JPH04257573A - Production of dicarboxylic acid anhydride - Google Patents

Abstract

PURPOSE:To produce a dicarboxylic acid anhydride by vapor phase catalytic oxidation reaction of >=4C hydrocarbon, where the reactional activity and selectivity are remarkably improved. CONSTITUTION:In a method for producing a dicarboxylic acid by vapor phase catalytic oxidation reaction from >=4C hydrocarbon, an oxide complex having a specific X ray diffraction spectrum (precursor oxide) consisting of (1) a quadivalent vanadium compound, (2) pentavalent phosphorus compound and, as necessary, (3) a promoter selected from a group composed of iron, chromium, cobalt, nickel, zirconium and titanium and is subjected to wet grinding in a specific organic solvent and calcine the complex oxide or the precursor, and then the calcined oxide is wet-ground in an organic solvent to form a crystalline oxide, and is used as the catalyst.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing dicarboxylic anhydrides. Specifically, the present invention relates to a method for producing maleic anhydride by a gas phase catalytic oxidation reaction of a hydrocarbon having 4 or more carbon atoms.

0002

BACKGROUND OF THE INVENTION Vanadium-phosphorus composite oxides are widely known to be effective catalyst components for the production of maleic anhydride through gas phase catalytic oxidation reactions of hydrocarbons having 4 or more carbon atoms. Especially in the case of n-butane, which has low reactivity (V
A compound called O)2 P2 O7 (divanadyl pyrophosphate) is used as a catalyst component (E.Bo
rdes, P. Courtine, J. Catal
．． , 57, 236-252, (1979)).

This compound has an X-ray diffraction spectrum (anticathode; Cu-Kα) of 14.2°, 15.7°, 1
8.5°, 23.0°, 28.4°, 30.0°, 33
．． Diffraction angles of 7° and 36.8° (2θ; ±0.2°)
shows the main peak (second X-ray diffraction peak). usually,
This compound is mixed with a suitable carrier and formed as a catalyst before being used in a fixed bed or fluidized bed reactor.

[0004] In this catalytic process, it is reported in JP-A-57-122944 that the catalytic activity is improved by wet-pulverizing divanadyl pyrophosphate in water. Furthermore, JP-A No. 62-203851 reports a method of preparing a fluidized catalyst from an aqueous slurry in which a catalyst oxide, a vanadium-phosphorus-containing aqueous solution, and silica sol are mixed. Wet or dry grinding of the material is recommended.

Furthermore, Japanese Patent Laid-Open No. 60-227835 discloses that divanadyl pyrophosphate, which has been pulverized to a diameter smaller than 0.5 μm, is further pulverized in an aqueous phosphoric acid solution to improve the attrition resistance of the catalyst. It has been reported that These are thought to contribute to increasing activity and improving fluidity and strength by crushing oxides that are active components in the catalyst.

[0006]

[Problems to be Solved by the Invention] However, all of the conventional methods involve wet pulverization treatment in water or an aqueous medium, which is insufficient for expressing sufficient activity and selectivity.

[0007]

[Means for solving the problem] Therefore, the present inventors
With the aim of providing a method for producing dicarboxylic acid anhydrides with markedly improved reaction activity and selectivity, we have conducted intensive studies on the effects of pulverization on catalysts. The inventors have discovered that when aromatic hydrocarbons or oxygen-containing organic compounds are used, remarkable improvements in reaction activity and selectivity can be seen, and the present invention has been achieved.

