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Definitions

• the present invention relates to a method for producing a multimetal oxide mass M of general stoichiometry I,
• M 1 at least one of the elements from the group comprising Al, Ga, In, Ge, Sn, Pb, As, Bi Se, Te and Sb;
• M 2 at least one of the elements from the group comprising Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Cr, W, Mn, Fe, Co, Ni, Zn, Cd and the lanthanides;
• M 3 at least one of the elements from the group comprising Re, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag and Au;
• M 4 at least one of the elements from the group comprising Li, Na, K, Rb, Cr, Be, Mg, Ca, Sr, Ba, NH 4 and TI;
• n a number which is determined by the valency and frequency of the elements other than oxygen in (I),
• Multimetal oxide compositions M of general stoichiometry I and processes for their preparation are known (cf. for example EP-A 318 295, EP-A 512 846, EP-A 767 164, EP-A 865 809, EP-A 529 853, EP-A 608 838, EP-A 962 253, DE-A 102 48 584, DE-A 101 19 933, DE-A 101 18 814, DE-A 100 29 338, DE-A 103 59 027, DE-A 103 21 398 , EP-A 1 407 819, Applied Catalysis A: General 194-195 (2000), pp. 479-485; Applied Catalysis A: General 200 (2000), pp. 135-143; Chem.
• multimetal oxide compositions M as active compositions for catalysts for heterogeneously catalyzed partial gas phase oxidation and for heterogeneously catalyzed partial gas phase ammoxidation (differs from pure partial gas phase oxidation essentially by the additional presence of ammonia) of (for example 3 to 8, in particular 2 or 3 and / or 4 carbon atoms) saturated and unsaturated hydrocarbons, alcohols and aldehydes are suitable.
• Partial oxidation products include ⁇ .ß-monoethylenically unsaturated aldehydes (e.g.
• acrolein and methacroiein and, ß-monoethylenically unsaturated carboxylic acids (e.g. acrylic acid and methacrylic acid) and their nitriles (e.g. acrylonitrile and methacrylonitrile).
• carboxylic acids e.g. acrylic acid and methacrylic acid
• nitriles e.g. acrylonitrile and methacrylonitrile
• the target compounds acrolein, acrylic acid and / or acrylonitrile are e.g. as described available from the hydrocarbons propane and / or propene.
• Acrolein itself can also be the starting compound for the preparation of the latter two compounds.
• These target compounds form important intermediates which e.g. used for the production of polymers, e.g. can be used as adhesives.
• methacroiein and methacrylic acid can be obtained from isobutane and isobutene.
• Methacroiein can also be the starting compound for the production of methacrylic acid.
• multimetal oxide compositions M predominantly occur in two different crystal phases, which are referred to in the literature as “i-phase” and as “k-phase”.
• the associated X-ray diffractogram is used as a fingerprint of the respective crystal phase to identify it and to identify its crystalline structure.
• the X-ray diffractogram of the crystalline i-phase is characterized in that the subsequent X-ray diffraction pattern RMi, reproduced in the form of of the wavelength of the X-rays used 'independent interplanar spacings d [A], d [A] 3.06 + 0.2 3.17 + 0.2 3.28 + 0.2 3.99 + 0.2 9.82 + 0.4 11.24 + 0.4 13.28 + 0.5
• the X-ray diffractogram of the crystalline k-phase is characterized in that it has the following X-ray diffraction pattern RMk, reproduced in the form of network plane distances d [A], [ ⁇ ] 4.02 + 0.2 3.16, which are independent of the wavelength of the X-ray radiation used + 0.2 2.48 + 0.2 2.01 + 0.2 1.82 + 0.1,
• the i-phase and k-phase are similar to one another, but differ primarily in that the X-ray diffractogram of the k-phase normally has no diffraction reflections for d> 4.2 A.
• the k phase usually also contains no diffraction reflections in the range 3.8 A> d> 3.35 A. Furthermore, the k phase generally does not contain any diffraction reflections in the range 2.95 A> d> 2.68 ⁇ .
• the catalytic activity (activity, selectivity of target product formation) of the multimetal oxide compositions with i-phase structure is generally superior to those in other (e.g. k-phase) structures.
• multimetal oxide compositions M of general stoichiometry I is generally carried out in such a way that an intimate dry mixture is produced from their starting compounds (sources) containing elemental constituents and this is thermally treated at elevated temperature.
• Increased i-phase proportions up to exclusive i-phase are generally obtained if a mixture of sources of the elemental constituents of the multimetal oxide mass M is subjected to hydrothermal treatment and the newly formed solid is separated off (cf. A 2003 / 0187299A1, DE-A 100 29 338, EP-A 1 270 068, EP-A 1 346 766 and EP-A 1 407 819).
• a disadvantage of such a hydrothermal production method is that its reproducibility, especially when it is produced in large-scale quantities, is not fully satisfactory.
• the i-phase portion resulting from such a production fluctuates around a mean value in a comparatively large range during repeated production.
• this mean value is often a comparatively low i-phase component.
• the catalytic performance of the product which is immediately available hydrothermally is often unsatisfactory and generally requires subsequent thermal treatment to improve it.
• the object of the present invention was therefore to provide a hydrothermal process for the production of multimetal oxide compositions M of general stoichiometry I which is improved with respect to the disadvantages mentioned.
• M 1 at least one of the elements from the group comprising AI (+3), Ga (+3), In (+3), Ge (+4), Sn (+4), Pb (+4), As (+ 5), Bi (+5), Se (+6), Te (+6) and Sb (+5);
• M 2 at least one of the elements from the group comprising Sc (+3), Y (+3), La (+3), Ti (+4), Zr (+4), Hf (+4), Nb (+ 5), Ta (+5+), Cr (+5), W (+6), Mn (+7), Fe (+3), Co (+3), Ni (+3), Zn (+2 ), Cd (+2) and the lanthanides (Ce (+4), Pr (+3), Nd (+3), Pm (+3), Sm (+3), Eu (+3), Gd (+ 3), Tb (+4), Dy (+3), Ho (+3), Er (+3), Tm (+3), Yb (+3) and Lu (+3));
• M 3 at least one of the elements from the group comprising Re (+7), Ru (+8), Rh (+8), Pd (+8), Os (+8) lr (+8+), Pt (+8 ), Cu (+2), Ag (+1) and Au (+1);
• M 4 at least one of the elements from the group comprising Li (+1), Na (+1), K (+1), Rb (+1), Cs (+1), Be (+2), Mg (+ 2), Ca (+2), lr (+2), Ba (+2), NH 4 (+1) and Tl (+1);
• n a number which is determined by the valency and frequency of the elements other than oxygen in (I),
• the sources of the elementary constituents of the multimetal oxide mass M are exclusively sources from the group comprising compounds , which consist only of the elementary constituents of the multimetal oxide mass M and elementary constituents of water (O, H, OH), the elementary constituents of the multimetal oxide mass M itself in their elemental form and elemental constituents of the multimetal oxide mass M containing ammonium salts (ie, sources from of the group comprising oxides, oxide hydrates, oxygen acids, hydroxides, oxide hydroxides of the elemental constituents, the metal elements of the elemental constituents and compounds such as ammonium metavanadate or ammonium heptamolybodate) are used with the proviso that the molar ratio MV N H ⁇ Mo from NH contained in mixture G and Mo contained in mixture G is ⁇ 0.5 and at least a partial amount
• Sources of elementary constituents that have elementary constituents contained in these sources with an oxidation number that is below the maximum oxidation number of the respective elemental constituent this is the one behind the individually listed elements M 1 , M 2 , M 3 and M 4 in brackets with a positive sign).
