JP2011235270A - Mixed catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixed catalyst for gas-phase catalytic oxidation or gas-phase catalytic ammoxidation reaction of propane or isobutane, wherein it is possible to obtain, from propane or isobutane and at a high yield, unsaturated acid or unsaturated nitrile, respectively.SOLUTION: The mixed catalyst for gas-phase catalytic oxidation or gas-phase catalytic ammoxidation reaction of propane or isobutane contains a composite oxide represented by compositional formula (1) and a tungsten compound at a ratio represented by formula (2). The compositional formula (1) is MoVNbSbWZO. (In formula (1), Z represents at least one element selected from among La, Ce, Pr, Yb, Y, Sc, Sr, and Ba; a, b, c, d, e, and n represent the atom ratio of each element per 1 atom of Mo such that a is 0.01≤a≤1, b is 0.01≤b≤1, c is 0.01≤c≤1, d is 0.001≤d≤1, e is 0≤e≤1, and n is a number that is determined by means of the atomic valence of the constituent metal). Formula (2) is 0.001<w<0.3. (In formula (2), w represents the atom ratio of tungsten within the tungsten compound as the atom ratio per 1 atom of Mo in the composite oxide).

Description

  The present invention relates to a mixture catalyst and a method for producing an unsaturated acid or an unsaturated nitrile using the mixture catalyst.

Conventionally, a method for producing a corresponding unsaturated carboxylic acid or unsaturated nitrile by subjecting propylene or isobutylene to gas phase catalytic oxidation or gas phase catalytic ammoxidation reaction is well known. In recent years, attention has been focused on a method for producing a corresponding unsaturated carboxylic acid or unsaturated nitrile by subjecting propane or isobutane to gas phase catalytic oxidation or gas phase catalytic ammoxidation instead of propylene or isobutylene.
Up to now, various oxide catalysts have been proposed as catalysts used for gas phase catalytic ammoxidation. Generally, an oxide obtained by mixing and calcining molybdenum, vanadium, etc., if necessary, is used as a catalyst as it is. However, in producing an unsaturated carboxylic acid or an unsaturated nitrile, the catalyst after calcining is further added. Post-processing techniques have also been studied.
For example, Patent Document 1 discloses that a Mo—V—Sb / Te catalyst is tungsten, molybdenum, chromium, zirconium, titanium, niobium, tantalum, vanadium, boron, bismuth, tellurium, palladium, cobalt, nickel, iron, phosphorus, silicon. A method of impregnating a solution containing one or more elements selected from the group consisting of rare earth elements, alkali metals, and alkaline earth metals is disclosed.
Patent Document 2 discloses a method for producing a modified mixed metal oxide by bringing a mixed metal oxide catalyst into contact with water and optionally an aqueous metal oxide precursor, and firing the resulting modified mixed metal oxide. Has been.
Patent Document 3 discloses a technique of immersing tungsten and manganese in a Mo—V—Sb—Nb-based catalyst.
In Patent Document 4, a catalyst such as an antimony compound, a molybdenum compound, a tellurium compound, or a tungsten compound is mixed and used for the reaction, or the catalyst or catalyst precursor is mixed with a modifier and calcined, and then used for the reaction. A technique is disclosed.

Japanese Patent Laid-Open No. 10-028862 JP 2008-066221 A International Publication No. 2007-119376 Pamphlet International Publication No. 2009-048553 Pamphlet

However, when the present inventors used the oxide catalyst disclosed in Patent Documents 1 to 3 for the gas phase catalytic oxidation or gas phase catalytic ammoxidation reaction of propane or isobutane, none of the catalysts still contained the target product. The rate was insufficient.
In the production methods described in Patent Documents 1 to 4, it is described that the performance is improved by impregnating or immersing tungsten in a Mo-V-Te / Sb-based composite oxide that is still active. However, the composite oxide before impregnation or immersion does not contain tungsten, and has not led to a catalyst with a high yield of the target product.
In view of the above circumstances, the problem to be solved by the present invention is a catalyst for gas phase catalytic oxidation or gas phase catalytic ammoxidation reaction of propane or isobutane, and the corresponding unsaturated acid or unsaturated nitrile from propane or isobutane Is provided in a high yield, and a process for producing an unsaturated acid or an unsaturated nitrile using the mixture catalyst is provided.

  As a result of intensive studies to solve the above problems, the present inventors have found that when Mo—V—Nb—W composite oxide and tungsten compound are mixed, W contained in the composite oxide before mixing. And the tungsten compound have been found to have different functions in the mixture catalyst. As a result, the mixture catalyst containing the Mo—V—Nb—W-based composite oxide and the tungsten compound in a specific ratio has the above-mentioned problems. The present invention has been completed by finding out that the problem can be solved.

  That is, the present invention is as follows.

[1]
Mixture catalyst for gas phase catalytic oxidation reaction or gas phase catalytic ammoxidation reaction of propane or isobutane,
A mixed catalyst containing a composite oxide represented by the following composition formula (1) and a tungsten compound in a proportion of the following formula (2);
_{Mo 1 V a Nb b Sb c} W d Z e O n (1)
(In the formula (1), Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba, and a, b, c, d, e, and n are Mo1. Indicates the atomic ratio of each element per atom, a is 0.01 ≦ a ≦ 1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and d is 0.001 ≦ d ≦ 1. E represents 0 ≦ e ≦ 1, and n represents a number determined by the valence of the constituent metal.)
0.001 <w <0.3 (2)
(In formula (2), w represents the atomic ratio of tungsten in the tungsten compound as the atomic ratio per Mo atom in the composite oxide).
[2]
The mixture catalyst according to [1] above, wherein the tungsten compound contains tungsten oxide.
[3]
The mixture catalyst according to the above [1] or [2], which is used in a fluidized bed reaction.
[4]
A method for producing an unsaturated acid or an unsaturated nitrile, comprising:
A production method comprising a step of contacting propane or isobutane with oxygen or propane or isobutane with oxygen and ammonia with the mixture catalyst according to any one of the above [1] to [3].
[5]
The production method of the above-mentioned [4], wherein propane or isobutane and oxygen, or propane or isobutane, oxygen and ammonia are heated to 400 ° C. or more in a contact state.

  By using the mixture catalyst of the present invention, the corresponding unsaturated acid or unsaturated nitrile can be produced in high yield from propane or isobutane.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

The mixture catalyst of this embodiment is
Mixture catalyst for gas phase catalytic oxidation reaction or gas phase catalytic ammoxidation reaction of propane or isobutane,
A mixed catalyst containing a composite oxide represented by the following composition formula (1) and a tungsten compound in a proportion of the following formula (2);
_{Mo 1 V a Nb b Sb c} W d Z e O n (1)
(In the formula (1), Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba, and a, b, c, d, e, and n are Mo1. Indicates the atomic ratio of each element per atom, a is 0.01 ≦ a ≦ 1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and d is 0.001 ≦ d ≦ 1. E represents 0 ≦ e ≦ 1, and n represents a number determined by the valence of the constituent metal.)
0.001 <w <0.3 (2)
(In formula (2), w represents the atomic ratio of tungsten in the tungsten compound as the atomic ratio per Mo atom in the composite oxide).

  It does not specifically limit as a manufacturing method of the mixture catalyst of this embodiment, The example is demonstrated below.

[1] Method for Producing Mixture Catalyst The composite oxide contained in the mixture catalyst of the present embodiment can be produced, for example, by the following method.
(A) Production of complex oxide A complex oxide is produced by the following three steps.
(1) Step for preparing raw material preparation liquid by preparing raw materials (2) Step for drying raw material preparation liquid obtained in step (1) to obtain dry powder (3) Drying obtained in step (2) Process of firing powder to obtain composite oxide

  The preparation in the above step (1) refers to dissolving or dispersing a composite oxide raw material in an aqueous solvent, and the raw material refers to a compound containing a constituent element of the composite oxide.

