JP7468291B2 - Method for producing catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids - Google Patents

Description

The present invention relates to a method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids. More specifically, the present invention relates to a method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, which is used in producing unsaturated aldehydes and unsaturated carboxylic acids by catalytically oxidizing an olefin such as propylene or isobutylene with an oxygen-containing gas in the gas phase.

Catalysts that produce unsaturated aldehydes and unsaturated carboxylic acids by catalytically oxidizing olefins such as propylene and isobutylene with oxygen-containing gas in the gas phase generally contain molybdenum as an essential component. Specifically, catalysts used in the production of acrolein and acrylic acid from propylene and other raw materials, and catalysts used in the production of methacrolein and methacrylic acid from isobutylene and other raw materials, and improvements to the production methods thereof, are being vigorously pursued from various perspectives.

The method for producing unsaturated aldehydes and unsaturated carboxylic acids involves catalytic oxidation of olefins such as propylene and isobutylene with an oxygen-containing gas in the gas phase in a fixed-bed reactor packed with a catalyst.

The catalyst packed into the fixed bed reactor has a shape such as a cylinder, ring, tablet, or sphere, and generally, a catalyst formed by molding a powder of catalytically active components, or a catalyst in which catalytic component elements are supported on an inert carrier having a shape similar to the above shapes, is used.

Patent Document 1 discloses that by using a catalyst for oxidizing olefins such as propylene and isobutylene, which contains molybdenum, bismuth, cobalt, nickel, and iron, has a specific pore volume, and is crushed under specific crushing conditions, sufficient mechanical strength and catalytic performance in the production of unsaturated aldehydes and unsaturated carboxylic acids can be obtained.
Furthermore, Patent Document 2 discloses that by using a supported catalyst having a specific shape, in which a catalyst powder containing molybdenum as an essential component and which may also contain bismuth, vanadium, etc. is coated on an inert carrier, sufficient catalytic performance in the production of unsaturated aldehydes and unsaturated carboxylic acids can be obtained.

WO2019/182089 Brochure WO2009/147965 Brochure

However, even when using previously known catalysts for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, the mechanical strength of the catalysts produced and the catalytic performance, such as the raw material conversion rate and product selectivity, were not necessarily satisfactory.

The present invention has been made to solve the above problems. That is, the object of the present invention is to provide a catalyst for use in synthesizing the corresponding unsaturated aldehydes, such as acrolein and methacrolein, and unsaturated carboxylic acids, such as acrylic acid and methacrylic acid, by gas-phase catalytic oxidation of olefins, such as propylene and isobutylene, with an oxygen-containing gas, which has excellent conversion of the raw material, high selectivity for the desired unsaturated aldehydes and unsaturated carboxylic acids, can be produced in high yields, has high mechanical strength, and is capable of stable gas-phase catalytic oxidation reactions for a long period of time, even under conditions of high catalyst load.

As a result of intensive research conducted by the present inventors to solve the above problems, they have discovered a method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, which includes a molding step of introducing a carrier, a powder containing catalytic component elements, and a binder into a granulator, and supporting the powder containing the catalytic component elements on the carrier to form a catalyst precursor, in which the carrier is introduced into the granulator, and then a specific amount of binder relative to the amount of the carrier is introduced, and further the powder containing the catalytic component elements and a specific amount of binder relative to the amount of the carrier are introduced to form a catalyst precursor, and the produced catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids has high strength and Furthermore, when the catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids is used to carry out gas-phase catalytic oxidation of olefins such as propylene and isobutylene with an oxygen-containing gas, the conversion rate of olefins such as propylene and isobutylene is excellent even under conditions of high load on the catalyst, and the selectivity of unsaturated aldehydes such as acrolein and methacrolein, and unsaturated carboxylic acids such as acrylic acid and methacrylic acid is good, and as a result, it has been found possible to improve the yield of unsaturated aldehydes such as acrolein and methacrolein, and unsaturated carboxylic acids such as acrylic acid and methacrylic acid, which led to the present invention.

That is, the present invention relates to the following.
[1] A method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, comprising a molding step of introducing a carrier, a powder containing catalytic component elements, and a binder into a granulator, and supporting the powder containing the catalytic component elements on the carrier to form a catalyst precursor, wherein the carrier is introduced into the granulator, and then a binder is introduced in an amount of 0.5% by mass or more and 40% by mass or less relative to the amount of the carrier, and further the powder containing the catalytic component elements and a binder in an amount of 5% by mass or more and 50% by mass or less relative to the amount of the carrier are introduced to form the catalyst precursor.

[2] The method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids according to [1], wherein the total amount of binders introduced into the granulator is 10% by mass or more and 60% by mass or less relative to the amount of carriers introduced into the granulator.
[3] The method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids according to [1] or [2], wherein the total amount of binder introduced into the granulator is 10% by mass or more and 70% by mass or less relative to the amount of powder containing the catalyst component elements introduced into the granulator.
[4] The method for producing a catalyst for synthesizing an unsaturated aldehyde and an unsaturated carboxylic acid according to any one of [1] to [3], wherein the binder contains an organic compound.

