JP3502526B2 - Vanadium-phosphorus oxide, method for producing the same, catalyst for gas phase oxidation comprising the oxide, and method for partial gas phase oxidation of hydrocarbons - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel vanadium-phosphorus oxide having a specific X-ray diffraction pattern, a method for producing the same, a gas phase oxidation catalyst comprising the oxide, and a partial gas phase of hydrocarbons. It relates to an oxidation method.

[0002]

2. Description of the Related Art Conventionally, various studies have been conducted on vanadium-phosphorus oxides, and physical properties and applications of these oxides have been developed at the same time.
In particular, it is well known that vanadium-phosphorus-based oxides are effective for producing maleic anhydride by gas phase oxidation of hydrocarbons having 4 carbon atoms (C4 hydrocarbons) such as butane, butene and butadiene. It is also well known that the vanadium-phosphorus oxide catalytically active component is divanadyl pyrophosphate, which is a crystalline oxide having a composition of (VO) ₂ P ₂ O ₇ . This divanadyl pyrophosphate is a precursor of vanadyl monohydrogen orthophosphate (VOHPO ₄ ·.
0.5H ₂ O) is synthesized, the precursor is calcined, and the precursor is calcined under an inert gas called activation treatment or a mixed gas flow of a hydrocarbon gas such as butane and air and the precursor. From a topotactic transition from

N-butane, 1-butene, 2-butene, butadiene or a mixture thereof (in the present invention, these are collectively referred to as "C4 hydrocarbon") is vaporized in the presence of a vanadium-phosphorus catalyst. It is well known that maleic anhydride can be obtained by phase oxidation, and many improved vanadium-phosphorus-based catalysts and production methods have already been proposed.

As these improved vanadium-phosphorus catalysts, in addition to those specified by the preparation method thereof, there are also those specified by the X-ray diffraction peak pattern (JP-A-53-61588 and JP-A-56-41816). issue,
56-45815, 59-132938, JP-A-5-15781 and the like). In vanadium-phosphorus catalysts, vanadium in the near tetravalent state rather than pentavalent state is said to be preferable for the production of maleic anhydride (Japanese Patent Laid-Open No. 50-35088).
56-41816, etc.).

C using a vanadium-phosphorus catalyst
Some of them have improved reaction conditions when carrying out gas phase oxidation of tetrahydrocarbons (JP-A-61-191680 and 61-61).
No. 251678, etc.).

A method for producing a vanadium-phosphorus oxide as a catalyst for producing maleic anhydride is described in many documents other than the above-mentioned publication, for example,
B. K. Hodnett, ed. , Catalysis
Today, Vol. 1, No. 5 (1987).

However, when the conventional vanadium-phosphorus oxide is used as a catalyst for the production of maleic anhydride by vapor-phase oxidation, for example, vapor-phase oxidation of butane, its catalytic activity is insufficient and the temperature is relatively low. However, when the maleic anhydride is produced under industrially advantageous conditions, there is a problem that the yield of maleic anhydride is low. In addition, in conventional vanadium-phosphorus catalysts, the valence of vanadium fluctuates, and thus it may or may not be possible to produce a vanadium-phosphorus catalyst having initial catalytic performance, and as a result, the maleic anhydride yield There was also a very inconvenient problem in industrial practice where the rate varied depending on the catalyst lot.

[0008]

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of conventional vanadium-phosphorus oxide catalysts and to provide vanadium-phosphorus oxides suitable for a gas phase oxidation reaction. To provide.

Another object of the present invention is to provide a novel vanadium-phosphorus oxide having a specific X-ray diffraction pattern and a method for producing the same.

Still another object of the present invention is to provide a novel vanadium-phosphorus oxide which can be produced with good reproducibility in terms of catalytic performance.

Another object of the present invention is to provide a gas phase oxidation catalyst comprising the vanadium-phosphorus oxide.

Still another object of the present invention is to provide a partial gas phase oxidation method for hydrocarbons.

Another object of the present invention is to provide a method for producing maleic anhydride by partial gas phase oxidation of hydrocarbons having 4 carbon atoms.

[0014]

The above-mentioned objects are achieved by the following items (1) to (18).

(1) X-ray diffraction spectrum (anti-cathode Cu
-Kα), the diffraction angle 2θ (± 0.2 °) is 18.
5 °, 23.0 °, 28.4 °, 29.9 ° and 4
It has a main peak of 3.1 ° and a diffraction angle 2θ (± 0.
2 °) = Vanadium-phosphorus oxide having an intensity ratio of peaks at 23.0 ° and 28.4 ° within the following range.

