JP2008212818A - Method of manufacturing palladium-containing supported catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a palladium-containing supported catalyst for manufacturing an α,β-unsaturated carboxylic acid from an olefin or an α,β-unsaturated aldehyde with high productivity, its manufacturing method and a method of manufacturing an α,β-unsaturated carboxylic acid with high productivity. <P>SOLUTION: The catalyst is manufactured by a method having a process of mixing a support with a solution consisting of a palladium salt dissolved in a solvent in a mass ratio of the solvent to the support of 0.3-20 to prepare a catalyst precursor, a process of heat-treating the catalyst precursor at a temperature ≥40°C and below the thermal decomposition temperature of the palladium salt so as to produce a mass ratio of the residual solvent to the support of ≤0.25 and a process of (1) heat-treating the heat-treated catalyst precursor, continuously without cooling to a temperature below 40°C, at a temperature equal to or higher than the thermal decomposition temperature of the palladium or (2) cooling the heat-treated catalyst precursor to a temperature below 40°C in a gas containing practically no moisture or the vapor of the solvent, storing and then heat-treating the catalyst precursor at a temperature equal to or higher than the thermal decomposition temperature of the palladium salt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to 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. The present invention also relates to a method for producing an α, β-unsaturated carboxylic acid.

As palladium-containing supported catalysts for producing α, β-unsaturated carboxylic acids by liquid phase oxidation of olefins or α, β-unsaturated aldehydes with molecular oxygen, for example, Patent Document 1 and Patent Document 2 include palladium. A palladium metal supported catalyst obtained by reducing a salt with a reducing agent has been proposed. Patent Document 3 proposes a palladium-containing supported catalyst having a step of reducing palladium oxide contained in a catalyst precursor while being supported on a support.
International Publication No. 02/083299 Pamphlet Japanese Patent Laid-Open No. 2000-202287 JP 2006-167709 A

  However, the productivity of α, β-unsaturated carboxylic acid produced by the method described in the above patent document is not yet sufficient, and a catalyst for producing α, β-unsaturated carboxylic acid with higher productivity is desired. ing.

  Accordingly, an object of the present invention is to provide a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde with high productivity, a method for producing the catalyst, and α, β- The object is to provide a method for producing an unsaturated carboxylic acid with high productivity.

The present invention is a process for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of an olefin or α, β-unsaturated aldehyde with molecular oxygen.
(A) mixing a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support to prepare a catalyst precursor;
(B) Heat-treating the catalyst precursor at a temperature of 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of mass ratio with respect to the support. When,
(C1) heat-treating the catalyst precursor heat-treated in the step (b) at a temperature equal to or higher than the thermal decomposition temperature of the palladium salt without cooling to a temperature of less than 40 ° C .;
It is a manufacturing method of the palladium containing supported catalyst characterized by having.

The present invention also provides a method for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid by liquid-phase oxidation of an olefin or α, β-unsaturated aldehyde with molecular oxygen.
(A) mixing a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support to prepare a catalyst precursor;
(B) Heat-treating the catalyst precursor at a temperature of 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of mass ratio with respect to the support. When,
(C2) The catalyst precursor heat-treated in the step (b) is cooled and stored at a temperature of less than 40 ° C. in a gas substantially free of moisture and the vapor of the solvent, and then the heat of the palladium salt. Heat treatment at a temperature equal to or higher than the decomposition temperature;
It is a manufacturing method of the palladium containing supported catalyst characterized by having.

  Moreover, this invention is a palladium containing supported catalyst obtained by the said manufacturing method.

  Furthermore, the present invention is 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.

  According to the method for producing a palladium-containing supported catalyst of the present invention, when α, β-unsaturated carboxylic acid is produced by liquid phase oxidation of olefin or α, β-unsaturated aldehyde with molecular oxygen, α, β -A palladium-containing supported catalyst capable of producing an unsaturated carboxylic acid with high productivity can be produced.

  Further, according to the palladium-containing supported catalyst of the present invention, when α, β-unsaturated carboxylic acid is produced by liquid phase oxidation of olefin or α, β-unsaturated aldehyde with molecular oxygen, α, β- Unsaturated carboxylic acids can be produced with high productivity.

  Furthermore, according to the method for producing an α, β-unsaturated carboxylic acid of the present invention, an α, β-unsaturated carboxylic acid can be produced with high productivity.