That is, the gist of the present invention is to provide a method for producing a dicarboxylic acid anhydride from a hydrocarbon having 4 or more carbon atoms by a gas phase catalytic oxidation reaction, in which (1) a compound of tetravalent vanadium, (2) a compound of tetravalent vanadium is used as a catalyst; a compound of pentavalent phosphorus, and (3
) If necessary, a composite oxide (precursor oxide) consisting of a promoter selected from the group consisting of iron, chromium, cobalt, nickel, zirconium, and titanium and having a specific X-ray diffraction spectrum is mixed with an aromatic hydrocarbon solvent or an oxygen-containing solvent. Phosphorus-vanadium crystals obtained by wet-pulverizing in an organic solvent and then firing, or by firing a precursor and then wet-pulverizing a fired oxide in an aromatic hydrocarbon solvent or an oxygen-containing organic solvent. The present invention relates to a method for producing a dicarboxylic acid anhydride, characterized in that a dicarboxylic acid anhydride is used.

The present invention will be explained in detail below. The phosphorus-vanadium crystalline oxide used as a catalyst is usually produced by calcining its precursor oxide. This precursor oxide has 15.6°, 19.6°, 24.2°, and 27.1° in the X-ray diffraction spectrum (anticathode; Cu-Kα).
°, 28.8°, 30.5°, 32.0° and 33.
It has a main peak (first X-ray diffraction peak) at a diffraction angle of 8° (2θ; ±0.2°).

[0010] Many methods for producing precursor oxides have been reported, some examples of which are shown below. (2) Vanadium pentoxide is reduced with a reducing organic solvent such as isobutanol in the presence of phosphoric acid and heated to obtain a slurry (Japanese Patent Publication No. 8761/1983). (2) Vanadium pentoxide is reduced with an inorganic reducing agent such as hydrazine in the presence of phosphoric acid, and then treated under hydrothermal conditions to obtain a slurry (JP-A-57-32110). The precursor oxide can be removed as a solid by evaporating the slurry to dryness, spray drying, centrifugation, filtration, or the like.

The obtained precursor oxide is heated in a muffle furnace, rotary kiln, or fluidized in an atmosphere of an inert gas such as nitrogen or argon; air; air diluted with an inert gas; or air containing butane, butene, etc. By firing using a device such as a floor firing furnace, it is converted into an oxide (fired product oxide) whose main component is divanadyl pyrophosphate, which has a second X-ray diffraction peak. The firing temperature is usually in the range of 300 to 700°C.

The present invention is characterized in that the precursor oxide or fired oxide is pulverized in the presence of an aromatic hydrocarbon solvent or an oxygen-containing organic compound solvent. As aromatic hydrocarbon solvents and oxygen-containing organic compound solvents,
Aromatic hydrocarbons such as toluene, isobutanol, alcohols such as ethylene glycol, and ethers such as tetrahydrofuran are used, and it is particularly preferable to use isobutanol or toluene. These solvents may be used alone or in combination.

The pulverization is desirably carried out using a suitable wet or dry pulverizer such as a hammer mill, jet mill, colloid mill, or sand grinder until the average particle size is 0.5 μm or less.

The precursor oxide or calcined oxide pulverized as described above is recovered by appropriate means such as spray drying or centrifugation.

The precursor oxide pulverized and recovered by the method of the present invention can be used as a catalyst itself or as an active component of a catalyst, or as a precursor thereof. It is suitably used in the production of maleic anhydride by gas phase oxidation of hydrocarbons of number 4 or more.

For example, the precursor oxide itself can be used as a fixed bed catalyst by molding it into a pellet or other catalyst shape, if necessary using a molding aid. Further, the precursor oxide as an active ingredient can be used as a fixed bed catalyst by molding it into a pellet or other catalyst shape together with a carrier and other auxiliary components and, if necessary, a molding aid.

[0017] When catalyzed in the form of the precursor oxide in this way, the resulting catalyst usually has a
It is fired at a temperature of about 600°C, activated by being converted into a fired oxide form, and used for the reaction. The firing atmosphere is an inert gas such as nitrogen or argon;
Air; air diluted with an inert gas; air containing butane, butene, etc. are preferably used. Note that the activation by calcination can also be performed outside the reactor using a suitable calcination furnace.

