JP6922993B2 - A method for producing a catalyst for producing α, β-unsaturated carboxylic acid, a method for producing α, β-unsaturated carboxylic acid, and a method for producing an α, β-unsaturated carboxylic acid ester. - Google Patents

Description

The present invention relates to a method for producing a catalyst for producing an α, β-unsaturated carboxylic acid, a method for producing an α, β-unsaturated carboxylic acid, and a method for producing an α, β-unsaturated carboxylic acid ester.

The catalyst used when α, β-unsaturated aldehyde is vapor-phase catalytically oxidized with molecular oxygen to produce α, β-unsaturated carboxylic acid is a heteropolyacid such as phosphomolybdic acid or phosphomolybate. A catalyst whose main component is the salt is known. Many studies have been conducted on the method for producing the catalyst, and most of them first prepare an aqueous slurry or an aqueous solution containing each element constituting the catalyst, and then dry and calcin the catalyst to produce the catalyst. ing.

The basic performance of such a catalyst mainly depends on the elemental composition, crystal structure, particle size, etc., but its control is required to control the conditions of the preparation process of the aqueous slurry or aqueous solution. Generally, as a raw material used for preparing an aqueous slurry or an aqueous solution, both a water-soluble raw material and a water-insoluble raw material can be used. However, it is known that the physical characteristics of the raw material have a great influence on the catalytic performance, especially when a raw material insoluble in water is used. For example, Patent Document 1 describes that a molybdenum-containing solid catalyst having high catalytic activity and selectivity can be produced by using a molybdenum oxide having a compression degree of 60 or less as a raw material. Further, Patent Document 2 discloses a method for producing a catalyst using a molybdenum oxide having a defined diffraction peak position and diffraction intensity in an X-ray diffraction diagram using CuKα rays as X-rays as a raw material.

Japanese Unexamined Patent Publication No. 2007-229561 Japanese Unexamined Patent Publication No. 2004-8834

However, in the catalyst produced using the molybdenum oxide disclosed in Patent Documents 1 and 2, the yield of α, β-unsaturated carboxylic acid is still insufficient, and further improvement of the catalyst is desired.

An object of the present invention is to provide a catalyst capable of producing an α, β-unsaturated carboxylic acid in a high yield.

The present invention is the following [1] to [ 12 ].

[1] α, β-unsaturated carboxylic acid using molybdenum oxide as a molybdenum raw material in which the proportion of particles having a particle size of 6 μm or less is 2 to 55% by volume in the frequency distribution curve obtained by measuring the particle size distribution. It is a manufacturing method of a catalyst for manufacturing.
(I) An aqueous slurry (I) obtained by mixing water with a catalyst raw material containing at least the molybdenum raw material and a phosphorus raw material is heated to 90 to 150 ° C. to prepare an aqueous slurry or an aqueous solution (II) containing a heteropolyacid. The process of obtaining and
(Ii) A step of adding a metal cation-containing compound to the aqueous slurry or aqueous solution (II) to obtain an aqueous slurry (III) in which a heteropolylate is precipitated.
(Iii) A step of drying the aqueous slurry (III) to obtain a dried catalyst precursor, and
(Iv) A step of heat-treating the dried catalyst precursor to obtain a catalyst, and
In the step (i), the time from when the temperature of the aqueous slurry (I) reaches 60 ° C. to when it reaches 90 ° C. is 5 to 40 minutes, α, β-unsaturated carboxylic acid. A method for producing a catalyst for producing an acid .

[ 2 ] The α, according to [1 ], wherein in the step (i), the time from when the temperature of the aqueous slurry (I) reaches 60 ° C. to when it reaches 90 ° C. is 7 to 30 minutes. A method for producing a catalyst for producing β-unsaturated carboxylic acid.

[ 3 ] Production of α, β-unsaturated carboxylic acid according to [1] or [2] , wherein the molybdenum raw material is a molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less is 2 to 35% by volume. Method for manufacturing catalyst for use.

[ 4 ] Production of the catalyst for producing α, β-unsaturated carboxylic acid according to [3 ], wherein the molybdenum raw material is a molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less is 2 to 15% by volume. Method.

[ 5 ] The α, β-unsaturated carboxylic acid according to any one of [1] to [4 ], wherein the catalyst for producing α, β-unsaturated carboxylic acid has a composition represented by the following formula (1). A method for producing a catalyst for producing an acid.
P _a Mo _b V _c Cu _d A _e E _f G _{g Oh} (1)
(In formula (1), P, Mo, V, Cu and O are element symbols indicating phosphorus, molybdenum, vanadium, copper and oxygen, respectively. A is antimony, bismuth, arsenic, germanium, zirconium, tellurium, respectively. Represents at least one element selected from the group consisting of silver, selenium, silicon, tungsten and boron, where E represents iron, zinc, chromium, magnesium, calcium, strontium, tantalum, cobalt, nickel, manganese, barium, titanium, Represents at least one element selected from the group consisting of tin, lead, niobium, indium, sulfur, palladium, gallium, cerium and lanthanum, where G is selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and tarium. Represents at least one element to be formed. A to h represent the atomic ratio of each element, and when b = 12, a = 0.5 to 3, c = 0.01 to 3, d = 0.01. ~ 2, e = 0 to 3, f = 0 to 3, g = 0.01 to 3, and h is the atomic ratio of oxygen required to satisfy the atomic value of each element.).

