Method for complexing and separating n-alkanes in direct coal liquefaction oil

Abstract

The invention discloses a method for complexing and separating n-alkanes in direct coal liquefaction oil, which comprises the following steps: 1) carrying out complexing reaction on the direct coal liquefaction oil and a complexing solution at 40-80 DEG C to obtain a complex suspension; 2) separating the complex suspension to obtain a complex and a filtrate; 3) demulsifying the filtrate at 20-60 DEG C, and separating out an oil phase to obtain an n-alkane removed oil product; wherein the complexing solution comprises a complexing agent, an activating agent and a solvent, the complexing agent is one or more of urea and thiourea, and the activating agent is low-carbon alcohol. The method effectively solves the problem that n-alkanes and isoalkanes in the direct coal liquefaction oil are difficult to separate.

Description

Technical Field

[0001] The invention relates to the field of normal alkane separation, and in particular to a method for complexing and separating normal alkanes in coal direct liquefaction oil. Background Art

[0002] Solvent oil is one of the main separation products of petroleum. It is an important basic oil in organic chemical raw materials and industrial production. It has a wide range of applications and is closely related to human daily life, involving national economic industries such as chemical, electronics, medicine, textile, and machinery. The proportion of naphtha fraction in coal direct liquefaction oil is relatively low, generally between 15-30%, and its sulfur content is extremely low (below 0.25 mg / kg). The total volume fraction of cycloalkanes and aromatics can reach more than 70%, and it does not contain olefins. Among them, the presence of normal alkanes increases the pour point of coal direct liquefaction oil and reduces the low-temperature performance of the oil. The research octane number is relatively low (RON is around 70). Therefore, effectively separating normal alkanes in coal direct liquefaction oil, reducing the pour point of de-normalized oil, and improving the low-temperature performance of oil products meet the requirements of refining and upgrading of coal direct liquefaction oil. De-normalized oil can be obtained by separating normal alkanes from coal direct liquefaction oil. Compared with untreated coal direct liquefaction oil, de-normalized alkane oil is safe and environmentally friendly, has low surface tension, strong cohesion, is easy to recycle, has a high reuse rate, better ductility, lower cloud point, melting point, boiling point and freezing point, and can be used as a lubricant for various instruments in low temperature environments. At the same time, due to the poor thermal oxidation stability of normal alkanes and the easy production of peroxides at high temperatures, the stability and solubility of de-normalized alkane oil are better than those of untreated coal direct liquefaction oil. In addition, de-normalized alkane oil also has the advantage of low toxicity. Taking 6# solvent oil as an example, its main component is C6 alkane, of which the content of normal hexane is about 25%. It can usually be used as a cleaning agent and is often used in printing, hardware, electronics, glue, rubber, defense industry, paint, chemical industry and grease.

[0003] The direct liquefaction oil of raw coal has defects such as high freezing point, low octane number, and low oil quality, which can be improved by separation of normal alkanes. In the prior art, the methods for separating normal alkanes from oil products mainly include molecular sieve method and urea complexation method. Molecular sieve adsorption separation of normal alkanes mainly utilizes its adsorption characteristics to effectively separate normal alkanes from oil products. Although the domestic molecular sieve dewaxing technology has simple equipment, the molecular sieve has a short life, frequent regeneration, the device cannot be operated all year round, the energy consumption is high, and the liquid wax recovery rate is also low; while the foreign molecular sieve dewaxing technology has low energy consumption and the separated normal alkanes have high purity, but the process is cumbersome, the equipment is complex, and the investment is high. More importantly, compared with urea dewaxing, heavy liquid wax cannot be produced. This is mainly because long-chain normal alkanes will seriously restrict their diffusion rate and adsorption and desorption rate on the molecular sieve.

