JP2009011896A - OXIDATION CATALYST, ITS MANUFACTURING METHOD, AND alpha,beta-UNSATURATED CARBOXYLIC ACID PRODUCTION METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for producing α,β-unsaturated carboxylic acid from an olefin or α,β-unsaturated aldehyde with high productivity, a manufacturing method of the catalyst, and a method for producing α,β-unsaturated carboxylic acid using the catalyst. <P>SOLUTION: An oxidation catalyst containing a palladium element, a tellurium element, and a cobalt element is prepared, and used for production of α,β-unsaturated carboxylic acid. The oxidation catalyst can be prepared by a method comprising a process for reducing a compound containing a palladium element in an oxidation state by a reducing agent, a process for mixing a compound containing a tellurium element in an oxidation state, and a process for mixing a compound containing a palladium element in an oxidation state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oxidation catalyst for producing an α, β-unsaturated carboxylic acid from 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 an α, β-unsaturated aldehyde by oxidation with molecular oxygen in a liquid phase has been studied. As a catalyst for producing an α, β-unsaturated carboxylic acid by oxidizing an olefin or α, β-unsaturated aldehyde with molecular oxygen in a liquid phase, for example, Patent Document 1 proposes a palladium-containing catalyst. Yes. Further, as a catalyst for producing an α, β-unsaturated carboxylic acid by oxidizing an olefin in a liquid phase with molecular oxygen, for example, in Patent Document 2, palladium, lead, bismuth, thallium, or mercury is used. Palladium-containing catalysts containing intermetallic compounds have been proposed.
JP 2004-141863 A JP 56-59722 A

  However, in the oxidation in the liquid phase using the palladium-containing catalysts of Patent Documents 1 and 2, the productivity of the target product α, β-unsaturated carboxylic acid is not always sufficient. Furthermore, in the oxidation in the liquid phase using the above catalyst, carbon dioxide was a byproduct. As the by-product carbon dioxide selectivity increases, the selectivity of α, β-unsaturated carboxylic acid decreases, and the productivity of α, β-unsaturated carboxylic acid decreases. The desired catalyst was desired.

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

  The present invention relates to an oxidation catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, the oxidation catalyst containing palladium element, tellurium element and cobalt element. is there.

  The present invention is also a method for producing the oxidation catalyst, the step of reducing the compound containing palladium element in the oxidized state with a reducing agent, the step of mixing the compound containing tellurium element in the oxidized state, and the oxidation state It is the manufacturing method of the oxidation catalyst including the process of mixing the compound containing the palladium element of.

  The present invention is also a method for producing an α, β-unsaturated carboxylic acid in which an olefin or an α, β-unsaturated aldehyde is oxidized in the liquid phase with molecular oxygen using the oxidation catalyst.

  According to the present invention, it is possible to provide an oxidation catalyst capable of producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde with high productivity. And the alpha, beta-unsaturated carboxylic acid can be manufactured by high productivity by using the oxidation catalyst. Furthermore, carbon dioxide by-products can be reduced.

  The oxidation catalyst of the present invention (hereinafter also referred to as “catalyst” for short) produces an α, β-unsaturated carboxylic acid by oxidizing an olefin or α, β-unsaturated aldehyde with molecular oxygen in the liquid phase. (Hereinafter also referred to as “liquid phase oxidation” for short), and contains a palladium element, a tellurium element, and a cobalt element. By using an oxidation catalyst having such a composition, it becomes possible to produce an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde with high productivity.

  The chemical state of the palladium element contained in the oxidation catalyst is not particularly limited, and it may be in the metal state or in the oxidized state, but it is preferable that the palladium element is in the metal state because it exhibits high catalytic activity.

  The molar ratio (Te / Pd) of tellurium element to palladium element contained in the oxidation catalyst needs to exceed 0, but is preferably 0.002 to 0.30, more preferably 0.003 to 0.25. preferable. Te / Pd can be adjusted by the blending ratio of each raw material of palladium element and tellurium element used for manufacturing the oxidation catalyst described later.

