SG193383A1

SG193383A1 - Method for producing catalyst for producing methacrylic acid

Info

Publication number: SG193383A1
Application number: SG2013068002A
Authority: SG
Inventors: Takuro Watanabe; Masahide Kondo; Tetsufumi Yamaguchi; Mieji Sugiyama
Original assignee: Mitsubishi Rayon Co
Priority date: 2011-04-11
Filing date: 2012-04-05
Publication date: 2013-10-30
Also published as: CN103459022B; WO2012141076A1; CN103459022A; KR20140024889A; KR101860595B1; JPWO2012141076A1; JP5888233B2

Abstract

31 AbstractMETHOD FOR PRODUCING CATALYST FOR PRODUCING METHACRYLIC ACIDA method for producing a catalyst for producing methacrylic acid used in producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen, the catalyst containing at least molybdenum and phosphorus as catalyst components, the method including: producing a dried material having an apparent density (X) of 1.00 to 1,80 kg/L.by drying an aqueous liquid mixture containing raw material compounds for catalyst components; and producing a catalyst molded body having a molded10 article density (Y) of 1.60 to 2.40 kgiL and a ratio of the apparent density (X) to the molded article density (Y), (X/Y), of 0,50 to 0.80 by molding the dried material or a mixture containing the dried material.

Description

Dascription

Title of Invention: METHOD FOR PRODUCING CATALYST FOR

PRODUCING METHACRYLIC ACID

Technical Field

[0001]

The present invention relates to a method for producing a catalyst used in producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen (hereinafter, referred to as a catalyst for producing methacrylic acid), and a catalyst produced by the method, and a method for producing methacrylic acid using the catalyst.

Background Art

[0002]

A heteropoly acid compound represented by phosphomolybdic acid has been known as a catalyst component for a catalyst for producing methacrylic acid. Further, a large number of methods for forming an effective pore structure in a catalyst in order to allow the catalyst component to work effectively in a catalytic gas-phase oxidation reaction have been proposed.

[0003]

In Patent Literature 1, there is proposed a method of molding a catalyst by adding a polymer organic compound that decomposes to a monomer and vaporizes at a relatively low temperature such as polymethyl methacrylate or polystyrene. In Patent Literature 2, there is proposed a method for producing a catalyst in which a dried material of a mixed solution or an aqueous slurry containing a catalyst component, the particle diameter of which is adjusted fo a range of 1 to 250 um is molded. In Patent Literature 3, there is proposed a method for producing a catalyst including: a step of making a primary molded article by mixing a particle including a catalyst component and a liquid; and further, a secondary molding step of molding the primary molded article with a piston molding machine to a final form,

Citation List

Patent Literature

[0004]

Patent Literature 1; JP04-367737A

Patent Literature 2; JP08-10621A

Patent Literature 3; JP2003-83882A

Summary of invention Technical Problem

[0005]

However, the development of a catalyst that is capable of further improving a yield of methacrylic acid in the catalytic gas-phase oxidation reaction of methacrolein has been desired.

[00086]

An object of the present invention is to provide a catalyst for producing methacrylic acid that is capable of producing methacrylic acid in high yield through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen.

Solution to Problem 0007]

A method for producing a catalyst for producing methacrylic acid according to the present invention is a method for producing a catalyst for producing methacrylic acid used in producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen, the catalyst containing at least molybdenum and phosphorus as catalyst components, the method including: producing a dried material having an apparent density (X) of 1.00 to 1.80 kg/L by drying an aqueous fiquid mixture containing raw material compounds for catalyst components; and producing a catalyst molded body having a molded article density (Y) of 1.60 fo 2.40 ka/L and a ratio of the apparent density (X) to the molded article density (Y), (XY), of 0.50 to 0.80 by molding the dried material or a mixture containing the dried material,

Advantageous Effect of Invention

[0008]

According to the present invention, a catalyst for producing methacrylic acid that is capable of producing methacrylic acid in high vield through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen can be provided.

Description of Embodiments

[0009] [Catalyst for producing methacrylic acid]

A catalyst for producing methacrylic acid according to the present invention is a catalyst for producing methacrylic acid used in producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen, the catalyst containing at least molybdenum and phosphorus as catalyst components, and the catalyst is produced by a method to be described later.

[0010]

The composition of the catalyst components that constitutes the catalyst according to the present invention is not specifically limited as long as the composition contains at least molybdenum and phosphorus, and can be selected appropriately depending on the intended performance of the catalyst for producing methacrylic acid. The catalyst for producing methacrylic acid according to the present invention preferably has a composition represented by the following formula (A), for example.

[0011]

FaMopVCuaXe YZ On (A) in the above formula (A), P, Mo, V, Cu, and O represent phosphorus, molybdenum, vanadium, copper, and oxygen, respectively. X represents at least one element selected from the group consisting of arsenic, antimony, and tellurium. Y represents at least one element selected from the group consisting of bismuth, germanium, zirconium, silver, salenium, silicon, tungsten, boron, iron, zing, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium, and lanthanum. Z represents at least one element selected from the group consisting of potassium, rubidium, and cesium. a, b,c d, g, f, g, and h represent the atomic ratio of each element. Whenbis 12.8is 0.1 1c 3,cis001t03, dis001i02,eis0t03, fis0io3,gis0.01tod andh

& represents the atomic ratio of oxygen necessary for satisfying the valence of each element mentioned above. The above composition is calculated from the amount of the raw material of each element fo be added.