• At least a subset of the (of mixture G) sources of the elemental constituent V preferably contains the vanadium with an oxidation number ⁇ +5 (e.g. +4, or +3, or + 2, or 0).
• the pressure range typically extends to (> 1 bar) up to 500 bar, preferably up to 250 bar.
• temperatures above 600 ° C. and water vapor pressures above 500 bar can also be used, but this is less expedient in terms of application technology.
• the hydrothermal treatment according to the invention is particularly advantageously carried out under conditions under which water vapor and liquid aqueous phase coexist. This is possible in the temperature range from> 100 to 374.15 ° C (critical temperature of the water) using the appropriate pressures.
• the amounts of water are expediently dimensioned such that the liquid aqueous phase is able to absorb the total amount of the starting compounds of the elemental constituents in suspension and / or solution.
• the hydrothermal treatment according to the invention advantageously takes place at temperatures> 100 ° C. to 300 ° C., preferably at temperatures from 120 ° C. or from 150 ° C. to 250 ° C. (e.g. 160 ° C. to 180 ° C.).
• the weight fraction of the latter in the autoclave generally bears at least 1% by weight.
• the aforementioned proportion by weight is usually not above 90% by weight.
• Weight proportions of 5 to 60 or 10 to 50% by weight are preferred, more preferably 20 or 30 to 50% by weight.
• the proportion by weight of such further substances should normally be ⁇ 10% by weight, advantageously ⁇ 5% by weight and even better ⁇ 3% by weight.
• Foreign substances are, for example, all the substances listed in DE-A 100 29 338 and EP-A 1 407 819 but also H 2 O 2 (taking into account the preferred redox conditions).
• the molar ratio MV is advantageously ⁇ 0.3, particularly preferably ⁇ 0.1 and very particularly preferably 0.
• the process according to the invention preferably at least 5 mol%, or at least 10 mol%, preferably at least 20 mol% or at least 30 mol%, very particularly preferably at least 40 mol% or at least 50 mol% and most preferably at least 60 mol% or at least 70 mol% or at least 80 mol% or at least 90 mol% or more (with particular advantage the total amount) of the V contained in these sources as vanadium, the oxidation number of which is ⁇ +5.
• the arithmetic mean oxidation number of the V averaged over the molar total amount of V of the vanadium sources contained in the mixture G is preferably +3.5 to +4.5, particularly preferably +3.8 to +4.2 and very particularly preferably +4 ,
• the composition of the mixture G in the process according to the invention is preferably chosen with regard to the oxidation numbers of the elemental constituents contained in the sources for the mixture G in such a way that with a change of all elementary constituents different from V (+5), which are not contained in the sources of the mixture G in their maximum oxidation number (including V ( ⁇ + 5)), in their respective maximum (with V in its second highest Oxidation number +4) Oxidation number the resulting reduct potential is just sufficient to set the mean oxidation number of the total V contained in the sources of the mixture G to a value from 3.5 to 4.5, particularly preferably from 3.8 to 4.2 and very particularly preferably from 4.
• hydrothermal treatment according to the invention is carried out under an oxidative, molecular oxygen-containing atmosphere (e.g. under standing, closed air), the aforementioned reduction potential can be correspondingly higher.
• the conditions of the hydrothermal treatment according to the invention are preferably chosen such that the above reduction potential is actually implemented in the manner described during the hydrothermal treatment.
• the oxidation number of an atom in a free element is zero. 2.
• the oxidation number of a monatomic ion is equal to its charge.
• the oxidation number corresponds to the charge that each atom contains when the binding electron pairs are completely assigned to the more electron-negative atom. With electron pairs between two identical atoms, each atom receives one electron.
• sources of element V for the process according to the invention are primarily: vanadium oxides such as VO 2 , V 2 O 3 , V 6 O 13 , V 3 O 7 , V 4 O 9 and VO, elemental vanadium, and, under Consideration of the quantity limits according to the invention, also compounds such as V 2 O 5 and ammonium metavanadate.
• Suitable sources for the element Mo according to the invention are, for example, molybdenum oxides such as MoO 3 and MoO 2 , but elemental Mo, taking into account those according to the invention
• Quantity limits including compounds such as ammonium heptamolybdate and its hydrates.
• sources of the element tellurium are, for example, tellurium oxides such as TeO 2 , metallic tellurium, but also telluric acids such as orthotelluric acid H 6 TeO 6 .
• Antimony starting compounds which are advantageous according to the invention are, for example, antimony oxides such as Sb 2 O 3 , elemental Sb, but also antimonic acids such as HSb (OH) 6 .
• Niobium sources suitable according to the invention are, for example, niobium oxides such as Nb 2 O 5 or elemental Nb.
• An advantageous bismuth source according to the invention is Bi 2 O 3 .
• An advantageous source of gold is gold hydroxide.
• Further advantageous starting compounds for the process according to the invention are, for example, silver oxide, copper hydroxide, copper oxide, alkali and alkaline earth oxide or hydroxide, scandium oxide, iridium oxide, zinc oxide, Ga 2 O, Ga 2 O 3 etc.
• mixed oxides also come as sources of the elemental constituents into consideration, which contain more than one elementary constituent and, if appropriate, have been obtained by a hydrothermal route, for example by the hydrothermal route according to the invention. Further sources of the elementary constituents which are suitable according to the invention can be found in the documents of the cited prior art.
• the hydrothermal treatment according to the invention itself generally takes from a few minutes or hours to a few days. A period of 48 hours is typical.
• the inside of the autoclave to be used for the hydrothermal treatment is coated with Teflon.
• the autoclave optionally including the aqueous mixture it contains, can advantageously be evacuated.
