Polymetallic oxygen cluster and preparation method and application thereof

Abstract

The invention relates to the technical field of aldehyde oxidation, and discloses a multi-metal oxygen cluster as well as a preparation method and application thereof. The structural general formula of the multi-metal oxygen cluster is [X] 3 [M1M26O18 (OH) 6], and M1 is one of VIII subgroup elements; m2 is chromium, molybdenum or tungsten; and X is an organic positive ion. According to the present invention, the polyoxometalate comprises two combined metal elements and an organic structure, such that the high-carbon aldehyde is efficiently oxidized into the high-carbon acid, the reaction efficiency of the high-carbon aldehyde oxidation to prepare the high-carbon acid is improved, the generation of the by-product is substantially reduced, and the conversion rate and the selectivity of the high-carbon aldehyde are improved.

Description

Technical Field

[0001] This invention relates to the field of aldehyde oxidation technology, specifically to a polymetallic oxy-cluster, its preparation method, and its application. Background Technology

[0002] Oxidation is one of the most fundamental reactions in nature, and the oxidation of aldehydes to carboxylic acids is one of the most well-known and commonly used methods. The oxidation of aldehydes to carboxylic acids is a very important biological process in nature. One of the most representative examples is the oxidation of acetaldehyde to acetic acid in hepatocytes, using aldehyde dehydrogenase as a catalyst and oxygen as the sole oxidant, in water at 37°C. Although aldehydes are readily oxidized, most aldehydes are generally stable and do not respond to auto-oxidation. While it is easy to obtain carboxylic acids in the laboratory by oxidizing the corresponding aldehydes, efficiently and environmentally friendly conversion of aldehydes to carboxylic acids remains a challenge. Even in modern industry and academia, methods for catalytic oxidation of aldehydes to carboxylic acids are still rare. Even today, most oxidation reactions require stoichiometric amounts of harmful oxidants such as KMnO4, CrO3, KHSO5, KIO4, etc., and are often carried out in harmful solvents. Notably, among all classic aldehyde oxidation methods, the Fehlings reaction and the Tollens reaction are very useful due to their very broad substrate range and high reaction efficiency. However, the fatal weakness of these methods is that they still require stoichiometric amounts of copper or silver reagents and produce stoichiometric amounts of metal waste, making them both expensive and wasteful. Therefore, environmentally friendly oxidation schemes are in high demand. Compared with other oxidants, molecular oxygen has many advantages; reactions using molecular oxygen are highly atom-economical and produce water as the only byproduct. However, methods for the catalytic oxidation of aldehydes to carboxylic acids using molecular oxygen as the terminal oxidant remain scarce. The number of catalysts available for direct activation by molecular oxygen is limited, and the need for rare and expensive precious metals as catalysts restricts its use. Furthermore, most systems reported to date require expensive metals, commercially unavailable ligands, and non-recoverable aerobic catalyst systems, resulting in prohibitively high costs for practical applications. Therefore, there is a strong desire to use inexpensive and globally abundant transition metal catalyst systems that use molecular oxygen as the terminal oxidant. Compared to common organic solvents, the natural abundance of water and its inherent green properties make it highly attractive for developing more environmentally friendly reactions. In recent years, catalytic aerobic oxidation methods have attracted widespread attention due to their high efficiency and simple operation. For example, there are examples in the prior art of aerobic oxidation catalyzed by homogeneous silver or copper in water, which successfully oxidizes various aldehydes to carboxylic acids under mild reaction conditions with conversion rates approaching 100%. However, the organic ligands used in these reactions are prone to oxidative degradation, which limits their applications. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of low reaction efficiency, numerous byproducts, and low conversion and selectivity of high-carbon aldehydes in the oxidation process of high-carbon aldehydes to high-carbonic acid in existing technologies. This invention provides a polyoxometalate cluster, its preparation method, and its applications. This polyoxometalate cluster improves the reaction efficiency of the oxidation of high-carbon aldehydes to high-carbonic acid, significantly reduces the formation of byproducts, and improves the conversion and selectivity of high-carbon aldehydes. It features low reaction pressure, low reaction temperature, high conversion rate, and high selectivity, making it easier to industrialize. Furthermore, the polyoxometalate cluster can be reused as a catalyst and is easy to separate from the product, showing good industrialization prospects. Simultaneously, the higher conversion rate and selectivity can significantly improve the production efficiency of the target product, reduce production costs, and make the product performance more stable, which is beneficial for market promotion.

[0004] To achieve the above objectives, the first aspect of the present invention provides a polyoxometalate cluster, the general structural formula of which is [X]3[M]. 1 M 2 6O 18 [(OH)6], where M 1 It is one of the elements in subgroup VIII; M 2 It is chromium, molybdenum, or tungsten; X is an organic positive ion.

[0005] Preferably, M 1 It can be iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum.

[0006] Preferably, X is a quaternary ammonium cation, an organomethane cation, or an organomethane cation.

[0007] Preferably, X is a tetrabutylammonium cation, a tetrapropylammonium cation, a tetraethylammonium cation, a trimethylethylammonium cation, a triphenylsulfonium cation, or a (fluoromethyl)triphenylphosphonium cation.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned polymetallic oxy-oxide clusters, the method comprising:

[0009] The first metal salt solution and the second metal salt solution are first stirred and mixed at 90-100℃, and the filtrate is separated at 90-100℃. The obtained filtrate is cooled to 10-35℃ to obtain a solid-liquid mixture. Then, the solid phase is separated from the solid-liquid mixture, and the obtained solid phase is prepared into a solution. The obtained solution is then stirred and mixed with an organic positive ion salt for the second time. The metal element in the first metal salt solution is one of the group VIII sub-elements; the second metal salt solution is a chromate solution, a tungstate solution, or a molybdate solution.

