JP5363021B2 - Method for producing oxide catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a catalyst having excellent performance (high yield of an objective product) in large quantities and in high efficiency by restraining the catalyst from sticking to the inside surface of a firing vessel while keeping a particle shape though the catalyst is an oxide catalyst for producing a compound having the melting point lower than the firing temperature during a firing step. <P>SOLUTION: The method for manufacturing the oxide catalyst includes: the firing step of supplying a catalyst precursor to the firing vessel to fire the catalyst precursor at the temperature equal to or higher than the melting point of an oxide of a constituent metallic element of the oxide catalyst; and a low temperature treatment step of temporarily treating the catalyst precursor and/or the oxide catalyst at the temperature lower than the firing temperature during the firing step. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a method for producing an oxide catalyst including a step of firing at a firing temperature equal to or higher than the melting point of a metal oxide of a catalyst constituent element.

Conventionally, a method for producing (meth) acrylonitrile by an ammoxidation reaction of propylene or isobutylene and a method for producing (meth) acrylic acid by an oxidation reaction of propylene or isobutylene are known. Recently, instead of such a method using propylene or isobutylene, (meth) by a gas phase catalytic ammoxidation reaction of propane or isobutane
Attention has been focused on a method for producing acrylonitrile and a method for producing (meth) acrylic acid by a gas phase catalytic oxidation reaction of propane or isobutane.

So far, as the catalyst used in the above reaction, molybdenum (Mo), vanadium (V
), Various oxide catalysts containing niobium (Nb), tellurium (Te) and / or antimony (Sb) have been proposed. For example, Patent Document 1 discloses an oxide catalyst containing Mo—V—Nb—Te, and Patent Document 2 discloses an oxide catalyst containing Mo—V—Nb—Sb. As for these catalysts, it is known that the calcination method during the production process affects the catalyst performance, and the above-mentioned patent document describes the calcination method in detail. In Patent Document 3, gas is introduced into the catalyst bed in order to prevent deterioration of workability due to solidification of the catalyst and adhesion of particles in the firing step for regenerating the metal oxide catalyst containing iron, antimony and phosphorus. It is described that fluid firing is preferable.

JP 2002-320853 A JP 2003-170044 A JP 7-328447 A

However, when the present inventors actually calcinate an oxide catalyst containing molybdenum and antimony by fluidized calcination in which a gas is introduced into the catalyst bed, there is a problem that the catalyst cannot be consolidated and particles cannot be adhered to each other. occured.
In particular, when the present inventor performed continuous firing using a rotary kiln, there was a problem that the yield of the catalyst was reduced due to the large amount of oxide catalyst and catalyst precursor adhering as fixed substances. Moreover, the adhering matter adhering in large quantities deteriorated the heat transfer to the powder in the calciner, and the calcining temperature decreased with the passage of time. Furthermore, the thickened material layer substantially shortened the residence time of the flowing powder in the furnace, and it could not be fired under appropriate conditions, and the performance of the resulting catalyst deteriorated.

In view of the above circumstances, the problem to be solved by the present invention is to reduce the sticking in the calciner while maintaining the particle shape with respect to the oxide catalyst that generates a compound having a melting point lower than the calcining temperature during the calcining process ( (Suppressing) is to provide a method for efficiently producing a catalyst having excellent performance (high yield of the target product) in a large amount.

Therefore, as a result of intensive studies on the above problems, the present inventors have found that when the catalyst contains a constituent element whose melting point of the metal oxide is lower than the firing temperature, the oxide catalyst and the catalyst precursor are melted. ,
It became clear that it adhered to the inner wall of the calciner. And when manufacturing such a catalyst, by performing the low-temperature treatment process which makes the temperature of a catalyst precursor and / or an oxide catalyst temporarily lower than a calcination temperature during a calcination process, As a result, the inventors have found that a catalyst having excellent performance can be produced in a large amount and efficiently, thereby completing the present invention.

That is, the present invention is as follows.
[1]
A step of supplying a catalyst precursor calcining device, a method of manufacturing an oxide catalyst containing a main firing step of firing at least the melting point of the sintering temperature of the metal oxide of the catalyst constituting elements,
Wherein during the baking step, including a low-temperature process step to a temperature lower than the temporarily the firing temperature the temperature of the catalyst precursor and / or the oxide catalyst, producing the oxide catalyst.
[2]
The method for producing an oxide catalyst according to the above [1], wherein in the low temperature treatment step, the temperature of the catalyst precursor and / or the oxide catalyst is lowered by 10 ° C. or more.
[3]
The method for producing an oxide catalyst according to the above [1], wherein in the low temperature treatment step, the temperature of the catalyst precursor and / or the oxide catalyst is reduced by 50 ° C. or more.
[4]
The method for producing an oxide catalyst according to the above [1], wherein in the low temperature treatment step, the temperature of the catalyst precursor and / or the oxide catalyst is lowered by 100 ° C. or more.
[5]
The method for producing an oxide catalyst according to any one of [1] to [4], further including a step of applying an impact to the calciner in the main calcining step.
[6]
The method for producing an oxide catalyst according to any one of the above [1] to [4], further comprising a step of applying an impact to the calciner in the low-temperature treatment step.
[7]
The method for producing an oxide catalyst according to any one of [1] to [6], further including a pre-stage calcination step performed before the main calcination step .
[8]
The method for producing an oxide catalyst according to the above [7], wherein the main calcination is performed in a temperature range of 550 to 800 ° C.
[9]
The method for producing an oxide catalyst according to the above [7] or [8], wherein the pre-stage calcination is performed in a temperature range of 250 to 400 ° C, and the main calcination is performed in a temperature range of 580 to 750 ° C.
[10]
The method for producing an oxide catalyst according to any one of the above [1] to [ 9 ], wherein a catalyst precursor is continuously supplied to the calciner and calcined by continuous calcining.
[ 11 ]
The method for producing an oxide catalyst according to any one of the above [1] to [ 10 ], wherein the oxide catalyst contains Mo and Sb and / or Te.
[ 12 ]
When the oxide catalyst contains Mo, V, and Nb, and the atomic ratios of V and Nb per Mo atom are a and b, respectively, 0.1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1 The method for producing an oxide catalyst according to any one of [1] to [ 11 ], which is satisfied.
[ 13 ]
[1] to [ 12 ], wherein the oxide catalyst is supported on silica, and the mass of the silica is 10 to 80% by mass in terms of SiO ₂ with respect to the total mass of the oxide catalyst and the silica. The manufacturing method of the oxide catalyst in any one of these.

The production method of the present invention can remarkably reduce the sticking generated in the calciner in the step of calcining the catalyst precursor, and as a result, efficiently produce a catalyst having excellent performance in a large amount. It becomes possible to do.
In addition, since the oxide catalyst obtained by the production method of the present invention has excellent catalytic performance, it can be used for gas phase catalytic oxidation or gas phase catalytic ammoxidation of propane or isobutane. Saturated carboxylic acids or unsaturated nitriles (e.g. (meth) acrylic acid, (
(Meth) acrylonitrile) can be stably produced in high yield.

Hereinafter, the best 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.

[Production method of oxide catalyst]
The method for producing an oxide catalyst of the present embodiment is a method for producing an oxide catalyst including a step of supplying a catalyst precursor to a calciner and calcining at a calcining temperature equal to or higher than the melting point of the metal oxide of the catalyst constituent element. And a low temperature treatment step in which the temperature of the catalyst precursor and / or the oxide catalyst is temporarily lower than the calcining temperature during the calcining step.

