Method for producing oxide and method for producing pt / bi composite catalyst

Abstract

The present invention relates to a method for producing an oxide with which an oxide of an organic compound can be obtained efficiently in the presence of a raw material for a Pt / Bi composite catalyst, and a method for producing a Pt / Bi composite catalyst with which it is possible to produce a catalyst exhibiting high activity in a dehydrogenation oxidation reaction of an organic compound, even in the present of an organic compound which is the raw material of an oxide.　Provided is a method for producing an oxide, wherein an organic compound that has one primary hydroxyl group is subjected to a dehydrogenation oxidation reaction in the presence of water and a Pt, Bi ion source supported by a carrier, in conditions such that the minimum pH value during the reaction is less than 7, so as to obtain an oxide of the organic compound.

Description

Method for producing oxide and method for producing Pt / Bi composite catalyst

[0001] The present invention relates to a method for producing an oxide and a method for producing a Pt / Bi composite catalyst.

[0002] Conventionally, a method has been known in which a platinum noble metal catalyst is combined with bismuth (Bi) as a promoter to catalytically dehydrogenate and oxidize hydroxy compounds or aldehyde compounds, thereby converting them into the corresponding carboxy compounds or ketone compounds. Japanese Patent Application Laid-Open No. 2016-120484 (Patent Document 1) discloses a method for preparing a catalyst by adding an aqueous dispersion of a platinum catalyst supported on activated carbon to an aqueous solution containing bismuth (Bi) in an ionic state, and a method for producing an oxide by dehydrogenating an alcohol or the like in the presence of the catalyst obtained by the preparation method. Japanese Patent Application Laid-Open No. 1-146840 (Patent Document 2) discloses a method for producing an ethercarboxylic acid by oxidizing a polyalkoxy alcohol or an aliphatic alcohol alkoxylate in an alkaline aqueous phase in the presence of a catalyst containing a noble metal of Group VIII of the periodic table, such as palladium or platinum.

[0003] The present invention relates to a method for producing an oxide, which comprises dehydrogenating an organic compound having one primary hydroxyl group in the presence of Pt supported on a carrier, a Bi ion source, and water, under conditions where the minimum pH during the reaction is less than 7, to obtain an oxide of the organic compound. The present invention also relates to a method for producing a Pt / Bi composite catalyst, which comprises mixing Pt supported on a carrier and a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting the resulting mixture under conditions where the minimum pH during the reaction is less than 7.

[0004] The catalyst preparation method described in Patent Document 1 involves a separate process from the production process of an oxide of alcohol or the like, and therefore requires the preparation of a catalyst production facility separate from the production facility of the oxide of alcohol or the like. Furthermore, the catalyst preparation process requires a process of separating and purifying the catalyst in addition to a process of preparing raw materials for the catalyst. Furthermore, the prepared catalyst must be stored under appropriate storage conditions until it is used to produce the oxide of alcohol or the like. Therefore, there is a problem in that the preparation of the catalyst requires significant cost and labor, separate from the production of the oxide of alcohol or the like. Furthermore, the production method of ethercarboxylic acid described in Patent Document 2 has a problem in that the productivity of ethercarboxylic acid is low.

[0005] The present invention relates to a method for producing an oxide, which can efficiently produce an oxide of an organic compound in the presence of a raw material for the Pt / Bi composite catalyst, and a method for producing a Pt / Bi composite catalyst, which can produce a catalyst that exhibits high activity in the dehydrogenation reaction of an organic compound even in the presence of the organic compound that serves as the raw material for the oxide.

[0006] The inventors have discovered that, even in the presence of raw materials for a Pt / Bi composite catalyst, oxides of organic compounds can be efficiently obtained by maintaining a pH of less than 7 during the reaction. Furthermore, even in the presence of an organic compound serving as a raw material for the oxide, a catalyst exhibiting high activity in the dehydrogenation oxidation reaction of organic compounds can be produced by maintaining a pH of less than 7 during the reaction. The present invention relates to the following [1] and [2]: [1] A method for producing an oxide, comprising: dehydrogenating an organic compound having one primary hydroxyl group in the presence of Pt supported on a carrier, a Bi ion source, and water under conditions where the minimum pH during the reaction is less than 7; and [2] A method for producing a Pt / Bi composite catalyst, comprising mixing Pt supported on a carrier and a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting the mixture under conditions where the minimum pH during the reaction is less than 7.

[0007] The present invention provides a method for producing an oxide, which can efficiently produce an oxide of an organic compound in the presence of a raw material for the Pt / Bi composite catalyst, and a method for producing a Pt / Bi composite catalyst, which can produce a catalyst that exhibits high activity in the dehydrogenation reaction of an organic compound even in the presence of the organic compound that serves as the raw material for the oxide.

[0008] The present invention will be described in detail below.

[0009] [Method for Producing Oxide] The method for producing an oxide of the present invention comprises subjecting an organic compound having one primary hydroxyl group (hereinafter also simply referred to as "organic compound") to a dehydrogenative oxidation reaction in the presence of Pt supported on a carrier, a Bi ion source, and water under conditions where the minimum pH during the reaction is less than 7, to obtain an oxide of the organic compound.

[0010] The oxide production method of the present invention allows efficient production of oxides of organic compounds. The reason for this effect is unclear, but is presumed to be as follows. In the oxide production method of the present invention, the Pt / Bi composite catalyst used in the dehydrogenative oxidation of organic compounds is charged as a raw material together with the Pt / Bi composite catalyst used in the reaction, and the organic compound is dehydrogenated while the Pt / Bi composite catalyst is produced in the reaction system. Conventional catalysts, such as the Pt / Bi composite catalyst used in the dehydrogenative oxidation of organic compounds, are typically prepared by adding a reducing agent to a Pt ion source and a Bi ion source under alkaline conditions to precipitate Pt and Bi, thereby preparing a Pt and Bi composite catalyst. However, the Bi segregates during this process, which is thought to result in few active structures effective in the dehydrogenative oxidation of organic compounds and low catalytic activity. On the other hand, in the present invention, when Pt supported on a carrier is contacted with a Bi ion source under conditions where the minimum pH during the reaction is less than 7, Bi can be uniformly reduced and precipitated on the Pt without a reducing agent, forming many active structures effective in the dehydrogenation oxidation of organic compounds, presumably resulting in high catalytic activity. Furthermore, in conventional dehydrogenation oxidation reactions of organic compounds containing hydroxyl or aldehyde groups, alkaline conditions have been used to improve reactivity when the catalyst exhibits low activity. However, in the oxide production method of the present invention, the minimum pH during the reaction is less than 7, and the catalytic activity can be increased as described above, thereby improving the production rate of the oxide of the organic compound without the addition of an alkaline agent. Furthermore, when the dehydrogenation oxidation reaction is performed under conventional alkaline conditions, an alkaline agent or the like is added to create alkaline conditions in the system, resulting in the by-production of a neutralized salt of the oxide. When a neutralized salt of an oxide is formed in a reaction system, the viscosity of the reaction solution increases and the reaction solution gels if the oxide / water ratio is high compared to when only the oxide is present. Therefore, in conventional oxidation reactions under alkaline conditions, the reaction must be carried out in a composition with a low oxide / water ratio and a low concentration of active ingredients, making it difficult to increase productivity.On the other hand, in the method for producing an oxide of the present invention, it is possible to suppress the by-production of neutralized salt of the oxide, and to suppress an increase in viscosity and gelation of the reaction solution, so that an organic compound can be efficiently dehydrogenated and oxidized in a composition with a high oxide / water ratio and a high concentration of active ingredients, thereby improving productivity. Furthermore, it is possible to suppress the generation of salt that is generated when extracting the oxide from the by-produced neutralized salt of the oxide, thereby suppressing the generation of waste liquid and reducing the environmental burden.

