DE102016007628A1 - Tungsten phosphates of the ReO3 structural family - Google Patents

Abstract

The present invention relates to novel tungsten phosphates of the ReO3 structural family, to a process for preparing the tungsten phosphates of the ReO3 structural family, and to the use of the tungsten phosphates of the ReO3 structural family according to the invention as a heterogeneous catalyst for carrying out chemical reactions.

Description

The present invention relates to new tungsten phosphates of ReO ₃ -Strukturfamilie, a method for manufacturing the tungsten phosphates of ReO ₃ -Strukturfamilie and the use of tungsten phosphates of the invention ReO ₃ -Strukturfamilie as a heterogeneous catalyst for carrying out chemical reactions.

In recent decades, the thermal decomposition of the keggin anion ( JF Keggin, Proc. Roy. Soc. A 1934, 144, 75 ) to form tetragonal or cubic WO ₃ structures ( MB Varfolomeev, VV Burljaev, TA Toporenskaya, H.-J. Lunk, W. Wilde, W. Hilmer, Z. Anorg. Gen. Chem. 1981, 472, 185 ; H.-J. Lunk, MB Varfolomeev, W. Hilmer, Zh. Neorg. Khim. 1983, 28, 936 ; UB Mioč, R. Ž. Dimitrijevic, M. Davidoic, ZP Nedic, MM Mitrovic, P. Colomban, J. Mater. Sci. 1994, 29, 3705 ). A Keggin anion (12-tungstato-1-phosphate) can be described by the molecular formula [P (W ₁₂ O ₄₀ )] ^3- or simplified by: {PW12}.

The decomposition of compounds containing the keggin anion {e.g. As H ₃ PW ₁₂ O ₄₀ · 29 H ₂ O ( MB Varfolomeev, VV Burljaev, TA Toporenskaya, H.-J. Lunk, W. Wilde, W. Hilmer, Z. Anorg. Gen. Chem. 1981, 472, 185 ; H.-J. Lunk, MB Varfolomeev, W. Hilmer, Zh. Neorg. Khim. 1983, 28, 936 ; UB Mioć, R. Ž. Dimitrijevic, M. Davidoic, ZP Nedic, MM Mitrovic, P. Colomban, J. Mater. Sc ,. 1994, 29, 3705 ); [Al (H ₂ O) ₆ ] PW ₁₂ O ₄₀ .4H ₂ O ( AR Siedle, TE Wood, ML Brostrom, DC Koskenmaki, B. Montez, E. Oldfield, J. Am. Chem. Soc. 1989, 111, 1665 )} leads to the formation of phases with tetragonal or cubic WO ₃ structure ( T. Vogt, PM Woodward, BA Hunter, J. Solid State Chem. 1999, 144, 209 ; LS Palatnik, OA Obol'yaninova, MN Naboka, NT Gladkikh, Izv. Akad. Nauk SSSR, Neorg. Mater. 1973, 9, 718 ). So far, however, no compounds of the ReO _{3 family of} structures are known which contain higher levels of PO _2.5 of up to 50 mol%. In addition, no compounds are known in which a significant proportion of the tungsten is replaced by one or two elements of the group Sc, Ti, V, Cr, Fe, In, Mo or Sb.

T. Vogt describes ( J. Solid State Chem. 1999, 144, 209 ) Neutron diffraction experiments to structurally characterize the various modifications of pure WO ₃ between room temperature and 850 ° C.

LS Palatnik describes in Izv. Akad. Nauk SSSR, Neorg. Mater. 1973, 9, 718 new cubic modifications of W ₂ O ₃ and WO ₃ in thin condensed films.

Tungsten phosphates are characterized by structural diversity and high variability in chemical composition. This combination leads to interesting property profiles. Therefore, (modified) tungsten phosphates can be used as catalysts.

It is therefore the object of the present invention to provide novel tungsten phosphates of the ReO ₃ structural family, in particular with a so-called tetragonal and / or cubic WO ₃ structure.

Another object of the invention is the preparation of the tungsten phosphates of the ReO _{3 family of} structures and the development of tungsten phosphates of the ReO _{3 family of} structures for use as heterogeneous catalysts.

The object has been achieved by tungsten phosphates of the ReO ₃ structural family of the general formula (I): (M _{a M'b} W _c P _d ) O _{3 -x} (I) wherein
M is at least one element selected from the group consisting of Sc, Ti, V, Cr, Fe, Nb, Mo, In, Sb or mixtures thereof,
M 'is at least one element selected from the group consisting of Sc, Ti, V, Cr, Fe, Nb, Mo, In, Sb or mixtures thereof,
a is a value of ≥ 0 to ≤ 0.30,
b is a value of ≥ 0 to ≤ 0.30,
c is a value of ≥ 0.30 to ≤ 0.93,
d is a value of ≥ 0 to ≤ 0.5, in particular a value of ≥ 0.07 to ≤ 0.5, and
x has a value of ≥ 0 to ≤ 0.5,
where M is not M '.

In other words, preferably, for the tungsten phosphates of the ReO ₃ structure family of the general formula (I), 0 ≦ a ≦ 0.30, 0 ≦ b ≦ 0.30, 0.30 ≦ c ≦ 0.93, 0 ≦ d ≦ 0 , 5, in particular 0.07 ≤ d ≤ 0.5, and 0 ≤ x ≤ 0.5.

In particular, the tungsten phosphates of the ReO ₃ structural family contain the elements of the general formula (I) (M _a M ' _b W _c P _d ) O _3-x , where M and M' stand for the elements already described. In particular, the tungsten phosphates of the ReO ₃ structural family are composed of the elements of the general formula (I) (M _a M ' _b W _c P _d ) O _3-x , where M and M' represent the elements already described.

The object has also been achieved by a process for the preparation of the tungsten phosphates according to the invention of the ReO ₃ structural family of the general formula (I).

The object was additionally achieved by the use of the tungsten phosphates according to the invention of the ReO ₃ structural family of the general formula (I) as heterogeneous catalysts, in particular as oxidation catalysts, for carrying out chemical reactions.

The ReO _{3 family of} structures are compounds with crystal structures derived from the crystal structure of the rhenium (VI) oxide ReO ₃ . From WO ₃ various modifications with different symmetries are known ( T. Vogt, PM Woodward, BA Hunter, J. Solid State Chem. 1999, 144, 209 ; LS Palatnik, OA Obol'yaninova, MN Naboka, NT Gladkikh, Izv. Akad. Nauk SSSR, Neorg. Mater. 1973, 9, 718 ) whose crystal structures are derived from that of the (cubic) ReO ₃ by different distortions. The existence of pure WO ₃ in the cubic, to ReO ₃ isotypic structure is not assured. In particular, it is unclear whether this phase can occur only in the presence of foreign elements.

The compounds of the ReO ₃ structural family, in particular the claimed compounds of the ReO ₃ structural family, are distinguished by characteristic reflections in their powder X-ray diffraction pattern with at least six diffraction reflections at the lattice plane spacings d, the six diffraction reflectors d ₁ = 3.78 ± 0, 02 Angstrom (Å), d ₂ = 2.67 ± 0.02 Å, d ₃ = 2.18 ± 0.02 Å, d ₄ = 1.88 ± 0.02 Å, d ₅ = 1.68 ± 0 , 02 Å and d ₆ = 1.54 ± 0.02 Å.

