Catalyst for preparing p-methoxycyclohexanone through hydrogenation as well as preparation method and application of catalyst
By developing a supported catalyst and using fixed bed atmospheric hydrogenation process, the existing safety hazards and environmental pollution problems in the synthesis process of methoxycyclohexanone were solved, and efficient and selective preparation results were achieved.
Patent Information
- Application Number
- CN202311744577.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-19
- Publication Date
- 2025-06-20
AI Technical Summary
In the existing synthesis process of methoxycyclohexanone, the methylation reagents and oxidants used have safety hazards and environmental pollution problems, and the process is complex, and the product selectivity and yield need to be improved.
A supported catalyst is developed, including a support and a supported two-component active metal, with the noble metal active components Pd or Pt, and the non-precious metal active components Zr, Zn, Mn, Cu, Cr, La, and used to prepare p-methoxycyclohexanone at normal pressure hydrogenation in fixed beds.
The preparation of p-methoxycyclohexanone with high efficiency and good selectivity under mild reaction conditions has been achieved, eliminating the safety hazards of high-pressure hydrogenation process and has the advantages of continuous production and high production efficiency.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalyst preparation, and particularly relates to a catalyst for the preparation of p-methoxycyclohexanone by fixed-bed atmospheric-pressure hydrogenation, a preparation method thereof, and an application thereof. Background Art
[0002] p-Methoxycyclohexanone is widely used as an important intermediate in pharmaceuticals and pesticides. For example, M1 receptor antagonists for the treatment of amyloid-related psychiatric geriatric diseases, visual system diseases and mental diseases, novel polymers with excellent antithrombotic properties, the insecticide and acaricide spirotetramat, and similar spirocyclic tetronic acid insecticides, etc. p-Methoxycyclohexanone has broad application prospects, and it is very necessary to vigorously develop and explore its synthesis process route.
[0003] The traditional synthesis route of p-methoxycyclohexanone uses cyclohexanediol as the starting material, and adds dimethyl sulfate or methyl iodide as the methylation reagent to obtain p-methoxycyclohexanol through selective methylation, and then uses pyridinium chlorochromate (PCC) as the oxidant to oxidize the hydroxyl group to obtain p-methoxycyclohexanone. The raw materials of this route are easy to obtain, but the two methylation reagents used are both highly dangerous and highly toxic chemicals, and the difficulty of selective methylation is very high, the reaction yield is low, and a large amount of by-product cyclohexyl dimethyl ether has no market. At the same time, the hydroxyl oxidant pyridinium chlorochromate also has carcinogenic risks, and the dosage is large, which will produce a large amount of chromium-containing industrial wastewater, polluting the environment (see: Chemical Engineering Journal, 2022, 430, 132589; Journal of the American Chemical Society, 2015, 137(29), 9250-9253).
[0004] In recent years, a strategy for preparing p-methoxycyclohexanone from p-methoxyphenol through catalytic hydrogenation and catalytic oxidation has been developed. For example, Chu Xiaoning et al. prepared a Ni / Al2O3-DP catalyst by the deposition-precipitation method, catalyzed the hydrogenation of p-methoxyphenol to p-methoxycyclohexanol, and then used hydrogen peroxide as the oxidant to oxidize p-methoxycyclohexanol to prepare p-methoxycyclohexanone, and the product selectivity reached 95.3% (see: "Fine Chemicals", 2018, 35(02), 349-356). In fact, in the first step of the above process, the catalytic hydrogenation of p-methoxyphenol to p-methoxycyclohexanol must go through the p-methoxycyclohexanone intermediate process. Therefore, if the hydrogenation process can be controlled on the p-methoxycyclohexanone intermediate, one-step preparation of p-methoxycyclohexanone can be achieved, which has the advantages of simple process, clean production, and easy separation and purification of products, and has been widely applied and concerned in recent years.
