KR810000780B1 - Process for regenerating iron-antimony oxide containing catalyst - Google Patents

Abstract

A process for regenerating a deteriorated iron-antimony oxide contains catalyst comprising as essential components (I) iron, (II) antimony, (III) at least one element selected from the group consisting of vanadium, molybdenum and tungsten and (iv) tellurium. The process has the crystalline structure of an iron-antimony oxide compound, is substantially free of free antimony trioxide and contains at least 50 wt % of the original tellurium content of the fresh catalyst which comprises calcining the catalyst under a non-reducing atmosphere at a temperature of from about 600≰ to 950≰C.

Description

Regeneration method of iron-antimony-containing oxide catalyst

FIG. 1 X-ray diffraction diagram of Catalyst 1. FIG.

2 is an X-ray diffraction diagram of the deterioration catalyst of Example 1. FIG.

3 is an X-ray diffraction diagram of the degradation catalyst of Comparative Example 1. FIG.

The present invention relates to a method for regenerating an iron-antimony-containing oxide catalyst whose activity is lowered by being used in oxidizing, ammoxidizing or oxidative dehydrogenation of olefins.

Oxidation and ammoxidation of olefins with iron-antimony oxides containing (I) iron, (II) antimony, (III) vanadium, molybdenum, tungsten, and iron-antimony oxides containing (IV) tellurium as essential components Or useful as catalysts for oxidative dehydrogenation reactions. For example, acrolein is produced by the propylene oxidation, acrylonitrile is produced by the ammoxidation reaction, and methacrolein is produced by the oxidation reaction of isobutene, and methacrylonitrile is produced by the ammoxidation reaction. Or butadiene by oxidative dehydrogenation of butene-1 or butene-2. This is described in Japanese Patent Application No. 46-2804, Japanese Patent Application No. 47-19765, and Japanese Patent Application No. 50-108219.

The catalyst has both good activity and long-lasting activity (catalyst lifetime) and shows excellent catalytic performance. However, the catalyst is inevitably deteriorated when used for a long time. In addition, deactivation may accelerate due to inadequate reaction conditions. Continued use of catalysts whose activity has fallen below the threshold is undesirable from an economic point of view. Large industrial scales, such as acrylonitrile production, have a large effect on this. Sometimes the replacement of a new catalyst results in economic losses. However, it is economically expensive to replace expensive and degraded catalysts with new ones. Therefore, it is very economically beneficial to find an appropriate catalyst regeneration method.

As described above, it is not technically explained at the level of activity and selectivity that the catalyst is not deteriorated or deteriorated, or the deteriorated catalyst is not regenerated or regenerated by the regeneration treatment.

According to the experience of the present inventors, deterioration refers to a case in which the yield of the target product is lowered by 2 to 3% or more relative to the value of using a new catalyst, and regeneration means that the yield of the target product is a new catalyst. It is the same as or higher than that.

It is difficult to tell what causes the lowering of the catalytic activity occurring during the reaction use. Generally, a plurality of causes are combined to cause a decrease in catalytic activity.

For example, even if the cause is identified, it cannot be directly connected to the development of the catalyst regeneration method. Although the regeneration method of the catalyst was examined in various synthetic catalysts, such as unsaturated nitrile, unsaturated aldehyde, and diolefin, it cannot be seen that this method was successful. The only example of such a thing is the antimony-uranium oxide catalyst of Unexamined-Japanese-Patent No. 47-8615.

This method is characterized in that a regeneration gas mixture containing unsynthesized oxygen or oxygen in the form of a target active nitrogen is added to an antimony-uranium oxide catalyst complex at a temperature of 427 ° C to 1038 ° C until the complex is not regenerated. It is characterized in that the contact time. The performance of this catalyst is defined in the surface area of the catalyst and is based on calcination so as not to fall to the optimum critical level. Moreover, regeneration over an extremely wide temperature range is possible. In this respect, it can be said to be a method which is very easy to implement practically.

In some cases regeneration in the reactor is possible and described in the examples. However, the iron-antimony-containing oxide catalyst cannot be regenerated by such an easy method, and as described below, regeneration is not possible unless the catalyst obtained for regeneration is specified, and the regeneration conditions are relatively narrow. Therefore, in consideration of the advantages, the regeneration is not possible without performing the regeneration operation, on the contrary, the catalyst performance may be deteriorated and the original state may not be reduced.

