JP2010188227A - Method for producing catalyst for producing methacrylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of producing a catalys, which has satisfactory catalytic activity as an industrial catalyst for producing methacrylic acid and is excellent in selectivity and yield of methacrylic acid, through a simplified a catalyst production process. <P>SOLUTION: The method for producing the catalyst for producing methacrylic acid, which catalyst is used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen and contains molybdenum and vanadium at the least as catalytic components, comprises the steps of: mixing raw material compounds of catalytic components in water being a solvent to prepare a mixed solution or slurry; concentrating the prepared mixed solution or slurry to the extent that the water content thereof becomes 21-70 mass%; adding an organic binder to the mixed solution or slurry before, during or after the time to carry out the concentrating step; and molding the organic binder-added concentrate to obtain a molding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Conventionally, many proposals have been made on a catalyst for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. Many of these catalysts have a composition containing molybdenum and vanadium, and industrially produced and used are classified into tableting molding catalysts, extrusion molding catalysts, supported molding catalysts, etc., from the molding method. Has been. Usually, the tableting catalyst is a method of compressing and molding the catalyst composition powder. The extrusion-molded catalyst is manufactured through a process of kneading particles containing the catalyst composition and extrusion-molding, and the supported molded catalyst is manufactured through a process of supporting a powder containing a catalyst component on a carrier.

  Such catalysts are required to be improved in catalytic activity, target product selectivity, yield, catalyst moldability, etc., and their production methods are being studied. For example, a solution or slurry in which a compound containing a catalyst component element is mixed is concentrated or dried, and the water content in the resulting concentrate or dried product is adjusted to 5 to 20% by weight, and then at a temperature of 100 to 250 ° C. It has been shown that the catalyst obtained by heat treatment can produce the target product in a high yield at a relatively low reaction temperature (Patent Documents 1 and 2). In addition, a method has been proposed in which a pore structure can be formed in the catalyst by adding an organic substance such as polyvinyl alcohol at the time of catalyst molding and performing heat treatment, thereby improving the selectivity (Patent Documents 3 and 3). 4). Moreover, in order to improve the physical strength of a catalyst, the method of adding graphite to a catalyst substance and extruding is proposed (Patent Document 5).

JP 58-51943 A JP 58-11250 A JP 55-73347 A JP 2002-282696 A JP-A-60-150834

  However, the catalysts obtained by these known methods are not necessarily sufficient as industrial catalysts in terms of catalyst activity, target product selectivity and the like, and further improvements are desired. On the other hand, these known methods are complicated in process, require large initial capital investment in the catalyst manufacturing factory, and have a large human load, so the catalyst manufacturing cost is high and the productivity is low. Improvement of catalyst production productivity is desired.

  In view of these problems, the present invention provides a catalyst having sufficient catalytic activity as an industrial catalyst for methacrylic acid production and excellent selectivity for methacrylic acid and yield, in which the catalyst production process is greatly omitted. It aims at providing the manufacturing method of the catalyst which can be manufactured, and the manufacturing method of methacrylic acid using the catalyst.

  The method for producing a catalyst for producing methacrylic acid according to the present invention is used for producing methacrylic acid containing at least molybdenum and vanadium as catalyst components, which are used when producing methacrolein by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. In the method for producing a catalyst, a step of preparing a mixed solution or slurry in which the raw material compound of the catalyst component is mixed with water as a solvent, a step of concentrating until the water content of the mixed solution or slurry is 21 to 70% by mass, A step of adding an organic binder at any stage before, during or after concentration of the mixed solution or slurry, and a step of obtaining a molded body by molding the concentrate to which the organic binder has been added. It is characterized by.

  The catalyst for producing methacrylic acid according to the present invention is obtained by the method for producing a catalyst for producing methacrylic acid.

  In addition, according to the method for producing methacrylic acid according to the present invention, methacrolein is subjected to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid.

  ADVANTAGE OF THE INVENTION According to this invention, the high catalyst activity in methacrylic acid manufacture, the selectivity of methacrylic acid, the catalyst of a high yield can be manufactured, and the catalyst manufacturing method with high production efficiency which simplified the catalyst manufacturing process Can be provided.

  The method for producing a catalyst for producing methacrylic acid according to the present invention is used for producing methacrylic acid containing at least molybdenum and vanadium as catalyst components, which are used when producing methacrolein by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. In the method for producing a catalyst, a step of preparing a mixed solution or slurry in which the raw material compound of the catalyst component is mixed with water as a solvent, a step of concentrating until the water content of the mixed solution or slurry is 21 to 70% by mass, A step of adding an organic binder to the mixed solution or slurry before, during or after the concentration, and a step of obtaining a molded body by molding the concentrate to which the organic binder has been added.