[0012]

Method for producing a catalyst for producing methacrylic acid]

A method for producing a catalyst for producing methacrylic acid according to the present invention is a method for producing a catalyst for producing methacrylic acid used in producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen, the catalyst containing at least molybdenum and phosphorus as catalyst components, the method including: producing a dried material having an apparent density (X) of 1.00 to 1.80 kg/L by drying an aqueous liquid mixture containing raw material compounds for catalyst components; and producing a catalyst molded body having a molded article density (Y) of 1.60 to 2.40 kg/L and a ratio of the apparent density (X) to the molded article density (Y), (X/Y), of 0.50 to 0.80 by molding the dried material or a mixture containing the dried material.

[0013]

Catalyst activity, selectivity to methacrylic acid, and methacrylic acid yield in the methacrylic acid production have been found to be improved by making X, Y, and X/Y satisfy the ranges as specified in the present invention.

Embodiments of the praesent invention are shown hereinafter.

[0014] {Preparation of aqueous liquid mixture containing raw material compounds for catalyst components)

First of all, a raw material compound for a catalyst component for a catalyst for producing methacrylic acid containing at least molybdenum and phosphorus is dissolved or suspended in water to prepare an aqueous liquid mixture. A method for preparing the agueous liguid mixture is not specifically limited, and examples thereof include known methods such as a precipitation method and an oxide mixing method.

[0015]

A raw material compound for a catalyst component used for preparing an aqueous liquid mixture is not specifically limited. Examples thereof that can be used include nitrates; carbonates; acetates; ammonium salls; oxides; halides; oxo acids; and salts of oxo acids of each constituent element of the catalyst. These may be used singly or in combinations of two or more.

Examples of a raw material compound of molybdenum include molybdenum oxides such as molybdenum trioxide, and ammonium molybdates such as ammonium paramolybdate and ammonium dimolybdate. Examples of a raw material compound of phosphorus include phosphoric acid, phosphorus pentacxide, and ammonium phosphate. Examples of a raw material compound of vanadium include ammonium metavanadate, vanadium pentoxide, and vanadyl oxalate. Examples of a raw material compound of copper include copper nitrate, copper oxide, copper carbonate, and copper acetate. These raw material compounds for catalyst components may be used singly or in combinations of two or more for each element that constitules a catalyst component.

[018]

The aqueous liquid mixture may include ethyl alcohol, acetone, or the like, in addition to water, as a solvent.

[0017] (Drying)

Next, the obtained aguecus liguid mixture including the raw material compounds for the catalyst components is dried. A drying method is not specifically limited, and, for example, an evaporation to dryness method, a spray drying method {spray drying), a drum drying method, or a flash drying method may be used. Among these, a spray drying is preferable.

[0018]

The apparent density (X) of the dried material in the present invention is inthe range of 1.00 to 1.80 kg/L, preferably in the range of 1.00 to 1.60 kg/L, more preferably in the range of 1.00 to 1.50 kg/L, and even more preferably in the range of 1.05 to 1.40 kg/L. With the apparent density (X} in the range of 1.00 to 1.80 kgfL, catalyst activity and selectivity to methacrylic acid in the methacrylic acid production are improved because it becomes possible to allow pores effective in selective oxidation of methacrolein to be formed while obtaining a sufficient molded body density. In the case where the apparent density (X) is less than 1.00 kg/L., it is possible to form pores effective in the reaction, but the molded article density becomes smaller in molding, and the amount of the catalyst to be packed into a reaction tube is decreased resulting in decreased reaction rate. On the other hand, in the case where the apparent density (X) is more than 1.80 kg/L, catalyst activity and selectivity to methacrylic acid are lowered. Here, the apparent density (X) is a value measured by the method as described in JIS K 7365. Namely, the obtained dried material is measured off into a 100 mL measuring cylinder, and the apparent density is a value calculated from the mass of 100 mi volume by the following formula.

[0018]

Apparent density {X) (kg/L {g/mL}) = Mass of the dried material packed into a 100 mL measuring cylinder {g} / 100

[0020]

A spray drying can be carried out by supplying the aqueous liquid mixture obtained by the above method and hot air to a spray drier and spraying the aqueous liquid mixture into the hot air. Examples of a spraying system for the aqueous liquid mixture include a rotating disk system and a pressure nozzle system. Furthermore, as hot air, an oxidizing gas such as air may be used, and non-oxidizing gas such as nitrogen may also be used. The apparent density (X) of the obtained dried material tends to become larger as an inlet temperature of the hot air is lower; a liquid temperature of the aqueous liquid mixture to be supplied is lower; a stirring of the agueous liquid mixture to be supplied is more vigorous; and the solid content rate of the aqueous liquid mixture is higher. Thus, these may be adjusted so that the apparent density (X} falls within the range from 1.00 to 1.80 kg/L.