[0005] Among them, developing a catalyst with high activity, good selectivity and long life is the key to improving the yield of p-methoxycyclohexanone and realizing its industrial production. Feng Xue et al. used 5% Pd / C as the catalyst, and at 120 °C, 0.8 MPa, and a mass ratio of p-methoxyphenol to methylcyclohexane of 1:4.0, the conversion rate of the raw materials was as high as 95%, and the yield of the product reached 75% (see: Hebei University of Science and Technology, Feng Xue, Master's Thesis, 2020). Although the batch catalytic hydrogenation method has good product selectivity, the batch catalytic hydrogenation method is an intermittent operation, with a complex process, cumbersome operation, large workload, and the need for pressurized hydrogen, which poses a safety hazard. In addition, the yield of p-methoxycyclohexanone in the existing process needs to be further improved (see: ChemCatChem, 2015, 7(16), 2485-2492; Green Chemistry, 2017, 19(15), 3585-3594).
[0006] Therefore, developing a fixed-bed atmospheric-pressure hydrogenation catalyst and catalytic process with good selectivity and high production efficiency is of great significance in the production field of p-methoxycyclohexanone. Summary of the Invention
[0007] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a selective hydrogenation catalyst with good catalytic activity, high stability, good selectivity for the target product and long service life under mild reaction conditions, and its preparation method and application. And the catalyst of the present invention can be used for fixed-bed atmospheric-pressure hydrogenation to prepare p-methoxycyclohexanone, eliminating the safety hazards existing in the high-pressure hydrogenation production process, and having the advantages of continuous production, high production efficiency, etc.
[0008] The present invention is realized through the following technical solutions:
[0009] On the one hand, the present invention provides a supported catalyst for preparing p-methoxycyclohexanone, the catalyst comprising a carrier and a two-component active metal supported on the carrier, wherein one active component is a noble metal active component, and calculated by 100%, the mass percentage content of the noble metal is 0.1-10.0%, and the other active component is a non-noble metal active component, and calculated by 100%, the mass percentage content of the non-noble metal is 0.1-20%, and the rest is the carrier.
[0010] Among them, the noble metal active component in the catalyst is Pd or Pt.
[0011] Among them, the non-noble metal active component in the catalyst is one or more of Zr, Zn, Mn, Cu, Cr, La.
[0012] Among them, the carrier is Al2O3.
[0013] Preferably, the mass percentage content of the noble metal active component in the catalyst is 0.1 - 5.0%, and the mass percentage content of the non-noble metal active component is 0.1 - 10.0%.
[0014] Preferably, the mass percentage content of the noble metal active component in the catalyst is 0.1 - 1.0%, and the mass percentage content of the non-noble metal active component is 0.1 - 3.0%.
[0015] Preferably, the catalyst carrier is spherical γ-Al2O3 pellets with a diameter of 1 - 5 mm, a specific surface area of 100 - 300 m 2 / g, an average pore diameter of 5 - 20 nm, and a water absorption rate of 40 - 80%.
[0016] On the other hand, the present invention also provides a method for preparing a supported catalyst, which includes attaching active components on a carrier, and the active components include specific noble metal active components and non-noble metal active components. The noble metal active component is Pd or Pt, and the non-noble metal active component is one or more of Zr, Zn, Mn, Cu, Cr, and La.
[0017] Preferably, it includes the following steps:
[0018] (1) Preparation of precursor 1: Stir, impregnate, dry, and calcine at high temperature to constant weight a soluble salt solution of the non-noble metal active component and the carrier to obtain precursor 1;
[0019] (2) Preparation of precursor 2: Stir, impregnate, dry, and calcine at high temperature to constant weight precursor 1 and a soluble salt solution of the noble metal active component to obtain precursor 2;
[0020] (3) Pass precursor 2 through hydrogen and calcine at high temperature until constant weight to obtain the catalyst.
[0021] Preferably, it further includes the following steps:
[0022] In step (1), the drying temperature is 100 - 150 °C, the drying time is 12 - 72 h, preferably 18 - 36 h; the calcination temperature is 400 - 1000 °C, preferably 500 - 800 °C, and the calcination time is 4 - 12 h, preferably 4 - 8 h;
[0023] In step (2), the drying temperature is 100 - 150 °C, the drying time is 12 - 72 h, preferably 18 - 36 h; the calcination temperature is 300 - 800 °C, preferably 400 - 700 °C, and the calcination time is 4 - 12 h, preferably 4 - 8 h;
[0024] In step (3), the hydrogen space velocity is 0.5 - 10 min -1, the calcination temperature is 200 - 800 °C, preferably 200 - 600 °C, and the heating rate is 2 - 8 °C / min, preferably 2 - 5 °C / min.
