A catalyst for efficiently synthesizing 4-methylcatechol from p-cresol and a preparation method and application thereof

Abstract

The application discloses a catalyst for efficiently synthesizing 4-methyl catechol from p-cresol and a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: dissolving an active component in water, impregnating the active component on a carrier by using an equal-volume impregnation method, drying after sufficient impregnation, calcining in a muffle furnace, and extruding the product after calcination and a binder into a strip, drying, and calcining again in the muffle furnace. The active component is one of the following: 1) iron salt and vanadium salt, the mass ratio of the two is 1:0.5-2, and the total mass of the two is 40-70% of the mass of the carrier; 2) main metal salt and doped metal salt, the mass ratio of the two is 7.5-50:1, and the total mass of the two is 20-42% of the mass of the carrier. The main metal salt is iron salt or vanadium salt, and the doped metal salt is cobalt salt, nickel salt, copper salt or palladium salt. The catalyst is applied to catalyze the synthesis of 4-methyl catechol from p-cresol, simplifies the synthesis route, improves the production efficiency, has high catalyst activity, and has high target product yield and few by-products.

Description

Technical Field

[0001] This invention relates to the field of organic chemical synthesis, specifically to a catalyst for the efficient synthesis of 4-methylcatechol from p-cresol, its preparation method, and its application. Background Technology

[0002] 4-Methylcatechol, chemically known as 3,4-dihydroxytoluene, 4-methyl-1,2-benzenediol, or homocatechol, is typically a white or off-white crystalline powder. It is an important organic compound with wide applications in various fields, including chemical engineering and pharmaceuticals. In organic synthesis, 4-methylcatechol serves as an important raw material or intermediate for synthesizing biologically active compounds or functional materials. In the pharmaceutical field, due to its unique chemical structure, it can be used as a precursor or key component in the synthesis of specific drugs, such as in the synthesis of antibacterial agents, dyes, and fragrances. Industrially, it is used to prepare developing agents, rubber antioxidants or anti-oxidants, polymerization inhibitors, and stabilizers to improve product performance or extend product lifespan.

[0003] There are many methods for synthesizing 4-methylcatechol, including liquefaction lignin method, halobenzene hydrolysis method, direct hydroxylation method, 4-methylguaiacol hydrolysis method, and magnesium phenol-formaldehyde method.

[0004] Chinese patent CN107216238A discloses a method for preparing 4-methylcatechol using the magnesium alkoxide method. This method uses p-cresol as a raw material, reacting it with magnesium alkoxide to first generate magnesium p-cresol, then synthesizing 3-methylsalicylaldehyde from magnesium p-cresol, and finally oxidizing it with hydrogen peroxide to synthesize 4-methylcatechol. This method offers mild reaction conditions and high yields, but the operation steps are relatively cumbersome and require reagents such as toluene and paraformaldehyde, which is not conducive to environmental protection and large-scale industrial production.

[0005] Chinese patent CN103864578A discloses a method for preparing 4-methylcatechol from 2-methoxy-4-methylphenol. In this method, under light-protected and inert gas conditions, sodium sulfite is added while hydrogen bromide gas is continuously introduced to carry out a one-step demethylation reaction. Following neutralization, extraction, and centrifugation, 4-methylcatechol is obtained. This method uses natural raw materials and has a high product yield, but the operation is cumbersome, the reaction conditions are relatively harsh, and a large amount of hydrogen bromide is used.

[0006] Chinese patent CN1298857A discloses a method for preparing 4-methylcatechol by hydroxylation of p-cresol with a certain amount of titanium silicate molecular sieve under the action of hydrogen peroxide. This method has a relatively simple and clean process, but it has drawbacks such as high reaction temperature and low yield.

