JPH07223812A - Production of hydrogen cyanide - Google Patents

Abstract

PURPOSE:To produce hydrogen cyanide in a high yield while keeping high catalytic activity even by using a small amount of ammonia or oxygen relative to methanol by reacting a gaseous mixture containing methanol, ammonia and oxygen in the presence of a specific oxide catalyst. CONSTITUTION:Hydrogen cyanide is produced by reacting a gaseous mixture containing methanol, ammonia and oxygen in the presence of a catalyst consisting of an oxide catalyst containing active components having a composition expressed by the experimental formula and produced by baking at the final baking temperature of 700-900 deg.C). In the formula, Q is P, Sb, Bi, Te, B or Nb; R is Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, etc.; (a), (b), (c), (d) and (e) are atomic ratios and (b) is 1.0-3.0, (c) is 0.01-0.3 and (d) is 0-1.0 when (a) is 1; (e) is a number corresponding to the oxide produced by bonding the above components.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing hydrogen cyanide by reacting methanol, ammonia and oxygen in the presence of a catalyst. Hydrogen cyanide is a substance widely used industrially as a raw material for various organic syntheses.

[0002]

BACKGROUND ART Hydrogen cyanide has been produced by decomposing formamide, ammoxidation of methane, etc., but in recent years, a route as a by-product at the time of acrylonitrile production by ammoxidation of propylene has become the main route. However, with the progress of acrylonitrile synthesis catalysts, the amount of hydrogen cyanide by-product has decreased and, for example, a situation has arisen where it is difficult to secure quantitative quantity as a methyl methacrylate raw material by the acetone cyanohydrin method. Also, hydrogen cyanide cannot be transported due to the dangers associated with its toxicity. Therefore, it must be used in a process that is consumed simultaneously with manufacturing.

The significance of the present invention is that when it becomes difficult to secure the amount of hydrogen cyanide to be supplied to the auxiliary acetone cyanohydrin device due to catalyst conversion or the like in the existing acrylonitrile production apparatus, or hydrogen cyanide to be supplied to various hydrogen cyanide derivative production facilities. It is to provide an advantageous method in the case of manufacturing Although methanol has been recently discussed as a fuel, the present invention is a particularly advantageous method when such inexpensive methanol is available.

Various methods have been proposed for producing hydrogen cyanide by the ammoxidation method of methanol, but a method using an oxide containing molybdenum as a catalyst is disclosed in, for example, Japanese Patent Publication No. 51-35400. A method using a catalyst, a method using an iron / molybdenum oxide catalyst described in Japanese Patent Publication No. 60-44294, a method using an oxide catalyst containing molybdenum / bismuth / iron described in Japanese Patent Publication No. 61-4771. A method using an iron / molybdenum oxide catalyst described in JP-A-59-87407 and a method using a catalyst in which molybdenum oxide and iron oxide are supported on activated alumina described in JP-B-60-42187 are known.

[0005]

However, these conventional methods are not always satisfactory in practical use. That is, the amount of ammonia used must be excessive with respect to methanol, the yield of hydrogen cyanide decreases unless a large amount of water vapor is used, the concentration of methanol in the reaction gas is low, and the space-time yield is low. There have been many problems to be improved in that the change with time of the catalyst is large and the strength of the catalyst is insufficient. The present invention is a molybdenum-containing oxide catalyst different from these and has been made to improve the above problems, and an object thereof is to provide a method for producing hydrogen cyanide which can be practically carried out advantageously. Specifically, the activity of the catalyst is good even when the amount of ammonia or oxygen used with respect to methanol is low, a high hydrogen cyanide yield can be obtained, and in addition, physical properties (catalyst strength, etc.) can be obtained even in a long-term reaction,
It is an object of the present invention to provide a method for producing hydrogen cyanide which is stable in both activities.