The present inventors have already proposed the method of Japanese Patent Application Laid-Open No. 51-17194 as a novel method for producing a catalyst containing the catalyst of the present invention. This method can also be used as a regeneration method of a deteriorated catalyst with reduced activity, and is an extremely effective method. Examples used for this purpose are also listed. However, the process of impregnation, drying, and calcining of the catalyst component is a little complicated and expensive to operate. In addition, since a new catalyst component is added, there is a problem that the catalyst composition with the original catalyst is changed, or the reaction rate or the optimum reaction condition is likely to occur, which makes it difficult to use the so-called catalyst regeneration method.

The present inventors have studied variously to develop a more convenient regeneration method for an iron-antimony-containing oxide catalyst having reduced activity, and it is estimated that the degradation of the activity of the iron-antimony-containing oxide catalyst is mainly due to reduction degradation. However, it has been found that simply reoxidizing the deterioration catalyst is not a simple catalyst that recovers its activity. Thus, in an iron-antimony-containing oxide catalyst having reduced activity, the catalyst structure has an iron-antimony oxide compound, which is the basic structure of the catalyst, and It was found that when the antimony trioxide of the glass was not substantially produced, the catalytic activity was recovered and regenerated when calcined under specific conditions.

The present invention has been completed based on the above theory. In other words, the regeneration method of the iron-antimony-containing oxide catalyst according to the present invention is used in the production of unsaturated, aldehyde, unsaturated nitrile, or diolefin by olefin oxidation method, ammoxidation reaction, oxidative dehydration reaction, and reduced activity ( I) firing a metal oxide catalyst comprising at least one element selected from iron, (II) antimony, (III) vanadium, molybdenum and tungsten and (I)-(IV) elements of (IV) tellurium When regenerating the catalytic activity, the catalyst has a crystal structure of the antimony iron tetraoxide compound and does not substantially produce antimony trioxide of glass, which is used in the preparation of the catalyst in a temperature range of 600 ° C to 950 ° C. It is characterized by firing in a non-reducing atmosphere at temperatures below the final firing temperature.

The iron-antimony-containing oxide catalyst of the present invention contains at least one element selected from iron, antimony and vanadium, molybdenum, tungsten, and tellurium, but for various purposes, copper, magnesium, zinc, lanthanum, cerium, aluminum Or a catalyst in which a fluorine selected from chromium, manganese, cobalt, nickel, bismuth, tin, phosphorus and boron is added as necessary or more. This catalyst has an iron-antimony oxide compound (Fe, SbO ₄ ) as the main crystal structure of this catalyst. The composition range of the catalyst is as follows. The composition is expressed as an atomic ratio as follows.

Fe1 ₀ Sba Meb Tec Qb Oe

Wherein Me is at least one element selected from vanadium, molybdenum and tungsten, and Q is at least one selected from copper, magnesium, zinc, lanthanum, cesium, aluminum, chromium, manganese, cobalt, nickel, bismuth, tin, phosphorus and boron And a is 5 to 60, b is 0.001 to 10, c is 0.1 to 10, d is 20 or less, and e represents the number of oxygen corresponding to the oxides formed by combining the respective components.

The present invention regenerates the deterioration catalyst when the iron-antimony-containing oxide catalyst is reduced during the use of the reaction or under certain conditions to decrease the activity, but any deterioration catalyst cannot be recovered by regeneration. In the present invention, the regenerable catalyst is iron, the basic structure of the present catalyst crystal structure of the catalyst of the deteriorated catalyst of pictures of antimony oxide active compound (FeSbo _4), and also antimony trioxide in the glass (Sb ₂ o ₃₎ It should not be created. The deterioration catalyst in which the structure of the iron-antimony oxide compound in the catalyst is destroyed by the reduction of the under or the antimony trioxide is produced by the reduction is impossible to regenerate. This can be determined by X-ray diffraction of the catalyst.

In the iron-antimony-containing oxide catalyst according to the present invention, the terium component may be lost by reduction. The rate, speed, etc. of this loss depend on the reaction conditions, the equipment conditions, and the like. For example, when the catalyst is used under very severe conditions, the terium component in the catalyst is relatively largely lost when the catalyst is reduced by mistake. The performance of the catalyst is not necessarily proportional to the terium content, but the activity may be lowered as described above.

