JP2005324084A - METHOD FOR PRODUCING PALLADIUM-CONTAINING CATALYST, PALLADIUM-CONTAINING CATALYST, AND METHOD FOR PRODUCING alpha,beta-UNSATURATED CARBOXYLIC ACID - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a palladium-containing catalyst by which it is possible to produce an objective substance in a good productivity; and to provide the palladium-containing catalyst and a method for producing an α,β-unsaturated carboxylic acid using the catalyst. <P>SOLUTION: The method for producing the palladium-containing catalyst includes at lest a reduction process for reducing a palladium compound containing palladium atom in an oxidized state, and in the method, the reduction is performed by using an olefin and an aldehyde separately or simultaneously. The palladium-containing catalyst is produced by the method. The method for producing the α,β-unsaturated carboxylic acid comprises performing liquid phase oxidation of an olefin or an α,β-unsaturated aldehyde with molecular oxygen by using the palladium-containing catalyst produced by the method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a palladium-containing catalyst and a palladium-containing catalyst. The present invention also relates to a method for producing an α, β-unsaturated carboxylic acid from an olefin or an α, β-unsaturated aldehyde.

  As described in Non-Patent Document 1, the precious metal-containing catalyst is used for various purposes such as environmental conservation use including purification of exhaust gas from automobiles, chemical use such as petroleum refining, petrochemistry, medicine, fragrance and food. in use. In chemical applications, it is used as a catalyst for synthesizing and producing various compounds by various chemical reactions such as hydrogenation, dehydrogenation, oxidation, carbonylation, hydroformylation and the like. Many of these have already been established industrially, but some of them are still under development and development for industrialization is underway.

One of those under development is a palladium-containing catalyst used in a method for producing an α, β-unsaturated carboxylic acid by oxidizing an olefin or an α, β-unsaturated aldehyde with molecular oxygen. For example, Patent Document 1 discloses a method for reducing palladium in an oxidized state with an olefin having 3 to 6 carbon atoms. It is also described that a supported catalyst can be produced by the above method.
JP 60-155148 A By Muroi Takagi, industrial precious metal catalyst, published by JETI

  When the present inventor produced acrylic acid from propylene using a palladium-containing catalyst produced according to the method described in the example of Patent Document 1, the reaction rate of propylene is low and the productivity of acrylic acid is low. found. When productivity deteriorates, it may become a factor which raises manufacturing cost. As described above, the palladium-containing catalyst produced by the method described in Patent Document 1 is not yet sufficient for the production of α, β-unsaturated carboxylic acid, and a palladium-containing catalyst with higher productivity has been desired.

  An object of the present invention is to provide a method for producing a palladium-containing catalyst capable of producing an object product with high productivity, a palladium-containing catalyst, and a method for producing an α, β-unsaturated carboxylic acid using the same.

  That is, the first gist of the present invention is a method for producing a palladium-containing catalyst having a reduction step of reducing a palladium compound containing a palladium atom in an oxidized state, wherein the reduction is performed using olefin and aldehyde separately or simultaneously. Is a method for producing a palladium catalyst.

  It is preferable to reduce using the aldehyde after reducing using the olefin.

  Moreover, it is suitable as a method for producing a palladium-containing catalyst in which a reduction product obtained by reducing a palladium compound is carried on the carrier by carrying out the reduction step in the presence of a carrier.

  The second gist of the present invention is a palladium-containing catalyst produced by the method described above.

  The third gist of the present invention is an α, β-unsaturated carboxylic acid that liquid-phase oxidizes an olefin or α, β-unsaturated aldehyde with molecular oxygen using the palladium-containing catalyst produced by the above-described method. It is a manufacturing method.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the palladium containing catalyst which can obtain a target object with sufficient productivity, the palladium containing catalyst, and the manufacturing method of (alpha), (beta)-unsaturated carboxylic acid using the same can be provided.

  The method for producing a palladium-containing catalyst of the present invention is a method having at least a reduction step of reducing a palladium compound containing a palladium atom in an oxidized state, and is a method of reducing using an olefin and an aldehyde separately or simultaneously.

  Examples of the palladium compound containing an oxidized palladium atom that is a catalyst raw material include palladium salts, palladium oxides, palladium oxide alloys, and the like, among which palladium salts are preferable. Examples of the palladium salt include palladium chloride, palladium acetate, palladium nitrate, palladium sulfate, tetraamminepalladium chloride and bis (acetylacetonato) palladium, among which palladium chloride, palladium acetate, tetraamminepalladium chloride. Is preferred.

  The reduction of the palladium compound containing an oxidized palladium atom as the catalyst raw material is preferably performed in a liquid phase. Specifically, a palladium compound containing a palladium atom in an oxidized state is dissolved in an appropriate solvent, and the palladium compound is reduced using a reducing agent. Thereby, palladium metal precipitates and becomes a palladium-containing catalyst.