In the present embodiment, the “oxide catalyst” refers to a catalyst containing an oxide of one or more metal components. The “catalyst precursor” refers to a compound produced in the production process of the oxide catalyst, which is obtained through a raw material preparation step and a drying step, which will be described later. The “pre-stage calcined powder” after the pre-stage firing is also included. In this embodiment, the “melting point of the metal oxide of the catalyst constituent element” means that the metal component contained in the oxide catalyst and / or catalyst precursor is a single oxide (a single metal component and only two components of oxygen). The melting point when the oxide is formed. When one or more kinds of metal components form a single oxide having a plurality of composition formulas, the melting point of the oxide having the lowest melting point among them is meant. For example, Phase Diagrams for Ceramists (A
According to the American Ceramic Society, the melting point of molybdenum oxide:
MoO ₂ (818 ° C.), MoO ₃ (782 ± 5 ° C.), melting point of antimony oxide: Sb ₂ O ₃
(655 ° C.) and Sb ₂ O ₅ (525 ° C.), the melting point of the metal oxide of the catalyst constituent element is (782-5) ° C. when molybdenum is included, and 525 ° C. when antimony is included, When both are included, the temperature is set to 525 ° C. Specifically, when the oxide catalyst is made of Mo, Sb, V, and Nb and the firing temperature is 650 ° C., the melting point of the antimony single oxide (antimony pentoxide) is lower than the firing temperature. Of “fired at a temperature equal to or higher than the melting point of the metal oxide of the catalyst constituent element”. According to this document, the melting point of niobium oxide Nb ₂ O ₅ is (151
0 ° C.), the melting point of vanadium oxide V ₂ O ₅ is (685 ° C.).

In the present embodiment, “calcination temperature” refers to the temperature at which the oxide catalyst and / or catalyst precursor in the calciner reaches the highest temperature. In the case of batch calcination, the calcination temperature depends on the oxide catalyst and / or
Alternatively, it can be measured by a thermocouple inserted in the catalyst precursor. In the case of continuous calcination, the oxide catalyst and / or catalyst precursor flow while being deposited in the calciner, and the calcination temperature is the thermocouple inserted into the deposited oxide catalyst and / or catalyst precursor. Can be measured.

The oxide catalyst and / or catalyst precursor of the present embodiment includes a metal component that forms a compound having a melting point lower than the firing temperature. When a compound having a melting point lower than the calcination temperature is generated in the calcination step, it is melted during calcination, and an oxide catalyst, a catalyst precursor, and the like are fixed or fused to the inner wall of the calciner to form a lump. Particularly in continuous firing, this causes deterioration of heat transfer, a decrease in residence time, and unstable powder flow, making it difficult to stably fire at a desired temperature.

In the present embodiment, during the calcination step, by performing a low temperature treatment that temporarily lowers the temperature of the catalyst precursor and / or the oxide catalyst to a temperature lower than the calcination temperature, the lump fixed to the inner wall of the calciner is obtained. When the crack is generated and then the catalyst precursor is supplied into the calciner together with an inert gas or the like and the calcining is continued, the lump can be easily separated from the inner wall of the calciner. It is presumed that the reason why cracks occur in the clumps fixed by the low-temperature treatment is caused by solidification of a compound having a melting point at a temperature lower than the firing temperature or shrinkage of the firing device.

Furthermore, the method for producing an oxide catalyst including the low-temperature treatment step of the present embodiment is more effective than the case of directly contacting the catalyst by a method such as mechanically scraping or crushing the fixed matter on the inner wall of the calciner. There is also an advantage that the shape can be maintained well.

From the above viewpoint, the low temperature treatment step is not limited to the case of “calcining at a temperature equal to or higher than the melting point of the metal oxide of the catalyst constituent element”, but also when the compound generated during the firing step has a melting point equal to or lower than the firing temperature. This is effective to prevent sticking. However, since it is not realistic to grasp all the compounds generated during firing, in the present embodiment, in view of the inventor's empirical rules,
Depending on whether or not the melting point of the metal oxide of the catalyst constituent element is equal to or lower than the firing temperature, it is used as an index of occurrence of sticking or the like.

Here, “temporarily” in the low-temperature treatment step means a time sufficient for cracks to be formed in the mass of the fixed catalyst precursor and / or oxide catalyst, and the catalyst production amount, the firing period, and the firing temperature. It is possible to adjust appropriately according to the fixing speed / fixing amount, the period during which the calcination temperature is lowered, the depth (powder depth) of the catalyst precursor deposited in the calcination machine, the diameter / length / thickness / material of the calcination machine, etc. Is possible. The time from when the temperature starts to decrease until the temperature starts again is, for example, an inner diameter of 300 mm and a length of 2500
In the case of using a SUS fired tube having a thickness of 5 mm and a thickness of 5 mm, it is usually 10 minutes to 200 hours, preferably 20 minutes to 96 hours, more preferably 30 minutes to 48 hours. After completion of the low temperature treatment step, the temperature is raised again to the firing temperature and the firing is continued.

Further, the timing for starting the low-temperature treatment is not particularly limited, but the firing of the catalyst precursor and / or oxide catalyst in the calciner increases in the calcining process, and a sufficient calcining temperature cannot be obtained, or the production amount It is preferable to carry out the process before problems such as insufficiency cannot be ensured.

The frequency of low-temperature treatment is as follows: catalyst production amount, calcination period, calcination temperature, fixation rate / fixation amount, period for lowering the calcination temperature, depth of catalyst precursor deposited in the calcination device (powder depth), It is possible to adjust appropriately according to the diameter, length, thickness, material, etc. For example, inner diameter 300mm, length 2
In the case of using a SUS fired tube having a thickness of 500 mm and a thickness of 5 mm, it is preferably at least once every 6 months, more preferably at least once every 3 months, even more preferably at least once a month, particularly preferably 2 At least once a week.

The method for lowering the temperature of the catalyst precursor and / or oxide catalyst in the low-temperature treatment step may be a general method, and a method such as lowering the temperature of the heater or turning off the heater power can be adopted. The lowering temperature can be appropriately adjusted according to the catalyst production amount, continuous firing period, firing temperature, fixing speed / fixed amount and the period of reduction, preferably 10 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 100 ° C. As described above, the temperature is particularly preferably lowered by 200 ° C. or more.
From the viewpoint of removing the stuck catalyst precursor and / or oxide catalyst mass, it is preferable to lower the temperature of the catalyst precursor and / or oxide catalyst to below the “melting point of the metal oxide of the catalyst constituent element”. It is estimated to be. However, in addition to the metal oxide, other compounds having a relatively high melting point can be generated during firing, so that the fixed object can be obtained even if the temperature of the low temperature treatment does not necessarily reach below the melting point of the metal oxide. The effect which makes it easy to remove can be acquired. In particular, this tendency is remarkable in firing an oxide catalyst composed of a plurality of metals. The temperature lowering rate is not particularly limited, but cracking tends to occur in the lump when the temperature is quickly lowered at a temperature lowering rate that does not damage the calciner, and therefore preferably 0.1 to 50 ° C./min, more preferably 0. .5-40
The temperature is lowered at a rate of 1 ° C / minute, more preferably 1-30 ° C / minute.

