JP2008194634A - Production method of catalyst for producing acrylonitrile and production method of acrylonitrile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of catalyst for producing acrylonitrile which obtains the acrylonitrile to be an objective product at a high yield and obtains hydrocyanic acid at a high yield by suppressing ammonia combustibity. <P>SOLUTION: The production method of the catalyst for producing the acrylonitrile is the method of producing the catalyst for producing the acrylonitrile which contains molybdenum, bismuth, iron, and silica. The method has the process of obtaining dried particles by drying slurry which contains a catalyst material that contains a part or all of a component constituting the catalyst, the process of treating the dried particles at a low temperature by exposing them in the environment of 0-80°C for 10-300 hours, and the process of baking the dried particles which have been treated at a low temperature at a temperature in the range of 500-700°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an acrylonitrile production catalyst for producing an acrylonitrile production catalyst. The present invention also relates to a method for producing acrylonitrile in which an ammoxidation reaction of propylene is performed in the presence of a catalyst.

As a method for producing acrylonitrile, a method in which propylene is subjected to gas phase catalytic ammoxidation with molecular oxygen and ammonia in the presence of a catalyst is widely known. As a catalyst used in that case, for example, Patent Documents 1 to 6 disclose catalysts mainly composed of molybdenum and bismuth.
Patent Documents 7 and 8 disclose a catalyst composition of an acrylonitrile production catalyst that can suppress combustion of ammonia during an ammoxidation reaction.
Patent Document 9 discloses a method for producing an oxidation reaction catalyst mainly composed of molybdenum and bismuth. In particular, in order to improve catalyst activity and selectivity, an aqueous slurry containing a catalyst raw material is dried to obtain dry particles, and then the dry particles are exposed to an environment of 0 to 80 ° C. for 10 to 100 hours, followed by firing. A method is disclosed.
Japanese Patent Publication No. 61-13701 JP 59-204163 A JP-A-1-228950 JP-A-10-43595 JP-A-10-156185 US Pat. No. 5,688,739 JP 2000-5603 A Japanese Patent No. 2903317 Japanese Patent Laid-Open No. 2000-275992

In general, in the production of acrylonitrile by ammoxidation of propylene, not only is the production yield of acrylonitrile high relative to the amount of propylene supplied, but also industrially, the production yield of hydrocyanic acid is high relative to the amount of ammonia supplied. It is important from a point of view.
However, although the catalysts described in Patent Documents 1 to 8 were able to obtain the target product acrylonitrile in a high yield, the combustibility of ammonia was high. For this reason, the yield of hydrocyanic acid, which is an industrially useful by-product, is low and cannot be said to be sufficiently suitable for industrial use. For these reasons, there has been a demand for a catalyst that can obtain acrylonitrile in a high yield, and can suppress ammonia combustibility and can obtain hydrocyanic acid in a high yield.
The catalyst described in Patent Document 9 is a catalyst for producing methacrolein and methacrylic acid, and there is no description relating to the production of acrylonitrile.

  The present invention has been made in order to solve the above-mentioned problems. In addition to being able to obtain the target product acrylonitrile in a high yield, it is possible to obtain a high yield of hydrocyanic acid by suppressing ammonia combustibility. It aims at providing the manufacturing method of the catalyst for acrylonitrile manufacture which manufactures the catalyst for acrylonitrile manufacture which can be performed. Another object of the present invention is to provide a method for producing acrylonitrile, which can obtain acrylonitrile in a high yield and can also obtain hydrocyanic acid in a high yield.