Tungsten phosphates of the ReO ₃ structural family of the general formula (I) are preferred: (M _{a M'b} W _c P _d ) O _{3 -x} (I) wherein
M is at least one element selected from the group consisting of V, Fe, Sb or mixtures thereof,
M 'is at least one element selected from the group consisting of V, Fe, Sb or mixtures thereof,
a is a value of ≥ 0 to ≤ 0.30,
b is a value of ≥ 0 to ≤ 0.30,
c is a value of ≥ 0.30 to ≤ 0.93,
d is a value of ≥ 0 to ≤ 0.5, in particular a value of ≥ 0.07 to ≤ 0.5, and
x has a value of ≥ 0 to ≤ 0.5,
where M is not M '.

Tungsten phosphates of the ReO ₃ structural family of the general formula (I) are preferred: (M _{a M'b} W _c P _d ) O _{3 -x} (I) wherein
M is at least one element selected from the group consisting of Sc, Ti, V, Cr, Fe, Nb, Mo, In, Sb or mixtures thereof,
M 'is at least one element selected from the group consisting of Sc, Ti, V, Cr, Fe, Nb, Mo, In, Sb or mixtures thereof,
a is a value of ≥ 0.01 to ≤ 0.30,
b is a value of ≥ 0.01 to ≤ 0.30,
c is a value of ≥ 0.30 to ≤ 0.93,
d is a value of ≥ 0.07 to ≤ 0.5, and
x has a value of ≥ 0.01 to ≤ 0.5,
where M is not M '.

Particular preference is given to tungsten phosphates of the ReO ₃ structural family of the general formula (I): (M _{a M'b} W _c P _d ) O _{3 -x} (I) wherein
M is at least one element selected from the group consisting of V, Fe, Sb or mixtures thereof,
M 'is at least one element selected from the group consisting of V, Fe, Sb or mixtures thereof,
a is a value of ≥ 0.01 to ≤ 0.30,
b is a value of ≥ 0.01 to ≤ 0.30,
c is a value of ≥ 0.30 to ≤ 0.93,
d is a value of ≥ 0.07 to ≤ 0.5, and
x has a value of ≥ 0.01 to ≤ 0.5,
where M is not M '.

In the meaning of the present invention, M other than M 'means that M is an element other than M' in the tungsten phosphate of the present invention.

A + b + c + d = 1 is preferred in the tungsten phosphates. In this case, a can have a value of ≥ 0 to ≦ 0.30, b a value of ≥ 0 to ≦ 0.30, c a value of ≥ 0.30 to ≤ 0.93, your value from ≥ 0 to ≤ 0.5, and x has a value of ≥ 0 to ≤ 0.5. Particularly preferably, a can have a value of ≥ 0.01 to ≦ 0.30, b a value of ≥ 0.01 to ≦ 0.30, c a value of ≥ 0.30 to ≦ 0.93, your value of ≥ 0 , 07 to ≤ 0.5, and x has a value of ≥ 0.01 to ≤ 0.5.

By x can assume a value of ≥ 0 to ≤ 0.5, the charge neutrality is guaranteed depending on the oxidation states of the elements involved.

The tungsten phosphates preferably have a tetragonal or cubic WO ₃ structure.

Preferably, a and / or b have a value of ≥ 0.01 to ≦ 0.3. Particularly preferably, a and / or b have a value of ≥ 0.05 to ≦ 0.3, very particularly preferably a and / or b have a value of ≥ 0.1 to ≦ 0.3.

Preferably has your value of ≥ 0.07 to ≤ 0.5, especially your value of ≥ 0.07 to ≤ 0.4.

Particularly preferably, the tungsten phosphates, in particular modified tungsten phosphates, a powder X-ray diffraction pattern with diffraction reflections at lattice spacings d, which are selected from the group consisting of d ₁ = 3.78 ± 0.02 angstrom (Å), d ₂ = 2.67 ± 0 , 02 Å, d ₃ = 2.18 ± 0.02 Å, d ₄ = 1.88 ± 0.02 Å, d ₅ = 1.68 ± 0.02 Å and d ₆ = 1.54 ± 0.02 Å.

Another term for powder X-ray diffraction pattern is X-ray powder diffraction. Tungsten phosphates, in particular modified tungsten phosphates, in which the lattice parameters of the cubic unit cell for the lengths a1, b1 and c1 have the values for a1 = b1 = c1 = 3.78 ± 0.1 Å and where the values for the angles α, β, γ have the values α = 90 °, β = 90 °, γ = 90 ° or for the tetragonal unit cells the lengths a1, b1 and c1 have the values for a1 = b1 = 5.30 ± 0.1 Å and c1 = 7.69 ± 0.1 Å and wherein the values for the angles α, β, γ have the values α = 90 °, β = 90 °, γ = 90 °.

• i) Bereitstellen einer homogenen Lösung umfassend mindestens eine Wolframverbindung, mindestens ein Oxidationsmittel, mindestens eine Phosphorverbindung und mindestens ein Additiv,
• ii) Behandlung des Reaktionsgemisches aus Schritt i) unter Erhalt eines Feststoffes F1,
• iii) Erhitzen des Feststoffes F1 auf eine Temperatur in einem Bereich von 300°C bis 600°C unter Erhalt des Feststoffes F2,
• iv) Erhitzen des Feststoffes F2 auf eine Temperatur in einem Bereich von 300°C bis 800°C unter verschiedenen Gasatmosphären.

The invention further provides a process for preparing the tungsten phosphates according to the invention of the ReO ₃ structural family of the general formula (I), comprising the steps:

• i) providing a homogeneous solution comprising at least one tungsten compound, at least one oxidizing agent, at least one phosphorus compound and at least one additive,
• ii) treatment of the reaction mixture from step i) to obtain a solid F1,
• iii) heating the solid F1 to a temperature in the range of 300 ° C to 600 ° C to obtain the solid F2,
• iv) heating the solid F2 to a temperature in a range of 300 ° C to 800 ° C under various gas atmospheres.

Step i)

The step i) is understood in the process according to the invention to provide a homogeneous solution comprising at least one tungsten compound, at least one oxidizing agent, at least one phosphorus compound and at least one additive. Preferably, a solvent is also provided.

In this case, the solvent in step i) may be a protic, polar solvent. Especially preferred are alcohols and water. Also preferred are mixtures of water and organic solvents such as alcohols, ketones or esters.

Suitable oxidizing agents are H ₂ O ₂ , S, I ₂ , O ₃ , O ₂ , F ₂ , Cl ₂ , S ₂ O ₈ , HBiO ₃ , MnO ₂ , KMnO ₄ , HNO ₃ , KClO ₃ and / or CuO ,

Also suitable oxidizing agents are selected from salts containing the ions MnO ₄ ^- , OCl ^- , NO ₃ ^- , ClO ₃ ^- , ClO ₂ ^- , Au ³⁺ , Pt ²⁺ , Pb ⁴⁺ , BrO ₃ ^- , CrO ₄ ^2- , Fe (CN) ₆ ^3- , Co ³⁺ , Ni ³⁺ , FeO ₄ ^2- , AsO ₄ ^3- , Cu ²⁺ , Sn ²⁺ , Pb ⁴⁺ , As ³⁺ and / or Bi ³⁺ .

Preferably, the oxidizing agent is nitric acid.

