JP3299424B2 - Catalyst for producing acrylic acid and method for producing the same - Google Patents

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 a molybdenum-vanadium catalyst used for producing acrylic acid by subjecting acrolein or an acrolein-containing gas to catalytic gas phase oxidation with molecular oxygen or a molecular oxygen-containing gas. .

[0002]

2. Description of the Related Art Various improved catalysts have been proposed for efficiently producing acrylic acid by a catalytic gas-phase oxidation reaction of acrolein, but most of them are molybdenum-vanadium-based molybdenum-vanadium catalysts. It is.

[0003] Among the molybdenum-vanadium-based catalysts proposed so far, the yield of acrylic acid has reached a considerable level from an industrial point of view, and is used in an actual process for producing acrylic acid. ing. However, the conventional molybdenum-vanadium-based catalyst has not always been satisfactory from the viewpoint of whether the catalyst can stably maintain a high acrylic acid yield for a long period of time. Therefore, there has been a demand for the development of a molybdenum-vanadium-based catalyst which exhibits stable performance for a long time when producing acrylic acid by oxidation of acrolein.

As one of approaches to the development of such a molybdenum-vanadium catalyst, studies have been made to devise a catalyst preparation process. For example, Japanese Patent Publication No. 50-25
No. 914 discloses a method in which an organic acid such as oxalic acid is present in a catalyst preparation step, and the effect of the organic acid is used to control the oxidation state of the catalyst or to form a compound of molybdenum and vanadium. ing.
However, in this method, the reproducibility of the catalyst performance is poor due to the thermal effect due to the heat generated by the decomposition of the organic acid in the heating and calcination steps of the catalyst, and in performing the oxidation reaction of acrolein for a long time. Since it is difficult to maintain the effect of the organic acid in the catalyst preparation step, it is not satisfactory in industrial practice not only in terms of the yield of acrylic acid but also in terms of life.

[0005]

The present invention 0005] generally formula (I): detail later _{Mo a V b W c Cu d} X e O f (I) ( the components and their ratio in formula The present invention intends to provide a method for producing a molybdenum-vanadium-based catalyst for producing acrylic acid, which has excellent activity, selectivity and catalyst life, and exhibits stable performance over a long period of time.

[0006]

The present invention relates to a molybdenum-vanadium-based catalyst represented by the above general formula (I) whose active species is VMo ₃ O ₁₁ , and the vanadium and molybdenum are combined with the progress of the oxidation reaction of acrolein. (Hereinafter sometimes referred to as “vanadium-molybdenum active compound”) is deteriorated, the catalyst is deteriorated, and most of vanadium is pentavalent (for example, V ₂ O _5).
), It has been reported that the selectivity to acrylic acid from acrolein is significantly reduced (TV AND).
RUSHKEVICH, CATAL. REV. −SC
I. ENG. , 35, P213 (1993)).

Accordingly, the present inventors have investigated various changes in physical properties of the molybdenum-vanadium-based catalyst, for example, changes in surface area and pore volume, and further reduced its activity using X-ray diffraction analysis. The physical and chemical differences between the catalyst and the unused catalyst were compared.
= 4.00 angstroms was found to be related to the catalyst performance and its aging. According to the above literature, the peak at d = 4.00 Å is assigned to VMo ₃ O ₁₁ which is a compound of vanadium and molybdenum.

