Composition with catalytic oxidation and its use in the oxidation of aldehydes to acids

Abstract

The present application relates to the field of catalytic oxidation, and discloses a composition with catalytic oxidation and its application in acid preparation by aldehyde oxidation. The composition with catalytic oxidation comprises a first component and a second component, wherein the weight ratio of the first component and the second component is 0.0001-20, the first component is at least one of ketone, sulfone, amide, ester and alcohol, and the second component is at least one of alkali metal salt, alkaline earth metal salt, manganese salt, cobalt salt, copper salt and iron salt of organic acid. The composition with catalytic oxidation and the method for acid preparation by aldehyde can improve the conversion rate of aldehyde and the selectivity of acid, avoid the introduction of a large amount of metal impurities, and reduce the processing difficulty of subsequent processes.

Description

Technical Field

[0001] This invention relates to the field of catalytic oxidation, and more specifically, to a composition having catalytic oxidation activity and its application in the oxidation of aldehydes to produce acids. Background Technology

[0002] Acids are an important type of compound. The oxidation of aldehydes to produce acids, as an important acid production route, has been studied for many years. For example, the oxidation of acetaldehyde to acetic acid has become a mature industrial technology with large production capacity.

[0003] The reaction mechanism of aldehyde liquid-phase oxidation to produce acids is a free radical mechanism, and its catalytic system mainly consists of carboxylates, such as sodium carboxylate, potassium carboxylate, and manganese carboxylate. This reaction involves a BV rearrangement process. The rearrangement of H atoms yields the corresponding acid product of the aldehyde, while the rearrangement of alkyl groups yields formate ester byproducts. Therefore, selectively controlling the H rearrangement rather than the alkyl rearrangement is key to improving the selectivity of this reaction, especially for the selective oxidation of higher aldehydes to produce acids.

[0004] US5504229 discloses a method for preparing aliphatic C2-C22 carboxylic acids, in which the corresponding aldehyde is oxidized with oxygen in a liquid phase system in the presence of an alkali metal salt or alkaline earth metal salt (approximately 0.5-5%), and the reaction mixture is separated by distillation. CN115916736A also discloses that the addition of potassium and sodium salts (approximately 0.05-0.5%) can significantly improve the selectivity of isooctanoic acid.

[0005] These methods inevitably introduce a large amount of metal ions into the reaction system. Although some metal ions are removed through refining processes such as distillation, a considerable amount of metal ions will still remain in the product due to the intermolecular interactions between organic acids and carboxylates. This has a significant impact on the quality of high-quality acid compound products.

[0006] Therefore, a method for producing acid by aldehyde oxidation that can both improve selectivity and reduce the amount of metal impurities added is very meaningful. Summary of the Invention

[0007] The purpose of this invention is to overcome the aforementioned problems in the prior art and to provide a composition with catalytic oxidation activity and its application in aldehyde oxidation to produce acid.

[0008] To achieve the above objectives, the present invention provides a composition having catalytic oxidation activity, the composition comprising a first component and a second component, wherein the weight ratio of the first component and the second component is 0.0001-20, the first component is at least one selected from ketones, sulfones, amides, esters and alcohols, and the second component is at least one selected from alkali metal salts, alkaline earth metal salts, manganese salts, cobalt salts, copper salts and iron salts of organic acids.

[0009] A second aspect of the present invention provides a method for preparing carboxylic acids by oxidizing aldehydes, the method comprising: reacting an aldehyde with an oxidant in the presence of a catalyst and a solvent, wherein the catalyst is the aforementioned composition.

[0010] A third aspect of the present invention provides the use of the aforementioned composition or method in improving the conversion rate of raw materials and / or the selectivity of target products in the preparation of carboxylic acids by aldehyde oxidation.

[0011] The above technical solution enables high aldehyde conversion rate and high selectivity for the target product acid. By employing the composition with catalytic oxidation effect and the method for aldehyde-to-acid conversion described in this invention, the conversion rate of aldehyde and acid selectivity can be improved while avoiding the introduction of large amounts of metal impurities and reducing the difficulty of subsequent processing. Detailed Implementation

[0012] 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.

