Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/23—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups
  • C07C51/235—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups of —CHO groups or primary alcohol groups
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/30—Loose or shaped packing elements, e.g. Raschig rings or Berl saddles, for pouring into the apparatus for mass or heat transfer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/24—Chromium, molybdenum or tungsten
  • B01J23/28—Molybdenum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/24—Chromium, molybdenum or tungsten
  • B01J23/31—Chromium, molybdenum or tungsten combined with bismuth
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
  • B01J23/887—Molybdenum containing in addition other metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/8876—Arsenic, antimony or bismuth
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
  • B01J23/887—Molybdenum containing in addition other metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/8877—Vanadium, tantalum, niobium or polonium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
  • B01J35/55—Cylinders or rings
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
  • C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
  • C07C45/34—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds
  • C07C45/35—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds in propene or isobutene
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/25—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of unsaturated compounds containing no six-membered aromatic ring
  • C07C51/252—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of unsaturated compounds containing no six-membered aromatic ring of propene, butenes, acrolein or methacrolein
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/30—Details relating to random packing elements
  • B01J2219/302—Basic shape of the elements
  • B01J2219/30223—Cylinder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/30—Details relating to random packing elements
  • B01J2219/302—Basic shape of the elements
  • B01J2219/30242—Star
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/30—Details relating to random packing elements
  • B01J2219/304—Composition or microstructure of the elements
  • B01J2219/30475—Composition or microstructure of the elements comprising catalytically active material

Definitions

• the invention relates to a process of heterogeneously catalyzed
• (Meth) acrylic acid to (meth) acrolein and / or (meth) acrylic acid by passing a reaction gas starting mixture of the precursor compound, molecular oxygen and, if appropriate, a gas which is inert with respect to the catalytic gas phase partial oxidation at elevated temperature through a fixed catalyst bed, which contains as a catalyst a mixed oxide active material shaped into a geometric body, this geometric body being a geometric base body, in the surface of which at least one cavity is incorporated.
• (meth) acrylic acid is used as an abbreviation for methacrylic acid or acrylic acid.
• Method acrolein is used in this document as an abbreviation for methacrolein or acrolein.
• (Meth) acrylic acid is particularly useful for the preparation of polymers for a wide variety of applications, e.g. Use as an adhesive, important.
• precursor compounds of (meth) acrylic acid are generally understood to mean organic compounds from which (meth) acrylic acid can be obtained by heterogeneously catalyzed gas phase partial oxidation. These are usually alkanes, alkanols, alkenes or alkenals which contain 3 or 4 carbon atoms.
• (Meth) acrylic acid is particularly advantageously obtainable, for example, by heterogeneously catalyzed gas phase partial oxidation of propane, propene, tert-butanol, isobutene, isobutane, isobutyraldehyde or (meth) acrolein.
• precursors are also conceivable from which the actual C / C 4 precursor compound only forms as an intermediate during the heterogeneously catalyzed gas phase partial oxidation.
• the methyl ether of tert-butanol may be mentioned as an example.
• the precursor compounds described above are diluted as starting gases, generally with inert gases such as molecular nitrogen, CO, CO 2 , inert hydrocarbons and / or water vapor, in a mixture with molecular oxygen at elevated temperatures (usually approx. 200 to 450 ° C) as well as optionally increased pressure via transition metal (e.g. Mo, Cu and P, or Mo, Bi and Fe or Mo, V and W or Mo, V, Te and Nb containing (where P is not mentioned is, it is usually not included)) Mixed oxide active materials and oxidative either directly into the
• (Meth) acrylic acid or, in a first step, converted into its precursor compound (meth) acrolein see, for example, DE-A 4 405 059, EP-A 253 409, EP-A 92097, DE-A 4 431 957, DE-A 4 431 949, CN-A 1 105 352, WO 97/36849, EP-A 608 838, EP-A 714 700, EP-A 700 893, EP-A 700 714, DE-A 19 815 279, DE-A 10 046 672 and DE-A 10 034 825.
