JP5609394B2 - Method for producing palladium-containing supported catalyst and method for producing α, β-unsaturated carboxylic acid - Google Patents

Description

The present invention is an olefin or alpha, alpha from β- unsaturated aldehydes, a method for manufacturing a palladium-containing supported catalysts for the production of β- unsaturated carboxylic acid. The present invention also relates to a method for producing an α, β-unsaturated carboxylic acid.

  As a method for producing a palladium-containing catalyst for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen, Patent Document 1 proposes a method of reducing a palladium salt with a reducing agent. ing. Patent Document 2 proposes a method for reducing palladium oxide present in a catalyst precursor in a state of being supported on a carrier.

  On the other hand, in Patent Document 3, since the productivity of α, β-unsaturated carboxylic acid is lowered by inorganic chlorine contained in the catalyst raw material, the mass ratio of inorganic chlorine to palladium is 0.001 to 0.005. There has been proposed a method of reducing palladium with a reducing agent in a suspension prepared from a catalyst raw material.

International Publication No. 02/083299 Pamphlet JP 2006-167709 A JP 2005-177588 A

  However, the productivity of the α, β-unsaturated carboxylic acid produced by the method described in Patent Document 1 or 2 is not yet sufficient, and a palladium-containing catalyst that can realize higher productivity is desired. If a catalyst raw material with a low content of inorganic chlorine is used as in the method described in Patent Document 3, a high productivity can be realized, but a palladium raw material and other metal raw materials with a high inorganic chlorine content that can be obtained at a relatively low cost. Etc. were not available.

Accordingly, an object of the present invention, an olefin or alpha, beta-unsaturated aldehyde alpha, a method of manufacturing a palladium-containing supported catalysts for the production of beta-unsaturated carboxylic acid with high productivity, as well as alpha, beta-unsaturated The object is to provide a method for producing a saturated carboxylic acid with high productivity.

  The present invention is a method for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, comprising a step of supporting a palladium raw material on a support, and the palladium A method for producing a palladium-containing supported catalyst, comprising: a step of heat-treating the support on which the raw material is supported at a temperature of 100 ° C. or higher; and a step of contacting the heat-treated support with a basic solution to obtain a catalyst precursor. It is.

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

  According to the present invention, a palladium-containing supported catalyst capable of producing an α, β-unsaturated carboxylic acid with high productivity can be obtained. Moreover, according to the present invention, an α, β-unsaturated carboxylic acid can be produced from an olefin or an α, β-unsaturated aldehyde with high productivity.

  A method for producing a palladium-containing supported catalyst according to the present invention is a method for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde, wherein a palladium raw material is used. A step of supporting a carrier, a step of heat-treating the carrier on which the palladium raw material is supported at a temperature of 100 ° C. or higher, a step of bringing the heat-treated carrier into contact with a basic solution to obtain a catalyst precursor; Have

  In the present invention, first, a palladium raw material is supported on a carrier. The “palladium raw material” as used herein means a component other than the carrier supported on the carrier, and includes at least a palladium salt. Hydrochloric acid or the like present in a state where the palladium salt is adsorbed in a solution or carrier. When molecular chlorine is also included and it contains a metal component other than palladium, the salt of the metal component, or the chloride ion or molecular state contained in the solution used when the salt of the metal component is supported Including chlorine.

  Examples of the palladium salt include palladium chloride (II) (thermal decomposition temperature: 650 ° C.), palladium acetate (II) (thermal decomposition temperature: 230 ° C.), palladium nitrate (II) (thermal decomposition temperature: 120 ° C.), tetraammine. Palladium nitrate (II) (thermal decomposition temperature: 220 ° C.), tetraammine palladium hydrochloride, bis (acetylacetonato) palladium (II) (thermal decomposition temperature: 210 ° C.) and the like can be mentioned. The palladium salt can be used alone or in combination of two or more.