[0013] The present invention provides a composition having catalytic oxidation activity, the composition comprising a first component and a second component, wherein the weight ratio of the first component and the second component is 0.0001-20, the first component is at least one selected from ketone, sulfone, amide, ester and alcohol, and the second component is at least one selected from alkali metal salt, alkaline earth metal salt, manganese salt, cobalt salt, copper salt and iron salt of organic acid.

[0014] According to the present invention, preferably, the weight ratio of the first component and the second component is 0.1-15, which can be any two values ​​formed by 0.1, 0.3, 0.5, 1, 1.5, 3, 5, 8, 10, 12, 15, or values ​​within the range. The weight ratio of the first component and the second component in the composition is within the preferred range of the present invention, and the composition has better catalytic oxidation effect while introducing less metal impurities.

[0015] In this invention, the first component has an oxygen-containing functional group. Preferably, the first component has 1-20 carbon atoms, wherein the oxygen content is 0.5-30% by mass. More preferably, the first component is selected from at least one of acetone, butanone, cyclohexanone, cyclohexanedione, sulfolane, 3-heptanone, methyl terpentine, isobutyrate formamide, pyruvic acid, triheptyl formate, octanol, isooctyl alcohol, and dimethyl sulfoxide.

[0016] According to the present invention, preferably, the organic acid of the organic acid residue of the second component is a C1-C20 organic acid, and more preferably, the second component is at least one selected from sodium isooctanoate, potassium isooctanoate, manganese isooctanoate, cobalt isooctanoate, copper isooctanoate, sodium nonanoate, sodium isonononanoate, cobalt nonanoate, cobalt isononononate, iron nonanoate, and iron isooctanoate.

[0017] In this invention, the composition includes a first component and a second component, which form a complex effect, resulting in better aldehyde conversion and acid selectivity.

[0018] A second aspect of the present invention provides a method for preparing carboxylic acids by oxidizing aldehydes, the method comprising: reacting an aldehyde with an oxidant in the presence of a catalyst and a solvent, wherein the catalyst is a composition as described above.

[0019] According to the present invention, preferably, the weight ratio of the aldehyde to the solvent is 0.1-50:100, which can be any two values ​​formed by 0.1:100, 1:100, 5:100, 8:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, and 50:100, or values ​​within that range, and is more preferably 5-40:100. In the present invention, the weight ratio of aldehyde to solvent within the above range can further improve the conversion rate of the aldehyde and the selectivity of the acid.

[0020] According to the present invention, preferably, the amount of oxidant used is 0.5-8 mol relative to each mole of aldehyde. The amount of oxidant used within the above range is more conducive to improving the conversion rate of aldehyde and the selectivity of acid. More preferably, the amount of oxidant used is 0.5-2 mol.

[0021] According to the present invention, preferably, the aldehyde has 2-22 carbon atoms; more preferably, the aldehyde is at least one selected from propionaldehyde, n-butyraldehyde, 2-methylpropionaldehyde, n-pentanaldehyde, 3-methylbutyraldehyde, 2-methylbutyraldehyde, 2,2-dimethylpropionaldehyde, hexanal, 2-methylpentanaldehyde, 3-methylpentanaldehyde, 4-methylpentanaldehyde, 2,3-dimethylbutyraldehyde, 3,3-dimethylbutyraldehyde, heptanaldehyde, 2-methylhexanaldehyde, octanaldehyde, 2-methylheptanaldehyde, 2-ethylhexanaldehyde, 2-ethyl-4-methylpentanaldehyde, 2-propylpentanaldehyde, nonanaldehyde, 3,5,5-trimethylhexanaldehyde, decanal, 2-propylheptanaldehyde, 2-propyl-4-methylhexanaldehyde, undecaneal, 2-methyldecanaldehyde, dodecaneal, and 2-butyloctanaldehyde; more preferably, 2-ethylhexanaldehyde.