[0004] The urea complexation method relies on the complexation reaction between urea and normal alkanes to separate normal alkanes from oil products. In basic principle, the urea complexation method is superior to the molecular sieve adsorption method. The urea complexation method is often used to separate high-carbon normal alkanes from isoalkanes and cycloalkanes with similar carbon numbers. The molecular types of the components involved are relatively simple and the molecular structures vary greatly. However, the composition of direct coal liquefaction oil is more complex, and the molecular structures of some compounds are less different. The difference in complexation with urea molecules is small, making separation more difficult. Therefore, the existing technology has not effectively separated normal alkanes from direct coal liquefaction oil. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide a method for complexing and separating normal alkanes in coal direct liquefaction oil, which effectively solves the problem of difficulty in separating normal alkanes and isoalkanes in coal direct liquefaction oil.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a method for complexing and separating normal alkanes in direct coal liquefaction oil, comprising the following steps:

[0007] 1) performing a complex reaction on the coal direct liquefaction oil and the complex solution at 40-80° C. to obtain a complex suspension;

[0008] 2) separating the complex suspension to obtain a complex and a filtrate;

[0009] 3) placing the filtrate at 20-60° C. for demulsification, separating the oil phase, and obtaining a de-normalized oil product;

[0010] The complexing solution comprises a complexing agent, an activator and a solvent, the complexing agent is one or more of urea and thiourea, and the activator is a low-carbon alcohol.

[0011] Furthermore, the activator is selected from any one of methanol, ethanol, ethylene glycol, isopropanol, glycerol or a mixture thereof; preferably, it is selected from any one of methanol, ethanol, isopropanol or a mixture thereof.

[0012] Furthermore, the solvent is water, preferably deionized water.

[0013] Furthermore, the mass ratio of the complexing agent, the activating agent and the solvent is (1-8):(1-8):1, preferably, (1-5):(1-5):1, more preferably, (1-3):(1-3):1, for example, 1:1:1, 1:1.5:1, 1:2:1, 1:2.5:1, 1:3:1, 3:1:1, 2.5:1:1, 2:1:1, 1.5:1:1, etc. A better complexing separation effect can be achieved within the above mass ratio range.

[0014] Furthermore, the mass ratio of the complex solution to the coal direct liquefaction oil is (2-10):1, preferably (2-8):1, more preferably (3-6):1, such as 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, etc. A better complex separation effect can be achieved within the above mass ratio range.

[0015] Furthermore, the temperature of the complexation reaction is preferably 40-60°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, etc.; the complexation reaction time is 10-300 min, preferably 30-300 min, more preferably 30-150 min.

[0016] Furthermore, the method also includes: after the complex reaction is completed, the reactants are cooled to 25-50°C, more preferably, to 25-35°C, such as 26°C, 28°C, 30°C, 32°C, etc., so that the non-normal alkane components that have not undergone complex reaction can be effectively separated from the complex phase within the above temperature range.

[0017] Furthermore, the demulsification temperature is preferably 30-60°C, such as 35°C, 40°C, 45°C, 50°C, 55°C, etc., to achieve better separation of normal alkanes and complexing agents; the demulsification time is 1-24h, preferably 3-24h, more preferably 6-12h.

[0018] Furthermore, the temperature during separation of the oil phase is 10-50°C to achieve efficient separation of the complexing agent and the oil phase; preferably, it is 20-50°C, more preferably, it is 20-40°C, for example, 25°C, 30°C, 35°C, etc.

[0019] Furthermore, the normal alkane content in the direct coal liquefaction oil is 10 to 30 wt.%.

[0020] Furthermore, the normal alkane content in the normal alkane-free oil product is 5 to 20 wt.%, preferably 5 to 10 wt.%.

[0021] Furthermore, the method further comprises step 4): thermally decomposing the complex obtained in step 2) to separate the oil phase to obtain a product rich in normal alkane oil, thereby further realizing efficient utilization of resources.

[0022] Furthermore, in step 3) and step 4), the aqueous phase is separated to obtain a solution containing a complexing agent. The aqueous phase is mainly a urea aqueous solution and also contains an alcohol activator; preferably, the complexing agent solution obtained above can be reused as a complexing solution by supplementing corresponding components, thereby realizing the recycling of complexing agents such as urea.

[0023] Furthermore, the hot water decomplexation temperature is 40-100°C to achieve effective decomplexation of the complex and improve the decomplexation rate and efficiency; preferably, it is 50-90°C, more preferably, it is 60-80°C, for example, 65°C, 70°C, 75°C, etc.

[0024] In a specific embodiment, the hot water decomplexation method is: add the complex obtained in step 2) and water into a container, and place it in a constant temperature water bath for hot water decomplexation.

[0025] Furthermore, the hot water decomplexation time is 5 to 60 minutes, preferably 10 to 60 minutes, and more preferably 10 to 30 minutes.

