JP3796132B2 - Preparation of composite oxide catalyst for gas phase ammoxidation reaction - Google Patents

Description

【００４０】
【発明の効果】
本発明の方法により調製される気相アンモ酸化反応用複合酸化物触媒は高活性で、且つ高い収率で目的生成物を与えることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preparing a composite oxide catalyst used in a gas phase ammoxidation reaction of an organic compound, and more specifically, molybdenum-bismuth-iron antimolybdenum used in a gas phase ammoxidation reaction of an olefin, alcohol, aromatic compound, heterocyclic compound, or the like. The present invention relates to a method for preparing a nate-containing composite oxide catalyst.
[0002]
[Prior art]
Various molybdenum-bismuth-iron antimonate-containing composite oxide catalysts have been proposed as catalysts for vapor phase ammoxidation reactions of organic compounds. For example, Japanese Patent No. 3142549 discloses a metal oxide catalyst in which iron antimonate having a crystallite size of 20 nm or more exists as a crystal phase in the catalyst, and Japanese Patent Laid-Open No. 2000-5603 discloses iron oxide in the catalyst. Metal oxide catalysts containing antimonates are disclosed. In these catalysts containing iron antimonate, improvement in the yield of the target product and improvement in the physical properties of the catalyst have been recognized. On the other hand, in the reaction targeting commodity chemicals such as gas phase oxidation reaction and gas phase ammoxidation reaction, the yield of the target product can be as low as 1% as disclosed in Japanese Patent Publication No. 58-8895. Since the improvement can produce a surprising economic effect commercially, research efforts such as catalyst improvement are constantly being made.
[0003]
[Problems to be solved by the invention]
However, the catalyst in the prior art has not been sufficient in terms of the yield of the gas phase ammoxidation reaction. The present invention relates to a molybdenum-bismuth-iron antimonate-containing composite oxide catalyst particularly useful for gas phase ammoxidation reactions such as olefins, alcohols, aromatic compounds, and heterocyclic compounds, and is a highly active and objective nitrile compound. Is provided in a high yield.
[0004]
[Means for solving problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a catalyst selected from molybdenum, bismuth, iron, magnesium and the like, iron antimonate, and silicon as essential components, at least molybdenum. The present invention has been found by adding a step of heat-treating a slurry containing bismuth, iron antimonate, and silicon in a specific temperature range to obtain a catalyst having high activity and a high yield of a nitrile compound.
[0005]
That is, the present invention provides (1) molybdenum, (2) bismuth, (3) iron, (4) cerium, magnesium, chromium, manganese, cobalt, nickel, and at least one element selected from the group consisting of zinc, (5) In the method for preparing a complex oxide catalyst for gas phase ammoxidation reaction containing iron antimonate and (6) silicon as an essential component, at least (1), (2), (5) of the essential components And a method for preparing a composite oxide catalyst for gas phase ammoxidation reaction, comprising a step of heat-treating the slurry containing (6) at a temperature in the range of 50 to 120 ° C.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, although it is not clear about the mechanism in which high activity and high selectivity are manifested, the slurry containing iron antimonate particles is heat-treated at a temperature in the range of 50 to 120 ° C., whereby molybdenum, It is considered that the reason is that a preferable catalyst precursor containing bismuth, silicon and iron antimonate is formed, and that a preferable dispersion state of iron antimonate particles is obtained.
[0007]
The catalyst to which the present invention is applied includes a group consisting of (1) molybdenum, (2) bismuth, (3) iron, (4) cerium, magnesium, calcium, chromium, manganese, cobalt, nickel, and zinc as essential components. The catalyst may be a composite oxide catalyst containing at least one element selected from (5) iron antimonate and (6) silicon, and a catalyst having a composition represented by the following general formula is preferably used.
MoaBibFecSbdHeLfMgNhXiYjSikOx
Here, Mo, Bi, Fe, Sb, Si and O represent molybdenum, bismuth, iron, antimony, silicon and oxygen, respectively, H is cerium, magnesium, calcium, strontium, barium, chromium, manganese, cobalt, At least one element selected from the group consisting of nickel, copper, zinc and cadmium, L is at least one element selected from the group consisting of yttrium, lanthanum, praseodymium, neodymium, samarium, aluminum, gallium and indium, M is At least one element selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, tungsten, germanium, tin and lead, N is from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and silver Chosen At least one element, X is at least one element selected from the group consisting of phosphorus, boron, arsenic, thallium and tellurium, Y is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium and cesium Represents. The subscripts a, b, c, d, e, f, g, h, i, j, k, and x represent the atomic ratio of each element. When a = 10, b = 0.1 to 1.5. , Preferably 0.3-1.2, c = 0.5-6.0, preferably 0.6-5.5, d = 0.5-5.5, preferably 0.6-5.0 E = 3-10, preferably 5-8, f = 0-2, preferably 0-1.5, g = 0-3, preferably 0-2, h = 0-1, preferably 0-0. 0.5, i = 0-3, preferably 0-2, j = 0.05-1.5, preferably 0.1-1.0, k = 20-200, and x is an atom of each component. This is the number of oxygen atoms necessary to satisfy the valence.