[0010] Preferably, the metal element in the first metal salt solution is iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum.

[0011] Preferably, the organic positive ionic salt is a quaternary ammonium salt, an organic sulfonium salt, or an organic phosphonium salt.

[0012] Preferably, the organic positive ion salt is tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride, trimethylethylammonium bromide, triphenylthiohexafluorophosphate, or (fluoromethyl)triphenylphosphine tetrafluoroborate.

[0013] The third aspect of the present invention provides the application of the above-mentioned polymetallic oxy-groups in aldehyde oxidation.

[0014] A fourth aspect of the present invention provides a method for preparing high carbonic acid using high carbon aldehydes, the method comprising: mixing high carbon aldehydes, a catalyst, an alkaline additive and a solvent, and carrying out an oxidation reaction under the action of an oxidant, wherein the catalyst is the aforementioned polymetallic oxy-oxide cluster; and the high carbon aldehyde is at least one of a C4 or higher ortho-aldehyde compound and a C4 or higher iso-aldehyde compound.

[0015] Preferably, the molar ratio of the catalyst to the high carbon aldehyde is (0.0005-0.002):1.

[0016] Preferably, the high carbon aldehyde is at least one of n-heptanal, dodecanoal, and isobutyraldehyde.

[0017] Preferably, the alkaline additive is an organic base and / or an inorganic base.

[0018] Preferably, the alkaline additive is at least one selected from sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, ammonia, and fatty amines.

[0019] Preferably, the molar ratio of the alkaline additive to the high carbon aldehyde is (0.05-0.15):1.

[0020] Preferably, the solvent is a polar solvent.

[0021] Preferably, the solvent is at least one selected from water, ethylene glycol, methanol, acetonitrile, and acetone.

[0022] Preferably, the ratio of the high carbon aldehyde to the solvent is 0.1 mol: (90-200) mL.

[0023] Preferably, the oxidant is air and / or oxygen.

[0024] Preferably, the conditions for the oxidation reaction include: a temperature of 20-90°C and a time of 12-24 hours.

[0025] Through the above technical solution, the polymetallic oxygen cluster, as a catalyst, improves the reaction efficiency of the oxidation of high carbon aldehydes to high carbonic acid, greatly reduces the generation of by-products, improves the conversion rate and selectivity of high carbon aldehydes, and is easy to separate and can be reused. Detailed Implementation

[0026] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0027] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] The general structural formula of the polymetallic oxygen cluster described in this invention is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 It is one of the elements in subgroup VIII; M 2 X is chromium, molybdenum, or tungsten; X is an organic positive ion. The polyoxometalate cluster is a composite structure of inorganic and organic compounds. The polyoxometalate cluster according to this invention contains two combined metal elements and an organic structure, achieving efficient oxidation of high-carbon aldehydes to high-carbonic acid, improving the reaction efficiency of high-carbon aldehyde oxidation to high-carbonic acid, significantly reducing the formation of byproducts, and improving the conversion rate and selectivity of high-carbon aldehydes.

[0029] In the polymetallic oxygen clusters described in this invention, in order to improve conversion rate and selectivity, M 1 Preferably, it is made of iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum, more preferably iron, cobalt, or nickel. To improve conversion and selectivity, M... 2 Preferably, it is chromium, molybdenum, or tungsten, more preferably molybdenum or tungsten. In some embodiments, M 1 For iron, M 2 Molybdenum is used. In other embodiments, M... 1 For cobalt, M 2 It is tungsten. In other embodiments, M... 1 For nickel, M 2 It is molybdenum.

[0030] In the polyoxometalate clusters described in this invention, X can be a quaternary ammonium cation, an organosulfonium cation, or an organophosphorus cation, preferably a quaternary ammonium cation. X can be a tetrabutylammonium cation, a tetrapropylammonium cation, a tetraethylammonium cation, a trimethylethylammonium cation, a triphenylsulfonium cation, or a (fluoromethyl)triphenylphosphorus cation, preferably a tetrabutylammonium cation, a tetrapropylammonium cation, or a tetraethylammonium cation. In some embodiments, M... 1 For iron, M 2 Molybdenum is present, and X is a tetraethylammonium cation. In other embodiments, M... 1 For cobalt, M 2 Tungsten is present, and X is a tetrabutylammonium cation. In other embodiments, M... 1 For nickel, M 2 Molybdenum is represented by X, which is a tetrapropylammonium cation.

[0031] In some embodiments, the general structural formula of the polyoxometalate clusters described in this invention is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 It is made of iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum; M 2 It is chromium, molybdenum or tungsten; X is a quaternary ammonium cation, an organomethane cation or an organomethane cation.

[0032] In other embodiments, the general structural formula of the polyoxometalate clusters described in this invention is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 It is made of iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum; M 2 It is chromium, molybdenum or tungsten; X is tetrabutylammonium cation, tetrapropylammonium cation, tetraethylammonium cation, trimethylethylammonium cation, triphenylsulfonium cation or (fluoromethyl)triphenylphosphonium cation.

[0033] In other embodiments, the general structural formula of the polyoxometalate clusters described in this invention is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 Iron, cobalt, or nickel; M 2 It is molybdenum or tungsten; X is tetrabutylammonium cation, tetrapropylammonium cation or tetraethylammonium cation.

[0034] The present invention also provides a method for preparing the above-mentioned polyoxometalate clusters, the method comprising:

[0035] The first metal salt solution and the second metal salt solution are first stirred and mixed at 90-100℃, and the filtrate is separated at 90-100℃. The obtained filtrate is cooled to 10-35℃ to obtain a solid-liquid mixture. Then, the solid phase is separated from the solid-liquid mixture, and the obtained solid phase is prepared into a solution. The obtained solution is then stirred and mixed with an organic positive ion salt for the second time. The metal element in the first metal salt solution is one of the group VIII sub-elements; the second metal salt solution is a chromate solution, a tungstate solution, or a molybdate solution.