[5] A method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids according to any one of [1] to [4], wherein a catalyst component element of the catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids is represented by the following formula (1):
_{Mo12Bi aFe b} Co _c Ni _d X _e Y _f Z _g Si _h O _i (1)
(In formula (1), X represents at least one element selected from the group consisting of Na, K, Rb, Cs, and Tl; Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Mn, and Zn; and Z represents at least one element selected from the group consisting of F, Cl, B, P, As, W, and Nb. a to i represent atomic ratios of each element and are in the ranges of 0.5≦a≦7, 0.05≦b≦5, 0≦c≦10, 0≦d≦10, 0≦e≦2, 0≦f≦5, 0≦g≦5, and 0≦h≦500, and i is a value that satisfies the oxidation state of other elements.)

[6] A method for producing acrolein and acrylic acid by gas-phase catalytic oxidation of propylene with an oxygen-containing gas using a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids produced by the method described in any one of [1] to [5].

The catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids produced by the production method of the present invention has high mechanical strength, and when olefins such as propylene and isobutylene are subjected to gas-phase contact oxidation with an oxygen-containing gas using the catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, the conversion rate of olefins such as propylene and isobutylene is excellent even under conditions of high load on the catalyst, and the selectivity of unsaturated aldehydes such as acrolein and methacrolein and unsaturated carboxylic acids such as acrylic acid and methacrylic acid is good. As a result, the yield of unsaturated aldehydes such as acrolein and methacrolein and unsaturated carboxylic acids such as acrylic acid and methacrylic acid can be improved, and the strength of the catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids produced can be improved, enabling a stable gas-phase contact oxidation reaction for a long period of time.

The following describes in detail the embodiments of the present invention. Note that the present invention is not limited to the following description, and can be modified in various ways within the scope of the gist of the invention.

The method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids (hereinafter, sometimes simply referred to as "catalyst") according to the present invention will be described in detail.
The catalyst according to the present invention is a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, which are produced by gas-phase catalytic oxidation of olefins such as propylene and isobutylene (hereinafter, sometimes simply referred to as "olefins") as raw materials with an oxygen-containing gas to produce unsaturated aldehydes such as acrolein and methacrolein (hereinafter, sometimes simply referred to as "unsaturated aldehydes"), and unsaturated carboxylic acids such as acrylic acid and methacrylic acid (hereinafter, sometimes simply referred to as "unsaturated carboxylic acids").

[Catalyst manufacturing method]
The method for producing the catalyst of the present invention includes a molding step of introducing a carrier, powders containing the constituent elements of the catalyst (hereinafter sometimes referred to as "catalyst component elements"), and a binder into a granulator to obtain a catalyst precursor.
This molding process is characterized in that the carrier is first introduced into the granulator, then a specific amount of binder relative to the amount of the carrier is introduced, and then a powder containing the catalyst component elements and a specific amount of binder relative to the amount of the carrier are introduced, thereby obtaining a catalyst precursor.

The powder containing the catalyst component elements can be obtained by the following steps: Namely, the steps include a step of using a compound having the catalyst component elements as a catalyst source compound (hereinafter referred to as "source compound"), adding each source compound having the catalyst component elements to a solvent or solution to combine them, and heating as necessary to obtain a prepared solution (liquid preparation step), and a step of drying the prepared solution to obtain a powder (drying step).
In addition, the catalyst precursor obtained in the molding step can be converted into a catalyst by calcining the catalyst precursor (calcination step).

[Liquid preparation process]
The liquid preparation step is a step of combining the respective supply source compounds containing the catalyst component elements in an aqueous system and heating the combined mixture to obtain a prepared liquid.
The integration in an aqueous system refers to the integration of each supply source compound by adding it to an aqueous solvent or solution. The aqueous solvent is an aqueous medium for dissolving or suspending each supply source compound, and refers to water, an organic solvent compatible with water such as methanol or ethanol, or a mixture thereof. The aqueous solution refers to a liquid in which one or more supply source compounds are dissolved, suspended, or integrated in the aqueous solvent.

The integration mentioned above refers to mixing the aqueous solutions or aqueous dispersions of the source compounds of the catalyst component elements all at once or in stages, and heating as necessary. Specific examples include a method of mixing the source compounds all at once, a method of mixing the source compounds all at once and then heating, a method of mixing the source compounds in stages, a method of repeatedly mixing the source compounds in stages and heating them, and a combination of these methods, all of which are included in the concept of integration of the source compounds of the catalyst component elements.

