Production method of industrial naphthalene

Abstract

The invention relates to the technical field of industrial naphthalene, in particular to a production method of industrial naphthalene, which comprises the following steps: S1, raw material pretreatment: selecting coal tar as a raw material, and pretreating the coal tar to obtain a coarse material; s2, distillation treatment: carrying out distillation treatment on the coarse material to obtain a base material; s3, purification treatment: carrying out dephenolization and pyridine removal treatment on the base material to obtain naphthalene oil; s4, crystal separation treatment: carrying out crystal separation treatment on the naphthalene oil to obtain crude naphthalene; and S5, refining treatment: carrying out refining treatment on the crude naphthalene to obtain the industrial naphthalene. According to the method, in the first treatment liquid, isopropanol serves as a solubilizing phenol and can play a role in promoting dissolution of sodium phenolate, precipitation and blockage are prevented in the treatment process, the extraction efficiency is improved, polysorbate 80 serves as a surface active agent, diffusion of phenols from an oil phase to alkali liquor can be enhanced, and the extraction efficiency is further improved.

Description

Technical Field

[0001] This invention relates to the field of industrial naphthalene technology, specifically to a method for producing industrial naphthalene. Background Technology

[0002] Industrial naphthalene is an important chemical raw material extracted from coal tar by distillation. Its main component is naphthalene, which is widely used in the production of phthalic anhydride, dye intermediates, rubber additives, pesticides, etc., and is also used as a solvent and preservative.

[0003] In existing technologies, the purification of coal tar in the extraction and production process of industrial naphthalene typically involves alkaline washing and acid washing. This method is not sufficiently effective in purifying coal tar, thus affecting the extraction efficiency of industrial naphthalene. Therefore, this invention provides a method for producing industrial naphthalene. Summary of the Invention

[0004] The purpose of this invention is to provide a method for producing industrial naphthalene. The industrial naphthalene prepared by this method not only has good purity but also excellent yield.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for producing industrial naphthalene.

[0007] Includes the following steps:

[0008] S1: Raw material pretreatment: Coal tar is selected as the raw material. The coal tar is pretreated to obtain coarse material.

[0009] S2: Distillation process, the crude material is distilled to obtain the base material;

[0010] S3: Purification treatment, the base material is subjected to phenol and pyridine removal treatment to obtain naphthalene oil;

[0011] S4: Crystallization separation treatment, naphthalene oil is subjected to crystallization separation treatment to obtain crude naphthalene;

[0012] S5: Refining process, which refines crude naphthalene to obtain industrial naphthalene.

[0013] Furthermore, the method for pre-treating the raw materials is as follows: coal tar is fed into a dehydration tank, which is equipped with a steam heating coil and the temperature is set at 80-86°C. The coal tar is left to stand for dehydration for 24-36 hours. The upper layer of coal tar is pumped out for use. The water content of the upper layer of coal tar is 3-5%. The lower layer of coal tar is further processed.

[0014] Furthermore, the method for further processing of the lower coal tar is as follows: the lower coal tar is heated to 120-130°C under normal pressure for 10-20 hours, and the resulting product is mixed with the upper coal tar to complete the raw material pretreatment and obtain the coarse material.

[0015] Furthermore, the distillation process is as follows: the crude material is fed into a distillation apparatus, the distillation temperature is 210-230℃, the distillation process is completed, and the base material is obtained.

[0016] Further, the purification process is as follows: the base material is fed into an extraction tower, the temperature is set at 160-200℃, a first treatment liquid is added from the top of the tower, followed by a second treatment liquid, the temperature is set at 230-260℃, resulting in a dephenolized base material. The dephenolized base material is then subjected to depyridine treatment. The dephenolized base material and dilute sulfuric acid are added to a reaction vessel, the reaction vessel is set at 50-60℃, the stirring speed is 80-120 r / min, and the mixture is stirred at a constant temperature for 40-60 min. Afterwards, it is allowed to stand for 10-20 h. After the sedimentation, surface substances are removed, and the resulting product is added to a thin-film evaporator and flash-distilled at -0.06--0.08 MPa and 140-160℃. The resulting product is then subjected to distillation at a temperature of 240-250℃ to complete the purification process, yielding naphthalene oil.