[0036] The polymetallic oxygen clusters prepared according to the method described in this invention improve the reaction efficiency of the oxidation of high carbon aldehydes to high carbonic acid, greatly reduce the generation of by-products, and improve the conversion rate and selectivity of high carbon aldehydes.

[0037] In the method described in this invention, to improve conversion rate and selectivity, the metal element in the first metal salt solution is preferably iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum, more preferably iron, cobalt, or nickel. The metal salt in the first metal salt solution can be an iron salt, cobalt salt, nickel salt, ruthenium salt, rhodium salt, palladium salt, osmium salt, iridium salt, or platinum salt. The concentration of the metal salt in the first metal salt solution can be 0.1-0.2 mol / L, preferably 0.15-0.2 mol / L. The solvent in the first metal salt solution can be water. The iron salt can be ferric nitrate, ferric sulfate, or ferric phosphate, preferably ferric sulfate. The cobalt salt can be cobalt nitrate, cobalt sulfate, or cobalt phosphate, preferably cobalt sulfate. The nickel salt can be nickel nitrate, nickel sulfate, or nickel phosphate, preferably nickel sulfate. The ruthenium salt can be ruthenium trichloride, ruthenium nitrate, or ruthenium oxalate, preferably ruthenium trichloride. The rhodium salt can be rhodium trichloride, rhodium nitrate, or rhodium sulfate, preferably rhodium sulfate. The palladium salt can be palladium chloride, palladium nitrate, or palladium sulfate, preferably palladium sulfate. The osmium salt can be osmium chloride, osmium nitrate, or osmium sulfate, preferably osmium chloride. The iridium salt can be iridium chloride, iridium nitrate, or iridium sulfate, preferably iridium chloride. The platinum salt can be platinum chloride, platinum nitrate, or platinum sulfate, preferably platinum chloride.

[0038] In the method described in this invention, to improve conversion rate and selectivity, the second metal salt solution is preferably a chromate solution, a tungstate solution, or a molybdate solution, more preferably a tungstate solution or a molybdate solution. The concentration of the metal salt in the second metal salt solution can be 0.04-0.064 mol / L, preferably 0.05-0.06 mol / L. The solvent in the second metal salt solution can be water. The chromate solution can be at least one of ammonium chromate, potassium chromate, and sodium chromate, preferably ammonium chromate. The molybdate solution can be at least one of ammonium molybdate, potassium molybdate, and sodium molybdate, preferably ammonium molybdate. The tungstate solution can be at least one of ammonium tungstate, potassium tungstate, and sodium tungstate, preferably ammonium tungstate.

[0039] In the method described in this invention, the conditions for the first stirring and mixing include: a stirring rate of 40-200 rpm, preferably 60-80 rpm; and a time of 0.5-6 h, preferably 1-2 h. The specific process of stirring and mixing the first metal salt solution and the second metal salt solution at 90-100°C may include: adding the first metal salt solution dropwise to the second metal salt solution at 90-100°C at a stirring rate of 60-80 rpm for 0.5-2 h; after the addition is complete, continuing stirring and mixing at 90-100°C for 0.8-1.5 h.

[0040] In the method described in this invention, the filtrate separated at 90-100°C can be filtered. The filtrate contains ammonium salts. The specific process of cooling the obtained filtrate to 10-35°C may include: cooling the obtained filtrate to 10-35°C and allowing it to stand at 10-35°C for 10-15 hours.

[0041] In the method described in this invention, the method may further include: recrystallizing the obtained solid phase 2-4 times before preparing it into a solution. The specific recrystallization process may include: dissolving the obtained solid phase in water at 75-85°C, then cooling it to 10-35°C to obtain a solid-liquid mixture, and then separating the solid phase from the solid-liquid mixture.

[0042] In the method described in this invention, the specific process of preparing the obtained solid phase into a solution may include: refluxing the obtained solid phase and water at 90-100°C for 20-30 hours. The concentration of the solution prepared from the obtained solid phase may be 0.08-0.15 mol / L, preferably 0.1-1.12 mol / L. The method may further include: cooling the obtained solution to 10-35°C before subjecting the obtained solution and the organic positive ion salt to a second stirring mixture.

[0043] In the method described in this invention, the organic cation salt can be a quaternary ammonium salt, an organic sulfonium salt, or an organic phosphonium salt, preferably a quaternary ammonium salt. The quaternary ammonium salt can be tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride, or trimethylethylammonium bromide. The organic sulfonium salt can be triphenylthiohexafluorophosphate. The organic phosphonium salt can be (fluoromethyl)triphenylphosphine tetrafluoroborate.

[0044] In the method described in this invention, the organic positive ion salt can be tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride, trimethylethylammonium bromide, triphenylthiohexafluorophosphate, or (fluoromethyl)triphenylphosphine tetrafluoroborate, preferably tetrabutylammonium bromide, tetrapropylammonium bromide, or tetraethylammonium chloride.

[0045] In the method described in this invention, the amounts of the first metal salt solution, the second metal salt solution, and the organic positive ion salt are such that the general structural formula of the prepared polyoxometalate cluster is [X]3[M]. 1 M 2 6O 18 [(OH)6], where M 1 It is one of the elements in subgroup VIII; M 2 It is chromium, molybdenum, or tungsten; X is an organic positive ion.

[0046] In the method described in this invention, the conditions for the second stirring and mixing include: the temperature can be 10-35℃, preferably 15-35℃; the stirring rate can be 40-200rpm, preferably 60-80rpm; and the time can be 0.8-1.5h, preferably 1-1.5h.

