JP2009006236A - PALLADIUM-CONTAINING CATALYST, ITS MANUFACTURING METHOD AND MANUFACTURING METHOD OF alpha,beta-UNSATURATED CARBOXYLIC ACID - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for manufacturing α,β-unsaturated carboxylic acid with high productivity from olefin or α,β-unsaturated aldehyde, to provide a manufacturing method of the catalyst and to provide a manufacturing method of α,β-unsaturated carboxylic acid using the same. <P>SOLUTION: The palladium-containing catalyst is manufactured so that the catalyst contains 0.001-0.15 mols of platinum element per 1.0 mol of palladium element. The catalyst is used for manufacturing α,β-unsaturated carboxylic acid. Further, it is preferable that the catalyst contains 0.001-0.40 mols of tellurium element per 1.0 mol of palladium element. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde and a method for producing the same. The present invention also relates to a method for producing an α, β-unsaturated carboxylic acid.

  Many α, β-unsaturated carboxylic acids are industrially useful. For example, acrylic acid and methacrylic acid are used in extremely large quantities for applications such as synthetic resin raw materials.

As a method for producing an α, β-unsaturated carboxylic acid, research has been conducted on a method for producing an olefin or α, β-unsaturated aldehyde by liquid phase oxidation with molecular oxygen. As a catalyst for producing α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin or α, β-unsaturated aldehyde with molecular oxygen, for example, in Patent Document 1, palladium, platinum, rhodium or ruthenium is used as a catalyst. Acrylic acid production by the oxidation of propylene used as a catalyst, and Patent Documents 2 and 3 propose the production of an α, β-unsaturated carboxylic acid by oxidation of an olefin using palladium as a catalyst.
US Pat. No. 3,624,147 JP-A-56-115737 International Publication No. 05/118134 Pamphlet

  However, in the liquid phase oxidation using the palladium-containing catalyst of Patent Documents 1 to 3, the productivity of the target product α, β-unsaturated carboxylic acid is not always sufficient, and further improvement in productivity is desired. It was.

  An object of the present invention is to provide a catalyst for producing an α, β-unsaturated carboxylic acid with high productivity from an olefin or an α, β-unsaturated aldehyde, a method for producing the catalyst, and α, β- using the catalyst. It is providing the manufacturing method of unsaturated carboxylic acid.

  The present invention relates to a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, and 0.001 to 0.15 platinum element per 1 mol of palladium element. Palladium-containing catalyst containing moles.

  The present invention also relates to a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, wherein the platinum element is 0.001 to 0 per 1 mol of palladium element. A palladium-containing catalyst containing .15 moles and 0.001-0.4 moles of tellurium element.

  The present invention also provides a palladium-containing catalyst in which a catalytically active component is supported on a carrier.

  The present invention is also a method for producing a palladium-containing catalyst, comprising a step of reducing a compound containing palladium element in an oxidized state with a reducing agent, and a step of reducing a compound containing platinum element in an oxidized state with a reducing agent. It is a manufacturing method of a palladium containing catalyst.

  Furthermore, the present invention is a method for producing an α, β-unsaturated carboxylic acid in which an olefin or an α, β-unsaturated aldehyde is subjected to liquid phase oxidation with molecular oxygen using the palladium-containing catalyst.

  According to the present invention, a palladium-containing catalyst capable of obtaining an α, β-unsaturated carboxylic acid with high productivity from an olefin or an α, β-unsaturated aldehyde, a method for producing the same, and an α, β- using the same. A method for producing an unsaturated carboxylic acid can be provided.

  The palladium-containing catalyst of the present invention (hereinafter also referred to as “catalyst” for short) produces α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin or α, β-unsaturated aldehyde with molecular oxygen. (Hereinafter, also referred to as “liquid phase oxidation” for short), a platinum element containing 0.001 to 0.15 mol per mol of palladium element. The catalyst preferably further contains 0.001 to 0.4 mol of tellurium element with respect to 1 mol of palladium element.