[0017] Furthermore, the amount of the first treatment liquid used is 5-10% of the mass of the base material. The preparation method of the first treatment liquid is as follows: isopropanol, sodium hydroxide solution, and polysorbate 80 are added to the reaction vessel. The reaction vessel is set at a temperature of 50-60°C and a stirring speed of 200-400 r / min. The mixture is stirred at a constant temperature for 20-30 min to obtain the first treatment liquid. The mass concentration of the sodium hydroxide solution is 8-12%, and the mass ratio of isopropanol, sodium hydroxide solution, and polysorbate 80 is 1:(0.2-0.4):(0.03-0.05).

[0018] Furthermore, the amount of the second treatment liquid used is 30-35% of the mass of the base material, and the second treatment liquid is a sodium hydroxide solution with a mass concentration of 8-12%.

[0019] Further, the crystallization separation process is as follows: naphthalene oil is heated to 80-90°C, then heating is stopped, and the temperature is lowered to 30-40°C. The resulting product is centrifuged, and solid matter is obtained from the centrifuged product to complete the crystallization separation process and obtain crude naphthalene.

[0020] Furthermore, the refining process is as follows: crude naphthalene is heated to a temperature of 80-90°C, and the crude naphthalene melts to obtain a liquid product. The liquid product is then adsorbed through a molecular sieve fixed bed. The resulting product is subjected to vacuum distillation at a temperature of 230-240°C to complete the refining process and obtain industrial naphthalene.

[0021] Furthermore, the molecular sieve fixed bed uses MCM-41 silanized molecular sieve with a pore size of 6–8 nm.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. In this invention, during the extraction and production process of industrial naphthalene, the base material is subjected to composite purification treatment by combining a first treatment liquid and a second treatment liquid. In the first treatment liquid, isopropanol, as a solubilizing phenol, can promote the dissolution of sodium phenolate, prevent precipitation and blockage during the treatment process, and improve extraction efficiency. Polysorbate 80, as a surfactant, can enhance the diffusion of phenols from the oil phase to the alkaline solution, further improving extraction efficiency. Combined with the direct alkaline washing treatment of the second treatment liquid, the extraction and treatment of industrial naphthalene can be achieved with high efficiency.

[0024] 2. In this invention, the flash evaporation treatment after extraction can quickly remove residual moisture, avoid component decomposition at high temperatures, further separate impurities with similar boiling points, improve impurity removal efficiency, and ensure the extraction purity of industrial naphthalene. Through molecular sieve adsorption treatment in the refining process, MCM-41 silanized molecular sieve can adsorb small molecule impurities, avoid naphthalene molecules being adsorbed and causing loss, and further improve extraction efficiency. Attached Figure Description

[0025] Figure 1 This is a flowchart of a method for producing industrial naphthalene according to the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0028] Example 1:

[0029] S1: Raw material pretreatment: Coal tar is selected as the raw material. The coal tar is pretreated to obtain coarse material.

[0030] The raw material pretreatment method is as follows: coal tar is fed into a dehydration tank, which is equipped with a steam heating coil and set at 80℃. The tank is left to stand for dehydration for 24 hours. The upper layer of coal tar is pumped out for use. The water content of the upper layer of coal tar is 3%. The lower layer of coal tar is further processed. The method for further processing of the lower layer of coal tar is as follows: the lower layer of coal tar is heated to 120℃ under normal pressure for 10 hours. The resulting product is mixed with the upper layer of coal tar to complete the raw material pretreatment and obtain the coarse material.

