A method for separating a tertiary dodecyl mercaptan reaction solution

Abstract

The application relates to the chemical technology field and discloses a kind of tert-dodecyl mercaptan reaction liquid separation methods.The separation method is by using specific sulfonyl substance as extractant, with the tert-dodecyl mercaptan reaction liquid to be separated together in extractive rectification column to carry out extractive rectification, so that high-purity tetramer propylene can be obtained at the top of the extractive rectification column;The extractive rectification column kettle liquid is rectified and separated, and high-purity tert-dodecyl mercaptan can be obtained.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a method for separating a tert-dodecyl mercaptan reaction liquid. Background Art

[0002] Tert-dodecyl mercaptan (TDDM) is an important chemical intermediate used as a molecular weight regulator for polymers such as synthetic resins and synthetic rubber. It can be produced using tetrapropylene and hydrogen sulfide as raw materials. The reaction typically achieves a conversion rate of 80-90% and a selectivity exceeding 99%. Therefore, the resulting tert-dodecyl mercaptan reaction solution is a mixture of tetrapropylene and tert-dodecyl mercaptan.

[0003] The reaction raw material, tetrapropylene, is a mixture of C10-C14 olefins with a boiling range of 162-237°C. The product, tert-dodecyl mercaptan, is also a mixture with a boiling range of 227-248°C. Because the high-boiling components in tetrapropylene overlap with the low-boiling components in tert-dodecyl mercaptan, they are difficult to separate using conventional distillation processes. Summary of the Invention

[0004] In view of this, the present application provides a method for separating a tert-dodecyl mercaptan reaction solution to solve the problem that tetrapropylene and tert-dodecyl mercaptan are difficult to separate in the existing process.

[0005] The present application provides a method for separating a tert-dodecyl mercaptan reaction solution, wherein the tert-dodecyl mercaptan reaction solution comprises tetrapropylene and tert-dodecyl mercaptan; the separation method comprises the following steps:

[0006] S1. In the presence of an extractant, the tert-dodecyl mercaptan reaction solution is subjected to extractive distillation in an extractive distillation tower, and the extractive distillation tower bottom liquid and tetrapropylene are collected respectively;

[0007] The extractant is at least one of sulfolane, phenethyl sulfone, and diphenyl sulfone;

[0008] S2. Send the extractive distillation tower bottom liquid obtained in S1 into a recovery distillation tower for separation to obtain tert-dodecyl mercaptan.

[0009] In some optional embodiments, the mass flow ratio of the extractant to the tert-dodecyl mercaptan reaction solution is 1-5.

[0010] In some optional embodiments, the extractive distillation tower has 20-30 plates.

[0011] In some optional embodiments, the reflux ratio of the extractive distillation tower is 1-5.

[0012] In some optional embodiments, the reflux ratio of the extractive distillation tower is 2-3.

[0013] In some optional embodiments, the mass flow rate of the extractant is 2 g / min-10 g / min.

[0014] In some optional embodiments, the mass flow rate of the tert-dodecyl mercaptan reaction solution is 2 g / min.

[0015] In some optional embodiments, the operating pressure of the extractive distillation tower is 1 kPa-5 kPa absolute pressure.

[0016] In some optional embodiments, the operating pressure of the extractive distillation tower is 2 kPa-3 kPa absolute pressure.

[0017] In some optional embodiments, the recovery distillation tower has 10-20 plates.

[0018] In some optional embodiments, the reflux ratio of the recovery distillation tower is 0.2-3.

[0019] In some optional embodiments, the reflux ratio of the recovery distillation tower is 0.5-2.

[0020] In some optional embodiments, the operating pressure of the recovery distillation tower is 0.1 kPa-3 kPa absolute pressure.

[0021] In some optional embodiments, the operating pressure of the recovery distillation tower is 0.5 kPa-2 kPa absolute pressure.

[0022] In some optional embodiments, the bottom liquid of the recovery distillation tower obtained in S2 is recycled to S1 as an extractant.

[0023] In some optional embodiments, the tert-dodecyl mercaptan reaction solution includes 10 wt%-20 wt% of tetrapropylene and 80 wt%-90 wt% of tert-dodecyl mercaptan.

