JP4678765B2 - A method for producing a metal oxide catalyst, and a method for producing an unsaturated aldehyde and an unsaturated carboxylic acid. - Google Patents

Description

Production method of the present invention is a metal oxide catalyst, and in the presence of a metallic oxide catalyst prepared in this way, propylene, isobutylene, tertiary butyl alcohol (hereinafter, also referred to as TBA) or methyl tert-butyl ether (hereinafter also referred to as MTBE) to gas phase catalytic oxidation with molecular oxygen, for producing how the unsaturated aldehyde and unsaturated carboxylic acid.

Conventionally, many proposals have been made on oxidation catalysts used for producing unsaturated aldehydes and unsaturated carboxylic acids by gas phase catalytic oxidation of, for example, propylene, isobutylene, TBA or MTBE, and methods for producing the same. For example, Patent Document 1 discloses a method of cleaning by pressing an abrasive against a rotary blade obtained by cutting a columnar material formed with a powder of a catalyst material such as a composite oxide. Non-Patent Document 2 discloses a method of cleaning a molding facility that handles catalyst material powder with water, alkali, or acid.
JP 2001-47396 A Granulation Handbook (1991), edited by Japan Powder Industrial Technology Association, published by Ohm Co., Ltd., pages 341-342

  However, a catalyst produced through a molding process using an apparatus such as a rotary blade or molding equipment washed by these methods is not necessarily sufficient as an industrial catalyst in terms of catalytic activity and target product selectivity. Further improvements are desired.

  Further, in these methods, since the catalyst material adheres to devices such as a rotary blade and molding equipment, there is a problem that the molded product cannot be stably manufactured and the productivity of the molded product is lowered.

  The present invention relates to a method for producing a metal oxide catalyst having excellent catalytic activity and target product selectivity, a metal oxide catalyst for producing an unsaturated aldehyde and an unsaturated carboxylic acid produced by this method, and the use of this catalyst. It is an object of the present invention to provide a method for producing highly active and highly selective unsaturated aldehydes and unsaturated carboxylic acids.

  It is another object of the present invention to provide a method for producing a metal oxide catalyst with high productivity.

  In order to achieve the above object, the inventors of the present invention provide a method for producing a metal oxide catalyst comprising a step of forming a catalyst material containing at least one of a metal oxide and a metal oxide precursor. As a result, it was found that a catalyst excellent in catalytic activity and selectivity can be produced with high productivity by washing the portion in contact with the catalyst material using alcohol. The invention has been completed.

  That is, the first of the present invention is a method for producing a metal oxide catalyst comprising a step of producing a molded product by molding a catalyst material containing at least one of a metal oxide and a metal oxide precursor. In this method, the portion of the apparatus in contact with the catalyst material and / or the molded article is washed intermittently or continuously with alcohol.

Furthermore, the present invention provides an unsaturated aldehyde and an unsaturated aldehyde characterized by subjecting propylene, isobutylene, TBA or MTBE to gas phase catalytic oxidation with molecular oxygen in the presence of the metal oxide catalyst produced by the method of the first invention. it is a manufacturing how saturated carboxylic acid.

  According to the method for producing a metal oxide catalyst of the present invention, a metal oxide catalyst having excellent catalytic activity and target product selectivity can be obtained, and a metal oxide catalyst can be produced with high productivity.

  The metal oxide catalyst produced by the method of the present invention can be used for producing unsaturated aldehydes and unsaturated carboxylic acids.

  According to the method for producing an unsaturated aldehyde and unsaturated carboxylic acid of the present invention, an unsaturated aldehyde and unsaturated carboxylic acid can be produced with high activity and high selectivity.

  Hereinafter, the manufacturing method of the metal oxide catalyst which is one Embodiment of this invention is demonstrated in detail. As described above, the method for producing a metal oxide catalyst of the present invention includes a step of producing a molded product by molding a catalyst material containing at least one of a metal oxide and a precursor of the metal oxide. In this production method, the part of the apparatus used in the step that is in contact with the catalyst material and / or the molded product is washed intermittently or continuously with alcohol.

  The composition of the metal oxide catalyst is not particularly limited. For example, a Mo—Bi-based oxide catalyst such as Mo—Bi—Co—Fe—Cs (a symbol such as Mo is an element symbol, the same shall apply hereinafter), Mo—V—Co—. Examples include Mo-V based oxide catalysts such as Cu and heteropolyacid based catalysts such as partially neutralized salts of phosphomolybdic acid.

