JP4768590B2 - Palladium-supported sepiolite catalyst and method for producing carbonyl compound - Google Patents

Description

  The present invention relates to an alcohol oxidation catalyst comprising palladium-supported sepiolite and a method for producing a carbonyl compound using the catalyst.

  As a method for producing a carbonyl compound by oxidizing alcohols, a method using an oxidizing agent such as manganese dioxide, chromic acid and selenium dioxide is known.

  On the other hand, a method using a catalyst using oxygen as an oxidizing agent is also known. For example, a method using a ruthenium complex (Patent Document 1), a method using a ruthenium-supported carbon catalyst or a ruthenium-supported alumina catalyst (Patent Document 2), a method using a ruthenium-supported hydrotalcite catalyst (Patent Document 3), an alkali-treated ruthenium A method using a supported alumina catalyst (Patent Document 4), a method using a ruthenium-supported hydroxyapatite catalyst (Non-Patent Document 1), and a method using a palladium-supported hydroxyapatite catalyst (Patent Document 5) are disclosed.

Japanese Patent Laid-Open No. 11-226417 US Pat. No. 4,996,007 JP 2000-70723 A JP 2004-894 A JP 2002-275116 A Journal of American Chemical Society, 122, 7144, 2000

  However, in the method using manganese dioxide, chromic acid, selenium dioxide and the like, it is necessary to use a stoichiometric amount of an oxidizing agent, which is not only uneconomical but also produces a large amount of waste liquid containing highly toxic heavy metals as a by-product. There are also environmental problems. In the method using a ruthenium complex as a catalyst, it is difficult to separate and recover the catalyst from the produced reaction solution containing the carbonyl compound, which is industrially disadvantageous. A solid catalyst such as a ruthenium-supported carbon catalyst is easy to separate and recover, but is industrially disadvantageous because of its low catalytic activity per ruthenium atom.

  The palladium-supported hydroxyapatite catalyst has a higher activity per metal atom than the ruthenium catalyst, but has a drawback that the amount of palladium that can be supported on the hydroxyapatite is extremely small. In particular, in a batch reaction, if the amount of palladium that can be supported is small, it is necessary to increase the production amount by using a large amount of catalyst, which not only reduces the production amount for the catalyst but also complicates the operation. Further, when the amount of the solvent is increased in order to simplify the operation, the productivity is lowered and it is uneconomical.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly active and highly efficient catalyst with good productivity that is used when oxidizing alcohol. It is to provide a method for economical production of compounds.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by using palladium-supported sepiolite as a catalyst, and have completed the present invention.

  That is, the present invention is an alcohol oxidation catalyst comprising a palladium-supported sepiolite.

  The present invention also provides a general formula (1)

［式中、Ｒ^１およびＲ^２は、同一または相異なって水素原子、置換されていてもよいフェニル基、置換されていてもよい炭素数１から４のアルキル基、置換されていてもよい炭素数２から４のアルケニル基または置換されていてもよい炭素数２から４のアルキニル基を示す。あるいは、Ｒ^１とＲ^２が結合する炭素原子と共に環を形成していても良い。ただし、Ｒ^１およびＲ^２が同時に水素原子ではない。］で表されるアルコール類を酸化して、一般式（２）

[Wherein, R ¹ and R ² are the same or different and each represents a hydrogen atom, an optionally substituted phenyl group, an optionally substituted alkyl group having 1 to 4 carbon atoms, or an optionally substituted carbon] An alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms which may be substituted is shown. Alternatively, they may form a ring with the carbon atom to which R ¹ and R ² are attached. However, R ¹ and R ² are not simultaneously hydrogen atoms. The alcohol represented by the general formula (2)

［式中、Ｒ^１およびＲ^２は、前記と同じ内容を示す。］で表されるカルボニル化合物を製造する際に、上述のアルコール酸化用触媒を用いることを特徴とする製造方法である。以下、本発明を詳細に説明する。

[Wherein R ¹ and R ² represent the same contents as described above. ] When manufacturing the carbonyl compound represented by this, it is the manufacturing method characterized by using the above-mentioned catalyst for alcohol oxidation. Hereinafter, the present invention will be described in detail.