0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0. 2 °) = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown.

[0017] (2) 0.35 ≦ I (23.0) / I (28.4) ≦ 0.65 The vanadium-phosphorus oxide according to (1) above, which is

[0018] (3) 0.4 ≦ I (23.0) / I (28.4) ≦ 0.6 The vanadium-phosphorus oxide according to (1) above, which is

(4) Vanadium / phosphorus (atomic ratio) is 1
The vanadium-phosphorus oxide according to (1) above, which has a ratio of /0.9 to 1 / 1.2.

(5) X consisting of reacting a tetravalent vanadium compound and a phosphorus compound in an organic solvent at a temperature in the range of 60 to 150 ° C. and calcining the resulting reaction product.
In the line diffraction spectrum (anti-cathode Cu-Kα), the diffraction angle 2θ (± 0.2 °) was 18.5 °, 23.0 °, 2
It has major peaks at 8.4 °, 29.9 ° and 43.1 °, and the intensity ratio of the peaks at diffraction angles 2θ (± 0.2 °) = 23.0 ° and 28.4 ° is in the following range. A method for producing a vanadium-phosphorus oxide having the property of being inside.

0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0. 2 °) = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown.

(6) Vanadium / phosphorus (atomic ratio) is 1
/0.9 to 1 / 1.2, The method for producing the vanadium-phosphorus oxide according to (5) above.

(7) The method for producing a vanadium-phosphorus oxide according to (5) above, wherein the reaction temperature is 80 to 140 ° C.

(8) Since the pentavalent vanadium compound is reduced in an organic solvent and then reacted with the phosphorus compound at a temperature in the range of 60 to 150 ° C., the resulting reaction product is calcined and then activated. In the X-ray diffraction spectrum (anticathode Cu-Kα) having diffraction angles 2θ (± 0.2 °) of 18.5 °, 23.0 °, 28.4 °, 29.9 ° and 43.1 °. It has one peak and the diffraction angle 2θ (±
0.2 [deg.]) = 23.0 [deg.] And 28.4 [deg.] Peak intensity ratio is within the following range.

0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 However, I (23.0) and I (28.4) are diffraction angles 2θ (± 0. 2 °) = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown.

(9) Vanadium / phosphorus (atomic ratio) is 1
/0.9 to 1 / 1.2, The method for producing the vanadium-phosphorus oxide according to (8) above.

(10) The method for producing a vanadium-phosphorus oxide as described in (8) above, wherein the reaction temperature is 80 to 140 ° C.

(11) X-ray diffraction spectrum (anticathode C
u-Kα), the diffraction angle 2θ (± 0.2 °) is 1
It has major peaks of 8.5 °, 23.0 °, 28.4 °, 29.9 ° and 43.1 ° and has a diffraction angle 2θ (±
0.2 °) = 23.0 ° and a gas phase oxidation catalyst containing a vanadium-phosphorus oxide having an intensity ratio of peaks at 28.4 ° within the following range.

0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0. 2 °) = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown.

[0030] (12) 0.35 ≦ I (23.0) / I (28.4) ≦ 0.65 The catalyst for gas phase oxidation according to (11) above.

[0031] (13) 0.4 ≦ I (23.0) / I (28.4) ≦ 0.6 The catalyst for gas phase oxidation according to (11) above.

(14) The catalyst for vapor phase oxidation according to (11), wherein the vanadium / phosphorus (atomic ratio) is 1 / 0.9 to 1 / 1.2.

(15) In the partial gas phase oxidation of hydrocarbons using a gas containing molecular oxygen, an X-ray diffraction spectrum (cathode Cu—Kα) as a catalyst has a diffraction angle of 2
θ (± 0.2 °) is 18.5 °, 23.0 °, 28.4
With major peaks at °, 29.9 ° and 43.1 °,
Vanadium having the property that the intensity ratios of the peaks at the diffraction angles of 23.0 ° and 28.4 ° are within the following ranges:
A partial gas phase oxidation method comprising using a phosphorus oxide.

0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 However, I (23.0) and I (28.4) are diffraction angles 2θ (± 0. 2 °) = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown.

(16) The partial vapor phase oxidation method according to the above (15), wherein the hydrocarbon is an aliphatic hydrocarbon having 3 to 5 carbon atoms.