[ 6 ] The method for producing an α, β-unsaturated carboxylic acid production catalyst according to any one of [1] to [5 ], wherein 50% by mass or more of molybdenum trioxide is used as the molybdenum raw material.

[ 7 ] The method for producing an α, β-unsaturated carboxylic acid production catalyst according to [6 ], wherein 70% by mass or more of molybdenum trioxide is used as the molybdenum raw material.

[ 8 ] The catalyst for producing α, β-unsaturated carboxylic acid is used when α, β-unsaturated aldehyde is vapor-phase catalytically oxidized with molecular oxygen to produce α, β-unsaturated carboxylic acid. Any of [1] to [7 ], which is a catalyst, wherein the α, β-unsaturated aldehyde is (meth) acrolein and the α, β-unsaturated carboxylic acid is (meth) acrylic acid. The method for producing a catalyst for producing an α, β-unsaturated carboxylic acid according to.

[ 9 ] A catalyst for producing α, β-unsaturated carboxylic acid is produced by the method according to any one of [1] to [ 8], and α, β-unsaturated aldehyde is produced by molecular oxygen using the catalyst. A method for producing an α, β-unsaturated carboxylic acid by vapor-phase catalytic oxidation to produce an α, β-unsaturated carboxylic acid.

[ 10 ] Using the catalyst for producing α, β-unsaturated carboxylic acid produced by the method according to any one of [1] to [ 8], the gas phase of α, β-unsaturated aldehyde with molecular oxygen. A method for producing an α, β-unsaturated carboxylic acid by catalytic oxidation to produce an α, β-unsaturated carboxylic acid.

[ 11 ] A method for producing an α, β-unsaturated carboxylic acid ester, which esterifies an α, β-unsaturated carboxylic acid produced by the method according to [9 ] or [ 10].

[ 12 ] A α, β-unsaturated carboxylic acid ester for producing an α, β-unsaturated carboxylic acid by the method described in [9 ] or [ 10] and esterifying the α, β-unsaturated carboxylic acid. Production method.

According to the present invention, it is possible to provide a catalyst capable of producing an α, β-unsaturated carboxylic acid in a high yield.

It is a figure which shows the particle size distribution of molybdenum trioxide in Examples 1 to 4 and Comparative Examples 1 to 3.

[Catalyst for producing α, β-unsaturated carboxylic acid]
The catalyst for producing α, β-unsaturated carboxylic acid produced by the method according to the present invention contains at least molybdenum, but preferably contains phosphorus and molybdenum, and has a composition represented by the following formula (1). Is more preferable. As a result, α, β-unsaturated carboxylic acid can be produced in high yield in the production of α, β-unsaturated carboxylic acid. The elemental composition of the catalyst is a value obtained by analyzing a solution of the catalyst in aqueous ammonia by ICP emission spectrometry.
P _a Mo _b V _c Cu _d A _e E _f G _{g Oh} (1)

In formula (1), P, Mo, V, Cu and O are element symbols indicating phosphorus, molybdenum, vanadium, copper and oxygen, respectively. A represents at least one element selected from the group consisting of antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron, and E represents iron, zinc, chromium, magnesium, calcium, Represents at least one element selected from the group consisting of strontium, tantalum, cobalt, nickel, manganese, barium, titanium, tin, lead, niobium, indium, sulfur, palladium, gallium, cerium and lanthanum, where G represents lithium, Represents at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium. a to h represent the atomic ratio of each element, and when b = 12, a = 0.5 to 3, c = 0.01 to 3, d = 0.01 to 2, e = 0 to 3, f. = 0 to 3, g = 0.01 to 3, and h is the atomic ratio of oxygen required to satisfy the valence of each element.
Further, the catalyst may contain a small amount of an element not described in the formula (1).

The catalyst for producing α, β-unsaturated carboxylic acid produced by the method according to the present invention produces α, β-unsaturated carboxylic acid by vapor-phase catalytic oxidation of α, β-unsaturated aldehyde with molecular oxygen. It is preferable to be used when Further, it is preferable that the α, β-unsaturated aldehyde is (meth) acrolein and the α, β-unsaturated carboxylic acid is (meth) acrylic acid.