[0047] In the method described in this invention, the method may further include: after the second stirring and mixing, separating the solid phase from the obtained mixture by filtration.

[0048] In some embodiments, the method for polyoxometalate clusters according to the present invention includes:

[0049] A first metal salt solution with a concentration of 0.1-0.2 mol / L was dropwise added to a second metal salt solution with a concentration of 0.04-0.064 mol / L at a temperature of 90-100℃ for 0.5-6 hours. After the addition was complete, the mixture was stirred and mixed at 90-100℃ for 0.8-1.5 hours. The filtrate was then separated by filtration at 90-100℃. The filtrate was cooled to 10-35℃ and allowed to stand at 10-35℃ for 10-15 hours to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture by dissolving it in water at 75-85℃, followed by cooling to 10-35℃. A solid-liquid mixture is obtained at 0-35℃. The solid phase is then separated from the mixture and recrystallized. This recrystallization process is repeated. The resulting solid phase and water are refluxed at 90-100℃ for 20-30 hours to prepare a solution with a concentration of 0.08-0.15 mol / L. The resulting solution and an organic positive ion salt are then stirred and mixed at 10-35℃ with a stirring rate of 40-200 rpm for 0.8-1.5 hours. The solid phase is then separated from the mixture by filtration. The metal element in the first metal salt solution is one of the group VIII transition metals. The second metal salt solution is a chromate solution, a tungstate solution, or a molybdate solution.

[0050] In other embodiments, the method for polymetallic oxygen clusters according to the present invention includes:

[0051] A first metal salt solution with a concentration of 0.1-0.2 mol / L was added dropwise to a second metal salt solution with a concentration of 0.04-0.064 mol / L at a temperature of 90-100℃ for 0.5-6 hours. After the addition was complete, the mixture was stirred and mixed at 90-100℃ for 0.8-1.5 hours. The filtrate was then separated by filtration at 90-100℃. The filtrate was cooled to 10-35℃ and allowed to stand at 10-35℃ for 10-15 hours to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture by dissolving it in water at 75-85℃, followed by cooling to 10-35℃ to obtain another solid-liquid mixture. The solid phase is then separated from the solid-liquid mixture and recrystallized, and the recrystallization is repeated. The obtained solid phase and water are refluxed at 90-100℃ for 20-30h to prepare a solution with a concentration of 0.08-0.15mol / L. The obtained solution and an organic positive ion salt are then stirred and mixed at 10-35℃ with a stirring rate of 40-200rpm for 0.8-1.5h. The solid phase is then separated from the obtained mixture by filtration. The metal element in the first metal salt solution is iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium or platinum; the second metal salt solution is a chromate solution, tungstate solution or molybdate solution; and the organic positive ion salt is a quaternary ammonium salt, an organic sulfonium salt or an organic phosphonium salt.

[0052] In other embodiments, the method for polymetallic oxygen clusters according to the present invention includes:

[0053] A first metal salt solution with a concentration of 0.1-0.2 mol / L was added dropwise to a second metal salt solution with a concentration of 0.04-0.064 mol / L at a temperature of 90-100℃ for 0.5-6 hours. After the addition was complete, the mixture was stirred and mixed at 90-100℃ for 0.8-1.5 hours. The filtrate was then separated by filtration at 90-100℃. The filtrate was cooled to 10-35℃ and allowed to stand at 10-35℃ for 10-15 hours to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture by dissolving it in water at 75-85℃, followed by cooling to 10-35℃ to obtain another solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture. The solid phase is recrystallized, and the recrystallization is repeated. The obtained solid phase and water are refluxed at 90-100℃ for 20-30h to prepare a solution with a concentration of 0.08-0.15mol / L. The obtained solution and an organic positive ion salt are then stirred and mixed at 10-35℃ at a stirring rate of 40-200rpm for 0.8-1.5h. The solid phase is then separated from the mixture by filtration. The metal element in the first metal salt solution is iron, cobalt, or nickel; the second metal salt solution is a tungstate solution or a molybdate solution; and the organic positive ion salt is tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride, trimethylethylammonium bromide, triphenylthiohexafluorophosphate, or (fluoromethyl)triphenylphosphine tetrafluoroborate.

[0054] This invention also provides the application of the aforementioned polyoxometalate clusters in aldehyde oxidation. According to the application described in this invention, by using the polyoxometalate clusters as catalysts, the oxidation reaction can achieve efficient oxidation of high-carbon aldehydes to high-carbonic acid under conditions requiring no additional pressure and low reaction temperature. This improves the reaction efficiency of high-carbon aldehyde oxidation to high-carbonic acid, significantly reduces the formation of byproducts, and enhances the conversion rate and selectivity of high-carbon aldehydes.

[0055] This invention also provides a method for preparing high carbonic acid from high carbon aldehydes. The method includes: mixing high carbon aldehydes, a catalyst, an alkaline additive, and a solvent, and carrying out an oxidation reaction under the action of an oxidant. The catalyst is a polyoxometalate cluster as described above; the high carbon aldehyde is at least one of a normal aldehyde compound with more than four carbon atoms and an isoaldehyde compound with more than four carbon atoms. The method according to this invention, using the polyoxometalate cluster, alkaline additive, and oxidant, results in low reaction pressure, low reaction temperature, high conversion rate, and high selectivity, making it easier to industrialize. Simultaneously, the polyoxometalate cluster, as a catalyst, can be reused and is easily separated from the product, showing good industrialization prospects. Furthermore, the high conversion rate and selectivity can significantly improve the production efficiency of the target product, reduce production costs, and make the product performance more stable, which is beneficial for market promotion.

