JP2001500427A - Method for producing catalytically active composite metal oxide composition - Google Patents

Abstract

(57) [Summary] Contains tungsten and / or molybdenum, sulfur, phosphorus, arsenic, boron, silicon and / or germanium, vanadium and / or niobium and antimony, and is converted from methacrolein to methacrylic acid by catalytic gas phase oxidation a method of producing a composite metal oxide compositions suitable as catalysts for, using a source containing at least partially ammonium ions, to conduct the calcination in a firing atmosphere not containing sufficient NH _3.

Description

DETAILED DESCRIPTION OF THE INVENTION                  Method for producing catalytically active composite metal oxide composition   The present invention provides compounds of the general formula I:     X¹ _aX^Two _bX^Three _cX^Four _dX^Five _eSb_fO_n                      (I) [In the formula   X¹Is tungsten and / or molybdenum;   X^TwoIs S, P, As, B, Si and / or Ge;   X^ThreeIs V and / or Nb;   X^FourRepresents Cu, Ag, Zn, Cd, Fe, Ni, Co, Ru, Rh, Pd, Bi And / or an alkaline earth metal,   X^FiveIs an alkali metal, NH⁺ _Four, Tl and / or Te;   a is 12;   b is 0.01 to 10,   c is 0.2 to 6,   d is 0 to 10,   e is 0 to 10,   f is 0.1 to 10, and   n is a number determined by the valence and frequency of the element different from oxygen in the formula I Catalytic activity compound represented by When producing a composite metal oxide composition, at least a portion of the elemental components of the composition Very homogeneous, preferably finely divided, from a source containing Producing a dry mixture which has been dispersed and firing the dried mixture containing molecular oxygen. Of the catalytically active composite metal oxide composition by firing at 150 ° C to 450 ° C in It relates to a manufacturing method.   The invention further provides a composite metal oxide composition obtained using the method of the invention and A catalyst for the production of methacrylic acid from methacrolein by gas-phase catalytic oxidation Regarding its use.   Catalyst active complex metal oxide composition of general formula I Its use as a catalyst for producing luic acid by gas-phase catalytic oxidation is known ( See, for example, German Patent Application Publication No. 4329907).   The composition is generally very homogeneous and advantageous from the source of the elemental components of the composition. To produce a finely dispersed dry mixture, this dry mixture is 150 ° C ~ 450 ° C It is manufactured by firing.   Many sources particularly suitable for the preparation of the catalytically active complex metal oxide compositions of general formula I Is a starting compound containing an ammonium ion. For example, the advantageous molybdenum The source is ammonium salt of molybdic acid and ammonium salt of phosphomolybdic acid It is. Appropriate vanadium Is the source of ammonium vanadate, and the preferred sources of phosphorus and sulfur are Diammonium phosphate and ammonium sulfate. Furthermore, European Patent Publication No. 4 No. 42517, additionally ammonium carbonate, ammonium hydrogen carbonate Compounds such as ammonium, ammonium sulfate and ammonium hydrogen sulfate are converted to compounds of the general formula I It is advantageous to use the composite metal oxide composition of the present invention.   A source containing ammonium ions for the preparation of the composite metal oxide composition of general formula I As a result of the use of NH during the calcination of the corresponding catalyst precursor_ThreeIs released That is, firing is performed in a firing atmosphere containing ammonia. This is especially true of the general formula I When producing the composite metal oxide composition of the present invention on a large-scale industrial scale, special measures must be taken during firing. This is the case if no NH3 is taken, since NH during the calcination of large amounts of catalyst precursor_Threeof This is because the increased absolute amount is naturally released.   