Preferably, the tungsten compound is the (NH ₄ ) ₂ W ₁₂ O ₃₉ hydrate.

Preferably, the phosphorus compound comprises salts or esters of phosphoric acid. As the phosphorus compound, for example, phosphoric acid, phosphorus (V) oxide, ammonium hydrogenphosphate or diammonium hydrogenphosphate can be used.

Very particular preference is given to (NH ₄ ) ₂ HPO ₄ .

Preferred additives are oxides of metals from the group M, M ': Sc, Ti, V, Cr, Fe, Nb, Mo, In, Sb.

The proportions depend on the desired composition of the product, therefore the tungsten phosphate of the general formula (I): (M _{a M'b} W _c P _d ) O _{3 -x} (I)

Preferably, the reaction mixture is reacted (i.e., at least one tungsten compound, at least one oxidant, at least one phosphorus compound, and at least one additive). The components of the reaction mixture are preferably brought into contact with each other. For example, at least one tungsten compound, at least one oxidizing agent, at least one phosphorus compound and at least one additive are placed in a reaction vessel. The order of addition can be varied.

The provision can be made of a homogeneous solution of the educts as well as their suspension in aqueous nitric acid. Preferably, the synthesis of a product by the reaction of the starting materials can be carried out.

The provision can be carried out at a temperature in a range of 0 ° C to 120 ° C, in particular in a range of 15 ° C to 80 ° C, wherein the pressure corresponds to the normal pressure. Normal pressure refers to the standard physical conditions.

The provision can take place within a period of 0.25 to 48 hours, in particular within 0.5 to 12 hours.

Step ii)

Under the step ii) in the process according to the invention the treatment of the reaction mixture from step i) to obtain a solid F1 understood. Particularly preferably, the treatment is carried out under vacuum or with the supply of energy, so that the solvent is removed. For example, the solvent can be evaporated.

Preferably, a thermal treatment of the reaction mixture from step i) takes place at a temperature of 20 ° C to 180 ° C to obtain a solid F1. Preferably, the treatment is carried out under normal pressure.

Step iii)

Under the step iii) is understood in the process according to the invention, the heating of the solid F1 to a temperature in a range of 300 ° C to 600 ° C to obtain the solid F2.

In this case, the solid F1 can be placed in a preheated oven. In particular, the solid F1 can be placed in a preheated oven at 400 ° C to 600 ° C for 3 to 15 minutes.

In this process step, the solid is brought to its ignition temperature. At this temperature, combustion may occur by oxidation with oxygen of the solid F1 to form the solid F2.

Step iv)

The step iv) in the process according to the invention is understood to mean the heating of the solid F 2 to a temperature in a range from 300 ° C. to 800 ° C. under different gas atmospheres. Therefore, step iv) may be carried out in an oxygen atmosphere, in air or in a hydrogen atmosphere. The hydrogen atmosphere has preferably been saturated with water vapor at room temperature.

During and / or after step iv), the solid F3 can be obtained. This solid F3 may be a nanocrystalline polynary tungsten phosphate particle.

In step iv), the temperature may be gradually increased in a range of 300 ° C to 800 ° C. In this case, the temperature in each stage can be increased by 100 ° C and recorded from the resulting compound for the reaction control a Pulverröngtendiffraktogramm. Annealing, d. H. Gradually increase the temperature by 100 ° C, can be stopped as soon as the desired structure has formed. The final temperature depends on the connection to be made.

Advantageously, in step iv) the oxidation states of the metals in the tungsten phosphate can be adjusted in a targeted manner. Also in step iv) the amount of metaphosphate melt on the surface of the nanocrystalline polynary tungsten phosphate particles and the particle size of the tungsten phosphates can be influenced.

Preferably, the gas atmosphere is an oxygen atmosphere of either air having an oxygen partial pressure p (O ₂ ) in a range of 0.1 to 0.4 bar abs or argon having an oxygen partial pressure p (O ₂ ) in a range of 10 ^-6 to 10 ^{. 4} bar absolute. The total pressure of air or argon with oxygen is 1 bar absolute.

Preferably, the gas atmosphere is a hydrogen atmosphere of hydrogen with oxygen, wherein the oxygen partial pressure p (O ₂ ) in a range 10 ^-37 to 10 ^-22 bar absolute in a temperature range of 500 ° C to 800 ° C and the total pressure of oxygen and hydrogen 1 bar absolute results.

Another object of the invention is the use of the tungsten phosphates according to the invention of the ReO ₃ -Strukturfamilie the general formula (I) as heterogeneous catalysts for carrying out chemical reactions. The use of the tungsten phosphates according to the invention of the ReO ₃ structural family of the general formula (I) as oxidation catalysts for carrying out chemical reactions is particularly preferred. Preferred tungsten phosphates are mentioned above.

Preferably, the tungsten phosphates according to the invention having a tetragonal or cubic WO ₃ structure of the general formula (I) are used as heterogeneous catalysts for the selective oxidation of at least one hydrocarbon to an anhydride or of an aldehyde group to a carboxylic acid group.

Preferably, the selective oxidation of a hydrocarbon to an anhydride or from an aldehyde group to a carboxylic acid group occurs at a temperature of 300 ° C to 500 ° C. Particularly preferably, the selective oxidation takes place at GHSV values of 500 to 5000 h ^-1 . GHSV stands for "gas hourly space velocity" (gas volume flow / catalyst volume).

The tungsten phosphates according to the invention having a tetragonal or cubic WO ₃ structure of the general formula (I) are preferably used as heterogeneous catalysts for the selective oxidation of n-butane to maleic anhydride or for the selective oxidation of ortho-xylene to phthalic anhydride.

Particularly preferred in the selective oxidation of n-butane to maleic anhydride n-butane concentrations in a range of 1 to 10 vol .-% are used. In addition, the gas stream in addition to n-butane may contain other gases, such as oxygen, water vapor and at least one inert gas. In this case, the oxygen concentration may be in a range from 2 to 25% by volume, the water vapor concentration in a range from 1 to 60% by volume and the concentration of the optionally at least one inert gas in a range from 0 to 97% by volume, so that the total amount of all gases is 100 vol.%. The intergass may be noble gases and / or nitrogen.

Particularly preferably, in the selective oxidation of ortho-xylene to phthalic anhydride, ortho-xylene concentrations ranging from 0.1 to 10% by volume are used. In addition, the gas stream in addition to ortho-xylene may contain other gases, such as air and at least one inert gas. In this case, the air concentration may be in a range of 15 to 30% by volume and the concentration of the at least one inert gas in a range of 60 to 84.9% by volume, so that the total amount of all gases is 100% by volume. The inert gases may be noble gases and / or nitrogen.

Another object of the invention is a catalyst A obtainable by heating the solid F2 according to steps i) to iii) from the inventive method to a temperature of 300 ° C to 600 ° C for 1 h to 48 h.

Advantageously, by heating, the oxidation states of the metals in the tungsten phosphate (solid F2) can be adjusted in a targeted manner. Also, the amount of metaphosphate melt on the surface of the nanocrystalline polynuclear polystyrene phosphate particles resulting from the heating of F2 can be influenced as well as the particle size.

