CN113105320A - Refining method of p-tert-butyl benzoic acid - Google Patents
Refining method of p-tert-butyl benzoic acid Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
- C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/04—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing carboxylic acids or their salts
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- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
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- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
- B01J31/38—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24 of titanium, zirconium or hafnium
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- C—CHEMISTRY; METALLURGY
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
- C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring
- C07C2/64—Addition to a carbon atom of a six-membered aromatic ring
- C07C2/66—Catalytic processes
- C07C2/70—Catalytic processes with acids
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/47—Separation; Purification; Stabilisation; Use of additives by solid-liquid treatment; by chemisorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
- B01J2231/70—Oxidation reactions, e.g. epoxidation, (di)hydroxylation, dehydrogenation and analogues
Abstract
The invention provides a refining method of p-tert-butyl benzoic acid, which comprises the following steps: step one, obtaining p-tert-butyl toluene; adding the p-tert-butyl toluene obtained in the step one and a supported composite catalyst into a reaction kettle, introducing oxygen, and carrying out oxidation reaction at a certain temperature to obtain a p-tert-butyl benzoic acid crude product; step three, cooling and crystallizing the p-tert-butyl benzoic acid crude product obtained in the step two, centrifuging and spin-drying, and washing with p-tert-butyl toluene to obtain a centrifugal crude product; and step four, adding the centrifugal crude product into a dissolving kettle, centrifuging, and drying to obtain a p-tert-butyl benzoic acid finished product. The invention has the beneficial effects that: the invention adopts the crude product to obtain a high-quality product through simple water washing, simplifies the post-treatment process, and can improve the quality of the product and reduce the production cost.
Description
Technical Field
The invention relates to the field of preparation of p-tert-butyl benzoic acid, and more particularly relates to a refining method of p-tert-butyl benzoic acid.
Background
The p-tert-butyl benzoic acid is an organic synthesis intermediate, and is mainly used for various special functions of polypropylene nucleating agents, polyvinyl chloride heat stabilizers, additives of metal processing cutting and lubricating oil, antioxidants, alkyd resin modifiers, soldering flux, dyes and the like.
The production route of p-tert-butyl benzoic acid mainly comprises a high-temperature gas-phase oxidation method, an electrochemical oxidation method, a liquid-phase solvent-free oxidation method and the like. The high-temperature gas-phase oxidation method is rarely adopted due to higher reaction temperature (420 ℃), complex catalyst preparation and lower selectivity (only about 65%); although the electrochemical oxidation method is pollution-free, the yield is low (less than 30 percent) and the electrochemical oxidation method is not suitable for industrial production; the liquid phase solvent oxidation method promotes the full contact of reactants and a catalyst due to the existence of a solvent (mainly acetic acid), prevents the precipitation of a product at the later stage of the reaction, enables the reaction to be carried out at a lower temperature, has high yield, and is the main method for industrially producing the tert-butyl benzoic acid at present.
However, in the production of t-butylbenzoic acid, there is a problem of corrosion of the equipment due to the presence of bromide.
Disclosure of Invention
The invention overcomes the defects in the prior art and provides a refining method of p-tert-butyl benzoic acid.
The purpose of the invention is realized by the following technical scheme.
The refining process of p-tert-butyl benzoic acid includes the following steps:
step one, obtaining p-tert-butyl toluene;
adding the p-tert-butyl toluene obtained in the step one and a supported composite catalyst into a reaction kettle, introducing oxygen, and carrying out oxidation reaction at two gradient temperatures to obtain a crude p-tert-butyl benzoic acid;
step three, cooling, crystallizing and centrifugally drying the p-tert-butyl benzoic acid crude product obtained in the step two, and washing with p-tert-butyl toluene to obtain a centrifugal crude product, wherein the p-tert-butyl benzoic acid is crystallized by adopting a gradient cooling mode, the gradient temperature is divided into 3 cooling intervals, and the lowest value of each cooling interval is 90 ℃, 40 ℃ and 10 ℃ respectively;
and step four, adding the centrifugal crude product obtained in the step three into a dissolving kettle, adding toluene, heating to dissolve, transferring the material to a recrystallization kettle, cooling, crystallizing, and drying to obtain a p-tert-butyl benzoic acid finished product.
Preferably, the specific method for obtaining p-tert-butyltoluene in the first step is as follows:
step one, adding toluene and concentrated sulfuric acid into a reaction kettle, and introducing isobutene to perform alkylation reaction to obtain crude p-tert-butyl toluene;
and secondly, rectifying the crude product p-tert-butyl toluene obtained in the first step to obtain p-tert-butyl toluene.