The method for producing the palladium-containing supported catalyst of the present invention comprises:
(A) mixing a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support to prepare a catalyst precursor;
(B) Heat-treating the catalyst precursor at a temperature of 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of mass ratio with respect to the support. When,
(C1) heat-treating the catalyst precursor heat-treated in the step (b) at a temperature equal to or higher than the thermal decomposition temperature of the palladium salt without cooling to a temperature of less than 40 ° C .;
It is a manufacturing method of the palladium containing supported catalyst characterized by having.

The method for producing the palladium-containing supported catalyst of the present invention includes:
(A) mixing a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support to prepare a catalyst precursor;
(B) Heat-treating the catalyst precursor at a temperature of 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of mass ratio with respect to the support. When,
(C2) The catalyst precursor heat-treated in the step (b) is cooled and stored at a temperature of less than 40 ° C. in a gas substantially free of moisture and the vapor of the solvent, and then the heat of the palladium salt. Heat treatment at a temperature equal to or higher than the decomposition temperature;
It is a manufacturing method of the palladium containing supported catalyst characterized by having.

  By using the palladium-containing catalyst obtained by this method for producing a palladium-containing supported catalyst, an α, β-unsaturated carboxylic acid was produced by liquid phase oxidation of an olefin or α, β-unsaturated aldehyde with molecular oxygen. In this case, the α, β-unsaturated carboxylic acid can be produced with high productivity.

  As a factor that can produce α, β-unsaturated carboxylic acid with high productivity, by reducing the residual solvent when the palladium salt is thermally decomposed into palladium oxide or the like by heat treatment, Compared with the method, the interaction between the support and the palladium salt becomes stronger, and the aggregation and particle growth of the generated palladium oxide and the like can be suppressed. Therefore, a catalyst precursor in which palladium oxide and the like are supported in a highly dispersed state is manufactured. In particular, it is conceivable to produce a catalyst in which palladium atoms are supported in a highly dispersed state.

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

  The palladium-containing supported catalyst of the present invention is a supported catalyst in which a catalyst constituent element containing palladium metal is supported on a carrier, and can be obtained, for example, by the following production method. However, if the obtained palladium containing supported catalyst is the same, it is not limited to what was manufactured with the following manufacturing method.

  Although the carrier is not particularly limited, in the present invention, the catalyst precursor is prepared by mixing the carrier and a palladium salt solution and then heat-treated. Therefore, an inorganic oxide that does not easily burn or deteriorate under the heat-treatment conditions. A carrier is preferred. For example, silica, alumina, silica alumina, magnesia, calcia, titania, zirconia and the like can be mentioned, among which silica, alumina, titania and zirconia are preferable. One type of carrier can be used, or two or more types can be used in combination. 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 specific surface area of the support can not be said sweepingly because different by the kind of carrier, the case of silica, preferably at least ^{50m 2 / g, 100m 2 /} g or more is more preferable. Moreover, 1500 m < ² > / g or less is preferable and 1000 m < ² > / g or less is more preferable. The smaller the specific surface area of the 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. The pore volume of the carrier is preferably 0.05 to 2.0 cc / g from the viewpoint of the strength of the carrier and the efficiency of palladium loading.

  First, a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support are mixed to prepare a catalyst precursor (step (a)). The mass of the solvent to be used is preferably 0.4 or more, more preferably 0.5 or more by mass ratio with respect to the carrier. Further, the mass of the solvent to be used is preferably 15 or less, more preferably 12 or less in terms of mass ratio with respect to the carrier.

  The solvent for dissolving the palladium salt is not particularly limited as long as it dissolves the palladium salt. For example, water; aqueous solution containing inorganic substances such as hydrochloric acid, aqueous nitric acid, aqueous sulfuric acid, aqueous sodium chloride, aqueous potassium chloride, aqueous sodium hydroxide, aqueous potassium hydroxide, aqueous ammonium chloride, aqueous ammonia; methanol, ethanol, n-propanol, Alcohols such as isopropanol; hydrocarbons such as hexane, benzene, toluene, xylene; halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; dimethylformamide, dimethyl Amides such as acetamide; and the like. One type of solvent can be used, or a mixture of two or more types can be used.