  By setting the number of moles of platinum element relative to 1 mole of palladium element in the catalyst (that is, the molar ratio of platinum element to palladium element: Pt / Pd) within such a predetermined range, the olefin or α, β-unsaturated aldehyde can be used. A catalyst capable of producing an α, β-unsaturated carboxylic acid with high productivity is obtained. Pt / Pd is preferably 0.005 to 0.10, and more preferably 0.01 to 0.07. Further, by setting the number of moles of tellurium to 1 mole of palladium element in the catalyst (that is, the molar ratio of tellurium element to palladium element: Te / Pd), the olefin or α, β-unsaturated aldehyde can be changed to α, It becomes a catalyst capable of producing β-unsaturated carboxylic acid with higher productivity. Te / Pd is more preferably 0.005 to 0.35, and still more preferably 0.01 to 0.3. The Pt / Pd and Te / Pd are palladium compounds (hereinafter also referred to as “Pd raw materials”), platinum compounds (hereinafter also referred to as “Pt raw materials”), and tellurium compounds (which are used in the production of palladium-containing catalysts). Hereinafter, it can be adjusted by the blending ratio of “Te raw material”).

  Pt / Pd can be calculated from the mass and atomic weight of platinum element and palladium element contained in the catalyst. The masses of platinum and palladium contained in the catalyst can be quantified by elemental analysis. In addition, when the catalyst is manufactured by a method in which the catalyst contains substantially all of palladium element and platinum element contained in the Pd raw material and Pt raw material as in the pore filling method, the palladium element content of the Pd raw material used. The mass of both elements may be calculated from the blending amount, the platinum element content of the Pt raw material to be used, and the blending amount. Te / Pd can also be quantified by the same method.

As a method for determining the mass of palladium element and platinum element in the catalyst by elemental analysis, the following A treatment liquid and B treatment liquid are prepared and analyzed. The tellurium element can be measured similarly.
Preparation of treatment solution A: 0.2 g of catalyst and a predetermined amount of concentrated nitric acid, concentrated sulfuric acid, and hydrogen peroxide water were placed in a Teflon (registered trademark) decomposition tube, and a microwave thermal decomposition apparatus (CEM, MARS5 (product) Name)). The sample is filtered, and the filtrate and washing water are combined, and the volume is made up in a volumetric flask to obtain the treatment solution A.
Preparation of B treatment solution: The filter paper in which the insoluble parts in the A treatment are collected is transferred to a platinum crucible, heated and incinerated, and then added with lithium metaborate and melted with a gas burner. After cooling, add hydrochloric acid and a small amount of water in a crucible and dissolve, then add up to a volumetric flask to make the B treatment solution.

  The mass of platinum element and palladium element contained in the obtained A treatment liquid and B treatment liquid was quantified with an ICP emission analyzer (manufactured by Thermo Elemental, IRIS-Advantage (trade name)), and the elements in both treatment liquids The mass of each element in the catalyst can be determined from the total mass of each.

  The catalyst of the present invention as described above may be a non-supported type, but a supported type in which a catalytically active component (at least one of palladium element, platinum element and tellurium element) is supported on a support is preferable. Examples of the carrier include activated carbon, carbon black, silica, alumina, magnesia, calcia, titania and zirconia. Among these, silica, alumina, magnesia, calcia, titania and zirconia are more preferable, and silica, titania and zirconia are particularly preferable. One type of carrier may be used, but two or more types may be used. When using 2 or more types, for example, a mixture such as a mixed oxide obtained by mixing silica and alumina, a composite such as silica-alumina which is a composite oxide, and the like can be given.

The preferred specific surface area of the support can not be said sweepingly because different by the kind of carrier, the case of silica, preferably at least ^{50m 2 / g, 100m 2 /} g or more is more preferable. Moreover, 1500 m < ² > / g or less is preferable and 1000 m < ² > / g or less is more preferable. The smaller the specific surface area of the support is, the more the catalyst having a useful component (palladium element or platinum element) supported on the surface can be produced, and the larger the specific surface area, the more the useful component can be produced.

  The pore volume of the carrier is not particularly limited, but is preferably 0.1 cc / g or more, and more preferably 0.2 cc / g or more. Moreover, 2.0 cc / g or less is preferable and 1.5 cc / g or less is more preferable.