[0007] Although 4-methylcatechol can be synthesized artificially using chemical methods, existing methods suffer from drawbacks such as long reaction routes, cumbersome operating conditions, or severe environmental pollution. Therefore, developing a simple, efficient, environmentally friendly method for preparing 4-methylcatechol that is suitable for large-scale industrial production is of great significance. Summary of the Invention

[0008] In view of the above-mentioned technical problems existing in the prior art, the purpose of the present invention is to provide a catalyst for the efficient synthesis of 4-methylcatechol from p-cresol, its preparation method and application.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing a catalyst for the efficient synthesis of 4-methylcatechol from p-cresol includes the following steps: dissolving the active component in water and impregnating it onto a support using an equal-volume impregnation method; drying the impregnated component after thorough impregnation; calcining the calcined product in a muffle furnace at 450-600℃ for 1-4 hours; extruding the calcined product with a binder into strips; drying the strips; and calcining the product again in a muffle furnace at 450-600℃ for 1-4 hours to obtain the catalyst.

[0011] The active component is one of the following:

[0012] 1) Iron salts and vanadium salts, with a mass ratio of 1:0.5-2, and the total mass of the two is 40-70% of the carrier mass;

[0013] 2) The mass ratio of the main metal salt and the doped metal salt is 7.5-50:1, and the total mass of the two is 20-42% of the carrier mass. The main metal salt is an iron salt or a vanadium salt, and the doped metal salt is a cobalt salt, a nickel salt, a copper salt, or a palladium salt.

[0014] Furthermore, the iron salt, cobalt salt, nickel salt, and copper salt are respectively nitrate, sulfate, chloride, or acetate; the vanadium salt is sodium vanadate or sodium pyrovanadate; and the palladium salt is palladium acetate.

[0015] Furthermore, when the main metal salt is an iron salt and the doped metal salt is a cobalt salt or a copper salt, the mass ratio of the main metal salt to the doped metal salt is 20-40:1.

[0016] Furthermore, when the main metal salt is an iron salt and the doped metal salt is a nickel salt, the mass ratio of the main metal salt to the doped metal salt is 7.5-10:1, and the total mass of the two is 30-35% of the carrier mass.

[0017] Furthermore, when the main metal salt is a vanadium salt and the doped metal salt is a palladium salt, the mass ratio of the main metal salt to the doped metal salt is 45-50:1, and the total mass of the two is 20-25% of the carrier mass.

[0018] Furthermore, the carrier is a TS-1 molecular sieve, an MCM-41 molecular sieve, or a ZSM-5 molecular sieve.

[0019] This invention also provides the application of the catalyst in the catalytic synthesis of 4-methylcatechol from p-cresol. A reaction solution is obtained by mixing p-cresol, an alcohol solvent, and hydrogen peroxide. This reaction solution is then passed through a fixed bed packed with the catalyst for a catalytic reaction to generate 4-methylcatechol. The catalytic reaction is carried out at a temperature of 40-60°C and a pressure of atmospheric pressure, with a mass hourly space velocity (WHSV) of 0.1-1 h⁻¹. -1 .

[0020] Furthermore, the alcohol solvent is methanol or ethanol, and the mass ratio of p-cresol to the alcohol solvent is 1:0.5-2, preferably 1:1; the mass ratio of p-cresol to the H2O2 component in hydrogen peroxide is 1:0.5-3, preferably 1:1-1.5.

[0021] Compared with existing technologies, the beneficial effects of this invention are: the catalyst preparation method of this invention is simple and inexpensive, and the prepared catalyst has high catalytic activity and stability, possessing significant industrial application value. When applied to the synthesis of 4-methylcatechol from p-cresol, this catalyst simplifies the synthesis route, improves production efficiency, exhibits high catalyst activity, high yield of the target product, and fewer byproducts. It reduces the generation of waste salts and wastewater and environmental pollution associated with traditional multi-step reactions, meeting the requirements of low-carbon, environmentally friendly, and sustainable development, and is beneficial for large-scale industrial production.

[0022] The implementation of this invention will provide a stable and reliable source of 4-methylcatechol for the pharmaceutical, chemical and other fields, and promote the development of related industries. Detailed implementation method:

[0023] In this invention, the content and purity of the product are detected by gas chromatography. The invention is described in detail below with reference to some specific embodiments, but the invention is not limited to these embodiments in any way. Any modifications, equivalent substitutions, and improvements made based on the idea and principle of this invention should be included within the scope of protection of this invention.