  The composition of the catalyst component constituting the catalyst produced by the method of the present invention can be appropriately selected according to the target catalyst for producing methacrylic acid, and is not particularly limited as long as it contains at least molybdenum and vanadium as catalyst components. However, it preferably has a composition represented by the following formula (1).

_{P a Mo b V c Cu d} X e Y f Z g O h (1)
In the formula (1), P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively, and X is at least one element selected from the group consisting of arsenic, antimony and tellurium. Y is selected from the group consisting of bismuth, germanium, zirconium, silver, selenium, silicon, tungsten, boron, iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum At least one element is represented, and Z represents at least one element selected from the group consisting of potassium, rubidium, and cesium. a, b, c, d, e, f, g, and h represent atomic ratios of the respective elements. When b = 12, a = 0.1-1, c = 0.01-3, d = 0. 01 to 2, e = 0 to 3, f = 0 to 3, g = 0.01 to 3, and h is an atomic ratio of oxygen necessary to satisfy the valence of each element.

  The catalyst for producing methacrylic acid as described above can be suitably produced by the following method.

  First, the raw material compound of the catalyst component of the catalyst for producing methacrylic acid is dissolved or suspended in water to prepare a mixed solution or slurry. The method for preparing the mixed solution or slurry is not particularly limited, and examples thereof include known methods such as a precipitation method and an oxide mixing method.

  Examples of the raw material compound of molybdenum include molybdenum oxides such as molybdenum trioxide; ammonium molybdates such as ammonium paramolybdate and ammonium dimolybdate. Examples of the raw material compound for vanadium include ammonium metavanadate, vanadium pentoxide, and vanadyl oxalate. As raw material compounds other than molybdenum and vanadium, for example, oxides, nitrates, carbonates, ammonium salts, halides and the like of each element can be used. Examples of the phosphorus source compound include phosphoric acid, phosphorus pentoxide, and ammonium phosphate. Examples of the copper raw material compound include copper nitrate, copper hydroxide, and copper chloride. The raw material compound of the catalyst component may be used alone or in combination of two or more for each element constituting the catalyst component.

  Water is used as a solvent for dissolving or dispersing the raw material compound of the catalyst component, but a solvent obtained by adding ethyl alcohol, acetone or the like to water may be used.

  In the present invention, an organic binder is added to the mixed solution or slurry. The organic binder added to the mixed solution or slurry is not particularly limited. For example, methyl cellulose, ethyl cellulose, carboxyl methyl cellulose, sodium carboxyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxybutyl methyl cellulose, ethyl hydroxyethyl cellulose Cellulose derivatives such as water-soluble or water-dispersible polymer compounds such as polyvinyl alcohol; α-glucans such as dextrin, cyclodequillin, and pullulan; curdlan, laminaran, paramylon, callose, Pakiman, scleroglucan And β-glucan. Among these, “Biopoly” (mainly composed of methylcellulose, pullulan, β-1,3-glucan) is used because the kneaded material is easy to handle and the strength of the dried material is strong and it is easy to form pores effective for the oxidation reaction. Name, Kirin Food Tech Co., Ltd.) is preferable. One kind of organic binder may be added to the mixed solution or slurry, or two or more kinds may be appropriately combined.

  The amount of the organic binder added to the mixed solution or slurry is preferably from 0.1 to 20 parts by weight, more preferably from 0.5 to 15 parts by weight, based on 100 parts by weight of the raw material compound as a solid content. More preferably, it is 10 mass parts. In addition, 100 mass parts of raw material compounds as a solid content is a total of 100 mass parts in terms of oxide mass of each charged catalyst component.

  The timing for adding the organic binder to the mixed solution or slurry is not particularly limited, and examples thereof include a method of adding to the mixed solution or slurry before concentration, a method of adding during concentration, and a method of adding after concentration.

  The method for adding the organic binder is not particularly limited, and examples thereof include a method of directly adding and dissolving or dispersing in a mixed solution or slurry, a method of adding by dissolving or dispersing in a solvent, and the like. The method of dissolving or dispersing in a solvent is not particularly limited, and examples thereof include a method in which a binder is dispersed in a high temperature solvent and dissolved at a low temperature, and a method in which the binder is dispersed in a low temperature solvent and dissolved at a high temperature.