The present invention includes the following aspects.
[1] A method for producing a catalyst for producing acrylonitrile containing molybdenum, bismuth, iron, and silica,
A step of drying a slurry containing a catalyst raw material containing a part or all of the components constituting the catalyst to obtain dry particles, and subjecting the dry particles to a low temperature treatment by exposing them to an environment of 0 to 80 ° C. for 10 to 300 hours Process,
A method for producing a catalyst for acrylonitrile production, comprising the step of calcining the dried particles subjected to low temperature treatment at a temperature in the range of 500 to 700 ° C.
[2] The method for producing an acrylonitrile production catalyst according to [1], wherein the acrylonitrile production catalyst has a composition represented by the following general formula (1).
Formula _{(1) Mo a Bi b Fe} c A d B e C f D g O h (SiO 2) i
(Wherein Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively, A is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and B is At least one element selected from the group consisting of cobalt, nickel, copper, zinc, magnesium, strontium, calcium, barium and manganese, C is chromium, vanadium, tungsten, niobium, zirconium, lanthanum, cerium, praseodymium, neodymium and At least one element selected from the group consisting of samarium, D is at least one element selected from the group consisting of thallium, silver, boron, aluminum, indium, antimony, phosphorus and tellurium, and SiO ₂ represents silica However, subscripts a, b, c, d, e, f, g, h and i represent atomic ratios. When a = 12, 0.1 ≦ b ≦ 5, 0.1 ≦ c ≦ 10, 0.01 ≦ d ≦ 3, 2 ≦ e ≦ 12, 0.5 ≦ f ≦ 5, 0 ≦ g ≦ 5, 20 ≦ i ≦ 200, and h is an atomic ratio of oxygen necessary to satisfy the valence of each component.
[3] A method for producing acrylonitrile, wherein an ammoxidation reaction of propylene is carried out using the catalyst for producing acrylonitrile produced by the method for producing a catalyst for producing acrylonitrile according to [1] or [2].

According to the method for producing a catalyst for acrylonitrile production of the present invention, acrylonitrile which can obtain acrylonitrile as a target product in a high yield and also can suppress flammability of ammonia and obtain a high amount of hydrocyanic acid. A production catalyst can be produced.
According to the method for producing acrylonitrile of the present invention, acrylonitrile can be obtained in high yield, and hydrocyanic acid can also be obtained in high yield.

Hereinafter, the present invention will be described in detail.
<Method for producing catalyst for acrylonitrile production>
A method for producing an acrylonitrile production catalyst (hereinafter abbreviated as catalyst) of the present invention is a method for producing an acrylonitrile production catalyst containing molybdenum, bismuth, iron, and silica,
A step of drying the slurry containing the catalyst raw material to obtain dry particles (hereinafter referred to as a drying step), and a step of subjecting the dry particles to an environment of 0 to 80 ° C. to perform low temperature treatment (hereinafter referred to as low temperature treatment step). And a step of calcining the dried particles that have been treated at a low temperature to obtain a catalyst (hereinafter referred to as a calcining step).

[slurry]
The catalyst raw material for obtaining the slurry contains part or all of the components constituting the catalyst. For example, the compound containing molybdenum, the compound containing bismuth, the compound containing iron, and the thing containing 1 or more types chosen from the group which consists of silica are mentioned. There is no restriction | limiting in particular as a form of each compound, According to catalyst property and a preparation method, it can select suitably.

  For example, the raw material of the molybdenum component includes an oxide such as molybdenum trioxide, a molybdic acid such as molybdic acid, ammonium paramolybdate, ammonium metamolybdate or a salt thereof, and a heteropolyethylene containing molybdenum such as phosphomolybdic acid or silicomolybdic acid. An acid or a salt thereof can be used.

  As raw materials for the bismuth component, bismuth salts such as bismuth nitrate, bismuth carbonate, bismuth sulfate, bismuth acetate, bismuth trioxide, metal bismuth, and the like can be used. These raw materials can be used in the form of a solid or as an aqueous solution, an aqueous nitric acid solution, or a slurry of a bismuth compound generated from the aqueous solution, but it is preferable to use nitrate, a solution thereof, or a slurry generated from the solution.

