Preparation method of catalyst for preparing m-cresol from toluene and preparation method of m-cresol

Abstract

The present invention provides a method for preparing a catalyst for preparing meta-cresol from toluene and a method for preparing meta-cresol, comprising the following steps: S1: preparing TS-2 titanium silicon molecular sieve; S2: placing the TS-2 titanium silicon molecular sieve in step S1 in a treatment liquid A, separating the TS-2 titanium silicon molecular sieve, and drying; S3: placing the TS-2 titanium silicon molecular sieve obtained in step S2 in a treatment liquid B, stirring to obtain a slurry, transferring the slurry to a hydrothermal kettle, and crystallizing; S4: placing the TS-2 titanium silicon molecular sieve obtained in step S3 in a treatment liquid C, filtering and separating the TS-2 titanium silicon molecular sieve and cleaning to neutrality, drying and calcining to obtain a catalyst, wherein the treatment liquid A is a mixed solution of a metal salt and an oxyacid of boron. The modified titanium silicon molecular sieve catalyst provided by the present invention has the advantage of high selectivity for meta-cresol.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for preparing a catalyst for preparing m-cresol from toluene and a method for preparing m-cresol. Background Art

[0002] Cresol has three isomers, namely o-cresol, m-cresol and p-cresol. Cresol is widely used in the synthesis of flavors and fragrances. It is also an important fine chemical intermediate and plays an important role in organic synthesis.

[0003] Meta-cresol can also be called meta-cresol, meta-methylphenol, 3-methylphenol, 3-hydroxytoluene, meta-hydroxytoluene, etc. Meta-cresol can be used as an intermediate for synthetic rubber, color film, plasticizers, and flavors and fragrances. It can also be used to manufacture vitamin E, dyes, pesticides, cosmetics and other products.

[0004] The three isomers of cresol are usually produced together in the same process. Early cresols were mostly obtained by fractionation from coal tar and waste liquid from washing petroleum fractions in refineries. Now the production methods of cresol include sulfonation alkali fusion method, chlorination hydrolysis method, phenol alkylation method, isopropyl toluene oxidation method and other methods.

[0005] Among them, the phenol alkylation method is a method for preparing cresol using metal oxides as catalysts and phenol and methanol as raw materials, including gas phase method and liquid phase method.

[0006] In the liquid-phase process, the reaction is carried out at a temperature of 300-400°C and a pressure of 1-3 MPa, using aluminum oxide as a catalyst. The resulting product has a selectivity of approximately 43%-51% for o-cresol, 17%-36% for m-cresol, and 17%-36% for p-cresol. Disadvantages of this method include the catalyst's tendency to deactivate due to carbonization, the need for high temperature and pressure, and the production of certain byproducts that affect product quality, such as anisole, which reacts at the hydroxyl group rather than the phenyl ring, where the methyl group reacts.

[0007] The vapor-phase method offers numerous improvements over the liquid-phase method and has become a key method for producing o-cresol worldwide. This method involves vaporizing phenol and methanol and then passing them at a constant flow rate through a fixed-bed reactor containing a catalyst. Common catalysts include Al₂O₃, Fe₂O₃, and MgO. The final product is primarily o-cresol and the byproduct 2,6-dimethylphenol. This method offers a relatively simple process with few reaction steps and high selectivity, making it suitable for large-scale production. The byproduct, 2,6-dimethylphenol, also has numerous industrial applications.

[0008] This method has cost and environmental advantages and is widely used in the production of o-cresol and p-cresol. However, this process is not widely used in major domestic p-cresol production enterprises, but is more widely used in m-cresol production enterprises.

[0009] The sulfonation alkaline fusion method is an early industrial method for preparing cresols, primarily used to produce p-methylphenol. It uses abundant toluene as a raw material, which reacts with concentrated sulfuric acid to produce toluene sulfonate. This is then alkali-fused to produce sodium phenolate, which is then acidified to produce methylphenol.

[0010] In addition to concentrated H2SO4, chlorosulfonic acid and SO3 can also be used as sulfonating agents. Concentrated sulfuric acid is widely used in China due to its low price. However, since concentrated H2SO4 generates water in addition to toluenesulfonic acid when used as a sulfonating agent, the resulting toluenesulfonic acid tends to contain water of crystallization and has a high melting point (104°C). Therefore, alkali fusion requires the use of a 40% sodium hydroxide solution for dissolution. This additional step increases reaction energy consumption and is now being phased out.

