JP3320616B2 - Novel metal ion-exchanged phosphorus-vanadium compound and solid acid catalyst using the compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel phosphorus-vanadium-based oxide and a solid acid catalyst containing the phosphorus-vanadium-based oxide. Specifically, the novel phosphorus-vanadium-based oxide is a compound having a specific d value (plane spacing, Å). This compound shows a solid acid, and can be used as a catalyst due to its acid nature. The solid acid catalyst according to the present invention includes, for example, dehydration reaction and dehydrogenation reaction of alcohol, hydration reaction and isomerization reaction of olefin, alkylation, esterification,
It can be used for various reactions such as amidation, acetalization, amination, hydrogen transfer reaction, aldol condensation reaction, and hydrocarbon oxidation reaction. Particularly preferably, it can be used as a catalyst for catalytic gas phase oxidation, for example, production of maleic anhydride by oxidation of butane, production of methacrolein and methacrylic acid by oxidation of isobutane, production of methacrylic acid by oxidation of methacrolein It can be used for reactions such as production of acrylonitrile by ammoxidation of propane and methacrylic acid by oxidative dehydrogenation of isobutyric acid.

[0002]

2. Description of the Related Art Conventionally, various studies have been made on phosphorus-vanadium-based oxides, and physical properties, applications and development of the oxides have been simultaneously conducted. Phosphorus-vanadium compounds have various crystal structures due to their specific characteristics such as oxidation state and structure, and have been used for various purposes because of their structures. The catalytically active component of the phosphorus-vanadium-based oxide is (VO) ₂ P ₂ O ₇
It is also well known that divanadyl pyrophosphate is a crystalline oxide having the following composition. This divanadyl pyrophosphate is obtained by synthesizing a precursor thereof, vanadyl orthohydrogen phosphate hydrate (VOHPO ₄ .nH ₂ O), and dehydrating the precursor by heating. The precursor, vanadyl orthohydrogen phosphate, is VOHP.
It is known that an O ₄ layer is an interlayer compound formed by hydrogen bonding through water molecules between layers.

[0003] Applications used include hydrocarbons having 4 carbon atoms such as butane, butene and butadiene (hereinafter referred to as C4
It is well known that it is effective for gas phase oxidation of hydrocarbons. Various patterns of X-ray diffraction peaks for specifying this phosphorus-vanadium-based oxide have been published. (JP-A-53-61588, JP-A-56-41816)
No., 56-45815, 59-132938,
Japanese Patent Application Laid-Open No. 5-15781). Various additions of the third component to phosphorus-vanadium-based oxides have also been disclosed (Japanese Patent Application Laid-Open Nos. 52-135580 and 54-30).
Nos. 114 and 57-111219).

[0004] Phosphorus-vanadium-based oxides are described in many documents in addition to the above-mentioned publications. K. Hodnett, ed. , Cataly
sis Today, Vol. 1, No. 5 (198
7) is described in detail.

However, vanadyl monohydrogen orthophosphate, which is a precursor of a phosphorus-vanadium-based oxide (V
No attempt has been made to synthesize a compound obtained by exchanging H ⁺ between the layers of OHPO ₄ .nH ₂ O) with a divalent metal cation.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found a phosphorus-vanadium compound having a special structure and completed the invention. Since this compound is a solid acid, it can be used as a catalyst. Furthermore, as a result of using the properties as a solid acid, it has been found that it is particularly effective when used as a catalyst for catalytic gas phase oxidation. The present invention is specified as follows.

(1) A vanadium compound and a phosphorus compound are reacted in an aqueous or organic solvent (VOHPO _4.
nH ₂ O) (0.5 ≦ n ≦ 2.0) and then the compound VOM _0.5 obtained by ion exchange with an aqueous metal salt solution.
A novel metal ion-exchange phosphorus-vanadium compound, which is a metal ion-exchange phosphorus-vanadium compound obtained by further firing PO ₄ (M; divalent metal).

(2) (VOHPO ₄ .nH ₂ O) (0.5 ≦ n ≦) obtained from a vanadium compound and a phosphorus compound
2.0) to prepare a state in which metal ions can be exchanged between the layers,
Thereafter, a novel metal ion-exchanged phosphorus-vanadium-based compound, which is ion-exchanged with an aqueous metal salt solution.

(3) The novel metal ion-exchanged phosphorus-vanadium compound according to the above (1) or (2), wherein the metal salt is a divalent metal.