  The chemical state of the tellurium element contained in the oxidation catalyst is not particularly limited and may be a metal state or an oxidized state. However, since the electronic state of the palladium element is further changed, the tellurium element is preferably in the metal state. Moreover, since the ratio of the palladium element which the electronic state changed greatly by adjoining the tellurium element becomes high, it is more preferable that the tellurium element is alloyed or formed an intermetallic compound with the palladium element.

  The molar ratio of cobalt element to palladium element (Co / Pd) contained in the oxidation catalyst needs to exceed 0, but is preferably 0.002 to 0.30, more preferably 0.003 to 0.10. preferable. Co / Pd can be adjusted by the blending ratio of each raw material of palladium element and cobalt element used for the production of the oxidation catalyst described later.

  The chemical state of the cobalt element contained in the oxidation catalyst is not particularly limited and may be a metal state or an oxidized state. However, since the electronic state of the palladium element is further changed, the cobalt element is preferably in the metal state. Moreover, since the ratio of the palladium element which the electronic state changed greatly by adjoining a cobalt element becomes high, it is more preferable that a cobalt element is alloying or forming an intermetallic compound with a palladium element.

  The sum of Te / Pd and Co / Pd ((Te + Co) / Pd) contained in the oxidation catalyst needs to exceed 0, but the selectivity of α, β-unsaturated carboxylic acid is further increased, In order to further reduce carbon dioxide by-product, 0.004 to 0.40 is preferable, and 0.006 to 0.30 is more preferable.

  Te / Pd, Co / Pd, and (Te + Co) / Pd can be calculated from the mass and atomic weight of palladium element, tellurium element, and cobalt element contained in the prepared oxidation catalyst. The mass of palladium element, tellurium element and cobalt element in the oxidation catalyst can be measured by the following method.

  That is, an oxidation catalyst, concentrated nitric acid, concentrated sulfuric acid, hydrochloric acid, and hydrofluoric acid are placed in a Teflon (registered trademark) decomposition tube and dissolved in a microwave thermal decomposition apparatus. Mass of the palladium element, tellurium element, and cobalt element in the oxidation catalyst can be obtained by measuring the dissolved solution in a volumetric flask and quantifying with an ICP emission spectroscopic analyzer.

  The oxidation catalyst of the present invention may contain other metal elements. Examples thereof include noble metal elements such as platinum, rhodium, ruthenium, iridium, gold, silver and osmium, and base metal elements such as antimony, thallium and lead. Two or more other metal elements can be included. From the viewpoint of expressing high catalytic activity, the total amount of palladium element, tellurium element, and cobalt element among the metal elements contained in the oxidation catalyst is preferably 50% by mass or more, and preferably 80% by mass or more. More preferred.

  The oxidation catalyst of the present invention may be a non-supported type, but is preferably a supported type in which palladium element, tellurium element and cobalt element are supported on a support. Examples of the carrier include activated carbon, carbon black, silica, alumina, magnesia, calcia, titania and zirconia, among which silica, titania and zirconia are 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.

Although the specific surface area of the preferred 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 (palladium element, tellurium element and cobalt element) supported on the surface can be produced, and the larger the range, the more useful components supported. Can be manufactured.

  The pore volume of the carrier is not particularly limited, but is preferably 0.1 cc / g to 2.0 cc / g, more preferably 0.2 cc / g to 1.5 cc / g.

  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. The particle diameter (median diameter) when the carrier is powdery or granular is preferably 0.5 μm to 200 μm, more preferably 1.0 μm 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 total supported rate of palladium element, tellurium element, and cobalt element is preferably 1% by mass to 40% by mass, more preferably 2% by mass to 30% by mass with respect to the mass of the carrier before support, 4 mass%-20 mass% are especially preferable.