[0011] Furthermore, in the oxide production method of the present invention, from the viewpoint of obtaining an oxide of an organic compound at a high production rate, the preparation of a Pt / Bi composite catalyst is preferably accompanied. The reason for the preferred inclusion of the preparation of a Pt / Bi composite catalyst is unclear, but is believed to be as follows: By mixing an organic compound in the presence of Pt supported on the carrier and the Bi ion source, a dehydrogenation-oxidation reaction of the organic compound occurs. This produces a small amount of the oxide of the organic compound, forming an oxide-containing solution. It is presumed that the Bi ion source dissolves, generating Bi ions, and Bi is reduced and precipitated on the Pt, thereby preparing a Pt / Bi composite catalyst in the system, which has higher activity than a Pt catalyst. It is also presumed that the preparation of the Pt / Bi composite catalyst promotes the dehydrogenation reaction of the organic compound, resulting in a high yield of the oxide of the organic compound. From the above, the oxide production method of the present invention can simultaneously prepare a catalyst during the oxide production process, eliminating the need for separate catalyst production equipment or processes, allowing for efficient production of an oxide of an organic compound, offering significant advantages in terms of production efficiency and production costs.

[0012] In this specification, unless otherwise specified, Pt means platinum, Bi means bismuth, and C means activated carbon. In addition, unless otherwise specified, "%" means "mass %."

[0013] <Organic Compound Having One Primary Hydroxyl Group> The method for producing an oxide of the present invention is carried out by subjecting an organic compound having one primary hydroxyl group (hereinafter also referred to simply as organic compound) to a dehydrogenation oxidation reaction. Examples of organic compounds having one primary hydroxyl group include aliphatic alcohols, polyoxyalkylene alkyl ethers, amide alcohols, and aromatic alcohols. From the viewpoint of hydrophilicity, preferred is at least one selected from aliphatic alcohols, polyoxyalkylene alkyl ethers, and amide alcohols, and more preferred is at least one selected from aliphatic alcohols and polyoxyalkylene alkyl ethers. The aliphatic alcohol or polyoxyalkylene alkyl ether is preferably one or more of the following general formula (1) or (2):

[0014] R １ O-H (1) In general formula (1), R １ is a monovalent aliphatic hydrocarbon group having 2 to 40 carbon atoms.

[0015] R ２ O-(AO) ｎ -H (2) In general formula (2), R ２ represents a monovalent aliphatic hydrocarbon group having from 2 to 40 carbon atoms, A represents an alkanediyl group having from 2 to 4 carbon atoms, AO represents an alkyleneoxy group, and n is the average number of moles of alkyleneoxy groups added, which is from 1 to 30.

[0016] R １ From the viewpoint of reactivity, is preferably a linear or branched primary monovalent aliphatic hydrocarbon group, more preferably a linear or branched primary alkyl or alkenyl group, and even more preferably a linear primary alkyl group.

[0017] R １ The number of carbon atoms is not particularly limited, but may be 6 or more, 8 or more, 10 or more, or 12 or more, and from the viewpoint of reactivity, is preferably 36 or less, more preferably 22 or less, even more preferably 18 or less, and still more preferably 14 or less.

[0018] R ２From the viewpoint of reactivity, is preferably a linear or branched primary aliphatic hydrocarbon group, more preferably a linear or branched primary alkyl group or alkenyl group, and even more preferably a linear primary alkyl group.

[0019] R ２ The number of carbon atoms is not particularly limited, but may be 6 or more, 8 or more, 10 or more, or 12 or more, and from the viewpoint of reactivity, is preferably 36 or less, more preferably 22 or less, even more preferably 18 or less, and still more preferably 14 or less.

[0020] From the viewpoint of reactivity, A is preferably an ethylene group or a propylene group, more preferably an ethylene group. Similarly, from the viewpoint of reactivity, AO is preferably an ethyleneoxy group (EO) or a propyleneoxy group (PO), more preferably an ethyleneoxy group (EO).

[0021] From the viewpoint of reactivity, n is preferably 3 or more, and preferably 25 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less.

[0022] In the oxide production method of the present invention, the hydrophilicity of the organic compound affects reactivity, and the higher the hydrophilicity, the higher the reactivity between the Pt / Bi composite catalyst and the organic compound. That is, the higher the IOB value (balance value between inorganic and organic) IV / OV, calculated from the inorganic value (IV) and organic value (OV) of the organic conceptual diagram of the organic compound, the higher the reactivity. Therefore, from the viewpoint of high hydrophilicity, the organic compound is preferably a polyoxyalkylene alkyl ether, more preferably a polyoxyalkylene alkyl ether represented by the above general formula (2). From the viewpoint of reactivity, the IOB value based on the organic conceptual diagram of the organic compound is preferably 0.3 or more, more preferably 1 or more, and even more preferably 4 or more. The IOB value of the organic compound may be less than 5.

[0023] The method for producing an oxide of the present invention can obtain a carboxylic acid compound or a salt of a carboxylic acid compound as an oxide by subjecting the above-mentioned organic compound to a dehydrogenative oxidation reaction. Examples of the carboxylic acid compound or the salt of a carboxylic acid include a carboxylic acid compound or a salt of a carboxylic acid compound obtained by subjecting the above-mentioned aliphatic alcohol or polyoxyalkylene alkyl ether to a dehydrogenative oxidation reaction, and examples thereof include so-called ether carboxylates or salts thereof obtained by subjecting polyoxyalkylene alkyl ether to an oxidation reaction.

[0024] <Pt Supported on a Carrier> From the viewpoint of carrying out the reaction under conditions of a pH of less than 7, the carrier used for the Pt supported on a carrier is preferably a carrier selected from titania, zirconia, and activated carbon, and more preferably activated carbon. There are no particular limitations on the activated carbon, and any type of activated carbon can be used as long as it can adsorb and support Pt. Examples of activated carbon include vegetable activated carbon such as coconut shell activated carbon, mineral activated carbon such as coal-based activated carbon, and activated carbon made from pulp waste liquor, synthetic resin, and organic waste. There are also no particular limitations on the activation method, pore distribution, shape, etc. However, the reactivity differs. Coal-based activated carbon is more highly active than vegetable activated carbon and is therefore preferable. On the other hand, vegetable activated carbon is more preferable than coal-based activated carbon in terms of strength to prevent crushing during filtration.

[0025] There are no particular restrictions on the particle size of Pt supported on the support, but from the viewpoint of increasing the amount of Pt supported, it is preferably 1 nm or more, more preferably 3 nm or more, and from the viewpoint of increasing the dispersibility of Pt on the support surface, it is preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less.

[0026] The amount of Pt supported on the carrier, i.e., the amount of Pt supported relative to the total amount of the carrier and Pt, is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, still more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of the reactivity of the dehydrogenation oxidation reaction of organic compounds, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving the dispersibility of Pt on the carrier surface. Furthermore, Pt supported on a carrier can be prepared by known impregnation methods or precipitation methods, but commercially available products can also be used.

[0027] The amount of Pt supported on a carrier to be charged can be selected arbitrarily within a range in which a practical reaction rate can be obtained, depending on the reaction temperature or reaction pressure. When the reaction is carried out batchwise, from the viewpoint of reactivity, the amount is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less, relative to 100 parts by mass of the organic compound.

[0028] <Bi ion source> The Bi ion source is preferably water-insoluble from the viewpoint of improving the catalytic activity of the produced Pt / Bi composite catalyst and efficiently obtaining oxides. As the Bi ion source, bismuth nitrate pentahydrate (Bi(NO ３ ) ３ ・5H ２ O), bismuth oxide (Bi ２ O ３ ), bismuth basic carbonate ((BiO) ２ CO ３ ) and bismuth hydroxide (Bi(OH) ３ The catalytic activity of the resulting Pt / Bi composite catalyst varies depending on the Bi ion source used, and in the present invention, when bismuth oxide is used as the Bi ion source, a Pt / Bi composite catalyst with high catalytic activity is obtained, and an oxide of an organic compound can be efficiently obtained. Therefore, bismuth oxide is preferred as the Bi ion source.

[0029] From the viewpoint of the production efficiency of the catalyst and the production efficiency of the oxide of the organic compound, the amount of the Bi ion source to be charged is preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, even more preferably 0.05 part by mass or more, and is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, even more preferably 0.3 part by mass or less, relative to 100 parts by mass of the organic compound.

[0030] In the method for producing an oxide of the present invention, the mass ratio (atomic ratio) of the amount of Bi charged to Pt, Bi / Pt, is preferably 0.05 or more, more preferably 0.1 or more, from the viewpoint of improving the productivity of the product of the oxidation reaction, and is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, still more preferably 1.4 or less, still more preferably 1.2 or less, and still more preferably 1.0 or less.

