Synthesis method and modification method of TS-1 catalyst and method for preparing benzenediol

Abstract

The invention provides a synthesis method and a modification method of a TS-1 catalyst and a method for preparing benzenediol. The TS-1 catalyst is obtained by taking tetraethyl orthosilicate as a silicon source, tetrabutyl titanate as a titanium source and quaternary ammonium salt of chitosan and tetrapropylammonium hydroxide as structure-directing agents, and the TS-1 catalyst is uniform in particle size and smooth in surface and has a short b-axis lamellar and mesoporous structure. According to the method, the TS-1 catalyst is modified by the silane coupling agent to obtain the modified TS-1 catalyst, and under the action of the modified TS-1 catalyst, phenol hydroxylation is performed to synthesize benzenediol by taking hydrogen peroxide as an oxidizing agent, so that the phenol conversion rate of hydroxylation reaction and the para-position content in the product are improved, the reaction economic value is increased, and the operation process is simple.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst synthesis and relates to a synthesis method and a modification method of a TS-1 catalyst and a method for preparing hydroquinone. Background Art

[0002] Phenol is an organic compound with the chemical formula C 6 H 5 OH is a colorless needle-shaped crystal with a special smell. It is toxic and is an important raw material for the production of certain resins, bactericides, preservatives and drugs (such as aspirin). It has a melting point of 43°C. It is slightly soluble in water at room temperature and easily soluble in organic solvents. When the temperature is higher than 65°C, it can be miscible with water in any proportion.

[0003] Catechol can undergo substitution reactions similar to phenol, such as sulfonation, chlorination, and alkylation. The electron cloud density on the benzene ring will change with the position of the hydroxyl group. The substitution position will change due to the position of the hydroxyl group, resulting in different substitution reactions on the benzene ring. Catechol generally undergoes a single electrophilic substitution reaction at the 3 or 4 position. Hydroquinone has two symmetrical hydroxyl groups, and the electron cloud density at the other four positions is the same. When a single electrophilic substitution reaction occurs, the other four -H are equally likely to be replaced and are in an equal competitive relationship. Catechol can react with metal salts to form metal salt complexes. These complexes can be used as analytical reagents, mainly because the ortho-hydroxyl group is a conjugated hydroxyl group, so it is easy to undergo complexation reactions. Hydroquinone is a substance with strong reducing properties. In the presence of H 2 O 2 Or it can be converted into benzoquinone under the oxidation of oxygen, and this reaction will be accelerated under alkaline conditions. Hydroquinone is the main photographic developer because it is easy to undergo silver mirror reaction. The hydroxyl group on its benzene ring can undergo esterification and etherification reactions, and under certain conditions, it can also undergo alkylation and hydrogenation reactions.

[0004] 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 great difficulty in separation and recovery. Summary of the invention

[0005] In order to overcome the above technical deficiencies, the present invention develops a method for synthesizing, modifying and preparing hydroquinone of a TS-1 catalyst. The present invention prepares a TS-1 catalyst having a short b-axis flake and mesoporous structure. After the TS-1 catalyst is modified with a silane coupling agent, due to its unique structure and the resulting steric hindrance effect, the product hydroquinone is more inclined to generate the para position, thereby improving the phenol conversion rate of the hydroxylation reaction and the para content in the product, improving the economic value of the reaction, and the operation process is simple.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a method for synthesizing a TS-1 catalyst, comprising the following steps:

[0008] (1) mixing a structure directing agent, tetrapropylammonium hydroxide and deionized water to obtain a solution A; the structure directing agent is a quaternary ammonium salt of chitosan and tetrapropylammonium hydroxide;

[0009] (2) adding a silicon source to solution A and vigorously stirring at room temperature for 1-4 hours to obtain solution B; the silicon source is one or more of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate;

[0010] (3) dissolving a titanium source in an organic solvent, adding the solution dropwise to solvent B to obtain solution C, and stirring the solution at room temperature for 2-6 hours; the titanium source is one or more of titanium tetrachloride, titanium tetrabromide, tetrabutyl titanate, and tetrapropyl titanate; the organic solvent is one or more of isopropanol, butanol, and methanol;

[0011] (5) heating under reflux at 40-80° C. for 3-12 h, evaporating the organic solvent to obtain solution D, and placing the solution D in a polytetrafluoroethylene-lined crystallization reactor at 150-200° C. for crystallization for 18-36 h;

[0012] (5) The crystallized sample is separated, washed, dried and calcined to obtain TS-1 catalyst.

[0013] The quaternary ammonium salt of chitosan is one or more of hydroxypropyltrimethylammonium fluoride chitosan, hydroxypropyltrimethylammonium chloride chitosan and hydroxypropyltrimethylammonium bromide chitosan.

[0014] The tetrapropylammonium hydroxide / silicon dioxide is 0.15-0.3 (mol / mol), preferably 0.15-0.28 (mol / mol).

