Method for preparing benzenediol by using fixed bed
By using pretreated TS-1 catalyst and hydrogen peroxide in the fixed bed device, the problems of low phenol conversion and difficulty in product separation in the prior art are solved, and the efficient preparation of rekinocyanide is achieved, which improves economic value and industrial applicability.
Patent Information
- Application Number
- CN202510269845.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-05-02
AI Technical Summary
In the prior art, phenol conversion rate is low, the para-to-orthodox ratio in the product is low, the production cost is high, and separation and recycling are difficult.
The pretreated TS-1 catalyst was used to continuously prepare rekinetol with a fixed bed device, and hydrogen peroxide was used as a hydroxylation agent to avoid the addition of alcohols and simplify the separation process.
It improves the conversion rate of phenol and the selectivity of rekinocyanide, increases the parametric ratio, reduces production costs, simplifies the separation process, and is suitable for large-scale industrial production.
Smart Images
Figure CN119912318A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of hydroquinone synthesis and relates to a method for preparing hydroquinone by using a fixed bed. Background Art
[0002] The aniline oxidation method was the earliest method for producing hydroquinone. Later, some manufacturers changed the aniline oxidation method to the diisopropylbenzene oxidation method. This method has low total cost and less chemical pollution, but it has been gradually eliminated due to the small amount of organic pollutants, complex composition, and difficulty in product separation. In the 1970s, the phenol hydroxylation method using hydrogen peroxide as an oxidant was developed. This method has low raw material cost and is easier to obtain. It is widely considered to be the most promising method for preparing hydroquinone.
[0003] At present, the application fields represented by catechol and hydroquinone are gradually developing, and the demand for catechol and hydroquinone is growing exponentially. Among them, hydroquinone is not only an important fine chemical intermediate, but also can be used in photosensitive materials, rubber, dyes and daily chemical industries, and has great economic value. Nearly 40% of hydroquinone in the world is used in the photosensitive materials industry. Hydroquinone and its derivatives can be used as photographic developers, and can also be added to photosensitive resins as thermal inhibitors. They are widely used. At present, there are still many problems in the synthesis technology of o- and hydroquinone: low phenol conversion rate in the process, low ratio of para- to ortho-position in the product, high production cost, and very difficult separation and recovery. Summary of the invention
[0004] In order to overcome the above technical deficiencies and solve the technical problems of low phenol conversion rate and low ratio of para-ortho positions in the product, the present invention develops a method for continuously preparing hydroquinone using pretreated TS-1 as a catalyst and a fixed bed as a reaction device, thereby effectively improving the phenol conversion rate and the content of hydroquinone in the product on a fixed bed device for continuous reaction; no new organic solvent is introduced into the product, thereby solving the problems of difficulty in separating the product from alcohol substances after the reaction and complex separation process; the economic value is improved and the method is suitable for large-scale industrial production.
[0005] The technical solution of the present invention is as follows:
[0006] A method for preparing hydroquinone using a fixed bed comprises the following steps: hydroxylating a phenol aqueous solution to synthesize hydroquinone in a fixed bed device using hydrogen peroxide as a hydroxylating agent under the action of a TS-1 catalyst pretreated with a silane coupling agent alcohol solution.
[0007] The specific steps include: placing the pretreated TS-1 catalyst in the constant temperature section of the reaction tube, and when the reaction temperature reaches 30-100°C, using an injection pump to simultaneously pump hydrogen peroxide and phenol aqueous solution into the reaction tube, reacting at normal pressure to obtain a hydroquinone product.
[0008] The pretreatment process includes filling the TS-1 catalyst in the constant temperature section of the reaction tube, introducing the silane coupling agent alcohol solution therein, using nitrogen as carrier gas, performing pretreatment under normal pressure, and drying to obtain the pretreated TS-1 catalyst.
[0009] The mass space velocity of the silane coupling agent alcohol solution is 0.5-1h -1 .
[0010] The pretreatment temperature is 100-160° C., and the pretreatment time is 4-6 hours.
[0011] The mass fraction of the silane coupling agent in the silane coupling agent alcohol solution is 2% to 10%, preferably 3% to 6%.
[0012] The silane coupling agent is one or more of KH570, APTES and DETAS, preferably APTES.
[0013] The solvent in the silane coupling agent alcohol solution is one or two of monohydric alcohol and dihydric alcohol; preferably, the solvent is one or more of methanol, 1,2-cyclohexanediol and 1,4-cyclohexanediol.
[0014] The reaction temperature is 50-85°C.
[0015] The phenol mass fraction of the phenol aqueous solution is 5%-60%, preferably 15%-50%.
[0016] The molar ratio of the hydrogen peroxide to phenol is 0.5-5:1, preferably 2-4:1.
[0017] The mass space velocity of the phenol is 0.3-1h -1 .
