Method for recovering intermediate from 2-ethyl anthraquinone waste sulfuric acid

Abstract

The invention relates to the technical field of synthesis of 2-ethyl anthraquinone, in particular to a method for recovering an intermediate from waste sulfuric acid of 2-ethyl anthraquinone, which comprises the following steps: pumping waste sulfuric acid containing 2-ethyl anthraquinone into a reaction tank, starting stirring, adding magnesium oxide mineral powder, heating to 120-140 DEG C, and carrying out heat preservation reaction for 2-6 hours; after the reaction is finished, adding an extracting agent, layering, and respectively collecting an organic phase and a water phase; and washing the organic phase with hot water at 80-90 DEG C, and distilling to remove the extracting agent to obtain the ethyl anthraquinone intermediate 2-ethyl benzoylbenzoic acid. The technical scheme provided by the invention can be directly adapted to the waste sulfuric acid generated by the existing 2-ethyl anthraquinone production process, large-scale transformation of the existing production equipment is not needed, the transformation difficulty is low, and the investment is low; the 2-ethyl benzoylbenzoic acid intermediate can be directly used for subsequent preparation of ethyl anthraquinone, so that a production closed loop is realized, and the economic benefits and environmental protection benefits of the whole production process are improved.

Description

Technical Field

[0001] This invention relates to the field of 2-ethylanthraquinone synthesis technology, and in particular to a method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid. Background Technology

[0002] 2-Ethylanthraquinone is the core catalyst in the anthraquinone process for producing hydrogen peroxide. Its synthesis process generates a large amount of waste sulfuric acid containing 2-ethylanthraquinone and its derivatives. If discharged directly, it will not only waste sulfuric acid resources but also seriously pollute the environment.

[0003] Meanwhile, 2-ethylbenzoylbenzoic acid (a key intermediate in the synthesis of 2-ethylanthraquinone) contained in waste sulfuric acid has high recycling value. If the resource utilization of waste sulfuric acid and the efficient recycling of intermediates can be realized, the production cost of 2-ethylanthraquinone can be significantly reduced, achieving a win-win situation for both environmental protection and economic benefits.

[0004] Existing recovery methods suffer from low intermediate recovery rates. Currently, waste sulfuric acid generated during the production of 2-ethylanthraquinone is typically disposed of by neutralization before discharge or by simple treatment and sale as a low-value byproduct, failing to effectively recover the organic intermediates contained therein. Summary of the Invention

[0005] In view of the deficiencies mentioned in the background art, the present invention provides a method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid, aiming to achieve resource utilization of waste sulfuric acid and efficient recovery of 2-ethylbenzoylbenzoic acid intermediates.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: a method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid, comprising the following steps: S1. Add waste sulfuric acid containing 2-ethylanthraquinone into the reaction vessel, start stirring, add magnesium oxide ore powder, control the mass fraction of magnesium oxide ore powder in the system to be 5% to 15%, raise the temperature to 120 to 140°C, and keep the reaction at this temperature for 2 to 6 hours. S2. After the reaction is complete, add the extractant, and collect the organic phase and aqueous phase separately after separation. S3. The aqueous phase is pumped into a negative pressure vessel to remove the residual extractant under negative pressure. Then, magnesium oxide powder is added to adjust the pH to 5-6. After pressure filtration to remove the undissolved magnesium oxide residue, the temperature is lowered, and the precipitated magnesium sulfate heptahydrate is collected. After drying, the magnesium sulfate heptahydrate product is obtained. S4. The organic phase is washed with hot water at 80-90℃ and then distilled to remove the extractant, yielding the ethyl anthraquinone intermediate 2-ethylbenzoylbenzoic acid.

[0007] As a further improvement of the present invention, the extractant is toluene or chlorobenzene.

[0008] As a further improvement of the present invention, the 2-ethylbenzoylbenzoic acid is further cyclically closure with fuming sulfuric acid to obtain ethylanthraquinone.

[0009] As a further improvement of the present invention, the volume ratio of the extractant to the reaction system is 1:1 to 1:2.

[0010] As a further improvement of the present invention, the mass ratio of 2-ethylbenzoylbenzoic acid to fuming sulfuric acid is 1:1.2 to 1:1.5.

[0011] As a further improvement of the present invention, the SO3 mass fraction in the fuming sulfuric acid is 20% to 30%.

[0012] As a further improvement of the present invention, the mass fraction of sulfuric acid in the waste sulfuric acid is 35% to 40%.

[0013] As a further improvement of the present invention, the particle size of the magnesium oxide ore powder is 80-120 mesh.

