JP2007222854A - Catalyst for synthesizing methacrolein and methacrylic acid, its manufacturing method, method for producing methacrolein and methacrylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst having excellent selectivity when used for producing methacrolein and methacrylic acid and a method for manufacturing the catalyst. <P>SOLUTION: The method for manufacturing the catalyst, which contains a compound oxide containing molybdenum, bismuth and iron as essential components and is used for synthesizing methacrolein and methacrylic acid, comprises the steps of: dissolving or dispersing each of raw materials of molybdenum, bismuth and iron at the least in water to prepare a raw material solution or slurry; heat-treating the raw material solution or slurry to obtain a catalyst precursor; pulverizing the catalyst precursor; dispersing the pulverized catalyst precursor in water to prepare catalyst precursor slurry; and heat-treating the catalyst precursor slurry. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a catalyst for synthesizing methacrolein and methacrylic acid containing at least molybdenum, bismuth and iron, particularly isobutylene or tertiary butyl alcohol (hereinafter sometimes abbreviated as TBA) is vapor-phase catalytically oxidized with molecular oxygen. The present invention relates to a catalyst used when synthesizing methacrolein and methacrylic acid, and a method for producing methacrolein and methacrylic acid using the catalyst.

  Methacrylic acid is an industrially useful substance used as a raw material for methyl methacrylate, which is a raw material for methacrylic resin, which is a representative of transparent resins.

  One of the industrial methods for producing methacrylic acid is a direct acid method using isobutylene or TBA. In this method, a two-stage oxidation reaction is used, and methacrolein and a small amount of methacrylic acid are mainly oxidized by the oxidation of isobutylene or TBA in the former stage, and methacrylic acid is produced by oxidizing the methacrolein produced in the first stage in the latter stage. The

Many studies have been made on a catalyst for producing methacrolein and methacrylic acid by vapor-phase catalytic oxidation of isobutylene or TBA with molecular oxygen, that is, a catalyst used in the preceding reaction. For example, the component which comprises a catalyst, and the thing regarding the ratio (patent documents 1-4), the thing regarding the manufacturing method of a catalyst (patent documents 5, 6), etc. are mentioned.
JP-A-55-127328 JP-A-56-2926 Japanese Patent Application Laid-Open No. 56-161341 JP 59-31727 A JP-A-7-289902 JP 2001-205090 A

  Since the compounds (methacrolein and methacrylic acid) produced by the reaction using these catalysts have a great demand as chemical raw materials, they are only large-scale industrial plants. Therefore, even if the total selectivity of methacrolein and methacrylic acid is improved by only 0.1%, there is a great merit from the viewpoint of resource validation and manufacturing cost reduction. Therefore, it is desired to further increase the total selectivity of methacrolein and methacrylic acid.

  An object of the present invention is to provide a catalyst excellent in methacrolein and methacrylic acid selectivity and a method for producing the same.

The present invention is a method for producing methacrolein and methacrylic acid synthesis catalyst comprising a composite oxide containing molybdenum, bismuth and iron as essential components,
At least a step of preparing a raw material solution or slurry by dissolving or dispersing each raw material of molybdenum, bismuth and iron in water;
Heat-treating the raw material solution or slurry to obtain a catalyst precursor;
Pulverizing the catalyst precursor;
Dispersing the finely divided catalyst precursor in water to prepare a catalyst precursor slurry; and
Heat treating the catalyst precursor slurry;
A method for producing methacrolein and a methacrylic acid synthesis catalyst characterized by having, and a catalyst for synthesizing methacrolein and methacrylic acid obtained by the method.

  The present invention also provides a method for producing methacrolein and methacrylic acid, characterized in that isobutylene or tertiary butyl alcohol is subjected to gas phase catalytic oxidation with molecular oxygen using the above-mentioned methacrolein and methacrylic acid synthesis catalyst. is there.

  The catalyst for synthesizing methacrolein and methacrylic acid of the present invention is excellent in methacrolein and methacrylic acid selectivity. By using this catalyst, methacrolein and methacrylic acid can be produced with high selectivity.

  As long as the catalyst for synthesizing methacrolein and methacrylic acid of the present invention contains a composite oxide containing molybdenum, bismuth and iron as essential components, the composition of the composite oxide is not particularly limited. The composite oxide having the composition represented by the formula (1) is included.