The heating mentioned above refers to stirring the mixed liquid or mixed dispersion obtained in the integration step at a specified temperature for a specified time. This heating increases the viscosity of the mixed liquid or mixed dispersion, which in the case of a mixed dispersion, reduces settling of solid components therein, and is particularly effective in suppressing the components from becoming non-uniform in the subsequent drying step, improving the catalytic activity of the catalyst, which is the final product obtained, such as the raw material conversion rate and product selectivity.

The heating temperature is preferably 60°C to 100°C, more preferably 60°C to 90°C, and even more preferably 60°C to 80°C. By keeping the heating temperature within the above range, the activity of the produced catalyst may be good.

The heating time is preferably 2 to 12 hours, more preferably 3 to 8 hours. By keeping the heating time within the above range, the activity of the produced catalyst may be improved.
As the stirring method, any method can be adopted, and examples thereof include a method using a stirrer having stirring blades and a method using external circulation with a pump.

[Source Compounds]
This catalyst preferably contains molybdenum (Mo), bismuth (Bi), and iron (Fe) as catalytic component elements, and more preferably contains cobalt (Co) and nickel (Ni) as other catalytic component elements. In addition, the catalyst may contain one or more of the following components: sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), titanium (Ti), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), manganese (Mn), zinc (Zn), fluorine (F), chlorine (Cl), boron (B), phosphorus (P), arsenic (As), tungsten (W), niobium (Nb), silicon (Si), and the like.

Examples of the molybdenum (Mo) source compound include ammonium paramolybdate, molybdenum trioxide, molybdic acid, ammonium phosphomolybdate, and phosphomolybdic acid.

Examples of the bismuth (Bi) supply source compound include bismuth chloride, bismuth nitrate, bismuth oxide, and bismuth subcarbonate. The amount of bismuth added is preferably such that, when the atomic ratio of the catalyst component elements is 12 molybdenum atoms, the ratio is 0.5 to 7, more preferably 0.5 to 5, even more preferably 0.5 to 4, and particularly preferably 0.5 to 3. By being within this range, the catalyst can be one that has excellent raw material conversion and can produce unsaturated aldehydes and unsaturated carboxylic acids with high selectivity.

Examples of the iron (Fe) source compound include ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate. The amount of iron added is preferably such that, when the atomic ratio of the catalyst component elements is 12 molybdenum atoms, it is 0.05 to 5, more preferably 0.1 to 4, even more preferably 0.2 to 3, and particularly preferably 0.3 to 3. By being within this range, it is possible to obtain a catalyst that has excellent raw material conversion and can produce unsaturated aldehydes and unsaturated carboxylic acids with high selectivity.

Examples of the cobalt (Co) source compound include cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt carbonate, and cobalt acetate. The amount of cobalt added is preferably such that, when the molybdenum atoms are taken as 12, the atomic ratio of the catalyst component elements is 0 to 10, more preferably 0.5 to 9, even more preferably 1 to 8, and particularly preferably 2 to 7. By being within this range, the catalyst can be one that has excellent raw material conversion and can produce unsaturated aldehydes and unsaturated carboxylic acids with high selectivity.

Examples of the nickel (Ni) supply source compound include nickel nitrate, nickel sulfate, nickel chloride, nickel carbonate, nickel acetate, etc. The amount of nickel added is preferably such that, when the molybdenum atoms are taken as 12, the atomic ratio of the catalyst component elements is 0 to 10, more preferably 0.5 to 9, even more preferably 1 to 8, and particularly preferably 2 to 7. By being within this range, the catalyst can be one that has excellent raw material conversion and can produce unsaturated aldehydes and unsaturated carboxylic acids with high selectivity.

Examples of the sodium (Na) source compound include sodium chloride, sodium carbonate, sodium nitrate, sodium sulfate, sodium acetate, sodium borate, etc. Examples of the potassium (K) source compound include potassium nitrate, potassium sulfate, potassium chloride, potassium carbonate, potassium acetate, etc. Examples of the rubidium (Rb) source compound include rubidium nitrate, rubidium sulfate, rubidium chloride, rubidium carbonate, rubidium acetate, etc. Examples of the cesium (Cs) source compound include cesium nitrate, cesium sulfate, cesium chloride, cesium carbonate, cesium acetate, etc. Examples of the titanium (Ti) source compound include titanium oxide, titanium chloride, etc. The amount of at least one element selected from sodium, potassium, rubidium, cesium, and titanium added is preferably 0 to 2 when molybdenum is 12, more preferably 0.01 to 2, and even more preferably 0.02 to 2. By being within this range, the catalyst can be made to have excellent raw material conversion rate and produce unsaturated aldehydes and unsaturated carboxylic acids with high selectivity.