German Patent No. 2610249 (for example, page 3, lines 35-38) and European According to State Patent Publication No. 113156 (for example, page 3, lines 23 to 28), At least one element X¹And at least one element X^TwoAnd antimony In the firing atmosphere during the production of the catalytically active composite metal oxide composition_ThreeContent is raw Catalytic activity (for catalytic gas phase oxidation of methacrolein to methacrylic acid) Has advantageous effects. Only However, according to Applicant's research, this may additionally include the element V and / or niobium. Not applicable to the composite metal oxide compositions of the general formula I which need to contain Is shown.   An object of the present invention is to provide a method suitable for catalytic gas-phase oxidation of methacrolein to methacrylic acid. It is an object of the present invention to provide an improved method for producing the composite metal oxide composition of the general formula I.   The object is to at least partially reduce the amount of ammonium component of the component of the composition of general formula I. A very homogeneous, preferably finely dispersed dry mix from a source containing The dried mixture is prepared at 150 ° C. in a firing atmosphere containing molecular oxygen. Catalytically active composite metal oxide composition of general formula I by calcining at a temperature of 450 ° C Is solved by a method comprising the steps of:_ThreeThe content is 0. 75 vol% or less, and the molecular oxygen content during the entire calcination time is 5 vol% or more. The calcination is performed in a forming atmosphere.   The calcination is advantageously carried out with NH during the entire calcination time._ThreeThe content is less than 0.5% by volume, preferably 0 . 25% by volume or less, especially 0.1% by volume or less, particularly preferably 0.05% by volume or less It is performed in a certain firing atmosphere. According to the invention, the molecular oxygen content of the firing atmosphere is: Advantageously, it is not less than 5% by volume and not more than 25% by volume. The remaining components in the firing atmosphere are N for profit_TwoOr, it is made of an inert gas such as a noble gas. Firing time is generally several hours Up to.   The process of the present invention comprises   X¹Is tungsten and / or molybdenum;   X^TwoIs S, P, As and / or Si;   X^ThreeIs V and / or Nb;   X^FourIs Cu, Ag, Zn, Fe, Ni, Co, Rh and / or Bi ,   X^FiveIs an alkali metal, Tl, Te and / or NH⁺ _FourAnd   a is 12;   b is 0.2-3,   c is 0.2-3,   d is 0-2,   e is 0-3,   f is 0.2-3, and   n is a number determined by the valence and frequency of the element different from oxygen in the formula I Has been found to be particularly advantageous for the production of composite metal oxide compositions.   In the case of this composite metal oxide composition of formula I, the process of the invention comprises methacrolein Results in increased catalytic activity for the gas phase catalytic activity conversion of methacrylic acid to methacrylic acid. Do No. 4,329,907 discloses a composite metal oxide composition of the formula I Senarmonite (senarmonite) is a source of at least a part of Sb present in the material. It is preferred according to the invention to use tite).   Advantageously at least 25% of the Sb present in the composite metal oxide composition of the formula I, Particularly advantageously, at least 50% is derived from senamontite as antimony source I do. However, the method according to the invention naturally exists in the form of senamontite. Metal oxide composition produced by adding at least 80% of Sb Includes manufacturing of goods. However, present in the composite metal oxide compositions of the present invention of formula I Advantageously, 1 to 10% of the total amount of Sb is present in the amorphous surrounding material . The senamontite used for preparing the composite metal oxide composition of the formula I of the present invention is It is preferably used in finely dispersed form. Maximum diameter is advantageously greater than 0 μm And 50 μm or less. However, 0.1-25 μm or 0.5-5 μm It may be.   Other suitable sources of the components of the complex metal oxide compositions of general formula I are oxides or acids. A compound that can be converted to an oxide by heating in the presence of element. Therefore appropriate Starting compounds are, in addition to oxides, especially halides, nitrates, formates, oxalates, Acetate, carbonate and hydroxide. Possible starting compounds for Mo and V are These tungstates and vanadates and the acids derived therefrom. Regarding the element Sb, suitable sources are, in addition to senamontite, valentinite ( valentinite) and / or simple salts of Sb such as antimony nitrate.   