Method for extracting indane and co-producing refined naphthalene from mixture of naphthalene and indane

Abstract

According to the method for extracting the indane and co-producing the refined naphthalene from the mixture of the naphthalene and the indane, the indane and the refined naphthalene can be synchronously obtained from the mixture of the naphthalene and the indane, and the obtained product has better purity and yield. The method comprises the following steps: 1) mixing the mixture of naphthalene and indane with ethylene glycol, and crystallizing the obtained mixed solution to obtain a crystalline solution; carrying out solid-liquid separation on the crystallization liquid to obtain an impurity-removed mixture of naphthalene and thioindene; 2) heating and melting the impurity-removed mixture of naphthalene and indane to obtain molten liquid, carrying out azeotropic distillation on the molten liquid and ethylene glycol, and separating to obtain an indane material and a mixed material of naphthalene and ethylene glycol; and (3) mixing and washing the mixed material of naphthalene and ethylene glycol with water, carrying out phase separation on the obtained mixed solution, separating out a light-phase component rich in naphthalene, and drying the light-phase component to obtain a refined naphthalene product.

Description

Technical Field

[0001] The invention relates to a separation technology of naphthalene and thionaphthene in a mixture of naphthalene and thionaphthene, and in particular to a method for extracting thionaphthene from the mixture of naphthalene and thionaphthene and co-producing refined naphthalene. Background Art

[0002] Thianaphthene is also known as benzothiophene, with a molecular weight of 134.20, a melting point of 31.3°C, a boiling point of 219.9°C, and is insoluble in water, but soluble in organic solvents such as ethanol, ether, acetone, and benzene. Thianaphthene is an important fine chemical raw material, widely used in the fields of medicine, pesticides, optical materials, and dyes, and is mainly used in the preparation of fungicides, insecticides, herbicides, housefly killers, plant growth hormone raw materials, synthetic dye raw materials, and other intermediates of thiaphthene derivatives.

[0003] Refined naphthalene, molecular weight 128.16, melting point 80.1℃, boiling point 217.9℃, insoluble in water, soluble in benzene, ether, anhydrous ethanol and other organic substances. Refined naphthalene is widely used in the preparation of fine chemical products such as water reducer, phthalic anhydride, naphthoquinone, naphthol, dye diffuser, dye intermediates, etc.

[0004] Thianaphthene resources in tar are mainly concentrated in the naphthalene fraction after tar distillation. The naphthalene residual oil after the industrial naphthalene melt crystallization method is used to produce refined naphthalene contains 10-15% thionaphthene. Due to the difficulty in separation, this part of naphthalene residual oil is generally used as fuel oil, wasting precious naphthalene and thionaphthene resources.

[0005] Since thionaphthene and naphthalene have similar boiling points, it is very difficult to separate and purify thionaphthene using ordinary distillation methods.

[0006] Chinese patent application CN101747317A discloses a method for enriching thionaphthene from a mixture containing thionaphthene and naphthalene, which uses glycol as a solvent to enrich thionaphthene in the glycol, and recovers the glycol to obtain an enriched thionaphthene fraction. In the embodiment, the thionaphthene content of the enriched thionaphthene fraction does not exceed 30%, and a high-purity thionaphthene product cannot be obtained.

[0007] Chinese patent application CN114315792A discloses a method for enriching thionaphthene from a mixture containing thionaphthene and naphthalene by a solvent crystallization coupled extraction and distillation method. The method uses triethylene glycol, tetraethylene glycol, MDEA and other solvents to extract thionaphthene from the mixture of thionaphthene and naphthalene, and then extracts and distills to obtain a thionaphthene fraction. In the embodiment, the maximum content of thionaphthene in the extraction and distillation fraction does not exceed 50%, and the purity of thionaphthene is still not high.