It does not specifically limit as a raw material, For example, the following compound can be used.
As the raw material for Mo and V, but are not limited to, respectively, be used ammonium heptamolybdate _{[(NH 4) 6 Mo 7} O 24 · 4H 2 O] and ammonium metavanadate [NH ₄ VO _3] suitably it can.

As a raw material of Nb, niobic acid, an inorganic acid salt of niobium and an organic acid salt of niobium can be suitably used, and niobic acid is particularly preferable. Niobic acid is a compound represented by Nb ₂ O ₅ .nH ₂ O and is also called niobium hydroxide or niobium oxide hydrate. Furthermore, it is also preferable to use an Nb raw material liquid having a dicarboxylic acid / niobium molar ratio of 1 to 4 as the Nb raw material. In this case, oxalic acid is preferable as the dicarboxylic acid.

The raw material of Sb is not particularly limited, but diantimony trioxide [Sb ₂ O ₃ ] is preferable.

  There is no restriction | limiting in particular as a raw material of W, The compound which solubilized the compound containing W and the metal of W with a suitable solvent can be used. Examples of the compound containing W include W ammonium salt, nitrate, carboxylate, ammonium carboxylate, peroxocarboxylate, ammonium peroxocarboxylate, ammonium halide salt, halide, acetylacetonate, alkoxide and the like. Among these, water-soluble raw materials such as nitrates and carboxylates are preferably used.

  The raw material for component Z is not particularly limited as long as it is a substance containing at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba. Alternatively, a solution obtained by solubilizing the metal of the above element with an appropriate solvent can be used. Examples of the compound containing the above element include nitrates, carboxylates, ammonium carboxylates, peroxocarboxylates, ammonium peroxocarboxylates, ammonium halides, halides, acetylacetonates, alkoxides, and the like of the above metal elements. Among these, water-soluble raw materials such as nitrates and carboxylates are preferably used.

  When the composite oxide is a silica-supported material, silica sol can be used as the silica raw material, but powdered silica can also be used for a part or all of the silica raw material. The powder silica is preferably produced by a high heat method. The powder silica can be easily added to and mixed in the slurry by being dispersed in water in advance. There is no restriction | limiting in particular as a dispersion method, A general homogenizer, a homomixer, an ultrasonic vibrator, etc. can be disperse | distributed individually or in combination.

Below, the suitable manufacture example of complex oxide containing process (1)-(3) is demonstrated.
(Step (1): Step of preparing raw materials)
In the step (1), Mo compound, V compound, Sb compound, W compound, component Z compound, and other ingredients as necessary are added to water and heated to prepare an aqueous mixture (I). At this time, the inside of the container for preparing the mixed liquid (I) may be a nitrogen atmosphere. Next, the Nb compound and dicarboxylic acid are heated and stirred in water to prepare a mixed solution (B ₀ ). Further, hydrogen peroxide is added to the mixed solution (B ₀ ) to prepare an aqueous mixed solution (II). At this time, H ₂ O ₂ / Nb (molar ratio) is preferably 0.5 to 20, and more preferably 1 to 10.

  Next, the aqueous mixture (I) and the aqueous mixture (II) are suitably mixed according to the target composition to obtain the aqueous mixture (III). The obtained aqueous mixed liquid (III) is aged in an air atmosphere to obtain a slurry-form raw material preparation liquid (hereinafter also simply referred to as “slurry”).

Here, the aging of the aqueous mixed liquid (III) means that the aqueous mixed liquid (III) is allowed to stand for a predetermined time or is stirred. When manufacturing complex oxides industrially, the processing speed of the spray dryer is usually limited, and after a part of the aqueous mixed liquid (III) is spray dried, until the spray drying of all the mixed liquid is completed. Takes time. During this time, aging of the liquid mixture that has not been spray-dried is continued. Therefore, the aging time includes not only the aging time before spray drying but also the time from the start to the end of spray drying.
The aging time is preferably 90 minutes or more and 50 hours or less, and more preferably 90 minutes or more and 6 hours or less from the viewpoint of the yield of the target product.
The aging temperature is preferably 25 ° C. or higher from the viewpoint of preventing condensation of the Mo component and precipitation of V. Moreover, 65 degreeC or less is preferable from the viewpoint of preventing hydrolysis of the complex containing Nb and hydrogen peroxide from occurring too much and forming a slurry of a preferable form. Therefore, the aging temperature is preferably 25 ° C. or more and 65 ° C. or less, and more preferably 30 ° C. or more and 60 ° C. or less.

  The atmosphere in the container at the time of aging preferably has a sufficient oxygen concentration. Insufficient oxygen may make it difficult for a substantial change in the aqueous mixture (III) to occur. The oxygen concentration in the gas phase portion in the container (hereinafter also referred to as “gas phase oxygen concentration”) is preferably 1 vol% or more.

  The gas phase oxygen concentration in the container can be measured by a general method, for example, it can be measured using a zirconia oxygen analyzer. The place where the gas phase oxygen concentration is measured is preferably near the interface between the aqueous mixed liquid (III) and the gas phase. For example, it is preferable to measure the gas-phase oxygen concentration at the same point three times within 1 minute, and use the average value of the three measurement results as the gas-phase oxygen concentration.

  Although it does not specifically limit as a dilution gas for reducing a gaseous-phase oxygen concentration, Nitrogen, helium, argon, a carbon dioxide, water vapor | steam etc. are mentioned, Industrially, nitrogen is preferable. The gas for increasing the gas phase oxygen concentration is preferably pure oxygen or air with a high oxygen concentration.

  It is considered that some kind of change occurs in the redox state of the components contained in the aqueous mixed liquid (III) by the aging described above. Some kind of change is also suggested from the fact that a change in the color of the aqueous mixture (III), a change in redox potential, and the like occur during aging. As a result, a difference also appears in the composite oxide obtained depending on the presence or absence of aging in the atmosphere having an oxygen concentration of 1 to 25 vol% and not less than 90 minutes and not more than 50 hours. For example, during aging, it is extremely difficult to accurately identify the morphological changes of the components in the liquid, but composite oxides with different aging times are produced, and the yield of the target product is increased using this composite oxide as a catalyst. By evaluating, it can be seen that the aging time applied to the catalyst with a good yield is preferable, and at this time, it can be inferred that a slurry of some preferable form was formed.

  The redox potential of the aqueous mixture (III) is dominated by the potential 600 mV / AgCl of the aqueous raw material liquid (II), and the oxalic acid Nb peroxide and other metal components contained in the aqueous raw material liquid (II) are oxidized in some way. It is considered that the potential decreases with time due to the reduction reaction. The redox potential of the aqueous mixture (III) is preferably 450 to 530 mV / AgCl, more preferably 470 to 510 mV / AgCl.

  From the viewpoint of preventing the oxidation-reduction state in the slurry stage from becoming overoxidized without slowing the progress of the oxidation-reduction reaction that affects the change in the oxidation-reduction state of the components contained in the aqueous mixture (III). The oxygen concentration inside is preferably 1 vol% or more. On the other hand, from the viewpoint of preventing the oxidation-reduction reaction from proceeding excessively and causing the slurry to become overreduced, the oxygen concentration during the aging is preferably 25 vol% or less. In any case, since the gas phase oxygen affects the redox state of the slurry, it is necessary to maintain the oxygen concentration within an appropriate range, and the range is more preferably 5 to 23 vol%, and further 10 to 20 vol%. preferable.

  When the composite oxide is a silica-supported material, the raw material preparation liquid is prepared so as to include silica sol. Silica sol can be added as appropriate. Also, a part of the silica sol can be made into an aqueous dispersion of powdered silica. An aqueous dispersion of powdered silica can also be added as appropriate.

Moreover, it is preferable to add hydrogen peroxide to the liquid containing the components of the aqueous mixed liquid (I) or the aqueous mixed liquid (I) being prepared. At this time, H ₂ O ₂ / Sb (molar ratio) is preferably 0.01 to 5, more preferably from 0.05 to 4. At this time, it is preferable to continue stirring at 30 ° C. to 70 ° C. for 30 minutes to 2 hours.