The intimate mixing of the starting compounds can take place in dry or moist form. Dry When carried out in dry form, the starting compounds are advantageously in the form of a finely divided powder. Used and molded (eg, tableted) after mixing, for example, to produce the desired shaped catalyst compact. This is subsequently fired according to the invention. However, firing is performed according to the present invention. It can also be performed before shaping. However, advantageously, the homogeneous mixture is moistened Implement in the form. In this case, the starting compounds are generally prepared in the form of solutions and / or suspensions. Mix with each other. In this case, the senamontite used as the starting compound It is advantageous if it does not dissolve as much as possible. This is, for example, the source of other elemental components Mix first and stir only the Senarmontite just before the liquid mixture dries It can be done by putting. After the mixing operation is completed, the fluid composition is dried, After drying (before or after shaping), it is calcined according to the invention. Drying, preferably spray drying Perform by drying. The resulting powder is often too fine to mold immediately, and Often to a solid size, followed by grinding to a larger particle size. Or into a dough with the addition of a liquid, typically water, then shaped and drawn Subsequently, firing is performed according to the present invention. If performing homogeneous mixing in wet form, increase Temperature can be used. Dissolution and / or dissolution with the addition of an acid or base Alternatively, suspension may be performed.   The composite metal oxides of the general formula I obtained according to the invention are advantageously not supported catalysts. It is used in the form of a catalyst, which consists solely of the medium, ie the composition of the invention. Outer diameter and Hollow cylinders having a length of 4 to 10 mm and a wall thickness of 1 to 3 mm are particularly advantageous. In the form of a catalyst.   Aqueous mixtures of the starting components are used as auxiliaries in organic compounds such as nitrogen-containing cyclic compounds. A pyridine, carboxylic acid or alcohol to the calcined catalyst composition. May be additionally contained in an amount of 1 to 20% by weight. Wet, generally aqueous mixture Drying of the product is generally performed at 60 to 180 ° C. The catalyst composition or its calcined Molding of the precursor composition without using known methods such as tableting or extrusion In this case, such as graphite or stearic acid Lubricants, molding aids, fine glass fibers, asbestos, silicon carbide or potassium titanate A strengthening agent such as um may be added. However, the compositions of the present invention do not Applied to coated or coated, ie preformed, substantially inert material To produce acrylic acid by gas-phase oxidation of methacrolein in the form of a supported catalyst Application to substantially inert substances can take place, for example, by aqueous starting In the form of a solution or suspension, subsequently combined with drying and calcination according to the invention, Or as a composition of a powder already calcined according to the invention in combination with a binder. Can be applied.   The composite metal oxide compositions of the formula I obtained according to the invention can, of course, be used in the form of a catalyst in powder form. Can be used as   The composite metal oxide composition of the formula I obtained according to the invention is prepared from methacrolein Particularly suitable as catalyst for catalytic gas phase oxidation to produce tacrylic acid, increased Forms methacrylic acid on activation.   