JP5280239B2 - Palladium-containing catalyst, method for producing the same, and method for producing α, β-unsaturated carboxylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for manufacturing an &alpha;,&beta;-unsaturated carboxylic acid with high productivity from an alcohol, olefin or &alpha;,&beta;-unsaturated aldehyde, to provide a manufacturing method of the same and to provide a manufacturing method of an &alpha;,&beta;-unsaturated carboxylic acid. <P>SOLUTION: The manufacturing method of the &alpha;,&beta;-unsaturated carboxylic acid manufactures the &alpha;,&beta;-unsaturated carboxylic acid by conducting the liquid-phase oxidation of the alcohol, olefin or &alpha;,&beta;-unsaturated aldehyde with molecular oxygen using the catalyst containing palladium and 0.001-0.04 mols aluminum per 1.0 mol of the palladium as catalyst consisting elements. The catalyst can be suitably manufactured by the step of reducing a compound containing palladium in the oxidation state with a reducing agent and the step of reducing a compound containing aluminum in the oxidation state with the reducing agent. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an alcohol, an olefin or an α, β-unsaturated aldehyde, a method for producing the same, and 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, a method for producing an olefin or α, β-unsaturated aldehyde by liquid phase oxidation with molecular oxygen has been studied. A palladium catalyst is known as a catalyst for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen, and as a catalyst containing a metal element other than palladium, in Patent Document 1, A palladium-containing catalyst containing an intermetallic compound of palladium and lead, bismuth, thallium or mercury has been proposed. Further, as a catalyst for producing α, β-unsaturated aldehyde and α, β-unsaturated carboxylic acid from olefin, or α, β-unsaturated carboxylic acid from α, β-unsaturated aldehyde, patent literature 2 proposes a palladium-containing catalyst containing 0.001 to 0.40 mol of tellurium metal with respect to 1.0 mol of palladium metal.

JP 56-59722 A International Publication No. 2005/118134 Pamphlet

  In general, as a matter to be considered in the development of a catalyst, the productivity of a target compound when used in a catalytic reaction can be mentioned, but the catalyst is not necessarily selected only by the productivity. Other considerations include the price of raw materials for catalyst constituent elements, supply stability, and handleability.

  As a catalyst for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen, a catalyst that has been developed in consideration of such matters is conventionally known palladium. The catalyst is a palladium-containing catalyst having the composition described in Patent Documents 1 and 2 above. However, industrially, it is desired to further increase the productivity of the catalyst thus developed.

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

The present invention relates to a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an alcohol, an olefin or an α, β-unsaturated aldehyde, comprising palladium as a catalyst constituent element and 1.0 mol of the palladium. Is a palladium-containing catalyst containing 0.001 to 0.04 mol of aluminum and tellurium .

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

  Furthermore, the present invention is a method for producing an α, β-unsaturated carboxylic acid in which an alcohol, 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 for producing an α, β-unsaturated carboxylic acid with high productivity from an alcohol, olefin or α, β-unsaturated aldehyde, a method for producing the catalyst, and α, β- A method for producing an unsaturated carboxylic acid can be provided.

<Palladium-containing catalyst>
The palladium-containing catalyst of the present invention (hereinafter also referred to as “catalyst” for short) is obtained by liquid-phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen to produce α, β-unsaturated carboxylic acid. A catalyst for production (hereinafter also referred to as “liquid phase oxidation” for short), which contains palladium and aluminum as catalyst constituent elements. When the catalyst contains aluminum, it becomes a catalyst capable of producing α, β-unsaturated carboxylic acid from alcohol, olefin or α, β-unsaturated aldehyde with high productivity.

  The number of moles of aluminum per mole of palladium in the catalyst, that is, the molar ratio of aluminum to palladium (sometimes abbreviated as Al / Pd) is 0.001 to 0.04, preferably 0.005 to 0.03. 0.01 to 0.02 is more preferable.

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

  In particular, the catalyst of the present invention preferably contains tellurium as a catalyst constituent element. The number of moles of tellurium relative to 1 mole of palladium in the catalyst, that is, the mole ratio of tellurium to palladium (sometimes abbreviated as Te / Pd) is preferably 0.001 to 0.4, more preferably 0.005 to 0.35. Preferably, 0.01 to 0.3 is more preferable.