• i) eine homogene Lösung umfassend mindestens eine Wolframverbindung, mindestens ein Oxidationsmittel, mindestens eine Phosphorverbindung, mindestens ein Additiv und gegebenenfalls ein Lösungsmittel, bereitgestellt wird,
• ii) das Reaktionsgemisch aus Schritt i) unter Erhalt eines Feststoffes F1 behandelt wird,
• iii) der Feststoff F1 auf eine Temperatur in einem Bereich von 300°C bis 600°C unter Erhalt des Feststoffes F2 erhitzt wird.

Preferably, the solid F2 is obtainable by

• i) a homogeneous solution comprising at least one tungsten compound, at least one oxidizing agent, at least one phosphorus compound, at least one additive and optionally a solvent, is provided,
• ii) the reaction mixture from step i) is treated to give a solid F1,
• iii) the solid F1 is heated to a temperature in the range of 300 ° C to 600 ° C to obtain the solid F2.

Another object of the invention is a catalyst B obtainable by heating the solid F2 according to steps i) to iii) from the inventive method at a temperature of 400 ° C to 600 ° C for 1 day to 30 days.

Advantageously, by heating, the oxidation states of the metals in the tungsten phosphate (solid F2) can be adjusted in a targeted manner. Also, the amount of the meta-phosphate melt on the surface of the nanocrystalline polynary polystyrene phosphate particles resulting from the heating of F2 can be influenced as well as the particle size.

• i) eine homogene Lösung umfassend mindestens eine Wolframverbindung, mindestens ein Oxidationsmittel, mindestens eine Phosphorverbindung, mindestens ein Additiv und gegebenenfalls ein Lösungsmittel, bereitgestellt wird,
• ii) das Reaktionsgemisch aus Schritt i) unter Erhalt eines Feststoffes F1 behandelt wird,
• iii) der Feststoff F1 auf eine Temperatur in einem Bereich von 300°C bis 600°C unter Erhalt des Feststoffes F2 erhitzt wird.

Preferably, the solid F2 is obtainable by

• i) a homogeneous solution comprising at least one tungsten compound, at least one oxidizing agent, at least one phosphorus compound, at least one additive and optionally a solvent, is provided,
• ii) the reaction mixture from step i) is treated to give a solid F1,
• iii) the solid F1 is heated to a temperature in the range of 300 ° C to 600 ° C to obtain the solid F2.

All the above-mentioned embodiments and preferred embodiments can be freely combined with each other, unless the context clearly contradicts.

The term "comprising", "comprising" or "composed of" may more preferably also include the term "consist" or "consisting of".

Further advantages and advantageous embodiments of the subject invention are illustrated by the drawings and explained in the following description. It should be noted that the drawings have only descriptive character and are not intended to limit the invention in any way. Show it:

1 : In 1 the X-ray powder diffraction pattern of the compound (W _0.75 P _0.25 ) O _2.875 (phase A1) is shown (guinine technique, Cu-Kα ₁ , without background correction) of (W _0.75 P _0.25 ) O _2.875 (a). Simulation with matched lattice parameters (a = 5.294 (2) Å, c = 7.688 (4) Å) based on the crystal structure of tetragonal WO ₃ ( T. Vogt, PM Woodward, BA Hunter, J. Solid State Chem. 1999, 144, 209 ), statistical occupation of the metal layer with W / P and statistical distribution of the oxygen vacancies (b)).

2 : In 2 the X-ray powder diffraction pattern of the compound (W _0.50 P _0.50 ) O _2,750 (phase A2) is shown (guinine technique, Cu-Kα ₁ , without background correction) of (W _0.50 P _0.50 ) O _2,750 (a ). Simulation based on the crystal structure of cubic WO ₃ {ReO ₃ structure type ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 )} in space group pm 3 m with adapted lattice parameter (a = 3.773 (6) Å), statistical occupation of the metal layer with W / P and statistical distribution of the oxygen vacancies (b)).

3 : In 3 the X-ray powder diffraction pattern of the compound (V ^III _0.167 W _0.333 P _0.50 ) O _2.5 (phase A3) is shown (guinine technique, Cu-Kα ₁ , without background correction) of (V ^III _0.167 W _0.333 P _0.50 ) O _2.5 ☐ _0.5 {□ stands for oxygen vacancy based on the ReO ₃ structure type ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 )} (a). Simulation in room group pm 3 m with adapted lattice parameter (a = 3.7811 (3) Å), statistical occupation of the metal layer with V / W / P and statistical distribution of the oxygen vacancies (b)).

4 : In 4 is the Röngtenpulverdiffraktogramm the compound (V _0.167 W _0.333 P _0.50) O _{2.5 + δ} (phase A4) represented (Guiniertechnik, Cu-Ka _1; without background correction) of (V _{0.167 0.333} W ^VI P P _{0, 50} ) O _{2.5 + δ} with δ = 0.167 and V (+ V) after annealing in air at 450 ° C (24 h), 550 ° C (24 h) and 600 ° C (144 h) (a). Simulation based on the crystal structure of tetragonal WO ₃ ( T. Vogt, PM Woodward, BA Hunter, J. Solid State Chem. 1999, 144, 209 ) in space group P4 / ncc with matched lattice parameters (a = 5.325 (2) Å, c = 7.58 (2) Å), random occupation of the metal layer with V / W / P and statistical distribution of oxygen vacancies (b)).

5 : In 5 the X-ray powder diffraction pattern of the compound (V _0.167 W _0.5 P _0.333 ) O _{2.5 + δ} (phase A5) is shown (guinine technique, Cu-Kα ₁ , without background correction) of (V _1/6 W _3/6 P _2/6 ) O _{2.5 + δ} (a). Simulation using the cubic ReO ₃ structure type ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207 121 ) with room group pm 3 m , adapted lattice parameter (a = 3.7744 (9) Å), statistical occupation of the metal layer with V / W / P and statistical distribution of the oxygen vacancies (b).

6 : In 6 the X-ray powder diffractogram of the compound Fe ^III _0.1 V _0.1 W ^VI _0.3 P ^V _0.5 ) O _{2.5 + δ} (phase A6) is shown (Guiniertechnik, Cu-Kα ₁ , without background correction) of (Fe _0.1 V _0.1 W _0.3 P _0.5 ) O _{2.5 + δ} (a). Simulation using the cubic ReO ₃ structure type ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ) with room group pm 3 m , adapted lattice parameter (a = 3.7732 (8) Å), statistical occupation of the metal layer with Fe / V / W / P and statistical distribution of the oxygen vacancies (b)).

7 : In 7 the X-ray powder diffraction pattern of the compound (Sb ^III _0.1 V _0.1 W ^VI _0.3 P ^V _0.5 ) O _{2.5 + δ} (phase A7) is shown (guinine technique, Cu-Kα ₁ , without background correction) of ( Sb _0.1 V _0.1 W _0.3 P _0.5 ) O _{2.5 + δ} (a). Simulation using the cubic ReO ₃ structure type ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ) with room group pm 3 m , adapted lattice parameter (a = 3.7664 (4) Å), statistical occupation of the metal layer with Sb / V / W / P and statistical distribution of the oxygen vacancies (b)).

The invention is further illustrated by the following examples.

