Preparation method of catechol and hydroquinone
By using a porous carbon-supported nano-metal oxide composite catalyst to catalyze the hydroxylation reaction of phenol with hydrogen peroxide in a mixed solvent of small molecule dicarboxylic acids, the problems of low phenol conversion rate and environmental pollution in existing technologies have been solved, and high-selectivity and low-energy-consumption hydroquinone production has been achieved.
Patent Information
- Application Number
- CN202511648483.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-12
- Publication Date
- 2026-01-23
AI Technical Summary
Existing methods for synthesizing hydroquinone by hydroxylation of phenol have problems such as low phenol conversion rate, poor product selectivity, strong equipment corrosivity, and potential environmental pollution risks.
A porous carbon-supported nano-metal oxide composite catalyst was used to carry out the hydroxylation reaction of phenol and hydrogen peroxide in a mixed solvent of small molecule dicarboxylic acids. The catalyst was synthesized in situ at high temperature from soluble carbon source, nitrogen source, copper salt and zinc salt to form a uniformly distributed porous carbon framework and nano-metal oxide composite, thus optimizing the reaction pathway.
It improves the conversion rate of phenol and the selectivity of catechol and hydroquinone, reduces the reaction temperature and energy consumption, avoids environmental pollution, and conforms to the concept of green environmental protection.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of catechol synthesis, and particularly relates to a preparation method of catechol and hydroquinone. BACKGROUND
[0002] Catechol (including catechol and hydroquinone) is an important chemical raw material, and has a wide range of application fields. Catechol, also known as pyrocatechol, is a raw material for producing vanillin, piperonal and other spices, and is an intermediate of amino methyl carbamate pesticides such as carbofuran, propetamphos and dihydrocarbam, is a precursor of polymerization inhibitor and antioxidant, and can also be used to manufacture coughing element, eugenol, berberine and isopropyl adrenaline. Hydroquinone, also known as hydroquinone, is an important raw material, additive and intermediate of rubber, medicine, dye, pesticide and fine chemical industry, and is mainly used for manufacturing black and white developing agent of photographic film, producing anthraquinone dye and azo dye, synthesizing gas desulfurization catalyst, manufacturing anti-aging agent of rubber and plastic, monomer polymerization inhibitor, stabilizer and antioxidant of food and paint varnish, petroleum anticoagulant and the like.
[0003] Traditional production processes of hydroquinone include aniline oxidation method and p-diisopropylbenzene oxidation method, and production processes of catechol include o-chlorophenol and o-methoxyphenol hydrolysis method. These production methods have problems of multiple reaction steps, complex process, large amount of wastewater discharge, low production efficiency and serious corrosion. In comparison, the method of preparing catechol by direct hydroxylation of phenol has simple steps and no environmental pollution hidden danger, and becomes a mainstream process for producing catechol. Since phenol is more easily oxidized than phenol in the synthesis of catechol by hydroxylation, the selection of catalyst and process optimization in the production process of phenol hydroxylation are extremely important.
[0004] At present, the route of synthesizing catechol by phenol hydroxylation with hydrogen peroxide includes Rhone-Poulenc method, Brichima method and Enichem method. The Rhone-Poulenc method uses HClO4 as a catalyst and H3PO4 as a cocatalyst, has strong corrosion, has extremely high requirements for equipment material and corrosion prevention, and has environmental pollution hidden danger in post-treatment. The method has low phenol conversion rate per pass and high energy consumption. The Brichima method uses a mixture of iron salt and cobalt salt as a catalyst, although the corrosion grade and pollution hidden danger are reduced, but the problems of low phenol conversion rate and poor product selectivity still exist. The Enichem method uses titanium-silicon molecular sieve as a catalyst, the method is safe, the phenol conversion rate is improved to a certain extent, but the synthesis process of titanium-silicon molecular sieve is complex, the cost is high, and the performance is unstable, and the catalytic activity needs to be recovered by regeneration frequently, and the phenol conversion rate and product selectivity still have a large space for improvement.