[0022] In this invention, the solvent has 2-22 carbon atoms. It is understood that the solvent is selected from the acid corresponding to the aldehyde, which is beneficial for the subsequent separation of the target product. More preferably, the solvent is at least one selected from propionic acid, n-butyric acid, 2-methylpropionic acid, n-valeric acid, 3-methylbutyric acid, 2-methylbutyric acid and 2,2-dimethylpropionic acid, hexanoic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, heptanoic acid, 2-methylhexanoic acid, octanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 2-ethyl-4-methylvaleric acid, 2-propylvaleric acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, 2-propylheptanoic acid, 2-propyl-4-methylhexanoic acid, undecanoic acid, 2-methyldecanoic acid, dodecanoic acid and 2-butyloctanoic acid, more preferably 2-ethylhexanoic acid.

[0023] According to the present invention, preferably, the oxidant is a gas containing oxygen, which can be air, oxygen-enriched air, or oxygen mixed with nitrogen; more preferably, the oxygen content in the oxidant is 10-60% by volume.

[0024] According to the present invention, preferably, the amount of the first component is 0.001-14g relative to 15g of aldehyde. The amount of the first component within the above range can further improve the catalytic oxidation performance of aldehyde. More preferably, it is 0.001-3g, and more preferably, it is 0.01-1g.

[0025] According to the present invention, preferably, the contact reaction conditions include: a temperature of 35-120°C, a pressure of 0-6 MPa, and a time of 1-5 h; more preferably, the contact reaction conditions include: a temperature of 45-70°C, a pressure of 3-5 MPa, and a time of 1.5-3 h. Contact reaction conditions within the above ranges can achieve higher aldehyde conversion rates and acid selectivity.

[0026] According to the present invention, preferably, the contact reaction is carried out in a batch reactor, a microchannel reactor, or a reflux reactor.

[0027] In this invention, the contact method can either involve first mixing the aldehyde, solvent, and catalyst together to react with the oxidant, or adding the aldehyde, solvent, and catalyst separately into the reactor and then reacting with the oxidant.

[0028] In this invention, the reaction product is further subjected to vacuum distillation after the contact reaction. The target product acid is obtained by vacuum distillation. The vacuum distillation is a conventional distillation method in the art. Preferably, the distillation conditions are: temperature of 90-150℃ and pressure of -0.09MPa to 0.1MPa (atmospheric pressure).

[0029] A third aspect of the present invention provides the use of the compositions or methods described above in improving the feed conversion rate and / or the selectivity of the target product in the oxidation of aldehydes to carboxylic acids.

[0030] The present invention will be described in detail below through examples. Unless otherwise specified, all reagents used in the following examples and comparative examples are from the same batch and are commercially available.

[0031] Conversion rate refers to the percentage of aldehydes that have reacted out relative to the total amount of aldehydes fed into the feed.

[0032] Selectivity refers to the percentage of aldehydes used to generate the target compound that are reacted out of the total aldehydes.

[0033] Gas chromatography was used to detect the concentrations of each substance in the reaction mixture before and after the reaction, and the conversion rate and selectivity were calculated.

[0034] The metal content of the mixture before and after the reaction can be determined by ICP.

[0035] Example 1

[0036] 15g of isooctaldehyde, 0.75g of cyclohexanone, 0.075g of sodium isooctanoate, and 60g of isooctanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 30mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 4.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0037] Example 2

[0038] 15g of isooctaldehyde, 0.75g of cyclohexanone, 0.075g of potassium isooctanoate, and 60g of isononanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 30mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 4.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0039] Example 3

[0040] 15g of isooctaldehyde, 0.75g of sulfolane, 0.075g of potassium isooctanoate, and 60g of isooctanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 30mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 4.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0041] Example 4

[0042] 15g of isooctaldehyde, 0.75g of 3-heptanone, 0.075g of potassium isooctanoate, and 60g of isooctanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 30mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 4.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0043] Example 5

[0044] 15g of isooctaldehyde, 0.75g of methyl pentovalinate, 0.075g of potassium isooctanoate, and 60g of isooctanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 30mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 4.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0045] Example 6

[0046] 15g of isooctaldehyde, 0.75g of isobutyric acid formamide, 0.075g of potassium isooctanoate, and 60g of isooctanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 30mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 4.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0047] Example 7

