KR810000461B1 - Method for catalytical production of acrylonitrile - Google Patents

Abstract

Acrylonitrile was prepd. by reacting propylene, ammonia and oxygen in the presence of catalyst at the rised temp. and at atmosphere. The mixture containing propylene, ammonia and oxygen were contacted with the catalyst of empirical formula, MoaCobFecXdOe. In the above formula, X = P or As or Sb; a, b, c, d, e = atomic number of each element, a: b: c: d = 12: 4-9:1-5:0.1-0.07; e = oxygen atomic number to meet average atomic values of elements; a:e = 12: 39.5-52.7.

Description

Catalytic Preparation of Acrylonitrile

The present invention relates to a process for producing acrylonitrile. More specifically, the present invention relates to a method for producing acrylonitrile by catalytic chemical reaction of propylene, ammonia and oxygen molecules at elevated temperature and gas phase.

Various methods have been known for producing acrylonitrile by contacting propylene with oxygen and ammonia at elevated temperatures and in the gas phase in the presence of a catalyst. Various types of catalysts have been published respectively in the above-described process. The present catalyst is mainly composed of an oxide composition including a bond of oxides of plural elements.

Most of the catalysts usually contain bismuth and molybdenum as catalyst components. For example, Japanese Patent Publication No. 36-5870 (1961) published P-Mo-Bi-O type catalyst and Japanese Patent Publication No. 38-17967 (1963) published Fe-Bi-Mo-PO type catalyst. Japanese Patent Publication No. 45-35287 (1970) is a P-Mo-Bi-Fe-Co-Ni-O catalyst, Japanese Patent Publication No. 49-4209 (1974) is a Ti-Mo-Fe-Bi-XP catalyst, X represents a magnesium, cobalt or nickel atom, Japanese Patent Laid-Open Publication No. 47-17718 (1972) is a Mo-Bi-Fe-Mg-PO type catalyst, and Japanese Patent Laid-Open Publication No. 48-49719 (1973) refers to Mo A catalyst of the type -Bi-Fe-Co-O has been disclosed.

However, in the production of acrylonitrile, the use of the above-described conventional catalyst has the following disadvantages. First, the reaction should proceed at a relatively high temperature of 450 ° C. or higher. Second, in order to complete the reaction, the reaction mixture should be brought into contact with the catalyst for a long time, and third, the yield of acrylonitrile relative to the unit amount of the catalyst and the unit time is relatively small.

In addition, the known catalysts described above are disadvantageous in that the price of the catalyst is relatively high. This is because they contain bismuth and molybdenum in relatively large amounts, which increases the production cost of the catalyst. Furthermore, even when the catalyst of the conventional type is used under the condition that the conversion of propylene is high by using the catalyst of the conventional type which is supposed to increase the selective conversion rate in converting propylene to acrylonitrile, Morphological catalysts exhibit relatively low selectivity in the conversion of propylene to acrylonitrile.

The above and the selectivity for conversion of propylene to acrylonitrile will be referred to below as the term "selectivity for acrylonitrile".

From the above point of view, it is evident that it is very difficult to produce acrylonitrile in high yield of 80% or more using a known catalyst which is a conventional form.

Under these conditions, the inventors' objective is to obtain (a) acrylonitrile in 80% or higher yields of its life during a relatively short reaction time at a relatively low reaction temperature, (b) to increase the reaction rate of propylene, ( c) to provide a new type of catalyst with the action of being able to convert propylene to acrylonitrile at high selectivity.

In addition, an object of the present invention is to obtain a new type of catalyst that can satisfy the above-mentioned object without using bismuth which is extremely expensive as an element of the catalyst component. Although the new type of catalyst contains bismuth, it is also required for molybdenum to contain bismuth in a proportion less than the amount of bismuth contained in another conventionally known catalyst.

An object of the present invention is to obtain a method of obtaining acrylonitrile from propylene, ammonia, and oxygen with a relatively low reaction temperature and a relatively high reaction rate.

Another object of the present invention is to catalyze the preparation of acrylonitrile from propylene, ammonia and oxygen as (a) high yield of acrylonitrile, (b) high reaction rate of propylene and (c) high selectivity of acrylonitrile. Is in developing.