  Al / Pd and Te / Pd can be adjusted by the compounding ratio of the compound containing palladium, the compound containing aluminum and the compound containing tellurium used for the production of the palladium-containing catalyst. In the present specification, a compound containing palladium used for producing a palladium-containing catalyst is also referred to as “Pd raw material”, a compound containing aluminum as “Al raw material”, and a compound containing tellurium as “Te raw material”.

  Al / Pd and Te / Pd can be calculated from the mass and atomic weight of aluminum and palladium contained in the catalyst and the mass and atomic weight of tellurium and palladium contained in the catalyst, respectively. The masses of palladium, aluminum and tellurium contained in the catalyst can be determined by elemental analysis. In addition, when the catalyst is produced by a method in which palladium, aluminum and tellurium contained in the catalyst are substantially all contained in the Pd raw material, Al raw material and Te raw material as in the pore filling method, the palladium of the Pd raw material to be used is used. The mass of each element may be calculated from the content and blending amount, the aluminum content and blending amount of the Al raw material used, and the tellurium content and blending amount of the Te raw material used.

As a method for quantifying the masses of palladium and aluminum in the catalyst by elemental analysis, the following A treatment liquid and B treatment liquid are prepared and analyzed. Tellurium can be measured in the same way.
Preparation of treatment solution A: 0.2 g of catalyst and a predetermined amount of concentrated nitric acid, concentrated sulfuric acid, and hydrogen peroxide solution were placed in a Teflon (registered trademark) decomposition tube, and a microwave thermal decomposition apparatus (manufactured by CEM, MARS5 ( The product was dissolved in the 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 liquid: The filter paper in which the insoluble parts in the A treatment were collected was 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 masses of aluminum and palladium contained in the obtained A treatment liquid and B treatment liquid were quantified with an ICP emission analyzer (manufactured by Thermo Elemental, IRIS-Advantage (trade name)). From the total mass, the mass of each element in the catalyst can be determined.

  The catalyst of the present invention may be a non-supported type, but a supported type in which at least one catalyst constituent element is supported on a carrier is preferable. Examples of the carrier include activated carbon, carbon black, silica, magnesia, calcia, titania and zirconia. Among these, silica, magnesia, calcia, titania and zirconia are preferable, and silica, titania and zirconia are more preferable. The carrier may be one type or two or more types.

The preferred specific surface area of the carrier varies depending on the type of the carrier and the like, and thus cannot be generally stated. In the case of silica, 50 to 1500 m ² / g is preferred, and 100 to 1000 m ² / g is more preferred. The smaller the specific surface area of the carrier, the more the catalyst with the useful components (palladium and aluminum) supported on the surface can be produced, and the larger the specific surface area, the more the useful components supported. The pore volume of the carrier is not particularly limited, but is preferably 0.1 to 2.0 cc / g, and more preferably 0.2 to 1.5 cc / g.

  The preferred shape and size of the support vary depending on the shape and size of the reaction apparatus used for the production of the catalyst, and are not particularly limited. Examples thereof include various shapes such as powder, granules, spheres, and pellets. Among these, granular and spherical shapes that are easy to operate such as filtration are preferable. When the carrier is powdery or granular, the particle size is preferably 0.5 to 200 μm, more preferably 1.0 to 100 μm. 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 palladium loading ratio relative to the carrier is preferably 0.1 to 40 mass%, more preferably 0.5 to 30 mass%, and 1.0 to 20 mass% with respect to the mass of the carrier before loading. Is 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-described method and the like 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.

<Method for producing palladium-containing catalyst>
The catalyst of the present invention includes a step of reducing a compound containing palladium in an oxidized state with a reducing agent (hereinafter also referred to as “Pd reduction step”), and a step of reducing a compound containing aluminum in an oxidized state with a reducing agent (hereinafter referred to as “Pd reduction step”). , And also referred to as “Al reduction step”).

  Examples of the compound containing palladium in an oxidized state include palladium salts, palladium oxide, palladium oxide alloys, and the like. Of these, palladium salts are preferred. Examples of the palladium salt include palladium chloride, palladium acetate, palladium nitrate, palladium sulfate, tetraammine palladium chloride and bis (acetylacetonato) palladium. Of these, palladium chloride, palladium acetate, palladium nitrate, and tetraammine palladium chloride are preferable. The compound containing palladium in an oxidized state may be used alone or in combination of two or more.

  Examples of the compound containing aluminum in an oxidized state include an aluminum salt, aluminum oxide, an aluminum oxide alloy, and the like. Of these, aluminum salts are preferred. Examples of the aluminum salt include aluminum nitrate, aluminum acetate, and aluminum sulfate. The compound containing aluminum in an oxidized state may be used alone or in combination of two or more.