The present invention can be regenerated even when the content of the titanium component in the catalyst is less than that of the new catalyst or in a very wide range of the terium content. The reason for the settlement is not clear, but it is thought to be due to the possibility that the terium component in the deterioration catalyst moves in the catalyst (diffusion to the surface of the catalyst) during catalyst regeneration. However, for catalysts with reduced terium above the threshold, further regeneration is not possible and only a low performance is achieved even with regeneration by the method of the present invention. Usually, such a case is difficult to regenerate. However, when the terium content of the deterioration catalyst becomes less than about 50% of the terium content of the new catalyst, regeneration is generally impossible. According to the method of the present invention, the performance of the catalyst can be greatly restored, but the performance level of the new catalyst can hardly be reached. In addition, catalysts whose terium content is less than about 50% of the new catalyst content by some conditions (reduction, excessive firing, etc.) at the time of regeneration are not sufficiently regenerated.

In the present invention, the catalyst is calcined and regenerated only for the measured deterioration catalyst as described above, but at the temperature of 600 ° C. to 900 ° C. as the firing conditions at that time, and moreover, at a temperature near the final firing temperature at the time of preparing the catalyst, it is non-reducing. It is necessary to bake in the atmosphere. Deteriorated catalysts are difficult to find by conventional means and it is not clear how they are changing, but it is thought that they usually lead to structural changes in the active site of the catalyst surface. Any deterioration catalyst cannot be regenerated at a temperature below 600 ° C., but in some cases, complete oxidation activity may be increased as such treatment. As a result, the structure recovery reaction of this catalyst shows that the activation energy is large and the temperature effect is enormous. At temperatures above 950 ° C, catalyst performance deteriorates. This is not a decrease in the reaction rate which causes only the disappearance of the active site due to sintering, but a significant decrease in the selectivity, a change in the reaction rate, a decrease in the catalyst strength, and the like cannot be reproduced. In addition, the catalyst according to the present invention is calcined under optimum firing conditions that vary depending on the composition and the manufacturing method at the time of its production.

Therefore, the temperature and time conditions at the time of regeneration must be taken into consideration. In other words, it should be carried out under milder conditions than during manufacture. The temperature at the time of regeneration is preferably carried out at a temperature near or below the firing temperature during the production of this catalyst. When the firing temperature is higher than the firing temperature at the time of catalyst production, the firing time must be shortened. The relationship between temperature and time is somewhat different depending on the catalyst, and it is difficult to express it numerically. Normally, the regeneration temperature is preferably selected in the temperature range of 150 ° C to + 20 ° C, based on the final firing temperature at the time of preparation of the catalyst.

However, as mentioned above, it is less than 600 degreeC at low temperature, and it is up to 950 degreeC at high temperature. Moreover, it is good to select a baking time suitably in the range of 10 minutes-about 10 hours.

The atmosphere during catalyst firing according to the present invention needs to be performed under a non-reducing atmosphere. It goes without saying that there is a possibility of deterioration acceleration under a reducing atmosphere. The oxidative atmosphere is not essential here as atmospheric conditions. In practice, it is convenient to carry out while introducing air. For example, it may be carried out in the presence of nitrogen, helium, cutlet carbonate and the like. Although it is assumed that the cause of the deterioration is reduction deterioration, it is difficult to understand that the performance is restored by applying the firing temperature conditions in the inert gas. The reaction during regeneration may be referred to as regeneration of the catalyst surface structure rather than reoxidation of the catalyst. In addition, since the change due to deterioration occurs only in the surface layer of the catalyst, the adsorbed oxygen before regeneration does not necessarily contribute.

But this is not clear. It is also not necessary to measure the conditions as in this case if only removing organic matter attached to the catalyst. Some examples are given for non-reducing gases, but steam cannot be used. Although somewhat contained in the non-reducing gas may be acceptable, the amount of the non-reducing gas is increased, especially when the temperature is high, the sintering of the catalyst is significantly promoted, and it is difficult to recover the catalytic performance.

In the present invention, the apparatus for calcining the catalyst is not particularly limited, and stationary furnaces, turnnels, rotary furnaces, and flow furnaces commonly used in the production of catalysts can be used. The temperature distribution in the furnace must be carried out, and the problem is the real temperature, so this should be fully considered. Inadvertent advantages arise in some cases even if they seem to meet the conditions of the present invention. In view of this, a flow catalyst which is easy to have a uniform temperature distribution and which is convenient for using a flow path is preferable.

The present inventor has already shown in Special Office 50-3750 that it is preferable to use a fluid-fired furnace in the production of a series of catalysts containing this type of catalyst. This method can be adopted as required for carrying out the catalyst regeneration method according to the present invention. In this way, the regenerated catalyst recovers to the same extent as the new catalyst in yield and reaction rate on the active side, and the optimum reaction conditions hardly change.

