JP2013169482A - Catalyst for producing acrylonitrile, method of producing the same, and method of producing acrylonitrile using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a catalyst containing an alkali metal, which is a catalyst capable of producing acrylonitrile at a high yield, and to produce acrylonitrile at a high yield using the catalyst.SOLUTION: A method of producing a catalyst for producing acrylonitrile containing molybdenum, bismuth, iron, an alkali metal, and silica includes: a slurry preparation step of preparing a slurry mixture containing at least molybdenum, bismuth, iron and silica; a drying step of drying the slurry mixture to obtain a dry object; a first calcination step of calcining the dry object and producing a catalyst precursor; an impregnation step of impregnating the catalyst precursor with a liquid containing the alkali metal and producing an alkali impregnated catalyst precursor; and a second calcination step of calcining the alkali impregnated catalyst precursor. By the catalyst obtained by the method, the acrylonitrile can be produced at a high yield.

Description

  TECHNICAL FIELD The present invention relates to a catalyst for producing acrylonitrile suitably used for producing acrylonitrile by vapor phase catalytic ammoxidation of propylene, a method for producing the catalyst for producing acrylonitrile, and a method for producing acrylonitrile using the catalyst for producing acrylonitrile. .

Acrylonitrile is obtained by a method of vapor phase catalytic ammoxidation of propylene with molecular oxygen and ammonia, and is industrially produced by a “fluidized bed ammoxidation process” using a fluidized bed reactor.
Thus, many proposals are made about the catalyst used when manufacturing acrylonitrile, For example, the patent documents 1-6 etc. have disclosed the catalyst which has molybdenum and bismuth as a main component. These mainly define the constituent elements of the catalyst for obtaining a catalyst with a high acrylonitrile yield and the composition ratio thereof, but the catalyst obtained by these known methods is an industrial catalyst in terms of catalyst performance and the like. Was insufficient.

On the other hand, studies have been made to improve the selectivity and yield of acrylonitrile by including an alkali metal in the catalyst.
For example, Patent Document 7 discloses a catalyst in which the selectivity of acrylonitrile is greatly improved by bringing the amount of one or more alkali metals selected from sodium, potassium, rubidium and cesium within an appropriate range. Yes. Patent Document 8 discloses a method for suppressing a decrease in acrylonitrile yield over time by supplementing a catalyst having a high alkali metal content because the alkali metal in the catalyst is lost during the reaction. . Further, Patent Document 9 discloses that when sodium is used as the alkali metal, it is possible to enhance the attrition resistance, and it is possible to enhance both the catalytic activity and the acrylonitrile selectivity by using it together with a specific element (Ge). Has been. In Patent Document 10, in addition to molybdenum, bismuth, iron, and tungsten, when a catalyst that essentially uses rubidium as an alkali metal is used, the selectivity of by-products (mainly carbon dioxide) decreases with time. As a result, it has been disclosed that acrylonitrile selectivity is improved with time and stable operation can be performed while maintaining a high acrylonitrile yield over a long period of time.

Japanese Patent Publication No. 61-013701 JP 59-204163 A Japanese Patent Laid-Open No. 01-228950 Japanese Patent Laid-Open No. 10-043595 JP-A-10-156185 US Pat. No. 5,688,739 Japanese Patent Publication No.58-002232 JP-A-2005-162707 Special table 2003-507180 gazette JP 2009-207974 A

  However, as described above, although catalysts containing alkali metals have been studied, these conventional catalysts are not necessarily sufficient as industrial catalysts in terms of acrylonitrile yield, and further improvement in catalyst performance is desired. ing.

  This invention is made | formed in view of the said situation, Comprising: It aims at provision of the manufacturing method of the catalyst which is a catalyst containing an alkali metal and can manufacture acrylonitrile with a high yield. Another object of the present invention is to produce acrylonitrile in a high yield by using the catalyst.