[0005] Therefore, it is of great significance to study a new method for preparing hydroquinone and catechol by phenol hydroxylation, and to improve the phenol conversion rate and the selectivity of catechol. SUMMARY
[0006] The present application aims at providing a preparation method of catechol and hydroquinone to overcome the defects of the prior art.
[0007] To achieve the above-mentioned purposes, the present application provides the following technical solutions. The present application provides a preparation method of catechol and hydroquinone, which comprises the following steps: under the condition of a catalyst, phenol and hydrogen peroxide are subjected to a hydroxylation reaction. The hydroxylation reaction is carried out in a mixed solvent containing a small-molecule dibasic acid. The catalyst is a porous carbon loaded nanometer metal oxide composite catalyst.
[0008] Preferably, the small-molecule dibasic acid contains one or more of oxalic acid, malonic acid and succinic acid. The mixed solvent contains water and an organic solvent, and the volume ratio of water to the organic solvent is 1:10-20.
[0009] Preferably, the molar ratio of phenol to hydrogen peroxide is 1-4:1, the molar ratio of phenol to small-molecule dibasic acid is 1:0.2-0.5, the mass ratio of phenol to mixed solvent is 1:1-3, and the mass of the catalyst is 0.02-0.1% of the mass of phenol.
[0010] Preferably, the metal element in the porous carbon loaded nanometer metal oxide composite catalyst is copper and zinc.
[0011] Preferably, the preparation method of the porous carbon loaded nanometer metal oxide composite catalyst comprises the following steps: 1) dissolving a soluble carbon source, a soluble nitrogen source, a soluble copper salt and a soluble zinc salt in water to form a mixed solution; 2) sequentially performing pre-carbonization and carbonization on the mixed solution to obtain the porous carbon loaded nanometer metal oxide composite catalyst.
[0012] Preferably, the soluble carbon source contains one or more of glucose, sucrose, lactose, maltose and starch. The soluble nitrogen source contains urea and / or melamine. The soluble copper salt contains one or more of copper nitrate, copper chloride and copper sulfate. The soluble zinc salt contains one or more of zinc nitrate, zinc chloride and zinc sulfate.
[0013] Preferably, the mass ratio of the soluble carbon source to the soluble nitrogen source is 1:0.5-2, the mass of the soluble copper salt is 3-8% of the mass of the soluble carbon source, and the molar ratio of the soluble copper salt to the soluble zinc salt is 1:1-3.
[0014] Preferably, the pre-carbonization temperature is 150-250℃, the pre-carbonization time is 1-3h, and the temperature rising rate to the pre-carbonization temperature is 0.5-2℃ / min; The carbonization is performed in a nitrogen atmosphere, the carbonization temperature is 450-550℃, the carbonization time is 1-3h, and the temperature rising rate to the carbonization temperature is 2-4℃ / min.
[0015] Preferably, the hydroxylation reaction temperature is 20-40℃, and the hydroxylation reaction time is 4-8h.
[0016] The present application has the following advantages: 1) The present application uses phenol as raw material to prepare o-dihydroxybenzene and p-dihydroxybenzene through hydroxylation reaction, which is simple in steps, mild in conditions, free of harmful by-products, and free of environmental pollution, and thus conforms to the green environmental protection concept.
[0017] 2) The addition of small molecular dibasic acid in the hydroxylation reaction system accelerates the hydroxylation reaction process, improves the phenol conversion rate, inhibits the deep oxidation of dihydroxybenzene, and improves the selectivity of o-dihydroxybenzene and p-dihydroxybenzene; the porous carbon loaded nanometer metal oxide composite catalyst catalyzes the hydroxylation reaction, the composite catalyst is synthesized in situ, the carbon source, nitrogen source, copper salt and zinc salt are carbonized at high temperature to form porous carbon, and the metal components are uniformly distributed in the porous carbon carrier, realizing the in-situ compounding of the porous carbon skeleton and nanometer metal oxide, avoiding the problem of uneven distribution of metal in the traditional impregnation loading method, and improving the catalytic activity; the interaction between the nanometer metal oxide and the porous carbon can optimize the activation path of hydrogen peroxide, inhibit the deep oxidation of dihydroxybenzene, reduce the yield of deep oxidation by-products (such as benzoquinone), and thus improve the selectivity of target products; the porous carbon loaded nanometer metal oxide composite catalyst can significantly reduce the reaction temperature and energy consumption.