  The present invention relates to an oxidation reaction in which the specific surface area of the catalyst and the state of pores on the surface greatly affect the selectivity of the target product (hereinafter also referred to as selectivity), for example, isobutylene, TBA and MTBE (hereinafter referred to as isobutylene and the like). Oxidation reaction from at least one compound selected from methacrolein and methacrylic acid, oxidation reaction from propylene to acrolein and acrylic acid, oxidation reaction from methacrolein to methacrylic acid, oxidation reaction from acrolein to acrylic acid Metal oxide catalyst used for reactions such as oxidation reaction from n-butane, n-butene to maleic anhydride, oxidation reaction from o-xylene, naphthalene to phthalic anhydride, oxidation reaction from methanol to formaldehyde Suitable for manufacturing. In particular, propylene, isobutylene, TBA or MTBE is suitable for the production of a catalyst for producing unsaturated aldehydes and unsaturated carboxylic acids by gas phase catalytic oxidation with molecular oxygen. In addition to the oxidation reaction, for example, it can be applied to an ammoxidation reaction from propylene to acrylonitrile, steam reforming of hydrocarbons, and the like.

For an oxidation reaction from isobutylene or the like to methacrolein or the like, or an oxidation reaction from propylene to acrolein or the like, a metal oxide catalyst having a composition represented by the following formula (1) is suitable.
_{Mo a Bi b Fe c M d} X e Y f Z g Si h O i (1)
In the formula (1), Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, M represents at least one element selected from the group consisting of cobalt and nickel, and X Represents at least one element selected from the group consisting of chromium, lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc, and Y represents phosphorus, boron, sulfur, selenium, tellurium, cerium , Z represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and thallium. a, b, c, d, e, f, g, h, and i represent the atomic ratio of each element, and when a = 12, b = 0.01-3, c = 0.01-5, d = 1 -12, e = 0 to 8, f = 0 to 5, g = 0.001 to 2, h = 0 to 20, and i is an atomic ratio of oxygen necessary to satisfy the valence of each component. It is.

A metal oxide catalyst having a composition represented by the following formula (2) is suitable for the oxidation reaction from acrolein to acrylic acid.
Mo _j V _{k Al} x _m Y _n O _o (2)
In the formula (2), Mo, V and O represent molybdenum, vanadium and oxygen, respectively, A represents at least one element selected from the group consisting of iron, cobalt, chromium, aluminum and strontium, X represents germanium, Represents at least one element selected from the group consisting of boron, arsenic, selenium, silver, silicon, sodium, tellurium, lithium, antimony, phosphorus, potassium, and barium; Y represents magnesium, titanium, manganese, copper, It represents at least one element selected from the group consisting of zinc, zirconium, niobium, tungsten, tantalum, calcium, tin and bismuth. J, k, l, m, n, and o represent the atomic ratio of each element. When j = 12, k = 0.01 to 6, l = 0 to 5, m = 0 to 10, n = 0. -5, and o is the atomic ratio of oxygen necessary to satisfy the valence of each component.

For the oxidation reaction from methacrolein to methacrylic acid, a metal oxide catalyst having a composition represented by the following formula (3) is suitable.
_{P p Mo q V r Cu s} X t Y u Z v O w (3)
In the formula (3), P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively, X represents antimony, bismuth, arsenic, germanium, zirconium, tellurium, selenium, silicon, tungsten, boron And at least one element selected from the group consisting of silver and Y is at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, manganese, cobalt, barium, gallium, cerium and lanthanum Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, and p, q, r, s, t, u, v and w represent atomic ratios of the respective elements. And when q = 12, p = 0.5-3, r = 0.01-3, s = 0-2, t = 0-3, u = 0-3, v They are 0.01 to 3, w is an atomic ratio of oxygen required to satisfy the valence of each component.

The manufacturing method of a metal oxide catalyst is implemented by the following process (1)-(3), for example. Here, the metal oxide may be a single oxide or a complex oxide, and further includes an isopolyacid and a salt thereof, a heteropolyacid having a heteroatom such as phosphorus, silicon, and arsenic and a salt thereof. The metal oxide catalyst may contain components other than the metal oxide, and examples of such components include platinum and cobalt. The metal oxide precursor is a compound that can be converted into a metal oxide by heat treatment, and examples thereof include sulfates, nitrates, carbonates, hydroxides, ammonium salts, and halides of metal elements.
(1) A step of producing a catalyst material containing at least one of a metal oxide and a metal oxide precursor (hereinafter also simply referred to as a catalyst material) (2) A step of producing a molded product by molding the catalyst material (3) ) A process for producing a metal oxide catalyst by drying and / or heat-treating a molded article.

  Various known methods can be applied to the step (1) of producing the catalyst material. For example, a method of producing particles as a catalyst material by drying an aqueous slurry of a compound (hereinafter also referred to as catalyst raw material) containing each metal element that is a raw material of a metal oxide, and pulverizing as necessary. . The form of the catalyst material is not particularly limited, and may be, for example, a powder form or a lump form other than the particulate form. However, it is preferably particulate because it is easy to control the pores and surface area of the final catalyst.