[0031] When bismuth oxide is used as a Bi ion source, the reactivity of the Pt / Bi composite catalyst prepared varies depending on the amount of bismuth oxide added. Adding even a small amount of bismuth oxide improves the reactivity of the Pt / Bi composite catalyst prepared. The preferred amount of bismuth oxide added per 100 parts by mass of the organic compound is the same as the preferred amount of the Bi ion source described above.

[0032] <Water> The method for producing an oxide of the present invention is carried out in the presence of water, and preferred examples of water include ion-exchanged water, distilled water, and pure water.

[0033] The amount of water used is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and preferably 35 parts by mass or less, more preferably 30 parts by mass or less, relative to 100 parts by mass of the organic compound, from the viewpoints of improving productivity of the oxide of the organic compound and suppressing an increase in viscosity of the liquid phase.

[0034] The amount of water used is the total amount of the water charged, the water content of the Pt supported on the carrier, and the water content of the Bi ion source.

[0035] <Reaction Conditions> (pH During Reaction) In the oxide production method of the present invention, the minimum pH during the reaction is less than 7. By keeping the minimum pH during the reaction less than 7, the reaction system can be made acidic, the Bi ion source dissolves, Bi ions are easily produced, and Bi is prevented from precipitating independently from the Bi ions on a carrier such as activated carbon, and Bi is reduced and precipitated near Pt, creating a highly active structure. This is thought to significantly improve the reactivity of the reaction for producing a highly active Pt / Bi composite catalyst and the dehydrogenative oxidation reaction of an organic compound.

[0036] In the method for producing an oxide of the present invention, the minimum pH during the reaction can be adjusted to less than 7 by not adding an alkaline agent or the like to the reaction system, since the organic compound undergoes a dehydrogenation oxidation reaction to produce an oxide.

[0037] In the method for producing an oxide of the present invention, when Bi oxide is used as the Bi ion source, the pH is alkaline when the raw materials are charged, but as the reaction progresses and the amount of an organic compound oxide in the reaction system increases, the pH becomes acidic. From the viewpoint of improving the production efficiency of the Pt / Bi composite catalyst and the organic compound oxide, the minimum pH at the end of the reaction is preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less, and is preferably 1 or more, more preferably 1.5 or more, and even more preferably 2 or more.

[0038] (Reaction Temperature) The reaction temperature in the oxide production method of the present invention is preferably 50°C or higher, more preferably 60°C or higher, from the viewpoint of the reaction for producing a Pt / Bi composite catalyst and the reactivity of the dehydrogenation reaction of an organic compound, and is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 85°C or lower, from the viewpoint of the equipment load.

[0039] (Oxygen-Containing Gas) In the method for producing an oxide of the present invention, oxygen is preferably supplied to the reaction system from the viewpoint of dehydrogenation of an organic compound. The supply of oxygen can be carried out by circulating an oxygen-containing gas through the liquid phase. Examples of the oxygen-containing gas include oxygen gas and air, which contain oxygen. When using an oxygen-containing mixed gas, the gas used in combination with oxygen is preferably an inert gas such as helium, argon, or nitrogen, from the viewpoint of not affecting activity. The oxygen concentration in the oxygen-containing gas is preferably 10% by volume or more, more preferably 50% by volume or more, even more preferably 70% by volume or more, even more preferably 90% by volume or more, and even more preferably 100% by volume, from the viewpoint of productivity of the oxide.

[0040] (Reaction Pressure) In the oxide production method of the present invention, the reaction may be carried out under normal pressure or under increased pressure. From the viewpoint of reactivity, the reaction pressure is preferably 0.09 MPa or more, more preferably 0.10 MPa or more, in terms of absolute pressure, and from the viewpoint of equipment load, it is preferably 0.5 MPa or less, more preferably 0.2 MPa or less, and even more preferably 0.11 MPa or less. The reaction is preferably carried out under normal pressure.

[0041] <Oxide Purification> The oxide production method of the present invention may further include a step of purifying the resulting oxide after completion of the dehydrogenation oxidation reaction of the organic compound. In the oxide production method of the present invention, after completion of the oxidation reaction of the organic compound, the Pt / Bi composite catalyst can be removed from the reaction solution containing the oxide of the organic compound by, for example, pressure filtration, vacuum filtration, or the like. Since the oxide production method of the present invention can produce an oxide of the organic compound at a high production rate, the reaction solution containing the oxide of the organic compound can be used directly as a raw material for producing a cleaning agent, etc. Furthermore, if necessary, the organic compound can be obtained at a high concentration by extraction, distillation, or the like of the reaction solution containing the oxide of the organic compound.

[0042] [Another method for producing an oxide] Another method for producing an oxide of the present invention is a method for producing an oxide, which comprises dehydrogenating an organic compound having one primary hydroxyl group in the presence of a Pt / Bi composite catalyst, a Bi ion source, and water under conditions where the minimum pH during the reaction is less than 7, to obtain an oxide of the organic compound. According to this other method for producing an oxide of the present invention, an oxide of an organic compound can be produced at a high yield. In this other method for producing an oxide of the present invention, the Pt / Bi composite catalyst is the same as the Pt / Bi composite catalyst obtained by the above-mentioned method for producing an oxide or the Pt / Bi composite catalyst obtained by the method for producing a Pt / Bi catalyst described below.

[0043] The other oxide production method of the present invention preferably involves regeneration of the Pt / Bi composite catalyst. While the reason for the preferred regeneration of the Pt / Bi composite catalyst is unclear, it is believed to be as follows: Repeated use of the Pt / Bi composite catalyst in the production process for an organic compound oxide is thought to gradually leach out Bi, causing the catalyst structure to change and resulting in a decrease in catalytic activity. In the other oxide production method of the present invention, adding a Bi ion source together with the Pt / Bi composite catalyst reduces and deposits Bi on the Pt / Bi composite catalyst, replenishing the leached Bi and regenerating the Pt / Bi composite catalyst. Furthermore, it is thought that regeneration of the Pt / Bi composite catalyst promotes the dehydrogenation reaction of the organic compound, resulting in a high yield of the organic compound oxide. From the above, the other oxide production method of the present invention can involve regeneration of the Pt / Bi composite catalyst within the oxide production process. Therefore, separate equipment or processes for catalyst regeneration are not required, allowing for efficient production of organic compound oxides, offering significant advantages in terms of production efficiency and production costs.

[0044] Furthermore, in the oxide production method of the present invention and other oxide production methods, from the viewpoint of efficiently regenerating the Pt / Bi composite catalyst and improving the yield of the oxide of an organic compound, it is preferable to add a Bi ion source at the start of or during the dehydrogenation-oxidation reaction of an organic compound, and it is more preferable to add the Bi ion source during the reaction. Adding a Bi ion source to the system at the start of the reaction can easily suppress deterioration of the Pt / Bi composite catalyst and easily improve the yield of the oxide of an organic compound. Furthermore, adding a Bi ion source to the system during the reaction in accordance with the deterioration status of the Pt / Bi composite catalyst can regenerate the Pt / Bi composite catalyst, thereby suppressing a decrease in the efficiency of the dehydrogenation-oxidation reaction of an organic compound and easily improving the yield of the oxide of an organic compound. Furthermore, this method can also be a method that enables catalyst regeneration without re-preparing a high-performance Pt / Bi composite catalyst, addressing the issue of Bi elution and reduced catalytic activity when the catalyst is recycled.

[0045] [Method for Producing Pt / Bi Composite Catalyst] The method for producing a Pt / Bi composite catalyst of the present invention comprises mixing Pt supported on a carrier with a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting the resulting mixture under conditions where the minimum pH during the reaction is less than 7.

[0046] The method for producing a Pt / Bi composite catalyst of the present invention enables the production of a catalyst exhibiting high activity in the dehydrogenation-oxidation reaction of organic compounds. While the reason for this effect is unclear, it is presumed to be as follows. Conventional catalysts, such as Pt / Bi composite catalysts, are typically prepared by precipitating Pt and Bi by adding a reducing agent to a Pt ion source and a Bi ion source under alkaline conditions. However, this method results in segregation of Bi, which presumably results in low catalytic activity due to the low number of active structures effective in the dehydrogenation-oxidation reaction of organic compounds. In contrast, the method for producing a Pt / Bi composite catalyst of the present invention involves contacting Pt supported on a carrier such as a Pt / C catalyst with Bi ions under conditions where the minimum pH during the reaction is less than 7. This allows Bi to be uniformly reduced and precipitated on the Pt without the addition of a reducing agent, forming many active structures effective in the dehydrogenation-oxidation reaction of organic compounds. This is presumably responsible for the high catalytic activity.