[Manufacturing method of catalyst for producing α, β-unsaturated carboxylic acid]
In the method for producing a catalyst for producing α, β-unsaturated carboxylic acid according to the present invention, the proportion of particles having a particle size of 6 μm or less is 2 to 55 volumes in the frequency distribution curve obtained by measuring the particle size distribution as a molybdenum raw material. Use% molybdenum oxide. The particle size distribution of molybdenum oxide was measured using a laser diffraction type particle size distribution measuring device SALD-7000 (product name, manufactured by Shimadzu Corporation), and 0.02 to 0.1 g of molybdenum oxide was obtained with respect to 500 g of pure water. Is dispersed and stirred for 30 seconds. Further, in the present invention, the frequency distribution curve is obtained by assuming the integrated volume of particles having a particle size of 1000 μm or less as the total particle volume.

In the present invention, in the frequency distribution curve obtained by the above-mentioned particle size distribution measurement, a molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less in particles having a particle size of 1000 μm or less is 2 to 55% by volume is used as a molybdenum raw material. To produce a catalyst for producing α, β-unsaturated carboxylic acid. As a result, it is considered that suitable active sites are formed in the obtained catalyst, the catalytic activity is improved, and the yield of α, β-unsaturated carboxylic acid can be improved.

The method for producing a catalyst for producing α, β-unsaturated carboxylic acid according to the present invention is not particularly limited except that the molybdenum oxide is used as a molybdenum raw material, and for example, a raw material containing the molybdenum oxide and water are mixed. Can have a step of obtaining an aqueous slurry or an aqueous solution. However, from the viewpoint of further improving the yield of α, β-unsaturated carboxylic acid, the method preferably has the following steps (i) to (iv).
(I) An aqueous slurry (I) obtained by mixing water with a catalyst raw material containing at least a molybdenum raw material and a phosphorus raw material is heated to 90 to 150 ° C. to obtain an aqueous slurry or an aqueous solution (II) containing a heteropolyacid. Process.
(Ii) A step of adding a metal cation-containing compound to the aqueous slurry or aqueous solution (II) to obtain an aqueous slurry (III) in which a heteropolylate is precipitated.
(Iii) A step of drying the aqueous slurry (III) to obtain a dried catalyst precursor.
(Iv) A step of heat-treating the dried catalyst precursor to obtain a catalyst.

Further, the method for producing a catalyst for producing an α, β-unsaturated carboxylic acid according to the present invention may further include a molding step described later.

(Step (i))
In the step (i), the aqueous slurry (I) obtained by mixing water with a catalyst raw material containing at least a molybdenum raw material and a phosphorus raw material is heated to 90 to 150 ° C. to heat an aqueous slurry or an aqueous solution (II) containing a heteropolyacid. ). After heating the aqueous slurry (I), it may become an aqueous slurry or an aqueous solution. Therefore, these are collectively referred to as "aqueous slurry or aqueous solution (II)". When the catalyst has a composition represented by the formula (1), an element other than G contained in the composition represented by the formula (1) is mixed with water as the catalyst raw material, and the aqueous slurry (I) is mixed. ) Is preferably obtained.

When the aqueous slurry (I) is heated, the molybdenum raw material dissolves in water, and the dissolution rate at this time changes depending on the particle size distribution of the molybdenum raw material. It is presumed that this dissolution rate affects the active site of the obtained catalyst.

As the molybdenum raw material, a molybdenum oxide having a particle size of 6 μm or less and a particle size of 2 to 55% by volume is used in the frequency distribution curve obtained by measuring the particle size distribution. As a result, an active site suitable for vapor-phase catalytic oxidation of α, β-unsaturated aldehyde with molecular oxygen is formed. The lower limit of the ratio is preferably 5% by volume or more, more preferably 10% by volume or more. The upper limit is preferably 35% by volume or less, more preferably 30% by volume or less, further preferably 25% by volume or less, particularly preferably 20% by volume or less, and most preferably 15% by volume or less.

Further, in the molybdenum oxide, the proportion of particles having a particle size of 30 to 200 μm is preferably 35 to 90% by volume. The lower limit of the ratio is more preferably 40% by volume or more, further preferably 50% by volume or more, particularly preferably 60% by volume or more, and most preferably 70% by volume or more. Further, the upper limit is more preferably 85% by volume or less, and further preferably 80% by volume or less. As a result, a more suitable active site for vapor-phase catalytic oxidation of α, β-unsaturated aldehyde with molecular oxygen is formed.

The atomic ratio of molybdenum to oxygen in the molybdenum oxide is not particularly limited, and examples thereof include molybdenum dioxide having a molybdenum: oxygen atomic ratio of 1: 2 and molybdenum trioxide having an atomic ratio of 1: 3. However, from the viewpoint of further improving the yield of α, β-unsaturated carboxylic acid, 50% by mass or more of molybdenum trioxide having a particle size of 6 μm or less is 2 to 55% by volume is used as a molybdenum raw material. It is preferable to do so. The lower limit of the proportion of molybdenum trioxide is more preferably 70% by mass or more, further preferably 90% by mass or more. The molybdenum oxide may contain trace impurities such as sodium, potassium, iron, lead, sulfate root, nitrate root, and ammonium root, but the smaller the content of these impurities, the more preferable. It is particularly preferable that it does not contain the impurities of.