The catalyst precursor may continue to be supplied during the low temperature treatment, but if the temperature of the calciner is low, the catalyst precursor becomes insufficiently calcined and may not be a catalyst with good performance. It is preferable to start supplying the catalyst precursor again after the low temperature treatment is completed.

Also, if an impact is applied to the calciner in the firing process, the effect of causing cracks in the fixed mass tends to increase. In particular, if an impact is applied to the calciner during the low-temperature treatment process, the cracked mass is fired. This is preferred because it tends to peel easily from the vessel.

The impact applied to the calciner depends on the powder depth of the catalyst precursor supplied into the calciner, the diameter, length, thickness, and material of the calciner, the material, type, shape, position, and impact of the device that applies the impact. Since it depends on the frequency of addition, etc., it is preferable to set appropriately.

From the viewpoint of sufficiently reducing the adhesion to the inner wall of the calciner, the vibration acceleration at a place where impact is applied (hereinafter also referred to as impact point) is preferably 0.1 m / s ² or more, more preferably 1 m / s. ² or more, more preferably 5 m / s ² or more, and particularly preferably 10 m / s ² or more. Further, from the viewpoint of preventing breakage of the calciner and not disturbing the flow of the powder flowing through the calciner, it is preferably 3000 m / s ² or less, more preferably 1000 m.
/ S ² or less, more preferably 500 m / s ² or less, particularly preferably 300
m / s ² or less.

In the present embodiment, the “vibration acceleration” of the impact applied to the calciner is L / 4, 3L / 8, L from the calciner powder inlet in parallel to the powder flow direction with respect to the calciner full length L. It means the average value of the values measured at a distance of / 2. The measurement position is the same position as the impact point in the cross-sectional direction of the calciner. The vibration acceleration can be measured with a vibrometer attached to the baking machine. As the vibrometer, MD220 manufactured by Asahi Kasei Techno System Co., Ltd. can be used.

The method for applying the impact is not particularly limited, and an air knocker, hammer, hammering device, or the like can be preferably used. The material of the portion that directly contacts the firing device at the tip of the impact is not particularly limited as long as the material has sufficient heat resistance, for example, a general resin that can withstand impact, metal, etc. can be used, Of these, metals are preferred. The metal preferably has a hardness that does not damage or deform the calciner, and can be suitably made of copper or SUS. The location to which the impact is applied is not particularly limited and can be performed at a location convenient for operation. However, since the impact can be directly applied to the calciner without waste, it is applied to the location not covered with the heating furnace of the calciner. It is preferable.

The place where the impact is applied may be one place or a plurality of places. In order to transmit vibration efficiently, it is preferable to apply the impact from a direction perpendicular to the rotation axis. The frequency at which the impact is applied is not particularly limited, but it is preferable that the impact is steadily applied to the calciner because the adhesion in the calciner tends to be reduced more favorably. Here, “constantly applying impact” is preferably 1 second or longer 1
Applying an impact once per hour, more preferably once every 1 second to 30 minutes, more preferably once every 1 second to 5 minutes, particularly preferably once every 1 second to 1 minute. means. The frequency at which the impact is applied is appropriately adjusted according to the vibration acceleration, the powder depth of the catalyst precursor supplied into the calciner, the diameter / length / thickness / material of the calciner, and the material / type / shape of the device to which the impact is applied. It is preferable to do.

The shape of the calciner used in the manufacturing method of the present embodiment is not particularly limited.
Continuous firing 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 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 the inner diameter is preferably 70 to 2000 mm, more preferably 100 to 1200 mm, and the length is preferably The thing of 200-10000 mm, More preferably, the thing of 800-8000 mm is used.

The thickness of the calciner is not particularly limited as long as it is sufficient to prevent damage by impact, but it is preferably 2 mm or more, more preferably 4 mm or more. Further, from the viewpoint of sufficiently transmitting the impact to the inside of the baking machine, the thickness is preferably 100 mm or less, more preferably 50 mm or less. The material is not particularly limited as long as it has heat resistance and has a strength that is not damaged by an impact. For example, SUS can be suitably used.

The firing in the manufacturing method of the present embodiment may be either continuous firing or batch firing. Normally, continuous calcination makes it possible to produce a large amount of catalyst compared to batch calcination, but continuous calcination tends to cause variations in residence time and calcination temperature. There is a tendency that firing is difficult at an optimum firing time and firing temperature. Therefore, even if the catalyst composition and firing temperature are the same, in the case of continuous firing, it may be difficult to obtain a yield equivalent to that of batch firing.

In the case where the calcination is carried out continuously, a weir plate having a hole for the passage of the catalyst precursor and / or oxide catalyst at the center is provided in the calcination device perpendicular to the flow of the catalyst precursor, and the calcination device is provided. It can also be divided into two or more areas. By installing the weir plate, it becomes easy to secure the residence time in the calciner. The number of weir plates may be one or more. The material of the weir plate is preferably a metal, and the same material as that of the calciner 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 a catalyst precursor at 250 g / hr in a rotary furnace having a SUS calciner having an inner diameter of 150 mm and a length of 1150 mm, the barrier plate is preferably 5 to 50 mm, more preferably 10 to 40 mm, and still more preferably 13-35 mm. The thickness of the weir plate is not particularly limited and is preferably adjusted according to the size of the calciner. For example, an inner diameter of 150 mm,
In the case of a rotary furnace having a SUS calciner having a length of 1150 mm, it is preferably 0.3 mm or more and 30 mm or less, more preferably 0.5 mm or more and 15 mm or less.

In the firing step, it is preferable to rotate the calciner in order to prevent cracking and cracking of the catalyst precursor and to perform uniform firing. The rotation speed of the calciner is preferably 0.1-30 rp
m, more preferably 0.3 to 20 rpm, still more preferably 0.5 to 10 rpm.

In calcination of the dried catalyst precursor, the temperature is raised from a temperature lower than 400 ° C.
It is preferable to raise the temperature continuously or intermittently to a temperature within the range of 800 ° C.

The firing atmosphere can be carried out in an air atmosphere or 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.

When the calcination is carried out batchwise, the supply amount of the inert gas is 50 N per 1 kg of the catalyst precursor.
Liter / hr or more, preferably 50 to 5000 N liter / hr, more preferably 5
0 to 3000 N liter / hr (N liter is a standard temperature / pressure condition, that is, 0 ° C.,
Means liters measured at 1 atm). When the calcination is carried out continuously, the supply amount of the inert gas is 50 N liters or more, preferably 50 to 5000 N liters, preferably 50 to 3000 N liters per 1 kg of the catalyst precursor (N liter is a standard temperature / pressure). conditions,
That is, liters measured at 0 ° C. and 1 atmosphere). At this time, the inert gas and the catalyst precursor may be counter-current or co-current, but counter-current contact is preferable in consideration of gas components generated from the catalyst precursor and air mixed in a small amount together with the catalyst precursor.

The calcination step can be carried out even in one stage, but it is preferable to perform the pre-stage calcination before the main calcination because the reduction rate of the catalyst tends to be easily adjusted to an appropriate range efficiently. As a temperature range, it is preferable to perform pre-baking at 250 to 400 ° C. and main baking at 550 to 800 ° C. 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. When firing is performed separately in the pre-stage firing and the main firing, it is preferable to perform a low temperature treatment in the main firing.