  The thermal decomposition temperature of the palladium salt can be measured by thermogravimetry. Here, when using a thermogravimetric measuring apparatus (trade name: TGA-50, manufactured by Shimadzu Corporation), the palladium salt was heated from room temperature to 5.0 ° C./min in an air stream, and the weight was 10%. The decreased temperature is regarded as the thermal decomposition temperature of the palladium salt.

  The present invention is also applicable to the case of using a palladium raw material, a carrier, and a suspension containing inorganic chlorine of 0.01 or more by mass ratio with respect to palladium. The mass ratio of inorganic chlorine to palladium may be, for example, 0.1 or more, or 1 or more. However, in consideration of the efficiency when removing inorganic chlorine in the subsequent step, the mass ratio of inorganic chlorine to palladium is preferably 2 or less, more preferably 1.5 or less, still more preferably 0.8 or less, and 0.8. 4 or less is particularly preferable. The inorganic chlorine referred to here includes palladium chloride or tetraamminepalladium hydrochloride as a palladium salt in the form of a palladium salt, in a solution or carrier used when a palladium salt is supported on a carrier. If it contains hydrochloric acid, molecular chlorine, etc. that are adsorbed on the metal and contains a metal component other than palladium, it supports inorganic chlorine contained in the salt state of the metal component or a salt of the metal component. Also included are chloride ions, molecular chlorine and the like contained in the solution used for the treatment.

  The carrier is not particularly limited as long as it can carry a palladium raw material. In the present invention, since the support is heat-treated after the palladium raw material is supported on the support, an inorganic oxide support that does not easily cause combustion or alteration under the heat-treatment conditions is preferable. Examples of the carrier include silica, alumina, silica alumina, magnesia, calcia, titania and zirconia, among which silica, titania or zirconia is preferable. One type of carrier can be used, or two or more types can be used in combination.

Since the specific surface area of the carrier varies depending on the type of the carrier and the like, it cannot be generally stated, but in the case of silica, 50 m ² / g or more is preferable, and 100 m 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 carrier, the more the catalyst having a useful component supported on the surface can be produced, and the larger the specific surface area of the carrier, the more the useful component supported.

  As a method of supporting the palladium raw material on the carrier, a method of evaporating the solvent after immersing the carrier in a solution of palladium salt may be used, or the solvent after absorbing the solution of palladium salt corresponding to the pore volume of the carrier to the carrier. Alternatively, a so-called pore filling method may be used. The solvent for dissolving the palladium salt is not particularly limited as long as it dissolves the palladium salt.

  Next, in the present invention, the carrier carrying the palladium raw material is heat-treated at a temperature of 100 ° C. or higher. This heat treatment can prevent the palladium salt from eluting when the carrier is brought into contact with the basic solution in the next step.

  The heat treatment temperature is preferably 100 ° C. or higher, more preferably 200 ° C. or higher because the temperature at which the palladium salt is immobilized by interacting with the carrier is preferable. The heat treatment temperature is preferably selected from a temperature of 650 ° C. or lower, which is the thermal decomposition temperature of palladium chloride, more preferably selected from a temperature of 600 ° C. or lower, and further preferably selected from a temperature of 550 ° C. or lower. .

  During the heat treatment, inorganic chlorine contained in the palladium raw material, the carrier, and the suspension reacts with the palladium salt, and at least a part of the palladium raw material becomes palladium chloride, but the heat treatment is performed at a temperature lower than the thermal decomposition temperature of palladium chloride. Thus, aggregation and growth of palladium particles due to heat generation accompanying thermal decomposition of palladium chloride can be suppressed. Therefore, even when using a palladium raw material, a carrier, and a suspension containing a large amount of inorganic chlorine, it is possible to produce an α, β-unsaturated carboxylic acid with high productivity. Due to problems such as the amount of catalyst and the scale of the calcining device, it is usually unavoidable that the layer height of the carrier carrying the palladium raw material during heat treatment is unavoidable due to the pyrolysis of palladium chloride. There is a great merit that a highly active palladium-containing catalyst can be prepared while suppressing heat generation.