Sepiolite used in the present invention is one of clay minerals, and an ideal chemical formula is represented by Mg ₈ Si ₁₂ O ₃₀ (OH) ₄ (H ₂ O) ₄ .nH ₂ O from the crystal structure. Here, (H ₂ O) ₄ represents bound water, and nH ₂ O represents zeolite water. The crystal structure of sepiolite is shared with SiO 4 ₄ tetrahedra oxygen so as to sandwich the apex oxygen MgO 6 _{6-coordinated} octahedral sheet from both sides, 2: 1 layer was formed, the sheet is periodically vertex direction A tunnel structure having a rectangular cross section as shown in FIG. 1 is formed by being reversed. Two molecules of water are coordinated with Mg ²⁺ present facing the tunnel wall to complete a hexacoordinate octahedron.

  The sepiolite used in the present invention may be used as it is, but it is desirable to perform the activation treatment in advance in view of high catalytic activity. Examples of the activation treatment include acid treatment, base treatment, heat treatment, vacuum treatment, reduction treatment and the like.

  The acid treatment is a treatment in which an acidic solution is removed by immersing in a solution showing acidity and stirring, and washing with distilled water or the like after a predetermined time. There is no restriction | limiting in particular in an acidic solution, The solution of an inorganic acid and its inorganic acid salt, an organic acid, and its organic acid salt can be used. Specific examples of inorganic acids and inorganic acid salts include hydrochloric acid, sulfuric acid, nitric acid, ammonium chloride, ammonium sulfate, and ammonium nitrate. Organic acids and organic acid salts thereof include formic acid, oxalic acid, acetic acid, fluoroacetic acid, benzenesulfonic acid, and toluene. Examples include sulfonic acid, ammonium benzenesulfonate, ammonium toluenesulfonate, and the like. Inorganic acids and inorganic acid salts thereof are preferred. The pH of the acidic solution is preferably 2 to 7 in order to avoid damage to the sepiolite skeleton. There is no restriction | limiting in particular in the temperature at the time of immersing in an acidic solution, Usually, 0 to 300 degreeC, Preferably it is 20 to 220 degreeC. Although there is no restriction | limiting in particular in the time of an acid treatment, Usually, 5 minutes-100 hours, Preferably it is 30 minutes-48 hours.

  The basic treatment is a treatment in which the basic solution is removed by immersing in a basic solution and stirring, and washing with distilled water or the like after a predetermined time. The basic solution is not particularly limited, and an inorganic base and organic base solution can be used. Specific examples of inorganic bases include lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, cesium hydrogen carbonate Sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, lithium formate, sodium formate, potassium formate, cesium formate, lithium oxalate, sodium oxalate, potassium oxalate, cesium oxalate, lithium acetate, sodium acetate , Potassium acetate, cesium acetate, ammonia and the like. Examples of the organic base include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, isopropylamine, butylamine, isobutylamine, tert-butylamine, pyridine, piperazine, piperidine, imidazole, pyrrole and morpholine. An inorganic base is preferable. The pH of the basic solution is preferably 9 to 14 because it is easy to support palladium. There is no restriction | limiting in particular in the temperature at the time of immersing in a basic solution, Usually, 0 to 300 degreeC, Preferably it is 20 to 220 degreeC. The time for the base treatment is not particularly limited, but is usually 5 minutes to 100 hours, preferably 30 minutes to 48 hours.

  The treatment temperature of the heat treatment is usually 50 ° C to 500 ° C, preferably 100 ° C to 400 ° C. Although there is no restriction | limiting in particular in the time of heat processing, Usually, 5 minutes-100 hours, Preferably they are 30 minutes-48 hours. The atmosphere at the time of heat treatment can be exemplified by air, inert gas such as oxygen and nitrogen, helium, argon, etc., but preferably in air.

  There is no restriction | limiting in particular in the processing temperature of a vacuum process, Usually, 0 to 500 degreeC, Preferably it is 50 to 250 degreeC. The treatment time is not particularly limited, but is usually 5 minutes to 100 hours, preferably 30 minutes to 48 hours.

  The reduction treatment is a heat treatment in advance in a hydrogen stream before using sepiolite. The treatment temperature is usually 50 ° C to 500 ° C, preferably 100 ° C to 400 ° C. The treatment time is not particularly limited, but is usually 5 minutes to 100 hours, preferably 30 minutes to 48 hours. The hydrogen gas may be diluted with an inert gas to form a hydrogen-containing mixed gas. The inert gas is not particularly limited, and examples thereof include nitrogen, carbon dioxide, and helium. The hydrogen partial pressure in the hydrogen-containing mixed gas may be at least 0.1% in order to increase the yield.

