JP5006175B2 - Palladium-containing supported catalyst, method for producing the same, and method for producing α, β-unsaturated carboxylic acid - Google Patents

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, a method for liquid phase oxidation of an olefin or an α, β-unsaturated aldehyde with molecular oxygen has been studied. For example, Patent Document 1 proposes a method using a catalyst containing palladium and tellurium. As an olefin oxidation method, Patent Document 2 proposes a method in which palladium is used as a catalyst and an aqueous solution of a molybdenum compound coexists.
International Publication No. 05/118134 Pamphlet JP 56-59722 A

  However, in the liquid phase oxidation using the palladium-containing catalyst of Patent Documents 1 and 2, 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 capable of producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde with high productivity, a method for producing the catalyst, and an α, β-unsaturated using the catalyst. It is providing the manufacturing method of saturated carboxylic acid.

The present invention relates to a palladium-containing supported catalyst in which a catalytically active component for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde is supported on a carrier, the element containing palladium element 1.0 A palladium-containing supported catalyst containing 0.01 to 0.30 mol of potassium element or cesium element with respect to mol , and 0.001 to 0.40 mol of tellurium element .

The present invention is also a method for producing a palladium-containing supported catalyst, the step of reducing a compound containing palladium element in an oxidized state with a reducing agent, the step of mixing a compound containing potassium element or cesium element , and tellurium element, which is a method for producing a palladium-containing supported catalyst comprising the steps of: mixing a compound containing.

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 supported catalyst.

According to the present invention, a palladium-containing supported catalyst capable of producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde with high productivity, its production method, and α, β- using the catalyst 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), which is also referred to as an alkali metal element or alkaline earth metal element (hereinafter referred to as “A (E) M element”) per 1 mol of palladium element. .) It contains 0.01 to 0.30 mol. The catalyst preferably further contains 0.001 to 0.4 mol of tellurium element with respect to 1 mol of palladium element.

  The alkali metal element means a lithium element, a sodium element, a potassium element, a rubidium element, a cesium element, or a francium element. Among these, sodium element, potassium element, and cesium element are preferable. The alkaline earth metal element means a beryllium element, a magnesium element, a calcium element, a strontium element, a barium element, or a radium element. Of these, magnesium element and calcium element are preferable.

  The catalyst may contain only an alkali metal element, may contain only an alkaline earth metal element, or may contain both an alkali metal element and an alkaline earth metal element. The alkali metal element contained in the catalyst may be one type or two or more types. The alkaline earth metal element contained in the catalyst may be one type or two or more types.

  The number of moles of A (E) M element relative to 1 mole of palladium element in the catalyst (that is, the molar ratio of A (E) M element to palladium element: A (E) M / Pd) is set within such a predetermined range. Thus, a catalyst capable of producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde with high productivity can be obtained. When the catalyst contains both an alkali metal element and an alkaline earth metal element, the total number of moles may be within this predetermined range. A (E) M / Pd is preferably 0.03 to 0.25, and more preferably 0.05 to 0.2.

  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 A (E) M / Pd and Te / Pd are palladium compounds (hereinafter also referred to as “Pd raw materials”), alkali metal compounds or alkaline earth metal compounds (hereinafter referred to as “A”) used in the production of the palladium-containing catalyst. (E) also referred to as “M raw material”), and a mixing ratio of tellurium compounds (hereinafter also referred to as “Te raw material”).

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

  Further, 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, A (E) M element and tellurium element) is supported on a carrier. preferable. Examples of the carrier include activated carbon, carbon black, silica, alumina, titania and zirconia. Of these, silica, alumina, 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, the more the useful components (at least one of palladium element, A (E) M element and tellurium element) can be produced on the surface, and the larger the specific surface area, the more useful components are supported. The production of a catalyst is possible.

  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 A (E) M element with respect to the support is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass with respect to the mass of the carrier before support. Preferably, 1.0 to 20% by mass is more preferable.

  The catalyst of the present invention may contain other metal elements other than palladium element, A (E) M element, and tellurium element. Examples of other metal elements include platinum, 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, A (E) M element, and tellurium element is preferably 60% by mass or more, and 80% by mass or more, among the metal elements contained in the catalyst. It is more preferable.

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

  The catalyst of the present invention can be suitably produced by a method comprising a step of reducing a compound containing palladium element in an oxidized state with a reducing agent and a step of mixing a compound containing an alkali metal element or an alkaline earth metal element. In the case of producing a catalyst containing tellurium element, it can be suitably produced by a method including a step of mixing a compound containing tellurium element.

  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 compound containing an alkali metal element or an alkaline earth metal element include the following compounds. Examples of the compound containing sodium element include sodium hydroxide, sodium chloride, sodium bicarbonate, sodium carbonate and the like. Examples of the compound containing potassium element include potassium hydroxide, potassium chloride, potassium nitrate, and potassium carbonate. Examples of the compound containing a cesium element include cesium hydroxide, cesium chloride, cesium nitrate, cesium sulfate, cesium carbonate, cesium hydrogen carbonate, and the like. Examples of the compound containing magnesium element include magnesium hydroxide, magnesium oxide, magnesium carbonate, magnesium chloride, magnesium acetate and the like. Examples of the compound containing calcium element include calcium hydroxide, calcium oxide, calcium carbonate, calcium chloride, and calcium acetate. Since the reduction of the A (E) M raw material is not necessarily essential, the A (E) M element contained in the A (E) M raw material may be in an oxidized state, a reduced state, or a metal state.

  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.

  The above Pd raw material and A (E) M raw material are appropriately selected and used as a raw material for producing a catalyst. The compounding amounts of these compounds are appropriately selected so that A (E) M / Pd and the loading ratio are the intended 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, A (E) M element and tellurium element, a compound containing other metal elements as a raw material (hereinafter also referred to as “other raw material”). ). 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.