The magnesium (Mg) source compound may be magnesium oxide, magnesium carbonate, or magnesium sulfate. The calcium (Ca) source compound may be calcium oxide, calcium carbonate, or calcium hydroxide. The strontium (Sr) source compound may be strontium oxide, strontium carbonate, strontium hydroxide, or strontium nitrate. The barium (Ba) source compound may be barium oxide, barium carbonate, barium nitrate, barium acetate, or barium sulfate. The manganese (Mn) source compound may be manganese dioxide, manganese carbonate, or zinc. The zinc (Zn) source compound may be zinc oxide, zinc carbonate, zinc hydroxide, or zinc nitrate.
The amount of at least one element selected from the group consisting of magnesium, calcium, strontium, barium, manganese and zinc is preferably added so that, in terms of atomic ratio of the catalyst component elements, when molybdenum is 12, it is 0 to 5, more preferably 0 to 4, and further preferably 0 to 3. When the amount is within this range, a catalyst excellent in raw material conversion and capable of producing unsaturated aldehydes and unsaturated carboxylic acids with high selectivity can be obtained.

Examples of the fluorine (F) source compound include calcium fluoride and sodium fluoride. Examples of the chlorine (Cl) source compound include sodium chloride and ammonium chloride. Examples of the boron (B) source compound include borax, ammonium borate, and boric acid. Examples of the phosphorus (P) source compound include ammonium phosphomolybdate, ammonium phosphate, phosphoric acid, and phosphorus pentoxide. Examples of the arsenic (As) source compound include ammonium diarseno-18 molybdate and ammonium diarseno-18 tungstate.
The source compound of tungsten (W) includes tungstic acid or a salt thereof, etc. The source compound of niobium (Nb) includes niobium hydroxide, etc.
The amount of at least one element selected from fluorine, chlorine, boron, phosphorus, arsenic, tungsten and niobium added is preferably 0 to 5, more preferably 0 to 4, and even more preferably 0 to 3, when the amount of molybdenum is 12. When the amount is within this range, a catalyst having excellent raw material conversion and capable of producing unsaturated aldehydes and unsaturated carboxylic acids with high selectivity can be obtained.

Examples of the silicon (Si) supply source compound include silica, granular silica, colloidal silica, and fumed silica. The amount of silicon added is preferably such that, when the atomic ratio of the catalyst component elements is 12 for molybdenum atoms, it is 0 to 500, more preferably 0 to 400, and even more preferably 0 to 300. By being within this range, it is possible to obtain a catalyst that has excellent raw material conversion and can produce unsaturated aldehydes and unsaturated carboxylic acids with high selectivity.

[Method of adding source compound]
In the above-mentioned solution preparation step, all of the supply source compounds may be prepared as one preparation solution, or each supply source compound may be prepared individually or in several groups as a plurality of preparation solutions, and the plurality of preparation solutions may be mixed together or in sequence to prepare a single preparation solution, or one or more preparation solutions may be dried and further calcined to form a solid, and the solid may be added to a preparation solution of the remaining supply source compounds to prepare a new preparation solution.

[Drying process]
The obtained preparation liquid is dried in a drying step to obtain a powder containing the catalyst component elements (hereinafter, may be simply referred to as "powder".) The drying method in this drying step is not particularly limited, and for example, a normal spray dryer, slurry dryer, drum dryer, etc. may be used to obtain the powder.

The powder obtained by the drying treatment may be further subjected to a heat treatment, if necessary. This heat treatment is a treatment carried out in air for a short period of time at a temperature range of 300°C to 600°C, preferably 350°C to 550°C. There are no particular limitations on the method, and for example, the powder may be heated in a fixed state using a normal box-type heating furnace, a tunnel-type heating furnace, or the like, or the powder may be heated while being fluidized using a rotary kiln, or the like.
In addition, a dried product that has been further subjected to a treatment such as pulverization is also included in the powder of the present invention.

The catalyst component elements of the powder obtained by the drying process preferably contain molybdenum and bismuth, more preferably contain iron, and even more preferably are represented by the following general formula (1). By setting the catalyst component elements of the powder within the above range, the produced catalyst has high mechanical strength, excellent raw material conversion even under high load conditions, and good selectivity for unsaturated aldehydes and unsaturated carboxylic acids, making it possible to improve the yield of unsaturated aldehydes and unsaturated carboxylic acids.

_{Mo12Bi aFe b} Co _c Ni _d X _e Y _f Z _g Si _h O _i (1)
(In formula (1), X represents at least one element selected from the group consisting of Na, K, Rb, Cs, and Tl; Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Mn, and Zn; and Z represents at least one element selected from the group consisting of F, Cl, B, P, As, W, and Nb. a to i represent atomic ratios of each element and are in the ranges of 0.5≦a≦7, 0.05≦b≦5, 0≦c≦10, 0≦d≦10, 0≦e≦2, 0≦f≦5, 0≦g≦5, and 0≦h≦500, and i is a value that satisfies the oxidation state of other elements.)

[Molding process]
The molding step is a step in which the carrier, the powder obtained in the drying step, and a binder are introduced into a granulator to obtain a catalyst precursor.