Specifically, when the catalyst composition is Mo ₁₂ V ₅ W ₁ Cu _2.2
The molybdenum-vanadium-based catalyst (atomic ratio excluding oxygen) will be described below as an example. When the surface area and pore volume of the unused catalyst having this catalyst composition and the acrolein catalytic gas phase oxidation reaction continued for 4000 hours and the performance of the reduced catalyst were measured, the unused catalyst was subjected to the reaction for 4000 hours and the activity was measured. The surface area by the BET method with the lowered catalyst was 2.5 m ² / g and 2.4 m ² / g, respectively, and there was no significant difference. Also, the pore volume was 0.20 cc / g and 0.18 c / g, respectively.
c / g, which was not much different. However, X
The peak of d = 4.00 angstroms caused by the above vanadium-molybdenum active compound and the peak of d = 4.38 angstroms caused by V ₂ O ₅ known as a pentavalent vanadium compound are examined by a line diffraction method. As a result, the intensity of the peak at d = 4.00 angstroms was 84 for the catalyst subjected to the reaction for 4000 hours assuming that the unused catalyst was 100, which was significantly lower than that of the unused catalyst. That is, the activity of the catalyst is d =
There is a strong correlation with the intensity of the vanadium-molybdenum active compound having a peak at 4.00 angstroms, and one of the causes of the decrease in activity is that the crystal phase having a peak at d = 4.00 angstroms is reduced. There was found.

Therefore, the present inventors have determined that d = 4.00.
As a result of intensive studies on the generation of the above-mentioned vanadium-molybdenum active compound having a peak at angstrom, ammonium metavanadate and copper nitrate were used as sources of vanadium and copper, respectively, and a part of the ammonium metavanadate and copper nitrate was used. Is substituted with vanadium oxide and copper oxide, respectively, having small valences to prepare a catalyst, whereby in the X-ray diffraction analysis, d = attributable to the vanadium-molybdenum active compound described above is obtained.
It has been found that the peak intensity at 4.00 angstroms increases, while the peak intensity at d = 4.38 angstroms due to V ₂ O ₅ decreases, the activity of the catalyst is improved and stable performance is exhibited over a long period of time. . The present invention has been completed based on such findings.

[0010] Namely, the present invention provides for the production of acrylic acid acrolein or acrolein-containing gas is oxidized with molecular oxygen or a molecular oxygen-containing gas at vapor phase, the following general formula (I): Mo _a V _{b W c Cu d X e O} f (I) ( wherein, Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, X is at least one element selected from titanium, zirconium and cerium, and,
And O is oxygen, a, b, c, d, e and f represent the number of atoms of Mo, V, W, Cu, X and O, respectively, and when a = 12, 2 ≦ b ≦ 14, 0 ≤c≤12,0
<D ≦ 6 (preferably 0.01 ≦ d ≦ 6), 0 ≦ e ≦ 1
0, and f is a value determined by the oxidation state of each element). In producing a molybdenum-vanadium-based oxide catalyst represented by the following formulas (A) and (B), Or a method for producing a catalyst for producing acrylic acid, which comprises producing the catalyst under the condition (c).

(A) As a source of vanadium, ammonium metavanadate and a vanadium oxide having a valence of vanadium greater than 0 and less than 5 are used, and copper nitrate is used as a source of copper.

(B) Ammonium metavanadate is used as a source of vanadium, and copper nitrate and a copper oxide having a valence of more than 0 and less than 2 are used as a source of copper.

(C) As a source of vanadium, ammonium metavanadate and a vanadium oxide having a valence of vanadium of more than 0 and less than 5 are used, and as a source of copper, a valence of copper nitrate and copper of more than 0 and less than 2 is used. Is used. Further, the present invention relates to a molybdenum-vanadium-based acrylic acid production catalyst represented by the general formula (I), wherein the peak intensity at d = 4.00 Å measured by X-ray diffraction analysis of an unused catalyst. 4 for I0)
The ratio of peak intensity (I 4000) at d = 4.00 Å (I 4000 / I 0) (I 4000 / I 0) measured by X-ray diffraction analysis of the catalyst after use for 2,000 hours is at least 0.8.
And a catalyst for producing molybdenum-vanadium-based acrylic acid.

Although the molybdenum-vanadium catalyst represented by the general formula (I) is produced according to the method of the present invention, it is not clear how the catalyst has excellent activity, selectivity and life. When low-valent oxides, that is, oxides having a low valence state, are used, the interaction with these oxides controls the oxidation state of the catalyst constituent elements, particularly vanadium, and promotes the formation of a molybdenum-vanadium active compound. It is considered to be. The starting compounds of each element used in the production of the catalyst of the present invention will be described for each component of the general formula (I).

