Separation method of p-benzoquinone in phenol electrolytic circulation liquid
By adding organic alcohol to the phenol electrolytic circulation liquid and centrifugation and dropping method, the problems of large solvent recovery, toxic substance generation and wastewater in the p-benzoquinone separation process in the prior art were successfully solved, and high yields were achieved and high purity of parabenzoquinone separation.
Patent Information
- Application Number
- CN202411427254.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2025-02-25
AI Technical Summary
The separation method of benzyl quinone in the prior art has problems such as large solvent recovery, toxic substances, large amount of wastewater and high cost.
Organic alcohol was added to the phenol electrolytic circulation solution, and the organic phase was obtained by centrifugation and dropwise addition, and then concentrated and dried to obtain p-benzoquinone.
High yield and high purity separation of p-benzoquinone is achieved, reducing solvent usage and wastewater generation, and reducing production costs.
Smart Images
Figure CN119504394A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of p-benzoquinone preparation, and in particular to a method for separating p-benzoquinone from a phenol electrolysis circulating liquid. Background Art
[0002] p-Benzoquinone is an important raw material for the production of hydroquinone and dye intermediates. It is also widely used in polymer and rubber industries as an inhibitor, antioxidant and rubber antioxidant. At present, the industrial synthesis of p-benzoquinone mainly adopts the aniline oxidation method, that is, aniline is oxidized to p-benzoquinone using pyrolusite as an oxidant. However, this process requires the addition of excessive MnO2 and dilute sulfuric acid, which produces a large amount of waste residue during the reaction, causing serious environmental pollution problems.
[0003] The electrochemical oxidation of phenol to prepare p-benzoquinone is a green and environmentally friendly preparation method. This technology has high selectivity and high conversion rate, but during the electrolysis process, phenol will combine with p-benzoquinone to form quinone hydroquinone, which affects the separation of products. Under long-term operation, the electrolytic circulating fluid will produce certain charred impurities, which will affect the electrolytic performance of the electrolytic circulating fluid. Therefore, recovering p-benzoquinone from the phenol electrolytic circulating fluid can reduce waste liquid pollution while increasing production efficiency. However, the current separation method of p-benzoquinone has the following disadvantages: there is a large amount of solvent recovery in the separation process, which produces certain toxic substances, or produces a large amount of wastewater and is costly. Separation by new equipment requires special customization, and the single processing capacity of the equipment is low. Summary of the invention
[0004] In order to solve the above-mentioned deficiencies in the art, the present application aims to provide a method for separating p-benzoquinone from phenol electrolysis circulating fluid. By adding organic alcohol to the reaction system, the technical problems of complex process and low yield in the preparation method of p-benzoquinone compounds in the prior art are solved.
[0005] According to one aspect of the present application, a method for separating p-benzoquinone in a phenol electrolysis circulating liquid is provided, comprising:
[0006] The phenol electrolytic circulating liquid is adjusted to alkaline and then centrifuged to obtain the supernatant;
[0007] Add organic alcohol dropwise to the supernatant to obtain an organic phase;
[0008] The organic phase was concentrated and dried to obtain p-benzoquinone.
[0009] According to some embodiments of the present application, the rotation speed of the centrifugal treatment is 6000-12000 rpm, and the centrifugation time is 5-20 min.
[0010] According to some embodiments of the present application, the volume ratio of the organic alcohol to the supernatant is (0.5-5):1.
[0011] According to some embodiments of the present application, the dropping speed of the organic alcohol is 20-30 mL / min.
[0012] According to some embodiments of the present application, the organic alcohol is added dropwise while stirring.
[0013] According to some embodiments of the present application, the stirring temperature is 0-95° C., and the stirring is continued for 1-5 h.
[0014] According to some embodiments of the present application, the organic alcohol is selected from one or more of benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, n-butanol, n-pentanol, n-hexanol, n-octanol, n-decanol, 2-methyl-1-propanol, cyclopentanol and cyclohexanol.
[0015] According to some embodiments of the present application, the organic phase before concentration is washed with toluene or xylene.
[0016] According to some embodiments of the present application, the drying treatment temperature is 30-110° C., and the drying treatment time is 2-5 hours.