[0048] 15g of isooctaldehyde, 0.75g of cyclohexanone, 0.075g of sodium isooctanoate, and 60g of isooctanoic acid were mixed and added to a high-pressure reactor lined with polytetrafluoroethylene. Air was bubbled into the bottom of the reactor at a flow rate of 35mL / min using a flow meter, and stirring was started. The pressure inside the reactor was adjusted to 3.5MPa using a back pressure valve. The reactor was heated using a jacket, and the heat of reaction was removed using an internal coil. The reaction temperature was controlled at 50℃, and the reaction time was 2 hours. The concentrations of each substance before and after the reaction were detected by gas chromatography, and the conversion rate and selectivity were calculated. The product after the reaction was placed in a glass flask, and a glass vacuum distillation apparatus was set up for vacuum distillation. The middle distillate was collected. The metal content of the mixture after the reaction, the metal content of the vacuum distillation residue, and the metal content of the middle distillate were detected by ICP. The results are shown in Table 1.

[0049] Example 8

[0050] The method was the same as in Example 1, except that the second component of the catalyst was manganese isooctanoate. The reaction results and metal content results are shown in Table 1.

[0051] Example 9

[0052] The method was followed in Example 1, except that the catalyst was 1.5 g of cyclohexanone and 0.075 g of sodium isooctanoate. The reaction results and metal content results are shown in Table 1.

[0053] Example 10

[0054] The method was followed in Example 1, except that the catalyst was 0.038 g of cyclohexanone and 0.075 g of sodium isooctanoate. The reaction results and metal content results are shown in Table 1.

[0055] Example 11

[0056] The method was followed in Example 1, except that the aldehyde was replaced with isononanal and the acid was replaced with isononanoic acid. The reaction results and metal content results are shown in Table 1.

[0057] Comparative Example 1

[0058] The method was followed as in Example 1, except that no catalyst was added. The results are shown in Table 1.

[0059] Comparative Example 2

[0060] The method was followed in Example 1, except that the catalyst was 0.75 g of sodium isooctanoate. The reaction results and metal content results are shown in Table 1.

[0061] Comparative Example 3

[0062] The method was followed in Example 1, except that the catalyst was 0.075 g of sodium isooctanoate. The reaction results and metal content results are shown in Table 1.

[0063] Comparative Example 4

[0064] The method was followed in Example 1, except that the catalyst was 0.075 g sodium isononanoate and the solvent was 60 g isononanoic acid. The reaction results and metal content results are shown in Table 1.

[0065] Comparative Example 5

[0066] The method was followed in Example 1, except that the catalyst was 0.075 g of sodium acetate. The reaction results and metal content results are shown in Table 1.

[0067] Comparative Example 6

[0068] The method was followed in Example 1, except that 0.825 g of cyclohexanone was used as the catalyst. The reaction results and metal content results are shown in Table 1.

[0069] Comparative Example 7

[0070] The method was followed in Example 1, except that the first component was replaced with tert-butylthiol. The reaction results and metal content results are shown in Table 1.

[0071] Comparative Example 8

[0072] The method was followed in Example 1, except that the second component was replaced with aluminum isooctanoate. The reaction results and metal content results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] As shown in Table 1, the composition and method for catalytic oxidation of aldehydes to produce acids of the present invention can achieve higher aldehyde conversion and acid selectivity while introducing less metal impurities. The examples and comparative examples demonstrate that the composition with catalytic oxidation provided by the present invention can prepare organic acids with high selectivity and less introduced metal impurities. Comparing Examples 1, 9, and 10 reveals that the ratio of the first and second components in the composition is within the preferred range of the present invention, resulting in higher aldehyde conversion and acid selectivity.

[0077] 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 composition having catalytic oxidation activity, characterized in that, The composition comprises a first component and a second component, wherein the weight ratio of the first component and the second component is 0.0001-20, the first component is at least one selected from ketones, sulfones, amides, esters and alcohols, and the second component is at least one selected from alkali metal salts, alkaline earth metal salts, manganese salts, cobalt salts, copper salts and iron salts of organic acids.

2. The composition according to claim 1, wherein, The weight ratio of the first component to the second component is 0.1-15.

