JPS58118551A - Preparation of unsaturated nitrile - Google Patents

Abstract

PURPOSE:To prepare the titled compound in high selectivity and yield, by the ammoxidation of the corresponding olefin in the presence of a specific catalyst at high temperature in a vapor phase. CONSTITUTION:The objective compound is prepared by the ammoxidation of an olefin in the presence of a catalyst of formula (X is P, As or Sb; A is alkali metal; B is Fe, Cr or W; a-h represent the numbers of respective atoms, and when a=10, then b and c are 0.1-10, d is 0.01-1, e and g are 0-10, f is 0-1, and h is a value defined by the numbers of atoms other than O and is usually 31.5-112) (prepared, e.g. by calcining at 400-700 deg.C for 0.5-20hr in air) at high temperature in vapor phase. It is not necessary to use high purity oxygen for the ammoxidation reaction, and it is economical and convenient to use air as the oxygen source.

Description

[Detailed description of the invention] This invention relates to olefins such as propylene.

The present invention relates to a method for producing corresponding unsaturated nitriles such as acrylonitrile and methacrylonitrile by ammoxidizing isobutylene or the like in the presence of a catalyst in a high temperature gas phase.

The method of producing the corresponding unsaturated di-IJ by ammoxidation of an olefin in the presence of a catalyst in a high-temperature gas phase is well known, and many catalysts for use in this process have already been proposed.

For example, in Japanese Patent Publication No. 36-5870, MO-B1-
(p) system catalyst, B15 in Japanese Patent Publication No. 47-8526
b04 ToPbMoO4 and Garanal catalyst, 4 years old
-6649 publication, Tl-P-Mo-'Fe-B
i-Ni-Pb type catalysts, and Mo-W-Bi-Pb type catalysts are described in JP-A-54-110997.

However, in general, even with catalysts that have excellent selectivity toward unsaturated IJ, it is necessary to keep the olefin reaction rate low in order to maintain the selectivity at a high value. Then, the selectivity tends to decrease.

In addition, some of the catalysts proposed so far can produce unsaturated nitriles in relatively high yields, but catalysts containing lead as a catalyst component reduce the olefin reaction rate to 100%.
If it is increased to a similar value, the selectivity for unsaturated nitrile is at most about 80%, and the yield of unsaturated nitrile cannot be said to be sufficient.

As a result of intensive research aimed at developing a catalyst that can produce unsaturated nitriles with higher selectivity and yield using a catalyst containing lead as a catalyst component, the inventors discovered that molybdenum, bismuth, and lead A catalyst containing thallium can produce unsaturated nitrile in good yield with a high selectivity of about 85% even if the olefin reaction rate is increased to nearly 100%. This invention was based on the discovery that adding it as a component further improves catalyst performance.

This invention relates to a method for producing a corresponding unsaturated nitrile by ammoxidizing an olefin in a high-temperature gas phase in the presence of a catalyst, using the following general compositional formula as a catalyst.

MOaBibPboTtdXoAfBgoh [In this formula, +MO is molybdenum + Bi is bismuth.

Pb is lead, Tt is thallium, X is one or more elements selected from the group consisting of phosphorus, arsenic, and antimony, A is an alkali metal, and B is one element selected from the group consisting of iron, chromium, and tungsten. In the above elements, 0 indicates oxygen, subscripts a-h indicate the number of atoms, and if a=1Q, b=0.1-10, c=0.1-10. d
=0.01~i, e=0~10. f=o~1. ri = o to 1o, and h is a value naturally determined from the valence of the element other than oxygen.

It usually takes a value of 31.5 to 112. ] The present invention relates to a method for producing an unsaturated nitrile characterized by using a composition represented by the following.