(Process (2): Drying process)
In step (2), a dry powder is obtained by drying the slurry obtained in the raw material preparation step. Drying can be performed by a known method, for example, spray drying or evaporation to dryness. Among them, it is preferable to obtain a fine spherical dry powder by spray drying. The atomization in the spray drying method can be performed by a centrifugal method, a two-fluid nozzle method, or a high-pressure nozzle method. As the drying heat source, air heated by steam, an electric heater or the like can be used. The dryer inlet temperature of the spray dryer is preferably 150 to 300 ° C, and the dryer outlet temperature is preferably 100 to 160 ° C.

(Process (3): Firing process)
In step (3), a composite oxide is obtained by subjecting the dry powder obtained in the drying step to firing. As a baking apparatus, a rotary furnace (rotary kiln) can be used, for example. The shape of the calciner is not particularly limited, but a tubular shape is preferable because continuous calcining can be performed. The shape of the firing tube is not particularly limited, but is preferably cylindrical.

  The heating method is preferably an external heating type, and for example, an electric furnace can be suitably used. The size, material, and the like of the firing tube can be selected appropriately depending on the firing conditions and production amount, but preferably have an inner diameter of 70 to 2000 mm, more preferably an inner diameter of 100 to 1200 mm. The length of the firing tube is preferably 200 to 10000 mm, more preferably 800 to 8000 mm. In the case of giving an impact to the calciner, the thickness is preferably 2 mm or more, more preferably 4 mm or more from the viewpoint of having a sufficient thickness so as not to be damaged by the impact, and the impact is sufficiently transmitted to the inside of the firing tube. From the viewpoint, it is preferably 100 mm or less, more preferably 50 mm or less. The material of the fired tube is not particularly limited as long as it has heat resistance and has a strength that does not break due to impact, and SUS can be suitably used.

  In the firing tube, a weir plate having a hole in the center for allowing the powder to pass can be provided perpendicular to the flow of the powder to partition the firing tube into two or more areas. By installing the weir plate, it becomes easy to secure the residence time in the firing tube. The number of weir plates may be one or more. The material of the weir plate is preferably metal, and the same material as that of the firing tube can be suitably used. The height of the weir plate can be adjusted according to the residence time to be secured. For example, when supplying powder at a rate of 250 g / hr using a rotary furnace having an SUS firing tube having an inner diameter of 150 mm and a length of 1150 mm, the height of the weir plate is preferably 5 to 50 mm, more preferably 10 to 10 mm. It is 40 mm, more preferably 13 to 35 mm. The thickness of the weir plate is not particularly limited and is preferably adjusted according to the size of the firing tube. For example, in the case of a rotary furnace having a SUS firing tube having an inner diameter of 150 mm and a length of 1150 mm, the thickness of the barrier plate is preferably 0.3 mm or more and 30 mm or less, more preferably 0.5 mm or more and 15 mm or less.

  It is preferable to rotate the firing tube during firing in order to prevent cracking, cracking, etc. of the dry powder and to fire uniformly. The rotation speed of the firing tube is preferably 0.1 to 30 rpm, more preferably 0.5 to 20 rpm, and still more preferably 1 to 10 rpm.

  As firing of the dry powder, it is preferable that the heating temperature of the dry powder is started from a temperature lower than 400 ° C. and continuously or intermittently raised to a temperature in the range of 550 to 800 ° C. .

  The firing atmosphere may be an air atmosphere or an air circulation, but it is preferable to carry out at least a part of the firing while circulating an inert gas substantially free of oxygen such as nitrogen. The supply amount of the inert gas is preferably 50 N liters or more, more preferably 50 to 5000 N liters, and still more preferably 50 to 3000 N liters per 1 kg of the dry powder (N liter is a standard temperature / pressure condition, that is, Means liters measured at 0 ° C. and 1 atm). At this time, there is no problem whether the inert gas and the dry powder are counter-current or co-current, but counter-current contact is preferable in consideration of a gas component generated from the dry powder and a small amount of air mixed with the dry powder.

  The firing step can be carried out even in one stage, but the firing comprises pre-stage firing and main firing, the pre-stage firing is performed in a temperature range of 250 to 400 ° C., and the main firing is performed in a temperature range of 550 to 800 ° C. Preferably it is done. The pre-baking and the main baking may be performed continuously, or the main baking may be performed again after the pre-baking is once completed. Moreover, each of pre-stage baking and main baking may be divided into several stages.

  The pre-stage calcination is preferably carried out in the range of a heating temperature of 250 ° C. to 400 ° C., preferably 300 ° C. to 400 ° C. under an inert gas flow. The pre-stage firing is preferably held at a constant temperature within a temperature range of 250 ° C. to 400 ° C., but the temperature may fluctuate within the range of 250 ° C. to 400 ° C., or the temperature may be gradually raised or lowered. The holding time of the heating temperature is preferably 30 minutes or more, more preferably 3 to 12 hours.

  The temperature rising pattern until reaching the pre-stage firing temperature may be increased linearly, or the temperature may be increased by drawing an upward or downward convex arc.

  There is no particular limitation on the average temperature increase rate at the time of temperature increase until reaching the pre-stage firing temperature, but it is generally about 0.1 to 15 ° C./min, preferably 0.5 to 5 ° C./min, more preferably 1 to 2 ° C./min.

  The main calcination is preferably carried out under an inert gas flow, preferably at 550 to 800 ° C, more preferably 580 to 750 ° C, still more preferably 600 to 720 ° C, and particularly preferably 620 to 700 ° C. The main calcination is preferably held at a constant temperature within a temperature range of 620 to 700 ° C., but the temperature may fluctuate within a range of 620 to 700 ° C., or the temperature may be gradually increased or decreased. The firing time is preferably 0.5 to 20 hours, more preferably 1 to 15 hours.

  When the calcined tube is divided by a dam plate, the dry powder and / or the composite oxide passes continuously through at least two, preferably 2 to 20, more preferably 4 to 15 areas. The temperature can be controlled by using one or more controllers, but in order to obtain the desired firing pattern, a heater and a controller should be installed and controlled for each area separated by these weirs. Is preferred. For example, in the case of using a calcining tube that is divided into 8 sections by dividing the length of the portion of the weir plate into the heating furnace into 8 parts, and using a calcining tube divided into 8 areas, dry powder and / or composite oxide It is preferable that the set temperature is controlled by a heater and a controller in which eight areas are provided for each of the areas so that the temperature becomes the desired firing temperature pattern. If desired, an oxidizing component (for example, oxygen) or a reducing component (for example, ammonia) may be added to the firing atmosphere under an inert gas flow.

  The temperature rising pattern until reaching the main firing temperature may be increased linearly, or the temperature may be increased by drawing an upward or downward convex arc.

  The average rate of temperature increase during the temperature increase until reaching the main firing temperature is not particularly limited, but is generally 0.1 to 15 ° C / min, preferably 0.5 to 10 ° C / min, more preferably 1 to 1 ° C. 8 ° C./min.

  Moreover, the average temperature-fall rate after completion | finish of this baking is 0.01-1000 degreeC / min, Preferably it is 0.05-100 degreeC / min, More preferably, it is 0.1-50 degreeC / min, Most preferably, it is 0.5- 10 ° C./min. Moreover, it is also preferable to hold once at the temperature lower than the main baking temperature after the main baking. The temperature to be held is a temperature that is 10 ° C. or higher, preferably 50 ° C. or higher, more preferably 100 ° C. or higher, than the main firing temperature. The holding time is 0.5 hours or more, preferably 1 hour or more, more preferably 3 hours or more, and particularly preferably 10 hours or more.

  When the main baking is performed again after the pre-stage baking is once completed, it is preferable to perform a low temperature treatment in the main baking.