• it can preferably be filled with inert gas (N 2 , noble gas such as He, Ne and / or argon). Both measures can also be omitted in a less advantageous manner.
• the aqueous mixture can additionally or alternatively be flushed with inert gas for advantageous inerting prior to the hydrothermal treatment according to the invention.
• the aforementioned inert gases can also be used expediently to set above atmospheric pressure before the hydrothermal treatment in the autoclave.
• the autoclave Upon completion of the hydrothermal treatment, the autoclave can either be quenched to room temperature or slowly, i.e. be brought to room temperature over a longer period of time (e.g. left by yourself).
• the solid newly formed in the course of the hydrothermal treatment according to the invention and separated off after the end of the hydrothermal treatment is normally a multimetal oxide M with an increased or exclusive i-phase content and that this is obtained according to the invention in improved reproducibility , It is also essential according to the invention that the multimetal oxides M obtainable by the process according to the invention develop the desired catalytic activity even without a thermal treatment following the hydrothermal treatment.
• the multimetal oxides M obtainable according to the invention can additionally advantageously be thermally aftertreated before they are used as active compositions for the heterogeneously catalyzed processes mentioned at the outset.
• This thermal aftertreatment can be carried out at temperatures of 200 to 1200 ° C, preferably 350 to 700 ° C, often 400 to 650 ° C and often 400 to 600 ° C.
• the oxidizing atmosphere is e.g. Air, air enriched with molecular oxygen or air de-oxygenated.
• the thermal treatment is carried out under an inert atmosphere, i.e. e.g. carried out under molecular nitrogen and / or noble gas (He, Ar and / or Ne) (inert atmosphere in this document always means that the content of molecular oxygen then normally ⁇ 5% by volume, preferably ⁇ 3% by volume, particularly preferably ⁇ 1% by volume or ⁇ 0.1% by volume and most preferably 0% by volume).
• inert atmosphere i.e. e.g. carried out under molecular nitrogen and / or noble gas (He, Ar and / or Ne)
• inert atmosphere in this document always means that the content of molecular oxygen then normally ⁇ 5% by volume, preferably ⁇ 3% by volume, particularly preferably ⁇ 1% by volume or ⁇ 0.1% by volume and most preferably 0% by volume.
• the thermal aftertreatment can also be carried out under vacuum.
• the thermal aftertreatment can take up to 24 hours or more.
• a thermal aftertreatment is preferably carried out first under an oxidizing (oxygen-containing) atmosphere (e.g. under air) at a temperature of 150 ° C to 400 ° C or 250 ° C to 350 ° C. Thereafter, the thermal aftertreatment is expediently continued under inert gas at temperatures of 350 ° C. to 700 ° C. or 400 ° C. to 650 ° C. or 400 ° C. to 600 ° C.
• the thermal aftertreatment of the hydrothermally generated multimetal oxide M can also be carried out in such a way that the hydrothermally generated multimetal oxide M is first tableted, then thermally aftertreated and then split.
• the multimetal oxide M obtainable in the context of the hydrothermal process according to the invention is split up for the purpose of its thermal aftertreatment.
• both the multimetal oxide compositions M obtainable according to the invention by hydrothermal means and their secondary or successor multimetal oxide compositions which have been thermally post-treated as described can be further treated in an advantageous manner by, for example, in DE-A 102 54 279 and EP-A 1 : 4Q7 819 beBciTilben, "with suitable liquids.
• suitable liquids for example, organic acids or their aqueous solutions (e.g. oxalic acid, formic acid, acetic acid, citric acid and tartaric acid) as well as inorganic acids and their aqueous solutions (e.g.
• JP-A 7-232 071 and DE-A 103 21 398 also disclose a suitable washing process. Such a wash generally leaves pure i-phase (or an increased i-phase portion), which in the washed state normally also has an additionally improved catalyst performance.
• the intimate mixing of the starting compounds of the elementary constituents to obtain the mixture G to be treated hydrothermally can take place in dry or in wet form. If it is in dry form, the starting compounds are expediently used as finely divided powders. However, the intimate mixing is preferably carried out in wet, aqueous form.
• the starting compounds are preferably mixed with one another in the form of an aqueous solution (optionally with the use of small amounts of complexing agents) and / or finely divided suspension.
• the X-ray diffraction pattern RMi of the multimetal oxide masses M which can be obtained hydrothermally according to the invention or their secondary masses (or also subsequent masses) which can be obtained by thermal aftertreatment and / or by washing as described (or depending on those contained) Elements and the crystal geometry (eg needle shape or platelet shape)) additional characteristic diffraction reflex intensities.
• these (relative) diffraction reflex intensities I (%) are as follows: d [A] I (%) 3.06 + 0.2 ( preferably + 0.1) 5 to 65 3.17 + 0.2 (preferably + 0.1) 5 to 65 3.28 + 0.2 (preferably + 0.1) 15 to 130, often 15 to 95 3.99 + 0.2 (preferably + 0.1) 100 9.82 + 0.4 (preferably + 0.2) 1 to 50, often 1 to 30 11, 24 + 0.4 (preferably + 0.2) 1 to 45, often 1 to 30 13.28 + 0.5 (preferably + 0.3) 1 to 35, often 1 to 15.
• the following x-ray diffraction pattern RMi also frequently shows the following diffraction reflections, also reproduced in the form of network plane spacings d [A] which are independent of the wavelength of the x-ray radiation used: d [A] 8.19 + 0, 3 (preferably + 0.15) 3.51 + 0.2 (preferably + 0.1) 3.42 + 0.2 (preferably + 0.1) 3.34 + 0.2 (preferably + 0.1) 2.94 + 0.2 (preferably + 0.1) 2.86 + 0.2 (preferably + 0.1).
• the (relative) intensities I (%) of the above diffraction reflexes are often as follows: d [A] I (%) 8.19 + 0.3 (or + 0.15) 0 to 25 3.51 + _0.2 (or + 0.1) 2 to 50 3.42 + 0.2 (or + 0.1) 5 to 75 3.34 + 0.2 (or + 0.1) 5 to 80 2.94 + 0.2 (or + 0.1) 5 to 55 2.86 + 0.2 (or + 0.1 ) 5 to 60.
• the (relative) diffraction reflex intensities obtained in the same way as above are often as follows for these diffraction reflections: d [A] I (%) 2.54 + 0.2 (or + 0.1) 0.5 to 40 2, 01 + 0.2 (or + 0.1) 5 to 60.
• X-ray diffraction patterns RMi or the multimetal oxide masses belonging to them or their subsequent masses
• the 2 ⁇ half-value width of the other diffraction reflections mentioned is normally ⁇ 3 °, preferably ⁇ 1, 5 °, particularly preferably ⁇ 1 °.