[0018] 3) Copper and zinc are used as metal elements, copper and zinc cooperate with each other, and by reasonably controlling the ratio of copper and zinc, the selectivity of the composite catalyst for catalyzing the hydroxylation reaction to generate o-dihydroxybenzene and p-dihydroxybenzene is stronger. DETAILED DESCRIPTION
[0019] The present application provides a preparation method of o-dihydroxybenzene and p-dihydroxybenzene, which comprises hydroxylation reaction of phenol and hydrogen peroxide under the condition of a catalyst; The hydroxylation reaction is performed in a mixed solvent containing small molecular dibasic acid. The catalyst is a porous carbon loaded nanometer metal oxide composite catalyst.
[0020] In the present application, the small molecular dibasic acid preferably comprises one or more of oxalic acid, malonic acid and succinic acid. The mixed solvent preferably comprises water and an organic solvent, and the volume ratio of water to the organic solvent is preferably 1:10-20, further preferably 1:12-18, and more preferably 1:15.
[0021] In the present application, the organic solvent preferably comprises one or more of methanol, acetone and acetonitrile. The hydroxylation reaction is carried out in a mixed solvent comprising water and an organic solvent, which helps to achieve high selectivity in the production of o-dihydroxybenzene and p-dihydroxybenzene.
[0022] In the present application, the molar ratio of the phenol to hydrogen peroxide is preferably 1-4:1, further preferably 2-3:1, and more preferably 2.5:1; the molar ratio of the phenol to the small molecule diacid is preferably 1:0.2-0.5, further preferably 1:0.25-0.4, and more preferably 1:0.3-0.35; the mass ratio of the phenol to the mixed solvent is preferably 1:1-3, further preferably 1:1.5-2.5, and more preferably 1:2; and the mass of the catalyst is preferably 0.02-0.1% of the mass of the phenol, further preferably 0.04-0.08%, and more preferably 0.05-0.07%.
[0023] In the present application, the metal element in the porous carbon-supported nanometal oxide composite catalyst is preferably copper and zinc.
[0024] In the present application, the preparation method of the porous carbon-supported nanometal oxide composite catalyst preferably comprises the following steps: 1) dissolving a soluble carbon source, a soluble nitrogen source, a soluble copper salt and a soluble zinc salt in water to form a mixed solution; 2) sequentially performing pre-carbonization and carbonization on the mixed solution to obtain the porous carbon-supported nanometal oxide composite catalyst.
[0025] In the present application, the soluble carbon source preferably comprises one or more of glucose, sucrose, lactose, maltose and starch; The soluble nitrogen source preferably comprises urea and / or melamine; The soluble copper salt preferably comprises one or more of copper nitrate, copper chloride and copper sulfate; The soluble zinc salt preferably comprises one or more of zinc nitrate, zinc chloride and zinc sulfate.
[0026] In the present application, the mass ratio of the soluble carbon source to the soluble nitrogen source is preferably 1:0.5-2, further preferably 1:0.8-1.5, and more preferably 1:1-1.2; the mass of the soluble copper salt is preferably 3-8% of the mass of the soluble carbon source, further preferably 4-7%, and more preferably 5-6%; and the molar ratio of the soluble copper salt to the soluble zinc salt is preferably 1:1-3, further preferably 1:1.5-2.5, and more preferably 1:2.
[0027] In the present application, the amount of water used in step 1) is preferably enough to completely dissolve the soluble carbon source, the soluble nitrogen source, the soluble copper salt and the soluble zinc salt.