[0017] According to some embodiments of the present application, the yield of p-benzoquinone separated by the separation method is greater than 76%, and the purity is greater than 94%.
[0018] Compared with the prior art, this application has at least the following beneficial effects:
[0019] The present application provides a method for separating p-benzoquinone in a phenol electrolysis circulating liquid, using an organic alcohol compound as a separation solvent. The separation method is simple, the raw material source is wide and the price is reasonable, and the prepared p-benzoquinone has not only a high yield and few impurities, but also a high purity. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a liquid phase diagram of the separation of p-benzoquinone according to Example 1 of the present application.
[0021] Figure 2 This is a separation effect diagram of an exemplary embodiment of the present application. DETAILED DESCRIPTION
[0022] The technical solution of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.
[0023] It is particularly important to point out that similar substitutions and modifications made to the present application are obvious to those skilled in the art, and they are all deemed to be included in the present application. Relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present application to implement and apply the technology of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments.
[0024] If no specific conditions are specified in this application, the preparation shall be carried out under conventional conditions or the conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, for which the manufacturers are not specified, are all conventional products that can be obtained commercially.
[0025] The application is described in detail below.
[0026] At present, most of the separation methods of benzoquinone have problems such as large amount of solvent recovery during the separation process, generation of certain toxic substances, or generation of large amount of wastewater and high cost.
[0027] The present application provides a method for recovering benzoquinone in a phenol electrolysis circulating liquid, wherein the impurities in the phenol electrolysis circulating liquid are centrifuged and one or more organic alcohols are added to the reaction system to separate the phenol electrolysis circulating liquid. The separation method is particularly suitable for use in the field of electrochemical oxidation of phenol and is an effective separation method.
[0028] Separation method of the present application
[0029] The phenol electrolysis circulating liquid mixture is centrifuged to obtain a clear liquid portion, wherein the rotation speed is 6000 to 12000 revolutions and the centrifugation time is 1 to 5 hours.
[0030] The organic alcohol is added to the supernatant according to the volume ratio of the organic alcohol to the phenol electrolytic circulating liquid (0.5-5):1, and the organic phase is separated.
[0031] The organic phase is transferred to a flask by separation, and toluene or xylene in a preset volume ratio is added for washing, and then the solvent is evaporated off, and para-benzoquinone is obtained after drying. The drying temperature is 30 to 110° C., and the drying time is 2 to 5 hours.
[0032] The organic alcohol may be one or more of benzyl alcohol, phenylethyl alcohol, phenylpropanol, n-butanol, n-pentanol, n-hexanol, n-octanol, n-decanol, 2-methyl-1-propanol, cyclopentanol, and cyclohexanol.
[0033] The technical solution of the present application is further described below in conjunction with specific embodiments.
[0034] Preparation Example Pre-prepared phenol electrolytic circulating fluid
[0035] The phenol electrolytic circulating liquid is a circulating electrolyte for preparing p-benzoquinone by electrolyzing phenol. It uses a homemade catalyst and the environment is alkaline. The phenol electrolytic circulating liquid after 150h circulation. The preparation steps are as follows:
[0036] The phenol at the anode is oxidized to p-benzoquinone, and the phenol at the cathode is reduced. The reaction voltage is 0.9V
[0037] Effect: Faradaic efficiency exceeds 90%, selectivity is close to 100%, and it can operate stably for 300 hours.
[0038] The electrolyte is a high-concentration potassium hydroxide solution (it can also be one or more of potassium hydroxide, sodium hydroxide, and calcium hydroxide); the cathode and anode substrates are both phenol.
[0039] Electrodes: Metal electrodes and graphite electrodes loaded with nickel sulfide, made in the laboratory.
[0040] The above preparation example was prepared by our laboratory, which does not mean that the separation method of the present application can only separate the above phenol electrolytic circulating liquid.
[0041] Example 1
[0042] Weigh 150 ml of electrolyte (product of 0.15 mol phenol electrolysis for 150 h, selectivity 100%), centrifuge at 9000 rpm for 20 min, and obtain the supernatant.