[0015] The quaternary ammonium salt / silicon dioxide of the chitosan is 0.005-0.03 (mol / mol), preferably 0.015-0.024 (mol / mol).

[0016] The Si / Ti of the TS-1 catalyst is 20-80, preferably Si / Ti is 30-60.

[0017] The calcination temperature is 350-650° C. for 2-8 hours, preferably 450-600° C. for 4-6 hours.

[0018] The present invention also provides a TS-1 catalyst modification method, comprising: modifying the TS-1 catalyst with a liquid containing a silane coupling agent to obtain a modified TS-1 catalyst.

[0019] The TS-1 catalyst has a short b-axis mesoporous structure.

[0020] The TS-1 catalyst is obtained by the above method.

[0021] The modification was carried out by vapor deposition method.

[0022] The silane coupling agent is one or more of KH570, APTES and DETAS.

[0023] The silane coupling agent / silicon dioxide is 0.02-0.05 (mol / mol), preferably 0.025-0.045 (mol / mol).

[0024] The modification temperature of the silane coupling agent is 180-350°C, preferably 200-300°C.

[0025] The present invention also provides a method for preparing hydroquinone, wherein a phenol aqueous solution is hydroxylated to synthesize hydroquinone under the action of the modified TS-1 catalyst obtained by the modification method and with hydrogen peroxide as a hydroxylating agent.

[0026] The specific steps include: putting a phenol aqueous solution and a modified TS-1 catalyst into a reactor, and when the temperature reaches 30-100° C., adding hydrogen peroxide dropwise, and continuing to keep warm for reaction after the addition is completed to obtain a hydroquinone product.

[0027] The reaction temperature is 50-90°C.

[0028] The molar ratio of phenol to hydrogen peroxide is 0.5-5:1, preferably 2-4:1.

[0029] The hydrogen peroxide droplets are added within 60-90 minutes, preferably within 75-85 minutes.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The TS-1 catalyst synthesized with chitosan quaternary ammonium salt and tetrapropylammonium hydroxide as structure-directing agents has uniform particle size, smooth surface, short b-axis flakes and mesoporous structure. After the TS-1 catalyst is modified with a silane coupling agent, it is applied to the hydroxylation reaction of phenol. Due to its unique structure and the resulting steric hindrance effect, the product hydroquinone is more inclined to generate the para position, which improves the phenol conversion rate of the hydroxylation reaction and the para content in the product, and increases the economic benefits of the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the SEM image of TS-1 catalyst. DETAILED DESCRIPTION

[0033] Example 1

[0034] Preparation of TS-1 catalyst: 320 g of tetrabutyl silicate was added to an aqueous solution containing 0.35 g of hydroxypropyltrimethylammonium fluoride chitosan and 40.6 g of tetrapropylammonium hydroxide, and stirred vigorously at room temperature for 2 h; 26.75 g of tetrabutyl titanate was dissolved in isopropanol and added dropwise to the above solution, stirred at room temperature for 4 h, heated under reflux at 70 °C for 4 h, and then the isopropanol was evaporated; SiO 2 / TiO 2 =35, put the sample into a polytetrafluoroethylene lined crystallization kettle and crystallize at 180℃ for 24h, pour the crystallized sample into a centrifuge tube, centrifuge for 5min, collect the sample, wash it 3 times, dry it at 100℃ for 2h, and calcine it at 550℃ for 4h to obtain TS-1 catalyst, such as Figure 1 As shown, the particle size is uniform, the surface is smooth, and it has a short b-axis flake and mesoporous structure. The obtained TS-1 catalyst was further modified with a silane coupling agent by vapor deposition, and APTES gas was introduced at 240°C for 2 hours to obtain TS-1 catalyst-1 for preparing hydroquinone.

[0035] Example 2

[0036] 3g TS-1 catalyst-1 and 30% phenol aqueous solution were added to a three-necked flask. When the reaction temperature reached 85°C, hydrogen peroxide was slowly added dropwise. The molar ratio of phenol to hydrogen peroxide was 2:1. The hydrogen peroxide was added dropwise within 70-85 minutes. After the addition of hydrogen peroxide was completed, the reaction was continued for 1 hour. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 31.34%, the selectivity of dihydroxybenzene was 77.46%, and the ratio of hydroxybenzene to orthobenzene was 1.1.

[0037] Example 3

[0038] 3g TS-1 catalyst-1 and 40% phenol aqueous solution were added to a three-necked flask. When the reaction temperature reached 65°C, hydrogen peroxide was slowly added dropwise. The molar ratio of phenol to hydrogen peroxide was 2:1. The hydrogen peroxide was added dropwise within 70-85 minutes. After the addition of hydrogen peroxide was completed, the reaction was continued for 1 hour. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 35.77%, the selectivity of dihydroxybenzene was 80.02%, and the ratio of ortho-benzene was 1.4.