(4) Any one of the above (1) to (3)
A solid acid catalyst comprising the phosphorus-vanadium-based compound described in 1 above .

(5) A catalyst for gas phase oxidation, comprising the phosphorus-vanadium compound according to any one of (1) to (3).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, the main d values (plane spacing,
Å) and a novel metal ion-exchanged phosphorus-vanadium compound characterized in that the intensity is an X-ray diffraction peak shown in Table 1 below.

[0013]

[Table 1]

(However, in Table 1, VS indicates a very strong peak intensity, S indicates a strong peak intensity, M indicates a medium peak intensity, and W indicates a weak peak intensity.) A method for preparing such a phosphorus-vanadium-based oxide will be described in detail below.

Although any method can be used as long as it can prepare a specific X-ray diffraction spectrum according to the present invention, a typical preparation method is vanadyl hydrogen monohydrogen orthophosphate used as a precursor. Japanese (VOHPO
There are the following two preparation methods depending on the water content of ₄ · nH ₂ O). First, the raw materials used for preparing the catalyst will be described.

As the vanadium source, any vanadium compound generally used for producing a phosphorus-vanadium-based oxide can be used. Specific examples include pentavalent, tetravalent or trivalent vanadium-containing compounds such as vanadium pentoxide, metavanadate, and vanadium oxyhalide. Of these, vanadium pentoxide is particularly preferably used.

As the phosphorus source, similar to the vanadium source,
A phosphorus compound generally used for producing a phosphorus-vanadium-based oxide can be used. As a specific example,
Orthophosphoric acid, pyrophosphoric acid, phosphorous acid, polyphosphoric acid, phosphorus pentoxide and the like can be mentioned. Of these, orthophosphoric acid is preferably used.

Preparation Method 1 Preparation method 1 will be described. The compound H ₂ O
Is a specific amount for convenience.

In preparation method 1, a vanadium compound and a phosphorus compound are reacted in an aqueous or organic solvent to give (VOHPO ₄ .0.5H ₂ O) to obtain (VO).
HPO ₄ · 0.5H ₂ O) was added to distilled water, further adjusted to 5-7 and the pH after addition of the alkali salt, after filtration and washing, a method of ion-exchanged with a metal salt solution. Thereafter, the ion exchanger is dried, and the obtained dried body (VOM _0.5 PO ₄ ) is calcined. More specifically, the following procedure is performed.

(1) Step of reacting a vanadium compound with a phosphorus compound This step involves reacting a vanadium compound with a phosphorus compound in an aqueous or organic solvent (VOHPO _4.
0.5H ₂ O) and the resulting (VOHPO ₄ .0.5
H ₂ O).

Solvents for reacting the vanadium compound with the phosphorus compound include aliphatic alcohols such as methanol, ethanol, 2-butanol, isobutanol, 2-pentanol and isopentyl alcohol; benzyl alcohol, methylbenzyl alcohol, dimethylbenzyl Aromatic alcohols such as alcohol and ethylbenzyl alcohol. In addition, a mixture of an aliphatic alcohol and an aromatic alcohol can be used.

The ratio of the phosphorus source to the vanadium source is 0.9 / 1 as phosphorus / vanadium (atomic ratio).
１．２1.2 / 1, preferably 0.95 / 1１〜1.1 / 1.

In the solution, a vanadium compound and a phosphorus compound are reacted at 60 to 150 ° C. for 2 to 4 hours, and VOHPO
₄ · 0.5H get a ₂ O.

(2) pH adjustment step This step refers to the obtained (VOHPO ₄ .0.5H
_This is a step of adding ₂ O) to distilled water, further adjusting the pH to 5 to 7 after adding an alkali salt, filtering and washing.

The pH adjustment is usually carried out with an alkaline solution. VOHPO ₄ · 0.5H ₂ O was added to distilled water, sufficiently stirred, gradually added an aqueous solution of an alkali such as sodium hydroxide, to adjust the pH to 5-7. Immediately after preparation, the precipitate is filtered and washed thoroughly.

(3) Metal ion exchange step This step is a step in which, after the above-mentioned washing, distilled water is added and ion exchange is performed with a metal salt aqueous solution.

The resulting precipitate is added to an aqueous solution of a metal salt,
The mixture is refluxed at 60 to 100 ° C. for 5 to 60 hours to perform an ion exchange reaction. The metal salt is a nitrate, a carbonate, an organic acid salt or the like, preferably a divalent metal salt of an organic acid salt such as an acetate. The metal is VOHPO ₄ .0.5H ₂ O
It is preferable to use 0.5 to 5 times in molar ratio with respect to. As divalent metals, cobalt, nickel, copper,
There are zinc and the like.