• the wavelength ⁇ of the X-ray radiation used for diffraction and the diffraction angle ⁇ (the apex of a reflection in the 2 ⁇ order is used as the diffraction reflex layer in this document) are linked as follows via the Bragg relationship:
• d is the network plane distance of the atomic spatial arrangement belonging to the respective diffraction reflex.
• Preferred multimetal oxide compositions M of general stoichiometry I are those for which:
• M 1 at least one of the elements from the group comprising Sb, Bi, Se and Te;
• M 2 at least one of the elements from the group comprising Ti, Zr, Nb, Cr, W, Fe, Co, Ni and Zn;
• n a number which is determined by the valency and frequency of the elements other than oxygen in (I).
• the stoichiometric coefficient a of the multimetal oxide compositions M obtainable according to the invention (and the subsequent compositions belonging to them), particularly independently of the preferred ranges for the other stoichiometric coefficients of the multimetal oxide compositions M and the selected element composition, is 0.05 to 0.5 0.1 to 0.5.
• the stoichiometric coefficient b is preferably> 0 or 0.01 to 0.5, and particularly preferably 0.1 to 0.5 or to 0.4.
• the stoichiometric coefficient c of the multimetal oxide compositions M obtainable according to the invention is advantageously from 0.01 to 0.5 and particularly preferably from 0.1 to 0.5 or to 0.4.
• a very particularly preferred range for the stoichiometric coefficient c which, regardless of the preferred ranges for the other stoichiometric coefficients of the multimetal oxide materials M obtainable according to the invention, can be combined with all other preferred ranges in this document and all selected element compositions, is the range 0.05 to 0 ; 2.
• the stoichiometric coefficient d of the multimetal oxide compositions M obtainable according to the invention is preferably> 0 or 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.
• the coefficient e can also be> 0 to 0.1 and advantageously also 0.
• Multimetal oxide compositions M which are obtainable according to the invention and whose stoichiometric coefficients a, b, c and d are simultaneously in the following grid are particularly favorable:
• Multimetal oxide compositions M obtainable according to the invention are particularly favorable, their stoichiometric coefficients a, b, c and d simultaneously lying in the following grid:
• fl1 is preferably Bi, Se, Te and / or Sb and very particularly preferably Te.
• M 2 is at least 50 mol% of its total amount of Nb, Ti, Zr, Cr, W, Fe.Co, Ni, Zn and / or Ta and very particularly when M 2 at least 50 mol% or at least 75 mol% of its total amount, or 100 mol% of its total amount Nb and at least one of the elements Ti, Zr, Cr, Ta, W, Fe, Co, Ni and Zn or Nb and / or Ta is.
• M 3 is at least one element from the group comprising Re, Pd and Pt.
• M 2 contains at least 50 mol% of its total amount, or at least 75 mol%, or 100 mol% Nb and M 3 contains at least one element from the group comprising Re, Pd and Pt is.
• the multimetal oxide compositions M of the general stoichiometry I which are obtainable according to the invention by hydrothermal means as described or the secondary compositions of these multimetal oxide compositions (they generally also have the stoichiometry I) can be used as such (ie as a powder or as chippings) or as shaped articles Shaped as catalytic active materials for all partial gas phase oxidations and / or amoxidations of eg saturated and unsaturated hydrocarbons or lower aldehydes and / or alcohols are used.
• the catalyst bed can be a fixed bed, a moving bed or a fluidized bed.
• the shape can e.g. by extrusion or tableting in the case of unsupported catalysts or by application to a support body (production of coated catalysts) as described in DE-A 10118814 or PCT / EP / 02/04073 or DE-A 10051419.
• the support bodies to be used in the case of coated catalysts for the multimetal oxide compositions M obtainable according to the invention and their subsequent compositions are preferably chemically inert. This means that they essentially do not intervene in the course of the partial catalytic gas phase oxidation or amoxidation of the hydrocarbon (eg propane and / or propene to give acrylic acid), alcohol or aldehyde, which is catalyzed by the multimetal oxide compositions M obtainable according to the invention and their subsequent compositions on.
• the hydrocarbon eg propane and / or propene to give acrylic acid
• alcohol or aldehyde which is catalyzed by the multimetal oxide compositions M obtainable according to the invention and their subsequent compositions on.
• the surface of the carrier body can be both smooth and rough.
• the surface of the carrier body is advantageously rough, since an increased surface roughness generally results in an increased adhesive strength of the applied active material shell.
• the surface roughness R z of the carrier body is often in the range from 5 to 200 ⁇ m, often in the range from 20 to 100 ⁇ m (determined in accordance with DIN 4768 Sheet 1 using a "Hommel Tester for DIN-ISO surface measurement parameters" from Hommelwerke, DE).
• the carrier material can be porous or non-porous.
• the carrier material is expediently non-porous (total volume of the pores based on the volume of the carrier body ⁇ _1% by volume).
• the thickness of the active oxide mass shell located in the shell catalysts according to the invention is usually from 10 to 1000 ⁇ m. However, it can also be 50 to 700 ⁇ m, 100 to 600 ⁇ m or 150 to 400 ⁇ m. Possible shell thicknesses are also 10 to 500 ⁇ m, 100 to 500 ⁇ m or 150 to 300 ⁇ m.
• any geometries of the carrier bodies can be considered for the method according to the invention.
• Their longest dimension is usually 1 to 10 mm.
• balls or cylinders, in particular hollow cylinders are preferably used as carrier bodies.
• Favorable diameters for carrier balls are 1.5 to 4 mm.
• cylinders are used as carrier bodies, their length is preferably 2 to 10 mm and their outside diameter is preferably 4 to 10 mm.
• the wall thickness is also usually 1 to 4 mm.
• Annular carrier bodies suitable according to the invention can also have a length of 3 to 6 mm, an outer diameter of 4 to 8 mm and a wall thickness of 1 to 2 mm.
• a carrier ring geometry of 7 mm x 3 mm x 4 mm or 5 mm x 3 mm x 2 mm (outer diameter x length x inner diameter) is also possible.
• the shell catalysts can be produced in a very simple manner by forming multimetal oxide compositions M or their back-up composition in the manner according to the invention, converting them into a finely divided form and finally applying them to the surface of the support body with the aid of a liquid binder.
• the surface of the carrier body is moistened in the simplest manner with the liquid binder, and a layer of the active composition is attached to the moistened surface by contacting it with finely divided active multimetal oxide composition M obtained according to the invention M or finely divided follower composition. Finally, the coated carrier body is dried.