[0031] S2: Distillation process, the crude material is distilled to obtain the base material;

[0032] The distillation process is as follows: the crude material is fed into a distillation apparatus, the distillation temperature is 210℃, the distillation process is completed, and the base material is obtained;

[0033] S3: Purification treatment, the base material is subjected to phenol and pyridine removal treatment to obtain naphthalene oil;

[0034] The purification process is as follows: the base material is fed into an extraction tower, the temperature is set at 160℃, the first treatment liquid is added from the top of the tower, followed by the second treatment liquid, the temperature is set at 230℃, and a phenol-free base material is obtained. Then, the phenol-free base material is subjected to pyridine removal treatment. The phenol-free base material and dilute sulfuric acid are added to a reaction vessel, the reaction vessel is set at 50℃, the stirring speed is 80 r / min, and the mixture is stirred at a constant temperature for 40 min. After that, it is allowed to stand for 10 h. After standing and stratification, the surface substances are removed, and the resulting product is added to a thin-film evaporator and flashed at -0.06 MPa and 140℃. The resulting product is then subjected to distillation at a distillation temperature of 240℃ to complete the purification process and obtain naphthalene oil.

[0035] The amount of the first treatment solution used is 5% of the mass of the base material. The preparation method of the first treatment solution is as follows: isopropanol, sodium hydroxide solution, and polysorbate 80 are added to a reaction vessel. The reaction vessel is set at a temperature of 50°C and a stirring speed of 200 r / min. The mixture is stirred at a constant temperature for 20 min to obtain the first treatment solution. The mass concentration of the sodium hydroxide solution is 8%, and the mass ratio of isopropanol, sodium hydroxide solution, and polysorbate 80 is 1:0.2:0.03. The amount of the second treatment solution used is 30% of the mass of the base material. The second treatment solution is sodium hydroxide solution with a mass concentration of 8%.

[0036] S4: Crystallization separation treatment, naphthalene oil is subjected to crystallization separation treatment to obtain crude naphthalene;

[0037] The crystallization separation process is as follows: naphthalene oil is heated to 80°C, then heating is stopped, and the temperature is lowered to 30°C. The resulting product is centrifuged, and solid matter is obtained from the centrifuged product. This completes the crystallization separation process and yields crude naphthalene.

[0038] S5: Refining process, refining crude naphthalene to obtain industrial naphthalene;

[0039] The refining process is as follows: crude naphthalene is heated to 80°C, and the crude naphthalene melts to obtain a liquid product. The liquid product is then adsorbed through a molecular sieve fixed bed. The resulting product is then subjected to vacuum distillation at 230°C to complete the refining process and obtain industrial naphthalene. The molecular sieve fixed bed uses MCM-41 silanized molecular sieve with a pore size of 6 nm.

[0040] Example 2:

[0041] S1: Raw material pretreatment: Coal tar is selected as the raw material. The coal tar is pretreated to obtain coarse material.

[0042] The raw material pretreatment method is as follows: Coal tar is fed into a dehydration tank equipped with a steam heating coil, and the temperature is set at 83℃. The tank is left to stand for dehydration for 30 hours. The upper layer of coal tar is pumped out for later use; the water content of the upper layer is 4%. The lower layer of coal tar undergoes further processing. The method for further processing of the lower layer is as follows: The lower layer of coal tar is heated to 125℃ under normal pressure for 15 hours. The resulting product is mixed with the upper layer of coal tar to complete the raw material pretreatment, yielding coarse material.

[0043] S2: Distillation process, the crude material is distilled to obtain the base material;

[0044] The distillation process is as follows: the crude material is fed into a distillation apparatus, the distillation temperature is 220℃, the distillation process is completed, and the base material is obtained;

[0045] S3: Purification treatment, the base material is subjected to phenol and pyridine removal treatment to obtain naphthalene oil;

[0046] The purification process is as follows: the base material is fed into an extraction tower, the temperature is set at 180℃, the first treatment liquid is added from the top of the tower, followed by the second treatment liquid, the temperature is set at 245℃, and a phenol-free base material is obtained. Then, the phenol-free base material is subjected to pyridine removal treatment. The phenol-free base material and dilute sulfuric acid are added to a reaction vessel, the reaction vessel is set at 55℃, the stirring speed is 100 r / min, and the stirring is carried out at a constant temperature for 50 min. After that, it is allowed to stand for 15 h. After standing and stratification, the surface substances are removed. The obtained product is added to a thin-film evaporator and flashed at -0.07 MPa and 150℃. The obtained product is then subjected to distillation at a distillation temperature of 245℃ to complete the purification process and obtain naphthalene oil.