Examples of the method for producing the molybdenum oxide according to the present invention include the following methods. The crude molybdenum trioxide obtained by roasting an ore containing molybdenum is dispersed in pure water and then dissolved in aqueous ammonia. After filtering this solution, hydrochloric acid is added to adjust the pH, and the obtained precipitate is dispersed and washed with an aqueous solution containing a small amount of pure water, ammonium nitrate, ammonium chloride, or the like. Then, the water content is reduced by centrifugal filtration or the like to obtain a precursor precipitate, which is dried and then calcined to obtain a molybdenum oxide. Another method is to calcin the ammonium paramolybdate obtained by adding aqueous ammonia to the precursor precipitate to dissolve and crystallize it. The latter method can reduce the particle size of the molybdenum oxide obtained than the former method. Further, the particle size of the molybdenum oxide can be adjusted by the firing temperature. The particle size of the molybdenum oxide obtained by lowering the calcination temperature tends to decrease, and the particle size of the molybdenum oxide obtained by increasing the calcination temperature tends to increase. Further, with respect to the molybdenum oxide produced by the above method, the proportion of particles having a particle size of 6 μm or less is 2 to 55% by volume, preferably 2 to 35% by volume, and more preferably 2 to 15 volumes, if necessary. A crushing operation or a classification operation may be performed so as to be%. Examples of the crushing operation include a method using an apparatus such as a ball mill, a rod mill, a SAG mill, a self-made crushing mill, a pebble mill, a high-pressure crushing roll, a vertical axis impactor mill, and a jet mill. Examples of the classification operation include a method using a sieve, a method using gravity or centrifugal force (semi-free vortex type classifier, forced vortex type classifier), and the like. Further, as the molybdenum oxide according to the present invention, a mixture of a plurality of molybdenum oxides having different particle size distributions produced by the above-mentioned method may be used.

Examples of the phosphorus raw material include orthophosphoric acid, phosphorus pentoxide, ammonium phosphate, cesium phosphate and the like. These may be used alone or in combination of two or more.

The types of catalyst raw materials other than molybdenum raw materials and phosphorus raw materials are not particularly limited, and sulfates, nitrates, carbonates, bicarbonates, acetates, ammonium salts, oxides, hydroxides, chlorides, and halides of each element are not particularly limited. , Oxoic acid, oxolate salt and the like. Examples of the copper raw material include copper sulfate, copper nitrate, copper acetate, copper oxide, copper chloride and the like. Examples of the vanadium raw material include ammonium vanadate, ammonium metavanadate, vanadium pentoxide, vanadium chloride and the like. These may be used alone or in combination of two or more.

It is convenient to prepare the aqueous slurry or aqueous solution (II) containing the heteropolyacid by a method of stirring the aqueous slurry (I) obtained by adding a part or all of the catalyst raw materials to water while heating. preferable. The aqueous slurry (I) can also be obtained by adding an aqueous solution of the catalyst raw material, an aqueous slurry or an aqueous sol to water. It is preferable to heat the aqueous slurry (I) to 90 to 150 ° C. to obtain an aqueous slurry or an aqueous solution (II). The lower limit of the heating temperature is more preferably 95 ° C. or higher, and the upper limit is more preferably 130 ° C. or lower. By setting the heating temperature to 90 ° C. or higher, a heteropolyacid is efficiently produced from the catalyst raw material. Further, by setting the heating temperature to 150 ° C. or lower, evaporation of water in the aqueous slurry or aqueous solution can be suppressed.

As described above, when a molybdenum oxide having a particle size of 6 μm or less and a particle size of 2 to 55% by volume is used as the molybdenum raw material in the frequency distribution curve obtained by measuring the particle size distribution, the aqueous slurry (I) ) Is heated, and it is presumed that the dissolution rate when the molybdenum raw material is dissolved in water affects the active point of the obtained catalyst. At this time, the molybdenum raw material dissolves in water between the time when the temperature of the aqueous slurry (I) reaches 60 ° C. and the time when the temperature reaches 90 ° C. Therefore, by adjusting this time, a more suitable active site can be formed for the vapor phase catalytic oxidation of α, β-unsaturated aldehyde by molecular oxygen. The time from when the temperature of the aqueous slurry (I) reaches 60 ° C. to when it reaches 90 ° C. is preferably 5 to 40 minutes, more preferably 7 to 30 minutes.

In the aqueous slurry (I), the time from when the temperature reaches 60 ° C to when it reaches 90 ° C can be controlled by adjusting the temperature rising rate or the like. Further, the temperature of the aqueous slurry (I) may be monotonically increased, or may be controlled while appropriately changing the temperature rising rate.

The pH of the prepared aqueous slurry or aqueous solution (II) is preferably 4 or less, more preferably 2 or less, from the viewpoint of improving the yield of α, β-unsaturated carboxylic acid. When the pH of the aqueous slurry or aqueous solution (II) is high, it is preferable to select each raw material so as to contain a large amount of nitrate roots and the like.