  In the present invention, it is preferable to use a palladium salt having a thermal decomposition temperature of 400 ° C. or lower as the palladium salt. The thermal decomposition temperature of the palladium salt is more preferably 300 ° C. or less, and particularly preferably 200 ° C. or less. The thermal decomposition temperature of the palladium salt is generally higher than 40 ° C. The lower the decomposition temperature of the palladium salt, the lower the calorific value. In particular, by using a palladium salt having a thermal decomposition temperature of 200 ° C. or less, even when the layer height of the catalyst precursor during heat treatment is thick, the calorific value can be reduced and the aggregation and growth of palladium particles can be suppressed. Therefore, it is possible to produce an α, β-unsaturated carboxylic acid with higher productivity. In catalyst preparation on an industrial scale, the layer height of the catalyst precursor during heat treatment is usually unavoidable due to the relationship between the amount of catalyst and the scale of the calciner, etc., so high production is possible even if the layer height is increased. The fact that it is possible to manufacture with a great advantage has a great advantage when scaling up.

  Examples of the palladium salt to be used include palladium (II) chloride (thermal decomposition temperature: 650 ° C.), palladium (II) acetate (thermal decomposition temperature: 230 ° C.), palladium (II) nitrate (thermal decomposition temperature: 120 ° C.). , Tetraamminepalladium nitrate (II) (thermal decomposition temperature: 220 ° C.), bis (acetylacetonato) palladium (II) (thermal decomposition temperature: 210 ° C.), and the like. Of these, palladium (II) acetate, palladium (II) nitrate, tetraammine palladium nitrate (II), and bis (acetylacetonato) palladium (II) are preferred. One palladium salt can be used, or two or more palladium salts can be used in combination.

  Subsequently, the catalyst precursor obtained by mixing the support and the palladium solution is used at a temperature of 40 ° C. or higher and the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of a mass ratio with respect to the support. The heat treatment is performed at a temperature lower than the thermal decomposition temperature (step (b), hereinafter, this heat treatment is referred to as “pre-stage heat treatment”). By this pre-stage heat treatment, the palladium salt is supported on the carrier. The mass of the residual solvent contained in the catalyst precursor after the pre-stage heat treatment is preferably 0.15 or less, more preferably 0.1 or less, by mass ratio with respect to the carrier used. Moreover, the mass of the residual solvent contained in the catalyst precursor after the pre-stage heat treatment is preferably as small as possible from the viewpoint of the performance of the catalyst. However, for this purpose, there are methods such as evacuation or extremely long processing time in the pre-stage heat treatment, but this is often not economical, and considering the balance with economic efficiency, The mass ratio with respect to the carrier is preferably 0.001 or more, and more preferably 0.002 or more.

  The mass of the residual solvent contained in the catalyst precursor after the preceding heat treatment is the mass of the support used from the mass of the entire catalyst precursor containing the residual solvent, the mass of the palladium salt used (however, in the palladium salt having crystal water) Is determined by reducing the mass of the compound of the metal component other than palladium used as necessary.

  Although there is no particular limitation on the method of the pre-stage heat treatment, for example, stationary heat treatment using a box furnace, reduced pressure flow heat treatment using a rotary evaporator, spray heat treatment using a spray dryer, or the like can be used.

  The temperature of the pre-stage heat treatment is not particularly limited as long as it is 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt used, and is appropriately selected according to the boiling point of the solvent and the thermal decomposition temperature of the palladium salt. The temperature of the pre-stage heat treatment is preferably 45 ° C. or higher, and more preferably 50 ° C. or higher. The temperature of the pre-stage heat treatment is preferably less than the thermal decomposition temperature of the palladium salt −5 ° C., more preferably less than the thermal decomposition temperature of the palladium salt −10 ° C. When the boiling point of the solvent is high and / or the thermal decomposition temperature of the palladium salt is low, heat treatment in a reduced pressure state using a rotary evaporator or the like is preferable.

  The method for raising the temperature up to the predetermined pre-heating 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 of palladium atoms in the palladium-containing supported catalyst. However, a method in which the catalyst precursor is charged in advance to a predetermined temperature of the pre-stage heat treatment may be used. The holding time after reaching the temperature of the predetermined pre-stage heat treatment is not particularly limited as long as a catalyst precursor in which a solvent having a mass ratio of 0.001 to 0.25 remains with respect to the support is obtained.