(17) The partial vapor phase oxidation method according to (16), wherein the aliphatic hydrocarbon has 4 carbon atoms.

(18) The partial gas phase oxidation method according to the above (17), wherein the aliphatic hydrocarbon having 4 carbon atoms is butane, and the partial oxide is maleic anhydride.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The vanadium-phosphorus oxide according to the present invention has an diffraction angle 2θ (± 0.2 °) of 18.5 ° and 2 in the X-ray diffraction spectrum (cathode Cu-Kα).
It has major peaks of 3.0 °, 28.4 °, 29.9 ° and 43.1 °, and a diffraction angle 2θ (± 0.2 °) = 2.
The intensity ratio of the peaks at 3.0 ° and 28.4 ° is within the following range.

0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0.2), respectively. °) = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown.

In particular, the peak intensity ratio I (23.0)
/I(28.4) is 0.35 to 0.65, and further 0.
Those in the range of 4 to 0.6 are preferable.

The vanadium-phosphorus oxide according to the present invention has a very strong peak at a diffraction angle 2θ (± 0.2 °) = 28.4 as compared with the conventionally known vanadium-phosphorus oxide.
It is characterized by the point at °.

The vanadium-phosphorus oxide according to the present invention is manufactured as follows.

Step (1) According to the method of the present invention, first, a tetravalent vanadium compound and a phosphorus compound are reacted in an organic solvent at a temperature in the range of 60 to 150 ° C., or a pentavalent vanadium compound is reacted. Is reduced and subsequently reacted with a phosphorus compound at a temperature in the range of 60 to 150 ° C. In particular, the latter method of using the pentavalent vanadium compound as a starting material is preferably used.
Therefore, first, a method of using a pentavalent vanadium compound as a starting material will be described.

According to this method, first, a pentavalent vanadium compound is reduced and dissolved in an organic solvent. It is considered that pentavalent vanadium is in the range of +3.9 to 4.1 by this reduction treatment.

The organic solvent of the present invention means one having a function as a reducing agent capable of reducing a pentavalent vanadium compound and a function as a reaction solvent, and any solvent having these functions is used. can do. Representative examples of this organic solvent include benzyl alcohols such as benzyl alcohol, and single or plural benzyl alcohols such as methylbenzyl alcohol, dimethylbenzyl alcohol, ethylbenzyl alcohol, and anise alcohol.
The benzyl alcohol derivative substituted by the C1-C3 alkyl group or alkoxy group can be mentioned.
Of these, benzyl alcohol is particularly preferably used.

In addition, as long as the reducing function of benzyl alcohol is not impaired, methanol, ethanol, n
-Propanol, isopropanol, n-butanol,
Aliphatic alcohols such as isobutanol and amyl alcohol; aromatic aldehydes such as benzaldehyde, tolualdehyde, dimethylbenzaldehyde and anisaldehyde can also be used in combination.

The pentavalent vanadium compound of the present invention means 5
It means an organic or inorganic compound containing a valent vanadium, and representative examples thereof include vanadium pentoxide and metavanadate, such as ammonium metavanadate. Of these, vanadium pentoxide is preferably used.

The phosphorus compound of the present invention means an organic or inorganic compound containing phosphorus, and typical examples thereof include orthophosphoric acid, pyrophosphoric acid, phosphorous acid, polyphosphoric acid and phosphorus pentoxide. it can. Of these, about 9
9% (98-101%) orthophosphoric acid is preferably used.

Therefore, according to a preferred embodiment of the present invention, vanadium pentoxide is added to benzyl alcohol and then heated at 80 to 150 ° C., preferably 100 to 130 ° C. with stirring to make the solution dark blue. The vanadium is reduced until the vanadium is completely dissolved in benzyl alcohol. It is considered that vanadium is in the range of +3.9 to 4.1 as described above due to this reduction treatment. Next, a solution prepared by dissolving orthophosphoric acid in benzyl alcohol is added to the above reduced vanadium solution, and the reaction is carried out by stirring at a temperature in the range of 60 to 150 ° C, preferably 80 to 140 ° C.

