. mol Te) were stirred in and dissolved. The resulting reddish solution was cooled to 25 ° C and added with stirring at 25 ° C with water to a clear, transparent partial solution A with a total volume of 4500 ml.

to Production of a partial solution B were heated in 1000 ml of water heated to a temperature of 80 ° C 221.28 g of niobium ammonium oxalate from H.C. Starck, Goslar (DE) with an Nb content of 20.1 wt .-% (0.48 mol Nb) dissolved. The The resulting clear, transparent solution was cooled to 25 ° C and with water, which also had a temperature of 25 ° C, on a clear, transparent partial solution B with a total volume of 1500 ml.

Subsequently were the two stable aqueous solutions A and B by means of two laboratory metering pumps of the type ProMinent, type gamma g / 4a, over two separate plastic hoses continuously in the two input pieces of a Y-shaped so-called Tee pumped from plastic. The three tubular sections of the T-piece (2 input pieces and 1 leaving piece) each had an inner diameter of 5 mm and a length of 38 mm up. The solution A was used as a volume flow of 1500 ml / h and the solution B as promoted a volume flow of 500 ml / h. Inside the tee were the two solution streams A and B to a total solution flow of 2000 ml / h combined, the in the exit piece of the tee flowed. In this was a SMXS static mixer of the company Sulzer Chemtech, Obermörlen-Ziegenberg (DE). The diameter of the static mixer was 4.8 mm, the Length of Mixer bar was 35 mm. The end of the exit piece of the Tee was directly with the atomizer head a spray dryer (Niro Atomizer, type Minor Hi-Tec from Niro, Copenhagen (DK)) connected to the supplied Mixture solution stream atomized (Droplet size about 30 microns). Within the atomizer head, the in the center of the attached to the ceiling of the drying tower hot air distributor was attached, the mixture solution flow flowed through a 15 cm long connecting cable with an internal diameter of 6 mm directly to a rotating with 30,000 revolutions per minute atomizing disk (so-called channel plate). The resulting spray was from a hot air stream (DC, inlet temperature 320 ° C, outlet temperature 105 ° C) dried. Within 3 h, the total of 6000 ml of total solution flow spray dried become.

From the total solution flow of 2000 ml / h, the inner diameter of the T-outlet piece and the length of the static mixing section of 35 mm, a time t ¹ of about 1.2 seconds can be calculated, within the merged partial solution flows A and B in an im essential homogeneous mixture solution stream are transferred. If one additionally considers the transport of the mixture solution flow from the outlet of the static mixer through the 15 cm long connection line in the atomizer head with an inner diameter of 6 mm to the atomization location, the result is a time t of combining the solution streams A and B until the atomization of their mixture solution flow ² of less than nine seconds. Taking a drying time of less than one second, the time period t ³ from the combination to the dry powder is less than ten seconds. According to the weighing stoichiometry of solution A and solution B and the selected partial solution flows (3: 1), the resulting spray powder contained the elements Mo, V, Nb and Te in the molar stoichiometric ratio of Mo ₁ V _0.3 Nb _0.12 Te _0.23 (The tee tailpiece was not directly connected to the atomizer head of the spray dryer, but instead a 15 cm long, 6 mm internal diameter plastic tubing was connected to the end of the T-tail, through which the mixture solution stream into a lower one Collecting vessel, provided a visual check that both the mixture solution flow on the total length of the plastic tube and on arrival in the receiver contained no precipitate and was fully clear and transparent, a filtration test of the mixture solution flowing out of the plastic tube confirms the freedom of solids) ,

150 g of the resulting spray powder were in a rotary ball furnace according to 1 DE-A 10118814 under air (10 Nl / h) at a heating rate of 5 ° C / min from room temperature (25 ° C) to 275 ° C heated. Immediately thereafter was heated under nitrogen molecular stream (10 Nl / h) at a heating rate of 2 ° C / min from 275 ° C to 650 ° C and maintained this temperature while maintaining the nitrogen stream for 6 h. Subsequently, while maintaining the flow of nitrogen, it was left to self-cool to 25 ° C. A black calcined multimetal oxide M was obtained.

