A solid base catalyst for preparing ketone from hydrocarbon oxidation and a preparation method and application thereof

Abstract

The application provides a solid base catalyst for preparing ketones from hydrocarbons, and a preparation method and application thereof. The catalyst comprises magnesium-aluminum spinel, rare earth metal oxides loaded on the magnesium-aluminum spinel, and doped transition metals. The content of each component in the catalyst is as follows: the rare earth metal oxides are 5-25%, the transition metals are 0.5-10%, and the rest is the magnesium-aluminum spinel. The catalyst provided by the application can realize the oxidation of naphthenes, aromatic hydrocarbons and aromatic hydrocarbon derivatives to prepare ketone compounds by using green oxidants such as oxygen or air. The catalyst has high catalytic activity and high selectivity, the product is easy to separate, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, specifically relating to a method for preparing and applying a solid base catalyst for the oxidation of hydrocarbons to ketones. Background Technology

[0002] Ketones are an important class of organic chemical raw materials, widely used in organic synthesis and pharmaceutical preparation. They can also serve as good organic solvents and monomers for polymers.

[0003] The selective oxidation of hydrocarbon feedstocks to prepare ketones is a green synthetic method with good atom economy. The selective oxidation of methyl or methylene groups in hydrocarbon molecules to prepare ketones is essentially the activation of the CH bond. Alkane molecules have low electron cloud density, making the activation of their CH bonds more difficult. The CH bonds of methyl or methylene groups on the benzene ring undergo oxidation relatively easily due to the conjugation effect with the π electrons of the benzene ring. However, when electron-withdrawing groups are present on the benzene ring, the electron density on the benzene ring decreases, increasing the difficulty of activating and oxidizing the conjugated methyl or methylene groups.

[0004] Traditional hydrocarbon oxidation reactions often rely on transition metal catalysts (such as Cr and Mn-based catalysts) or homogeneous acid / base systems, which suffer from problems such as high catalyst toxicity, harsh reaction conditions (high temperature and pressure), and numerous byproducts (such as acid anhydrides and carboxylic acids). Patent CN113321574A discloses a method for the catalytic oxidation of 4,4′-dichlorodiphenylmethane to prepare 4,4′-dichlorobenzophenone, using a manganese, cobalt, and vanadium compound as the catalyst. Patent CN113304759A discloses a method for the catalytic oxidation of diphenylmethane to prepare benzophenone, using a cobalt and manganese bimetallic catalyst supported on a γ-Al₂O₃ support. The oxidation of diphenylmethane to benzophenone under solvent-free conditions involves oxygen oxidation, requiring high pressure and stringent conditions.

[0005] In recent years, solid base catalysts have attracted attention due to their high activity, reusability, and environmental friendliness, particularly their ability to catalyze the deprotonation of CH bonds to generate carbanion intermediates. However, their application in the selective oxidation of hydrocarbons still faces the following challenges: firstly, the activation efficiency of CH bonds in hydrocarbons is low; secondly, excessive oxidation products (such as carboxylic acids) are easily generated during the oxidation process; and thirdly, there are problems such as insufficient catalyst stability and easy deactivation.

[0006] Therefore, there is an urgent need to develop a highly efficient and selective solid base catalytic system to achieve the selective conversion of hydrocarbons into ketones. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a solid base catalyst for the oxidation of hydrocarbons to ketones, its preparation method, and its application. This catalyst, in the presence of an oxidant, can selectively oxidize hydrocarbons to ketones, exhibiting high catalytic activity, high selectivity, and easy product separation.

[0008] A solid base catalyst for the oxidation of hydrocarbons to prepare ketones comprises magnesium aluminum spinel, rare earth metal oxides supported on the magnesium aluminum spinel, and a doped transition metal. The mass of the catalyst is 100%, and the contents of each component are as follows: rare earth metal oxides 5~25%, transition metals 0.5~10%, and the balance is magnesium aluminum spinel.

[0009] Preferably, the rare earth metal oxide is CeO2 or La2O3.

[0010] Preferably, the transition metal is any one of Fe, Co, Zn, Mn, Ni, and Cu.

[0011] The method for preparing the solid base catalyst for the oxidation of hydrocarbons to ketones includes the following steps: (1) Dissolve rare earth metal nitrates in water to obtain solution A; (2) Dissolve the nitrate of a transition metal in water to obtain solution B; (3) Add magnesium aluminum spinel to solution A, add precipitant dropwise at 60~90℃, adjust the pH of the system to 8~10, and stir the reaction for 4~24h; then add solution B to it, add precipitant dropwise at 60~90℃, adjust the pH of the system to 8~10, and stir the reaction for 4~24h. (4) Filter, wash, dry, and calcine in a mixed atmosphere of hydrogen and nitrogen to obtain the catalyst.