[0021]

The hot air inlet temperature of a spray drier is preferably 200 to 400°C, more preferably 210 to 370°C, even more preferably 220 to 300°C, and particularly preferably 230 to 280°C,

[0022]

A stirring of the aqueous liquid mixture before feeding it into a spray drier is preferably carried out at the highest possible speed. Examples of a stirrer include known stirrers such as: a rotary stirrer such as a rotary blade stirrer or a high-speed rotation shear stirrer (homogenizer and the like); a pendulum linear motion type stirrer; a shaker that shakes a container itself; and a vibration type stirrer using ultrasonics or the like. As a stirrer, a rotary stirrer such as a rotary blade stirrer or a high-speed rotation shear stirrer (homogenizer and the like} is preferable because it is easy to adjust the intensity of stirring and it is a simple method from an industrial standpoint. A rotation speed of a stirring vane or a rotating blade in the rotary stirrer may be adjusted appropriately taking the shape of a container, a stirring vane, a baffle plate, and so on; and the liquid volume into consideration so as not for the liquid to scatter. A temperature of the aqueous liquid mixture at the time of stirring is preferably 25°C or lower, mare preferably 20°C or lower, even more preferably 18°C or lower, and particularly preferably 15°C or lower. A stirring time is preferably 30 minutes or longer, more preferably 40 minutes or longer, even more preferably 50 minutes or longer, and particularly preferably one hour or longer.

[0023]

A solid content rate of the aqueous liguid mixture in the present invention is calculated, after drying a part of the aqueous liquid mixture with a hot air drier and so on, from the mass of solid content after drying by the following formula.

[0024]

Solid content rate (%) = (Mass of the sclid content of the aqueous liguid mixture after drying / Mass of the aqueous liquid mixture before drying) x 100

[00285]

The solid content rate of the aqueous liquid mixture is preferably 18% or more, more preferably 20% or more, even more preferably 22% or more, and particularly preferably 25% or more. Furthermore, the solid content rate of the aqueous liquid mixture is preferably 50% or less, and more preferably 40% or 2% less.

An average particle diameter of the dried material is preferably 1 to 250 pum. In the case where the average particle diameter is 1 pm or more, a pore diameter necessary for the oxidation reaction of methacrolein can be assured, thus methacrylic acid can be obtained in a higher yield. Further, in the case where the average particle diameter is 250 um or less, the number of contact points between dried material particles per unit volume does not decrease, thus a catalyst having a sufficient mechanical strength can be obtained. The average particle diameter of the dried material is more preferably § fo 150 pm.

The average particle diameter means a volume average particle diameter, and the value is measured by a laser particle diameter distribution measuring apparalus.

[0027]

Furthermore, a contact mode of sprayed liquid drops with the hot air may be any one of co-current, counter current, and co-counter current {mixed current), and the drying can preferably be carried out in any one of these modes.

[0028]

The dried material thus obtained may be subjected to, if necessary, a heat treatment (calcination) at 200 to 500°C to make a calcined product. The calcination condition is not specifically limited, but the calcination is usually carried out under the flow of oxygen, air, or nitrogen. Further, the calcination time is set appropriately according to the intended catalyst. Hereinafter, a dried material which has not been calcined and the calcined product described above are collectively referred to as a dried material. When the heat treatment is carried out, the apparent density (X) is measured for the calcined product after the heat treatment, and the measured value may be included within the range of the apparent density (X) according to the present invention,

[0028] {Preparation of mixture containing dried material)

When extrusion is carried out in the molding to be described below, itis also possible to prepare a mixture containing the obtained dried material to carry out extrusion of the mixture. The mixture is not specifically limited as long as it contains the dried material, however the mixiure is preferably a kneaded material that is produced by kneading a liquid and an organic binder with the obtained dried material.

[0030]

An apparatus to be used for kneading is not specifically limited, and for example, a batch type kneader with a double arm type stirring impeller; or a continuous kneader such as one having a rotating reciprocating screw, or one having a self-cleaning function can be used. However, a balch type kneader is preferable from a viewpoint that it is possible to carry out kneading while checking the state of the kneaded material. The end point of kneading is defined as a point of time when the kneaded material is mixed until itis possible for the kneaded material to be extruded, and the end point is determined by a visual observation or a touch.

[0031]

The liquid is not specifically limited as long as the liquid has a function of wetting the dried material, and examples thereof include water; and an alcohol having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol. Among these, ethyl alcohol and propyl! alcohol are preferable from the standpoint that the particles in the dried material do not collapse, and that pores effective in the oxidation reaction are easy to be formed. These may be used singly or in combinations of two or more,

[0032]

The amount of the liquid to be used is selected appropriately depending on the type and size of the dried material, and the type of the liquid; however, it is preferably 10 to 80 parts by mass relative to 100 parts by mass of the dried material to be subjected to a kneading. When the amount of the liquid fo be used is 10 parts by mass or more, it becomes possible to smoothly carry out extrusion, therefore particles in the dried material become difficult to be crushed. Thereby, large voids, namely large pores are formed in the dried or calcined molded article, and the selectivity to methacrylic acid tends to be improved. On the other hand, when the amount of the liquid to be used is 60 parts by mass or less, adhesiveness at the time of molding is lowered resulting in improved handling characteristics. Furthermore, the strength of the molded arficle tends to be improved because the molded article becomes denser. The amount of liquid to be used is more preferably 15 to 50 parts by mass relative to 100 paris by mass of the dried material to be subjected to a kneading, even more preferably 16 to 45 parts by mass, and particularly preferably 20 to 35 parts by mass.