Whether or not a heteropolymetalate is formed in the aqueous slurry or the aqueous solution (II) in the step (i) is determined by an infrared absorption analysis and an X-ray diffractometer using NICOLET6700FT-IR (product name, manufactured by Thermo electron) or the like. It can be confirmed by X-ray diffraction analysis using X'Pert PRO MPD (product name, manufactured by PANALTICAL) or the like.

(Step (ii))
In step (ii), a metal cation-containing compound is added to the aqueous slurry or aqueous solution (II) obtained in step (i) to obtain an aqueous slurry (III) in which a heteropolylate is precipitated. As the metal cation-containing compound, it is preferable to use a compound containing at least one element (corresponding to G in the above formula (1)) selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium. Further, in the step (ii), it is preferable to add an ammonium compound in addition to the metal cation-containing compound. By adding the ammonium compound, a crystal structure suitable for vapor-phase catalytic oxidation of α, β-unsaturated aldehyde with molecular oxygen is formed. Examples of the ammonium compound include ammonium hydrogen carbonate, ammonium carbonate, ammonium nitrate, aqueous ammonia and the like. These ammonium compounds may be used alone or in combination of two or more.

The metal cation-containing compound and the ammonium compound are preferably added after being dissolved or suspended in a solvent. Examples of the solvent include water, ethyl alcohol, acetone and the like. However, it is preferable to use the same water as the aqueous slurry or aqueous solution (II) obtained in the step (i) as the solvent. The stirring time of the aqueous slurry or aqueous solution after adding the metal cation-containing compound and the ammonium compound added as needed is preferably 1 to 300 minutes, the lower limit is preferably 10 minutes or more, and the upper limit is more preferably 30 minutes or less. The temperature of the aqueous slurry or aqueous solution during stirring is preferably 50 to 100 ° C., and the lower limit is more preferably 80 ° C. or higher. By setting the stirring time to 1 minute or more and the temperature to 50 ° C. or higher, the metal salt and ammonium salt of the heteropolyacid can be sufficiently formed. On the other hand, by setting the stirring time to 300 minutes or less and the temperature to 100 ° C. or less, the formation of compounds other than the target heteropolyacid metal salt and ammonium salt can be suppressed.

The heteropolylate to be precipitated (metal salt and ammonium salt of heteropolyacid) may have a kegin-type structure or a structure other than the kegin-type structure such as a Dawson-type structure, but α, β -From the viewpoint of improving the yield of unsaturated carboxylic acid, it is preferable to have a kegin-type structure. Examples of the method for precipitating the heteropolylate having a kegin-type structure include a method for adjusting the pH of the aqueous slurry (III) obtained in the step (ii) to 3 or less. For the structure of the precipitated heteropolylate, an infrared absorption analysis using NICOLET6700FT-IR (product name, manufactured by Thermo electron) and an X-ray diffractometer X'Pert PRO MPD (product name, manufactured by PANALTICAL) are used. It can be confirmed by the X-ray diffraction analysis.

(Step (iii))
In the step (iii), the aqueous slurry (III) obtained in the step (iii) is dried to obtain a dried catalyst precursor. Examples of the drying method include a drum drying method, an air flow drying method, an evaporation drying method, a spray drying method and the like. The drying temperature is preferably 120 to 500 ° C., the lower limit is 140 ° C. or higher, and the upper limit is 350 ° C. or lower. Drying can be carried out until the aqueous slurry (III) dries. The water content of the dried catalyst precursor is preferably 0.1 to 4.5% by mass. These conditions can be appropriately selected depending on the shape and size of the desired dried catalyst precursor.

(Molding process)
In the molding step, the dried catalyst precursor obtained in the step (iii) can be molded. Examples of the apparatus used for molding include powder molding machines such as a tableting molding machine, an extrusion molding machine, a pressure molding machine, and a rolling granulator. The shape of the molded product is not particularly limited, and any shape such as spherical granules, ring-shaped, cylindrical pellet-shaped, star-shaped, and granules crushed and classified after molding can be mentioned. At the time of molding, it may be supported on a carrier, and if necessary, a known additive such as graphite or talc or a known binder derived from an organic substance or an inorganic substance may be added. In the present invention, the dried catalyst precursor obtained in the step (iii) and the molded dried catalyst precursor are collectively referred to as a dried catalyst precursor.

(Process (iv))
In the step (iv), the dried catalyst precursor obtained in the step (iii) or the molding step is heat-treated to obtain a catalyst. The heat treatment conditions are not particularly limited, but can be carried out under the flow of at least one of an oxygen-containing gas such as air and an inert gas, for example. The heat treatment temperature is preferably 200 to 500 ° C., more preferably the lower limit is 300 ° C. or higher and the upper limit is 450 ° C. or lower. The heat treatment time is preferably 0.5 to 40 hours, and the lower limit is more preferably 1 hour or more. If the molding step is not performed after the step (iii), the molding step may be performed on the catalyst after the heat treatment obtained in the step (iv).