[0008]
In the present invention, it is essential to contain iron antimonate, and the object of the present invention is achieved particularly well when it is in the composition range. Iron antimonate is a compound represented by the chemical formula FeSbO4 described in Japanese Patent No. 3142549 and Japanese Patent Laid-Open No. 10-231125, and its presence can be confirmed by X-ray diffraction of the catalyst.
[0009]
Various methods for preparing iron antimonate have been proposed. For example, there are methods described in Japanese Patent No. 3142549, Japanese Patent Laid-Open No. 10-231125, etc., and these methods may be appropriately selected and used. In the production of the catalyst of the present invention, it is important that iron antimonate is prepared in advance by these methods and then mixed with other catalyst component raw materials. At this time, it is possible to obtain a more preferable effect by adding iron antimonate prepared in advance to a slurry containing part or all of other components adjusted to pH 1.5 or more. The presence of iron antimonate contributes to improved acrylonitrile selectivity and improved physical properties as a fluidized bed catalyst.
[0010]
The starting material for each component element of the catalyst used in the present invention is not particularly limited. For example, the starting material for the molybdenum component includes molybdenum oxide such as molybdenum trioxide, molybdic acid, ammonium paramolybdate, and meta. A molybdic acid such as ammonium molybdate or a salt thereof, a heteropoly acid containing molybdenum such as phosphomolybdic acid or silicomolybdic acid, or a salt thereof can be used.
[0011]
As raw materials for the bismuth component, bismuth salts such as bismuth nitrate, bismuth carbonate, bismuth sulfate, bismuth acetate, bismuth trioxide, metal bismuth, and the like can be used. These raw materials can be used in the form of a solid or as an aqueous solution, an aqueous nitric acid solution, or a slurry of a bismuth compound generated from the aqueous solution, but it is preferable to use nitrate, a solution thereof, or a slurry generated from the solution.
[0012]
Ferrous oxide, ferric oxide, ferric tetroxide, ferrous nitrate, ferric nitrate, ferrous sulfate, iron chloride, iron organic acid salt, iron hydroxide, etc. can be used as raw materials for iron components In addition, metallic iron may be dissolved in heated nitric acid.
[0013]
Silica sol, fumed silica or the like is used as a raw material of silicon, and silica sol is particularly preferable.
[0014]
As raw materials for other elements, usually oxides, nitrates, carbonates, organic acid salts, hydroxides and the like, which can be converted into oxides by igniting, or a mixture thereof are used.
[0015]
The catalyst according to the present invention is prepared by mixing catalyst raw materials, spray drying, and calcining. A catalyst or solution containing at least a molybdenum component raw material, a bismuth component raw material, iron antimonate, and a silicon component raw material is prepared. The catalyst slurry is prepared by adding a step of heat treatment in the temperature range of 50 to 120 ° C. At this time, it is preferable to adjust the pH of the slurry to about 1 to 8. When manufacturing by preparing a relatively high pH of 3-8, chelating agents such as ethylenediaminetetraacetic acid, lactic acid, citric acid, tartaric acid, glucone are prepared in accordance with the method described in Japanese Patent No. 2747920 for the purpose of suppressing the gelation of the slurry. It is preferable to coexist an acid. Further, when the pH is relatively low and less than 3, coexistence of a chelating agent is not necessarily required, but good results may be obtained by adding a small amount.
[0016]
In the method of the present invention, the catalyst component is at least one selected from the group consisting of (1) molybdenum, (2) bismuth, (3) iron, (4) cerium, magnesium, chromium, manganese, cobalt, nickel, and zinc. In the method for preparing a composite oxide catalyst for gas phase ammoxidation reaction containing (5) iron antimonate and (6) silicon as an essential component, at least (1), (2), ( Although the process which heat-processes the slurry containing 5) and (6) in the temperature range of 50-120 degreeC is required, Preferably it is good to heat-process in the temperature range of 60-110 degreeC. Moreover, although heating time is not specifically limited, In order to express a sufficient effect, 10 minutes or more are preferable, Especially preferably, it is the heat processing for about 30 minutes-12 hours. Further, there is no problem even if the heating time is over 24 hours, but the effect is not increased. By such heat treatment, the properties of the slurry can be stabilized, and the yield of the nitrile compound of the catalyst finally obtained can be improved.