[0047] The amount of the first treatment solution used is 7% of the mass of the base material. The preparation method of the first treatment solution is as follows: isopropanol, sodium hydroxide solution, and polysorbate 80 are added to the reaction vessel. The reaction vessel is set at a temperature of 55°C and a stirring speed of 300 r / min. The mixture is stirred at a constant temperature for 25 min to obtain the first treatment solution. The mass concentration of the sodium hydroxide solution is 10%, and the mass ratio of isopropanol, sodium hydroxide solution, and polysorbate 80 is 1:0.3:0.04. The amount of the second treatment solution used is 32% of the mass of the base material. The second treatment solution is sodium hydroxide solution with a mass concentration of 10%.

[0048] S4: Crystallization separation treatment, naphthalene oil is subjected to crystallization separation treatment to obtain crude naphthalene;

[0049] The crystallization separation process is as follows: naphthalene oil is heated to 85°C, then heating is stopped, and the temperature is lowered to 35°C. The resulting product is centrifuged, and solid matter is obtained from the centrifuged product to complete the crystallization separation process and obtain crude naphthalene.

[0050] S5: Refining process, refining crude naphthalene to obtain industrial naphthalene;

[0051] The refining process is as follows: crude naphthalene is heated to 85°C. After heating, the crude naphthalene melts to obtain a liquid product. The liquid product is then adsorbed through a molecular sieve fixed bed. The resulting product is then subjected to vacuum distillation at 235°C to complete the refining process and obtain industrial naphthalene. The molecular sieve fixed bed uses MCM-41 silanized molecular sieve with a pore size of 7 nm.

[0052] Example 3:

[0053] S1: Raw material pretreatment: Coal tar is selected as the raw material. The coal tar is pretreated to obtain coarse material.

[0054] The raw material pretreatment method is as follows: Coal tar is fed into a dehydration tank equipped with a steam heating coil, the temperature of which is set at 86℃. The tank is left to stand for dehydration for 36 hours. The upper layer of coal tar is pumped out for later use; its moisture content is 5%. The lower layer of coal tar undergoes further processing. This further processing involves heating the lower layer of coal tar to 130℃ under normal pressure for 20 hours. The resulting product is then mixed with the upper layer of coal tar to complete the raw material pretreatment, yielding coarse material.

[0055] S2: Distillation process, the crude material is distilled to obtain the base material;

[0056] The distillation process is as follows: the crude material is fed into a distillation apparatus, the distillation temperature is 230℃, the distillation process is completed, and the base material is obtained;

[0057] S3: Purification treatment, the base material is subjected to phenol and pyridine removal treatment to obtain naphthalene oil;

[0058] The purification process is as follows: the base material is fed into an extraction tower, the temperature is set at 200℃, the first treatment liquid is added from the top of the tower, followed by the second treatment liquid, the temperature is set at 260℃, and a phenol-free base material is obtained. Then, the phenol-free base material is subjected to pyridine removal treatment. The phenol-free base material and dilute sulfuric acid are added to a reaction vessel, the reaction vessel is set at 60℃, the stirring speed is 120 r / min, and the stirring is carried out at a constant temperature for 60 min. After that, it is allowed to stand for 20 h. After standing and stratification, the surface substances are removed, and the resulting product is added to a thin-film evaporator and flashed at -0.08 MPa and 160℃. The resulting product is then subjected to distillation at a distillation temperature of 250℃ to complete the purification process and obtain naphthalene oil.