[0011] As an early chemical synthesis method for cresol, the sulfonation alkaline fusion method played a key role in meeting market demand for cresol due to its readily available raw materials, simple reaction equipment, mature technology, high yield, and scalable production. However, this process, which uses large amounts of strong acids and bases, poses significant equipment corrosion risks and is environmentally unfriendly, and is now being phased out.

[0012] The toluene chlorination hydrolysis method refers to a method in which toluene is used as a raw material, first reacted with chlorine gas to allow chlorine to replace hydrogen on the benzene ring to generate chlorotoluene, and then the chlorotoluene is reacted with sodium hydroxide solution in the presence of a catalyst under high temperature and high pressure environment to generate sodium methylphenolate, which is then acidified to generate methylphenol.

[0013] The chlorination reaction involves passing Cl2 through a reactor containing toluene in the presence of a Cu-Fe catalyst at 230°C. This reaction produces a mixture of o-, m-, and p-chlorotoluene. Hydrolysis is then carried out at 425°C using silica as a catalyst to produce a mixture of sodium methylphenolates. This mixture is then neutralized with an acid to produce a cresol mixture. The acid required for neutralization can be hydrogen chloride, a byproduct of the chlorination process. The resulting cresol mixture exhibits a selectivity ratio of approximately 1:2:1 for o-, m-, and p-cresol.

[0014] This method has relatively low requirements for equipment, but it has many reaction steps and produces many by-products, especially dimethylhydroxybiphenyl and dimethyl diether, which are easily hydrolyzed, making it difficult for the product quality to meet the standards. Therefore, this method still needs further improvement.

[0015] The cymene oxidation process produces meta-cresol and p-cresol as its main products, along with acetone as a byproduct. The selectivity ratio of meta-cresol to p-cresol is approximately 7:3, making it the predominant method for industrially producing meta-cresol. This process involves an alkylation reaction of toluene with propylene over the catalyst AlCl3 to produce cymene. The cymene is then oxidized to produce a peroxide of cymene, which is then reacted with dilute sulfuric acid for acidolysis to produce the corresponding cresols and acetone as a byproduct. While this process yields relatively high product purity, it is technically challenging, requires a long process route, and requires significant product separation effort. Furthermore, for every molecule of cresol produced, one molecule of acetone is also produced, resulting in poor atom economy.

[0016] Researchers have been diligently pursuing the direct oxidation of toluene to produce cresols. Due to the readily available and inexpensive raw material, toluene holds great industrial value. Using hydrogen peroxide as an oxidant for the hydroxylation of toluene is a preferred method. Compared to these traditional processes, the one-step direct hydroxylation of toluene and hydrogen peroxide to produce cresols offers significant advantages, including lower cost, simpler production, higher molecular weight, and reduced waste generation and emissions.

[0017] Generally, the preparation of cresol produces three isomers: o-cresol, m-cresol and p-cresol. Among them, the boiling point difference between m-cresol and p-cresol is very small, only 0.8°C, which makes separation and purification difficult, greatly increasing the production cost of m-cresol and p-cresol. Therefore, the problem of separation and purification of m-cresol needs to be solved urgently. Summary of the Invention

[0018] In view of this, the present invention aims to provide a preparation method of a catalyst for catalytic oxidation of toluene to produce m-cresol, so as to solve the problems of difficulty in separation and purification of m-cresol and high production cost.

[0019] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0020] A method for preparing a catalyst for preparing m-cresol from toluene comprises the following steps:

[0021] S1: Preparation of TS-2 titanium silicalite molecular sieve;

[0022] S2: placing the TS-2 titanium silicate molecular sieve in step S1 into the treatment solution A, separating the TS-2 titanium silicate molecular sieve, and drying;

[0023] S3: placing the TS-2 titanium silicalite obtained in step S2 into treatment solution B, stirring to obtain a slurry, and transferring the slurry to a hydrothermal reactor for crystallization;

[0024] S4: placing the TS-2 titanium silicalite obtained in step S3 into the treatment solution C, filtering and separating the TS-2 titanium silicalite, washing it to neutrality, drying it, and calcining it to obtain a catalyst;

[0025] The treatment solution A is a mixed solution of a metal salt and an oxygen-containing acid of boron.