The calcined material was ground (granular size ≤ 0.12 mm) in a Retsch mill (centrifugal mill, type ZM 100, Retsch, DE) 75 g of the resulting powder were applied to 162 g of spherical support bodies with a diameter of 2.2 to 3.2 mm (R _z = 45 μm, support material = steatite C 220 from Ceramtec (DE), total pore volume of the support ≦ 1% by volume, based on the total volume of support) The drum was rotated at 25 rpm and a total of 30 ml of a mixture was uniformly distributed over a spray nozzle operated with 300 Nl / h of compressed air over a period of 60 minutes from glycerol and water (weight ratio glycerol: water = 1: 3) sprayed on the presented carrier balls.The nozzle was installed in such a way that the spray cone in the drum du rch entrainment plates to the top of the inclined drum carried carrier body in the upper half of the rolling track wetted. The active material powder was introduced into the drum via a powder screw, with the point of powder addition being within the rolling distance or below the spray cone. As a result of the periodic repetition of wetting and powder addition, the base-coated carrier body itself became the carrier body in the subsequent period.

To Completion of the coating were the coated carrier body during 16 h at 120 ° C in a circulating air drying cabinet (Binder (DE), interior volume 53 I) dried. The glycerine was followed by a two-hour heat treatment at 150 ° C removed under air.

It a shell catalyst S1 was obtained which has an active mass fraction of 32% by weight.

B) Preparation of a shell catalyst S2, which is a product obtained according to the invention Multimetal oxide mass M contributes

It was carried out as in A), but the partial solution stream A became too 3000 ml / h (instead of 1500 ml / h) and the partial solution stream B became 1000 ml / h (instead of 500 ml / h). About that In addition, the inlet temperature in the spray-drying became 400 ° C instead of 320 ° C selected.

t ^{1 is} calculated to be about 0.6 seconds, t ² to 4.5 seconds and t ³ to 5.5 seconds. Within 1.5 hours, the 6,000 ml of total solution stream was spray dried. The stoichiometry of the spray dry powder was also Mo ₁ V _0.3 Nb _0.12 Te _0.23 . The resulting shell catalyst was the shell catalyst S2.

C) Preparation of a shell catalyst S3, one of a multimetal oxide composition obtained according to the invention M available Multimetal oxide material M 'contributes

100 g of a multimetal oxide composition obtained as in A) after completion of calcination M was placed in 500 g of a 20% by weight aqueous nitric acid.

The resulting aqueous Suspension was refluxed at 70 ° C for 7 h stirred. Then it was heated to 25 ° C cooled. The solid in the black suspension was passed through Filtration of the aqueous Phase separated, washed with water free of nitrate and then in a convection oven dried at 120 ° C overnight. Subsequently was the dried material analogous to the procedure A) in one Retsch mill ground (particle size ≤ 0.12 mm) and the resulting powder as described in A) to a coated catalyst S3 further processed.

D) Preparation of a shell catalyst S4, one of a multimetal oxide composition obtained according to the invention M available Multimetal oxide material M 'contributes

100 g of a multimetal oxide composition obtained as in B) after completion of calcination M were treated as described in C) with aqueous nitric acid and the remaining solid as described in C) to a Shell catalyst S4 further processed.

E) Preparation of a shell catalyst VS5, which is a multimetal oxide composition not according to the invention wearing

As in A), 4500 ml of partial solution A and 1500 ml partial solution B, each having a temperature of 25 ° C. Then, the 1500 ml of the partial solution B within about 3 Seconds into the partial solution A stirred. This gave 6000 ml of a reddish 25 ° C having clear, transparent mixture solution C. Immediately afterwards was the continuously stirred mixture solution C while maintaining the temperature of 25 ° C by means of a laboratory metering pump of type ProMinent, type gamma g / 4a, via a plastic hose with a volume flow of 2000 ml / h continuously into the atomizer head of the in A) applied spray drier guided and as described in A) atomized by the same and in the hot air stream dried (inlet temperature 320 ° C, outlet temperature 105 ° C).