[0026] Furthermore, the normal alkane content in the normal alkane-rich oil is 5 to 40 wt.%, preferably 25 to 30 wt.%.

[0027] Furthermore, in step 3), a demulsifier is added to the filtrate for demulsification; the demulsifier is an aqueous demulsifier or an oily demulsifier or a mixture thereof, preferably an aqueous demulsifier.

[0028] Furthermore, the amount of the demulsifier added is 100 to 2000 ppm. Under the above minimum dosage, efficient demulsification can be achieved to obtain the best oil-water separation effect; preferably, it is 100 to 1000 ppm, and more preferably, it is 100 to 500 ppm.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The present invention conducts a complex reaction between coal direct liquefaction oil and a complex solution, wherein the complex solution comprises a complexing agent, an activator and a solvent, wherein the complexing agent is one or more of urea and thiourea, and the activator is a low-carbon alcohol; when the complex reaction is conducted at 40-80°C, the complexing agent can complex with normal alkanes in the coal direct liquefaction oil to generate complex crystals, while isoalkanes cannot complex with the complexing agent, thereby separating normal alkanes from the coal direct liquefaction oil. In order to increase the reaction speed and shorten the time to reach equilibrium, the low-carbon alcohol solution added to the reaction system is used as an activator. The low-carbon alcohol solution has a large polarity and a low viscosity, and can promote the dissolution of complexing agents such as urea, and the low-carbon alcohol solution can also promote the mutual contact between complexing agents such as urea and normal alkanes in the oil phase, thereby accelerating the reaction speed. At the same time, the low-carbon alcohol solution can dilute the liquid phase, so that the generated complex can float freely in the liquid phase and unite into balls, that is, the reaction obtains a complex suspension, and the complex suspension is separated to obtain a complex and a filtrate; the filtrate is demulsified at 20-60°C to separate the oil phase, that is, the de-normalized alkane oil product is obtained.

[0031] Therefore, the present invention effectively solves the problem of separation of normal alkanes and isoalkanes in oil products, and can be widely used for removal or purification of normal alkanes for other purposes, such as reducing the pour point of oil products, refining paraffin, etc. The present invention efficiently separates normal alkanes from coal direct liquefaction oil, overcoming the defects of high pour point, low octane number and low oil quality of raw coal direct liquefaction oil.

[0032] In addition, the present invention also provides a method for recovering n-alkane-rich oil and recycling urea solution, by decomplexing the complex and recovering the n-alkane-rich oil and urea solution therein, further achieving the purpose of efficient resource utilization and green chemical industry.

[0033] Other features and advantages of the present invention will be described in detail through the following detailed description. DETAILED DESCRIPTION

[0034] The present application is further described below in conjunction with embodiments, but the present application is not limited to the listed embodiments, but also includes equivalent improvements and modifications of the technical solutions defined in the claims attached to the present application.

[0035] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0036] The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers. Unless otherwise specified, percentages and parts are by weight.

[0037] Unless otherwise specified, the experimental materials and reagents used in the following examples can be obtained from commercial channels.

[0038] Coal direct liquefaction oil comes from the Ordos Branch of China Shenhua Coal to Oil Chemical Co., Ltd. The normal alkane content is about 10-20wt.%.

[0039] The gas chromatography-mass spectrometry instrument model is Agilent 5975.

[0040] The present invention is described in detail below by way of examples:

[0041] Example 1

[0042] Weigh 82 parts of urea, 90 parts of isopropanol, 45 parts of water and 54 parts of coal direct liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and suction flask for suction filtration. After the suction filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, obtain oil and water phases. At room temperature of 26°C, use a separatory funnel for separation to obtain a de-normalized alkane oil product (oil phase). The product was weighed and the yield of the product was calculated to be 70%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 6.0%.

[0043] Example 2

[0044] Weigh 70 parts of urea, 90 parts of isopropanol, 45 parts of water and 60 parts of direct coal liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction filter bottle to filter. After the filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, obtain oil and water phases. At room temperature of 26°C, use a separatory funnel to separate the liquid to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 62%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 6.0%.

[0045] Example 3

[0046] Weigh 82 parts of urea, 90 parts of isopropanol, 33 parts of water and 54 parts of coal direct liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction flask for suction filtration. After the suction filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours, and obtain oil-water two phases after demulsification. At room temperature of 26°C, use a separatory funnel for separation to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 58%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 6.9%.

