JP4911361B2 - Palladium-containing 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 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. As a catalyst for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen, for example, in Patent Document 1, an intermetallic compound of palladium and lead, bismuth, thallium or mercury is used. Containing palladium-containing catalysts have 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, for example, Patent Document 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.

A method for producing an α, β-unsaturated carboxylic acid from alcohol has also been studied. For example, Patent Document 3 proposes a technique for dehydrating and oxidizing alcohol in the liquid phase in the presence of molecular oxygen, a noble metal-containing catalyst, and an acidic substance. A method of dehydrating and oxidizing alcohol at 110 to 250 ° C. in the absence of an acidic substance has also been proposed.
JP 56-59722 A WO2005 / 118134 JP 2006-265227 A

  However, in the liquid phase oxidation using the palladium-containing catalyst produced according to the method described in the examples of Patent Documents 1 and 2, the activity of the palladium-containing catalyst may be insufficient. The productivity of α, β-unsaturated carboxylic acid as a product is not sufficient, and a catalyst for producing α, β-unsaturated carboxylic acid with higher productivity is desired. Furthermore, in the production method of Patent Document 3 using alcohol as a raw material, an acidic substance or a predetermined temperature control is essential, and the development of a catalyst that can be produced more simply has been desired as well.

  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 by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen, and palladium as a catalyst constituent element. An element , a tellurium element and a vanadium element, the number of moles of vanadium element per mole of palladium element is 0.001 to 0.55, and at least one of the catalyst constituent elements is supported on a carrier, and the reducing agent in a reduced palladium-containing catalyst.

Further, the present invention provides a method of producing the palladium-containing catalyst, the oxidation state of the compound containing palladium element in the oxidation state in the presence step is reduced with a reducing agent, and in the presence of the carrier of the carrier vanadium It is a manufacturing method of a palladium containing catalyst including the process of reduce | restoring the compound containing an element with a reducing agent .

  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.

  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 element and vanadium element. By containing palladium element and vanadium element in the catalyst, a catalyst capable of producing α, β-unsaturated carboxylic acid from alcohol, olefin or α, β-unsaturated aldehyde with high productivity can be obtained. The number of moles of vanadium element relative to 1 mole of palladium element in the catalyst, that is, the molar ratio of vanadium element and palladium element (sometimes abbreviated as V / Pd) is preferably 0.001 to 0.55, and 0.01 to 0. .45 is more preferred.

  The catalyst of the present invention preferably further contains a tellurium element. The number of moles of tellurium element per mole of palladium element in the catalyst, that is, the molar ratio of tellurium element to palladium element (sometimes abbreviated as Te / Pd) is preferably 0.001 to 0.4, preferably 0.005 to 0. .35 is more preferable, and 0.01 to 0.3 is more preferable.

  V / Pd and Te / Pd can be adjusted by the compounding ratio of the compound containing palladium element in the oxidized state, the compound containing vanadium element in the oxidized state, and the compound containing tellurium element, which are used for the production of the palladium-containing catalyst. It is. In the present specification, a compound containing palladium element in an oxidized state used for the production of a palladium-containing catalyst is “Pd raw material”, a compound containing vanadium element in an oxidized state is “V raw material”, and a compound containing tellurium element is used. Also called “Te raw material”.

V / Pd and Te / Pd can be calculated from the mass and atomic weight of vanadium element and palladium element, and the mass and atomic weight of tellurium element and palladium element, respectively. The mass of palladium element, vanadium element and tellurium element contained in the catalyst can be determined by elemental analysis. As a method for quantifying the mass of palladium element and vanadium 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 each element contained in the obtained A treatment liquid and B treatment liquid was quantified with an ICP emission spectrometer (manufactured by Thermo Elemental Co., Ltd., IRIS-Advantage (trade name)), and the mass of each element in both treatment liquids. From the total, the mass of each element in the catalyst can be determined.

  In addition, when the catalyst is manufactured by a method in which substantially all of the palladium element, vanadium element and tellurium element contained in the Pd raw material, the V raw material and the Te raw material are contained in the catalyst, such as the pore filling method and the immersion supporting method. The mass of both elements may be calculated from the palladium content and blending amount of the Pd raw material used, the vanadium content and blending amount of the V raw material used, and the tellurium content and blending amount of the Te raw material used.

  The catalyst of the present invention may be an unsupported type, but a supported type in which at least one or all of catalyst constituent elements (palladium element, vanadium element and tellurium element) are 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 carrier varies depending on the type of the carrier and the like and cannot be generally stated. In the case of silica, it is preferably 50 m ² / g or more, more preferably 100 m ² / g or more. 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 components having useful components (palladium element, vanadium element and tellurium element) supported on the surface can be produced, and the larger the specific surface area, the more the components having useful components supported. .