As raw materials for iron components, ferrous oxide, ferric oxide, ferrous nitrate, ferric nitrate, iron sulfate, iron chloride, iron organic acid salt, iron hydroxide, etc. can be used. Iron may be dissolved in heated nitric acid.
The solution containing the iron component may be used after adjusting the pH with aqueous ammonia or the like. When adjusting the pH, it is preferable to allow a chelating agent to coexist in the solution containing the iron component because precipitation of the iron component can be prevented. Examples of chelating agents that can be used here include ethylenediaminetetraacetic acid, lactic acid, citric acid, tartaric acid, and gluconic acid. When preparing an aqueous solution containing iron ions and a chelating agent, it is preferable to use these raw materials by dissolving them in an acid or water.

  As a raw material of the silica component, colloidal silica is preferable and can be appropriately selected from commercially available ones.

  Other raw materials include oxides, chlorides, sulfates, nitrates, ammonium salts, carbonates, hydroxides, organic acid salts, oxyacids, oxyacid salts, heteropolyacids that can be converted into oxides when ignited. A heteropolyacid salt or a mixture thereof can be used.

  Examples of the method for preparing the slurry include a method in which the raw materials of the respective components are mixed in colloidal silica or water in the form of a solid, a solution, or a slurry. As the solution of each component, a solution obtained by dissolving some of the plurality of components in water or nitric acid in advance can be used. As the slurry of each component, a solution obtained by previously suspending some of the plurality of components in water or the like. Can be used. The solution and slurry of each component may be subjected to pH adjustment, heat treatment, and atomization treatment.

  The pH of the slurry after mixing all the components is preferably in the range of 0 to 5, and more preferably 0.2 to 2.5. By adjusting the pH within this range, the yield of acrylonitrile and hydrocyanic acid may be improved.

  The slurry concentration is preferably 10 to 50% by mass in terms of oxides of elements constituting the catalyst. If the slurry concentration is lower than 10% by mass, the amount of water volatilized in the drying step increases, which is not rational. On the contrary, if it is higher than 50% by mass, the viscosity of the slurry becomes high, and the subsequent steps may be difficult.

  The slurry does not necessarily contain all the elements constituting the catalyst, as long as at least a part of the elements is contained. The element raw material not contained in the slurry may be added in each step up to the firing step, or may be added by impregnating the catalyst after the firing step.

[Drying process]
As a drying method in the drying step, a method of spray drying the slurry prepared as described above is preferable because spherical dry particles can be easily obtained. Examples of the spray dryer used at that time include a pressure nozzle type, a two-fluid nozzle type, and a rotating disk type.

The temperature of the hot air circulated in the drying chamber of the spray dryer is preferably 130 to 350 ° C, more preferably 140 to 300 ° C in the vicinity of the inlet into the drying chamber. Moreover, it is preferable that the temperature in the drying chamber exit vicinity is 100-200 degreeC, and it is more preferable that it is 110-180 degreeC. Furthermore, the difference between the hot air temperature in the vicinity of the inlet and the hot air temperature in the vicinity of the drying chamber outlet is preferably maintained at 20 to 120 ° C, more preferably 25 to 110 ° C.
By setting the hot air temperature within the above range, sufficiently dried particles can be obtained, and physical properties such as bulk density and particle strength of the finished catalyst can be set within a preferable range.

The dry particles referred to here are particulate solids obtained by the above drying step. Usually, the dried particles contain nitrate radicals, ammonium roots and the like derived from moisture and raw materials in addition to the elements constituting the catalyst. The contents of water, nitrate radical, ammonium root and the like vary depending on the slurry preparation method and drying conditions. The contents of moisture, nitrate radical, and ammonium root can be measured, for example, by a method such as measuring mass reduction in heat treatment.
The mass reduction when the dry particles are heat-treated at 180 ° C. for 1 hour is preferably 5 to 40% by mass, more preferably 8 to 30% by mass of the dry particle mass. When the mass reduction after the heat treatment of the dry particles is smaller than 5% by mass of the dry particle mass, the effect of the present invention is not sufficiently exhibited, the ammonia combustibility becomes high, and the cyanic acid yield decreases. On the other hand, if it is larger than 40% by mass, the dry particles are likely to adhere and solidify in the drying step or the low-temperature treatment step, and stable catalyst production may be difficult.