After ion exchange, excess metal salts are removed by filtration and washing.

(4) Drying Step This step is a step of drying the obtained precipitate.

The obtained precipitate is heated at 150 to 250 ° C. for 5 to 5 hours.
Dry for 24 hours in a stream of an inert gas such as nitrogen or in a stream of air to obtain (VOM _0.5 PO ₄ ).

(5) Firing Step This step is a step of firing after the drying step.

After (VOM _0.5 PO ₄ ) is formed into a powder or a molded body, the powder is _{350 to 6} under an inert gas stream or a mixed gas stream of a hydrocarbon gas such as butane and air.
The firing is performed at a temperature of 00 ° C. for about 5 to 24 hours.

Preparation Method 2 Preparation method 2 will be described. The amount of H ₂ O in the compound is indicated by a specific amount for convenience. The preparation method 2, and a vanadium compound and phosphorus compound was heated to reflux in an aqueous solvent and α-VOPO ₄ · 2.0H ₂ O, organic solvents α-VOPO ₄ · 2.0H ₂ O further obtained In this method, VOHPO ₄ .1.5H ₂ O is obtained in the solution, followed by ion exchange with a metal salt aqueous solution. More specifically, the following procedure is performed.

(1) Step of reacting a vanadium compound and a phosphorus compound This step is a step of heating a vanadium compound and a phosphorus compound to reflux in an aqueous solvent to obtain α-VOPO ₄ .2.0H ₂ O. .

With respect to the use ratio of the phosphorus source and the vanadium source, the ratio of phosphorus / vanadium (atomic ratio) was 5/1 to 1
It is good to use it so that it may be 2/1, preferably 7/1 to 10/1.

By adding a vanadium source and a phosphorus source to distilled water and heating and refluxing at 60 to 100 ° C. for 2 to 12 hours, α-VOPO ₄ .2.0H ₂ O can be obtained.

(2) Step of Reducing α-VOPO ₄ .2.0 H ₂ O This step is the step of reducing α-VOPO _4.
2.0H ₂ O is reduced in an organic solvent to form VOHPO _4.
In this step, 1.5H ₂ O is obtained.

Α-VOPO ₄ .2.0H ₂ O reduction solvent
As II, 1-alcohol such as 1-propanol, 1-butanol and 1-pentanol can be used.

Α-VOPO ₄ .2.0H ₂ O
At a temperature of 60 to 150 ° C. for 2 to 24 hours.
₄ · 1.5H get a ₂ O.

(3) Metal ion exchange step This step means that after obtaining VOHPO ₄ .1.5H ₂ O,
This is a step of performing ion exchange with a metal salt aqueous solution.

The obtained VOHPO ₄ .1.5H ₂ O is added to the aqueous solution of the metal salt, and refluxed at 60 to 100 ° C. for 5 to 60 hours to perform an ion exchange reaction. The metal salt is a nitrate, a sulfate, a carbonate, an organic acid salt, or the like, and preferably a divalent metal salt of an organic acid salt such as an acetate. The metal salt is preferably used in a molar ratio of 0.5 to 5 times that of VOHPO ₄ .1.5H ₂ O. Examples of the divalent metal include cobalt, nickel, copper, and zinc.

After ion exchange, excess metal salts are removed by filtration and washing.

(4) Drying Step This step is a step of drying the precipitate.

The obtained precipitate is heated at 150 to 250 ° C. for 5 to 5 hours.
Dry for 24 hours in a stream of an inert gas such as nitrogen or in a stream of air to obtain (VOM _0.5 PO ₄ ).

(5) Firing Step This step is a step of firing after drying.

After (VOM _0.5 PO ₄ ) is made into a powder or a molded body, the powder is _{350 to 6} under an inert gas stream or a mixed gas stream of a hydrocarbon gas such as butane and air.
The firing is performed at a temperature of 00 ° C. for about 5 to 24 hours.

Through the above steps, the vanadium-phosphorus oxide of the present invention is obtained.

When the phosphorus-vanadium compound obtained by the above Preparation Method 1 and Preparation Method 2 is used as a catalyst, not only can the compound be formed into a specific shape and used, but also the molding aid Agents can also be added. As a molding aid, inorganic substances such as silica gel, alumina sol, talc, or graphite,
Organic substances such as fatty acid hydrochloric acid can also be used. In molding, inorganic fibers can be used.