• precursor compound (meth) acrolein see, for example, DE-A 4 405 059, EP-A 253 409, EP-A 92097, DE-A 4 431 957, DE-A 4 431 949, CN-A 1 105 352, WO 97/36849, EP-A 608 838, EP-A 714 700, EP-A 700 893, EP-A 700 7
• the mixed oxide active materials are poured into a fixed bed through which the reaction gas starting mixture containing the precursor compound is passed at the elevated temperature.
• the desired partial oxidation occurs during contact with the mixed oxide active material.
• the shaped catalyst bodies can also be diluted with inert shaped bodies.
• the shape of the mixed oxide active composition can e.g. by compacting powdered mixed oxide active material to the desired catalyst geometry (e.g. by tableting, extruding or extruding).
• the resulting catalysts are referred to as full catalysts.
• auxiliaries such as e.g. Graphite or stearic acid can also be used as lubricants and / or molding aids and reinforcing agents such as microfibers made of glass, asbestos, silicon carbide or potassium titanate.
• the shape can also be e.g. by applying powdered mixed oxide active material to preformed inert or active catalyst supports of suitable geometry. Shell catalysts are obtained in this way.
• the shaping methods described can also be used on the basis of precursor compositions of the mixed oxide active compositions.
• the conversion into the active catalysts is usually carried out subsequently by thermal treatment at elevated temperature.
• the shaped catalyst bodies can be heaped up either individually or in a mixture with inert shaped bodies (for example the inert support bodies which can be used for the production of coated catalysts) to form fixed catalyst beds.
• These fixed catalyst beds can be located, for example, in the tubes of tube bundle reactors (cf. e.g. EP-A 700 893 and EP-A 700 714) or on the trays of tray reactions.
• balls and cylinders are recommended as typical geometries for the unsupported catalytic converter, shell-type catalytic converter and supported catalytic converter shaped bodies.
• EP-A 417 723 and EP-A 355 664 also recommend the use of geometric catalyst bodies which correspond to a geometric base body in whose surface at least one cavity is incorporated.
• Possible geometric basic bodies are e.g. Cylinders, cubes or prisms are considered.
• a disadvantage of the aforementioned, in the prior art for the process of heterogeneously catalyzed gas phase partial oxidation of precursor compounds of (meth) acrylic acid to (meth) acrolein and / or (meth) acrylic acid, different from spheres and cylinders, is the geometric catalyst body that in in all cases either the ratio of the volume of the geometric catalyst body (V R ) to the volume of the geometric base body (V G ), ie V K : V G ,> 0.6 and / or the ratio of the outer surface of the geometric catalyst body (O ⁇ ) to V ⁇ , ie O ⁇ : V ⁇ , ⁇ 22 cm “ 1 .
• This is disadvantageous insofar as the selectivity of the product of value formation achieved with such geometric catalyst bodies is not fully satisfactory.
• the object of the present invention was therefore to provide a process for heterogeneously catalyzed gas phase partial oxidation of a precursor compound of (meth) acrylic acid to (meth) acrolein and / or (meth) acrylic acid, by combining a reaction gas starting mixture from the precursor compound, molecular oxygen and, if appropriate leads a gas which is inert with respect to the catalytic gas phase partial oxidation at elevated temperature through a fixed catalyst bed which contains as a catalyst a mixed oxide active composition shaped into a geometrical body, this geometrical body being a geometrical basic body, in the surface of which at least one cavity is incorporated provide, which ensures an improved selectivity of the formation of valuable products.
• 0 K to V can thus be> 23 cm -1 , or> 24 c -1 , or 25 cm “ 1 , or> 26 cm -1 or> 27 cm" 1 .
• the ratio according to the invention will be 0 K to V ⁇ ⁇ 30 cm _1 .
• V K : V G can be ⁇ 0.62, or ⁇ 0.61, or ⁇ 0.60, or ⁇ 0.58, or ⁇ 0.56, or ⁇ 0.54, or 0.52, or ⁇ 0.50, or ⁇ . 0.48, or ⁇ 0.45.
