JPS59132938A - Vanadium-phosphorus oxide catalyst intermediate and preparation of maleic anhydride preparing catalyst by using same - Google Patents

Abstract

PURPOSE:To provide a catalyst having high activity and high selectivity and keeping initial capacities for a long period of time, obtained by using substance wherein the diffraction angle of an X-ray diffraction spectrum has a specific peak as a vanadium-phosphorus oxide catalyst intermediate. CONSTITUTION:As a vanadium-phosphorus oxide catalyst intermediate used in preparing maleic anhydride due to the gas phase oxidiation of 4c hydrocarbon, substance wherein the diffraction angle 2theta in an X-ray diffraction spectrum has a main peak at 10.7 deg., 13.1 deg., 21.4 deg., 24.6 deg., 28.4 deg. and 29.5 deg. is used. This catalyst shows high activity and high selectivity even if corrosive gas such as hydrogen chloride is not used and keeps initial capacities for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vanadium-phosphorous oxide useful as an intermediate for a catalyst for producing maleic anhydride by gas phase oxidation of hydrocarbons having 4 carbon atoms, and a method for producing a vanadium-phosphorus oxide as an intermediate. The present invention relates to a method for producing a vanadium-phosphorus oxide catalyst to be used.

Vanadium-phosphorus oxide is a hydrocarbon having 4 carbon atoms (hereinafter referred to as C4 hydrocarbon) such as butane, butene, butadiene.

) is well known to be effective as a catalyst for the production of maleic anhydride by gas phase oxidation, and vanadium-
Various X-ray diffraction patterns for identifying phosphorous oxides have been published (Japanese Patent Application Laid-open No. 51-15990,
2-156193, JP-A-54-146287, JP-A-56-41816, JP-A-57-135706) 0 There are also many methods for manufacturing the vernadium-phosphorus oxide catalyst. is proposed.

For example, a common manufacturing method involves reacting a pentavalent vanadium compound and a phosphorus compound in an aqueous or organic medium in the presence of a reducing agent to obtain a vanadium-phosphorus compound precursor; It is a method of baking to make a catalyst. Of these, in the production in an aqueous medium, concentrated hydrochloric acid (JP-A-48-63982, JP-A-5
1-95990, etc.), hydrazine (Japanese Unexamined Patent Application Publication No. 1983/1983)
146287, JP-A-54-161594), or react with phosphorous acid under naturally occurring pressure in an autoclave at about 15 Ic (JP-A-Sho 54-161594). No. 49-126587, Japanese Unexamined Patent Publication No. 1983-
156193) method, etc. have been proposed.

However, when using concentrated hydrochloric acid in industrial catalyst production, there is a problem of corrosion, and in the case of hydrazine, there are problems in the production process.
Complications are unavoidable, and in the case of phosphorous acid, the reaction rate is slow and it takes a long time to produce the desired precursor. In addition, the catalysts produced by these methods still have insufficient performance in industrial implementation of maleic anhydride production, such as high reaction temperature and low selectivity for maleic anhydride. They have the common drawback that when used in

On the other hand, in the case of production in an organic medium, an organic medium that has a reducing effect, such as inbutyl alcohol, is used, and the organic medium itself acts as a reducing agent (Japanese Patent Laid-Open No. 53-91100, Kaisho 56-16883
7, JP-A-57-130552) or gaseous hydrogen chloride (JP-A-50-35088, JP-A-5
A method has been proposed in which the reaction is carried out under reflux by using other reducing agents such as phosphorous acid (Japanese Patent Application Laid-open No. 56-141840). There is. Compared to methods in an aqueous medium, maleic anhydride catalysts tend to have lower reaction temperatures and better selectivity to maleic anhydride. However, deterioration of performance is still observed when used for a long period of time in industrial practice, and initial performance cannot be maintained. In this case as well, the most common method is to use corrosive hydrogen chloride, which is a disadvantage in industrial catalyst production methods. Furthermore, even when hydrogen chloride gas is not used, there are drawbacks such as a long reaction time in the catalyst preparation process.

As described above, all of the production methods proposed so far have various drawbacks, and they are still insufficient for industrial implementation.