[Low temperature treatment process]
The low temperature treatment is preferably performed in a filling machine such as a hopper from the viewpoint of operability, but can also be performed in a drum can or a plastic bag.
The container for performing the low temperature treatment is preferably sealed. The dried particles contain nitrate and ammonium roots and are easy to absorb moisture and solidify. However, if the container is sealed, moisture absorption and consolidation can be prevented.
When the low temperature treatment is performed near room temperature, the dried particles can be gradually cooled by natural cooling or the like to bring the treatment temperature to near room temperature. In that case, the low temperature treatment is performed from the time when the temperature becomes 80 ° C. or lower.

  As the atmospheric gas for the low temperature treatment, for example, an inert gas such as air or nitrogen can be used, and air is preferable from the viewpoint of cost. Furthermore, dehumidified air is preferable because moisture absorption and consolidation can be prevented.

The lower limit of the treatment temperature in the low temperature treatment step is 0 ° C, preferably 5 ° C, more preferably 10 ° C. When the treatment temperature is lower than the lower limit, the acrylonitrile yield decreases when an ammoxidation reaction is performed using the obtained catalyst. Further, the particles may solidify due to condensation of moisture in the dried particles.
The upper limit of processing temperature is 80 degreeC, Preferably it is 70 degreeC, More preferably, it is 60 degreeC. If the treatment temperature is higher than the upper limit, ammonia combustibility cannot be suppressed.
The treatment temperature is particularly preferably about 10 to 30 ° C. from the viewpoint of economy and operability.

Moreover, the minimum of the processing time of low temperature processing is 10 hours, Preferably it is 15 hours, More preferably, it is 20 hours. If the treatment time is shorter than the lower limit, ammonia combustibility cannot be suppressed.
The upper limit of the treatment time is 300 hours, preferably 270 hours, more preferably 250 hours. When the treatment time is longer than the upper limit, the dried particles are consolidated, or the activity of the catalyst and the acrylonitrile yield are reduced.

[Baking process]
The lower limit of the firing temperature in the firing step is 500 ° C, preferably 520 ° C, more preferably 530 ° C. When the calcination temperature is lower than the lower limit, sufficient catalyst performance cannot be obtained, and the acrylonitrile yield decreases.
The upper limit of the firing temperature is 700 ° C., preferably 680 ° C., more preferably 670 ° C. When the calcination temperature is higher than the upper limit, the activity of the catalyst becomes low, or ammonia combustibility cannot be suppressed.

The lower limit of the firing time is preferably 0.1 hour, more preferably 0.5 hour, particularly preferably 1 hour. When the calcination time is shorter than 0.1 hour, sufficient catalyst performance cannot be obtained, and the acrylonitrile yield decreases.
The upper limit of the firing temperature is not particularly limited, but it is preferably 20 hours, because even if the time is longer than necessary, the obtained effect is not improved further.

  Moreover, since a catalyst with a higher acrylonitrile yield and higher yield of hydrocyanic acid is obtained, it is preferable to calcine at a temperature in the range of 200 to 490 ° C. before firing at 500 to 700 ° C.

A general-purpose firing furnace can be used for firing and temporary firing, and among them, a rotary kiln, a fluidized firing furnace, and the like can be preferably used because uniform firing is possible.
The gas atmosphere during firing may be an oxidizing gas atmosphere containing oxygen or an inert gas atmosphere such as nitrogen. Air is preferable from the viewpoint of cost.

