KR800001379B1 - Catalytic ammoxidation of olefins to nitriles - Google Patents

Abstract

No content.

Description

Process for producing nitriles by catalytic chemical dark oxidation of olefins

The present invention relates to a process for the production of acrylonitrile by catalytic oxidization of propylene. More specifically, the present invention relates to a method for producing acrylonitrile by subjecting a reaction mixture gas containing propylene, ammonia, oxygen, and the like to be reacted at a relatively low temperature with a catalyst having enhanced activity than a conventional catalyst in a gas phase.

In the production of unsaturated nitriles corresponding to olefins which are conventionally charged and supplied with olefins without reducing the conversion of olefins by catalytic chemical amoxidation in the gas phase, the selectivity for increasing the selectivity to the desired unsaturated nitriles is increased. In view of the above, various kinds of catalysts for reaction have been published. Known catalysts for this purpose include, for example, Japanese Patent Publication No. 5870/61 composed of molybdenum, bismuth and any amount of phosphorus, Japanese Patent Publication No. From the catalyst disclosed in Japanese Patent Publication No. 24367/65 consisting of 13966/62, the uranium and antimony, and the catalyst disclosed in Japanese Patent Publication No. 19111/63 consisting of iron and antimony. It was composed by the combination of two or more metal elements as shown. In general, it is often difficult to upgrade both the desired selectivity to unsaturated nitrile and the high conversion of olefins. For example, in order to obtain high selectivity, the conversion rate needs to be adjusted. As these well-known catalysts, even if there were many yields of unsaturated nitriles, it was about 70%. Such a closed end is caused by a long contact time and a high reaction temperature, for example, because a reaction temperature of 450 ° C. or higher is required, so that the yield of unsaturated nitrile for a certain amount of catalyst can be obtained. Silver was inevitably lowered and the life of the catalyst was shortened.

The inventors have conducted a number of studies on catalysts composed of molybdenum, bismuth, iron, cobalt and the like as catalysts for oxidizing olefins. However, even when controlling the conversion of olefins with the above-described catalyst, it was difficult to make the selectivity to unsaturated nitrile to 80% or more, or to obtain the yield of 80% or more.

Therefore, an important object of the present invention is to obtain a catalyst having a higher conversion and selectivity even at a lower reaction temperature, and a catalyst for dark oxidation which has a longer life even at a relatively high reaction temperature.

Other objects and features of the present invention will become more apparent from the following description.

The present invention uses a catalyst comprising oxides such as (A) molybdenum, (B) bismuth, (C) iron, (D) cobalt and (E) zirconium in an atomic ratio as shown in the following ingredient formula. A method for producing acrylonitrile is performed by performing ammoxidation by catalytic chemical reaction of a reaction gas containing ammonia and oxygen at a reaction temperature of 300-550 ° C. for 0.3-20 seconds.

Mo _a Bi Co _b Fe _c Zr _d O _e

In the above formula, a, b, c and d are integer values of each metal element in atomic ratios based on bismuth, preferably in the range of a = 1.0-20.0 but in the range of 5-15.0. b = 1.0-10.0, preferably 2.0-8.0, c = 0.2-5.0 but preferably 0.5-4.0, d = 0.05-4.0 It is preferable to set the range, and e is an integer value generally reduced to 6-86, which is a value that can satisfy the valence of each member.

The catalyst of the present invention is beneficial and effective in the composition range of the metal oxide described above, but when it does not contain zirconium, it affects the selectivity and mechanical strength to nitrile.

There is no limit to the method for producing this catalyst. However, in the case where each metal component is formed so as to satisfy the component formula of the catalyst indicated above, the catalyst of the present invention is produced even by any known method. Generally, this catalyst is prepared by the following method. Each metal-containing compound is mixed sequentially to form a precipitate in an aqueous medium or a slurry is formed with as little water as possible. The resulting mixture, ie the precipitate or slurry described above, is heated and calcined at 400-700 ° C. after drying.