As a result of intensive studies to improve these drawbacks, the inventors of the present invention discovered that the average valence of vanadium was 3.9 to 4.4 by reacting a vanadium compound with a phosphorus compound and hydrazine as a reducing agent in an aqueous medium. Dust within the range of Table 1 below
An unconventional vanadium-phosphorous crystalline oxide with an X-ray diffraction peak of is added and heat treated at a temperature of 50 to 200°C, preferably 60 to 160°C to convert it into a catalyst precursor,
We have developed the method of the present invention to prepare a catalyst by calcining this at a temperature of 250 to 550 °C, and this catalyst uses corrosive gases such as hydrogen chloride in the production of maleic anhydride by 04 hydrocarbon gas phase oxidation. The inventors have discovered that it is possible to create a catalyst that has high activity and high selectivity, and can maintain its initial performance for a long period of time, even if the catalyst is not used, and has completed the present invention.

The present invention will be explained in more detail below.

As the vanadium compound used as a raw material for preparing the vanadium-phosphorus oxide catalyst intermediate in the present invention in an aqueous medium, compounds containing pentavalent vanadium such as vanadium pentoxide, metavanadate, and pyrovanadate are used.

A portion of a tetravalent or trivalent vanadium compound may be included in this.

However, among these, it is preferable to use vanadium pentoxide as the raw material. Similarly, phosphorus compounds used as raw materials for preparing vanadium-phosphorus oxide catalyst intermediates include orthophosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, phosphorus pentoxide, etc.
An oxide with a valence of 1. The atomic ratio of these phosphorus and vanadium is preferably in the range of 0.7 to 1.25:1, and in particular, it is easier to generate the catalyst intermediate when there is an excess of phosphorus, so the atomic ratio is 1.00 to 1. A range of .20:1 is preferred.

The stoichiometric amount of hydrazine used as a reducing agent is sufficient to reduce the pentavalent nadium raw material to a valence of 3.9 to 4.4, and usually 90 to 120% of that amount.
used within the range.

The method for preparing a vanadium-phosphorus oxide intermediate according to the present invention may be carried out by suspending a vanadium compound in water, adding thereto an aqueous solution of hydrazine and a phosphorus compound in a dropwise manner, or reacting the vanadium compound by suspending the vanadium compound in water. The hydrazine may be added dropwise into the aqueous medium containing the compound and the phosphorus compound. Other addition orders different from these can also be used. A suitable reaction temperature is 50 to 100°C. The catalyst intermediate is
It can be produced by maintaining this temperature for a certain period of time.

The reaction time varies depending on the reaction temperature or the order of addition, but is preferably about 1 hour to about 5 hours.

The precipitate of the catalyst intermediate thus produced is
It is easily confirmed that it shows a line diffraction pattern. This catalyst intermediate has a composition of phosphorus-vanadium-oxygen and contains water of crystallization. Differential thermal analysis shows that this water of crystallization begins to desorb at 110° C., does not lose its crystallinity, and gradually becomes an amorphous substance.

The slurry containing the precipitate of the catalyst intermediate is allowed to cool at room temperature, and then the precipitate is removed from the aqueous medium by a conventional method such as filtration or centrifugation.

As mentioned above, this catalyst intermediate can easily be an amorphous substance, but in the present invention, the amorphous substance that has passed through this catalyst intermediate contains, or the amorphous substance that has passed through this catalyst intermediate, A subsequent heat treatment in an organic medium may be performed, but it is desirable to carry out the heat treatment in a state in which these amorphous substances are kept as low as possible.

Therefore, the cake taken out from the aqueous medium contains free water, which is preferably removed by the following method.

■Replace with the organic medium used.

Drying is carried out at a temperature of 0.0100°C or less, preferably at a temperature of 5 to 80°C, under normal pressure or reduced pressure.

The organic medium used in the present invention does not necessarily have to be a reducing substance. In addition to alcohols, ketones, and ethers, any organic solvent can be used, including nonpolar solvents such as benzene and toluene, and aprotic polar solvents such as N-N' dimethylformamide. Among them, alcohols and ketones that are compatible with phosphorus compounds,
Ethers are preferred. Especially methanol, ethanol,
n-butyl alcohol, cyclohexanol, methyl
Ethyl ketone and dioxane are preferred. Mixtures of organic media may be used. It is desirable to use about 600 CC to 1600 CjT of organic medium per 100 dry powders.