[0006]

That is, in the present invention, when hydrogen cyanide is produced by reacting a gaseous mixture containing methanol, ammonia and oxygen in the presence of a catalyst, the composition of the active ingredient of the catalyst is empirical formula: Mo _a Fe _b Q _C R _d O _e (wherein Q is at least one element selected from the group consisting of P, Sb, Bi, Te, B and Nb, R is Li,
Na, K, Rb, Cs, Be, Mg, Ca, Sr, B
a, Sc, Y, La, Ce, Pr, Nd, Sm, Th,
U, Ti, Zr, V, Hf, Ta, Cr, W, Mn, R
e, Co, Ni, Ru, Rh, Pd, Os, Ir, P
t, Cu, Ag, Au, Zn, Cd, Hg, Al, G
at least one element selected from the group consisting of a, In, Tl, Ge, Sn, Pb, and Se, with the subscript a,
b, c, d and e represent atomic ratios, and when a = 1, b
= 1.0 to 3.0, c = 0.01 to 0.3, d = 0
1.0 and e = numbers corresponding to oxides formed by combining the above components, respectively. ) And finally using an oxide catalyst produced by calcining at a temperature of 700 to 900 ° C., and to a method for producing hydrogen cyanide.

The present invention will be described in detail below. The catalyst used in the present invention is an oxide composition containing Mo and Fe, and at least one element selected from the group consisting of P, Sb, Bi, Te, B and Nb as Q components as essential components. Specifically, when the composition ratio of the catalyst is atomic ratio Mo = 1, Fe = 1.0 to 3.0, preferably 1.5 to 2.5, Q component = 0.01 to 0.
3, preferably in the range of 0.03 to 0.2. If the Fe component is out of this range, the yield of hydrogen cyanide decreases. The Q component affects the activity of this catalyst and the selectivity of hydrogen cyanide. When the Q component is out of this range, the complete oxidation activity increases and the hydrogen cyanide yield decreases.

The above composition further contains Li, Na, K, Rb, Cs, Be, Mg, Ca and S as R components.
r, Ba, Sc, Y, La, Ce, Pr, Nd, Sm,
Th, U, Ti, Zr, V, Hf, Ta, Cr, W, M
n, Re, Co, Ni, Ru, Rh, Pd, Os, I
r, Pt, Cu, Ag, Au, Zn, Cd, Hg, A
1, Ga, In, Tl, Ge, Sn, Pb and Se, at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, La, Ce and T.
i, Zr, V, Ta, Cr, W, Mn, Co, Ni, C
By adding at least one element selected from the group consisting of u, Zn, Al, Sn and Pb, the physical properties of the catalyst, the reaction rate, etc. can be adjusted. The addition amount of the R component is 1 or less, preferably 0.1 to 0.5, with respect to Mo = 1 in terms of atomic ratio.

In preparing the above-mentioned catalyst, the starting material for each component constituting the catalyst can be selected from many kinds such as oxides, hydroxides, chlorides, nitrates and organic acid salts. . As the Mo component, molybdenum trioxide, molybdic acid, ammonium paramolybdate,
Ammonium metamolybdate, molybdenum halides and the like can be used. As the Fe component, metallic iron, ferrous oxide, ferric oxide, iron nitrate, iron chloride, iron acetate, iron oxalate, and ammonium oxalate can be used. As the other Q component and R component, oxides, hydroxides, chlorides, nitrates, carbonates and organic acid salts of the respective elements can be used.

The catalyst according to the present invention can be used without a carrier, but can also be used by being carried on a carrier. In this case, the carrier is preferably used in the range of about 10 to 90% by weight based on the total weight of the catalyst. Examples of the carrier include silica, alumina, titania, zirconia and the like. When silica is used as the carrier, it is convenient to use silica sol as a starting material.

The catalyst used in the present invention can be prepared by any method known in the art of this type, provided that it is prepared to have the catalyst composition described above. For example, in the case of producing a fixed bed catalyst, a slurry prepared from each of the above-mentioned components is dried or dried and fired, and then molded by a method such as tablet molding or extrusion molding. When producing a catalyst for a fluidized bed, it is preferable to spray-dry the above slurry and mold it into fine spherical particles. For spray-drying the slurry, an ordinary spray-drying device such as a pressure nozzle type or a rotating disk type can be optionally used. The concentration of the slurry subjected to spray drying is preferably in the range of about 10 to about 40% by weight in terms of the oxide of the elements constituting the catalyst. It is preferable to appropriately adjust the concentration of the slurry and the spray-drying conditions to carry out spray-drying so as to obtain particles having a desired particle size distribution.