A specific example of the molding process is a process in which a granulator, for example a granulator having a flat or uneven disk at the bottom of the granulator, is used, and the disk of the granulator is rotated to agitate the carrier introduced into the granulator by repeated rotation and revolution, and a powder containing catalyst component elements and a binder are introduced therein, and other additives are optionally added, and the powder is supported on the carrier to obtain a catalyst precursor (hereinafter sometimes referred to as "rolling granulation method").

The carrier may be a spherical carrier such as silica, silicon carbide, alumina, mullite, or alundum, with a major axis diameter of preferably 2.5 mm to 10 mm, and more preferably 2.5 mm to 6 mm. Of these, the porosity of the carrier is preferably 20% to 60%, more preferably 30% to 57%, and even more preferably 40% to 55%. The water absorption of the carrier is preferably 10% to 60%, more preferably 12% to 50%, and even more preferably 15% to 40%. By setting the porosity and water absorption of the carrier within the above ranges, powder containing catalyst component elements can be easily supported on the carrier. It is preferable that the carrier is inactive in the reaction of gas-phase catalytic oxidation of olefins with an oxygen-containing gas.

In the method for producing the catalyst of the present invention, a carrier is introduced into the granulator, and then a binder (hereinafter sometimes referred to as "binder A") in an amount of 0.5% by mass or more and 40% by mass or less relative to the amount of the carrier is introduced into the granulator, and further a powder containing the catalyst component elements and a binder (hereinafter sometimes referred to as "binder B") in an amount of 5% by mass or more and 50% by mass or less relative to the amount of the carrier are introduced.
The upper limit of the amount of binder A relative to the amount of the carrier is preferably 38% by mass, more preferably 35% by mass, and even more preferably 32% by mass. The lower limit of the amount of binder A relative to the amount of the carrier is preferably 0.6% by mass, and more preferably 0.7% by mass.
The upper limit of the amount of binder B relative to the amount of the carrier is preferably 48% by mass, more preferably 46% by mass, and even more preferably 45% by mass. The lower limit of the amount of binder B relative to the amount of the carrier is preferably 6% by mass, and more preferably 7% by mass.

By setting the amounts of binder A and binder B within the above ranges, the produced catalyst has high mechanical strength, and even under high load conditions, has excellent raw material conversion, and has good selectivity for unsaturated aldehyde and unsaturated carboxylic acid, making it possible to improve the yield of unsaturated aldehyde and unsaturated carboxylic acid.
By introducing the carrier into the granulator and then introducing a specific amount of binder A relative to the amount of the carrier into the granulator, the carrier surface is covered with an appropriate amount of binder, making it possible to improve the adhesion between the powder containing the catalytic component elements and the carrier. Furthermore, by introducing the powder containing the catalytic component elements and a specific amount of binder B relative to the amount of the carrier, it is possible to form an optimal pore structure as a catalyst precursor. As a result, the produced catalyst has high mechanical strength and, even under high load conditions, has excellent raw material conversion, and has good selectivity for unsaturated aldehydes and unsaturated carboxylic acids, making it possible to improve the yields of unsaturated aldehydes and unsaturated carboxylic acids.

Examples of the binder include organic compounds such as ethylene glycol, glycerin, propionic acid, maleic acid, benzyl alcohol, propyl alcohol, butyl alcohol, polyvinyl alcohol, stearic acid, or phenol, and inorganic compounds such as sulfuric acid, ammonium sulfate, nitric acid, ammonium nitrate, ammonium carbonate, and water, and preferably contains an organic compound, more preferably contains an organic compound having a hydroxyl group, and further preferably contains glycerin and/or polyvinyl alcohol. By containing the compound as a binder, the produced catalyst has high mechanical strength, and even under high load conditions, has excellent raw material conversion, and has good selectivity for unsaturated aldehyde and unsaturated carboxylic acid, making it possible to improve the yield of unsaturated aldehyde and unsaturated carboxylic acid.
Incidentally, it is particularly preferable that the binder A among the binders contains an organic compound.
Furthermore, binder A and binder B may be the same binder or different binders.

When the binder is introduced into the granulator, it is preferably an aqueous solution, and the concentration is preferably 2% by mass or more and 40% by mass or less. The lower limit is more preferably 3% by mass. The upper limit is more preferably 30% by mass. By being in the above range, it becomes possible to uniformly disperse the binder into the carrier or powder inside the granulator.

The method for introducing the powder containing the catalyst component elements and the binder B into the granulator may be as follows:
(1) A method of preparing a homogeneous mixture by mixing powders containing catalyst component elements with binder B, and introducing the homogeneous mixture into a granulator;
(2) A method in which the powder containing the catalyst component elements and the binder B are simultaneously introduced into a granulator;
(3) A method in which a powder containing catalyst component elements is introduced into a granulator, and then a binder B is introduced into the granulator;
(4) A method in which a binder B is added to a powder containing catalyst component elements to form a heterogeneous mixture, and the heterogeneous mixture is introduced into a granulator;
(5) A method in which the powder containing the catalyst component elements and the binder B are separately introduced into the granulator simultaneously, alternately, or in random order.
In the present invention, any method can be adopted, such as adding the entire amount of a suitable combination of (1) to (5). Among these, in (5), it is preferable to adjust the addition speed using an autofeeder or the like so that a predetermined amount is supported on the carrier without adhesion of the powder containing the catalyst component elements to the inner wall of the granulator or aggregation of the powder containing the catalyst component elements.