[Composition of catalyst]
The catalyst produced by the above production method preferably has a composition represented by the following general formula (1). If the catalyst is a composition represented by the following general formula (1), the yields of acrylonitrile and hydrocyanic acid in the ammoxidation reaction are further improved.
Formula _{(1) Mo a Bi b Fe} c A d B e C f D g O h (SiO 2) i

In the formula, Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively.
A represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium and cesium.
B represents at least one element selected from the group consisting of cobalt, nickel, copper, zinc, magnesium, calcium, strontium, barium and manganese.
C represents at least one element selected from the group consisting of chromium, vanadium, tungsten, niobium, zirconium, lanthanum, cerium, praseodymium, neodymium and samarium.
D represents at least one element selected from the group consisting of thallium, silver, boron, aluminum, indium, antimony, phosphorus, and tellurium, and SiO ₂ represents silica.
The subscripts a, b, c, d, e, f, g, h, and i represent atomic ratios.

When a = 12, the lower limit of b is preferably 0.1, more preferably 0.2, and the upper limit is preferably 5, more preferably 4.5.
The lower limit of c is preferably 0.1, more preferably 0.3, and the upper limit is preferably 10, more preferably 8.
The lower limit of d is preferably 0.01, more preferably 0.03, and the upper limit is preferably 3, more preferably 2.5.
The lower limit of e is preferably 2, more preferably 2.5, and the upper limit is preferably 12, more preferably 10.
The lower limit of f is preferably 0.5, more preferably 0.6, and the upper limit is preferably 5, more preferably 4.
The lower limit of g is 0, and the upper limit is preferably 5, more preferably 4.
The lower limit of i is preferably 20, more preferably 25, and the upper limit is preferably 200, more preferably 180.
h is the number of oxygen atoms necessary to satisfy the valence of each component. The atomic ratio h of oxygen is a value inevitably determined by the valence of other elements.
If the composition of the catalyst is within these ranges, the properties thereof are preferable as a fluidized bed catalyst, and the catalyst has a higher acrylonitrile yield.

In order to make the catalyst have the above-mentioned composition, for example, a method of appropriately selecting the amount of the catalyst raw material added when preparing the slurry, or an amount of the raw material added in each step from the preparation of the slurry to the firing is appropriately selected. The method etc. are mentioned.
Further, the catalyst after the calcination may be further impregnated with a catalyst raw material to make the above range.

  The particle size of the obtained catalyst is preferably in the range of 5 to 200 μm, and more preferably in the range of 10 to 150 μm. When the particle size of the catalyst is within this range, the catalyst can be made to have a good fluidity with little scattering of the catalyst during reaction use.

  As a result of investigations by the present inventors, the above-described catalyst production method for treating dry particles at a low temperature can obtain acrylonitrile in a high yield, and also can suppress ammonia combustibility and obtain a high level of hydrocyanic acid. It was found that a catalyst for producing acrylonitrile that can be produced can be produced.

<Manufacture of acrylonitrile>
The method for producing acrylonitrile of the present invention is a method for carrying out an ammoxidation reaction of propylene using the catalyst produced by the method for producing a catalyst described above. Specifically, it is a method for producing acrylonitrile by an ammoxidation reaction of propylene in a fluidized bed in the presence of the catalyst.

 In the method for producing acrylonitrile, it is preferable to supply a raw material gas having propylene / ammonia / oxygen in the range of 1 / 1.1-1.5 / 1.5-3 (molar ratio) to the catalyst. By setting the composition of the raw material gas within the above range, acrylonitrile and hydrocyanic acid can be obtained in a higher yield.

As the oxygen source, air is preferable from the viewpoint of cost.
The source gas containing propylene, ammonia, and oxygen may be diluted with an inert gas such as water vapor, nitrogen, carbon dioxide, saturated hydrocarbon, or the like, or the oxygen concentration may be increased.

The reaction temperature is preferably 370 to 500 ° C.
The reaction pressure is preferably from normal pressure to 500 kPa.
The apparent contact time is preferably 0.1 to 20 seconds.
By setting the reaction temperature, reaction pressure, and apparent contact time within the above ranges, acrylonitrile and hydrocyanic acid can be obtained in higher yields.