The organic medium is preferably essentially anhydrous, but need not necessarily be anhydrous and may contain less than about 10% water by weight.

The heat treatment temperature is preferably in the range of 50 to 200° C. while stirring. Preferably, the temperature is 60 to 160°C. When using an organic medium with a low boiling point, such as methanol or ethanol, the reaction may be carried out under autogenous pressure using an autoclave or rape.

The treatment time is preferably 0.5 to 10 hours, particularly 0.5 to 6 hours.

Any phosphorus compound can be used as the phosphorus source added to the organic medium. Among them, orthophosphoric acid, birophosphoric acid, polyphosphoric acid, and phosphorous acid are particularly preferred. If orthophosphoric acid is used, it may be commercially available at a concentration of about 85%. The amount of phosphorus to be added is 10% of the dry powder as a catalyst intermediate.
Appropriate values are approximately 0.17 to 357, preferably approximately 57 to 307, in elemental terms relative to 0 yK.

The reason for adding a phosphorus compound is that the heat treatment effect is enhanced by carrying out the heat treatment under acidic conditions in an organic medium. Also, the atomic ratio of phosphorus and vanadium in the final catalyst is 1.0.
．． 0-1.25:1, preferably 1.02-1.20
: The purpose is to adjust the amount of phosphorus so that it is within the range of 1. By adjusting within this range, a catalyst with good performance can be obtained.

The catalyst precursor obtained by heat treatment in an organic medium is
Unlike the intermediates mentioned above, there is little crystalline material, and most of the material has changed to fine amorphous materials. This transformation into an amorphous substance by heat treatment in an organic medium is considered to be one of the reasons why the catalyst has good activity, selectivity, and long life.

The precursor obtained by heat treatment in an organic medium is isolated from the organic medium by conventional methods such as evaporation to dryness, filtration or centrifugation. The isolated catalyst precursor is
Molded alone or with a carrier such as silica, alumina, silicon carbide, titania, etc., or supported on such a carrier at a temperature of 250 to 550 °C, preferably 350 to 450 °C
It is fired at a temperature of ℃. A suitable firing time is 0.5 to 16 hours. Firing is preferably carried out in an oxygen-containing gas atmosphere, such as air. It may also be fired in an inert gas or in an air mixed gas atmosphere containing hydrocarbon gas. The catalyst calcined in this manner is used as a catalyst for producing maleic anhydride by gas phase oxidation of C4 hydrocarbons. Under such calcination conditions, the initial yield of maleic anhydride may be low, but in that case, a mixed gas of air and a hydrocarbon such as methane, ethane, propane, or butane is fed for a certain period of time, and its concentration is adjusted. A high level of activity can be achieved by carrying out an activation treatment that involves contacting the molecule.

What is the C4 hydrocarbon used in the production of maleic anhydride? l-
Butane is preferred. Air is preferred as the oxygen source, but pure oxygen may also be used, or it may be diluted with other inert gases such as water vapor or nitrogen.

The concentration of 04 hydrocarbons in the total raw material gas is preferably 0.5 to 1 volume, preferably 0.5 to 3 volume. When the catalyst is used in a fixed bed, the space velocity of the raw material gas is 1,500 to 20,000 hr, preferably 1,000 to 20,000 hr.
5.000br'. Reaction temperature is 300-55
A temperature of 0°C, preferably 350 to 500°C is suitable.

