JPH05317713A - Preparation of catalyst for synthesizing acrylic acid - Google Patents

Abstract

PURPOSE:To prepare a catalyst with an improved yield on acrylic acid by a method wherein water and/or an alcohol are incorporated in a dried product obtd. from an aq. slurry of a catalytic ingredient and the mixture is molded after mixing and the molded catalyst is frozen and then, heat-treated. CONSTITUTION:In a method for preparing a catalyst contg. at least Mo and V as the ingredients for synthesizing acrylic acid by performing vapor phase catalytic oxidation of acrolein with molecular oxygen, a mixed soln. or an aq. slurry contg. the catalytic ingredients is dried and 5-60wt.% water and/or alcohol are added to and mixed with the obtd. dried product and after molding, it is frozen and heat-treated. As the result, a catalyst wherein fine hole area in the catalyst is increased and the yield of acrylic acid is improved, can be prepd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a process for producing a catalyst used in the synthesis of acrylic acid from acrolein by vapor phase catalytic oxidation.

[0002]

2. Description of the Related Art Conventionally, gas phase catalytic oxidation of acrolein,
Regarding the method for synthesizing acrylic acid and the catalyst used at that time, see, for example, JP-A-49-47276 and 50-
84521, 52-153889, 53-76.
Although many proposals have been made such as JP-A No. 14 and JP-A No. 58-166939, it is desired to further improve the performance as an industrial catalyst.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel method for producing a catalyst used when synthesizing acrylic acid from acrolein.

[0004]

The present invention provides a method for producing a catalyst containing at least molybdenum and vanadium as components for synthesizing acrylic acid by vapor-phase catalytic oxidation of acrolein with molecular oxygen. The mixed solution or aqueous slurry containing the above is dried, 5 to 60% by weight of water and / or alcohol is added to the obtained dried product and mixed, and after shaping, the shaped catalyst is frozen, then dried and heat treated. Or a heat treatment, the present invention relates to a method for producing a catalyst for acrylic acid synthesis.

In the present invention, after preparing a mixed solution or an aqueous slurry containing a catalyst component, most of the water is removed and then dried to obtain a dried catalyst product. It is important that the dried catalyst product obtained is mixed with water and / or alcohol, shaped, and then the shaped catalyst is frozen, followed by drying and heat treatment, or heat treatment. Mechanism of improving catalyst performance by freezing the water- and / or alcohol-containing shaped catalyst obtained by mixing with water and / or alcohol and shaping and then heat-treating or drying without drying Is not clear at this stage.
However, by freezing the water-containing and / or alcohol-containing catalyst, the pores of 100 to 10000Å in the catalyst, which are considered to be effective for the oxidation reaction of synthesizing acrylic acid from acrolein, are increased, which is ideal. It is estimated that the catalyst performance is improved due to the formation of the pore structure.

In the present invention, the amount of water and / or alcohol mixed with the dried catalyst product is preferably in the range of 5 to 60% by weight, more preferably 10 to 30% by weight, based on the weight of the dried catalyst product. .. If it is less than 5% by weight or more than 60% by weight, the moldability at the time of shaping becomes poor and it becomes unsuitable as a method for producing an industrial catalyst. The alcohol is preferably liquid at room temperature and water-soluble.
Methyl alcohol, ethyl alcohol, etc. can be mentioned as such an example.

When the dried catalyst product is mixed with water and / or alcohol, conventionally known additives such as polyvinyl alcohol, carboxymethyl cellulose, inorganic fiber and the like may be further added. In the present invention, the method of mixing the dried catalyst product with water and / or alcohol and shaping is not particularly limited, and a general powder molding machine such as an extrusion molding machine or a rolling granulator. Can be used to mold into any shape such as spherical, ring-shaped, columnar, or star-shaped.

In the present invention, if water and / or alcohol freezes, the freezing temperature, time and method of the catalyst are not particularly limited. Examples of such a method include a method of adding a shaped water and / or alcohol-containing catalyst into liquid nitrogen. The frozen catalyst thus obtained is then dried and heat treated, or heat treated. In the present invention, these processing conditions are not particularly limited, and known processing conditions can be applied. Usually, the drying condition is 60 to 150 ° C., and the heat treatment condition is 300 to 600 ° C.