[0012] Preferably, the precipitant is a sodium carbonate solution, a sodium bicarbonate solution, or ammonia.

[0013] Preferably, the drying is performed at 100~120℃ for 10~12 hours; the calcination is performed at 400~600℃ for 4~6 hours.

[0014] A method for preparing ketones by oxidizing hydrocarbons: adding raw hydrocarbon compounds, catalysts, and solvents into a reaction vessel, introducing oxygen-containing gas, controlling the oxygen partial pressure to be 0.1~0.5 MPa, reacting at 80~190℃ for 3~10 h, filtering to recover the catalyst, and collecting the filtrate; wherein, the catalyst is the above-mentioned catalyst, and the mass of the catalyst is 1~25% of the mass of the hydrocarbon compounds.

[0015] Preferably, the hydrocarbon compound is a cycloalkanes, aromatic hydrocarbons, or aromatic hydrocarbon derivatives containing methylene groups.

[0016] More preferably, the hydrocarbon compound is any one of cyclohexane, ethylbenzene, p-chloroethylbenzene, p-fluoroethylbenzene, diphenylmethane, 4-chlorodiphenylmethane, 4,4'-dichlorodiphenylmethane, 4-fluorodiphenylmethane, or 4,4'-difluorodiphenylmethane.

[0017] Preferably, the solvent is anhydrous methanol, acetonitrile, or an ionic liquid.

[0018] More preferably, the ionic liquid is 1-ethyl-3-methylimidazolium hexafluorophosphate ([C2C1im][PF6]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmin][BF4]), N-ethylpyridine hexafluorophosphate ([C2Py][PF6]), or tetrabutylammonium bis(trifluoromethanesulfonyl)imide ([N... 4444 Any one of [NTf2]).

[0019] Preferably, the oxygen-containing gas is air or oxygen.

[0020] Advantages of this invention: The catalyst provided by this invention uses green oxidants such as oxygen or air to oxidize cycloalkanes, aromatic hydrocarbons, and aromatic hydrocarbon derivatives to prepare ketone compounds. The catalyst has high catalytic activity, high selectivity, and the products are easy to separate, showing great application prospects. Detailed Implementation

[0021] Example 1: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide CeO2 supported on the magnesium aluminum spinel, and doped transition metal Fe. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 5%, transition metal 0.5%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 1.26g of cerium nitrate in 30mL of deionized water to obtain solution A; (2) Dissolve 0.36g of ferric nitrate in 30mL of deionized water to obtain solution B; (3) Add 9.45g of magnesium aluminum spinel to solution A, add 0.1mol / L sodium carbonate solution dropwise at 80℃ to adjust the pH of the system to 8, and stir the reaction for 24h; then add solution B to it, add 0.1mol / L sodium carbonate solution dropwise at 80℃ to adjust the pH of the system to 9, and stir the reaction for 20h. (4) Filter, wash, dry at 100℃ for 12h, calcine at 400℃ for 6h under 10%H2 / N2 atmosphere to obtain the catalyst, denoted as 0.5Fe-5CeO2 / MgAl2O4.

[0022] Example 2: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide CeO2 supported on the magnesium aluminum spinel, and doped transition metal Co. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 25%, transition metal 2%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 6.31g of cerium nitrate in 30mL of deionized water to obtain solution A; (2) Dissolve 0.99g of cobalt nitrate in 30mL of deionized water to obtain solution B; (3) Add 7.3g of magnesium aluminum spinel to solution A, add 0.1mol / L sodium bicarbonate solution dropwise at 90℃ to adjust the pH of the system to 9, and stir the reaction for 10h; then add solution B to it, add 0.1mol / L sodium bicarbonate solution dropwise at 90℃ to adjust the pH of the system to 10, and stir the reaction for 12h; (4) Filter, wash, dry at 120°C for 10 h, and calcine at 500°C for 6 h under 10% H2 / N2 atmosphere to obtain the catalyst, denoted as 2Co-25CeO2 / MgAl2O4.