In the method for producing a catalyst of the present invention, the above-mentioned methods (1) to (5) can be appropriately combined. However, the method (5) is preferred because the produced catalyst has high mechanical strength, and even under high load conditions, has excellent raw material conversion and good selectivity for unsaturated aldehyde and unsaturated carboxylic acid, and is likely to enable an improvement in the yield of unsaturated aldehyde and unsaturated carboxylic acid.
In the method (5), when a binder is introduced into the granulator prior to the powder containing the catalytically active component, the binder corresponds to binder A.

The total amount of binder introduced into the granulator relative to the amount of carrier introduced into the granulator is preferably 10% by mass or more and 60% by mass or less. The lower limit is more preferably 13% by mass, and even more preferably 15% by mass. The upper limit is more preferably 58% by mass, and even more preferably 55% by mass. By keeping it within the above range, the produced catalyst has high mechanical strength, and even under high load conditions, has excellent raw material conversion rate, and has good selectivity for unsaturated aldehydes and unsaturated carboxylic acids, making it possible to improve the yield of unsaturated aldehydes and unsaturated carboxylic acids.

The total amount of binder introduced into the granulator is preferably 10% by mass or more and 70% by mass or less relative to the amount of powder containing the catalyst component elements introduced into the granulator. The lower limit is more preferably 13% by mass, and even more preferably 15% by mass. The upper limit is more preferably 67% by mass, and even more preferably 64% by mass. By keeping it within the above range, the produced catalyst has high mechanical strength, and even under high load conditions, has excellent raw material conversion rate, and has good selectivity for unsaturated aldehydes and unsaturated carboxylic acids, making it possible to improve the yield of unsaturated aldehydes and unsaturated carboxylic acids.

The amount of powder containing the catalyst component elements relative to the amount of carrier introduced into the granulator is preferably 20% by mass or more and 300% by mass or less. The lower limit is more preferably 30% by mass, and even more preferably 40% by mass. The upper limit is more preferably 250% by mass, and even more preferably 200% by mass. By keeping it within the above range, the produced catalyst has high mechanical strength, and even under high load conditions, has excellent raw material conversion rate, and has good selectivity for unsaturated aldehydes and unsaturated carboxylic acids, making it possible to improve the yield of unsaturated aldehydes and unsaturated carboxylic acids.

In the molding process, in addition to the carrier, powder, and binder, other molding aids may be added. Examples of other molding aids include silica, alumina, glass, silicon carbide, silicon nitride, graphite, cellulose, methyl cellulose, and starch.

If the catalyst has low strength, the catalyst may be powdered or cracked when it is packed into a reaction tube or the like for producing an unsaturated aldehyde and an unsaturated carboxylic acid by gas-phase catalytic oxidation of an olefin with an oxygen-containing gas, and the pressure difference (pressure difference between the inlet and outlet of the reaction tube) may become large. If the pressure difference becomes large, a compressor that blows a raw material mixed gas containing an olefin and an oxygen-containing gas into the reaction tube packed with the catalyst may be subjected to a large load.
Furthermore, if the catalyst strength is low, the pulverization of the catalyst may accelerate in proportion to the progress of the gas phase catalytic oxidation, and the pressure difference may further increase over time.
Therefore, the powdering rate of the catalyst, which is an index of the strength of the catalyst, is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. The powdering rate indicates the ratio of the weight of fine particles to the weight of a catalyst sample when the catalyst is dropped from a height of 1 m.

[Firing process]
The catalyst precursor obtained in the molding step is calcined in a moderate oxygen atmosphere for about 1 hour to 16 hours at a temperature condition of preferably 400° C. to 600° C., more preferably 450° C. to 550° C. As the calcination method, the method used in the heat treatment in the drying step can be adopted.
In this manner, a catalyst having high mechanical strength, high activity, and excellent yields of the desired unsaturated aldehyde and unsaturated carboxylic acid can be obtained.
The obtained catalyst preferably contains molybdenum and bismuth as catalytic component elements, more preferably contains iron in addition to them, and even more preferably is represented by the following general formula (2): By controlling the catalytic component elements of the catalyst to be within the above ranges, the produced catalyst has high mechanical strength, is excellent in raw material conversion even under high load conditions, and has good selectivity for unsaturated aldehydes and unsaturated carboxylic acids, making it possible to improve the yields of unsaturated aldehydes and unsaturated carboxylic acids.