  As the next step of the pre-stage heat treatment, the pre-stage heat-treated catalyst precursor is heat-treated at a temperature equal to or higher than the thermal decomposition temperature of the palladium salt (hereinafter, this heat treatment is described as “post-stage heat treatment”). At this time, the catalyst precursor subjected to the pre-stage heat treatment is continuously subjected to the post-stage heat treatment without cooling to a temperature of less than 40 ° C. (step (c1)), or the catalyst precursor subjected to the pre-stage heat treatment is substantially treated. In particular, after cooling and storing at a temperature of less than 40 ° C. in a gas not containing moisture or the solvent vapor, heat treatment is performed later (step (c2)).

  By this subsequent heat treatment, at least a part of the palladium salt is decomposed to become palladium oxide. The temperature of the post-stage heat treatment is appropriately selected at a temperature equal to or higher than the thermal decomposition temperature of the palladium salt, preferably a thermal decomposition temperature of the palladium salt + 10 ° C. or higher, and more preferably a thermal decomposition temperature of the palladium salt + 20 ° C. Moreover, 800 degrees C or less is preferable and 700 degrees C or less is more preferable.

  The method for raising the temperature up to the predetermined post-heating 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 of palladium atoms in the palladium-containing supported catalyst. The holding time after reaching the temperature of the predetermined post-stage heat treatment is not particularly limited as long as the palladium salt is decomposed, but is preferably 1 to 12 hours.

  Although there is no particular limitation on the method of continuously performing the subsequent heat treatment without cooling the catalyst precursor subjected to the previous heat treatment to a temperature of less than 40 ° C., the same apparatus as the previous heat treatment is used because the process can be simplified. Thus, it is desirable to use a method of performing the latter-stage heat treatment or a method of continuously supplying from the former-stage heat treatment apparatus to the latter-stage heat treatment apparatus using a heated pipe or the like.

In addition, after the catalyst precursor subjected to the pre-stage heat treatment is cooled and stored at a temperature of less than 40 ° C. in a gas substantially free of moisture and the solvent vapor, the post-stage heat treatment may be performed, for example, There is a method in which the heat-treated catalyst precursor is cooled and stored in a container substituted with a dry gas such as dry air or dry nitrogen, and then subjected to a subsequent heat treatment. The dry gas may contain moisture or solvent vapors not exceeding 0.1 g / m ³ .

  When a cooling and storage method different from the production method of the present invention is adopted between the pre-stage heat treatment and the post-stage heat treatment, that is, the catalyst precursor subjected to the pre-stage heat treatment is treated in a gas containing moisture or vapor of the solvent. After cooling to a temperature of less than 0 ° C. and storage, and subsequent heat treatment, the catalyst precursor subjected to the previous heat treatment absorbs moisture contained in the gas or the vapor of the solvent, whereby the carrier and the palladium salt The catalyst precursor in which palladium oxide or the like is supported in a highly dispersed state cannot be produced, and the palladium atom is finally produced. It is considered that the catalyst supported in a highly dispersed state cannot be produced and the activity of the catalyst is lowered.

  By the above-mentioned pre-stage and post-stage heat treatment, a catalyst precursor in which at least a part of the palladium salt supported on the support is decomposed into palladium oxide is obtained. And in this invention, it is preferable to reduce | restore the catalyst precursor obtained by said front | former stage and back | latter stage heat processing with a reducing agent, and to use it as a palladium metal. When a palladium salt is present on the catalyst precursor support, the palladium salt is simultaneously reduced to palladium metal.

  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. 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.

  As a solvent used for the reduction in the liquid phase, water is preferable, but alcohols such as ethanol, 1-propanol, 2-propanol, n-butanol, t-butanol, etc., depending on the dispersibility of the carrier; acetone , Methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones; acetic acid, n-valeric acid, iso-valeric acid and other organic acids; heptane, hexane, cyclohexane and other hydrocarbons; Can be used. 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 a gas, it is preferably performed in a pressure apparatus such as an autoclave in order to increase the solubility in the solvent. At that time, the inside of the pressurizer is pressurized with a reducing agent. The pressure is preferably 0.1 to 1.0 MPa (gauge pressure; hereinafter, pressure is expressed as gauge pressure).