• multimetal oxide compositions M or their back-up composition in the manner according to the invention, converting them into a finely divided form and finally applying them to the surface of the support body with the aid of a liquid binder.
• the surface of the carrier body is moistened in the simplest manner with the liquid binder, and a layer of the active composition is attached to the moistened surface by contacting it with finely divided active multimetal oxide composition M obtained
• the fineness of the catalytically active multimetal oxide composition M of the general formula (I) to be applied to the surface of the carrier body or its subsequent composition is of course adapted to the desired shell thickness.
• the shell thickness range from 100 to 500 " ⁇ m, £ B are suitable .
• Such active bulk powders from which pass at least 50% of the total number of powder particles through a sieve with a mesh size of 1 to 20 ⁇ m and whose numerical proportion of particles with a longest dimension above 50 ⁇ m is less than 10%.
• the distribution of the longest dimensions of the powder particles corresponds to a Gaussian distribution due to the manufacturing process.
• the particle size distribution is often as follows:
• D diameter of the particle
• x the percentage of particles whose diameter is> D
• y the percentage of particles whose diameter is ⁇ D.
• the carrier bodies to be coated are rotated in a preferably inclined (the angle of inclination is generally> 0 ° and ⁇ 90 °, usually> 30 ° and ⁇ 90 °; the angle of inclination is the angle of the center axis of the rotating container against the horizontal) (e.g. B. turntable or coating drum).
• the rotating rotary container leads the z. B. spherical or cylindrical carrier body under two consecutively arranged metering devices at a certain distance.
• the first of the two metering devices suitably corresponds to a nozzle (for example an atomizing nozzle operated with compressed air) through which the carrier bodies rolling in the rotating turntable are sprayed with the liquid binder and moistened in a controlled manner.
• the second metering device is located outside the atomizing cone of the sprayed-in liquid binder and serves to supply the finely divided oxidic active material (for example via a shaking channel or a powder screw).
• the controlled, moistened carrier balls take up the active mass powder that is fed through the rolled lumbar movement on the outer surface of the z.
• the base body coated in this way again passes through the spray nozzles in the course of the subsequent rotation, is moistened in a controlled manner in order to be able to take up a further layer of finely divided oxidic active material, etc. (intermediate drying is generally not necessary). Fine-particle oxidic active material and liquid binder are usually fed in continuously and simultaneously.
• the removal of the liquid binder can be done after the coating z. B. by the action of hot gases such as N 2 or air.
• hot gases such as N 2 or air.
• the coating method described brings about both a fully satisfactory adhesion of the successive layers to one another and also the base layer on the surface of the carrier body.
• the moistening of the surface of the carrier body to be coated is carried out in a controlled manner.
• Detailed information on this can be found in DE-A 2909671 and in DE-A 10051419.
• the aforementioned final removal of the liquid binder used can be carried out in a controlled manner, for. B. by evaporation and / or sublimation. In the simplest case, this can be done by exposure to hot gases of the appropriate temperature (often 50 to 300, often 150 ° C). The effects of hot gases can also only be used for predrying.
• the final drying can then take place, for example, in a drying oven of any type (for example a belt dryer) or in the reactor.
• the temperature acting should not be above the calcination temperature used to produce the oxidic active composition. Of course, drying can also be carried out exclusively in a drying oven.
• binders for the coating process 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 acid, glutaric acid or maleic acid, amino alcohols such as ethanolamine or difethane ⁇ irrirrs as well as mono- or polyvalent organic ganic amides such as formamide.
• 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 acid, glutaric acid or maleic acid
• binders are also solutions consisting of 20 to 90% by weight of water and 10 to 80% by weight of an organic compound dissolved in water, whose boiling point or sublimation temperature at normal pressure (1 atm)> 100 ° C., preferably> 150 ° C, is.
• the organic compound is advantageously selected from the above list of possible organic binders.
• the organic proportion of the aforementioned aqueous binder solutions is preferably 10 to 50 and particularly preferably 20 to 30% by weight.
• Monosaccharides and oligosaccharides such as glucose, fructose, sucrose or lactose as well as polyethylene oxides and polyacrylates are also suitable as organic components.
• Balls, solid cylinders and hollow cylinders come into consideration as geometries (both for solid catalysts and for shell catalysts).
• the longest dimension of the aforementioned geometries is usually 1 to 10 mm.
• their length is preferably 2 to 10 mm and their outside diameter is preferably 4 to 10 mm.
• the wall density is also usually 1 to 4 mm.
• Suitable annular unsupported catalysts can also have a length of 3 to 6 mm, an outer diameter of 4 to 8 mm and a wall thickness of 1 to 2 mm.
• a full catalyst ring geometry of 7 mm x 3 mm x 4 mm or 5 mm x 3 mm x 2 mm (outer diameter x length x inner diameter) is also possible.
• all those of DE-A 101 01 695 are also suitable for the geometry of the multimetal oxide active compositions M obtainable according to the invention and their successor compositions.
• the specific surface area of multimetal oxide compositions M (and their subsequent compositions) obtainable according to the invention is in many cases 1 to 80 m 2 / g between 40 m 2 / g, often 11 or 12 to 40 m 2 / g and frequently 15 or 20 to 40 or 30 m 2 / g (determined according to the BET method, nitrogen).
• the multimetal oxide compositions M and their subsequent compositions obtainable according to the invention can also be used with finely divided, e.g. colloidal, essentially only thinning materials, such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide and niobium oxide diluted form can be used as catalytic active materials.
• finely divided, e.g. colloidal, essentially only thinning materials such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide and niobium oxide diluted form can be used as catalytic active materials.
• the dilution mass ratio can be up to 9 (thinner): 1 (active mass). This means that possible dilution mass ratios are, for example, 6 (thinner): 1 (active mass) and 3 (thinner): 1 (active mass).
• the thinners can be incorporated before and / or after a thermal aftertreatment.
• the multimetal oxide compositions M obtainable according to the invention and their successor compositions are suitable as such or in the form just described (as already mentioned) as active compositions for heterogeneously catalyzed partial gas phase oxidations (including oxide hydrogenations) and / or ammoxidations of saturated and / or unsaturated hydrocarbons and of alcohols and aldehydes (for example in a process according to DE-A 103 16465).
• Such saturated and / or unsaturated hydrocarbons are in particular ethanol, ethylene, propane, propylene, n-butane, isobutane and isobutene.
• the main target products are acrolein, acrylic acid, methacroiein, methacrylic acid, acrylonitrile and methacrylonitrile.
• they are also suitable for the heterogeneously catalyzed partial gas phase oxidation and / or amoxidation of compounds such as acrolein and methacroiein.
