JPH11309374A - Production of molybdenum-containing oxide catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a good catalyst by a method in which raw material compounds are mixed in advance and burned at a temperature in a specified range after being dried, and a small amount of a specified component to activated catalyst precursor, and base substance metal oxide particles is immersed, dried, and burned again. SOLUTION: To base substance metal oxide particles containing molybdenum, bismuth, iron, and silica prepared by burning at a temperature of 450-750 deg.C after drying in advance, a component comprising Mox Biy Fez Aa Bb (wherein Mo is molybdenum: Fe is iron; Bi is bismuth; A is an element selected from the group consisting of chromium, zirconium, lanthanum, and cesium; B is an element selected from the group consisting of phosphorus, boron, tellurium, potassium, and rubidium; (x), (y), (z), (a), and (b) are atomic ratios) is immersed and burned at a temperature of 450-700 deg.C again after being dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a molybdenum-containing oxide catalyst, and more particularly to a method for producing a molybdenum-containing oxide catalyst for producing unsaturated nitrile by ammoxidation.

[0002]

2. Description of the Related Art Molybdenum-containing oxide catalysts are known as catalysts for various organic reactions such as oxidation of organic compounds and ammoxidation. It has been known for a long time that molybdenum-containing oxide catalysts are also used for producing unsaturated nitriles by ammoxidation. For example, molybdenum-bismuth-containing catalysts described in JP-B-36-5870 and JP-B-38-17 are disclosed.
No. 967, a molybdenum / bismuth / iron-containing catalyst described in JP-B-51-33888.
Catalysts containing bismuth, iron, cobalt, nickel, etc.
JP-A-4-118051 in which other components are further diversified
JP, JP-A-7-47271, JP-A-7-28
No. 9901 discloses a catalyst and the like. The methods for producing these catalysts are also described in the above-mentioned patent gazettes, but all of these methods involve mixing and drying and calcining the raw material compounds.

Another method is disclosed in Japanese Patent Application Laid-Open No. 48-132.
No. 90 discloses a method of treating a bismuth / phosphomolybdate catalyst supported on silica with an aqueous solution of an iron salt, followed by drying and calcining. Japanese Patent Application Laid-Open No. 48-13314 discloses a similar method. In addition, Japanese Patent Publication No. 58-5
No. 2696 discloses a catalyst oxide matrix containing cobalt and molybdenum, magnesium and molybdenum, nickel and molybdenum, manganese and molybdenum oxides, or a mixture thereof, containing a compound of bismuth, iron, tellurium alone or a mixture thereof. A method of impregnating a liquid containing a mixture and firing at a high temperature is disclosed. The advantage of this method is that the amount of expensive components such as bismuth can be reduced, and iron, bismuth or tellurium components are not included in the production of the substrate matrix.

As a related technique, a method of impregnating a deteriorated K / Co / Ni / Fe / Bi / P / Mo-containing catalyst with a Bi / Mo component and calcining the catalyst in connection with regeneration of the catalyst (Japanese Patent Publication No. 55-49541) No.), deteriorated Mo ・ Bi ・ P ・
A catalyst containing Fe, Co, Ni, and an alkali metal is impregnated with an aqueous solution of molybdate, dried, and then dried.
There is a proposal of a method of firing at 0 ° C. (Japanese Patent Publication No. 5-33100). However, both of these catalyst production methods and regeneration methods
The operation is remarkably complicated, and the improvement of the catalyst performance corresponding to the operation cannot be guaranteed with good reproducibility.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a high-performance catalyst containing molybdenum, bismuth, iron and silica with good reproducibility.

[0006]

The present inventors have conducted various studies to solve the above-mentioned problems. As a result, the starting compounds were mixed in advance, dried, and then fired at a temperature of 450 to 750 ° C. to activate them. Molybdenum, bismuth, a catalyst precursor containing iron and silica, impregnating a small amount of a specific component to the base metal oxide particles, drying, and calcining again, it was found that an excellent catalyst can be produced, The present invention has been completed.

Although the reason for this is not yet clear, the composition and structure of the catalyst surface layer, which could not be attained by the conventional method of merely mixing, drying and calcining the starting compounds, can be finely adjusted by the method of the present invention. This is considered to be due to the further optimization of the catalyst surface layer. The method of the present invention comprises:
Although the process is somewhat complicated, it is economically advantageous because a high-performance catalyst which could not be obtained by the conventional method can be produced with good reproducibility.