[0039] Example 4

[0040] 3g TS-1 catalyst-1 and 30% phenol aqueous solution were added to a three-necked flask. When the reaction temperature reached 65°C, hydrogen peroxide was slowly added dropwise. The ratio of phenol to hydrogen peroxide was 2:1. The hydrogen peroxide was added dropwise within 70-85 minutes. After the addition of hydrogen peroxide was completed, the reaction was continued for 1 hour. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 34.25%, the selectivity of dihydroxybenzene was 79.86%, and the ratio of ortho-benzene was 1.2.

[0041] Comparative Example 1

[0042] 3g TS-1 catalyst and 30% phenol aqueous solution were added to a three-necked flask. When the reaction temperature reached 65°C, hydrogen peroxide was slowly added dropwise. The molar ratio of hydrogen peroxide to phenol was 2:1. The hydrogen peroxide was added dropwise within 70-85 minutes. After the hydrogen peroxide was added dropwise, the reaction was continued for 1 hour. The obtained product was analyzed by gas chromatography, and the conversion rate of phenol was 25.65%, the selectivity of hydroquinone was 74.63%, and the ratio of ortho-hydroquinone was 0.9.

Claims

1. A method for synthesizing a TS-1 catalyst, characterized in that: The steps include: (1) mixing a structure directing agent with deionized water to obtain a solution A; the structure directing agent is a quaternary ammonium salt of chitosan and tetrapropylammonium hydroxide; (2) adding a silicon source to solution A and vigorously stirring at room temperature for 1-4 hours to obtain solution B; the silicon source is one or more of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate; (3) dissolving a titanium source in an organic solvent, adding the solution dropwise to solution B to obtain solution C, and stirring at room temperature for 2-6 hours; the titanium source is one or more of titanium tetrachloride, titanium tetrabromide, tetrabutyl titanate and tetrapropyl titanate; the organic solvent is one or more of isopropanol, butanol and methanol; (4) heating under reflux at 40-80° C. for 3-12 h, evaporating the organic solvent to obtain solution D, and placing the solution D in a polytetrafluoroethylene-lined crystallization reactor at 150-200° C. for crystallization for 18-36 h; (5) The crystallized sample is separated, washed, dried and calcined to obtain the TS-1 catalyst.

2. A method for synthesizing a TS-1 catalyst as claimed in claim 1, characterized in that: The molar ratio of tetrapropylammonium hydroxide to silicon dioxide is 0.15-0.3; and / or, The molar ratio of the quaternary ammonium salt of chitosan to silicon dioxide is 0.005-0.03; and / or, The quaternary ammonium salt of chitosan is one or more of hydroxypropyltrimethylammonium fluoride chitosan, hydroxypropyltrimethylammonium chloride chitosan and hydroxypropyltrimethylammonium bromide chitosan; and / or The Si / Ti of the TS-1 catalyst is 20-80.

3. A method for modifying a TS-1 catalyst, characterized in that: The method comprises modifying a TS-1 catalyst by using a liquid containing a silane coupling agent to obtain a modified TS-1 catalyst.

4. A method for modifying a TS-1 catalyst as claimed in claim 3, characterized in that: The TS-1 catalyst has a short b-axis mesoporous structure.

5. A method for modifying a TS-1 catalyst as claimed in claim 4, characterized in that: The TS-1 catalyst is obtained by the method according to any one of claims 1 or 2.

6. A method for modifying a TS-1 catalyst as claimed in claim 3, characterized in that: Modification by vapor deposition; and / or, The silane coupling agent is one or more of KH570, APTES and DETAS; and / or, The molar ratio of the silane coupling agent to silicon dioxide is 0.02-0.

05.

7. A method for modifying a TS-1 catalyst as claimed in claim 3, characterized in that: The modification temperature of the silane coupling agent is 180-350°C.

8. A method for preparing hydroquinone, characterized in that: Under the action of the modified TS-1 catalyst obtained by the modification method according to any one of claims 3 to 7, the phenol aqueous solution is hydroxylated to synthesize diphenol using hydrogen peroxide as a hydroxylating agent.

9. A method for preparing hydroquinone as claimed in claim 8, characterized in that: The specific steps include: putting a phenol aqueous solution and a modified TS-1 catalyst into a reactor, and when the reaction temperature reaches 30-100° C., adding hydrogen peroxide dropwise, and continuing to keep the temperature for reaction after the addition is completed to obtain a hydroquinone product.

10. A method for preparing hydroquinone according to claim 9, characterized in that: The reaction temperature is 50-90°C; and / or, The molar ratio of phenol to hydrogen peroxide is 0.5-5:1; and / or, The hydrogen peroxide solution is added dropwise within 60-90 minutes.

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