[0009] The present invention relates to compounds of the general formula _{Mo a V b X c Y d} Z e O f ( wherein, Mo, V and O each represent molybdenum, vanadium and oxygen, X is iron, chromium, cobalt,
At least one element selected from the group consisting of strontium and aluminum is shown, Y is germanium,
At least one element selected from the group consisting of boron, arsenic, selenium, silver, tellurium, silicon, sodium, lithium, antimony, phosphorus, potassium and barium is shown, and Z is magnesium, titanium, manganese, copper, zinc,
At least one element selected from the group consisting of zirconium, niobium, tungsten, tantalum, bismuth, calcium and tin is shown. a, b, c, d, e and f represent the atomic ratio of each element, and when a = 12, b = 0.
01-6, c = 0.1-5, d = 0-10, e = 0-5
And f is the number of oxygen atoms required to satisfy the valence of each component. It is preferably applied when producing a catalyst having a composition represented by

The method for producing the catalyst having the composition used in the present invention does not need to be limited to a special method, and is a well-known evaporation dry method or precipitation method as long as there is no significant uneven distribution of the components. Various methods such as the oxide mixing method can be used. As a raw material of the catalyst component, a combination of oxides, nitrates, carbonates, ammonium salts, halides and the like of each element can be used. For example, ammonium paramolybdate, molybdenum trioxide, molybdenum chloride or the like can be used as the molybdenum raw material, and ammonium metavanadate, vanadium pentoxide, vanadium chloride or the like can be used as the vanadium raw material.

When the catalyst obtained in the present invention is used, the concentration of acrolein in the raw material gas can be varied over a wide range, but 1 to 20% by volume is suitable, and particularly 3 to 1
0% by volume is preferred. The raw material acrolein may contain a small amount of impurities such as water and lower saturated aldehydes, and these impurities do not substantially affect the reaction. It is economical to use air as an oxygen source for the catalytic oxidation, but if necessary, air enriched with pure oxygen can also be used. The oxygen concentration in the raw material gas is defined by the molar ratio to acrolein, and this value is 0.3 to 4, especially 0.4 to
2.5 is preferred. The raw material gas may be diluted by adding an inert gas such as nitrogen, steam or carbon dioxide gas. The reaction pressure is
From normal pressure to several atmospheres is good. The reaction temperature is 200 to 45
It can be selected in the range of 0 ° C., but especially 220 to 430
C is preferred. The reaction can be carried out in a fixed bed or a fluidized bed.

[0012]

EXAMPLES The method for producing the catalyst according to the present invention and the reaction examples using the same will be specifically described below. In the examples and comparative examples, the reaction rate of acrolein and the selectivity of acrylic acid produced are defined as follows.

[0013]

[Equation 1]

Parts in the following Examples and Comparative Examples are parts by weight, and analysis was carried out by gas chromatography.

Example 1 A mixed solution containing a catalyst component was prepared in accordance with Example 1 described in Japanese Patent Application No. 3-210264, and the solid solution obtained was evaporated to dryness. Dried for hours.
18 parts of water was mixed with 100 parts of this dry powder, and shaped into a ring with an outer diameter of 5 mm, an inner diameter of 2 mm and an average length of 5 mm by an extruder. 5% of this water-containing shaped material was added to liquid nitrogen.
After soaking for 5 minutes to freeze, dry at 130 ℃ for 6 hours,
Then, the one that was heat-treated at 380 ° C. for 5 hours under air flow was used as a catalyst. The composition of elements other than oxygen in the obtained catalyst (hereinafter the same) is Mo ₁₂ V ₃ Si _4.3 Na _0.7 Fe ₁ B
It was a _0.3 . This catalyst was filled in a reaction tube, and a mixed gas of acrolein 5%, oxygen 10%, water vapor 30%, and nitrogen 55% (volume%) was passed through at a reaction temperature of 270 ° C. and a contact time of 3.6 seconds. When the products were collected and analyzed by gas chromatography, the acrolein conversion was 99.7% and the acrylic acid selectivity was 95.4%. 100 ~ of this catalyst
The pore volume in the range of 10000Å was 0.31 ml / g.

Comparative Example 1 Molding and reaction were carried out in the same manner as in Example 1 except that the water-containing shaped product was not immersed in liquid nitrogen. As a result, the acrolein conversion was 98.9% and the acrylic acid selectivity was 95.0%. 100-1 of this catalyst
The pore volume in the range of 0000Å was 0.25 ml / g. Comparative Example 2 When a mold was applied in the same manner as in Example 1 except that the amount of water mixed with 100 parts of dry powder was 3.5 parts, the moldability during molding was extremely high. Poorly, it was not possible to obtain the target shaped object. Comparative Example 3 When molding was performed in the same manner as in Example 1 except that the amount of water mixed with 100 parts of dry powder was 110 parts, the moldability during molding was poor, and However, it was difficult to maintain the shape of the shaped product, and the intended shaped product could not be obtained.

Example 2 Molding and reaction were carried out in the same manner as in Example 1 except that the hydrous shaped product was left in a freezer at -10 ° C for 15 hours. The reaction results and pore volume are shown in Table 1.

Example 3 In Example 1, the amount of water mixed with 100 parts of dry powder was changed to 25 parts, and the hydrous shaped product was frozen in liquid nitrogen.
In the same manner as in Example 1 except that the drying was not performed, that is, the reaction was performed using a catalyst that was heat-treated at 380 ° C. immediately after freezing under air flow. The reaction results and pore volume are shown in Table 1.