• ethylene, propylene and acetic acid can also be the target product.
• a complete oxidation of a hydrocarbon, alcohol and / or aldehyde is understood in this document to mean that the total carbon contained in the hydrocarbon, alcohol and / or aldehyde is converted into oxides of carbon (CO, CO 2 ).
• the multimetal oxide compositions M and their subsequent compositions obtainable according to this document are preferably suitable as catalytic active compositions for the conversion of propane to 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 methacroiein and / or methacrylic acid, from isobutane to methacrylic acid and / or methacrylonitrile, from ethane to ethylene, from ethane to acetic acid and from ethylene to acetic acid.
• reaction gas mixture which can be controlled in a manner known per se
• the reaction can essentially be designed exclusively as partial oxidation, or exclusively as partial ammoxidation, or as a superimposition of both reactions; cf.
• WO 98/22421 is known per se from the multimetal oxide compositions of general stoichiometry I of the prior art and can be carried out in a completely corresponding manner.
• crude propane or crude propylene is used as the hydrocarbon, this is preferably composed as described in DE-A 102 46 119 or DE-A 101 18 814 or PCT / EP / 02/04073. The same procedure as described there is preferred.
• a partial oxidation of propane to acrylic acid to be carried out with multimetal oxide M active composition (or successor active composition) catalysts can e.g. as described in EP-A 608 838, EP-A 1 407 819, WO 00/29106, JP-A 10-36311 and EP-A 1 192 987. ,
• reaction gas starting mixture contains no noble gas, in particular no helium, as the inert diluent gas.
• the reaction gas starting mixture can of course also comprise inert diluent gases such as N 2 , CO and CO 2 . Water vapor as a component of the reaction gas mixture is advantageous according to the invention.
• reaction gas starting mixture with which the multimetal oxide active composition M obtainable according to the invention or its subsequent composition at reaction temperatures of e.g. 200 to 550 ° C or from 230 to 480 ° C or 300 to 440 ° C and pressures from 1 to 10 bar or 2 to 5 bar have the following composition:
• Reaction gas starting mixtures containing water vapor are preferred.
• compositions of the reaction gas starting mixture are:
• the acrylic acid contained can be taken up from the product gas mixture by absorption with water or by absorption with a high-boiling inert hydrophobic organic solvent (for example a mixture of diphenyl ether and diphyl which may also contain additives such as dimethyl phthalate).
• a high-boiling inert hydrophobic organic solvent for example a mixture of diphenyl ether and diphyl which may also contain additives such as dimethyl phthalate.
• the resulting mixture of absorbent and acrylic acid can then be, rectification, extraction and / or crystallization worked up in a manner known per se to give pure acrylic acid.
• the basic separation of the acrylic acid from the product gas mixture can also be carried out by fractional condensation, as described, for example, in DE-A 19 924 532.
• the resulting aqueous acrylic acid condensate can then e.g. can be further purified by fractional crystallization (e.g. suspension crystallization and / or layer crystallization).
• fractional crystallization e.g. suspension crystallization and / or layer crystallization.
• the residual gas mixture remaining in the basic separation of acrylic acid contains, in particular, unreacted propane, which is preferably recycled into the gas phase oxidation. For this purpose, e.g. partially or fully separated by fractional pressure rectification and then returned to the gas phase oxidation. However, it is more favorable to bring the residual gas into contact with a hydrophobic organic solvent in an extraction device (e.g. by passing it through), which the propane is able to absorb preferentially.
• the absorbed propane can be released again by subsequent desorption and / or stripping with air and returned to the process according to the invention. In this way, economic total propane sales can be achieved.
• propene formed as a secondary component is generally not or not completely separated from the propane and circulated with it. This also applies to other homologous saturated and olefinic hydrocarbons. Above all, it applies very generally to heterogeneously catalyzed partial oxidations and / or amoxidations of saturated hydrocarbons according to the invention.
• the multallall oxide masses M obtainable according to the invention and their successor masses can also heterogeneously catalyze the partial oxidation and / or amoxidation of the homologous olefinic hydrocarbon to the same target product.
• acrylic acid by heterogeneously catalyzed partial gas phase oxidation of propene with molecular oxygen as in DE-A 101 18 814 or PCT / EP / 02/04073 or JP-A 7-53448 described.
• reaction zone A a single reaction zone A is sufficient to carry out the process.
• this reaction zone there are exclusively multimetal oxide mass M or successor mass catalysts available as catalytically active masses.
• the catalysts to be used can be diluted with inert material, as was recommended in this document, for example, as a support material.
• the propene partial oxidation process according to the invention is carried out as a fixed bed oxidation, it is expediently carried out in a tube bundle reactor, the contact tubes of which are charged with the catalyst.
• a liquid usually a salt bath, is usually passed around the contact tubes as a heat transfer medium.
• a plurality of temperature zones along the reaction zone A can then be realized in a simple manner by passing more than one salt bath around the contact tubes in sections along the contact tubes.
• the reaction gas mixture is viewed in the catalyst tubes via 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.
• the salt bath around the catalyst tubes can also carry out a meandering flow, which, viewed only via the reactor, is conducted in cocurrent or countercurrent to the reaction gas mixture.
• the reaction temperature in the propene partial oxidation process can be 200 ° to 500 ° C. along the entire reaction zone A. Usually it will be 250 to 450 ° C.
• the reaction temperature is preferably 330 to 420 ° C., particularly preferably 350 to 400 ° C.
• the working pressure in the propene partial oxidation process can be either 1 bar, less than 1 bar or more than 1 bar.
• Typical working pressures according to the invention are 1.5 to 10 bar, frequently 1.5 to 5 bar.
• the propene to be used for the propene partial oxidation process is not subject to particularly high purity requirements.
• propene can be used for such a process in general, e.g. Propene (also called raw propene) of the following two specifications can be used without any problems:
• propene is also suitable as a source of propene for the process according to the invention, which is formed as a by-product in a process which differs from the process according to the invention and e.g. contains up to 40% of its weight propane.
• This propene can additionally be accompanied by other accompanying components which do not substantially disrupt the process according to the invention.
• Pure oxygen as well as air or air enriched or depleted with oxygen can be used as the oxygen source for the propene partial oxidation process.
• a reaction gas starting mixture to be used for the propene partial oxidation process usually also contains at least one diluent gas.
• nitrogen, carbon oxides, noble gases and lower hydrocarbons such as methane, ethane and propane come into consideration (higher ones, eg C 4 hydrocarbons should be avoided).
• Water vapor is also often used as a diluent. Mixtures of the aforementioned gases frequently form the diluent gas for the partial propene oxidation process.