[0017]
The resulting catalyst slurry is usually spray dried. The spray drying device may be a general device such as a rotary disk type or a nozzle type. The conditions are adjusted so that a catalyst having a preferable particle size as a fluidized bed catalyst can be obtained.
[0018]
The catalyst drying thus obtained is usually used after calcination. A box furnace, tunnel furnace, rotary furnace, fluidized furnace, or the like is used for firing. The firing temperature is 400 to 800 ° C, preferably 500 to 700 ° C. When calcination is performed at a temperature outside this range, a high-performance catalyst may not be obtained. The firing time is not particularly limited. However, if the firing time is too short, a high-performance catalyst may not be obtained. The firing atmosphere is preferably an oxygen-containing gas. Although it is convenient to carry out in the air, oxygen and nitrogen, carbon dioxide and / or water vapor can be mixed and used.
[0019]
The particle size of the fluidized bed catalyst thus produced is preferably 5 to 200 μm.
[0020]
The catalyst obtained by the present invention maintains high activity over a long period of time by applying it to a gas phase ammoxidation reaction of olefin, alcohol, aromatic compound, heterocyclic compound, etc. Give in. Examples of olefins include propylene and isobutylene; alcohols such as methanol, ethanol and tertiary butanol; aromatic compounds such as toluene and xylene; and heterocyclic compounds such as picoline, quinaldine and methylthiophene. In particular, it is preferably used for the production of acrylonitrile from propylene, methacrylonitrile from isobutylene or tertiary butanol, and hydrocyanic acid from methanol.
[0021]
The ammoxidation reaction using the catalyst obtained by the present invention can be carried out by arbitrarily selecting from a conventionally known reaction condition range. For example, the reaction temperature is 370 to 500 ° C. using a feed gas having a composition range of hydrocarbons such as olefins: ammonia: oxygen 1: 0.9 to 1.3: 1.6 to 2.5 (molar ratio). The pressure is from normal pressure to 500 kPa. Apparent contact time is 0.1 to 20 seconds. As the oxygen source, it is convenient to use air. However, it may be diluted with water vapor, nitrogen, carbon dioxide, saturated hydrocarbon or the like, or enriched with oxygen.
[0022]
However, when the fluidized bed catalyst of the present invention, which is stable in terms of catalyst structure, continues to react, a decrease in the yield of the ammoxidation product due to escape of the molybdenum component is observed. The reaction temperature of the ammoxidation reaction using this type of fluidized bed catalyst exceeds 400 ° C., and it is considered that escape of the molybdenum component during the reaction is unavoidable. As a method for maintaining the performance for a long time in the reaction use of such a fluidized bed catalyst, as disclosed in Japanese Patent Publication No. 58-57422, DE 3,311,521C2, WO 97/33863, etc. A method of adding a molybdenum component during the reaction is known. Also in the present invention, in order to maintain a high ammoxidation product yield for a long period of time, it is preferable to react while adding a molybdenum component.
[0023]
Examples of the molybdenum component used here include metal molybdenum, molybdenum trioxide, molybdic acid, ammonium dimolybdate, ammonium paramolybdate, ammonium octamolybdate, ammonium dodecamolybdate, and phosphomolybdic acid. Although it can be used in a gas or liquid state, it is practical to use these molybdenum components in a solid state. Further, these molybdenum components may be supported on an inert substance or supported on a catalyst. In particular, a method using a molybdenum component enriched in a catalyst is effective. This method is a preferred mode of use because the use efficiency of the added molybdenum is good and troubles due to precipitation of molybdenum oxide in the system are suppressed. As a method for producing the molybdenum-enriched catalyst, the method described in JP-A-11-33400 can be applied.
[0024]
These molybdenum components are added to the reactor continuously or intermittently. The addition timing and addition amount may be appropriately determined depending on the transition of reaction results, but the amount added at a time is preferably in the range of 0.05 to 2% by mass with respect to the packed catalyst. Even if a large amount is added at one time, care must be taken because it escapes to the outside of the reaction system and is consumed unnecessarily and deposits and accumulates in the reactor.