Preferably, in any of the above embodiments, the alkylation reaction in the first step is carried out at a temperature of 20 to 24 ℃ for a time of 9 to 11 hours.
Preferably, in any of the above embodiments, the supported composite catalyst in the second step comprises a titanium zeolite and a supported catalyst, and the titanium zeolite and the supported catalyst are also co-pelletized or co-extruded before use.
Preferably, according to any of the above schemes, the preparation method of the supported catalyst comprises the following steps:
firstly, drying silica gel at the temperature of 120-150 ℃ for 3-5h, and removing adsorbed moisture and volatile substances for later use;
secondly, preparing a mixed solution of cobalt acetate and sodium bromide according to a molar ratio of 1: 3 by using deionized water, adding the silica gel under the stirring condition to form sol, and enabling the silica gel to be just capable of being equally immersed with the mixed solution of cobalt acetate and sodium bromide; standing and aging the sol at room temperature for 36h, drying the sol at 140 ℃, activating at 290-310 ℃ for 2-4h, and finally activating at 400-600 ℃ for 4-6h to prepare the supported composite catalyst.
Preferably, in any of the above schemes, the oxidation reaction is performed in the reaction kettle in the second step, and the reaction is performed for 0.25-2h at the temperature of 150-155 ℃; then reacting for 5h at 135-145 ℃.
Preferably, in any of the above schemes, the temperature is reduced from the reaction temperature to 70 ℃ at a speed of 25-35 ℃/h in the first temperature reduction interval, the temperature is reduced to 40 ℃ at a speed of 12-18 ℃/h in the second temperature reduction interval, and the temperature is reduced to 10 ℃ to room temperature at a speed of 6-10 ℃/h in the third temperature reduction interval.
Preferably, the amount of the supported composite catalyst added is 0.1-1.0% of the weight of the p-tert-butyltoluene.
The invention has the beneficial effects that:
the p-tert-butyl benzoic acid is prepared by a high-temperature and high-pressure method by using acetic acid as a solvent and cobalt acetate as a catalyst; the invention takes the p-tert-butyl toluene as the raw material and the solvent at the same time, and adds the composite catalyst, and the normal pressure oxidation method reduces the production cost;
by applying the self-made supported composite catalyst, reagents such as acetic acid, bromide and the like are not used, so that the problems of corrosion caused by the reagents and complex post-treatment can be solved;
the self-made supported composite catalyst has high activity, easy separation, repeated use, low production cost, environmental protection and safe production;
the reaction is carried out at a lower temperature to obtain the p-tert-butyl benzoic acid crude product, and the method avoids the problems of equipment corrosion and complex post-treatment caused by the existence of bromide.
The gradient cooling is divided into 3 temperature intervals, and the formed crystals can grow rapidly and stably in a high temperature interval, a medium temperature interval and a low temperature interval, so that the crystals can grow rapidly and stably.
The invention adopts the crude product to obtain a high-quality product through simple water washing, simplifies the post-treatment process, and can improve the quality of the product and reduce the production cost.
Detailed Description
The technical solution of the present invention is further illustrated by the following specific examples.
The refining process of p-tert-butyl benzoic acid includes the following steps:
step one, obtaining p-tert-butyl toluene; the specific method for obtaining the p-tert-butyl toluene in the first step comprises the following steps: step one, adding toluene and concentrated sulfuric acid into a reaction kettle, and introducing isobutene to perform alkylation reaction to obtain crude p-tert-butyl toluene; secondly, rectifying the crude product p-tert-butyl toluene obtained in the first step to obtain p-tert-butyl toluene; the toluene, the isobutene and the concentrated sulfuric acid are prepared from the following components in parts by weight: 16-19 parts of toluene, 7.5-8 parts of isobutene and 4.2-4.5 parts of concentrated sulfuric acid; preferably, the toluene, the isobutene and the concentrated sulfuric acid are in parts by weight: 18 parts of toluene, 8 parts of isobutene and 4.5 parts of concentrated sulfuric acid; the weight ratio of the cobalt acetate to the bromide is 1: 1.15-1.2; the alkylation reaction in the first step is carried out at the temperature of 20-24 ℃ for 9-11 hours.
Step two, adding the p-tert-butyl toluene obtained in the step one and a supported composite catalyst into a reaction kettle, wherein the addition amount of the supported composite catalyst is 0.1-1.0% of the weight of the p-tert-butyl toluene, introducing oxygen, performing oxidation reaction in the reaction kettle in the step two, and firstly reacting for 0.25-2h at the temperature of 150-; then reacting for 5h at the temperature of 135 ℃ and 145 ℃ to obtain a crude product of p-tert-butyl benzoic acid;
the supported composite catalyst in the step two comprises titanium zeolite and a supported catalyst, and the titanium zeolite and the supported catalyst are also subjected to co-granulation or co-extrusion molding before use; the titanium zeolite is titanium silicalite, and the titanium zeolite is TS-1.