Molybdenum (Mo) component: Ammonium paramolybdate, molybdic acid, molybdenum oxide or the like can be used alone or in combination of two or more.

Vanadium (V) component: Ammonium metavanadate is used. If necessary, the vanadium oxide having a valence of more than 0 and less than 5 used together with the ammonium metavanadate includes vanadium monoxide, vanadium dioxide and vanadium trioxide. These can be used alone or in combination of two or more. The vanadium oxide has a ratio of (vanadium of vanadium oxide) / (total vanadium) (atomic ratio) of 0.01 / 1 to 0.5 / 1, preferably 0.1 / 1 to 0.3 / 1. Good to use.

Tungsten (W) component: Ammonium paratungstate, tungstic acid, tungsten oxide or the like can be used alone or in combination of two or more.

Copper (Cu) component: Copper nitrate is used. If necessary, cupric oxide can be used as a copper oxide having a valence of more than 0 and less than 2 used together with the copper nitrate. Copper oxide (copper of copper oxide) / (total copper) (atomic ratio) is 0.01 / 1 to 0.5 /
1, It is good to use so that it may become 0.1 / 1-0.3 / 1.

Component X: Nitrate, carbonate, ammonium salt, sulfate, etc. of each of titanium, zirconium and cerium can be used alone or in combination of two or more.

A further feature of the catalyst of the present invention is that the peak intensity at d = 4.00 angstroms (denoted as d4.00) due to its vanadium-molybdenum phase is increased, while attributable to V ₂ O ₅ . The peak intensity at d = 4.38 angstroms (denoted as d4.38) is reduced. In particular, the ratio of the peak intensities of both (d4.38 / d
4.00) is less than 0.07, a favorable catalytic activity is observed. Further, this ratio (d4.38 / d4.00) is set to be 0.
06 or less, particularly preferably in the range of 0 to 0.05. When this ratio is 0.07 or more, the vanadium-molybdenum phase decreases, so that the catalytic activity decreases.

The preferred catalyst of the present invention has a peak intensity at d = 4.00 Angstroms (designated I 0) as determined by X-ray diffraction analysis of the fresh catalyst.
The ratio (I4000 / I0) of peak intensity (I4000) at d = 4.00 Å measured by X-ray diffraction analysis of the catalyst after 4000 hours of use is at least 0,4.
8, preferably at least 0.85.
Percentage of this ratio (I4000 / I0 (x100) (%))
Is defined as a peak intensity retention, a catalyst having a peak intensity retention of at least 80%, particularly at least 85%, is preferred. In the case of a catalyst having a peak intensity retention of less than 80%, the catalytic activity is reduced due to a small amount of the vanadium-molybdenum phase.

The process for producing the catalyst according to the present invention is characterized in that the source of vanadium is ammonium metavanadate and vanadium oxide having a valence of more than 0 and less than 5 and / or the source of copper is copper nitrate and copper. Except that the catalyst is prepared using a copper oxide having a number greater than 0 and less than 2, it is essentially the same as the method generally used for preparing such a catalyst. For example, it can be produced according to any well-known conventional methods such as an evaporation to dryness method, a granulation method and an extrusion method.

The above-mentioned low-valent oxide may be added and dispersed at any stage of catalyst preparation. In addition, in order to efficiently control the oxidation state of vanadium in the catalyst preparation stage, it is preferable that these low-valent oxides are small particles, and 1 to 150 μm, preferably 5 to 10 μm.
It is preferable to use one having an average particle size of 0 μm.

In the production of the catalyst, inorganic fibers such as glass fibers and various whiskers which are generally well known as having an effect of improving the strength and the degree of pulverization of the catalyst may be added. In order to control the reproducibility of the physical properties of the catalyst well, additives generally known as powder binders such as ammonium nitrate, cellulose, starch, polyvinyl alcohol and stearic acid can be used.