  In the present invention, the mixed solution or slurry is concentrated until a predetermined water content is obtained. The method of concentration is not particularly limited, and examples thereof include a method of concentrating using a catalyst mixing preparation kettle as it is, a method of using a universal mixing stirrer, and a method of using a kneader equipped with a heating mechanism. Concentration is performed by heating, but the heating method is not particularly limited, and heating equipment such as heating with steam or hot water or an electric heater can be used. The concentration ratio is preferably such that the water content of the mixed solution or slurry is 21 to 70% by mass. More preferably, the moisture content is in the range of 30 to 50% by mass. When the concentration ratio is outside the above range, it becomes difficult to obtain a molded body in the extrusion process, which is the next process. If the water content is less than 21% by mass, drying proceeds too much, and the concentrate becomes papasa, making it difficult to obtain a molded body with a well-formed shape in the extrusion process. On the other hand, when the water content exceeds 70% by mass, the viscosity of the mixed solution or slurry is too low, and it becomes difficult to obtain a molded body having a uniform shape in the extrusion molding process. The water content was determined by a loss on drying method using an infrared moisture meter. Moreover, it is preferable to carry out at 90-130 degreeC as a jacket temperature at the time of heat concentration.

  Next, the concentrate to which the organic binder has been added is molded. The molding method is not particularly limited, and examples thereof include known methods such as extrusion molding, support molding, and rolling granulation. Among these, extrusion molding is preferable from the viewpoint that the concentrate can be used as it is. The shape of the molded body is not particularly limited, and for example, it can be molded into an arbitrary shape such as a ring shape, a cylindrical shape, a star shape, a spherical shape, and the like. Moreover, diatomaceous earth, silica sol, silica gel, bentonite, kaolin and the like can be added as a shaping reinforcing agent, and glass fiber, asbestos, ceramic fiber, carbon fiber and the like can be further added.

  Next, the molded body is dried as necessary, and then heat-treated. There are no particular limitations on the drying conditions and heat treatment conditions at this time, and known processing conditions can be applied. Usually, drying is performed at a temperature of 60 to 150 ° C. for 1 to 24 hours, and heat treatment can be performed at a temperature of 200 to 500 ° C., preferably 300 to 450 ° C. for 1 to 24 hours. Note that heat treatment may be performed without drying.

  In the method of the present invention, as in the conventional method, the step of drying the slurry to obtain a dry powder of the catalyst, the step of measuring the dry catalyst powder and the binder powder, the step of mixing the measured ones in a dry process, the mixing All or part of the step of adding a solvent to the powder and kneading can be omitted or simplified.

  Next, the manufacturing method of methacrylic acid of this invention is demonstrated. The method for producing methacrylic acid of the present invention is a method for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen in the presence of the methacrylic acid production catalyst obtained as described above.

  Production of methacrylic acid by gas phase catalytic oxidation can be generally carried out by supplying a raw material gas containing methacrolein and molecular oxygen using a fixed bed reactor and reacting them. The catalyst layer packed in the fixed bed reactor is not particularly limited, and may be an undiluted layer containing only a catalyst or a diluted layer containing an inert carrier, and may be a single layer or a mixed layer composed of a plurality of layers. Good.

  The concentration of methacrolein in the raw material gas can be varied within a wide range, but is preferably 1 to 20% by volume, more preferably 3 to 10% by volume.

  Although methacrolein may contain a small amount of a lower saturated aldehyde or the like as an impurity that does not substantially affect the reaction, the amount is preferably as small as possible. The molecular oxygen concentration in the raw material gas is preferably 0.3 to 4 mol, and particularly preferably 0.4 to 2.5 mol, per 1 mol of methacrolein. It is economical to use air as the molecular oxygen source, but if necessary, air enriched with pure oxygen can also be used.

  The source gas preferably contains water (water vapor) in addition to methacrolein and molecular oxygen. By performing the reaction 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 volume or more, and more preferably 1% by volume or more. Moreover, 50 volume% or less is preferable and 40 volume% or less is more preferable. Moreover, you may add inert gas, such as nitrogen and a carbon dioxide gas, for dilution.

  The reaction pressure is usually appropriately set within a range from normal pressure to several atmospheres.

  The reaction temperature is usually set within the range of 230 to 450 ° C., and from the point of methacrylic acid yield, 250 to 400 ° C. is preferable.