[0047] Furthermore, in the method for producing a Pt / Bi composite catalyst of the present invention, from the viewpoint of producing a catalyst exhibiting high activity, preferably, a dehydrogenation-oxidation reaction of an organic compound having one primary hydroxyl group is accompanied in the reaction system, and more preferably, the dehydrogenation-oxidation reaction of the organic compound is accelerated. The reason why the dehydrogenation-oxidation reaction of the organic compound is preferably accompanied and more preferably accelerated is unclear, but is thought to be as follows: By mixing Pt supported on a carrier with a Bi ion source in the presence of the organic compound, a dehydrogenation-oxidation reaction of the organic compound is accompanied. This produces a small amount of oxide of the organic compound, forming an oxide-containing solution. This dissolves the Bi ion source, generating Bi ions, which are then reduced and precipitated on the Pt, producing a Pt / Bi composite catalyst in the system that is more active than a Pt catalyst. It is presumed that this accelerates the dehydrogenation reaction of the organic compound, resulting in a high yield of the oxide of the organic compound. From the above, it is believed that it is possible to produce a catalyst simultaneously in the process of producing an oxide, which does not require any separate equipment or process for producing a catalyst, and it is possible to efficiently produce an oxide of an organic compound, which has great advantages in terms of production efficiency and production costs.

[0048] According to the method for producing a Pt / Bi composite catalyst of the present invention, a carboxylic acid compound or a salt of a carboxylic acid compound, which is an oxide of the organic compound, can be obtained during the production of the Pt / Bi composite catalyst. Examples of the carboxylic acid compound or the salt of the carboxylic acid compound include the carboxylic acid compound or the salt of the carboxylic acid compound obtained by the dehydrogenation oxidation of the aforementioned aliphatic alcohol or polyoxyalkylene alkyl ether. Examples of the carboxylic acid compound include a fatty acid obtained by the dehydrogenation oxidation of an aliphatic alcohol, and an ether carboxylate obtained by the dehydrogenation oxidation of a polyoxyalkylene alkyl ether. Examples of the salt of the carboxylic acid compound include a neutral salt of the aforementioned fatty acid or ether carboxylate with an alkali metal hydroxide such as sodium or potassium.

[0049] In the method for producing a Pt / Bi composite catalyst of the present invention, preferred examples of the organic compound having one primary hydroxyl group include aliphatic alcohols and polyoxyalkylene alkyl ethers, and those listed as examples of the organic compound having one primary hydroxyl group in the method for producing an oxide of the present invention can be suitably used. From the viewpoint of the oxide production rate, the organic compound having one primary hydroxyl group is preferably a highly hydrophilic organic compound. Furthermore, the organic compound having one primary hydroxyl group is preferably a polyoxyalkylene alkyl ether, more preferably a polyoxyalkylene alkyl ether represented by the above general formula (2).

[0050] In the method for producing a Pt / Bi composite catalyst of the present invention, the reaction may be further carried out in the presence of an oxide of the organic compound. Examples of the oxide of the organic compound include carboxylic acid compounds or salts of carboxylic acid compounds in which the hydroxyl groups of the organic compounds exemplified in the method for producing an oxide of the present invention are oxidized.

[0051] Examples of Pt supported on a carrier used in the method for producing a Pt / Bi composite catalyst of the present invention include those similar to those of Pt supported on a carrier used in the method for producing an oxide of the present invention, and the preferred ranges are also similar. The carrier for Pt supported on a carrier used in the method for producing a Pt / Bi composite catalyst of the present invention is preferably activated carbon. Examples of activated carbon include those similar to those used in the method for producing an oxide of the present invention, and the preferred ranges are also similar.

[0052] In the method for producing a Pt / Bi composite catalyst of the present invention, the Bi ion source is preferably water-insoluble from the viewpoint of improving the catalytic activity of the produced Pt / Bi composite catalyst. Examples of the Bi ion source include the same Bi ion sources as those used in the method for producing an oxide of the present invention.

[0053] The method for producing a Pt / Bi composite catalyst of the present invention is carried out in the presence of water. Examples of water include the same water as that used in the method for producing an oxide of the present invention, and the preferred range is also the same.

[0054] In the method for producing a Pt / Bi composite catalyst of the present invention, the minimum pH during the reaction is less than 7. By keeping the minimum pH during the reaction less than 7, the reaction system can be made acidic, the Bi ion source dissolves, Bi ions are easily produced, and the precipitation of Bi alone from the Bi ions onto a carrier such as activated carbon is suppressed, allowing Bi to be reduced and precipitated near Pt, creating a highly active structure. This is thought to significantly improve the reactivity of the reaction for producing a highly active Pt / Bi composite catalyst and the dehydrogenative oxidation reaction of organic compounds. The pH conditions during the reaction are the same as the preferred range of pH during the reaction in the method for producing an oxide of the present invention.

[0055] The reaction temperature in the method for producing a Pt / Bi composite catalyst of the present invention is the same as that in the method for producing an oxide of the present invention.

[0056] In the method for producing a Pt / Bi composite catalyst of the present invention, it is preferable to supply oxygen to the reaction system from the viewpoint of dehydrogenation of an organic compound. The supply of oxygen can be carried out by circulating an oxygen-containing gas through the liquid phase. Examples of the oxygen-containing gas include the same oxygen-containing gases as those used in the method for producing an oxide of the present invention, and the preferred ranges are also the same.

[0057] The reaction pressure in the method for producing a Pt / Bi composite catalyst of the present invention is the same as that in the method for producing an oxide of the present invention.

[0058] <Recovery of catalyst> The catalyst produced by the method for producing a Pt / Bi composite catalyst of the present invention can be recovered by separating it from the reaction liquid. Recovery methods include, for example, pressure filtration, vacuum filtration, etc. The recovered Pt / Bi composite catalyst may be washed, but can also be used as a catalyst for the dehydrogenation oxidation reaction of organic compounds without washing. After recovery, the catalyst produced by the method for producing a Pt / Bi composite catalyst of the present invention can be reused as a catalyst for the dehydrogenation oxidation reaction of the aforementioned organic compounds.

[0059] [Another method for producing a Pt / Bi composite catalyst] Another method for producing a Pt / Bi composite catalyst of the present invention is a method for producing a Pt / Bi composite catalyst, which comprises mixing a Pt / Bi composite catalyst and a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting the catalyst under conditions where the minimum pH during the reaction is less than 7. According to this method for producing a Pt / Bi composite catalyst of the present invention, a catalyst exhibiting high activity in the dehydrogenation reaction of organic compounds can be produced. In this method for producing a Pt / Bi composite catalyst of the present invention, the Pt / Bi composite catalyst is the same as the Pt / Bi composite catalyst described above or the Pt / Bi composite catalyst obtained by the oxide production method described below.

[0060] In another method for producing a Pt / Bi composite catalyst of the present invention, a Bi ion source is preferably added at the start of the reaction or during the reaction to regenerate the Pt / Bi composite catalyst, and more preferably added during the reaction to regenerate the Pt / Bi composite catalyst. Adding a Bi ion source to the system at the start of the reaction can suppress deterioration of the Pt / Bi composite catalyst and improve the yield of the oxide of the organic compound. Furthermore, adding a Bi ion source to the system during the reaction can regenerate the Pt / Bi composite catalyst, thereby suppressing a decrease in the efficiency of the dehydrogenation oxidation reaction of the organic compound and improving the yield of the oxide of the organic compound.