Further, when the precursor oxide pulverized and recovered by the method of the present invention is fired, a fired oxide is obtained as described above. Firing temperature is usually 350-800℃,
Preferably it is 400-600°C. The atmosphere for the calcination is the same as that described above for the calcination of the precursor oxide-containing catalyst.

[0019] The sintered oxide obtained by pulverizing and recovering the precursor oxide or the sintered oxide obtained by pulverizing and recovering the precursor oxide and then sintering itself It is suitably used in the production of maleic anhydride by gas phase oxidation of hydrocarbons having 4 or more carbon atoms, such as butane, butene, 1,3-butadiene, etc., as a catalyst or as an active component of a catalyst.

For example, the fired oxide itself can be used as a fixed bed catalyst by molding it into a pellet or other catalyst shape, using a molding aid if necessary. It can also be used as a fixed bed catalyst by forming the calcined oxide as an active ingredient into a pellet or other catalyst shape together with a carrier and other auxiliary ingredients and, if necessary, a forming aid. Note that even in the case of a catalyst containing a fired oxide as described above, activation by firing may be performed in the same manner as in the case of the catalyst containing a precursor oxide.

Furthermore, the precursor oxide or calcined oxide can be used as a fluidized bed catalyst by forming it into the shape of a fluidized bed catalyst such as fine spherical particles together with a carrier or other auxiliary components. As the molding method in this case, it is preferable to use a spray drying method.

A particularly preferred method for this is a first component consisting of a precursor oxide or calcined oxide, an aqueous solution containing vanadium and phosphorus (preferably at least in part in the form of vanadyl phosphate). In this method, a second component consisting of a solution and a third component consisting of a silica sol are mixed to form an aqueous slurry, the slurry is spray-dried, and the obtained solid particles are calcined (Japanese Patent Application Laid-open No. 170542/1983). , No. 58-170543, etc.).

[0023] At this time, the composition of the first component is 20~
90% by weight, preferably from 30 to 80% by weight, and the third component from 3 to 60% by weight, preferably from 5 to 30% by weight.

[0024] At this time, it is preferable to pulverize the first component before preparing the aqueous slurry, and for this purpose, use a suitable pulverizing device such as a hammer mill, jet mill, colloid mill, sand grinder, etc. It is pulverized by a wet method or a dry method to obtain a particle size of usually 10 μm or less, preferably 5 μm or less.

[0025] For firing, any type of firing furnace such as a muffle furnace, rotary kiln, fluidized fluidized furnace, etc. can be used. The atmosphere for the calcination is the same as that described above for the calcination of the precursor oxide-containing catalyst. The fluidized bed catalyst thus obtained has excellent activity, fluidity and strength.

[0026] The solid particles obtained by the above spray drying can also be used as a solid bed catalyst by forming them into pellets or other catalyst shapes. Also,
Adding additives such as Fe, Cr, Ti, Zr, etc. into the catalyst is a common practice to improve activity and selectivity. (B.K. Hodnett, Cata
l. Rev. , 27, 373, (1985), etc.). The pulverization method of the present invention can also be effectively used for catalysts modified with these.

The catalyst thus produced can be suitably used for producing maleic anhydride from hydrocarbons having 4 or more carbon atoms by gas phase catalytic oxidation. Preferably n-butane, 1-butene, 2-butene, 1,3-butadiene or mixtures thereof are used. Particularly economically advantageous are n-butane and butenes, which can be easily obtained by separation from natural gas, from naphtha cracking products, or by FCC reaction.

The gas phase catalytic reaction may be carried out in either a fluidized bed or a fixed bed. Air or a molecular oxygen-containing gas is used as the oxidizing agent. Feedstock hydrocarbon is usually 0.1-10% by volume
The oxygen concentration is preferably 1 to 5% by volume, and the oxygen concentration is 10 to 30% by volume. The reaction temperature is in the range of 300 to 550°C, more preferably 350 to 500°C, and the reaction pressure is usually normal pressure or 0.05 to 10 kg/cm2.