  The method for producing the aqueous slurry is not particularly limited, and examples thereof include known methods such as a precipitation method and an oxide mixing method. Examples of the catalyst raw material used for the production of the aqueous slurry include oxides, sulfates, nitrates, carbonates, hydroxides, ammonium salts, halides and the like of each metal element. For example, examples of the molybdenum raw material include ammonium paramolybdate and molybdenum trioxide. The raw material of the catalyst component may be used alone or in combination of two or more for each element.

  The method for producing the catalyst material from the aqueous slurry is not particularly limited. Examples of the method for producing the particulate catalyst material include a method of drying using a spray dryer, a method of drying using a slurry dryer, and a drum dryer. And the like, and a method of pulverizing a lump-like dried product by evaporating to dryness.

  The catalyst material obtained in this way may contain a salt such as nitrate derived from the catalyst raw material. When the catalyst material containing salt is molded as described later and then heat-treated, the salt may be decomposed during the heat treatment to lower the strength of the molded product. For this reason, the catalyst material is not only dried, but may be heat-treated at this point. The heat treatment conditions are not particularly limited, and for example, known conditions can be applied. The heat treatment is preferably performed in the temperature range of 200 to 600 ° C. in the presence of oxygen, air, nitrogen, nitrogen oxides and the like. The heat treatment temperature is preferably, for example, 400 ° C. to 600 ° C. in the case of the catalyst having the composition represented by the formula (1), and preferably 250 ° C. to 450 ° C. in the case of the catalyst having the composition represented by the formula (2). (3) In the case of the catalyst having the composition represented by the formula, 250 ° C. to 450 ° C. is preferable. The heat treatment time is appropriately selected depending on the target catalyst, but is preferably 5 hours to 30 hours.

  In step (2), the catalyst material produced in step (1) is molded to produce a molded product. The molding method is not particularly limited, and examples thereof include tableting molding, support molding, and extrusion molding. A method of extruding the particulate catalyst material is preferable in that the pores of the catalyst molded body can be easily controlled.

  In molding, an organic binder can be added to the catalyst material. The organic binder that can be used is not particularly limited. Cellulose derivatives, water-soluble or water-dispersible synthetic polymer compounds such as polyvinyl alcohol, and β-1,3-glucans such as curdlan, laminaran, paramylon, callose, pakiman, and scleroglucan. . Among these, cellulose derivatives are preferable because of their excellent moldability and catalyst selectivity, and methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl methyl cellulose are particularly preferable. The amount of the organic binder used is appropriately selected depending on the type and size of the catalyst material, the type of liquid, and the like, but is usually 0.05 to 15 mass with respect to 100 mass parts of the catalyst material obtained in the step (1). Part, preferably 0.1 to 10 parts by weight. As the amount of the organic binder added increases, the moldability tends to improve, and as the amount decreases, the removal of the organic binder by heat treatment after molding tends to become easier.

  Molded articles include, for example, known silica, alumina, silica-alumina, silicon carbide, titania, magnesia, inorganic compounds such as graphite and diatomaceous earth, glass fibers, ceramic balls and stainless steel, inorganic fibers such as ceramic fibers and carbon fibers. An inert carrier such as Such a molded article can be produced by mixing a catalyst material and an inert carrier before molding.

  The present invention is suitable for the production of a catalyst including a step of adding an organic binder to a catalyst material and extruding it, and particularly suitable for producing a catalyst while washing a cutting device for cutting an extruded product. As a specific example of such an extrusion molding process, for example, a catalyst material, an organic binder and a liquid are kneaded to obtain a kneaded product, which is used with an apparatus such as an auger type extruder or a piston type extruder. Examples thereof include a method of extruding to form an extrudate, and cutting this into a formed product. The shape of the obtained molded product is not particularly limited, and examples thereof include a ring shape, a columnar shape, and a columnar shape having a star shape at the bottom.

  When the catalyst material is molded, a metal oxide or a precursor thereof adheres to a portion where the catalyst material of the used apparatus and / or the molded product is in contact. Examples of the place where the adhesion occurs include, for example, a punch or a mortar part of a tableting machine in the case of tableting, and a cutting blade of a kneader or an extruder or a cutting device in the case of extrusion molding. Such a part needs to be washed in order to stably produce a molded product.

  In the present invention, the portion of the apparatus used in step (2) where the catalyst material and / or the molded product thereof is in contact is washed intermittently or continuously using alcohol. The term “intermittent” means, for example, that the cleaning is performed at regular intervals or when the adhesion of the metal oxide or its precursor exceeds an allowable range. Further, continuous means, for example, that a portion where the catalyst material and / or the molded product thereof is not always in contact, such as a circular rotary cutting blade (rotating blade), is continuously cleaned without leaving an interval. In addition, it is preferable not to suspend the molding operation from the viewpoint of the productivity of the molded product at the time of cleaning, but it may be suspended.