  The reduction treatment can also be performed using a reducing agent in the liquid phase. Examples of the reducing agent include hydrazine, hydroxyamine, hydroxyamine hydrochloride, hydroxyamine sulfate, methanol, ethanol, formaldehyde, formic acid, oxalic acid, methylamine, ethylamine, dimethylamine, diethylamine and the like. The treatment temperature is usually 0 ° C to 150 ° C, preferably 10 ° C to 110 ° C. The treatment time is not particularly limited, but is usually 5 minutes to 100 hours, preferably 30 minutes to 48 hours.

  In view of high catalytic activity, acid treatment and base treatment are more desirable.

  Next, a method for preparing a palladium-supported sepiolite catalyst will be described.

  Although it does not specifically limit as a palladium raw material, For example, palladium chloride, palladium bromide, palladium iodide, palladium acetate, palladium nitrate, palladium sulfate, palladium oxide, palladium oxides, palladium acetylacetonate, dichlorobisbenzo Palladium complexes such as nitrile palladium, dichlorobisacetonitrile palladium, dichlorobisammine palladium, tetraammine palladium chloride, dichlorobistriphenylphosphine palladium, tetrakistriphenylphosphine palladium, and the like can be used. Of these, palladium complexes are preferably used because they are easily supported and the yield of the target carbonyl compound is high, and tetraammine palladium chloride is preferably used from the viewpoint of operability.

  There is no particular limitation on the method of supporting palladium on sepiolite, and a normal supporting method such as an impregnation supporting method, an ion exchange method and a coprecipitation method can be used, but the catalyst activity is high and the operation is easy. The ion exchange method is preferable in that the reproducibility of catalyst preparation is high. When preparing a palladium-carrying sepiolite catalyst by an ion exchange method, for example, sepiolite is mixed in a solution containing the above palladium raw material and dried to prepare a palladium-carrying sepiolite catalyst.

  Although the solvent of the solution containing the palladium raw material at the time of ion exchange is not particularly limited, for example, alcohols such as methanol and ethanol, organic solvents such as ketones such as acetone and methyl ethyl ketone, and water are used. These solvents can be used alone or in combination of two or more. The concentration of the solution containing the palladium raw material is not particularly limited, but is usually 0.001 wt% to 20 wt%, preferably 0.05 wt% to 10 wt%.

  The ion exchange time is not particularly limited, but is preferably 1 hour to 100 hours because the ion exchange rate is increased.

  The ion exchange temperature is not particularly limited, but is preferably 0 ° C. to 100 ° C., more preferably 20 ° C. to 80 ° C., because the ion exchange rate is increased.

  After the ion exchange, the solvent is removed by an operation such as decantation, filtration, heating or heating under reduced pressure according to a conventional method. Drying after removing the solvent can be performed by heat drying, drying under reduced pressure, or the like. In the case of firing, it is preferably performed at 100 ° C. to 1000 ° C. in an atmosphere of oxygen or oxygen diluted with an inert gas such as nitrogen, helium, or argon, or air.

  In the present invention, the palladium-supported sepiolite catalyst may be further supported with an element other than palladium as long as it does not interfere with the production of the target product. For example, lithium, sodium, potassium, rubidium, cesium, beryllium, Magnesium, calcium, strontium, barium, scandium, yttrium, lanthanum, cerium, praseodymium, samarium, europium, titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, Rhodium, iridium, nickel, platinum, copper, silver, gold, zinc, cadmium, boron, aluminum, gallium, indium, thallium, germanium, tin, lead, antimony, bismuth Such as tellurium, and the like. Similar to palladium, these elements can be supported by using an impregnation supporting method, an ion exchange method, and a coprecipitation method using salts and complexes of each element.

  The palladium content of the palladium-supported sepiolite obtained as described above is not particularly limited, but is 0.01 wt% to 50 wt%, preferably 0.5 wt% to 20 wt% from the viewpoint of economy and production efficiency.

  This palladium-supported sepiolite can be used as a catalyst for oxidation of alcohols, and a carbonyl compound can be obtained by oxidizing alcohols by contacting the palladium-supported sepiolite catalyst with alcohols. There are no particular limitations on the alcohol or carbonyl compound at this time, but for example, the carbonyl compound represented by the general formula (2) can be obtained by oxidizing the alcohol represented by the general formula (1).

In the general formulas (1) and (2), the alkyl group having 1 to 4 carbon atoms represented by R ¹ and R ² specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, and a cyclopropyl group. Butyl group, isobutyl group, sec-butyl group, tert-butyl group, cyclobutyl group or cyclopropylmethyl group.