  The time required for low-temperature treatment, that is, the time required for raising the temperature to the firing temperature after reducing the temperature of the dry powder and / or composite oxide is the size, thickness, material, catalyst of the calciner It is possible to adjust appropriately according to the production amount, a series of periods in which the dry powder and / or the composite oxide are continuously fired, the fixing speed, the fixing amount, and the like. For example, in the case of using a SUS calcining tube having an inner diameter of 500 mm, a length of 4500 mm, and a wall thickness of 20 mm, preferably within 30 days, more preferably within 15 days, Preferably within 3 days, particularly preferably within 2 days.

  For example, dry powder is supplied at a rate of 35 kg / hr while rotating at 6 rpm by a rotary furnace having a SUS firing tube having an inner diameter of 500 mm, a length of 4500 mm, and a wall thickness of 20 mm, and the main firing is performed at a main firing temperature of 645 ° C. In the case of performing, after the temperature is lowered to 400 ° C., the step of raising the temperature to 645 ° C. can be performed in about one day. In the case of continuous firing for one year, by performing such low temperature treatment once a month, firing can be performed while maintaining the oxide layer temperature stably.

(B) Mixing step of tungsten source Although the composite oxide in this embodiment has catalytic activity even if it is as it is, the target product can be obtained by using a mixed catalyst containing a tungsten compound in a specific ratio with the composite oxide. The yield of is improved.

  As a method for obtaining a mixture catalyst containing a tungsten compound, an example of a step of mixing a supply source of a tungsten compound (hereinafter also referred to as “tungsten source”) and a composite oxide will be described.

(B-1) Tungsten source Examples of the tungsten source include tungsten ammonium salt, nitrate salt, carboxylate salt, ammonium carboxylate salt, peroxocarboxylate salt, ammonium peroxocarboxylate salt, ammonium halide salt, halide, and acetyl. Acetonates, alkoxides, triphenyl compounds, polyoxometalates, polyoxometalate ammonium salts; powder raw materials such as tungsten oxide, tungstic acid, ammonium paratungstate, silicotungstic acid, silicotungsto molybdic acid, and cavernadotungstic acid; Examples thereof include liquid raw materials such as an aqueous solution of ammonium metatungstate and tungsten oxide sol.

  The type of the tungsten source and whether it is mixed in a solid or liquid form can be selected depending on the mixing process, the composition of the mixture catalyst to be prepared, and the like. As described later, the mixing step includes a method of supplying the tungsten source in a solid state and a method of supplying the tungsten source in a liquid state. In the case of a liquid supply method, a commercially available liquid product such as an ammonium metatungstate aqueous solution may be used. Of course, the above powder raw material may be used after being dissolved and / or dispersed. . In that case, an appropriate amount of powder raw material may be dissolved and / or dispersed in water, acetone, methanol, ethanol, or other polar / nonpolar solvent. Although depending on solubility and the like, it is preferable to use water as a solvent and / or a dispersion medium from the viewpoint of ease of handling. When the powder is directly mixed without using a solvent, tungsten oxide is preferable from the viewpoint of influence on the target product by the tungsten compound, more preferably tungsten oxide having a tungsten bronze structure, and further preferably tungsten trioxide.

The mixture catalyst of this embodiment can be obtained by physically or chemically mixing the above-described composite oxide and a tungsten source at a predetermined ratio.
(B-2) Physical mixing method The physical mixing method of the composite oxide and the tungsten source is not particularly limited. For example, the composite oxide is added to the hopper that supplies the catalyst to the reactor, and an appropriate amount of the tungsten source is added. A method is mentioned. Before the mixed oxide and the tungsten source are put into the hopper, they may be mixed in advance, but they are naturally mixed in the process of supplying the catalyst from the hopper to the reactor without mixing in advance. It is not essential to keep it. The order in which the composite oxide and the tungsten source are put into the hopper is not particularly limited, and may be appropriately determined so as to be in a sufficiently contacted state in the reactor from the viewpoint of the particle size of the both. If necessary, air and nitrogen can be circulated and mixed. In the case of the fluidized bed reaction, the composite oxide and the tungsten source may be sequentially supplied into the reactor, instead of supplying from the hopper at a time. In this case, the composite oxide and the tungsten source are mixed while flowing in the reactor while the reaction proceeds.

  In the case of the physical mixing method, since no chemical change occurs in the tungsten source before the reaction for producing the unsaturated acid or unsaturated nitrile, the tungsten compound contained in the mixture catalyst has the same structure as the tungsten source. On the other hand, when the production reaction of the unsaturated acid or unsaturated nitrile is advanced using this mixture catalyst, the tungsten compound is chemically changed because heat is applied in a state of being in contact with the composite oxide or the reaction substrate. The mixture catalyst is a catalyst with a view to affecting the catalyst performance by acting on the composite oxide by such a structural change during the progress of the reaction. Therefore, even if the structure is changed so that a part or all of the tungsten compound becomes a part of the composite oxide during the progress of the reaction, the present embodiment is naturally applied to the case where it exists as a mixture before the reaction. This is a category of a mixture catalyst.

  Even if the tungsten source is supplied to the fluidized bed reactor during the reaction, the same effect as that supplied before the reaction occurs. In that case, the mixture catalyst does not exist before the reaction, but it can be said that the mixture catalyst is formed immediately after the supply of the tungsten source.

(B-3) Chemical mixing method (b-3-i) Liquid phase process In this embodiment, the method of dripping the solution which melt | dissolved the tungsten source in complex oxide is called impregnation. On the other hand, a method in which a complex oxide is added to a solution in which a tungsten source is dissolved and contacted for a certain time by stirring or the like is called dipping. In either case, unnecessary solutions can be removed by filtration or evaporation. Evaporation is carried out at about 30 to 300 ° C, preferably 40 to 250 ° C. Thereafter, if necessary, a baking treatment may be performed so that a part or all of the tungsten source is converted into an oxide. The pores of the complex oxide are filled with air, inert gas, and other atmospheric gases that existed before the contact treatment of the complex oxide, which may hinder the diffusion of tungsten into the pores. There is. In that case, the gas in the pores can be removed under a reduced pressure atmosphere before or during the impregnation or immersion.

  When impregnation or immersion is performed, there is a possibility that the metal element and tungsten in the composite oxide undergo ion exchange while the composite oxide and the tungsten source are present in the liquid phase. When ion exchange occurs, surface modification by ion exchange is expected to proceed during treatment in the liquid phase, but tungsten is in a state of being incorporated into the complex oxide. In that case, tungsten does not exist as a simple substance of the tungsten compound in the mixture catalyst, but is no longer a mixture and is not included in the mixture catalyst of the present embodiment. I can't. In addition, when the catalyst in which tungsten is incorporated into the complex oxide and the mixture catalyst are compared in terms of the performance of the catalyst, when the catalyst in which tungsten is incorporated is used for the production reaction of the unsaturated acid or unsaturated nitrile, The yield of the target product shows the maximum value at the initial stage of the reaction, and after that, even if the yield deteriorates, it does not improve, whereas in the case of a mixed catalyst, the time until a certain reaction time as described later As the process proceeds, the yield of the target product tends to improve.

  The ion exchange in the liquid phase depends on the pH, the liquid temperature, the tungsten concentration in the solution, the contact time between the solution and the complex oxide, and the pH is, for example, 1.0 to 7.0, preferably 1.0. Ion exchange can be suppressed by adjusting to ˜4.0. In general, the liquid temperature is preferably low. For example, ion exchange can be suppressed by adjusting the liquid temperature to 0 to 50 ° C, more preferably 0 to 30 ° C. The lower the tungsten concentration, the less the ion exchange proceeds, and the preferred concentration is less than 1.0 mol / kg as the tungsten metal concentration. The contact time between the solution and the composite oxide is preferably shorter, and is within 1 hour, more preferably within 15 minutes.

  The mixture obtained by the impregnation and / or dipping process can be used as it is as a mixture catalyst, but may be used after calcination.

  The tungsten compound contained in the mixture catalyst that has undergone the liquid phase treatment may have an aspect in which the tungsten source is changed (eg, oxidized, crystallized, or amorphous) in addition to an aspect having the same structure as the tungsten source. Even if it is an aspect, as long as it contains the tungsten compound which is not a part of complex oxide, it is the category of the mixture catalyst in this embodiment.