  The method of cleaning with alcohol is not particularly limited as long as it is a method in which alcohol comes into contact with the catalyst material of the apparatus used and / or the part (hereinafter also referred to as a soiled part) in contact with the molded product. As a cleaning method, for example, a method of washing out a dirty part with alcohol, a method of spraying the dirt part to contact the alcohol and wiping or scraping with an adhering substance, or wiping the dirty part with a member soaked with alcohol or For example, a method of scraping off deposits may be used. As described above, not only alcohol but also physical cleaning means such as wiping or scraping may be used in combination for cleaning.

  1 and 2 show a multi-rotating blade cutting machine that can be suitably used for cutting an extrudate of a catalyst material. Hereinafter, the present invention will be described by taking this cutting machine as an example. Reference numeral 1 denotes a columnar extrudate obtained by extruding a catalyst material. First, the extruded product 1 is disposed behind the inclined plate-shaped lower guide plate 2. A cylindrical rotary roll 7 is provided on the distal end side of the lower guide plate 2 so as to rotate about its axis. On the rotary roll 7 and the lower guide plate 2, a plate-like upper guide is provided. A plate 4 is provided. The tip portion 4a of the upper guide plate 4 has a comb blade shape and is provided with a plurality of slits 4b. In each of the cuts 4b, peripheral portions of a plurality of disk-shaped rotary blades 6a of a cutting machine 6 provided on the upper guide plate 4 are respectively inserted rotatably. In this cutting machine 6, the rotary blades 6a are integrally fixed to the rotary shaft 6b in a state where the rotary blades 6a are spaced apart from each other by a predetermined distance, and all the rotations are made by the rotation of the rotary shaft 6b. The blade 6a rotates in the same direction. Next, the extruded product 1 is fed between the lower guide plate 2 and the upper guide plate 4 according to the inclination of the lower guide plate 2. Then, the extruded product 1 fed under the respective cuts 4b of the upper guide plate 4 is sandwiched and cut by the rotation of the rotary roll 7 and the plurality of rotary blades 6a protruding from the cuts 4b. A plurality of molded products 1a are obtained. Accordingly, the lower guide plate 2, the upper guide plate 4, the cutting machine 6, and the rotary roll 7 constitute a cutting means 8. As the cutting of the extruded product 1 is repeated, dirt accumulates on both the outer peripheral edge and both side surfaces of each rotary blade 6a. In this case, the adhesion of dirt on both side surfaces becomes more significant as the thickness of the extruded product 1 increases, and the cutting ability of each rotary blade 6a is greatly reduced. As shown in FIG. 1, dressing members 9 are provided in the vicinity of each rotary blade 6a. The dressing member 9 is selected depending on the properties of the deposit, and is not particularly limited. For example, a nylon brush, an abrasive, a non-woven fabric, or the like is applicable. The dressing member 9 is held by a holder 10 and is moved perpendicularly to the axis of the rotary shaft 6b by a drive mechanism (not shown) and pressed so as to bite each rotary blade 6a, and rotates in the pressed state. It can be moved in the axial direction of the shaft 6b. Accordingly, the cleaning device is constituted by the drive mechanism, the dressing member 9 and the like.

  Next, a method for cleaning the rotary blade 6a will be described. First, alcohol is sprayed from the opposite side of the rotary roll to the outer edge portion of the rotary blade 6a that is cutting the extrudate 1 by a sprayer (not shown). This spraying operation may be performed continuously or intermittently. Further, as shown in FIG. 3, the dressing member 9 is moved perpendicularly to the axis CL of the rotary shaft 6b by driving the drive mechanism through the holder 10, and pressed so that each rotary blade 6a bites into this. (Pressing step (a)). After this pressing step (a), as shown in FIG. 4, the dressing member 9 is moved in parallel to the right side in the direction of the axis CL of the rotating shaft 6 b by driving the drive mechanism via the holder 10 (right side parallel movement). Step (b)). After this right translation step (b), as shown in FIG. 5, the dressing member 9 is moved in parallel to the left side in the direction of the axis CL of the rotating shaft 6b by driving the drive mechanism via the holder 10 (left side translation) Step (c)). As described above, in the pressing step (a), the adhering matter is removed from the outer peripheral edge 6e of each rotary blade 6a for cleaning, and the right side translation step (b) and the left side translation step (c). Then, the dressing member 9 comes into contact with both side surfaces 6s (left side surface and right side surface) of each rotary blade 6a and rubs them to remove the deposit F. In the pressing step (a), the rotary blade 6a needs to bite into the dressing member 9 to some extent. In order to facilitate biting, the dressing member 9 may be cut in advance. The operations of the steps (a) and (b) and (c) may be performed continuously or intermittently, but the dressing member 9 is applied to the outer peripheral edge 6e and the side surfaces 6s of each rotary blade 6a. If they are always pressed, a load is always applied to each rotary blade 6a and the rotary drive mechanism that rotationally drives the rotary blade 6a, which may cause problems such as rapid wear and tear. Preferably. When the operations of the steps (a) and (b) and (c) are performed intermittently, the operation and the alcohol spraying operation may or may not be linked. However, for the reason that the cleaning effect is great, a method of spraying a large amount of alcohol just before the operation of (b) and / or (c) is preferable.