The method for producing an acrylonitrile production catalyst of the present invention is a method for producing an acrylonitrile production catalyst containing molybdenum, bismuth, iron, an alkali metal, and silica, and includes at least molybdenum, bismuth, and iron. A slurry preparing step for preparing a mixed slurry containing silica, a drying step for drying the mixed slurry to obtain a dried product, a first firing step for producing a catalyst precursor by firing the dried product, It comprises an impregnation step of impregnating the catalyst precursor with a liquid containing an alkali metal to produce an alkali-impregnated catalyst precursor, and a second calcining step of calcining the alkali-impregnated catalyst precursor.
The catalyst for producing acrylonitrile preferably has a composition represented by the following general formula.
_{Mo a Bi b Fe c X d} Z e O f (SiO 2) g
(Wherein Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, respectively, X is at least one alkali metal element selected from the group consisting of sodium, potassium, rubidium and cesium, Z is , Magnesium, calcium, strontium, barium, titanium, zirconium, boron, aluminum, gallium, indium, tantalum, phosphorus, arsenic, antimony, germanium, tin, lead, vanadium, niobium, chromium, tungsten, manganese, cobalt, nickel, copper , At least one element selected from the group consisting of silver, zinc, sulfur, selenium, tellurium, lanthanum, cerium, praseodymium, neodymium and samarium, SiO ₂ represents silica, a, b, c, d, e, f and g are each element (in the case of silica Silicon), and when a = 10, 0.1 ≦ b ≦ 5.0, 0.1 ≦ c ≦ 10.0, 0.01 ≦ d ≦ 3.0, 0 ≦ e ≦ 12, 10 ≦ g ≦ 200, and f is an atomic ratio of oxygen necessary to satisfy the valence of each of the above components excluding silica.)
The catalyst for producing acrylonitrile of the present invention is produced by the production method of the present invention.
The method for producing acrylonitrile of the present invention is characterized in that an ammoxidation reaction of propylene is carried out using the catalyst for acrylonitrile production of the present invention.

  According to the method for producing a catalyst for producing acrylonitrile of the present invention, a catalyst containing an alkali metal and capable of producing acrylonitrile in a high yield can be produced. And by using this catalyst, acrylonitrile can be manufactured with a high yield.

Hereinafter, the present invention will be described in detail.
The method for producing a catalyst for producing acrylonitrile of the present invention is a method for producing a catalyst for producing acrylonitrile containing at least molybdenum, bismuth, iron, an alkali metal, and silica, and includes molybdenum, bismuth, and iron. And a slurry preparation step of preparing a mixed slurry containing at least silica.

As a raw material of molybdenum, molybdenum element or a raw material compound containing molybdenum element may be used as it is, but it should be used in a solution in which these are dissolved in a solvent or in a slurry in which these are suspended in a solvent. Is preferred. Although it does not specifically limit as a solvent, Water is preferable.
Examples of the raw material compound containing molybdenum element include molybdenum oxides such as molybdenum trioxide, and molybdates of ammonium molybdates (for example, ammonium paramolybdate and ammonium dimolybdate). Among these, from the viewpoint of solubility, it is preferable to use ammonium molybdates such as ammonium paramolybdate and ammonium dimolybdate.
The raw material of molybdenum can use 1 type (s) or 2 or more types.

As a raw material for bismuth, a bismuth element or a raw material compound containing a bismuth element may be used as it is, but it should be used in a solution in which these are dissolved in a solvent or in a slurry in which these are suspended in a solvent. Is preferred. Although it does not specifically limit as a solvent, Nitric acid or water is preferable.
The raw material compound containing a bismuth element is not particularly limited, and bismuth oxide, bismuth nitrate, bismuth carbonate, bismuth hydroxide, and the like can be used.
The raw material of bismuth can use 1 type (s) or 2 or more types.

As a raw material of iron, iron element or a raw material compound containing iron element may be used as it is, but it should be used in a solution in which these are dissolved in a solvent or in a slurry in which these are suspended in a solvent. Is preferred. Although it does not specifically limit as a solvent, Nitric acid or water is preferable.
The raw material compound containing iron element is not particularly limited, and iron oxide, iron hydroxide, iron nitrate, iron chloride, iron sulfate and the like can be used. Further, metallic iron may be dissolved in nitric acid or the like.
The raw material of iron can use 1 type (s) or 2 or more types.

  As a raw material of silica, colloidal silica (silica sol) is preferable. Colloidal silica may be appropriately selected from commercially available ones. 2-100 nm is preferable and, as for the average particle diameter of the colloidal particle in colloidal silica, 5-80 nm is especially preferable. Moreover, colloidal silica may have a single peak or a plurality of peaks in the particle size distribution of colloidal particles.