  The shape and size of the carrier vary depending on the shape and size of the reaction apparatus and are not particularly limited, and examples thereof include various shapes such as powder, granules, spheres, and pellets. Among these, granular and spherical shapes are preferable because they are easy to operate such as filtration. When the carrier is powdery or granular, the particle size (median diameter) is preferably 0.5 μm or more, and more preferably 1.0 μm or more. Moreover, 200 micrometers or less are preferable and 100 micrometers or less are more preferable. The larger the particle size of the carrier, the easier the separation of the catalyst and the reaction solution, and the smaller the support, the better the dispersibility of the catalyst in the reaction solution.

  In the case of a supported catalyst, the total supported rate of palladium element and platinum element with respect to the support is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass relative to the mass of the carrier before support. 0-20 mass% is further more preferable.

  In the case of a supported catalyst, the loading rate can be calculated from the mass of each element determined by the above method and the mass of the carrier used. The mass of the carrier can also be quantified by the following method. That is, the catalyst is placed in a platinum crucible and melted by adding sodium carbonate. Thereafter, distilled water is added to obtain a uniform solution, and a specific element in the sample solution is quantified by ICP emission analysis. For example, in the case of a silica carrier, Si element is quantified.

  The catalyst of the present invention may contain other metal elements other than palladium element, platinum element and tellurium element. Examples of other metal elements include rhodium, ruthenium, iridium, gold, silver, osmium, copper, lead, antimony, bismuth, thallium, mercury, and the like. One or more other metal elements can be contained. From the viewpoint of expressing high catalytic activity, the total of palladium element, platinum element, and tellurium element is preferably 60% by mass or more, more preferably 80% by mass or more, among the metal elements contained in the catalyst. .

  The manufacturing method of the catalyst of this invention is demonstrated.

  The catalyst of the present invention includes a step of reducing a compound containing palladium element in an oxidized state with a reducing agent (hereinafter also referred to as “Pd reduction step”), and a step of reducing a compound containing platinum element in an oxidized state with a reducing agent. (Hereinafter, also referred to as “Pt reduction step”). Furthermore, when producing a catalyst containing tellurium element, it can be suitably produced by a method including a Pd reduction step, a Pt reduction step, and a step of adding a compound containing tellurium element (hereinafter also referred to as “Te addition step”). .

  Examples of the palladium compound containing palladium element in an oxidized state include palladium salts, palladium oxides, palladium oxide alloys, etc. Among them, palladium salts are preferable. Examples of the palladium salt include palladium chloride, palladium acetate, palladium nitrate, palladium sulfate, tetraamminepalladium chloride and bis (acetylacetonato) palladium, among which palladium chloride, palladium acetate, palladium nitrate, tetraammine. Palladium chloride is preferred.

  Examples of the platinum compound containing platinum element in an oxidized state include platinum salts and platinum oxide. Specifically, chloroplatinic acid, iodinated platinic acid, dichlorodiammine platinum, dinitrodiammine platinum, tetraammine platinum chloride, tetraammine platinum nitrate, tetraammine platinum acetate, tetraammine platinum sulfate, potassium tetrachloroplatinate, hexachloroplatinic acid Examples include potassium, potassium tetranitroplatinate, potassium tetrabromoplatinate, hexahydroxoplatinic acid, bis (acetylacetonato) platinum, and platinum oxide. Of these, chloroplatinic acid, dichlorodiammine platinum, dinitrodiammine platinum, tetraammine platinum chloride, tetraammine platinum nitrate, tetraammine platinum acetate, bis (acetylacetonato) platinum and the like are preferable.

  Examples of the tellurium compound containing the tellurium element include tellurium metal, tellurium salt, telluric acid and its salt, telluric acid and its salt, tellurium oxide and the like. Examples of tellurium salts include hydrogen telluride, tellurium tetrachloride, tellurium dichloride, tellurium hexafluoride, tellurium tetraiodide, tellurium tetrabromide, tellurium dibromide, and the like. Examples of tellurate include sodium tellurate and potassium tellurate. Examples of tellurite include sodium tellurite and potassium tellurite. Of these, telluric acid and its salt, telluric acid and its salt, and tellurium oxide are preferred. Since reduction of the Te raw material is not necessarily essential, the tellurium element contained in the Te raw material may be in an oxidized state, a reduced state, or a metal state.