  The method for raising the temperature up to the predetermined heat treatment temperature is not particularly limited, but the rate of temperature rise is preferably 1 to 10 ° C./min in order to obtain a good dispersion state in the palladium-containing supported catalyst. The holding time after reaching the predetermined heat treatment temperature is not particularly limited as long as it is sufficient for the palladium salt and the carrier to interact with each other, but is preferably 1 to 12 hours, and more preferably 1 to 10 hours.

  In the present invention, the heat-treated support is then brought into contact with a basic solution to obtain a catalyst precursor. Thereby, since at least a part of the inorganic chlorine contained in the support after the heat treatment can be removed, a catalyst precursor with a small amount of inorganic chlorine, and thus a highly productive catalyst with a small amount of inorganic chlorine can be produced.

  As the basic solution, for example, a basic aqueous solution in which a basic substance is dissolved in water can be used. Specifically, a strong basic solution such as an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, or an aqueous calcium hydroxide solution can be used. Examples include aqueous solutions, weakly basic aqueous solutions such as aqueous sodium carbonate, aqueous potassium carbonate, aqueous cesium carbonate, and aqueous sodium bicarbonate. The basic solution can be used alone or in combination of two or more.

  The pH of the basic solution before being brought into contact with the heat-treated carrier is preferably in the range of 8 to 14, and more preferably in the range of 8 to 13. In particular, when contacting with a carrier that dissolves in a basic solution such as silica, the carrier may dissolve due to strong basicity, and an optimal pore structure may not be maintained.

  The amount of the basic solution to be contacted with the heat-treated carrier varies depending on the type of basic substance contained in the basic solution, but is preferably in the range of 5 to 100 in terms of mass ratio with respect to the heat-treated carrier. In addition, the amount (molar number) of the basic substance contained in the basic solution is preferably in the range of 0.5 to 10 in terms of the substance amount ratio (molar ratio) to palladium contained in the carrier.

  The method of bringing the heat-treated carrier into contact with the basic solution is not particularly limited, and examples thereof include a method of weighing the heat-treated carrier and adding the basic solution thereto. In order to promote the removal of inorganic chlorine contained in the heat-treated carrier, the temperature of the basic solution at the time of contact is preferably 40 to 100 ° C. The contact time is preferably 1 to 4 hours.

  The pH of the solution when the heat-treated carrier is brought into contact with the basic solution is preferably in the range of 3 to 12, and more preferably in the range of 3 to 10. In particular, when a carrier that dissolves in a basic solution, such as silica, is used, if the basic solution that comes into contact with the basic solution is strong, the carrier dissolves, and an optimal pore structure may not be maintained. is there.

  If the pH of the solution at the time when the heat-treated carrier is brought into contact with the basic solution is too high, it is preferable to redo the contact treatment by reducing the amount of the basic solution or increasing the amount of the carrier. . Conversely, when the pH of the solution at the time of contact is too low, it is preferable to redo the contact treatment by increasing the amount of the basic solution or reducing the amount of the carrier.

  In the obtained catalyst precursor, the mass ratio of inorganic chlorine to palladium is preferably 0.4 or less.

  According to the present invention, a palladium-containing supported catalyst capable of producing an α, β-unsaturated carboxylic acid with high productivity can be produced. This is because even when a catalyst raw material containing inorganic chlorine is used according to the present invention, a catalyst in which palladium is well dispersed on the support can be obtained. Although the effect of contacting the heat-treated carrier with the basic solution cannot be specified, at least a part of the palladium salt supported on the carrier is changed to palladium hydroxide or the like by contacting with the basic solution, and the carrier and palladium By increasing the interaction with the salt or palladium hydroxide, it is considered that the aggregation of palladium particles can be suppressed during the subsequent reduction operation.

  Inorganic chlorine contained in the catalyst precursor can be confirmed by XRD measurement and XRF measurement. Here, the amount of inorganic chlorine is measured using a fluorescent X-ray diffractometer (trade name: ZSX-100C, manufactured by Rigaku Corporation). Specifically, 0.15 parts by mass of binder and 0.01 parts by mass of copper oxide were mixed with 0.2 parts by mass of the catalyst precursor dried at 50 ° C. under reduced pressure, and the disk was formed by pressure molding at 10 t. The mass of inorganic chlorine contained in the catalyst precursor can be determined by determining the abundance ratio (mass percentage) of chlorine and copper from the peak area calculated by XRF measurement of the obtained sample. it can.