[0008] CN108558591B discloses a naphthalene residual oil separation and recovery method, which removes light components through a light component removal tower, sends the bottom material of the light component removal tower to a naphthalene removal tower, separates naphthalene and thionaphthene through the naphthalene removal tower, obtains naphthalene components at the top of the naphthalene removal tower, sends the bottom material to a benzothiophene tower, and the top component of the benzothiophene tower goes to a static crystallizer, and obtains thionaphthene products through crystallization in the static crystallizer. In this method, naphthalene and thionaphthene are separated by ordinary distillation of the naphthalene removal tower, which has high energy consumption, and the naphthalene content of the naphthalene removal tower top discharge material is only 85.6%; the benzothiophene tower bottom discharge material is a byproduct, and its benzothiophene content is as high as 29.2%, and the thionaphthene recovery rate is low, only reaching 70%.

[0009] CN115504960A discloses a method for extracting thionaphthene from naphthalene residual oil, which uses naphthalene residual oil after preparing refined naphthalene by melting and crystallizing industrial naphthalene as raw material, firstly adopts a two-solvent extraction method, utilizes the different distribution coefficients of naphthalene and thionaphthene in solvent ether and ethanolamine, naphthalene is dissolved in ether, thionaphthene is dissolved in ethanolamine, and preliminary separation of naphthalene and thionaphthene is achieved; then, utilizing the azeotropic property of naphthalene and ethanolamine, intermittent azeotropic distillation is performed on the ethanolamine solution of thionaphthene, ethanolamine and a small amount of naphthalene in the solution are first azeotropically distilled out, and then a thionaphthene fraction is obtained, and the thionaphthene fraction is washed with ether to obtain a 98% thionaphthene product. This method does not provide a method for separating naphthalene and ethanolamine azeotropes, and the intermittent azeotropic distillation separation to obtain the thionaphthene fraction cannot achieve large-scale continuous production, and the embodiment shows that the thionaphthene recovery rate is only 75.3%. Summary of the invention

[0010] The invention provides a method for extracting thionaphthene from a mixture of naphthalene and thionaphthene and co-producing refined naphthalene. The method of the invention can synchronously obtain thionaphthene and refined naphthalene products from the mixture of naphthalene and thionaphthene, and the obtained products have good purity and yield.

[0011] To achieve the purpose, the present invention provides the following technical solutions:

[0012] The present invention provides a method for extracting thionaphthene from a mixture of naphthalene and thionaphthene and co-producing refined naphthalene, the method comprising the following steps:

[0013] 1) mixing the mixture of naphthalene and thiophanate with ethylene glycol, crystallizing the obtained mixed solution to obtain a crystallization liquid; subjecting the crystallization liquid to solid-liquid separation to obtain a mixture of naphthalene and thiophanate from which impurities are removed;

[0014] 2) heating and melting the impurity-removed mixture of naphthalene and thionaphthene to obtain a melt, and subjecting the melt to azeotropic distillation with ethylene glycol to separate and obtain a thionaphthene material and a mixture of naphthalene and ethylene glycol;

[0015] 3) the mixture of the naphthalene and ethylene glycol is mixed and washed with water, the resulting mixed solution is phase-splitting to separate a light phase component rich in naphthalene, and the light phase component is dried to obtain a refined naphthalene product.

[0016] In the present invention, ethylene glycol is first used as a solvent to mix with a mixture of naphthalene and thionaphthene, and then crystallization is performed, which is beneficial to removing impurities (such as dimethylphenol, etc.) carried out therein; and then the crystallized product is heated and melted, and then ethylene glycol is used for azeotropic distillation, which can more efficiently and thoroughly separate thionaphthene and naphthalene; subsequently, the thionaphthene product can be obtained by simple cooling, and the refined naphthalene product can be obtained by washing with water, phase separation and drying.

[0017] In some embodiments, in step 1), the mixture of naphthalene and thionaphthene can be industrial naphthalene, or a naphthalene fraction after tar distillation separation, or naphthalene residual oil after melt crystallization of the industrial naphthalene or the naphthalene fraction. In some specific embodiments, the mixture of naphthalene and thionaphthene contains 10-15wt% of thionaphthene, 80-85wt% of naphthalene, and 3-5t% of impurities such as dimethylphenol.