[0043] Weigh 50 ml of n-butanol and add it dropwise into the supernatant at a dropping speed of 30 mL / min and a system temperature of 70°C. After the dropping is completed, stir for 2 h to obtain the organic phase.
[0044] After the reaction is completed, the mixture is allowed to stand and wait for cooling. An appropriate amount of toluene is added to the organic phase to dissolve the mixture and the solvent is removed by rotary evaporation. The obtained product is then placed in an oven and dried at 80°C for 1.5 hours to obtain 13.62 g of p-benzoquinone.
[0045] Example 2
[0046] Weigh 150 ml of electrolyte (product of 0.15 mol phenol electrolysis for 100 h), centrifuge at 9500 rpm for 20 min, and obtain the supernatant.
[0047] Weigh 100 ml of n-octanol and add it dropwise into the supernatant at a dropping speed of 20 mL / min and a system temperature of 65° C. After the dropping is completed, stir for 2 h to obtain the organic phase.
[0048] After the reaction is completed, the mixture is allowed to stand and wait for cooling. An appropriate amount of toluene is added to the organic phase to dissolve the mixture and the solvent is removed by rotary evaporation. The obtained product is then placed in an oven and dried at 80°C for 1.5 hours to obtain 12.37 g of p-benzoquinone.
[0049] Example 3
[0050] Weigh 150 ml of electrolyte (product of 0.15 mol phenol electrolysis for 150 h), centrifuge at 10,000 rpm for 10 min, and obtain the supernatant.
[0051] Weigh 110 ml of cyclohexanol and add it dropwise into the supernatant at a dropping speed of 20 mL / min and a system temperature of 65° C. After the dropping is completed, stir for 2 h to obtain the organic phase.
[0052] After the reaction is completed, the mixture is allowed to stand and wait for cooling. An appropriate amount of toluene is added to the organic phase to dissolve the mixture and the solvent is removed by rotary evaporation. The obtained product is then placed in an oven and dried at 80°C for 1.5 hours to obtain 12.97 g of p-benzoquinone.
[0053] Example 4
[0054] Weigh 150 ml of electrolyte (product of 0.15 mol phenol electrolysis for 150 h), centrifuge at 8500 rpm for 20 min, and obtain the supernatant.
[0055] Weigh 150 ml of benzyl alcohol and add it dropwise into the supernatant at a dropping speed of 20 mL / min and a system temperature of 65°C. After the dropping is completed, stir for 2 h to obtain the organic phase.
[0056] After the reaction is completed, the mixture is allowed to stand and wait for cooling. An appropriate amount of toluene is added to the organic phase to dissolve the mixture and the solvent is removed by rotary evaporation. The obtained product is then placed in an oven and dried at 85°C for 2 hours to obtain 13.06 g of p-benzoquinone.
[0057] Comparative Example 1
[0058] Steam distillation method: Weigh 150 ml of electrolyte (the product of 0.15 mol of phenol electrolysis for 150 hours) and distill it through steam at a distillation rate of 20 mL / min. After the distillation is completed, let it stand and wait for cooling. Add an appropriate amount of toluene to dissolve the organic phase and then evaporate the solvent. Then, place the product in an oven at 85°C and dry it for 2 hours to obtain 7.68 g of p-benzoquinone.
[0059] Comparative Example 2
[0060] Weigh 150 ml of electrolyte (product of 0.15 mol phenol electrolysis for 150 h), centrifuge at 10,000 rpm for 10 min, and obtain the supernatant.
[0061] Weigh 1200 ml of cyclohexanol and add it dropwise into the supernatant at a dropping speed of 20 mL / min and a system temperature of 65° C. After the dropping is completed, stir for 2 h to obtain the organic phase.
[0062] After the reaction is completed, the mixture is allowed to stand and wait for cooling. An appropriate amount of toluene is added to the organic phase to dissolve the mixture and the solvent is removed by rotary evaporation. The obtained product is then placed in an oven and dried at 80°C for 1.5 hours to obtain 13.94 g of p-benzoquinone.
[0063] Comparative Example 3
[0064] The pH of the electrolyte in the preparation example was adjusted to neutral, 150 ml of the electrolyte (the product of 0.15 mol of phenol electrolysis for 150 h) was weighed and centrifuged at 10,000 rpm for 10 min under neutral conditions to obtain a supernatant.