  Next, in the present invention, it is preferable to reduce the catalyst precursor. Thereby, the palladium salt existing in a state of being supported on the carrier can be reduced, and a catalyst in which metallic palladium is present is obtained. The catalyst precursor can be used as it is without reducing the catalyst precursor.

  Although it does not specifically limit as a reducing agent, For example, a salt of hydrazine, formaldehyde, sodium borohydride, hydrogen, formic acid, formic acid, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1,3-butadiene, 1 -Heptene, 2-heptene, 1-hexene, 2-hexene, cyclohexene, allyl alcohol, methallyl alcohol, acrolein, methacrolein and the like. One reducing agent can be used, or two or more reducing agents can be used in combination.

  The reduction may be performed in the gas phase or in the liquid phase. When reducing in the gas phase, it is preferable to use hydrogen as the reducing agent. Moreover, when reducing in a liquid phase, it is preferable to use hydrazine, formaldehyde, formic acid, or a salt of formic acid as a reducing agent.

  The solvent used for the 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, or a combination thereof Can do. A mixed solvent of these and water can also be used.

  When the reduction is performed in the liquid phase and the reducing agent is liquid, the apparatus for performing the reduction is not limited and can be performed by adding the reducing agent to the solvent. Although the usage-amount of a reducing agent at this time is not specifically limited, It is preferable to set it as 1-100 mol with respect to 1 mol of palladium in a catalyst precursor.

  The reduction temperature and reduction time can be appropriately set depending on the type of reducing agent and 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.

  After the reduction, the palladium-containing supported catalyst in which palladium metal is supported on the support is separated. The method for separating the catalyst is not particularly limited, and examples thereof include methods such as filtration and centrifugation. The separated palladium-containing supported catalyst is appropriately dried. The drying method is not particularly limited, and various methods can be used.

  The size of the palladium particles supported on the carrier can be confirmed by XRD measurement. The crystallite diameter of the XRD observation target can be generally estimated by the Scherrer equation.

D = (Kλ) / (βcosθ)
D is the crystallite diameter, K is a constant, λ is the measured X-ray wavelength, β is the half width of the peak, and θ is the Bragg angle of the diffraction line. Here, K = 0.9, λ = 1.54Å, and θ is the diffraction peak value (about 20 °) corresponding to the (111) plane of palladium observed by XRD measurement. I have an estimate.

  The crystallite size of the palladium particles in the palladium-containing supported catalyst is preferably 6 nm or less, and more preferably 5 nm or less, from the viewpoint of increasing the number of reaction active sites with respect to the mass of palladium. In addition, the crystallite size of the palladium particles in the palladium-containing supported catalyst is 0.5 nm or more from the viewpoint of preventing the aggregation of the palladium particles from being promoted by the reaction heat generated locally because the initial activity is too high. Preferably, 1 nm or more is more preferable.

  The palladium-containing supported catalyst of the present invention may contain a metal component other than palladium. Examples of the metal component other than palladium include ruthenium, rhodium, silver, osmium, iridium, platinum, gold, copper, antimony, tellurium, lead and bismuth. From the viewpoint of developing high catalytic activity, it is preferable that 50% by mass or more of the metal component contained in the palladium-containing supported catalyst is palladium metal.

  A palladium-containing supported catalyst containing a metal component other than palladium can be obtained by supporting a metal compound such as a corresponding metal salt or oxide on a support and performing the above reduction as necessary. The method for supporting the metal compound at that time is not particularly limited, but can be the same method as the method for supporting the palladium raw material. Further, the metal compound can be supported on a carrier before the palladium raw material is supported, can be supported on the carrier after the palladium raw material is supported, or can be supported on the carrier simultaneously with the palladium raw material. Metal compounds containing inorganic chlorine can also be used.