The preparation method of the supported catalyst comprises the following steps:
firstly, drying silica gel at the temperature of 120-150 ℃ for 3-5h, and removing adsorbed moisture and volatile substances for later use;
preferably, the silica gel has a surface area of 10 to 700m2A more preferred silica gel has a surface area of from 50 to 500m2(iv) g, most preferably the surface area of the silica gel is 100-400m2/g；
The pore volume of the silica gel is from 0.1 to 4.0ml/g, more preferably the pore volume of the silica gel is from 0.5 to 3.5ml/g, most preferably the pore volume of the silica gel is from 0.8 to 3.0 ml/g;
the average particle size of the silica gel is in the range of 0.1 to 500. mu.m, more preferably 1 to 200. mu.m, and most preferably 10 to 100. mu.m.
Secondly, preparing a mixed solution of cobalt acetate and sodium bromide according to a molar ratio of 1: 3 by using deionized water, adding the silica gel under the stirring condition to form sol, and enabling the silica gel to be just capable of being equally immersed with the mixed solution of cobalt acetate and sodium bromide; standing and aging the sol at room temperature for 36h, drying the sol at 140 ℃, activating at 290-310 ℃ for 2-4h, and finally activating at 400-600 ℃ for 4-6h to prepare the supported composite catalyst.
Step three, cooling, crystallizing and centrifugally drying the p-tert-butyl benzoic acid crude product obtained in the step two, and washing with p-tert-butyl toluene to obtain a centrifugal crude product, wherein the p-tert-butyl benzoic acid is crystallized by adopting a gradient cooling mode, the gradient temperature is divided into 3 cooling intervals, and the lowest value of each cooling interval is 90 ℃, 40 ℃ and 10 ℃ respectively; the temperature is reduced from the reaction temperature to 70 ℃ at the speed of 25-35 ℃/h in the first temperature reduction interval, the temperature is reduced to 40 ℃ at the speed of 12-18 ℃/h in the second temperature reduction interval, and the temperature is reduced to 10 ℃ to the room temperature at the speed of 6-10 ℃/h in the third temperature reduction interval.
And step four, adding the centrifuged crude product into a dissolving kettle, adding toluene, heating to dissolve, carrying out hot filtration to remove impurities, adding water for washing, transferring the material to a recrystallization kettle, cooling and crystallizing, centrifuging, washing with toluene, and drying to obtain a p-tert-butylbenzoic acid finished product.
Example 1
1. P-tert-butyltoluene was obtained: adding toluene and concentrated sulfuric acid into a reaction kettle, introducing isobutene to perform alkylation reaction to obtain crude p-tert-butyl toluene, wherein the alkylation reaction temperature is 20 ℃ and the alkylation reaction time is 11 hours, and then rectifying the crude p-tert-butyl toluene to obtain the p-tert-butyl toluene.
2. Synthesis of p-tert-butylbenzoic acid: adding p-tert-butyl toluene, titanium zeolite and a supported catalyst into a reaction kettle, introducing a gas mixture containing 90% of oxygen and other inert gases, starting to react at the temperature of 150 ℃ at the beginning of the reaction, and carrying out oxidation reaction for 2 hours at the temperature; then the temperature is reduced to 135 ℃ to continue the oxidation reaction, the reaction time is 5h, and a crude product of the p-tert-butyl benzoic acid is obtained.
3. Gradient cooling crystallization
The solution containing the crude p-tert-butylbenzoic acid is cooled in a gradient way, the temperature is firstly reduced from the reaction temperature to about 70 ℃ at the speed of 25 ℃/h, then is uniformly reduced to about 40 ℃ at the speed of 12 ℃/h, at the moment, crystals begin to precipitate, and is then uniformly reduced to 10 ℃ at the speed of 6 ℃/h. And (3) completely crystallizing the p-tert-butyl benzoic acid, centrifugally drying, washing with a small amount of p-tert-butyl toluene to obtain a centrifugal crude product, circularly applying the centrifugal mother liquor to the next batch of oxidation reaction, and repeatedly applying the centrifugal mother liquor for 11-12 times.