(B-3-ii) Firing step Even when no ion exchange occurs in the liquid phase, an exchange reaction may occur in the firing step, and the tungsten source may become a part of the composite oxide. As in the liquid phase treatment, this exchange reaction is expected to be in a non-mixed state due to progress of surface modification. The ease with which the exchange reaction occurs depends mainly on the firing temperature. If the firing temperature is too high, the exchange reaction tends to proceed. The firing temperature at which the exchange reaction hardly occurs is preferably 200 to 400 ° C, more preferably 250 to 350 ° C. The tungsten compound contained in the mixture catalyst that has undergone the calcination treatment generally has a structure different from that of the tungsten source, but as long as it contains a tungsten compound that is not a part of the composite oxide, similar to the one after the liquid phase treatment. The category of the mixture catalyst in the present embodiment.

(C) Mixture catalyst The mixture catalyst in this embodiment is
Mixture catalyst for gas phase catalytic oxidation reaction or gas phase catalytic ammoxidation reaction of propane or isobutane,
A mixed catalyst containing a composite oxide represented by the following composition formula (1) and a tungsten compound in a proportion of the following formula (2);
_{Mo 1 V a Nb b Sb c} W d Z e O n (1)
(In the formula (1), Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba, and a, b, c, d, e, and n are Mo1. Indicates the atomic ratio of each element per atom, a is 0.01 ≦ a ≦ 1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and d is 0.001 ≦ d ≦ 1. E represents 0 ≦ e ≦ 1, and n represents a number determined by the valence of the constituent metal.)
0.001 <w <0.3 (2)
(In formula (2), w represents the atomic ratio of tungsten in the tungsten compound as the atomic ratio per Mo atom in the composite oxide).

  The mixture catalyst in the present embodiment is a mixture of a tungsten compound and a composite oxide. By containing a tungsten compound as an essential component in the mixture catalyst, during the vapor phase catalytic oxidation reaction of propane or isobutane and oxygen, or during the vapor phase catalytic ammoxidation reaction of propane or isobutane, oxygen and ammonia, Based on the principle that tungsten element diffuses and is immobilized on the surface of the complex oxide, the yield of the target product can be dramatically improved.

The composition of the composite oxide in the present embodiment is represented by the following formula (1).
_{Mo 1 V a Nb b Sb c} W d Z e O n (1)
(In the formula (1), Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, Ba, a, b, c, d, e, n are Indicate the atomic ratio of each element per Mo atom, a is 0.01 ≦ a ≦ 1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, d is 0.001 ≦ d ≦ 1 and e are 0 ≦ e ≦ 1, and n is a number determined by the valence of the constituent metal.

  The atomic ratios a and b per Mo atom are preferably 0.1 to 0.4 and 0.02 to 0.2, respectively.

  C, which is the atomic ratio of Sb per Mo atom, is preferably 0.01 to 0.6, and more preferably 0.1 to 0.4. Moreover, as a result of earnestly examining a / c which is the atomic ratio of V and Sb, the detailed reason is not clear, but from the viewpoint of improving the yield, a / c is preferably in the range of 0.1 to 1. I understood that.

  D, which is the atomic ratio of W per Mo atom, is 0.001 ≦ d ≦ 1, and preferably 0.001 ≦ d ≦ 0.3. It is presumed that tungsten in the composite oxide (hereinafter, tungsten present in the composite oxide is also referred to as “bulk tungsten”) is replaced with molybdenum or vanadium sites in the composite oxide. When the melting points of the oxides are compared, for example, the melting points of molybdenum trioxide and tungsten trioxide are 795 ° C. and 1473 ° C., and the melting point of tungsten oxide is high, so molybdenum in the composite oxide is replaced with tungsten. It is estimated that the melting point of the composite oxide becomes high. Therefore, it is considered that the bulk tungsten dispersed in the composite oxide affects the crystal structure of the composite oxide and contributes to heat resistance and redox resistance. As a result, the composite oxide having bulk tungsten is The catalyst life tends to be long and tends to be advantageous for industrial long-term use. On the other hand, tungsten in the tungsten compound is presumed to have an effect of increasing the yield of unsaturated acid or unsaturated nitrile. Further, as an effect of bulk tungsten, it is presumed that there is an effect of suppressing a decrease in the yield of the target product due to excessive diffusion of tungsten in the tungsten compound into the composite oxide.

  E which is an atomic ratio per Mo atom of the component Z is 0 ≦ e ≦ 1, preferably 0.001 ≦ e <1, more preferably 0.001 ≦ e <0.1, and 0.002 ≦ e. <0.01 is more preferable. Component Z is preferably contained in a trace amount because component Z may cause an undesirable reaction in the slurry as taught in JP-A-11-244702. On the other hand, since the component Z is highly effective in improving the yield of the target product, it is preferable that the component Z is uniformly dispersed in the catalyst particles. Component Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba, and one type selected from the group consisting of La, Ce, Pr, and Yb The above elements are preferable, and Ce is particularly preferable because the yield of the target product tends to be the highest.

The composite oxide is preferably supported by a carrier mainly composed of silica. When the composite oxide is supported by a carrier containing silica as a main component, it has a high mechanical strength, and therefore is suitable for a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction using a fluidized bed reactor. The content of silica in the carrier mainly composed of silica is 20 to 70% by mass in terms of SiO _{2 with} respect to the total mass of the supported oxide composed of the oxide of the complex oxide constituting element and the carrier. Preferably, it is 30 to 60% by mass.

  The content of the silica carrier in the composite oxide is preferably 20% by mass or more from the viewpoint of strength and prevention of powdering. Further, even when the composite oxide is used industrially, stable operation is difficult, and it is necessary to replenish the lost composite oxide. On the other hand, when the content of the silica support is more than 70% by mass, sufficient activity cannot be obtained and the required amount of catalyst increases. In particular, in the case of a fluidized bed, if the silica content is more than 70% by mass, the specific gravity of the silica-supported particles becomes too light and it becomes difficult to obtain a good fluidized state.

The mixture catalyst in the present embodiment is a catalyst containing the composite oxide represented by the composition formula (1) and the tungsten compound in the ratio of the following formula (2).
0.001 <w <0.3 (2)
In formula (2), w represents the atomic ratio of tungsten in the tungsten compound as the atomic ratio per Mo atom in the composite oxide.

  The atomic ratio of tungsten in the tungsten compound per Mo atom of the composite oxide, w is 0.001 <w <0.3, preferably 0.01 <w <0.2, more preferably 0. .015 <w <0.18. When w is 0.001 or less, the amount of tungsten is too small to confirm the effect of the present application. When it is 0.3 or more, the amount of tungsten is too large and the catalyst surface is not modified into a preferable form. The effect cannot be confirmed.

  In the mixture catalyst, the composite oxide and the tungsten compound are preferably in contact with each other. The contact may be contact between particles in the order of micrometers and millimeters, or contact between a tungsten compound and a composite oxide dispersed in nano-order within pores in the composite oxide particle. For example, the former is obtained by physical mixing of composite oxide particles and a tungsten source, and the latter is obtained by liquid phase treatment using the composite oxide particles and a liquid tungsten source.

  In the mixed catalyst of the present embodiment, it is difficult to confirm the structural change before and after the mixing process even if the structural analysis by X-ray diffraction or the like is performed. In addition, when the production reaction of the target product is carried out using a mixture catalyst, it is common that there is no difference at the stage immediately after the start of the reaction, compared with the performance of the composite oxide not containing the tungsten compound. For example, when the unsaturated nitrile production reaction is carried out at 445 ° C., there is substantially no difference in the yield of the target product between the mixed catalyst and the composite oxide after 5 hours from the start of the reaction. On the other hand, as the reaction time elapses, a difference appears in the yields of both reactions. For example, after 240 hours, a yield improvement of 1% or more is observed in the reaction using the mixture catalyst as compared with the initial stage. However, in the case of the composite oxide, there is almost no change from the initial yield.