In the above reduction treatment, the treatment temperature is 80 ° C.
If it is lower, the reduction of the vanadium compound does not proceed, or the treatment takes a long time. On the other hand, when the treatment time exceeds 150 ° C., the oxidation of the organic solvent proceeds, and further the condensation may occur, which may make it difficult to separate the organic solvent and the produced oxide. In any case, the reduction treatment is performed at 80 to 150 ° C., preferably 1
By carrying out at 00 to 130 ° C., a vanadium-phosphorus-based oxide having the above X-ray diffraction spectrum pattern and peak intensity ratio can be obtained. The reduction treatment time is until the solution turns black blue and vanadium is completely dissolved, but 2 to 10 hours is usually sufficient.

Regarding the ratio of vanadium compound and phosphorus compound used, vanadium / phosphorus (atomic ratio) is 1
/0.9-1/1.2, preferably 1 / 0.95-1 /
It is preferable to use it so that it becomes 1.1.

In the above reaction, mixing and stirring are performed for 60 to 15
By carrying out at a temperature of 0 ° C., preferably 80 to 140 ° C., a vanadium-phosphorus oxide having the above X-ray diffraction spectrum pattern and peak intensity ratio can be obtained. The reaction time under stirring is usually about 3 to 24 hours.

Next, a method of using a tetravalent vanadium compound as a starting material will be described.

In the case of this method, a tetravalent vanadium compound is used as a starting material, which is dissolved in an organic solvent and reacted with a phosphorus compound at a temperature of 60 to 150 ° C.

The tetravalent vanadium compound of the present invention means 4
It means an organic or inorganic compound containing a valent vanadium, and representative examples thereof include vanadium dioxide and vanadium oxydichloride. Of these, vanadium dioxide is particularly preferably used.

In this method, the phosphorus compound and organic solvent to be used and the proportion of vanadium compound and phosphorus compound used are the same as those explained in the above method.

Therefore, according to a preferred embodiment, after addition of vanadium dioxide to benzyl alcohol, 80-
The vanadium compound is completely dissolved by heating at 150 ° C, preferably 100 to 130 ° C under stirring, and then a solution of orthophosphoric acid in benzyl alcohol is added to the vanadium compound solution, and the temperature is 60 to 150 ° C, preferably Is stirred at a temperature in the range of 80 to 140 ° C. to react.

In the above-mentioned dissolution treatment, the vanadium compound having a valence of 4 is not reduced so that the vanadium becomes trivalent. It is considered that this is because benzyl alcohols do not have a sufficient function to reduce tetravalent vanadium to trivalent.

In the above reaction, mixing and stirring are performed at 60
By carrying out at a temperature of 150 to 150 ° C., preferably 80 to 140 ° C., a vanadium-phosphorus oxide having the above X-ray diffraction spectrum pattern and peak intensity ratio can be obtained. The reaction time under stirring is usually 3 to
24 hours is enough.

In any of the method of using a pentavalent vanadium compound as a starting material and the method of using a tetravalent compound, after the reaction was carried out at a temperature of 60 to 150 ° C. under stirring, the reaction was continued by further stirring. Aging is preferred until the product precipitates. If the reaction temperature is lower than 60 ° C, the reaction between the vanadium compound and the phosphorus compound is difficult to proceed, while
This is because if the temperature exceeds 150 ° C., the oxidation of the organic solvent proceeds, and further condensation may occur, which may make it difficult to separate the organic solvent and the produced oxide.

Step (2) In step (2), the reaction product (precipitate) obtained in step (1) is calcined.

That is, after the obtained precipitate is washed and filtered, it is usually 100 to 150 ° C., preferably 120 to 150 ° C.
After drying in an inert gas or air stream for about 6 to 24 hours at a temperature of 150 ° C. to obtain a powder or a molded product of the dried product, an oxygen-containing gas atmosphere such as air or an inert gas is used. 350-in a mixed gas atmosphere with air
About 2 at a temperature of 600 ° C, preferably 400-550 ° C.
Bake for 10 hours. Nitrogen is usually used as the inert gas.

[0063] Step (3) There is no particular limitation on the method of activation in step (3),
The activation method generally used in the preparation of this type of oxidation catalyst can be adopted. For example, the powder or molded product fired in the step (2) is heated in an inert gas stream at a temperature of 600 to 800 ° C., preferably 650 to 750 ° C., or a mixed gas stream of a hydrocarbon gas such as butane and air is 350. ~ 600 ° C, preferably 400-4
At a temperature of 50 ° C. for about 5 to 24 hours, preferably 10 to 24
Activate by processing for a period of time.