  Acrylonitrile and hydrocyanic acid can be obtained in a high yield by using the catalyst produced by the above-described catalyst production method for the ammoxidation reaction of propylene.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to an Example. In the following examples and comparative examples, “part” means mass part, and “%” means mass%.

[Example 1]
Catalysts having the compositions shown in Table 1 were produced by the following method. Note that the atomic ratio of oxygen is a value that is inevitably determined by the valences of other elements, and thus description thereof is omitted. The same applies to the following examples.
408.1 parts of ammonium paramolybdate was dissolved in 850 parts of pure water (solution A).
Apart from this, 420 parts of 17% nitric acid, 124.5 parts of ferric nitrate, 336.1 parts of nickel nitrate, 49.4 parts of magnesium nitrate, 11.1 parts of manganese nitrate, 46.2 parts of chromium nitrate, nitric acid 16.7 parts of lanthanum, 41.8 parts of cerium nitrate, 3.9 parts of potassium nitrate, and 56.1 parts of bismuth nitrate were sequentially added and dissolved (solution B).
Under stirring, liquid A, liquid B and 44.7 parts of a 50% ammonium metatungstate aqueous solution were sequentially added to 1157 parts of 40% silica sol to obtain an aqueous slurry.
The obtained slurry was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. to obtain dry particles. The dried particles were sealed in a stainless steel container and kept at a temperature of 25 ° C. for 75 hours.
Then, using an electric furnace, it stood and calcined at 250 degreeC for 2 hours and 450 degreeC for 2 hours, and then fluidized and calcined at 580 degreeC for 3 hours, and the catalyst was obtained.
About the catalyst obtained in this way, the acrylonitrile manufacture by ammoxidation of propylene was performed as follows, and activity was evaluated. The evaluation results are shown in Table 2.

(Catalyst activity test)
The catalyst was packed in a fluidized bed reactor having an inner diameter of the catalyst fluidized portion of 25 mm and a height of 40 mm. A gas mixture having a composition of propylene / ammonia / oxygen (supplied as air) / water vapor = 1 / 1.1 / 2.2 / 0.5 (molar ratio) is supplied to the fluidized bed reactor. Ammoxidation reaction was carried out at 5 cm / sec. The reaction temperature was 440 ° C. and the reaction pressure was 200 kPa.

The contact time, propylene conversion rate, acrylonitrile yield, hydrocyanic acid yield, and ammonia combustion rate are defined by the following equations. In the table, the acrylonitrile yield is expressed as AN yield, and the hydrocyanic acid yield is expressed as HCN yield.
Contact time (seconds) = apparent volume density-based catalyst volume (ml) / feed gas amount converted to reaction conditions (ml / second)
Propylene conversion rate (%) = (carbon mass of supplied propylene−carbon mass of unreacted propylene) / carbon mass of supplied propylene Acrylonitrile yield (%) = (carbon mass of produced acrylonitrile / carbon of supplied propylene) Mass) × 100
Yield of cyanide (%) = (carbon mass of produced cyanide / carbon mass of supplied propylene) × 100
Ammonia combustion rate (%) = (nitrogen mass of supplied ammonia−nitrogen mass of unreacted ammonia−nitrogen mass of collected nitrogen-containing organic compound) / (nitrogen mass of supplied ammonia) × 100