It is a further object of the present invention to develop a process for the catalytic chemical preparation of acrylonitrile from propylene, ammonia and oxygen in the presence of a catalyst containing no bismuth or containing very small amounts.

In order to achieve the above object, various studies have been conducted by the inventor of the present invention. As a result of these studies, the above-mentioned object is selected from the oxides of phosphorus, arsenic, antimony and bismuth in the basic catalyst component composed of the oxides of molybdenum, cobalt and iron with an atomic ratio of the above-described elements within a specific range. It has been found that by using a new type of catalyst containing at least one component as an additional component, a small amount of this additional component is achieved.

The present invention has been developed on the basis of the above-mentioned knowledge.

That is, the above object is to contact the reaction mixture containing propylene, ammonia and oxygen molecules in a parasitic reaction as a catalyst comprising the oxide composition of the experimental formula Mo _a Co _b Fe _c X _d O _e as a catalyst of the present invention. It was completed by. Wherein X is an atom of at least one element selected from phosphorus, arsenic, antimony, bismuth, and the like, a, b, c and d each represent the number of atoms of the electric element, and a: b: c: d The ratio is in the range of 12: 4 to 9: 1 to 5: 0.01 to 0.07, e represents the number of oxygen atoms satisfying the average atom of the element, and the ratio of a: e is in the range of 12: 39.5 to 52.7.

The present invention is characterized by the use of the new type of catalyst described above. This catalyst has the following technical advantages.

(1) Even at a temperature of 380 ° C. or lower, which is a significantly lower reaction temperature than known industrial methods for catalytic chemical conversion of propylene to acrylonitrile, the catalyst of the present invention is highly active as a catalyst and has a reaction time. Is shortened to 2 seconds or less.

(2) Therefore, the amount of heat required to complete the conversion reaction is less than that required in the known method, and the lifetime of the catalyst can be used longer than that in the known method.

(3) The yield of acrylonitrile with the unit amount of catalyst is higher than that in the known method.

(4) The reaction rate of propylene and the selectivity to acrylonitrile are higher than that of known methods. Thus, the amount of by-products produced in the side reactions is smaller and the yield of acrylonitrile is higher than 80%.

(5) The price of the new type of catalyst is lower than that of the known catalyst. This is because the new type of catalyst does not contain bismuth or contains very small amounts.

(6) Therefore, the production of acrylonitrile becomes possible industrially advantageously by using a new type of catalyst.

In the novel catalyst of the present invention, the atomic ratio a: b: c: d needs to be in the range of 12: 4 to 9: 1 to 5: 0.01 to 0.07. If the content of molybdenum, cobalt and iron is outside the above range, the selectivity of acrylonitrile and the reaction rate of propylene will be reduced. In particular, the selectivity of acrylonitrile is significantly reduced. If the catalyst contains phosphorus, arsenic, antimony or bismuth in an atomic ratio above the upper limit of 0.07 above, the reaction temperature is about 380 ° C. or lower and the reaction is promoted or the reaction time is 2 seconds. Or shorter than that, but both the reaction rate of propylene and the selectivity to acrylonitrile erosion will both be reduced. It is therefore difficult to produce acrylonitrile in a yield of 80%. If the atomic ratio of phosphorus, arsenic, antimony or bismuth in this catalyst is lower than a specific lower limit of 0.01, the catalytic activity of the catalyst will decrease and the yield of acrylonitrile will be undesirably lower.

In the new type of catalyst of the present invention, the elements of the catalyst components are in the form of their oxides. Some oxides may form complexes. The majority of the electrical elements together with oxygen form compounds.

There is no limitation in the manufacturing method of the catalyst of this invention. Generally, the catalyst is prepared from a solution of molybdenum-containing compound, cobalt-containing compound, iron-containing compound and any one of phosphorus, arsenic, antimony and bismuth-containing compounds, and these solutions are made into a solid mixture and dried. The solid mixture is prepared by calcining at least 550 ° C.

Examples of the compound containing the catalytic component element include those in the form of oxides, hydroxides, salts, acids, and the like. When using salts, it is preferable to use salts in the form of pyrolysis. The molybdenum-containing compound may be selected from molybdate, ammonium molybdate, molybdenum trioxide, phosphomolybdate, ammonium phosphide, and molybdenum sulfide.