3. The composition according to claim 1, wherein, The first component has 1-20 carbon atoms and an oxygen content of 0.5-30% by mass; Preferably, the first component is selected from at least one of acetone, butanone, cyclohexanone, cyclohexanedione, sulfolane, 3-heptanone, methyl tervastatin, isobutyrate formamide, pyruvic acid, triheptyl formate, octanol, isooctanol and dimethyl sulfoxide; And / or, the organic acid residues of the second component are provided to be C1-C20 organic acids; Preferably, the second component is at least one selected from sodium isooctanoate, potassium isooctanoate, manganese isooctanoate, cobalt isooctanoate, copper isooctanoate, sodium nonanoate, sodium isonononanoate, cobalt nonanoate, cobalt isononononate, ferric nonanoate, and ferric isooctanoate.

4. A method for preparing carboxylic acids by aldehyde oxidation, characterized in that, The method comprises reacting an aldehyde with an oxidant in the presence of a catalyst and a solvent, wherein the catalyst is a composition according to any one of claims 1-3.

5. The method according to claim 4, wherein, The weight ratio of the aldehyde to the solvent is 0.1-50:100; Preferably, the weight ratio of the aldehyde to the solvent is 5-40:100; And / or, the amount of the oxidant used is 0.5-8 mol relative to each mole of aldehyde; Preferably, the amount of the oxidant is 0.5-2 mol relative to each mole of aldehyde.

6. The method according to claim 4, wherein, The aldehyde has 2-22 carbon atoms; Preferably, the aldehyde is at least one selected from the following: propionaldehyde, n-butyraldehyde, 2-methylpropionaldehyde, n-pentanaldehyde, 3-methylbutyraldehyde, 2-methylbutyraldehyde, 2,2-dimethylpropionaldehyde, hexanal, 2-methylpentanaldehyde, 3-methylpentanaldehyde, 4-methylpentanaldehyde, 2,3-dimethylbutyraldehyde, 3,3-dimethylbutyraldehyde, heptanaldehyde, 2-methylhexanaldehyde, octanaldehyde, 2-methylheptanaldehyde, 2-ethylhexanaldehyde, 2-ethyl-4-methylpentanaldehyde, 2-propylpentanaldehyde, nonanaldehyde, 3,5,5-trimethylhexanaldehyde, decanal, 2-propylheptanaldehyde, 2-propyl-4-methylhexanaldehyde, undecanoaldehyde, 2-methyldecanaldehyde, dodecanoaldehyde, and 2-butyloctanaldehyde. More preferably, the aldehyde is 2-ethylhexanal.

7. The method according to claim 4, wherein, The solvent is at least one selected from the following: propionic acid, n-butyric acid, 2-methylpropionic acid, n-valeric acid, 3-methylbutyric acid, 2-methylbutyric acid and 2,2-dimethylpropionic acid, hexanoic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, heptanoic acid, 2-methylhexanoic acid, octanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 2-ethyl-4-methylvaleric acid, 2-propylvaleric acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, 2-propylheptanoic acid, 2-propyl-4-methylhexanoic acid, undecanoic acid, 2-methyldecanoic acid, dodecanoic acid and 2-butyloctanoic acid; Preferably, the solvent is the acid corresponding to the aldehyde of claim 6; More preferably, the solvent is 2-ethylhexanoic acid; And / or, the oxidant is a gas containing oxygen; Preferably, the oxygen content in the oxidant is 10-60% by volume.

8. The method according to claim 4, wherein, The amount of the first component relative to 15g of aldehyde is 0.001-14g, preferably 0.001-3g, and more preferably 0.01-1g.

9. The method according to claim 4, wherein, The conditions for the contact reaction include: temperature 1240-890°C. I97304BHY Temperature range: 35-120℃; pressure range: 0-6MPa; time range: 1-5h. Preferably, the conditions for the contact reaction include: a temperature of 45-70°C, a pressure of 3-5 MPa, and a time of 1.5-3 h; And / or, the contact reaction is carried out in a batch reactor, a microchannel reactor, or a reflux reactor.

10. The use of the composition according to any one of claims 1-3 or the method according to any one of claims 4-9 in improving the feed conversion rate and / or the selectivity of the target product in the preparation of carboxylic acids by aldehyde oxidation.

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