• V K : V G in the method according to the invention will be> 0.30, frequently> 0.35 or> 0.40. According to the invention, it is advantageous if O ⁇ to V is as large as possible and V K : V G is as small as possible.
• V R , V G and O R are those volumes and surfaces that the eye can perceive visually when viewing the geometric body. This means that internal volumes and surfaces that result from finely divided pores and / or cracks in the material of the geometric body are not included in V, V G and O ⁇ .
• At least 25% (by number), more preferably at least 50%, preferably at least 75% and particularly preferably 100% of the total of the mixed oxide active composition contained in the fixed catalyst bed are shaped into geometric bodies for which the aforementioned conditions have been met, ie for the V K : V G ⁇ 0.63 and for the O ⁇ to V ⁇ > 22 cm " 1.
• the fixed catalyst bed used for the process according to the invention additionally contains inert shaped bodies for the purpose of dilution, it is preferred according to the invention if it is also at least 25% (of the number), better at least 50%, preferably at least 75% and particularly preferably 100% of all the inert moldings contained are geometric bodies for which the above-mentioned conditions are fulfilled, ie for the V R. VQ ⁇ 0.63 and for which O ⁇ to V ⁇ > 22 cm " 1 applies.
• EP-A 552 287 can be considered as the geometric base body for the method according to the invention. These are in particular the cylinder, the pyramid, the cone, the cube, the cuboid, the prism, the ball, the truncated cone and the truncated pyramid.
• FIG. 1A, B cylinder as a geometric base body; Cavities are worked into the surface of the base body as rounded, essentially perpendicular grooves running from top to bottom; Fig. 1, B shows the view from above.
• FIGS. 1A, B This figure shows a variation of the geometry shown in FIGS. 1A, B. 3A, B: This figure shows a variation of the geometry shown in FIGS. 1A, B, which additionally contains a central bore.
• 4A, B cylinder as a geometric base body; Cavity incorporated as a central hole. 4B shows the top view.
• FIGS. 1A, B This figure shows a variation of the geometry shown in FIGS. 1A, B. Angled grooves.
• 6A, B cylinder as a geometric base body; Cavity as central bore and continuously wound spiral worked into the surface of the base body. 6B shows the view from above.
• 7A, B cylinder as a geometric base body; Cavity as a rounded, essentially vertical groove from top to bottom, which is connected to the central bore. 7B shows the
• Cavities are worked in as rounded grooves with the same distance on the outer surface at the edges of the pyramid. 8B shows the top view.
• Cavities are worked into the sides of the pyramid as rounded grooves with equal spacing on the outer surface, running obliquely from top to bottom. 9B shows the top view.
• 10A, B cone with a circular base as the base body. Cavities are worked in as rounded grooves with the same distance on the outer surface of the cone, running obliquely from top to bottom. 10B shows the top view.
• 11A, B cubes as the base body; Cavities are incorporated as angled grooves with the same spacing on the outer surface of the base body on the sides, running essentially vertically from top to bottom. 11B shows the top view.
• 12A, B cubes as the base body; Cavities are incorporated as angled grooves on the outer surface in opposite sides running essentially vertically from top to bottom. 12B shows the top view.
• 13A, B cubes as the base body; Cavities are worked in as rounded troughs with equal spacing on the outer surface of the base body on the sides, the upper surface and the lower surface. 13B shows the top view.
• 14A, B ball as base body; Cavities are worked in as rounded troughs with the same distance on the outer surface. 14B shows the cross section at the equator.
• Mixed oxide active materials shaped into rings are advantageously used as catalysts for the process according to the invention. If they are used diluted with inert shaped bodies, the inert shaped bodies also advantageously have a ring geometry.
• the geometry of the inert molded body and the geometric catalyst body is preferably identical.
• the end faces of the rings can also be curved, as described in EP-A 184 790, for example so that the radius of the curvature is preferably 0.4 to 5 times the outer diameter.
• EP-A 552 287 for which 0 K : V K > 22 and V K : V G ⁇ 0.6, are also considered.
