阅读说明：本技术 氧化环烷烃的方法 (Process for oxidizing cycloalkanes ) 是由 S·周其尔 A·科马 M·博罗纳特 S·马斯特罗扬尼 J·T·洛佩兹奥森斯 于 2019-01-28 设计创作，主要内容包括：本发明涉及氧化环烷烃以形成包含相应的醇和酮的产物混合物的方法,所述方法包含在包含金的多相催化剂的存在下使所述环烷烃与氢过氧化物接触。(The present invention relates to a process for oxidizing a cycloalkane to form a product mixture comprising a corresponding alcohol and ketone, said process comprising contacting said cycloalkane with a hydroperoxide in the presence of a heterogeneous catalyst comprising gold.)

1. A process for oxidizing a cycloalkane to form a product mixture comprising the corresponding alcohol and ketone, said process comprising contacting said cycloalkane with a hydroperoxide in the presence of a heterogeneous catalyst comprising gold supported on an oxide, wherein said oxidation is carried out in a reaction mixture comprising cycloalkane and hydroperoxide and at a temperature of from 80 ℃ to 110 ℃.

2. The method of claim 1, wherein the cycloalkane is cyclohexane, the corresponding alcohol is cyclohexanol, and the corresponding ketone is cyclohexanone.

3. The process according to claim 1 or 2, wherein the hydroperoxide is a compound of formula (I)

R-O-O-H (I)

Wherein R is a hydrocarbyl group containing 1 to 15 carbon atoms.

4. The method of claim 3, wherein the hydrocarbyl group is an alkyl or aryl group.

5. The process according to claim 1 or 2, wherein the hydroperoxide is cyclohexyl hydroperoxide or tert-butyl hydroperoxide.

6. The process of any one of the preceding claims, wherein the reaction temperature is from 85 ℃ to 105 ℃.

7. The method according to any one of the preceding claims, wherein the oxide is selected from TiO₂、ZnO、MgO、CeO₂And ZrO₂。

8. The method of any one of the preceding claims, wherein the reaction mixture further comprises a free radical scavenger.

9. The process of any one of the preceding claims, wherein the product mixture comprises less than 7 wt% of by-products formed during the reaction.

10. The process of any of the preceding claims, wherein the heterogeneous catalyst comprises from 0.01 to 10 wt.% gold, based on the total weight of the heterogeneous catalyst.

11. The process according to any of the preceding claims, wherein the conversion of the reaction is from 50 to 100%.

12. The process of any one of claims 2 to 11, further comprising oxidizing the alkanol/cyclohexanone mixture to adipic acid with nitric acid.

13. Use of a heterogeneous catalyst comprising gold supported on an oxide for converting a cycloalkane to a corresponding cycloalkanol.

14. Use of a heterogeneous catalyst comprising gold supported on an oxide for the oxidation of cycloalkanes.

Technical Field

The present invention relates to a process for oxidizing a cycloalkane to form a product mixture comprising a corresponding alcohol and ketone, said process comprising contacting said cycloalkane with a hydroperoxide in the presence of a heterogeneous catalyst comprising gold.

Background

The liquid-phase aerobic oxidation of cyclohexane to cyclohexanone and cyclohexanol mixtures (known as K/A-oils) is a relevant process in the chemical industry. Cyclohexanol and cyclohexanone are precursors of adipic acid and caprolactam, which are key intermediates in the production of nylon-6 and nylon-6, 6 polyamides. The first step in this process is the hot air oxidation of cyclohexane to cyclohexyl hydroperoxide (CyOOH). The hydroperoxide is then decomposed to K/a oil according to scheme (1) below:

currently, the deperoxidation step is carried out by means of a catalyst containing Co²⁺Cationic NaOH aqueous solution or Cr-containing solution⁶⁺Organic solution catalysis of compounds, but for environmental reasons it is necessary to replace this homogeneous process with new non-toxic heterogeneous catalytic systems.

To date, most efforts have focused on the use of metal-exchanged molecular sieves, polymers, and silica-supported transition metal complexes or transition metal oxides and hydroxides. Although some of these materials show relatively good activity and selectivity for K/a oil, most of them undergo deactivation and/or metal leaching, thus hindering their industrial application.

It is well known that gold catalysts undergo deperoxidation reactions.

Disclosure of Invention

The main reaction is the dehydration of CyOOH to cyclohexanone (scheme (2), reaction (a), below). The inventors have found that during deperoxidation, the oxygen in the hydroperoxide can be used to simultaneously oxidize the alkane solvent (scheme 2, reaction (b)) to obtain a selectivity to K/A-oil of greater than 100%. This selectivity has been described for homogeneous catalysts containing Ru and Os. The advantageous reaction (b) is of interest because it enables an increase in the yield of K/A-oil. It has further been found that good conversion and efficiency can be obtained when a gold catalyst supported on a metal oxide is used.