[0018] In a preferred embodiment, in step 1), the mass ratio of the ethylene glycol to the mixture of naphthalene and thionaphthene is 1 to 4:1, preferably 1.5 to 3:1 (e.g., 1.5:1, 2:1, 2.5:1, 3:1, etc.). The preferred mass ratio is used for mixing and then cooling and crystallizing to facilitate the removal of impurities. If the mass ratio is too low, some impurities will precipitate during the crystallization process, which may not be conducive to the more complete removal of impurities. If the mass ratio is too high, the cooling and crystallization refrigeration energy consumption is high, the loss of the target products thionaphthene and naphthalene increases during the crystallization process, and the energy consumption of solvent recovery is also high.

[0019] In a preferred embodiment, in step 1), the crystallization temperature for crystallization is 15-35°C, preferably 20-30°C (for example, 20, 25, 30°C, etc.); the crystallization time is 30-50min, preferably 35-45min (for example, 35, 40, 45min, etc.). Preferably, in step 1), the temperature is lowered to the crystallization temperature at a cooling rate of 1-3°C / min (for example, 1°C / min, 2°C / min, 3°C / min, etc.) for crystallization. The preferred cooling crystallization conditions are used to facilitate the full crystallization and precipitation of the target products thionaphthene and naphthalene, as well as the removal of impurities, and to facilitate the acquisition of thionaphthene and refined naphthalene products with high purity and product recovery rate.

[0020] In some embodiments, the solid-liquid separation in step 1) can be performed by filtration, for example, the crystallization liquid is sent to a filter for solid-liquid separation, and the obtained filter cake (ie, the solid phase component) is a mixture of naphthalene and thionaphthene from which impurities have been removed.

[0021] In some embodiments, in step 2), the heating and melting temperature is 80-85°C, such as 80, 84, 85°C, etc.

[0022] The inventors have found that ethylene glycol and naphthalene can form a minimum azeotrope, and naphthalene and thionaphthene can be effectively separated by azeotropic distillation. In a preferred embodiment, in step 2), the mass ratio of ethylene glycol used for the azeotropic distillation to the melt is 0.53 to 0.62:1, preferably 0.55 to 0.62:1, more preferably 0.55 to 0.60:1 (for example, 0.55:1, 0.56:1, 0.57:1, 0.58:1, 0.59:1, 0.60:1, etc.). The preferred mass ratio is used to facilitate the discharge of ethylene glycol and naphthalene at the top of the tower in the form of an azeotropic composition, and the tower bottom can obtain a high-purity thionaphthene product without causing high energy consumption. If the mass ratio is too low, the amount of residual naphthalene in the bottom product may increase, resulting in a decrease in the purity of the bottom thionaphthene product. If the mass ratio is too high, although the bottom product can obtain a high-purity thionaphthene product, energy consumption is increased because ethylene glycol also needs to be distilled out of the bottom product.

[0023] In a preferred embodiment, in step 2), the conditions of the azeotropic distillation include: the top pressure of the azeotropic distillation tower is 5 to 15 kPa, the top temperature is 110 to 120° C., and the reflux ratio is 5 to 10. The preferred azeotropic distillation conditions are beneficial to the efficient separation of naphthalene and thionaphthene, and to the acquisition of high-purity, high-recovery refined naphthalene products and thionaphthene products.

[0024] In a preferred embodiment, in step 3), the mass ratio of water used for the mixed washing to the mixture of naphthalene and ethylene glycol is 0.8-1.5:1, for example, 0.8:1, 1.0:1, 1.2:1, 1.4:1, 1.5:1, etc.; preferably, the temperature of the water used for the mixed washing is 70-80°C, for example, 70°C, 72°C, 75°C, 77°C, 80°C, etc. In a preferred embodiment, the phase separation is carried out at a temperature of 80-85°C (for example, 80°C, 82°C, 84°C, 85°C, etc.). Adopting preferred water washing and phase-splitting conditions, it is beneficial to further improve the recovery rate of naphthalene and the recovery rate of ethylene glycol entrainer; if the quality ratio is relatively low, the aqueous phase may be difficult to fully dissolve and recycle the ethylene glycol entrainer, and if the quality ratio is relatively high, more naphthalene will be dissolved in the aqueous phase, resulting in a reduction in the recovery rate of naphthalene; and when the phase-splitting temperature is higher, the evaporation loss of naphthalene will increase, and when the temperature is relatively low, naphthalene may crystallize out. In step 3), a light phase component and a heavy phase component are obtained through phase-splitting, wherein the light phase component is a component rich in naphthalene, and the heavy phase component is mainly a mixture of water and entrainer (ethylene glycol).