[0026] Furthermore, the cation of the metal salt of the treatment solution A in step S2 is one of iron ion, cobalt ion, nickel ion, copper ion, manganese ion, calcium ion, magnesium ion, and ammonium ion; and the anion of the metal salt is one or more of acetate, citrate, tungstate, and molybdate;

[0027] The mass ratio of the metal salt to the boron oxygen acid is 1:(0.5-2);

[0028] Preferably, the immersion temperature of TS-2 titanium silicate molecular sieve is 80-200°C and the immersion time is 12-20h;

[0029] Preferably, the boron oxygen acid comprises one or more of orthoboric acid, pyroboric acid, metaboric acid or tetraboric acid.

[0030] Further, the treatment liquid B in step S3 includes a tetrabutylammonium hydroxide solution;

[0031] The mass ratio of tetrabutylammonium hydroxide to catalyst is 1:(2-10);

[0032] Preferably, the treatment temperature in the hydrothermal reactor in step S3 is 80-200° C., and the crystallization reaction time is 20-80 h.

[0033] Furthermore, the treatment liquid C in step S4 is an organic acid solution, wherein the organic acid solution is one or more of acetic acid, propionic acid, acrylic acid, citric acid, oxalic acid, and benzoic acid, and the acid concentration is 1 to 5%;

[0034] Preferably, the drying temperature in step T2 is 80-150° C., the drying time is 12-24 hours, the calcination temperature is 450-600° C., and the calcination time is 4-24 hours.

[0035] Furthermore, the preparation method of TS-2 titanium silicalite in step S1 comprises the following steps:

[0036] T1: Stir tetrabutylammonium hydroxide until dissolved, add silicon source and titanium source into water respectively, and stir until a uniform gel is formed;

[0037] T2: The gum solution in step T1 is stirred for hydrolysis and dealcoholization, and the gum solution is transferred to a hydrothermal kettle for crystallization, washed to neutrality, dried and calcined.

[0038] Furthermore, the silicon source in step T1 includes one or more of fumed silicon oxide, ethyl orthosilicate, and silica sol;

[0039] The titanium source includes one or more of isobutyl titanate, titanium oxide powder, and titanium tetrachloride;

[0040] The molar ratio of tetrabutylammonium hydroxide, silicon source and titanium source is 1::(0.2-2):(0.01-0.1).

[0041] Furthermore, in step T2, the stirring temperature of the glue solution is 50-90° C., and the stirring time is 60-200 min;

[0042] The crystallization temperature in the hydrothermal reactor is 80-200° C., and the crystallization reaction time is 10-120 hours.

[0043] Furthermore, in step T2, the drying temperature is 120° C., the drying time is 12 h, the calcination temperature is 550° C., and the calcination time is 4 h.

[0044] The preparation method of m-cresol comprises the following steps:

[0045] C1: Place the catalyst in a reactor, then add toluene and solvent into the reactor and stir until a uniform slurry is formed;

[0046] C2: heating the slurry obtained in step C1, adding hydrogen peroxide to the slurry for reaction, and keeping the temperature to obtain the m-cresol product.

[0047] In the preferred technical solution of the above-mentioned method for preparing m-cresol, the solvent in step C1 includes one or more of methanol, ethanol, isopropanol, tert-butanol, formic acid, acetic acid, acetonitrile, and 1,2-dichloroethane;

[0048] Preferably, the mass ratio of toluene, catalyst, and solvent is 1:(0.5-2):(0.2-4);

[0049] Preferably, the concentration of hydrogen peroxide in hydrogen peroxide is 10 to 50%;

[0050] Preferably, the molar ratio of toluene to hydrogen peroxide in hydrogen peroxide is 1:(0.15-1.1), preferably 1:(0.15-1.0).

[0051] Preferably, the slurry heating temperature in step C2 is 50-90° C., and the reaction time is 5-60 minutes. The metal salt and the boron oxyacid are prepared into a solution to treat the TS-2 molecular sieve. After calcination, the metal oxide and boron oxide can be loaded into the pores of the molecular sieve. The metal oxide and boron oxide are loaded together in the pores of the TS-2 molecular sieve, which can optimize the pore size of the molecular sieve, provide a good shape selectivity effect for the reaction, and optimize the electronic structure of the molecular sieve, thereby improving the selectivity for m-cresol.