Examples

A) Preparation of various novel compounds according to the invention

A1) Preparation of the new compound _{according to} the invention (W _0.75 P _0.25 ) O _2.875

In a 250 ml beaker, the starting materials (NH ₄ ) ₂ HPO ₄ (m = 356.76 mg corresponding to 2.70 mmol P, Merck, 64293 Darmstadt, Germany) and (NH ₄ ) ₆ W ₁₂ O ₃₉ xH ₂ O ( m = 1996.34 mg corresponding to 7.92 mmol W, x = 4.8, thermogravimetric determination as WO ₃ , Alfa Aesar GmbH, 76185 Karlsruhe, Germany) with about 15 ml of deionized water and 3.46 ml of 65% by weight. % HNO ₃ (Riedel De Haen AG, Germany). 1783.6 mg of glycine (corresponding to 23.76 mmol, Sigma Aldrich GmbH, Germany) were added to the solution within 2 min with stirring (stirring speed 120 min ^-1 ). The molar amount of the oxidant HNO ₃ was so dimensioned that with the glycine and the present ammonium ("fuels") complete combustion to H ₂ O, CO ₂ and molecular nitrogen can be carried out according to the following reaction equation. Smaller amounts of nitric acid lead to an incomplete combustion reaction, clearly in excess nitric acid is already lost in the subsequent evaporation, even before the ignition of the combustion reaction. 3/48 (NH ₄ ) ₆ W ₁₂ O ₃₉ · 4.8H ₂ O + ¼ (NH ₄ ) ₂ HPO ₄ + 9 / 4H ₅ NC ₂ O ₂ + 4.575HNO ₃ → (W _0.75 P _0.25 ) O _2,875 + 18 / 4CO ₂ + 3,85N ₂ + 9,696H ₂ O

The solution of the reactants was evaporated with stirring (stirring speed 120 min ^-1 ) on a hotplate (magnetic stirrer RH Basic 2, IKA, 79219 Staufen, Germany) at a temperature of 100 ° C for drying (T-measurement was carried out with the aid of a mercury thermometer). The beaker with the dry residue was then introduced to ignite the combustion reaction in a preheated to 400 ° C convection muffle furnace (model L5 / 11 temperature controller B170, Fa. Nabertherm GmbH, 28865 Lilienthal, Germany) and left there for 10 min. The powdered combustion product was transferred to a silica glass boat and heated in air in the same forced air muffle furnace at 500 ° C for 72 hours and then at 600 ° C for another 72 hours.

An X-ray powder diffractogram was recorded from the powder thus obtained (IP Guinier camera G670, HUBER, 83253 Rimsting, Germany, Cu-Kα ₁ radiation, Ge monochromator, λ = 1.54059 Å, 1 ).
Table 1 shows the indexing based on these Guinieraufnahmen on the basis of the crystal structure of tetragonal WO ₃ ( T. Vogt, PM Woodward, BA Hunter, J. Solid State Chem. 1999, 144, 209 ). The intensity calculation was performed in the space group P4Incc with matched lattice parameters (a = 5.294 (2) Å, c = 7.688 (4) Å) and a statistical occupation of the metal layer with W / P and statistical distribution of the oxygen vacancies. Table 1 H k l 4θ _calculate. ^a) 4θ _monitored. ^a) l _calculated . ^a) I _observed. ^a) 0 0 2 46.26 46.33 460 551 1 1 0 47.57 47.48 1000 1000 1 0 2 57.40 57.34 174 61 1 1 2 66.83 66.83 408 559 2 0 2 82.86 82.79 131 209 2 1 2 89.97 90.06 109 29 0 0 4 94.54 94.55 64 43 2 2 0 97.37 97.30 212 131 1 0 4 101.01 100.94 139 51 1 1 4 107.18 107.15 108 92 2 2 2 109.12 109.27 185 213 2 0 4 118.86 118.95 49 59 3 1 2 120.67 120.60 207 140 2 1 4 124.43 124.40 167 29 ^a) Calculate the values _4θ. follow from the adjusted grid parameters; 4θ _monitored. are read from the powder diffractogram. l _calculated. and I _observed. are normalized to 1000.

A2) Preparation of the new compound according to the invention (W _0.50 P _0.50 ) O _2,750

The preparation was carried out as in Example A1 using the following educts:
776.5 mg (NH ₄ ) ₂ HPO ₄ (corresponding to 5.88 mmol P, Merck, 64293 Darmstadt, Germany)
1482.1 mg (NH ₄ ) ₆ W ₁₂ O ₃₉ .xH ₂ O (corresponding to 5.88 mmol W, x = 4.8, thermogravimetric determination as WO ₃ , Alfa Aesar GmbH, 76185 Karlsruhe, Germany)
1324.2 mg glycine (corresponding to 17.64 mmol, Sigma Aldrich GmbH, Germany)
3.46 ml HNO ₃ (65% by weight, corresponding to 50 mmol, Riedel De Haen AG, Germany)
20 ml of deionized water.

From the powder thus obtained, a X-ray powder diffractogram was recorded (IP Guinier camera G670, HUBER, 83253 Rimsting, Germany, Cu-Kα ₁ radiation, Ge monochromator, λ = 1.54059 Å, 2 ).
Table 2 shows the indexing on the basis of these Guinieraufnahmen on the basis of the crystal structure of cubic WO ₃ ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ). The intensity calculation was in space group pm 3 m with adapted lattice parameter (a = 3.773 (6) Å), statistical occupation of the metal layer with W / P and statistical distribution of the oxygen vacancies. Table 2 ^H k l 4θ _calculate. ^a) 4θ _monitored. ^a) l _calculated. ^a) I _observed. ^a) 1 0 0 47.11 47.29 1000 1000 1 1 0 67.12 66.97 421 589 1 1 1 82.82 82.80 72 204 2 0 0 96.38 97.06 230 97 2 1 0 108.63 108.99 433 246 2 1 1 120.00 120.41 205 156 2 2 0 141.06 140.33 173 70

A3) Preparation of the novel compound _{according to} the invention (V ^III _0.167 W _0.333 P _0.50 ) O _2.5

The preparation was carried out as in Example A1 using the following educts:
792.39 mg (NH ₄ ) ₂ HPO ₄ (corresponding to 6.00 mmol P, Merck, 64293 Darmstadt, Germany)
231.60 mg NH ₄ VO ₃ (corresponding to 1.98 mmol V, Chempur, 76137 Karlsruhe, Germany)
1013.30 mg (NH _{4) 6} W ₁₂ O ₃₉ · xH ₂ O (corresponding to 4.02 mmol W, x = 4.8, thermogravimetric determination as WO _3, Alfa Aesar GmbH, 76185 Karlsruhe, Germany)
1324.2 mg glycine (corresponding to 17.64 mmol, Sigma Aldrich GmbH, Germany)
3.46 ml HNO ₃ (65% by weight, corresponding to 50 mmol, Riedel De Haen AG, Germany)
20 ml of deionized water

After drying on the hot plate, which was carried out as described in Example A1, the material was ignited in a muffle furnace, in contrast to A1 not at 400 ° C but at 500 ° C. The further thermal treatment was carried out initially in air at 500 ° C for 5 h, then, to adjust the oxidation state + III of vanadium, in a stream (p _ges = 1 bar) of hydrogen saturated with hydrogen first at 500 ° C for 24 h and finally at 600 ° C for 60 h.