Methacrylein can be converted to methacrylic acid by using the catalyst obtained according to the present invention. Catalytic gas-phase oxidation to produce phosphoric acid is described, for example, in DE-A 40 22 212 It is carried out by a known method as described in the detailed description. The same is true of the product gas stream This corresponds to the separation of lylic acid. Acids as oxidants, for example in the form of air and in pure form Element can be used. Due to the high heat of the reaction, the reaction components are advantageously N 2_Two, C O_TwoDiluted with an inert gas such as saturated hydrocarbons and / or steam. use The ratio of methacrolein: oxygen: steam: inert gas used is advantageously 1: (1 to 1 3): (2-20): (3-30), particularly preferably 1: (1-3): (3-10) ): (7 to 18). The methacrolein used can be prepared in various ways, e.g. Gas phase oxidation of sobutylene, t-butanol or methyl ether of t-butanol Can be obtained by In the presence of secondary amines and acids, in the liquid phase, No. 875,114 or German Patent No. 2,855,514. Re Metaclone obtained by condensation of propanol and formaldehyde It is advantageous to use rain. Gas phase oxidation can be performed in a fluidized bed reactor or in a fixed bed It can be carried out in a reactor. Advantageously, the tubes are fixedly arranged, preferably in series. The reaction is carried out in a tube-bundle reactor containing the catalyst component in the form of particles of silica. Reaction temperature is one The reaction pressure is generally between 1 and 3 bar, generally between 250 and 350 ° C. The rate between 800 and 1800 l (standard temperature and pressure, stp) / 1 / h. Under these conditions, methacrolein in one pass through the reactor The conversion is generally between 50 and 80 mol%. These limiting conditions are based on a single reactor operation. The passages are adjusted to one another such that a methacrolein conversion of 60 to 70 mol% is obtained. Methacryl by using the composition of the formula I obtained according to the invention as catalyst The increased activity of the acid formation is higher than 60 l (stp) / l / h Maintained at in-space velocity.   Remarkably, the composition of formula I obtained according to the invention has a high working time. However, its advantageous properties are maintained essentially unchanged.   However, such gas phase oxidation generally does not yield pure methacrylic acid, Instead, methacrylic acid produces a product mixture that must be subsequently separated . This is done in a known manner, for example by reacting the reaction gas indirectly. Washing with water at a temperature of 40-80 ° C. after cooling directly and / or A crylic acid solution is formed, from which methacrylic acid is extracted by generally using an organic solvent. And separation from it by distillation.   However, the composition of the present invention has a tendency to generate methacrylic acid from methacrolein. Besides phase-catalyzed oxidation, other organic compounds, preferably having 3 to 6 carbon atoms Other alkanes, alkanols, alkanals and alkenes (such as propyle , Acrolein, t-butanol, methyl ether of t-butanol, isobutane Olefinically unsaturated alde Hydrates and / or carboxylic acids and the corresponding nitriles (ammoxidation, especially Formation of acrylonitrile from lopene, meta-form from isobutene or t-butanol (Formation of acrylonitrile). A The production of crylic acid, acrolein and methacrolein is described by way of example. Only However, the composition is also suitable for dehydrogenation by oxidation of organic compounds.   The low ammonia content of the firing atmosphere required by the present invention allows air to flow through Can hardly be achieved with conventional calcinations in cooling tube reactors, The invention does not achieve this if the amount of catalyst precursor must be calcined. It is characteristic.   The calcination according to the invention is therefore advantageously carried out in a belt calcination machine. In this case, The material to be formed is deposited in a thin layer on a continuous conveyor belt running horizontally in the firing path. Will remain. Belts generally use a large amount of hot firing gas (eg, hot Screen belt (narrow) through which fresh air passes (with vacuum and / or pressure) Mesh wire mesh). The ammonia thus released should be calcined immediately Removed from the material, NH_ThreeSintering atmosphere which basically does not contain Hot firing The gas can be blown vertically or diagonally into the passing material from below.   