  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 loading ratio of palladium element to the carrier is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, and 1.0 to 20% by mass with respect to the mass of the carrier before carrying. % Is more preferable.

  In the case of a supported catalyst, the loading ratio of each element 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, vanadium element, and tellurium element as catalyst constituent elements. Examples of other metal elements include platinum, rhodium, ruthenium, iridium, gold, silver, osmium, copper, lead, bismuth, thallium, mercury, antimony, and the like. One or more other metal elements can be contained. From the viewpoint of developing a high catalytic activity, the total of palladium element, vanadium element, and tellurium element is preferably 60% by mass or more, and 80% by mass or more among all catalyst constituent elements contained in the catalyst. Is more preferable.

  Next, 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 (Pd raw material) with a reducing agent (hereinafter also referred to as “Pd reduction step”), and a compound containing vanadium element in an oxidized state (V raw material). ) With a reducing agent (hereinafter also referred to as “V reduction step”). Further, when producing a catalyst containing tellurium element, a Pd reduction step, a V reduction step, and a step of reducing a compound containing tellurium element in an oxidized state with a reducing agent (hereinafter also referred to as “Te reduction step”). The method of including is mentioned. However, when producing a catalyst containing tellurium element, the Te reduction step is not necessarily essential. That is, instead of the Te reduction step, a method including a step of mixing a compound containing tellurium element (Te raw material) (hereinafter also referred to as “Te mixing step”) may be used.

  Examples of the Pd raw material 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.

  Examples of the V raw material include metavanadic acid and its salt, vanadium salt, vanadium oxide, vanadium oxide alloy, and the like. Among these, metavanadate and vanadium salt are preferable. Examples of metavanadate include ammonium metavanadate. Examples of vanadium salts include vanadium oxysuccinate, vanadyl oxalate, vanadium acetylacetonate, and the like. Among these, ammonium metavanadate, vanadium oxyoxalate, and vanadyl oxalate are preferable.

  Examples of the Te raw material include tellurium metal, 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. Since the Te reduction step is not always essential, the tellurium element contained in the Te raw material may be in an oxidized state or a metal state.

In addition to the above compound, a compound containing two or more elements of palladium element, vanadium element, and tellurium element can be used as a raw material for the two or more elements. Specifically, for example, palladium-tellurium complex [PdX _n (TeRR ′) _4-n ] (wherein Pd represents palladium, X represents fluorine, chlorine, bromine or iodine, and TeRR ′ represents an organic tellurium compound. Is used as a Pd raw material and a Te raw material. It is also possible to use a compound containing both an oxidized palladium element and an oxidized vanadium element as a Pd raw material and a Te raw material.

  The Pd raw material and V raw material as described above are appropriately selected and used as raw materials for producing the catalyst. The blending amounts of these raw materials are appropriately selected so that V / Pd and palladium element loadings have the desired values. In the case of 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 becomes a target value.

  In addition, in the case of producing a catalyst containing other metal elements as catalyst constituent elements in addition to palladium element, vanadium 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. The oxidation number of other raw materials is arbitrary.

  The Pd reduction process and the V reduction process may be performed simultaneously or separately. The order of the Pd reduction step and the V reduction step when they are performed separately is arbitrary. When performing the Te mixing step or the Te reduction step, the step can be performed simultaneously with the Pd reduction step and / or the V reduction step or in any order.

  Further, when a catalyst containing a metal element other than palladium element, vanadium element, and tellurium element is produced, the reduction step in the case where a step of mixing other raw materials and a step of reducing other raw materials with a reducing agent is required is Pd The reduction step and / or the V reduction step and / or the Te mixing step or the Te reduction step can be performed simultaneously or in any order.

  Examples of the reduction method for producing a supported catalyst include, 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 A method of reducing and supporting the metal element in the solution or slurry by bringing a reducing agent into contact with the support in contact with the solution or slurry of the raw material containing the metal element in the oxidized state; Examples include a method of adding another raw material after the method is carried out. Among them, the reduction method (1) in which a catalyst having a high degree of metal element dispersion is easily obtained is preferable.

  As the reduction method (1), a solution or slurry in which one or more of Pd raw material, V raw material, Te raw material and other raw materials (hereinafter also referred to as “metal raw material”) are dissolved or dispersed in a solvent is used. An example is a method in which the oxide is reduced by contacting with a reducing agent after impregnating the support. In addition, a method is preferred in which heat treatment is performed prior to the reduction, the metal oxide is supported on the carrier, and then the oxide is reduced by contacting with a reducing agent.

