α-Alkene extractant and method for separating alkanes and α-alkenes

Abstract

This disclosure provides an α-alkene extractant comprising an alcoholamine, a saturated monoketone having a carbon chain length of 7-10, and a monovalent salt of a Group IB metal, wherein the mass ratio of the alcoholamine, the saturated monoketone having a carbon chain length of 7-10, and the monovalent salt of the Group IB metal is (0.9-2.0):(0.8-1.5):(0.1-0.6), and a method for separating alkanes and α-alkenes. This disclosure utilizes the principle of complexation extractive rectification technology, and by adding a complexation extractant, a relatively stable complex is formed between the metal and the alkene, achieving the goal of separation from the alkane, with good separation efficiency and high product yield.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 202211482757.X, filed on November 24, 2022, and entitled "α-Alkene Extractant and Method for Separating Alkane and α-Alkene," the entire contents of which are incorporated herein by reference.

[0002] The present disclosure belongs to the technical field of alkene separation, and specifically relates to an α-alkene extractant and a method for separating alkanes and α-alkenes. [Background technology]

[0003] Long-chain α-alkenes are important chemical raw materials and are widely used in the fields of surfactants, oilfield chemicals, alkene copolymers, alcohol plasticizers, lubricants and other fields. Traditionally, due to problems in the production process, the productivity of long-chain α-alkenes is low, and the supply of raw materials cannot keep up with the demand. In the end, the fine chemical industry of long-chain α-alkenes is in short supply and the import price is too high, so they can only import part of it or give up development. Fischer-Tropsch (FT) synthetic oil contains abundant long-chain α-alkenes, and the production capacity of coal-based FT synthetic oil is high, so the technical problem that needs to be solved first is to find a method to separate high-purity long-chain α-alkenes from FT crude petroleum products.

[0004] Fischer-Tropsch synthesis is a reaction that uses synthesis gas (CO+H2) as a raw material and the action of a catalyst to produce liquid hydrocarbons, oxygen-containing organic matter, carbon dioxide, water, etc. Fischer-Tropsch synthesis can indirectly convert carbon-containing resources such as coal, natural gas, and biomass into liquid fuels, and is of great practical significance to China's energy structure, which is "rich in coal, short on oil, and rich in natural gas." Wang Yadong et al. stated in the literature that the main products of high-temperature Fischer-Tropsch synthesis include fuel oil, oxygen-containing organic chemical products and alkenes. By using effective separation technology to extract 1-carbon or α-alkenes with a certain carbon number range from alkenes with a high content and continuous carbon number distribution, not only can alkenes be produced instead of traditional processes such as wax cracking, ethylene oligomerization and alkane dehydrogenation, but it is also advantageous for the diversification and development of downstream Fischer-Tropsch products. Separating high-purity long-chain α-alkene from FT synthetic oil not only makes it possible to obtain high-added-value long-chain α-alkene, but also improves the economic efficiency of coal-based FT synthetic oil.

[0005] In the past, the main separation methods include extractive rectification, composite membrane separation, adsorption, etc. Among them, extractive rectification technology combines the advantages of two operations, extraction and rectification, to greatly improve the separation efficiency of alkanes and alkenes. The operation process is to continuously add a high boiling point additive to the top of the rectification tower to change the relative volatility of the components in the liquid matter, making it easier to separate mixtures that are difficult to separate by ordinary rectification. However, most of the extractants used in the conventional extractive rectification method are single organic solvents, which are consumed in large quantities and have a severe impact on the environment due to secondary pollution, or the extractant used is a composite solvent, but the yield of the alkene product is extremely low, which does not meet the yield requirements in actual industrial production. The selection of an appropriate extractant is the key to whether separation can be realized. In the method of separating alkenes and alkanes using a composite membrane, the fabrication cost of the composite membrane is high and the implementation is complicated. The adsorption method has high requirements for the specific surface area and pore volume of the adsorbent, and in the adsorption separation process, the adsorbent is easily deactivated due to the accumulation of harmful substances during feeding, which leads to a decrease in production capacity and an easy adsorption saturation, and the regeneration and desorption processes generally require high temperatures and consume heat. Reactive rectification has strict requirements, for example, the main reaction time compared with the rectification time must not be too long, otherwise the separation capacity of the rectification tower will not be fully utilized.

[0006] In light of this, we propose this disclosure. Summary of the Invention

[0007] The object of the present disclosure is to provide an α-alkene extractant that can solve the problem of the stringent requirements of conventional rectification, and a method for separating alkanes and α-alkenes.

[0008] The disclosed embodiment can be realized as follows.