The mixed slurry prepared in the slurry preparation step may further contain another element (Z) as an optional component as long as it contains at least molybdenum, bismuth, iron, and silica.
Examples of other elements (Z) include magnesium, calcium, strontium, barium, titanium, zirconium, boron, aluminum, gallium, indium, tantalum, phosphorus, arsenic, antimony, germanium, tin, lead, vanadium, and niobium. , Chromium, tungsten, manganese, cobalt, nickel, copper, silver, zinc, sulfur, selenium, tellurium, lanthanum, cerium, praseodymium, neodymium and samarium, and one or more of these can be included.

As raw materials for other elements, Z elements or raw material compounds containing Z elements may be used as they are, but they are used in the form of a solution in which these are dissolved in a solvent, or a slurry in which these are suspended in a solvent. It is preferable to do. Although it does not specifically limit as a solvent to be used, Nitric acid or water is preferable.
The raw material compound containing the Z element is not particularly limited, and examples thereof include oxides, hydroxides, nitrates, carbonates, sulfates, and ammonium salts.
The raw material for the element Z can be used alone or in combination of two or more.

In the slurry preparation step, these raw materials are mixed to prepare a mixed slurry. Here, an alkali metal is not added to the mixed slurry, and the mixed slurry is substantially free of alkali metal. Is preferred. Even when an alkali metal is added to the mixed slurry, the amount added is preferably as small as possible. When the total amount of alkali metal used in the production of the catalyst for acrylonitrile production is 100% by mass, the amount added to the mixed slurry Is preferably 60% by mass or less, and more preferably 30% by mass or less.
That is, it is preferable that 40% by mass or more of the alkali metal in the total amount (100% by mass) is added to the impregnating liquid in the impregnation step described later and supported on the catalyst, more preferably 70% by mass or more. Is preferably added to the impregnation liquid in the impregnation step and supported on the catalyst. Thereby, the obtained catalyst for acrylonitrile production can produce acrylonitrile in a high yield.
The mixed slurry prepared in the slurry preparation step preferably contains the entire amount of each raw material other than the alkali metal.

  The mixing order and mixing method of the raw materials in the slurry preparation step are not limited, but as described above, it is preferable to mix the raw materials after dissolving or dispersing them in a solvent in advance. However, when a plurality of nitrates are used as raw materials, for example, these nitrates may be collectively dissolved in nitric acid (solvent) to form one solution, and a solution or slurry each containing one raw material is not necessarily required. It may not be prepared. Alternatively, a target mixed slurry may be prepared by preparing a plurality of solutions for each type of solvent, such as a solution using nitric acid as a solvent and a solution using water as a solvent, and mixing them. Note that the obtained slurry may be subjected to heat treatment such as aging and concentration as necessary.

  The liquid temperature in the slurry preparation step and the concentration of the prepared mixed slurry are not particularly limited and can be adjusted as appropriate.

In the drying step, the mixed slurry prepared in the above-described slurry preparation step is dried to obtain a dried product (solid matter).
Although there is no restriction | limiting in particular as a drying method, When using the catalyst for acrylonitrile manufacture obtained in a fluidized bed, it is preferable to obtain a spherical particle-like dried material using a spray dryer.
As the spray dryer, various types of dryers such as a pressure nozzle type, a two-fluid nozzle type, and a rotary disk type can be used. The temperature of the hot air circulated in the drying chamber of the spray dryer is preferably a lower limit of the temperature in the vicinity of the inlet to the drying chamber, preferably 130 ° C, more preferably 140 ° C, and an upper limit, preferably 350 ° C. More preferably, it is 300 degreeC. Further, the lower limit of the temperature in the vicinity of the drying chamber outlet is preferably 100 ° C., more preferably 110 ° C., and the upper limit is preferably 200 ° C., more preferably 180 ° C. When each temperature in the drying chamber is within the above range, the activity and acrylonitrile yield of the finally obtained acrylonitrile production catalyst are more excellent, and the bulk density, particle strength, and the like are also more suitable.

In the first firing step, the dried product obtained in the above-described drying step is fired to produce a catalyst precursor.
The lower limit of the firing temperature in the first firing step is preferably 200 ° C, more preferably 300 ° C, and even more preferably 450 ° C. On the other hand, the upper limit is preferably 750 ° C, more preferably 700 ° C, and even more preferably 680 ° C or less. By performing the first calcination step in such a temperature range, a catalyst having a higher acrylonitrile yield is easily obtained.
The lower limit of the firing time is preferably 0.1 hours, more preferably 0.5 hours. When the calcination time is equal to or more than the lower limit, the finally obtained acrylonitrile production catalyst has sufficient catalytic performance to exhibit a high acrylonitrile yield. There is no particular upper limit on the calcination time, but even if the calcination time is increased more than necessary, the catalyst performance does not become a certain level, so it is usually within 20 hours.
Further, in the first firing step, multi-stage firing such as firing at a certain temperature for a certain time and then firing at a higher temperature for a certain time may be performed.