The cobalt-containing compound is selected from cobalt carbonate, cobalt nitrate, cobalt oxide (II), cobalt oxide (III), cobalt chloride, 4,3, cobalt oxide, cobalt hydroxide (II), cobalt hydroxide (III), cobalt sulfide, and the like. Can be.

Examples of iron-containing compounds include ferrous nitrate, ferric nitrate, ferrous oxide, ferric oxide, ferrous chloride, ferric chloride, ferrous hydroxide, ferric hydroxide, ferric phosphate, Iron sulfide, ferrous sulfate, ferric sulfate, and the like. The phosphorus-containing compound may be selected from pyrophosphoric acid, metaphosphoric acid, phosphoric acid, ammonium phosphomolybdate, phosphomolybdic acid, ammonium phosphate, phosphorus trichloride, 4,2, phosphorus oxide, and 5,2, phosphorus oxide and the like.

Arsenic-containing compounds are selected from arsenic chloride, arsenic anhydride and arsenic pentoxide.

The antimony-containing compound is selected from antimony trichloride, antimony pentachloride, antimony trioxide, antimony pentaoxide, antimony oxychloride, antimony first acid, diantimony acid, antimony trichloride, and antimony pentasulphide.

The bismuth-containing compound is selected from bismuth chloride, bismuth nitrate, bismuth oxide, bismuth oxychloride, bismuth hydroxide and bismuth oxide.

In the preparation of nibs, the making of the mixture aqueous solution into a solid mixture is carried out by an evaporation method. In addition, it can be prepared by precipitating all the catalyst components contained in the mixed solution.

The precipitate is separated from the mixed solution by filtration or centrifugation and then dried. In order to prepare the solid mixture thus prepared as the active catalyst, for example, it is calcined at a temperature of at least 550 ° C. for a predetermined time. The calcination temperature ranges from 550-700 ° C. and lower than 550 ° C. tends to decrease the selectivity of acrylonitrile. Calcining temperatures higher than 700 ° C. tend to reduce the reaction rate of propylene. The catalyst of the present invention described above is composed only of the catalyst component.

However, in order to improve the mechanical strength of the catalyst, it is preferable to support the catalyst component on the carrier. The carrier is more preferably composed of at least one material selected from silica, alumina, silica-alumina, silicate and the like. There is no limit to the size and shape of the catalyst. In other words, the catalyst of the present invention can be selected in a desired size, and may be formed in a desired form, for example, powder, grain, granule, femlet, or tablet, and may have a desired strength according to the purpose and conditions of the catalyst used. . Moreover, in the formation of the catalyst, it is important to ensure that there is no variation in the activity of the catalyst.

For convenience of explanation, the catalyst production method of the present invention composed of molybdenum, cobalt, iron, phosphorus, and oxygen is described below. A predetermined amount of ammonium molybdate is dissolved in a predetermined amount of water heated to 50-90 ° C. A predetermined amount of phosphoric acid is added dropwise while stirring the above solution. An aqueous solution containing a predetermined amount of cobalt nitrate and ferrous nitrate is added dropwise to the above solution.

It becomes a slurry liquid. Evaporation of the slurry liquid yields a dried solid mixture.

The dried solid mixture is calcined at a temperature of at least 550 ° C., more preferably 550-700 ° C. In order to prepare the catalyst composition added to the carrier, the carrier is mixed with the slurry described above. However, it should be understood that the catalyst preparation method of the present invention is not limited to the above description.

The reaction raw material mixture in the process of the present invention contains propylene, ammonia and oxygen molecules. This reaction raw material mixture is prepared by mixing together a raw material gas containing propylene and a gas containing ammonia and an oxygen molecule.

Pure oxygen gas may be used industrially as the oxygen molecule-containing gas. However, the oxygen molecule-containing gas is not particularly required to have a high concentration of oxygen. Therefore, the oxygen molecule-containing gas is advantageous to use air economically.

The propylene resources used in the process of the present invention do not require high purity propylene. However, the resources of propylene are more preferably liberated in the form of certain compounds, for example n-butylene and acetylene, which are reactive under the conditions under which propylene is converted.