The catalyst used in the present invention contains thallium as a catalyst component along with molybdenum, bismuth, and lead, and thallium has a remarkable effect on improving the selectivity of the target product, unsaturated nitrile. The optimal amount of thallium in the catalyst is within the above range; if thallium is less than 0.01 gram atom per 10 gram atom of molybdenum, the effect of adding it will be small, and if it is more than 1 gram atom, the effect of adding thallium will be small. Although the selectivity is improved, the reaction rate of olefin must be kept low, and the yield of unsaturated nitrile is lowered, so it is not suitable. In addition, in the catalyst represented by the above-mentioned membrane composition formula, one or more elements selected from the group consisting of phosphorus, arsenic, and antimony, which are 2% components, have a strong effect of improving the selectivity of unsaturated IJ. In particular, it is desirable that the atomic element be contained in the catalyst in an amount ranging from 0.01 to 7 gram atoms per 10 gram atoms of molybdenum. The alkali metal of component A is not particularly limited, but potassium, cesium, rubidium, sodium, etc. are preferably used. Still, the B component is one or more elements selected from the group consisting of iron, chromium, and tungsten, but among these, iron is preferable, and the B component is 0 to 10 g atoms per 10 g atoms of molybdenum. , preferably in an amount of 0.01 to 10 gram atoms.

The catalyst used in the method of the present invention can be prepared by a conventionally known method for preparing an oxidation catalyst (preparation operation).

Generally, a compound 2 containing each component element constituting the catalyst, such as a salt of each component element.

After mixing a predetermined amount of oxide etc. in the presence of water.

Dry, 400-700℃, preferably 500-670℃
It can be prepared by calcination at a temperature of °C. More specifically, a predetermined amount of a compound 9 containing each element, such as a salt or oxide of each element, is mixed in the presence of water to form a slurry or paste, and then dried and fired at the above temperature. , or by evaporating to dryness a mixed solution or suspension in which predetermined amounts of salts, oxides, etc. of each element are mixed in the presence of water, and then calcining the dried product at the above-mentioned hot water temperature, or the above-mentioned mixture is A coprecipitate containing each element is generated from the solution and separated.

After drying, the catalyst can be prepared by calcining at the above temperature. It is generally convenient to perform firing in an air atmosphere, and the firing time is generally 0.5 to 2.
0 hours, preferably 2 to 15 hours is suitable. If the calcination temperature is too low, the catalyst will have a low unsaturated nitrile selectivity, and if it is too high, the olefin reactivity will be low. Therefore, the calcination temperature during catalyst preparation is Temperatures within the above range are suitable.

In the preparation of the catalyst used in this invention, compounds containing each component element used as starting materials for catalyst preparation include molybdic acid, ammonium molybdate, molybdenum compounds such as molybdenum oxide, bismuth nitrate, and bismuth chloride.

Bismuth oxide, bismuth hydroxide, bismuth hydroxide nitrate,
Bismuth compounds such as bismuth oxide carbonate, bismuth oxide nitrate, bismuth oxide chloride, lead nitrate.

Lead compounds such as lead acetate and lead hydroxide, and thallium nitrate.

Thallium compounds such as thallium acetate and thallium sulfate, phosphorus compounds and phosphorus such as sulfuric acid, metaphosphoric acid, phosphorous acid, phosphoric anhydride, and various organic phosphorus compounds.

Arsenic compounds such as arsenic acid, arsenic trioxide, arsenic pentoxide, arsenic, antimony trioxide, antimony pentoxide.

Antimony compounds such as antimony chloride and antimony metals, sodium, potassium, and rubidium.

Nitrates of alkali metals such as cesium, alkali metal compounds such as chloride, ferric nitrate, iron carbonate, iron sulfate,
Iron compounds such as iron hydroxide and iron oxide.

Mention may be made of chromium compounds such as chromium nitrate, chromic acid, chromium sulfate and chromium oxide, and tungsten compounds such as ammonium paratungstate and tungstic acid, generally ammonium salts soluble in water, aqueous ammonia or nitric acid.

It is convenient to use nitrates, oxides, etc. as starting materials for catalyst preparation. Furthermore, compounds containing multiple component elements such as lead molybdate, phosphomolybdic acid, iron molybdate, and bismuth antimonate may be used as starting materials for catalyst preparation.