As the inert gas used for the above activation,
Nitrogen is usually used. In addition to butane, butene, butadiene, pentane, isopentane and other hydrocarbons having about 4 to 5 carbon atoms can be used as the hydrocarbon. When the activation treatment is performed in a mixed gas flow of hydrocarbon gas with air, the concentration of the hydrocarbon gas in the mixed gas is usually 0.5 to 10% by volume, preferably 1 to 5% by volume in terms of butane. Is good. When activation is performed in an inert gas stream, it is necessary to raise the treatment temperature, which tends to reduce the surface area and thus the catalytic activity. It is preferable to carry out in a mixed gas stream.

When the vanadium-phosphorus oxide obtained by the above-mentioned preparation method 1 is used as a catalyst, not only the oxide can be molded into a specific shape and used, but also a molding aid is used during molding. It can also be added.
As a molding aid, an inorganic substance such as silica gel, alumina sol, or talc, or an organic substance such as graphite or a fatty acid salt can be used. In addition, an inorganic fiber can be used in the molding.

The gas-phase oxidation catalyst of the present invention may be used alone or after being molded with a carrier such as silica, alumina, titania, silicon carbide, or earthenware, or supported on these carriers. The shape is not particularly limited, and may be used in the form of powder, or in the form of a sphere, a cylinder, an arch, a saddle, etc., by a conventionally known molding method such as tablet molding or extrusion molding. You can also

The vanadium-phosphorus oxide is a solid acid. By utilizing this property of the solid acid, it can be used as a catalyst for a partial catalytic gas phase oxidation reaction of hydrocarbons, particularly aliphatic hydrocarbons having 3 to 5 carbon atoms.

Examples of the catalytic gas phase oxidation reaction include the production of maleic anhydride by the oxidation of butane, the production of methacrolein and methacrylic acid by the oxidation of isobutane, the production of methacrylic acid by the oxidation of methacrolein, and the acrylonitrile by the ammoxidation of propane. And the production of methacrylic acid by oxidative dehydrogenation of isobutyric acid. In particular, it can be used for the selective oxidation of normal butane to maleic anhydride in the presence of molecular oxygen.

The gas-phase oxidation catalyst of the present invention comprises the above vanadium-phosphorus oxide, and this gas-phase oxidation catalyst contains, in addition to the vanadium-phosphorus oxide, X-ray diffraction for identifying it. Peak to peak intensity ratio: I (2
3.0) / I (28.4) within the range where it does not change, alkali metals such as potassium, sodium, rubidium and cesium; alkaline earth metals such as magnesium, calcium and barium; iron, nickel, cobalt, ruthenium, Rhodium, palladium, iridium, platinum,
It may contain transition metals such as gold, silver, copper, manganese, tungsten, molybdenum, chromium, arsenic, antimony, bismuth, thallium, lead and tin. When these metal components are added, as their supply sources, respective oxides, nitrates, sulfates, carbonates, organic acid salts, phosphates and the like can be used.

As described above, the gas phase oxidation catalyst of the present invention is particularly preferably used for gas phase oxidation of butane to produce maleic anhydride.

Usually, n-butane is used as butane, but the n-butane may contain a small amount of isobutane, butenes, propane, pentanes and the like. Air is preferably used as the oxygen source for the gas phase oxidation, but pure oxygen may be used, or it may be diluted with an inert gas such as steam or nitrogen before use. Usually, the n-butane concentration in the total raw material gas is 0.5 to 10% by volume, preferably 0.5 to 4
% By volume, and the oxygen concentration is 10 to 30% by volume. When the catalyst is used in a fixed bed, the space velocity is 500 to 1000
It is 0 hr ^-1 , preferably 1000 to 5000 hr ^-1 . The reaction temperature is 300 to 550 ° C., preferably 300 to 550 ° C.
It is 450 ° C. The reaction pressure may be either normal pressure or increased pressure, but is usually normal pressure. Further, it goes without saying that a fluidized bed system may be adopted instead of the fixed bed system.

[0072]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. The conversion rate, selectivity and yield in Examples and Comparative Examples are defined as follows.