Specific examples of the raw material mixture for the reaction of the present invention is a molar ratio of propylene and oxygen is in the range of 1: 1 to 3, more preferably 1: 1.2 to 2, the molar ratio of propylene to ammonia is in the range of 1: 0.5 to 2.0 More preferably, it is 1: 0.8-1.2. The reaction raw material mixture contains an inert dilution gas such as nitrogen, carbon dioxide, water vapor and the like which does not adversely affect the conversion of propylene into acrylonitrile. In particular, water vapor has the effect of increasing the activity and durability of the catalyst as well as the selectivity of the desired acrylonitrile. The molar ratio of diluent gas to propylene in the reaction mixture is more preferably 0.5 or higher. The pressure when contacting the reaction raw material mixture with the catalyst is effective under normal pressure, slightly increased pressure or slightly reduced pressure. However, it is convenient to carry out the contact reaction at normal pressure.

The reaction in the process of the invention is to proceed at elevated temperatures, preferably in the range of 300-470 ° C, more preferably in the range of 330-450 ° C. In particular, the process of the present invention is effective in relatively low temperatures in the range of 350-400 ° C. in particular 380 ° C. This is because the catalyst of the present invention has a high activity at the aforementioned temperatures.

The desired dark oxidation does not limit the contact time between the reaction raw material mixture and the catalyst as long as the reaction is completed within the above contact time. That is, the reaction of the present invention is completed by maintaining the reaction feed under atmospheric pressure for 0.2-10 seconds, more preferably 0.5-5 seconds, in contact with the catalyst. However, it is important that the catalyst of the present invention can be completed by contacting for 1-3 seconds, in particular for 2 seconds.

The catalyst of the present invention is used in fluidized beds, moving beds or fixed beds. In particular, the stationary phase is most suitable for carrying out the process of the present invention because it is convenient for the method of the present invention to maintain the persistence of the catalytic activity for a long time by adding water vapor to the reaction raw material mixture.

Acrylonitrile produced in the process of the present invention is separated from the reaction mixture by conventional separation methods such as those disclosed in US Pat. Nos. 3,424,781 and 3,688,002. Application of the process of the present invention allows acrylonitrile to be produced in high yields and high selectivity while limiting side reactions with the production of unwanted byproducts. In addition, in the method of the present invention, it can be said that the increase in the reaction rate of propylene does not have any kind of adverse effect on the selectivity to acrylonitrile. This is one of the industrial benefits provided by the method of the present invention.

The following examples and comparative examples will more fully explain the actuality of the method of the present invention. However, it should be understood that these examples are only illustrative and are not intended to limit the scope of the present invention.

In the Examples, the reaction rate of propylene, the selectivity to acrylonitrile and the yield of acrylonitrile were respectively calculated according to the following equations.

In the above formula, X ₁ is the molar amount of propylene contained in the raw material mixture for reaction power generation reaction in mol, and X ₂ is the molar amount of propylene remaining in the reaction mixture after the reaction is completed, and Y is generated. The amount of the acrylonitrile expressed in moles is shown.

[Example 1-4 and Comparative Example 1-2]

In Example (1), the slurry liquid of the catalyst component is prepared by the following method. First, 170.3 g of ammonium paramolybdate [(NH ₄ ) ₆ .Mo ₇ O ₂₄ 4H ₂ O] is dissolved in 250 ml of water and the solution is heated to 80 ° C. with stirring. Then 0.236 g of phosphoric acid (H ₃ PO ₄ ) is added dropwise to the solution prepared above. Then, 187.2 g of cobalt nitrate [Co (NO ₃ ) ₂ .6H ₂ O] and 65.0 g of ferrous nitrate [Fe (NO ₃ ) ₃ .9H ₂ O] were dissolved in 200 ml of water heated to a temperature of 80 ° C. The second solution prepared is added dropwise to the solution prepared previously. Thus, a slurry liquid is obtained.

In order to form a dried solid mixture of the above-mentioned material, the above-mentioned slurry liquid is heated to 120 ° C while stirring. The dried solid mixture is formed into tablets, and the tablets are formed into a diameter of 5 mm and a thickness of 5 mm. The tablet thus obtained is heated to 600 ° C. at a heating rate of 100 ° C./hr, and calcined for 5 hours at the above temperature in the calcination furnace while air flows through it.

The resulting catalyst has an atomic ratio of 12: 8: 2: 0.03 of Mo: Co: Fe: P.