[0008] In other words, the present invention relates to a method of preparing a pre-dried 45
For a base metal oxide particle containing molybdenum, bismuth, iron and silica prepared by calcining at a temperature of 0 to 750 ° C., Mox Biy Fez Aa Bb (where Mo is molybdenum, Fe is iron, Bi is bismuth, A is at least one element selected from the group consisting of chromium, zirconium, lanthanum and cerium, B is phosphorus, boron,
X, y, z, a at least one element selected from the group consisting of tellurium, potassium, rubidium and cesium
And b represent the atomic ratio, and when molybdenum in the base metal oxide particles is 10, x = 0 to 2, y = 0 to 1, z = 0 to 1,
a = 0 to 1, b = 0 to 1, and a + b = 0.1 to 1. The present invention provides a method for producing a molybdenum-containing oxide catalyst, characterized by impregnating a component consisting of) and calcining at 450 to 700 ° C. after drying.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the production of base metal oxide particles used in the present invention, a slurry containing molybdenum, bismuth, an iron raw material compound and silica is prepared, dried and calcined. When producing a fluidized bed catalyst, first, an aqueous slurry containing a raw material compound such as molybdenum, bismuth, iron, etc., for example, ammonium paramolybdate, bismuth nitrate, iron nitrate, etc. and silica sol is prepared. When components other than molybdenum, bismuth, and iron are included, the raw materials for those components are also added. This aqueous slurry is spray-dried and then fired to prepare base metal oxide particles.

In preparing the base metal oxide particles, a catalyst composition having better activity and physical properties can be obtained by adding a chelating agent to the aqueous slurry before spray drying and adjusting the pH to 6 or more. The chelating agent is not particularly limited as long as it has a heavy metal capturing ability, for example, ethylenediaminetetraacetic acid, lactic acid, citric acid, tartaric acid,
Gluconic acid and the like.

When the base metal oxide particles contain iron antimonate, the selectivity of a target product is particularly improved,
In addition, advantages such as improvement in the physical properties of the catalyst are recognized. When producing a catalyst containing iron antimonate, after preparing iron antimonate in advance, this is mixed with the slurry before drying.

The base metal oxide particles in the method of the present invention must themselves have at least a certain level of activity and physical properties. In particular, regarding the physical properties, since the influence on the final catalyst is very large, it is necessary that the final catalyst has almost no problem. For that purpose, the firing conditions in the stage of preparing the base metal oxide particles are extremely important. That is, if the firing temperature is too low, the selectivity deteriorates, and it becomes difficult to improve the performance by the subsequent impregnation operation.If the firing temperature is too high, the reaction rate decreases, physical properties, particularly strength, etc., occur, and the final A good catalyst cannot be obtained, which is not preferable. Baking 450-75
At a temperature of 0 ° C, preferably 500-700 ° C,
The treatment is carried out for 5 to 20 hours, preferably 1 to 10 hours. The calcining method can be selected from conventionally known various methods. In particular, when the catalyst is a fluidized bed catalyst, it is preferable to employ a fluidized calciner capable of more strictly controlling the calcining temperature. In general, firing is conveniently performed in air.

The molybdenum-containing oxide catalyst of the present invention is prepared by applying a solution containing a Mo, Bi, Fe, AB component to the base metal oxide particles prepared in advance as described above. 80 to 110 of pore volume
%, Preferably adjusted to a liquid amount corresponding to 90 to 98%, and the mixture is poured, thoroughly mixed, impregnated, dried and calcined.

As the molybdenum component raw material, ammonium molybdate, peroxomolybdic acid or a salt thereof, molybdenum phosphoric acid, molybdenum silicic acid and the like are used. For the preparation of the impregnating solution, it is convenient to use peroxomolybdic acid or a salt thereof prepared from molybdic acid or a salt thereof and hydrogen peroxide, which form a stable co-solution with many compounds.

As a raw material for the bismuth, iron, chromium, zirconium, lanthanum, and cerium components, nitrates thereof can be used. Phosphoric acid for the phosphorus component raw material, boric acid for the boron component raw material, basic tellurium nitrate in which metallic tellurium is dissolved in nitric acid, and telluric acid in which hydrogen peroxide is dissolved in hydrogen peroxide, potassium, rubidium, and cesium component raw materials The hydroxides and nitrates are preferably used.