In addition to the method using the above compound as a catalyst raw material, it is also possible to use a compound containing two or more of palladium element, platinum element and tellurium element. Specifically, for example, palladium-tellurium complex PdX _n (TeRR ′) _4-n (wherein Pd represents palladium, X represents fluorine, chlorine, bromine or iodine, Te represents tellurium, R, R 'Each independently represents a linear or branched alkyl group having 1 to 8 carbon atoms, and n represents an integer of 0 to 3). It is also possible to use a compound containing both an oxidized palladium element and an oxidized platinum element.

  The above Pd raw material and Pt raw material are appropriately selected and used as a raw material for producing a catalyst. The compounding amount of these compounds is appropriately selected so that Pt / Pd and the loading ratio are the target values. When producing a catalyst containing tellurium element, the above Te raw material is appropriately selected and used as a raw material for producing the catalyst. The blending amount of the Te raw material is appropriately selected so that Te / Pd and the loading rate become the target values.

  Further, in the case of producing a catalyst containing other metal elements in addition to palladium element, platinum element and tellurium element, a compound containing other metal elements (hereinafter also referred to as “other raw materials”) is used in combination as a raw material. That's fine. Examples of the other raw materials include metals, metal oxides, metal salts, metal oxyacids, and metal oxyacid salts containing other metal elements. Since reduction of other raw materials is not always essential, the metal element contained in the other raw materials may be in an oxidized state, a reduced state, or a metal state.

  The Pd reduction process and the Pt reduction process may be performed simultaneously or separately. The order of the Pd reduction process and the Pt reduction process in the case of performing separately is arbitrary. When performing the Te addition step, the Te addition step can be performed simultaneously with the Pd reduction step and / or the Pt reduction step, or in any order. In the case of producing a catalyst containing a metal element other than palladium element, platinum element and tellurium element, the process of adding other raw materials and the process of reducing other raw materials in an oxidized state with a reducing agent are the Pd reduction process and / or the Pt reduction process. It can be performed simultaneously with the step and / or the Te addition step or in any order.

In the case of producing a supported catalyst, it is preferable to perform the reduction step in the presence of a carrier. As a reduction method when producing a supported catalyst, for example,
(1) A method in which a metal element in an oxidized state such as a salt or an oxide is supported on a support and then brought into contact with a reducing agent to reduce the metal,
(2) A method in which a reducing agent is brought into contact with a carrier in contact with a solution or slurry of an oxidized metal element such as a salt or an oxide to reduce the metal in the solution or slurry and simultaneously carry it,
(3) After carrying out the method of (2), there may be mentioned a method of further adding a metal raw material. Of these, the reduction method (1) is preferred because a catalyst having a high degree of metal dispersion is easily obtained.

  As the reduction method of (1), a Pd raw material, Pt raw material, Te raw material, and other raw materials (hereinafter collectively referred to as “metal raw materials”) in a solvent are used as a carrier. After impregnation, a method is preferred in which part or all of the metal raw material is converted into a metal oxide by heat treatment, and then the metal oxide is reduced by contacting the metal oxide supported on the carrier with a reducing agent. In this method, it is preferable to evaporate the solvent before the heat treatment to carry the metal raw material on the carrier.

  In the method of producing a catalyst by impregnating a carrier with a solution, the solvent is evaporated after the carrier is immersed in the metal raw material solution, or the metal raw material solution corresponding to the pore volume of the carrier is absorbed by the carrier. A so-called pore filling method in which the solvent is evaporated thereafter is preferable. The solvent of the solution is not particularly limited as long as it dissolves the metal raw material. Examples of the metal raw material solvent include water; organic carboxylic acids such as acetic acid and valeric acid; inorganic acids such as nitric acid and hydrochloric acid; and alcohols such as ethanol, 1-propanol, 2-propanol, n-butanol, and t-butanol. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; solvents such as hydrocarbons such as heptane, hexane, and cyclohexane can be used singly or in combination. From the viewpoint of the solubility of the metal raw material and the reducing agent or the dispersibility of the carrier, water and organic carboxylic acids are preferred.