_{Mo12Bi aFe b} Co _c Ni _d X _e Y _f Z _g Si _h O _i (2)
(In formula (2), X represents at least one element selected from the group consisting of Na, K, Rb, Cs, and Tl; Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Mn, and Zn; and Z represents at least one element selected from the group consisting of F, Cl, B, P, As, W, and Nb. a to i represent atomic ratios of each element and are in the ranges of 0.5≦a≦7, 0.05≦b≦5, 0≦c≦10, 0≦d≦10, 0≦e≦2, 0≦f≦5, 0≦g≦5, and 0≦h≦500, and i is a value that satisfies the oxidation state of other elements.)
The catalytic component elements of the catalyst are those excluding the carrier from the catalyst.

[Application]
By using the catalyst produced by the production method of the present invention, it is possible to improve the catalytic performance such as high mechanical strength and raw material conversion rate and product selectivity, and it is possible to produce the corresponding unsaturated aldehydes such as acrolein and methacrolein, and unsaturated carboxylic acids such as acrylic acid and methacrolein in high yields by gas-phase catalytic oxidation of olefins such as propylene and isobutylene with an oxygen-containing gas.

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples in any way as long as the gist of the present invention is not exceeded.
The propylene conversion, the selectivities to acrolein and acrylic acid, and the yields of acrolein and acrylic acid are defined as shown in the following formulas (1) to (3).
(1) Propylene conversion rate (mol%)=100×(moles of reacted propylene)/(moles of supplied propylene)
(2) Acrolein and acrylic acid selectivity (mol%)=100×(moles of acrolein and acrylic acid produced)/(moles of propylene converted)
(3) Acrolein and acrylic acid yield (mol%)=100×(moles of acrolein and acrylic acid produced)/(moles of propylene supplied)

<Gas-phase catalytic oxidation of propylene>
A reaction tube with an inner diameter of 21.4 mm was filled with 13.3 ml of catalyst. A raw material mixed gas having the following composition was introduced from the inlet of the reaction tube, and the reaction was evaluated at a space velocity of 3064/hr. The heat transfer medium temperature was 380° C. The reaction evaluation results are shown in Table 1.
The composition of the raw material mixed gas used is as follows:
Propylene: 10% by volume, steam: 17% by volume, oxygen: 15% by volume, (nitrogen-containing inert gas + other gases): 58% by volume

<Measurement of catalyst powdering rate>
The catalyst was sieved through a sieve with a mesh size of 2.36 mm, and the catalyst on the sieve was used as a sample for measuring the powdering rate. A funnel (cone upper diameter 150 mm, cone lower diameter 25 mm) was inserted into the top of an acrylic cylinder (φ66 mm) with a height of 1 m, and a tray was placed at the bottom of the cylinder. Approximately 20 g of the sample for measuring the powdering rate was precisely weighed and placed in the top of the funnel's cone, and then dropped into the tray through the cylinder. The dropped sample for measuring the powdering rate was collected from the tray, and the weight (powdered weight) of the fine particles sieved through the sieve with a mesh size of 2.36 mm was measured, and the catalyst powdering rate was calculated from the following formula.
Catalyst powder rate (%) = (powder weight/weight of sample for powder rate measurement) x 100

Example 1
A container was charged with 1700 ml of warm water, and 447.2 g of ammonium molybdate was added and dissolved. Next, 2.1 g of potassium nitrate was added and dissolved. Next, 1.1 g of ammonium chloride was further added and dissolved to obtain a solution (hereinafter referred to as "Solution A").
Next, a solution obtained by dissolving 159.8 g of iron nitrate, 376.2 g of cobalt nitrate, and 174.1 g of nickel nitrate in 376 ml of warm water was added to solution A and mixed for 1 hour to become uniform (hereinafter referred to as "solution B"). Next, a solution obtained by dissolving 22.1 g of nitric acid and 96.5 g of bismuth nitrate in 104.8 ml of pure water at room temperature was added to solution B and mixed for 2 hours to become uniform, thereby obtaining a starting material mixture.
This mixture of starting materials was spray-dried at 150° C., and then heat-treated in air at a heating temperature of 440° C. for 6 hours to obtain a dried product.

The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 7.5% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Further, the mixed powder for support and 39.5% by mass of binder B relative to the amount of the carrier introduced into the granulator were each divided, and the divided mixed powder for support was alternately introduced to support the catalyst precursor, which was a molded body. The binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

Example 2
A dried product was obtained in the same manner as in Example 1.
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 5.0% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Furthermore, the mixed powder for support and 42.0% by mass of binder B relative to the amount of the carrier introduced into the granulator were each divided, and the divided mixed powder for support were alternately introduced to support the catalyst precursor, which was a molded body. The binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

Example 3
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 2.5% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Further, the mixed powder for support and 44.5% by mass of binder B relative to the amount of the support introduced into the granulator were each divided, and the divided mixed powder for support was alternately introduced to support the catalyst precursor, which was a molded body. The binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