[0056] In the method described in this invention, the molar ratio of the catalyst to the higher carbon aldehyde is (0.0005-0.002):1, preferably (0.0005-0.001):1. The higher carbon aldehyde can be at least one of n-heptanal, dodecanoal, and isobutyraldehyde.

[0057] In the method described in this invention, the alkaline additive can be an organic base and / or an inorganic base. The organic base can be a fatty amine, preferably triethylamine. The inorganic base can be at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, and ammonia. In a preferred embodiment, the alkaline additive is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, ammonia, and a fatty amine. In a more preferred embodiment, the alkaline additive is at least one of sodium carbonate, triethylamine, and sodium ethoxide.

[0058] In the method described in this invention, the molar ratio of the alkaline additive to the high carbon aldehyde can be (0.05-0.15):1, preferably (0.1-0.15):1.

[0059] In the method described in this invention, the solvent can be a polar solvent. The solvent can be at least one selected from water, ethylene glycol, methanol, acetonitrile, and acetone, preferably water. The ratio of the high carbon aldehyde to the solvent can be 0.1 mol:(90-200) mL, preferably 0.1 mol:(90-150) mL.

[0060] In the method described in this invention, the oxidant can be air and / or oxygen, preferably oxygen. Using air and / or oxygen as the oxidant is clean and environmentally friendly. The blowing rate of the oxygen and the air can be 50-90 mL / min, preferably 60-80 mL / min.

[0061] In the method described in this invention, the conditions for the oxidation reaction include: a temperature of 20-90°C, preferably 60-85°C; and a time of 12-24 hours, preferably 18-24 hours. The specific process of the oxidation reaction may include: mixing a high-carbon aldehyde, a catalyst, an alkaline additive, and a solvent; then, under stirring conditions, blowing in an oxidant at a rate of 50-90 mL / min; and carrying out the oxidation reaction at a temperature of 20-90°C for 12-24 hours. The stirring rate of the oxidation reaction can be 40-200 rpm, preferably 60-80 rpm; and the time can be 0.5-6 hours, preferably 1-2 hours.

[0062] In some embodiments, the method for preparing high carbonic acid using high carbon aldehydes according to the present invention includes: mixing high carbon aldehydes, a catalyst, an alkaline additive, and a solvent; then blowing in an oxidant at a stirring rate of 50-90 mL / min at a stirring rate of 40-200 rpm; and carrying out an oxidation reaction at a temperature of 20-90°C for 12-24 h. The catalyst is a polymetallic oxygen cluster, and the general structural formula of the polymetallic oxygen cluster is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 It is one of the elements in subgroup VIII; M 2 The catalyst is chromium, molybdenum, or tungsten; X is an organic positive ion; the high-carbon aldehyde is at least one of a C4 or higher ortho-aldehyde compound and a C4 or higher or iso-aldehyde compound; the molar ratio of the catalyst to the high-carbon aldehyde is (0.0005-0.002):1; the alkaline additive is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, ammonia, and aliphatic amine; the molar ratio of the alkaline additive to the high-carbon aldehyde is (0.05-0.15):1; the solvent is at least one of water, ethylene glycol, methanol, acetonitrile, and acetone; the ratio of the high-carbon aldehyde to the solvent is 0.1 mol: (90-200) mL.

[0063] In other embodiments, the method for preparing high carbonic acid using high carbon aldehydes according to the present invention includes: mixing high carbon aldehydes, a catalyst, an alkaline additive, and a solvent; then blowing in an oxidant at a stirring rate of 50-90 mL / min at a stirring rate of 40-200 rpm; and carrying out an oxidation reaction at a temperature of 20-90°C for 12-24 h. The catalyst is a polymetallic oxygen cluster, and the general structural formula of the polymetallic oxygen cluster is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 It is made of iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum; M 2The catalyst is chromium, molybdenum, or tungsten; X is a quaternary ammonium cation, an organomethane cation, or an organophosphorus cation; the high-carbon aldehyde is at least one of a C4 or higher ortho-aldehyde compound and a C4 or higher iso-aldehyde compound; the molar ratio of the catalyst to the high-carbon aldehyde is (0.0005-0.002):1; the alkaline additive is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, ammonia, and aliphatic amines; the molar ratio of the alkaline additive to the high-carbon aldehyde is (0.05-0.15):1; the solvent is at least one of water, ethylene glycol, methanol, acetonitrile, and acetone; the ratio of the high-carbon aldehyde to the solvent is 0.1 mol: (90-200) mL.

[0064] In other embodiments, the method for preparing high carbonic acid using high carbon aldehydes according to the present invention includes: mixing high carbon aldehydes, a catalyst, an alkaline additive, and a solvent; then blowing in an oxidant at a stirring rate of 50-90 mL / min at a stirring rate of 40-200 rpm; and carrying out an oxidation reaction at a temperature of 20-90°C for 12-24 h. The catalyst is a polymetallic oxygen cluster, and the general structural formula of the polymetallic oxygen cluster is [X]3[M 1 M 2 6O 18 [(OH)6], where M 1 Iron, cobalt, or nickel; M 2 The catalyst is molybdenum or tungsten; X is a tetrabutylammonium cation, tetrapropylammonium cation, tetraethylammonium cation, trimethylethylammonium cation, triphenylsulfonium cation, or (fluoromethyl)triphenylphosphonium cation; the high carbon aldehyde is at least one of a C4 or higher ortho-aldehyde compound and a C4 or higher iso-aldehyde compound; the molar ratio of the catalyst to the high carbon aldehyde is (0.0005-0.002):1; the alkaline additive is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, ammonia, and aliphatic amine; the molar ratio of the alkaline additive to the high carbon aldehyde is (0.05-0.15):1; the solvent is at least one of water, ethylene glycol, methanol, acetonitrile, and acetone; the ratio of the high carbon aldehyde to the solvent is 0.1 mol: (90-200) mL.