Mo _a Bi _{b F c} Co _d N _e X _f Y _g Z _h Si _i O _j (1)
In the formula (1), Mo, Bi, Fe, Co, Ni, Si and O represent molybdenum, bismuth, iron, cobalt, nickel, silicon and oxygen, respectively, X is chromium, lead, manganese, calcium, magnesium, Represents at least one element selected from the group consisting of niobium, silver, barium, tin, tantalum and zinc, and Y is selected from the group consisting of phosphorus, boron, sulfur, selenium, tellurium, cerium, tungsten, antimony and titanium Z represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium. a, b, c, d, e, f, g, h, i, and j represent the atomic ratio of each element, and when a = 12, b = 0.01-3, c = 0.01-5 , D = 0-12, e = 0-12 (provided d + e = 1-12), f = 0-8, g = 0-5, h = 0.001-2, i = 0-20, j Is the oxygen atom ratio necessary to satisfy the valence of each component. The composition of the composite oxide other than oxygen is obtained by dissolving the catalyst in aqueous ammonia and analyzing it by ICP emission spectrometry and atomic absorption spectrometry, or analyzing a standard sample analyzed by ICP emission analysis and atomic absorption spectrometry. In some cases, it can be estimated by comparison with this standard sample using an X-ray fluorescence analyzer.

  Hereinafter, a method for producing the methacrolein and methacrylic acid synthesis catalyst will be described.

  First, at least each raw material of molybdenum, bismuth and iron is dissolved or dispersed in water to prepare a raw material solution or slurry. The raw material to be used is not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides, halides and the like of each element can be used in combination. As the molybdenum raw material, for example, ammonium paramolybdate, molybdenum trioxide, molybdic acid, molybdenum chloride, or the like can be used. Examples of the bismuth raw material that can be used include bismuth trioxide, bismuth nitrate, and bismuth subcarbonate. Examples of the iron raw material that can be used include ferric nitrate, iron hydroxide, and iron trioxide. The raw material of each element may be 1 type, and may use 2 or more types together.

  Next, the raw material solution or slurry is heat-treated to form a catalyst precursor. The heat treatment method is not particularly limited, but it can be first dried using a general-purpose box-type dryer, spray dryer, drum dryer, slurry dryer or the like, and further baked separately. The heat treatment temperature is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and further preferably 200 ° C. or higher. Moreover, 500 degrees C or less is preferable, 400 degrees C or less is more preferable, and also 300 degrees C or less is preferable. The heat treatment time is preferably 0.1 to 48 hours. When drying and baking are performed as the heat treatment, the drying temperature in cases other than spray drying is preferably 50 to 200 ° C, and the outlet temperature in the case of spray drying is usually 100 ° C or higher, preferably 105 to 200 ° C. Firing is preferably performed at 150 to 400 ° C. for 0.1 to 48 hours.

  Next, the obtained catalyst precursor is pulverized. As a method for pulverizing the catalyst precursor, either a dry method or a wet method may be used. In the case of the dry type, a crusher, a ball mill or the like is used. In the case of the wet type, a liquid such as water is mixed and pulverized using a homogenizer or the like. Dry and wet methods may be used in combination. The median diameter of the catalyst precursor after pulverization is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. Moreover, 0.01 micrometer or more, 0.05 micrometer or more, and 0.1 micrometer or more are preferable. The median diameter can be measured with a laser diffraction particle size distribution analyzer.

  Thereafter, the finely divided catalyst precursor is dispersed in water to prepare a catalyst precursor slurry. In the present invention, the effect does not appear unless the finely divided catalyst precursor is dispersed in water. The mass of water to be used is preferably 1 to 100 times, more preferably 2 to 10 times the mass of the finely divided catalyst precursor. In some cases, heating and cooling may be performed, and various acids other than water, bases, and organic solvents may be further mixed.

  Thereafter, the catalyst precursor slurry is heat-treated to obtain a catalyst. The heat treatment method is not particularly limited, but the same operation as the heat treatment method of the raw material solution or slurry can be performed. The heat treatment temperature is preferably 300 ° C. or higher, and more preferably 400 ° C. or higher. Moreover, 700 degrees C or less is preferable and 600 degrees C or less is more preferable. The heat treatment time is preferably 0.1 to 48 hours. However, the heat treatment temperature here is preferably higher than the heat treatment temperature of the raw material solution or slurry. When performing drying and baking as the heat treatment, drying is performed at 50 to 200 ° C. for 0.1 to 48 hours in the case other than spray drying, and in the case of spray drying, the outlet temperature is usually 100 ° C. or higher, and 105 to 200 ° C is preferred. Firing is preferably performed at 300 to 700 ° C. for 0.1 to 48 hours. In this case, the drying temperature here is not particularly limited, but the firing temperature here is preferably higher than the heat treatment temperature of the raw material solution or slurry.