The remaining components of the hot calcining gas, apart from the amount of molecular oxygen required according to the invention, Generally N_TwoAnd / or an inert gas such as a noble gas. Particularly simple configuration In this case, hot air is used as a hot firing gas.   The process according to the invention is advantageously carried out in a number of steps.   For example, a two-step firing method is advantageous. In this case, the first baking step is performed at 150 to 3 It is carried out at 00C, preferably at 190-280C. The firing temperature in the second firing step is 350-450 ° C, preferably 370-400 ° C. Firing atmosphere of two firing steps The atmosphere is at least 5% by volume of O_TwoConsists of O of two firing steps_TwoContent is generally 2 5% by volume or less. After the first firing, the volatile NH_ThreeIs generally already scattered You. According to the present invention, the ammonia to be released has a sintering atmosphere of NH 2 in two steps._Three0 . 75% by volume or less, preferably 0.5% by volume or less, more preferably 0.25% by volume or less Below, in particular not more than 0.1% by volume, particularly preferably not more than 0.005% by volume. Must be removed. The firing time for the two steps is generally up to several hours.   The firing time of the first firing step is advantageously 0.5 to 1.5 hours and the second firing step The firing time of the process is generally between 1 and 10 hours, preferably between 1 and 5 hours. According to the invention The firing of the first firing step is particularly advantageously started at about 190 ° C. and carried out for about 20 minutes. Give. Subsequent firing is carried out at 220 ° C. for about 50 minutes and finally at 270 ° C. Perform for about 50 minutes. The second calcination step is particularly preferably at about 370-400 ° C. for about Perform for 3 hours. This is especially the case in DE-A-4329907. This corresponds to the composite metal oxide of Example M6.   Finally, during the calcination to produce the catalytically active complex metal oxide of formula I, NH_ThreeAre described as causing an irreversible decrease in its activity.   An example a) Production of catalyst precursor   At 50 ° C., 530 g of ammonium heptamolybdate tetrahydrate, metavanazine 17.5 g of ammonium acid, 48.9 g of cesium nitrate, concentration of 45% by weight orthophosphorous 81.6 g of an acid, 3.9 g of a 35% by weight aqueous solution of ammonium sulfate, and ammonium trioxide Nchimon (Sena Montai 99% by weight and 1% by weight of valentinite, average maximum particle diameter 0.5 μm) 3 6.5 g was stirred into 600 g of water. The aqueous mixture is subsequently brought to 95 ° C. Heat, add a solution of 51.5 g of copper aqueous solution (Cu 15% by weight) in nitric acid, mix The material was evaporated at the above temperature and dried. Outer diameter 7 mm, length from subsequent composition A hollow cylinder having a diameter of 6 mm and an inner diameter of 3 mm was molded and fired as described below. Done. The stoichiometric ratio of the resulting composite metal oxide is   MO₁₂P_1.5V_0.6Cs_1.0Cu_0.5Sb₁S_0.04 Met. b) Calcination of catalyst precursor   The firing apparatus used was an inner diameter 1 heated electrically to 290 ° C. by external heating. It was a 6 cm steel pipe. Mesh support extending to the cross section of the pipe It was placed in a pipe and coated with the catalyst precursor prepared in a) in a layer thickness of only 5 cm. During firing, hot firing gas (T = 290 ° C) 10m^Three(Stp) / h (Nm^Three (Stp) = standard temperature and pressure, ie cubic at 25 ° C. and 1 atmosphere Meters) passed through the catalyst precursor layer. Low layer thickness and high loading of firing gas As a result of the filling, the firing atmosphere substantially corresponded to the composition of the firing gas. Firing time is 3 hours.   The following firing gas composition was used: A: 100% by volume of air B: 99.43% by volume of air, NH_Three0.57% by volume, C: 98.9% by volume of air, NH_Three1.1% by volume D: 98.43% by volume of air, NH_Three1.57% by volume, E: air 98.37% by volume, NH_Three1.63% by volume, F: 98% by volume of air, NH_Three2% by volume.   