The catalyst thus produced finally exhibits preferable activity by calcining at a temperature of 700 to 900 ° C. for 0.5 to 20 hours. If the calcination temperature is lower than 700 ° C, the activity of the catalyst is not sufficient.
At higher temperatures, especially in the case of a fluidized bed catalyst, the adhesion of catalyst particles increases, making uniform calcination difficult. Further, it is preferable to carry out preliminary firing at a temperature of 250 to 500 ° C. prior to firing.

The raw material methanol in the method of the present invention may be not only pure but also crude methanol containing some impurities. Air is preferably used as the oxygen source for economic reasons, but it may be used after diluting it with an inert gas such as nitrogen or steam, or by enriching it with oxygen.

The reaction of the present invention can be carried out in a fixed bed or a fluidized bed. Concentration of methanol in feed gas is 1-2
It can be changed in the range of 0% by volume. The oxygen / methanol ratio in the feed gas is 1-20, preferably 1-10, and the ammonia / methanol ratio is 0.5-3, preferably 0.7-.
It can be changed in the range of 2. Even if the reaction is carried out at an ammonia / methanol ratio of 3 or more, there is no negative effect on the yield of hydrogen cyanide, but if the reaction is carried out below this, a sufficient yield can be obtained, which is not necessary. Reaction temperature is 300-60
The reaction is preferably carried out at 0 ° C. for a contact time of 0.1 to 20 seconds and at a reaction pressure of atmospheric pressure to about 2 Kg / cm ² G. The hydrogen cyanide formed can be recovered using any method known in the art of this type. In addition, this catalyst is also useful for ammoxidation of methyl formate, formaldehyde, dimethyl ether, methylal, etc.
It is also possible to react them in the presence of methanol.

[0015]

The embodiments and effects of the present invention will be specifically described below with reference to Examples and Comparative Examples.

Example 1 The empirical formula is Mo ₁ Fe ₂ Sb _0.2 O _6.4 (SiO ₂ ) ₆
Was prepared as follows. Pure water 1
After dissolving 516 g of iron (III) nitrate nonahydrate in 040 g, 1123 g of silica sol (SiO ₂ 20.4%) and 18.6 g of antimony trioxide powder are added. Further, 112 g of ammonium paramolybdate was added to pure water 67
A solution dissolved in 3 g is added. Next, this is heated while stirring to prepare a catalyst slurry. This catalyst slurry is spray dried according to a conventional method. 4 spray dried products
Final firing was carried out at 00 ° C for 2 hours and then at 750 ° C for 3 hours.

Example 2 The empirical formula is Mo ₁ Fe _2.5 Bi _0.05 O _6.8 (SiO ₂ ).
A fluidized bed catalyst of ₁₂ was prepared in the same manner as in Example 1. However, bismuth nitrate was used as the raw material for the Bi component, and the final firing was performed at 850 ° C. for 3 hours.

Example 3 The empirical formula is Mo ₁ Fe _1.5 Te _0.2 Zn _0.3 O _6.0 (S
A fluidized bed catalyst of iO ₂ ) ₈ was prepared in the same manner as in Example 1. However, as the raw material of the Te component, telluric acid,
Zinc nitrate was used as the raw material for the Zn component, and the final firing was 70
It was 5 hours at 0 ° C.

Example 4 A catalyst for fluidized bed having an empirical formula of Mo ₁ Fe ₂ P _0.1 O _6.3 (SiO ₂ ) ₁₀ was prepared in the same manner as in Example 1.
However, 85% orthophosphoric acid was used as the raw material of the P component, and the final firing was performed at 800 ° C. for 3 hours.

Example 5 The empirical formula is Mo ₁ Fe _2.5 B _0.1 Nb _0.05 K _0.1 O _7.1
A (SiO ₂ ) ₈ fluidized bed catalyst was prepared in the same manner as in Example 1. However, orthoboric acid was used as the raw material of the B component, niobium oxalate was used as the raw material of the Nb component, potassium nitrate was used as the raw material of the K component, and the final firing was at 800 ° C. for 4 hours.

Comparative Example 1 The empirical formula is Mo ₁ Fe _0.5 Sb _0.2 O _4.2 (SiO ₂ ).
A fluidized bed catalyst of ₆ was prepared in the same manner as in Example 1.