[0024] The technical solution of this application has the following advantages:

[0025] The present application provides a method for separating a tert-dodecyl mercaptan reaction liquid. A specific sulfone is used as an extractant, and extractive distillation is performed in an extractive distillation column along with the tert-dodecyl mercaptan reaction liquid to be separated. This allows high-purity tetrapropylene to be obtained at the top of the extractive distillation column. The bottom liquid of the extractive distillation column is then subjected to distillation and separation to obtain high-purity tert-dodecyl mercaptan. This separation method can significantly improve the separation purity of tetrapropylene and tert-dodecyl mercaptan, resolving the difficulty in separating tetrapropylene and tert-dodecyl mercaptan in existing processes.

[0026] Additional aspects and advantages of the embodiments of the present application will be described and shown in part in the subsequent description, or explained through the implementation of the embodiments of the present application. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusions.

[0029] In the description of the embodiments of the present application, “multiple” means more than two, unless otherwise clearly and specifically defined.

[0030] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0033] In the laboratory, 80 plates are commonly used to distill the tert-dodecyl mercaptan reaction solution at a reflux ratio of 10. However, the purity of the separated polypropylene tetramer is only 90%, and the purity of tert-dodecyl mercaptan is only 98.5%. Furthermore, using these separation conditions results in high energy consumption due to the high reflux ratio, and the large number of separation plates leads to large equipment investment.

[0034] In order to solve the problems existing in the above-mentioned related art, according to an embodiment of the present application, a method for separating a tert-dodecyl mercaptan reaction solution is provided, wherein the tert-dodecyl mercaptan reaction solution comprises tetrapropylene and tert-dodecyl mercaptan; the separation method comprises the following steps:

[0035] S1. In the presence of an extractant, the tert-dodecyl mercaptan reaction solution is subjected to extractive distillation in an extractive distillation tower, and the extractive distillation tower bottom liquid and tetrapropylene are collected respectively;

[0036] The extractant is at least one of sulfolane, phenethyl sulfone, and diphenyl sulfone;

[0037] S2. Send the extractive distillation tower bottom liquid obtained in S1 into a recovery distillation tower for separation to obtain tert-dodecyl mercaptan.

[0038] The present application provides a method for separating a tert-dodecyl mercaptan reaction liquid. A specific sulfone is used as an extractant, and extractive distillation is performed in an extractive distillation column along with the tert-dodecyl mercaptan reaction liquid to be separated. This allows high-purity tetrapropylene to be obtained at the top of the extractive distillation column. The bottom liquid of the extractive distillation column is then subjected to distillation and separation to obtain high-purity tert-dodecyl mercaptan. This separation method can significantly improve the separation purity of tetrapropylene and tert-dodecyl mercaptan, resolving the difficulty in separating tetrapropylene and tert-dodecyl mercaptan in existing processes.

[0039] It is worth noting that the boiling points of sulfolane, phenethyl sulfone and diphenyl sulfone are 285°C, 313°C and 379°C respectively, which are significantly higher than the boiling ranges of tetrapropylene and tert-dodecyl mercaptan. In addition, sulfolane, phenethyl sulfone and diphenyl sulfone will not form azeotropic solutions with tetrapropylene and tert-dodecyl mercaptan. At the same time, sulfolane, phenethyl sulfone and diphenyl sulfone have good mutual solubility with tetrapropylene and tert-dodecyl mercaptan. Therefore, the present application adopts sulfolane, phenethyl sulfone and diphenyl sulfone as extractants, and utilizes the strong interaction between the sulfone structure in the extractant and the mercaptan. The method can significantly change the relative volatility of the tert-dodecyl mercaptan reaction liquid to be separated, thereby separating the tetrapropylene with a relatively low boiling point from the tert-dodecyl mercaptan and the extractant with relatively high boiling points, obtaining high-purity tetrapropylene (purity of more than 99.5%) at the top of the extractive distillation tower, and obtaining a mixture of tert-dodecyl mercaptan and the extractant in the bottom of the extractive distillation tower. The bottom liquid of the extractive distillation tower is then subjected to distillation separation to obtain high-purity tert-dodecyl mercaptan (purity of more than 99.5%).