[0061] Although the reason why adding a Bi ion source at the start of or during the reaction leads to regeneration of the Pt / Bi composite catalyst is unclear, we believe the following: It is believed that repeated use of the Pt / Bi composite catalyst in the production of an organic compound oxide results in gradual elution of Bi, which changes the catalyst structure and reduces catalytic activity. In the other production method of the Pt / Bi composite catalyst of the present invention, adding a Bi ion source together with the Pt / Bi composite catalyst reduces and deposits Bi on the Pt / Bi composite catalyst, replenishing the eluted Bi and regenerating the Pt / Bi composite catalyst. Furthermore, it is believed that the regeneration of the Pt / Bi composite catalyst promotes the dehydrogenation reaction of the organic compound, resulting in a high yield of the organic compound oxide. As described above, the other method for producing a Pt / Bi composite catalyst of the present invention can accompany the regeneration of the Pt / Bi composite catalyst within the oxide production process, and therefore does not require any separate equipment or process for catalyst regeneration, making it possible to efficiently produce a Pt / Bi composite catalyst, which has significant advantages in terms of production efficiency and production costs.

[0062] [Oxide of Organic Compound] The oxide of an organic compound obtained by the method for producing an oxide and the method for producing a Pt / Bi composite catalyst of the present invention can be used in a wide range of fields, such as detergents, fabric softeners, wetting agents, dyeing aids, etc. Furthermore, because it has excellent foaming power and detergency and is less irritating to the skin, it can be suitably used in products that come into contact with human skin for long periods of time, such as shampoos, body soaps, kitchen detergents, cosmetic compositions, and fragrances.

[0063] According to the oxide production method and Pt / Bi composite catalyst production method of the present invention, organic compound oxides can be obtained at a high production rate. In the oxide production method and Pt / Bi composite catalyst production method of the present invention, the production rate of organic compound oxides after 24 hours of reaction is preferably 75% or more, more preferably 77% or more, even more preferably 80% or more, and even more preferably 83% or more. Furthermore, the production rate of organic compound oxides after 3 hours of reaction is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. In the present invention, the production rate of organic compound oxides can be determined in the same manner as the calculation method for the carboxylic acid compound production rate in the examples described later.

[0064] [Pt / Bi Composite Catalyst] The Pt / Bi composite catalyst of the present invention can be obtained by the oxide production method and Pt / Bi composite catalyst production method of the present invention described above. The Pt / Bi composite catalyst of the present invention is suitable for use in a reaction for producing an oxide of an organic compound by dehydrogenating an organic compound having one primary hydroxyl group as described above. That is, the present invention also relates to a method for producing an oxide, in which an organic compound having one primary hydroxyl group is dehydrogenated in the presence of the Pt / Bi composite catalyst to obtain an oxide of the organic compound. The oxide production method of the present invention preferably includes water as a solvent, and supplies oxygen to a composition containing an organic compound having one primary hydroxyl group in the presence of the Pt / Bi composite catalyst to dehydrogenate the organic compound having one primary hydroxyl group.

[0065] From the viewpoint of improving the productivity of the oxidation reaction product, the amount of Bi supported in the Pt / Bi composite catalyst is preferably 0.01 mass% or more, more preferably 0.5 mass% or more, and is preferably 10 mass% or less, more preferably 5 mass% or less, even more preferably 3.5 mass% or less, and still more preferably 2.5 mass% or less.

[0066] In the Pt / Bi composite catalyst of the present invention, the mass ratio (atomic ratio) of Bi to Pt, Bi / Pt, is preferably 0.05 or more, more preferably 0.1 or more, from the viewpoint of improving the productivity of the oxidation reaction product, and is preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.0 or less, and still more preferably 0.5 or less.

[0067] In addition to the above-described embodiments, the present invention further discloses the following methods for producing an oxide and a method for producing a Pt / Bi composite catalyst. <1> A method for producing an oxide, comprising: subjecting an organic compound having one primary hydroxyl group to a dehydrogenative oxidation reaction in the presence of Pt supported on a carrier, a Bi ion source, and water, under conditions where the minimum pH during the reaction is less than 7, to obtain an oxide of the organic compound. <2> A method for producing an oxide, comprising subjecting an organic compound having one primary hydroxyl group to a dehydrogenative oxidation reaction in the presence of a Pt / Bi composite catalyst, a Bi ion source, and water, under conditions where the minimum pH during the reaction is less than 7, to obtain an oxide of the organic compound. <3> A method for producing an oxide according to <1> or <2>, which involves the preparation of a Pt / Bi composite catalyst. <4> A method for producing an oxide according to any one of <1> to <3>, in which the Bi ion source is water-insoluble. <5> A method for producing an oxide according to any one of <1> to <4>, in which the Bi ion source is bismuth oxide. <6> The method for producing an oxide according to any one of <1> to <5>, wherein the amount of the Bi ion source charged is preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, even more preferably 0.05 part by mass or more, and preferably 1 part by mass or less, more preferably 0.5 part by mass or less, and even more preferably 0.3 part by mass or less, relative to 100 parts by mass of the organic compound. <7> The method for producing an oxide according to any one of <1> to <6>, wherein the mass ratio (atomic ratio) of Bi to Pt charged, Bi / Pt, is preferably 0.05 or more, more preferably 0.1 or more, and preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, still more preferably 1.4 or less, still more preferably 1.2 or less, and still more preferably 1.0 or less.

[0068] <8> The method for producing an oxide according to any one of <1> to <7>, wherein the organic compound is an aliphatic alcohol or a polyoxyalkylene alkyl ether. <9> The method for producing an oxide according to <8>, wherein the aliphatic alcohol or the polyoxyalkylene alkyl ether is preferably one or more compounds represented by the following general formula (1) or (2): １ O-H (1) In general formula (1), R １ is a monovalent aliphatic hydrocarbon group having 2 to 40 carbon atoms. ２ O-(AO) ｎ -H (2) In general formula (2), R ２ represents a monovalent aliphatic hydrocarbon group having from 2 to 40 carbon atoms, A represents an alkanediyl group having from 2 to 4 carbon atoms, AO represents an alkyleneoxy group, and n represents the average number of moles of alkyleneoxy groups added, which is from 1 to 30. １ is preferably a linear or branched primary monovalent aliphatic hydrocarbon group, more preferably a linear or branched primary alkyl or alkenyl group, and even more preferably a linear primary alkyl group. １ <12> The method for producing an oxide according to <9> or <10>, wherein the number of carbon atoms in R in the general formula (2) is preferably 6 or more, more preferably 8 or more, even more preferably 10 or more, still more preferably 12 or more, and is preferably 36 or less, more preferably 22 or less, even more preferably 18 or less, still more preferably 14 or less. ２ is preferably a linear or branched primary aliphatic hydrocarbon group, more preferably a linear or branched primary alkyl or alkenyl group, and even more preferably a linear primary alkyl group. ２The method for producing an oxide according to any one of <9> to <12>, wherein the number of carbon atoms in the general formula (2) is preferably 6 or more, more preferably 8 or more, even more preferably 10 or more, still more preferably 12 or more, and preferably 36 or less, more preferably 22 or less, even more preferably 18 or less, and still more preferably 14 or less. <14> The method for producing an oxide according to any one of <9> to <13>, wherein A in the general formula (2) is preferably an ethylene group or a propylene group, more preferably an ethylene group. <15> The method for producing an oxide according to any one of <9> to <14>, wherein AO in the general formula (2) is preferably an ethyleneoxy group (EO) or a propyleneoxy group (PO), more preferably an ethyleneoxy group (EO). <16> The method for producing an oxide according to any one of <9> to <15>, wherein n in the general formula (2) is preferably 3 or more, and preferably 25 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less. <17> The method for producing an oxide according to any one of <9> to <16>, wherein the organic compound is preferably a polyoxyalkylene alkyl ether, more preferably a polyoxyalkylene alkyl ether represented by the general formula (2).

[0069] <18> The method for producing an oxide according to any one of <1> to <17>, wherein the oxide of an organic compound is a carboxylic acid compound or a salt of a carboxylic acid compound. <19> The method for producing an oxide according to <18>, wherein the carboxylic acid compound or the salt of a carboxylic acid is an ether carboxylate or a salt thereof obtained by an oxidation reaction of a polyoxyalkylene alkyl ether. <20> The method for producing an oxide according to any one of <1> to <19>, wherein the support is activated carbon. <21> The method for producing an oxide according to any one of <1> to <20>, wherein the particle size of Pt supported on the support is preferably 1 nm or more, more preferably 3 nm or more, and preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less. <22> The method for producing an oxide according to any one of <1> to <21>, wherein the amount of Pt supported on the support, i.e., the amount of Pt supported relative to the total amount of the support and Pt, is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, still more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. <23> The method for producing an oxide according to any one of <1> to <22>, wherein the amount of Pt supported on the support is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less, relative to 100 parts by mass of the organic compound. <24> The method for producing an oxide according to any one of <1> to <23>, wherein the amount of water is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and preferably 35 parts by mass or less, more preferably 30 parts by mass or less, relative to 100 parts by mass of the organic compound.