Adding the obtained centrifugal crude product into a dissolving kettle, adding toluene accounting for 2.5 times of the volume of the centrifugal crude product, heating for dissolving, carrying out hot filtration to remove impurities, adding water for washing for 3 times, transferring the material to a recrystallization kettle for cooling and crystallizing, centrifuging, washing for 3 times by using a small amount of toluene, and drying in a vacuum drying mode to obtain the p-tert-butylbenzoic acid finished product. The washing water is recycled, and the recrystallization mother liquor is mainly toluene which can be recycled for 7-10 times.
The finished product of the p-tert-butyl benzoic acid prepared by the method is white crystal, has no mechanical impurities, has a melting point range of 165.3-166.3 ℃, an acid value of 314-316mgKOH/g, a purity of 99.5 percent by HPLC detection, a water content of 0.05 percent and a toluene content of 0.03 percent.
Example 2
1. P-tert-butyltoluene was obtained: adding toluene and concentrated sulfuric acid into a reaction kettle, introducing isobutene to perform alkylation reaction to obtain crude p-tert-butyl toluene, wherein the alkylation reaction temperature is 24 ℃ and the alkylation reaction time is 9 hours, and then rectifying the crude p-tert-butyl toluene to obtain the p-tert-butyl toluene.
2. Synthesis of p-tert-butylbenzoic acid: adding p-tert-butyltoluene, titanium zeolite and a supported catalyst into a reaction kettle, introducing a gas mixture containing 90% of oxygen and other inert gases, starting to react at 155 ℃ in the reaction starting stage, and carrying out oxidation reaction for 0.25h at the temperature; then the temperature is reduced to 145 ℃ for continuous oxidation reaction, the reaction time is 5h, and crude p-tert-butyl benzoic acid is obtained.
4. Gradient cooling crystallization
The solution containing the crude p-tert-butylbenzoic acid is cooled in a gradient way, the temperature is firstly reduced from the reaction temperature to about 70 ℃ at the speed of 35 ℃/h, then is uniformly reduced to about 40 ℃ at the speed of 18 ℃/h, at the moment, crystals begin to precipitate, and is then uniformly reduced to 10 ℃ at the speed of 10 ℃/h. And (3) completely crystallizing the p-tert-butyl benzoic acid, centrifugally drying, washing with a small amount of p-tert-butyl toluene to obtain a centrifugal crude product, circularly applying the centrifugal mother liquor to the next batch of oxidation reaction, and repeatedly applying the centrifugal mother liquor for 11-12 times.
Adding the obtained centrifugal crude product into a dissolving kettle, adding toluene accounting for 2.5 times of the volume of the centrifugal crude product, heating for dissolving, carrying out hot filtration to remove impurities, adding water for washing for 3 times, transferring the material to a recrystallization kettle for cooling and crystallizing, centrifuging, washing for 3 times by using a small amount of toluene, and drying in a vacuum drying mode to obtain the p-tert-butylbenzoic acid finished product. The washing water is recycled, and the recrystallization mother liquor is mainly toluene which can be recycled for 7-10 times.
The finished product of the p-tert-butyl benzoic acid prepared by the method is white crystal, has no mechanical impurities, has a melting point range of 164.4-165.1 ℃, an acid value of 314-316mgKOH/g, a purity of 99.3 percent by HPLC detection, a water content of 0.04 percent and a toluene content of 0.03 percent.
Example 3
1. P-tert-butyltoluene was obtained: adding toluene and concentrated sulfuric acid into a reaction kettle, introducing isobutene to perform alkylation reaction to obtain crude p-tert-butyl toluene, wherein the alkylation reaction temperature is 22 ℃ and the alkylation reaction time is 10 hours, and then rectifying the crude p-tert-butyl toluene to obtain the p-tert-butyl toluene.
2. Synthesis of p-tert-butylbenzoic acid: adding p-tert-butyltoluene, titanium zeolite and a supported catalyst into a reaction kettle, introducing a gas mixture containing 90% of oxygen and other inert gases, starting to react at 153 ℃ in the reaction starting stage, and carrying out oxidation reaction for 1.25h at the temperature; then the temperature is reduced to 130 ℃ to continue the oxidation reaction, the reaction time is 5h, and a crude product of the p-tert-butyl benzoic acid is obtained.
3. Gradient cooling crystallization
The solution containing the crude p-tert-butylbenzoic acid is cooled in a gradient way, the temperature is firstly reduced from the reaction temperature to about 70 ℃ at the speed of 30 ℃/h, then is uniformly reduced to about 40 ℃ at the speed of 15 ℃/h, at the moment, crystals begin to precipitate, and is then uniformly reduced to 10 ℃ at the speed of 8 ℃/h. And (3) completely crystallizing the p-tert-butyl benzoic acid, centrifugally drying, washing with a small amount of p-tert-butyl toluene to obtain a centrifugal crude product, circularly applying the centrifugal mother liquor to the next batch of oxidation reaction, and repeatedly applying the centrifugal mother liquor for 11-12 times.