• the empty volume of the fixed catalyst bed used that is the sum of the volume portions of the fixed catalyst bed bed which are not taken up by solid when the bed is viewed visually
• the total volume of the fixed catalyst bed used this is the sum of the volume portions of the fixed catalyst bed, which are taken up either visually from solid or from gas
• the empty volume of the fixed catalyst bed used can thus be> 52 vol.%, Or> 55 vol.%, Or> 57 vol.%, Or> 60 vol.%, Or> 62 vol.%, Or> 65 Vol .-%, or 10> 67 vol .-%.
• the empty volume of the fixed catalyst bed used in the process according to the invention will not be more than 70% by volume.
• the ratio of the inner tube diameter to the longest dimension of the cross section of a bore is ⁇ 7.5, preferably ⁇ 7, 20 with advantage ⁇ 6.5, often ⁇ 6 and often ⁇ 5.5. As a rule, this ratio is> 4, mostly> 4.5 and often> 5.
• 30 is 50 mol%, preferably at least 75 mol% and particularly preferably at least 85 mol%.
• the process according to the invention is particularly suitable for the following heterogeneously catalyzed gas phase partial oxidations 35 of precursor compounds of (meth) acrylic acid (each to be carried out in one oxidation stage):
• the mixed oxide active compositions required as catalysts for these heterogeneously catalyzed gas-phase oxidations and the methods for shaping them into geometric bodies suitable according to the invention can be known in the art, e.g. can be taken from that cited in this document.
• a large number of the mixed oxide active compositions suitable for the heterogeneously catalyzed gas phase partial oxidation of propene to acrolein can be obtained using the general formula I.
• X 1 nickel and / or cobalt
• ⁇ 2 thallium
• X 3 zinc, phosphorus, arsenic, boron, antimony, tin, cerium, lead and / or tungsten,
• X 4 silicon, aluminum, titanium and / or zirconium
• n a number which is determined by the valency and frequency of the elements in I other than oxygen,
• suitable mixed oxide active materials I can be prepared in a simple manner by producing an intimate, preferably finely divided, dry mixture of suitable elemental constituents according to their stoichiometry and calcining it at temperatures of 350 to 650 ° C.
• the calcination can be carried out both under inert gas and under an oxidative atmosphere such as air ( mix of inert gas and oxygen) and also under a reducing atmosphere (for example a mixture of inert gas, NH 3 , CO and / or H 2 ).
• the calcination time can range from a few minutes to a few hours and usually decreases with temperature.
• Suitable sources for the elementary constituents of the mixed oxide active materials I are those compounds which are already oxides and / or those compounds which can be converted into oxides by heating, at least in the presence of oxygen.
• such starting compounds are, above all, halides, nitrates, formates, oxalates, citrates, acetates, carbonates, amine complexes, ammonium salts and / or hydroxides (compounds such as NH 4 OH, (NH 4 ) 2 CO 3 , NH 4 N0 3 , NH 4 CH0, CH 3 COOH, NH 4 CH 3 C0 2 and / or ammonium oxalate, which can decompose and / or decompose to form completely gaseous compounds at the latest during later calcination, can also be incorporated into the intimate dry mixture) ,
• the intimate mixing of the starting compounds for the preparation of mixed oxide active compositions I can take place in dry or in wet form. If it is carried out in dry form, the starting compounds are expediently used as finely divided powders and, after mixing and, if appropriate, compacting, subjected to calcination. However, the intimate mixing is preferably carried out in wet form. Usually, the starting compounds are mixed together in the form of an aqueous solution and / or suspension. Particularly intimate dry mixtures are obtained in the mixing process described if only sources of the elementary constituents present in dissolved form are used. Water is preferably used as the solvent. The aqueous composition obtained is then dried, the drying process preferably being carried out by spray drying the aqueous mixture at exit temperatures of 100 to 150 ° C.
• the mixed oxide active compositions of the general formula I can be used for the process according to the invention, for example in the form of a ring-shaped catalyst geometry, it being possible for the shaping to take place before or after the final calcination.