  In the present invention, it is necessary to use both olefin and aldehyde as the reducing agent. When none of them is used or only one of them is used, the performance of the resulting palladium-containing catalyst is deteriorated. As long as these two kinds of reducing agents are used, different reducing agents may be additionally used.

  Examples of the olefin used as the reducing agent include ethylene, propylene, 1-butene, 2-butene, and isobutylene. Among them, propylene is preferable. The reduction using olefin is preferably carried out in a pressure device such as an autoclave in order to increase the solubility of the olefin in the solution. At that time, the inside of the pressurizer is pressurized with a reducing agent. The pressure is usually 0.1 to 1.0 MPa (gauge pressure; hereinafter, all pressures are expressed as gauge pressures).

  Examples of the aldehyde used as the reducing agent include formaldehyde, acrolein, methacrolein, and crotonaldehyde. Among these, formaldehyde is preferable. There is no restriction | limiting in the apparatus which performs the reduction | restoration using an aldehyde, It can carry out by adding a reducing agent in a palladium compound solution. Although the usage-amount of a reducing agent at this time is not specifically limited, It is about 1-100 mol normally with respect to 1 mol of palladium atoms.

  In the reduction step, the reduction using olefin may be performed first, or the reduction using aldehyde may be performed first, and the olefin and the aldehyde may be used together. However, after the reduction using olefin, the aldehyde is used. It is most effective to reduce it.

  The reduction temperature is usually −5 ° C. or higher, preferably 15 ° C. or higher. Moreover, it is normally performed at 150 ° C. or lower, preferably 80 ° C. or lower. The reduction time is usually 0.1 hour or longer, preferably 0.25 hour or longer, more preferably 0.5 hour or longer. Moreover, it is 4 hours or less normally, Preferably it is 3 hours or less, More preferably, it is 2 hours or less. In addition, when reducing using olefin and an aldehyde separately, reduction temperature and / or reduction time can be set suitably independently.

  Solvents used in the reduction in the liquid phase include alcohols such as water, ethanol, 1-propanol, 2-propanol, n-butanol and t-butanol; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like. Ketones; organic acids such as acetic acid, n-valeric acid and iso-valeric acid; and organic solvents such as hydrocarbons such as heptane, hexane and cyclohexane can be used alone or in combination. Moreover, the mixed solvent of these organic solvents and water can also be used. The content of water in the mixed solvent of the organic solvent and water is not particularly limited. Water is preferred as the solvent for reduction with formaldehyde.

When preparing a supported palladium-containing catalyst supported on a carrier, the reduction step can be performed in the presence of the carrier. Specifically, it may be reduced in the same manner as when the carrier is not used except that the carrier is dispersed in the palladium compound solution at a desired stage. That is, the carrier may be dispersed in the palladium compound solution before or after the reduction step, but it is preferable to disperse the carrier in the palladium compound solution before the reduction step. Examples of the carrier include activated carbon, carbon black, silica, alumina, magnesia, calcia, titania and zirconia. Among them, activated carbon, silica and alumina are preferable. Although specific surface area of the support can not be said sweepingly because different by type of carrier, if activated carbon, 100 m ² / g or more, more preferably 300 meters ² / g or more, preferably 5000 m ² / g or less, more preferably 4000 m ² / g or less. As the specific surface area of the activated carbon is smaller than the above upper limit, it becomes possible to produce a palladium-containing catalyst in which useful components are supported on the surface. It becomes.

  In the preparation of an activated carbon-supported palladium-containing catalyst, when the solution containing the palladium compound comes into contact with the support before contacting with the reducing agent, the palladium compound is reduced by the reaction with the active groups present on the outer surface of the support, thereby producing palladium metal. May be deposited, resulting in a palladium-containing catalyst in which palladium metal is unevenly distributed on the outer surface of the support. In order to prevent such reduction and to obtain an activated carbon-supported palladium-containing catalyst in which palladium metal is uniformly dispersed into the inside of the support, for example, hydrogen peroxide, nitric acid, It is preferable that an appropriate amount of an oxidizing agent such as hypochlorous acid is present. Even when the carrier is not used, the palladium compound may be reduced depending on the preparation conditions. In this case, the reduction can be prevented in the same manner.

  In the case of a supported type palladium-containing catalyst, the supported rate of palladium metal is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, relative to the mass of the carrier before support. And particularly preferably 4% by mass or more. Moreover, it is 40 mass% or less normally, Preferably it is 30 mass% or less, More preferably, it is 20 mass% or less, Most preferably, it is 15 mass% or less.