[0065] The following examples further illustrate the polyoxometalate clusters, their preparation methods, and applications described in this invention. These examples are implemented based on the technical solutions of this invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of this invention is not limited to the following examples.

[0066] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0067] Preparation Example 1

[0068] 9.5 mmol of ferric sulfate was dissolved in 60 mL of water to prepare a 0.158 mol / L ferric sulfate solution. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare a 0.052 mol / L ammonium molybdate solution, and the solution was added to 100 °C. The ferric sulfate solution was then added dropwise to the 100 °C ammonium molybdate solution while stirring at 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then... The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. The resulting solution was then mixed with tetraethylammonium chloride at 20°C with a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [NEt4]3[FeMo6O 18 (OH)6.

[0069] Preparation Example 2

[0070] 9.5 mmol of cobalt sulfate was dissolved in 60 mL of water to prepare a cobalt sulfate solution with a concentration of 0.158 mol / L. 13 mmol of ammonium tungstate was dissolved in 250 mL of water to prepare an ammonium tungstate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The cobalt sulfate solution was then added dropwise to the ammonium tungstate solution at 100 °C with a stirring speed of 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then subjected to further processing. The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, and then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. The resulting solution was then mixed with tetrabutylammonium bromide at 20°C and a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [N(n-Bu)4]3[CoW6O]3. 18 (OH)6.

[0071] Preparation Example 3

[0072] 9.5 mmol of nickel sulfate was dissolved in 60 mL of water to prepare a nickel sulfate solution with a concentration of 0.158 mol / L. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare an ammonium molybdate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The nickel sulfate solution was then added dropwise to the ammonium molybdate solution at 100 °C with a stirring speed of 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then... The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. The resulting solution was then mixed with tetrapropylammonium bromide at 20°C and a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [NPr4]3[NiMo6O 18 (OH)6.

[0073] Preparation Example 4

[0074] 9.5 mmol of ruthenium trichloride was dissolved in 60 mL of water to prepare a ruthenium trichloride solution with a concentration of 0.158 mol / L. 13 mmol of ammonium chromate was dissolved in 250 mL of water to prepare an ammonium chromate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The mixture was then stirred dropwise into the 100 °C ammonium chromate solution at a stirring speed of 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 90 °C for another 1 hour. The filtrate was then separated by filtration at 90 °C. The filtrate was cooled to 35 °C and allowed to stand at 35 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then filtered to separate the solid from the liquid. The solid phase was separated from the liquid mixture by dissolving it in water at 80°C and then cooling it to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the mixture and recrystallized, with the recrystallization process repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. This solution was then mixed with trimethylethylammonium bromide at 20°C and a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [CH3CH2N(CH3)]3[RuCr6O 18 (OH)6.

[0075] Preparation Example 5

[0076] 9.5 mmol of rhodium trichloride was dissolved in 60 mL of water to prepare a 0.158 mol / L rhodium trichloride solution. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare a 0.052 mol / L ammonium molybdate solution, and the solution was added to 100 °C. The rhodium trichloride solution was then added dropwise to the 100 °C ammonium molybdate solution while stirring at 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then... The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. This solution was then mixed with triphenylthiohexafluorophosphate at 20°C with a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [SPh3]3[RhMo6O 18 (OH)6.

[0077] Preparation Example 6

[0078] 9.5 mmol of palladium chloride was dissolved in 60 mL of water to prepare a palladium chloride solution with a concentration of 0.158 mol / L. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare an ammonium molybdate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The palladium chloride solution was then added dropwise to the ammonium molybdate solution at 100 °C with a stirring speed of 75 rpm for 1.2 h. After the addition was complete, the mixture was stirred and mixed at 100 °C for another 1 h. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 h to obtain a solid-liquid mixture. This mixture was then filtered to separate the solid from the liquid. The solid phase was separated from the mixture by dissolving it in water at 80°C, followed by cooling to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the mixture and recrystallized, with the recrystallization process repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. This solution was then mixed with (fluoromethyl)triphenylphosphine tetrafluoroborate at 20°C with a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [FCH2PPh3]3[PdMo6O 18 (OH)6.

[0079] Preparation Example 7

[0080] 9.5 mmol of osmium chloride was dissolved in 60 mL of water to prepare an osmium chloride solution with a concentration of 0.158 mol / L. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare an ammonium molybdate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The osmium chloride solution was then added dropwise to the 100 °C ammonium molybdate solution while stirring at 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then... The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. The resulting solution was then mixed with tetraethylammonium chloride at 20°C with a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [NEt4]3[OsMo6O 18 (OH)6.

[0081] Preparation Example 8

[0082] 9.5 mmol of iridium chloride was dissolved in 60 mL of water to prepare an iridium chloride solution with a concentration of 0.158 mol / L. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare an ammonium molybdate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The iridium chloride solution was then added dropwise to the 100 °C ammonium molybdate solution while stirring at 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then... The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. The resulting solution was then mixed with tetraethylammonium chloride at 20°C with a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [NEt4]3[IrMo6O 18 (OH)6.