  The palladium loading is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1 to 20% by mass with respect to the carrier before loading.

  The physical properties of the finally obtained palladium-containing supported catalyst can be confirmed by XRD measurement, XPS measurement, XRF measurement, TEM observation 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 palladium-containing supported catalyst of the present invention will be described.

  Examples of the raw material olefin include propylene, isobutylene and 2-butene. Examples of the raw α, β-unsaturated aldehyde include acrolein, methacrolein, crotonaldehyde (β-methylacrolein) and cinnamaldehyde (β-phenylacrolein). The raw material olefin or α, β-unsaturated aldehyde may contain some saturated hydrocarbons and / or lower saturated aldehydes as impurities.

  The α, β-unsaturated carboxylic acid produced is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the olefin when the raw material is an olefin, and when the raw material is an α, β-unsaturated aldehyde, the α , Β-unsaturated aldehyde is an α, β-unsaturated carboxylic acid in which the aldehyde group is changed to a carboxyl group.

  The production method of the present invention is suitable for liquid phase oxidation for producing acrylic acid from propylene or acrolein, and methacrylic acid from isobutylene or methacrolein.

  Air is economical as the molecular oxygen source used for liquid phase oxidation, but pure oxygen or a mixed gas of pure oxygen and air can also be used. A mixed gas diluted with water vapor or the like can also be used.

  Although the solvent used for liquid phase oxidation is not specifically limited, For example, Water; Alcohols, such as tertiary butanol and cyclohexanol; Ketones, such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Acetic acid, propionic acid, n-butyric acid, iso- Organic acids such as butyric acid, n-valeric acid and iso-valeric acid; organic acid esters such as ethyl acetate and methyl propionate; hydrocarbons such as hexane, cyclohexane and toluene can be used. Among these, organic acids having 2 to 6 carbon atoms, ketones having 3 to 6 carbon atoms, or tertiary butanol are preferable. 1 type may be sufficient as a solvent and 2 or more types of mixed solvents may be sufficient as it. Moreover, when using at least 1 sort (s) chosen from the group which consists of alcohol, ketones, organic acids, and organic acid esters, it is preferable to set it as a mixed solvent with water. The amount of water at that time is not particularly limited, but is preferably 2 to 70% by mass, and more preferably 5 to 50% by mass with respect to the mass of the mixed solvent. Although the solvent is desirably uniform, it may be used in a non-uniform state.

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

  The amount of olefin or α, β-unsaturated aldehyde used as the raw material for liquid phase oxidation is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the solvent.

  The amount of molecular oxygen used is preferably from 0.1 to 30 mol, more preferably from 0.3 to 25 mol, and more preferably from 0.5 to 20 with respect to 1 mol of the raw material olefin or α, β-unsaturated aldehyde. Mole is particularly preferred.

  The catalyst is preferably used in a state of being 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 to 30 parts by weight, more preferably 0.5 to 20 parts by weight as the catalyst present in the reactor with respect to 100 parts by weight of the solution present in the reactor. ˜15 parts by mass is particularly preferred.

  The reaction temperature and reaction pressure for liquid phase oxidation are appropriately selected depending on the solvent and reaction raw materials used. The reaction temperature is preferably 30 to 200 ° C, more preferably 50 to 150 ° C. The reaction pressure is preferably atmospheric pressure (0 MPa: gauge pressure, hereinafter all pressures are expressed as gauge pressure) to 10 MPa, more preferably 2 to 7 MPa.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to an Example.

(Analysis of raw materials and products)
Analysis of raw materials and products was performed using gas chromatography. The reaction rate of olefin or α, β-unsaturated aldehyde and the productivity of α, β-unsaturated carboxylic acid 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 amount of olefin or α, β-unsaturated aldehyde supplied (number of moles), B is the amount of reacted olefin or α, β-unsaturated aldehyde (number of moles), and C is the generated α , Β-unsaturated carboxylic acid mass (g), D is the palladium metal mass (g) in the catalyst, and E is the reaction time (h).