[0033]

The organic binder is not specifically limited, and examples thereof include a polymer compound such as polyvinyl alcohol, a-glucan derivatives, and B-glucan derivatives. These may be used singly or in combinations of two oF more,

The a-glucan derivative is a polysaccharide in which glucose is bound in the form of a-configuration among polysaccharides that are constituted from glucose. Examples thereof include derivatives such as a-1,4 glucan, a-1,6 glucan, and «-1,4/1,6 glucan. Examples of such an a-glucan derivative include amylose, glycogen, amylopectin, pullulan, dextrin, and cyclodextrin,

These may be used singly or in combinations of two or more.

[0035]

The B-glucan derivative is a polysaccharide in which glucose is bound in the form of p-configuration among polysaccharides that are constituted from glucose. Examples thereof include derivatives such as §-1,4 glucan, §-1,3 glucan, $-1,6 glucan, and $-1,3/1,6 glucan, Examples of such a B-glucan derivative include: a cellulose derivatives such as methyl cellulose, sthyl cellulose, carboxymethyl cellulose, sodium carboxymethyl! cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose (HPMOC), hydroxyethyl methyl cellulose, hydroxybutyl methyl cellulose, and ethyl hydroxyethy! cellulose; §-1,3 glucans such as curdian, laminaran, paramylon, callose, pachyman, and scleroglucan. These may he used singly or in combinations of two or more.

[0036]

The organic binder may be used without being refined, or may be used as refined. However, in the case where metals or ignition residues as impurities are contained, the catalyst performance sometimes is reduced, therefore the content of metals or ignition residues is preferably smaller,

[0037]

The amount of the organic binder to be used is selected appropriately depending on the type and size of the dried material, and the type of liquid,

however it is preferably 0.05 to 15 parts by mass relative to 100 parts by mass of the dried material to be subjected to a kneading, and more preferably 0.1 to 10 parts by mass, With an amount of the organic binder to be used of 0.05 parts by mass or more, the moldability tends to be improved. On the other hand, the amount of the organic binder to be used of 15 parts by mass or less makes it easy to carry out a process of removing the organic binder by, for example, a heat treatment after molding.

[0038] in addition, in the kneading, an inert carrier such as an inorganic compound such as silica, alumina, silica-alumina, silicon carbide, titania, magnesia, graphite, and diatomaceous earth; inorganic fiber such as glass fiber, ceramic fiber and carbon fiber; or ceramic ball or stainless steel can further be added to carry out kneading. These may be used singly or in combinations of two or more,

[0039] (Molding)

Next, the dried material or the mixture containing the dried material is molded to produce a catalyst molded body. Examples of a molding method of the dried material include known methods for molding powders such as tableting, extrusion, and a tumbling granulation. Among these, extrusion is preferable. In addition, as described above, in the case of extrusion, the mixture containing the dried material can be extruded. For example, an auger extrusion machine or a piston type extrusion machine can be used for the extrusion. A shape of the catalyst molded body is not specifically limited, and it can be, for example, any shape such as ring shape, cylindrical shape, or star shape.

in the case of extrusion, an extruded form obtained by extrusion may be dried to make a catalyst molded body. A method for drying is not specifically fimited, and for example, commonly known methods such as a hot air drying, a far infrared drying, or a microwave drying can arbitrarily be used. The drying condition can appropriately be selected as long as the intended water content is obtained. In the case where the drying is applied to the extruded form, the molded article density (Y) to be described later is measured for the catalyst molded body after drying, and the measured value may be included within the range of the molded article density (YY) according to the present invention and the value of (X/Y) may be included within the range according {o the present invention.

[0041]

The molded article density (Y) of the catalyst molded body of the present invention is in the range of 1.60 to 2.40 kg/L., preferably in the range of 1.6510 2.30 kg/L, more preferably in the range of 1.70 to 2.20 kg/l., and even more preferably in the range of 1.75 to 2.10 kg/L.. Furthermore, the ratio of the apparent density (X} to the molded article density (Y), (XY) in the present invention is in the range of 0.50 to 0.80, preferably in the range of 0.53 10 0.75 kg/l, more preferably in the range of 0.55 to 0.73 kg/L., and even more preferably 0.57 t0 0.70 kg/l.. Here, the molded article density {Y) is the value calculated from the average value of the mass (kg) per a catalyst molded article divided by the volume (L) for 100 catalyst molded articles.

[0042] 25% When the molded article density {Y) is in the range of 1.60 to 2.40 kg/L, catalyst activity is improved in the methacrylic acid production because the amount of the catalyst to be packed effective in the oxidation of methacrolein can be assured. Furthermore, when the ratio (X/Y)} is in the range of 0.50 fo 0.80, the amount of pore effective in the selective oxidation of methacrolein and the amount of the catalyst fo be packed effective in the oxidation of methacrolein are simultaneously assured, therefore the yield of methacrylic acid is improved.