  The mass of the carrier used can be measured by the following method. That is, when the support is silica, the catalyst is taken up in a platinum crucible, melted by adding sodium carbonate, and distilled water is added to form a homogeneous solution, and the amount of silicon element is determined by ICP quantitative determination of Si atoms in the sample solution. Can be obtained. When the support is titania or zirconia, the catalyst is put in a Teflon (registered trademark) decomposition tube, concentrated sulfuric acid and hydrofluoric acid are added and dissolved in a microwave thermal decomposition apparatus, distilled water is added to form a uniform solution, and a sample is obtained by ICP. By quantifying Ti or Zr atoms in the solution, the mass of titanium element or zirconia element can be obtained.

  The oxidation catalyst of the present invention can be produced using, as raw materials, elemental metals of palladium element, tellurium element, and cobalt element, alloys of these elements, and compounds containing these elements. Among these, a compound containing these elements is preferable as a raw material because a highly active catalyst in which useful components are highly dispersed on a carrier can be easily prepared.

  The raw material of the palladium element is not particularly limited, and examples thereof include palladium metal, palladium salt, palladium oxide, etc. Among them, palladium salt is 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 and palladium nitrate is particularly preferred.

  The raw material of the tellurium element is not particularly limited, and examples 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.

  The raw material for the cobalt element is not particularly limited, and examples thereof include cobalt metal, cobalt salt, and cobalt oxide. Examples of the cobalt salt include cobalt acetate (II), cobalt bromide (II), basic cobalt carbonate (II), cobalt chloride (II), cobalt iodide (II), cobalt nitrate (II), cobalt sulfate ( II) and the like. Of these, cobalt oxide and cobalt nitrate are preferred.

  The raw materials of palladium element, tellurium element and cobalt element as described above are appropriately selected and used as raw materials for producing an oxidation catalyst. The mixing ratio of these raw materials is appropriately selected so that the molar ratio of palladium element, tellurium element and cobalt element in the oxidation catalyst becomes a target value.

  The method for producing an oxidation catalyst includes a step of reducing a compound containing palladium element in an oxidized state with a reducing agent, a step of mixing a compound containing tellurium element in an oxidized state, and a step of mixing a compound containing palladium element in an oxidized state. It is preferable to include. As a more preferable production method, as a raw material of palladium element, tellurium element and cobalt element, respectively, a compound having palladium element in oxidation state, a compound having tellurium element in oxidation state, and a compound having cobalt element in oxidation state are selected. And a method of reducing at least palladium element by contacting with a reducing agent. At that time, it is more preferable that tellurium element and / or cobalt element is also reduced by contact with the reducing agent.

  In the case of producing a supported oxidation catalyst, the raw material may be supported on a carrier. The amount of the carrier used is appropriately selected so that a catalyst having a desired loading rate can be obtained.

  A method for supporting the raw material on the carrier is not particularly limited, and examples thereof include a precipitation method, an ion exchange method, an impregnation method, and a deposition method. In the case of producing by the impregnation method, the raw materials of palladium element, tellurium element and cobalt element may be impregnated and supported at the same time, or after impregnating and supporting any of the raw materials, the remaining raw materials may be impregnated and supported.

  Alternatively, the palladium element, tellurium element, and cobalt element raw materials may be supported on the support and then heat-treated so that palladium oxide, tellurium oxide, and cobalt oxide are supported on the support. The range of the heat treatment temperature is preferably 200 ° C to 800 ° C, more preferably 300 ° C to 700 ° C. The heat treatment time is not particularly limited, but is preferably in the range of 1 hour to 12 hours.

  The oxidation catalyst can be produced by reducing with a reducing agent in a state where the oxidized palladium element, the oxidized tellurium element and the oxidized cobalt element are supported on the carrier.