From the blue-black powder obtained in this way, a X-ray powder diffractogram was recorded (IP Guinier camera G670, HUBER, 83253 Rimsting, Germany, Cu-Kα ₁ radiation, Ge monochromator, λ = 1.54059 Å, 3 ).
Table 3 shows the indexing on the basis of these Guinieraufnahmen on the basis of the crystal structure of cubic WO ₃ ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ). The intensity calculation was in space group pm 3 m with adapted lattice parameter (a = 3.7811 (3) Å), statistical occupation of the metal layer with W / P and statistical distribution of the oxygen vacancies. Table 3 H k l 4θ _calculate. ^a) 4θ _monitored. ^a) I _calculate. ^a) I _{'m watching} ^a) 1 0 0 47.15 47.01 1000 1000 1 1 0 67.16 67.15 330 450 1 1 1 82.88 82.81 33 110 2 0 0 96.45 96.52 248 142 2 1 0 108.71 108.72 414 221 2 1 1 120.10 120.09 162 112

A4) Preparation of the novel compound _{according to} the invention (V _0.167 W _0.333 P _0.50 ) O _{2.5 + δ}

The preparation was carried out as in Example A1, however, in a 400 ml beaker using the following educts:
3565.60 mg (NH ₄ ) ₂ HPO ₄ (corresponding to 27.0 mmol P, Merck, 64293 Darmstadt, Germany)
1052.80 mg NH ₄ VO ₃ (corresponding to 9.0 mmol V, Chempur, 76137 Karlsruhe, Germany)
4537.32 mg (NH ₄ ) ₆ W ₁₂ O ₃₉ .xH ₂ O (corresponding to 1.5 mmol W, x = 4.8, thermogravimetric determination as WO ₃ , Alfa Aesar GmbH, 76185 Karlsruhe, Germany)
1830.0 mg glycine (corresponding to 24.38 mmol, Sigma Aldrich GmbH, Germany)
8.0 ml of HNO ₃ (65% by weight, corresponding to 125.6 mmol, Riedel De Haen AG, Germany)
40 ml of deionized water

After drying on the hot plate, which was carried out as described in Example A1, the material was ignited in a preheated muffle furnace at 450 ° C. The further thermal treatment was carried out in air at 450 ° C (24 h), 550 ° C (24 h) and 600 ° C (144 h).

From the greenish-yellow powder thus obtained, a X-ray powder diffractogram was recorded (IP Guinier camera G670, HUBER, 83253 Rimsting, Germany, Cu-Kα ₁ radiation, Ge monochromator, λ = 1.54059 Å, 4 ).
The table shows the indexing based on these Guinieraufnahmen on the basis of the crystal structure of tetragonal WO ₃ ( T. Vogt, PM Woodward, BA Hunter, J. Solid State Chem. 1999, 144, 209 ). The intensity calculation was carried out in space group P4lncc with matched lattice parameters (a = 5.325 (2) Å, c = 7.58 (2) Å), random occupation of the metal layer with V / W / P and statistical distribution of the oxygen vacancies.

A5) Preparation of the new compound _{according to} the invention (V _0.167 W _0.5 P _0.333 ) O _{2.5 + δ}

The preparation was carried out as in Example A1 using the following educts:
1434.1 mg (NH ₄ ) ₂ HPO ₄ (corresponding to 10.86 mmol P, Merck, 64293 Darmstadt, Germany)
635.5 mg NH ₄ VO ₃ (corresponding to 5.43 mmol V. Chempur, 76137 Karlsruhe, Germany)
4217.9 mg (NH _{4) 6} W ₁₂ O ₃₉ · xH ₂ O (corresponding to 1.36 mmol W, x = 9.37, thermogravimetric determination as WO _3, Alfa Aesar GmbH, 76185 Karlsruhe, Germany)
4898.1 mg glycine (corresponding to 65.25 mmol, Sigma Aldrich GmbH, Germany)
9.7 ml of HNO ₃ (65% by weight, corresponding to 138.64 mmol, Riedel De Haen AG, Germany)
40 ml of deionized water

After drying on the hot plate, which was carried out as described in Example A1, the dry residue was ignited in a muffle furnace at 400 ° C. The further thermal treatment was carried out in air at 500 ° C (48 h) and 600 ° C (24 h).

From the thus obtained light brownish-gray powder was added to a Röngtenpulverdiffraktogramm (IP Guinier camera G670, Fa. HUBER, 83253 Rimsting, Germany, Cu-Ka ₁ radiation, Ge-monochromator, λ = 1.54059 Å, 5 ).
Table 5 shows the indexing on the basis of these Guinieraufnahmen on the basis of the crystal structure of cubic WO ₃ ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ). The intensity calculation was in space group pm 3 m with adjusted lattice parameter (a = 3.7744 (9) Å), statistical occupation of the metal layer with V / W / P and statistical distribution of the oxygen vacancies. Table 5 H k l 4θ _calculate. ^a) 4θ _monitored. ^a) l _calculated. ^a) I _observed. ^a) 1 0 0 47.10 47.05 1000 1000 1 1 0 67.10 67.04 434 485 1 1 1 82.80 82.74 77 115 2 0 0 96.35 96.41 227 155 2 1 0 108.60 108.67 434 246 2 1 1 119.97 120.05 209 126 2 2 0 141.02 140.93 170 59

A6) Preparation of the new compound according to the invention (Fe ^III _0.1 V _0.1 W ^VI _0.3 P ^V _0.5 ) O _{2.5 + δ}

The preparation was carried out as in Example A1, however, in a 500 ml beaker using the following starting materials:
3169.4 mg (NH ₄ ) ₂ HPO ₄ (corresponding to 24.0 mmol P, Merck, 64293 Darmstadt, Germany)
701.89 mg NH ₄ VO ₃ (corresponding to 6.0 mmol V, Chempur, 76137 Karlsruhe, Germany)
904.98 mg FePO ₄ (corresponding to 6.0 mmol Fe, synthesis according to R. Glaum, Dissertation, University of Gießen 1990)
4537.52 mg (NH _{4) 6} W ₁₂ O ₃₉ · xH ₂ O (corresponding to 18.0 mmol W, x = 4.8, thermogravimetric determination as WO _3, Alfa Aesar GmbH, 76185 Karlsruhe, Germany)
2595 mg glycine (corresponding to 34.58 mmol, Sigma Aldrich GmbH, Germany)
16.0 ml HNO ₃ (65% by weight, corresponding to 251.2 mmol, Riedel De Haen AG, Germany)
40 ml of deionized water

After drying on the hot plate, which was carried out as described in Example A1, the dry residue was ignited in a muffle furnace at 400 ° C. The further thermal treatment was carried out in air at 450 ° C (24 h), 550 ° C (24 h) and 600 ° C (24 h).

From the pale greenish-gray powder obtained in this way, a X-ray powder diffractogram was recorded (IP Guinier camera G670, HUBER, 83253 Rimsting, Germany, Cu-Kα ₁ radiation, Ge monochromator, λ = 1.54059 Å, 6 ).
Table 6 shows the indexing on the basis of these Guinieraufnahmen on the basis of the crystal structure of cubic WO ₃ ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ). The intensity calculation was in space group pm 3 m with adjusted lattice parameter (a = 3.7732 (8) Å), statistical occupation of the metal layer with Fe / V / W / P and statistical distribution of the oxygen vacancies. Table 6 H k l 4θ _calculate. ^a) 4θ _monitored. ^a) l _calculated. ^a) l _obs. ^a) 1 0 0 47.12 47.15 1000 1000 1 1 0 67.12 67.09 317 450 1 1 1 82.83 82.81 29 104 2 0 0 96.39 96.47 251 143 2 1 0 108.64 108.68 410 222 2 1 1 120.01 119.95 155 147 a) Calculate the values _4θ. follow from the adjusted grid parameters; 4θ _monitored. are read from the powder diffractogram. l _calculated. and I _observed. are normalized to 1000.