  The operation of impregnating the solution can be performed only once using a solution containing all the metal raw materials, but can also be performed a plurality of times using a plurality of solutions. When performing several times, you may perform impregnation operation after the 2nd time after either the last heat processing or a reduction process. The order in which the metal elements are supported is not particularly limited.

  It is preferable that the temperature of the heat treatment be equal to or higher than a decomposition temperature at which the metal raw material is changed to an oxide. The temperature of the heat treatment may be a time during which at least a part of the metal raw material changes to a metal oxide, and is preferably 1 to 12 hours.

  As the reduction method of (2), for example, the metal raw material is reduced by contacting a reducing agent in a state where the support is impregnated with a solution or slurry in which one or more metal raw materials are dissolved or dispersed in a solvent. And a method of reducing a metal raw material by bringing a reducing agent into contact with the carrier in a state of dissolution or slurry as described above.

  The operation of bringing the reducing agent into contact can be performed only once using a solution containing all metal raw materials, but can also be performed a plurality of times using a plurality of solutions. In the case of performing a plurality of times, the carrier subjected to the previous reduction treatment is used in the second and subsequent reduction treatments. The order in which the metal elements are supported is not particularly limited.

  As the reduction method of (3), for example, a solution or slurry obtained by reducing a metal raw material with a reducing agent in the presence of a carrier, or a solution obtained by dissolving or dispersing another metal raw material in a solvent such as water, or A method of adding a slurry is preferred. The solvent of the solution or slurry to be added is preferably water, but various organic solvents as described above may be used. After adding another metal raw material, you may reduce by adding a reducing agent again.

  When the reduction treatment is performed a plurality of times, the type of the reducing agent, the reduction temperature and time, the type of the solvent used in the liquid phase, and the like can be appropriately set independently for each time.

  The reducing agent used for the reduction is not particularly limited. For example, ethylene glycol, propylene glycol, hydrazine, formaldehyde, sodium borohydride, hydrogen, formic acid, formic acid salt, ethylene, propylene, 1-butene, 2-butene, Examples include isobutylene, 1,3-butadiene, 1-heptene, 1-hexene, 2-hexene, cyclohexene, allyl alcohol, methacryl alcohol, acrolein, and methacrolein. Of these, ethylene glycol, propylene glycol, hydrazine, formaldehyde, hydrogen, formic acid, and formic acid salts are preferred. Two or more of these may be used in combination.

  The solvent used for reduction in the liquid phase is preferably water, but depending on the dispersibility of the carrier, alcohols such as ethanol, 1-propanol, 2-propanol, n-butanol, and t-butanol; acetone, Ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; organic acids such as acetic acid, n-valeric acid and isovaleric acid; and organic solvents such as hydrocarbons such as heptane, hexane and cyclohexane may be used alone or in combination. it can. A mixed solvent of these and water can also be used.

  When the reducing agent is a gas, it is desirable to carry out in a pressure device such as an autoclave in order to increase the solubility in the solution. In that case, it is preferable to pressurize the inside of a pressurization apparatus with a reducing agent. The pressure is preferably 0.1 to 1 MPa (gauge pressure; hereinafter, pressure is expressed as gauge pressure).

  In addition, when the reducing agent is a liquid, there is no limitation on the apparatus for performing the reduction, and the reduction can be performed by adding the reducing agent to the solution. Although the usage-amount of a reducing agent at this time is not specifically limited, It is preferable to set it as 1 mol-100 mol with respect to 1 mol of palladium elements.

  Although the reduction temperature and the reduction time vary depending on the metal raw material to be reduced, the metal oxide, the reducing agent, or the like, the reduction temperature is preferably −5 to 150 ° C., more preferably 15 to 80 ° C. The reduction time is preferably 0.1 to 4 hours, more preferably 0.25 to 3 hours, and further preferably 0.5 to 2 hours.