[0028] In the present application, the temperature of the pre-carbonization is preferably 150-250℃, further preferably 180-220℃, and more preferably 200℃; the time of the pre-carbonization is preferably 1-3h, further preferably 1.5-2.5h, and more preferably 2h; and the heating rate for heating to the pre-carbonization temperature is preferably 0.5-2℃ / min, further preferably 0.8-1.5℃ / min, and more preferably 1-1.2℃ / min. The carbonization is preferably carried out in a nitrogen atmosphere, the temperature of the carbonization is preferably 450-550℃, further preferably 480-520℃, and more preferably 500℃; the time of the carbonization is preferably 1-3h, further preferably 1.5-2.5h, and more preferably 2h; and the heating rate for heating to the carbonization temperature is preferably 2-4℃ / min, further preferably 2.5-3.5℃ / min, and more preferably 3℃ / min.
[0029] In the present application, the temperature of the hydroxylation reaction is preferably 20-40℃, further preferably 25-35℃, and more preferably 30℃; and the time of the hydroxylation reaction is preferably 4-8h, further preferably 5-7h, and more preferably 6h.
[0030] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.
[0031] Example 1
[0032] Dissolve glucose, urea, copper nitrate and zinc chloride in water to obtain a mixed solution. The mass ratio of glucose to urea is 1:2, the mass of copper nitrate is 3% of the mass of glucose, the molar ratio of copper nitrate to zinc chloride is 1:2, and the mass of water is 200% of the mass of glucose. The mixed solution is heated to 200℃ at a rate of 1℃ / min, and pre-carbonization is carried out at 200℃ for 1h to obtain an intermediate. The intermediate is heated to 450℃ at a rate of 3℃ / min in a nitrogen atmosphere, and carbonization is carried out at 450℃ for 3h to obtain a porous carbon supported nano-metal oxide composite catalyst.
[0033] Phenol, hydrogen peroxide (mass fraction of hydrogen peroxide is 50%) were dissolved in mixed solvent (the mixed solvent was composed of water and acetonitrile with a volume ratio of 1:15) to obtain a reaction system. The molar ratio of phenol to hydrogen peroxide was 2.5:1, and the mass ratio of phenol to mixed solvent was 1:1. Oxalic acid, porous carbon supported nanometer metal oxide composite catalyst were added to the reaction system, the molar ratio of phenol to oxalic acid was 1:0.5, and the mass of porous carbon supported nanometer metal oxide composite catalyst was 0.05% of the mass of phenol. The reaction system was subjected to hydroxylation reaction at 30℃ for 4h. After the reaction was completed, the contents of phenol, benzoquinone, catechol and hydroquinone in the product were analyzed by high performance liquid chromatography, and the phenol conversion rate, benzoquinone selectivity and ortho / para ratio of diols (catechol / hydroquinone) were calculated. The results are shown in Table 1.
[0034] Example 2
[0035] Sucrose, melamine, copper sulfate and zinc nitrate were dissolved in water to obtain a mixed solution. The mass ratio of sucrose to melamine was 1:1, the mass of copper sulfate was 8% of the mass of sucrose, the molar ratio of copper sulfate to zinc nitrate was 1:3, and the mass of water was 180% of the mass of sucrose. The mixed solution was heated to 150℃ at a rate of 2℃ / min, and then was kept at 150℃ for 2h to obtain an intermediate. The intermediate was heated to 550℃ at a rate of 4℃ / min in a nitrogen atmosphere, and then was kept at 550℃ for 2h to obtain a porous carbon supported nanometer metal oxide composite catalyst.
[0036] Phenol, hydrogen peroxide (mass fraction of hydrogen peroxide is 50%) were dissolved in mixed solvent (the mixed solvent was composed of water and acetone with a volume ratio of 1:10) to obtain a reaction system. The molar ratio of phenol to hydrogen peroxide was 1:1, and the mass ratio of phenol to mixed solvent was 1:2. Succinic acid, porous carbon supported nanometer metal oxide composite catalyst were added to the reaction system, the molar ratio of phenol to succinic acid was 1:0.3, and the mass of porous carbon supported nanometer metal oxide composite catalyst was 0.1% of the mass of phenol. The reaction system was subjected to hydroxylation reaction at 20℃ for 6h. After the reaction was completed, the contents of phenol, benzoquinone, catechol and hydroquinone in the product were analyzed by high performance liquid chromatography, and the phenol conversion rate, benzoquinone selectivity and ortho / para ratio of diols (catechol / hydroquinone) were calculated. The results are shown in Table 1.