[0059] The amount of the first treatment solution used is 10% of the mass of the base material. The preparation method of the first treatment solution is as follows: isopropanol, sodium hydroxide solution, and polysorbate 80 are added to the reaction vessel. The reaction vessel is set at a temperature of 60℃ and a stirring speed of 400 r / min. The mixture is stirred at a constant temperature for 30 min to obtain the first treatment solution. The mass concentration of the sodium hydroxide solution is 12%, and the mass ratio of isopropanol, sodium hydroxide solution, and polysorbate 80 is 1:0.4:0.05. The amount of the second treatment solution used is 35% of the mass of the base material. The second treatment solution is sodium hydroxide solution with a mass concentration of 12%.

[0060] S4: Crystallization separation treatment, naphthalene oil is subjected to crystallization separation treatment to obtain crude naphthalene;

[0061] The crystallization separation process is as follows: naphthalene oil is heated to 90°C, then heating is stopped, and the temperature is lowered to 40°C. The resulting product is centrifuged, and solid matter is obtained from the centrifuged product to complete the crystallization separation process and obtain crude naphthalene.

[0062] S5: Refining process, refining crude naphthalene to obtain industrial naphthalene;

[0063] The refining process is as follows: crude naphthalene is heated to 90°C. After heating, the crude naphthalene melts to obtain a liquid product. The liquid product is then adsorbed through a molecular sieve fixed bed. The resulting product is then subjected to vacuum distillation at 240°C to complete the refining process and obtain industrial naphthalene. The molecular sieve fixed bed uses MCM-41 silanized molecular sieve with a pore size of 8 nm.

[0064] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example did not undergo adsorption treatment during the purification process.

[0065] Comparative Example 2 differs from Example 1 in that flash evaporation was not performed during the purification process in this comparative example.

[0066] Comparative Example 3 differs from Example 1 in that polysorbate 80 was not added when preparing the first treatment solution in this comparative example.

[0067] Comparative Example 4 differs from Example 1 in that it does not contain the first treatment solution.

[0068] Performance testing: The industrial naphthalene prepared in Examples 1, 2, 3, 1, 2, 3, and 4 were subjected to performance testing. The test data are recorded in the table below:

[0069]

[0070]

[0071] It is evident that the purity and yield of the industrial naphthalene prepared in Comparative Examples 1, 2, 3, and 4 are all lower than those in Examples 1, 2, and 3. This indicates that in the extraction and production process of industrial naphthalene, the composite purification treatment of the base material by combining the first and second treatment solutions is effective. In the first treatment solution, isopropanol, as a solubilizing phenol, can promote the dissolution of sodium phenolate, prevent precipitation and blockage during the treatment process, and improve extraction efficiency. Polysorbate 80, as a surfactant, can enhance the diffusion of phenols from the oil phase to the alkaline solution, further improving extraction efficiency. Combined with the direct alkaline washing treatment of the second treatment solution, the extraction of industrial naphthalene can be achieved with high efficiency.

[0072] Flash evaporation after extraction can quickly remove residual moisture, prevent component decomposition at high temperatures, further separate impurities with similar boiling points, improve impurity removal efficiency, and ensure the extraction purity of industrial naphthalene. Molecular sieve adsorption treatment in the refining process allows MCM-41 silanized molecular sieves to adsorb small molecule impurities, preventing naphthalene molecules from being adsorbed and causing loss, and further improving extraction efficiency.

[0073] By comparing and analyzing the relevant data in the table, it can be seen that the industrial naphthalene prepared by the method of this invention not only has good purity but also excellent yield. This indicates that the industrial naphthalene production method provided by this invention has a broader market prospect and is more suitable for widespread application.

[0074] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0075] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing industrial naphthalene, characterized in that: Includes the following steps: S1: Raw material pretreatment: Coal tar is selected as the raw material. The coal tar is pretreated to obtain coarse material. S2: Distillation process, the crude material is distilled to obtain the base material; S3: Purification treatment, the base material is subjected to phenol and pyridine removal treatment to obtain naphthalene oil; S4: Crystallization separation treatment, naphthalene oil is subjected to crystallization separation treatment to obtain crude naphthalene; S5: Refining process, which refines crude naphthalene to obtain industrial naphthalene.