[0047] Example 4

[0048] Weigh 82 parts of urea, 102 parts of isopropanol, 45 parts of water and 54 parts of direct coal liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction flask for suction filtration. After the suction filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After the demulsification is completed, oil and water phases are obtained. At room temperature of 26°C, use a separatory funnel for separation to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 72%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated de-normalized oil was found to be 6.3%.

[0049] Example 5

[0050] Weigh 82 parts of urea, 90 parts of isopropanol, 45 parts of water and 54 parts of direct coal liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 40°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction flask for suction filtration. After the suction filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, obtain oil and water phases. At room temperature of 26°C, use a separatory funnel for separation to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 61%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 6.1%.

[0051] Example 6

[0052] Weigh 82 parts of urea, 90 parts of isopropanol, 45 parts of water and 54 parts of direct coal liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 60°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction filter bottle to filter. After the filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, obtain oil and water phases. At room temperature of 26°C, use a separatory funnel to separate the liquid to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 62%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 5.7%.

[0053] Example 7

[0054] Weigh 82 parts of urea, 90 parts of isopropanol, 45 parts of water and 54 parts of coal direct liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 30 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and suction flask for suction filtration. After the suction filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, obtain oil and water phases. At room temperature of 26°C, use a separatory funnel for separation to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 63%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 5.9%.

[0055] Example 8

[0056] Weigh 82 parts of urea, 90 parts of isopropanol, 45 parts of water and 54 parts of coal direct liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 150 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature naturally cools to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction flask to filter. After the filtration is completed, collect the filter cake and continue to process the filtrate. Place the filtrate in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, obtain oil and water phases. At room temperature of 26°C, use a separatory funnel to separate the liquid to obtain a de-normalized alkane oil product after treatment. The product was weighed and the yield was calculated to be 54%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated normal-alkane-free oil was found to be 6.1%.

[0057] Example 9

[0058] Weigh 82 parts of urea, 90 parts of isopropanol, 45 parts of water and 54 parts of direct coal liquefaction oil into a flask, insert a stirring paddle, and place the flask in a constant temperature water bath at 50°C for complexation reaction under stirring. After 60 minutes of reaction, set the temperature of the constant temperature water bath to 28°C to cool the complex suspension. When the temperature is naturally cooled to 28°C (at room temperature of 26°C) under stirring, take out the flask. Use a heated Buchner funnel and a suction filter bottle to filter, collect the filter cake after the filtration is completed, and continue to process the filtrate. Add 300ppm of aqueous demulsifier polyoxyethylene propylene glycol ether to the filtrate, and place it in a constant temperature water bath at 50°C for demulsification for 10 hours. After demulsification, oil and water phases are obtained. At room temperature of 26°C, use a separatory funnel to separate the liquid to obtain the de-normalized alkane oil after treatment. The product was weighed and the yield was calculated to be 74%. The product was then analyzed by gas chromatography-mass spectrometry to obtain its composition, and further the content of normal alkanes in the treated de-normalized oil was found to be about 5.5%.

[0059] Example 10

[0060] According to the method of Example 9, the filter cake collected after the filtration was washed with petroleum ether with a boiling range of 60 to 90°C, and the amount of petroleum ether was 3 ml / g of coal direct liquefaction oil raw material. The yield of the de-normalized oil product was greatly improved to 96.82%. At the same time, the normal alkane content in the by-product paraffin after decomplexation was increased from 28.91% before washing to 63.33%.

[0061] Comparative Example 1

[0062] Weigh 10 parts of urea, 10 parts of isopropanol, 50 parts of water and 50 parts of coal direct liquefaction oil into a flask, insert a stirring paddle, and carry out complexation reaction under stirring at room temperature (25°C). After reacting for 20 minutes, take out the flask. Use a heated Buchner funnel and a suction filter bottle to filter, collect the filter cake after the filtration is completed, and continue to process the filtrate. Place the filtrate in a 35°C constant temperature water bath for demulsification for 10 hours, and obtain oil and water phases after demulsification. At room temperature of 25°C, use a separatory funnel to separate the liquids to obtain the oil phase product after treatment. The product is weighed and the yield of the oil phase product is calculated to be 65%. The product is then analyzed by gas chromatography-mass spectrometry to obtain its composition, and then the content of normal alkanes in the treated de-normal alkane oil is obtained to be 16.7%.