  The reducing agent to be used 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-butadiene, 1-butadiene, Examples include heptene, 2-heptene, 1-hexene, 2-hexene, cyclohexene, allyl alcohol, methallyl alcohol, acrolein, and methacrolein. Two or more kinds can be used in combination. For reduction in the gas phase, hydrogen is preferred as the reducing agent. In the reaction in the liquid phase, hydrazine, formaldehyde, formic acid, and a salt of formic acid are preferable as the reducing agent.

  The solvent used in the reduction in the liquid phase is preferably water, but depending on the dispersibility of the carrier in the case of a supported type, ethanol, 1-propanol, 2-propanol, n-butanol, t-butanol Alcohols such as acetone; ketones such as acetone, 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 alone Or it can be used in combination. A mixed solvent of these and water can also be used.

  When the reducing agent is a gas, it is preferably carried out in a pressurizing apparatus such as an autoclave in order to increase the solubility in the solution. At that time, the inside of the pressurizer is pressurized with a reducing agent. The pressure is preferably in the range of 0.1 MPa (gauge pressure; hereinafter, pressure is expressed as gauge pressure) to 1.0 MPa.

  In addition, when the reducing agent is a liquid, there is no limitation on the apparatus for performing the reduction, and it can be performed by adding the reducing agent to the solution. The amount of the reducing agent used at this time is not particularly limited, but is preferably in the range of 1 mol to 100 mol with respect to 1 mol of palladium element in the oxidized state.

  Although the reduction temperature and reduction time vary depending on the reducing agent and the like, the reduction temperature is preferably −5 ° C. to 150 ° C., more preferably 15 ° C. to 80 ° C. or less. The reduction time is preferably 0.1 to 4 hours, more preferably 0.25 to 3 hours, and particularly preferably 0.5 to 2 hours.

  The oxidation catalyst prepared by reduction is preferably washed with water, a solvent or the like. By washing with water, a solvent or the like, impurities derived from raw materials such as chloride, acetate radical, nitrate radical and sulfate radical are removed. The washing method and number of times are not particularly limited, but depending on the impurities, the liquid phase oxidation reaction of olefins or α, β-unsaturated aldehydes may be hindered. Therefore, washing is preferably performed to such an extent that impurities can be sufficiently removed. 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. The drying method is not particularly limited, but it is usually dried in air or in an inert gas using a dryer. The dried catalyst can be activated before use in a liquid phase oxidation 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, the oxide film on the surface of the palladium metal and impurities that could not be removed by washing can be removed. The physical properties of the prepared catalyst can be confirmed by BET surface area measurement, XRD measurement, CO pulse adsorption method, TEM measurement, XPS measurement and the like.

  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 oxidation catalyst of the present invention will be described.

  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. Specifically, acrylic acid is obtained when the raw material is propylene, and methacrylic acid is obtained when the raw material is isobutylene. In addition, α, β-unsaturated aldehyde is usually obtained from olefin at the same time. 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.

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

  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.

  As the source of molecular oxygen used for liquid phase oxidation, air is economical and preferable. However, pure oxygen or a mixed gas of pure oxygen and air can also be used. If necessary, air or pure oxygen is mixed with nitrogen, dioxide. A mixed gas diluted with carbon, water vapor or the like can also be used. Such a gas containing molecular oxygen is usually preferably supplied in a pressurized state in a reaction vessel such as an autoclave.

  Examples of the solvent used for the liquid phase oxidation 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, and acetic acid. It is preferable to use at least one organic solvent selected from the group consisting of ethyl 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. Although the quantity of the water to coexist is not specifically limited, 2 mass%-70 mass% are preferable with respect to the total mass of an organic solvent and water, and 5 mass%-50 mass% are more preferable. In the case of two or more kinds of mixed solvents, the solvent 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 used as the liquid phase oxidation raw material is preferably 0.1% by mass to 30% by mass, and 0.5% by mass to 20% with respect to the solvent present in the reactor. The mass% is more preferable.