[Method for producing α, β-unsaturated carboxylic acid]
In the present invention, a catalyst for producing α, β-unsaturated carboxylic acid is produced by the method according to the present invention, and α, β-unsaturated aldehyde is vapor-phase catalytically oxidized with molecular oxygen using the catalyst to produce α, β-unsaturated carboxylic acid. Produces β-unsaturated carboxylic acids. Further, in the method for producing an α, β-unsaturated carboxylic acid according to the present invention, an α, β-unsaturated aldehyde is produced using a catalyst for producing an α, β-unsaturated carboxylic acid produced by the method according to the present invention. Is a method for producing α, β-unsaturated carboxylic acid by vapor-phase catalytic oxidation with molecular oxygen.

In the method according to the present invention, examples of the α, β-unsaturated aldehyde include (meth) acrolein, crotonaldehyde (β-methylacrolein), and cinnamaldehyde (β-phenylacrolein). Above all, from the viewpoint of the yield of the target product, (meth) acrolein is preferable, and methacrolein is more preferable. The α, β-unsaturated carboxylic acid produced is an α, β-unsaturated carboxylic acid in which the aldehyde group of the α, β-unsaturated aldehyde is converted into a carboxyl group. Specifically, when the α, β-unsaturated aldehyde is (meth) acrolein, (meth) acrylic acid is obtained. In addition, "(meth) acrolein" indicates acrolein and methacrolein, and "(meth) acrylic acid" indicates acrylic acid and methacrylic acid.

Hereinafter, as a representative example, a method for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen in the presence of a catalyst for producing methacrylic acid produced by the method according to the present invention will be described.

In this method, methacrylic acid is produced by contacting a raw material gas containing methacrolein and molecular oxygen with a catalyst according to the present invention. A fixed bed reactor can be used for this reaction. Specifically, the reaction can be carried out by filling the reaction tube with a catalyst and supplying the raw material gas to the reactor. The catalyst layer may be one layer, or a plurality of catalysts having different activities may be divided into a plurality of layers and filled. Further, in order to control the activity, the catalyst for producing methacrylic acid may be diluted with an inert carrier and filled.

The concentration of methacrolein in the raw material gas is not particularly limited, but is preferably 1 to 20% by volume, more preferably 3% by volume or more at the lower limit and 10% by volume or less at the upper limit. The raw material, methacrolein, may contain a small amount of impurities such as lower saturated aldehyde that do not substantially affect the reaction.

The concentration of molecular oxygen in the raw material gas is preferably 0.4 to 4 mol, more preferably 0.5 mol or more, and an upper limit of 3 mol or less with respect to 1 mol of methacrolein. As the molecular oxygen source, air is preferable from the viewpoint of economy. If necessary, a gas enriched with molecular oxygen by adding pure oxygen to air may be used.

The raw material gas may be a gas obtained by diluting methacrolein and molecular oxygen with an inert gas such as nitrogen or carbon dioxide. Further, water vapor may be added to the raw material gas. By carrying out the reaction in the presence of water vapor, methacrylic acid can be obtained in a higher yield. The concentration of water vapor in the raw material gas is preferably 0.1 to 50% by volume, more preferably 1% by volume or more at the lower limit and 40% by volume or less at the upper limit.

The contact time between the raw material gas and the catalyst for producing methacrylic acid is preferably 1.5 to 15 seconds. The reaction pressure is preferably 0.1 to 1 MPa (G). However, (G) means that it is a gauge pressure. The reaction temperature is preferably 200 to 450 ° C., the lower limit is 250 ° C. or higher, and the upper limit is 400 ° C. or lower.

[Method for producing α, β-unsaturated carboxylic acid ester]
The method for producing an α, β-unsaturated carboxylic acid ester according to the present invention is a method for esterifying an α, β-unsaturated carboxylic acid produced by the method according to the present invention. Further, in the method for producing an α, β-unsaturated carboxylic acid ester according to the present invention, α, β-unsaturated carboxylic acid is produced by the method according to the present invention, and the α, β-unsaturated carboxylic acid is esterified. How to do it. According to these methods, α, β-unsaturated carboxylic acid ester can be obtained by using α, β-unsaturated carboxylic acid obtained by vapor phase catalytic oxidation of α, β-unsaturated aldehyde. The alcohol to be reacted with α, β-unsaturated carboxylic acid is not particularly limited, and examples thereof include methanol, ethanol, isopropanol, n-butanol, isobutanol and the like. Examples of the obtained α, β-unsaturated carboxylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. The reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The reaction temperature is preferably 50 to 200 ° C.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. “Parts” in Examples and Comparative Examples means parts by mass. Analysis of the source gas and product was performed using gas chromatography. From the result of gas chromatography, the yield of methacrylic acid was calculated by the following formula.