  A compound containing palladium in the oxidized state and a compound containing aluminum in the oxidized state are appropriately selected and used as a raw material for producing the catalyst. The compounding amount of these compounds is appropriately selected so that the loading ratio of Al / Pd or palladium becomes a target value.

  In the case of producing a catalyst containing tellurium, it is a method having a Pd reduction step, an Al reduction step, and a step of reducing a compound containing tellurium in an oxidized state with a reducing agent (hereinafter also referred to as “Te reduction step”). It can manufacture suitably. However, in the case of producing a catalyst containing tellurium, the Te reduction step is not necessarily essential, and a step of mixing a compound containing tellurium or tellurium metal in an oxidized state may be performed instead of the Te reduction step.

  Examples of the compound containing tellurium in the oxidized state include tellurium salt, telluric acid and its salt, telluric acid and its salt, tellurium oxide and the like. Of these, telluric acid and its salt, telluric acid and its salt, and tellurium oxide are preferred. Examples of the tellurium salt 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. A compound containing tellurium in an oxidized state may be used alone or in combination of two or more.

  When producing a catalyst containing tellurium, a compound containing tellurium in the oxidized state as described above or a tellurium metal is appropriately selected and used as a raw material for producing the catalyst. The compounding amounts of these compounds are appropriately selected so that Te / Pd has a target value.

  In the case of producing a catalyst containing a metal element other than palladium, aluminum and tellurium, a compound containing another metal element (hereinafter also referred to as “other raw material”) is used in combination as a raw material for producing the catalyst. Good. Examples of the other raw materials include metals, metal oxides, metal salts, metal oxyacids, and metal oxyacid salts containing other metal elements. The oxidation number of other raw materials is arbitrary.

  When producing a catalyst containing a metal element other than palladium, aluminum, and tellurium, if a step of reducing other raw materials with a reducing agent is necessary, the reduction step includes a Pd reduction step, an Al reduction step, and a Te reduction step. It can be done simultaneously or in any order.

  The reducing agent used in the reduction is not particularly limited. For example, hydrazine, formaldehyde, sodium borohydride, hydrogen, formic acid, formic acid salt, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1,3- Examples include butadiene, 1-heptene, 1-hexene, 2-hexene, cyclohexene, allyl alcohol, methacryl alcohol, acrolein, and methacrolein. Of these, 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 in the production of the supported catalyst, ethanol, 1-propanol, 2-propanol, n-butanol, t- Alcohols such as butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; organic acids such as acetic acid, n-valeric acid and isovaleric acid; organic solvents such as hydrocarbons such as heptane, hexane and cyclohexane It can be used alone or in combination. A mixed solvent of these and water can also be used.

  When the reducing agent is a gas, the reduction is preferably performed 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 1-100 mol with respect to 1 mol of raw materials to reduce | restore.

  Although the reduction temperature and reduction time vary depending on the raw material to be reduced, the reducing agent, etc., 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 the reduction treatment is performed a plurality of times, the type of reducing agent, the reduction temperature and time, the type of solvent used in the liquid phase, and the like can be appropriately set independently at each time.

  As a method for producing a supported catalyst, for example, (1) a method in which a raw material containing a metal element in an oxidized state is supported on a carrier and then brought into contact with a reducing agent to reduce the metal element, (2) an oxidized state A method of reducing and supporting the metal element in the solution or slurry by bringing a reducing agent into contact with the raw material solution or slurry containing the metal element in contact with the carrier, and carrying out the method of (3) and (2) Then, a method of further adding other raw materials can be mentioned. Among these, the reduction method (1) is preferable because a catalyst having a high degree of dispersion of the metal element is easily obtained.

  As the reduction method (1), a carrier is impregnated with a solution obtained by dissolving one or more of Pd raw material, Al raw material, Te raw material and other raw materials (hereinafter also referred to as “metal raw material”) in a solvent. After that, a method in which the oxide is reduced by carrying out heat treatment to be carried on the carrier as a metal oxide and then contacting a reducing agent is preferable.

  As a method for impregnating the carrier with the solution, a so-called pore filling method in which the carrier is absorbed by the carrier is preferable. The solvent of the solution is not particularly limited as long as it dissolves the metal raw material. Examples of the solvent for the metal raw material include water; organic carboxylic acids such as acetic acid and valeric acid; inorganic acids such as nitric acid and hydrochloric acid; 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 preferable.