  When producing a supported catalyst using a metal raw material that does not require reduction, the metal raw material may be supported on the carrier after the reduction.

  The obtained catalyst is preferably washed with water, an organic solvent or the like. By washing with water, an organic solvent or the like, impurities derived from metal raw materials such as chloride, acetate radical, nitrate radical, and sulfate radical are removed. The cleaning method and the number of times are not particularly limited. However, depending on the impurities, there is a possibility that the liquid phase oxidation reaction may be inhibited. The washed catalyst may be recovered by filtration or centrifugation and used for the reaction as it is. Further, when the reduction of the palladium compound and the reduction of the platinum compound are performed in separate steps, it is also preferable to perform washing between the steps.

  Further, the recovered catalyst may be dried. Although a drying method is not specifically limited, It is preferable to dry in air or an inert gas using a dryer. The dried catalyst can also be activated before use in the reaction if desired. The activation method is not particularly limited, and examples thereof include a heat treatment method in a reducing atmosphere in a hydrogen stream. According to this method, an oxide film on the surface of palladium element or platinum element and impurities that could not be removed by washing can be removed.

  Next, a method for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin or α, β-unsaturated aldehyde with molecular oxygen using the palladium-containing catalyst of the present invention will be described.

  Only one of the raw material olefin and α, β-unsaturated aldehyde for liquid phase oxidation may be used, or a mixture of both may be used.

  Examples of the raw material olefin include propylene, isobutylene, and 2-butene. Among these, propylene and isobutylene are preferable. Two or more olefins can be used in combination. The raw material olefin may contain a small amount of saturated hydrocarbon and / or lower saturated aldehyde as impurities.

  An α, β-unsaturated carboxylic acid produced from an olefin is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the olefin. For example, acrylic acid is obtained when the raw material is propylene, and methacrylic acid is obtained when the raw material is isobutylene. Usually, α, β-unsaturated aldehyde is simultaneously obtained from olefin. This α, β-unsaturated aldehyde is an α, β-unsaturated aldehyde having the same carbon skeleton as the olefin. For example, acrolein is obtained when the raw material is propylene, and methacrolein is obtained when the raw material is isobutylene.

  Examples of the raw α, β-unsaturated aldehyde include acrolein, methacrolein, crotonaldehyde (β-methylacrolein), and cinnamaldehyde (β-phenylacrolein). Of these, acrolein and methacrolein are preferable. Two or more α, β-unsaturated aldehydes can be used in combination. The raw α, β-unsaturated aldehyde may contain a small amount of saturated hydrocarbon and / or lower saturated aldehyde as impurities.

  The α, β-unsaturated carboxylic acid produced from the α, β-unsaturated aldehyde is an α, β-unsaturated carboxylic acid in which the aldehyde group of the α, β-unsaturated aldehyde is changed to a carboxyl group. Specifically, acrylic acid is obtained when the raw material is acrolein, and methacrylic acid is obtained when the raw material is methacrolein.

  The liquid phase oxidation may be carried out in either a continuous type or a batch type, but in view of productivity, the continuous type is preferred industrially.

  The raw material of molecular oxygen used for liquid phase oxidation is preferably air because it is economical, but pure oxygen or a mixed gas of pure oxygen and air can also be used. If necessary, air or pure oxygen can be converted to nitrogen, A mixed gas diluted with carbon dioxide, water vapor or the like can also be used. It is preferable to supply molecular oxygen in a pressurized state in a reaction vessel such as an autoclave.

  Examples of the solvent used in the liquid phase oxidation reaction include t-butanol, cyclohexanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, iso-valeric acid, It is preferable to use at least one organic solvent selected from the group consisting of ethyl acetate and methyl propionate. Among these, at least one organic solvent selected from the group consisting of t-butanol, methyl isobutyl ketone, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid and iso-valeric acid is more preferable. Further, in order to produce an α, β-unsaturated carboxylic acid with higher selectivity, it is preferable to coexist water in these organic solvents. The amount of water to coexist is not particularly limited, but is preferably 2% by mass or more, more preferably 5% by mass or more, preferably 70% by mass or less, more preferably 50% by mass with respect to the total mass of the organic solvent and water. % Or less. The mixture of the organic solvent and water is desirably in a uniform state, but may be in a non-uniform state.