Specific examples of the alkenyl group having 2 to 4 carbon atoms represented by R ¹ and R ² include a vinyl group, 1-methylvinyl group, 1-propenyl group, 2-propenyl group, 3-butenyl group, 2- Examples thereof include a methyl-2-propenyl group, 1-ethylvinyl group, 2-butenyl group, 1,3-butanedienyl group and the like.

Specific examples of the alkynyl group having 2 to 4 carbon atoms represented by R ¹ and R ² include ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group and 3-butynyl. Examples include groups.

  These alkyl groups, alkenyl groups and alkynyl groups may be substituted with phenyl groups such as phenyl group, o-tolyl group, p-tolyl group, m-tolyl group, mesityl group, methoxyphenyl group, etc. Include phenylmethyl group, o-tolylmethyl group, m-tolylmethyl group, p-tolylmethyl group, mesitylmethyl group, o-methoxyphenylmethyl group, m-methoxyphenylmethyl group, p-methoxyphenylmethyl group, 1-phenylethyl Group, 2-phenylethyl group, 1-phenylpropyl group, 2-phenylpropyl group, 3-phenylpropyl group, 1-phenylbutyl group, 1-phenylvinyl group, 2-phenylvinyl group, 1-methyl-2- Phenylvinyl group, 2-phenyl-1-propenyl group, 3-phenyl-1-propenyl group, 1-phenyl 2-propenyl group, 2-phenyl-2-propenyl group, 3-phenyl-2-propenyl group, 1-phenyl-3-butenyl group, 2-methyl-1-phenyl-2-propenyl group, 1-ethyl-2 -Phenylvinyl group, 1-phenyl-2-butenyl group, 2-phenyl-1,3-butanedienyl group, 4-phenyl-1,3-butanedienyl group, 2-phenyl-ethynyl group, 1-phenyl-1-propynyl Group, 1-phenyl-2-propynyl group, 3-phenyl-2-propynyl group, 3-phenyl-1-butynyl group, 4-phenyl-1-butynyl group, 1-phenyl-2-butynyl group, 1-phenyl Examples include a -3-butynyl group.

Examples of the optionally substituted phenyl group represented by R ¹ and R ² include a phenyl group, an o-tolyl group, a p-tolyl group, an m-tolyl group, a mesityl group, a methoxyphenyl group, and o-trifluoromethylphenyl. Group, m-trifluoromethylphenyl group, p-trifluoromethylphenyl group, o-difluoromethylphenyl group, m-difluoromethylphenyl group, p-difluoromethylphenyl group, o-fluorophenyl group, m-fluorophenyl group , P-fluorophenyl group, 3,5-difluorophenyl group and the like.

Examples of alcohols (1) that form a ring together with the carbon atom to which R ¹ and R ² are bonded include cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, 2-cyclopenten-1-ol, 2- Examples include cyclohexen-1-ol.

  The oxidizing agent that can be used in this reaction may be an organic peroxide such as hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc., but the reaction proceeds sufficiently even with air or oxygen.

  When air or oxygen is used, an oxygen-containing mixed gas may be diluted with an inert gas. The inert gas is not particularly limited, and examples thereof include nitrogen, carbon dioxide, and helium. The oxygen partial pressure in the oxygen-containing mixed gas may be at least 0.1%.

  The reaction mode in the production of the carbonyl compound by oxidation of the alcohols of the present invention is not particularly limited, and can be performed in any reaction mode. For example, it can be carried out by a fixed bed gas phase flow type, a fixed bed liquid phase flow type, or a suspension bed batch type. From the viewpoint of easy operation, a suspension bed batch system is desirable.

  When carrying out by a suspension bed batch type, a solvent may be used and it can carry out without a solvent. Examples of the solvent include, but are not limited to, aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cyclooctane, and decahydronaphthalene. Aliphatic hydrocarbons such as benzene, toluene and xylene, halogenated aromatic hydrocarbons such as chlorobenzene and trifluorotoluene, ethyl ether, tetrahydrofuran, dioxane, diglyme, triglyme, etc. Ethers, acetone, methyl ethyl ketone, ketones such as cyclohexanone, esters such as methyl acetate and ethyl acetate, nitriles such as acetonitrile, amides such as N-methylpyrrolidone, dichloromethane, chloroform Carbon tetrachloride, dichloroethane, trichloroethane, halogenated hydrocarbons such as tetrachloroethane and the like. From the viewpoint of operation, aromatic hydrocarbons such as benzene, toluene and xylene are preferable.