[0014] After adopting the above technical solution, the beneficial effects of the present invention are: The technical solution of this invention can be directly adapted to the waste sulfuric acid generated by the existing 2-ethylanthraquinone production process without the need for large-scale modification of existing production equipment. The modification is simple and requires little investment. The recovered magnesium sulfate heptahydrate product can be widely used in chemical, agricultural and other fields. The 2-ethylbenzoylbenzoic acid intermediate can be directly used for the subsequent preparation of ethylanthraquinone, realizing a closed-loop production and improving the economic and environmental benefits of the entire production process. Detailed Implementation

[0015] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0016] 2-Ethylanthraquinone (2-EAQ) is an essential reaction carrier for the anthraquinone process in the preparation of hydrogen peroxide. Currently, its industrial preparation process mainly consists of the following two steps: (1) Phthalic anhydride, ethylbenzene and aluminum trichloride react, and then acid hydrolyze and desolventize to obtain the intermediate 2-ethylbenzoylbenzoic acid; (2) 2-Ethylbenzoylbenzoic acid is reacted with fuming sulfuric acid to produce 2-ethylanthraquinone. After extraction, alkali washing, water washing to remove solvent, and purification, 2-ethylanthraquinone is obtained.

[0017] In the above-mentioned ring-closure reaction process, fuming sulfuric acid, acting as both a medium and catalyst, inevitably undergoes a side reaction with 2-ethylbenzoylbenzoic acid to generate sulfonic acid compounds, primarily monosulfonic and disulfonic acid compounds. The reaction formula is as follows:

[0018] Unreacted intermediates and byproducts enter the next sulfuric acid treatment process, increasing the difficulty and cost of treating waste sulfuric acid after the reaction, and also causing waste of unreacted intermediates.

[0019] Example 1 This embodiment provides a method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid. The specific preparation steps and technical details are as follows.

[0020] Waste sulfuric acid generated during the production of 2-ethylanthraquinone was selected, filtered first to remove mechanical impurities and insoluble residues, and then allowed to settle for 2 hours before the supernatant was taken for use.

[0021] 50 tons of supernatant were pumped into a 50 cubic meter reaction tank. The mass fraction of sulfuric acid in the waste sulfuric acid was 36%, meaning that the mass of sulfuric acid accounted for 36% of the total mass of the waste sulfuric acid solution.

[0022] Start stirring, add magnesium oxide ore powder with an average particle size of 80 mesh, and stir thoroughly to ensure it is fully dispersed in the system. Control the mass fraction of magnesium oxide ore powder in the system to be 5%. After the addition is complete, raise the temperature to 120℃ and maintain the temperature for 2 hours.

[0023] After the reaction is complete, wait for the temperature of the reaction system to drop to 70°C, then add toluene as an extractant, with a volume ratio of extractant to reaction system of 1:1. After adding the extractant, stir thoroughly to ensure that the organic components in the reaction system are completely dissolved in the extractant. After stirring is complete, stop stirring, allow the mixture to stand and separate into layers, and collect the organic phase and aqueous phase separately.

[0024] The collected aqueous phase was pumped into a negative pressure vessel, the negative pressure device was turned on, and the negative pressure was adjusted to -0.06 MPa. The temperature control device of the negative pressure vessel was turned on, and the temperature inside the vessel was controlled at 80℃. The residual toluene extractant in the aqueous phase was removed under negative pressure for 1.5 hours. The residual toluene in the aqueous phase was measured to be 0.08%. After the extractant removal was completed, the negative pressure device was turned off, and the aqueous phase was cooled to 65℃. Magnesium oxide powder with an average mesh size of 80 mesh was slowly added, and the stirring speed was adjusted to 100 r / min. The pH value of the system was continuously stirred and monitored in real time, and the pH value was precisely adjusted to 5.5 (within the 5-6 limit range). After adjustment, stirring was continued for 20 minutes to fully disperse the undissolved magnesium oxide. The system was then sent to a plate and frame filter press, and the filtration pressure was adjusted to 0.3 MPa. Filtration was performed using a filter cloth with a pore size of 5 μm to remove the undissolved magnesium oxide residue in the system, resulting in a clear filtrate. The clarified filtrate was fed into a crystallization vessel, and the cooling rate was adjusted to 2℃ / min, slowly cooling to 25℃. Crystallization was allowed to proceed for 6 hours. The centrifuge was then turned on, and the centrifuge speed was adjusted to 1500 r / min. The precipitated magnesium sulfate heptahydrate crystals were collected. The collected crystals were washed twice with deionized water to remove trace impurities adhering to the surface, and then sent to a drying oven. The drying temperature was controlled at 80℃, and the drying time was 2.5 hours to remove free moisture from the crystal surface, yielding the magnesium sulfate heptahydrate product.