[0083] Preparation Example 9

[0084] 9.5 mmol of platinum chloride was dissolved in 60 mL of water to prepare a platinum chloride solution with a concentration of 0.158 mol / L. 13 mmol of ammonium molybdate was dissolved in 250 mL of water to prepare an ammonium molybdate solution with a concentration of 0.052 mol / L, and the solution was added to 100 °C. The platinum chloride solution was then added dropwise to the ammonium molybdate solution at 100 °C with a stirring speed of 80 rpm for 1 hour. After the addition was complete, the mixture was stirred and mixed at 100 °C for another hour. The filtrate was then separated by filtration at 100 °C. The filtrate was cooled to 20 °C and allowed to stand at 20 °C for 12 hours to obtain a solid-liquid mixture. This mixture was then... The solid phase was separated from the solid-liquid mixture by filtration. The obtained solid phase was dissolved in water at 80°C, then cooled to 20°C to obtain a solid-liquid mixture. The solid phase was then separated from the solid-liquid mixture and recrystallized, and this recrystallization was repeated twice. 2 mmol of the obtained solid phase and 20 mL of water were refluxed at 100°C for 24 h to prepare a 0.1 mol / L solution. The resulting solution was then mixed with tetraethylammonium chloride at 20°C with a stirring rate of 80 rpm for 1 h. The solid phase was then separated from the mixture by filtration to obtain [NEt4]3[PtMo6O 18 (OH)6.

[0085] Example 1

[0086] In a 500 mL round-bottom flask, 0.1 mol of n-heptaldehyde and 0.0001 mol of the [NEt4]3[FeMo6O] prepared in Preparation Example 1 were added. 18 [OH)6], 0.01 mol sodium carbonate, and 150 mL of water were mixed, and oxygen was blown in at 60 mL / min while stirring at 80 rpm. The oxidation reaction was carried out at 70 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, yielding 12.88 g of n-heptanoic acid, with a conversion rate of 100%, a selectivity of 99%, and a yield of 99%.

[0087] Example 2

[0088] In a 500 mL round-bottom flask, 0.1 mol of dodecanal and 0.0001 mol of the [N(n-Bu)4]3[CoW6O] prepared in Preparation Example 2 were added. 18 [OH)6], 0.01 mol triethylamine, and 200 mL of water were mixed, and oxygen was blown in at 60 mL / min while stirring at 75 rpm. The oxidation reaction was carried out at 85 °C for 24 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, and 19.63 g of dodecanoic acid was obtained, with a conversion rate of 99%, a selectivity of 99%, and a yield of 98%.

[0089] Example 3

[0090] In a 500 mL round-bottom flask, 0.2 mol of isobutyraldehyde and 0.0001 mol of the [NPr4]3[NiMo6O] prepared in Preparation Example 3 were added. 18 [OH)6], 0.02 mol sodium ethoxide, and 200 mL of water were mixed, and oxygen was blown in at 60 mL / min while stirring at 70 rpm. The oxidation reaction was carried out at 60 °C for 18 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, and 16.92 g of isobutyric acid was obtained, with a conversion rate of 98%, a selectivity of 98%, and a yield of 96%.

[0091] Example 4

[0092] In a 500 mL round-bottom flask, 0.1 mol of n-heptaldehyde and 0.0001 mol of the [CH3CH2N(CH3)]3[RuCr6O] prepared in Preparation Example 4 were added. 18 [OH)6], 0.005 mol potassium carbonate, and 150 mL ethylene glycol were mixed, and oxygen was blown in at 60 mL / min while stirring at 80 rpm. The oxidation reaction was carried out at 90 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, yielding 12.63 g of n-heptanoic acid, with a conversion rate of 99%, a selectivity of 98%, and a yield of 97%.

[0093] Example 5

[0094] In a 500 mL round-bottom flask, 0.1 mol of n-heptaldehyde and 0.0002 mol of the [SPh3]3[RhMo6O3] prepared in Preparation Example 5 were added. 18 [OH)6], 0.015 mol potassium carbonate, and 150 mL methanol were mixed, and oxygen was blown in at 60 mL / min while stirring at 80 rpm. The oxidation reaction was carried out at 20 °C for 24 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, yielding 12.63 g of n-heptanoic acid, with a conversion rate of 98%, a selectivity of 99%, and a yield of 97%.

[0095] Example 6

[0096] In a 500 mL round-bottom flask, 0.1 mol of n-heptanal and 0.0001 mol of the [FCH2PPh3]3[PdMo6O] prepared in Preparation Example 6 were added. 18 [OH)6], 0.01 mol sodium bicarbonate, and 150 mL acetonitrile were mixed, and oxygen was blown in at 60 mL / min while stirring at 75 rpm. The oxidation reaction was carried out at 70 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, yielding 12.50 g of n-heptanoic acid, with a conversion rate of 98%, a selectivity of 98%, and a yield of 96%.

[0097] Example 7

[0098] In a 500 mL round-bottom flask, 0.1 mol of n-heptanal and 0.0001 mol of the [NEt4]3[OsMo6O] prepared in Preparation Example 7 were added. 18 [OH)6], 0.01 mol sodium methoxide, and 150 mL acetone were mixed, and oxygen was blown in at 60 mL / min while stirring at 75 rpm. The oxidation reaction was carried out at 70 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, yielding 12.51 g of n-heptanoic acid, with a conversion rate of 99%, a selectivity of 97%, and a yield of 96%.

[0099] Example 8

[0100] In a 500 mL round-bottom flask, 0.1 mol of n-heptaldehyde and 0.0001 mol of the [NEt4]3[IrMo6O] prepared in Preparation Example 8 were added. 18[OH)6], 0.01 mol potassium hydroxide, and 150 mL of water were mixed, and oxygen was blown in at 60 mL / min while stirring at 70 rpm. The oxidation reaction was carried out at 70 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, and 12.63 g of n-heptanoic acid was obtained, with a conversion rate of 99%, a selectivity of 98%, and a yield of 97%.

[0101] Example 9

[0102] In a 500 mL round-bottom flask, 0.1 mol of n-heptaldehyde and 0.0001 mol of the [NEt4]3[PtMo6O] prepared in Preparation Example 9 were added. 18 [OH)6], 0.01 mol sodium hydroxide, and 150 mL of water were mixed, and oxygen was blown in at 60 mL / min while stirring at 70 rpm. The oxidation reaction was carried out at 70 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, and 12.37 g of n-heptanoic acid was obtained, with a conversion rate of 98%, a selectivity of 97%, and a yield of 95%.