  Regarding the reason why the yield of the target product is improved during the production reaction of the unsaturated acid or unsaturated nitrile using the mixture catalyst of the present embodiment, the present inventors combined tungsten in the tungsten compound by solid-phase reaction. It is presumed that this is because it diffuses on the oxide surface and undergoes an exchange reaction with a metal element such as Mo, whereby the catalyst surface is modified into a preferred form. Although the preferred form of the catalyst surface and the mechanism for improving the performance are not clear, it is presumed that the sequential decomposition of the target product or intermediate product is suppressed by placing tungsten at a specific site in the vicinity of the composite oxide surface. As described above, it is considered that there is a difference in the structure and dispersion state of the tungsten compound depending on the preparation method of the mixture catalyst, etc., but according to the study by the present inventors, in the mixture catalyst before the solid-phase reaction, There was almost no difference in performance depending on the structure and dispersion state. This is because it is important that the mixture catalyst contains an appropriate amount of the tungsten compound independently of the composite oxide, and the content of the tungsten compound is within an appropriate range regardless of the state of the tungsten compound. If so, it is estimated that a solid-phase reaction may occur during a long-term production reaction. When the reaction is carried out for a long time using a general mixture catalyst, Mo in the catalyst decreases with time. At that time, as a known technique, a method is known in which a Mo compound is introduced into a reactor to suppress a decrease in activity associated with a decrease in Mo composition. In this embodiment, it can be used in combination with this known Mo compound makeup technique.

[2] Unsaturated acid or unsaturated nitrile In the presence of the mixture catalyst in this embodiment, propane or isobutane is subjected to gas phase catalytic oxidation or gas phase catalytic ammoxidation to produce the corresponding unsaturated acid or unsaturated nitrile. be able to.
That is, the method for producing an unsaturated acid or unsaturated nitrile in this embodiment is as follows:
This is a production method including a step of bringing the above-mentioned mixture catalyst into contact with propane or isobutane and oxygen, or with propane or isobutane, oxygen and ammonia.

  When using the mixture catalyst of this embodiment, the yield of a target object approaches the maximum value with progress of unsaturated acid or unsaturated nitrile manufacturing reaction. Although the detailed reason is unknown, in the basic study of this embodiment, since the yield of the target product is not improved by air atmosphere firing at 300 to 550 ° C. or nitrogen atmosphere firing, propane or isobutane and air are used. Under the gas phase catalytic oxidation reaction used, or under the gas phase catalytic ammoxidation reaction using propane or isobutane, air and ammonia, the solid phase reaction of tungsten in the tungsten compound proceeds moderately, and the mixture catalyst is activated. It is estimated that The preferable conditions for activation are not particularly limited, but are preferably 350 to 550 ° C., more preferably 400 to 500 ° C. in a state where propane or isobutane and oxygen, or propane or isobutane, oxygen and ammonia are brought into contact with each other. Heat to. On the other hand, a preferable activation treatment time is 1 to 1500 hours, more preferably 5 to 750 hours, and further preferably 50 to 500 hours.

The feedstock for propane or isobutane and ammonia need not be highly pure, and industrial grade gases can be used.
As the supply oxygen source, air, air enriched with oxygen, or pure oxygen can be used. Further, helium, argon, carbon dioxide gas, water vapor, nitrogen or the like may be supplied as a dilution gas.

The gas phase catalytic oxidation reaction of propane or isobutane can be carried out under the following conditions.
The molar ratio of oxygen supplied to the reaction to propane or isobutane is 0.1 to 6, preferably 0.5 to 4.
The reaction temperature is 300 to 500 ° C, preferably 350 to 450 ° C.
The reaction pressure is 5 × 10 ^{4 to} 5 × 10 ⁵ Pa, preferably 1 × 10 ^{5 to} 3 × 10 ⁵ Pa.
The contact time is 0.1 to 10 (sec · g / cc), preferably 0.5 to 5 (sec · g / cc). In the present embodiment, the contact time is determined by the following equation.
Contact time (sec · g / cc) = (W / F) × 273 / (273 + T)
Here, W, F, and T are defined as follows.
W = filled catalyst amount (g)
F = Raw material mixed gas flow rate (Ncc / sec) at standard condition (0 ° C., 1.013 × 10 ⁵ Pa)
T = reaction temperature (° C.)

The gas phase catalytic ammoxidation reaction of propane or isobutane can be carried out under the following conditions.
The molar ratio of oxygen supplied to the reaction to propane or isobutane is 0.1 to 6, preferably 0.5 to 4.
The molar ratio of ammonia to propane or isobutane supplied to the reaction is 0.3 to 1.5, preferably 0.7 to 1.2.
The reaction temperature is 350 to 500 ° C, preferably 380 to 470 ° C.
The reaction pressure is 5 × 10 ^{4 to} 5 × 10 ⁵ Pa, preferably 1 × 10 ^{5 to} 3 × 10 ⁵ Pa.
The contact time is 0.1 to 10 (sec · g / cc), preferably 0.5 to 5 (sec · g / cc).

  As a reaction system, a conventional system such as a fixed bed, a fluidized bed, and a moving bed can be adopted, but a fluidized bed reactor in which reaction heat can be easily removed is preferable. The gas phase catalytic oxidation or ammoxidation reaction may be a single flow type or a recycle type.

Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the scope of the present embodiment is not limited to these examples.
In the examples and comparative examples, the propane conversion and the acrylonitrile yield follow the following definitions, respectively.
Propane conversion (%) = (moles of propane reacted) / (moles of propane fed) × 100
Acrylonitrile (AN) yield (%) = (Mole number of acrylonitrile produced) / (Mole number of supplied propane) × 100

(Preparation of niobium mixture)
A niobium mixed solution was prepared by the following method.
To 65 kg of water, 0.765 kg of niobic acid containing 80.0% by mass as Nb ₂ O ₅ and 2.633 kg of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] were mixed. The molar ratio of the charged oxalic acid / niobium was 5.0, and the charged niobium concentration was 0.50 (mol-Nb / Kg-solution). This solution was heated and stirred at 95 ° C. for 2 hours to obtain a mixed solution in which niobium was dissolved. The mixture was allowed to stand and ice-cooled, and then the solid was separated by suction filtration to obtain a uniform niobium mixture. The molar ratio of oxalic acid / niobium in this niobium mixed solution was 2.71 according to the following analysis.
10 g of this niobium mixture was precisely weighed in a crucible, dried at 95 ° C. overnight, and then heat treated at 600 ° C. for 1 hour to obtain 0.771 g of Nb ₂ O ₅ . From this result, the niobium concentration was 0.580 (mol-Nb / Kg-solution).
3 g of this niobium mixture was precisely weighed into a 300 mL glass beaker, 200 mL of hot water at about 80 ° C. was added, and then 10 mL of 1: 1 sulfuric acid was added. The obtained mixed liquid was titrated with 1 / 4N KMnO ₄ under stirring while maintaining the liquid temperature at 70 ° C. on a hot stirrer. The end point was a point where a faint pale pink color by KMnO ₄ lasted for about 30 seconds or more. The concentration of oxalic acid was 1.570 (mol-oxalic acid / Kg) as a result of calculation according to the following formula from titration.
2KMnO ₄ + 3H ₂ SO ₄ + 5H ₂ C ₂ O ₄ → K ₂ SO ₄ + 2MnSO ₄ + 10CO ₂ + 8H ₂ O
The obtained niobium mixed solution was used as a niobium mixed solution (B ₀ ) for catalyst preparation described below.