[0023] Example 3: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide La2O3 supported on the magnesium aluminum spinel, and doped transition metal Zn. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 5%, transition metal 5%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 0.66g of lanthanum nitrate in 30mL of deionized water to obtain solution A; (2) Dissolve 2.29g of zinc nitrate in 30mL of deionized water to obtain solution B; (3) Add 9g of magnesium aluminum spinel to solution A, add 0.1mol / L ammonia solution dropwise at 70℃ to adjust the pH of the system to 10, and stir the reaction for 14h; then add solution B to it, add 0.1mol / L ammonia solution dropwise at 70℃ to adjust the pH of the system to 10, and stir the reaction for 12h. (4) Filter, wash, dry at 120°C for 10 h, and calcine at 450°C for 5.5 h under 10% H2 / N2 atmosphere to obtain the catalyst, denoted as 5Zn-5La2O3 / MgAl2O4.

[0024] Example 4: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide CeO2 supported on the magnesium aluminum spinel, and doped transition metal Mn. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 12%, transition metal 10%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 3.03g of cerium nitrate in 30mL of deionized water to obtain solution A; (2) Dissolve 5.22g of manganese nitrate in 30mL of deionized water to obtain solution B; (3) Add 7.8g of magnesium aluminum spinel to solution A, add 0.1mol / L sodium carbonate solution dropwise at 80℃ to adjust the pH of the system to 9, and stir the reaction for 18h; then add solution B to it, add 0.1mol / L sodium bicarbonate solution dropwise at 80℃ to adjust the pH of the system to 10, and stir the reaction for 4h. (4) Filter, wash, dry at 120°C for 10 h, and calcine at 550°C for 4 h under 10% H2 / N2 atmosphere to obtain the catalyst, denoted as 10Mn-12CeO2 / MgAl2O4.

[0025] Example 5: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide La2O3 supported on the magnesium aluminum spinel, and doped transition metal Ni. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 12%, transition metal 8%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 1.59g of lanthanum nitrate in 30mL of deionized water to obtain solution A; (2) Dissolve 3.96g of nickel nitrate in 30mL of deionized water to obtain solution B; (3) Add 8g of magnesium aluminum spinel to solution A, add 0.1mol / L sodium carbonate solution dropwise at 75℃ to adjust the pH of the system to 10, and stir the reaction for 20h; then add solution B to it, add 0.1mol / L ammonia solution dropwise at 75℃ to adjust the pH of the system to 8, and stir the reaction for 8h. (4) Filter, wash, dry at 120°C for 10 h, and calcine at 600°C for 4 h under 10% H2 / N2 atmosphere to obtain the catalyst, denoted as 8Ni-12La2O3 / MgAl2O4.

[0026] Example 6: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide La2O3 supported on the magnesium aluminum spinel, and doped transition metal Cu. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 25%, transition metal 5%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 3.32g of lanthanum nitrate in 30mL of deionized water to obtain solution A; (2) Dissolve 1.89g of copper nitrate in 30mL of deionized water to obtain solution B; (3) Add 7g of magnesium aluminum spinel to solution A, add 0.1mol / L ammonia solution dropwise at 90℃ to adjust the pH of the system to 8, and stir the reaction for 4h; then add solution B to it, add 0.1mol / L sodium bicarbonate solution dropwise at 90℃ to adjust the pH of the system to 9, and stir the reaction for 16h. (4) Filter, wash, dry at 120°C for 10 h, and calcine at 550°C for 4 h under 10% H2 / N2 atmosphere to obtain the catalyst, which is denoted as 5Cu-25La2O3 / MgAl2O4.

[0027] Example 7: A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, comprising magnesium aluminum spinel, rare earth metal oxide La2O3 supported on the magnesium aluminum spinel, and doped transition metal Co. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxide 18%, transition metal 6%, and the balance is magnesium aluminum spinel. The catalyst is prepared as follows: (1) Dissolve 2.39 g of lanthanum nitrate in 30 mL of deionized water to obtain solution A; (2) Dissolve 2.96g of cobalt nitrate in 30mL of deionized water to obtain solution B; (3) Add 7.6g of magnesium aluminum spinel to solution A, add 0.1mol / L ammonia solution dropwise at 80℃ to adjust the pH of the system to 8, and stir the reaction for 16h; then add solution B to it, add 0.1mol / L sodium carbonate solution dropwise at 90℃ to adjust the pH of the system to 10, and stir the reaction for 24h. (4) Filter, wash, dry at 120°C for 10 h, and calcine at 500°C for 4.5 h under 10% H2 / N2 atmosphere to obtain the catalyst, which is denoted as 6Co-18La2O3 / MgAl2O4.