The starting material used for this may be an oxide or a salt or a mixture thereof. Examples of the compound containing a metal component include molybdenum-containing compounds, such as ammonium molybdate, molybdenum oxide, ammonium molybdate oxychloride, molybdenum oxychloride, and molybdenum chloride, and the bismuth-containing compound as bismuth nitrate , Bismuth oxide, bismuth hydroxide, bismuth hydroxy nitrate, bismuth chloride, iron-containing compounds iron oxide, iron nitrate, iron hydroxide, iron chloride, cobalt-containing compounds cobalt nitrate, cobalt oxide, cobalt hydroxide, cobalt chloride and chloride Ammonium cobalt and the zirconium-containing compounds include zirconyl nitrate, zirconyl chloride, zirconium oxide and zirconium hydroxide.

One preferred method for producing the catalyst of the present invention is described below. A predetermined amount of ammonium molybdate is dissolved in warm water. A solution of bismuth nitrate previously identified in the aqueous solution in nitric acid solution and a predetermined amount of ferric nitrate, an aqueous solution of ferrous nitrate, and cobalt nitrate and zirconyl nitrate are added dropwise at the same time to form a slurry. The slurry is heated to dry and then calcined to 400-700 ° C. The calcined powder is powdered to form pellets or granules of the desired shape and size. If a separate promoter or carrier is to be added, it is preferred to add it in a step prior to drying of the precipitate.

As a result of X-ray analysis, the main part of the catalyst was composed of two or more types of metal oxides such as, for example, cobalt molybdate, iron molybdate, zirconium molybdate, bismuth ferrate, and bismuth zirconate, and a small part of the catalyst It is proved that the metal is in the form of oxide.

This catalyst can be used alone or in combination with a known carrier. As a carrier having a good influence on the progress of the reaction, for example, silica, alumina, alumina-silica, silicate and the like, and those which prevent activation by heat treatment can be used as useful carriers. These carriers use any amount as desired.

The use of this catalyst can be either fluid bed or stationary bed. The size and shape of the catalyst is not limited and is primarily determined by either the fluidized bed or the fixed bed. In order to give the mechanical strength required for this catalyst, it is molded or granulated in a known manner.

In carrying out the present invention, the propylene to be supplied is not required to be highly pure, and propylene containing saturated hydrocarbons such as propane and butane may also be used. However, for example, acetylene, n-butylene and similar substances that can produce unwanted by-products under certain reaction conditions are removed because they will affect the dark oxidization reaction if certain limits are exceeded.

For the same reason, diluents that do not affect the cancer oxidation reaction do not have harmful consequences, so they may be contained in the charging mixture gas. Examples of such diluents include water vapor, nitrogen, carbon dioxide, and the like. The amount of these diluent gases contained in the reaction mixture gas is preferably more than 0.5 moles with respect to 1 mole of propylene. In addition to the simple diluent, the water vapor in the above-mentioned mixed gas serves to improve the selectivity for the production of acrylonitrile, and also to maintain the catalytic activity. Therefore, it is generally preferred to add water vapor to the reaction charge gas, especially when the reaction proceeds in a fixed manner. The amount of steam to be added is preferably at least 0.5 mole with respect to 1 mole of propylene. When the reaction is carried out in a fluidized bed, water generated by the reaction acts as water vapor, so it is not necessary to add water vapor separately.

As the oxygen source required for the dark oxidation reaction of the present invention, even pure oxygen or any kind of oxygen-containing gas can be used. In particular, air can be used to advantage. The oxygen content in the reaction gas mixture is in the range of 0.8-4 moles of oxygen per mole of propylene, and preferably in the range of 1 moles to about 2.5 moles. When oxygen is exceeded than the above range, unnecessary carbon monoxide, carbon dioxide, and the like are byproducts. On the contrary, if the oxygen supply amount is less than the above range, the selectivity regarding the production of the desired product is reduced.