  The operation of impregnating the carrier with 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 a plurality of times, the second and subsequent impregnation operations may be performed either after the previous heat treatment or after the reduction treatment. The order in which the metal elements are supported is not particularly limited.

  The temperature of the heat treatment is preferably equal to or higher than the decomposition temperature at which the metal raw material changes to an oxide, and preferably 1 to 12 hours. 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.

  Examples of the reduction method (2) include a method of reducing a metal raw material by contacting a reducing agent in a state in which a carrier is impregnated with a solution obtained by dissolving one or more metal raw materials in a solvent, and a solution. Examples thereof include a method of reducing a metal raw material by bringing a reducing agent into contact with the carrier dispersed therein.

  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 that has been subjected to the previous reduction treatment in the second and subsequent reduction treatments is used. The order in which the metal elements are supported is not particularly limited.

  Examples of the reduction method (3) include a solution or slurry obtained by reducing a part of a metal raw material with a reducing agent in the presence of a carrier, and a solution obtained by dissolving or dispersing the remaining metal raw material in a solvent such as water. Or the method of adding a slurry is preferable. As a solvent of the solution or slurry to be added, water is generally used, 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.

  Furthermore, 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.

  It should be noted that all steps of loading, heating, and reduction treatment of each metal raw material can be performed simultaneously or in any order. However, in the case of a Pd raw material, it is preferable to perform a reduction process after the heating process.

  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, 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, it is possible to remove the oxide film on the surface of the catalyst constituent element and impurities that could not be removed by washing. The physical properties of the prepared catalyst can be confirmed by BET surface area measurement, XRD measurement, CO pulse adsorption method, TEM measurement, and the like. The physical properties of the prepared catalyst can be confirmed by BET surface area measurement, XRD measurement, CO pulse adsorption method, TEM measurement, and the like.

<Method for Producing α, β-Unsaturated Carboxylic Acid>
In the present invention, an α, β-unsaturated carboxylic acid is produced by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen using the above palladium-containing catalyst.

  Examples of the raw material alcohol include 2-propanol, t-butyl alcohol, and 2-butanol. Among these, 2-propanol and t-butyl alcohol are preferable. Two or more alcohols as raw materials can be used in combination. The starting alcohol may contain a small amount of water, saturated hydrocarbons and / or lower saturated aldehydes as impurities. When alcohol is used as a raw material, α, β-unsaturated carboxylic acid is obtained via a dehydration reaction. Therefore, the α, β-unsaturated carboxylic acid produced is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the olefin produced by the dehydration reaction of alcohol. For example, when the raw material is 2-propanol, propylene is used, so that an α, β-unsaturated carboxylic acid having the same skeleton as propylene is obtained. When the raw material is t-butyl alcohol, it passes through isobutylene, so that an α, β-unsaturated carboxylic acid having the same skeleton as isobutylene is obtained.

  Examples of the raw material olefin include propylene, isobutylene, and 2-butene. Among these, propylene and isobutylene are preferable. Two or more raw 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 can be obtained simultaneously 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 as raw materials 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. For example, acrylic acid is obtained when the raw material is acrolein, and methacrylic acid is obtained when the raw material is methacrolein.

  The combination of raw materials is preferably a combination of olefin and alcohol. When using alcohol as a raw material, it is preferable to use alcohol as a raw material and solvent.

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

  As the molecular oxygen source used in the liquid phase oxidation reaction, air is economical and preferable, but pure oxygen or a mixed gas of pure oxygen and air can also be used. If necessary, air or pure oxygen is converted into nitrogen, dioxide. A mixed gas diluted with carbon, 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 coexisting water 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 raw materials (alcohol, olefin and α, β-unsaturated aldehyde) present in the reaction system of liquid phase oxidation is preferably 0.1 to 50% by mass with respect to the solvent present in the reactor. More preferably, it is 5-30 mass%. However, this is not the case when the raw material is also used as a solvent, and the total concentration of the raw material may be a concentration exceeding 50% by mass.

  Further, an acidic substance may coexist in the reaction system. Examples of the acidic substance include inorganic acids, heteropoly acids and salts thereof, and solid acids. Two or more acidic substances can be used in combination.