  The alcohol used for washing in the present invention is not particularly limited, and examples thereof include lower alcohols such as ethyl alcohol, methyl alcohol, propyl alcohol, and butyl alcohol, and higher alcohols such as octyl alcohol, decyl alcohol, and lauryl alcohol. Of these, lower alcohols are preferred in view of economy and ease of handling, and ethyl alcohol is particularly preferred. The alcohol used may be one type or a combination of two or more types. Commercially available alcohols may contain water and other compounds, but they can be used as they are. Moreover, you may use together cleaning agents other than alcohol for washing | cleaning. Here, the combined use includes not only the case of using a mixture of alcohol and a cleaning agent other than alcohol, but also the case of individual cleaning. Examples of the cleaning agent other than alcohol include water, an aqueous acid solution, an aqueous alkaline solution, a surfactant, and soap. However, if these are used for washing, the reaction performance of the metal oxide catalyst may be lowered, so that the amount used is preferably small.

  In step (3), the molded product produced in step (2) is dried and / or heat-treated to produce a metal oxide catalyst. The method in the case of drying a molded article is not specifically limited, For example, arbitrary methods, such as hot-air drying, humidity drying, far-infrared drying, and microwave drying, can be used. Of these, hot air drying or microwave drying is preferred because it is simple and excellent in selectivity. Conditions for drying can be appropriately selected so that the liquid content of the molded product can be lowered to the target value. The drying temperature is preferably 50 to 150 ° C. The method for performing heat treatment, so-called calcination, is not particularly limited. For example, a method of performing a reaction using a metal oxide catalyst, a method of performing in a box-type calcination furnace, a method of performing in a tunnel-type calcination furnace Any method can be used. Known conditions can be applied for firing. The heat treatment is preferably performed in the temperature range of 200 to 600 ° C. in the presence of oxygen, air, nitrogen, nitrogen oxides and the like. The heat treatment temperature is preferably, for example, 400 ° C. to 600 ° C. in the case of the catalyst having the composition represented by the formula (1), and preferably 250 ° C. to 450 ° C. in the case of the catalyst having the composition represented by the formula (2). (3) In the case of the catalyst having the composition represented by the formula, 250 ° C. to 450 ° C. is preferable. The heat treatment time is appropriately selected depending on the target catalyst, but is preferably 5 hours to 30 hours. When the catalyst material is heat-treated in step (1), the heat treatment in step (3) can be omitted. In addition, the catalyst material can be heat-treated in the step (1), and additives such as a binder can be decomposed by the heat-treatment in the step (3).

  Next, a method for performing a reaction using a metal oxide catalyst will be described. The reaction that can be used is a reaction other than the above-described oxidation reaction or oxidation reaction, and is not particularly limited as long as the reaction can use a metal oxide catalyst. The reaction format may be either a gas phase reaction or a liquid phase reaction. However, the method of the present invention is suitable for producing a metal oxide catalyst for a gas phase catalytic oxidation reaction. In particular, propylene, isobutylene, TBA or MTBE is suitable for the production of a catalyst for producing unsaturated aldehydes and unsaturated carboxylic acids by gas phase catalytic oxidation with molecular oxygen.

  The type of the reactor used for the reaction is not particularly limited, and examples thereof include a fixed bed tubular reactor and a fluidized bed. In the case of the gas phase catalytic oxidation reaction using the catalyst having the composition represented by the above formulas (1) to (3), it is preferable to use a fixed bed tubular reactor, particularly a fixed bed multitubular reactor. Various conditions for carrying out the reaction using a fixed bed tubular reactor vary depending on the type of reaction and cannot be generally stated, but known conditions for each reaction can be applied. Examples of the case of performing an oxidation reaction from isobutylene or the like to methacrolein and methacrylic acid and the case of performing an oxidation reaction from propylene to acrolein and acrylic acid using the metal oxide catalyst having the composition of the formula (1) are shown below. The conditions for the reaction will be described.