Accordingly, the present invention relates to the subject matter defined in the following items 1 to 27:

1. a process for oxidizing a cycloalkane to form a product mixture comprising the corresponding alcohol and ketone, the process comprising contacting a cycloalkane with a hydroperoxide in the presence of a heterogeneous catalyst comprising gold supported on an oxide, wherein the oxidation is carried out in a reaction mixture comprising the cycloalkane and the hydroperoxide at a temperature of from 80 ℃ to 110 ℃.

2. The method of clause 1, wherein the heterogeneous catalyst is present in a catalytically effective amount.

3. The method of clause 1 or 2, wherein the cycloalkane is cyclohexane, the corresponding alcohol is cyclohexanol, and the corresponding ketone is cyclohexanone.

4. The process of any of the preceding items, wherein the hydroperoxide is selected from the group consisting of t-butyl hydroperoxide, t-amyl hydroperoxide, cumene hydroperoxide, ethylbenzene hydroperoxide, cyclohexyl hydroperoxide, methylcyclohexyl hydroperoxide, tetrahydronaphthalene hydroperoxide, isobutylbenzene hydroperoxide, ethylnaphthalene hydroperoxide, and combinations thereof.

5. The process of any one of the preceding items, wherein the hydroperoxide is cyclohexyl hydroperoxide or t-butyl hydroperoxide.

6. The process of any one of the preceding items, wherein the hydroperoxide is cyclohexyl hydroperoxide.

7. The process of any one of the preceding items, wherein the reaction temperature is from 85 ℃ to 105 ℃.

8. The method of any of the preceding items, wherein the oxide is selected from TiO₂、ZnO、 MgO、CeO₂And ZrO₂。

9. The method of any one of the preceding items, wherein the oxide has a morphology selected from the group consisting of amorphous, cubic, octahedral, rod-like, and combinations thereof.

10. The method of any one of the preceding items, wherein the mixture further comprises a free radical scavenger.

11. The method of claim 10, wherein the radical scavenger is selected from the group consisting of hydroquinone, catechol, resorcinol, aminophenol, phenol, phenylenediamine, p-methoxyphenol, and combinations thereof.

12. The method of claim 10 or 11, wherein the radical scavenger is hydroquinone.

13. The process of any one of the preceding items, wherein less than 7 wt.%, preferably less than 6 wt.%, more preferably less than 5 wt.% of by-products are formed during the reaction.

14. The process of any one of the preceding items, wherein the product mixture comprises less than 7 wt.%, preferably less than 6 wt.%, more preferably less than 5 wt.% of by-products.

15. The method of any one of the preceding items, wherein the gold particles have a diameter of 0.5nm to 20 nm.

16. The method of any one of the preceding items, wherein the gold particles have a diameter of 1nm to 15 nm.

17. The method of any one of the preceding items, wherein the gold particles have a diameter of 2nm to 10 nm.

18. The method of any one of the preceding items, wherein the heterogeneous catalyst comprises 0.01 to 10 weight percent gold, based on the total weight of the heterogeneous catalyst.

19. The method of any one of the preceding items, wherein the heterogeneous catalyst comprises 0.1 to 8 wt.% gold, based on the total weight of the heterogeneous catalyst.

20. The method of any one of the preceding items, wherein the heterogeneous catalyst comprises 0.2 to 5 wt.% gold, based on the total weight of the heterogeneous catalyst.

21. The process of any one of the preceding items, wherein the conversion of the reaction is from 50 to 100%.

22. The process of any one of the preceding items, wherein the conversion of the reaction is from 90 to 100%.

23. The method of any one of the preceding items, wherein the efficiency of the reaction is greater than 100%.

24. The process of any one of the preceding items, further comprising oxidizing the cyclohexanol/cyclohexanone mixture to adipic acid with nitric acid.

25. Use of a heterogeneous catalyst comprising gold supported on an oxide for converting a cycloalkane to a corresponding cycloalkanol.

26. Use of a heterogeneous catalyst comprising gold supported on an oxide for the oxidation of cycloalkanes.

27. The use of item 25 or 26, comprising the method of any one of claims 1 to 24.

Detailed Description

The present invention relates to a process for oxidizing cycloalkanes to form a product mixture containing a corresponding alcohol and ketone. The process comprises contacting a cycloalkane with a hydroperoxide in the presence of a heterogeneous catalyst comprising gold supported on an oxide, for example a metal oxide. The oxidation is carried out in a reaction mixture comprising a cycloalkane and a hydroperoxide at a temperature of from 80 ℃ to 110 ℃.