Catalysts A, B, C, D, E and F were obtained correspondingly. C) Test of catalytic activity   The calcined hollow cylinder produced in a) was powdered (arithmetic mean particle diameter 1-2). mm), a gas mixture having the following composition:   Methacrolein 5% by volume,   9% oxygen by volume,   25% by volume steam and   Nitrogen 61% by volume At the same time, a tubular reactor (inner diameter 10 mm, catalyst layer 100 g, salt bath temperature at 290 ° C) Control) average residence time 3 seconds and methacrolein rate 0.11 g / g / h (1 (Numerical values in terms of% by volume with respect to stp). The reaction gas obtained The solution was cooled to 40 ° C. and washed sequentially with water and a 50% by weight aqueous acetic acid solution. pull The wash was subsequently analyzed by gas chromatography and polarography, The methacrolein conversion was calculated from the analysis results.   One pass through various catalysts A, B, C, D, E and F The methacrolein conversion achieved by this is shown in the table below. High meth Lorain conversion ([moles of methacrolein reacted / metacrolein used) Mole number] × 100%) shows high catalytic activity. Selectivity for methacrylic acid formation ([ Number of moles of methacrolein converted to methacrylic acid / all converted methacrolein Moles x 100%) was 88% in all cases.     tableCatalyst used Conversion rate   A 79   B 72   C 62   D 62   E 62   F 63   The result obtained is the NH_ThreeShows the opposite effect of the presence of Equivalent composition and Production of a catalyst that has been calcined by flowing air through a cooling tube reactor in a conventional manner. Use results in a stated conversion of less than 70%.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 57/055 C07C 57/055 B // C07B 61/00 300 C07B 61/00 300 (81) Designated country EP (AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), EA (AM, AZ, BY, KG, KZ, MD) , RU, TJ, TM), AL, AU, BG, BR, BY, CA, CN, CZ, GE, HU, IL, JP, KR, KZ, LT, LV, MX, NO, NZ, PL, RO , RU, SG, SI, SK, TR, UA, US (72) Inventor Hermann Petersen Germany D-67269 Grünstadt Rugensteiner Wök 14

Claims (1)

[Claims] 1. General formula ^{_{I: X 1 a X 2 b}} X 3 c X 4 d X 5 e Sb f O n (I) [X 1 in the formula is tungsten and / or molybdenum, X ² is S, P, As, X ³ is V and / or Nb, X ⁴ is Cu, Ag, Zn, Cd, Fe, Ni, Co, Ru, Rh, Pd, Bi and / or alkaline earth a metalloid, X ⁵ is an alkali metal, NH ⁺ _4, Tl and / or Te, a is 12, b is 0.01 to 10, c is 0.2 to 6, d Is from 0 to 10, e is from 0 to 10, f is from 0.1 to 10, and n is a number determined by the valence and frequency of an element different from oxygen in Formula I] In producing the catalytically active composite metal oxide composition represented by, at least a partial A catalytically active composite metal oxide composition comprising: producing a very homogeneous dry mixture from a source containing ammonium ions at a temperature of 150 ° C. to 450 ° C. in a firing atmosphere containing molecular oxygen. Wherein the NH ₃ content of the firing atmosphere during the entire firing time is 0.75% by volume or less and the molecular oxygen content is 5% by volume or more. A method for producing the composition. 2. In the general formula I, X ¹ is tungsten and / or molybdenum, X ² is S, P, As and / or Si, X ³ is V and / or Nb, and X ⁴ is Cu, Ag, Zn , Fe, an Ni, Co, Rh and / or Bi, X ⁵ is an alkali metal, Tl, a Te and / or NH ⁺ _4, a is 12, b is 0.2 to 3, c Is from 0.2 to 3, d is from 0 to 2, e is from 0 to 3, f is from 0.2 to 3, and n is the valence of an element different from oxygen in Formula I and The method of claim 1, wherein the number is determined by a frequency number. 3. _3. The method according to claim 1, wherein the NH ₃ content of the firing atmosphere is 0.25% by volume or less. 4. 3. The calcination according to claim 1 or 2, wherein the calcination is carried out in two temporally successive steps, wherein the temperature of the first calcination step is 150-300C and the temperature of the second calcination step is 350-450C. Method. 5. The method according to any one of claims 1 to 4, wherein the firing is performed in a belt-type firing machine. 6. A composite metal oxide composition obtained by the method according to any one of claims 1 to 5. 7. A catalytic gas phase oxidation method for producing methacrylic acid from methacrolein, comprising using the composite metal oxide composition according to claim 6 as a catalyst. 8. Use of the composite metal oxide composition according to claim 6 as a catalyst for catalytic gas phase oxidation of methacrylic acid from methacrolein.