A7) Preparation of the novel compound according to the invention (Sb ^III _0.1 V _0.1 W ^VI _0.3 P ^V _0.5 ) O _{2.5 + δ}

The preparation was carried out as in Example A1 using the following educts:
5162.2 mg (NH ₄ ) ₂ HPO ₄ (corresponding to 39.10 mmol P, Merck, 64293 Darmstadt, Germany)
914.6 mg NH ₄ VO ₃ (corresponding to 7.82 mmol V, Chempur, 76137 Karlsruhe, Germany)
1139.6 mg Sb ₂ O ₃ (corresponding to 3.91 mmol Sb, Sigma Aldrich GmbH, Germany)
5912.0 mg (NH _{4) 6} W ₁₂ O ₃₉ · xH ₂ O (corresponding to 1.96 mmol W, x = 4.8, thermogravimetric determination as WO _3, Alfa Aesar GmbH, 76185 Karlsruhe, Germany)
8803.2 mg glycine (corresponding to 117.27 mmol, Sigma Aldrich GmbH, Germany)
18.8 ml of HNO ₃ (65% by weight, corresponding to 269.73 mmol, Riedel De Haen AG, Germany)
40 ml of deionized water

After drying on the hot plate, which was carried out as described in Example A1, the dry residue was ignited in a muffle furnace at 400 ° C. The further thermal treatment was carried out in air at 500 ° C (48 h) and 600 ° C (48 h).

From the thus obtained light brownish-gray powder was added to a Röngtenpulverdiffraktogramm (IP Guinier camera G670, Fa. HUBER, 83253 Rimsting, Germany, Cu-Ka ₁ radiation, Ge-monochromator, λ = 1.54059 Å, 7 ).
Table 7 shows the indexing on the basis of these Guinieraufnahmen on the basis of the crystal structure of cubic WO ₃ ( K. Meisel, Z. Anorg. Gen. Chem. 1932, 207, 121 ). The intensity calculation was in space group pm 3 m with adjusted lattice parameter (a = 3.7664 (4) Å), statistical occupation of the metal layer with Sb / V / W / P and statistical distribution of the oxygen vacancies. Table 7 ^H k l 4θ _calculate. ^a) 4θ _monitored. ^a) l _calculated. ^a) I _observed. ^a) 1 0 0 47.2 47.09 1000 1000 1 1 0 67.24 67.21 390 481 1 1 1 83.0 82.95 58 83 2 0 0 96.56 96.58 232 123 2 1 0 108.84 108.89 421 219 2 1 1 120.24 120.26 188 115 2 2 0 141.36 141.35 172 48 a) Calculate the values _4θ. follow from the adjusted grid parameters; 4θ _monitored. are read from the powder diffractogram. l _calculated. and l _obs. are normalized to 1000.

B) Catalytic Testing of the Various Novel Compounds of the Invention

B1) Testing for the selective oxidation of n-butane to maleic anhydride

The performance tests of the various catalysts were carried out in a high-throughput test system with parallel flow reactor systems from hte GmbH (69123 Heidelberg, Germany). The plant was specially designed for the oxidation of butane to maleic anhydride and consists of a gas metering with evaporators for liquids, a furnace unit with 9 individually heatable reactors (8 reactors for catalysts, a reactor filled with inert material for the determination of the educt gas mixture), and an analytical part, which determines the chemical composition of the educt and product mixture. The whole system is fully automated.

The gas metering is designed for GHSV (gas hourly space velocity: GHSV = gas volume flow / catalyst volume) of 500 to 5000 h ^-1 . The butane concentration can be varied from 1 to 10% by volume. The oxygen concentration can be varied from 2 to 25% by volume. The water vapor concentration can be varied from 1 to 60% by volume. The reactions are always carried out at atmospheric pressure. The reactors consist of stainless steel tubes with an outer diameter of 18 mm and an inner diameter of 10 mm. The reactors contain stainless steel immersion sleeves with an outer diameter of 1/8 inch into which three-point thermocouples are placed to monitor the temperature of the catalyst beds. The temperature of the reactors can be varied by means of an electric heater from 250 to 550 ° C. The analysis consists of two gas chromatographs (GC 7890A, Agilent Technologies GmbH, 76337 Waldbronn, Germany), which are equipped with flame ionization detectors and thermal conductivity sensors, and can take gas samples from the gas streams of the individual reactors via sample loop valves online. All lines from the reactor to the gas chromatograph are fully heated (electronically controlled to 200 ° C).

In a typical test, 1 ml each of a pressed, split and sieved catalyst (100 to 200 μm grain size) is used per reactor. For pressing the catalyst powder, which is fine in the original state, a laboratory press with a press tool, which is customary in spectroscopy laboratories, is used (2.5 min at a contact pressure of 2 t on a 12 mm stamp). For splitting an agate mortar is used. Sieving is carried out by means of analysis sieves made of stainless steel. The catalyst bed is fixed in the reactor tube by a bottom and cover of inert material (calcined steatite, grain size 800 to 1000 microns, CeramTec GmbH, 73207 Plochingen, Germany). The reactors are installed in the oven at room temperature. The GHSV is set to 2000 h ^-1 . The catalysts are heated in a mixture of 5 vol .-% oxygen in nitrogen up to 250 ° C. Then the reaction mixture is changed to 2% by volume of butane, 3% by volume of water vapor, 3% by volume of argon (as internal standard for the analysis) in nitrogen. The temperature of the reactors is set at 375 ° C. After 30 minutes of waiting the actual test starts. 5 measurements per reactor are carried out with the gas chromatographs. Then the temperature of the reactors is raised by 25 ° C and another 5 measurements are made. The temperature of the reactors is gradually increased from 375 ° C to 450 ° C, and then gradually lowered again to 375 ° C. This makes it possible to make a statement about the thermal stability and the deactivation of catalysts. Overall, the test duration is typically 7 days. After the test, the reactors are cooled to room temperature in a mixture of 5 vol.% Oxygen in nitrogen. The catalysts are removed, separated from the steatite and their state after catalysis tested by various analysis methods (eg nitrogen physisorption, X-ray diffractometry).

Sales and selectivities are calculated from the concentrations determined by gas chromatography (averaged over the 5 analyzes measured per temperature step). The conversion (U ^C4 ) is determined from the butane concentrations (c (butane)), measured at the reactor outlet of the individual reactors (R _i ), and the butane concentration, measured at the outlet of the reactor filled with inert material (R ₉ ), which is the input gas of all reactors Equivalent to the measured concentrations of the internal standard argon (c (Ar)) according to Equation 1. Here, c (Ar) _R9 / c (Ar) _{Ri represents} the volume change factor caused by the reactions. The selectivities (S. (by-product)) represent the portion of the converted butane, which is obtained as the respective by-product ((with respect to the number of carbon atoms N _C) of by-product and butane), according to equation 2. as a possible by-products are butenes, acrylic acid, propionic acid, Acetic acid, acrolein, acetaldehyde, propane, propene, ethane, ethene, carbon monoxide and carbon dioxide. There are no unassigned peaks in the gas chromatographic spectra. The selectivity to maleic anhydride (S ^MSA ) is calculated according to equation 3 from the sum of the selectivities of all by-products.