The ammonia in the semi-adaptive mixed gas is preferably 0.5-3 mol to 1 mol of propylene, but preferably 0.8-1.2 mol.

The dark oxidation reaction is usually carried out at normal pressure, but if necessary, may be carried out under a slightly pressurized or slightly reduced state.

The temperature range of this reaction is preferably 300-550 ° C., preferably between 350-500 ° C. Exceeding the reaction temperature leads to decomposition of propylene, reduced selectivity and triggered unwanted side reactions. In order to obtain the most suitable performance, the reaction is carried out at about 400 ° C.

The contact time with the catalyst in carrying out the process is 0.3-20 seconds, preferably 0.5-15 seconds. Exceeding the contact time above the upper limit will degrade the reaction product and cause other undesirable side reactions.

The present invention will be described in the following examples and comparative examples, and the scope of the present invention is not limited to these examples in any case, which is only to be described in the description of the present invention. Unless otherwise specified, the percentages indicated in these examples are% of the weight indication, and "conversion%", "selectivity%" and "yield%" are calculated by the following formula.

The yield mentioned above means the yield of the first pass.

Example 1

318.6 g of ammonium molybdate [(NH ₄ ) ₆ No ₇ O ₂₄ .4H ₂ O] was dissolved in 450 ml of water at a temperature of 80 ° C. in a bath. Bismuth nitrate [Bi (NO ₃ ) _{3. To} 110 ml of 15% nitric acid while stirring the solution. 5H ₂ O] solution of 87.6 g of ferric nitrate [Fe (NO ₃ ) ₃ . 6H ₂ O] 72.9 g and nitrate cobalt [Co (NO ₃ ) ₂ . 6H ₂ O] 210.0 g and zirconyl nitrate [ZrO (NO ₃ ) ₂ . 2H ₂ O] was added dropwise at the same time a solution of 9.6 g dissolved in 200 ml of water at 80 ℃. The slurry thus obtained is stirred and heated to dryness to obtain a powder. This powder was formed into a tablet by heating it to 510 ° C at a heating rate of 20 ° C / hr, and calcined at the same temperature for 10 hours to form a catalyst.

The atomic ratio of the element component contained in the catalyst thus prepared is set to Mo: Bi: Co: Fe: Zr: O = 10: 1: 4: 1: 0.2: 37.4.

8 ml of the catalyst thus obtained are charged into a vitreous U-type [reaction tube having an internal diameter of 8 mlm. A reaction mixture gas containing four components of propylene, ammonia, air, and water vapor in a molar ratio of 1.0: 1.0: 11.0: 2.0, respectively, was charged at a rate of 150 ml / min into the above-described reaction tube filled with a catalyst and maintained at 400 ° C. Pass it through. The contact time at this time is 3.2 seconds.

As a result, the conversion of propylene, the selectivity to acrylonitrile and the yield of acrylonitrile were 94.2%, 85.2% and 80.3%, respectively.

[Examples 2 to 10]

A catalyst was prepared in the same manner as in Example 1 above, but using only a catalyst whose composition ratio was varied as shown in the first table below. Amoxidation is performed by the method similar to Example 1 using the various catalysts comprised in this way. The results are shown in the first table.

Example 11

395.5 g of ammonium molybdate [(NH ₄ ) ₆ No ₇ O ₂₄ .4H ₂ O] is stirred and dissolved in 644 ml of water. The solution was kept at 90 ° C., and 1 cobalt nitrate [Co (NO ₃ ) ₂ . 6H ₂ O] 391.1 g and ferric nitrate [Fe (NO ₃ ) ₃ . 6H ₂ O] Bismuth nitrate [Bi (NO ₃ ) ₃ ] in 385 ml of a solution of 90.5 g dissolved in 10% nitric acid solution. 5H ₂ O] 108.7 g Zirconyl nitrate [ZrO (NO ₃ ) ₂ . 2H ₂ O] 15.0 g dissolved in the solution was added dropwise at the same time. Next, 1667 g of a silica solution (which is manufactured by Shokubai Kasei Co., Ltd., having a SiO ₂ content of 30%) is added to the slurry described above. The whole slurry thus obtained is stirred for about 1 hour and then dried by spraying at about 200 ° C. The fine powder thus obtained was a powder having an average diameter of 60 μ. The fine powder was heated to a temperature rising rate of 600 ° C. at 20 ° C./hr and calcined at the same temperature for 10 hours.