• ring-shaped unsupported catalysts can be produced from the powder form of the active composition or its uncalcined and / or partially calcined precursor composition by compression to the desired catalyst geometry (for example by extrusion), with auxiliaries such as, for example, graphite or stearic acid as lubricants and / or molding aids and reinforcing agents means like Microfibers made of glass, asbestos, silicon carbide or potassium titanate can be added.
• the powdery mixed oxide active composition or its powdery, not yet and / or partially calcined, precursor composition can also be shaped by application to inert catalyst supports preformed in the form of a ring.
• the coating of the ring-shaped carrier bodies for the production of the coated catalysts is generally carried out in a suitable rotatable container, such as is e.g. is known from DE-A 2909671, EP-A 293859 or from EP-A 714700.
• the powder mass or carrier body to be applied is expediently moistened and, after application, e.g. using hot air, dried again.
• the layer thickness of the powder mass applied to the annular carrier body is expediently selected in the range from 10 to 1000 ⁇ m, preferably in the range from 50 to 500 ⁇ m and particularly preferably in the range from 150 to 250 ⁇ m.
• porous or non-porous aluminum oxides silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide or silicates such as magnesium or aluminum silicate can be used as carrier materials.
• Carrier bodies with a clearly formed surface roughness are preferred.
• the use of essentially non-porous, rough-surface, ring-shaped supports made of steatite is suitable.
• the fineness of the catalytically active oxide compositions to be applied to the surface of the support body is of course adapted to the desired shell thickness (cf. EP-A 714 700).
• the annular support body can also be soaked with a solution and / or suspension containing the starting compounds of the elemental constituents of the relevant mixed oxide active composition, dried and finally, as described, calcined to obtain supported catalysts.
• compositions to be used according to the invention for a partial oxidation of propene to acrolein according to the invention are also compositions of the general formula II
• Y 1 bismuth, tellurium, antimony, tin and / or copper
• Y 2 molybdenum and / or tungsten
• Y 3 an alkali metal, thallium and / or samarium
• Y 4 an alkaline earth metal, nickel, cobalt, copper, manganese,
• Y 7 a rare earth metal, titanium, zirconium, niobium, tantalum,
• ⁇ 0.01 to 8
• Particularly advantageous mixed oxide active compositions II according to the invention are those in which Y 1 is bismuth.
• Z 2 molybdenum and / or tungsten
• Z 3 nickel and / or cobalt
• Z 4 thallium, an alkali metal and / or an alkaline earth metal
• Z 5 phosphorus, arsenic, boron, antimony, tin, cerium and / or lead,
• Z 6 silicon, aluminum, titanium and / or zirconium
• Z 7 copper, silver and / or gold
• Oxygen different element can be determined in III
• mixed oxide active materials I applies to mixed oxide active materials II.
• X 1 W, Nb, Ta, Cr and / or Ce
• X 2 Cu, Ni, Co, Fe, Mn and / or Zn,
• X 3 Sb and / or Bi
• X 4 one or more alkali metals
• X 5 one or more alkaline earth metals
• X 6 Si, Al, Ti and / or Zr
• a 1 to 6
• b 0.2 to 4
• e 0 to 2
• f 0 to 4
• g 0 to 40
• n a number that is determined by the valency and frequency of elements other than oxygen in IV is determined
• X 1 W, Nb, and / or Cr
• X 2 Cu, Ni, Co, and / or Fe
• X 4 Na and / or K
• X 5 Ca, Sr and / or Ba
• mixed oxide active compositions IV are those of the general formula V
• Y5 Ca and / or Sr
• ⁇ 6 Si and / or Al
• a ' 2 to 4
• b' 1 to 1.5
• c ' 1 to 3
• f 0 to 0.5 g '0 to 8 and n' a number which is determined by the valency and frequency of the elements in V other than oxygen.
• the mixed oxide active compositions (IV) which are suitable according to the invention are known per se, e.g. available in DE-A 4335973 or in EP-A 714700.