[0052] Using tetrabutylammonium hydroxide aqueous solution as treatment liquid B can optimize the pore structure of the TS-2 molecular sieve matrix, ensure the uniformity of the pore shape and size of the TS-2 molecular sieve matrix, suitable pore size and suitable metal oxide and boride filling, can ensure that the pores of the TS-2 molecular sieve can provide a good shape-selective environment, ensure the selectivity of generating meta-cresol. When using metal salts for filling, a small amount of metal oxide particles will be produced and will be free outside the catalyst matrix. These metal oxide particles are not only difficult to form coupling with the TS-2 molecular sieve, but also will catalyze the decomposition of hydrogen peroxide, causing waste of raw materials. Therefore, we use organic acid treatment as treatment liquid C to treat the catalyst, while not destroying the metal oxide in the dispersed state, the free metal oxide particles are dissolved to prevent side reactions from occurring.

[0053] Compared with the prior art, the preparation method of the catalyst for catalytic oxidation of toluene to produce m-cresol according to the present invention has the following advantages:

[0054] 1. The modified titanium silicate molecular sieve catalyst provided by the present invention has the advantage of high selectivity for m-cresol.

[0055] 2. The present invention uses toluene as a raw material and hydrogen peroxide as an oxidant, with mild reaction conditions, low by-products and little pollution. DETAILED DESCRIPTION

[0056] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0057] The present invention will be described in detail below with reference to the embodiments.

[0058] Example 1

[0059] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 400g of ethyl orthosilicate to the solution and stir until uniform. Then add 18g of titanium oxide powder to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 80°C for 120 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 180°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0060] 12 g of ammonium molybdate and 10 g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12 h, the treated molecular sieve was taken out and dried at 120° C. for 12 h.

[0061] 100 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 250 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 180° C. for 60 h.

[0062] Prepare a 3% acetic acid solution as treatment solution C, heat it to 60°C, and treat the TS-2 catalyst in this solution for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0063] Dissolve 100g of toluene in 150g of methanol, then add 200g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0064] The product solution was analyzed and found to have a toluene conversion rate of 41.78% and a cresol selectivity of 93.76%, of which the m-cresol selectivity was 90.72%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 99.15%.

[0065] Example 2

[0066] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 350g of 30% silica sol to the solution and stir until uniform. Then add 40g of isobutyl titanate to the solution and stir until a uniform gel solution is formed. Stir the gel solution at 90°C for 200min to allow the gel solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the gel solution to a hydrothermal kettle and crystallize at 180°C for 48h to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12h, and then calcined in a muffle furnace at 550°C for 4h.

[0067] 10 g of manganese citrate and 10 g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12 h, the treated molecular sieve was taken out and dried at 120° C. for 12 h.

[0068] 50 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 200 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 200° C. for 40 h.

[0069] Prepare a 3% acrylic acid solution as treatment solution C, heat treatment solution C to 60°C, and treat the TS-2 catalyst in treatment solution C for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0070] Dissolve 100g of toluene in 200g of acetonitrile, then add 150g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 60°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0071] The product solution was analyzed and found to have a toluene conversion rate of 40.12% and a cresol selectivity of 91.85%, of which the m-cresol selectivity was 89.12%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 99.31%.

[0072] Example 3

[0073] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 120g of fumed silica to the solution and stir until uniform. Then add 40g of isobutyl titanate to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 90°C for 200min to allow the glue solution to be fully hydrolyzed and dealcoholized. The generated alcohols are completely volatilized. Then add the glue solution to a hydrothermal kettle and crystallize at 180°C for 48h to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12h, and then calcined in a muffle furnace at 550°C for 4h.

[0074] 25 g of magnesium acetate and 20 g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12 h, the treated molecular sieve was taken out and dried at 120° C. for 12 h.

[0075] 100 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 200 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 180° C. for 72 h.

[0076] Prepare a 3% acetic acid solution as treatment solution C, heat it to 60°C, and treat the TS-2 catalyst in this solution for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0077] Dissolve 100g of toluene in 200g of acetic acid, then add 150g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 15g of 50% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0078] The product solution was analyzed and found to have a toluene conversion rate of 18.78% and a cresol selectivity of 93.65%, of which the m-cresol selectivity was 91.76%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 99.08%.

[0079] Example 4

[0080] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 120g of fumed silica to the solution and stir until uniform. Then add 20g of titanium chloride to the solution and stir until a uniform gel is formed. Stir the gel at 70°C for 30 minutes to allow the gel to fully hydrolyze and dealcoholize, and the generated alcohols to completely evaporate. Then add the gel to a hydrothermal kettle and crystallize at 160°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0081] 20g of ammonium tungstate and 10g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12h, the treated molecular sieve was taken out and dried at 120℃ for 12h.

[0082] 100 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 150 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 160° C. for 48 h.

[0083] Prepare a 1% benzoic acid solution as treatment solution C, heat it to 60°C, and treat the TS-2 catalyst in this solution for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0084] Dissolve 100g of toluene in 200g of tert-butyl alcohol, then add 150g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 30g of 50% hydrogen peroxide to the slurry and continue the reaction for 60 minutes.

[0085] The product solution was analyzed and found to have a toluene conversion rate of 28.52% and a cresol selectivity of 96.52%, of which the m-cresol selectivity was 92.51%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 99.33%.

[0086] Example 5

[0087] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 380g of ethyl orthosilicate to the solution and stir until uniform. Then add 20g of titanium chloride to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 70°C for 30 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 200°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0088] 20 g of cobalt citrate and 28 g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12 h, the treated molecular sieve was taken out and dried at 120° C. for 12 h.

[0089] 100 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 200 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 200° C. for 72 h.

[0090] Prepare a 3% oxalic acid solution as treatment solution C, heat it to 30°C, and treat the TS-2 catalyst in this solution for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0091] Dissolve 100g of toluene in 200g of tert-butyl alcohol, then add 150g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 74g of 50% hydrogen peroxide to the slurry and continue the reaction for 60 minutes.

[0092] The product solution was analyzed and found to have a toluene conversion rate of 68.72% and a cresol selectivity of 88.52%, of which the m-cresol selectivity was 84.95%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 99.07%.

[0093] It can be seen from Examples 1 to 5 that m间甲酚 / (m 对甲酚 +m 间甲酚 ) can reach 99% and above.

[0094] Comparative Example 1

[0095] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 400g of ethyl orthosilicate to the solution and stir until uniform. Then add 18g of titanium oxide powder to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 80°C for 120 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 180°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0096] Dissolve 100g of toluene in 150g of methanol, then add 200g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0097] The product solution was analyzed and found to have a toluene conversion rate of 46.61% and a cresol selectivity of 62.62%, of which the m-cresol selectivity was 50.72%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 80.87%.

[0098] Comparative Example 2

[0099] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 400g of ethyl orthosilicate to the solution and stir until uniform. Then add 18g of titanium oxide powder to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 80°C for 120 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 180°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0100] 10 g of orthoboric acid was added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in the treatment solution A. After stirring for 12 hours, the treated molecular sieve was taken out and dried at 120° C. for 12 hours.

[0101] Dissolve 100g of toluene in 150g of methanol, then add 200g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0102] The product solution was analyzed and found to have a toluene conversion rate of 44.85% and a cresol selectivity of 84.98%, of which the m-cresol selectivity was 52.73%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 76.90%.

[0103] Comparative Example 3

[0104] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 400g of ethyl orthosilicate to the solution and stir until uniform. Then add 18g of titanium oxide powder to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 80°C for 120 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 180°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0105] 12 g of ammonium molybdate and 10 g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12 h, the treated molecular sieve was taken out and dried at 120° C. for 12 h.

[0106] 100 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 250 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 180° C. for 60 h.

[0107] Dissolve 100g of toluene in 150g of methanol, then add 200g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0108] The product solution was analyzed and found to have a toluene conversion rate of 32.84% and a cresol selectivity of 96.22%, of which the m-cresol selectivity was 91.73%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 97.87%.

[0109] Comparative Example 4

[0110] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 400g of ethyl orthosilicate to the solution and stir until uniform. Then add 18g of titanium oxide powder to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 80°C for 120 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 180°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0111] 12 g of ammonium molybdate and 10 g of orthoboric acid were added to water to prepare treatment solution A. The obtained TS-2 molecular sieve was immersed in treatment solution A. After stirring for 12 h, the treated molecular sieve was taken out and dried at 120° C. for 12 h.

[0112] Prepare a 3% acetic acid solution as treatment solution C, heat it to 60°C, and treat the TS-2 catalyst in this solution for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0113] Dissolve 100g of toluene in 150g of methanol, then add 200g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0114] The product solution was analyzed and found to have a toluene conversion rate of 41.01% and a cresol selectivity of 93.79%, of which the m-cresol selectivity was 88.84%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 95.62%.

[0115] Comparative Example 5

[0116] Add 250g of tetrabutylammonium hydroxide to water and stir until dissolved. Then add 400g of ethyl orthosilicate to the solution and stir until uniform. Then add 18g of titanium oxide powder to the solution and stir until a uniform glue solution is formed. Stir the glue solution at 80°C for 120 minutes to allow the glue solution to be fully hydrolyzed and dealcoholized, and the generated alcohols to completely evaporate. Then add the glue solution to a hydrothermal kettle and crystallize it at 180°C for 72 hours to obtain TS-2 molecular sieve. The obtained molecular sieve is washed until neutral, then dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours.

[0117] 100 g of tetrabutylammonium hydroxide was dissolved in water to prepare treatment solution B, and 250 g of TS-2 molecular sieve was added to the treatment solution B and stirred until uniform. The slurry was added to a hydrothermal kettle and crystallized at 180° C. for 60 h.

[0118] Prepare a 3% acetic acid solution as treatment solution C, heat it to 60°C, and treat the TS-2 catalyst in this solution for 60 minutes. Wash the treated molecular sieve until neutral, dry it at 120°C for 12 hours, and then calcine it in a muffle furnace at 550°C for 4 hours. This yields the modified TS-2 molecular sieve catalyst.

[0119] Dissolve 100g of toluene in 150g of methanol, then add 200g of modified TS-2 molecular sieve catalyst to the solution and stir until a uniform slurry forms. Heat the slurry to 80°C, then gradually add 61g of 30% hydrogen peroxide to the slurry and continue the reaction for 30 minutes.

[0120] The product solution was analyzed and found to have a toluene conversion rate of 45.15% and a cresol selectivity of 84.25%, of which the m-cresol selectivity was 41.90%, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) is 61.6%.

[0121] Comparative Example 1 Compared with Example 1, Comparative Example 1 was not treated with treatment liquid A, treatment liquid B, or treatment liquid C. It can be seen that the selectivity of cresol and m-cresol decreased significantly, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) value decreased.

[0122] Comparative Example 2 Compared with Example 1, Comparative Example 2 was not treated with treatment solution B or treatment solution C. It can be seen that the selectivity of cresol decreased, m 间甲酚 / (m 对甲酚 +m 间甲酚 ) value decreased.

[0123] Comparative Example 3 is compared with Example 1. Comparative Example 3 is not treated with treatment liquid C. It can be seen that m 间甲酚 / (m 对甲酚 +m 间甲酚 ) value decreased.

[0124] Comparative Example 4 is compared with Example 1. In Comparative Example 4, no treatment liquid B is used between treatment liquid A and treatment liquid C. It can be seen that the selectivity of m-cresol in Comparative Example 4 decreases. 间甲酚 / (m 对甲酚 +m 间甲酚 ) value decreased.

[0125] Comparative Example 5 Compared with Example 1, Comparative Example 5 was not treated with treatment solution A. It can be seen that the selectivity of cresol and m-cresol were greatly reduced. 间甲酚 / (m 对甲酚 +m 间甲酚 )decline.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for preparing m-cresol from toluene, characterized in that: The steps include: S1: Preparation of TS-2 titanium silicalite molecular sieve; S2: placing the TS-2 titanium silicate molecular sieve in step S1 into the treatment solution A, separating the TS-2 titanium silicate molecular sieve, and drying; S3: placing the TS-2 titanium silicalite obtained in step S2 into treatment solution B, stirring to obtain a slurry, and transferring the slurry to a hydrothermal reactor for crystallization; S4: placing the TS-2 titanium silicalite obtained in step S3 into the treatment solution C, filtering and separating the TS-2 titanium silicalite, washing it to neutrality, drying it, and calcining it to obtain a catalyst; The treatment liquid A is a mixed solution of a metal salt and an oxygen-containing acid of boron, and the treatment liquid C in step S4 is an organic acid solution; The cation of the metal salt of the treatment solution A in step S2 is one or more of iron ion, cobalt ion, nickel ion, copper ion, manganese ion, calcium ion, magnesium ion, and ammonium ion, and the anion of the metal salt is one or more of acetate, citrate, tungstate, and molybdate; The mass ratio of the metal salt to the boron oxygen acid is 1:(0.5-2); The treatment liquid B in step S3 includes a tetrabutylammonium hydroxide solution; The mass ratio of tetrabutylammonium hydroxide to TS-2 titanium silicalite molecular sieve is 1:(2-10); The treatment temperature in the hydrothermal reactor in step S3 is 80-200° C., and the crystallization reaction time is 20-80 hours.

2. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 1, wherein: The temperature of the TS-2 titanium silicate molecular sieve soaking treatment solution A is room temperature, and the soaking time is 12-20 hours.

3. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 1, wherein: The oxyacid of boron includes one or more of orthoboric acid, pyroboric acid, metaboric acid or tetraboric acid.

4. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 1, wherein: The organic acid solution is one or more of acetic acid, propionic acid, acrylic acid, citric acid, oxalic acid, and benzoic acid, and the concentration of the acid solution is 1-5%.

5. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 1, wherein: The drying temperature in step S4 is 20-80° C., and the drying time is 10-200 min.

6. The method for preparing a catalyst for preparing m-cresol from toluene according to any one of claims 1 to 5, characterized in that: The preparation method of TS-2 titanium silicalite molecular sieve in step S1 comprises the following steps: T1: Add tetrabutylammonium hydroxide, silicon source, and titanium source to the solution respectively and stir until a uniform gel is formed; T2: The gum solution in step T1 is stirred for hydrolysis and dealcoholization, and the gum solution is transferred to a hydrothermal kettle for crystallization, washed to neutrality, dried and calcined.

7. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 6, wherein: The silicon source in step T1 includes one or more of fumed silicon oxide, ethyl orthosilicate, and silica sol; The titanium source includes one or more of isobutyl titanate, titanium oxide powder, and titanium tetrachloride; The molar ratio of tetrabutylammonium hydroxide, silicon source and titanium source is 1:(0.2-2):(0.01-0.1).

8. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 6, wherein: In step T2, the stirring temperature of the glue solution is 50-90°C, and the stirring time is 60-200 minutes; The crystallization temperature in the hydrothermal reactor is 80-200° C., and the crystallization reaction time is 10-120 hours.

9. The method for preparing a catalyst for preparing m-cresol from toluene according to claim 6, wherein: In step T2, the drying temperature is 80-150° C., the drying time is 12-24 hours, the calcination temperature is 450-600° C., and the calcination time is 4-24 hours.

10. A method for preparing m-cresol, characterized in that: The preparation method of m-cresol comprises the following steps: C1: Add the catalyst, toluene and solvent into the reactor and stir until a uniform slurry is formed; C2: heating the slurry obtained in step C1, adding hydrogen peroxide to the slurry for reaction, and keeping the temperature to obtain the m-cresol product; Wherein, the catalyst is prepared by the preparation method of the catalyst for producing m-cresol from toluene according to any one of claims 1 to 9.

11. The method for preparing m-cresol according to claim 10, wherein: The solvent in step C1 includes one or more of methanol, ethanol, isopropanol, tert-butanol, formic acid, acetic acid, acetonitrile, and 1,2-dichloroethane.

12. The method for preparing m-cresol according to claim 11, wherein: The mass ratio of toluene, catalyst and solvent is 1:(0.5-2):(0.2-4).

13. The method for preparing m-cresol according to claim 11, wherein: The concentration of hydrogen peroxide is 10-50%.

14. The method for preparing m-cresol according to claim 11, wherein: The molar ratio of toluene to hydrogen peroxide in hydrogen peroxide is 1:(0.15~1.1).

15. The method for preparing m-cresol according to claim 11, wherein: In step C2, the slurry heating temperature is 50-90° C., and the reaction time is 5-60 min.