The atomic ratio of the composition component of the catalyst thus obtained is Mo: Bi: Co: Fe: Zr: O = 10: 1: 6: 1: 0.25: 39.5 and content of SiO ₂ is 50%.

Thus, 150 ml of the catalyst is charged into a fluidized bed reactor having an inner diameter of 36 mm and a length of 420 mm. The temperature of the reactor is maintained at m440 ° C, and the reaction vessel is mixed at a flow rate of 1927 ml / min so that the molar ratio of propylene, ammonia and air, such as three components, is 1: 1.1: 12. The contact time with the catalyst is 4.68 seconds.

The conversion of propylene, the selectivity to acrylonitrile and the yield of acrylonitrile were 96.2%, 83.9% and 80.7%, respectively.

Example 12

As its all production conditions in Example 11, and just the atom obesity catalyst Sung compound Mo: Bi: Co: Fe: Zr: O = 10: 1: 5: 1: 0.5: The composition of the 40 SiO ₂ 50% A catalyst was prepared to be contained. This catalyst was used to carry out the dark oxidation reaction of propylene in accordance with that described in Example 11.

As a result, the conversion of propylene, the selectivity to acrylonitrile and the yield of acrylonitrile were 97.6%, 84.5% and 82.5%, respectively.

Comparative Example 1

A catalyst was prepared in accordance with that of Example 1 without addition of only zirconyl nitrate. The component atomic ratio of this catalyst is Mo: Bi: Co: Fo: O = 10: 1: 4: 1:37.

This catalyst was used in the same manner as in Example 1 to carry out the propylene amoxidation reaction. The conversion of propylene, selectivity to acrylonitrile and yield of acrylonitrile were 94.5%, 82.1% and 77.6%, respectively.

Comparative Example 2

Only the atomic ratio of each element component constituting the catalyst is set to Mo: Bi: Co: Fe: Zr: O = 3: 1: 4: 1.1: 18, and all other conditions were carried out using the catalyst prepared according to that of Example 1. Amoxidation of propylene is carried out according to the method of Example 1. The conversion of propylene, selectivity to acrylonitrile and yield of acrylonitrile were 92.5%, 70.6% and 70.3%, respectively.

Claims (1)

A propylene or propylene-containing gas and an inert gas selected from nitrogen, carbon dioxide, water vapor, and the like as a reaction gas mixture consisting of ammonia, oxygen, or air, are added in an amount of at least 0.5 mol relative to 1 mole ratio of propylene contained in the reaction mixture gas. (A) molybdenum, (B) bismuth, (C) iron, (D) cobalt and (E) zirconium in carrying out the preparation of acrylonitrile by ammoxidation by contacting the reaction filler gas without addition to the catalyst. A method for producing acrylonitrile by amoxidation of propylene, wherein a catalyst having an atomic ratio represented by the following compositional formula and the aforementioned reaction gas mixture are subjected to a catalytic reaction at a temperature of 300 to 550 ° C. Mo _a Bi Co _b Fe _c Zr _d O _e In the above formula, a, b, c and d are the atomic ratios of the respective elements expressed on the basis of bismuth, a = 1.0-20.0, b = 1.0-10.0, c = 0.2-5.0, d = 0.05-4.0, e is a number between 6 and 86, which meets the valence of each member.