The catalyst composition represented by the above general formula (I) can be used alone, but may be used alone such as alumina, silica-alumina, silicon carbide, titanium oxide, magnesium oxide, aluminum sponge, and diatomaceous earth. It is preferable to carry on an active carrier.

The catalytic gas phase oxidation reaction of acrolein or an acrolein-containing gas using the catalyst for producing acrylic acid obtained by the method of the present invention is not particularly limited.
This type of reaction can be carried out by well-known methods. For example, 1 to 15% by volume, preferably 4 to 1%
2% by volume of acrolein, 0.5 to 25% by volume, preferably 2 to 20% by volume of oxygen, 0 to 30% by volume, preferably 3 to 25% by volume of steam and 20 to 80% by volume, preferably 50 to 50% by volume A mixed gas consisting of 70% by volume of an inert gas such as nitrogen is supplied at 180 to 350 ° C., preferably 200 to 350 ° C.
330 ° C., normal pressure to 10 atm (or reduced pressure), space velocity (STP) 500 to 2000
The reaction may be carried out by contacting with the catalyst composition of the present invention at ⁰ hr ^-1 , preferably 1000 to 10000 hr ^-1 .

As the raw material gas, not only a mixed gas consisting of acrolein, oxygen and an inert gas, but also an acrolein-containing gas obtained by directly oxidizing propylene can be used. In this case, acrylic acid as a by-product contained in the acrolein-containing gas, acetaldehyde, oxidation products such as acetic acid, carbon oxide, propane,
Alternatively, unreacted propylene or the like does not cause any obstacle to the catalyst composition of the present invention.

The above catalytic gas phase oxidation reaction can be carried out in either a fixed bed type or a fluidized bed type.

[0029]

The catalyst obtained by the method of the present invention comprises:
Since high activity is maintained, acrylic acid can be produced in high yield.

The catalyst obtained by the process of the present invention has an excellent catalyst life, and thus maintains its excellent performance for a long time. For this reason, acrylic acid can be produced with a yield as high as that at the start of the reaction without significantly increasing the reaction temperature even after long-time use.

The catalyst obtained by the method of the present invention exhibits excellent performance even under high load conditions, so that acrylic acid can be produced in high yield.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it should be understood that the present invention is by no means restricted by these Examples.

The acrolein, acrylic acid selectivity and acrylic acid single stream yield were determined by the following equations.

Acrolein conversion (%) = (moles of reacted acrolein) / (moles of supplied acrolein) (× 100) Acrylic acid selectivity (%) = (moles of generated acrylic acid) / ( Number of moles of reacted acrolein) (× 100) Single stream yield of acrylic acid (%) = (number of moles of generated acrylic acid) / (number of moles of supplied acrolein) (× 10
0) Example 1 While heating and stirring 2500 ml of water, 350 g of ammonium paramolybdate, 106.3 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved therein. Separately, while stirring and heating 750 ml of water, 87.8 g of copper nitrate was dissolved therein, and 5.9 g of cuprous oxide was added. After mixing the obtained two liquids, the mixture was put into a porcelain evaporator on a hot water bath, and 1000 ml of a spherical carrier made of α-alumina having a diameter of 3 to 5 mm was added thereto.
Was added thereto and evaporated to dryness with stirring to adhere to the carrier, and then calcined at 400 ° C. for 6 hours to obtain a catalyst (1). The composition of the metal element (atomic ratio excluding oxygen, the same applies hereinafter) of the catalyst (1) was as follows.

Mo ₁₂ V _5.5 W ₁ Cu _2.7 400 ml of the catalyst (1) obtained in this way was
A 5 mm stainless steel U-shaped tube was charged, and a mixed gas of 4% by volume of acrolein, 4.5% by volume of oxygen, 25% by volume of steam, and 66.5% by volume of nitrogen was introduced.
The reaction was performed at a contact temperature of 2 ° C. for 2 seconds. The results are shown in Table 1.