As the impregnating component, components other than the above molybdenum, bismuth, iron, A and B, such as lithium, sodium, magnesium, calcium, strontium, barium, yttrium, praseodymium, neodymium, samarium, vanadium, niobium, tantalum, Tungsten, manganese, rhenium, cobalt, nickel,
Ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, zinc, cadmium, aluminum, gallium, indium, thallium, germanium,
Tin, lead, arsenic, antimony, sulfur, selenium, etc. can also be added in small amounts. In preparing the catalyst, these water-soluble salts are used as raw materials and mixed with the impregnating solution for use.

Various methods can be considered for impregnation of the base metal oxide particles with the impregnating liquid and calcination after drying. When the catalyst is a fluidized bed catalyst, the calcination temperature is more strictly controlled in the final calcination. It is preferable to employ a fluidized firing furnace that can be used. Firing is 4
50 to 700 ° C, preferably 500 to 680
C. for 0.5 to 20 hours, preferably 1 to 10 hours. The atmosphere at the time of firing is usually conveniently air, but it is also possible to use those containing nitrogen, carbon dioxide gas, water vapor, etc., or ammonia, organic compounds and the like.

The molybdenum-containing oxide catalyst thus prepared can be used for oxidation, ammoxidation, and oxidative dehydrogenation of various organic compounds. In particular, it is suitably used as a fluidized bed catalyst in the production of unsaturated nitriles such as acrylonitrile and methacrylonitrile by ammoxidation. The reaction conditions in this case are usually the same as the starting organic compound /
Ammonia / air = 1 / 0.9-1.3 / 8-12
(Molar ratio) using a feed gas having a composition range of 35
The reaction pressure is from 0 to 500 ° C. and the reaction pressure is from normal pressure to 500 kPa. The apparent contact time is between 0.1 and 20 seconds.

[0019]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples using ammoxidation of propylene as a reaction example.

Catalyst activity test The catalyst activity tests for the catalysts of the following Examples and Comparative Examples were carried out as follows. Inner diameter of catalyst flow section is 25m
m, a 400-mm-high fluidized bed reactor was charged with the catalyst, and propylene / ammonia / air / steam = 1 / 1.1.2 / 10
/0.5 (molar ratio) mixed gas having a gas linear velocity of 4.
It was fed at 5 cm / sec. The reaction pressure was 200 kPa. Contact time (sec) = catalyst volume based on apparent bulk density (ml)
/ Flow rate of supplied gas converted to reaction conditions (ml / sec) Yield of acrylonitrile (%) = number of moles of acrylonitrile generated / number of moles of supplied propylene x 100 acrylonitrile selectivity (%) = number of moles of acrylonitrile generated / Number of moles of reacted propylene × 100 Conversion rate of propylene (%) = number of moles of reacted propylene / number of moles of supplied propylene × 100 The characteristics and activity test results of the catalysts of Examples and Comparative Examples are shown in Table 1. Was.