The reaction column is prepared by filling 10 ml of the catalyst prepared above into a U-shaped glass tube having an inner diameter of 8 mm.

The reaction column is heated to 380 ° C. and maintained at this temperature. In the gas phase, the reaction mixture prepared by mixing the propylene, ammonia, air, and water vapor in a molar ratio of 1.0: 1.0: 11.0: 2.0 is passed through the reaction column at a flow rate of 300 ml / min. The reaction raw material mixture is brought into contact with the catalyst for 2.0 seconds.

In the catalysts of Examples (2)-(3), the atomic ratios of Mo, Co, Fe and P were 12: 8: 2: 0.05 in Example (2) and 12: 8: 2: in Example (3). Except that it is 0.07, all the rest was carried out in the same manner as in Example (1).

Example (4) was repeated in the same manner as in Example (1) except that the atomic ratio of Mo, Co, Fe and P of the produced catalyst was 12: 8: 2.5: 0.3. Was carried out at 400 ° C.

In Comparative Example (1), the same method as in Example (1) was repeated except that phosphoric acid was not used in the catalyst composition.

The same procedure as in Example (1) was repeated except that the atomic ratio of Mo, Co, Fe, and P in the catalyst composition of Comparative Example (2) was 12: 8: 2: 0.5. The proportion of phosphorus in the resulting catalyst is greater than the upper limit of 0.07 of the proportion of phosphorus carried out by the invention.

The results of the above-described examples and comparative examples are shown in Table 1.

TABLE 1

Example 5

First, 250 ml of water was heated to 80 ° C. to dissolve 170.1 g of molybdenum ammonium [(NH ₄ ) ₆ .Mo ₇ O ₂₄ .4H ₂ O] in heated water, followed by 0.468 g of antimony trioxide (Sb ₂ O ₃ ). The above solution is added and suspended with stirring. The second is prepared in the following cobalt nitrate in water, 200ml of _{80 ℃ [Co (NO 3)} 6 .6H 2 O] 186.9g of ferrous nitrate _{[Fe (NO 3) 3 .9H} 2 O] by dissolving 64.9g The solution is mixed with the suspension to prepare a slurry solution. When the obtained slurry liquid was heated and evaporated to 120 degreeC, stirring, the dried solid mixture was formed. The solid mixture is formed into tablets, each tablet having a diameter of 5 mm and a thickness of 5 mm. The catalyst is prepared by heating the tablet to 600 ° C. at a heating rate of 100 ° C./hr and calcining for 5 hours at the above temperature.

The resulting catalyst has an atomic ratio of 12: 8: 2: 0.04 of Mo: Co: Fe: Sb.

The reaction as in Example (1) was carried out using 10 ml of the catalyst thus prepared. The reaction rate of propylene is 94.8, the selectivity of acrylonitrile is 84.5, and the yield of acrylonitrile is 80.1.

[Example 6-9 and Comparative Example 3-4]

In Example (6), the first solution was prepared by dissolving 169.8 g of ammonium molybdate in 250 ml of water heated to 80 ° C. The second solution is 15% of bismuth nitrate in nitric acid is prepared by _{[Bi (NO 3) 3 .5H} 2 O] dissolved in 1.55g. The third solution is prepared by dissolving 186.6 g of cobalt nitrate [Co (NO ₃ ) ₃ .6H ₂ O] and 64.8 g of ferrous nitrate [Fe (NO ₃ ) ₃ .9H ₂ O] in 200 ml of water at 80 ° C. To prepare the slurry solution, the second solution and the third solution are added dropwise to the first solution with stirring.

In order to make the slurry liquid into a dried solid mixture, the slurry liquid is evaporated to dryness at a temperature of 120 ° C. while stirring. The solid mixture obtained is formed into tablets and the tablets are made to have a diameter of 5 mm and a thickness of 5 mm. The tablet is heated to 600 ° C. at a heating rate of 100 ° C./hr and calcined at this temperature for 5 hours to become a catalyst.

The atomic ratio of Mo: Co: Fe: Bi possessed by the produced catalyst is 12: 8: 2: 0.04. 10 ml of the catalyst prepared as above is reacted in the same manner as in Example (1).

In Example (7), the catalyst composition was carried out in the same manner as in Example (6), except that the atomic ratio of Mo, Co, Fe, and Bi was set to 12: 8: 2: 0.07.