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 of reducing palladium element in an oxidized state by contacting at least a Pd raw material on a carrier and then contacting a reducing agent;
(2) A method in which a reducing agent is brought into contact with a solution or slurry containing a Pd raw material in contact with a support to reduce and simultaneously support oxidized palladium element in the solution or slurry;
(3) After carrying out the method of (2), there may be mentioned a method of adding the remaining raw materials.
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 and, if desired, one or more of A (E) M raw material, Te raw material and other raw materials (hereinafter collectively referred to as “metal raw materials”) are used as a solvent. After impregnating the support with a solution or slurry dissolved or dispersed in the carrier, heat treatment is performed to change part or all of the Pd raw material to palladium oxide, and then the palladium oxide supported on the support is brought into contact with a reducing agent to form palladium oxide. A method of reducing 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 support with a solution or slurry, a method of evaporating a solvent after immersing the support in a solution or slurry of a metal raw material, or a solution or slurry of a metal raw material corresponding to the pore volume of the support A so-called pore filling method is preferred, in which the solvent is evaporated after absorption. The solvent of the solution or slurry is not particularly limited as long as it dissolves or disperses 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.

  The operation of impregnating the solution or slurry can be performed only once using a solution or slurry containing all the metal raw materials, but can also be performed a plurality of times using a plurality of solutions or slurries. 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 the decomposition temperature at which the Pd raw material changes to palladium oxide. The heat treatment time may be a time during which at least a part of the Pd raw material changes to palladium oxide, and is preferably 1 to 12 hours.

  As the reduction method (2), for example, in a state where a support is impregnated with a solution or slurry obtained by dissolving or dispersing a Pd raw material and, optionally, one or more metal raw materials other than the Pd raw material in a solvent. Examples thereof include a method of reducing a Pd raw material by contacting a reducing agent, and a method of reducing a Pd raw material by contacting a reducing agent in a state where the carrier is dispersed in the above-described dissolution or slurry.

  The operation of bringing the reducing agent into contact can be performed only once using a solution or slurry containing all the metal raw materials, but can also be performed a plurality of times using a plurality of solutions or slurries. 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.

  Examples of the reduction method (3) include, for example, a solution or slurry obtained by reducing a Pd 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. 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 the remaining metal raw material is added, the reducing agent may be added again for reduction.

  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).

  Moreover, when a reducing agent is a liquid, there is no restriction | limiting in the apparatus which performs reduction, It can carry out by adding a reducing agent in a 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.

  The reduction temperature and 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, the mixing of the A (E) M raw material, and the mixing of the tellurium 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 A (E) M 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.

  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 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 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)
An aqueous solution in which 0.11 part of telluric acid is dissolved in 10 parts of pure water in 4.0 parts of palladium nitrate solution (manufactured by NE Chemcat, palladium element content: 25.0% by mass), and potassium hydroxide An aqueous solution in which 053 parts were dissolved in 20 parts of pure water was added. Next, 5.0 parts of a silica support (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. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating. As for the molar ratio of each element in this catalyst raw material, K / Pd is 0.1 and Te / Pd is 0.05. Further, the total loading ratio of Pd and K in this catalyst is 20.7 mass% with respect to the mass of the silica carrier before loading.

(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% by mass aqueous t-butanol 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 potassium hydroxide used was changed to 0.11 part. The total supported rate of Pd and K in the obtained catalyst is 21.5% by mass with respect to the mass of the silica support before being supported.

[Example 3]
This was carried out in the same manner as in Example 1 except that 0.18 part of cesium hydrogen carbonate was used instead of 0.053 part of potassium hydroxide. The total supported rate of Pd and Cs in the obtained catalyst is 22.5% by mass with respect to the mass of the silica support before being supported.

[Example 4]
This was carried out in the same manner as in Example 1 except that 0.36 part of cesium hydrogen carbonate was used instead of 0.053 part of potassium hydroxide. The total supported rate of Pd and Cs in the obtained catalyst is 25.0% by mass with respect to the mass of the silica support before being supported.

[Example 5]
This was carried out in the same manner as in Example 1 except that 0.55 part of cesium hydrogen carbonate was used instead of 0.053 part of potassium hydroxide. The total supported rate of Pd and Cs in the obtained catalyst is 27.5% by mass with respect to the mass of the silica support before being supported.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that potassium hydroxide was not used. In addition, the loading rate of Pd in the obtained catalyst is 20.0 mass% with respect to the mass of the silica carrier before loading.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that the amount of potassium hydroxide used was changed to 0.21 part. The total supported rate of Pd and K in the obtained catalyst is 22.9% by mass relative to the mass of the silica support before being supported.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that 0.72 part of cesium hydrogen carbonate was used instead of potassium hydroxide. The total supported rate of Pd and Cs in the obtained catalyst is 30.0% by mass with respect to the mass of the silica support before being supported.

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

Claims (3)

A palladium-containing supported catalyst in which a catalytically active component for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde is supported on a carrier, with respect to 1.0 mol of palladium element A palladium-containing supported catalyst containing 0.01 to 0.30 mol of potassium element or cesium element and 0.001 to 0.40 mol of tellurium element . A method for producing a palladium-containing supported catalyst according to claim 1, comprising a step of reducing a compound containing palladium element in an oxidized state with a reducing agent, a step of mixing a compound containing potassium element or cesium element , and tellurium method for producing a palladium-containing supported catalyst and a step of mixing a compound containing the element. A method for producing an α, β-unsaturated carboxylic acid, wherein the palladium-containing supported catalyst according to claim 1 is used to liquid-phase oxidize an olefin or α, β-unsaturated aldehyde with molecular oxygen.