[Example 2]
Catalysts having the compositions shown in Table 1 were produced by the following method.
331.0 parts of ammonium paramolybdate was dissolved in 700 parts of pure water (solution C).
Separately, 350 parts of 17% nitric acid, 113.6 parts of ferric nitrate, 90.9 parts of cobalt nitrate, 181.7 parts of nickel nitrate, 40.1 parts of magnesium nitrate, 62.5 parts of chromium nitrate, oxy Next, 4.2 parts of zirconium nitrate, 33.9 parts of cerium nitrate, 6.8 parts of praseodymium nitrate, 1.1 parts of potassium nitrate, 1.5 parts of cesium nitrate and 30.3 parts of bismuth nitrate were sequentially added and dissolved (D solution ).
Further, 0.9 parts of ammonium metavanadate and 1.0 part of boric acid were sequentially added to 50 parts of pure water and dissolved (solution E).
Under stirring, C solution, D solution, 36.2 parts of 50% aqueous solution of metatungstic acid, E solution and 1.8 parts of 85% phosphoric acid were sequentially added to 1408 parts of 40% silica sol to obtain an aqueous slurry.
The obtained slurry was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. to obtain dry particles. The dried particles were sealed in a stainless steel container and maintained at a temperature of 50 ° C. for 258 hours.
Then, using an electric furnace, it stood and calcined at 250 degreeC for 2 hours and 450 degreeC for 2 hours, and then fluidized and calcined at 590 degreeC for 3 hours, and the catalyst was obtained.
The activity of the catalyst thus obtained was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Example 3]
Catalysts having the compositions shown in Table 1 were produced by the following method.
240.2 parts of ammonium paramolybdate was dissolved in 500 parts of pure water (F solution).
Separately, 400 parts of 17% nitric acid, 50.4 parts of ferric nitrate, 33.0 parts of cobalt nitrate, 164.8 parts of nickel nitrate, 14.5 parts of magnesium nitrate, 36.3 parts of chromium nitrate, nitric acid 19.7 parts of cerium, 9.8 parts of lanthanum nitrate, 1.3 parts of indium nitrate, 0.6 parts of potassium nitrate, 1.7 parts of rubidium nitrate, and 66.0 parts of bismuth nitrate were sequentially added and dissolved (solution G). .
Further, 5.9 parts of ammonium paratungstate and 2.6 parts of telluric acid were sequentially added to 300 parts of pure water and dissolved (solution H).
Under stirring, liquid F, liquid G and liquid H were sequentially added to 1703 parts of 40% silica sol to obtain an aqueous slurry.
The obtained slurry was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. to obtain dry particles. The dried particles were sealed in a stainless steel container and maintained at a temperature of 25 ° C. for 128 hours.
Then, using an electric furnace, it stood still for 2 hours at 250 degreeC, and 2 hours at 450 degreeC, Then, it flow-fired at 610 degreeC for 3 hours, and the catalyst was obtained.
The activity of the catalyst thus obtained was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Example 4]
Catalysts having the compositions shown in Table 1 were produced by the following method.
403.0 parts of ammonium paramolybdate was dissolved in 1200 parts of pure water (Liquid I).
Separately, 17% nitric acid 450 parts ferric nitrate 99.9 parts, cobalt nitrate 110.7 parts, nickel nitrate 221.2 parts, copper nitrate 23.0 parts, zinc nitrate 28.3 parts, magnesium nitrate 24.4 parts, manganese nitrate 21.8 parts, chromium nitrate 45.7 parts, cerium nitrate 41.3 parts, neodymium nitrate 8.3 parts, potassium nitrate 1.2 parts, rubidium nitrate 2.8 parts, bismuth nitrate 73. 8 parts were sequentially added and dissolved (solution J).
In addition, 14.9 parts of ammonium paratungstate was dissolved in 750 parts of pure water (solution K).
Under stirring, liquid I, liquid J, liquid K, and 2.8 parts of antimony trioxide powder were sequentially added to 1523 parts of 30% silica sol to obtain an aqueous slurry.
The obtained slurry was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. to obtain dry particles. The dried particles were sealed in a stainless steel container and kept at a temperature of 15 ° C. for 64 hours.
Then, using an electric furnace, it stood and calcined at 250 degreeC for 2 hours, 450 degreeC for 2 hours, Then, it fluidized and calcined at 560 degreeC for 3 hours, and the catalyst was obtained.
The activity of the catalyst thus obtained was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 1]
Slurry preparation and spray drying were performed in the same manner as in Example 1 to obtain dry particles having the same composition as in Example 1. The dried particles were sealed in a stainless steel container and kept at a temperature of 25 ° C. for 3 hours.
Then, using an electric furnace, it stood and calcined at 250 degreeC for 2 hours and 450 degreeC for 2 hours, and then fluidized and calcined at 580 degreeC for 3 hours, and the catalyst was obtained.
The activity of the catalyst thus obtained was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 2]
Slurry preparation and spray drying were performed in the same manner as in Example 1 to obtain dry particles having the same composition as in Example 1. The dried particles were sealed in a stainless steel container, kept at a temperature of 25 ° C. for 361 hours.
Then, using an electric furnace, it stood and calcined at 250 degreeC for 2 hours and 450 degreeC for 2 hours, and then fluidized and calcined at 580 degreeC for 3 hours, and the catalyst was obtained.
The activity of the catalyst thus obtained was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 3]
Slurry preparation and spray drying were performed in the same manner as in Example 2 to obtain dry particles having the same composition as in Example 2. The dried particles were sealed in a stainless steel container and maintained at a temperature of 150 ° C. for 75 hours.
Then, using an electric furnace, it stood and calcined at 250 degreeC for 2 hours and 450 degreeC for 2 hours, and then fluidized and calcined at 590 degreeC for 3 hours, and the catalyst was obtained.
The activity of the catalyst thus obtained was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