  In carrying out the present invention, the obtained catalyst can be molded. In addition, the method for molding the catalyst is not particularly limited, and using a general powder molding machine such as a tableting molding machine, an extrusion molding machine, a rolling granulator, a spherical shape, a ring shape, a cylindrical shape, It can be molded into any shape such as a star shape. In addition, a supported catalyst in which the above-described catalyst component is supported on a carrier can be used, and in this case, the carrier may be molded in the coexistence. Further, the support may be mixed with the catalyst precursor slurry.

  When molding the catalyst, conventionally known additives such as organic compounds such as polyvinyl alcohol and carboxymethyl cellulose may be further added. Further, inorganic compounds such as graphite and diatomaceous earth, and inorganic fibers such as glass fiber, ceramic fiber and carbon fiber may be added. Examples of the carrier used for carrying are silica, alumina, silica-alumina, magnesia, titania and the like.

  The catalyst molded body obtained as described above can be further heat-treated. The heat treatment conditions are not particularly limited, and known heat treatment conditions can be applied. The heat treatment is usually performed at a temperature range of 300 to 600 ° C. for 0.1 to 48 hours.

  According to such a method, it is considered that the components that have become non-uniform at the time of the heat treatment are homogenized by pulverization after the heat treatment, and further, the portion dissolved in the water is reconstructed by redispersing it in water. Therefore, it is considered that the selectivity of the obtained catalyst is improved. That is, it is presumed that the composition of the catalyst surface and the interior changes before and after redispersion in water.

  The catalyst of the present invention can be used after diluted with an inert carrier such as silica, alumina, silica-alumina, magnesia, titania, silicon carbide and the like.

  The catalyst of the present invention can be used when performing a gas phase catalytic oxidation reaction of isobutylene or TBA with molecular oxygen. Specifically, molecular oxygen is added to the raw material isobutylene or TBA, and gas phase catalytic oxidation is performed in the presence of the catalyst. In carrying out the gas phase catalytic oxidation reaction, the molar ratio of isobutylene or TBA to molecular oxygen is preferably in the range of 1: 0.5-3. The raw material gas containing the raw material isobutylene or TBA and molecular oxygen is preferably used in a state diluted with an inert gas. The concentration of the raw material in the raw material gas is preferably 1 to 20% by volume. It is economical to use air as the molecular oxygen source, but if necessary, air enriched with pure oxygen is used. Further, it is preferable to add water vapor to the raw material gas. The concentration of water in the raw material gas is preferably 1 to 45% by weight. The reaction pressure is preferably from normal pressure to several atmospheres. The reaction temperature can be selected in the range of 200 to 450 ° C. The range of 250-400 degreeC is especially preferable.

Hereinafter, the manufacture example of the catalyst by this invention and the reaction example using it are demonstrated with a comparative example. In the description, “parts” means parts by mass. The analysis used gas chromatography. The reaction rate of the raw material (isobutylene or TBA) and the selectivity of the produced methacrolein and methacrylic acid are respectively defined as follows.
Reaction rate of raw material (%) = (number of moles of reacted raw material / number of moles of supplied raw material) × 100
Selectivity (%) of methacrolein = (number of moles of methacrolein produced / number of moles of reacted raw material) × 100
Methacrylic acid selectivity (%) = (number of moles of methacrylic acid produced / number of moles of reacted raw material) × 100
The median diameter of the catalyst precursor was measured with SALD-7000 (trade name) manufactured by Shimadzu Corporation. The elemental composition of the catalyst (excluding oxygen) was estimated by ICP emission analysis and atomic absorption analysis of the catalyst dissolved in aqueous ammonia.

<Example 1>
(Catalyst preparation)
Liquid A was prepared by dissolving and mixing 500 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate, and 27.6 parts of cesium nitrate in 1,000 parts of pure water. Thereafter, when 27.5 parts of bismuth trioxide having a sodium content of 3 ppm was added, a white precipitate was formed in the liquid A. Separately, 200.2 parts of ferric nitrate, 78.9 parts of nickel nitrate, 14.0 parts of zinc nitrate, and 357.1 parts of cobalt nitrate were sequentially added and dissolved in 1,000 parts of pure water. It was set as B liquid. Subsequently, the B liquid was added to the A liquid in which the white precipitate was generated to obtain a slurry C liquid. Thereafter, 24.1 parts of antimony trioxide was added to the C liquid to obtain a D liquid. After aging at 80 ° C. for 1 hour, most of the water was evaporated.