[0070] <25> The method for producing an oxide according to any one of <1> to <24>, wherein no alkali agent or the like is added to the reaction system. <26> The method for producing an oxide according to any one of <1> to <25>, wherein the minimum pH at the end of the reaction in the method for producing an oxide is preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and preferably 1 or more, more preferably 1.5 or more, and even more preferably 2 or more. <27> The method for producing an oxide according to any one of <1> to <26>, wherein the reaction temperature in the method for producing an oxide is preferably 50°C or more, more preferably 60°C or more, and preferably 100°C or less, more preferably 90°C or less, and even more preferably 85°C or less. <28> The method for producing an oxide according to any one of <1> to <27>, wherein oxygen is preferably supplied into the reaction system in the method for producing an oxide. <29> The method for producing an oxide according to <28>, wherein the supply of oxygen is carried out by circulating an oxygen-containing gas through a liquid phase. <30> The method for producing an oxide according to <29>, wherein the oxygen-containing gas is oxygen gas or air. <31> The oxygen concentration in the oxygen-containing gas is preferably 10 vol% or more, more preferably 50 vol% or more, even more preferably 70 vol% or more, still more preferably 90 vol% or more, and still more preferably 100 vol%. <32> The method for producing an oxide according to any one of <1> to <31>, wherein the reaction pressure, in terms of absolute pressure, is preferably 0.09 MPa or more, more preferably 0.10 MPa or more, and preferably 0.5 MPa or less, more preferably 0.2 MPa or less, and still more preferably 0.11 MPa or less. <33> The method for producing an oxide according to any one of <1> to <32>, wherein the reaction is preferably carried out under normal pressure.

[0071] <34> The method for producing an oxide according to any one of <1> to <33>, wherein a Bi ion source is added at the start of or during the dehydrogenation oxidation reaction. <35> The method for producing an oxide according to any one of <1> to <34>, further comprising a step of purifying the obtained oxide after completion of the dehydrogenation oxidation reaction of the organic compound. <36> The method for producing an oxide according to <35>, wherein in the step of purifying the obtained oxide, the Pt / Bi composite catalyst is removed from the reaction solution containing the oxide of the organic compound by pressure filtration or vacuum filtration after completion of the oxidation reaction of the organic compound.

[0072] <37> A method for producing a Pt / Bi composite catalyst, comprising mixing Pt supported on a carrier with a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting them under conditions where the minimum pH during the reaction is less than 7. <38> A method for producing a Pt / Bi composite catalyst, comprising mixing a Pt / Bi composite catalyst and a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting them under conditions where the minimum pH during the reaction is less than 7. <39> A method for producing a Pt / Bi composite catalyst according to <38>, comprising adding a Bi ion source at the start of the reaction or during the reaction to regenerate the Pt / Bi composite catalyst. <40> A method for producing a Pt / Bi composite catalyst according to any of <37> to <39>, wherein a dehydrogenation reaction of the organic compound is also involved.

[0073] <41> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <40>, wherein the organic compound is an aliphatic alcohol or a polyoxyalkylene alkyl ether. <42> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <41>, wherein the aliphatic alcohol or the polyoxyalkylene alkyl ether is preferably one or more species represented by the following general formula (1) or general formula (2): １ O-H (1) In general formula (1), R １ is a monovalent aliphatic hydrocarbon group having 2 to 40 carbon atoms. ２ O-(AO) ｎ -H (2) In general formula (2), R ２represents a monovalent aliphatic hydrocarbon group having from 2 to 40 carbon atoms, A represents an alkanediyl group having from 2 to 4 carbon atoms, AO represents an alkyleneoxy group, and n represents the average number of moles of alkyleneoxy groups added, which is from 1 to 30. <43> R in the above general formula (1) １ <44> The method for producing a Pt / Bi composite catalyst of an oxide according to <42>, wherein R in the general formula (1) is preferably a linear or branched primary monovalent aliphatic hydrocarbon group, more preferably a linear or branched primary alkyl or alkenyl group, and even more preferably a linear primary alkyl group. １ <45> The method for producing a Pt / Bi composite catalyst according to <42> or <43>, wherein the number of carbon atoms in R in the general formula (2) is preferably 6 or more, more preferably 8 or more, even more preferably 10 or more, still more preferably 12 or more, and is preferably 36 or less, more preferably 22 or less, even more preferably 18 or less, still more preferably 14 or less. ２ <46> The method for producing a Pt / Bi composite catalyst according to any one of <42> to <44>, wherein R in the general formula (2) is preferably a linear or branched primary aliphatic hydrocarbon group, more preferably a linear or branched primary alkyl or alkenyl group, and even more preferably a linear primary alkyl group. ２The method for producing a Pt / Bi composite catalyst according to any one of <42> to <45>, wherein the number of carbon atoms in the aryl group is preferably 6 or more, more preferably 8 or more, even more preferably 10 or more, still more preferably 12 or more, and preferably 36 or less, more preferably 22 or less, even more preferably 18 or less, and still more preferably 14 or less. <47> The method for producing a Pt / Bi composite catalyst according to any one of <42> to <46>, wherein A in the general formula (2) is preferably an ethylene group or a propylene group, more preferably an ethylene group. <48> The method for producing a Pt / Bi composite catalyst according to any one of <42> to <47>, wherein AO in the general formula (2) is preferably an ethyleneoxy group (EO) or a propyleneoxy group (PO), more preferably an ethyleneoxy group (EO). <49> A method for producing a Pt / Bi composite catalyst according to any one of <42> to <48>, wherein n in the general formula (2) is preferably 3 or more and preferably 25 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less. <50> A method for producing a Pt / Bi composite catalyst according to any one of <42> to <49>, wherein the organic compound is preferably a polyoxyalkylene alkyl ether, more preferably a polyoxyalkylene alkyl ether represented by the general formula (2).

[0074] <51> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <50>, wherein the reaction is further carried out in the presence of an oxide of the organic compound. <52> A method for producing a Pt / Bi composite catalyst according to <51>, wherein the oxide of the organic compound is a carboxylic acid compound or a salt of a carboxylic acid compound. <53> A method for producing a Pt / Bi composite catalyst according to <52>, wherein the carboxylic acid compound or the salt of the carboxylic acid compound is any one of a fatty acid obtained by dehydrogenative oxidation of an aliphatic alcohol, an ether carboxylate obtained by dehydrogenative oxidation of a polyoxyalkylene alkyl ether, and a neutralized salt of either of these with an alkali metal hydroxide such as sodium or potassium.

[0075] <54> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <53>, wherein the Bi ion source is water-insoluble. <55> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <54>, wherein the Bi ion source is bismuth oxide. <56> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <55>, wherein the amount of the Bi ion source charged is preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, even more preferably 0.05 part by mass or more, and preferably 1 part by mass or less, more preferably 0.5 part by mass or less, even more preferably 0.3 part by mass or less, relative to 100 parts by mass of the organic compound. <57> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <56>, wherein the mass ratio (atomic ratio) of the amount of Bi charged to the amount of Pt, Bi / Pt, is preferably 0.05 or more, more preferably 0.1 or more, and preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, still more preferably 1.4 or less, still more preferably 1.2 or less, and still more preferably 1.0 or less.

[0076] <58> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <57>, wherein the support is activated carbon. <59> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <58>, wherein the particle size of the Pt supported on the support is preferably 1 nm or more, more preferably 3 nm or more, and preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less. <60> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <59>, wherein the amount of Pt supported on the support, i.e., the amount of Pt supported relative to the total amount of the support and Pt, is preferably 0.1 mass% or more, more preferably 1 mass% or more, even more preferably 2 mass% or more, still more preferably 3 mass% or more, still more preferably 5 mass% or more, and preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 10 mass% or less. <61> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <60>, wherein the amount of Pt supported on the carrier is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less, per 100 parts by mass of the organic compound.