[0040] The present application has found that when the mass flow ratio of the extractant to the tert-dodecyl mercaptan reaction solution is 1-5, efficient separation of tert-dodecyl mercaptan and tetrapropylene can be achieved. If the mass flow ratio of the extractant to the tert-dodecyl mercaptan reaction solution is too small, the separation effect of tert-dodecyl mercaptan and tetrapropylene will be poor, and the product purity will be unqualified. On the contrary, if the ratio is too large, the amount of extractant used will be too large, and the separation cost will be too high. As an example, the mass flow ratio of the extractant to the tert-dodecyl mercaptan reaction solution can be, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc., or within the range consisting of any two of the above values. In some embodiments, the mass flow rate of the extractant is 2 g / min-10 g / min. As an example, it can be 2 g / min, 3 g / min, 4 g / min, 5 g / min, 6 g / min, 7 g / min, 8 g / min, 9 g / min, 10 g / min, etc. or within the range of any two of the above values; the mass flow rate of the tert-dodecyl mercaptan reaction solution is 2 g / min.

[0041] In some optional embodiments, the number of plates of the extractive distillation tower is 20-30, thereby ensuring the effective separation of tert-dodecyl mercaptan and tetrapropylene. Compared with the existing process that requires the use of 80 plates, the present application can significantly reduce the number of plates, thereby reducing equipment investment. The present application has found that if the number of plates of the extractive distillation tower is too large, the equipment investment is large and the separation cost is high. On the contrary, if the number of plates of the extractive distillation tower is too small, it will lead to poor separation effect and unqualified product indicators. As an example, the number of plates of the extractive distillation tower can be, for example, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, etc. or within the range composed of any two of the above values.

[0042] In some optional embodiments, the reflux ratio of the extractive distillation tower is 1-5, thereby ensuring the effective separation of tert-dodecyl mercaptan and tetrapropylene. Compared with the existing process, the present application can significantly reduce the reflux ratio, thereby reducing process energy consumption. The present application has found that if the reflux ratio of the extractive distillation tower is too large, the separation energy consumption is too high. On the contrary, if the reflux ratio of the extractive distillation tower is too small, it will lead to poor separation effect and unqualified product indicators. As an example, the reflux ratio of the extractive distillation tower can be, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc. or within the range composed of any two of the above values.

[0043] In some alternative embodiments, the operating pressure of the extractive distillation column is 1-5 kPa. This can achieve the separation of the product under relatively economical conditions, while avoiding decomposition of the product at high temperatures. The present application has found that if the operating pressure of the extractive distillation column is too high, the temperature of the column bottom is high, and the tertiary dodecyl mercaptan can decompose during the distillation process. Conversely, if the operating pressure of the extractive distillation column is too low, the energy consumption of the vacuum unit is high, the investment is large, and the separation effect is poor, and the product quality is unqualified. For example, the operating pressure of the extractive distillation column can be 1 kPa, 1.5 kPa, 2 kPa, 2.5 kPa, 3 kPa, 3.5 kPa, 4 kPa, 4.5 kPa, 5 kPa, or within a range defined by any two of the above values.

[0044] In some alternative embodiments, the number of trays of the recovery distillation column is 10-20, which can achieve efficient separation of the extractant and the tertiary dodecyl mercaptan. The present application has found that if the number of trays of the recovery distillation column is too large, the energy consumption is high, and conversely, if the number of trays of the recovery distillation column is too small, the separation effect of the extractant and the tertiary dodecyl mercaptan is poor. For example, the number of trays of the recovery distillation column can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or within a range defined by any two of the above values.

[0045] In some alternative embodiments, the reflux ratio of the recovery distillation column is 0.2-3, which can ensure efficient separation of the extractant and the tertiary dodecyl mercaptan. The present application has found that if the reflux ratio of the recovery distillation column is too large, the energy consumption is too high, and conversely, if the reflux ratio of the recovery distillation column is too small, the separation effect of the extractant and the tertiary dodecyl mercaptan is poor. For example, the reflux ratio of the recovery distillation column can be 0.2, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, or within a range defined by any two of the above values.