2. The method for producing industrial naphthalene according to claim 1, characterized in that, The method for pre-treating the raw materials is as follows: coal tar is fed into a dehydration tank, which is equipped with a steam heating coil and the temperature is set at 80-86℃. The coal tar is left to stand for dehydration for 24-36 hours. The upper layer of coal tar is pumped out for use. The water content of the upper layer of coal tar is 3-5%. The lower layer of coal tar is further processed.

3. The method for producing industrial naphthalene according to claim 2, characterized in that, The method for further processing of the lower coal tar is as follows: the lower coal tar is heated to 120-130℃ under normal pressure for 10-20 hours, and the resulting product is mixed with the upper coal tar to complete the raw material pretreatment and obtain the coarse material.

4. The method for producing industrial naphthalene according to claim 1, characterized in that, The distillation process is as follows: the crude material is fed into a distillation apparatus, the distillation temperature is 210-230℃, the distillation process is completed, and the base material is obtained.

5. The method for producing industrial naphthalene according to claim 1, characterized in that, The purification process is as follows: the base material is fed into an extraction tower, the temperature is set at 160-200℃, the first treatment liquid is added from the top of the tower, followed by the second treatment liquid, the temperature is set at 230-260℃, resulting in a phenol-free base material. The phenol-free base material is then subjected to pyridine removal treatment. The phenol-free base material and dilute sulfuric acid are added to a reaction vessel, the reaction vessel temperature is set at 50-60℃, the stirring speed is 80-120 r / min, and the mixture is stirred at a constant temperature for 40-60 min. Afterwards, it is allowed to stand for 10-20 h. After the sedimentation, surface substances are removed, and the resulting product is added to a thin-film evaporator and flash-evaporated at -0.06--0.08 MPa and 140-160℃. The resulting product is then subjected to distillation at a temperature of 240-250℃ to complete the purification process, yielding naphthalene oil.

6. The method for producing industrial naphthalene according to claim 5, characterized in that, The amount of the first treatment liquid used is 5-10% of the mass of the base material. The preparation method of the first treatment liquid is as follows: isopropanol, sodium hydroxide solution and polysorbate 80 are added to the reaction vessel. The reaction vessel is set at a temperature of 50-60℃ and a stirring speed of 200-400 r / min. The mixture is stirred at a constant temperature for 20-30 min to obtain the first treatment liquid. The mass concentration of sodium hydroxide solution is 8-12%, and the mass ratio of isopropanol, sodium hydroxide solution and polysorbate 80 is 1:(0.2-0.4):(0.03-0.05).

7. The method for producing industrial naphthalene according to claim 5, characterized in that, The amount of the second treatment solution used is 30-35% of the mass of the base material. The second treatment solution is a sodium hydroxide solution with a mass concentration of 8-12%.

8. The method for producing industrial naphthalene according to claim 1, characterized in that, The crystallization separation process is as follows: naphthalene oil is heated to 80-90°C, then heating is stopped, and the temperature is lowered to 30-40°C. The resulting product is centrifuged, and solid matter is obtained from the centrifuged product. The crystallization separation process is completed to obtain crude naphthalene.

9. The method for producing industrial naphthalene according to claim 1, characterized in that, The refining process is as follows: crude naphthalene is heated to a temperature of 80-90°C. After heating, the crude naphthalene melts to obtain a liquid product. The liquid product is then adsorbed through a molecular sieve fixed bed. The resulting product is then subjected to vacuum distillation at a temperature of 230-240°C to complete the refining process and obtain industrial naphthalene.

10. The method for producing industrial naphthalene according to claim 9, characterized in that, The molecular sieve fixed bed uses MCM-41 silanized molecular sieve with a pore size of 6-8 nm.

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