  In the following examples and comparative examples, since the reaction for producing methacrylic acid from isobutylene is performed, A is the amount of isobutylene supplied (number of moles), and B is the amount of reacted isobutylene (number of moles). , C is the mass (g) of the produced methacrylic acid.

[Example 1]
(Catalyst preparation)
Suspend 1.67 g of palladium (II) chloride (manufactured by NE Chemcat) in 20.0 g of water, add 1.3 g of hydrochloric acid (35 mass percent) in small portions, and heat and stir at 50 ° C. Thus, palladium chloride was dissolved to obtain a solution of a palladium raw material. At this time, the calculated value of the content of inorganic chlorine contained in the palladium raw material solution was 1.12 in terms of the mass ratio of inorganic chlorine to palladium. The above solution was added to 10.0 g of a silica support (specific surface area 480 m ² / g, total pore volume 0.68 cc / g by BJH method, median diameter 56 μm). Thereafter, evaporation was performed to obtain a silica carrier on which palladium (II) chloride was supported. This was thinly and evenly spread on a stainless bat (15 cm × 20 cm), and heat treatment was performed. As the heat treatment, the temperature was raised to 300 ° C. at 1 ° C./min and held for 3 hours. Thereafter, the temperature was lowered to room temperature.

  As a basic solution, an aqueous sodium carbonate solution in which 0.10 g of sodium carbonate was dissolved in 20.0 g of pure water was prepared. The pH of this aqueous sodium carbonate solution was 11.5. The silica support after the heat treatment was weighed in 0.1 g in terms of palladium mass, an aqueous sodium carbonate solution was added thereto, and the silica support after the heat treatment was brought into contact with the aqueous sodium carbonate solution. The pH of the solution at the time of this contact was 6.9. This was heated to 70 ° C., stirred and held for 2 hours, suction filtered, and then filtered and washed with 500 g of pure water to obtain a catalyst precursor. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.32.

  20.0 g of an aqueous formaldehyde solution (37 mass percent) was added dropwise to the catalyst precursor. This was heated to 70 ° C., stirred and held for 2 hours, suction filtered, and then filtered and washed with 500 g of pure water to obtain a catalyst. The obtained catalyst was dried at 50 ° C. under reduced pressure for 2 hours and then subjected to XRD measurement. As a result, it was confirmed that metallic palladium was produced in the catalyst.

(Reaction evaluation)
The catalyst obtained by the above method (weighed 0.1 g in terms of palladium mass) and 75 g of a 75 mass% t-butanol aqueous solution as a reaction solvent were placed in an autoclave (volume 200 mL), and the autoclave was sealed. Next, 2.0 g of isobutylene was introduced, stirring (rotation speed: 1000 rpm) was started, and the temperature was raised to 110 ° C. After the temperature increase was completed, compressed air was introduced to an internal pressure of 4.8 MPa. When the internal pressure decreased by 0.1 MPa during the reaction (when the internal pressure reached 4.7 MPa), the operation of introducing 0.1 MPa of oxygen was repeated. The reaction was completed 30 minutes after the start of the reaction.

  After completion of the reaction, the inside of the autoclave was cooled with 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, and the catalyst and the reaction solution were separated with a membrane filter. The obtained 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]
A catalyst was prepared in the same manner as in Example 1 except that an aqueous cesium carbonate solution in which 0.31 g of cesium carbonate was dissolved in 20.0 g of pure water was used as the basic solution. The pH of this aqueous cesium carbonate solution was 11.5. The pH of the solution at the time when the silica support after the heat treatment was brought into contact with the aqueous cesium carbonate solution was 7.3. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.13. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Example 3]
0.2 g of the silica support after heat treatment in terms of palladium mass was weighed, and an aqueous sodium hydroxide solution in which 0.15 g of sodium hydroxide was dissolved in 20.0 g of pure water was added thereto as a basic solution. Was prepared in the same manner as in Example 1. The pH of this aqueous sodium hydroxide solution was 13.3. The pH of the solution at the time when the silica support after the heat treatment was brought into contact with the aqueous sodium hydroxide solution was 9.8. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.15. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction was evaluated in the same manner as in Example 1 except that 0.1 g of the catalyst obtained by the above method was converted to palladium mass and weighed 0.1 g.