[Example 1]
(Preparation of complex oxide)
Mixing composition formula was produced by the composite oxide as follows represented by _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.03 Ce 0.005 O n /47.0wt%-SiO 2.
1.902 kg of water, 424.3 g of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 59.0 g of ammonium metavanadate [NH ₄ VO ₃ ], cerium nitrate hexahydrate 5 .22 g and 87.6 g of diantimony trioxide [Sb ₂ O ₃ ] were added and heated at 95 ° C. for 1 hour with stirring to obtain an aqueous raw material liquid (I).
Aqueous raw material liquid (II) is prepared by adding 54.5 g of hydrogen peroxide containing 30 wt% as H ₂ O _{2 to} 414.3 g of niobium mixed liquid (B ₀ ) and stirring and mixing at room temperature for 10 minutes. did.
After cooling the obtained aqueous raw material liquid (I) to 70 ° C., 760.3 g of silica sol containing 34.0 wt% as SiO ₂ was added, and hydrogen peroxide solution 102 containing 30 wt% as H ₂ O ₂ was further added. .2 g was added and stirring was continued at 55 ° C. for 30 minutes. Next, an aqueous raw material liquid (II), a dispersion in which 33.4 g of a 50 wt% ammonium metatungstate aqueous solution as WO _{3 and} 211.5 g of powdered silica are dispersed in 2.750 kg of water are sequentially added to the aqueous mixture. (III) was obtained. The aqueous mixed liquid (III) was aged at 50 ° C. for 2 hours and 30 minutes after the addition of the aqueous raw material liquid (II) to obtain a slurry.
The obtained slurry was supplied to a centrifugal spray dryer and dried to obtain a fine spherical dry powder. The dryer inlet temperature was 210 ° C and the outlet temperature was 120 ° C.
800 g of the obtained dry powder was filled into a SUS firing tube having a diameter of 3 inches, and the composite oxide was obtained by firing at 680 ° C. for 2 hours while rotating the tube under a nitrogen gas flow of 8.0 NL / min. It was.

(Preparation of mixture catalyst)
100 g of the composite oxide obtained was added to and mixed with an aqueous solution (concentration 0.7 mol / kg as W) in which 46.2 g of an aqueous ammonium metatungstate solution was diluted with 453.8 g of water. The obtained mixed liquid was moved into an aspirator container and subjected to reduced pressure treatment at 100 kPa for 10 minutes. Then, the liquid mixture in the aspirator was filtered and dried at 50 ° C. for 12 hours in a dryer to obtain a mixture with a tungsten compound. Composition analysis was performed on the obtained mixture catalyst. A fluorescent X-ray analyzer (Rigaku Denki, RIX1000) was used for composition analysis.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.10 Ce 0.005 O n, was confirmed to be w = 0.07.

(Propane ammoxidation reaction)
35 g of the obtained mixture catalyst was charged into a Vycor glass fluidized bed reaction tube having an inner diameter of 25 mm, and the reaction temperature was 445 ° C. and the reaction pressure was normal pressure, and the molar ratio of propane: ammonia: oxygen: helium = 1: 1: 3: 18. The mixed gas was supplied at a contact time of 3.4 (sec · g / cc). The propane conversion after 5 hours from the start of the mixed gas supply was 88.3%, and the AN yield was 52.4%.
Thereafter, the reaction was continued under the same conditions. The propane conversion after 240 Hr after starting the supply of the mixed gas was 88.8%, and the AN yield was 54.4%.

[Example 2]
(Production of mixture catalyst)
A mixed catalyst was produced using the composite oxide obtained in Example 1. The same procedure as in Example 1 was conducted except that the ammonium tungstate aqueous solution concentration after dilution was changed to 1.5 mol / kg as W.
Results The composition of the resulting mixture catalyst was measured in the same manner as in Example 1, a _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.06 Ce 0.005 O n, was confirmed to be w = 0.15.

(Propane ammoxidation reaction)
The ammoxidation reaction of propane was performed in the same manner as in Example 1 using the obtained mixture catalyst. After 5 hours from the start of the gas supply, the propane conversion was 88.2% and the AN yield was 52.3%.
Thereafter, the reaction was continued under the same conditions, and the propane conversion after 240 hours after starting the mixed gas supply was 88.6%, and the AN yield was 53.8%.

[Comparative Example 1]
(Preparation of complex oxide)
Mixing composition formula was produced composite oxide as follows represented by _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} Ce 0.005 O n /47.0wt%-SiO 2.
1.964 kg of water, 441.1 g of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 61.4 g of ammonium metavanadate [NH ₄ VO ₃ ], cerium nitrate hexahydrate 5 .42 g and 87.4 g of diantimony trioxide [Sb ₂ O ₃ ] were added and heated at 95 ° C. for 1 hour with stirring to obtain an aqueous raw material liquid (I).
Aqueous raw material liquid (II) is prepared by adding 56.7 g of hydrogen peroxide containing 30 wt% as H ₂ O _{2 to} 430.8 g of niobium mixed liquid (B ₀ ) and stirring and mixing at room temperature for 10 minutes. did.
After cooling the obtained aqueous raw material liquid (I) to 70 ° C., 760.3 g of silica sol containing 34.0 wt% as SiO ₂ was added, and hydrogen peroxide solution 102 containing 30 wt% as H ₂ O ₂ was further added. 0.0 g was added and stirring was continued at 55 ° C. for 30 minutes. Next, an aqueous raw material liquid (II) and a dispersion obtained by dispersing 211.5 g of powdered silica in 2.750 kg of water were sequentially added to obtain an aqueous mixed liquid (III). The aqueous mixed liquid (III) was aged at 50 ° C. for 2 hours and 30 minutes after the addition of the aqueous raw material liquid (II) to obtain a slurry.
The obtained slurry was supplied to a centrifugal spray dryer and dried to obtain a fine spherical dry powder. The dryer inlet temperature was 210 ° C and the outlet temperature was 120 ° C.
800 g of the obtained dry powder was filled into a SUS firing tube having a diameter of 3 inches, and the composite oxide was obtained by firing at 680 ° C. for 2 hours while rotating the tube under a nitrogen gas flow of 8.0 NL / min. It was.

(Production of mixture catalyst)
Add 100 g of the composite oxide obtained while stirring to an aqueous solution (concentration of 1.0 mol / kg as W) of 231.0 g of ammonium metatungstate aqueous solution containing 50.0 wt% as WO ₃ Mixed. The obtained mixed liquid was moved into an aspirator container and subjected to reduced pressure treatment at 100 kPa for 10 minutes. Then, the liquid mixture in the aspirator was filtered and dried at 50 ° C. for 12 hours in a dryer to obtain a mixture with a tungsten compound. Composition analysis was performed on the obtained mixture catalyst. A fluorescent X-ray analyzer (Rigaku Denki, RIX1000) was used for composition analysis.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.10 Ce 0.005 O n, was confirmed to be w = 0.10.

(Propane ammoxidation reaction)
35 g of the mixture catalyst obtained by the above treatment was filled into a Vycor glass fluidized bed reaction tube having an inner diameter of 25 mm, and propane: ammonia: oxygen: helium = 1: 1: 3: 18 under a reaction temperature of 445 ° C. and a normal pressure of the reaction. A mixed gas having a molar ratio was supplied at a contact time of 3.4 (sec · g / cc). The propane conversion after 5 hours from the start of the mixed gas supply was 87.3%, and the AN yield was 52.2%.
Thereafter, the reaction was continued under the same conditions. The propane conversion after 240 Hr after starting the supply of the mixed gas was 86.3%, and the AN yield was 51.8%.

[Comparative Example 2]
(Production of mixture catalyst)
A mixture catalyst was produced in the same manner as in Comparative Example 1 except that the diluted ammonium tungstate aqueous solution concentration was changed to 1.5 mol / kg as W.
Results The composition of the resulting mixture catalyst was measured in the same manner as in Example 1, a _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.15 Ce 0.005 O n, was confirmed to be w = 0.15.

(Propane ammoxidation reaction)
The ammoxidation reaction of propane was performed in the same manner as in Example 1 using the obtained mixture catalyst. After 5 hours from the start of supplying the mixed gas, the propane conversion was 86.9% and the AN yield was 51.8%.
Thereafter, the reaction was continued under the same conditions, and the propane conversion after 240 hours after starting the supply of the mixed gas was 85.2%, and the AN yield was 50.3%.