One example of a preferred method for preparing the catalyst used in the present invention will be explained using a catalyst consisting of molybdenum, bismuth, lead, thallium, antimony, cesium, iron, and oxygen.

A predetermined amount of a water-soluble molybdenum compound such as molybdic acid or ammonium molybdate is dissolved in water or aqueous ammonia at about 50° C., and antimony trioxide is added thereto to suspend it (liquid A).

A predetermined amount of a bismuth compound soluble in nitric acid, such as bismuth nitrate or bismuth hydroxide, is dissolved in an aqueous nitric acid solution, and a lead compound such as lead nitrate or lead hydroxide, or a thallium compound such as thallium nitrate or thallium acetate is added to this.

Predetermined amounts of each of a cesium compound such as cesium nitrate and an iron compound such as ferric nitrate are added and dissolved (solution B).

Add liquid B to liquid A while stirring to form a slurry mixture. After adjusting the pH of the mixed liquid to 2 or less, it is dried by evaporation to dryness or spray drying, and the mixture is dried at 400 to 700°C, preferably 500 to 670°C, in an oxygen-containing gas atmosphere, for example, in an air atmosphere, to a temperature of 0.5 Bake for ~20 hours, preferably 2-15 hours. In order to obtain a catalyst that gives favorable results, it is preferable to adjust the pH of the mixed solution to the above-mentioned low value.

The desired catalyst is obtained by calcination.

In this invention, the catalyst may be used with or without being supported on a carrier. As the carrier, any of those conventionally known as carriers for catalysts for ammoxidation of olefins can be used, such as silica, titania, alumina, silica-alumina, zirconia, diatomaceous earth, silicon carbide, and various silicates. I can do it. When the catalyst is supported on the carrier, the amount of the carrier is not particularly limited, but in general, the ratio of the carrier to 12 of the catalyst is 0.05 to 3, preferably 0.1 to 22. The size and shape of the catalyst particles may be appropriately shaped and sized depending on the conditions of use.

The method of the present invention may be carried out in any reaction mode, such as fixed bed or fluidized bed. When the reaction is carried out in a fluidized bed, it is preferable to add a carrier component such as silica sol at the time of catalyst preparation and spray dry it to prepare a catalyst in the form of powder particles of about 60 to 100 microns.

In carrying out this invention, in addition to olefin, oxygen, and ammonia, a gas substantially inert to the ammoxidation reaction may be mixed and used as a diluent gas. As a diluent gas.

Examples include water vapor, nitrogen gas, carbon dioxide gas, etc. Among them, water vapor has the effect of improving the selectivity of unsaturated nitriles and sustaining catalytic activity, so it is particularly useful when the reaction is carried out in a fixed bed. It is preferable to carry out the reaction by adding water vapor. The amount of water vapor added is 0.1 to 5 mol, preferably 0.5 to 5 mol, per 1 mol of olefin.
4 moles is suitable. In addition, when the reaction is carried out in a fluidized bed, the water produced by the 9 reaction fulfills the above-mentioned role, so that the reaction can be carried out smoothly even without adding water vapor.

In this invention, the reaction pressure is usually normal pressure, but may be under a low pressure or reduced pressure. Also, the reaction temperature is 350~
A temperature of 550°C, preferably 420-500°C is suitable.

Further, the appropriate contact time is 1.5 to 20 seconds, preferably 2 to 10 seconds. In the method of this invention, the reaction temperature is about 450'C.

Best results are obtained with a contact time of about 4 seconds.

The olefins used in this invention include propylene,
Examples include inbutylene and methylstyrene, among which propylene and isobutylene are preferred. Further, the olefin does not necessarily have to be highly pure, and may contain a small amount of hydrocarbon 2, such as methane, ethane, propane, etc., which is substantially inert to the ammoxidation reaction. The amount of inert hydrocarbons to be incorporated is preferably 0.5 mol or less, preferably 0.1 mol or less, per 1 mol of olefin.9 Hydrocarbons that are substantially active under the reaction conditions, e.g. It is better to avoid contamination with acetylenes, etc.