[0046] In some alternative embodiments, the operating pressure of the recovery distillation column is 0.1-3 kPa, which can ensure efficient separation of the extractant and the tertiary dodecyl mercaptan. The present application has found that if the operating pressure of the recovery distillation column is too large, the energy consumption is too high, and conversely, if the operating pressure of the recovery distillation column is too small, the separation effect of the extractant and the tertiary dodecyl mercaptan is poor. For example, the operating pressure of the recovery distillation column can be 0.1 kPa, 0.5 kPa, 1 kPa, 1.5 kPa, 2 kPa, 2.5 kPa, 3 kPa, or within a range defined by any two of the above values.

[0047] It can be understood that the bottom liquid of the recovery distillation tower is the extractant. Therefore, in order to reduce the process cost as much as possible, in some optional embodiments, the bottom liquid of the recovery distillation tower obtained in S2 can be reused in S1.

[0048] The present application has found that the separation method provided herein can achieve the separation requirements when tetrapropylene and tert-dodecyl mercaptan are present in any ratio in the tert-dodecyl mercaptan reaction solution. Therefore, the present application does not impose any restrictions on the content of tetrapropylene and tert-dodecyl mercaptan in the tert-dodecyl mercaptan reaction solution. It is understood that in some embodiments, the tert-dodecyl mercaptan reaction solution comprises 10 wt%-20 wt% tetrapropylene and 80 wt%-90 wt% tert-dodecyl mercaptan.

[0049] The present application is further described in detail below with reference to specific examples. These examples are not to be construed as limiting the scope of protection claimed in this application. Where specific experimental procedures or conditions are not specified in the Examples and Comparative Examples, the procedures or conditions of conventional experimental procedures described in the literature in this field can be followed. Where the manufacturer of the reagents or instruments used is not specified, they are all commercially available conventional reagent products.

[0050] 1. Sources of raw materials and extractants:

[0051] The tert-dodecyl mercaptan reaction solution to be separated was produced by Wanhua Chemical Group Co., Ltd. Sulfolane, phenethyl sulfone, and diphenyl sulfone were purchased from Alfa Aesar Reagents.

[0052] 2. Content analysis method:

[0053] instrument Manufacturer Analytical methods Gas chromatography Agilent Normalization method

[0054] Chromatographic column: DB-5, HP-5 or wax column; gas chromatography analysis method: column temperature 50℃, maintain for 5 minutes, and then increase to 220℃ at a rate of 10℃ / min; detection by FID detector, injection volume 0.5μL.

[0055] Example 1

[0056] This embodiment provides a method for separating a tert-dodecyl mercaptan reaction solution, comprising the following steps:

[0057] In the first step, a tert-dodecyl mercaptan reaction solution (composed of 18 wt% tetrapropylene and 82 wt% tert-dodecyl mercaptan) is fed at a flow rate of 2 g / min into a 20-plate extractive distillation column through the raw material feed port on the 10th tray of the extractive distillation column. Sulfolane, an extractant, is fed at a flow rate of 2 g / min through the extractant feed port on the 5th tray of the extractive distillation column. The extractive distillation column is operated at an absolute pressure of 1 kPa and a reflux ratio of 1. Tetrapropylene with a purity of 99.6 wt% is obtained at the top of the extractive distillation column, and a mixture of tert-dodecyl mercaptan and the extractant sulfolane is obtained at the bottom of the extractive distillation column.

[0058] In a second step, the mixture of tert-dodecyl mercaptan and sulfolane, an extractant, is introduced into a 10-plate recovery distillation column through a feed inlet on the fifth tray of the recovery distillation column to separate sulfolane from tert-dodecyl mercaptan. The recovery distillation column is operated at an absolute pressure of 0.1 kPa and a reflux ratio of 0.2. Tert-dodecyl mercaptan with a purity of 99.6 wt% is obtained at the top of the recovery distillation column, and sulfolane with a purity of 99.9 wt% is obtained at the bottom of the recovery distillation column for recycling as an extractant.

[0059] The separation methods of Examples 1-A to 1-V are basically the same as those of Example 1, with the only differences shown in Table 1.