Table 1 contains the catalytic test results for the reaction of n-butane to maleic anhydride for the novel compounds of the invention. Table 1 catalyst 375 ° C 400 ° C 425 ° C 450 ° C U ^C4 l% S ^MSA 1 mol% U ^C4 l% S ^MSA 1 mol% U ^C4 l% S ^MSA 1 mol% U ^C4 l% S ^MSA 1 mol% A3 4.0 87.4 7.0 62.7 12.8 59.3 21.9 20.6 A5 5.0 36.7 10.3 47.7 17.0 40.6 29.2 39.7 A6 5.4 66.8 10.3 52.9 17.2 52.2 28.4 49.2 A7 <1.0 - 1.7 72.2 2.7 49.0 6.3 55.9

B2) Testing for the selective oxidation of o-xylene to pthalic anhydride

The catalytic testing for the selective oxidation of o-xylene to Pthalsäureanhydrid on the novel compound A5 according to the invention was carried out in a microreactor as in Chem. Ing. Techn. 2014, 86, pp. 1-5 described. The composition of the reaction gas mixture was as follows:
2.0% by volume o-xylene
20.4% by volume of air
75.9% by volume N ₂
at a total input _gas flow of 100 g _o-xylene / Nm ³ and 4 Nm ³ air

The difference to 100% by volume consisted of nitrogen. The analysis of the product gas flow was carried out by gas chromatographic analysis (Agilent Technologies GmbH, 76337 Waldbronn, Germany, Model 6890N, FID with HP5 column, WLD with CTR column, Supelco Poropack QS 80/100 columns). The selectivity of the formation of pthalic anhydride (S ^PSA in mol%) is understood in this document to mean: S ^PSA = molar - xylene reacted to form phthalic anhydride / molar - xylene totally reacted · 100 (The conversion figures are each based on a single pass of the reaction gas mixture through the fixed catalyst bed).

The conversion of U ^C8 to o-xylene (mol%) is correspondingly defined as: U ^C4 = molar number of reacted o - xylene / number of moles of o - xylene used · 100

Table 2 contains the catalytic test results for the conversion of o-xylene to phthalic anhydride for a novel compounds of this invention. Table 2 example T * [° C] GHSV ** [h ^-1 ] U ^C8 [%] S ^PSA [mol%] A5 450 2600 21.14 37.15 * T = reactor temperature
** GHSV = gas hourly space velocity = gas volume / catalyst volume per hour

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

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• Chem. Ing. Techn. 2014, 86, pp. 1-5 [0101]

Claims (17)

Tungsten phosphates of the ReO ₃ structural family of the general formula (I): (M _{a M'b} W _c P _d ) O _{3 -x} (I) wherein M is at least one member selected from the group consisting of Sc, Ti, V, Cr, Fe, Nb, Mo, In, Sb or mixtures thereof, M 'is at least one member selected from the group consisting of Sc , Ti, V, Cr, Fe, Nb, Mo, In, Sb or mixtures thereof, a is a value of ≥ 0 to ≦ 0.30, b is a value of ≥ 0 to ≦ 0.30, c is a value of ≥ 0 , 30 to ≤ 0.93, d has a value of ≥ 0 to ≤ 0.5, and x has a value of ≥ 0 to ≤ 0.5, where M is other than M '. Tungsten phosphates according to claim 1, wherein a + b + c + d = 1. Tungsten phosphates according to claim 1 or 2, wherein the tungsten phosphates have a tetragonal or cubic WO ₃ structure. Tungsten phosphates according to any one of claims 1 to 3, wherein a and / or b have a value of ≥ 0.01 to ≤ 0.3. Tungsten phosphates according to any one of claims 1 to 4, wherein their value is from ≥ 0.01 to ≤ 0.5. Tungsten phosphates according to one of claims 1 to 5, wherein the lattice parameters of the cubic unit cell for the lengths a1, b1 and c1 have the values for a1 = b1 = c1 = 3.78 ± 0.1 Å and the values for the angles α, β, γ have the values α = 90 °, β = 90 °, γ = 90 ° or for the tetragonal unit cells the lengths a1, b1 and c1 have the values for a1 = b1 = 5.30 ± 0.1 Å and c1 = 7.69 ± 0.1 Å and wherein the values for the angles α, β, γ have the values α = 90 °, β = 90 °, γ = 90 °. Tungsten phosphates according to any one of claims 1 to 6, having a powder X-ray diffraction pattern with diffraction reflections at lattice spacings d selected from the group consisting of d ₁ = 3.78 ± 0.02 angstroms (Å), d ₂ = 2.67 ± 0 , 02 Å, d ₃ = 2.18 ± 0.02 Å, d ₄ = 1.88 ± 0.02 Å, d ₅ = 1.68 ± 0.02 Å and d ₆ = 1.54 ± 0.02 Å. A process for preparing tungsten phosphates of the ReO ₃ structural family of the general formula (I) according to any one of claims 1 to 7, comprising the steps: i) providing a homogeneous solution comprising at least one tungsten compound, at least one oxidizing agent, at least one phosphorus compound and at least one additive ii) treating the reaction mixture of step i) to obtain a solid F1, iii) heating the solid F1 to a temperature in the range of 300 ° C to 600 ° C to obtain the solid F2, iv) heating the solid F2 to one Temperature in a range of 300 ° C to 800 ° C under various gas atmospheres. A method according to claim 8, wherein the oxidizing agent is nitric acid. A method according to claim 8 or 9, wherein the tungsten compound is (NH ₄ ) ₂ W ₁₂ O ₃₉ hydrate. The method according to any one of claims 8 to 10, wherein the gas atmosphere is an oxygen atmosphere of either air having an oxygen partial pressure p (O ₂ ) in a range of 0.1 to 0.4 bar absolute or argon having an oxygen partial pressure p (O ₂ ) in in a range of 10 ^-6 to 10 ^-4 bar absolute. The method according to any one of claims 8 to 11, wherein the gas atmosphere is a hydrogen atmosphere of hydrogen with oxygen, wherein the oxygen partial pressure (O ₂ ) is in a range of 10 ^-31 to 10 ^-22 bar absolute in a temperature range of 500 ° C to 800 ° C and the total pressure of oxygen and hydrogen 1 bar. Use of the tungsten phosphates of the ReO ₃ structural family of the general formula (I) according to one of claims 1 to 7 as heterogeneous catalysts for carrying out chemical reactions. Use of the tungsten phosphates with a tetragonal or cubic WO ₃ structure of the general formula (I) according to claim 13 as heterogeneous catalysts for the selective oxidation of at least one hydrocarbon to an anhydride or from an aldehyde group to a carboxylic acid group. Using tungsten phosphates having a tetragonal or cubic WO ₃ structure of the general formula (I) according to claim 13 as heterogeneous catalysts for the selective oxidation of n-butane to maleic anhydride or to the selective oxidation of ortho-xylene to phthalic anhydride. Catalyst A obtainable by heating the solid F2 according to steps i) to iii) of claim 8 to a temperature of 300 ° C to 600 ° C for 1 h to 48 h. Catalyst B obtainable by heating the solid F2 according to steps i) to iii) of claim 8 at a temperature of 400 ° C to 600 ° C for 1 day to 30 days.

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