[0025] The collected organic phase was transferred to a washing vessel, and deionized water at 85°C was added. The volume ratio of organic phase to deionized water was 2:1. The stirring speed was adjusted to 150 r / min, and the mixture was washed for 30 min. After stirring was stopped, the mixture was allowed to stand for 25 min to separate into layers, and the lower aqueous phase was removed. The washing was repeated twice until the pH of the aqueous phase after washing was 6.5 (within the range of 6-7), confirming that there were no acidic impurities remaining in the organic phase. The washed organic phase was then transferred to a distillation vessel, and the distillation apparatus was turned on. The distillation temperature was controlled at 115°C, and the toluene extractant in the organic phase was removed by atmospheric distillation. The distilled toluene was condensed, dried, purified, and then used for subsequent extraction steps. After distillation, the distillation apparatus was turned off, and the residue in the distillation vessel was collected. This residue was the ethyl anthraquinone intermediate 2-ethylbenzoylbenzoic acid. The purity of this intermediate was tested to be 97.5%, with no obvious impurities remaining.

[0026] The 2-ethylbenzoylbenzoic acid obtained above was fed into a closed-loop reactor. The stirrer was turned on, and fuming sulfuric acid (containing 25% SO3 by mass) was slowly added dropwise, maintaining a mass ratio of 2-ethylbenzoylbenzoic acid to fuming sulfuric acid of 1:1.3. After the addition was complete, the reaction temperature was adjusted to 85°C, and the reaction was continuously stirred for 4 hours to ensure complete ring closure of the 2-ethylbenzoylbenzoic acid. After the reaction was complete, the reaction product was slowly added to ice water at a mass ratio of 1:6. The mixture was stirred to dilute the product, and a solid precipitated. The solid was collected by filtration, washed with deionized water until neutral, and then placed in a drying oven at 105°C for 2.5 hours to obtain an ethylanthraquinone product with a purity of 98.6%.

[0027] Example 2 This embodiment provides a method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid. The specific preparation steps and technical details are as follows.

[0028] Waste sulfuric acid generated during the production of 2-ethylanthraquinone was selected, filtered first to remove mechanical impurities and insoluble residues, and then allowed to settle for 2 hours before the supernatant was taken for use.

[0029] 50 tons of supernatant liquid, containing 35% sulfuric acid by mass, was pumped into a 50 cubic meter reaction vessel. Stirring was started, and magnesium oxide powder with an average particle size of 100 mesh was added and stirred thoroughly to ensure complete dispersion in the system, maintaining a magnesium oxide powder mass fraction of 10%. After addition, the temperature was raised to 125°C and maintained for 4 hours.

[0030] After the reaction is complete, wait for the temperature of the reaction system to drop to 75°C, then add chlorobenzene as an extractant, with a volume ratio of extractant to reaction system of 1:1.5. After adding the extractant, stir thoroughly to ensure that the organic components in the reaction system are completely dissolved in the extractant. After stirring is complete, stop stirring, allow the mixture to stand and separate into layers, and collect the organic phase and aqueous phase separately.

[0031] The collected aqueous phase is pumped into a negative pressure vessel using a transfer pump, and magnesium sulfate heptahydrate is obtained by following the steps in Example 1.

[0032] The collected organic phase was fed into a water washing tank, and the steps of Example 1 were followed to obtain 2-ethylbenzoylbenzoic acid, an ethyl anthraquinone intermediate. The purity of the intermediate was tested to be 97.3%, with no obvious impurities remaining.

[0033] The 2-ethylbenzoylbenzoic acid obtained above was fed into a closed-loop reactor. The stirrer was turned on, and fuming sulfuric acid (containing 20% ​​SO3 by mass) was slowly added dropwise, maintaining a mass ratio of 2-ethylbenzoylbenzoic acid to fuming sulfuric acid of 1:1.2. After the addition was complete, the reaction temperature was adjusted to 85°C, and the reaction was continuously stirred for 4 hours to ensure complete ring closure of the 2-ethylbenzoylbenzoic acid. After the reaction was complete, the reaction product was slowly added to ice water at a mass ratio of 1:6. The mixture was stirred to dilute the product, and a solid precipitated. The solid was collected by filtration, washed with deionized water until neutral, and then placed in a drying oven at 105°C for 2.5 hours to obtain an ethylanthraquinone product with a purity of 98.4%.