Conversion (mol%) = (mol of reacted butane / mol of butane fed) × 100 Selectivity (mol%) = (mol of generated maleic anhydride / mol of reacted butane) ) × 100 Yield (mol%) = (number of moles of maleic anhydride formed /
(The number of moles of butane supplied) × 100 Example 1 400 g of vanadium pentoxide (V ₂ O ₅ ) was suspended in 4000 ml of benzyl alcohol, and the suspension was stirred at 120
The mixture was kept at 0 ° C. and reduced for 5 hours to completely dissolve vanadium pentoxide. 100% of 435.4 g of 99% orthophosphoric acid
A phosphoric acid solution was prepared by dissolving in 0 ml of benzyl alcohol and kept at 100 ° C. A phosphoric acid solution at 100 ° C. was added to the reduced black-blue solution of vanadium, and the mixture was heated and maintained at 120 ° C. and stirred for 10 hours, whereby a dark blue precipitate was formed. After allowing the reaction solution slurry to cool, the formed precipitate was separated, washed with acetone, and dried at 140 ° C. for 12 hours. Then, it was molded into a pellet having a length of 5 mm and a diameter of 5 mm. This molded body is placed in an air stream at 500 ° C for 4
Firing for an hour, further lowering the temperature to 400 ° C, and then n-
After switching to a mixed gas flow of n-butane having a butane concentration of 1.5% by volume and air, the temperature was raised to 500 ° C. at 1 ° C./min, and activation treatment was performed at 500 ° C. for 12 hours. X of vanadium-phosphorus oxide obtained as described above
The line diffraction spectrum is shown in FIG. As shown in this X-ray diffraction spectrum, the vanadium-phosphorus oxide had a diffraction angle 2θ (± 0.2 °) of 18.5 °, 23.0 °,
It has major peaks at 28.4 °, 29.9 ° and 43.1 °, and the intensity ratio of the peaks: I (23.0) / I (28.
4) was 0.5.

100 g of the above vanadium-phosphorus oxide was charged into a flow reactor having a diameter of 25 mm and a length of 300 mm, and a mixed gas of n-butane and air having an n-butane concentration of 1.5% by volume was filled therein. Introduced at a speed of 2000 hr ^-1 ,
Gas phase oxidation of n-butane was performed at reaction temperatures of 385 ° C and 390 ° C. The results are shown in Table 1.

Comparative Example 1 400 g of vanadium pentoxide was suspended in 4000 ml of isobutyl alcohol, and the suspension was maintained at 105 ° C. with stirring.
After reduction for 2 hours, reduction of vanadium pentoxide did not proceed completely. 435.4 g of 99% orthophosphoric acid was added to 1
A phosphoric acid solution was prepared by dissolving in 000 ml of isobutyl alcohol and kept at 100 ° C. 10 in vanadium solution
Add phosphoric acid solution at 0 ℃ and heat at 105 ℃.
After stirring for hours, a dark blue precipitate formed. The reaction solution slurry was allowed to cool and the formed precipitate was separated, washed with acetone and dried at 140 ° C. for 12 hours. Then, it was molded into a length of 5 mm and a diameter of 5 mm. This molded body was used in Example 1.
The firing and the activation treatment were performed in the same manner as in.

An X-ray diffraction spectrum of the vanadium-phosphorus oxide obtained as described above is shown in FIG. This X
As shown in the line diffraction spectrum, the vanadium-
The phosphorus-based oxide has a diffraction angle 2θ (± 0.2 °) of 18.
5 °, 23.0 °, 28.4 °, 29.9 ° and 4
It has a main peak of 3.1 °, but the intensity ratio of the peaks: I
(23.0) / I (28.4) was 1.3.

Example 1 except that the above vanadium-phosphorus oxide was used and the reaction temperature was changed to the temperature shown in Table 1.
Gas phase oxidation of n-butane was carried out in the same manner as in. The results are shown in Table 1.

Example 2 400 g of vanadium pentoxide (V ₂ O ₅ ) was suspended in 4000 ml of benzyl alcohol, and the suspension was stirred at 130%.
The temperature was kept at 0 ° C. and reduction was performed for 3 hours to completely dissolve vanadium pentoxide. 100% of 500.7 g of 99% orthophosphoric acid
A phosphoric acid solution was prepared by dissolving in 0 ml of benzyl alcohol and kept at 80 ° C. A phosphoric acid solution at 80 ° C. was added to the reduced black-blue solution of vanadium, and the mixture was heated and held at 110 ° C. and stirred for 10 hours, whereby a dark blue precipitate was formed. After allowing the reaction solution slurry to cool, the formed precipitate was separated, washed with acetone, and dried at 140 ° C. for 12 hours. Then, it was molded into a pellet having a length of 5 mm and a diameter of 5 mm. This molded body was fired and activated in the same manner as in Example 1.