[0025]
【Example】
Hereinafter, the effect of the present invention will be shown by examples. The catalyst activity test was carried out as follows using a propylene ammoxidation reaction as a representative example.
The catalyst was packed into a fluidized bed reactor having an inner diameter of 25 mmφ and a height of 400 mm so as to have a predetermined contact time, and the molar ratio of propylene: ammonia: air: water was 1: 1.2: 9.5 in this reactor. : A mixed gas of propylene, ammonia, air and water vapor of 0.5 was supplied at a gas linear velocity of 4.5 cm / s. The reaction pressure was maintained at 200 kPa and the reaction temperature was 440 ° C. In addition, the molybdenum rich catalyst was added suitably at the time of reaction. The addition amount was 0.1 to 0.2% by mass as molybdenum with respect to the packed catalyst at intervals of 100 to 500 hours.
[0026]
The yield of the ammoxidation product (acrylonitrile) and the conversion rate of the starting organic compound (propylene) in the examples are defined by the following formula.
Acrylonitrile yield (%) = (carbon mass of produced acrylonitrile) / (carbon mass of supplied propylene) × 100
Propylene conversion rate (%) = (carbon mass of propylene consumed) / (carbon mass of propylene supplied) × 100
Table 1 shows catalyst compositions, activity test conditions, activity test results, pH at the time of addition of iron antimonate slurry, and the like in Examples and Comparative Examples.
[0027]
Example 1
The composition is Mo10Bi0.5Fe5.1Sb4.2Ni4.0Cr0.8Ce0.3Co2.0K0.2P0.2B0.2Si35-Ox (because x is a value naturally determined by the valence of other elements, description of oxygen is omitted below) Was prepared by the following method.
Separately prepared 894.9 g of 20% iron antimonate slurry was added to 1982.5 g of 20% silica sol. The pH upon addition of the iron antimonate slurry was 9.14. Subsequently, 332.9 g of ammonium paramolybdate was dissolved. Then, 4.4 g of 85% phosphoric acid and 2.3 g of boric anhydride were added. Under stirring, a solution obtained by dissolving 45.7 g of bismuth nitrate, 3.8 g of potassium nitrate, 219.3 g of nickel nitrate, 109.8 g of cobalt nitrate, 60.4 g of chromium nitrate, and 30 g of citric acid in 270 g of 3.3% nitric acid. Were mixed. Next, a solution obtained by dissolving 24.6 g of cerium nitrate in 70 g of pure water was added to this solution. Next, a solution in which 30 g of citric acid and 99.0 g of ferric nitrate were dissolved in 270 g of pure water was added, and then adjusted to pH 2.2 by adding 15% aqueous ammonia. This slurry was heat-treated at 99 ° C. under reflux for 3 hours.
The resulting slurry was spray dried by controlling the inlet temperature at 330 ° C. and the outlet temperature at 160 ° C. with a rotary disk spray dryer. The obtained spherical particles were heat-treated at 250 ° C., followed by baking at 450 ° C. for 2.5 hours and further at 650 ° C. for 3 hours.
[0028]
Example 2
A catalyst having the same composition as in Example 1 was prepared in the same manner as in Example 1 except that 20% iron antimonate slurry was added after dissolving ammonium paramolybdate, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 5.60.
[0029]
Example 3
A catalyst having the same composition as in Example 1 was prepared in the same manner as in Example 1 except that 20% iron antimonate slurry was added after adding the cerium solution, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 1.58.
[0030]
Example 4
A method similar to Example 1 except that a catalyst represented by Mo10Bi0.6Fe4.9Sb4.2Ni6.0Cr0.8Ce0.4K0.2P0.1B0.1Si35 was added after adding 20% iron antimonate slurry after adding the cerium solution. And fired under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 1.55.
[0031]
Example 5
A catalyst having the same composition as in Example 1 was prepared in the same manner as in Example 1 except that 20% iron antimonate slurry was added after the addition of iron and citric acid solution, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 0.90.
[0032]
Example 6
A catalyst having the same composition as in Example 4 was prepared in the same manner as in Example 1 except that 20% iron antimonate slurry was added after the addition of iron and citric acid solution, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 0.93.
[0033]
Example 7
A catalyst having the same composition as in Example 1 was prepared in the same manner as in Example 1 except that 20% iron antimonate slurry was added after pH 2.2 adjustment, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 2.21.