Methacrylic acid yield (%) = (B / A) x 100
In the formula, A is the number of moles of methacrolein supplied to the reactor, and B is the number of moles of methacrylic acid produced.

To measure the particle size distribution of molybdenum trioxide, 0.02 to 0.1 g of molybdenum trioxide was dispersed in 500 g of pure water using a laser diffraction type particle size distribution measuring device SALD-7000 (product name, manufactured by Shimadzu Corporation). It was allowed to stir for 30 seconds.

(Example 1)
In 400 parts of pure water, 100 parts of molybdenum trioxide (ratio of particles having a particle size of 6 μm or less: 2.9% by volume) having the particle size distribution shown as Example 1 in FIG. 1, 3.4 parts of ammonium metavanadate, A dilution of 9.4 parts of an 85 mass% aqueous phosphate solution diluted with 6.0 parts of pure water, and a solution of 2.1 parts of copper (II) nitrate trihydrate dissolved in 4.5 parts of pure water. Addition gave an aqueous slurry (I). The aqueous slurry (I) was heated from 25 ° C. to 95 ° C. with stirring and stirred for 2 hours while maintaining the liquid temperature at 95 ° C. to obtain an aqueous slurry (II) containing a heteropolyacid. At this time, the time from when the temperature of the aqueous slurry (I) reached 60 ° C. to when it reached 90 ° C. was 15 minutes. Further, while maintaining the liquid temperature at 95 ° C. and stirring, a solution in which 13.5 parts of cesium bicarbonate was dissolved in 24 parts of pure water and a solution in which 9.2 parts of ammonium carbonate were dissolved in 26 parts of pure water were added dropwise. Stirring allowed the cesium and ammonium salts of the heteropolyacid to precipitate. The precipitated heteropolyacid cesium salt and ammonium salt had a kegin-type structure. Then, the mixture was stirred for 15 minutes while keeping the liquid temperature at 95 ° C. The obtained aqueous slurry (III) was dried with a spray dryer to obtain a dried catalyst precursor. The obtained dried catalyst precursor was extruded into a columnar shape having a diameter of 5.5 mm and a height of 5.5 mm, and heat-treated at 380 ° C. for 10 hours under air flow to produce a catalyst. The composition of the catalyst other than oxygen was P _1.4 Mo ₁₂ V _0.5 Cu _0.15 Cs _1.2 .

The catalyst is filled in a reaction tube, and a raw material gas having 5% by volume of metachlorine, 10% by volume of oxygen, 30% by volume of water vapor, and 55% by volume of nitrogen is used at a reaction temperature of 310 ° C. and a contact time between the raw material gas and the catalyst. It took 7.1 seconds. The product obtained from the reactor was collected and analyzed by gas chromatography to calculate the methacrylic acid yield. The results are shown in Table 1.

(Examples 2 to 4, Comparative Examples 1 to 3)
Instead of 100 parts of molybdenum trioxide used in Example 1, molybdenum trioxide having a particle size distribution shown in each Example and Comparative Example in FIG. 1 (the proportion of particles having a particle size of 6 μm or less is shown in Table 1). A catalyst was produced in the same manner as in Example 1 except that 100 parts were used, and the methacrylic acid yield was calculated. The results are shown in Table 1. In Examples 2 to 4 and Comparative Examples 1 to 3, the precipitated heteropolyacid cesium salt and ammonium salt had a kegin-type structure as in Example 1.

(Examples 5 to 8)
In Example 1, the catalyst was used in the same manner as in Example 1 except that the time from when the temperature of the aqueous slurry (I) reached 60 ° C. to when it reached 90 ° C. was adjusted as shown in Table 1. It was produced and the yield of methacrylic acid was calculated. The results are shown in Table 1. In Examples 5 to 8, as in Example 1, the precipitated heteropolyacid cesium salt and ammonium salt had a kegin-type structure.

As shown in Table 1, in Examples 1 to 8 in which molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less in the particle size distribution was 2 to 55% by volume was used as the molybdenum raw material, methacryl was obtained in a high yield. Acid was obtained. Further, among Examples 1 to 8, Examples 1 to 6 in which the time from when the temperature of the aqueous slurry (I) reaches 60 ° C to reaching 90 ° C is within the range of 5 to 40 minutes are higher. Examples 1 to 4, which had a high methacrylic acid yield and was in the range of 7 to 30 minutes, had a particularly high methacrylic acid yield. On the other hand, in Comparative Examples 1 to 3 in which the molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less in the particle size distribution was out of the above range was used as the molybdenum raw material, the methacrylic acid yields were all compared with those in Examples. Became low.

This application claims priority on the basis of Japanese application Japanese Patent Application No. 2017-203592 filed on October 20, 2017, and incorporates all of its disclosures herein.

Although the present invention has been described above with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples. Various changes that can be understood by those skilled in the art can be made within the scope of the present invention in terms of the structure and details of the present invention.

According to the present invention, it is possible to provide a catalyst for producing α, β-unsaturated carboxylic acid, which can produce α, β-unsaturated carboxylic acid from α, β-unsaturated aldehyde in a high yield. Industrially useful.