The pre-stage calcination is preferably performed in the range of a heating temperature of 250 to 400 ° C., preferably 300 to 400 ° C. under an inert gas flow. Although it is preferable to hold at a constant temperature within a temperature range of 250 ° C. to 400 ° C., the temperature may fluctuate within the range of 250 ° C. to 400 ° C., or the temperature may be gradually increased or decreased. The holding time of the heating temperature is 30 minutes or 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.

The average rate of temperature rise during the temperature rise until reaching the pre-stage firing temperature is not particularly limited, but is preferably 0.1 to 15 ° C / min, more preferably 0.5 to 5 ° C / min, and still more preferably 1 ˜2 ° C./min.

The main calcination is preferably performed under an inert gas flow at a heating temperature of 550 to 800 ° C., preferably 58
It is carried out at 0 to 750 ° C, more preferably 600 to 720 ° C, particularly preferably 620 to 700 ° C. Although it is preferable to hold at a constant temperature within a temperature range of 620 to 700 ° C,
The temperature may fluctuate within a range of 700 ° C., or the temperature may be gradually increased or decreased. The firing time is 0.5 to 20 hours, preferably 1 to 15 hours. 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 preferably 0.1 to 15 ° C / min, more preferably 0.5 to 10 ° C / min, and still more preferably 1 ˜5 ° C./min.

The average temperature drop rate after the completion of the main firing is 0.01 to 1000 ° C./min, preferably 0.05 to
100 ° C./min, more preferably 0.1 to 50 ° C./min, still more preferably 0.5 to
10 ° C./min. Moreover, it is also preferable to hold once at a temperature lower than the main firing temperature.
The temperature to be held is 5 ° C., preferably 10 ° C., more preferably 50 ° C. lower 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 calciner is separated by a dam plate, the catalyst precursor passes through at least two, preferably 2 to 20, more preferably 4 to 15 zones, each of which can be temperature controlled. For example, in the case where seven pieces of dam plates are placed so as to divide the length of the portion entering the heating furnace of the baking unit into eight equal parts and a baking unit divided into eight areas is used, in order to obtain the desired baking pattern, Adjustments can be made as follows. In the pre-stage calcination, the temperature of the thermocouple inserted in the central portion of the catalyst precursor staying in the calciner is counted from the supply side of the catalyst precursor, as shown in the section 1: 100 to 300 ° C., section 2: 150-350 ° C, Zone 3: 250-400 ° C, Zone 4: 250-400 ° C, Zone 5: 300-400 ° C, Zone 6: 300-400 ° C, Zone 7
: 310-400 ° C, Section 8: It is preferable to adjust so as to be 260-400 ° C.
More preferably, Zone 1: 120-280 ° C, Zone 2: 180-330 ° C, Zone 3:25
0-350 ° C, Zone 4: 270-380 ° C, Zone 5: 300-380 ° C, Zone 6: 300
~ 390 ° C, Zone 7: 320-390 ° C, Zone 8: 260-380 ° C. Similarly, in this firing, zone 1: 350-600 ° C, zone 2: 400-700 ° C, zone 3: 550-70.
0 ° C, zone 4: 550-700 ° C, zone 5: 550-700 ° C, zone 6: 450-680
It is preferable to adjust so that it may become C degree, area 7: 450-650 degreeC, and area 8: 350-600 degreeC. More preferably, zone 1: 360-560 ° C, zone 2: 450-650 ° C, zone 3: 600-690 ° C, zone 4: 620-690 ° C, zone 5: 580-690 ° C, zone 6: 480-660. ° C, zone 7: 450-630 ° C, zone 8: 370-580 ° C.

[Oxide catalyst]
As an oxide catalyst obtained by the manufacturing method of this Embodiment, the compound shown by following General formula (1) containing molybdenum, vanadium, and niobium can be mentioned, for example.
_{Mo 1 V a Nb b X c} Y d O n (1)
(In the formula, X represents at least one element selected from Te and Sb, and Y represents Mn.
, W, B, Ti, Al, at least one element selected from alkali metals, alkaline earth metals and rare earth metals, a, b, c, d and n are V, Nb, X, Y
Is an atomic ratio per one molybdenum (Mo) atom, 0.1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1
0.01 ≦ c ≦ 1, 0 ≦ d ≦ 1, and n represents the number of oxygen atoms determined by the valence of the constituent elements other than oxygen. )

Atomic ratio a per Mo ₁ atom, b, c, d, respectively, 0.1 ≦ a ≦ 1,0.01 ≦
b ≦ 1, 0.01 ≦ c ≦ 1, 0 ≦ d ≦ 1, preferably 0.1 ≦ a ≦ 0.5, 0
. More preferably, 01 ≦ b ≦ 0.5, 0.1 ≦ c ≦ 0.5, 0.0001 ≦ d ≦ 0.5, 0.2 ≦ a ≦ 0.3, 0.05 ≦ b ≦ 0.2, 0.2 ≦ c ≦ 0.3, 0.00
More preferably, 02 ≦ d ≦ 0.4.

A material containing Mo and Sb and / or Te is easily oxidized in a calciner and is an oxide catalyst suitable for applying the manufacturing method of the present embodiment.

When the catalyst is used in a fluidized bed, sufficient strength is required, so that the oxide catalyst is preferably supported on a silica support. The oxide catalyst is preferably 10 to 80% by mass, more preferably 20 to 60% in terms of SiO ₂ with respect to the total mass of the oxides of the catalyst constituent elements and silica.
It is supported on silica by mass%, more preferably 30-55 mass%. The amount of the silica carrying the oxide catalyst is determined from the viewpoint of strength and prevention of pulverization, ease of stable operation when using the catalyst, and reduction of replenishment of the lost catalyst. 10 for the total mass
From the viewpoint of achieving sufficient catalytic activity, it is preferably 80% by mass or less based on the total mass of the oxides of the catalyst constituent elements and silica. In particular, when the catalyst is used in a fluidized bed, if the amount of silica is 80% by mass or less, the specific gravity of the catalyst supported on silica is appropriate, and it is easy to create a good fluidized state.

In the method for producing an oxide catalyst of the present embodiment, the “catalyst precursor” supplied to the calciner can be obtained, for example, by performing the following raw material preparation step and drying step. In addition,
If the firing process consists of pre-stage firing and main-stage firing, the "pre-stage fired powder" after the pre-stage firing
Is also included in the “catalyst precursor”.
Hereinafter, each step will be described.

(Raw material preparation process)
This step is a step of obtaining a raw material preparation liquid by dissolving and mixing a raw material containing a metal component in a solvent such as water.

It does not specifically limit as a raw material containing a metal component, For example, the following compound can be used. Examples of the Mo material include molybdenum oxide, ammonium dimolybdate, ammonium heptamolybdate, phosphomolybdic acid, and silicomolybdic acid. Among these, ammonium heptamolybdate can be preferably used. Examples of the raw material for V include vanadium pentoxide, ammonium metavanadate, and vanadyl sulfate. Among them, ammonium metavanadate can be preferably used. Examples of the raw material for Nb include at least one selected from the group consisting of niobic acid, an inorganic acid salt of niobium, and an organic acid salt of niobium. Among these, niobic acid is preferable. Niobic acid is Nb ₂ O ₅ · nH ₂ O
And is also referred to as niobium hydroxide or niobium oxide hydrate. Among them, the niobium raw material contains a dicarboxylic acid and a niobium compound, and the molar ratio of dicarboxylic acid / niobium is 1 to 1.
4 niobium raw material liquid is preferably used. When Te is added as the other element, telluric acid can be preferably used as a raw material for Te. When Sb is added, antimony oxide can be preferably used as a raw material for Sb.