[0043]

The molded article density {Y) of the catalyst molded body tends to become larger as the amount of liquid is smaller in the case where the liquid is added in preparing the mixture; and the molding pressure is higher. Therefore, these may be adjusted so that the molded article density (Y) is 1.60 {0 2.40 kgfl., and, at the same time, the ratio of the apparent density (X} to the molded article density (Y)}, (X/Y} is 0.50 to 0.80.

[0044] {Calcination)

The obtained catalyst molded body as such may be used as the catalyst for producing methacrylic acid, however it may also be used as the catalyst for producing methacrylic acid after calcination.

[0045]

The calcination condition is not specifically limited, and known calcination conditions can be applied. The calcination temperature may be 200 {o 800°C, preferably 200 to 500°C, and more preferably 300 10 450°C. The calcination time may be 1 to 24 hours.

[0048] {Meathod for producing methacrylic acid]

A method for producing methacrylic acid according to the present invention is a method for producing methacrylic acid through a catalytic gas- phase oxidation reaction of methacrolein with molecular oxygen in the presence of the catalyst for producing methacrylic acid produced by the method according to the present invention, 10047] .

The catalytic gas-phase oxidation reaction can be carried outin a fixed- bed. A catalyst layer is not specifically limited. The catalyst layer may be a non-diluted layer composed of only the catalyst or a diluted layer containing an inert carrier, and may be a monolayer or a mixed layer composed of a plurality of layers.

[0048]

It is preferable to use a raw material gas that contains methacrolein and molecular oxygen for the catalytic gas-phase oxidation reaction. The concentration of methacrolein in the raw material gas can be changed in a wide range, however the concentration of methacrolein in the raw material gas is preferably 1% by volume or more, and more preferably 3% by volume or more.

Furthermore, the concentration of methacrolein in the raw material gas is preferably 20% by volume or less, and more preferably 10% by volume or less.

The concentration of molecular oxygen in the raw material gas is preferably 04 mol or more per 1 mol of methacrolein, and more preferably 0.5 mol or more. in addition, the concentration of molecular oxygen in the raw material gas is preferably 4 mol or less per 1 mol of methacrolein, and more preferably 3 mol or less. As a molecular oxygen source, it is economical to use air, however a pure oxygen-enriched alr can be used, if necessary.

The raw material gas preferably contains water (water vapor) besides methacrolein and molecular oxygen. When the reaction is carried out in the presence of water, methacrylic acid can be obtained in a higher yield. The concentration of water vapor in the raw material gas is preferably 0.1% by yplume or more, and more preferably 1% by volume or more. Furthermore, the concentration of water vapor in the raw material gas is preferably 50% by volume or less, and more preferably 40% by volume or less. The raw material gas may contain a small quantity of impurities such as lower saturated aldehyde, however it is preferable to keep the quantity as small as possible.

Moreover, the raw material gas may also contain an inert gas such as nitrogen or carbon dioxide gas.

[0050]

The reaction pressure of the catalytic gas-phase oxidation reaction is preferably from ordinary pressure (atmospheric pressure) to 5 atm. The reaction temperature is preferably 230°C or higher, and more preferably 250°C or higher. Furthermore, the reaction temperature is preferably 450°C or lower, and more preferably 400°C or lower. The flow rate of the raw material gas is not specifically fimited and can be set appropriately so that a suitable contact time is realized. The space velocity of the raw material gas Is preferably 300 to 3000 hr, and more preferably 500 to 2000 hr.

Examples

[0051]

Hereinafter, the present invention will be explained specifically with reference to Examples and Comparative Examples, however the present invention is not limited to these Examples. The term “parts” in the following

Examples and Comparative Examples means parts by mass.

[0052]

An analysis of the raw material gas and the products were carried out by gas chromatography. The reaction rate of methacrolein, the selectivity to methacrylic acid, and the yield of methacrylic acid are defined as follows.

[0053]

Reaction rate of methacrolein (%) = (B/A) x 100

Selectivity to methacrylic acid (%) = (G/B) x 100

Yield of methacrylic acid (%) = (C/A) x 100 in these formulas, A represents the number of moles of supplied methacrolein, B represents the number of moles of reacted methacrolein, and

C represents the number of moles of produced methacrylic acid.

[0054]

Furthermore, the apparent density (X) of the dried material, the molded article density (Y) of the catalyst molded body, and the solid content rate of the slurry (the aqueous liquid mixture) were measured as follows,

[0055] {Apparent density (X) of dried material)

The dried material was measured off into a 100 mb measuring cylinder according to the method as described in JS K 73685. The apparent density (X) of the dried material was calculated from the mass of a volume of 100 mL by the following formula.