[0025] In some embodiments, in step 2), the thionaphthene material is cooled to obtain a thionaphthene product.

[0026] In some better embodiments, in step 1), the mass ratio of the ethylene glycol to the mixture of naphthalene and thionaphthene is 1.5 to 3:1, the crystal growing temperature of the crystal growing is 20 to 30°C, and the crystal growing time is 35 to 45 minutes; in step 2), the mass ratio of the ethylene glycol used for the azeotropic distillation to the melt is 0.55 to 0.60:1. The preferred method is used to extract thionaphthene from the mixture of naphthalene and thionaphthene and co-produce refined naphthalene, which can better balance the purity and yield of refined naphthalene products and thionaphthene products.

[0027] The technical solution provided by the present invention has the following beneficial effects:

[0028] (1) The method of the present invention is adopted, wherein the mixture of naphthalene and thionaphthene is first mixed with ethylene glycol solvent for crystallization and impurity removal, the impurity-removed mixture of naphthalene and thionaphthene is heated and melted, and then subjected to azeotropic distillation with ethylene glycol to separate the thionaphthene material and the mixture of naphthalene and ethylene glycol, wherein the mixture of naphthalene and ethylene glycol is washed with water, phase-separated, and then simply dried to obtain a refined naphthalene product; the method of the present invention can be used to synchronously separate the thionaphthene product and the refined naphthalene product from the mixture of naphthalene and thionaphthene, and has good yield and purity. In a preferred embodiment, by further optimizing the process conditions, the yield and purity of the thionaphthene product and refined naphthalene can be further improved.

[0029] (2) The method of the present invention has the characteristics of simple process flow, required operating conditions and temperature, good product quality, etc., and the process operation and control are simple and easy. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0031] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0032] Thianaphthene purity detection method: quantitative analysis by GC-MS.

[0033] Purity detection method of refined naphthalene: quantitative analysis by GC-MS.

[0034] The calculation formula of the yield of thionaphthene is: the mass of thionaphthene in the refined thionaphthene product / the mass of thionaphthene contained in the crystallization residual oil*100%;

[0035] The calculation formula of refined naphthalene yield is: the mass of naphthalene contained in the refined naphthalene product / the mass of naphthalene contained in the crystallization residual oil*100%.

[0036] Example 1

[0037] The mixture of naphthalene and thiophanate used in this example is the residual oil obtained by crystallization after extracting refined naphthalene from the naphthalene fraction obtained from a tar processing device through melt crystallization. The raw material contains 12.68wt% of thiophanate, 83.45wt% of naphthalene, and 3.87wt% of impurities such as dimethylphenol.

[0038] The following steps are used to extract thionaphthene from the above-mentioned crystallization residual oil and co-produce refined naphthalene:

[0039] 1) mixing ethylene glycol and crystallization residual oil in a mass ratio of 1.9:1 to obtain a mixed solution at 73° C.; crystallizing the obtained mixed solution in a crystallizer to obtain a crystal solution; wherein the crystallization conditions include: cooling at a rate of 2° C. / min, cooling to 25° C. for crystal growth, and a crystal growth time of 40 min;

[0040] The crystal liquid is filtered in a filter to obtain a filter cake, which is a mixture of naphthalene and thionaphthene from which impurities have been removed. The main components of the filter cake are 57.45 wt % of naphthalene, 8.73 wt % of thionaphthene and 33.82 wt % of ethylene glycol.

[0041] 2) heating the filter cake at 82° C. to melt to obtain a melt, and performing azeotropic distillation on the melt and ethylene glycol in an azeotropic distillation tower, wherein the mass ratio of ethylene glycol to the melt is 0.55:1, and the operating conditions of the azeotropic distillation tower include: a theoretical plate number of 120, a tower top pressure of 10 kPa, a tower top temperature of 115° C., a tower bottom temperature of 156° C., a tower bottom pressure of 18 kPa, and a reflux ratio of 7;

[0042] A thionaphthene material (bottom material) and a mixture of naphthalene and ethylene glycol (top material) are obtained by azeotropic distillation; the thionaphthene material is cooled to 40° C. to obtain a thionaphthene product.