• the heterogeneously catalyzed partial oxidation of propene is advantageously carried out in the presence of propane.
• reaction gas starting mixture for the propene oxidation process is typically composed as follows (molar ratios):
• the aforementioned ratio is preferably 1: (1-5): (1-40): (0-10).
• propane is used as the diluent gas, this can, as described, advantageously also be partially oxidized to acrylic acid.
• the reaction gas starting mixture advantageously contains molecular nitrogen, CO, CO 2 , water vapor and propane as the diluent gas.
• the molar ratio of propane: propene can assume the following values in the propene oxidation process: 0 to 15, often 0 to 10, often 0 to 5, advantageously 0.01 to 3.
• the loading of the catalyst with propene can be, for example, 40 to 250 Nl / l » h or more.
• the loading of starting reaction gas mixture is often in the range from 500 to 15,000 Nl / I »h, often in the range 600 to 10,000 Nl / lh, often 700 to 5,000 Nl / l * h.
• a product gas mixture is obtained which does not consist exclusively of acrylic acid. Rather, the product gas mixture contains, in addition to unconverted propene, secondary components such as propane, acrolein, CO 2 , CO, H 2 O, acetic acid, propionic acid, etc., from which the acrylic acid must be separated.
• secondary components such as propane, acrolein, CO 2 , CO, H 2 O, acetic acid, propionic acid, etc.
• the acrylic acid contained in the product gas mixture can be absorbed by absorption with water or by absorption with a high-boiling inert hydrophobic organic solvent (e.g. a mixture of diphenyl ether and diphyl which may also contain additives such as dimethyl phthalate).
• a high-boiling inert hydrophobic organic solvent e.g. a mixture of diphenyl ether and diphyl which may also contain additives such as dimethyl phthalate.
• the resulting mixture of absorbent and acrylic acid can then be worked up in a manner known per se by rectification, extraction and / or crystallization to give pure acrylic acid.
• the basic separation of the acrylic acid from the product gas mixture can also be carried out by fractional condensation, as it is e.g. is described in DE-A 199 24 532.
• the resulting aqueous acrylic acid condensate can then e.g. can be further purified by fractional crystallization (e.g. suspension crystallization and / or layer crystallization).
• fractional crystallization e.g. suspension crystallization and / or layer crystallization.
• the residual gas mixture remaining in the basic separation of acrylic acid contains, in particular, unreacted propene (and possibly propane).
• This can be separated from the residual gas mixture, for example by fractional pressure rectification, and then recycled into the gas phase oxidation according to the invention.
• it is more favorable to bring the residual gas into contact with a hydrophobic organic solvent in an extraction device (for example by passing it through), which the propene (and optionally propane) is able to absorb preferentially.
• the absorbed propene (and optionally propane) can be released again by subsequent desorption and / or stripping with air and returned to the process according to the invention. In this way, economic total propene sales can be achieved.
• propene is partially oxidized in the presence of propane, propene and propane are preferably separated off and recycled together.
• the multimetal oxides M and their subsequent compositions obtainable according to the invention can be used as catalysts for the partial oxidation of isobutane and / or isobutene to methacrylic acid.
• the multimetal oxide compositions M and their subsequent compositions obtainable according to the invention can also be integrated into other multimetal oxide compositions (for example, mixing their finely divided compositions, optionally pressing and calcining, or mixing, preferably aqueous) as slurries, drying and calcining (for example as described in EP-A 529 853 describes)). It is preferably calcined again under inert gas.
• the resulting multimetal oxide compositions preferably contain> 50% by weight, particularly preferably> 75% by weight, and very particularly preferably> 90% by weight or> 95% by weight of multimetal oxide compositions M obtainable according to the invention or their successive dimensions and are also suitable for the partial oxidations and / or amoxidations discussed in this document.
• the geometric shape of the total masses is expediently as described for the multimetal oxide masses M according to the invention and their successor masses.
• the multimetal oxide compositions M obtainable according to the invention, their successor compositions and multimetal oxide compositions or catalysts containing such compositions are preferably put into operation as described in DE-A 101 22 027.
• the excellent reproducibility when using the procedure according to the invention is attributed to the fact that the desired multimetal oxide M occurs in an environment which essentially contains only water and its constituents H, O, OH. In this way, the multimetal oxide M is quasi below its natural intrinsic pH, which obviously gives the procedure a particularly robust character.
• Example 1 Production of a multimetal oxide mass of the weighing stoichiometry
• the lid of the autoclave was closed and the portion of air in the autoclave above the aqueous phase was exchanged for nitrogen by flushing with nitrogen.
• the autoclave was then heated continuously (linearly) to 175 ° C. in the course of 10 hours under autogenous pressure with continuous stirring (700 rpm) and held at this temperature with further stirring for 48 hours.
• the mixture was then cooled to room temperature (25 ° C.).
• the autoclave - was opened and the black powder formed was filtered, washed three times 'mitje' 2ü0 ml Washed water at 25 ° C and then dried at 80 ° C for 12 h in a vacuum drying cabinet.
• FIG. 1 shows, only the i-phase is obtained.
• SEM scanning electron micrograph (FIG. 2, three different magnifications) shows needle-shaped crystals with a high length-to-thickness ratio of approximately 50 to 100.
• needle or “fiber shape” is likely to be that other (additional) crystallographic surfaces are more accessible to catalysis compared to an isotropic material.
• Comparative Example 1 Production of a multimetal oxide mass of the weighing stoichiometry
• Example 1 The procedure was then as in Example 1 (hydrothermal). The experiment carried out as described was repeated ten times. In two cases there was an increased proportion of i-phase in the multimetal oxide powder formed. In the eight other experiments, on the other hand, a phase mixture was obtained which contained only a small i-phase portion.
• Example 2 Production of a multimetal oxide mass of the weighing stoichiometry Mo V G , 32 Bio ⁇ 027 O x
• the powder X-ray diffractogram (cf. FIG. 3) showed in all cases only i-phase for the black powder obtained.
• the associated scanning electron micrograph (FIG. 4, three different magnifications) shows needle-shaped crystals with a high length-to-thickness ratio of approximately 30 to 150.
• Comparative Example 2 Production of a multimetal oxide mass of weighing stoichiometry Mo 1 V 0 ⁇ 32 Bio, o 2 7 ⁇
• Example 2 The procedure was as in Example 2. Instead of MoO 3 , however, 151.87 g (NH) 6 Mo 7 O 2 -4H 2 O (as in Comparative Example 1) and instead of VO 2 became 66.64 g of vanadyl sulfate hydrate (VOSO 4 (H 2 O) x ) (as in Comparative Example 1). The experiment was repeated ten times. In two cases, an increased proportion of i-phase was obtained in the black powder produced.