[0060] Table 1

[0061]

[0062]

[0063] Example 2

[0064] This embodiment provides a method for separating a tert-dodecyl mercaptan reaction solution, comprising the following steps:

[0065] In the first step, a tert-dodecyl mercaptan reaction solution (composed of 15 wt% tetrapropylene and 85 wt% tert-dodecyl mercaptan) is fed at a flow rate of 2 g / min into a 30-plate extractive distillation column through the raw material feed port on the 12th tray of the extractive distillation column. A 10 g / min flow rate of phenethyl sulfone, the extractant, is fed into the extractive distillation column through the extractant feed port on the 7th tray of the extractive distillation column. The extractive distillation column is operated at an absolute pressure of 5 kPa and a reflux ratio of 5. Tetrapropylene with a purity of 99.9 wt% is obtained at the top of the extractive distillation column, and a mixture of tert-dodecyl mercaptan and phenethyl sulfone, the extractant, is obtained at the bottom of the extractive distillation column.

[0066] In the second step, the mixture of tert-dodecyl mercaptan and phenethyl sulfone in the first step enters a 20-plate recovery distillation column through the raw material feed port on the ninth tray of the recovery distillation column to separate sulfolane from tert-dodecyl mercaptan. The recovery distillation column is operated at an absolute pressure of 3 kPa and a reflux ratio of 3. Tert-dodecyl mercaptan with a purity of 99.8 wt% is obtained at the top of the recovery distillation column; sulfolane with a purity of 99.9 wt% is obtained at the bottom of the recovery distillation column and is recycled as an extraction agent.

[0067] Example 3

[0068] This embodiment provides a method for separating a tert-dodecyl mercaptan reaction solution, comprising the following steps:

[0069] In the first step, a tert-dodecyl mercaptan reaction solution (composed of 10 wt% tetrapropylene and 90 wt% tert-dodecyl mercaptan) is fed at a flow rate of 2 g / min into a 25-plate extractive distillation column through the raw material feed port on the 10th tray of the extractive distillation column. Diphenyl sulfone, the extractant, is fed at a flow rate of 4 g / min through the extractant feed port on the 5th tray of the extractive distillation column. The extractive distillation column is operated at an absolute pressure of 2 kPa and a reflux ratio of 2. Tetrapropylene with a purity of 99.7 wt% is obtained at the top of the extractive distillation column, and a mixture of tert-dodecyl mercaptan and diphenyl sulfone, the extractant, is obtained at the bottom of the extractive distillation column.

[0070] In the second step, the mixture of tert-dodecyl mercaptan and diphenyl sulfone, an extractant, produced in the first step, is fed into a 15-plate recovery distillation column via a feed inlet on the seventh tray of the recovery distillation column to separate sulfolane from tert-dodecyl mercaptan. The recovery distillation column is operated at an absolute pressure of 0.5 kPa and a reflux ratio of 0.5. Tert-dodecyl mercaptan with a purity of 99.7% by weight is obtained at the top of the recovery distillation column, while diphenyl sulfone with a purity of 99.99% by weight is obtained at the bottom of the recovery distillation column for recycling as an extractant.

[0071] Example 4

[0072] This embodiment provides a method for separating a tert-dodecyl mercaptan reaction solution, comprising the following steps:

[0073] In the first step, a tert-dodecyl mercaptan reaction solution (composed of 20 wt% tetrapropylene and 80 wt% tert-dodecyl mercaptan) is fed at a flow rate of 2 g / min into a 25-plate extractive distillation column through the raw material feed port on the 10th tray of the extractive distillation column. Sulfolane, an extractant, is fed at a flow rate of 6 g / min through the extractant feed port on the 3rd tray of the extractive distillation column. The extractive distillation column is operated at an absolute pressure of 3 kPa and a reflux ratio of 3. Tetrapropylene with a purity of 99.8 wt% is obtained at the top of the extractive distillation column, and a mixture of tert-dodecyl mercaptan and the extractant sulfolane is obtained at the bottom of the extractive distillation column.