[0025] On the other hand, the present invention also provides an application of a supported catalyst for preparing p-methoxycyclohexanone. The catalyst can be used for the one-step atmospheric pressure reduction of p-methoxyphenol to produce p-methoxycyclohexanone.
[0026] Preferably, the reaction is carried out in a fixed-bed reactor, and specifically includes the following steps:
[0027] (1) Heating and activating the catalyst: Loading the catalyst into the fixed-bed reactor, introducing hydrogen into the fixed-bed reactor, and activating it at a certain heating rate.
[0028] (2) Feeding and preheating the reaction solution: Feeding the reaction solution into the fixed-bed reactor at a certain feeding rate and preheating it through a preheating device.
[0029] (3) Reacting in the fixed-bed reactor: Feeding the preheated reaction solution and hydrogen at a certain feeding rate to obtain the target product.
[0030] Preferably, it further includes the following steps:
[0031] In step (1), the hydrogen space velocity is 5 - 50 min -1 , the gas pressure in the fixed-bed reactor is 1 bar, and the temperature is raised to 110 - 180 °C at a heating rate of 2 - 5 °C / min for catalyst activation.
[0032] In step (2), the reaction solvent is toluene or xylene, the feeding rate of the reaction solution is 0.1 - 5 h -1 (the ratio of the mass of the raw material to the mass of the loaded catalyst), the concentration of the p-methoxyphenol solution is 0.05 - 1 g / mL, and the temperature in the preheating device is kept consistent with the reaction bed temperature.
[0033] In step (3), the feeding rate of the reaction solution is 0.1 - 5 h -1 , the hydrogen space velocity is 5 - 50 min -1 .
[0034] Preferably, the present invention is equipped with a preheating device in the front section of the feed inlet of the fixed-bed reactor, and the temperature can be controlled by electric heating or jacket heating.
[0035] Preferably, the ratio of the loading height to the diameter of the catalyst in the fixed-bed reactor is 5 - 50, and the ratio of the inner diameter of the pipeline of the fixed-bed reactor to the particle size of the catalyst is greater than 8.
[0036] Preferably, the fixed-bed reactor of the present invention is installed vertically, which can further increase the reaction contact area, accelerate the reaction, and improve the reaction rate.
[0037] Compared with the prior art, the technical solution of the present invention has the following advantages:
[0038] (1) Under the action of a specific catalyst, the present invention can be used for the one-step hydrogenation of p-methoxyphenol to produce p-methoxycyclohexanone. Combining with the fixed-bed hydrogenation preparation process, the reaction can be carried out under normal pressure, eliminating the safety hazards existing in the high-pressure hydrogenation production process, and having the advantages of continuous production and high production efficiency;
[0039] (2) The catalyst provided by the present invention has a low content, a low cost price, and excellent catalytic activity, selectivity and stability. The service life of the catalyst is up to 2400 h, and it can be used efficiently and continuously for the preparation of p-methoxycyclohexanone from p-methoxyphenol. The molar conversion rate of the raw material is greater than 99%, and the selectivity of the product p-methoxycyclohexanone is greater than 95%, which is beneficial to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Figure 1 is the flow chart of the reaction equipment of the present invention
[0041] Figure 2 is the NMR spectrum of the product of Application Example 1 of the present invention DETAILED DESCRIPTION OF THE INVENTION
[0042] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.
[0043] Example 1
[0044] 1. A supported catalyst for the preparation of p-methoxycyclohexanone by fixed-bed hydrogenation under normal pressure, comprising a carrier and a two-component active metal supported on the carrier, including a noble metal active component Pd and a non-noble metal active component Zr. Calculated by 100%, the mass percentage content of Pd in the catalyst is 0.5%, and the mass percentage content of Zr in the catalyst is 1.2%. The rest is the carrier, and the carrier is spherical γ-Al2O3 with a diameter of 1-5 mm, a specific surface area of 100-300 m 2 / g, and the water absorption rate is 40-80%.