[0028] Example 8: A method for preparing ketones by hydrocarbon oxidation, comprising adding a raw hydrocarbon compound, a catalyst, and a solvent to a reaction vessel, introducing oxygen-containing gas, controlling the oxygen partial pressure at 0.1~0.5 MPa, reacting at 80~190℃ for 3~10 h, filtering to recover the catalyst, and collecting the filtrate; wherein, the catalyst is the catalyst described in the example, and the mass of the catalyst is 1~8% of the mass of the hydrocarbon compound; the hydrocarbon compound is a cycloalkanes, aromatic hydrocarbons, or aromatic hydrocarbon derivatives; the solvent is anhydrous methanol, acetonitrile, or an ionic liquid; the oxygen-containing gas is air or oxygen; specific reaction conditions and results are shown in Table 1; Table 1 Reaction conditions and results

[0029] Therefore, the solid base catalyst prepared by this invention has excellent performance in catalyzing the preparation of ketone compounds from cycloalkanes, aromatic hydrocarbons, or aromatic hydrocarbon derivatives.

Claims

1. A solid base catalyst for the oxidation of hydrocarbons to prepare ketones, characterized in that: The catalyst comprises magnesium aluminum spinel, rare earth metal oxides supported on the magnesium aluminum spinel, and doped transition metals. The mass of the catalyst is 100%, and the content of each component is as follows: rare earth metal oxides 5~25%, transition metals 0.5~10%, and the balance is magnesium aluminum spinel.

2. The solid base catalyst for the oxidation of hydrocarbons to ketones according to claim 1, characterized in that: The rare earth metal oxide is CeO2 or La2O3.

3. The solid base catalyst for the oxidation of hydrocarbons to ketones according to claim 1, characterized in that: The transition metal is any one of Fe, Co, Zn, Mn, Ni, and Cu.

4. A method for preparing a solid base catalyst for the oxidation of hydrocarbons to ketones as described in claim 1, characterized in that: Includes the following steps: (1) Dissolve rare earth metal nitrates in water to obtain solution A; (2) Dissolve the nitrate of a transition metal in water to obtain solution B; (3) Add magnesium aluminum spinel to solution A, add precipitant dropwise at 60~90℃, adjust the pH of the system to 8~10, and stir the reaction for 4~24h; then add solution B to it, add precipitant dropwise at 60~90℃, adjust the pH of the system to 8~10, and stir the reaction for 4~24h. (4) Filter, wash, dry, and calcine in a mixed atmosphere of hydrogen and nitrogen to obtain the catalyst.

5. The method for preparing the solid base catalyst for the oxidation of hydrocarbons to ketones according to claim 4, characterized in that: The precipitant is a sodium carbonate solution, a sodium bicarbonate solution, or ammonia water; the drying is carried out at 100~120℃ for 10~12 hours; the calcination is carried out at 400~600℃ for 4~6 hours.

6. A method for preparing ketones by oxidizing hydrocarbons, characterized in that: Raw material hydrocarbon compounds, catalyst, and solvent are added to a reaction vessel, oxygen-containing gas is introduced, and the oxygen partial pressure is controlled at 0.1~0.5 MPa. The reaction is carried out at 80~190℃ for 3~10 h. The catalyst is recovered by filtration, and the filtrate is collected. The catalyst is the catalyst described in claim 1, and the mass of the catalyst is 1~25% of the mass of the hydrocarbon compounds.

7. The method for preparing ketones by hydrocarbon oxidation according to claim 6, characterized in that: The hydrocarbon compound is a cycloalkanes, aromatic hydrocarbons, or aromatic hydrocarbon derivatives containing methylene groups.

8. The method for preparing ketones by hydrocarbon oxidation according to claim 7, characterized in that: The hydrocarbon compound is any one of cyclohexane, ethylbenzene, p-chloroethylbenzene, p-fluoroethylbenzene, diphenylmethane, 4-chlorodiphenylmethane, 4,4'-dichlorodiphenylmethane, 4-fluorodiphenylmethane, or 4,4'-difluorodiphenylmethane.

9. The method for preparing ketones by hydrocarbon oxidation according to claim 6, characterized in that: The solvent is anhydrous methanol, acetonitrile, or an ionic liquid.

10. The method for preparing ketones by hydrocarbon oxidation according to claim 9, characterized in that: The ionic liquid is any one of 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, N-ethylpyridine hexafluorophosphate, and tetrabutylammonium bis(trifluoromethanesulfonyl)imide.

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