  The total concentration of the olefin and α, β-unsaturated aldehyde which are the raw materials for liquid phase oxidation is preferably 0.1% by mass or more, more preferably 0.5% by mass or more with respect to the solvent present in the reactor. Moreover, 30 mass% or less is preferable, and 20 mass% or less is more preferable.

  The amount of molecular oxygen used is preferably 0.1 mol or more, more preferably 0.2 mol or more, and particularly preferably 0.3 mol or more with respect to 1 mol of the raw material olefin and α, β-unsaturated aldehyde. . Moreover, 20 mol or less is preferable, 15 mol or less is more preferable, and 10 mol or less is especially preferable.

  The catalyst is preferably used in a state suspended in a reaction solution for liquid phase oxidation, but may be used in a fixed bed. The amount of the catalyst used is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more with respect to the solution present in the reactor. Moreover, 40 mass% or less is preferable, 35 mass% or less is more preferable, and 30 mass% or less is especially preferable.

  The reaction temperature and reaction pressure are appropriately selected depending on the solvent and raw materials used. The reaction temperature is preferably 30 ° C or higher, more preferably 50 ° C or higher. Moreover, 200 degrees C or less is preferable and 150 degrees C or less is more preferable. The reaction pressure is preferably atmospheric pressure (0 MPa) or more, more preferably 2 MPa or more. Moreover, 10 MPa or less is preferable and 7 MPa or less is more preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to an Example. The “parts” in the following examples and comparative examples are parts by mass.

(Analysis of raw materials and products in the production of α, β-unsaturated carboxylic acid)
Analysis of raw materials and products in the production of α, β-unsaturated carboxylic acid was performed using gas chromatography. The reaction rate of olefin or α, β-unsaturated aldehyde and the productivity of the α, β-unsaturated carboxylic acid produced are defined as follows.
Reaction rate of olefin or α, β-unsaturated aldehyde (%) = (B / A) × 100
Productivity of α, β-unsaturated carboxylic acid (g / gPd / h) = (C / D / E)
Here, A is the number of moles of olefin or α, β-unsaturated aldehyde supplied, B is the number of moles of reacted olefin or α, β-unsaturated aldehyde, and C is the amount of α, β-unsaturated carboxylic acid produced. Mass (g), D is the mass of palladium element in the catalyst (g), and E is the reaction time (h).

  In the following examples and comparative examples, a reaction for producing methacrylic acid from isobutylene is carried out. In this case, A is the number of moles of isobutylene supplied, B is the number of moles of reacted isobutylene, and C is the amount of methacrylic acid produced. It is the mass (g) of the acid.

[Example 1]
(Catalyst preparation)
To 4.0 parts of palladium nitrate nitric acid solution (manufactured by NE Chemcat, palladium element content: 25.0 mass%), tetraammine platinum nitrate solution (manufactured by NE Chemcat, platinum element content: 5.0 mass) %) 0.37 part and an aqueous solution in which 0.11 part of telluric acid was dissolved in 30 parts of pure water were added. Next, 10.0 parts of a silica carrier (specific surface area: 750 m ² / g, pore volume: 1.05 cc / g) was immersed in the above solution and evaporated. Thereafter, as a heat treatment, the temperature was raised from room temperature to 200 ° C. at a rate of 1.0 ° C./min, held at 200 ° C. for 3 hours, and then lowered to room temperature.

  The catalyst precursor thus obtained was added to 50.0 parts of ethylene glycol as a reducing agent. The mixture was heated to 70 ° C., stirred and held for 2 hours, filtered and washed with 1000 parts of pure water after suction filtration. Further, it was dried at 100 ° C. for 2 hours under a nitrogen flow to obtain a silica-supported palladium-containing catalyst. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating. The catalyst has a Pt / Pd of 0.01, a Te / Pd of 0.05, a palladium element loading of 10.0% by mass, a platinum element loading of 0.19% by mass, and a tellurium element loading of 0%. It was 60 mass%.