[0056]

Apparent density (X) (kg/L (g/ml) = Mass of the dried material packed into a 100 mL measuring cylinder (g) / 100

[0057] {Molded article density (Y) of catalyst molded body)

The mass (kg) per a catalyst molded article was divided by the volume (L). This calculation was carried out for 100 catalyst molded articles, and the molded article density (Y) of the catalyst molded body was determined by calculating the average value. 10058] {Solid content rate of slurry (agueous liquid mixture) 300 g of the slurry was dried with a hot air drier. The solid content rate of the slurry (the aqueous liquid mixture) was calculated from the mass of the solid content after drying by the following formula.

[0059]

Solid content rate {%) = (Mass of the solid content after drying slurry /

Mass of the slurry before drying slurry) x 100

[0060] (Example 1} 100 parts of molybdenum trioxide, 3.4 parts of ammonium metavanadate, 8.0 parts of 85% by mass aqueous phosphoric acid solution, and 1.4 parts of copper nitrate were dissolved in 400 parts of pure water. The resuitant solution was heated to 85°C while being stirred, and the stirring was continued for 3 hours keeping the solution temperature at 85°C. After cooling the solution to 85°C, a solution obtained by dissolving 14.0 parts of cesium bicarbonate in 20 parts of pure water was added thereto while stirring with a rotary blade stirrer, and the resultant mixture was stirred for 15 minutes, Next a solution obtained by dissolving 10.7 parts of ammonium nitrate in 20 parts of pure water was added thereto, and the resultant mixture was further stirred for

20 minutes. After that, the slurry was heated to 100°C while being stirred, and then condensed until the solid content rate of the slurry reached the value as shown in Table 1. 0061}

The slurry (aqueous liguid mixture) containing the raw material compounds for the catalyst components thus obtained was subdivided into small batches of slurry each having a volume of 20 L, which were then stirred.

After that, the subdivided slurry was spray dried using a co-current spray dryer under the condition of a rotation speed of a rotary disk for spraying slurry of 18,000 rpm. The method of stirring the slurry, the stirring rotation speed, the stirring time, and the liquid temperature of the slurry are shown in Table 1 as the condition of stirring the subdivided slurry each having a volume of 20 L before spray drying. Furthermore, the hot air inlet temperature in the spray drying and the apparent density (X} of the obtained dried material are shown in

Table 1. The solid content rate of the slurry shown In Table 1 was measured hefore stirring the subdivided slurry; however, the value does not change after stirring.

[0062]

The dried material thus obtained, HPMG, ethyl alcohol, and pure water were mixed, and kneaded until the dried material became clay-like by a batch- type kneader equipped with a double-arm type sigma-blade.

[0063]

Next, the kneaded mixture was extruded by a piston fype extrusion machine. In the extrusion, the mixture was molded into a cylindrical shape with an outer diameter of 4.8 mm and a length of 5 mm. This molded body was dried at 90°C for 12 hours to obtain a catalyst molded body. The amount of each additive and the molded article density (Y) of the oblained catalyst molded body are shown in Table 2.

[0064]

Next, the catalyst molded body was calcined at 380°C under airflow for

S 18 hours to obtain a catalyst. The elemental composition of the obtained catalyst other than oxygen (the same applies hereinafter) was as follows.

[0085]

MoV sP1.2C0u01C81 25

The above elemental composition is calculated from the amount of the raw material of each element to be added.

[0066]

This catalyst was packed into a reaction tube made of stainless steel with an outer diameter of 27.5 mm and a height of 6 m which has a thermo- bath outside in such a way that the packing length of the catalyst was 5 m.

Then, the temperature of the thermo-bath was set to 285°C, and then the catalytic gas-phase oxidation reaction of methacrolein was carried out under the condition that allowed a reaction gas consisting of 6% by volume of methacrolein, 12% by volume of oxygen, 10% by volume of water vapor, and 72% by volume of nitrogen to pass through the catalyst layer at a space velocity of 1100 het. The product obtained after 24 hours from the start of the reaction was collected and analyzed by gas chromatography to determine the reaction rate of methacrolein, the selectivity to methacrylic acd, and the yield of methacrylic acid. The results are shown in Table 3.

[0067] (Example 2, Comparative Examples 1 to 4)

The catalysts were prepared and the catalytic gas-phase oxidation reaction of methacrolein was carried out in the same manner as in Example 1 except for adopting the conditions shown in Tables 1 and 2. The results are shown in Table 3.

[0088] (Example 3} 100 parts of molybdenum trioxide, 2.7 parts of ammonium metavanadale, 7.3 parts of 85% by mass aqueous phosphoric acid solution, 7.5 parts of 60% by mass arsenic acid, and 2.8 parts of copper nitrate were dissolved in 400 parts of pure water. The resultant solution was heated to 85°C while being stirred, and the stirring was continued for 3 hours keeping the solution temperature at 85°C. Alter cooling the solution to 85°C, a solution obtained by dissolving: 12.4 paris of cesium bicarbonate dissolved in 20 paris of pure water: and 9.2 parts of ammonium carbonate dissolved in 20 parts of pure water in 26 parts of pure water was added thereto while stirring with a rotary blade stirrer, and the resultant mixture was further stirred for 20 minutes. After that, the slurry was heated to 100°C while being stirred, and then condensed until the solid content rate of the slurry reached the value as shown in Table 1.