According to X-ray diffraction analysis, d = 4.00
Table 1 also shows the relative intensities obtained by setting the peak at angstrom and d = 4.38 angstroms to the peak at d = 4.00 angstroms of catalyst (1) as 100.

Comparative Example 1 A catalyst (2) (the composition was the same as that of the catalyst (1)) was prepared in the same manner as in Example 1 except that copper nitrate was used instead of cuprous oxide. The oxidation reaction was performed in the same manner as in Example 1 except that the catalyst (2) was used instead of the catalyst (1).

Further, in the same manner as in Example 1, X-ray diffraction analysis revealed that d = 4.00 Å and d = 4.00 Å.
The peak at 4.38 angstroms was determined by d =
Table 1 also shows the relative intensities obtained by setting the peak at 4.00 angstroms to 100.

Comparative Example 2 A catalyst (3) (the composition was the same as that of the catalyst (1)) was prepared in the same manner as in Example 1 except that cupric oxide was used instead of cuprous oxide. An oxidation reaction was carried out in the same manner as in Example 1 except that the catalyst (3) was used instead of the catalyst (1). The results are shown in Table 1.

In the same manner as in Example 1, X-ray diffraction analysis showed that d = 4.00 angstroms and d =
The peak at 4.38 angstroms was determined by d =
Table 1 also shows the relative intensities obtained by setting the peak at 4.00 angstroms to 100.

[0041]

[Table 1]

From the results shown in Table 1, the valence of vanadium oxide and copper in which the valence of vanadium is greater than 0 and less than 5 is 0.
When none of the larger and less than 2 copper compounds is used (Comparative Example 1), or when a copper compound having a valence of 2 or more is used (Comparative Example 2), the resulting catalyst has d = 4. 0
It can be seen that the relative intensity of the peak at 0 Å is low, and the catalytic activity is inferior.

Example 2 After the reaction was continued for 4000 hours under the same conditions as in Example 1 using the catalyst (1), the product was collected and analyzed. The results are shown in Table 2.

X-ray diffraction analysis was performed on the catalyst (1) used for 4000 hours in the same manner as in Example 1, and d =
The peak of 4.00 angstroms was set to d = 4.00 angstroms of the unused catalyst (1).
Table 2 shows the relative intensities determined as 0.

Comparative Example 3 An oxidation reaction was carried out in the same manner as in Example 2 except that the catalyst (2) was used instead of the catalyst (1). The results are shown in Table 2.

X-ray diffraction analysis was performed on the catalyst (2) used for 4000 hours in the same manner as in Example 1, and d =
The peak of 4.00 angstroms was set to d = 4.00 angstroms of the unused catalyst (1).
Table 2 shows the relative intensities determined as 0.

Comparative Example 4 An oxidation reaction was carried out in the same manner as in Example 2 except that the catalyst (3) was used instead of the catalyst (1). The results are shown in Table 2.

X-ray diffraction analysis was performed on the catalyst (3) used for 4000 hours in the same manner as in Example 1, and d =
The peak of 4.00 angstroms was set to d = 4.00 angstroms of the unused catalyst (1).
Table 2 shows the relative intensities determined as 0.

[0049]

[Table 2]

From the results shown in Table 2, it can be seen that the catalyst obtained by the method of the present invention has an excellent catalyst life.

Example 3 An oxidation reaction was carried out in the same manner as in Example 1 except that the contact time was changed to 1.5 seconds in the method of Example 1 in which the oxidation reaction was carried out using the catalyst (1). The results are shown in Table 3.

Comparative Example 5 An oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (2) was used instead of the catalyst (1).
The results are shown in Table 3.

Comparative Example 6 An oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (3) was used instead of the catalyst (1).
The results are shown in Table 3.