  The amount of molecular oxygen used is preferably 0.1 to 20 mol, preferably 0.2 to 15 mol, based on 1 mol of the total of raw materials (alcohol, olefin and α, β-unsaturated aldehyde) present in the reaction system. Is more preferable, and 0.3 to 10 mol is particularly preferable. However, this is not the case when the raw material is also used as a solvent for the liquid phase oxidation reaction, and the amount of molecular oxygen used may be less than 0.1 mol with respect to 1 mol of the total of the raw materials.

  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. 0.1-40 mass% is preferable with respect to the solution which exists in a reactor, and the usage-amount of a catalyst has more preferable 0.5-35 mass%, and its 1-30 mass% 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 to 300 ° C, more preferably 50 to 200 ° C. The reaction pressure is preferably atmospheric pressure (0 MPa) to 10 MPa, more preferably 2 to 7 MPa.

  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.

  The masses of palladium, aluminum and tellurium used for calculating the loading ratio of Al / Pd, Te / Pd and palladium are the palladium content and blending amount of the Pd raw material used, the aluminum content and blending amount of the Al raw material used, and the usage It was calculated from the tellurium content of the tellurium compound and the blending amount. Further, the ratio of the mass of palladium to the mass of the carrier was defined as “palladium loading”.

  The carrier mass was quantified as follows. First, the catalyst was placed in a platinum crucible and melted by adding sodium carbonate. Then, distilled water was added to obtain a homogeneous solution, and the Si atoms in the sample solution were quantified by ICP.

(Analysis of products in the production of α, β-unsaturated carboxylic acid)
Analysis of the product in the production of α, β-unsaturated carboxylic acid was performed using gas chromatography. Note that the productivity of the α, β-unsaturated carboxylic acid to be produced is defined as follows.
Productivity of α, β-unsaturated carboxylic acid (g / (gPd × h)) = A / (B × C)
Here, A is the mass of the generated α, β-unsaturated carboxylic acid (unit: g), B is the mass of palladium metal contained in the catalyst (unit: g), and C is the reaction time (unit: time). .

[Example 1]
(Catalyst preparation)
5 parts of nitric acid was dissolved in 0.009 part of basic aluminum acetate (Al ₂ O (CH ₃ COO) ₄ .nH ₂ O <Al ₂ O (CH ₃ COO) ₄ = 81.0 wt%>). After 20 parts of a granular silica carrier (specific surface area 450 m ² / g, pore volume 0.68 cc / g, median diameter 53.58 μm) are completely immersed in 35 parts of this solution and pure water, an immersion solvent is obtained by evaporation. Was removed. The catalyst precursor (A) in which the support impregnated with the solution by such a dipping support method is calcined in the air at 400 ° C. for 3 hours (temperature increase rate = 1 ° C./min) to support the Al raw material on the silica support. Got.

  Meanwhile, 4.3 parts of palladium nitrate solution (palladium 23.33 wt%) was added to an aqueous solution in which 0.11 part of telluric acid was dissolved in pure water to prepare a total solution of 40 parts. The catalyst precursor (A) obtained by the above method was added to this solution and completely immersed, and then the immersion solvent was removed by evaporation. The carrier impregnated with the solution by such a dipping and supporting method was calcined in air at 200 ° C. for 3 hours (temperature increase rate = 1 ° C./min), and the Pd raw material, Te raw material and Al raw material were supported on the silica carrier. A catalyst precursor (B) was obtained.

  The obtained catalyst precursor (B) was added to 40.0 parts of a 37 mass% formaldehyde aqueous solution, heated to 70 ° C., and subjected to reduction treatment with stirring and holding for 2 hours. After suction filtration, it was filtered and washed with 1000 parts of warm water to obtain a catalyst in which palladium, tellurium and aluminum were supported on a silica carrier. The catalyst had an Al / Pd of 0.005, a Te / Pd of 0.05, and a palladium loading of 5.0% by mass.

(Reaction evaluation)
Of the catalyst obtained by the above method, 2.1 parts (0.1 parts as palladium) were charged into an autoclave (model: TPR-1 manufactured by Toyo Koatsu Co., Ltd.) having an internal volume of 200 ml, and 75% by mass as a reaction solvent. The autoclave was sealed by adding 75 parts of a t-butanol aqueous solution and 200 ppm of p-methoxyphenol as a radical trapping agent to the reaction solution. After the inside of the autoclave was replaced with nitrogen gas, 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. When the internal pressure decreased by 0.1 MPa (down to 4.7 MPa) during the reaction, the operation of introducing 0.12 MPa of oxygen was repeated. The reaction time was 30 minutes. Here, t-butanol does not substantially react under these reaction conditions, and functions only as a reaction solvent.