  The flow rate of the raw material gas is not particularly limited, and can be appropriately set so as to have an appropriate contact time. The contact time is preferably 1.5 seconds or longer, and more preferably 2 seconds or longer. Moreover, 15 seconds or less are preferable and 5 seconds or less are more preferable.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to these Examples. The “parts” in the following examples and comparative examples are parts by mass. As a heat medium for the reactor, a salt melt composed of 50% by mass of potassium nitrate and 50% by mass of sodium nitrite was used.

The analysis of the raw material gas and the product was performed using gas chromatography. In addition, the reaction rate of methacrolein, the selectivity of the methacrylic acid to produce | generate, and a single flow yield are defined as follows.
Reaction rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Methacrylic acid yield (%) = (C / A) × 100
Here, A is the number of moles of methacrolein supplied, B is the number of moles of reacted methacrolein, and C is the number of moles of methacrylic acid produced.

[Example 1]
In 400 parts of pure water, 100 parts of molybdenum trioxide, 3.1 parts of ammonium metavanadate, 7.3 parts of 85% by weight phosphoric acid aqueous solution and 1.1 parts of copper nitrate were dissolved, and the temperature was raised to 95 ° C. with stirring. The mixture was warmed and stirred for 3 hours while maintaining the liquid temperature at 95 ° C. After cooling to 40 ° C., a solution obtained by dissolving 13.5 parts of cesium bicarbonate in 20 parts of pure water was added while stirring using a rotary blade stirrer, and the mixture was stirred for 15 minutes. Next, a solution obtained by dissolving 11.6 parts of ammonium nitrate in 20 parts of pure water was added, and the mixture was further stirred for 20 minutes.

  In the slurry containing the raw material compound of the catalyst component obtained as described above, 1.0 part of hydroxypropylmethylcellulose and 5.0 parts of “Biopoly” are added to 100 parts of the raw material compound as the solid content. (Trade name, manufactured by Kirin Foodtech Co., Ltd.) was added as a powder. While stirring this with a universal mixing stirrer, the temperature of the jacket was heated at 110 ° C., and the slurry was concentrated to a moisture content of 43% by mass to obtain a clay-like concentrate. The water content is a value determined by a loss on drying method using an infrared moisture meter.

  The obtained clay-like concentrate was molded using a piston-type extrusion molding machine to obtain a pellet-shaped molded body having an outer diameter of 6 mm and an average length of 5 mm. The moldability at the time of piston type extrusion molding was extremely good. This molded body was dried at 60 ° C. for 16 hours, and then heat-treated at 380 ° C. for 5 hours under air flow to obtain a catalyst. The elemental composition other than oxygen (hereinafter the same) of the obtained catalyst was as follows. The catalyst composition was measured by ICP emission analysis and atomic absorption analysis.

Mo ₁₂ V _0.45 P _1.1 Cu _0.08 Cs _1.2
This catalyst is filled in a reaction tube, and a raw material gas of 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor, and 55% by volume of nitrogen is reacted at a reaction temperature of 290 ° C., a reaction pressure of 1 atm (absolute pressure), and a contact time. The gas phase catalytic oxidation reaction of methacrolein was performed in 3.6 seconds. The product was collected and analyzed by gas chromatography to determine methacrolein reaction rate, methacrylic acid selectivity, and methacrylic acid yield. The results are shown in Table 1.

[Example 2]
To the slurry containing the raw material compound of the catalyst component, 3.0 parts of pullulan and 3.0 parts of “Biopoly” are added as a solid to 100 parts of the raw material compound as a powder, and the water content of the slurry is 34. A catalyst was produced in the same manner as in Example 1 except that the catalyst was concentrated to mass%. Moldability at the time of piston-type extrusion molding was very good, and the gas phase catalytic oxidation reaction of methacrolein was performed in the same manner as in Example 1 using the obtained catalyst. The results are shown in Table 1.