Example 4 The procedure of Example 1 in which the oxidation reaction was carried out using the catalyst (1), except that the ratios of acrolein and nitrogen in the raw material gas were changed to 5% by volume and 65.5% by volume, respectively. An oxidation reaction was performed in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 7 An oxidation reaction was carried out in the same manner as in Example 4 except that the catalyst (2) was used instead of the catalyst (1).
The results are shown in Table 3.

Comparative Example 8 An oxidation reaction was carried out in the same manner as in Example 4 except that the catalyst (2) was used instead of the catalyst (1).
The results are shown in Table 3.

[0057]

[Table 3]

Example 5 350 g of ammonium paramolybdate, 116 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved in 2500 ml of water while heating and stirring. Separately, while heating and stirring 750 ml of water, 87.8 g of copper nitrate was dissolved therein, 8.2 g of cuprous oxide and 6.6 g of zirconium hydroxide were added. After mixing the obtained two liquids, the mixture was put into a porcelain evaporator on a hot water bath, and a diameter of 3 to 3 of α-alumina was added thereto.
1000 ml of a 5 mm spherical carrier was added, and the mixture was evaporated to dryness with stirring to adhere to the carrier, and then calcined at 400 ° C. for 6 hours to prepare a catalyst (4). The composition of the metal element of this catalyst (4) was as follows.

Mo ₁₂ V ₆ W ₁ Cu _2.9 Zr _{0.25 The} oxidation reaction was carried out in the same manner as in Example 1, except that the catalyst (4) was used instead of the catalyst (1). Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

Example 6 350 g of ammonium paramolybdate, 96.6 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved in 2500 ml of water while heating and stirring. Separately, while heating and stirring 750 ml of water, 87.8 g of copper nitrate was dissolved therein, and 1.2 g of cuprous oxide was added. After mixing the obtained two liquids, the mixture is put into a porcelain evaporator on a hot water bath, and 1000 ml of a spherical carrier made of α-alumina having a diameter of 3 to 5 mm is added thereto. After attaching
The catalyst (5) was prepared by calcining at 400 ° C. for 6 hours. The composition of the metal element of this catalyst (5) was as follows.

Mo ₁₂ V ₅ W ₁ Cu _2.3 An oxidation reaction was carried out in the same manner as in Example 1 except that the catalyst (5) was used instead of the catalyst (1). Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

Example 7 While heating and stirring 2500 ml of water, 350 g of ammonium paramolybdate, 106.3 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved therein, followed by vanadium dioxide 6.9.
g was added. Separately, while heating and stirring 750 ml of water, 87.8 g of copper nitrate and 26 g of titanium oxide were added thereto.
Was dissolved. After mixing the obtained two liquids, the mixture was put into a porcelain evaporator on a hot water bath, and a diameter of α-alumina of 3 was added thereto.
After adding 1000 ml of a 担 体 5 mm spherical carrier and evaporating to dryness with stirring to adhere to the carrier, the mixture was calcined at 400 ° C. for 6 hours to prepare a catalyst (6). The composition of the metal element of this catalyst (6) was as follows.

Mo ₁₂ V ₆ W ₁ Cu _2.2 Ti ₂ An oxidation reaction was carried out in the same manner as in Example 1 except that the catalyst (6) was used instead of the catalyst (1). Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

Example 8 350 g of ammonium paramolybdate, 116 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved in 2,500 ml of water while heating and stirring, and 20.5 g of vanadium dioxide was dissolved.
Was added. Separately, while heating and stirring 750 ml of water,
After dissolving 87.8 g of copper nitrate therein, 10 g of zirconium oxide was added. After mixing the obtained two liquids, the mixture is put into a porcelain evaporator on a hot water bath, and 1000 ml of a spherical carrier made of α-alumina having a diameter of 3 to 5 mm is added thereto.
After evaporating to dryness with stirring and attaching to the carrier, 400
C. for 6 hours to prepare a catalyst (7). The composition of the metal element of this catalyst (7) was as follows.