  In the first firing step, a rotary kiln, a fluidized firing furnace, or the like can be used in addition to a general-purpose firing furnace. The atmosphere during firing may be an oxidizing gas atmosphere containing oxygen, or an inert gas atmosphere such as nitrogen, and air is preferably used from the viewpoint of simplicity.

In the impregnation step, the catalyst precursor obtained as described above is impregnated with a liquid containing an alkali metal to produce an alkali-impregnated catalyst precursor.
As the liquid (impregnating liquid) containing an alkali metal, a solution in which an alkali metal element or a raw material compound containing an alkali metal element is dissolved in a solvent, or a slurry in which these are suspended in a solvent can be used. Although it does not specifically limit as a solvent to be used, It is preferable to use nitric acid or water.
The raw material compound containing an alkali metal element is not particularly limited, and oxides, hydroxides, nitrates, carbonates, sulfates, and the like can be used.
The impregnation solution can contain one or more alkali metals.

The impregnation operation for impregnating the liquid containing the alkali metal is not particularly limited, but the impregnation is preferably performed by the following method.
First, the pore volume of the catalyst precursor obtained by the first calcination step is measured by a water titration method. Next, an impregnating liquid containing an alkali metal is prepared, and the liquid volume (volume) is adjusted to 95% of the pore volume of the catalyst precursor. Then, the impregnating liquid is dropped into the catalyst precursor little by little while stirring or vibrating the catalyst precursor and mixed well.
Thereby, an alkali-impregnated catalyst precursor impregnated with an alkali metal is obtained.

In the second firing step, the alkali-impregnated catalyst precursor obtained as described above is fired. Thereby, the catalyst for acrylonitrile production of the present invention is obtained.
The lower limit of the firing temperature in the second firing step is preferably 200 ° C, more preferably 300 ° C, and even more preferably 450 ° C. On the other hand, the upper limit is preferably 750 ° C, more preferably 700 ° C, and even more preferably 680 ° C. By performing the second calcination step in such a temperature range, a catalyst having a higher acrylonitrile yield can be easily obtained.
The lower limit of the firing time is preferably 0.1 hours, more preferably 0.5 hours. When the calcination time is equal to or more than the lower limit, the finally obtained acrylonitrile production catalyst has sufficient catalytic performance to exhibit a high acrylonitrile yield. There is no particular upper limit on the calcination time, but even if the calcination time is increased more than necessary, the catalyst performance does not become a certain level, so it is usually within 20 hours.

  In addition, after the impregnation step and before carrying out the second calcination step, if a temporary calcination step of calcination of the alkali-impregnated catalyst precursor in the range of 200 to 490 ° C. is performed, a catalyst having excellent fluidity is obtained. It is easy and preferable.

  In addition to a general-purpose firing furnace, a rotary kiln, a fluidized firing furnace, or the like can be used for the temporary firing step and the second firing step. The atmosphere during firing may be an oxidizing gas atmosphere containing oxygen, or an inert gas atmosphere such as nitrogen, and air is preferably used from the viewpoint of simplicity.

  As a preferable form of the preliminary calcination step and the second calcination step, after performing the preliminary calcination step of standing and firing the alkali-impregnated catalyst precursor in the range of 200 to 490 ° C., fluidized calcination in the range of 450 to 680 ° C. An example in which the second baking step is performed is given as an example.

  The average particle diameter of the acrylonitrile production catalyst of the present invention thus produced is preferably in the range of 5 to 200 μm, more preferably in the range of 10 to 150 μm.

  The catalyst for producing acrylonitrile of the present invention preferably has a composition represented by the following general formula. When producing the acrylonitrile production catalyst having such a composition, when the production method of the acrylonitrile production catalyst of the present invention is applied, the resulting catalyst exhibits a higher acrylonitrile yield, and the effects of the present invention are fully exhibited. To do.