[0063] In the above Comparative Example 1, due to the inappropriate ratio of the complexing agent, activating agent and solvent, the separation effect of normal alkanes is poor.

[0064] In summary, the present invention solves the problem of the difficulty in effectively separating long-chain normal alkanes and isoalkanes through the method of urea complexing normal alkanes, thereby efficiently separating the normal alkanes in the coal direct liquefaction oil, and improving the defects of high pour point, low octane number and low oil quality of the raw coal direct liquefaction oil. In addition, the present invention also provides a method for recovering normal alkane-rich oil and recycling urea solution, further achieving the purpose of efficient resource utilization and green chemical industry. According to the method proposed in the present invention, based on the normal alkane composition in typical raw oil, it is easy to think of changing the reaction conditions to design a urea complexing separation process for normal alkanes based on other purposes, such as reducing the pour point of oil products, paraffin refining, etc. The method of the present invention greatly broadens the application of urea complexing separation of normal alkanes in oil refining.

[0065] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are within the spirit scope of the present invention.

Claims

1. A method for complex separation of normal alkanes in direct coal liquefaction oil, characterized in that: The steps include: 1) performing a complex reaction on the coal direct liquefaction oil and the complex solution at 40-80° C. to obtain a complex suspension; 2) separating the complex suspension to obtain a complex and a filtrate; 3) placing the filtrate at 20-60° C. for demulsification, separating the oil phase, and obtaining a de-normalized oil product; The complexing solution comprises a complexing agent, an activator and a solvent, the complexing agent is one or more of urea and thiourea, and the activator is a low-carbon alcohol.

2. The method for complexing and separating normal alkanes according to claim 1, characterized in that: The activator is selected from any one of methanol, ethanol, ethylene glycol, isopropanol, glycerol or a mixture thereof; preferably, selected from any one of methanol, ethanol, isopropanol or a mixture thereof; and / or, the solvent is water.

3. The method for complexing and separating normal alkanes according to claim 1, characterized in that: The mass ratio of the complexing agent, the activating agent and the solvent is (1-8):(1-8):1, preferably, (1-5):(1-5):1, more preferably, (1-3):(1-3):1; and / or, The mass ratio of the complex solution to the coal direct liquefaction oil is (2-10):1, preferably (2-8):1, and more preferably (3-6):

1.

4. The method for complexing and separating normal alkanes according to any one of claims 1 to 3, characterized in that: Step 1) The temperature of the complexation reaction is 40-60° C.; the complexation reaction time is 10-300 min, preferably 30-300 min, and more preferably 30-150 min.

5. The method for complexing and separating normal alkanes according to any one of claims 1 to 4, characterized in that: The method further comprises: cooling the reactants to 25-50°C, more preferably 25-35°C after the complexation reaction is completed.

6. The method for complexing and separating normal alkanes according to any one of claims 1 to 5, characterized in that: Step 3) The demulsification temperature is 30-60°C; the demulsification time is 1-24h, preferably 3-24h, more preferably 6-12h; and / or, The temperature during separation of the oil phase is 10-50°C, preferably 20-50°C, more preferably 20-40°C.

7. The method for complexing and separating normal alkanes according to claim 1, characterized in that: The method further comprises step 4): performing thermal hydrolysis on the complex obtained in step 2) to separate the oil phase and obtain a normal alkane-rich oil product.

8. The method for complexing and separating normal alkanes according to claim 7, characterized in that: In step 3) and step 4), the aqueous phase is separated to obtain a solution containing a complexing agent.

9. The method for complexing and separating normal alkanes according to claim 7, characterized in that: The hot water decomplexation temperature is 40 to 100° C., preferably 50 to 90° C., more preferably 60 to 80° C.; and / or, The hot water decomplexation time is 5 to 60 minutes, preferably 10 to 60 minutes, and more preferably 10 to 30 minutes.

10. The method for complexing and separating normal alkanes according to claim 1, characterized in that: In step 3), a demulsifier is added to the filtrate for demulsification; the demulsifier is an aqueous demulsifier or an oily demulsifier or a mixture thereof, preferably an aqueous demulsifier; and / or, The added amount of the demulsifier is 100-2000 ppm, preferably 100-1000 ppm, more preferably 100-500 ppm.