  In addition, when the reduction is performed in the liquid phase and the reducing agent is liquid, the apparatus for reducing the catalyst precursor is not limited, and the reduction 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 atoms in a catalyst precursor.

  Although the reduction temperature and reduction time vary depending on the 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. Although the method for separating the catalyst is not particularly limited, for example, methods such as filtration and centrifugation can be used. The separated palladium-containing supported catalyst is appropriately dried. The drying method is not particularly limited, and various methods can be used.

  The palladium-containing supported catalyst of the present invention can 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 reduction as necessary. The method for supporting the metal compound at that time is not particularly limited, but can be carried out in the same manner as the method for supporting the palladium salt. In addition, the metal compound can be supported before the palladium salt is supported, can be supported after the palladium salt is supported, or can be supported simultaneously with the palladium salt. Further, the metal compound may be supported before the first heat treatment of the palladium salt, between the first heat treatment and the second heat treatment, or after the second heat treatment.

  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 and the like of the finally obtained palladium-containing supported catalyst can be confirmed by XRD measurement, XPS 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, 2-butene and the like. 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. When the raw material is an α, β-unsaturated aldehyde, it is an α, β-unsaturated carboxylic acid in which the aldehyde group of the α, β-unsaturated aldehyde 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, 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; Of these, organic acids having 2 to 6 carbon atoms, ketones having 3 to 6 carbon atoms, and tertiary butanol are preferable. The solvent may be one kind or a mixed solvent of two or more kinds. 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 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. 1 to 15 parts by mass is particularly preferable.

  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) to 10 MPa, more preferably 2 to 7 MPa.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to an Example. The “parts” in the following examples and comparative examples are parts by mass.

(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 the α, β-unsaturated carboxylic acid produced are defined as follows.
Reaction rate of olefin or α, β-unsaturated aldehyde (%) = (B / A) × 100
Productivity of α, β-unsaturated carboxylic acid (g / gPd / h) = (C / D / E)
Here, A is the number of moles of olefin or α, β-unsaturated aldehyde supplied, B is the number of moles of reacted olefin or α, β-unsaturated aldehyde, and C is the amount of α, β-unsaturated carboxylic acid produced. Mass (g), D is the mass (g) of palladium metal in the catalyst, and E is the reaction time (h).

  In the following examples and comparative examples, a reaction for producing methacrylic acid from isobutylene is carried out. In this case, A is the number of moles of isobutylene supplied, B is the number of moles of reacted isobutylene, and C is the amount of methacrylic acid produced. The mass of acid (g).

[Example 1]
(Catalyst preparation)
An aqueous palladium (II) nitrate solution containing 4.33 parts of palladium (II) nitrate (aqueous solution containing 2.0 parts of palladium atoms in terms of palladium metal) was added purely to 0.46 parts of telluric acid. An aqueous solution dissolved in 16.4 parts of water was added. Next, 40.0 parts of a silica support (specific surface area: 450 m ² / g, pore volume: 0.68 cc / g) and the above solution were mixed to obtain 65.89 parts of a catalyst precursor. At this time, the mass ratio of the solvent used for dissolving the palladium salt to the carrier is 0.53.

  Thereafter, the catalyst precursor was heated in the first stage for 1 hour using a box-type electric furnace in which the temperature in the furnace was controlled at 100 ° C., and then heated from 100 ° C. to 200 ° C. at 2.0 ° C./min, After holding at 200 ° C. for 2 hours (after-stage heat treatment), the temperature was lowered to room temperature.

  The catalyst precursor thus obtained was added to 100.0 parts of a 37 mass% aqueous solution of formaldehyde as a reducing agent. The mixture was heated to 70 ° C., stirred and held for 2 hours, filtered and washed with 2000 parts of pure water after suction filtration. Furthermore, it was dried at 100 ° C. for 2 hours under a nitrogen flow to obtain a silica-supported palladium-containing catalyst (palladium metal support: 5.0% by mass). When the XRD measurement of the obtained catalyst was performed, it was confirmed that the metal palladium was producing | generating.