• mixed oxide active compositions of the general formula IV which are suitable according to the invention can be prepared in a simple manner by generating an intimate, preferably finely divided, dry mixture which is composed according to their stoichiometry, from suitable sources of their elemental constituents and calcined at temperatures of 350 to 600 ° C.
• the calcination can take place both under inert gas and under an oxidative atmosphere such as air (mixture of inert gas and oxygen) and under a reducing atmosphere (eg mixtures of inert gas and reducing gases such as H 2 , NH 3 , CO, methane and / or Acrolein or the reducing gases mentioned by themselves) are carried out.
• the calcination time can range from a few minutes to a few hours and usually decreases with temperature.
• Suitable sources for the elemental constituents of the mixed oxide active materials IV are those compounds which are already oxides and / or those compounds which can be converted into oxides by heating, at least in the presence of oxygen.
• the intimate mixing of the starting compounds for the production of mixed oxide active compositions IV can be carried out in dry or in wet form. If it is carried out in dry form, the starting compounds are expediently used as finely divided powders and after mixing and, if appropriate, compacting the
• the intimate mixing is preferably carried out in wet form.
• the starting compounds are mixed together in the form of an aqueous solution and / or suspension. Particularly intimate dry mixtures are obtained in the mixing process described if only sources of the elementary constituents present in dissolved form are used. Water is preferably used as the solvent. n- finally the aqueous mass obtained is dried, the Drying process is preferably carried out by spray drying the aqueous mixture with outlet temperatures of 100 to 150 ° C.
• the mixed oxide active materials IV suitable according to the invention can be used for the process according to the invention e.g. Shaped into annular catalyst geometries are used, the shaping can be carried out in a completely analogous manner to that of the mixed oxide active materials I before or after the final calcination.
• ring-shaped unsupported catalysts can be produced quite analogously from the powder form of the mixed oxide active composition or its uncalcined precursor composition by compression to the desired catalyst geometry (e.g. by extrusion), where appropriate auxiliaries such as e.g. Graphite or stearic acid can be added as a lubricant and / or molding aid and reinforcing agent such as microfibers made of glass, asbestos, silicon carbide or potassium titaniumate.
• the powdered active composition or its powdery, not yet calcined, precursor composition can also be shaped by application to inert catalyst supports preformed in the form of a ring.
• the coating of the support bodies for the production of the coated catalysts is usually carried out in a suitable rotatable container, as is e.g. is known from DE-A 2909671, EP-A 293859 or from EP-A 714700.
• the powder mass to be applied is expediently moistened and after application, e.g. using hot air, dried again.
• the layer thickness of the powder mass applied to the carrier body is expediently selected in the range from 10 to 1000 ⁇ m, preferably in the range from 50 to 500 ⁇ m and particularly preferably in the range from 150 to 250 ⁇ m.
• porous or non-porous aluminum oxides silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide or silicates such as magnesium or aluminum silicate can be used as carrier materials.
• the carrier bodies with a clearly formed surface roughness are preferred.
• the fineness of the catalytically active oxide compositions to be applied to the surface of the support body is of course adapted to the desired shell thickness (cf. EP-A 714 700).
• the mixed oxide active compositions IV can of course also be shaped into ring-shaped supported catalysts.
• Favorable mixed oxide active compositions to be used according to the invention for the gas phase partial oxidation of acrolein to acrylic acid are also compositions of the general formula VI,
• Z 1 W, Nb, Ta, Cr and / or Ce
• Z 2 Cu, Ni, Co, Fe, Mn and / or Zn
• Z 6 Si, Al, Ti and / or Zr
• Z 7 ' Mo, W, V, Nb and / or Ta
• starting mass 1 the preformed solid starting aces 1 in an aqueous solution, an aqueous suspension or in a finely divided dry mixture of sources of the elements Mo, V, Z 1 , Z 2 , Z 3 , Z 4 , Z 5 , Z 6 , which the aforementioned elements in the stoichiometry D
• Mixed oxide active materials VI are preferred in which the preformed solid starting material 1 is incorporated into an aqueous starting material 2 at a temperature of ⁇ 70.degree.