[0069]

The slurry aqueous liquid mixture containing the raw material compounds for the catalyst components thus obtained was subdivided info small batches of slurry each having a volume of 20 L, which were then stirred.

After that, the subdivided slurry was spray dried by a co-current spray dryer under the condition of a rotation speed of a rotary disk for spraying slurry of 18,000 rpm. The conditions of stirring and drying, and the apparent density {X) of the obtained dried material are shown in Table 1.

[0070]

The dried material thus obtained, HPMC, ethyl alcohol, and pure water were mixed, and kneaded until the dried material became clay-like by a batch- type kneader equipped with a double-arm type sigma-blade.

[6071]

Next, the kneaded mixture was extruded by a piston type extrusion machine. In the extrusion, the mixture was molded into a pellet shape with an outer diameter of 4.8 mm and a length of 8 mm. This molded body was dried at 80°C for 12 hours to obtain a catalyst molded body. The amount of each additive and the molded article density (Y) of the obtained catalyst molded body are shown in Table 2.

[0072]

Next, the catalyst molded body was calcined at 380°C under airflow for hours to obtain a catalyst. The elemental composition of the obtained 15 catalyst other than oxygen was as follows.

[0073]

M012Vo.4P 1 1AS0 550 U0 2081 4

This catalyst was packed into a reaction tube made of stainless steel with an outer diameter of 27.5 mm and a height of 8 m which has a thermo- bath outside in such a way that the packing length of the catalyst was & m.

Then, the temperature of the thermo-bath was set to 285°C, and then the catalytic gas-phase oxidation reaction of methacrolein was carried out under the condition that allowed a reaction gas consisting of 6% by volume of methacrolein, 12% by volume of oxygen, 10% by volume of water vapor, and 72% by volume of nitrogen to pass through the catalyst layer at a space velocity of 1100 hr. The product obtained after 24 hours from the start of the reaction was collected and analyzed by gas chromatography to determine the reaction rate of methacrolein, the selectivity to methacrylic acid, and the yield of methacrylic acid. The results are shown in Table 3.

[0074] (Examples 4 {to 8, Comparative Examples Sto 7}

The catalysts were prepared and the catalytic gas-phase oxidation reaction of methacrolein was carried out in the same manner as in Example 3 except for adopting the conditions shown in Tables 1 and 2. The results are shown in Table 3,

[0075]

The reaction each described in Example 3, Comparative Example 5, and

Comparative Example 8 was carried out for 2400 consecutive hours. The resulis are shown in Table 4.

{Table 1} [Table 1] - Ly | 1 Stirring — | ss Soli Cd arent

Example and | Hot alr inlet | Hering Stiming § Liqud | Solid . Appa on ot ~ od rte Mothod of | sotation | — 1 atgre | content rate density (X} of

Comparative | temperature stirling slurey seid tine | lemperature of slurry | dried raaterial

Fxample | [°CI | gery op find ofslurey [PCY oy ex — SR eo dpe TC lim RE

Rotary stirer

Exaraple 1} 250 | having 4 paddle | 150 45 20 22 1.05 {impellers | i

Fi prem IIT rs tatesns a a ena ! ¢ Rotary sturer i Example 2 258 having 4 paddle 150 45 20 | 23 108 i impellers

Comparative Rotary stirrer : . i

JEPAIAIYE Lo 2ep having 4 paddle | 150 | 48 28 Loom es

Example 1} . ] i ! ! impellers ih ST

Comparative {Rotary stirrer Lo

Momparanie L250 | having paddle | 150 | 48 2% Lo pes v Example ! . ! | i { i | ! impellers ! i i i cia}

Adina nasa re Le A SA eR A RR ns hese

Comparative | Rotary ster

SOWPRISIEE 4 agp having d paddle | 106 | 30 | 28 18 1 0.80

Example 3 | | Le i ! { i : impellers ! {

A A ries ses re ES

Comparative { {Rotary stirsy | i {

Oupards 300 | having 4 paddle | 10D 30 25 18 g90 \ Exarople 4 { , i i ! i impellers i na ssa aaa CS nr NNR

Rotary stirrer

Example 3 250 i having 4 paddie 156 | #Q is 27 1.47 ; ! impellers | \ i

Bristle ros omnes ise risa AE rma i ! | Rotary stirrer | : :

Example 4 | 250 | having 4 paddle | 180 | 60 {5 37 i £17 ; i impellers | | | {

RR ARR RR SR mmm es

Comparative | Rotary stirrer { !

PABIVE | ase | having 4 paddle | 150 | 60 | 15 70 wT

Exarople 3 | : , : | \ i : {impellers | { \ !