Comparative Example 2 The empirical formula is Mo ₁ Fe ₄ Sb _0.2 O _9.4 (SiO ₂ ) ₆
Was prepared in the same manner as in Example 1.

Comparative Example 3 A fluidized bed catalyst having an empirical formula of Mo ₁ Fe _1.5 O _5.3 (SiO ₂ ) ₈ was prepared in the same manner as in Example 1. However, the final firing was performed at 700 ° C. for 5 hours.

Comparative Examples 4 to 5 Catalysts having the same composition as in Example 4 were prepared. However, the final firing was performed at 600 ° C. for 4 hours or 950 ° C. for 2 hours.

Comparative Example 6 The empirical formula is Mo ₁ Fe _0.8 B _0.3 P _0.08 Pb _0.04 O _4.9
A (SiO ₂ ) ₄ fluidized bed catalyst was prepared in the same manner as in Example 1. However, orthoboric acid was used as the raw material of the B component, 85% orthophosphoric acid was used as the raw material of the P component, lead nitrate was used as the raw material of the Pb component, and the final firing was performed at 550 ° C.
It was time.

Comparative Example 7 The empirical formula is Mo ₁ Fe _0.08 Bi _0.08 P _0.007 Ni _0.3 C
A catalyst for fluidized bed of _0.3 Rb _0.08 Tl _0.04 O _4.1 (SiO ₂ ) _1.3 was prepared in the same manner as in Example 1. However, bismuth nitrate as a raw material of Bi component, 85% orthophosphoric acid as a raw material of P component, nickel nitrate as a raw material of Ni component, cobalt nitrate as a raw material of Co component, rubidium nitrate as a raw material of Rb component, nitric acid as a raw material of Tl component. Using thallium, the final firing was at 525 ° C. for 6 hours.

The activity of each catalyst prepared in the above Examples and Comparative Examples is shown in Table 1 together with the catalyst composition, activity test conditions and the like.
Shown in. In the catalyst activity test, a fluidized bed reactor having an inner diameter of a catalyst fluidized portion of 2.5 cm and a height of 40 cm was filled with the catalyst, and a gas having the following composition was fed. The reaction pressure is normal pressure. Oxygen (supplied as air) / methanol molar ratio = 1.2 Ammonia / methanol molar ratio = 1.0

The methanol conversion, hydrogen cyanide yield and selectivity are defined by the following equations.

[0029]

[Table 1]

[0030]

EFFECTS OF THE INVENTION The catalyst according to the present invention exhibits excellent performance in the production of hydrogen cyanide by the vapor phase ammoxidation reaction of methanol, and produces hydrogen cyanide in a high yield even under the condition that the concentration of methanol in the reaction gas is 10% by volume or more. In addition, the physical properties (catalyst strength, etc.) and activity are stable even in the reaction for a long time.

Claims (2)

[Claims] 1. When producing a hydrogen cyanide by reacting a gaseous mixture containing methanol, ammonia and oxygen in the presence of a catalyst, the composition of the active ingredient of the catalyst is empirical formula: Mo _a Fe _b Q _C R _d O _e ( In the formula, Q is at least one element selected from the group consisting of P, Sb, Bi, Te, B and Nb, and R is Li,
Na, K, Rb, Cs, Be, Mg, Ca, Sr, B
a, Sc, Y, La, Ce, Pr, Nd, Sm, Th,
U, Ti, Zr, V, Hf, Ta, Cr, W, Mn, R
e, Co, Ni, Ru, Rh, Pd, Os, Ir, P
t, Cu, Ag, Au, Zn, Cd, Hg, Al, G
at least one element selected from the group consisting of a, In, Tl, Ge, Sn, Pb, and Se, with the subscript a,
b, c, d and e represent atomic ratios, and when a = 1, b
= 1.0 to 3.0, c = 0.01 to 0.3, d = 0
1.0 and e = numbers corresponding to oxides formed by combining the above components, respectively. ) And finally using an oxide catalyst produced by calcining at a temperature of 700 to 900 ° C., a method for producing hydrogen cyanide. 2. The method for producing hydrogen cyanide according to claim 1, wherein the concentration of methanol in the gaseous mixture is 10 to 20% by volume.