A catalyst for catalytic oxidation of cyclohexylbenzene and a preparation method and application thereof

Abstract

The application discloses a catalyst for catalyzing and oxidizing cyclohexylbenzene and a preparation method and application thereof. a M b O x , the N is Co or Mn, the M is alkali metal or alkaline earth metal, wherein a:b = 1-10, the x is the number of oxygen atoms required to meet the oxidation state of the metal elements N and M. The catalyst has good catalytic performance when catalyzing and oxidizing cyclohexylbenzene, is easy to separate, can be recycled, the preparation method is simple, the price is low, and the catalyst has industrialization prospects.

Description

Technical Field

[0001] This invention belongs to the field of cyclohexylbenzene oxidation reaction technology. Specifically, this invention relates to catalysts for the catalytic oxidation of cyclohexylbenzene, their preparation methods, and applications. Background Technology

[0002] Phenol and cyclohexanone are both important basic organic chemical raw materials. Phenol is an important intermediate in the preparation of phenolic resins, bisphenol A, and pharmaceuticals, with a domestic demand of over 2 million tons per year. Cyclohexanone is an important intermediate in the preparation of adipic acid, caprolactam, and nylon, and is also an important chemical solvent, with a domestic demand of over 4 million tons per year.

[0003] Currently, the main industrial production method for phenol is the cumene process (Hock process), which involves the oxidative decomposition of cumene to produce phenol and acetone. This method accounts for over 90% of the total phenol production capacity. This process suffers from drawbacks such as complex flow, severe corrosion, numerous byproducts, and low yield (phenol single-pass yield less than 5%). Furthermore, the cumene process co-produces large quantities of acetone, but the market demand for acetone is low, impacting the overall economic viability of the production plant. Cyclohexanone production mainly involves the cyclohexane oxidative decomposition method and the cyclohexene hydration-dehydrogenation method. The cyclohexane oxidative decomposition method suffers from low single-pass conversion (4-6%), poor selectivity, and large emissions of waste gas, wastewater, and solid waste.

[0004] Phenol and cyclohexanone can also be simultaneously produced via the oxidative decomposition of cyclohexylbenzene, and the process is similar to that of the cumene process for producing phenol and acetone. Therefore, the oxidative decomposition of cyclohexylbenzene provides a promising technical route for the simultaneous production of phenol and cyclohexanone. Many domestic and international companies and research institutions, such as Phillips Petroleum, ExxonMobil, and Sinopec, have conducted related research on this process, but industrialization has not yet been achieved.

[0005] The oxidative decomposition of cyclohexylbenzene to cyclohexanone and phenol involves two reactions: (1) cyclohexylbenzene undergoes a peroxidation reaction under oxygen conditions to generate cyclohexylbenzene hydrogen peroxide (CHBHP); (2) under acidic conditions, cyclohexylbenzene hydrogen peroxide decomposes to obtain phenol and cyclohexanone. Among these, the peroxidation reaction is a free radical reaction, and cyclohexyl has more methylene CH bonds than isopropyl, so the selective control of the peroxidation reaction at the -1 position of cyclohexyl is crucial. Currently, common processes disclosed in a series of patent applications by ExxonMobil (such as CN104030892A and US3959381) include: using air or oxygen as an oxidant, adding a small amount of initiator, such as CHBHP and azoisobutyronitrile, using N-hydroxyphthalimide (NHPI) as a catalyst, and reacting for 3-8 hours at a reaction temperature of 95-120℃ and atmospheric pressure. Although the catalytic oxidation of cyclohexylbenzene based on NHPI exhibits good conversion rates and selectivity for cyclohexylbenzene hydrogen peroxide, several challenges remain. Firstly, this step requires the presence of an initiator. Secondly, NHPI catalysts are not only expensive but also difficult to recover and recycle. Furthermore, residual NHPI catalysts from the cyclohexylbenzene oxidation to cyclohexylbenzene hydrogen peroxide step can affect the subsequent decomposition to cyclohexanone and phenol, and the separation process for NHPI catalysts is extremely cumbersome.

[0006] Therefore, developing a low-cost, easily separable, and highly active catalyst is a new research focus for the oxidation reaction of cyclohexylbenzene. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a catalyst for the catalytic oxidation of cyclohexylbenzene, its preparation method, and its application. The catalyst preparation method is simple and exhibits high catalytic activity.

[0008] A catalyst for the catalytic oxidation of cyclohexylbenzene, wherein the catalyst is a metal composite oxide, denoted as N... a M b O x N is Co or Mn, M is an alkali metal or an alkaline earth metal, a:b = 1-10, and x is the number of oxygen atoms required to satisfy the oxidation states of metal elements N and M.

[0009] Preferably, M is any one of sodium, potassium, calcium, magnesium, and lithium.

[0010] The method for preparing the catalyst for the catalytic oxidation of cyclohexylbenzene includes the following steps:

[0011] (1) Dissolve the soluble salt of N and the soluble compound of M in water, stir at 50-90℃, and evaporate the solvent to dryness;

[0012] (2) Dry and calcine to obtain the catalyst.