While mixture solution C was still clear and transparent in the first two minutes, pronounced turbidity was evident after only 2.5 minutes. After 5 minutes, a significant amount of a reddish solid had precipitated and after 1 hour was a completely opaque reddish aqueous suspensions. That is, while still a homogeneous spray powder was obtained from a clear, transparent solution at the beginning of spray drying, fell in the further course of spray drying an inhomogeneous spray powder containing an increasing proportion of the precipitated reddish solid whose composition of the weight of the in the mixture solution C initially deviated significantly (while the weighing stoichiometry was Mo ₁ V _0.3 Nb _0.12 Te _0.23 , the elemental composition of solids separated off by filtration after 1 h is Mo ₁ V _0.3 Nb _0.6 Te _0.4 the X-ray diffractogram of the reddish solid exhibited three very broad peaks in the 2θ range of 5 to 65 °, with the peak having the maximum amplitude being about 28 °).

The after complete spray spray powder obtained was mixed evenly and as in A) thermally treated (calcined) and to a shell catalyst VS5 further processed.

F) Preparation of a shell catalyst VS6, one of a multimetal oxide composition not obtained according to the invention carries received Multimetalloxidmasse

The in E) obtained in the calcination multimetal was as in C) described with aqueous nitric acid treated and the remaining solid as described in C) further processed to a shell catalyst VS6.

G) Testing the coated catalysts S1 to VS6

With the respective shell catalyst was in each case a reaction tube made of V2A steel (length: 140 cm, outside diameter: 60 mm, inner diameter: 8.5 cm). The loading length was chosen to 52 cm (centered in the reaction tube housed). A forfeit of 30 cm bulk length out Steatite (C220 from Ceram-Tec, Diameter: 2.2 to 3.2 mm) was used to warm the reaction gas starting mixture. With the same steatite balls, the reaction tube became after the catalyst zone finally filled. The Reaction tube was from the outside on its entire length heated by electric heating mats. The mat temperature was to 340 ° C selected. The reaction was carried out at a pressure of 2 bar absolute, a residence time (based on the catalyst bed) of 2.4 s with a feed (reaction gas starting mixture) of the molar Composition Propane: Air: Water = 1: 15: 14 performed. in the Product gas stream was selected by gas chromatographic analysis the selectivity S (mol .-%) the formation of acrylic acid determined with a simple reaction tube passage. Dependent on The shell catalyst used were used in the following Table listed results obtained.

there the propane conversion was U (mol.%) and the selectivity of acrylic acid formation when using the coated catalyst S1 arbitrarily set equal to 100.

Table:

H) reworking according to the invention the "Preparation of Complex Metal Oxide (1) " JP-A 11-306228

29.21 liters of water were heated to 80 ° C. Then, while maintaining the 80 ° C., 7.09 kg of ammonium paramolybdate tetrahydrate ((= ammonium heptamolybdate) from the company HC Starck, Goslar (DE) having a MoO ₃ content of 81.53% by weight) were successively added thereto, 1.41 kg Ammonium metavanadate (from HC Starck, Goslar (DE) with a V ₂ O ₅ content of 77.4% by weight) and 2.12 kg telluric acid (from Fluka Chemie GmbH, Buchs (CH) with a Te (OH ) _6- content of ≥ 99%). Finally, 5 kg of silica sol with an SiO ₂ content of 20% by weight (produced from 2.5 kg of Ludox AS-40 colloidal silica 40 wt.% Suspension in water, DuPont product, Aldrich Chem. Comp Inc., Milwaukee, USA, and 2.5 kg of water), cooled to 50 ° C to obtain a partial solution A.

2.16 kg of ammonium niobium oxalate (H.C. Starck, Goslar (DE) with an Nb content of 20.1% by weight) were dissolved in 8.66 liters of water heated to 80 ° C. Then became the solution to 50 ° C chilled and so a partial solution B received.

The 50 ° C partial solutions A and B were combined as described in A), mixed and spray dried (Partial solution stream A: 1570 ml / h, partial solution flow B: 430 ml / h).

A review like in A) revealed that the mixture solution stream until finally to his spraying contained no precipitate (the sol used was also clear and transparent).