_{Mo a Bi b Fe c X d} Z e O f (SiO 2) g
In the formula, Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, respectively, X is at least one alkali metal element selected from the group consisting of sodium, potassium, rubidium and cesium, Z is Magnesium, calcium, strontium, barium, titanium, zirconium, boron, aluminum, gallium, indium, tantalum, phosphorus, arsenic, antimony, germanium, tin, lead, vanadium, niobium, chromium, tungsten, manganese, cobalt, nickel, copper, At least one element selected from the group consisting of silver, zinc, sulfur, selenium, tellurium, lanthanum, cerium, praseodymium, neodymium and samarium, SiO ₂ represents silica, and a, b, c, d, e, f And g are each element (in the case of silica, A), and when a = 10, 0.1 ≦ b ≦ 5.0, 0.1 ≦ c ≦ 10.0, 0.01 ≦ d ≦ 3.0, 0 ≦ e ≦ 12 10 ≦ g ≦ 200, and f is an atomic ratio of oxygen necessary for satisfying the valence of each component excluding silica.

The catalyst for producing acrylonitrile of the present invention is suitably used for producing acrylonitrile by vapor-phase catalytic ammoxidation of propylene with molecular oxygen and ammonia.
Vapor-phase catalytic ammoxidation can be carried out by introducing a raw material gas containing propylene, molecular oxygen and ammonia into a reactor in the presence of a catalyst for producing acrylonitrile.
As an oxygen source (molecular oxygen source) for performing gas phase catalytic ammoxidation, air is industrially advantageous, but if necessary, pure oxygen is added to air and a gas enriched with oxygen is used. May be. Further, as the reactor, a fluidized bed reactor is preferably used.

  The concentration of propylene in the raw material gas can be varied within a wide range, but 1 to 20% by volume is appropriate, and 3 to 15% by volume is particularly preferable. The molar ratio of propylene to oxygen (propylene: oxygen) in the raw material gas is preferably 1: 1.5 to 1: 3. The molar ratio of propylene to ammonia in the reaction gas (propylene: ammonia) is preferably 1: 1 to 1: 1.5. The source gas may be diluted with an inert gas, water vapor, or the like.

  The reaction pressure when performing vapor phase ammoxidation is preferably normal pressure to 500 kPa, and the reaction temperature is preferably in the range of 400 to 500 ° C. The contact time is preferably from 0.1 to 20 seconds.

  As described above, as a method for producing a catalyst for producing acrylonitrile containing molybdenum, bismuth, iron, alkali metal, and silica, a mixed slurry containing at least molybdenum, bismuth, iron, and silica. A slurry preparation step for preparing a slurry, a drying step for drying the mixed slurry to obtain a dried product, a first firing step for firing the dried product to produce a catalyst precursor, and a liquid containing an alkali metal in the catalyst precursor A catalyst for producing acrylonitrile in a high yield by adopting a method comprising an impregnation step for producing an alkali-impregnated catalyst precursor and a second firing step for firing the alkali-impregnated catalyst precursor. it can. And by using this catalyst, acrylonitrile can be manufactured with a high yield.

  The mechanism by which the catalyst for producing acrylonitrile produced by the above-described production method exhibits a high acrylonitrile yield is not necessarily clear at this stage, but by adding (supporting) the alkali metal by impregnation, This is presumably because the active sites that localize on the catalyst surface and produce acrylonitrile in a high yield appear on the catalyst surface.

As described above, according to the method of applying an alkali metal by impregnation, the alkali metal is localized on the catalyst surface and is effectively used for the catalytic reaction. Therefore, as a result, it is possible to produce a catalyst for producing acrylonitrile that exhibits a high acrylonitrile yield with a small amount of alkali metal used.
For example, rubidium, which is an alkali metal, is a rare metal whose annual global production of the compound is as small as several tons. For this reason, the present catalyst production method in which a high-performance catalyst can be obtained with a small amount of alkali metal used is also very advantageous from the viewpoint of supplying alkali metal raw materials.

  The effect of the present invention will be shown by examples. However, “parts” in the following Examples and Comparative Examples means parts by mass.

The catalyst activity test was performed as follows.
<Catalyst activity test>
Production of acrylonitrile by ammoxidation of propylene was carried out using a fluidized bed reactor having an inner diameter of 25 mm and a height of 40 cm.
At that time, as a raw material gas, a mixed gas of propylene / ammonia / air / water vapor = 1 / 1.2 / 9.5 / 0.5 (molar ratio) was supplied at 6.5 L (converted to NTP) per hour. The reaction temperature was 440 ° C. and the reaction pressure was 200 kPa. The contact time is as shown in Table 1. The reaction test analysis was performed by gas chromatography.