In addition, since the catalytic properties hardly change, for example, the change in fluidization properties is extremely small and therefore does not adversely affect the reaction performance. Therefore, not only can be used the same as the new catalyst, it can also be used in combination with it. Regenerated catalysts are prioritized for recovery of performance by activity tests but may also be partially identified by their physical properties. The specific surface area of the regenerated catalyst is within ± 30% of the specific surface area of the unused catalyst. When the specific surface area exceeds the above range, deterioration catalyst or regeneration condition which is not the object of the present invention becomes an inappropriate catalyst.

Such a catalyst does not correspond to the regeneration catalyst according to the present invention. Further, the catalyst regeneration method of the present invention can repeat the operation several times in the range of the deterioration catalyst defined above.

As described above, the method for regenerating the iron and antimony-containing oxide catalyst according to the present invention is very limited in both the reproducible catalyst and the regeneration conditions, but the industrial implementation is sufficiently possible, and the economic effect obtained as a result is extremely large. Hereinafter, the configuration and effects of the present invention are shown in detail by Examples and Comparative Examples, but the present invention is not limited only to these Examples.

[Catalyst 1]

A flow catalyst having an empirical formula of W _{0 25} Te _{1 0} Fe ₁₀ Sb ₂₅ O _{67 8} (SiO ₂ ) _{30 was} prepared as follows.

1.95 kg of metal antimony powder having a particle size of 100 μm or less is gradually added to 7.2 L of nitric acid having a specific gravity of 1.38 heated to about 80 ° C. After confirming that the antimony was completely oxidized, the excess nitric acid was removed, and the produced antimony nitrate oxide was washed 5 times with 2 liters of water, transferred to a ball mill and ground for 3 hours (I).

Specific gravity 1

3 l of 1.38 nitric acid is mixed with 4 l of water, warmed to about 80 ° C., and 0.385 kg of electrolytic iron is slowly added thereto. Iron is completely dissolved (II).

41.8 g of ammonium tungstate are dissolved in 1.5 L of water (III).

147 g of telluric acid are dissolved in 1 L of water (IV). 3.84 kg of silica sol containing 30% by weight of silicon dioxide is weighed out (V).

The above-mentioned (I), (II), (III), (IV) and (V) are mixed and thoroughly stirred, while slowly adding 15% by weight of ammonia water to adjust the pH value to 2. The slurry thus obtained is heated to 100 ° C. for 4 hours with sufficient stirring, and then the slurry is spray dried according to a conventional method. The obtained fine spherical particles are fired at 200 ° C. for 4 hours, at 400 ° C. for 4 hours, and at 830 ° C. for 4 hours.

X-ray diffraction confirmed that the crystal structure of this catalyst had no antimony trioxide in the glass and antimony tetraoxide as the main component, as shown in FIG.

[Catalyst 2]

Experimental Cu _{0 5} MO _{0 25} Te _{0 1} Fe ₁₀ Sb ₂₅ O ₆₈ (SiO) ₆₀ A catalyst with ₆₀ was prepared as follows.

Weigh out 2.91 kg of antimony trioxide powder (20 µ or less) (I).

Weighing 0.447 kg of electrolytic iron powder, 3.2 l of nitric acid (specific gravity 1.38) was mixed with 2 l of water.

35.3 g of ammonium molybdate is weighed out and then 500 ml of water is dissolved. Again 184 g of terluic acid are dissolved therein (III).

Weigh out 9.91 kg of silica sol (containing 30 wt% of silicon dioxide) (IV).

97 g of copper nitrate is dissolved in 500 ml of water (V). The above (I), (II), (III), (IV) and (V) are mixed and stirred well, and then adjusted to pH 2 by adding 15% ammonia water thereto. It is stirred well and heated at 100 ° C. for 4 hours. The slurry thus produced is spray dried according to a conventional method. The obtained fine constituent particles were calcined at 250 ° C. for 2 hours and 400 ° C. for 2 hours, respectively, and finally calcined at 810 ° C. for 4 hours in a fluid fired furnace.

[Catalyst 3]

A catalyst having an empirical formula of W _{0 5} Te _{1 0} CO _{3 0} Fe ₁₀ Sb ₁₀ O ₇₂ (SiO ₂ ) ₆₀ was prepared in the same manner as in Example 2. However, tungsten ammonium is used instead of ammonium molybdate and cobalt nitrate is used instead of copper nitrate. The final firing is carried out at 810 ° C. for 3 hours in a fluid fired furnace.