  When an oxidation reaction from isobutylene or the like to methacrolein or methacrylic acid is performed, a raw material gas containing isobutylene or the like and molecular oxygen is brought into contact with the metal oxide catalyst. The concentration of isobutylene or the like in the raw material gas is preferably 1 to 20% by volume, and the molar ratio of isobutylene or the like and oxygen in the raw material gas is preferably 1: 0.5 to 1: 3. The source gas preferably contains water vapor at a concentration of 1 to 45% by volume. The remainder of the reaction gas is composed of inert gas such as nitrogen and carbon dioxide, trace components contained in air, isobutylene, and the like. The reaction pressure is usually 0 to several hundred kPa (gauge pressure), the reaction temperature is usually 250 to 400 ° C., and the contact time is usually 1.5 to 15 seconds.

  When an oxidation reaction from propylene to acrolein and acrylic acid is performed, a raw material gas containing propylene and molecular oxygen is brought into contact with the metal oxide catalyst. The propylene concentration in the raw material gas is preferably 1 to 20% by volume, and the molar ratio of propylene and oxygen in the raw material gas is preferably 1: 0.5 to 1: 3. The source gas preferably contains water vapor at a concentration of 1 to 45% by volume. The remainder of the reaction gas is composed of inert gases such as nitrogen and carbon dioxide, and trace components contained in air and isobutylene. The reaction pressure is usually 0 to several hundred kPa (gauge pressure), the reaction temperature is usually 250 to 400 ° C., and the contact time is usually 1.5 to 15 seconds.

  The details of the reason why the metal oxide catalyst produced by the method of the present invention is excellent in activity and target product selectivity are unknown, but the following mechanism is estimated. In the conventional cleaning method using only water, the water adheres to the catalyst material or the molded product and dissolves a part of the surface to change the composition and the state of the pores of the part. That is, the catalyst performance was lowered due to the local change of the catalyst composition and the clogging of the pores caused by the dissolution of the easily soluble components such as alkali metal and binder. In the present invention, it is presumed that such problems are reduced because the alcohol hardly dissolves the catalyst material and the binder.

  Also, in the method of scraping off dirt without using water, dry particles of small catalyst material remain on the cutting blade and molding machine due to insufficient cleaning power, and it mixes in the product and deteriorates moldability. Although it is considered that problems such as selectivity and shape deterioration have occurred, it is presumed that in the present invention, such problems are reduced because the cleaning power is high.

Hereinafter, the present invention will be described using examples and comparative examples. Here, “part” means part by mass. The analysis of the reaction source gas and the reaction gas (product gas) was performed using gas chromatography. Reaction rate of raw material olefins (isobutylene, TBA or propylene) in Examples and Comparative Examples, selectivity of unsaturated aldehyde to be produced (methacrolein or acrolein), selectivity of unsaturated carboxylic acid (methacrylic acid or acrylic acid) The total yield of unsaturated aldehyde and unsaturated carboxylic acid (hereinafter also referred to as total yield) was calculated by the following formula.
Reaction rate of raw material olefin, etc. (%) = A / B × 100
Selectivity of unsaturated aldehyde (%) = C / A × 100
Selectivity of unsaturated carboxylic acid (%) = D / A × 100
Total yield (%) = (C + D) / B × 100
Here, A is the number of moles of the reacted raw material olefin, B is the number of moles of the supplied raw material olefin, C is the number of moles of the generated unsaturated aldehyde, and D is the number of moles of the generated unsaturated carboxylic acid.

The reaction rate of the raw material unsaturated aldehyde (methacrolein or acrolein), the selectivity of the unsaturated carboxylic acid (methacrylic acid or acrylic acid) to be produced, and the yield of the unsaturated carboxylic acid in the examples and comparative examples are as follows: Calculated by
Reaction rate of unsaturated aldehyde (%) = E / F × 100
Selectivity of unsaturated carboxylic acid (%) = G / E × 100
Unsaturated carboxylic acid yield (%) = G / F × 100
Here, E is the number of moles of reacted unsaturated aldehyde, F is the number of moles of supplied raw material unsaturated aldehyde, and G is the number of moles of unsaturated carboxylic acid produced.

Example 1
To 1000 parts of pure water, 500 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate, 23.0 parts of cesium nitrate, 24.0 parts of antimony trioxide and 33.0 parts of bismuth trioxide were added and stirred with heating. (Liquid A). Separately, add 209.8 parts of ferric nitrate, 68.6 parts of nickel nitrate, 446.4 parts of cobalt nitrate, 23.5 parts of lead nitrate, and 2.8 parts of 85% phosphoric acid to 1000 parts of pure water and dissolve. (Liquid B). After liquid B was added to liquid A to form an aqueous slurry, this aqueous slurry was formed into dry spherical particles having an average particle diameter of 60 μm using a spray dryer. The dried spherical particles were calcined at 300 ° C. for 1 hour and at 510 ° C. for 3 hours to produce a catalyst material having a spherical particle shape.