[0037] Example 3
[0038] Dissolve starch, urea, copper chloride and zinc sulfate in water to obtain a mixed solution. The mass ratio of starch and urea is 1:0.5, the mass of copper chloride is 5% of the mass of starch, the molar ratio of copper chloride and zinc sulfate is 1:1, and the mass of water is 160% of the mass of starch. The mixed solution is heated to 250℃ at a rate of 0.5℃ / min, and the intermediate is obtained by pre-carbonizing at 250℃ for 3h. The intermediate is heated to 500℃ at a rate of 2℃ / min in a nitrogen atmosphere, and the porous carbon loaded nanometer metal oxide composite catalyst is obtained by carbonizing at 500℃ for 1h.
[0039] Dissolve phenol and hydrogen peroxide (mass fraction of hydrogen peroxide is 50%) in a mixed solvent (the mixed solvent is composed of water and methanol in a volume ratio of 1:20) to obtain a reaction system. The molar ratio of phenol and hydrogen peroxide is 4:1, and the mass ratio of phenol and mixed solvent is 1:3. Add malonic acid and porous carbon loaded nanometer metal oxide composite catalyst to the reaction system, and the molar ratio of phenol and malonic acid is 1:0.2. The mass of porous carbon loaded nanometer metal oxide composite catalyst is 0.02% of the mass of phenol. The reaction system is subjected to hydroxylation reaction at 40℃ for 8h. After the reaction is completed, the contents of phenol, benzoquinone, catechol and hydroquinone in the product are analyzed by high performance liquid chromatography, and the phenol conversion rate, benzoquinone selectivity and ortho / para ratio of diphenols (catechol / hydroquinone) are calculated. The results are shown in Table 1.
[0040] Comparative Example 1
[0041] Replace the mixed solvent in Example 1 with water, and the other conditions are the same as in Example 1.
[0042] Comparative Example 2
[0043] Omit the oxalic acid in Example 1, and the other conditions are the same as in Example 1.
[0044] Comparative Example 3
[0045] Modify the molar ratio of copper nitrate and zinc chloride in Example 1 to 1:0.5, and omit the oxalic acid, and the other conditions are the same as in Example 1.
[0046] Comparative Example 4
[0047] Replace the zinc chloride in Example 1 with iron chloride, and the molar ratio of copper nitrate and iron chloride is 1:4, and the other conditions are the same as in Example 1.
[0048] Comparative Example 5
[0049] At normal temperature, titanium silicalite (TS-1) is impregnated in a mixed solution of copper nitrate and zinc chloride (the molar ratio of copper to zinc is 1:2) by an equal volume impregnation method, impregnated for 6 hours, then dried at 90℃ for 4 hours, and then calcined at 450℃ for 12 hours to obtain a titanium silicalite supported nanometer metal oxide composite catalyst.
[0050] Phenol and hydrogen peroxide (50% of mass fraction) are dissolved in a mixed solvent (the mixed solvent is composed of water and acetonitrile in a volume ratio of 1:15) to obtain a reaction system. The molar ratio of phenol to hydrogen peroxide is 2.5:1, and the mass ratio of phenol to the mixed solvent is 1:1. Oxalic acid and the titanium silicalite supported nanometer metal oxide composite catalyst are added to the reaction system, the molar ratio of phenol to oxalic acid is 1:0.5, and the mass of the titanium silicalite supported nanometer metal oxide composite catalyst is 0.05% of the mass of phenol. The reaction system is subjected to a hydroxylation reaction at 30℃ for 4 hours. After the reaction is completed, the contents of phenol, benzoquinone, catechol and hydroquinone in the product are analyzed by high performance liquid chromatography, and the conversion rate of phenol, the selectivity of benzoquinone and the ortho / para ratio of diols (catechol / hydroquinone) are calculated. The results are shown in Table 1.