  The palladium-containing catalyst of the present invention contains palladium metal obtained by reducing a palladium compound by the above method, but ruthenium, rhodium, silver, osmium, iridium, platinum, gold, copper, antimony, One or more kinds of other metals such as tellurium, lead, and bismuth can be contained. Such a palladium-containing catalyst can be obtained by performing a reduction step in the presence of a metal compound corresponding to another metal. From the viewpoint of expressing high catalytic activity, it is preferable that 50% by mass or more of the metal contained in the palladium-containing catalyst is palladium metal.

  The palladium-containing catalyst deposited by reduction (hereinafter also simply referred to as catalyst) is preferably washed with water, an organic solvent or the like. By washing, for example, impurities derived from palladium salts such as chloride, acetate, nitrate and sulfate 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. The washed catalyst may be recovered by filtration or centrifugation, and then used for a liquid phase oxidation reaction. This washing is preferably performed at the stage where the reduction process is completed. Moreover, when reducing using olefin and an aldehyde separately, it is also preferable to wash | clean at the completion of each reduction | restoration.

  Next, the catalyst recovered by filtration or the like may be used after drying. Although the drying method is not particularly limited, it is usually dried in air or in an inert gas using a dryer. The dried catalyst is activated before use in a liquid phase oxidation reaction, if necessary. 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 palladium-containing catalyst thus produced can be used for various reactions. For producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of an olefin or α, β-unsaturated aldehyde with molecular oxygen. It is effective when used as a catalyst, and particularly effective when used as a catalyst for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen. Here, a method for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin or α, β-unsaturated aldehyde with molecular oxygen will be described.

  Examples of the raw material olefin include propylene, isobutylene, 1-butene, and 2-butene. Among these, propylene or isobutylene is preferable. Examples of the raw material α, β-unsaturated aldehyde include acrolein, methacrolein, crotonaldehyde (β-methylacrolein), cinnamaldehyde (β-phenylacrolein), among which acrolein or methacrolein is used. Is preferred. The raw material olefin or α, β-unsaturated aldehyde may contain a small amount of saturated hydrocarbon, lower saturated aldehyde and the like as impurities.

  The α, β-unsaturated carboxylic acid produced by liquid phase oxidation is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the raw material olefin or α, β-unsaturated aldehyde. The catalyst of the present invention is suitable as a catalyst for liquid phase oxidation for producing acrylic acid from propylene or acrolein, or methacrylic acid from isobutylene or methacrolein.

  Air is economical as the molecular oxygen source used in the reaction, but pure oxygen or a mixed gas of pure oxygen and air can also be used. If necessary, air or pure oxygen is converted into nitrogen, carbon dioxide, water vapor. It is also possible to use a mixed gas diluted with the same.

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

  Examples of the reaction solvent for the liquid phase oxidation reaction include tertiary butanol, cyclohexanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, iso-valeric acid, It is preferable to use at least one compound selected from the group consisting of ethyl acetate and methyl propionate. Among these, at least one compound selected from the group consisting of tertiary 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 high selectivity, it is preferable to coexist water in these organic solvents. The amount of water to coexist is not particularly limited, but is usually 2% by mass or more, preferably 5% by mass or more, based on the total mass of the organic solvent and water. Moreover, it is 70 mass% or less normally, Preferably it is 50 mass% or less. The mixture of the organic solvent and water is desirably in a uniform state, but may be in a non-uniform state.

  The concentration of the olefin or α, β-unsaturated aldehyde which is a raw material for the reaction is usually 0.1% by mass or more, preferably 0.5% by mass or more, based on the solvent present in the reactor. Moreover, it is 20 mass% or less normally, Preferably it is 10 mass% or less.

  The amount of molecular oxygen to be used is usually 0.1 mol or more, preferably 0.3 mol or more, more preferably 0.5 mol or more with respect to 1 mol of the raw material olefin or α, β-unsaturated aldehyde. is there. Moreover, it is 20 mol or less normally, Preferably it is 15 mol or less, More preferably, it is 10 mol or less.

  Usually, the catalyst of the present invention is used in a state suspended in a reaction solution, but may be used in a fixed bed. The amount used is usually 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more with respect to the solution present in the reactor. Moreover, it is 30 mass% or less normally, 20 mass% or less is more preferable, and 15 mass% or less is further more preferable.

  The reaction temperature and reaction pressure are appropriately selected depending on the solvent used and the reaction raw materials. The reaction temperature is generally 30 to 200 ° C, preferably 50 ° C or higher, and preferably 150 ° C or lower. The reaction pressure is generally atmospheric pressure (0 MPa) to 10 MPa, preferably 0.5 MPa or more, and preferably 5 MPa or less.

  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. In the following Examples and Comparative Examples, “part” means “part by mass”.