[0013] Preferably, the soluble compound of M is Na2CO3, NaHCO3, NaOH, KOH, K2CO3, KHCO3, Ca(OH)2, Ca(NO3)2, CaHCO3, Mg(NO3)2, Li2CO3, LiHCO3 or LiOH.

[0014] Preferably, the drying is performed at 100-110°C for 8-12 hours.

[0015] Preferably, the calcination is performed by drying in air at 500-550°C for 4-6 hours.

[0016] A method for catalytic oxidation of cyclohexylbenzene, using the catalyst described in this invention to oxidize cyclohexylbenzene to generate cyclohexylbenzene hydrogen peroxide, is as follows: cyclohexylbenzene, solvent, and catalyst are mixed, heated to 60-120°C, oxygen-containing gas is introduced under normal pressure, the reaction is carried out for 6-24 hours, filtered, the catalyst is recovered, and the filtrate contains cyclohexylbenzene hydrogen peroxide.

[0017] Preferably, the amount of catalyst used is 0.5-20% of the mass of cyclohexylbenzene.

[0018] Preferably, the solvent is at least one of acetonitrile, cyclohexane, ethanol, and methanol; the oxygen-containing gas is at least one of oxygen or air; and the amount of the oxygen-containing gas, calculated as oxygen, is 0.1-3 mL / min relative to each milliliter of cyclohexylbenzene.

[0019] More preferably, the solvent is acetonitrile or cyclohexane.

[0020] Preferably, the oxygen-containing gas is introduced into the mixed liquid system by bubbling.

[0021] Preferably, the filtrate is subjected to acid catalysis to produce phenol and cyclohexanone; this can be achieved using existing acid catalysis techniques.

[0022] More preferably, the filtrate is acid-catalyzed to produce phenol and cyclohexanone as follows: 0.1-2 mol / L dilute sulfuric acid solution is added to the filtrate, and the mixture is stirred for 2-6 hours.

[0023] Advantages of this invention:

[0024] (1) The catalyst provided by the present invention has good catalytic performance, is easy to separate, and can be recycled when catalytically oxidizing cyclohexylbenzene;

[0025] (2) The preparation method is simple and inexpensive, and has industrialization prospects. Detailed Implementation

[0026] Example 1

[0027] A catalyst for the catalytic oxidation of cyclohexylbenzene, wherein the catalyst is a composite oxide of cobalt and sodium, denoted as Co. 10 Na2O 16 ;

[0028] The method for preparing the catalyst for the catalytic oxidation of cyclohexylbenzene includes the following steps:

[0029] (1) Dissolve 10 mmol Co(NO3)2 and 1 mmol Na2CO3 in 50 mL of water, stir at 50 °C, and evaporate the solvent to dryness;

[0030] (2) Dry at 105℃ for 8 hours, then calcine at 500℃ in air atmosphere for 6 hours to obtain catalyst Co. 10 Na2O 16 .

[0031] Example 2

[0032] A catalyst for the catalytic oxidation of cyclohexylbenzene, wherein the catalyst is a composite oxide of manganese and potassium, denoted as Mn2K2O3;

[0033] The method for preparing the catalyst for the catalytic oxidation of cyclohexylbenzene includes the following steps:

[0034] (1) Dissolve 6 mmol Mn(NO3)2 and 6 mmol KOH in 40 mL of water, stir at 80 °C, and evaporate the solvent to dryness;

[0035] (2) Dry at 100℃ for 12h, then calcine at 550℃ in air atmosphere for 4h to obtain catalyst Mn2K2O3.

[0036] Example 3

[0037] A catalyst for the catalytic oxidation of cyclohexylbenzene, wherein the catalyst is a composite oxide of manganese and calcium, denoted as Mn 10 CaO 11 ;

[0038] The method for preparing the catalyst for the catalytic oxidation of cyclohexylbenzene includes the following steps:

[0039] (1) Dissolve 10 mmol Mn(NO3)2 and 1 mmol Ca(NO3)2 in 50 mL of water, stir at 90 °C, and evaporate the solvent to dryness;

[0040] (2) Dry at 110℃ for 10 h, then calcine at 500℃ in air atmosphere for 6 h to obtain catalyst Mn 10 CaO 11 .

[0041] Example 4

[0042] A catalyst for the catalytic oxidation of cyclohexylbenzene, wherein the catalyst is a composite oxide of cobalt and magnesium, denoted as Co3Mg2O 6.5 ;

[0043] The method for preparing the catalyst for the catalytic oxidation of cyclohexylbenzene includes the following steps:

[0044] (1) Dissolve 9 mmol Co(NO3)2 and 6 mmol Mg(NO3)2 in 20 mL of water, stir at 60 °C, and evaporate the solvent to dryness;

[0045] (2) Dry at 105℃ for 10h, then calcine at 500℃ in air atmosphere for 5h to obtain catalyst Co3Mg2O 6.5 .