• VOSO 4 (H 2 O) x vanadyl sulfate hydrate
• phase mixture with only a digestive part was obtained.
• the remaining phases could be identified ai ⁇ ' Phase 05-0508 of the JPDS file [MoO 3 , orthorhombic], as phase 47-0872 of the JPDS file [HMo ⁇ O ⁇ OH eI JH 2 O], as phase 48-0744 of the JPDS file (Bi-VO 4 , tetragonal), as phase 85-0630 of the JPDS file (Bi 0.88 M ⁇ o , 37 Vo , 63 O), as crystal structure of phase 70-2321 (c) of the JPDS file [Sb 2 Mo 10 O 31 , orthorhombic ], as the crystal structure of phase 33-0104 of the JPDS file (Sb 4 M ⁇ 0 O 31 , hexagonal) and / or phase 77-0649 (c) of the JPDS file [(V 0 , 95 M ⁇ o, 97 ⁇ 5 , triclinic
• Example 3 Production of a multimetal oxide mass of the weighing stoichiometry
• the autoclave was closed and the proportion of air in the autoclave above the aqueous solution was replaced by nitrogen flushing with nitrogen.
• the autoclave was then heated continuously (linearly) to 90 ° C. over a period of 3 hours with continuous stirring (700 rpm) and under autogenous pressure and stirred at this temperature for 10 hours.
• the mixture was then heated continuously (linearly) to 175 ° C. in the course of 8 hours with continuous stirring (700 rpm) and under autogenous pressure and held at this temperature with stirring for 24 hours.
• the mixture was then cooled to room temperature (25 ° C.) and, as in Example 1, the black powder formed was filtered off, washed with water and dried.
• Example 2 The experiment carried out as described was repeated ten times. The same result as in Example 2 was obtained in six of the 10 embodiments.
• Example 4 Production of a multimetal oxide mass of the weighing stoichiometry
• Example 5 Preparation of a multimetal oxide material of the Stoichiometry Mo 1 V 0, 25 NbO, o Bio 98, o 42 x ⁇
• Example 2 The procedure was as in Example 1. That is, 123.27 g of MoO 3 were weighed out again, as well as the quantities of VO 2 , Nb 2 O 5 and Bi 2 O 3 required according to the stoichiometry required.
• Example 6 Production of a multimetal oxide mass of weighing stoichiometry M01Vo.3Sbo.25Nbo.12Ox
• Example 2 The procedure was as in Example 1. That is, 123.27 g of M0O 3 were weighed out again, as well as the quantities of VO 2 , Sb 2 O 3 and Nb 2 O 5 required in this regard according to the stoichiometry required.
• Example 7 Production of a multimetal oxide mass of the weighing stoichiometry M ⁇ V 0 ⁇ 3 Nbo, i 3 Sbo , i 3 ⁇ 4, 25
• Example 2 The procedure was as in Example 1. That is, 123.27 g of M0O3 were weighed out again, as well as the quantities of VO 2 , Nb 2 O 5 and Sb 2 O 3 required according to the stoichiometry required.
• Example 8 Production of a multimetal oxide mass of weighing stoichiometry M0 Vo.3Nbo.13Nio.13Ox
• Example 2 The procedure was as in Example 1. That is, 123.27 g of M0O 3 were weighed out again, as well as the quantities of VO 2 , Nb 2 O 5 and NiO required in this regard according to the stoichiometry required.
• Example 2 The procedure was as in Example 1. That is, 123.27 g of MoO 3 were weighed out again, as well as the quantities of VO 2 , Nb 2 O 5 and CoO required in this regard according to the stoichiometry required.
• Example 10 Preparation of a multimetal oxide material of the Stoichiometry M ⁇ V 0, 3 Nb 0 ⁇ i Cro 3, O 3 iO ⁇
• Example 11 Production of a multimetal oxide mass of the weighing stoichiometry
• Example 2 The procedure was as in Example 2. 100 g of the obtained and dried multimetal oxide mass were placed in 500 g of a 10% strength by weight aqueous nitric acid. The resulting aqueous suspension was stirred under reflux at 80 ° C for 5 h. Then it was cooled to 25 ° C. The solid in the black suspension was separated from the aqueous phase by filtration, washed free of nitrate with water and then dried in a forced-air drying cabinet at 120 ° C. overnight.
• Example 2 The procedure was as in Example 2. 100 g of the obtained and dried multimetal oxide mass were in a rotary ball oven (internal volume: 1 liter) according to FIG. 1 of DE-A 100 29 338 under a stream of molecular nitrogen (10 Nl / h) at a heating rate of 2 ° C./min from room temperature Heated 500 ° C and kept at this temperature while maintaining the nitrogen flow for 6 h. The mixture was then left to cool to 25 ° C. while maintaining the nitrogen flow.
• molecular nitrogen (10 Nl / h)
• Example 12 As in Example 5, but was thermally aftertreated as in Example 12.
• Example 7 As in Example 7, but was thermally aftertreated as in Example 12.
• the drum was rotated at 25 revolutions per minute.
• the nozzle was installed in such a way that the spray cone moistened the carrier bodies in the drum, which were transported by driving plates to the uppermost point of the inclined drum, in the upper half of the rolling path.
• the finely divided active material powder was introduced into the drum via a powder screw, the point at which the powder was added being within the rolling zone or below the spray cone. Due to the periodic repetition of wetting and powder metering, the base-coated carrier body itself became the carrier body in the subsequent period.
• the coated carrier body was dried in air in a muffle furnace at 150 ° C. for 16 h.
• a tubular reactor made of steel (inside diameter: 8.5 mm, length: 140 cm, wall thickness: 2.5 cm) was charged with 35.0 g each of the respective coated catalyst from B (catalyst bed length in all cases approx. 53 cm).
• a pre-fill of 30 cm steatite balls (diameter: 2.2 to 3.2 mm, manufacturer: Ceramtec, steatite C 220) and after the catalyst bed, a bed of the same steatite balls was added to the remaining length of the tubular reactor.
• the outside temperature T of the charged reaction tube was raised along the entire length from the outside by means of electrically heated heating mats. set the desired value.
• the residence time (based on the catalyst bed) volume) was set to 2.4 sec.
• the inlet pressure was 2 bar absolute.
• the following table shows the resulting propane conversion (U PAN (mol%)), the resulting selectivity of acrylic acid formation (S A cs (mol%)) and the selectivity depending on the coated catalyst used and the set outside temperature T (° C) by-product formation on propene (S PE N (mol%)).

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