Comparative Example 4 Molding and reaction were carried out in the same manner as in Example 3 except that the hydrous shaped article was not immersed in liquid nitrogen. The reaction results and pore volume are shown in Table 1.

Example 4 A mixed solution containing a catalyst component was prepared according to Example 6 described in Japanese Patent Application No. 2-285147, and the solid solution obtained was evaporated to dryness, and then the resulting solid matter was dried at 130 ° C. at 16 ° C. Dried for hours.
3.5 parts of polyvinyl alcohol having a degree of polymerization of 500 and 20 parts of water were mixed with 100 parts of this dry powder, and the mixture was shaped into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm and an average length of 5 mm by an extruder. This hydrated product was immersed in liquid nitrogen for 5 minutes to be frozen, dried at 130 ° C. for 6 hours, and then heat-treated at 380 ° C. for 5 hours under air circulation. The composition of elements of the obtained catalyst was Mo ₁₂ V ₃ W _0.2 Nb _0.2 Cr.
_{It was 0.5} Co _0.5 Al _0.5 Si ₃ Mg _0.2 . Using this catalyst, a reaction was carried out under the same conditions as in Example 1. The reaction results and pore volume are shown in Table 1.

Comparative Example 5 Molding and reaction were carried out in the same manner as in Example 4 except that the water-containing shaped product was not charged into liquid nitrogen. The reaction results and pore volume are shown in Table 1.

Example 5 A mixed solution containing a catalyst component was prepared according to Example 18 described in Japanese Patent Application No. 2-280683, and the solid solution obtained was evaporated to dryness, and the resulting solid matter was dried at 130 ° C. at 16 ° C. Dried for hours. 18 parts of ethyl alcohol to 100 parts of this dry powder
Parts and 5 parts of an inorganic fiber having an average length of 200 μ were mixed and shaped into a ring having an outer diameter of 5 mm, an inner diameter of 2 mm and an average length of 5 mm by an extruder. This ethyl alcohol-containing shaped product was immersed in liquid nitrogen for 15 minutes to be frozen, dried at 130 ° C. for 6 hours, and then dried under air flow at 38 ° C.
Heat treatment was performed at 0 ° C. for 5 hours. The composition of the elements of the obtained catalyst was Mo ₁₂ V _3.5 Fe _0.8 Na _0.3 Co _0.5 Si _4.5 Sr.
It was _0.5 Ag _0.08 . Using this catalyst, a reaction was carried out under the same conditions as in Example 1. The reaction results and pore volume are shown in Table 1.

Comparative Example 6 Molding and reaction were carried out in the same manner as in Example 5 except that the ethyl alcohol-containing shaped product was not charged into liquid nitrogen. The reaction results and pore volume are shown in Table 1.

Example 6 A mixed solution containing a catalyst component was prepared according to Example 10 described in Japanese Patent Application No. 3-112311, and the solid solution obtained was evaporated to dryness, and the resulting solid matter was dried at 16 ° C. at 16 ° C. Dried for hours. 10 parts of water and 8 parts of ethyl alcohol were mixed with 100 parts of this dry powder, and the average diameter was 4 by a tumbling granulator.
It was shaped into a spherical shape of mm. After this water-containing and ethyl alcohol-containing shaped product was put into liquid nitrogen to be frozen, 13
Dry for 6 hours at 0 ° C, then at 380 ° C for 5 hours under air flow
Heat treated for hours. The composition of the elements of the obtained catalyst is Mo ₁₂ V
It was _{3 Si 4.3 Fe 1 Sn 0.5 Mn} 0.1 Ta 0.2 Na 0.7. Using this catalyst, a reaction was carried out under the same conditions as in Example 1. The reaction results and pore volume are shown in Table 1.

Comparative Example 7 Molding and reaction were carried out in the same manner as in Example 6 except that the water-containing and ethyl alcohol-containing shaped product was not added to liquid nitrogen. The reaction results and pore volume are shown in Table 1.

[0026]

[Table 1]

[0027]

The catalyst obtained by the process of the present invention has an increased pore volume in the catalyst and improves the reaction rate of acrolein,
It also has the effect of improving the selectivity of acrylic acid.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Shioya 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A method for producing a catalyst containing at least molybdenum and vanadium as a component for synthesizing acrylic acid by vapor-phase catalytic oxidation of acrolein with molecular oxygen to prepare a mixed solution or an aqueous slurry containing the catalyst component. It is characterized in that after drying, 5 to 60% by weight of water and / or alcohol is added to the obtained dried product, mixed and shaped, and then the shaped catalyst is frozen, then dried and heat-treated, or heat-treated. A method for producing a catalyst for synthesizing acrylic acid, which comprises: 2. A method for producing acrylic acid by gas-phase catalytic oxidation of acrolein with molecular oxygen using the catalyst obtained in claim 1 at a temperature of 200 to 500 ° C.