(Measurement of residual solvent amount)
After obtaining a catalyst precursor in the same manner as in the above catalyst preparation method, the pre-heating treatment was performed for 1 hour using a box-type electric furnace in which the temperature in the furnace was controlled at 100 ° C., and the temperature was lowered to room temperature in dry nitrogen. The mass of the catalyst precursor thus obtained was measured and found to be 44.85 parts. From the above, the mass ratio of the remaining solvent to the carrier is 0.0023.

(Reaction evaluation)
1/4 of the catalyst obtained by the above method (corresponding to 0.5 part of palladium metal) was filtered and washed with an 86 mass% aqueous t-butanol solution. As a catalyst and a reaction solvent, 100 parts of an 86 mass% t-butanol aqueous solution was put in an autoclave, and the autoclave was sealed. Next, 6.5 parts of isobutylene was introduced, stirring (rotation speed: 1000 rpm) was started, and the temperature was raised to 110 ° C. After completion of the temperature increase, nitrogen was introduced into the autoclave to an internal pressure of 2.4 MPa, and then compressed air was introduced to an internal pressure of 4.8 MPa to initiate the reaction. When the internal pressure decreased by 0.1 MPa during the reaction (internal pressure 4.7 MPa), the operation of introducing 0.1 MPa of oxygen was repeated. The pressure immediately after introduction is 4.8 MPa. The reaction was completed 30 minutes after the start of the reaction.

  After completion of the reaction, the inside of the autoclave was ice-cooled in an ice bath. A gas collection bag was attached to the gas outlet of the autoclave, and the pressure in the reactor was released while collecting the gas that was opened by opening the gas outlet. The reaction solution containing the catalyst was taken out from the autoclave, the catalyst was separated with a membrane filter, and the reaction solution was recovered. The collected reaction liquid and the collected gas were analyzed by gas chromatography, and the reaction rate and productivity were calculated.

[Example 2]
(Catalyst preparation)
The same procedure as in Example 1 was performed, except that the time for the pre-treatment of the catalyst precursor was 30 minutes.

(Measurement of residual solvent amount)
The same procedure as in Example 1 was performed, except that the time for the pre-treatment of the catalyst precursor was 30 minutes. The mass of the catalyst precursor thus obtained was measured and found to be 45.35 parts. From the above, the mass ratio of the remaining solvent to the carrier is 0.015.

(Reaction evaluation)
The same method as in Example 1 was used.

[Comparative Example 1]
(Catalyst preparation)
The same procedure as in Example 1 was performed, except that the time for the pre-treatment of the catalyst precursor was 5 minutes.

(Measurement of residual solvent amount)
The same procedure as in Example 1 was performed, except that the time for the pre-treatment of the catalyst precursor was 5 minutes. The mass of the catalyst precursor thus obtained was measured and found to be 60.35 parts. From the above, the mass ratio of the remaining solvent to the carrier is 0.39.

(Reaction evaluation)
The same method as in Example 1 was used.

[Comparative Example 2]
(Catalyst preparation)
This was carried out in the same manner as in Example 1 except that the temperature rise to 200 ° C. was started immediately after the catalyst precursor was put into a box-type electric furnace whose temperature in the furnace was controlled at 100 ° C.

(Measurement of residual solvent amount)
This was performed in the same manner as in Example 1 except that the temperature was lowered to room temperature in dry nitrogen immediately after the catalyst precursor was put into a box-type electric furnace whose temperature in the furnace was controlled at 100 ° C. The mass of the catalyst precursor thus obtained was measured and found to be 64.68 parts. From the above, the mass ratio of the remaining solvent to the carrier is 0.50.

(Reaction evaluation)
The same method as in Example 1 was used.

[Example 3]
(Catalyst preparation)
The catalyst precursor was pre-heated for 30 minutes using a box-type electric furnace in which the temperature in the furnace was controlled at 100 ° C., and then taken out from the box-type electric furnace, in dry nitrogen with a residual water content of 0.03 g / m ³ The temperature was lowered to 25 ° C. or lower and stored for 24 hours. Then, it carried out by the same method as Example 1 except having started temperature rising to 200 degreeC immediately after throwing a catalyst precursor into the box-type electric furnace which controlled the temperature in a furnace again at 100 degreeC.

(Reaction evaluation)
The same method as in Example 1 was used.

[Comparative Example 3]
(Catalyst preparation)
The temperature was lowered and stored after the catalyst precursor was heat-treated in the previous stage, and the same procedure as in Example 3 was performed, except that the catalyst precursor was performed in non-humidified air (residual water content 16 g / m ³ ).