The X-ray diffraction spectrum of the vanadium-phosphorus oxide obtained as described above is shown in FIG. This X
As shown in the line diffraction spectrum, the vanadium-
The diffraction angle 2θ (± 0.2 °) of the phosphorus oxide is 18.5.
23.0 °, 28.4 °, 29.9 ° and 43.
It has a major peak at 1 ° and a peak intensity ratio: I (23.
0) / I (28.4) was 0.5.

Example 1 except that the above vanadium-phosphorus oxide was used and the reaction temperature was changed to the temperature shown in Table 1.
Gas phase oxidation of n-butane was carried out in the same manner as in. The results are shown in Table 1.

Example 3 400 g of vanadium dioxide (VO ₂ ) was suspended in 4000 ml of benzyl alcohol and stirred at 130 ° C.
And vanadium dioxide was completely dissolved by reduction for 2 hours. 99% orthophosphoric acid 477.4 g to 1000
A phosphoric acid solution was prepared by dissolving it in ml of benzyl alcohol and kept at 80 ° C. A phosphoric acid solution at 80 ° C. was added to the black-blue solution of the vanadium compound, and the mixture was heated and maintained at 110 ° C. and stirred for 10 hours to form a dark blue precipitate. After allowing the reaction solution slurry to cool, the generated precipitate was separated,
This was washed with acetone and dried at 140 ° C. for 12 hours. Then, it was molded into a length of 5 mm and a diameter of 5 mm. This molded body was fired and activated in the same manner as in Example 1.

FIG. 4 shows the X-ray diffraction spectrum of the vanadium-phosphorus oxide obtained as described above. This X
As shown in the line diffraction spectrum, the vanadium-
The diffraction angle 2θ (± 0.2 °) of the phosphorus oxide is 18.5.
23.0 °, 28.4 °, 29.9 ° and 43.
It has a major peak at 1 ° and a peak intensity ratio: I (23.
0) / I (28.4) was 0.6.

Example 1 except that the above vanadium-phosphorus oxide was used and the reaction temperature was changed to the temperature shown in Table 1.
Gas phase oxidation of n-butane was carried out in the same manner as in. The results are shown in Table 1.

[0084]

[Table 1]

[0085]

The vanadium-phosphorus oxide of the present invention is
It exhibits excellent activity as a gas-phase oxidation catalyst. For example, in producing maleic anhydride by gas phase oxidation of butane,
Compared with the conventional catalyst, it shows high catalytic activity even at a low reaction temperature, and it becomes possible to produce maleic anhydride with a high selectivity and, thus, a high yield. Therefore, the manufacturing cost can be significantly reduced in the industrial production of maleic anhydride.

Further, the vanadium-phosphorus oxide of the present invention can be produced with good reproducibility in terms of its catalytic performance. Therefore, the yield of the target product does not vary from lot to lot, and the gas phase oxidation reaction can be performed with high reliability and high yield.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction spectrum (anticathode Cu-Kα) of the vanadium-phosphorus oxide obtained in Example 1. The horizontal axis represents the diffraction angle 2θ, and the vertical axis represents the peak intensity (cps).

FIG. 2 is an X-ray diffraction spectrum (anticathode Cu—Kα) of the vanadium-phosphorus oxide obtained in Comparative Example 1. The horizontal axis and the vertical axis are the same as in FIG.

FIG. 3 is an X-ray diffraction spectrum (anticathode Cu—Kα) of the vanadium-phosphorus oxide obtained in Example 2. The horizontal axis and the vertical axis are the same as in FIG.

FIG. 4 is an X-ray diffraction spectrum (anticathode Cu—Kα) of the vanadium-phosphorus oxide obtained in Example 3. The horizontal axis and the vertical axis are the same as in FIG.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-31838 (JP, A) JP-A-50-35088 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 25/37 B01J 21/00-38/74

Claims (18)