Fr as Ee erin sy nse Ss

Comparative i Rotary stiver

LOmpAEHY 250 | having 4 paddle | 150 50 i 27 1.17

Example 6 . impellers frm mmm Se SY A A bimnnns iis Sa Sn es rss

Example 5 | 230 Homogenizer | ROOD | 60 10 : 34 1.31

Basngmgnrirnde nde re Tn ARR RRR aay A fr Lee i. arative i , i i A :

Comparative | gag Homogenizer | 8000 | 60 wo oa 1a i Exsuple 7 4 = | | : rs ys fron Rs od } Example 8 218 {| Hamogenizer | 8000 i 0 14 | 38 Lo 1.38 :

[0077]

Table 2} [Table 2}

Example and | Amount of Amount of | Amount of | Amount of Molded article \ Comparative | dried material] HPMC {ethyl aloohol | pure water | density (Y} of catalyst \ Example | {parts} | [pats] | [parts] | {parts} molded body [kg/L]

Formsmansangsnpmoni ese ent A TA tion ts dene ILA Ar irr nimi fe = = fA eA RA im a

Example {| 100 5 | FA EE

Example 2 | 100 5 os Ls 1.65

TTT AS AA fimmmim mm mmm mm a va EL ea Ed i a am re i pn aa im i SE ea ey 3 ativ :

Comparative 100 EE I 1.50

Comparative 100 | sw 6 | 2.19 i Example 2 : et ne Am AS An mem A rr ns A fe AnH em a aa we

Comparative L qq 1 5 21 7 1.79

Example 3 4 i frees Er

Comparative | 100 5 32 4 1 45 : \ Example 4 | | ; !

A srr Smee fe——— ARAN RY

Exaraople 3 | 106 § | 20 1 7 1.83

Er pe ey ros

Example 4 JRE 5 Lo 19 { 6 1.99

Jr Amr daa erp Sg ! ———

Comparative we 45 3 3 1.51

Comparative | c ! : 30 5 15 § 2.41 \ Example 6 Ho | 7 ; Lo ; = rr

Examples | 100 | 5 i 18 ! 6 246

Comparative 100 s L303 1.52

Example 7 \ bo '

Teamnan saa Sayan aa A tA A A A RR eb a a REA Sas

Examples | 100 0s | 18 | 5 1 2.06

0078] [Table 3] [Table3] oo - | Apparent | Molded article Ratioof {| Les ites

Frample density (X} | density (Y}of | apparent Rpagios rate Selectivity i Yieldof

Comparative of dried catalyst density to methacrolein | methact ti) ERE

Example | | 1.05 ree esr 1 sso | Tie | 655 amped LL EY rss em ee re ee na ee sone Yea ARR SE A a a 0

Example? | 1.05 165 | 064 | B42 | TI3 | 65.1 rr or fr (Compamativel yas 1 yey gy | 783 | 771 | 604

Bxampled | Cd A Lo LL

Comparative! 4c | 239 | 0.48 85.3 m1 | 64

Example 2 1

ANNA er Hi rer mn Bases a 1 RR sy [Comparative] p50 1 056 | 8s1 i 733 52.4

Example 3 i nN id

Lomparativel g g4 4s | 062 | 7A | a 604 \ Example 4 ] | i E sh ii AAA ARRAS SE rs =

Bxample3 | Li7 | 1.83 0.64 84.8 79.4 | 674 1

Boomers ssa Ht i En ra nmin an St dc ss rrp

Example 4 | 117 | 199 | 0.59 85.3 79.3 67.6

Frommmmmeiis . NANA AR CR A Ln narra A A A AA LLY {ri — isin Ce a ne mmm a a a aN

Compare 117 151 Lom mE 1 798 615

Maple S| Lanse

Comparative 0 oa | ous | ss m2 | oes

Exampie 6 | ho Co \ LL Ce

Examples | 131 | 206 | 06 | 885 1 793 | 678

Comparative) yg) 152 | 0.86 78.1 | 94 | 620

Example6 | 138 | 206 067 82 i 784 | 676

[Table 4] [Table 4} ) r | Reactionrate of | Selectivity to : Yield of : ixample and methacrolein | methacrylic acid | methacrylic acid

CompanteBomple | 0A | 04 Ce ___Example3 84.7 79.8 67.6 } \ Comparative Example 5 | 73.5 oo C793 58.7

Comparative Example 6 | 85.8 762 | } 65.4 [oso]

As described above, when the Example and Comparative Example that have the same catalyst composition are compared, all the Examples, in which the apparent density (X) is in the range of 1.00 to 1.80 kg/L,; the molded article density (Y} is in the range of 1.80 to 2.40 kg/L; and (X/Y} is in the range of 0.50 to 0.80, showed better yield of methacrylic acid than the Comparative

Examples.

Claims

Claims

[Claim 1] A method for producing a catalyst for producing methacrylic acid used in producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen, the catalyst comprising at least molybdenum and phosphorus as catalyst components, the method comprising: producing a dried material having an apparent density (X) of 1.0010 1.80 kg/L by drying an aqueous liquid mixture comprising raw material compounds for catalyst components; and producing a catalyst molded body having a molded article density (YY) of

1.80 to 2.40 kg/L and a ratio of the apparent density (X} to the molded article density {Y), (UY), of 0.50 to 0.80 by molding the dried material or a mixiure comprising the dried material.
[Claim 2] A catalyst for producing methacrylic acid produced by the method according to claim 1,
[Claim 3] A method for producing methacrylic acid through a catalytic gas-phase oxidation reaction of methacrolein with molecular oxygen in the presence of the catalyst for producing methacrylic acid according to claim 2.