[0024] In this embodiment of the invention, TS-1 molecular sieve, MCM-41 molecular sieve, and ZSM-5 molecular sieve were purchased from Zhuoran Environmental Protection Technology (Dalian) Co., Ltd. The TS-1 molecular sieve has an average pore size greater than 0.56 nanometers and a specific surface area of ​​approximately 370 m². 2 / g; MCM-41 molecular sieve has an average pore size of 2.5–3.5 nm and a specific surface area of ​​approximately 425 m². 2 / g; ZSM-5 molecular sieve has an average pore size of 0.55–0.6 nm and a specific surface area greater than 350 m². 2 / g. Ti-MWW molecular sieve was purchased from Angxing New Materials Changzhou Co., Ltd., with an average pore size greater than 0.4 nm and a specific surface area greater than 450 m². 2 / g.

[0025] Example 1:

[0026] Using water as a solvent, 15g of sodium vanadate and 15g of ferric nitrate were loaded onto 50g of TS-1 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours, and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as catalyst A.

[0027] Example 2:

[0028] Using water as a solvent, 0.5g of cobalt nitrate and 20g of ferric nitrate were loaded onto 50g of TS-1 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours, and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as catalyst B.

[0029] Example 3:

[0030] Using water as a solvent, 0.5g of copper nitrate and 10g of ferric chloride were loaded onto 50g of TS-1 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours, and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as catalyst C.

[0031] Example 4:

[0032] Using water as a solvent, 2g of nickel nitrate and 15g of ferric sulfate were loaded onto 50g of MCM-41 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours, and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Guess powder binder (the mass of the binder was 5% of the mass of the calcined product) was then added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as catalyst D.

[0033] Example 5:

[0034] Using water as a solvent, 0.2 g of palladium acetate and 10 g of sodium vanadate were loaded onto 50 g of ZSM-5 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120 °C for 3 hours and then calcined in a muffle furnace at 550 °C for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120 °C for 3 hours, and then calcined again in a muffle furnace at 550 °C for 3 hours to obtain the final catalyst, denoted as catalyst E.

[0035] Example 6:

[0036] Using water as a solvent, 20g of ferric nitrate was loaded onto 50g of TS-1 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as catalyst F.

[0037] Example 7:

[0038] Using water as a solvent, 10g of copper nitrate and 0.5g of ferric chloride were loaded onto 50g of TS-1 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours, and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as catalyst G.

[0039] Example 8:

[0040] Using water as a solvent, 0.2 g of palladium acetate and 15 g of copper nitrate were loaded onto 50 g of ZSM-5 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120 °C for 3 hours and then calcined in a muffle furnace at 550 °C for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120 °C for 3 hours, and then calcined again in a muffle furnace at 550 °C for 3 hours to obtain the final catalyst, denoted as catalyst H.

[0041] Example 9:

[0042] Using water as a solvent, 0.5g of zinc nitrate and 20g of ferric nitrate were loaded onto 50g of TS-1 molecular sieve using an equal-volume impregnation method. The mixture was dried at 120℃ for 3 hours, and then calcined in a muffle furnace at 550℃ for 3 hours for later use. Guess powder binder (the mass of the binder was 5% of the mass of the calcined product) was then added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120℃ for 3 hours, and then calcined again in a muffle furnace at 550℃ for 3 hours to obtain the final catalyst, denoted as Catalyst I.

[0043] Example 10:

[0044] Using water as a solvent, TS-1 molecular sieve without metal loading was dried at 120°C for 3 hours, and then calcined in a muffle furnace at 550°C for 3 hours for later use. Then, guar gum powder binder (the mass of the binder is 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120°C for 3 hours, and then calcined again at 550°C in a muffle furnace for 3 hours to obtain the final catalyst, denoted as catalyst J.

[0045] Example 11:

[0046] Using water as a solvent, 0.5 g of copper nitrate and 10 g of ferric chloride were loaded onto 50 g of Ti-MWW molecular sieve using an equal-volume impregnation method. The mixture was dried at 120 °C for 3 hours and then calcined in a muffle furnace at 550 °C for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120 °C for 3 hours, and then calcined again in a muffle furnace at 550 °C for 3 hours to obtain the final catalyst, denoted as catalyst K.