[0034] Example 3 This embodiment provides a method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid. The specific preparation steps and technical details are as follows.

[0035] Waste sulfuric acid generated during the production of 2-ethylanthraquinone was selected, filtered first to remove mechanical impurities and insoluble residues, and then allowed to settle for 2 hours before the supernatant was taken for use.

[0036] 50 tons of supernatant liquid, containing 40% sulfuric acid by mass, was pumped into a 50 cubic meter reaction vessel. Stirring was started, and magnesium oxide powder with an average particle size of 120 mesh was added and stirred thoroughly to ensure complete dispersion in the system, maintaining a magnesium oxide powder mass fraction of 15%. After addition, the temperature was raised to 140°C and maintained for 6 hours.

[0037] After the reaction is complete, wait for the temperature of the reaction system to drop to 80°C, then add toluene as an extractant, with a volume ratio of extractant to reaction system of 1:2. After adding the extractant, stir thoroughly to ensure that the organic components in the reaction system are completely dissolved in the extractant. After stirring is complete, stop stirring, allow the mixture to stand and separate into layers, and collect the organic phase and aqueous phase separately.

[0038] The collected aqueous phase is pumped into a negative pressure vessel using a transfer pump, and magnesium sulfate heptahydrate is obtained by following the steps in Example 1.

[0039] The collected organic phase was fed into a water washing tank, and the steps of Example 1 were followed to obtain 2-ethylbenzoylbenzoic acid, an ethyl anthraquinone intermediate. The purity of the intermediate was tested to be 98.1%, with no obvious impurities remaining.

[0040] The 2-ethylbenzoylbenzoic acid obtained above was fed into a closed-loop reactor. The stirrer was turned on, and fuming sulfuric acid (containing 30% SO3 by mass) was slowly added dropwise, maintaining a mass ratio of 2-ethylbenzoylbenzoic acid to fuming sulfuric acid of 1:1.5. After the addition was complete, the reaction temperature was adjusted to 85°C, and the reaction was continuously stirred for 4 hours to ensure complete ring closure of the 2-ethylbenzoylbenzoic acid. After the reaction was complete, the reaction product was slowly added to ice water at a mass ratio of 1:6. The mixture was stirred to dilute the product, precipitating a solid. The solid was collected by filtration, washed with deionized water until neutral, and then placed in a drying oven at 105°C for 2.5 hours to obtain an ethylanthraquinone product with a purity of 98.7%.

[0041] The embodiments described above are not exhaustive and do not limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the above description. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid, characterized in that, Includes the following steps: S1. Add waste sulfuric acid containing 2-ethylanthraquinone into the reaction vessel, start stirring, add magnesium oxide ore powder, control the mass fraction of magnesium oxide ore powder in the system to be 5% to 15%, raise the temperature to 120 to 140°C, and keep the reaction at this temperature for 2 to 6 hours. S2. After the reaction is complete, add the extractant, and collect the organic phase and aqueous phase separately after separation. S3. The aqueous phase is pumped into a negative pressure vessel to remove the residual extractant under negative pressure. Then, magnesium oxide powder is added to adjust the pH to 5-6. After pressure filtration to remove the undissolved magnesium oxide residue, the temperature is lowered, and the precipitated magnesium sulfate heptahydrate is collected. After drying, the magnesium sulfate heptahydrate product is obtained. S4. The organic phase is washed with hot water at 80-90℃ and then distilled to remove the extractant, yielding the ethyl anthraquinone intermediate 2-ethylbenzoylbenzoic acid.

2. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 1, characterized in that: The extractant is toluene or chlorobenzene.

3. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 2, characterized in that: The volume ratio of the extractant to the reaction system is 1:1 to 1:

2.

4. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 1, characterized in that: The 2-ethylbenzoylbenzoic acid is then cyclically closed with fuming sulfuric acid to obtain ethylanthraquinone.

5. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 4, characterized in that: The mass ratio of 2-ethylbenzoylbenzoic acid to fuming sulfuric acid is 1:1.2 to 1:1.

5.

6. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 5, characterized in that: The fuming sulfuric acid contains 20% to 30% SO3 by mass.

7. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 1, characterized in that: The waste sulfuric acid contains 35% to 40% sulfuric acid by mass.

8. The method for recovering intermediates from 2-ethylanthraquinone waste sulfuric acid according to claim 1, characterized in that: The average particle size of the magnesium oxide ore powder is 80-120 mesh.

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