[0065] Weigh 150 ml of cyclohexanol and add it dropwise into the supernatant at a dropping speed of 20 mL / min and a system temperature of 65° C. After the dropping is completed, stir for 2 h to obtain the organic phase.
[0066] After the reaction is completed, the mixture is allowed to stand and wait for cooling. An appropriate amount of toluene is added to the organic phase to dissolve the mixture and the solvent is removed by rotary evaporation. The obtained product is then placed in an oven and dried at 80°C for 1.5 hours to obtain 9.46 g of p-benzoquinone.
[0067] Experimental example
[0068] The yield and purity of p-benzoquinone in the above examples and comparative examples were tested and calculated, and the results are shown in the table below.
[0069] Yield (%) purity(%) Solvent consumption (solvent: circulating fluid) Example 1 84.1 96.1 1:1 Example 2 76.3 95.7 0.5:1 Example 3 80 94.7 1:1 Example 4 80.6 95.9 0.9:1 Comparative Example 1 47.0 84.7 / Comparative Example 2 85.3 96.3 8:1 Comparative Example 3 57.9 89.3 1:1(Neutral)
[0070] According to the data in the above table, the separation method of the present application uses a small amount of solvent, and the yield and purity are both high. At the same time, the present application found that the separation effect is better under alkaline conditions. Figure 2 As shown, it is a diagram of the separation effect of an embodiment of the present application. The lower layer is the circulating liquid, and the upper layer is the organic phase containing organic alcohol. The p-benzoquinone is effectively extracted into the organic alcohol phase, and the effect is more obvious.
[0071] In the present application, under alkaline conditions, phenol and benzoquinone combine to form a stable complex, phenol and benzoquinone are easily oxidized by air, and benzoquinone has photolysis, all of which make it difficult to separate p-benzoquinone from the phenol electrolysis circulating liquid. In the present application, by adding alcohol compounds, effective competitive separation can be performed under high alkaline conditions. Under alkaline conditions, benzoquinone will exist in the form of a complex with alcohols, and it does not need to contact the external environment when transferred from the circulating liquid system to the alcohol system, and is subsequently directly transferred to the desolventizing system to avoid contact with oxygen in the air, thereby achieving the purpose of separating p-benzoquinone.
[0072] The description of the above embodiments is only used to help understand the method and core idea of the present application. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.
Claims
1. A method for separating p-benzoquinone from a phenol electrolysis circulating liquid, characterized in that: include: The phenol electrolytic circulating liquid is adjusted to alkaline and then centrifuged to obtain the supernatant; adding an organic alcohol dropwise to the supernatant to obtain an organic phase; The organic phase is concentrated and dried to obtain p-benzoquinone; Wherein, the volume ratio of the organic alcohol to the supernatant is (0.5-5):
1.
2. The separation method according to claim 1, characterized in that The rotation speed of the centrifugal treatment is 6000-12000 rpm, and the centrifugal time is 5-20 min.
3. The separation method according to claim 1, characterized in that The organic alcohol is added dropwise at a speed of 20-30 mL / min; the organic alcohol is added dropwise while being stirred.
4. The separation method according to claim 3, characterized in that The volume ratio of the organic alcohol to the supernatant is (0.5-1):
1.
5. The separation method according to claim 4, characterized in that The stirring temperature is 0-95°C, and the stirring is continued for 1-5 hours.
6. The separation method according to any one of claims 1 to 5, characterized in that: The organic alcohol is selected from one or more of benzyl alcohol, phenylethyl alcohol, phenylpropanol, n-butanol, n-pentanol, n-hexanol, n-octanol, n-decanol, 2-methyl-1-propanol, cyclopentanol and cyclohexanol.
7. The separation method according to claim 6, characterized in that The organic phase before the concentration is washed with toluene or xylene.
8. The separation method according to claim 7, characterized in that The drying treatment temperature is 30-110°C.
9. The separation method according to claim 8, characterized in that The drying time is 2-5 hours.
10. The separation method according to any one of claims 7 to 9, characterized in that: The p-benzoquinone yield separated by the separation method is greater than 76%, and the purity is greater than 94%.