  The amount of molecular oxygen used is preferably 0.1 mol to 0 mol, and preferably 0.2 mol to 15 mol with respect to 1 mol in total of the olefin and α, β-unsaturated aldehyde used as the raw material for the liquid phase oxidation reaction. More preferred is 0.3 to 10 moles.

  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 to 30% by mass, more preferably 0.5% by mass to 20% by mass, and particularly preferably 1% by mass to 15% by mass with respect to the solution present in the reactor. 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 to 200 ° C, more preferably 50 ° C to 150 ° C. The reaction pressure is preferably atmospheric pressure (0 MPa) to 10 MPa, more preferably 0.5 MPa to 5 MPa.

  When the oxidation catalyst of the present invention is used, α, β-unsaturated carboxylic acid can be produced from olefin or α, β-unsaturated aldehyde with high productivity, and details of the mechanism by which by-product of carbon dioxide is reduced at that time Although it is unknown, it is estimated as follows. Metallic palladium alone exhibits activity as an oxidation catalyst, but by itself, the activity of the reaction in which an olefin or an α, β-unsaturated aldehyde is oxidized to form an α, β-unsaturated carboxylic acid is not sufficient, There are many by-products of carbon dioxide. When cobalt having an electronegativity different from that of palladium is present, the electronic state of palladium is changed by the action of cobalt. Furthermore, when tellurium having an electronegativity different from that of palladium or cobalt is present, the electronic state of palladium is further changed by the action of tellurium. As a result, the olefin or the α, β-unsaturated aldehyde is oxidized to increase the activity for the main reaction in which the α, β-unsaturated carboxylic acid is generated, while the side reaction in which carbon dioxide is generated is suppressed.

  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.

  Te / Pd, Co / Pd, and the masses of palladium element, tellurium element and cobalt element used to calculate the loading ratio are the palladium content and blending amount in the raw material of palladium element used, and the tellurium content in the raw material of tellurium element used. It calculated from the rate and the compounding quantity, and the cobalt content and compounding quantity in the raw material of the cobalt element to be used.

(XRD measurement)
It measured by Rigaku Corporation RU-200A (trade name). The measurement conditions were X-ray: Cu-Kα / 40 kV / 100 mA, scan speed: 4 ° / min.

(Analysis of raw materials, products and by-products in the production of α, β-unsaturated carboxylic acids)
Analysis of raw materials and products in the production of α, β-unsaturated carboxylic acid was performed using gas chromatography. The reaction rate of the olefin, the productivity of the α, β-unsaturated carboxylic acid to be produced, and the selectivity of the by-produced carbon dioxide are defined as follows.
Olefin reaction rate (%) = (B / A) × 100
Productivity of α, β-unsaturated carboxylic acid (g / g-Pd / h) = (C / F / G) × 100
Carbon dioxide selectivity (%) = (D / B / E) x 100
Here, A is the number of moles of olefin supplied, B is the number of moles of reacted olefin, C is the mass (g) of the α, β-unsaturated carboxylic acid produced, D is the number of moles of carbon dioxide produced as a by-product, E is the number of carbon atoms of the olefin used, F is the mass of palladium used in the reaction (g), and G is the reaction time (h).

[Example 1]
(Catalyst preparation)
0.0490 parts of telluric acid and 10 times its mass of distilled water were added to obtain a homogeneous solution. To this, 0.0133 parts of cobalt nitrate (II) hexahydrate and 10 times its mass of distilled water were added to obtain a homogeneous solution. 1.8201 parts of a palladium nitrate solution (manufactured by NE Chemcat: 24.8 mass% palladium nitrate-containing nitric acid aqueous solution) was added, and distilled water was further added to a total of 5.00 parts.