The contact time and the yield of acrylonitrile are defined as follows.
Contact time (seconds) = catalyst density based on bulk density (L) / feed gas flow rate converted to reaction conditions (L / second)
Acrylonitrile yield (%) = B / A × 100
Here, A represents the number of moles of propylene supplied, and B represents the number of moles of produced acrylonitrile.

[Example 1]
(Slurry preparation process)
A liquid A was prepared by adding 400 parts of ammonium paramolybdate in 800 parts of water to 2477.4 parts of 20% by mass silica sol (average particle size 22 nm) with stirring.
Separately, to 400 parts of 17% nitric acid heated to 40 ° C., 114.3 parts of bismuth nitrate, 137.3 parts of iron (III) nitrate, 349.2 parts of nickel nitrate, 57. 3 parts, 59.0 parts of cerium nitrate, 36.3 parts of chromium nitrate, and 2.68 parts of indium nitrate were sequentially added to prepare solution B.
After liquid B was added to liquid A heated to 40 ° C. with stirring, 73.5 parts of 50% aqueous solution of ammonium metatungstate (50% by mass as WO ₃ ) heated to 40 ° C., boric acid 3.50 Parts were sequentially added to obtain a mixed slurry.

(Drying process, first baking process)
The obtained slurry was dried with a rotating disk spray dryer while controlling the temperature at the hot air inlet at 280 ° C. and the temperature at the outlet at 150 ° C.
The obtained dried product was pre-fired at 300 ° C. for 2 hours under air flow, and then at 450 ° C. for 2 hours to perform a first firing step, thereby obtaining a catalyst precursor.
It was 0.24 ml / g as a result of measuring the pore volume of this catalyst precursor by the water titration method.

(Impregnation step, preliminary firing step, second firing step)
After dissolving 4.68 parts of rubidium nitrate in 20 parts of pure water, pure water was further added to prepare an impregnation liquid adjusted to a liquid volume corresponding to 95% of the pore volume of 100 parts of the catalyst precursor. The impregnating solution was added dropwise to 100 parts of the catalyst precursor and mixed well.
The obtained alkali-impregnated catalyst precursor was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours (preliminary calcining step) and then fluidized calcining at 600 ° C. for 2 hours (second calcining step). To obtain a catalyst for producing acrylonitrile.

The composition of the obtained catalyst is calculated as follows from the charged amount of raw material.
_{Mo 10 Bi 0.52 Fe 1.5 W 0.50} Ni 5.3 Zn 0.85 Ce 0.60 Cr 0.40 B 0.25 In 0.10 Rb 0.14 O f (SiO 2) 36. ₄
Here, f is an atomic ratio of oxygen necessary to satisfy the valence of each other element (excluding silicon).

  When the obtained catalyst was subjected to an activity test under the conditions described above, the yield of acrylonitrile was 83.5%, and the selectivity was 85.2%. The results are shown in Table 1.

[Example 2]
Instead of the impregnating liquid containing 4.68 parts of rubidium nitrate, an impregnating liquid containing 5.35 parts of rubidium nitrate was prepared, and the catalyst was treated in the same manner as in Example 1 except that this impregnating liquid was impregnated into the catalyst precursor. Manufacture was performed and reaction evaluation was performed. The results are shown in Table 1.

Example 3
Instead of the impregnating liquid containing 4.68 parts of rubidium nitrate, an impregnating liquid containing 4.01 parts of rubidium nitrate was prepared, and the catalyst was treated in the same manner as in Example 1 except that this impregnating liquid was impregnated into the catalyst precursor. Manufacture was performed and reaction evaluation was performed. The results are shown in Table 1.