[0046] Example 5

[0047] A catalyst for the catalytic oxidation of cyclohexylbenzene, wherein the catalyst is a composite oxide of cobalt and lithium, denoted as Co₂LiO. 3.5 ;

[0048] The method for preparing the catalyst for the catalytic oxidation of cyclohexylbenzene includes the following steps:

[0049] (1) Dissolve 20 mmol Co(NO3)2 and 5 mmol Li2CO3 in 50 mL of water, stir at 60 °C, and evaporate the solvent to dryness;

[0050] (2) Dry at 105℃ for 12 h, then calcine at 550℃ in air atmosphere for 5 h to obtain catalyst Co2LiO 3.5 .

[0051] Catalytic performance test

[0052] The preparation of cyclohexylbenzene hydrogen peroxide (CHBHP) by catalytic oxidation of cyclohexylbenzene using the catalyst described in this invention is as follows:

[0053] Mix 20 mL of cyclohexylbenzene, solvent, and catalyst, and heat in an oil bath to 60-120 °C under magnetic stirring. Introduce oxygen-containing gas at atmospheric pressure. The oxygen-containing gas is calculated as oxygen and the amount used is 0.1-3 mL / min relative to each milliliter of cyclohexylbenzene. React for 6-24 h, filter, and recover the catalyst. The filtrate contains cyclohexylbenzene hydrogen peroxide. Specific reaction conditions and results are shown in Table 1.

[0054] Table 1 Reaction conditions and results

[0055] catalyst Catalyst as a percentage of cyclohexylbenzene solvent oxygen gas Oxygen content, oxygen gas dosage (mL / min) Temperature, time Cyclohexylbenzene conversion rate % CHBHP selectivity % Example 1 5% Acetonitrile oxygen 0.5 mL / min 120℃，6h 12.0 95.4 Example 2 15% Cyclohexane oxygen 1.0 mL / min 60℃，10h 18.2 96.2 Example 3 10% ethanol oxygen 0.1 mL / min 100℃，16h 9.6 94.1 Example 4 0.5% methanol oxygen 1.5 mL / min 80℃，20h 27.9 93.8 Example 5 20% Acetonitrile Air 2mL / min 90℃，18h 23.7 90.4 Example 6 20% Acetonitrile oxygen 3mL / min 100℃，24h 45.5 93.5

Claims

1. A method for the catalytic oxidation of cyclohexylbenzene, characterized in that: Cyclohexylbenzene is oxidized using a catalyst to produce cyclohexylbenzene hydrogen peroxide, specifically as follows: Cyclohexylbenzene, solvent, and catalyst are mixed and heated to 60-120°C. Oxygen-containing gas is introduced under normal pressure, and the reaction is allowed to proceed for 6-24 hours. After filtration, the catalyst is recovered, and the filtrate contains cyclohexylbenzene hydrogen peroxide. The catalyst is a metal composite oxide, denoted as N0. a M b O x N is Co or Mn, M is an alkali metal, a:b = 1-10, and x is the number of oxygen atoms required to satisfy the oxidation states of metal elements N and M.

2. The method for catalytic oxidation of cyclohexylbenzene according to claim 1, characterized in that: M can be any one of sodium, potassium, or lithium.

3. The method for catalytic oxidation of cyclohexylbenzene according to claim 1, characterized in that: The catalyst was prepared by the following method: (1) Dissolve the soluble salt of N and the soluble compound of M in water, stir at 50-90℃, and evaporate the solvent to dryness; (2) Dry and calcine to obtain the catalyst.

4. The method for catalytic oxidation of cyclohexylbenzene according to claim 3, characterized in that: The soluble compound of M is Na2CO3, NaHCO3, NaOH, KOH, K2CO3, KHCO3, Li2CO3, LiHCO3, or LiOH.

5. The method for catalytic oxidation of cyclohexylbenzene according to claim 4, characterized in that: The drying process involves drying at 100-110℃ for 8-12 hours.

6. The method for catalytic oxidation of cyclohexylbenzene according to claim 5, characterized in that: The calcination is performed by drying in air at 500-550°C for 4-6 hours.

7. The method for catalytic oxidation of cyclohexylbenzene according to claim 1, characterized in that: The amount of catalyst used is 0.5-20% of the mass of cyclohexylbenzene.

8. The method for catalytic oxidation of cyclohexylbenzene according to claim 1, characterized in that: The solvent is at least one of acetonitrile, cyclohexane, ethanol, and methanol; the oxygen-containing gas is at least one of oxygen or air; the oxygen-containing gas, calculated as oxygen, is used at a rate of 0.1-3 mL / min relative to each milliliter of cyclohexylbenzene.

9. The method for catalytic oxidation of cyclohexylbenzene according to claim 1, characterized in that: The filtrate was then subjected to acid catalysis to produce phenol and cyclohexanone.