[0043] 3) the mixture of naphthalene and ethylene glycol obtained in step 2) is mixed and washed with 75° C. water in a mixer, wherein the mass ratio of the amount of water to the mixture of naphthalene and ethylene glycol is 1:1;

[0044] The obtained mixed liquid is sent to a phase separator for phase separation at 82°C to separate a light phase component rich in naphthalene. The light phase component is dried in a dryer at a temperature of 95°C and a pressure of 40kPa. After drying and removing trace amounts of water, a refined naphthalene product is obtained.

[0045] Experimental results: a thionaphthene product with a purity of 99.1% and a refined naphthalene product with a purity of 99.4% were obtained. The yield of thionaphthene was 93.1%, and the yield of naphthalene was 95.8%.

[0046] Example 2

[0047] The process is carried out in accordance with Example 1, except that in step 1), the mass ratio of ethylene glycol to the crystallized residual oil is 1:1.

[0048] Experimental results: the purity of the obtained thionaphthene product was 93.9%, and the yield was 92.3%; the purity of the obtained refined naphthalene product was 98.1%, and the yield was 95.3%.

[0049] Example 3

[0050] The process is carried out in accordance with Example 1, except that in step 1), the mass ratio of ethylene glycol to the crystallized residual oil is 4:1.

[0051] Experimental results: the purity of the obtained thionaphthene product was 98.9%, and the yield was 92.7%; the purity of the obtained refined naphthalene product was 99.1%, and the yield was 92.5%.

[0052] Example 4

[0053] The process is carried out in accordance with Example 1, except that in step 1), the crystal growing temperature is 15°C.

[0054] Experimental results: the purity of the obtained thionaphthene product was 98.5%, and the yield was 92.2%; the purity of the obtained refined naphthalene product was 99.1%, and the yield was 95.9%.

[0055] Example 5

[0056] The process is carried out in accordance with Example 1, except that in step 1), the crystal growing temperature is 35°C.

[0057] Experimental results: the purity of the obtained thionaphthene product was 98.7%, and the yield was 91.9%; the purity of the obtained refined naphthalene product was 98.9%, and the yield was 91.6%.

[0058] Example 6

[0059] The process is carried out in accordance with Example 1, except that in step 1), the crystal growing time is 30 min.

[0060] Experimental results: the purity of the obtained thionaphthene product was 98.9%, and the yield was 90.1%; the purity of the obtained refined naphthalene product was 99.2%, and the yield was 91.6%.

[0061] Example 7

[0062] The process is carried out in accordance with Example 1, except that in step 1), the crystal growing time is 50 min.

[0063] Experimental results: the purity of the obtained thionaphthene product was 98.7%, and the yield was 91.3%; the purity of the obtained refined naphthalene product was 98.8%, and the yield was 95.5%.

[0064] Example 8

[0065] The process is carried out in accordance with Example 1, except that in step 2), the mass ratio of the amount of the azeotropic agent ethylene glycol to the melt is 0.53:1.

[0066] Experimental results: the purity of the obtained thionaphthene product was 83.2%, and the yield was 91.6%; the purity of the obtained refined naphthalene product was 99.3%, and the yield was 87.5%.

[0067] Example 9

[0068] The process is carried out in accordance with Example 1, except that in step 3), the mass ratio of the amount of the azeotropic agent ethylene glycol to the melt is 0.62:1.

[0069] Experimental results: the purity of the obtained thionaphthene product was 99.0%, and the yield was 92.1%; the purity of the obtained refined naphthalene product was 99.1%, and the yield was 95.2%.

[0070] Table 1 Summary of experimental results

[0071]

[0072] It can be seen from the above experimental results that the method of the present invention can be used to simultaneously separate the thionaphthene product and the refined naphthalene product from the crystallization residual oil, while achieving good product yield and purity.