2.50 parts of zirconia support (specific surface area 70.94 m ² / g, pore volume 0.20 cc / g) were immersed in the above solution and evaporated. Then, it baked at 450 degreeC in the air for 3 hours. The obtained catalyst precursor was added to 20 parts of a 37 mass% formaldehyde aqueous solution. The mixture was heated to 70 ° C., kept under stirring for 2 hours, filtered and washed with 1000 parts of hot water after suction filtration to obtain a zirconia-supported oxidation catalyst. The catalyst had a Te / Pd of 0.05 and Co / Pd of 0.01. The catalyst had a palladium element loading of 15.14 mass%, a tellurium element loading of 0.91 mass%, and a cobalt element loading of 0.09 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.95 degrees, and it was confirmed that the catalyst contained palladium in a metal state.

(Reaction evaluation)
The autoclave was sealed with 0.65 part of the catalyst obtained by the above method and 75 parts of 75% by mass aqueous t-butanol solution as a reaction solvent. Next, 2.0 parts of isobutylene was introduced, stirring (rotation speed: 1000 rpm) was started, and the temperature was raised to 90 ° 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 0.10 MPa during the reaction (internal pressure 4.70 MPa), the operation of introducing 0.11 MPa of oxygen was repeated. The reaction was completed after a reaction time of 30 minutes.

  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 recovered reaction liquid and the collected gas were analyzed by gas chromatography, and the reaction rate of isobutylene, the productivity of methacrylic acid, and the selectivity of carbon dioxide were calculated. The results are shown in Table 1.

[Example 2]
(Catalyst preparation)
The amount of telluric acid was changed to 0.0484 parts, the amount of cobalt nitrate (II) hexahydrate was changed to 0.0742 parts, and the amount of palladium nitrate solution was changed to 1.8063 parts. Except for the above, an oxidation catalyst was obtained in the same manner as in Example 1. The catalyst had a Te / Pd of 0.05 and Co / Pd of 0.06. The catalyst had a palladium element loading of 14.98 mass%, a tellurium element loading of 0.90 mass%, and a cobalt element loading of 0.49 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.87 degrees, and it was confirmed that it contained palladium in a metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Example 3]
(Catalyst preparation)
The amount of telluric acid was changed to 0.0467 parts, the amount of cobalt nitrate (II) hexahydrate was changed to 0.1399 parts, and the amount of palladium nitrate solution was changed to 1.8409 parts. Except for the above, an oxidation catalyst was obtained in the same manner as in Example 1. The catalyst had a Te / Pd of 0.05 and Co / Pd of 0.11. The catalyst had a palladium element loading of 15.17 mass%, a tellurium element loading of 0.86 mass%, and a cobalt element loading of 0.92 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.80 degrees, and it was confirmed that the catalyst contained palladium in a metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Example 4]
(Catalyst preparation)
The amount of telluric acid was changed to 0.0978 parts, the amount of cobalt nitrate (II) hexahydrate was changed to 0.0138 parts, and the amount of palladium nitrate solution was changed to 1.8298 parts. Except for the above, an oxidation catalyst was obtained in the same manner as in Example 1. The catalyst had Te / Pd of 0.10 and Co / Pd of 0.01. The catalyst had a palladium element loading of 15.07 mass%, a tellurium element loading of 1.81 mass%, and a cobalt element loading of 0.09 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.65 degrees, and it was confirmed that it contained palladium in a metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Example 5]
(Catalyst preparation)
The amount of telluric acid was changed to 0.0990 parts, the amount of cobalt nitrate (II) hexahydrate was changed to 0.0737 parts, and the amount of palladium nitrate solution was changed to 1.8329 parts. Except for the above, an oxidation catalyst was obtained in the same manner as in Example 1. The catalyst had Te / Pd of 0.10 and Co / Pd of 0.06. The catalyst had a palladium element loading of 15.03 mass%, a tellurium element loading of 1.82 mass%, and a cobalt element loading of 0.48 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.48 degrees, and it was confirmed that the catalyst contained palladium in the metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Example 6]
(Catalyst preparation)
The amount of telluric acid was changed to 0.0974 parts, the amount of cobalt nitrate (II) hexahydrate was changed to 0.1484 parts, and the amount of palladium nitrate solution was changed to 1.8198 parts. Except for the above, an oxidation catalyst was obtained in the same manner as in Example 1. The catalyst had Te / Pd of 0.10 and Co / Pd of 0.12. The catalyst had a palladium element loading of 14.87 mass%, a tellurium element loading of 1.78 mass%, and a cobalt element loading of 0.96 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.40 degrees, and it was confirmed that the catalyst contained palladium in a metallic state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Comparative Example 1]
(Catalyst preparation)
Neither telluric acid nor cobalt nitrate (II) hexahydrate was used, and an oxidation catalyst was obtained in the same manner as in Example 1 except that the amount of palladium nitrate solution was changed to 1.8418 parts. . The palladium element loading of this catalyst was 15.45% by mass. In the XRD measurement of this catalyst, a peak was detected at 2θ = 40.11 degrees, and it was confirmed that it contained palladium in a metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Comparative Example 2]
(Catalyst preparation)
An oxidation catalyst was obtained in the same manner as in Example 1 except that cobalt nitrate (II) hexahydrate was not used and the amount of palladium nitrate solution used was changed to 1.8455 parts. The catalyst had a Te / Pd of 0.05. The catalyst had a palladium element loading of 15.33 mass% and a tellurium element loading of 0.91 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.50 degrees, and it was confirmed that it contained palladium in a metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Comparative Example 3]
(Catalyst preparation)
Example 1 except that the amount of telluric acid was changed to 0.0976 parts, cobalt nitrate (II) hexahydrate was not used, and the amount of palladium nitrate solution was changed to 1.8219 parts. An oxidation catalyst was obtained in the same manner. Te / Pd of this catalyst was 0.10. The catalyst had a palladium element loading of 15.03 mass% and a tellurium element loading of 1.80 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.00 degrees, and it was confirmed that the catalyst contained palladium in a metallic state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Comparative Example 4]
(Catalyst preparation)
Example 1 except that no telluric acid was used, the amount of cobalt nitrate (II) hexahydrate used was changed to 0.0722 parts, and the amount of palladium nitrate solution used was changed to 1.8044 parts. An oxidation catalyst was obtained in the same manner. Co / Pd of this catalyst was 0.05. The catalyst had a palladium element loading of 15.04 mass% and a cobalt element loading of 0.48 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.85 degrees, and it was confirmed that the catalyst contained palladium in the metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