Example 4
A dried product was obtained in the same manner as in Example 1.
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 10.0% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Furthermore, the mixed powder for support and 37.0% by mass of binder B relative to the amount of the carrier introduced into the granulator were each divided, and the divided mixed powder for support was alternately introduced to support the catalyst precursor, which was a molded body. The binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

Example 5
A dried product was obtained in the same manner as in Example 1.
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 12.5% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Furthermore, the mixed powder for support and 34.5% by mass of binder B relative to the amount of the support introduced into the granulator were each divided, and the divided mixed powder for support was alternately introduced to support the catalyst precursor, which was a molded body. The binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

Example 6
A dried product was obtained in the same manner as in Example 1.
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 30.0% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Furthermore, the mixed powder for support and 17.0% by mass of binder B relative to the amount of the support introduced into the granulator were each divided and introduced alternately from the divided mixed powder for support to support the catalyst, thereby obtaining a molded catalyst precursor. Note that the binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

(Comparative Example 1)
A dried product was obtained in the same manner as in Example 1.
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then the mixed powder for support and 47.0 mass% of a binder based on the amount of the carrier introduced into the granulator were divided and supported by alternately introducing the divided mixed powder for support first, thereby obtaining a molded catalyst precursor. The binder was glycerin and water, and was a 10 mass% aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

(Comparative Example 2)
A dried product was obtained in the same manner as in Example 1.
The dried product was pulverized to 200 μm or less using a stirring blade type pulverizer to obtain a pulverized product. This pulverized product was used as a support powder. 4.1 g of flake glass and 4.1 g of cellulose were added to 81.8 g of this support powder and mixed uniformly to obtain a support mixed powder.
100 g of a spherical inert carrier having a diameter of 4.5 mm and mainly composed of alumina-silica was introduced into a pan-type granulator, and then 45.0% by mass of binder A was introduced based on the amount of the carrier introduced into the granulator. The binder A was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
Furthermore, the mixed powder for support and 2.0% by mass of binder B relative to the amount of the support introduced into the granulator were each divided, and the divided mixed powder for support were alternately introduced to support the catalyst precursor, which was a molded body. The binder B was glycerin and water, and was a 10% by mass aqueous solution of glycerin.
This catalyst precursor was calcined in an air atmosphere at 510° C. for 2 hours to obtain a catalyst. The composition ratio of the catalyst component elements (excluding oxygen) of this catalyst was as follows:
_{Mo12Bi0.94Fe1.87Co6.30Ni2.84K0.1Cl0.1 ​ ​ ​ ​ ​ ​}
The results of evaluation of the gas phase catalytic oxidation reaction of propylene using the produced catalyst are shown in Table 1.

From the above, it can be seen that the production method of the present invention can produce a catalyst that has high mechanical strength, high propylene conversion rate, and high acrolein and acrylic acid selectivity, resulting in excellent acrolein and acrylic acid yields.

Claims (5)

A method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, comprising a molding step of introducing a carrier, a powder containing catalytic component elements, and a binder consisting of glycerin and water into a granulator consisting of a pan-type granulator, and supporting the powder containing the catalytic component elements on the carrier to form a catalyst precursor, comprising the steps of:
The support is introduced into the granulator, then a binder is introduced in an amount of 0.5% by mass or more and 40% by mass or less relative to the amount of the support, and further a powder containing the catalyst component elements and a binder in an amount of 5% by mass or more and 50% by mass or less relative to the amount of the support are introduced alternately in portions to form a catalyst precursor. This method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids is described above. The method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids according to claim 1, wherein the total amount of binder introduced into the granulator is 10% by mass or more and 60% by mass or less relative to the amount of carrier introduced into the granulator. 3. A method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids, as described in claim 1 or 2, wherein the total amount of binder introduced into the granulator is 10% by mass or more and 70% by mass or less relative to the amount of powder containing the catalyst component elements introduced into the granulator. 4. The method for producing a catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids according to claim 1, wherein a catalyst component element of the catalyst for synthesizing unsaturated aldehydes and unsaturated carboxylic acids is represented by the following formula (1):
_{Mo12Bi aFe b} Co _c Ni _d X _e Y _f Z _g Si _h O _i (1)
(In formula (1), X represents at least one element selected from the group consisting of Na, K, Rb, Cs, and Tl; Y represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Mn, and Zn; and Z represents at least one element selected from the group consisting of F, Cl, B, P, As, W, and Nb. a to i represent atomic ratios of each element and are in the ranges of 0.5≦a≦7, 0.05≦b≦5, 0≦c≦10, 0≦d≦10, 0≦e≦2, 0≦f≦5, 0≦g≦5, and 0≦h≦500, and i is a value that satisfies the oxidation state of other elements.) A method for producing acrolein and acrylic acid, comprising the step of catalytically oxidizing propylene with an oxygen-containing gas in the gas phase using a catalyst for synthesizing an unsaturated aldehyde and an unsaturated carboxylic acid produced by the method according to any one of claims 1 to 4.