[Comparative Example 1]
After the slurry preparation step and the drying step, the impregnation step was not performed, and the firing step was performed to produce catalysts having the compositions shown in Table 1.
Specifically, 4.68 parts of rubidium nitrate was added to the B liquid in the slurry preparation step. This addition was performed after the addition of indium nitrate. Except for this point, a mixed slurry was prepared in the same manner as in Example 1. And the drying process was performed like Example 1, and the obtained catalyst precursor was fluidly baked at 600 degreeC under air circulation for 2 hours, and the catalyst was obtained. Thereafter, the reaction was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
After the slurry preparation step and the drying step, the impregnation step was not performed, and the firing step was performed to produce catalysts having the compositions shown in Table 1.
Specifically, 5.35 parts of rubidium nitrate was added to the B liquid in the slurry preparation step. This addition was performed after the addition of indium nitrate. Except for this point, a mixed slurry was prepared in the same manner as in Example 1. And the drying process was performed like Example 1, and the obtained catalyst precursor was fluidly baked at 600 degreeC under air circulation for 2 hours, and the catalyst was obtained. Thereafter, the reaction was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
After the slurry preparation step and the drying step, the impregnation step was not performed, and the firing step was performed to produce catalysts having the compositions shown in Table 1.
Specifically, 6.02 parts of rubidium nitrate was added to the B liquid in the slurry preparation step. This addition was performed after the addition of indium nitrate. Except for this point, a mixed slurry was prepared in the same manner as in Example 1. And the drying process was performed like Example 1, and the obtained catalyst precursor was fluidly baked at 600 degreeC under air circulation for 2 hours, and the catalyst was obtained. Thereafter, the reaction was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4
(Slurry preparation process)
A solution A was prepared by adding 400 parts of ammonium paramolybdate in 800 parts of water to 2382.1 parts of 20% by mass silica sol (average particle size 22 nm) with stirring.
Separately, to 400 parts of 17% by mass nitric acid heated to 40 ° C., 131.9 parts of bismuth nitrate, 109.8 parts of iron (III) nitrate, 362.4 parts of nickel nitrate, 63.3% of magnesium nitrate are stirred. 9 parts, 16.3 parts of manganese nitrate, 29.5 parts of cerium nitrate, 24.5 parts of lanthanum nitrate, and 2.6 parts of 85% phosphoric acid were sequentially added to prepare a liquid B.
Liquid B was added to liquid A heated to 40 ° C. with stirring to obtain a mixed slurry.

(Drying process, first baking process)
In the same manner as in Example 1, a drying process and a first baking process were performed.
It was 0.24 ml / g as a result of measuring the pore volume of this catalyst precursor by the water titration method.

(Impregnation step, preliminary firing step, second firing step)
After dissolving 4.58 parts of potassium nitrate in 20 parts of pure water, pure water was further added to prepare an impregnation liquid adjusted to a liquid volume corresponding to 95% of the pore volume of 100 parts of the catalyst precursor. The impregnating solution was added dropwise to 100 parts of the catalyst precursor and mixed well.
The obtained alkali-impregnated catalyst precursor was subjected to a preliminary calcination step and a second calcination step in the same manner as in Example 1 to obtain an acrylonitrile production catalyst. And reaction evaluation was performed like Example 1. FIG. The results are shown in Table 1.

The composition of the obtained catalyst is calculated as follows from the charged amount of raw material.
_{Mo 10 Bi 0.60 Fe 1.2 Ni 5.5} Mg 1.1 Mn 0.25 Ce 0.30 La 0.25 P 0.10 K 0.20 O f (SiO 2) 35.0
Here, f is an atomic ratio of oxygen necessary to satisfy the valence of each other element (excluding silicon).

Example 5
In the preparation of solution B, the addition of 1.14 parts of potassium nitrate after the addition of 2.6 parts of 85% phosphoric acid, instead of the impregnating solution containing 4.58 parts of potassium nitrate, the impregnating solution containing 3.44 parts of potassium nitrate was used. A catalyst was produced and the reaction was evaluated in the same manner as in Example 4 except that the catalyst precursor thus prepared was impregnated with the obtained catalyst precursor. The results are shown in Table 1.

Example 6
The point that 2.29 parts of potassium nitrate was added after the addition of 2.6 parts of 85% phosphoric acid when preparing the liquid B, and instead of the impregnating liquid containing 4.58 parts of potassium nitrate, an impregnating liquid containing 2.29 parts of potassium nitrate was used. A catalyst was produced and the reaction was evaluated in the same manner as in Example 4 except that the catalyst precursor thus prepared was impregnated with the obtained catalyst precursor. The results are shown in Table 1.

[Comparative Example 4]
After the slurry preparation step and the drying step, the impregnation step was not performed, and the firing step was performed to produce catalysts having the compositions shown in Table 1.
Specifically, 4.58 parts of potassium nitrate was added to the B liquid in the slurry preparation step. This addition was performed after 85% phosphoric acid was added. A mixed slurry was prepared in the same manner as in Example 4 except for this point. And the drying process was performed like Example 4, and the obtained catalyst precursor was fluid-fired for 2 hours at 590 degreeC under air circulation, and the catalyst was obtained. Thereafter, the reaction was evaluated in the same manner as in Example 4. The results are shown in Table 1.