  As a method of impregnating the support with the solution or slurry, a so-called pore filling method in which the solution or slurry is absorbed by the support is preferable. The solvent is not particularly limited as long as it dissolves or disperses 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 or dispersibility 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 support with 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.

The temperature of the heat treatment is arbitrarily preferred that the metal material is equal to or higher than the decomposition temperatures varying in the oxide. The heat treatment time 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, a metal raw material is prepared by contacting a reducing agent in a state where a carrier is impregnated with a solution or slurry in which one or more metal raw materials are dissolved or dispersed in a solvent as described above. And a method of reducing the metal raw material by bringing a reducing agent into contact with the carrier dispersed in a solution or slurry.

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

  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.

  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, 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 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 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.

  All the steps of loading the Pd raw material, V raw material and Te raw material, heat treatment and reduction treatment can be performed simultaneously or in any order. In that case, it is preferable to perform a reduction treatment after the heat treatment of the Pd raw material.

  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. In addition, when the reduction of the palladium compound, the reduction of the vanadium compound, and the mixing or reduction 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, it is possible to remove the oxide film on the surface of palladium element, vanadium element, and tellurium 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 .

  Next, a method for producing an α, β-unsaturated carboxylic acid in which alcohol, olefin or α, β-unsaturated aldehyde is subjected to liquid phase oxidation with molecular oxygen using the catalyst of the present invention will be described.

  Examples of the raw material alcohol include 2-propanol, t-butyl alcohol, and 2-butanol. Of these, 2-propanol and t-butyl alcohol are preferred. 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. In production using alcohol as a raw material, an α, β-unsaturated carboxylic acid is obtained via a dehydration reaction. For example, acrylic acid having the same skeleton as propylene is obtained when the raw material is 2-propanol, so that acrylic acid having the same skeleton as propylene is obtained, and isobutylene is used when the raw material is t-butyl alcohol. An acid is obtained.

  Examples of the raw material olefin include propylene, isobutylene, 2-butene and the like. Of 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.

  Two or more raw materials selected from alcohols, olefins and α, β-unsaturated aldehydes can also be combined. The combination of raw materials is preferably a combination of olefin and alcohol, and when alcohol is used as the raw material, it is preferably used as the 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 olefin and α, β-unsaturated aldehyde present in the reaction system of liquid phase oxidation is preferably 0.1% by mass or more, and 0.5% by mass or more with respect to the solvent present in the reactor. More preferred. Moreover, 30 mass% or less is preferable, and 20 mass% or less is more preferable.

  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 mol or more, more preferably 0.2 mol or more, based on a total of 1 mol of olefin and α, β-unsaturated aldehyde present in the reaction system, 0.3 mol Mole or more is particularly preferable. 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.

  The masses of palladium element, vanadium element and tellurium element used for calculation of the loading ratio of V / Pd, Te / Pd and palladium element are respectively the palladium content and blending amount of the Pd raw material used, and the vanadium content of the V raw material used. It calculated from the rate and the blending amount, and the tellurium content and blending amount of the tellurium compound to be used.

  Further, the ratio of the mass of palladium element to the mass of carrier was defined as “palladium element loading ratio”. 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. The productivity of the α, β-unsaturated carboxylic acid 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 produced α, β-unsaturated carboxylic acid (unit: g), B is the mass of palladium element contained in the catalyst (unit: g), and C is the reaction time (unit: time). .

[ Reference Example 1]
(Catalyst preparation)
40 parts of pure water was added to 0.1 part of vanadium oxysuccinate (VOC ₂ O ₄ .nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) and dissolved by heating to 60 ° C. 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. The carrier impregnated with the solution by such an immersion supporting method was calcined in air at 500 ° C. for 3 hours (temperature increase rate = 1 ° C./min) to obtain a catalyst precursor (A) supporting vanadium element. .

  Further, a homogeneous solution in which 4.6 parts of palladium nitrate solution (palladium element 21.69 wt%) and 40 parts of pure water were mixed was prepared, and the catalyst precursor (A) obtained by the above method was added to this solution. After complete immersion, the immersion solvent was removed by evaporation. The carrier impregnated with the 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 catalyst precursor (B) supporting palladium element and vanadium element Got.