As used herein, the term "cycloalkane" refers to a saturated cyclic hydrocarbon. Cycloalkanes generally have from 3 to about 12 carbon atoms, preferably from 3 to about 10 carbon atoms; still more preferably from about 5 to about 8 carbon atoms. Non-limiting examples of cycloalkanes include cyclopentane, cyclohexane, cycloheptane, and cyclooctane. The cycloalkane may also be cyclodecane, cyclododecane or decalin. In a preferred embodiment, the cycloalkane is cyclohexane.

The phrase "corresponding alcohol and ketone" refers to cycloalkanol and cycloalkanone, respectively, having the same number of carbon atoms as the cycloalkane from which they are derived, without additional modification. For example, if the cycloalkane is cyclohexane, the corresponding alcohol is cyclohexanol, and the corresponding ketone is cyclohexanone. If the cycloalkane is cyclooctane, the corresponding alcohol is cyclooctanol and the corresponding ketone is cyclooctanone.

The hydroperoxide of the present invention may be, for example, hydrogen peroxide or an organic hydroperoxide.

Specific examples of hydroperoxides useful in the present invention may be represented by formula (I) as follows:

R-O-O-H(I)

wherein R is a hydrocarbyl group which may contain from 1 to 15 carbon atoms, predominantly alkyl or aryl.

As used herein, the term "hydrocarbyl" refers to a group consisting of carbon and hydrogen atoms, which group may be saturated or unsaturated, straight-chain, branched or cyclic, aliphatic or aromatic. The hydrocarbyl groups of the present invention may be alkyl, alkenyl or aryl groups.

Alkyl, as used herein, refers to a straight or branched saturated aliphatic hydrocarbon. As used herein, unless otherwise specified, the term "alkyl" refers to a straight or branched alkyl group optionally substituted with one or more substituents selected from the group consisting of: lower alkyl, lower alkoxy, lower alkylthio, lower alkylsulfinyl, lower alkylsulfonyl, oxy, hydroxy, mercapto, amino optionally substituted with alkyl, carboxy, carbamoyl optionally substituted with alkyl, aminosulfonyl optionally substituted with alkyl, nitro, cyano, halogen or lower perfluoroalkyl, allowing for multiple degrees of substitution.

Aryl, as used herein, refers to a 6-carbon monocyclic or 10-carbon bicyclic aromatic ring system wherein 0, 1, 2, 3 or 4 atoms of each ring are substituted with a substituent such as O or N. Examples of aryl groups include phenyl, naphthyl, and the like.

The hydroperoxide is preferably selected from: t-butyl hydroperoxide, t-amyl hydroperoxide, cumene hydroperoxide, ethylbenzene hydroperoxide, cyclohexyl hydroperoxide, methylcyclohexyl hydroperoxide, tetralin (i.e., tetralin) hydroperoxide, isobutylbenzene hydroperoxide, and ethylnaphthalene hydroperoxide.

More preferably, the hydroperoxide is an alkyl hydroperoxide, such as t-butyl hydroperoxide or cyclohexyl hydroperoxide.

Two or more of these hydroperoxides may also be used in combination.

Hydroperoxides are advantageously used in the alkane solution. Any alkane may be used, preferably cyclohexane. The concentration of peroxide in the alkane solution, preferably cyclohexane solution, is advantageously between 0.1% and 50% by weight, preferably between 2% and 15% by weight.

In a preferred embodiment, no other oxidizing agent than the hydroperoxide of the invention is used in the process of the invention. Advantageously, no other oxidizing agent is used in the process of the invention, such as pure oxygen, air, oxygen-enriched air or oxygen-depleted air or oxygen diluted with an inert gas.

The heterogeneous catalyst comprises gold on an oxide support, for example on a metal oxide support. Gold may be provided in any suitable form. For example, it may be deposited on the support by impregnation, precipitation, deposition-precipitation, ion exchange, adsorption of anions or cations from solution, and vapor deposition. Alternatively, gold-containing catalysts may be prepared by introducing a gold source at the hydrothermal synthesis stage of the support material. When using the above and other possible methods, the amount of gold introduced varies over a wide range up to about 10% by weight. Preferred amounts are from about 0.1 wt% to about 8 wt%, or from about 0.2 wt% to about 5 wt%.

The catalyst typically comprises ultrafine sized gold particles having a diameter of from about 0.5nm to about 20nm, preferably from about 1nm to about 15nm, more preferably from about 2nm to about 10 nm.