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

The phosphorus-vanadium compound indicates a solid acid. Using the properties of this solid acid, it can be used as a catalyst for a catalytic gas phase oxidation reaction.

The catalytic gas phase oxidation reaction includes the production of maleic anhydride by 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 methacrylic acid by oxidative dehydrogenation of isobutyric acid. In particular, it can be used to selectively oxidize normal butane to maleic anhydride in the presence of molecular oxygen.

[0052]

Next, the present invention will be described in more detail with reference to examples.

Example 1 Vanadium pentoxide (V ₂ O ₅ ) was mixed with 80
Prepared by reacting with 99% orthophosphoric acid at
_{PO 4 · 0.5H 2 O):} 6.0g was added and stirred distilled water 100 ml. A 1.0 mol / liter aqueous sodium hydroxide solution was gradually added to adjust the pH to 6.5.
Immediate filtration and washing were repeated to remove excess sodium ions. This precipitate was added to 250 ml of a 0.2 mol / l divalent cobalt acetate solution, and added at 80 ° C. for 48 hours.
Refluxed for hours. After the reflux, filtration and washing were performed to remove excess metal ions. This was dried at room temperature overnight, and further dried at 200 ° C. for 3 hours under a stream of argon. This dried product was confirmed to be a divalent cobalt exchanger of (VOM _0.5 PO ₄ ). The obtained cobalt exchanger was subjected to a 48-fold air stream with a normal butane concentration of 2.0% by volume.
The firing was performed at 0 ° C. for 12 hours.

The X-ray diffraction spectrum of the obtained cobalt-exchanged phosphorus-vanadium-based oxide (VOCO _0.5 PO ₄ ) was found to have the main peaks shown in Table 1.

Example 2 Vanadium pentoxide (V ₂ O ₅ ) and 85% orthophosphoric acid were prepared by heating to reflux in distilled water (α-VOPO _4.
The 2.0H ₂ O), were prepared further 1 was heated to reflux at 110 ° C. in butanol _{(VOHPO 4 · 1.5H 2 O)} . Obtained (VOHPO ₄ .1.5H ₂ O): 6.0
g of 0.2 mol / l divalent cobalt acetate solution 25
The mixture was added to 0 ml and refluxed at 80 ° C. for 48 hours. After reflux,
Excess metal ions were removed by filtration and washing. this,
Dry at room temperature overnight, and further, at 200 ° C under an argon stream.
For 3 hours. This dried product is (VOM _0.5 PO ₄ )
Was confirmed to be a divalent cobalt exchanger. The obtained cobalt exchanger was calcined at 480 ° C. for 12 hours under an air mixed gas flow having a normal butane concentration of 2.0% by volume.

The X-ray diffraction spectrum of the obtained cobalt-exchanged phosphorus-vanadium oxide (VOCO _0.5 PO ₄ ) was found to have the main peaks shown in Table 1.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI C07D 307/60 C07D 307/60 B 307/89 307/89 (58) Investigated field (Int.Cl. ⁷ , DB name) C01B 25/37 B01J 27/198

Claims (5)

(57) [Claims] 1. A vanadium compound and a phosphorus compound are reacted in an aqueous or organic solvent (VOHPO ₄ .nH ₂
O) (0.5 ≦ n ≦ 2.0) and then compound VOM _0.5 PO ₄ obtained by ion exchange with an aqueous metal salt solution
A novel metal ion-exchanged phosphorus-vanadium-based compound, which is a metal ion-exchanged phosphorus-vanadium-based compound obtained by further firing (M; divalent metal). 2. (VOHPO ₄ .nH ₂ O) obtained from a vanadium compound and a phosphorus compound (0.5 ≦ n ≦ 2.
A novel metal ion-exchanged phosphorus-vanadium-based compound, which is prepared in such a manner that a metal ion-exchangeable layer is prepared between layers 0) and then ion-exchanged with an aqueous solution of a metal salt. 3. The novel metal ion-exchange phosphorus according to claim 1, wherein the metal salt is a divalent metal.
Vanadium compounds. 4. A solid acid catalyst comprising the phosphorus-vanadium compound according to claim 1 . 5. A catalyst for gas-phase oxidation, comprising the phosphorus-vanadium compound according to claim 1.