[0029]

[Examples] The present invention will be explained in detail with reference to Examples below, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Production Example 1 In a beaker with a volume of 300 ml, 60 g of demineralized water, 27.
7g of 85% H3 PO4, 3.13g of 80% N2
H4 .H2 O and 18.4 g of V2 O5 were added to dissolve the entire amount. Concentrate the solution to 100 g, put it in a Teflon container, and add it to 150 g in a pressurized airtight container.
Hydrothermal treatment was performed at ℃ for 12 hours. Upon cooling, a blue aqueous slurry was obtained. After filtering the slurry, it was washed with acetone and dried at 130° C. overnight to obtain a precursor oxide (having the first X-ray diffraction peak).

15 g of this precursor oxide and 40 g of isobutanol were mixed in a wet pulverizer (sand mill) with an internal volume of 150 ml.
ZrO2 with a particle size of 0.8 to 1.2 mm
Add 100ml of beads and mix with a stirring blade of 42mm in diameter.
Stirring and pulverization were performed for 2 hours at a rotational speed of 300 rpm. The resulting slurry was filtered, washed with acetone, air-dried for one day, and then calcined under nitrogen at 600° C. for 30 minutes to obtain catalyst A.

Production Example 2 A precursor oxide obtained in the same manner as Production Example 1 was heated under nitrogen for 6 hours.
The mixture was fired at 00°C for 30 minutes to obtain a fired oxide (catalyst B). This oxide is a crystal with a diameter of 2 μm, and the second
It had a line diffraction peak.

Production Example 3 Catalyst B was pulverized and produced in the same manner as in Production Example 1 to obtain Catalyst C.

Production Example 4 Catalyst D was produced in the same manner as Catalyst C except that the pulverization time was 30 minutes.

Production Example 5 Catalyst E was obtained in the same manner as Catalyst C except that toluene was used instead of isobutanol.

Production Example 6 Catalyst F was obtained in the same manner as Catalyst C except that ethylene glycol was used instead of isobutanol.

Production Example 7 Catalyst G was obtained in the same manner as Catalyst C except that demineralized water was used instead of isobutanol.

Production Example 8 Catalyst H was produced in the same manner as Catalyst C except that cyclohexane was used instead of isobutanol.

Production Example 9 According to Example 1 of JP-A No. 60-227835, the precursor oxide was crushed in water, then calcined, and the calcined oxide was crushed in an aqueous phosphoric acid solution to produce catalyst I. Manufactured.

Production Example 10 1.35 g of FeCl3 was placed in a 500 ml flask.
, after dissolving 175 ml of isobutanol, V2
Add 18.2 g O5 and 23.8 g 99% H3 PO4 dissolved in 150 ml isobutanol,
Refluxed for an hour. The resulting slurry was centrifuged, washed with isobutanol, and dried overnight at 130°C to obtain a precursor oxide.

The precursor oxide was calcined at 600° C. for 30 minutes under nitrogen to obtain a calcined oxide (catalyst J). The obtained calcined oxide has a diameter of about 5 μm and a shape similar to a cabbage, and has a second X-ray peak like Catalyst A, but the peak intensity ratio is different.

Production Example 11 Catalyst I was prepared in Production Example 1 except that the pulverization time was 1 hour.
Catalyst K was obtained by pulverization and production in the same manner as above.

Production Example 12 250 g of demineralized water, V2 in a 1000 ml beaker
O5 91.8g, 85% H3 PO4 115.3g
After adding 126.1 g of oxalic acid (dihydrate) and boiling for 30 minutes, the weight was adjusted to 500 g. This solution contains amorphous PV and is useful as a binder component in producing fluidized catalysts. 13.3 g of this solution and 5 g of 20% by weight silica sol were added to Catalyst C and uniformly dispersed. After drying the obtained slurry on a hot plate, it was calcined at 600° C. for 30 minutes in a nitrogen atmosphere to obtain catalyst L.