Example 1 _Base metal oxide particles having a composition of Mo ₁₀ Bi _0.8 Fe _0.6 Ni _6.5 P _0.2 K _0.7 O _39.5 (SiO 2) ₄₀ (atomic ratio) were prepared as follows. Ammonium paramolybdate 30 in 15.2 kg of pure water
38 g were dissolved and 39.7 g of 85% phosphoric acid was added. (A
Liquid) 3253 g of nickel nitrate, 122 g of potassium nitrate, 200 g of citric acid and 668 g of bismuth nitrate were dissolved in 2160 g of 3.3% nitric acid. (Solution B) While stirring (Solution A), (Solution B) was added, and 20.7 kg of 20% silica sol was further added. Next, 15% aqueous ammonia was added to adjust the pH to 7.7. 100% of this slurry
Heat treatment was performed at reflux for 1.5 hours. (C solution) 200 g of citric acid and 417 g of iron nitrate were dissolved in 2080 g of pure water. To this, 15% aqueous ammonia was added to adjust the pH to 7. (Solution D) (Solution D) was added while stirring (Solution C). This slurry was dried at an inlet temperature of 330 ° C. and an outlet temperature of 160 ° C. by a rotating disk type spray dryer to obtain fine spherical particles. This is 2
Firing was carried out at 50 ° C. for 2 hours, then at 400 ° C. for 2 hours, and finally at 520 ° C. for 3 hours in a fluidized-bed kiln with air flowing. The pore volume of the base metal oxide particles thus prepared was measured by a water titration method and found to be 0.35 ml / g. 1960 g of the base metal oxide particles were taken, and molybdenum, iron, chromium, and zirconium components were added to the molybdenum 10 in the base metal oxide particles.
Impregnation was performed so that r0.05 (atomic ratio) was obtained. That is, the impregnating liquid (described later) was poured in an amount of 659 ml corresponding to 96% of the pore volume and mixed well with a V-type blender. After impregnation, it was placed in a ceramic container, dried in a dryer at 250 ° C. for 2 hours, fired in a box-shaped electric furnace at 400 ° C. for 2 hours, and finally fired in a fluidized-bed kiln at 520 ° C. for 3 hours under air flow. The impregnating solution was prepared as follows. 50% of 31% hydrogen peroxide solution was added to 200% of pure water to dissolve 37.2 g of ammonium paramolybdate. (E
Liquid) 130 g of 63% nitric acid was added to 320 g of pure water, and iron nitrate 1 was added.
7.0, 16.9 g of chromium nitrate and 5.6 g of zirconium oxynitrate were dissolved. (Solution F) While stirring (Solution E), (Solution F) was added to obtain an impregnation liquid.

Example 2 The composition is Mo ₁₀ Bi _0.3 Fe _4.4 Sb _4.2 Cr _0.5 Ni _5.75 Ce _0.2 P _0.5 B _0.3 T
Base metal oxide particles having an e of _0.25 K _0.7 O _54.9 (SiO 2) ₄₀ (atomic ratio) were prepared as follows. Ammonium paramolybdate 15 in 17.2 kg of pure water
35 g were dissolved and 33 g of 85% phosphoric acid was added. (Solution A) 3.3 g 2160 g nitric acid, 2423 g nickel nitrate, 290 g chromium nitrate, 126 g cerium nitrate, 103 g potassium nitrate, 200 g citric acid, 211 g bismuth nitrate
Was dissolved. (Solution B) While stirring (Solution A), (Solution B) was added, and 17.41 kg of 20% silica sol was further added. Then, 15% aqueous ammonia was added to adjust the pH to 7.7. This slurry is
The mixture was heated under reflux at 0 ° C. for 1.5 hours. (Solution C) To 2 kg of pure water, 46 g of metal tellurium powder, 38 g of ammonium paramolybdate, and 160 g of 31% hydrogen peroxide solution were added and dissolved at 90 to 95 ° C. Cool it to room temperature,
200 g of citric acid and 351 g of iron nitrate were dissolved. 15%
Aqueous ammonia was added to adjust the pH to 9.15. 985 g of ammonium paramolybdate was added little by little to dissolve, and the pH was adjusted to 7. (Solution D) While stirring (Solution C), (Solution D) was added, and 1411 g of iron antimonate containing a small amount of phosphorus and boron was further added.
The slurry thus prepared was spray-dried in the same manner as in Example 1 to obtain fine particles. This is fired at 250 ° C. for 2 hours, further at 400 ° C. for 2 hours, and finally at 590 ° C., 3
It was fluid calcined under flowing air for hours. The pore volume of the base metal oxide particles was measured by a water titration method.
It was 3 ml / g. 1962 g of the base metal oxide particles were taken, and an impregnating liquid containing molybdenum, bismuth, chromium, cerium and phosphorus components was applied to molybdenum 10 in the base metal oxide particles using Mo0.5Bi0.05Cr0.1Ce0.05P0.1 (atomic (Ratio). That is, 433 ml of an impregnating liquid (described later) corresponding to 96% of the pore volume was poured in, and mixed well with a V-type blender. This was carried out in the same manner as
After drying at 2 ° C. for 2 hours, it was calcined at 400 ° C. for 2 hours, and finally fluidized at 590 ° C. for 3 hours under flowing air. The impregnating liquid was prepared as follows. 50% of 31% hydrogen peroxide solution was added to 200 g of pure water, 31.5 g of ammonium paramolybdate was dissolved, and 4.1 g of 85% phosphoric acid was added. (Solution A) 130 g of 63% nitric acid was added to 120 g of pure water, 8.6% of bismuth nitrate, 14.3 g of chromium nitrate, and cerium nitrate 7.
7 g were dissolved. (Solution B) While stirring (Solution A), (Solution B) was added to obtain an impregnation liquid.