[Catalyst 4]

A catalyst having an empirical formula of V _{0 1} , MO _{0 5} W _{0 3} Te _{2 3} Cu ₃ Fe ₁₀ Sb ₂₀ O _{65 25} (SiO ₂ ) ₁₀₀ was prepared in the same manner as in Catalyst 2. However, ammonium metavanadate is used as a vanadium component raw material, and ammonium tungstate is used as a tungsten component raw material. The best firing is carried out for 5 hours at 770 ° C. in a fluid fired furnace.

[Catalyst 5]

A catalyst having an empirical formula of Mo _{0 3} W _{0 5} Te _{2 0} Mg ₄ Fe ₁₀ Sb ₂₅ O _{72 4} (SiO ₂ ) ₅₀ was prepared in the same manner as in Catalyst 1. However, ammonium molybdate is used as a molybdenum component raw material, and magnesium nitrate is used as a magnesium raw material. The final firing is carried out for 5 hours at 760 DEG C in a fluid fired furnace.

According to the X-ray diffraction, the catalysts of the catalysts 2 to 5 had a difference in strength, but all of them had a major crystal structure, such as the catalyst 1, and no antimony trioxide of glass was identified.

Using this catalyst, the experiment of the following Example and the comparative example was done.

The activity test conditions of the catalyst are as follows.

[Activity test condition]

The catalyst is filled in a fluidized bed reactor having an inner diameter of about 55 mm and a blocker installed therein to improve contact efficiency. In this reactor, a gas having the following composition is introduced so that the apparent gas line velocity is 15 cm / sec.

O ₂ (feed as air) /propylene=2.2 (molar ratio)

NH ₃ /propylene=1.15 (molar ratio)

However, the apparent contact time is defined as follows.

Apparent contact time (Q) (Sec) =

^* 1: based on bulk density of catalyst

Example 1

The activity test is carried out using the catalyst 1 under the above conditions. If the oxygen / propylene molar ratio is further reduced during the test, the oxygen concentration in the dry gas (N ₂ + CO ₂ + CO + propylene + O ₂ ) at the outlet is zero. The reaction is held in this state for about 30 minutes and then reduced to the original test conditions. At the beginning of the test, the acrylonitrile yield was 80%, but the activity was reduced by the reaction under such reducing conditions, and the yield was lowered to 76%. When the catalyst was taken out from the reactor, the color tone was black compared to the catalyst before the test. However, X-ray diffraction showed that the crystal structure of the catalyst was mainly antimony tetraoxide, and the generation of antimony trioxide was not observed. The color was black. However, according to the X-ray rotation, as shown in FIG. 2, the crystal structure of the catalyst was mainly antimony tetraoxide, and no generation of antimony trioxide in glass was observed.

The deterioration catalyst is calcined and regenerated for 4 hours at 320 ° C. in the presence of air in Tennelo.

Example 2

The activity test is carried out using the catalyst 2 under the above conditions. The same reactor as above is used, but here the internal blockage plate is removed and the test is carried out for about 750 hours with an apparent gas stone velocity of 5 cm / sec. During this time, the selectivity of acrylonitrile gradually decreases, and the oxygen concentration in the dry gas at the outlet becomes 0.2 to 1.5%, but the reaction is continued in this state. After a long time test, the catalyst activity test is carried out under the conditions of the above activity test. The results showed that the yield of acrylonitrile was 77% at the beginning of the test as shown in Table 1, but it was 73% with a decrease of about 4%. However, X-ray diffraction showed that the main crystal structure of the catalyst was antimony tetraoxide and no antimony trioxide was generated.

This deterioration catalyst was put into an external heat-type flow path having an inner diameter of 4 inches and calcined and regenerated for 2 hours at 800 ° C in the presence of air.

Example 3

Catalyst 3 was used to charge the catalyst in a flow reactor having an internal diameter of 8 inches and to react for a long time under the following conditions. The reaction time is 1820 hours.