[0077] <62> The method for producing a Pt / Bi composite catalyst according to any one of <37> to <61>, wherein the amount of water is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and preferably 35 parts by mass or less, more preferably 30 parts by mass or less, per 100 parts by mass of the organic compound.

[0078] <63> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <62>, wherein the minimum pH at the end of the reaction in the method for producing a Pt / Bi composite catalyst is preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and preferably 1 or more, more preferably 1.5 or more, and even more preferably 2 or more. <64> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <63>, wherein no alkaline agent or the like is added to the reaction system. <65> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <64>, wherein the reaction temperature in the method for producing a Pt / Bi composite catalyst is preferably 50°C or more, more preferably 60°C or more, and preferably 100°C or less, more preferably 90°C or less, and even more preferably 85°C or less. <66> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <65>, wherein oxygen is preferably supplied to the reaction system in the method for producing a Pt / Bi composite catalyst. <67> A method for producing a Pt / Bi composite catalyst according to <66>, wherein oxygen is supplied by passing an oxygen-containing gas through the liquid phase. <68> A method for producing a Pt / Bi composite catalyst according to <67>, wherein the oxygen-containing gas is oxygen gas or air. <69> The oxygen concentration in the oxygen-containing gas is preferably 10% by volume or more, more preferably 50% by volume or more, even more preferably 70% by volume or more, still more preferably 90% by volume or more, and still more preferably 100% by volume. <67> or <68> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <69>, wherein the reaction pressure, in terms of absolute pressure, is preferably 0.09 MPa or more, more preferably 0.10 MPa or more, and preferably 0.5 MPa or less, more preferably 0.2 MPa or less, and still more preferably 0.11 MPa or less. <71> A method for producing a Pt / Bi composite catalyst according to any one of <37> to <70>, wherein the reaction is preferably carried out under normal pressure. <72> A method for producing an oxide, comprising dehydrogenating an organic compound in the presence of the Pt / Bi composite catalyst obtained by the method for producing a Pt / Bi composite catalyst according to any one of <37> to <71>, to obtain an oxide of the organic compound.

[0079] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Each property value was measured and evaluated by the following methods.

[0080] [Production of Pt / Bi composite catalyst and carboxylic acid compound] Example 1 A 500 mL five-neck flask equipped with a reflux tube, a dissolved oxygen concentration meter (manufactured by METTLER TOLEDO), a mechanical stirrer (manufactured by IWAKI Corporation, equipped with a glass stirring rod fitted with a crescent-shaped stirring blade (blade width 7.5 cm × height 2.2 cm × thickness 0.4 cm)), a glass temperature-controlling holder, and a glass tube for gas introduction was charged with the following raw materials, etc. (Charged raw materials, etc.) Organic compound: AE1 (a polyoxyalkylene alkyl ether in which an average of 3.6 mol of ethylene oxide has been added to 1 mol of lauryl alcohol): 100 parts by mass (200 g) was charged. Pt supported on a carrier: 5% Pt / C (manufactured by Evonik, C: charcoal, moisture content: 59.9% by mass): 4.90 parts by mass (24.45 g) of solids excluding moisture were charged. Bi ion source: bismuth oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 0.11 parts by mass (0.219 g) were charged. Water: Ion-exchanged water (35.35 g) was charged so that the total weight, including the moisture content of the 5% Pt / C, was 25 parts by mass.

[0081] Next, under a nitrogen flow, the five-neck flask was immersed in a water bath, and the charged raw materials and the like were heated to 80° C. while being stirred at 600 rpm. After the temperature reached 80° C., the nitrogen flow was stopped, and oxygen was bubbled through the charged raw materials and the like at 60 mL / min, and the reaction was carried out under normal pressure for 24 hours.

[0082] The reaction was carried out in divided portions every few hours. When the reaction was temporarily stopped, the reaction temperature was lowered to room temperature, oxygen bubbling was stopped, nitrogen was introduced, and the reaction was stopped by maintaining the dissolved oxygen concentration at 0 ppm for 1 hour. When the reaction was restarted, the temperature was raised to 80°C while stirring at 600 rpm under nitrogen flow, then the nitrogen flow was stopped, and oxygen was introduced at 60 mL / min to start the reaction.

[0083] After the reaction for 24 hours, the oxygen bubbling was stopped and nitrogen was circulated. The dissolved oxygen concentration was maintained at 0 ppm for 1 hour, and then the mixture was filtered using a pressure filter at a temperature of 80°C and nitrogen at 4 kgf / cm. ２ The reaction liquid was filtered under pressure by injecting the pressure into the reaction vessel, and the reaction liquid and the catalyst were separated.

[0084] During the reaction, the reaction solution was sampled every hour, and the carboxylic acid compound production rate was determined by the method described below. The carboxylic acid compound production rates are summarized in Tables 1 to 4. (Calculation of carboxylic acid compound production rate) A mixed solution of 60 mL of acetone and 10 mL of ion-exchanged water was added to 0.3 g of the sampled reaction solution and stirred to prepare a measurement sample. The measurement sample was titrated with a 0.05 mol / L ethanolic potassium hydroxide aqueous solution to measure the neutralization point. The measured acid value of the reaction solution was calculated from the determined neutralization point, and the carboxylic acid compound production rate was calculated using the following formula: Carboxylic acid compound production rate (%) = (measured acid value / theoretical acid value) × 100. Here, the theoretical acid value and measured acid value were as follows. (1) Calculation of theoretical acid value: The OHV (hydroxyl value) of organic compound (AE1) was calculated to be 162 mg KOH / g. Furthermore, from the molecular weight of the carboxylic acid compound obtained by oxidizing the molecular weight of organic compound (AE1), the acid value (theoretical acid value) when 100% of the carboxylic acid compound is produced in the reaction is 156 mg KOH / g. (2) Calculation of actual acid value: The actual acid value was calculated from the determined neutralization point using the following formula: Actual acid value (mg KOH / g) = Titration amount of potassium hydroxide aqueous solution (mL) × 56.11 (g / mol) × 0.05 (mol / L) / Sampling amount (g) / 0.7692 (mass ratio of raw materials in the reaction solution).