[0045] 2. The preparation method of the supported catalyst includes the following steps:
[0046] (1) Prepare 12.8 mL of an aqueous solution of Zr(NO3)4 with a concentration of 0.1 mol / L. Add 10 g of dried spherical γ-Al2O3 support to the solution, stir and impregnate for 24 h, then dry at 110 °C. Calcine the obtained sample at 500 - 800 °C until constant weight;
[0047] (2) Weigh 10 g of the sample obtained in (1), add 16.4 ml of water and 0.17 g of Pd(OAc)2. Place the sample in the solution, stir and impregnate for 12 h, then dry at 110 °C. Calcine the obtained sample at 400 - 700 °C until constant weight;
[0048] (3) Reduce the sample obtained in step (2), introduce hydrogen and perform high-temperature calcination. The hydrogen space velocity is 0.5 - 10 min -1 , the heating rate is 2 - 5 °C / min, the calcination temperature is 200 - 600 °C, and calcine until constant weight to obtain the catalyst, denoted as S1.
[0049] Example 2
[0050] Replace the Zr(NO3)4 solution with an equal mass fraction of Zn(NO3)2 solution, and the others are the same as in Example 1. The preparation method is the same as in Example 1, and the obtained catalyst is denoted as S2.
[0051] Example 3
[0052] Replace the Zr(NO3)4 solution with an equal mass fraction of Mn(NO3)2 solution, and the others are the same as in Example 1. The preparation method is the same as in Example 1, and the obtained catalyst is denoted as S3.
[0053] Example 4
[0054] Replace the Zr(NO3)4 solution with an equal mass fraction of Cu(NO3)2 solution, and the others are the same as in Example 1. The preparation method is the same as in Example 1, and the obtained catalyst is denoted as S4.
[0055] Example 5
[0056] Replace the Zr(NO3)4 solution with an equal mass fraction of Cr(NO3)3 solution, and the others are the same as in Example 1. The preparation method is the same as in Example 1, and the obtained catalyst is denoted as S5.
[0057] Example 6
[0058] Replace the Zr(NO3)4 solution with an equal mass fraction of La(NO3)3 solution, and the others are the same as in Example 1. The preparation method is the same as in Example 1, and the obtained catalyst is denoted as S6.
[0059] Example 7
[0060] Replace Pd(OAc)2 with an equal mass of H2PtCl6, and keep other conditions the same as in Example 1. The preparation method is the same as in Example 1, and the obtained catalyst is denoted as S7.
[0061] Comparative Example 1
[0062] A catalyst sample D1 was prepared by the same method steps as in Example 1, except that step (1) was not included in the preparation method and directly started from step (2), that is, the non-noble metal component Zr(NO3)4 was not added.
[0063] Comparative Example 2
[0064] A catalyst sample D2 was prepared by the same method steps as in Example 1, except that activated carbon was used as the carrier.
[0065] Application of the catalyst
[0066] The present invention also provides an application method of a supported catalyst for preparing p-methoxycyclohexanone. Under the action of the catalyst, p-methoxycyclohexanone is prepared by hydrogenation. The method specifically includes the following steps:
[0067] (1) Heating and activating the catalyst: The catalyst is loaded layer by layer into a fixed-bed reactor, and hydrogen is introduced into the fixed-bed reactor. Among them, the hydrogen space velocity is 5 - 50 min -1 , the gas pressure in the fixed-bed reactor is 1 bar, and the temperature is raised to 110 - 180 °C at a heating rate of 2 - 5 °C / min for activation;
[0068] (2) Feeding and preheating the reaction solution: The reaction solution of p-methoxyphenol is introduced into a preheating device. Among them, the reaction solvent is toluene or xylene, the feeding rate of the reaction solution is 0.1 - 5 h -1 (the mass ratio of the raw material to the mass of the loaded catalyst), the concentration of the p-methoxyphenol solution is 0.05 - 1 g / mL, and the temperature in the preheating device is kept consistent with the reaction bed temperature;
[0069] (3) Reacting in the fixed-bed reactor: Continuously introduce the preheated reaction solution of p-methoxyphenol and hydrogen into the fixed-bed reactor to obtain the product p-methoxycyclohexanone. Among them, the feeding rate of the reaction solution is 0.1 - 5 h -1 , and the hydrogen space velocity is 5 - 50 min -1 .