[0074] In a second step, the mixture of tert-dodecyl mercaptan and sulfolane, an extractant, obtained in the first step, is fed into a 15-plate recovery distillation column through a feed inlet on the fifth tray of the recovery distillation column to separate sulfolane from tert-dodecyl mercaptan. The recovery distillation column is operated at an absolute pressure of 2 kPa and a reflux ratio of 2. Tert-dodecyl mercaptan with a purity of 99.9% by weight is obtained at the top of the recovery distillation column, and sulfolane with a purity of 99.99% by weight is obtained at the bottom of the recovery distillation column for recycling as an extractant.

[0075] Comparative Example 1

[0076] The process is basically the same as Example 1, except that N,N-dimethylformamide (DMF) is used as the extractant.

[0077] The separation effects of the above examples and comparative examples are shown in Table 2.

[0078] Table 2

[0079]

[0080]

[0081] As can be seen from Table 2, the recovery rate of tert-dodecyl mercaptan obtained in all examples was above 99.5%, and the purity of tert-dodecyl mercaptan was as high as above 98.8%. At the same time, the recovery rate of tetrapropylene was above 99.2%, and the purity of tetrapropylene was above 98.3%. Compared with Comparative Example 1 and the existing separation process, the purity of tert-dodecyl mercaptan and tetrapropylene obtained in all examples was significantly improved. This shows that the separation method of the present application, by using a specific sulfone substance as an extractant and first performing extractive distillation followed by conventional distillation, can significantly improve the separation purity and recovery rate of tetrapropylene and tert-dodecyl mercaptan.

[0082] At the same time, the separation method of the present application can also ensure high separation purity and recovery rate of the extractant, which is conducive to reducing process costs.

[0083] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A method for separating a tert-dodecyl mercaptan reaction solution, wherein the tert-dodecyl mercaptan reaction solution comprises tetrapropylene and tert-dodecyl mercaptan; characterized in that: The separation method comprises the following steps: S1. In the presence of an extractant, the tert-dodecyl mercaptan reaction solution is subjected to extractive distillation in an extractive distillation tower, and the extractive distillation tower bottom liquid and tetrapropylene are collected respectively; The extractant is at least one of sulfolane, phenethyl sulfone, and diphenyl sulfone; S2. Send the extractive distillation tower bottom liquid obtained in S1 into a recovery distillation tower for separation to obtain tert-dodecyl mercaptan.

2. The method for separating the tert-dodecyl mercaptan reaction solution according to claim 1, wherein The mass flow ratio of the extractant to the tert-dodecyl mercaptan reaction solution is 1-5; And / or, the number of plates of the extractive distillation tower is 20-30; And / or, the reflux ratio of the extractive distillation tower is 1-5.

3. The method for separating the tert-dodecyl mercaptan reaction solution according to claim 2, wherein The reflux ratio of the extractive distillation tower is 2-3; and / or, the mass flow rate of the extractant is 2 g / min-10 g / min; And / or, the mass flow rate of the tert-dodecyl mercaptan reaction solution is 2 g / min.

4. The method for separating the tert-dodecyl mercaptan reaction solution according to claim 1, wherein The operating pressure of the extractive distillation tower is 1 kPa-5 kPa absolute pressure.

5. The method for separating the tert-dodecyl mercaptan reaction solution according to claim 4, wherein The operating pressure of the extractive distillation tower is 2kPa-3kPa absolute pressure.

6. The method for separating the tert-dodecyl mercaptan reaction solution according to any one of claims 1 to 5, characterized in that: The number of plates of the recovery distillation tower is 10-20; And / or, the reflux ratio of the recovery distillation tower is 0.2-3.

7. The method for separating the tert-dodecyl mercaptan reaction solution according to claim 6, wherein: The reflux ratio of the recovery distillation tower is 0.5-2.

8. The method for separating the tert-dodecyl mercaptan reaction solution according to any one of claims 1 to 5, characterized in that: The operating pressure of the recovery distillation tower is 0.1 kPa-3 kPa absolute pressure.

9. The method for separating the tert-dodecyl mercaptan reaction solution according to claim 8, wherein The operating pressure of the recovery distillation tower is 0.5kPa-2kPa absolute pressure.

10. The method for separating a tert-dodecyl mercaptan reaction solution according to claim 1, 2, 3, 4, 5, 7 or 9, wherein: The bottom liquid of the recovery distillation tower obtained in S2 is recycled to S1 as an extractant.

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