• a detailed description of the production of mixed oxide VI active materials contains e.g. EP-A 668104, DE-A 19736105 and DE-A 19528646.
• the shaping required for the process according to the invention can, as in all other cases, also in the case of the aforementioned mixed oxide active materials, by coating suitable carrier bodies or e.g. done by extrusion processes.
• the process according to the invention is preferably carried out in shell-and-tube reactors coated with the catalysts, such as those e.g. describe EP-A 700 714 and EP-A 700 893 and the literature cited in these documents.
• the contact tubes are usually made of ferritic steel and typically have a wall thickness of 1 to 3 mm. Their inside diameter is usually 20 to 30 mm, often 21 to 26 mm.
• the number of contact tubes accommodated in the tube bundle container is at least 5000, preferably at least 10,000.
• the number of contact tubes accommodated in the reaction vessel is frequently from 15,000 to 30,000.
• Tube bundle reactors with a number of contact tubes above 40,000 are rather the exception.
• the contact tubes are normally homogeneous within the container distributed arranged, the distribution is expediently chosen so that the distance of the central inner axes from the nearest contact tubes (the so-called contact tube pitch) is 35 to 45 mm (see, for example, EP-B 468 290).
• Fluid heat transfer media are particularly suitable as heat exchange medium.
• melts of salts such as potassium nitrate, potassium nitrite, sodium nitrite and / or sodium nitrate, or of low-melting metals such as sodium, mercury and alloys of various metals is particularly favorable.
• the procedure according to the invention is suitable for carrying out heterogeneously catalyzed gas phase partial oxidations of precursor compounds of (meth) acrylic acid which are carried out with an increased load on the fixed catalyst bed with the precursor bond, as is e.g. in DE-A 19 948 523.
• Such high-load gas phase partial oxidations are preferably carried out in the multiple (preferably two) zone tube bundle reactors of DE-A 19 948 523.
• the advantage of the procedure according to the invention consists primarily in an increased selectivity of the formation of the product of value, in particular also when using increased loads on the fixed catalyst bed with the precursor compound of (meth) acrylic acid.
• the size of the catalyst body to be used according to the invention is generally such that the longest dimension (longest connecting line between two points on the surface of the catalyst body) is 2 to 12 mm, often 4 to 8 mm.
• a second solution B was prepared by adding 116.25 kg of an aqueous iron nitrate solution (14.2% by weight of Fe) to 333.7 kg of an aqueous cobalt nitrate solution (12.4% by weight of Co) at 30.degree , After the addition had ended, a further 30 min. stirred at 30 ° C. Thereafter, 112.3 kg of an aqueous were at 60 ° C.
• the resulting dry mixture was compacted (pressed) into hollow cylinders (rings) of different geometries such that the resulting density was approximately 2.5 mg / mm 3 and the resulting lateral compressive strength of the rings was approximately 10 N.
• a reaction tube (V2A steel, 30 mm outside diameter; 2 mm wall thickness; 26 mm inside diameter, length: 439 cm) was placed from bottom to top on a contact chair (44 cm length) initially over a length of 30 cm with steatite balls with a rough surface ( 4 to 5 mm in diameter; inert material for heating the reaction gas starting mixture) and then loaded over a length of 270 cm (the fixed catalyst bed) with the catalyst rings produced under A) before the loading over a length of 30 cm was completed with the aforementioned steatite balls as additional bed has been. The remaining contact tube length was left empty.
• the solids-free ends of the reaction tube were kept at 220 ° C. with steam under elevated pressure.
• reaction gas starting mixture of the following composition is fed continuously:
• the table below shows the selectivity of acrolein formation (S A ) achieved depending on the catalyst geometry used.
• the letter V indicates that it is a comparative example, while the letter B indicates that it is an example according to the invention.
• A outer diameter
• the table shows, as example B5, the result in the case of using a catalyst body with a geometry according to FIG. 1.
• Precursor mass was only pressed to the other geometry.
• the diameter and the height of the basic body were 4 mm.
• the groove depth was about 0.5 mm.
• the distance between the part ends of the groove was about 0.9 mm.

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