[0047] Example 12:

[0048] Using water as a solvent, 0.5g of copper nitrate and 10g of ferric chloride were loaded onto 50g of alumina using an equal-volume impregnation method. The alumina was dried at 120°C for 3 hours and then calcined in a muffle furnace at 550°C for 3 hours for later use. Then, guar gum powder binder (the mass of the binder was 5% of the mass of the calcined product) was added and dispersed with an appropriate amount of water. The mixture was extruded into strips, dried at 120°C for 3 hours, and then calcined again in a muffle furnace at 550°C for 3 hours to obtain the final catalyst, denoted as catalyst L.

[0049] Examples 13-24

[0050] The synthesis of 4-methylcatechol from p-cresol was carried out in a fixed bed reactor using the catalysts described in Examples 1-12. The reaction conditions were as follows: 80 g of catalyst was loaded onto the fixed bed; the reactants were mixed in a mass ratio of p-cresol:methanol:30% hydrogen peroxide = 1:1:5 to obtain a reaction solution, which was then introduced into the fixed bed and reacted under the action of the catalyst at a temperature of 50°C and a pressure of atmospheric pressure. The mass hourly space velocity (HHSV) of the reaction solution was 0.2 h⁻¹. -1 The reaction results are shown in Tables 1 and 2:

[0051] Table 1

[0052]

[0053] Table 2

[0054]

[0055] As can be seen from the experimental results in Table 1-2, the selection of the metal salt active component and the catalyst support has a significant impact on the catalytic activity of the catalyst.

Claims

1. Use of a catalyst in the catalytic synthesis of 4-methylcatechol from p-cresol, characterized in that The catalyst preparation method includes the following steps: dissolving the active component in water, impregnating it onto the support using an equal-volume impregnation method, drying it after thorough impregnation, calcining it in a muffle furnace at 450-600℃ for 1-4 hours, extruding the calcined product with a binder into strips, drying it, and calcining it again in a muffle furnace at 450-600℃ for 1-4 hours to obtain the catalyst. The active component is one of the following: 1) Iron salts and vanadium salts, with a mass ratio of 1:0.5-2, and their total mass being 40-70% of the carrier mass; 2) The mass ratio of the main metal salt and the doped metal salt is 7.5-50:1, and the total mass of the two is 20-42% of the carrier mass; When the main metal salt is an iron salt and the doped metal salt is a cobalt salt or a copper salt, the mass ratio of the main metal salt to the doped metal salt is 20-40:

1. When the main metal salt is an iron salt and the doped metal salt is a nickel salt, the mass ratio of the main metal salt to the doped metal salt is 7.5-10:1, and the total mass of the two is 30-35% of the carrier mass. When the main metal salt is vanadium salt and the doped metal salt is palladium salt, the mass ratio of the main metal salt to the doped metal salt is 45-50:1, and the total mass of the two is 20-25% of the carrier mass. The carrier is TS-1 molecular sieve, MCM-41 molecular sieve or ZSM-5 molecular sieve.

2. Use according to claim 1, wherein The iron salt, cobalt salt, nickel salt, and copper salt are respectively nitrate, sulfate, chloride, or acetate; the vanadium salt is sodium vanadate or sodium pyrovanadate, and the palladium salt is palladium acetate.

3. The use according to claim 1, wherein The p-cresol, alcohol solvent and hydrogen peroxide are mixed to obtain a reaction solution, and the reaction solution is subjected to catalytic reaction in a fixed bed filled with a catalyst to generate 4-methylcatechol, wherein the temperature of the catalytic reaction is 40-60℃, the pressure is normal pressure, the mass space velocity of the reaction solution is 0.1-1h -1 .

4. The use according to claim 3, wherein The alcohol solvent is methanol or ethanol, and the mass ratio of p-cresol to the alcohol solvent is 1:0.5-2; the mass ratio of p-cresol to the H2O2 component in hydrogen peroxide is 1:0.5-3.

5. The use according to claim 4, wherein The alcohol solvent is methanol or ethanol, and the mass ratio of p-cresol to the alcohol solvent is 1:1; the mass ratio of p-cresol to the H2O2 component in hydrogen peroxide is 1:1-1.5.

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