The oxide is preferably selected from TiO₂、ZnO、MgO、CeO₂And ZrO₂. The oxide may be provided as described in the examples below. Other methods of synthesizing oxides are known to the skilled person.

The oxide may have any morphology. If the oxide is cerium oxide, preferred morphologies include, but are not limited to, amorphous, cubic, octahedral, rod-like, and combinations thereof.

The reaction mixture may further comprise a scavenger that causes a reduction in by-products. Preferred scavengers include, but are not limited to, hydroquinone, catechol, resorcinol, aminophenol, phenol, phenylenediamine, p-methoxyphenol and combinations thereof. Hydroquinone is a preferred scavenger.

Preferably, less than 7 wt.%, or less than 6 wt.%, more preferably less than 5 wt.% of by-products are formed during the reaction. The product mixture preferably comprises less than 7 wt.%, or less than 6 wt.%, more preferably less than 5 wt.% of by-products. By-products include, for example, carboxylic acids, diols, lactones, peroxides.

Preferably, the process of the invention results in good conversion.

The conversion is defined as the ratio of the moles of hydroperoxide ROOH converted divided by the initial moles of ROOH.

Preferred conversions for the process of the invention are from 50% to about 100%, or from 60% to about 100%, or from 70% to about 100%, or from 80% to about 100%, or from 90% to about 100%. In other embodiments, the conversion is from 50% to less than 100%, or from 60% to less than 100%, or from 70% to less than 100%, or from 80% to less than 100%, or from 90% to less than 100%.

The process of the invention further provides good selectivity. The terms "selectivity" and "efficiency" are used synonymously herein. In the case of tBuOOH decomposition, efficiency is defined as the moles of cyclohexanol (CyOH) and cyclohexanone (CyO) produced divided by the moles of tBuOOH consumed.

If the efficiency is 0, the catalyst decomposes tBuOOH without oxidizing cyclohexane. If the efficiency is higher than 0, the catalyst is capable of simultaneously decomposing peroxide and oxidizing cyclohexane.

In the case of CyOOH decomposition, efficiency is defined as the moles of cyclohexanol (CyOH) and cyclohexanone (CyO) produced divided by the moles of CyOOH consumed.

When the efficiency is less than or equal to 1, the catalyst decomposes only CyOOH without oxidizing cyclohexane. When the efficiency is higher than 1, the catalyst is capable of simultaneously decomposing peroxide and oxidizing cyclohexane.

Preferred efficiencies of the process of the invention are from about 80% to about 125%, or from about 90% to about 120%, or from about 100% to about 115%.

In the practice of the invention, the catalyst may be contacted with the cycloalkane (e.g., cyclohexane) and hydroperoxide in a fixed bed arranged to provide intimate contact between the catalyst and the reactants. Alternatively, the catalyst may be slurried with the reaction mixture using techniques known in the art. The process of the present invention is suitable for batch or continuous oxidation of cycloalkanes. It will be apparent to those skilled in the art that these methods can be performed under a variety of conditions.

Suitable reaction temperatures for the process of the present invention are from 80 to 110 ℃, advantageously from about 85 to about 105 ℃, preferably from about 90 to about 105 ℃, more preferably from about 95 to about 105 ℃.

The process of the invention is advantageously carried out at a pressure of from 0.1MPa (1 bar) to 2MPa (20 bar), preferably from 0.1MPa (1 bar) to 1MPa (10 bar) and more preferably from 0.1MPa (1 bar) to 0.3MPa (3 bar).

The cycloalkane reactor residence time typically varies in a negative correlation with the reaction temperature, typically from 30 to 1440 minutes.

The catalyst of the present invention can be recovered and regenerated by conventionally known methods. More specifically, the catalyst may be regenerated so that it regains its original activity, for example by recovering and drying the catalyst, or by calcining the catalyst in air.

At the end of the reaction, the target compound may finally be purified by methods well known in the art, such as distillation.

To the extent that the disclosure of any patents, patent applications, and publications, which are incorporated by reference herein, conflicts with the description of the present application, the present specification controls.

Another aspect of the invention is the use of a heterogeneous catalyst comprising gold supported on an oxide for the conversion of a cycloalkane to the corresponding cycloalkanol. A further aspect of the invention is the use of a heterogeneous catalyst comprising gold supported on an oxide for the oxidation of cycloalkanes. Preferred embodiments of the use of the invention correspond, with suitable modifications, to the preferred embodiments of the process of the invention described herein.

The following examples are provided for illustrative purposes only and should not be construed as limiting the invention.