The catalyst of the present invention can be used in both fixed bed and fluidized bed reactors.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 Vanadium pentoxide V2O5100y was suspended in 50'OCC of water, kept at 80°C with stirring, and 85%
300 g of an aqueous solution in which orthophosphoric acid H3PO413,2f and 13.99 g of hydrazine hydrate were dissolved was dropped little by little to dissolve V2O5. After the dropwise addition, the dark blue solution was refluxed for 2 hours with stirring, producing a dark blue precipitate. A portion of the resulting precipitate was taken out, dried under reduced pressure at 60° C. for 4 hours, and analyzed by X-ray diffraction spectroscopy. As a result, it was confirmed that the precipitate was the catalyst intermediate described in Table 1. The reaction liquid slurry containing this precipitate was left to cool at room temperature, and the precipitate was filtered off. The water contained in this cake was removed by completely replacing it with ethanol. The cake 1322 containing this ethanol 322 is converted into pyrophosphoric acid H4P2O7
The suspension was suspended in ethanol 1150 C.C. in which 18.9 g of 18.9 g was dissolved, heated to 130.degree. C. using an autoclave, and kept under spontaneous pressure with stirring for 2 hours.

Then, the mixture was allowed to cool to room temperature, and the precipitate was filtered and dried at 120° C. for one day to obtain a catalyst precursor. This length is 3.5
tan, diameter 3.5. Molded to φ and 400 mm under air flow
℃ for 1 hour to obtain a catalyst. Analysis of the atomic ratio of phosphorus to vanadium in the catalyst revealed that it was approximately 1.10:I.

A 15Cr-15 catalyst was charged in a U-shaped reaction tube with an inner diameter of 12 mm, and the reaction was carried out to obtain the results shown in Table 2.

Example 2 V2O5100,Of', 85mm orthophosphoric acid H3PO
650 ml of an aqueous solution containing 4°12.6.8 S' was kept at 75°C. There, hydrazine hydrate 13.99
150 cc of an aqueous solution in which was dissolved was added dropwise little by little. After the dropwise addition, the mixture was refluxed for 1.5 hours while stirring to obtain a blue precipitate. These were left to cool at room temperature, and the precipitate was filtered off. The cake was then dried under reduced pressure at 80° C. for 4 hours to completely remove free water. A portion of this powder was subjected to X-ray diffraction spectrum analysis, and as a result, it was confirmed that it was a catalyst intermediate described in Table 1. This powder 100. 97% reduction in OS'/
Ethanol 120 in which eH3PO324,47 was dissolved
Suspended in 0CC and using an autoclave at 130
The temperature was raised to 0.degree. C. and maintained under spontaneous pressure for 3 hours while stirring.

The mixture was then allowed to cool to room temperature, and the precipitate was filtered and dried at 120°C to obtain a catalyst precursor. The following procedure was carried out in the same manner as in Example 1, and the results shown in Table 2 were obtained. An analysis of the atomic ratio of phosphorus and vanadium in the catalyst revealed that it was approximately 1.13:
It was 1.

Example 3 V2O5100,09 was suspended in 500cc of water, kept at 85°C with stirring, and 85ol) orthophosphoric acid H3PO4148,4 and hydrazine hydrate 14.6
300 d of an aqueous solution in which f was dissolved was added dropwise little by little.

After the dropwise addition, the mixture was refluxed for 3 hours with stirring to precipitate a deep blue catalyst intermediate. The reaction mixture containing this precipitate was left at room temperature overnight to cool and remove the precipitate. The cake was then dried under reduced pressure at 40°C to completely remove free water. Take 100.0 y of the resulting powder, suspend it in methanol 120 (Ic) in which 85 m orthophosphoric acid H3PO48,009 has been dissolved, heat it to 120°C using an autoclave, and naturally generate while stirring. The mixture was kept under pressure for 3 hours.Then, it was allowed to cool to room temperature, and the precipitate was filtered off and dried at 120°C to obtain a catalyst precursor.The following procedure was carried out in the same manner as in Example 1, and the results are shown in Table 2. The atomic ratio of phosphorus to vanadium in the catalyst was analyzed and found to be approximately 1.04:1.

Example 4 V2O3100,0? , 85 orthophosphoric acid H3P 0
4137.0? Add 5 50 ml of aqueous solution to 8
The mixture was kept at 0°C, and 200 me of an aqueous solution containing hydrazine hydrate, 3.99% was added dropwise little by little thereto. After the dropwise addition, the mixture was refluxed for 2 hours with stirring to precipitate a deep blue catalyst intermediate. The slurry containing this precipitate was left to cool at room temperature, and the precipitate was filtered. The water contained in this cake was completely replaced and removed with n-butanol. Then cake 1 containing 36.5 r of n-butanol
36.5 f was suspended in n-butanol 1150 (f) in which 14,2 t of 97% phosphorous acid H3PO3 was dissolved and kept under reflux with stirring for 4 hours.Then, it was allowed to cool to room temperature, and the precipitate was evaporated. The catalyst precursor was obtained by drying at 120°C.

The following procedure was carried out in the same manner as in Example 1, and the results shown in Table 2 were obtained. The atomic ratio of phosphorus to vanadium in the catalyst was analyzed and found to be 1.09:1.

Example 5 V2O3100,0? Suspended in 500 g of water, kept at 70°C with stirring, and added 85 orthophosphoric acid H3.
PO4133,2? and 2000: of an aqueous solution in which 13.99% of hydrazine hydrate was dissolved were added dropwise little by little. After the addition, the solution was refluxed for 2 hours while stirring to precipitate a deep blue catalyst intermediate.

The slurry containing 50% of O dispersion was left to cool at room temperature, and the precipitate was filtered off. This cake was dried under reduced pressure at 60°C to remove free water. 1002 in the obtained powder is converted into pyrophosphoric acid H
4P 20726.4 f? Dissolved Echi#Full=
Y-L1200 CCK was suspended and maintained at 140° C. for 1 hour under natural pressure using an autoclave. Then, the temperature was lowered to 50℃ using a rotary evaporator.
The mixture was evaporated to dryness under reduced pressure and then dried at 120°C to obtain a catalyst precursor. The results shown in Table 2 were obtained in the same manner as in Example 1. The atomic ratio of phosphorus to vanadium in the catalyst was analyzed and found to be 1.20:1.

Examples 6 to 9 Catalysts were prepared in the same manner as in Example 1 by changing the solvent, additional phosphorus source, and temperature, and the results shown in Table 2 were obtained in the same manner.

Example lO A catalyst precursor was prepared on a scale ten times that of Example 1.

The obtained powder was shaped into a shape with a length of 5.1 mm and a diameter of 5.1 mm, and was fired at 400°C for 1 hour under a stream of air. The height of the tactile layer is 2 m in the STEFLE 1 reaction tube with an inner diameter of 25 φ.
The reaction was carried out by filling the catalyst until the concentration reached 50,1-77+, and the results shown in Table 2 were obtained.

Comparative example 1 The catalyst intermediate was precipitated using the same procedure as in Example 1.

The reaction solution containing this precipitate was left to cool at room temperature, and the precipitate was filtered off. Then cake 13 containing 28 parts by weight of free water
9t was suspended in water in which 718.9% of birophosphoric acid H4P2O was dissolved, the temperature was raised to 145°C using an autoclave, and the suspension was kept under spontaneous pressure for 2 hours with stirring. Then, it was allowed to cool to room temperature, and the precipitate was filtered.
A catalyst precursor was obtained by drying at 0°C. The following procedure was carried out in the same manner as in Example 1, and the results shown in Table 2 were obtained. The atomic ratio of phosphorus and vanadium in this catalyst was analyzed and was 1.08:
It was 1.

Comparative example 2 The catalyst intermediate was precipitated using the same procedure as in Example 1.

The reaction solution containing this precipitate was left to cool at room temperature, the precipitate was filtered, and the resulting cake was dried under reduced pressure at 60°C.

The powder was made into a catalyst in the same manner as in Example 1 without heat treatment in an organic medium, and the reaction was carried out using the same reaction tube to obtain the results shown in Table 2.

Comparative Example 3 Water is removed by azeotropic distillation from 825 CC of inbutanol to which 85 orthophosphoric acid H3PO476,09!7' has been added, and 7y amount of isobutanol is added to V2O550,0? was suspended. The mixture was then refluxed for 16 hours while stirring. The large blue precipitate formed was filtered, washed and dried. The Ela Nada powder was used as a catalyst in the same manner as in Example 1, and the reaction was carried out using the same reaction tube to obtain the results shown in Table 2.