[0085] Examples 2 and 3 The reactions of Examples 2 and 3 were carried out in the same manner as Example 1, except that the amount of bismuth oxide used as the Bi ion source was changed as shown in Table 1. Table 1 summarizes the carboxylic acid compound production rate after 24 hours of reaction. Example 4 The reaction of Example 4 was carried out in the same manner as Example 1, except that the Bi ion source was changed to 0.23 parts by mass of bismuth nitrate pentahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as shown in Table 1. Table 1 summarizes the carboxylic acid compound production rate after 24 hours of reaction. Example 5 The reaction of Example 5 was carried out in the same manner as Example 1, except that the type of organic compound was changed to K2098 (Kalcol 2098 (lauryl alcohol), manufactured by Kao Corporation) as shown in Table 2. The OHV of K2098 was 301 mg KOH / g, and the theoretical acid value of its oxidation product (carboxylic acid compound) was 280 mg KOH / g. Table 2 summarizes the carboxylic acid compound production rate after 7 hours of reaction. Example 6 The reaction of Example 6 was carried out in the same manner as in Example 1, except that the type of organic compound was changed to AE2 (a polyoxyalkylene alkyl ether obtained by adding an average of 9 mol of ethylene oxide to 1 mol of 1-octanol) as shown in Table 2, and the reaction time was changed to 7 hours. The OHV of AE2 was 107 mg KOH / g, and the theoretical acid value of its oxidation product (carboxylic acid compound) was 104 mg KOH / g. Table 2 summarizes the carboxylic acid compound production rate after 7 hours of reaction. Comparative Example 1 The reaction of Comparative Example 1 was carried out in the same manner as in Example 1, except that no Bi ion source was added as shown in Table 1. Table 1 summarizes the carboxylic acid compound production rate after 24 hours of reaction. Comparative Example 2 The reaction of Comparative Example 2 was carried out in the same manner as in Example 1, except that a pH meter (manufactured by Nisshin Rika Co., Ltd.) was attached to the reaction vessel, and a 48% aqueous sodium hydroxide solution (manufactured by Kanto Chemical Co., Ltd.) was added as an alkaline agent to maintain a constant pH of 7.0 during the reaction. The carboxylic acid compound production rate was calculated by the following method, and the carboxylic acid compound production rate after 3 hours of reaction is summarized in Table 3. (Calculation of carboxylic acid compound production rate when an alkaline agent was added) 0.5 g of 6 M hydrochloric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 1 g of the sampled reaction solution, and the mixture was mixed well and then filtered with a syringe.The mixture was then left to stand until the oil and water were separated, to which 1 mL of a methylation reagent (reagent name "TMSI-H", manufactured by GL Science) was added, and the mixture was reacted at 70°C for 10 minutes. The mixture was then syringe filtered and analyzed by GC (gas chromatography). (GC measurement conditions) GC apparatus: Agilent Technologies 6850 (model number: Agilent 19091A-102E, manufactured by Agilent Technologies) Column: Ultra 1 Methyl Siloxane (25.0 m x 200 μm x 0.33 μm) Injection temperature: 300°C Detector temperature: 300°C Temperature program: Hold at 100°C for 5 minutes, then heat to 300°C at a rate of 5°C / min (total 45 minutes), then hold at 300°C for a further 40 minutes (total 90-minute program) Injection volume: 1.0 μL Split Ratio 25.0:1 Total flow 28.2 mL / min (gas: He) Comparative Example 3 The reaction was carried out in the same manner as in Comparative Example 2, except that the reaction time was set to 9 hours while adding a 48% aqueous sodium hydroxide solution (manufactured by Kanto Chemical Co., Inc.) as an alkaline agent so that the pH during the reaction was constant at 12.0. The carboxylic acid compound production rate was calculated using the method described in Comparative Example 2, and the carboxylic acid compound production rate after three hours of reaction is summarized in Table 3. Reference Example 1 The reaction of Reference Example 1 was carried out in the same manner as in Example 1, except that the catalyst separated and recovered from the reaction solution after completion of the reaction in Example 1 was charged instead of the Pt and Bi ion sources supported on a carrier, and the reaction time was set to 17 hours. The total amount of catalyst recovered in Example 1 was 17.80 g. The breakdown of the composition contained in the recovered catalyst was calculated to be 10 g of 5% Pt / C and bismuth oxide in total, 1.56 g of water, and 6.24 g of organic compounds (unreacted AE1 and carboxylic acid compounds) from the amounts charged in Example 1. Table 4 summarizes the carboxylic acid compound production rates after 17 hours of reaction.

[0086]

[0087]

[0088]

[0089]

[0090] As can be seen from Tables 1 to 4, the Pt / Bi composite catalyst obtained by mixing Pt and Bi ion sources supported on a carrier in the presence of an organic compound having one primary hydroxyl group and reacting under conditions where the minimum pH during the reaction was less than 7 showed a high carboxylic acid compound production rate at all reaction times, and the oxide of the target organic compound was efficiently obtained. Furthermore, Reference Example 1, in which the catalyst of Example 1 was separated and recovered and then used again in the oxidation reaction of an organic compound, also showed a high carboxylic acid compound production rate. On the other hand, the Pt / Bi composite catalyst of Comparative Example 1, in which no Bi ion source was added, produced only about 74% carboxylic acid compound at 24 hours, and the oxide of the target organic compound could not be efficiently obtained. Furthermore, the Pt / Bi composite catalysts of Comparative Examples 2 and 3, in which an alkaline agent was added during the reaction and the minimum pH during the reaction was 7 or higher, produced carboxylic acid compound production rates of 16.7% and 5.4%, respectively, at the third hour of reaction, which was lower than the 37.9% carboxylic acid compound production rate at the third hour of reaction in Example 1, resulting in poor reaction efficiency in the oxidation reaction of the organic compound. The production rate of carboxylic acid compounds after 17 hours of reaction in Reference Example 1 was 91.3%, which was higher than the production rate of 81.6% after 17 hours of reaction in Example 1. This is thought to be because the catalyst used in Reference Example 1 was a catalyst separated and recovered from the catalyst in Example 1, and therefore a highly active Pt—Bi / C catalyst was used that was presumed to have already been produced in the system, so there was no time for catalyst production in the system and the oxidation reaction of the organic compounds began immediately after the start of the reaction in Reference Example 1.

[0091] The oxide production method of the present invention can efficiently produce an oxide of an organic compound in the presence of Pt and Bi ion sources supported on a carrier, and can also involve the production of a Pt / Bi composite catalyst. Therefore, separate catalyst production equipment and processes are not required, and organic compound oxides can be efficiently produced. The resulting organic compound oxides can be used in a wide range of applications, such as detergents, fabric softeners, wetting agents, and dyeing aids. Furthermore, the Pt / Bi composite catalyst production method of the present invention can produce a catalyst that exhibits high activity in the dehydrogenation-oxidation reaction of an organic compound, even in the presence of an organic compound that serves as the oxide raw material, and can also involve the oxidative-dehydrogenation reaction of the organic compound. Therefore, separate catalyst production equipment and processes are not required, and organic compound oxides can be efficiently produced. The resulting Pt / Bi composite catalyst can be suitably used in the reaction of dehydrogenating an organic compound to produce the organic compound oxide.

Claims

1. A method for producing an oxide, comprising dehydrogenating and oxidizing an organic compound having one primary hydroxyl group in the presence of Pt supported on a carrier, a Bi ion source, and water under the condition that the minimum value of the pH during the reaction is less than 7 to obtain an oxide of the organic compound.

2. The method for producing an oxide according to claim 1, which involves the preparation of a Pt / Bi composite catalyst.

3. The method for producing an oxide according to claim 1 or 2, wherein the Bi ion source is water-insoluble.

4. The method for producing an oxide according to any one of claims 1 to 3, wherein the Bi ion source is bismuth oxide.

5. The method for producing an oxide according to any one of claims 1 to 4, wherein the organic compound is an aliphatic alcohol or a polyoxyalkylene alkyl ether.

6. The method for producing an oxide according to any one of claims 1 to 5, wherein the oxide of the organic compound is a carboxylic acid compound or a salt of a carboxylic acid compound.

7. The method for producing an oxide according to any one of claims 1 to 6, wherein the carrier is activated carbon.

8. A method for producing an oxide, comprising dehydrogenating and oxidizing an organic compound having one primary hydroxyl group in the presence of a Pt / Bi composite catalyst, a Bi ion source, and water under the condition that the minimum value of the pH during the reaction is less than 7 to obtain an oxide of the organic compound.

9. The method for producing an oxide according to claim 8, which involves the regeneration of the Pt / Bi composite catalyst.

10. The method for producing an oxide according to any one of claims 1 to 9, wherein the Bi ion source is added at the start or during the dehydrogenation oxidation reaction.

11. A method for producing a Pt / Bi composite catalyst, comprising mixing Pt supported on a carrier and a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water and reacting under the condition that the minimum value of the pH during the reaction is less than 7.

12. The method for producing a Pt / Bi composite catalyst according to claim 11, which involves the dehydrogenation oxidation reaction of the organic compound.

13. The method for producing a Pt / Bi composite catalyst according to claim 11 or 12, wherein the Bi ion source is water-insoluble.

14. The method for producing a Pt / Bi composite catalyst according to any one of claims 11 to 13, wherein the Bi ion source is bismuth oxide.

15. The method for producing a Pt / Bi composite catalyst according to any one of claims 11 to 14, wherein the carrier is activated carbon.

16. A method for producing a Pt / Bi composite catalyst, which comprises mixing a Pt / Bi composite catalyst and a Bi ion source in the presence of an organic compound having one primary hydroxyl group and water, and reacting them under the condition that the minimum value of pH during the reaction is less than 7.

17. The method for producing a Pt / Bi composite catalyst according to claim 16, wherein the Bi ion source is added at the start of the reaction or during the reaction to regenerate the Pt / Bi composite catalyst.

18. A method for producing an oxide, which comprises subjecting the organic compound to a dehydrogenation oxidation reaction in the presence of the Pt / Bi composite catalyst obtained by the method for producing a Pt / Bi composite catalyst according to any one of claims 11 to 17 to obtain an oxide of the organic compound.