  The reaction temperature is not particularly limited, but is preferably 0 ° C to 300 ° C, more preferably 20 ° C to 200 ° C from the viewpoint of production efficiency. Although the reaction pressure is not particularly limited, it is usually preferably 0.01 MPa to 10 MPa, more preferably 0.1 MPa to 1 MPa in terms of absolute pressure from the viewpoint of production efficiency. Although reaction time in particular is not restrict | limited, Since it can fully convert into a carbonyl compound, Preferably it is 1 minute-100 hours, More preferably, it is 5 minutes-50 hours.

  The raw material concentration is preferably 0.0001 g / L or more, more preferably 0.001 g / L or more because it can be efficiently converted into a carbonyl compound.

  The amount of the catalyst to be used is not particularly limited, and from the viewpoint of production efficiency, the palladium metal is 0.000001 to 20.0 mol%, preferably 0.00001 to 10.0 mol per mol of the starting alcohol. %, More preferably 0.0001 to 5.0 mol% of palladium-supported sepiolite catalyst.

  By using a palladium-supported sepiolite catalyst in which palladium is supported on the sepiolite of the present invention, an alcohol can be oxidized to produce a carbonyl compound industrially advantageously with high productivity.

  Examples and Comparative Examples of the present invention are shown below, but the present invention is not limited to these.

Example 1 Production of a palladium-carrying sepiolite catalyst 2.0 g of sepiolite manufactured by Wako Pure Chemical Industries, Ltd. was suspended in an acidic solution in which 10 g of ammonium chloride was dissolved in 80 mL of distilled water, and stirred at room temperature for 48 hours. The suspension was subjected to suction filtration and washing repeatedly to obtain acid-treated sepiolite. Next, 2.0 g of sepiolite treated as described above was suspended in an aqueous palladium solution in which 0.2 g of palladium tetraammine palladium chloride was dissolved in 80 mL of distilled water, and the mixture was stirred at room temperature for 48 hours. This suspension was suction filtered and dried at 110 ° C. to obtain a palladium-supported sepiolite catalyst. The palladium content was 1.3 wt%.

Example 2
1.08 g (10 mmol) of benzyl alcohol was added to 5 ml of toluene solvent, 0.1 g of palladium-supported sepiolite catalyst was suspended, oxygen was passed through at atmospheric pressure at 10 mL / min, and reaction was performed at 100 ° C. for 1 hour. When the reaction solution was analyzed by gas chromatography after the reaction, the conversion rate of benzyl alcohol was 96% and the production rate of benzaldehyde was 91%. The space-time yield was 9800 g / kg-cat · h.

Example 3
1.22 g (10 mmol) of 1-phenylethanol was added to 5 mL of a toluene solvent, 0.1 g of palladium-supported sepiolite catalyst was suspended, oxygen was passed through at atmospheric pressure at 10 mL / min, and reacted at 100 ° C. for 1 hour. . When analyzed in the same manner as in Example 2, the 1-phenylethanol conversion was 77% and the acetophenone production rate was 73%. The space time yield was 8600 g / kg-cat · h.

Comparative Example 1
In a toluene solution to which 0.11 g (1 mmol) of benzyl alcohol was added, 0.3 g of palladium-supported hydroxyapatite prepared according to Japanese Patent Laid-Open No. 2002-275116 was suspended, and oxygen was allowed to flow at 10 mL / min at atmospheric pressure. For 2 hours. When analyzed in the same manner as in Example 2, the benzyl alcohol conversion was 100% and the benzaldehyde production rate was 82%. The space time yield was 145 g / kg-cat · h.

It is a figure which shows the crystal structure of sepiolite.

Claims (4)

A catalyst for alcohol oxidation, comprising a palladium-supported sepiolite. General formula (1)

[Wherein, R ¹ and R ² are the same or different and each represents a hydrogen atom, an optionally substituted phenyl group, an optionally substituted alkyl group having 1 to 4 carbon atoms, or an optionally substituted carbon] An alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms which may be substituted is shown. Alternatively, they may form a ring with the carbon atom to which R ¹ and R ² are attached. However, R ¹ and R ² are not simultaneously hydrogen atoms. The alcohol represented by the general formula (2)

[Wherein R ¹ and R ² represent the same contents as described above. ] The manufacturing method characterized by using the catalyst of Claim 1 when manufacturing the carbonyl compound represented by this. The process according to claim 2, wherein the reaction temperature is from 0C to 300C. The production method according to claim 2 or 3, wherein the reaction pressure is from 0.01 MPa to 10 MPa.

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