Below, this process is demonstrated concretely by the example which prepares the raw material preparation liquid containing Mo, V, Nb, and Sb.
First, ammonium heptamolybdate, ammonium metavanadate, and antimony trioxide powder are added to water and heated to 80 ° C. or higher to prepare a mixed solution (A). At this time, for example, when the catalyst contains Te, B, or Ce, telluric acid, boric acid, and cerium nitrate can be added simultaneously.
Next, niobic acid and oxalic acid are heated and stirred in water to prepare a mixed solution (B). Mixed liquid (B
) Is obtained by the method shown below. That is, niobic acid and oxalic acid are added to water and stirred to obtain an aqueous solution or aqueous suspension. In the case of suspension, dissolution of the niobium compound can be promoted by adding a small amount of aqueous ammonia or heating. The aqueous solution or suspension is then cooled and filtered to obtain a niobium-containing liquid. Cooling can be carried out simply by ice-cooling, and filtration can be carried out simply by decantation or filtration. Oxalic acid can be appropriately added to the obtained niobium-containing liquid to prepare a suitable oxalic acid / niobium ratio. The molar ratio of oxalic acid / niobium is preferably 2-5, more preferably 2
~ 4. Furthermore, hydrogen peroxide may be added to the obtained niobium mixed solution to prepare a mixed solution (B). At this time, the molar ratio of hydrogen peroxide / niobium is preferably 0.5 to 20, and more preferably 1 to 10.
Next, the mixed solution (A) and the mixed solution (B) are mixed according to the target composition to obtain a raw material preparation solution. For example, when the catalyst contains W or Mn, a compound containing W is suitably mixed to obtain a raw material preparation solution. As the compound containing W, for example, ammonium metatungstate is suitably used. As a compound containing Mn, for example, manganese nitrate is preferably used.
The compound containing W or Mn can be added to the mixed liquid (A), or can be added simultaneously when the mixed liquid (A) and the mixed liquid (B) are mixed. When the oxide catalyst is supported on a silica carrier, the raw material preparation liquid is prepared so as to contain the silica sol, and in this case, the silica sol can be appropriately added.
Moreover, when using antimony, it is preferable to add hydrogen peroxide to the liquid containing the component of the liquid mixture (A) or the liquid mixture (A) in the middle of preparation. At this time, H ₂ O ₂ / Sb (molar ratio)
Is preferably 0.01-5, more preferably 0.05-4. Moreover, it is preferable at this time to continue stirring at 30 ° C. to 70 ° C. for 30 minutes to 2 hours. The catalyst raw material preparation liquid thus obtained may be a uniform solution, but is usually a slurry.

(Drying process)
This step is a step of drying the raw material preparation liquid obtained in the above-described step to obtain a (dry) catalyst precursor. Drying can be performed by a known method, for example, spray drying or evaporation to dryness, but it is preferable to obtain a microspherical dry catalyst precursor 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.
The dryer outlet temperature is preferably 100 to 160 ° C.

[Production method of unsaturated acid and unsaturated nitrile]
Using the oxide catalyst obtained by the production method of the present embodiment, propane or isobutane is reacted with molecular oxygen in the gas phase (gas phase catalytic oxidation reaction), and the corresponding unsaturated carboxylic acid (acrylic acid or Methacrylic acid) can be produced. Using this catalyst, propane or isobutane reacts with ammonia and molecular oxygen in the gas phase (gas phase ammoxidation reaction).
Thus, the corresponding unsaturated nitrile (acrylonitrile or methacrylonitrile) can be produced.

Propane or isobutane and ammonia feeds do not necessarily have to be high purity, and industrial grade gases can be used. As the supply oxygen source, air, pure oxygen, or air enriched with pure oxygen can be used. Furthermore, helium, neon, argon, carbon dioxide gas, water vapor, nitrogen or the like may be supplied as a dilution gas.

In the case of an ammoxidation reaction, the molar ratio of ammonia supplied to the reaction system to propane or isobutane is 0.3 to 1.5, preferably 0.8 to 1.2. In both the oxidation reaction and the ammoxidation reaction, the molar ratio of molecular oxygen supplied to the reaction system to propane or isobutane is 0.1 to 6, preferably 0.1 to 4.

Also, for both the oxidation reaction and the ammoxidation reaction, the reaction pressure is 0.5 to 5 atm,
The reaction temperature is preferably 1 to 3 atm, and the reaction temperature is 350 ° C to 500 ° C, preferably 380 ° C to
470 ° C., and 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 defined by the following equation.
Contact time (sec · g / cc) = (W / F) × 273 / (273 + T) × P
here,
W = mass of catalyst (g),
F = Raw material mixed gas flow rate (Ncc / sec) in standard state (0 ° C., 1 atm),
T = reaction temperature (° C.) and P = reaction pressure (atm).

Conventional reaction systems such as a fixed bed, fluidized bed, and moving bed can be adopted as the reaction system, but the heat of reaction can be easily removed and the temperature of the catalyst layer can be maintained almost uniformly, and the catalyst is extracted from the reactor during operation. Or a fluidized bed reaction is preferable because a catalyst can be added.

Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples. However, the present embodiment is not limited to these examples.

In the examples and comparative examples, the propane conversion, the acrylonitrile yield, and the acrylic acid yield follow the following definitions, respectively.
Propane conversion (%) = (moles of propane reacted) / (moles of propane fed) × 100
Acrylonitrile yield (%) = (Mole number of acrylonitrile produced) / (Mole number of supplied propane) × 100
Acrylic acid yield (%) = (number of moles of acrylic acid produced) / (number of moles of supplied propane) × 100

(Preparation of niobium raw material liquid)
A niobium raw material solution was prepared by the following method. 76.33 kg of niobic acid containing 80.2% by mass as Nb ₂ O _{5 in} 500 kg of water and oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] 2
9.02 g was mixed. The molar ratio of charged oxalic acid / niobium was 5.0, and the concentration of charged niobium was 0.532 (mol-Nb / kg-solution).
This solution was heated and stirred at 95 ° C. for 1 hour to obtain an aqueous solution in which the niobium compound was dissolved. The aqueous solution was allowed to stand and ice-cooled, and then the solid was separated by suction filtration to obtain a uniform aqueous niobium compound solution. The same operation was repeated several times, and the obtained niobium compound aqueous solution was combined into one niobium raw material solution. The molar ratio of oxalic acid / niobium in this niobium raw material liquid was 2.40 according to the following analysis.
In a crucible, 10 g of this niobium raw material solution was precisely weighed, dried overnight at 95 ° C., and then heat-treated at 600 ° C. for 1 hour to obtain 0.8323 g of Nb ₂ O ₅ . From this result, the niobium concentration is 0.627 (
mol-Nb / kg-solution).
In a 300 mL glass beaker, 3 g of this niobium raw material solution is precisely weighed, and hot water 200
mL was added followed by 10 mL of 1: 1 sulfuric acid. The obtained solution was titrated with 1 / 4N KMnO ₄ under stirring while maintaining the liquid temperature at 70 ° C. on a hot stirrer. KMnO ₄
The end point was a point where the faint pale pink color continued for about 30 seconds or more. The concentration of oxalic acid was 1.50 (mol-oxalic acid / kg) as a result of calculation from the titration amount according to the following formula.
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 raw material liquid was used as a niobium raw material liquid in the production of the following oxide catalyst.