  The obtained catalyst precursor (B) was added to 40.0 parts of a 37 mass% aqueous formaldehyde solution. A reduction treatment was performed by heating to 70 ° C. and stirring for 2 hours. Then, after suction filtration, it was filtered and washed with 1000 parts of warm water to obtain a catalyst in which palladium element and vanadium element were supported on a silica carrier. The catalyst had a V / Pd of 0.05 and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
10.5 g (0.5 g as palladium element) of the catalyst obtained by the above method was charged into an autoclave in an autoclave (model: LC-3, manufactured by Toyo Kodan Co., Ltd.) having an internal volume of 330 ml, and 86% by mass as a reaction solvent. An autoclave was sealed by adding 100 g of an aqueous t-butanol solution and 200 ppm of p-methoxyphenol as a radical trapping agent to the reaction solution. The inside of the autoclave was replaced with nitrogen gas, then 6.5 g 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 0.2 MPa during the reaction (internal pressure 4.6 MPa), the operation of introducing 0.2 MPa of oxygen was repeated. The reaction was terminated when the total amount of oxygen reached 2.0 MPa. The reaction time was 36 minutes.

  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 methacrylic acid produced at this time was 25.6 mmol (2.20 g), and the productivity of methacrylic acid was 7.3 (g / (gPd × h)). The results are shown in Table 1.

[ Reference Example 2]
(Catalyst preparation)
A catalyst was prepared in the same manner as in Reference Example 1, except that the amount of vanadium oxysuccinate (VOC ₂ O ₄ .nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) used was 0.62 parts. A catalyst in which palladium element and vanadium element were supported on a silica support was obtained. The catalyst had a V / Pd of 0.30 and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.6 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 23 minutes. The methacrylic acid produced at this time was 26.4 mmol (2.27 g), and the productivity of methacrylic acid was 11.8 (g / (gPd × h)). The results are shown in Table 1.

[ Reference Example 3]
(Catalyst preparation)
A catalyst was prepared in the same manner as in Reference Example 1, except that the amount of vanadium oxyoxalate (VOC ₂ O ₄ .nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) used was 0.82 parts. A catalyst in which palladium element and vanadium element were supported on a silica support was obtained. This catalyst had a V / Pd of 0.40 and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.6 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 23 minutes. The methacrylic acid produced at this time was 24.5 mmol (2.11 g), and the productivity of methacrylic acid was 11.0 (g / (gPd × h)). The results are shown in Table 1.

[Comparative Example 1]
(Catalyst preparation)
In the catalyst preparation of Reference Example 1, the V raw material was not used. That is, without preparing the catalyst precursor (A), a homogeneous solution was prepared by mixing 4.6 parts of a palladium nitrate nitric acid solution (21.69 wt% palladium element) and 40 parts of pure water. After 20 parts were completely immersed (specific surface area 450 m ² / g, pore volume 0.68 cc / g, median diameter 53.58 μm), the immersion solvent was removed by evaporation. The carrier impregnated with the solution by such a dipping support method was calcined in air at 200 ° C. for 3 hours (temperature increase rate = 1 ° C./min) to obtain a catalyst precursor (C) supporting palladium element. .

The obtained catalyst precursor (C) was subjected to reduction treatment and filtration washing in the same manner as in Reference Example 1 to obtain a catalyst in which palladium element was supported on a silica carrier. The palladium element loading of this catalyst was 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.5 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 33 minutes. The methacrylic acid produced at this time was 19.6 mmol (1.68 g), and the productivity of methacrylic acid was 6.1 (g / (gPd × h)). The results are shown in Table 1.

[Example 4]
(Catalyst preparation)
The same catalyst preparation as in Reference Example 1 was performed to obtain a catalyst precursor (A) on which a vanadium element was supported.

  Further, 4.6 parts of palladium nitrate solution (palladium element 21.69 wt%) was added to an aqueous solution in which 0.22 part of telluric acid was dissolved in pure water to make a uniform solution of 40 parts as a whole. 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 support method is calcined in air at 200 ° C. for 3 hours (temperature increase rate = 1 ° C./min), and a catalyst precursor supporting palladium element, vanadium element and tellurium element. (D) was obtained.

The obtained catalyst precursor (D) was subjected to reduction treatment and filtration washing in the same manner as in Reference Example 1 to obtain a catalyst in which palladium element, vanadium element and tellurium element were supported on a silica carrier. The catalyst had a Te / Pd of 0.10, a V / Pd of 0.05, and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.6 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 32 minutes. The methacrylic acid produced at this time was 33.1 mmol (2.85 g), and the productivity of methacrylic acid was 10.7 (g / (gPd × h)). The results are shown in Table 2.