  The obtained cake-like substance A was heat-treated at 120 ° C. for 16 hours and further in an air atmosphere at 200 ° C. for 3 hours, and then the obtained catalyst precursor was pulverized. The median diameter of the finely divided catalyst precursor was 1 μm. 500 parts of the resulting finely divided catalyst precursor was dispersed in 2000 parts of water and stirred for 1 hour. Thereafter, most of the water was evaporated. The obtained cake-like substance B was heat-treated at 120 ° C. for 16 hours and further in an air atmosphere at 300 ° C. for 1 hour, and then pulverized. Thereafter, the pressure-molded product was crushed, and among the crushed particles, a particle that passed through a sieve having an aperture of 2.36 mm and not passed through a sieve having an aperture of 0.71 mm was obtained. Thereafter, the particles of a specific size thus classified were again heat-treated at 500 ° C. for 6 hours in an air atmosphere to obtain a catalyst.

The elemental composition (excluding oxygen) of the catalyst thus obtained was Mo ₁₂ Bi _0.5 Fe _2.1 Ni _2.3 Co _5.2 Zn _0.2 W _0.1 Sb _0.7 Cs _0.6 .

(Reaction evaluation)
After filling this catalyst in a stainless steel reaction tube, the reaction tube was charged with a raw material mixed gas of 5% isobutylene (raw material), 12% oxygen, 10% water vapor, and 73% (volume%) nitrogen for a contact time of 3.6. The gas phase contact reaction of isobutylene was conducted at 340 ° C. As a result, the reaction rate of isobutylene was 98.6%, the selectivity of methacrolein was 90.7%, the selectivity of methacrylic acid was 3.7%, and the total selectivity of methacrolein and methacrylic acid was 94.4%.

<Comparative Example 1>
(Catalyst preparation)
The cake-like substance A obtained in the same manner as in Example 1 was heat-treated at 120 ° C. for 16 hours and further in an air atmosphere at 300 ° C. for 1 hour, and then pulverized. Thereafter, the pressure-molded product was crushed, and among the crushed particles, a particle that passed through a sieve having an aperture of 2.36 mm and not passed through a sieve having an aperture of 0.71 mm was obtained. Thereafter, the particles of a specific size thus classified were again heat-treated at 500 ° C. for 6 hours in an air atmosphere to obtain a catalyst.

(Reaction evaluation)
The reaction was evaluated under the same conditions as in Example 1 except that this catalyst was used. As a result, the reaction rate of isobutylene was 98.0%, the selectivity of methacrolein was 89.1%, the selectivity of methacrylic acid was 3.4%, and the total selectivity of methacrolein and methacrylic acid was 92.5%.

<Example 2>
The reaction was evaluated under the same conditions as in Example 1 except that the raw material was changed to TBA. As a result, the reaction rate of TBA was 100%, the selectivity of methacrolein was 89.7%, the selectivity of methacrylic acid was 3.4%, and the total selectivity of methacrolein and methacrylic acid was 93.1%.

<Comparative example 2>
The reaction was evaluated under the same conditions as in Comparative Example 1 except that the raw material was changed to TBA. As a result, the reaction rate of TBA was 100%, the selectivity of methacrolein was 88.1%, the selectivity of methacrylic acid was 3.0%, and the total selectivity of methacrolein and methacrylic acid was 91.1%.

  As described above, the catalyst of the present invention is excellent in the total selectivity of methacrolein and methacrylic acid, and methacrolein and methacrylic acid can be produced with high selectivity by using this catalyst.

Claims (3)

A method for producing methacrolein and methacrylic acid synthesis catalyst, comprising a composite oxide containing molybdenum, bismuth and iron as essential components,
At least a step of preparing a raw material solution or slurry by dissolving or dispersing each raw material of molybdenum, bismuth and iron in water;
Heat-treating the raw material solution or slurry to obtain a catalyst precursor;
Pulverizing the catalyst precursor;
Dispersing the finely divided catalyst precursor in water to prepare a catalyst precursor slurry; and
Heat treating the catalyst precursor slurry;
A method for producing methacrolein and a catalyst for synthesizing methacrylic acid, characterized by comprising:   A catalyst for synthesizing methacrolein and methacrylic acid obtained by the method according to claim 1.   A method for producing methacrolein and methacrylic acid, comprising subjecting isobutylene or tertiary butyl alcohol to gas phase catalytic oxidation with molecular oxygen using the methacrolein and methacrylic acid synthesis catalyst according to claim 2.