[0051] Table 1 Analysis results of products
[0052] It can be seen from the above examples that the preparation method of catechol and hydroquinone is provided, small molecule diacid is added to the reaction system, and the porous carbon supported nanometer metal oxide composite catalyst is used as the catalyst for the phenol hydroxylation reaction to accelerate the progress of the phenol hydroxylation reaction and improve the conversion rate of phenol. The preparation method of the present application can selectively perform the hydroxylation reaction of phenol, effectively inhibit the deep oxidation of the product, and reduce the selectivity of the byproduct (benzoquinone). The porous carbon supported nanometer metal oxide composite catalyst is synthesized in situ by a method, the metal elements are uniformly dispersed in the porous carbon during the formation of the porous carbon, copper and zinc are selected as the main active components, the ratio of copper to zinc is reasonably controlled, the conversion rate of the phenol hydroxylation reaction and the yield of the product diol are improved. The conversion rate of phenol is more than 42% by the preparation method of the present application, and the selectivity of benzoquinone is less than 3%.
[0053] The above only describes the preferred embodiments of the present application, and it should be noted that the ordinary skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A method for producing catechol, hydroquinone, characterized by, The phenol and hydrogen peroxide are subjected to a hydroxylation reaction under the condition of a catalyst; The hydroxylation reaction is carried out in a mixed solvent containing a small molecular dibasic acid; The catalyst is a porous carbon loaded nanometer metal oxide composite catalyst.
2. The production method according to claim 1, characterized by, The small molecular dibasic acid contains one or more of oxalic acid, malonic acid and succinic acid; The mixed solvent contains water and an organic solvent, and the volume ratio of water to the organic solvent is 1:10-20.
3. The production method according to claim 1 or 2, characterized by, The molar ratio of the phenol to hydrogen peroxide is 1-4:1, the molar ratio of the phenol to the small molecular dibasic acid is 1:0.2-0.5, the mass ratio of the phenol to the mixed solvent is 1:1-3, and the mass of the catalyst is 0.02-0.1% of the mass of the phenol.
4. The production method according to claim 3, characterized by, The metal element in the porous carbon loaded nanometer metal oxide composite catalyst is copper and zinc.
5. The preparation method according to claim 4, characterized in that, The preparation method of the porous carbon loaded nanometer metal oxide composite catalyst comprises the following steps: 1) dissolving a soluble carbon source, a soluble nitrogen source, a soluble copper salt and a soluble zinc salt in water to form a mixed solution; 2) sequentially performing pre-carbonization and carbonization on the mixed solution to obtain the porous carbon loaded nanometer metal oxide composite catalyst.
6. The production method according to claim 5, wherein The soluble carbon source contains one or more of glucose, sucrose, lactose, maltose and starch; The soluble nitrogen source contains urea and / or melamine; The soluble copper salt contains one or more of copper nitrate, copper chloride and copper sulfate; The soluble zinc salt contains one or more of zinc nitrate, zinc chloride and zinc sulfate.
7. The production method according to claim 5 or 6, characterized by, The mass ratio of the soluble carbon source to the soluble nitrogen source is 1:0.5-2, the mass of the soluble copper salt is 3-8% of the mass of the soluble carbon source, and the molar ratio of the soluble copper salt to the soluble zinc salt is 1:1-3.
8. The production method according to claim 7, characterized by, The pre-carbonization temperature is 150-250°C, the pre-carbonization time is 1-3h, and the temperature rising rate to the pre-carbonization temperature is 0.5-2°C / min; The carbonization is carried out in a nitrogen atmosphere, the carbonization temperature is 450-550°C, the carbonization time is 1-3h, and the temperature rising rate to the carbonization temperature is 2-4°C / min.
9. The method of claim 1, wherein, The hydroxylation reaction temperature is 20-40°C, and the hydroxylation reaction time is 4-8h.