[Example 3]
To the slurry containing the raw material compound of the catalyst component, 2.0 parts of hydroxypropylmethylcellulose and 8.0 parts of “Biopoly” are added as a solid to 100 parts of the raw material compound as a powder, and the water content of the slurry A catalyst was produced in the same manner as in Example 1 except that was concentrated to 55% by mass. The moldability at the time of piston type extrusion molding was good and the molded body was slightly soft, but there was no problem in manufacturing. Using the resulting catalyst, the gas phase catalytic oxidation reaction of methacrolein was carried out in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
Except for adding 3.0 parts of “Biopoly” as a solid to the slurry containing the raw material compound of the catalyst component as a solid, and concentrating the water content of the slurry to 28% by mass. A catalyst was produced in the same manner as in Example 1. The moldability at the time of piston-type extrusion molding was good, the molded body was slightly hard and the molding pressure was high, but there was no problem in manufacturing. Using the resulting catalyst, the gas phase catalytic oxidation reaction of methacrolein was carried out in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
A catalyst was produced in the same manner as in Example 1 except that 21.0 parts of “Biopoly” was added as a solid to the slurry containing the raw material compound of the catalyst component as a solid content with respect to 100 parts of the raw material compound. Although the moldability at the time of piston extrusion was good, the catalyst obtained by drying and heat treatment was weak in strength. Using this catalyst, the gas phase catalytic oxidation reaction of methacrolein was carried out in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A catalyst was produced in the same manner as in Example 1 except that the water content of the slurry was concentrated to 19% by mass. Since the water content of the concentrate was low, there was a feeling of dryness, the molding pressure during piston type extrusion molding was high, and the moldability was low. Using the obtained catalyst, the gas phase catalytic oxidation reaction of methacrolein was carried out in the same manner as in Example 1. However, since the molding pressure was increased, effective pores were not obtained, resulting in a low yield. The results are shown in Table 1.

[Comparative Example 2]
To the slurry containing the raw material compound of the catalyst component, 5.0 parts of hydroxypropylmethylcellulose and 10 parts of “Biopoly” are added as powder to 100 parts of the raw material compound as a solid, and the water content of the slurry is 75. A catalyst was produced in the same manner as in Example 1 except that the catalyst was concentrated to mass%. Since the obtained concentrate had a high water content, a molded body could not be obtained at the time of piston type extrusion molding.

[Comparative Example 3]
The slurry containing the raw material compound of the same catalyst component as in Example 1 was dried using a co-current type spray dryer under conditions of a dryer inlet temperature of 270 ° C. and a slurry spraying rotary disk of 16000 rpm. 40 parts of pure water, 1.0 part of hydroxypropylmethylcellulose, and 5.0 parts of “Biopoly” are added as powder to 100 parts of the obtained dry powder, mixed and kneaded in a kneader to form a clay A catalyst was obtained in the same manner as in Example 1 except that a kneaded product was obtained (water content: 38 mass%). Moldability at the time of piston-type extrusion molding was extremely good, and a gas phase catalytic oxidation reaction of methacrolein was performed in the same manner as in Example 1 using the obtained catalyst. The results are shown in Table 1.

[Comparative Example 4]
A catalyst was produced in the same manner as in Example 1 except that the water content was concentrated to 30% by mass without adding an organic binder to the slurry. However, since the organic binder was not added, the molded body was not organized, and a molded body having a certain size could not be obtained with a piston-type extrusion molding machine.

Claims (7)

In a method for producing a methacrylic acid production catalyst containing at least molybdenum and vanadium as catalyst components, which is used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen,
Preparing a mixed solution or slurry in which the raw material compound of the catalyst component is mixed with water as a solvent;
A step of concentrating until the water content of the mixed solution or slurry becomes 21 to 70% by mass;
A step of adding an organic binder at any stage before, during or after concentration of the mixed solution or slurry, and a step of obtaining a molded body by molding the concentrate to which the organic binder has been added,
The manufacturing method of the catalyst for methacrylic acid manufacture characterized by having.   The method for producing a catalyst for methacrylic acid production according to claim 1, wherein the organic binder is added before concentration of the mixed solution or slurry.   The manufacturing method of the catalyst for methacrylic acid production of Claim 1 or 2 with which the process of obtaining the said molded object is performed by extrusion molding.   The said organic binder is 1 or more types selected from the group which consists of a cellulose derivative, polyvinyl alcohol, polyethyleneglycol, alpha glucan, and beta glucan, The manufacture of the catalyst for methacrylic acid manufacture of any one of Claim 1 to 3 Method.   The amount of the organic binder added to the mixed solution or slurry is 0.1 to 20 parts by mass with respect to 100 parts by mass of the raw material compound of the catalyst component as a solid content. The manufacturing method of the catalyst for methacrylic acid manufacture of description.   The catalyst for methacrylic acid manufacture obtained by the manufacturing method of the catalyst for methacrylic acid manufacture of any one of Claim 1 to 5.   A method for producing methacrylic acid, comprising subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid according to claim 6.