Adding the obtained centrifugal crude product into a dissolving kettle, adding toluene accounting for 2.5 times of the volume of the centrifugal crude product, heating for dissolving, carrying out hot filtration to remove impurities, adding water for washing for 3 times, transferring the material to a recrystallization kettle for cooling and crystallizing, centrifuging, washing for 3 times by using a small amount of toluene, and drying in a vacuum drying mode to obtain the p-tert-butylbenzoic acid finished product. The washing water is recycled, and the recrystallization mother liquor is mainly toluene which can be recycled for 7-10 times.
The finished product of the p-tert-butyl benzoic acid prepared by the method is white crystal, has no mechanical impurities, has a melting point range of 164.5-166.5 ℃, an acid value of 314-316mgKOH/g, a purity of 99.4 percent by HPLC detection, a water content of 0.04 percent and a toluene content of 0.04 percent.
The three embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (8)
1. A process for purifying p-tert-butylbenzoic acid, which comprises the steps of: the method comprises the following steps:
step one, obtaining p-tert-butyl toluene;
adding the p-tert-butyl toluene obtained in the step one and a supported composite catalyst into a reaction kettle, introducing oxygen, and carrying out oxidation reaction at two gradient temperatures to obtain a crude p-tert-butyl benzoic acid;
step three, cooling, crystallizing and centrifugally drying the p-tert-butyl benzoic acid crude product obtained in the step two, and washing with p-tert-butyl toluene to obtain a centrifugal crude product, wherein the p-tert-butyl benzoic acid is crystallized by adopting a gradient cooling mode, the gradient temperature is divided into 3 cooling intervals, and the lowest value of each cooling interval is 90 ℃, 40 ℃ and 10 ℃ respectively;
and step four, adding the centrifugal crude product obtained in the step three into a dissolving kettle, adding toluene, heating to dissolve, transferring the material to a recrystallization kettle, cooling, crystallizing, and drying to obtain a p-tert-butyl benzoic acid finished product.
2. The process according to claim 1, wherein: the specific method for obtaining the p-tert-butyl toluene in the first step comprises the following steps:
step one, adding toluene and concentrated sulfuric acid into a reaction kettle, and introducing isobutene to perform alkylation reaction to obtain crude p-tert-butyl toluene;
and secondly, rectifying the crude product p-tert-butyl toluene obtained in the first step to obtain p-tert-butyl toluene.
3. The process according to claim 2, wherein: the alkylation reaction in the first step is carried out at the temperature of 20-24 ℃ for 9-11 hours.
4. The process according to claim 3, wherein: the supported composite catalyst in the second step comprises titanium zeolite and a supported catalyst, and the titanium zeolite and the supported catalyst are also co-granulated or co-extruded and molded before use.
5. The process according to claim 4, wherein: the preparation method of the supported catalyst comprises the following steps:
firstly, drying silica gel at the temperature of 120-150 ℃ for 3-5h, and removing adsorbed moisture and volatile substances for later use;
secondly, preparing a mixed solution of cobalt acetate and sodium bromide according to a molar ratio of 1: 3 by using deionized water, adding the silica gel under the stirring condition to form sol, and enabling the silica gel to be just capable of being equally immersed with the mixed solution of cobalt acetate and sodium bromide; standing and aging the sol at room temperature for 36h, drying the sol at 140 ℃, activating at 290-310 ℃ for 2-4h, and finally activating at 400-600 ℃ for 4-6h to prepare the supported composite catalyst.
6. The process according to claim 5, wherein: in the second step, oxidation reaction is carried out in the reaction kettle, and the reaction is carried out for 0.25-2h at the temperature of 150-155 ℃; then reacting for 5h at 135-145 ℃.
7. The process according to claim 6, wherein: the temperature is reduced from the reaction temperature to 70 ℃ at the speed of 25-35 ℃/h in the first temperature reduction interval, the temperature is reduced to 40 ℃ at the speed of 12-18 ℃/h in the second temperature reduction interval, and the temperature is reduced to 10 ℃ to the room temperature at the speed of 6-10 ℃/h in the third temperature reduction interval.
8. The process according to any one of claims 1 to 7, wherein: the addition amount of the supported composite catalyst is 0.1-1.0% of the weight of the p-tert-butyl toluene.
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| CN1571776A (en) * | 2001-10-19 | 2005-01-26 | 阿克奥化学技术有限公司 | Direct epoxidation process using a mixed catalyst system |
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