[0073] From the comparison between Examples 2 and 3 and Example 1, it can be seen that in Examples 2 and 3, the mass ratio of ethylene glycol to the crystallization residual oil is not controlled within the preferred range of 1.5 to 3:1. Compared with Example 1, the yield and purity of the thionaphthene product, as well as the yield and purity of the refined naphthalene product are inferior to those of Example 1.

[0074] Comparison between Examples 4 and 5 and Example 1 shows that Example 1 controls the crystal growing temperature within the preferred range of 20 to 30° C., which can better balance the acquisition of high purity and yield of thionaphthene products and refined naphthalene products.

[0075] Comparison between Examples 6 and 7 and Example 1 shows that Example 1 controls the crystal growing time within the preferred range of 35 to 45 minutes, which can better obtain thiophanate products and refined naphthalene products with both high purity and yield.

[0076] From the comparison between Example 8 and Examples 1 and 9, it can be seen that Example 8 does not adopt the preferred mass ratio of the amount of the entrainer to the melt of 0.55 to 0.62:1, and the purity of the obtained thionaphthene product decreases significantly, and the yield of the refined naphthalene product also decreases significantly. From the comparison between Examples 1 and 9, it can be seen that in Example 1, when other conditions are basically the same, the mass ratio of the amount of the entrainer to the melt is controlled within the more preferred range of 0.55 to 0.60:1, which can further improve the yield and purity of thionaphthene and refined naphthalene products.

[0077] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for extracting thionaphthene from a mixture of naphthalene and thionaphthene and co-producing refined naphthalene, characterized in that: The method comprises the following steps: 1) mixing the mixture of naphthalene and thiophanate with ethylene glycol, and crystallizing the obtained mixed solution to obtain a crystallization liquid; performing solid-liquid separation on the crystallization liquid to obtain a mixture of naphthalene and thiophanate that has been removed from impurities; 2) heating and melting the impurity-removed mixture of naphthalene and thionaphthene to obtain a melt, and subjecting the melt to azeotropic distillation with ethylene glycol to separate and obtain a thionaphthene material and a mixture of naphthalene and ethylene glycol; 3) the mixture of the naphthalene and ethylene glycol is mixed and washed with water, the resulting mixed solution is phase-splitting to separate a light phase component rich in naphthalene, and the light phase component is dried to obtain a refined naphthalene product.

2. The method according to claim 1, characterized in that In step 1), the mixture of naphthalene and thionaphthene is industrial naphthalene, or a naphthalene fraction separated by tar distillation, or naphthalene residual oil after melt crystallization of the industrial naphthalene or the naphthalene fraction.

3. The method according to claim 1, characterized in that In step 1), the mass ratio of the ethylene glycol to the mixture of naphthalene and thionaphthene is 1 to 4:1, preferably 1.5 to 3:

1.

4. The method according to claim 3, characterized in that In step 1), the crystal growth temperature for the crystal growth is 15-35° C., preferably 20-30° C.; the crystal growth time is 30-50 min, preferably 35-45 min; Preferably, in step 1), the temperature is lowered to the crystal growing temperature at a cooling rate of 1 to 3°C / min for crystal growing.

5. The method according to any one of claims 1 to 4, characterized in that: In step 2), the heating and melting temperature is 80-85°C.

6. The method according to any one of claims 1 to 4, characterized in that: In step 2), the mass ratio of ethylene glycol used for the azeotropic distillation to the melt is 0.53 to 0.62:1, preferably 0.55 to 0.62:1, and more preferably 0.55 to 0.60:

1.

7. The method according to claim 6, characterized in that In step 2), the conditions of the azeotropic distillation include: the top pressure of the azeotropic distillation tower is 5-15 kPa, the top temperature is 110-120° C., and the reflux ratio is 5-10.

8. The method according to any one of claims 1 to 4, characterized in that: In step 3), the mass ratio of water used for the mixed washing to the mixture of naphthalene and ethylene glycol is 0.8-1.5:1; preferably, the temperature of the water used for the mixed washing is 70-80°C.

9. The method according to claim 8, characterized in that The phase separation is carried out at a temperature of 80-85°C.

10. The method according to any one of claims 1 to 4, characterized in that: In step 2), the thionaphthene material is cooled to obtain a thionaphthene product.

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