Examples 1 to 7 and Comparative Examples 1 to 3 Using catalysts A, C, D, E, F, K, L, G, H and I obtained in the above production examples, n-butane gas was prepared. Phase catalytic oxidation was performed. The catalyst was calcined in a nitrogen atmosphere and then molded into tablets.
It was used after being ground to 0 mesh.

A quartz reaction tube was filled with 1.0 cc of catalyst, and 5
The temperature was raised to 20°C under a nitrogen atmosphere, and the reaction gas was switched to 4% n-butane/96% air (O2:N2 = 20%:76%) to carry out the reaction. The flow rate of the reaction gas was 1 liter/hr, and the SV was 1000 hr-1.

[0046] Analysis was carried out by on-line gas chromatography. The maximum maleic anhydride yield and the optimum reaction temperature giving it were determined. The results are summarized in Table 1.

Comparative Examples 4 and 5 Catalysts B and I produced without pulverization were tested for activity in the same manner as in Example 1 above. The results are summarized in Table 1.

In the case of both catalysts, particularly good yields of maleic anhydride can be obtained by grinding in an organic medium.

[0049]

[Table 1]

Claims (4)

[Claims] Claim 1. A method for producing a dicarboxylic acid anhydride from a hydrocarbon having 4 or more carbon atoms by a gas phase catalytic oxidation reaction, the catalyst comprising: (1) a compound of tetravalent vanadium;
(2) a compound of pentavalent phosphorus, and (3) optionally a promoter selected from the group consisting of iron, chromium, cobalt, nickel, zirconium, and titanium, and X-ray diffraction spectrum (anti-cathode; Cu-Kα) 15.6° at
19.6°, 24.2°, 27.1°, 28.8°, 3
Diffraction angles of 0.5°, 32.0° and 33.8° (2θ
; ±0.2°) is characterized by using a phosphorus-vanadium-based crystalline oxide obtained by wet-pulverizing a composite oxide having a main peak in an aromatic hydrocarbon solvent or an oxygen-containing organic compound solvent. Method for producing dicarboxylic acid anhydride. 2. As a catalyst, a wet-pulverized phosphorus-vanadium crystalline oxide is mixed with an aqueous solution containing vanadium and phosphorus and/or an aqueous medium containing silica, and then the resulting aqueous slurry is dried. 2. The method for producing a dicarboxylic acid anhydride according to claim 1, wherein a calcined product is used. 3. A method for producing a dicarboxylic acid anhydride from a hydrocarbon having 4 or more carbon atoms by a gas phase catalytic oxidation reaction, the catalyst comprising: (1) a compound of tetravalent vanadium;
(2) a pentavalent phosphorus compound; and (3) optionally a promoter selected from the group consisting of iron, chromium, cobalt, nickel, zirconium, and titanium; 15.6° at
19.6°, 24.2°, 27.1°, 28.8°, 3
Diffraction angles of 0.5°, 32.0° and 33.8° (2θ
; ±0.2°) obtained by firing a composite oxide having a main peak at
α) 14.2°, 15.7°, 18.5°, 2
3.0°, 28.4°, 30.0°, 33.7° and 3
Phosphorus-vanadium crystallinity obtained by wet grinding a composite oxide having a main peak at a diffraction angle of 6.8° (2θ; ±0.2°) in an aromatic hydrocarbon solvent or an oxygen-containing organic compound solvent. A method for producing a dicarboxylic acid anhydride, characterized by using an oxide. 4. As a catalyst, wet-milled phosphorus-vanadium crystalline oxide is mixed with an aqueous solution containing vanadium and phosphorus and/or an aqueous medium containing silica, and then the resulting aqueous slurry is dried. A method for producing a dicarboxylic acid anhydride, characterized by using a dicarboxylic acid anhydride.