Although pure oxygen gas may be used as the oxygen used in the ammoxidation reaction, it is not necessary to have particularly high purity, so it is generally economical and convenient to use air.

In this invention, the ratio of oxygen supplied to olefin is 1 to 4 mol, preferably 1.2 to 3 mol, per 1 mol of olefin, and the ratio of ammonia supplied to olefin is 1 to 4 mol, preferably 1.2 to 3 mol. Morni vs Shite 0
．． Suitable amount is 5 to 2 mol, preferably Schiff is 0.8 to 1.2 mol. Raw material gas (olefin +
The olefin concentration in the olefin (acid, L 77 mole, inert gas, etc.) is suitably 1 to 20 volumes, preferably 2 to 10 volumes.

Next, Examples and Comparative Examples will be shown.

On each side, the reaction rate of olefin ((a), the selectivity of unsaturated nitrile (a) and the yield of unsaturated nitrile@)
are according to the following definitions.

Example 1 Ammonium halamorifthenate [(NH4)6Mo70
24.4H20) 5'9.71 was dissolved in 600 g of 2.5% ammonia water at 50° C., and antimony trioxide (Sb203) + 4.7 y was added thereto to obtain a suspension solution. On the other hand, lead nitrate [Pl:+(No3)3] 84. Or
, taliuno nitrate (TtNo3:) o, i, 5g,
Cesium nitrate (CsNO3:) 0.631 and ferric nitrate (Fe(NO3)39H2o ) 1 '5.66
? 50ml of 50℃ warm water! A solution of bismuth nitrate (Bi (N03)35H20) 62.81 dissolved in 50 rttl of 15% nitric acid aqueous solution was mixed, and the resulting mixed solution was mixed with the above-mentioned ammonium molybdate and 35H20. It was added dropwise to a suspension solution containing antimony oxide while stirring to obtain a slurry-like mixed solution. Furthermore, add 30% silica sol 200% to this solution. After adding
pH of slurry solution with 15% nitric acid aqueous solution = 1.5
It was adjusted to

Next, this slurry solution was dried using a drum dryer to obtain a uniform catalyst composition. The obtained powder is
After heat treatment at 230°C for 16 hours.

The grain size was sized to 14 mesoyu or less. Furthermore, add this powder to 5
A catalyst was prepared by forming a tablet of Wng

The composition of this catalyst is M 01 (I B i2 P
b7. s Tto, )5Sb3 cso, 05
Fe 1 (excluding oxygen (+ 5i0230% by weight)
contained).

The catalyst 20d prepared in this way has an inner diameter of 16wn96
Fill a glass U-shaped reaction tube with propylene:
A mixed gas of ammonia: air: water vapor = 1:1.1:11:4 (molar ratio) is flowed at a flow rate of 400 m//min 1
The ammoxidation reaction was carried out at a reaction temperature of 440° C. and a contact time of 6.0 seconds.

The results of the ammoxidation reaction after 2 hours (the same applies hereinafter) were as shown in Table 1.

When 10 batches of this catalyst were prepared, catalysts having almost the same performance as shown in Table 1 could be obtained with good reproducibility.

Examples 2 to 8 Catalysts having the catalyst compositions shown in Table 1 were prepared according to the catalyst preparation method of Example 1. Using the catalyst thus obtained,
A propylene ammoxidation reaction was carried out under the same reaction conditions as in Example 1.

The results of the ammoxidation reaction are shown in Table 1.

Comparative Example 1 The catalyst composition (oxygen was except.

5in230% by weight) is r M 016 B 1
A catalyst of 2P b7.5 was prepared, and an ammoxidation reaction of polypylene was carried out under the same reaction conditions as in Example 1.

As a result, the propylene reaction rate was 99.0%, the acrylonitrile selectivity was 77.1%, and the acrylonitrile yield was 76.3%.

Examples 9 to 13 According to the catalyst preparation method of Example 1, catalysts having the catalyst compositions shown in Table 2 were prepared. The starting materials for phosphorus, arsenic, and tungsten are phosphoric acid, arsenic acid, and ammonium paratungstate.