[0018] The TS-1 catalyst has a short b-axis flake and mesoporous structure.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] The present invention uses phenol aqueous solution as a reaction raw material, uses hydrogen peroxide as a hydroxylating agent, and prepares hydroquinone under the catalysis of TS-1 pretreated with a silane coupling agent alcohol solution, and no other substances are introduced during the reaction process. Using TS-1 pretreated with a silane coupling agent alcohol solution as a reaction catalyst effectively avoids adding alcohol substances to the reaction system, solves the problems of alcohol substances and reaction products being difficult to separate, and the separation process being complicated, and the phenol conversion rate and hydroquinone selectivity are both high. This is due to the unique pore structure of TS-1 and further modification with a silane coupling agent alcohol solution. The silane coupling agent and the alcohol solution combine with the surface hydroxyl group of the titanium silicon catalyst to produce a steric hindrance effect, which can promote the product hydroquinone to be more inclined to generate the para position and improve the conversion rate; further, the short b-axis flake and mesoporous structure are more conducive to the diffusion of reactants and products in the pores. In addition, it is also achieved that the para ratio in the product obtained on the fixed bed device of the continuous reaction is significantly improved, the economic value of the reaction is increased, and a new technical solution is provided for large-scale industrialization. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is the SEM image of TS-1 catalyst. DETAILED DESCRIPTION
[0022] Example 1
[0023] Preparation of TS-1 catalyst: 320g of tetrabutyl silicate was added to an aqueous solution containing 0.35g of hydroxypropyltrimethylammonium fluoride chitosan and 40.6g of tetrapropylammonium hydroxide, and stirred vigorously at room temperature for 2h; 26.75g of tetrabutyl titanate was dissolved in isopropanol and added dropwise to the above solution, stirred at room temperature for 4h, heated under reflux at 70°C for 30min, and then the isopropanol was evaporated; the sample was placed in a polytetrafluoroethylene-lined crystallization reactor and crystallized at 180°C for 24h, the crystallized sample was poured into a centrifuge tube, centrifuged for 5min, the sample was collected and washed 3 times, dried at 100°C for 2h, and calcined at 550°C for 4h to obtain TS-1 catalyst, such as Figure 1 The nanostructured ...
[0024] Example 2
[0025] First, the silane coupling agent APTES was dissolved in methanol, 1,2-cyclohexanediol, 1,4-cyclohexanediol and their mixed alcohols to obtain 5 kinds of alcohol solutions, as shown in Table 1, in which the various alcohol solutions were added at a molar ratio of 1:1. APTES accounted for 5% of the mass fraction of the alcohol solution. The catalyst was pretreated using a fixed bed reaction device. 20g of TS-1 catalyst was loaded into the fixed bed constant temperature section, and the feed was started after the temperature rose to 120°C, with a mass space velocity of 0.8h -1The reaction was carried out under the reaction conditions for 6 hours. The catalyst after the reaction was unloaded and dried at 80-100°C to obtain a pre-treated catalyst, which was named according to the composition of the reaction solution as shown in Table 1.
[0026] Table 1 Catalyst nomenclature
[0027] Reaction solution composition Catalyst name APTES+Methanol M-TS-1 APTES+1,2-cyclohexanediol 1,2-TS-1 APTES+1,4-cyclohexanediol 1,4-TS-1 APTES+methanol+1,2-cyclohexanediol 1,2-M-TS-1 APTES+methanol+1,4-cyclohexanediol 1,4-M-TS-1
[0028] Example 3
[0029] 15g of M-TS-1 was loaded into the constant temperature section of the fixed bed reactor. When the reaction temperature reached 65°C, a 40% phenol aqueous solution and hydrogen peroxide were simultaneously pumped into the reactor using a feed pump. The mass space velocity of phenol was 0.3h -1 The molar ratio of hydrogen peroxide to phenol was 2:1, and samples were taken every 2 hours for analysis. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 37.33%, the selectivity of dihydroxybenzene was 82.13%, and the ratio of hydroxybenzene to orthohydroxybenzene was 1.7.
[0030] Example 4
[0031] 15g 1,2-TS-1 was loaded into the constant temperature section of the fixed bed reactor. When the reaction temperature reached 65°C, a 40% phenol aqueous solution and hydrogen peroxide were simultaneously pumped into the reactor using a feed pump. The mass space velocity of phenol was 0.3h -1 The molar ratio of hydrogen peroxide to phenol was 2:1, and samples were taken every 2 hours for analysis. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 40.15%, the selectivity of diol was 86.99%, and the ratio of ortho-hydroxybenzene was 2.1.