[0034]
Example 8
A catalyst having a composition represented by Mo10Bi0.5Fe2.9Sb1.8Ni4.0Cr0.8Ce0.3Co2.0K0.2P0.2B0.2Si35 was prepared in the same manner as in Example 1, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 9.14.
[0035]
Example 9
A catalyst having a composition represented by Mo10Bi0.5Fe5.6Sb4.7Ni4.0Cr0.8Ce0.3Co2.0K0.2P0.2B0.2Si35 was prepared in the same manner as in Example 1, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 9.14.
[0036]
Comparative Example 1
A catalyst having the same composition as in Example 1 was prepared in the same manner as in Example 1 except that 20% iron antimonate slurry was added after the heat treatment, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 1.84.
[0037]
Comparative Example 2
A catalyst having the same composition as in Example 4 was prepared in the same manner as in Example 1 except that 40% iron antimonate slurry was added after the heat treatment, and calcined under the conditions shown in Table 1. The pH at the time of adding the iron antimonate slurry was 1.80.
[0038]
Comparative Example 3
A catalyst having the same composition as in Example 1 was prepared by the following method.
Separately prepared 894.9 g of 20% iron antimonate slurry was added to 1982.5 g of 20% silica sol. The pH upon addition of the iron antimonate slurry was 9.14. Subsequently, 332.9 g of ammonium paramolybdate was dissolved. Then, 4.4 g of 85% phosphoric acid and 2.3 g of boric anhydride were added. Under stirring, a solution in which 3.8 g of potassium nitrate, 219.3 g of nickel nitrate, 109.8 g of cobalt nitrate, and 60.4 g of chromium nitrate were dissolved in 270 g of pure water was mixed. Next, a solution obtained by dissolving 24.6 g of cerium nitrate in 70 g of pure water was added to this solution. Next, a solution in which 30 g of citric acid and 99.0 g of ferric nitrate were dissolved in 270 g of pure water was added, and then adjusted to pH 2.2 by adding 15% aqueous ammonia. This slurry was heat-treated at 99 ° C. under reflux for 3 hours. Next, a solution in which 45.7 g of bismuth nitrate and 30 g of citric acid were dissolved in 50 g of 10% nitric acid was added.
The resulting slurry was spray dried by controlling the inlet temperature at 330 ° C. and the outlet temperature at 160 ° C. with a rotary disk spray dryer. The obtained spherical particles were heat-treated at 250 ° C., followed by baking at 450 ° C. for 2.5 hours and further at 650 ° C. for 3 hours.
[0039]
[Table 1]

[0040]
【The invention's effect】
The composite oxide catalyst for gas phase ammoxidation prepared by the method of the present invention is highly active and can give the target product in high yield.

Claims (2)

(1) molybdenum, (2) bismuth, (3) iron, (4) cerium, magnesium, chromium, manganese, cobalt, nickel, and at least one element selected from the group consisting of zinc, (5) iron antimonate And (6) a method for preparing a composite oxide catalyst for gas phase ammoxidation reaction containing silicon as an essential component, including at least (1), (2), (5) and (6) among the essential components. A method for preparing a composite oxide catalyst for vapor phase ammoxidation reaction, comprising a step of heat-treating the slurry at a temperature in the range of 50 to 120 ° C. The composition of the composite oxide catalyst has the general formula MoaBibFecSbdHeLfMgNhXiYjSikOx
(In the formula, Mo, Bi, Fe, Sb, Si and O represent molybdenum, bismuth, iron, antimony, silicon and oxygen, respectively, H represents cerium, magnesium, calcium, strontium, barium, chromium, manganese, cobalt and nickel. At least one element selected from the group consisting of copper, zinc and cadmium, L is at least one element selected from the group consisting of yttrium, lanthanum, praseodymium, neodymium, samarium, aluminum, gallium and indium, and M is titanium At least one element selected from the group consisting of zirconium, vanadium, niobium, tantalum, tungsten, germanium, tin and lead, N is selected from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and silver Small At least one element, X is at least one element selected from the group consisting of phosphorus, boron, arsenic, thallium and tellurium, Y is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium and cesium The subscripts a, b, c, d, e, f, g, h, i, j, k, and x represent the atomic ratio of each element, and when a = 10, b = 0.1 -1.5, c = 0.5-6.0, d = 0.5-5.5, e = 3-10, f = 0-2, g = 0-3, h = 0-1, i = 0-3, j = 0.05-1.5, k = 20-200, and x is the number of oxygen atoms necessary to satisfy the valence of each component. The method for preparing a composite oxide catalyst for vapor phase ammoxidation reaction according to claim 1.