Except that the contact reaction with the catalyst in Example (8) was carried out at 400 ℃ was the same as in Example (6).

In Example (9), the same method as in Example (6) was repeated except that the calcining temperature for producing the catalyst was changed to 650 ° C.

In Comparative Example (3), Example 6 was carried out except that the ratio of Bi was outside the ratio range of Bi carried out by the present invention so that the atomic ratio of Mo, Co, Fe and Bi was set to 12: 8: 2: 1. ) In the same manner.

In Comparative Example (4), the same method as in Comparative Example (3) was repeated except that the contact reaction was performed at 400 ° C.

The result obtained by the said Example and the comparative example is shown in Table 2.

TABLE 2

Example 10

A solution of 170.2 g of ammonium molybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O] was dissolved in 250 ml of water heated to 80 ° C., followed by arsenic trioxide (AS ₂ O _3). ) Dissolve 0.318 g. The second solution was prepared by dissolving 187.0 g of cobalt nitrate [Co (NO ₃ ) ₂ .6H ₂ O] and 64.9 g of ferrous nitrate [Fe (NO ₃ ) ₃ .9H ₂ O] in 200 ml of water heated to 80 ° C. do. To prepare the slurry solution, the second solution is added dropwise to the first solution.

The slurry liquid prepared in this way is dried at 120 degreeC, stirring to become a solid mixture. The solid mixture is formed into tablets and each tablet has a diameter of 5 mm and a thickness of 5 mm. The tablet is heated to 600 ° C. at an elevated rate of 100 ° C./hr and calcined at that temperature for 5 hours. A catalyst having an atomic ratio of 12: 8: 2: 0.04 of Mo, Co, Fe and As is obtained.

The same catalytic reaction as in Example (1) is carried out by using 10 ml of the catalyst prepared above.

As a result of the catalytic reaction, the propylene reaction rate was 95.6, the acrylonitrile selectivity was 82.2, and the yield was 78.6.

Example 11-12

In Example (11), first solution was prepared by dissolving 170.2 g of ammonium molybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O] in 250 ml of water heated to 80 ° C. Next, 0.16 g of arsenic trioxide (As ₂ O ₃ ) is dissolved in the solution.

A second solution prepared by dissolving 0.78 g of bismuth nitrate [Bi (NO ₃ ) ₃ .5H ₂ O] in 2.5 ml of 15% nitric acid and cobalt nitrate [Co (NO ₃ ) ₃ .6H _{2 in} 200 ml of water heated to 80 ° C. O] 187.0 g and ferrous nitrate [Fe (NO ₃ ) ₃ . 9H ₂ O] A third solution prepared by dissolving 64.9 g is added dropwise to the first solution being stirred to prepare a slurry solution.

The slurry solution is dried at 120 ° C. while stirring to prepare a solid mixture. The solid mixture is formed into tablets, each tablet having a diameter of 5 mm and a thickness of 5 mm. The tablet is heated to 600 ° C. at an elevated rate of 100 ° C./hr and calcined at high temperature for 5 hours. A catalyst having an atomic ratio of 12: 8: 2: 0.02: 0.02 of Mo, Co, Fe, Bi and As is obtained.

The same catalytic reaction as in Example (1) was carried out by using 100 ml of the catalyst prepared above.

In Example (12), the same procedure as in Example (11) was repeated except that 0.236 g of phosphoric acid (H ₃ PO ₄ ) was used instead of arsenic trioxide.

The results of these examples are shown in Table 3.

TABLE 3

Claims (1)

Reaction raw material mixture containing propylene, ammonia and oxygen molecules in the gas phase is contacted with a catalyst composed of an oxide composition of the experimental formula Mo _a Co _b Fe _c X _d O _e at a temperature of 300-470 ℃ Catalytic Preparation of Nitrile. In the above empirical formula, X represents at least one element selected from phosphorus, arsenic, antimony and bismuth and the like, a, b, c, d and e represent the atomic number of each element and a: b: c: d The ratio is in the range of 12: 4: 9: 1-5: 0.01 to 0.07, e represents the number of oxygen atoms satisfying the average cost of the element, and the ratio of a: e is in the range of 12: 39.5 to 52.7.