Mo ₁₂ V _7.5 W ₁ Cu _2.2 Zr _0.5 An oxidation reaction was carried out in the same manner as in Example 1, except that the catalyst (7) was used instead of the catalyst (1). Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

EXAMPLE 9 350 g of ammonium paramolybdate, 96.6 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved in 2500 ml of water while heating and stirring, and then 2.5 g of vanadium trioxide was dissolved.
Was added. Separately, while heating and stirring 750 ml of water,
87.8 g of copper nitrate was dissolved therein. After mixing the two obtained liquids, the mixture was put in a porcelain evaporator on a hot water bath, and α
A spherical support 1000 of alumina having a diameter of 3 to 5 mm
Then, the mixture was evaporated to dryness with stirring to adhere to the carrier, and then calcined at 400 ° C. for 6 hours to prepare a catalyst (8). The composition of the metal element of this catalyst (8) was as follows.

Mo ₁₂ V _5.7 W ₁ Cu _2.2 An oxidation reaction was carried out in the same manner as in Example 1 except that the catalyst (8) was used instead of the catalyst (1). Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

Example 10 While heating and stirring 2500 ml of water, 350 g of ammonium paramolybdate, 96.6 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved therein, followed by 6.9 g of vanadium dioxide.
And 1.1 g of vanadium monoxide were added. Separately, while heating and stirring 750 ml of water, copper nitrate 87.
After dissolving 8 g, 28.4 g of cerium oxide was added. After mixing the obtained two liquids, the mixture was put into a porcelain evaporator on a hot water bath, and a diameter of 3 to 5 mm made of α-alumina was added thereto.
Was added to the support by evaporation to dryness while stirring, and then calcined at 400 ° C. for 6 hours to prepare a catalyst (9). The composition of the metal element of this catalyst (9) was as follows.

Mo ₁₂ V _6.6 W ₁ Cu _2.2 Ce ₁ An oxidation reaction was carried out in the same manner as in Example 1 except that the catalyst (9) was used instead of the catalyst (1). Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

Example 11 While stirring 2500 ml of water while heating and stirring, 350 g of ammonium paramolybdate, 106.3 g of ammonium metavanadate and 44.6 g of ammonium paratungstate were dissolved, and then vanadium dioxide 4.1 was dissolved.
g was added. Separately, while heating and stirring 750 ml of water, 87.8 g of copper nitrate was dissolved therein, and 2.4 g of cuprous oxide was added. After mixing the obtained two liquids, the mixture is put into a porcelain evaporator on a hot water bath, and 1000 ml of a spherical carrier made of α-alumina having a diameter of 3 to 5 mm is added thereto.
After evaporating to dryness with stirring and attaching to the carrier, 400
C. for 6 hours to prepare a catalyst (10). The composition of the metal element of this catalyst (10) was as follows.

Mo ₁₂ V _5.8 W ₁ Cu _{2.4 In} Example 1, the catalyst (10) was used instead of the catalyst (1).
An oxidation reaction was carried out in the same manner as in Example 1 except for using. Table 4 shows the results. Further, X-ray diffraction analysis of the catalyst was performed to determine a peak intensity ratio (d4.38 / d4.00), and the results are shown in Table 4.

[0072]

[Table 4]

Example 12 Catalytic gas phase oxidation was carried out using industrial propylene (purity: 94% or more) in the presence of a molybdenum-bismuth catalyst to obtain 5% by volume of acrolein, 1.2% by volume of unreacted propylene and by-product organic matter. %, Oxygen 4.5% by volume, steam 20% by volume
And a reaction gas mixture comprising 69.3% by volume of a nitrogen-containing inert gas.

Subsequently, the reaction mixture gas was introduced into a reaction tube filled with the catalyst (1), and an oxidation reaction was performed at a temperature of 260 ° C. and a contact time of 2 seconds.

The conversion of acrolein to 9 was calculated assuming that propylene, propane, acrylic acid, acetic acid and the like in the reaction mixture gas introduced into the catalyst (1) did not react.
9.0%, a selectivity to acrylic acid of 94.5%, and a single flow yield to acrylic acid were 93.6%.

It has been confirmed that the catalyst produced according to the present invention can maintain high activity and stably produce acrylic acid from acrolein in high yield.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-47-8360 (JP, A) JP-B-45-30698 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 C07C 57/055 C07B 61/00 300

Claims (7)

(57) [Claims] 1. The following general formula (I) for producing acrylic acid by oxidizing acrolein or an acrolein-containing gas in the gas phase with molecular oxygen or a molecular oxygen-containing gas: Mo _a V _b W _c Cu _{d X e O f (I)} ( wherein, Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, X is at least one element selected from titanium, zirconium and cerium, O is oxygen, a, b, c, d, e and f are Mo,
Represents the number of atoms of V, W, Cu, X and O, and when a = 12, 2 ≦ b ≦ 14, 0 ≦ c ≦ 12, 0 <d ≦ 6, 0 ≦
e ≦ 10, and f is a numerical value determined by the oxidation state of each element). In producing a molybdenum-vanadium-based oxide catalyst represented by the following formulas (1) and (2), A method for producing a catalyst for producing acrylic acid, which comprises producing a catalyst under the conditions of (b) or (c). (A) As a source of vanadium, ammonium metavanadate and a vanadium oxide having a valence of vanadium greater than 0 and less than 5 are used, and copper nitrate is used as a copper source. (B) Ammonium metavanadate is used as a supply source of vanadium, and copper nitrate and a copper oxide having a valence of more than 0 and less than 2 are used as a supply source of copper. (C) As a source of vanadium, ammonium metavanadate and a vanadium oxide having a valence of vanadium greater than 0 and less than 5 are used, and copper nitrate and copper oxidation of a valence of copper greater than 0 and less than 2 are used as a copper source. Use things. 2. The method for producing a catalyst for producing acrylic acid according to claim 1, wherein the vanadium oxide having a valence of vanadium greater than 0 and less than 5 is at least one selected from vanadium monoxide, vanadium dioxide and vanadium trioxide. 3. The method for producing a catalyst for producing acrylic acid according to claim 1, wherein the copper oxide having a valence of copper greater than 0 and less than 2 is cuprous oxide. 4. (Vanadium oxide vanadium) /
(Total vanadium) (atomic ratio) 0.01 / 1 to 0.5 /
The method for producing a catalyst for producing acrylic acid according to claim 1, which is 1. 5. (copper of copper oxide) / (total copper) (atomic ratio)
Is from 0.01 / 1 to 0.5 / 1. 6. The X of the catalyst after 4000 hours of use relative to the peak intensity (I0) at d = 4.00 Angstroms as determined by X-ray diffraction analysis of the fresh catalyst.
Of the peak intensity (I4000) at d = 4.00 Å measured by X-ray diffraction analysis (I4000 / I
The method for producing a catalyst for producing acrylic acid according to claim 1, wherein 0) is at least 0.8. 7. following general formula _{(I): Mo a V b} W c Cu d X e O f (I) ( wherein, Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, X is titanium , At least one element selected from zirconium and cerium, O is oxygen, and a, b, c, d, e and f are Mo,
Represents the number of atoms of V, W, Cu, X and O, and when a = 12, 2 ≦ b ≦ 14, 0 ≦ c ≦ 12, 0 <d ≦ 6, 0 ≦
e ≦ 10, and f is a value determined by the oxidation state of each element), and is a molybdenum-vanadium-based acrylic acid production catalyst represented by the following formula: D = 4.00, determined by X-ray diffraction analysis of the catalyst after 4000 hours of use, against the peak intensity (I0) at 4.00 Å.
A molybdenum-vanadium-based acrylic acid-producing catalyst having a ratio (I4000 / I0) of peak intensity (I4000) in Angstrom of at least 0.8.