Example 1
Composition formula was prepared a catalyst represented by _{Mo 1 V 0.22 Nb 0.095 Sb 0.25} O n / 42 wt% -SiO ₂ as follows.
(Preparation of raw material mixture)
Water 43.5kg ammonium heptamolybdate _{[(NH 4) 6Mo 7 O 24} · 4H
₂ O] 9.68 kg, ammonium metavanadate [NH ₄ VO ₃ ] 1.40 kg,
1.99 kg of diantimony trioxide [Sb ₂ O ₃ ] was added and heated at 90 ° C. for 2.5 hours with stirring to obtain an aqueous mixed solution A-1.
1.87 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added to 8.74 kg of the niobium raw material liquid. The liquid temperature was maintained at about 20 ° C., and the mixture was stirred and mixed to obtain an aqueous liquid B-1.
After cooling the obtained aqueous mixed liquid A-1 to 70 ° C., 16.6 kg of silica sol containing 30.4% by mass as SiO ₂ was added. Next, 2.32 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added, and the mixture was stirred and mixed at 50 ° C. for 1 hour, and then the aqueous liquid B-1
Was added. Furthermore, a liquid in which 3.36 kg of fumed silica was dispersed in 47.0 kg of water was added to obtain a raw material preparation liquid.
In order to perform the “preparation of dry catalyst precursor” step and the “calcination” step, which will be described later, in a continuous manner, this step was repeated 103 times to prepare a total of about 2000 kg of the raw material mixture.
(Preparation of dry catalyst precursor)
The obtained raw material mixture was supplied to a centrifugal spray dryer and dried to obtain a microspherical dry catalyst precursor. The dryer inlet temperature was 210 ° C. and the outlet temperature was 120 ° C.
(Baking)
Five dam plates with a height of 85 mm were placed on a SUS fired tube having an inner diameter of 300 mm, a length of 2500 mm, and a wall thickness of 5 mm so that the length of the heating furnace portion was equally divided into six. While rotating this calcining tube at 3 rpm, the dry catalyst precursor was circulated at a rate of 3 kg / hr, heated to 360 ° C. over about 4 hours under a nitrogen gas flow of 70000 N liter / min, and heated at 360 ° C. for 3 hours. The temperature of the heating furnace was set so that the temperature profile was maintained for a time, and the pre-stage calcined powder was obtained by continuous pre-stage firing. The obtained pre-stage calcined powder was separated into another inner diameter of 300 mm and a length of 2500 mm.
A SUS fired tube with a thickness of 5 mm and seven weir plates with a height of 85 mm were placed on a fired tube placed so that the length of the heating furnace portion was divided into 6 parts at 2.5 rpm / hr while rotating at 3 rpm. Hammering with a hammer with a 2.5 kg weight made of SUS at the tip of the striking part from the direction perpendicular to the rotation axis, on the powder introduction side of the firing tube (the part not covered with the heating furnace) While applying a blow once every 30 seconds from a height of 80 mm above the firing tube in a direction perpendicular to the rotation axis, 645
The temperature was raised to 2 ° C./min at 2 ° C./min, calcined at 645 ° C. for 2 hours, and the temperature of the heating furnace was set so that the temperature profile decreased at 1 ° C./min, and continuous firing was continued for 13 days. At this time, the vibration acceleration of the firing tube was 30 m / s ² . Thereafter, the heating furnace was turned off, the supply of the pre-stage calcined powder was stopped, and the temperature of the catalyst precursor and / or oxide catalyst was reduced by 200 ° C. The temperature of the catalyst precursor and / or oxide catalyst is lowered to 445 ° C., and after 1 hour has passed, the heating furnace is turned on again to the set temperature before stopping the heating, and the pre-stage calcined powder is reduced to 2.5 kg / h
The main calcination was resumed by supplying at r. Hammering with hammering equipment continued during low temperature processing.
During the main calcination, an oxide catalyst could be obtained at a stable rate.
(Evaluation of catalyst performance)
[Ammoxidation reaction]
An oxide catalyst 45 g obtained from the exit of the calcining tube when 40 hours have passed after the resumption of calcining was filled in a Vycor glass fluidized bed type reaction tube having an inner diameter of 25 mm, and propane: ammonia: oxygen: A mixed gas having a molar ratio of helium = 1: 0.85: 3.0: 11 was passed at a contact time of 3.1 (sec · g / cc). As a result of evaluating the performance of the catalyst,
The propane conversion was 89.8% and the acrylonitrile yield was 53.4%.
[Oxidation reaction]
An oxide catalyst 45 g obtained from the exit of the firing tube when 40 hours passed after the resumption of firing was filled in a Vycor glass fluidized bed reaction tube having an inner diameter of 25 mm, and propane: oxygen: helium = at a reaction temperature of 420 ° C. and a reaction pressure and normal pressure. A mixed gas having a molar ratio of 1: 3.0: 11 is used for a contact time of 3.0 (
sec · g / cc). As a result of evaluating the performance of the catalyst, the propane conversion was 81.2.
%, And the acrylic acid yield was 46.2%.

(Example 2)
Baking was not performed on the calcining tube, but calcining was carried out in the same manner as in Example 1 except that continuous calcining was continued for 3 days and then low-temperature treatment was performed to obtain an oxide catalyst. When the performance in the ammoxidation reaction of the oxide catalyst obtained from the calcining tube outlet was evaluated after 40 hours had elapsed since the resumption of calcination as in Example 1, the propane conversion was 87.0% and the acrylonitrile yield was 52.5%. Met.

(Example 3)
Firing was carried out in the same manner as in Example 1 except that the temperature of the catalyst precursor and / or oxide catalyst was lowered by 100 ° C. to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate. When the performance in the ammoxidation reaction of the oxide catalyst obtained from the calcining tube outlet was evaluated after 40 hours had elapsed since the resumption of calcination as in Example 1, the propane conversion was 9
The yield was 0.1% and the acrylonitrile yield was 53.0%.

Example 4
Firing was performed in the same manner as in Example 1 except that the temperature of the catalyst precursor and / or oxide catalyst was reduced by 300 ° C., to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate. When the performance in the ammoxidation reaction of the oxide catalyst obtained from the calcining tube outlet was evaluated after 40 hours had elapsed since the resumption of calcination as in Example 1, the propane conversion was 9
The yield was 0.3% and the acrylonitrile yield was 53.6%.