[0070] Preferably, a preheating device is equipped at the front section of the feed inlet of the fixed-bed reactor of the present invention, and the temperature can be controlled by electric heating or jacket heating.
[0071] Preferably, the ratio of the filling height to the diameter of the catalyst in the fixed-bed reactor is 5 - 50, and the ratio of the inner diameter of the pipeline of the fixed-bed reactor to the particle diameter of the catalyst is greater than 8.
[0072] Preferably, the fixed-bed reactor of the present invention is installed vertically, which can further increase the reaction contact area, accelerate the reaction, and improve the reaction rate.
[0073] The catalysts provided in Examples 1-8 and Comparative Examples 1-2 were used to prepare p-methoxycyclohexanone according to the above application steps. The reaction conditions, conversion rate of p-methoxyphenol, selectivity of p-methoxycyclohexanone, and reaction time are shown in Table 1.
[0074] Table 1. Reaction Conditions and Reaction Results
[0075]
[0076]
[0077] As can be seen from Table 1, the catalyst of the present invention has high catalytic activity and selectivity. The highest conversion rate of the raw material p-methoxyphenol can reach 99.5%, and the highest selectivity of the product p-methoxycyclohexanone can reach 95.8%. The service life of the catalyst is not less than 2400 h, and it has good industrialization prospects.
[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of protection of the present invention.
Claims
1. A catalyst for the hydrogenation preparation of p-methoxycyclohexanone, characterized in that, The catalyst includes a support and a two-component active metal supported on the support. One of the active components is a noble metal active component, and the mass percentage of the noble metal is 0.1 - 10.0% based on 100%. The other active component is a non-noble metal active component, and the mass percentage of the non-noble metal is 0.1 - 20.0% based on 100%. The rest is the support. Among them, the noble metal active component in the catalyst is Pd or Pt. Among them, the non-noble metal active component in the catalyst is one or more of Zr, Zn, Mn, Cu, Cr, La. Among them, the support is Al2O3.
2. The catalyst according to claim 1, characterized in that, In the catalyst, the mass percentage of the noble metal active component is 0.1 - 5.0%, and the mass percentage of the non-noble metal active component is 0.1 - 10.0%.
3. The catalyst according to claim 1, characterized in that, In the catalyst, the mass percentage of the noble metal active component is 0.1 - 1.0%, and the mass percentage of the non-noble metal active component is 0.1 - 3%.
4. The catalyst according to claims 1-3, characterized in that, The catalyst support is spherical γ-Al2O3 with a diameter of 1-5 mm, a specific surface area of 100-300 m 2 / g, an average pore diameter of 5-20 nm, and a water absorption rate of 40-80%.
5. The catalyst according to claims 1-3, characterized in that, The catalyst can be used for the one-step atmospheric pressure reduction of p-methoxyphenol to produce p-methoxycyclohexanone.
6. The catalyst according to claim 5, characterized in that, The catalytic reaction is carried out in a fixed-bed reactor.
7. The catalyst according to claim 6, characterized in that, The progress of the catalytic reaction includes the following steps: (1) Heating and activating the catalyst: Loading the catalyst into the fixed-bed reactor, introducing hydrogen into the fixed-bed reactor, and activating it at a certain heating rate. (2) Feeding and preheating the reaction solution: Feeding the reaction solution into the fixed-bed reactor at a certain feeding rate and preheating it through a preheating device. (3) Reacting in the fixed-bed reactor: Feeding the preheated reaction solution and hydrogen into the fixed-bed reactor at a certain feeding rate to obtain the target product.
8. The catalyst according to claim 7, characterized in that, The fixed-bed reactor in the catalytic reaction is installed vertically. A preheating device is equipped in the front section of the feed inlet of the fixed-bed reactor, and temperature control can be achieved by electric heating or jacket heating. The ratio of the loading height to the diameter of the catalyst in the fixed-bed reactor is 5 - 50, and the ratio of the inner diameter of the pipeline of the fixed-bed reactor to the particle size of the catalyst is greater than 8.