The catalysts of Examples 1 to 4 obtained by leaving the dried particles in an environment of 0 to 80 ° C. for 10 to 300 hours had high acrylonitrile yield and hydrocyanic acid yield.
The catalyst of Comparative Example 1 obtained by leaving the dried particles in an environment of 0 to 80 ° C. for less than 10 hours had a low hydrocyanic acid yield.
The catalyst of Comparative Example 2 obtained by leaving the dried particles in an environment of 0 to 80 ° C. for more than 300 hours had low acrylonitrile yield and hydrocyanic acid yield.
The catalyst of Comparative Example 3 obtained by allowing the dried particles to stand for 10 to 300 hours in an environment at a temperature exceeding 80 ° C. had a low hydrocyanic acid yield.

Claims (3)

A method for producing a catalyst for acrylonitrile production comprising molybdenum, bismuth, iron, and silica,
A step of drying a slurry containing a catalyst raw material containing a part or all of the components constituting the catalyst to obtain dry particles, and subjecting the dry particles to a low temperature treatment by exposing them to an environment of 0 to 80 ° C. for 10 to 300 hours Process,
A method for producing a catalyst for acrylonitrile production, comprising the step of calcining the dried particles subjected to low temperature treatment at a temperature in the range of 500 to 700 ° C. 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 (1).
Formula _{(1) Mo a Bi b Fe} c A d B e C f D g O h (SiO 2) i
(Wherein Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively, A is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and B is At least one element selected from the group consisting of cobalt, nickel, copper, zinc, magnesium, calcium, strontium, barium and manganese, C is chromium, vanadium, tungsten, niobium, zirconium, lanthanum, cerium, praseodymium, neodymium and At least one element selected from the group consisting of samarium, D is at least one element selected from the group consisting of thallium, silver, boron, aluminum, indium, antimony, phosphorus and tellurium, and SiO ₂ represents silica However, subscripts a, b, c, d, e, f, g, h and i represent atomic ratios. When a = 12, 0.1 ≦ b ≦ 5, 0.1 ≦ c ≦ 10, 0.01 ≦ d ≦ 3, 2 ≦ e ≦ 12, 0.5 ≦ f ≦ 5, 0 ≦ g ≦ 5, 20 ≦ i ≦ 200, and h is an atomic ratio of oxygen necessary to satisfy the valence of each component.   A method for producing acrylonitrile, wherein an ammoxidation reaction of propylene is carried out using the catalyst for producing acrylonitrile produced by the method for producing a catalyst for producing acrylonitrile according to claim 1 or 2.