[0103] Example 10

[0104] In a 500 mL round-bottom flask, 0.1 mol of n-heptaldehyde and 0.0001 mol of the [NEt4]3[FeMo6O] prepared in Preparation Example 1 were added. 18 [OH)6], 20 mL of 0.5 mol / L ammonia solution and 150 mL of water were mixed, and oxygen was blown in at 60 mL / min while stirring at 80 rpm. The oxidation reaction was carried out at 70 °C for 12 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, and 12.50 g of n-heptanoic acid was obtained, with a conversion rate of 98%, a selectivity of 98%, and a yield of 96%.

[0105] Comparative Example 1

[0106] In a 500 mL round-bottom flask, 0.2 mol of isobutyraldehyde was injected with oxygen at a stirring rate of 80 rpm and a stirring rate of 60 mL / min. The oxidation reaction was carried out at 60 °C for 48 h to obtain the product. After the reaction was completed, the product was detected by liquid chromatography, yielding 16.92 g of isobutyric acid, with a conversion rate of 96%, a selectivity of 37%, and a yield of 35.5%.

[0107] Comparative Example 2

[0108] In a 500 mL round-bottom flask, 0.2 mol of isobutyraldehyde, oxygen, 0.02 mol of sodium ethoxide, and 200 mL of water were mixed. Oxygen was then introduced at a stirring rate of 80 rpm and a blowing rate of 60 mL / min. The oxidation reaction was carried out at 60 °C for 18 h to obtain the product. After the reaction was complete, the product was analyzed by liquid chromatography, yielding 6.47 g of isobutyric acid, with a conversion rate of 72%, a selectivity of 51%, and a yield of 36.7%.

[0109] The results of Examples 1-10 and Comparative Examples 1 and 2 show that using the polymetallic oxygen cluster described in this invention as a catalyst enables the oxidation reaction to efficiently oxidize high carbon aldehydes to high carbonic acid without the need for additional pressure and low reaction temperature. This improves the reaction efficiency of oxidizing high carbon aldehydes to high carbonic acid, greatly reduces the generation of by-products, and improves the conversion rate and selectivity of high carbon aldehydes.

[0110] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polymetallic oxygen cluster, characterized in that, The general structural formula of this polyoxometalate cluster is [X]3[M]. 1 M 2 6O 18 [(OH)6], Among them, M 1 It is one of the elements in subgroup VIII; M 2 It is made of chromium, molybdenum, or tungsten; X is an organic positive ion.

2. The polymetallic oxygen cluster according to claim 1, characterized in that, M 1 It can be iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum.

3. The polyoxometalate cluster according to claim 1 or 2, characterized in that, X is a quaternary ammonium cation, an organosulfonium cation, or an organophosphorus cation; Preferably, X is a tetrabutylammonium cation, a tetrapropylammonium cation, a tetraethylammonium cation, a trimethylethylammonium cation, a triphenylsulfonium cation, or a (fluoromethyl)triphenylphosphonium cation.

4. A method for preparing the polyoxometalate cluster according to any one of claims 1-3, characterized in that, The method includes: The first and second metal salt solutions are first stirred and mixed at 90-100°C, and the filtrate is separated at 90-100°C. The filtrate is then cooled to 10-35°C to obtain a solid-liquid mixture. The solid phase is then separated from the solid-liquid mixture, and the obtained solid phase is prepared into a solution. The obtained solution is then mixed with an organic positive ion salt in a second stirring process. The metal element in the first metal salt solution is one of the elements in Group VIII. The second metal salt solution is a chromate solution, a tungstate solution, or a molybdate solution.

5. The method according to claim 4, characterized in that, The metal element in the first metal salt solution is iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, or platinum.

6. The method according to claim 4 or 5, characterized in that, The organic positive ionic salt is a quaternary ammonium salt, an organic sulfonium salt, or an organic phosphonium salt; Preferably, the organic positive ion salt is tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride, trimethylethylammonium bromide, triphenylthiohexafluorophosphate, or (fluoromethyl)triphenylphosphine tetrafluoroborate.

7. The application of the polymetallic oxy-matrix according to any one of claims 1-3 in aldehyde oxidation.

8. A method for preparing high carbonic acid using high carbon aldehydes, characterized in that, The method includes: mixing high-carbon aldehydes, a catalyst, an alkaline additive, and a solvent, and carrying out an oxidation reaction under the action of an oxidant. The catalyst is a polymetallic oxygen cluster as described in any one of claims 1-3; The high-carbon aldehyde is at least one of ortho-aldehyde compounds with C4 or more and iso-aldehyde compounds with C4 or more.

9. The method according to claim 8, characterized in that, The molar ratio of the catalyst to the high-carbon aldehyde is (0.0005-0.002):1; Preferably, the high carbon aldehyde is at least one of n-heptanal, dodecanoal, and isobutyraldehyde.

10. The method according to claim 8 or 9, characterized in that, The alkaline additive is an organic base and / or an inorganic base; Preferably, the alkaline additive is at least one selected from sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium methoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, ammonia, and fatty amines. Preferably, the molar ratio of the alkaline additive to the high carbon aldehyde is (0.05-0.15):

1.

11. The method according to any one of claims 8-10, characterized in that, The solvent is a polar solvent; Preferably, the solvent is at least one selected from water, ethylene glycol, methanol, acetonitrile, and acetone; Preferably, the ratio of the high carbon aldehyde to the solvent is 0.1 mol: (90-200) mL.

12. The method according to any one of claims 8-11, characterized in that, The oxidant is air and / or oxygen; Preferably, the conditions for the oxidation reaction include: a temperature of 20-90°C and a time of 12-24 hours.