(Example 5)
Composition formula _{Mo 1 V 0.22 Nb 0.095 Sb 0.25} W 0.02 Ce 0.007 O n
A catalyst represented by / 42% by mass-SiO ₂ was produced as follows.
(Preparation of raw material mixture)
Water 42.3kg ammonium heptamolybdate _{[(NH 4) 6Mo 7 O 24} · 4H
₂ O] was 9.43Kg, ammonium metavanadate _[NH 4 VO _3] 1.34 kg,
1.94 kg of diantimony trioxide [Sb ₂ O ₃ ], cerium nitrate [Ce (NO ₃ ) _3.
6H ₂ O] was added, and the mixture was heated at 90 ° C. for 2.5 hours with stirring to obtain an aqueous mixture A-1.
1.14 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added to 8.51 kg of the niobium raw material liquid. The liquid temperature was maintained at about 20 ° C., and the mixture was stirred and mixed to obtain an aqueous liquid B-1.
After cooling the obtained aqueous mixed liquid A-1 to 70 ° C., 16.6 kg of silica sol containing 30.4% by mass as SiO ₂ was added. Next, 2.25 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, aqueous liquid B-1 was added. Subsequently, 0.489 kg of ammonium metatungstate containing 50.2% by mass as WO ₃ was added, and further a liquid in which 3.36 kg of fumed silica was dispersed in 47.0 kg of water was added to prepare a raw material preparation liquid Got.
In order to perform the “preparation of dry catalyst precursor” step and the “calcination” step, which will be described later, in a continuous manner, this step was repeated 103 times to prepare a total of about 2000 kg of the raw material mixture.
(Preparation of dry catalyst precursor)
Spray drying was performed in the same manner as in Example 1 to obtain a dry catalyst precursor.
(Baking)
Firing was performed in the same manner as in Example 1 to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate.
(Evaluation of catalyst performance)
When the catalyst was evaluated in the ammoxidation reaction of the oxide catalyst obtained from the calcining tube outlet when 40 hours had elapsed after resuming calcining by the same method as in Example 1, the propane conversion was 90.
The acrylonitrile yield was 53.5%.

(Example 6)
Composition formula _{Mo 1 V 0.22 Nb 0.095 Sb 0.25} W 0.02 O n / 42 wt% -
A catalyst represented by SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Water 42.5kg ammonium heptamolybdate _{[(NH 4) 6Mo 7 O 24} · 4H
₂ O] 9.48 kg, ammonium metavanadate [NH ₄ VO ₃ ] 1.37 kg,
1.95 kg of diantimony trioxide [Sb ₂ O ₃ ] was added, and the mixture was heated at 90 ° C. for 2.5 hours with stirring to obtain an aqueous mixture A-1.
1.85 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added to 8.55 kg of the niobium raw material liquid. The liquid temperature was maintained at about 20 ° C., and the mixture was stirred and mixed to obtain an aqueous liquid B-1.
After cooling the obtained aqueous mixed liquid A-1 to 70 ° C., 16.6 kg of silica sol containing 30.4% by mass as SiO ₂ was added. Next, 2.27 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then aqueous liquid B-1 was added. Subsequently, 0.492 kg of ammonium metatungstate containing 50.2% by mass as WO ₃ was added, and further, a liquid in which 3.36 kg of fumed silica was dispersed in 47.0 kg of water was added to prepare a raw material preparation liquid Got.
In order to perform the “preparation of dry catalyst precursor” step and the “calcination” step, which will be described later, in a continuous manner, this step was repeated 103 times to prepare a total of about 2000 kg of the raw material mixture.
(Preparation of dry catalyst precursor)
Spray drying was performed in the same manner as in Example 1 to obtain a dry catalyst precursor.
(Baking)
Firing was performed in the same manner as in Example 1 to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate.
(Evaluation of catalyst performance)
When the performance of the oxide catalyst obtained from the calcining tube outlet in the ammoxidation reaction was evaluated after 40 hours had elapsed since the resumption of calcination as in Example 1, the propane conversion was 90.4% and the acrylonitrile yield was 53.3%. Met.

(Example 7)
Composition formula _{Mo 1 V 0.22 Nb 0.095 Sb 0.25} B 0.2 Ce 0.006 O n /
The catalyst represented by 42 wt% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Water 41.0kg ammonium heptamolybdate _{[(NH 4) 6Mo 7 O 24} · 4H
₂ O], 9.14 kg, ammonium metavanadate [NH ₄ VO ₃ ], 1.32 kg,
1.88 kg of diantimony trioxide [Sb ₂ O ₃ ], cerium nitrate [Ce (NO ₃ ) _3.
6H ₂ O] and 0.142 kg of boric acid [H ₃ BO ₃ ] were added, and the mixture was heated at 90 ° C. for 2.5 hours with stirring to obtain an aqueous mixture A-1.
1.11 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added to 8.25 kg of the niobium raw material liquid. The liquid temperature was maintained at about 20 ° C., and the mixture was stirred and mixed to obtain an aqueous liquid B-1.
After cooling the obtained aqueous mixed liquid A-1 to 70 ° C., 16.6 kg of silica sol containing 30.4% by mass as SiO ₂ was added. Next, 2.19 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then aqueous liquid B-1 was added. Subsequently, 0.474 kg of ammonium metatungstate containing 50.2% by mass as WO ₃ was added, and further a liquid in which 3.36 kg of fumed silica was dispersed in 47.0 kg of water was added to prepare a raw material preparation liquid Got.
In order to perform the “preparation of dry catalyst precursor” step and the “calcination” step, which will be described later, in a continuous manner, this step was repeated 103 times to prepare a total of about 2000 kg of the raw material mixture.
(Preparation of dry catalyst precursor)
Spray drying was performed in the same manner as in Example 1 to obtain a dry catalyst precursor.
(Baking)
Firing was performed in the same manner as in Example 1 to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate.
(Evaluation of catalyst performance)
When the performance in the ammoxidation reaction of the oxide catalyst obtained from the outlet of the calcining tube was evaluated after 40 hours had elapsed after resuming the calcining by the same method as in Example 1, the propane conversion was 89.0.
%, And the acrylonitrile yield was 53.2%.

(Example 8)
Composition formula is Mo ₁ V _0.22 Nb _0.095 Sb _0.25 W _0.025 Mn _0.003 O
A catalyst represented by _n / 42% by mass-SiO ₂ was produced as follows.
(Preparation of raw material mixture)
Water 40.9kg ammonium heptamolybdate _{[(NH 4) 6Mo 7 O 24} · 4H
₂ O], 9.42 kg, ammonium metavanadate [NH ₄ VO ₃ ], 1.36 kg,
1.94 kg of diantimony trioxide [Sb ₂ O ₃ ] was added, and the mixture was heated at 90 ° C. for 2.5 hours with stirring to obtain an aqueous mixture A-1.
To the 8.50 kg of the niobium raw material liquid, 1.14 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added. The liquid temperature was maintained at about 20 ° C., and the mixture was stirred and mixed to obtain an aqueous liquid B-1.
After cooling the obtained aqueous mixed liquid A-1 to 70 ° C., 16.6 kg of silica sol containing 30.4% by mass as SiO ₂ was added. Next, 2.25 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, aqueous liquid B-1 was added. Subsequently, manganese nitrate _{[Mn (NO 3) 2 · 6H} 2 O ] 0.045 kg, WO
₃ , 0.613 kg of ammonium metatungstate containing 50.2% by mass was added, and a liquid prepared by dispersing 3.36 kg of fumed silica in 47.0 kg of water was added to obtain a raw material preparation liquid.
In order to perform the “preparation of dry catalyst precursor” step and the “calcination” step, which will be described later, in a continuous manner, this step was repeated 103 times to prepare a total of about 2000 kg of the raw material mixture.
(Preparation of dry catalyst precursor)
Spray drying was performed in the same manner as in Example 1 to obtain a dry catalyst precursor.
(Baking)
Firing was performed in the same manner as in Example 1 to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate.
(Evaluation of catalyst performance)
When the performance in the ammoxidation reaction of the oxide catalyst obtained from the exit of the calcining tube was evaluated after 40 hours had elapsed after resuming the calcining by the same method as in Example 1, the propane conversion was 88.8.
%, And the acrylonitrile yield was 53.1%.