[Example 3]
(Production of mixture catalyst)
An aqueous solution obtained by diluting 500 g of an aqueous ammonium metatungstate solution with 500 g of water was prepared, and the obtained aqueous solution was supplied to a centrifugal spray dryer and dried to obtain a fine spherical dry powder. The dryer inlet temperature was 210 ° C and the outlet temperature was 120 ° C. 100 g of the obtained tungsten-containing spray-dried product was fired at 500 ° C. for 2 hours in an air atmosphere to obtain a powdery tungsten compound. The tungsten compound was confirmed to be tungsten trioxide by X-ray diffraction measurement.
100 g of the composite oxide obtained in Example 1 and 3.37 g of the obtained tungsten compound were mixed in powder form to obtain a mixture catalyst. Composition analysis was performed on the obtained mixture catalyst. A fluorescent X-ray analyzer (Rigaku Denki, RIX1000) was used for composition analysis.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.09 Ce 0.005 O n, was confirmed to be w = 0.06.

(Propane ammoxidation reaction)
35 g of the obtained mixture catalyst was charged into a Vycor glass fluidized bed reaction tube having an inner diameter of 25 mm, and the reaction temperature was 445 ° C. and the reaction pressure was normal pressure, and the molar ratio of propane: ammonia: oxygen: helium = 1: 1: 3: 18. The mixed gas was supplied at a contact time of 3.4 (sec · g / cc). After 5 hours from the start of supplying the mixed gas, the propane conversion was 88.7% and the AN yield was 52.6%.
Thereafter, the reaction was continued under the same conditions, and the propane conversion after 240 hours after starting the mixed gas supply was 89.2%, and the AN yield was 54.0%.

[Example 4]
(Production of mixture catalyst)
A mixture catalyst was obtained in the same manner as in Example 3 except that the mass of the tungsten compound to be mixed was changed to 10.1 g. The composition analysis was performed on the obtained mixture catalyst in the same manner as in Example 1. A fluorescent X-ray analyzer (Rigaku Denki, RIX1000) was used for composition analysis.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.18 Ce 0.005 O n, was confirmed to be w = 0.15.

(Propane ammoxidation reaction)
35 g of the obtained mixture catalyst was charged into a Vycor glass fluidized bed reaction tube having an inner diameter of 25 mm, and the reaction temperature was 445 ° C. and the reaction pressure was normal pressure, and the molar ratio of propane: ammonia: oxygen: helium = 1: 1: 3: 18. The mixed gas was supplied at a contact time of 3.4 (sec · g / cc). The propane conversion after 5 hours from the start of the mixed gas supply was 88.6%, and the AN yield was 52.5%.
Thereafter, the reaction was continued under the same conditions. The propane conversion after 240 Hr after starting the supply of the mixed gas was 89.0%, and the AN yield was 53.6%.

[Comparative Example 3]
(Production of mixture catalyst)
A mixed catalyst was produced in the same manner as in Example 3 except that the composite oxide obtained in Comparative Example 1 was used and the mass of the tungsten compound to be mixed was changed to 6.74 g.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.10 Ce 0.005 O n, was confirmed to be w = 0.10.

(Propane ammoxidation reaction)
The ammoxidation reaction of propane was performed in the same manner as in Example 1 using the obtained mixture catalyst. The propane conversion after 5 hours from the start of the mixed gas supply was 88.6%, and the AN yield was 52.5%.
Thereafter, the reaction was continued under the same conditions, and the propane conversion after 240 hours after starting the mixed gas supply was 87.6%, and the AN yield was 52.1%.

[Comparative Example 4]
(Production of mixture catalyst)
A mixed catalyst was prepared in the same manner as in Example 3 except that the composite oxide obtained in Comparative Example 1 was used and the mass of the tungsten compound to be mixed was changed to 10.1 g.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.15 Ce 0.005 O n, was confirmed to be w = 0.15.

(Propane ammoxidation reaction)
The ammoxidation reaction of propane was performed in the same manner as in Example 1 using the obtained mixture catalyst. After 5 hours from the start of supplying the mixed gas, the propane conversion was 88.5% and the AN yield was 52.4%.
Thereafter, the reaction was continued under the same conditions, and the propane conversion after 240 hours after starting the supply of the mixed gas was 86.3%, and the AN yield was 50.9%.

[Comparative Example 5]
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 using the composite oxide obtained in Example 1 as it was without producing a mixture catalyst. The propane conversion after 5 hours from the start of the mixed gas supply was 88.4%, and the AN yield was 52.2%.
Thereafter, the reaction was continued under the same conditions, and the propane conversion after 240 hours after starting the supply of the mixed gas was 88.3%, and the AN yield was 52.1%.

[Example 5]
(Preparation of complex oxide)
Except for changing the amount of ammonium metatungstate aqueous solution 133.6 g, mixing composition formula Mo ₁ V _0.21 in the same manner as in Example _{1 Nb 0.10 Sb 0.24 W 0.12 Ce} 0.005 O n /47.0wt%- A composite oxide represented by SiO ₂ was produced.

(Production of mixture catalyst)
Using the obtained complex oxide, a mixture catalyst was produced in the same manner as in Example 1.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.19 Ce 0.005 O n, was confirmed to be w = 0.07.

(Propane ammoxidation reaction)
The ammoxidation reaction of propane was performed in the same manner as in Example 1 using the obtained mixture catalyst. After 5 hours from the start of supplying the mixed gas, the propane conversion was 87.6% and the AN yield was 52.1%.
Thereafter, the reaction was continued under the same conditions. The propane conversion after 240 Hr after starting the supply of the mixed gas was 87.7%, and the AN yield was 54.1%.

[Example 6]
A mixed catalyst was produced in the same manner as in Example 2 using the composite oxide obtained in Example 5.
The composition of the resulting mixture catalyst is _{Mo 1 V 0.21 Nb 0.10 Sb 0.24} W 0.27 Ce 0.005 O n, was confirmed to be w = 0.15.

(Propane ammoxidation reaction)
The ammoxidation reaction of propane was performed in the same manner as in Example 1 using the obtained mixture catalyst. The propane conversion after 5 hours from the start of the mixed gas supply was 87.5%, and the AN yield was 52.0%.
Thereafter, the reaction was continued under the same conditions. The propane conversion after 240 Hr after starting the supply of the mixed gas was 87.6%, and the AN yield was 53.6%.

  The mixture catalyst of the present invention can be usefully used in an industrial production process in which propane or isobutane is subjected to a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction to produce a corresponding unsaturated acid or unsaturated nitrile.

Claims (5)

Mixture catalyst for gas phase catalytic oxidation reaction or gas phase catalytic ammoxidation reaction of propane or isobutane,
A mixed catalyst containing a composite oxide represented by the following composition formula (1) and a tungsten compound in a proportion of the following formula (2);
_{Mo 1 V a Nb b Sb c} W d Z e O n (1)
(In the formula (1), Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr, and Ba, and a, b, c, d, e, and n are Mo1. Indicates the atomic ratio of each element per atom, a is 0.01 ≦ a ≦ 1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and d is 0.001 ≦ d ≦ 1. E represents 0 ≦ e ≦ 1, and n represents a number determined by the valence of the constituent metal.)
0.001 <w <0.3 (2)
(In formula (2), w represents the atomic ratio of tungsten in the tungsten compound as the atomic ratio per Mo atom in the composite oxide).   The mixture catalyst according to claim 1, wherein the tungsten compound includes tungsten oxide.   The mixture catalyst according to claim 1 or 2, which is used in a fluidized bed reaction. A method for producing an unsaturated acid or an unsaturated nitrile, comprising:
The manufacturing method including the process which makes propane or isobutane and oxygen or a propane or isobutane, oxygen, and ammonia contact the mixture catalyst of any one of Claims 1-3.   The manufacturing method of Claim 4 heated to 400 degreeC or more in the state which contacted propane or isobutane, and oxygen, or propane or isobutane, oxygen, and ammonia.