These, as well as antimony trioxide, were added to the solution of Nokumo 1J ammonium fodate. Nat 1 noum.

For each starting material of potassium, rubidium, and chromium, nitrates were used, and these were dissolved in a nitric acid solution prepared by dissolving bismuth nitrate in an aqueous nitric acid solution.

Using the catalyst obtained in this way, the second reaction temperature was
The ammoxidation reaction of propylene was carried out under the same reaction conditions as in Example 1 except that the temperature listed in the table was changed. The results of the ammoxidation reaction are shown in Table 2.

Table 2 Example 14 Using the same catalyst as in Example 1, the procedure of Example 111 was carried out.

An ammoxidation reaction of isobutylene was carried out under the same reaction conditions as in Example 1 except that robylene was replaced with inbutylene and the reaction temperature was changed to 420°C.

As a result, the reaction rate of isobutylene was 98.6%.

The selectivity of methacrylonitrile is s 1. s %, the yield of methacrylonitrile was ao, 7%.

Comparative Example 2 Using the same catalyst as in Comparative Example 1, an ammoxidation reaction of isobutylene was carried out under the same reaction conditions as in Example 7. As a result, the reaction rate of isobutylene was 99.3'%, the selectivity of methacrylonitrile was 77.6%, and the yield of methacrylonitrile was 77.1%.

Example 15 Silica sol 3801 was added to the slurry mixed solution of Example 1 in place of the 200v amount of silica sol in Example 1, and then the pH of the slurry solution was adjusted to 1 with a 15% nitric acid aqueous solution.
．． 5 and aged while stirring for 2 hours.

Next, this slurry solution was homogenized using a homogenizer, and a rotating disk type spray drying device was used.

After spray-drying to fine particles according to a conventional method, the particles were dried at 230°C for 16 hours, and then heated to 100°C in an air atmosphere in a calcining furnace.
The catalyst was heated at a temperature increase rate of °C/hr and calcined at 540 °C for 10 hours to obtain a catalyst having pores on the surface with an average particle size of 60 μm. The catalyst composition of this catalyst was the same as that of Example 1, but it contained 45% by weight of silica as a carrier.

Then, the catalyst 150++y/ thus obtained was put into a fluidized bed reactor with an inner diameter of 3611aR5Z', and the ratio of propylene:ammonia:air:steam=1.14:12.
06:1 (molar ratio) mixed gas is 1.922.6
flowing at a flow rate of me/min, contact time 4.68 seconds2
The ammoxidation reaction of Probile/ was carried out at a reaction temperature of 470°C. As a result, the propylene reaction rate was 99.6%, the acrylonitrile selectivity was 87.3%, and the acrylonitrile yield was 87.0%.

Comparative Examples 6 to 15 According to the preparation method of Example 1, catalysts having catalyst compositions shown in Table 3 (Sin carrier, containing 30% by weight) were prepared. Using these catalysts, a propylene ammoxidation reaction was carried out under the same reaction conditions as in Example 1.

The results of the ammoxidation reaction are shown in Table 3.

Table 3 (* Contains carrier Sin, 50% by weight)

Claims (1)

[Claims] A method for producing a corresponding unsaturated IJ by ammoxidizing an olefin in a high temperature gas phase in the presence of a catalyst,
The following general composition formula as a catalyst. MOaBlbPboTtdXoAfBgOh [This) Illusion MO O is molybdenum, Bi is bismuth, Pb is lead, T
t is thallium or one or more elements selected from the group consisting of phosphorus, arsenic and antimony, A is an alkali metal, B is one or more elements selected from the group consisting of iron, chromium and tungsten, and 0 indicates oxygen, the subscripts a-h indicate the number of atoms, and if a; 10, then 1)
=Q, 1~10゜020.1~10. d=0.01~1
．． e=0 to 10 degrees f=0 to 1 tt=O to 10, and h is a value naturally determined from the valence of the element other than oxygen, and usually takes a value of 31.5 to 112. ] A method for producing an unsaturated nitrile, characterized by using a composition represented by: