Preparation method of a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol

Abstract

The present invention belongs to the technical field of catalyst synthesis, and in particular to a method for preparing a catalyst for catalyzing meta-cresol to synthesize 2,3,6-tricresol. The preparation method comprises the following steps: iron salt and a modifier are mixed in dimethyl sulfoxide to form a mixed solution, activated carbon is added to the mixed solution to be mixed and placed in an environment of 40 to 50 ° C, and an iron-based catalyst is obtained by 60 to 80W ultrasonic power treatment for 25 to 45min, and the iron-based catalyst is dried and treated at 100 to 120 ° C for 8 to 12h to obtain a catalyst for synthesizing 2,3,6-tricresol from meta-cresol. The present invention fixes the metal active center in the form of an ionic bond of electrostatic bonding, avoids the agglomeration and loss of the metal active center, and then increases the specific surface area of ​​the metal active center by ultrasonic treatment, accompanied by the cavitation of ultrasonic treatment, the skeleton structure of the carrier and the microchannel can be fully contacted with the mixed liquid liquid with the metal active center, and the loading amount of the active component is increased, and the catalytic efficiency is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst synthesis, and particularly relates to a method for preparing a catalyst for catalyzing meta-cresol to synthesize 2,3,6-trimethylphenol. Background Art

[0002] 2,3,6-Trimethylol is an important organic chemical raw material intermediate. It can not only be used as the main ring structure for synthesizing vitamin E, but also as the raw material for producing monomers and plastic alloys for heat-resistant polyphenylene ether engineering plastics. At present, there are many process synthesis routes for 2,3,6-trimethylol, which are mainly divided into phenol method, hexanoic acid (4-methyl-3-carbonyl)-6-hexyl ester method, dimethylamino-vinyl methyl ketone method, diethyl ketone method, β-methyl acrolein method and meta-cresol method. Among these many process routes, the production methods with the highest research heat are mainly phenol method and meta-cresol method. The phenol method directly uses phenol and methanol for methylation to synthesize 2,3,6-trimethylol. Although the raw materials are easy to obtain, the exothermic process of the reaction is violent, and a two-stage reactor is required, which has certain difficulties in separating the products and is costly. Meta-cresol production has always been favored by scientific researchers because of its simple process, low pollution, few side reactions and high yield. The core of this process lies in the preparation of catalysts. The catalyst studied earlier was mainly activated aluminum, but this catalyst had low reaction selectivity and many side reactions. Later, it was modified to obtain a magnesium oxide-based catalyst. However, the reaction temperature of the magnesium oxide-based catalyst is as high as five hundred to six hundred degrees Celsius, which consumes a lot of energy. In addition, the catalyst has a short service life at high temperatures and is prone to carbonization and clogging the catalyst, causing a significant decrease in the catalytic effect. Patent CN102974354B discloses a method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol. In this method, iron ions, aluminum ions and alkali metal ions are precipitated by adding a precipitant, and then calcined at high temperature to form a solid oxide to catalyze the methylation of m-cresol to 2,3,6-trimethylphenol; Patent CN101844968B discloses a method for preparing 2,3,6-trimethylphenol from 2,5-xylenol. In this method, 2,5-xylenol and methanol are reacted in a fixed bed reactor in a gas phase catalytic manner using an iron oxide-based catalyst to synthesize 2,3,6-trimethylphenol; Patent 108409541B discloses a method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol. In this method, iron oxide, copper oxide and silicon dioxide are co-precipitated by treating with ammonia water to prepare the catalyst.

[0003] The above-mentioned catalysts for catalytic synthesis of 2,3,6-trimethylphenol have promoted the catalytic synthesis efficiency to a certain extent. However, due to the single use of metal active components as catalytic centers, there is agglomeration and loss of active components, resulting in the need to increase the amount of catalyst used to achieve the expected catalytic efficiency, which increases the cost. Therefore, it is of great significance to design a catalyst that can fix and disperse the active components on a specific carrier to achieve the separation of the active components and avoid the reduction of catalytic efficiency due to agglomeration between the active components. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention mixes the active component with the modifier, and the metal ions in the active component and the anions in the modifier form ionic bonds through electrostatic bonding, and then the treated active component is introduced into the surface of the carrier with a large specific surface area through ultrasonic assisted impregnation. The cavitation bubbles generated by the ultrasonic action will produce high temperature and high pressure physical and chemical effects locally during the generation and rupture process, so that the particle size of the active component is reduced, thereby increasing the specific surface area of ​​the active component. Along with the cavitation action, the skeleton structure and microchannels of the carrier can be fully contacted with the impregnation liquid with the active component, increasing the loading amount of the active component, thereby avoiding the agglomeration and loss of the active component, and increasing the catalytic efficiency, so as to solve the problems raised in the background technology. Specifically, the technical scheme of the present invention includes the following contents:

[0005] A method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol, the method comprising the following steps:

[0006] The iron salt and the modifier are mixed in dimethyl sulfoxide to form a mixed solution, activated carbon is added to the mixed solution for mixing, and then placed in an environment of 40 to 50° C., and subjected to an ultrasonic power treatment of 60 to 80 W for 25 to 45 minutes to obtain an iron-based catalyst, and the iron-based catalyst is dried at 100 to 120° C. for 8 to 12 hours to obtain a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol.

[0007] Furthermore, the iron salt includes any one or more of ferric chloride hexahydrate, ferric nitrate nonahydrate and ferric sulfate hydrate.

[0008] Furthermore, the preparation method of the modifier comprises the following steps:

[0009] The metal ion salt solution and the chloride ion salt are mixed in a polar organic solvent, reacted in a water bath, and then vacuum dried to obtain the modifier.

[0010] Furthermore, the metal ion salt solution includes aluminum chloride or copper chloride, and the anions in the metal ion salt solution should be consistent with the chloride ions in the chloride ion-containing salt, so that the chloride ions in the chloride ion-containing salt are complexed with the metal ions to form metal-containing complex anion components, which are convenient for subsequent combination with the cations in the iron salt through electrostatic action to form ionic bonds, thereby inhibiting the agglomeration and loss of active metal components.

[0011] Furthermore, the chloride ion-containing salt includes 2-(trichloroacetyl)pyrrole, 4-chloropiperidine or 1-piperidinyl chloride.

[0012] Furthermore, the polar solvent includes methanol, ethanol or tetrahydrofuran.

[0013] Furthermore, the conditions of the water bath reaction include reacting at 70-80° C. for 3-4 hours.

[0014] Furthermore, the molar ratio of the metal ion salt solution to the chloride ion salt is 1 to 3:1.

[0015] Furthermore, the mass ratio of the iron salt to the modifier is 1:2-4.

[0016] Compared with the prior art, the beneficial effects of the present invention include the following points:

[0017] The present invention fixes the metal active center of the catalyst and the modifier in the form of an electrostatically bonded ionic bond, thereby avoiding the agglomeration and loss of the metal active center caused by the single application of the metal active center as the catalytic center, and then fixes the modified catalyst on the surface of the activated carbon through ultrasonic treatment, and utilizes the cavitation bubbles generated by the cavitation effect in the ultrasound to generate high temperature and high pressure physical and chemical effects in the process of generation and rupture, so that the particle size of the metal active center is reduced, thereby increasing the specific surface area of ​​the metal active center. Accompanied by the cavitation effect, the skeleton structure and microchannel of the carrier can fully contact with the mixed liquid with the metal active center, thereby increasing the loading amount of the active component and further improving the catalytic efficiency. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0020] Carrier: Activated carbon and sodium carbonate were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0021] Iron salts: ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric sulfate hydrate, and ferrous sulfate heptahydrate were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0022] Solvents: Deionized water, dimethyl sulfoxide, methanol, ethanol, and tetrahydrofuran were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0023] Metal ion salt solutions: aluminum chloride, copper chloride and ferric chloride were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0024] Chloride ion-containing salts: 2-(trichloroacetyl)pyrrole, 4-chloropiperidine and 1-piperidinyl chloride were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0025] Ammonia water for adjusting pH was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] Activation treatment of activated carbon:

[0027] Use a sieve to obtain activated carbon with a mesh size of 50 to 60, rinse the activated carbon with deionized water and place it in an oven, adjust the temperature in the oven to 50°C, dry the activated carbon for 4 hours, put it in a three-necked flask, and place the three-necked flask in a water bath at 65 to 70°C, add 1 mol / L hydrochloric acid to the three-necked flask and treat the activated carbon for 2 hours, then wash the activated carbon with distilled water until it is neutral, then place the washed activated carbon in an oven, adjust the temperature to 150°C, dry it for 8 hours and set it aside.

[0028] Embodiment 1:

[0029] A method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol, the specific preparation process comprising the following steps:

[0030] (1) Preparation method of modifier:

[0031] Weigh 0.1 mol of aluminum chloride (13.3 g) and place it in a three-necked flask, add 150 ml of methanol to the three-necked flask to dissolve the aluminum chloride, weigh 0.1 mol of 2-(trichloroacetyl)pyrrole (21.2 g) and add it to the three-necked flask containing aluminum chloride and mix and stir evenly, then place the three-necked flask in a water bath, adjust the temperature of the water bath to 70°C, react at this temperature for 3 hours, and then place the obtained reaction solution in a rotary evaporator for vacuum drying to remove the methanol solvent to obtain a dry aluminum complex modifier.

[0032] (2) Preparation of catalyst:

[0033] Weigh 1.5 g of ferric chloride hexahydrate and place it in a three-necked flask, add 20 ml of deionized water and stir to dissolve until there are no obvious particles in the solution, then add 30 ml of dimethyl sulfoxide to the three-necked flask and continue to stir to dissolve, weigh 3 g of an aluminum complex modifier and add it to the three-necked flask and stir to dissolve with ferric chloride hexahydrate, weigh 6 g of activated carbon after activation treatment and add it to the three-necked flask for mixing, place the mixed solution in an ultrasonic cleaner, adjust the temperature to 40°C, control the ultrasonic power to 60 W, start ultrasonic treatment, react for 25 minutes, take out the mixed solution and dry it at 100°C for 8 hours to obtain a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol.

[0034] Embodiment 2:

[0035] A method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol, the specific preparation process comprising the following steps:

[0036] (1) Preparation method of modifier:

[0037] Weigh 0.2 mol of copper chloride (26.9 g) and place it in a three-necked flask, add 200 ml of ethanol to the three-necked flask to dissolve the aluminum chloride, weigh 0.1 mol of 4-chloropiperidine (12.0 g) and add it to the three-necked flask containing copper chloride and mix and stir evenly, adjust the temperature of the water bath to 75 ° C, react at this temperature for 4 hours, and then place the obtained reaction solution in a rotary evaporator for vacuum drying to remove the ethanol solvent to obtain a dry copper-containing complex modifier.

[0038] (2) Preparation of catalyst:

[0039] Weigh 1.5 g of ferric nitrate nonahydrate and 1.5 g of ferric sulfate hydrate and place them in a three-necked flask, add 30 ml of deionized water to stir and dissolve, then add 40 ml of dimethyl sulfoxide to the three-necked flask and continue to stir and dissolve, weigh 9 g of a copper-containing complex modifier and add it to the three-necked flask containing ferric nitrate nonahydrate and ferric sulfate hydrate, stir and dissolve, weigh 10 g of activated carbon after activation treatment and mix it with the mixed solution in the three-necked flask, place the mixed solution in an ultrasonic cleaner, adjust the temperature to 45°C, control the ultrasonic power to 70 W, start ultrasonic treatment, react for 30 minutes, take out the mixed solution and dry it at 110°C for 9 hours to obtain a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol.

[0040] Embodiment 3:

[0041] A method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol, the specific preparation process comprising the following steps:

[0042] (1) Preparation method of modifier:

[0043] Weigh 0.3 mol of ferric chloride (48.6 g) and place it in a three-necked flask, add 250 ml of tetrahydrofuran to the three-necked flask to dissolve the aluminum chloride, weigh 0.1 mol of 1-piperidinyl chloride (14.7 g) and add it to the three-necked flask containing ferric chloride and mix and stir evenly, then place the three-necked flask in a water bath, adjust the temperature of the water bath to 80°C, react at this temperature for 3.5 hours, and then place the obtained reaction solution in a rotary evaporator for vacuum drying to remove the tetrahydrofuran solvent to obtain a dry iron-containing complex modifier.

[0044] (2) Preparation of catalyst:

[0045] Weigh 1.5 g of ferrous sulfate heptahydrate and place it in a three-necked flask, add 20 ml of deionized water and stir to dissolve until there are no obvious particles in the solution, then add 30 ml of dimethyl sulfoxide to the three-necked flask and continue to stir to dissolve, weigh 6 g of iron-containing complex modifier and add it to the three-necked flask containing ferrous sulfate heptahydrate for mixed dissolution, weigh 6 g of activated carbon after activation treatment and mix it with the mixed solution in the three-necked flask, place the mixed solution in an ultrasonic cleaner, adjust the temperature to 50°C, control the ultrasonic power to 80 W, start ultrasonic treatment, react for 40 minutes, take out the mixed solution and dry it at 110°C for 11 hours to obtain a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol.

[0046] Embodiment 4:

[0047] A method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol, the specific preparation process comprising the following steps:

[0048] (1) Preparation method of modifier:

[0049] Same as Example 3(1).

[0050] (2) Preparation of catalyst:

[0051] Weigh 1.5 g of ferric chloride hexahydrate and 1.5 g of ferric sulfate hydrate and place them in a three-necked flask, add 20 ml of deionized water and stir to dissolve until there are no obvious particles in the solution, then add 30 ml of dimethyl sulfoxide to the three-necked flask and continue to stir to dissolve, weigh 3 g of iron-containing complex modifier and add it to the three-necked flask containing ferric chloride and ferric sulfate, stir to dissolve, weigh 6 g of activated carbon after activation treatment and add it to the three-necked flask containing ferric chloride and ferric sulfate to mix, place the mixed solution in an ultrasonic cleaner, adjust the temperature to 45°C, control the ultrasonic power to 75 W, start ultrasonic treatment, react for 45 minutes, take out the mixed solution and dry it at 120°C for 12 hours to obtain a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol.

[0052] Comparative Example:

[0053] A catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol using only active metal is prepared. The specific preparation process includes the following steps:

[0054] Weigh 20 g of iron nitrate nonahydrate and dissolve it in 100 ml of deionized water. Add ammonia water while stirring until the solution pH is within the range of 8 to 9, then continue stirring for 1 hour, filter out the precipitate and wash it, then dry it at 120°C for 12 hours, and then calcine it at 500°C for 5 hours to obtain a block solid. After grinding with a grinder, mix it with 1 g of sodium carbonate and heat it in 20 ml of deionized water for 5 hours, then dry it at 120°C for 12 hours and calcine it at 500 degrees Celsius for 2 hours to obtain an iron oxide catalyst.

[0055] Application Example 1:

[0056] The catalytic m-cresol is used to prepare 2,3,6-trimethylphenol, and the specific process includes the following steps:

[0057] The catalyst obtained in Example 1 was placed in a fixed bed reactor, m-cresol and methanol were mixed in a volume ratio of 1:5, heated to 240°C for vaporization, and then introduced into the fixed bed reactor. The temperature of the reactor was controlled at 300-320°C and the space velocity was 2.0 h / min. -1 After the reaction, the conversion rate of m-cresol was measured to be 98.8%, and the yield of 2,3,6-trimethylphenol was 96.5%.

[0058] Application Example 2:

[0059] The catalyst in Application Example 1 was replaced by the catalyst in Example 2, and other conditions remained unchanged. The conversion rate of m-cresol was measured to be 99.6%, and the yield of 2,3,6-trimethylphenol was 98.2%.

[0060] Application Example 3:

[0061] The catalyst in Application Example 1 was replaced by the catalyst in Example 3, and other conditions remained unchanged. The conversion rate of m-cresol was measured to be 98.5%, and the yield of 2,3,6-trimethylphenol was 96.7%.

[0062] Application example 4:

[0063] The catalyst in Application Example 1 was replaced by the catalyst in Example 4, and the other conditions remained unchanged. The conversion rate of m-cresol was measured to be 97.4%, and the yield of 2,3,6-trimethylphenol was 96.1%.

[0064] Application Example 5:

[0065] The catalyst in Application Example 1 was replaced by the catalyst in Comparative Example, and other conditions remained unchanged. The conversion rate of m-cresol was measured to be 88.7%, and the yield of 2,3,6-trimethylphenol was 91.2%.

[0066] The above-described embodiments are compared with the technical solutions and beneficial effects of the present invention, and it should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol, characterized in that: The preparation method comprises the following steps: The iron salt and the modifier are mixed in dimethyl sulfoxide to form a mixed solution, activated carbon is added to the mixed solution, the mixed solution is placed in an environment of 40-50° C., and ultrasonically treated at 60-80 W for 25-45 minutes to obtain an iron-based catalyst, and the iron-based catalyst is dried at 100-120° C. for 8-12 hours to obtain a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol; The preparation method of the modifier comprises the following steps: The metal ion salt solution and the chloride ion salt are mixed in a polar organic solvent, reacted in a water bath, and then vacuum dried to obtain the modifier; The chloride ion-containing salt is 2-(trichloroacetyl)pyrrole or 4-chloropiperidine or 1-piperidinyl chloride; The metal ion salt solution includes aluminum chloride or copper chloride.

2. The method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol according to claim 1, characterized in that: The iron salt includes any one or more of ferric chloride hexahydrate, ferric nitrate nonahydrate and ferric sulfate hydrate.

3. The method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol according to claim 1, characterized in that: The polar organic solvent includes methanol, ethanol or tetrahydrofuran.

4. The method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol according to claim 1, characterized in that: The conditions of the water bath reaction include reacting at 70-80° C. for 3-4 hours.

5. The method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol according to claim 1, characterized in that: The molar ratio of the metal ion salt solution to the chloride ion salt is 1-3:

1.

6. The method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol according to claim 1, characterized in that: The mass ratio of the iron salt to the modifier is 1:2-4.

7. A catalyst prepared by the method for preparing a catalyst for synthesizing 2,3,6-trimethylphenol from m-cresol according to any one of claims 1 to 6.