Examples 3 to 5 The same base metal oxide particles as in Example 1 were used, impregnated with the components shown in Table 1, dried and fired.

Examples 6 to 10 The same base metal oxide particles as in Example 2 were used, each impregnated with the components shown in Table 1, dried and fired.

Comparative Example 1 The base metal oxide particles of Example 1 were directly used as a catalyst.

Comparative Example 2 A catalyst was prepared in the same manner as in Example 1 except that the calcination of the base metal oxide particles was changed to 400 ° C.

Comparative Example 3 A catalyst was prepared in the same manner as in Example 9, except that a large amount of component A, chromium and zirconium, was added.

Comparative Example 4 A catalyst was prepared in the same manner as in Example 9 except that neither component A nor component B was added.

The catalysts of Examples and Comparative Examples were subjected to the above-mentioned catalytic activity test, and the results are shown in Table 1.

[Table 1]

[0030]

The molybdenum-containing oxide catalyst prepared by the method of the present invention has particularly high target compound selectivity, and is useful, for example, for producing acrylonitrile by ammoxidation of propylene.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C07C 255/08 C07C 255/08

Claims (4)

[Claims] 1. 450-750 ° C. after drying in advance
Against the base metal oxide particles containing molybdenum, bismuth, iron and silica prepared by firing at a temperature of MoBy Fez Aa Bb (where Mo is molybdenum, Fe is iron, Bi is bismuth, A is chromium, B is at least one element selected from the group consisting of zirconium, lanthanum and cerium, and B is at least one element selected from the group consisting of phosphorus, boron, tellurium, potassium, rubidium and cesium, x, y, z, a And b represent an atomic ratio, and when molybdenum in the base metal oxide particles is 10, x = 0 to 2, y = 0 to 1, z = 0 to 1, a = 0 to 1, and b = 0.
11 and a + b = 0.1 11. ) Impregnated with the component consisting of
A method for producing a molybdenum-containing oxide catalyst, which is dried and then calcined at a temperature of 450 to 700 ° C. 2. The method for producing a molybdenum-containing oxide catalyst according to claim 1, wherein the base metal oxide particles contain iron antimonate. 3. The base metal oxide particles are prepared by spray-drying an aqueous slurry containing at least molybdenum, bismuth and iron raw material components and a chelating agent and having a pH adjusted to 6 or more, followed by firing. The method for producing a molybdenum-containing oxide catalyst according to claim 1 or 2, wherein 4. The method for producing a molybdenum-containing oxide catalyst according to claim 1, wherein the molybdenum-containing oxide catalyst has a catalyst composition represented by the following empirical formula. Mo10 Bia Feb Sbc Dd Ee Ff Gg Hh Oi (SiO2) j (wherein Mo, Bi, Fe and Sb represent molybdenum, bismuth, iron and antimony, respectively, and D is magnesium, calcium, strontium, barium, chromium and manganese. , Cobalt, nickel and at least one element selected from the group consisting of zinc, E is copper, silver, cadmium, aluminum, gallium, indium, germanium,
At least one element selected from the group consisting of tin, lead, titanium, zirconium and hafnium; F is vanadium, niobium, tantalum, tungsten, yttrium,
Lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, thorium, uranium,
R is at least one element selected from the group consisting of rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, and gold; G is at least one element selected from the group consisting of phosphorus, boron, and tellurium; and H is lithium. , Sodium, potassium, rubidium and at least one element selected from the group consisting of cesium, O is oxygen, Si is silicon, subscripts a, b, c, d, e, f, g, h
, I and j indicate the atomic ratio, and when Mo = 10, a = 0.1 to 5
, B = 0.1-15, c = 0-20, d = 0-10, e = 0-10, f = 0
1010, g = 0 5, h = 0 3, i = the number of oxygen corresponding to the oxide formed by combining the above components, and j = 2020150. )