(Analysis of raw materials and products)
Analysis of raw materials and products was performed using gas chromatography. The reaction rate of isobutylene, the methacrolein (MAL), the selectivity of methacrylic acid (MAA) and the polymer / oligomer, and the yield and productivity of MAA are defined as follows.

Reaction rate of isobutylene (%) = (B / A) × 100
Selectivity (%) of methacrolein (MAL) = (C / B) × 100
Methacrylic acid (MAA) selectivity (%) = (D / B) × 100
Selectivity of polymer / oligomer (%) = (E / B) × 100
MAA yield (%) = (D / A) × 100
MAA productivity (g / gMe / h) = F / (G × H)
here,
A is the number of moles of isobutylene supplied,
B is the number of moles of reacted isobutylene,
C is the number of moles of methacrolein produced,
D is the number of moles of methacrylic acid produced,
E is the number of moles of polymer and oligomer in terms of isobutylene calculated by dividing the total mass (unit: g) of the produced polymer and oligomer by the molecular weight of the supplied isobutylene,
F is the mass of the generated methacrylic acid (unit: g),
G is the mass of palladium contained in the palladium-containing catalyst (unit: g),
H is the reaction time (unit: hours).

[Example 1]
(Catalyst preparation)
1.1 parts of palladium acetate was dissolved by heating in 60 parts of an 88 mass% n-valeric acid aqueous solution. To this solution, 5.0 parts of activated carbon (specific surface area of 780 m ^{2 /} g) was added, charged in an autoclave and sealed. Stirring was started, and after cooling the temperature of the internal liquid to 10 ° C. or lower, propylene gas was introduced to an internal pressure of 0.5 MPa, and then maintained at 50 ° C. for 1 hour. After holding for 1 hour, the temperature of the internal solution was lowered to 20 ° C. or lower, and then the internal pressure was released. Then, it suction-filtered and wash | cleaned several times with water. The solid thus obtained was dispersed in 20 parts of water, and 0.1N aqueous sodium hydroxide solution was added to adjust the pH to 10. Further, formalin (37% by weight aqueous solution of formaldehyde) 3.81 parts and 50 parts of water were added, and the suspension was heated at 90 ° C. After 2 hours, the temperature of the suspension was lowered to 20 ° C. or lower, filtered with suction, and washed 3 times with 500 parts of water. It dried at 100 degreeC overnight and the activated carbon carrying type palladium catalyst was obtained. The palladium loading rate of this catalyst was 10% by mass.

(Reaction evaluation)
The autoclave was sealed with 6.0 parts of the activated carbon-supported palladium catalyst obtained by the above method and 75 parts of a 75% by mass aqueous tertiary butanol solution as a reaction solvent, and the autoclave was sealed. Next, 2.0 parts of isobutylene was introduced, stirring (rotation speed: 100 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 0.1 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 performed for 60 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 by a membrane filter, and only the reaction solution was recovered. The collected reaction liquid and the collected gas were analyzed by gas chromatography. The results are shown in Table 1. It was found that MAA productivity was high.

[Comparative Example 1]
(Catalyst preparation)
1.1 parts of palladium acetate was dissolved by heating in 60 parts of an 88 mass% n-valeric acid aqueous solution. To this solution, 5.0 parts of activated carbon (specific surface area of 780 m ^{2 /} g) was added, charged in an autoclave and sealed. Stirring was started, and after cooling the temperature of the internal liquid to 10 ° C. or lower, propylene gas was introduced to an internal pressure of 0.5 MPa, and then maintained at 50 ° C. for 1 hour. After holding for 1 hour, the temperature of the internal solution was lowered to 20 ° C. or lower, and then the internal pressure was released. Thereafter, the mixture was suction filtered and washed several times with 75% by mass tertiary butanol to obtain an activated carbon-supported palladium catalyst. The palladium loading rate of this catalyst was 10% by mass.

(Reaction evaluation)
Evaluation similar to Example 1 was performed using this catalyst. The results are shown in Table 1. MAA productivity was low.

Claims (5)

  A method for producing a palladium-containing catalyst comprising at least a reduction step for reducing a palladium compound containing a palladium atom in an oxidized state, wherein the reduction is carried out using olefin and aldehyde separately or simultaneously. Method.   The method for producing a palladium-containing catalyst according to claim 1, wherein the reduction is performed using the olefin, and then the reduction is performed using the aldehyde.   3. The palladium-containing catalyst in which a reduced product obtained by reducing a palladium compound is supported on the carrier is produced by performing the reduction step in the presence of a carrier. A method for producing a palladium-containing catalyst.   The palladium containing catalyst manufactured by the method of any one of Claims 1-3.   A method for producing an α, β-unsaturated carboxylic acid, which comprises subjecting an olefin or an α, β-unsaturated aldehyde to liquid phase oxidation with molecular oxygen using the palladium-containing catalyst according to claim 4.