Claims (21)

Process for the preparation of a multimetal oxide composition M of general stoichiometry I Mo ₁ V _a M ¹ _b M ² _c M ³ _d M ⁴ _e O _n (I) with M ¹ = at least one of the elements from the group comprising Te and Sb; M ² = at least one of the group consisting of Nb, Ti, W, Ta, Bi, Zr and Re; M ³ = at least one of the group consisting of Pb, Ni, Co, Fe, Pd, Ag, Pt, Cu, Au, Ga, Zn, Sn, In, Ce, Ir, Sm, Sc, Y, Pr, Nd and Tb; M ⁴ = at least one of the elements selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, Ba; a = 0.01 to 1, b = ≥ 0 to 1, c => 0 to 1, d = ≥ 0 to 0.5, e = ≥ 0 to 1 and n = a number determined by the valence and frequency of the non-oxygen elements in (I) is determined, in which continuously from the required for the preparation of the M Multimetalloxidmasse M starting materials contained in the M Multimetalloxidmasse elemental constituents in a solvent produces a mixture solution, the mixture solution continuously feeds a drying device for the removal of the solvent and the resulting solid is thermally treated at elevated temperature, wherein the thermal treatment comprises a calcination at 200 to 1200 ° C, characterized in that from the starting materials required for the preparation of the multimetal oxide M starting compounds of the multimetal oxide M elemental constituents initially at least two spatially separate, respectively subsets of the required starting compounds g producing at least two partial solution streams which combine at least two partial solution streams into a total solution stream, the total solution stream passing through a mixing zone in which a mixture solution stream containing the total amount of starting compounds required is formed, the mixture solution stream either already in the mixing zone is divided into finely divided droplets or the Gemischlösungsstrom leads out of the mixing zone and then divided into finely divided droplets, drying the finely divided Gemischlösung droplets by contact with hot gas and thermally treated the resulting solid at elevated temperature, the thermal treatment calcination at 200 to 1200 ° C includes. Method according to claim 1, characterized in that that the solids content of the mixture solution stream, indicated as Total content of metals contained, 1 to 30 wt .-% is. Method according to claim 1, characterized in that that the solids content of the mixture solution stream, indicated as Total content of metals contained, 5 to 20 wt .-% is. Method according to one of claims 1 to 3, characterized that as a solvent an aqueous one solvent is used. Method according to one of claims 1 to 4, characterized the temperature of the at least two partial solution streams is 15 to 40 ° C. Method according to one of claims 1 to 4, characterized the temperature of the at least two partial solution streams is 20 to 30 ° C. Method according to one of claims 1 to 6, characterized that the number of partial solutions 2 to 5. Method according to one of claims 1 to 7, characterized that the procedure from the time of commencement of merging the at least two partial solution streams to one Total solution flow less than two until complete separation of the mixture solution stream Minutes claimed. Method according to one of claims 1 to 7, characterized that the procedure from the time of commencement of merging the at least two partial solution streams to one Total solution flow until complete separation of the mixture solution stream less than thirty seconds claimed. Method according to one of claims 1 to 7, characterized that the procedure from the time of commencement of merging the at least two partial solution streams to one Total solution flow until complete decomposition of the mixture solution flow is less than twenty Seconds claimed. Method according to one of claims 1 to 10, characterized that a = 0.05 to 0.6. Method according to one of claims 1 to 11, characterized that b = 0.01 to 1. Method according to one of claims 1 to 12, characterized that c = 0.01 to 1. Method according to one of claims 1 to 13, characterized that d = 0.0005 to 0.5. Method according to one of claims 1 to 14, characterized that a = 0.1 to 0.6; b = 0.1 to 0.5; c = 0.1 to 0.5; d = 0.001 to 0.5 and e = ≥0 to 0.5. Method according to one of claims 1 to 15, characterized in that M ^{2 is} at least 50 mol% of its total amount of Nb and / or Ta. Method according to one of claims 1 to 16, characterized in that M ^{3 is} at least one element selected from the group consisting of Ni, Co, Fe and Pd. Method according to one of claims 1 to 17, characterized in that M ¹ = Te, M ² = Nb and M ^{3 is} at least one element selected from the group consisting of Ni, Fe, Co and Pd. Method according to one of claims 1 to 18, characterized that at least a partial solution at least one finely divided, diluting material from the group comprising silica, titania, alumina, Contains zirconium oxide and niobium oxide added. Process of heterogeneously catalyzed partial Gas-phase oxidation and / or -ammoxidation of saturated and / or unsaturated Hydrocarbons, characterized in that as an active composition a multimetal oxide composition M, obtained by a process according to the claims 1 to 19, is used. Multimetal oxide materials M, obtainable by a process according to claim 1 to 19.