Comparative example 4 V20g 54.6! i', 85-cycle orthophosphoric acid H3
P 0437,, Of, Phosphite H3PO327,9G
'220 m/! Add each to 1 jl of water at 3 o'clock.
The mixture was refluxed with stirring for 3'tj. After cooling the obtained blue slurry to 80℃, it was poured into a crepe and heated to 150℃.
℃ and held under autogenous pressure for 4 hours. Then 12
The resulting powder was evaporated to dryness at 0° C. and used as a catalyst in the same manner as in Example 1, and reacted using the same reaction tube to obtain the results shown in Table 2.

As can be seen from the results shown in Table 2 Examples 1 to 9, the catalyst produced by the uninvented method has the advantage that it can be produced without using corrosive gas and the treatment time is short. n− compared to that of the conventionally proposed method.
The selectivity and yield of butane to maleic anhydride are excellent, and the initial performance can be maintained even if the reaction is carried out continuously. In addition, Example 10 in Table 2 shows the results obtained by attempting a longer reaction time under conditions close to industrial conditions, which can be said to be sufficiently satisfactory for industrial implementation.

As described above, the catalyst according to the present invention has the advantage that it can be produced in industrial practice so that it can maintain a long life and initial performance.

Patent applicant: Agent of Nippon Shokubai Chemical Co., Ltd.
Takeo Yamaguchi...

Claims (1)

[Claims] (In the 11 X-ray diffraction spectrum (α to the anticathode Cu-), the diffraction angles 2θ are 10.7°, 13.1', 21.4°,
A vanadium-phosphorous oxide catalyst intermediate characterized by having main peaks at 24.6°, 28.4° and 29.5°. (2) (a) A vanadium compound, a phosphorus compound, and hydrazine as a reducing agent are mixed in an aqueous medium so that the atomic ratio of phosphorus to vanadium is 0.7 to 1.25:1 and the valence of vanadium is 3.9 to 4. .4 to precipitate the catalyst intermediate composition according to claim (1); (b) then remove the precipitate in an aqueous medium; ) The resulting precipitate was heated in an organic medium in the presence of a phosphorus compound for 50~
From the steps of heat treatment at a temperature of 200° C. to obtain a catalyst precursor, (d) removing said precursor from an organic medium, and (e) calcining said precursor at a temperature of 250 to 550° C. A method for producing a catalyst for producing maleic anhydride having a phosphorus to vanadium atomic ratio of 1 to 1.25:1. (The method for producing a catalyst according to claim (2), characterized in that in the operation of 31(a), the vanadium compound is vanadium pentoxide and the phosphorus compound is orthophosphoric acid. (4) Heat treatment in the operation of (c) Temperature is 60-1
Claims characterized in that the temperature range is 60°C (
2) or the catalyst production method described in tS+. +5+ The method for producing a catalyst according to claim (2), (3) or (4), wherein the organic medium in the operation (C) is an alcohol, a ketone, an ether, or a mixture thereof. . +6) Claims (2), (3) characterized in that the organic medium in the operation (C) is methanol ethanol, n-butyl alcohol, cyclohexanol, methyl ethyl ketone, dioxane or a mixture thereof.
), +41 or the catalyst production method described in (5). (In the operation of Section 71(b), the said precipitate is
Claims (2) and (2), characterized in that the mountain water is removed by drying under normal pressure and reduced pressure at 0 degrees in the range of 5 to 80 degrees Celsius.
3), (4), (5) and the catalyst production method described in (6). (8) Claims (2), (3), (4), and (5) characterized in that in the operation (b), free water contained in the precipitate is removed by replacing it with an organic medium. Not yet (
6) Catalyst production method described. +9) The phosphorus compound in the operation (C) is at least one selected from the group consisting of orthophosphoric acid, pyrophosphoric acid and phosphorous acid, and the dry powder obtained in claim (7) is converted to 1005' Claims (2) characterized in that there is a range of approximately 57 to 30 degrees.
), (3), (4), (5), (7) or (8). Claim (2), characterized in that in the operation of Oot (c) the organic medium is heat-treated under autogenous pressure;
The catalyst manufacturing method described in (3), (4), (5), (6), (7), (81 or (9)).