(57) [Claims] 1. X-ray diffraction spectrum (anticathode Cu-K
In α), the diffraction angle 2θ (± 0.2 °) is 18.5.
23.0 °, 28.4 °, 29.9 ° and 43.
It has a major peak of 1 ° and a diffraction angle of 2θ (± 0.2
°) = 23.0 ° and a vanadium-phosphorus oxide having an intensity ratio of peaks at 28.4 ° within the following range. 0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0.2 °), respectively. = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown. 2. 0.35 ≦ I (23.0) / I (28.
4) The vanadium-phosphorus oxide according to claim 1, wherein ≦ 0.65. 3. 0.4 ≦ I (23.0) / I (28.
4) The vanadium-phosphorus-based oxide according to claim 1, wherein ≦ 0.6. 4. Vanadium / phosphorus (atomic ratio) is 1/0.
The vanadium-phosphorus-based oxide according to claim 1, which is 9 to 1 / 1.2. 5. An X-ray diffraction spectrum comprising reacting a tetravalent vanadium compound with a phosphorus compound in an organic solvent at a temperature in the range of 60 to 150 ° C. and calcining the resulting reaction product (counter-cathode Cu -Kα), diffraction angle 2
θ (± 0.2 °) is 18.5 °, 23.0 °, 28.4
With major peaks at °, 29.9 ° and 43.1 °,
And the diffraction angle 2θ (± 0.2 °) = 23.0 ° and 2
A method for producing a vanadium-phosphorus oxide, which has the property that the intensity ratio of the 8.4 ° peak is within the following range. 0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0.2 °), respectively. = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown. 6. Vanadium / phosphorus (atomic ratio) is 1/0.
It is 9-1 / 1.2, The manufacturing method of the vanadium phosphorus oxide of Claim 5. 7. The method for producing a vanadium-phosphorus oxide according to claim 5, wherein the reaction temperature is 80 to 140 ° C. 8. A method comprising reducing a pentavalent vanadium compound in an organic solvent, then reacting it with a phosphorus compound at a temperature in the range of 60 to 150 ° C., calcining the resulting reaction product, and then activating it. X-ray diffraction spectrum (anticathode Cu-
Kα), the diffraction angle 2θ (± 0.2 °) is 18.5.
23.0 °, 28.4 °, 29.9 ° and 43.
It has a major peak of 1 ° and a diffraction angle of 2θ (± 0.2
[Deg.] = 23.0 [deg.] And 28.4 [deg.] Peak intensity ratio is within the following range. 0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0.2 °), respectively. = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown. 9. Vanadium / phosphorus (atomic ratio) is 1/0.
It is 9-1 / 1.2, The manufacturing method of the vanadium phosphorus oxide of Claim 8. 10. The method for producing a vanadium-phosphorus oxide according to claim 8, wherein the reaction temperature is 80 to 140 ° C. 11. X-ray diffraction spectrum (anticathode Cu-K
In α), the diffraction angle 2θ (± 0.2 °) is 18.5.
23.0 °, 28.4 °, 29.9 ° and 43.
It has a major peak of 1 ° and a diffraction angle of 2θ (± 0.2
[Deg.] = 23.0 [deg.] And 28.4 [deg.] The intensity ratio of the peaks is within the following range: a catalyst for gas phase oxidation comprising a vanadium-phosphorus oxide. 0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0.2 °), respectively. = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown. 12. 0.35 ≦ I (23.0) / I (2
8.4) ≦ 0.65, The catalyst for gas phase oxidation according to claim 11. 13. 0.4 ≦ I (23.0) / I (28.
4) The gas phase oxidation catalyst according to claim 11, wherein ≦ 0.6. 14. Vanadium / phosphorus (atomic ratio) is 1 /
The gas phase oxidation catalyst according to claim 11, which is 0.9 to 1 / 1.2. 15. Diffraction angle 2θ (±) in X-ray diffraction spectrum (cathode Cu-Kα) as a catalyst when partially vapor-phase oxidizing hydrocarbons using a gas containing molecular oxygen.
0.2 °) is 18.5 °, 23.0 °, 28.4 °, 2
A vanadium-phosphorus-based oxide having major properties of 9.9 ° and 43.1 ° and having a property that the intensity ratio of peaks at diffraction angles of 23.0 ° and 28.4 ° is within the following range. A partial gas phase oxidation method comprising using. 0.3 ≦ I (23.0) / I (28.4) ≦ 0.7 where I (23.0) and I (28.4) are diffraction angles 2θ (± 0.2 °), respectively. = 23.0 ° and 2
The intensity of the 8.4 ° peak is shown. 16. The partial gas phase oxidation method according to claim 15, wherein the hydrocarbons are aliphatic hydrocarbons having 3 to 5 carbon atoms. 17. The partial gas phase oxidation method according to claim 16, wherein the aliphatic hydrocarbon has 4 carbon atoms. 18. The partial gas phase oxidation method according to claim 17, wherein the aliphatic hydrocarbon having 4 carbon atoms is butane, and the partial oxide is maleic anhydride.