(Reaction evaluation)
The same method as in Example 1 was used.

[Example 4]
(Catalyst preparation)
An aqueous palladium (II) nitrate solution containing 4.33 parts of palladium (II) nitrate (aqueous solution containing 2.0 parts of palladium atoms in terms of palladium metal) was added purely to 0.46 parts of telluric acid. An aqueous solution dissolved in 80.0 parts of water was added. Next, 40.0 parts of silica support (specific surface area: 450 m ² / g, pore volume: 0.68 cc / g) and the above solution were mixed to obtain 129.49 parts of a catalyst precursor. At this time, the mass ratio of the solvent used for dissolving the palladium salt to the carrier is 2.12.

Thereafter, the catalyst precursor was preheated under reduced pressure for 2 hours using a rotary evaporator whose water bath temperature was controlled at 60 ° C., then removed from the rotary evaporator, and in dry nitrogen having a residual water content of 0.03 g / m ^3. The temperature was lowered to 25 ° C. or lower and stored for 24 hours. Thereafter, immediately after the catalyst precursor was put into a box-type electric furnace in which the temperature in the furnace was controlled at 100 ° C., the temperature was raised from 100 ° C. to 200 ° C. at 2.0 ° C./min and held at 200 ° C. for 2 hours. After (second stage heat treatment), the temperature was lowered to room temperature. Thereafter, the same method as in Example 1 was performed.

(Measurement of residual solvent amount)
After obtaining a catalyst precursor in the same manner as in the above catalyst preparation method, a pre-heat treatment was performed under reduced pressure for 2 hours using a rotary evaporator in which the temperature of the water bath was controlled at 60 ° C. Thereafter, the temperature was removed from the rotary evaporator, and the temperature was lowered to 25 ° C. or less in dry nitrogen having a residual water content of 0.03 g / m ³ . The mass of the catalyst precursor thus obtained was measured and found to be 48.28 parts. From the above, the mass ratio of the remaining solvent to the carrier is 0.088.

(Reaction evaluation)
The same method as in Example 1 was used.

[Comparative Example 4]
(Catalyst preparation)
The temperature was lowered and stored after heat-treating the catalyst precursor in the same manner as in Example 4 except that it was performed in unconditioned air (residual water content 16 g / m ³ ).

(Reaction evaluation)
The same method as in Example 1 was used.

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

Claims (4)

A method for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid by liquid-phase oxidation of an olefin or α, β-unsaturated aldehyde with molecular oxygen,
(A) a step of mixing a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support to prepare a catalyst precursor;
(B) Heat-treating the catalyst precursor at a temperature of 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of mass ratio with respect to the support. When,
(C1) heat-treating the catalyst precursor heat-treated in the step (b) at a temperature equal to or higher than the thermal decomposition temperature of the palladium salt without cooling to a temperature of less than 40 ° C .;
A process for producing a palladium-containing supported catalyst, comprising: A method for producing a palladium-containing supported catalyst for producing an α, β-unsaturated carboxylic acid by liquid-phase oxidation of an olefin or α, β-unsaturated aldehyde with molecular oxygen,
(A) a step of mixing a support and a solution in which a palladium salt is dissolved in a solvent having a mass ratio of 0.3 to 20 with respect to the support to prepare a catalyst precursor;
(B) Heat-treating the catalyst precursor at a temperature of 40 ° C. or higher and lower than the thermal decomposition temperature of the palladium salt so that the mass of the residual solvent is 0.25 or less in terms of mass ratio with respect to the support. When,
(C2) The catalyst precursor heat-treated in the step (b) is cooled and stored at a temperature of less than 40 ° C. in a gas substantially free of moisture and the vapor of the solvent, and then the heat of the palladium salt. Heat treatment at a temperature equal to or higher than the decomposition temperature;
A process for producing a palladium-containing supported catalyst, comprising:   A palladium-containing supported catalyst obtained by the production method according to claim 1 or 2.   A method for producing an α, β-unsaturated carboxylic acid, which comprises subjecting an olefin or α, β-unsaturated aldehyde to liquid phase oxidation with molecular oxygen using the palladium-containing supported catalyst according to claim 3.