Example 9
Firing was carried out in the same manner as in Example 1 except that the temperature of the catalyst precursor and / or oxide catalyst was lowered by 5 ° C. to obtain an oxide catalyst. 40 after resuming firing by the same method as in Example 1.
When the performance in the ammoxidation reaction of the oxide catalyst obtained from the calcining tube outlet when hr passed was evaluated, the propane conversion was 86.8% and the acrylonitrile yield was 52.6%.

(Example 10)
Composition formula was prepared a catalyst represented by _{Mo 1 V 0.25 Nb 0.095 Sb 0.24} Ce 0.008 O n / 42 wt% -SiO ₂ as follows.
(Preparation of raw material mixture)
Water 48.8kg ammonium heptamolybdate _{[(NH 4) 6Mo 7 O 24} · 4H
₂ O] was 9.57Kg, ammonium metavanadate _[NH 4 VO _3] 1.57 kg,
1.89 kg of diantimony trioxide [Sb ₂ O ₃ ], cerium nitrate [Ce (NO ₃ ) ₃
6H ₂ O] was added, and the mixture was heated at 90 ° C. for 2.5 hours with stirring to obtain an aqueous mixed solution A-1.
1.86 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added to 8.63 kg of the niobium raw material liquid. The liquid temperature was maintained at about 20 ° C., and the mixture was stirred and mixed to obtain an aqueous liquid B-1.
After cooling the obtained aqueous mixed liquid A-1 to 70 ° C., 16.6 kg of silica sol containing 30.4% by mass as SiO ₂ was added. Next, 2.20 kg of hydrogen peroxide containing 30% by mass as H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, aqueous liquid B-1 was added. Furthermore, a liquid in which 3.36 kg of fumed silica was dispersed in 47.0 kg of water was added to obtain a raw material preparation liquid.
In order to perform the “preparation of dry catalyst precursor” step and the “calcination” step, which will be described later, in a continuous manner, this step was repeated 103 times to prepare a total of about 2000 kg of the raw material mixture.
(Preparation of dry catalyst precursor)
Spray drying was performed in the same manner as in Example 1 to obtain a dry catalyst precursor.
(Baking)
Firing was performed in the same manner as in Example 1 to obtain an oxide catalyst. During the main calcination, an oxide catalyst could be obtained at a stable rate.
(Evaluation of catalyst performance)
When the performance in the ammoxidation reaction of the oxide catalyst obtained from the outlet of the calcining tube was evaluated after 40 hours had elapsed after resuming the calcining by the same method as in Example 1, the propane conversion was 88.9.
%, And the acrylonitrile yield was 52.9%.

(Comparative Example 1)
Firing was performed in the same manner as in Example 2 except that the subsequent continuous firing was performed without lowering the temperature of the catalyst precursor and / or oxide catalyst. After the operation for 5 days, the performance in the ammoxidation reaction of the oxide catalyst obtained from the outlet of the calcining tube was evaluated.
. The acrylonitrile yield was 39.5% and 39.5%.

(Comparative Example 2)
The pre-stage calcined powder was heated to 475 ° C. at 2 ° C./min, calcined at 475 ° C. for 2 hours, and 12 ° C.
An oxide catalyst was obtained in the same manner as in Example 2 except that the heating furnace temperature was adjusted so as to have a temperature profile that lowered the temperature at / min and the main calcination was performed. When the catalyst performance was evaluated in the same manner as in Example 1, the propane conversion was 52.0% and the acrylonitrile yield was 24.8%.

Tables 1 and 2 show the conditions in the firing steps of the examples and comparative examples, the composition of the obtained oxide catalyst, the propane (PN) conversion, the acrylonitrile (AN) yield, and the acrylic acid (AA) yield. Shown in

From the above results, the production method of the present embodiment (Examples 1 to 10) is generated in the firing tube by performing a low-temperature treatment that lowers the temperature of the catalyst precursor and / or the oxide catalyst during the firing step. As a result, it was possible to manufacture a catalyst having excellent performance in a large amount and efficiently.
Further, since the oxide catalyst obtained by the production method of the present embodiment has excellent catalytic performance, it can be used by using it for the gas phase catalytic ammoxidation reaction and gas phase catalytic oxidation reaction of propane. Acrylonitrile and acrylic acid could be stably produced with high yield.
On the other hand, in the manufacturing method of Comparative Example 1, since the main calcination is continuously performed without lowering the temperature of the catalyst precursor and / or the oxide catalyst during the calcination step, it is fixed to the inner wall of the calcination tube. Increased,
The performance of the resulting oxide catalyst was inferior.
Moreover, since the manufacturing method of the comparative example 2 had low calcination temperature, the performance of the obtained oxide catalyst was inferior.

According to the present invention, it is possible to remarkably reduce the sticking generated in the firing tube in the step of firing the catalyst precursor, and as a result, it is possible to efficiently produce a catalyst having excellent performance in a large amount. It becomes.
Since the oxide catalyst obtained by the production method of the present invention has excellent catalytic performance, the corresponding unsaturated carboxylic acid or unsaturated nitrile (for example, (meth) acrylic acid, ( It has industrial applicability as an oxide catalyst when producing (meth) acrylonitrile).

Claims (13)

A step of supplying a catalyst precursor calcining device, a method of manufacturing an oxide catalyst containing a main firing step of firing at least the melting point of the sintering temperature of the metal oxide of the catalyst constituting elements,
Wherein during the baking step, including a low-temperature process step to a temperature lower than the temporarily the firing temperature the temperature of the catalyst precursor and / or the oxide catalyst, producing the oxide catalyst.   The method for producing an oxide catalyst according to claim 1, wherein in the low temperature treatment step, the temperature of the catalyst precursor and / or the oxide catalyst is lowered by 10 ° C or more.   The method for producing an oxide catalyst according to claim 1, wherein in the low temperature treatment step, the temperature of the catalyst precursor and / or the oxide catalyst is lowered by 50 ° C or more.   The method for producing an oxide catalyst according to claim 1, wherein, in the low temperature treatment step, the temperature of the catalyst precursor and / or the oxide catalyst is lowered by 100 ° C or more. The method for producing an oxide catalyst according to claim 1, further comprising a step of applying an impact to the calciner in the main calcining step. The method for producing an oxide catalyst according to claim 1, further comprising a step of applying an impact to the calciner in the low temperature treatment step. The method for producing an oxide catalyst according to claim 1, further comprising a pre-stage calcination step performed before the main calcination step .   The manufacturing method of the oxide catalyst of Claim 7 which performs the said main calcination in the temperature range of 550-800 degreeC.   The method for producing an oxide catalyst according to claim 7 or 8, wherein the pre-stage calcination is performed in a temperature range of 250 to 400 ° C, and the main calcination is performed in a temperature range of 580 to 750 ° C. The method for producing an oxide catalyst according to any one of claims 1 to 9 , wherein a catalyst precursor is continuously supplied to the calciner and calcined by continuous calcining. The method for producing an oxide catalyst according to any one of claims 1 to 10 , wherein the oxide catalyst contains Mo and Sb and / or Te. When the oxide catalyst contains Mo, V, and Nb, and the atomic ratios of V and Nb per Mo atom are a and b, respectively, 0.1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1 The manufacturing method of the oxide catalyst of any one of Claims 1-11 satisfy | filled. Wherein the oxide catalyst is carried on silica, with respect to the total mass of the mass of the silica is the oxide catalyst and the silica, 10 to 80 wt% in terms of SiO _2, any of Claim 1 to 1 2 A method for producing the oxide catalyst according to claim 1.