  To 500 parts of the catalyst material, 20 parts of hydroxypropylmethylcellulose and 5 parts of curdlan were added and dry mixed. 190 parts of pure water was mixed here, and after mixing (kneading) until it became a clay-like substance with a kneader, the obtained kneaded product was extruded using a piston-type extruder, the outer diameter was 5 mm, An extruded product having an inner diameter of 2 mm and an average length of 5 mm was produced. The cutting machine shown in FIGS. 1 and 2 was used for cutting, and the molding was stopped intermittently every 10 minutes, and 20 parts of ethyl alcohol (a special grade with a purity of 99.5% by mass) was added each time. It sprayed on the outer edge of the cutting blade, and the rotary blade was washed with a nylon brush as a dressing member. When the extrusion molding was repeated for 5 hours, the yield of the molded product was 100,000 parts. The time required for extrusion molding includes a pause period for filling the kneaded material into the molding machine in the middle and a pause period for removing molding defects, and the yield of molded articles does not include molding defects ( The same applies hereinafter).

Next, the molded product was dried at 110 ° C. using a hot air dryer, and further calcined at 400 ° C. for 3 hours in a reactor to produce a metal oxide catalyst. The composition of elements other than oxygen in the metal oxide catalyst (hereinafter the same) is Mo ₁₂ W _0.1 Bi _0.6 Fe _2.2 Sb _0.7 Ni _1.0 Co _6.5 Pb _0.3 P _{0. 1} Cs was _0.5 .

  This metal oxide catalyst was filled in a stainless steel reaction tube, and using a source gas of 5% by volume of isobutylene, 12% by volume of oxygen, 10% by volume of water vapor, and 73% by volume of nitrogen, under atmospheric pressure, a contact time of 3.6 seconds, The reaction was carried out at a reaction temperature of 340 ° C. As a result, the reaction rate of isobutylene was 98.0%, the selectivity of methacrolein was 89.9%, and the selectivity of methacrylic acid was 4.0%.

(Example 2)
In Example 1, in place of the cleaning that was performed by intermittently stopping the molding every 10 minutes, 20 parts of ethyl alcohol (special grade having a purity of 99.5% by mass) was added every 10 minutes without stopping the molding. A metal oxide catalyst was produced and reacted in the same manner as in Example 1 except that the rotating blade was washed with a nylon brush as a dressing member by spraying. As a result, the yield of the molded product was 120,000 parts. Further, the reaction rate of isobutylene was 98.0%, the selectivity of methacrolein was 89.9%, and the selectivity of methacrylic acid was 3.9%.

(Example 3)
In Example 1, water-containing ethyl alcohol (95 mass% ethanol-5 mass% water) was used instead of ethyl alcohol (purity 99.5 mass%), and the reaction raw material was changed from isobutylene to TBA. As in Example 1, a metal oxide catalyst was produced and reacted. As a result, the yield of the molded product was 90000 parts. The reaction rate of TBA was 100%, the selectivity of methacrolein was 89.1%, and the selectivity of methacrylic acid was 3.2%.

(Comparative Example 1)
A metal oxide catalyst was produced and reacted in the same manner as in Example 1 except that water was used instead of ethyl alcohol in Example 1. As a result, adhesion of the molded product to the cutting blade and a change in shape occurred during molding, resulting in an increase in downtime and defective molded product, resulting in a molded product yield of 60000 parts. The reaction rate of isobutylene was 97.6%, the selectivity of methacrolein was 89.6%, and the selectivity of methacrylic acid was 3.4%.

(Comparative Example 2)
A metal oxide catalyst was produced and reacted in the same manner as in Example 2 except that water was used instead of ethyl alcohol in Example 2. As a result, the adhesion of the molded product to the cutting blade and the shape change occurred remarkably during the molding, resulting in an increase in downtime and defective molded product, resulting in a molded product yield of 45,000 parts. The reaction rate of isobutylene was 97.4%, the selectivity of methacrolein was 89.5%, and the selectivity of methacrylic acid was 3.4%.

(Comparative Example 3)
In Example 1, a metal oxide catalyst was produced and reacted in the same manner as in Example 1 except that ethyl alcohol was not sprayed and cleaning was performed only with a nylon brush. As a result, adhesion of the molded product to the cutting blade and shape change occurred during molding, resulting in an increase in downtime and defective molded product, resulting in a molded product yield of 50000 parts. The reaction rate of isobutylene was 97.5%, the selectivity of methacrolein was 89.5%, and the selectivity of methacrylic acid was 3.4%.