[Example 4]
A catalyst was prepared in the same manner as in Example 2 except that the temperature of the heat treatment was 500 ° C. and the holding time was 12 hours. The pH of the solution at the time when the silica support after the heat treatment was brought into contact with the aqueous cesium carbonate solution was 9.5. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.14. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Comparative Example 1]
A catalyst was prepared in the same manner as in Example 1 except that the step of contacting the silica support after the heat treatment with an aqueous sodium carbonate solution as a basic solution was not performed. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 1.48. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Comparative Example 2]
A catalyst was prepared in the same manner as in Example 1 except that 20.0 g of pure water was used instead of the basic solution. The pH of this pure water was 7.0. The pH of the solution at the time when the silica support after the heat treatment was brought into contact with pure water was 2.3. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.43. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Comparative Example 3]
A catalyst was prepared in the same manner as in Example 1 except that the silica support on which palladium (II) chloride was supported was not heat-treated. The pH of the solution at the time when the silica support that was not heat-treated and the aqueous sodium carbonate solution was brought into contact was 3.4. When XRF measurement of the obtained catalyst precursor was performed, palladium immobilized on the catalyst precursor was reduced to 0.024 in mass ratio to palladium contained in the catalyst precursor of Example 1. . When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Comparative Example 4]
A catalyst was prepared in the same manner as in Example 4 except that the step of bringing the heat-treated silica carrier into contact with an aqueous cesium carbonate solution as a basic solution was not performed. When the XRF measurement of the silica support after the heat treatment was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.33. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Comparative Example 5]
A catalyst was prepared in the same manner as in Example 1 except that a sodium chloride aqueous solution in which 0.15 g of sodium chloride was dissolved in 20.0 g of pure water was used instead of the basic solution. The pH of this aqueous sodium chloride solution was 7.0. The pH of the solution at the time when the silica carrier after the heat treatment was brought into contact with the sodium chloride aqueous solution was 4.6. When XRF measurement of the obtained catalyst precursor was performed, palladium immobilized on the catalyst precursor was reduced to 0.050 in mass ratio with respect to palladium contained in the catalyst precursor of Example 1. . When the XRD measurement of the obtained catalyst was performed, it was confirmed that almost no metal palladium remained in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

[Comparative Example 6]
A catalyst was prepared in the same manner as in Example 1 except that a sodium nitrate aqueous solution in which 0.16 g of sodium nitrate was dissolved in 20.0 g of pure water was used instead of the basic solution. The pH of this aqueous sodium nitrate solution was 7.0. The pH of the solution at the time when the silica support after the heat treatment was brought into contact with the aqueous sodium nitrate solution was 2.2. When the XRF measurement of the obtained catalyst precursor was performed, the mass ratio of inorganic chlorine to palladium contained in the catalyst precursor was 0.49. When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating in the catalyst. The reaction evaluation was performed in the same manner as in Example 1.

  Table 1 summarizes the catalyst preparation conditions and reaction evaluation results in the above Examples and Comparative Examples. From this, it has been found that according to the present invention, α, β-unsaturated carboxylic acid can be produced with higher productivity.

Claims (3)

A process for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde comprising the steps of:
A step of supporting a palladium raw material on a carrier;
Heat treating the carrier carrying the palladium raw material at a temperature of 100 ° C. or higher;
A method for producing a palladium-containing supported catalyst, comprising a step of bringing the heat-treated carrier into contact with a basic solution to obtain a catalyst precursor.   The manufacturing method of the palladium containing supported catalyst of Claim 1 in which the said palladium raw material contains 0.01 or more inorganic chlorine by mass ratio with respect to palladium.   Production of an α, β-unsaturated carboxylic acid that oxidizes an olefin or α, β-unsaturated aldehyde with molecular oxygen in a liquid phase using the palladium-containing supported catalyst produced by the method according to claim 1 or 2. Method.