Claims (12)

As a molybdenum raw material, a catalyst for producing α, β-unsaturated carboxylic acid using molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less is 2 to 55% by volume in the frequency distribution curve obtained by measuring the particle size distribution. It is a manufacturing method of
(I) An aqueous slurry (I) obtained by mixing water with a catalyst raw material containing at least the molybdenum raw material and a phosphorus raw material is heated to 90 to 150 ° C. to prepare an aqueous slurry or an aqueous solution (II) containing a heteropolyacid. The process of obtaining and
(Ii) A step of adding a metal cation-containing compound to the aqueous slurry or aqueous solution (II) to obtain an aqueous slurry (III) in which a heteropolylate is precipitated.
(Iii) A step of drying the aqueous slurry (III) to obtain a dried catalyst precursor, and
(Iv) A step of heat-treating the dried catalyst precursor to obtain a catalyst, and
In the step (i), the time from when the temperature of the aqueous slurry (I) reaches 60 ° C. to when it reaches 90 ° C. is 5 to 40 minutes, α, β-unsaturated carboxylic acid. A method for producing a catalyst for producing an acid . The α, β- deficiency according to claim 1 , wherein in the step (i), the time from when the temperature of the aqueous slurry (I) reaches 60 ° C. to when it reaches 90 ° C. is 7 to 30 minutes. A method for producing a catalyst for producing a saturated carboxylic acid. The method for producing an α, β-unsaturated carboxylic acid production catalyst according to claim 1 or 2 , wherein the molybdenum raw material is a molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less is 2 to 35% by volume. .. The method for producing a catalyst for producing an α, β-unsaturated carboxylic acid according to claim 3 , wherein the molybdenum raw material is a molybdenum oxide in which the proportion of particles having a particle size of 6 μm or less is 2 to 15% by volume. The α, β-unsaturated carboxylic acid production catalyst according to any one of claims 1 to 4 , wherein the α, β-unsaturated carboxylic acid production catalyst has a composition represented by the following formula (1). Method for producing catalyst.
P _a Mo _b V _c Cu _d A _e E _f G _{g Oh} (1)
(In formula (1), P, Mo, V, Cu and O are element symbols indicating phosphorus, molybdenum, vanadium, copper and oxygen, respectively. A is antimony, bismuth, arsenic, germanium, zirconium, tellurium, respectively. Represents at least one element selected from the group consisting of silver, selenium, silicon, tungsten and boron, where E represents iron, zinc, chromium, magnesium, calcium, strontium, tantalum, cobalt, nickel, manganese, barium, titanium, Represents at least one element selected from the group consisting of tin, lead, niobium, indium, sulfur, palladium, gallium, cerium and lanthanum, where G is selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and tarium. Represents at least one element to be formed. A to h represent the atomic ratio of each element, and when b = 12, a = 0.5 to 3, c = 0.01 to 3, d = 0.01. ~ 2, e = 0-3, f = 0-3, g = 0.01-3, and h is the atomic ratio of oxygen required to satisfy the atomic value of each element.) The method for producing an α, β-unsaturated carboxylic acid production catalyst according to any one of claims 1 to 5 , wherein 50% by mass or more of molybdenum trioxide is used as the molybdenum raw material. The method for producing an α, β-unsaturated carboxylic acid production catalyst according to claim 6 , wherein 70% by mass or more of molybdenum trioxide is used as the molybdenum raw material. The α, β-unsaturated carboxylic acid production catalyst is a catalyst used for producing α, β-unsaturated carboxylic acid by vapor-phase catalytic oxidation of α, β-unsaturated aldehyde with molecular oxygen. The method according to any one of claims 1 to 7 , wherein the α, β-unsaturated aldehyde is (meth) acrolein, and the α, β-unsaturated carboxylic acid is (meth) acrylic acid. A method for producing a catalyst for producing α, β-unsaturated carboxylic acid. A catalyst for producing an α, β-unsaturated carboxylic acid is produced by the method according to any one of claims 1 to 8 , and the α, β-unsaturated aldehyde is vapor-phase contacted with molecular oxygen using the catalyst. A method for producing an α, β-unsaturated carboxylic acid, which is oxidized to produce an α, β-unsaturated carboxylic acid. Using the α, β-unsaturated carboxylic acid production catalyst produced by the method according to any one of claims 1 to 8 , the α, β-unsaturated aldehyde is vapor-phase catalytically oxidized with molecular oxygen. A method for producing an α, β-unsaturated carboxylic acid. A method for producing an α, β-unsaturated carboxylic acid ester, which esterifies the α, β-unsaturated carboxylic acid produced by the method according to claim 9 or 10. A method for producing an α, β-unsaturated carboxylic acid ester, wherein the α, β-unsaturated carboxylic acid is produced by the method according to claim 9 or 10, and the α, β-unsaturated carboxylic acid is esterified.

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