  After completion of the reaction, the inside of the autoclave was cooled in an ice water 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 recovered reaction solution and the collected gas were analyzed by gas chromatography. The results are shown in Table 1.

[Example 2]
A catalyst was prepared in the same manner as in Example 1 except that the amount of basic aluminum acetate used was 0.018 part, to obtain a catalyst in which palladium, tellurium and aluminum were supported on a silica carrier. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 1.

[Example 3]
A catalyst was prepared in the same manner as in Example 1 except that the amount of basic aluminum acetate used was 0.036 parts, to obtain a catalyst in which palladium, tellurium and aluminum were supported on a silica carrier. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 1.

[Example 4]
A catalyst was prepared in the same manner as in Example 1 except that the amount of basic aluminum acetate used was 0.054 parts, to obtain a catalyst in which palladium, tellurium and aluminum were supported on a silica carrier. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 1.

[Comparative Example 1]
(Catalyst preparation)
To an aqueous solution in which 0.11 part of telluric acid was dissolved in pure water, 4.3 parts of palladium nitrate solution (palladium 23.33 wt%) was added to prepare a total solution of 40 parts. After 20 parts of a granular silica carrier (specific surface area 450 m ² / g, pore volume 0.68 cc / g, median diameter 53.58 μm) was completely immersed in this solution, the immersion solvent was removed by evaporation. A catalyst precursor in which a support impregnated with a solution by such a dipping support method is calcined in air at 200 ° C. for 3 hours (temperature increase rate = 1 ° C./min), and a Pd raw material and a Te raw material are supported on a silica support. (E) was obtained.

  The obtained catalyst precursor (E) was subjected to reduction treatment and filtration washing in the same manner as in Example 1 to obtain a catalyst having palladium and tellurium supported on a silica carrier. The catalyst had a Te / Pd of 0.05 and a palladium loading of 5.0% by mass.

(Reaction evaluation)
Reaction evaluation was performed by the same operation as Example 1 using the catalyst obtained by said method. The results are shown in Table 1.

[Comparative Example 2]
A catalyst was prepared in the same manner as in Example 1 except that the amount of basic aluminum acetate used was 0.090 parts, to obtain a catalyst in which palladium, tellurium and aluminum were supported on a silica carrier. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 1.

[ Reference Example 1 ]
The catalyst was prepared in the same manner as in Example 1 except that the amount of basic aluminum acetate used was 0.009 parts and no telluric acid was used, and palladium and aluminum were supported on the silica support. A catalyst was obtained. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 2.

[ Reference Example 2 ]
The catalyst was prepared in the same manner as in Example 1 except that the amount of basic aluminum acetate used was 0.018 parts and no telluric acid was used, and palladium and aluminum were supported on a silica carrier. A catalyst was obtained. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 2.

[Comparative Example 3]
A catalyst was prepared in the same manner as in Comparative Example 1 except that telluric acid was not used, to obtain a catalyst in which palladium was supported on a silica carrier. And reaction evaluation was performed by operation similar to Example 1 using this catalyst. The results are shown in Table 2.

As described above, from the results of Examples 1 to 4 and Comparative Examples 1 and 2, a conventional catalyst containing palladium and tellurium contains 0.001 to 0.04 mole of aluminum with respect to 1.0 mole of palladium. It has been found that the acid productivity is improved. In addition, from the results of Reference Examples 1 and 2 and Comparative Example 3, it was found that the productivity of methacrylic acid was improved by containing aluminum in the same manner for conventional catalysts containing only palladium.

Claims (4)

A palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid from an alcohol, an olefin or an α, β-unsaturated aldehyde, comprising palladium as a catalyst constituent element and 0 with respect to 1.0 mol of the palladium A palladium-containing catalyst containing 0.001 to 0.04 moles of aluminum and tellurium . At least one catalyst constituent element, according to claim 1 Symbol placement of palladium-containing catalyst is supported on a carrier. A method for producing a palladium-containing catalyst according to claim 1 or 2 , comprising a step of reducing a compound containing palladium in an oxidized state with a reducing agent, and a step of reducing a compound containing aluminum in an oxidized state with a reducing agent. The manufacturing method of the palladium containing catalyst which has. Using palladium-containing catalyst according to claim 1 or 2, wherein the alcohol, olefin or alpha, alpha liquid-phase oxidation of β- unsaturated aldehyde with molecular oxygen, the production method of β- unsaturated carboxylic acid.