[Example 5]
(Catalyst preparation)
A catalyst was prepared in the same manner as in Example 4 except that the amount of vanadium oxysuccinate (VOC ₂ O ₄ · nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) used was 0.31 part. A catalyst in which palladium element, vanadium element and tellurium element were supported on a silica carrier was obtained. The catalyst had Te / Pd of 0.10, V / Pd of 0.15, and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.6 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 28 minutes. The methacrylic acid produced at this time was 32.2 mmol (2.77 g), and the productivity of methacrylic acid was 11.9 (g / (gPd × h)). The results are shown in Table 2.

[Example 6]
(Catalyst preparation)
A catalyst was prepared in the same manner as in Example 4 except that the amount of vanadium oxysuccinate (VOC ₂ O ₄ · nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) used was 0.62 parts. A catalyst in which palladium element, vanadium element and tellurium element were supported on a silica carrier was obtained. This catalyst had Te / Pd of 0.10, V / Pd of 0.30, and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.6 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 27 minutes. The methacrylic acid produced at this time was 34.1 mmol (2.93 g), and the productivity of methacrylic acid was 13.0 (g / (gPd × h)). The results are shown in Table 2.

[Example 7]
(Catalyst preparation)
A catalyst was prepared in the same manner as in Example 4 except that the amount of vanadium oxysuccinate (VOC ₂ O ₄ .nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) used was 0.82 parts. A catalyst in which palladium element, vanadium element and tellurium element were supported on a silica carrier was obtained. The catalyst had Te / Pd of 0.10, V / Pd of 0.40, and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.7 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 24 minutes. The methacrylic acid produced at this time was 31.7 mmol (2.73 g), and the productivity of methacrylic acid was 13.7 (g / (gPd × h)). The results are shown in Table 2.

[Example 8]
(Catalyst preparation)
A catalyst was prepared in the same manner as in Example 4 except that the amount of vanadium oxysuccinate (VOC ₂ O ₄ .nH ₂ O <VOC ₂ O ₄ = 70.9 wt%>) used was 1.03 parts. A catalyst in which palladium element, vanadium element and tellurium element were supported on a silica carrier was obtained. The catalyst had Te / Pd of 0.10, V / Pd of 0.50, and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.7 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 32 minutes. The methacrylic acid produced at this time was 32.4 mmol (2.79 g), and the productivity of methacrylic acid was 10.5 (g / (gPd × h)). The results are shown in Table 2.

[Comparative Example 2]
(Catalyst preparation)
In the catalyst preparation of Example 4, the V raw material was not used. That is, 4.6 parts of palladium nitrate solution (21.69 wt% palladium nitrate) was added to an aqueous solution in which 0.22 part of telluric acid was dissolved in pure water without preparing the catalyst precursor (A), A 20 part homogeneous solution was obtained. 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. The carrier impregnated with the solution by such a dipping support method is calcined in air at 200 ° C. for 3 hours (heating rate = 1 ° C./min), and a catalyst precursor (E) on which palladium element and tellurium element are supported Got.

The obtained catalyst precursor (E) was subjected to reduction treatment and filtration washing in the same manner as in Reference Example 1 to obtain a catalyst in which palladium element and tellurium element were supported on a silica carrier. The catalyst had Te / Pd of 0.10 and a palladium element loading of 5.0% by mass.

(Reaction evaluation)
The reaction was evaluated in the same manner as in Reference Example 1 except that 10.6 g (0.5 g as palladium element) of the catalyst obtained by the above method was used. The reaction was completed when the total amount of oxygen reached 2.0 MPa. The reaction time was 30 minutes. The methacrylic acid produced at this time was 29.0 mmol (2.50 g), and the productivity of methacrylic acid was 10.0 (g / (gPd × h)). The results are shown in Table 2.

Claims (3)

Palladium-containing catalyst for producing α, β-unsaturated carboxylic acid by liquid phase oxidation of alcohol, olefin or α, β-unsaturated aldehyde with molecular oxygen, palladium element , tellurium element as catalyst constituent elements And vanadium element, the number of moles of vanadium element with respect to 1 mole of palladium element is 0.001 to 0.55, and at least one of the catalyst constituent elements is supported on the carrier and reduced with a reducing agent. Palladium-containing catalyst. A method for producing a palladium-containing catalyst according to claim 1 , wherein the compound containing palladium element in the oxidized state in the presence of the carrier is reduced with a reducing agent, and the vanadium element in the oxidized state in the presence of the carrier. A method for producing a palladium-containing catalyst, comprising a step of reducing a compound containing a reducing agent with a reducing agent. Using palladium-containing catalyst according to claim 1 Symbol placement, alcohol, olefin or alpha, alpha liquid-phase oxidation of β- unsaturated aldehyde with molecular oxygen, the production method of β- unsaturated carboxylic acid.