(Comparative Example 4)
In Example 3, a metal oxide catalyst was produced and reacted in the same manner as in Example 3 except that water was used instead of hydrous ethyl alcohol. As a result, adhesion of the molded product to the cutting blade and shape change occurred during molding, resulting in an increase in downtime and defective molded product, resulting in a yield of the molded product of 42000 parts. Further, the reaction rate of TBA was 100%, the selectivity of methacrolein was 88.5%, and the selectivity of methacrylic acid was 2.8%.

Example 4
100 parts of ammonium paramolybdate, 3.3 parts of ammonium metavanadate and 4.8 parts of potassium nitrate were dissolved in 400 parts of pure water. While stirring this, a solution in which 8.2 parts of 85 mass% phosphoric acid was dissolved in 10 parts of pure water was added, and a solution in which 1.2 parts of copper nitrate was dissolved in 10 parts of pure water was further added. Next, after adding a solution obtained by dissolving 1.4 parts of zinc nitrate in 10 parts of pure water, the temperature was raised to 95 ° C. A solution prepared by dissolving 3.3 parts of 60% by mass of arsenic acid in 10 parts of pure water was added, followed by 2.8 parts of antimony trioxide and 2.0 parts of germanium dioxide. The solution was evaporated to dryness with stirring, and the resulting solid was dried at 130 ° C. for 16 hours. Thereafter, the catalyst material was pulverized using a ball mill to produce a powdery catalyst material.

  To 500 parts of this catalyst material, 15 parts of hydroxypropylmethylcellulose was added and dry mixed. 175 parts of ethyl alcohol was added here and mixed (kneaded) until it became clay-like with a kneader, then extruded using a piston-type extruder, and had an outer diameter of 6 mm, an inner diameter of 2 mm, and a length of 5 mm. Extrudates were produced. The cutting machine shown in FIGS. 1 and 2 is used for cutting, and without stopping molding every 10 minutes, 20 parts of ethanol is sprayed on the outer edge of the cutting blade and the rotary blade is washed with a dressing member of nylon brush did. The molded product yield was 125,000 parts when extrusion molding was repeated for 5 hours.

Next, the molded article was dried at 130 ° C. for 6 hours using a hot air dryer, and further calcined at 380 ° C. for 5 hours in an air stream to produce a metal oxide catalyst. The elemental composition of the metal oxide catalyst _{was P 1.5 Mo 12 V 0.6 Cu 0.1} Sb 0.4 Ge 0.4 As 0.3 Zn 0.1 K 1.

  This metal oxide catalyst is packed into a stainless steel reaction tube, and using a source gas of 5% methacrolein, 10% oxygen, 30% water vapor and 55% (volume%) nitrogen, at atmospheric pressure, a contact time of 3.6 seconds. The reaction was carried out at a reaction temperature of 290 ° C. As a result, the reaction rate of methacrolein was 86.5%, and the selectivity of methacrylic acid was 86.2%.

(Comparative Example 5)
A metal oxide catalyst was produced and reacted in the same manner as in Example 4 except that water was used in place of ethyl alcohol in Example 4. As a result, adhesion of the molded product to the cutting blade and a change in shape occurred significantly during molding, resulting in an increase in downtime and defective molded product, resulting in a molded product yield of 38000 parts. The reaction rate of methacrolein was 84.2%, and the selectivity of methacrylic acid was 84.3%.

It is a figure which shows one Embodiment of the washing | cleaning apparatus of the rotary blade of this invention, Comprising: It is a perspective view. It is a figure which shows the cutting machine wash | cleaned with the same washing | cleaning apparatus, Comprising: It is the view seen from the arrow A side of FIG. It is a figure which shows the first process of the washing | cleaning method by the washing | cleaning apparatus, Comprising: It is a principal part enlarged view. It is a figure which shows the next process of the washing | cleaning method by the washing | cleaning apparatus, Comprising: It is a principal part enlarged view. It is a figure which shows the next process of the washing | cleaning method by the washing | cleaning apparatus, Comprising: It is a principal part enlarged view.

Explanation of symbols

6a ... rotary blade 6b ... rotating shaft 6e ... outer peripheral edge 6s ... side face 9 ... dressing member (abrasive)
CL ... axis F ... deposit

Claims (2)

  In a method for producing a metal oxide catalyst comprising a step of producing a molded product by molding a catalyst material containing at least one of a metal oxide and a metal oxide precursor, the catalyst material of the apparatus used in the step and / or Alternatively, the method is characterized in that the part in contact with the molded product is washed intermittently or continuously with alcohol. A metal oxide catalyst is produced by the production method according to claim 1, and propylene, isobutylene, tertiary butyl alcohol or methyl tertiary butyl ether is subjected to gas phase catalytic oxidation with molecular oxygen in the presence of the obtained catalyst. A method for producing an unsaturated aldehyde and an unsaturated carboxylic acid.

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