Air / Propylene = 10.0 (mol / mol) Gas Line Speed = 18 (cm / sec)

Ammonia / propylene = 1.1 (mol / mol) Reaction temperature = 460 (℃)

Reaction pressure = 0.5 (kg / ㎠ G) Apparent contact time = 8 (sec)

When the unused catalyst and the catalyst used for the long time reaction were each tested as described above, the yield of acrylonitrile decreased by 2% for the catalyst used for the long time reaction. However, X-ray diffraction showed that the main crystal structure of the deterioration catalyst was antimony tetraoxide and no antimony trioxide was generated in the glass. 2 kg of this deterioration catalyst was taken and regenerated under the following conditions using the same flow path as used in Example 2, respectively.

(1) 790 ° C 6 hours (3) 810 ° C 1 hour

(2) 800 ℃ 4 hours

Example 4

The activity test is carried out using the catalyst 4 under the above conditions. Due to the failure of the compressor during the activity test, the air inflow was reduced to about 70%. For this reason, although reduced to normal reaction conditions, the yield of acrylonitrile fell 3%. However, X-ray diffraction showed that the main crystal structure of the deterioration catalyst was antimony tetraoxide, and no antimony trioxide was produced. This deterioration catalyst uses the same flow furnace as used in Example 2, in which nitrogen gas is introduced instead of air, and calcined and regenerated at 770 ° C. for 2 hours.

Example 5

The activity test is carried out using the catalyst 5 under the above conditions. Isobutylene is introduced simultaneously into the reaction system and the reaction is continued to be maintained. Since the yield of acrylonitrile decreases gradually, the introduction of isobutylene is stopped and reduced to the initial reaction conditions. However, the yield of acrylonitrile decreases by 2%. However, X-ray diffraction showed that the main crystal structure of this deterioration catalyst was antimony tetraoxide, and no antimony trioxide was produced. The catalyst was removed from the reactor and regenerated by firing at 750 ° C. for 4 hours in the presence of air using the same flow path as used in Example 2.

Comparative Example 1

About 2 kg of catalyst 1 is taken and gradually raised in a rotary furnace under propylene inlet and maintained at 450 ° C. for 30 minutes. The catalyst taken out from the reactor is black and fine earth crystals are attached to the surface of the catalyst. X-ray diffraction confirmed the production of antimony trioxide in the glass (FIG. 3).

This deterioration catalyst was put in a tunnel furnace as in Example 1 and calcined at 820 ° C. for 4 hours in air. However, activity is not restored. X-ray diffraction results of the regenerated catalyst were different from those of the unused catalyst.

Comparative Example 2

The activity test is carried out using the catalyst 2 under the above conditions. Here, the operation of discontinuously introducing air is repeated several times for about 50 hours. As a result, even under reduced reaction conditions, the yield of acrylonitrile was only 32%, indicating that the activity was greatly deteriorated. This deterioration catalyst was calcined at 800 ° C. for 2 hours under inflow of air from the flow furnace as in Example 2. But activity does not recover satisfactorily. Compositional analysis shows that the tellurium content is reduced to 46% of the unused catalyst.

Comparative Example 3

The deterioration catalyst produced in Example 3 is subjected to regeneration treatment under the same conditions as in Example 3. However, baking is performed at 500 degreeC for 5 hours.

[Comparative Example 4]

The deterioration catalyst produced in Example 3 is subjected to regeneration treatment under the same conditions as in Example 3. However, firing is performed at 1000 ° C. for 1 hour.

[Comparative Example 5]

The deterioration catalyst produced in Example 3 was calcined at 800 ° C. for 4 hours in a rotary furnace. The catalyst after firing was substantially excessively calcined and the color tone was whiter than that of the catalyst of the condition (2) of Example 3. The specific surface area is measured and is reduced to 67% of the unused catalyst. In other words, this regenerated catalyst was 30% less than the comparative area of the unused catalyst.

The results of the activity test of the catalysts in the above Examples and Comparative Examples were recorded in the first table.

TABLE 1

Claims (1)

(I) iron, (II) antimony, (III) vanadium, molybdenum, tungsten, used in the preparation of unsaturated aldehydes, unsaturated nitriles or diolefins by oxidation, ammoxidation or oxidative dehydrogenation of olefins Determination of the antimony iron oxide compound when regenerating catalytic activity by calcining a metal oxide catalyst containing at least one element selected from and (I)-(IV) elements of (IV) tellurium as essential components The catalyst, having a structure and substantially free of antimony trioxide in the glass, is fired in a non-reducing atmosphere at a temperature in the range of 600 ° C. to 950 ° C., at temperatures near to or below the final firing temperature used in the preparation of the catalyst. Regeneration method of the iron-antimony-containing oxide catalyst, characterized in that.

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