[Comparative Example 5]
(Catalyst preparation)
Example 1 except that no telluric acid was used, the amount of cobalt nitrate (II) hexahydrate used was changed to 0.1435 parts, and the amount of palladium nitrate solution was changed to 1.8044 parts. An oxidation catalyst was obtained in the same manner. Co / Pd of this catalyst was 0.12. The catalyst had a palladium element loading of 15.04 mass% and a cobalt element loading of 0.95 mass%. In the XRD measurement of this catalyst, a peak was detected at 2θ = 39.70 degrees, and it was confirmed that it contained palladium in a metal state.

(Reaction evaluation)
The same procedure as in Example 1 was performed using the catalyst obtained above. The results are shown in Table 1.

  As described above, by using the oxidation catalyst of the present invention, an α, β-unsaturated carboxylic acid can be produced with higher productivity, and the amount of carbon dioxide by-product is small.

Claims (3)

  An oxidation catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, comprising an element of palladium, a tellurium element, and a element of cobalt.   A method for producing an oxidation 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 tellurium element in an oxidized state, and a palladium element in an oxidized state. The manufacturing method of the oxidation catalyst including the process of mixing the compound containing.   A method for producing an α, β-unsaturated carboxylic acid, comprising oxidizing an olefin or an α, β-unsaturated aldehyde with molecular oxygen in a liquid phase using the oxidation catalyst according to claim 1.