[Comparative Example 5]
After the slurry preparation step and the drying step, the impregnation step was not performed, and the firing step was performed to produce catalysts having the compositions shown in Table 1.
Specifically, 5.73 parts of potassium nitrate was added to the B liquid in the slurry preparation step. This addition was performed after 85% phosphoric acid was added. A mixed slurry was prepared in the same manner as in Example 4 except for this point. And the drying process was performed like Example 4, and the obtained catalyst precursor was fluid-fired for 2 hours at 590 degreeC under air circulation, and the catalyst was obtained. Thereafter, the reaction was evaluated in the same manner as in Example 4. The results are shown in Table 1.

[Comparative Example 6]
After the slurry preparation step and the drying step, the impregnation step was not performed, and the firing step was performed to produce catalysts having the compositions shown in Table 1.
Specifically, 6.87 parts of potassium nitrate was added to the B liquid in the slurry preparation step. This addition was performed after 85% phosphoric acid was added. A mixed slurry was prepared in the same manner as in Example 4 except for this point. And the drying process was performed like Example 4, and the obtained catalyst precursor was fluid-fired for 2 hours at 590 degreeC under air circulation, and the catalyst was obtained. Thereafter, the reaction was evaluated in the same manner as in Example 4. The results are shown in Table 1.

As is clear from Table 1, each composite oxide catalyst obtained in each example was able to produce acrylonitrile in a higher yield than the composite oxide catalyst obtained in each comparative example.
For example, when Example 1 is compared with Comparative Example 1, they have the same amount of alkali metal used for catalyst production, but the acrylonitrile yield is higher in Example 1. From this, the amount of alkali metal necessary to produce a certain amount of acrylonitrile was lower in Example 1 than in Comparative Example 1, and the amount of alkali metal was reduced.
In addition, when the catalysts obtained in Examples 4 to 6 were compared, they had the same catalyst composition, but the higher the proportion of alkali metal supported in the impregnation step, the higher the yield of acrylonitrile. Was high.

  According to the catalyst for producing acrylonitrile of the present invention, acrylonitrile can be produced in high yield. Moreover, since it has the process of providing an alkali metal by impregnation, the manufacture of the catalyst for acrylonitrile manufacture which exhibits a high acrylonitrile yield as a result with the usage-amount of a small alkali metal is attained. Such a method has a great industrial value from the viewpoint of supplying raw materials when a rare metal such as rubidium is used as an alkali metal.

Claims (4)

A method for producing a catalyst for acrylonitrile production comprising molybdenum, bismuth, iron, alkali metal, and silica,
A slurry preparation step of preparing a mixed slurry containing at least molybdenum, bismuth, iron, and silica;
A drying step of drying the mixed slurry to obtain a dried product;
A first firing step of firing the dried product to produce a catalyst precursor;
Impregnating the catalyst precursor with a liquid containing an alkali metal to produce an alkali-impregnated catalyst precursor; and
And a second calcining step of calcining the alkali-impregnated catalyst precursor. The method for producing a catalyst for producing acrylonitrile according to claim 1, wherein the catalyst for producing acrylonitrile has a composition represented by the following general formula.
_{Mo a Bi b Fe c X d} Z e O f (SiO 2) g
(Wherein Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, respectively, X is at least one alkali metal element selected from the group consisting of sodium, potassium, rubidium and cesium, Z is , Magnesium, calcium, strontium, barium, titanium, zirconium, boron, aluminum, gallium, indium, tantalum, phosphorus, arsenic, antimony, germanium, tin, lead, vanadium, niobium, chromium, tungsten, manganese, cobalt, nickel, copper , At least one element selected from the group consisting of silver, zinc, sulfur, selenium, tellurium, lanthanum, cerium, praseodymium, neodymium and samarium, SiO ₂ represents silica, a, b, c, d, e, f and g are each element (in the case of silica Silicon), and when a = 10, 0.1 ≦ b ≦ 5.0, 0.1 ≦ c ≦ 10.0, 0.01 ≦ d ≦ 3.0, 0 ≦ e ≦ 12, 10 ≦ g ≦ 200, and f is an atomic ratio of oxygen necessary to satisfy the valence of each of the above components excluding silica.)   A catalyst for producing acrylonitrile, which is produced by the production method according to claim 1 or 2.   A method for producing acrylonitrile, comprising carrying out an ammoxidation reaction of propylene using the acrylonitrile production catalyst according to claim 3.