  The masses of palladium element, platinum element and tellurium element used for calculation of Pt / Pd, Te / Pd and the loading ratio of each element are the palladium element content and blending amount of the Pd raw material used, and the Pt raw material used. The platinum element content and blending amount were calculated from the tellurium element content and blending amount of the Te raw material used. The support mass in the catalyst was quantified as follows. First, the catalyst was placed in a platinum crucible and melted by adding sodium carbonate. Distilled water was added to obtain a homogeneous solution, and the Si atoms in the sample solution were quantified by ICP.

(Reaction evaluation)
1/10 (corresponding to 0.1 part of palladium element) of the catalyst obtained by the above method was filtered and washed with a 75 mass% t-butanol aqueous solution. As a catalyst and a reaction solvent, 75 parts by mass of 75% by mass t-butanol aqueous solution was put in an autoclave, and the autoclave was sealed. Next, 2.0 parts of isobutylene was introduced, stirring (rotation speed: 1000 rpm) was started, and the temperature was raised to 110 ° C. After completion of the temperature increase, nitrogen was introduced into the autoclave to an internal pressure of 2.4 MPa, and then compressed air was introduced to an internal pressure of 4.8 MPa to initiate the reaction. When the internal pressure decreased by 0.1 MPa during the reaction (internal pressure 4.7 MPa), the operation of introducing 0.1 MPa of oxygen was repeated. The pressure immediately after introduction is 4.8 MPa. The reaction was completed 30 minutes after the start of the reaction.

  After completion of the reaction, the inside of the autoclave was ice-cooled in an ice bath. A gas collection bag was attached to the gas outlet of the autoclave, and the pressure in the reactor was released while collecting the gas that was opened by opening the gas outlet. The reaction solution containing the catalyst was taken out from the autoclave, the catalyst was separated with a membrane filter, and the reaction solution was recovered. The collected reaction liquid and the collected gas were analyzed by gas chromatography, and the reaction rate of isobutylene and the productivity of methacrylic acid were calculated.

[Example 2]
The same procedure as in Example 1 was performed except that the amount of tetraammineplatinum nitrate solution was changed to 1.8 parts.

[Example 3]
The same procedure as in Example 1 was performed except that the amount of the tetraammineplatinum nitrate solution was changed to 3.7 parts.

[Example 4]
The same procedure as in Example 1 was performed, except that the amount of tetraammineplatinum nitrate solution was changed to 1.8 parts and no telluric acid was used.

[Example 5]
The amount of the tetraammineplatinum nitrate solution was changed to 3.7 parts, and the same procedure as in Example 1 was performed except that telluric acid was not used.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that the tetraammineplatinum nitrate solution and telluric acid were not used.

[Comparative Example 2]
The amount of the tetraammineplatinum nitrate solution was changed to 7.3 parts, and the same procedure as in Example 1 was performed except that telluric acid was not used.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that the amount of the tetraammineplatinum nitrate solution was changed to 7.3 parts.

  As the above results are summarized in Table 1, it was found that according to the method of the present invention, α, β-unsaturated carboxylic acid can be produced with higher productivity.

Claims (5)

  A palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, wherein 0.001 to 0.15 mol of platinum element is added to 1.0 mol of palladium element. Contains palladium-containing catalyst.   Furthermore, the palladium containing catalyst of Claim 1 which contains 0.001-0.40 mol of tellurium elements with respect to 1.0 mol of palladium elements.   The palladium-containing catalyst according to claim 1 or 2, wherein the catalytically active component is supported on a carrier.   A method for producing a palladium-containing catalyst according to any one of claims 1 to 3, comprising a step of reducing a compound containing palladium element in an oxidized state with a reducing agent, and a compound containing platinum element in an oxidized state. A method for producing a palladium-containing catalyst comprising a step of reducing with a reducing agent.   A method for producing an α, β-unsaturated carboxylic acid, which comprises subjecting an olefin or α, β-unsaturated aldehyde to liquid phase oxidation with molecular oxygen using the palladium-containing catalyst according to claim 1.