[0032] Example 5
[0033] 15g 1,4-TS-1 was loaded into the constant temperature section of the fixed bed reactor. When the reaction temperature reached 65°C, a 40% phenol aqueous solution and hydrogen peroxide were simultaneously pumped into the reactor using a feed pump. The mass space velocity of phenol was 0.3h -1 The molar ratio of hydrogen peroxide to phenol was 2:1, and samples were taken every 2 hours for analysis. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 42.11%, the selectivity of dihydroxybenzene was 89.41%, and the ratio of hydroxybenzene to orthohydroxybenzene was 1.9.
[0034] Example 6
[0035] 15g 1,2-M-TS-1 was loaded into the constant temperature section of the fixed bed reactor. When the reaction temperature reached 65°C, a 40% phenol aqueous solution and hydrogen peroxide were simultaneously pumped into the reactor using a feed pump. The mass space velocity of phenol was 0.3h -1The molar ratio of hydrogen peroxide to phenol was 2:1, and samples were taken every 2 hours for analysis. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 45.34%, the selectivity of dihydroxybenzene was 93.15%, and the ratio of hydroxybenzene to orthohydroxybenzene was 2.9.
[0036] Example 7
[0037] 15g 1,4-M-TS-1 was loaded into the constant temperature section of the fixed bed reactor. When the reaction temperature reached 65°C, a 40% phenol aqueous solution and hydrogen peroxide were simultaneously pumped into the reactor using a feed pump. The mass space velocity of phenol was 0.3h -1 The molar ratio of hydrogen peroxide to phenol was 2:1, and samples were taken every 2 hours for analysis. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 41.95%, the selectivity of dihydroxybenzene was 92.47%, and the ratio of hydroxybenzene to orthohydroxybenzene was 2.4.
[0038] Comparative Example 1
[0039] The same as Example 2, but the TS-1 catalyst was treated with a silane coupling agent alone, and the obtained catalyst was named ATS-1.
[0040] 15g ATS-1 was loaded into the constant temperature section of the fixed bed reactor. When the reaction temperature reached 65°C, a 40% phenol aqueous solution and hydrogen peroxide were simultaneously pumped into the reactor using a feed pump. The mass space velocity of phenol was 0.3h -1 The molar ratio of hydrogen peroxide to phenol was 2:1, and samples were taken every 2 hours for analysis. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 35.91%, the selectivity of dihydroxybenzene was 79.34%, and the ratio of hydroxybenzene to orthohydroxybenzene was 1.5.
Claims
1. A method for preparing hydroquinone using a fixed bed, characterized in that: The method comprises the following steps: using hydrogen peroxide as a hydroxylating agent and TS-1 catalyst pretreated with a silane coupling agent alcohol solution to hydroxylate a phenol aqueous solution in a fixed bed device to synthesize hydroquinone.
2. A method for preparing hydroquinone using a fixed bed as claimed in claim 1, characterized in that: The specific steps include: placing the pretreated TS-1 catalyst in the constant temperature section of the reaction tube, and when the reaction temperature reaches 30-100°C, using an injection pump to simultaneously pump hydrogen peroxide and phenol aqueous solution into the reaction tube, reacting at normal pressure to obtain a hydroquinone product.
3. A method for preparing hydroquinone using a fixed bed as claimed in claim 1, characterized in that: The pretreatment process includes filling the TS-1 catalyst in the constant temperature section of the reaction tube, introducing the silane coupling agent alcohol solution therein, using nitrogen as carrier gas, performing pretreatment under normal pressure, and drying to obtain the pretreated TS-1 catalyst.
4. A method for preparing hydroquinone using a fixed bed as claimed in claim 3, characterized in that: The mass space velocity of the silane coupling agent alcohol solution is 0.5-1h -1 .
5. A method for preparing hydroquinone using a fixed bed as claimed in claim 3, characterized in that: The pretreatment temperature is 100-160° C., and the pretreatment time is 4-6 hours.
6. A method for preparing hydroquinone using a fixed bed as claimed in any one of claims 1 to 3, characterized in that: 2% to 10% of the mass fraction of the silane coupling agent in the silane coupling agent alcohol solution; and / or, The silane coupling agent is one or more of KH570, APTES and DETAS; and / or, The solvent in the silane coupling agent alcohol solution is one or two of monohydric alcohol and dihydric alcohol.
7. A method for preparing hydroquinone using a fixed bed as claimed in any one of claims 1 to 3, characterized in that: The phenol mass fraction of the phenol aqueous solution is 5%-60%; and / or, The molar ratio of the hydrogen peroxide to the phenol is 0.5-5:
1.
8. A method for preparing hydroquinone using a fixed bed as claimed in any one of claims 1 to 3, characterized in that: The reaction temperature is 50-85°C.
9. A method for preparing hydroquinone using a fixed bed as claimed in any one of claims 1 to 3, characterized in that: The mass space velocity of the phenol is 0.3-1h -1 .
10. A method for preparing hydroquinone using a fixed bed according to any one of claims 1 to 3, characterized in that: The TS-1 catalyst has a short b-axis flake and mesoporous structure.