[0009] In a first aspect, the present disclosure provides an α-alkene extractant comprising an alcohol amine, a saturated monoketone having a carbon chain length of 7 to 10, and a monovalent salt of a Group IB metal, wherein the mass ratio of the alcohol amine, the saturated monoketone having a carbon chain length of 7 to 10, and the monovalent salt of the Group IB metal is (0.9-2.0):(0.8-1.5):(0.1-0.6).

[0010] In an alternative embodiment, the alcohol amine is at least one of monoethanolamine, diethanolamine, and triethanolamine.

[0011] In an alternative embodiment, the organic ketone is at least one of 2-heptanone, 2-octanone, 2-nonanone, and 3-decanone.

[0012] In alternative embodiments, the monovalent salt of a Group IB metal comprises at least one of cuprous chloride, cuprous tetrafluoroborate, silver tetrafluoroborate, cuprous trifluoroacetate, silver trifluoroacetate, cuprous acetate, silver acetate, and silver nitrate.

[0013] In a second aspect, the disclosure provides a method for the preparation of a compound comprising: an extractive rectification step, employing the extractant according to any one of the above-mentioned embodiments, extractively rectifying a raw material containing an alkane and an α-alkene to obtain a raffinate phase and a rich solvent containing an α-alkene; a purification step of rectifying the rich solvent containing the α-alkene to obtain the extractant and the separated α-alkene; The present invention provides a method for separating an alkane containing an α-alkene from an α-alkene.

[0014] In an alternative embodiment, the alkane and α-alkene containing feedstock is a Fischer-Tropsch synthetic oil; Preferably, before extracting the Fischer-Tropsch synthetic oil, the oil is first deoxidized and deoxidized with a compound; Preferably, the raw material contains, by weight, 20 to 25 parts of alkane and 70 to 75 parts of α-alkene.

[0015] In an alternative embodiment, the extractive distillation step is carried out in an extractive distillation column, the purification step is carried out in a purification column, the pressure in the extractive distillation column and / or the purification column is 45 to 56 Kpa, and the temperature is 45 to 125° C.; Preferably, the temperature in the extractive distillation tower and / or the purification tower is 45 to 65°C, more preferably, the still temperature of the extractive distillation tower is 55 to 59°C, and the still temperature of the purification tower is 58 to 62°C, Preferably, the temperature in the extractive distillation column and / or the purification column is 75 to 95° C., more preferably, the still temperature of the extractive distillation column is 84 to 88° C., and the still temperature of the purification column is 87 to 91° C.; Preferably, the temperature in the extractive rectification column and / or the purification column is 95 to 125°C, and more preferably, the still temperature of the extractive rectification column is 110 to 114°C, and the still temperature of the purification column is 113 to 117°C.

[0016] In an alternative embodiment, the operating parameters in the extractive rectification column are: the number of trays is 34-36, the feedstock is charged at trays 24-26, the extractant is charged at trays 3-5, the reflux ratio is 3.3-3.7:1, and the mass ratio of the extractant to the feedstock is 2.5-3.5:1; Preferably, the operating parameters in the extractive rectification column are: number of trays 35, feed position at tray 25, extractant feed position at tray 4, reflux ratio 3.5:1, and extractant to feed mass ratio 3:1.

[0017] In an alternative embodiment, the operating parameters within the purification column are: a tray number of 39 to 41, a feed position of trays 27 to 29, and a reflux ratio of 2.5 to 3.5:1; Preferably, the operating parameters within the purification column are: number of trays 40, charge position at tray 28, and reflux ratio of 3:1.

[0018] In an alternative embodiment, before the raw material and the extractant are charged into an extractive rectification column, preheating is first performed, the raw material is preheated to 65 to 100 ° C., and the extractant is preheated to 55 to 85 ° C., Preferably, before the raw material and the extractant are charged into an extractive rectification column, they are first preheated, that is, the raw material is preheated to 93 to 97°C and the extractant is preheated to 78 to 82°C. [Brief description of the drawings]

[0019] In order to more clearly explain the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings that need to be used in the embodiments. The drawings below only show some embodiments of the present disclosure, so they should not be considered as limiting the scope. Those skilled in the art can also obtain other related drawings based on these drawings without creative work.

[0020] [Figure 1] FIG. 1 is a structural schematic diagram of an apparatus for separating alkanes and α-alkenes in an embodiment of the present disclosure. [Explanation of symbols]

[0021] 1 Extraction rectification column 2 Refining tower 3 Piping C 4 Piping D 5 Piping E 6 Piping F 7 Conduit G 8 Piping H 9 Piping I DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Examples of the disclosed embodiments include, for example, the following beneficial effects:

[0023] Using the principle of complexation extraction rectification technology, a complexation extractant is added to form a relatively stable complex between the metal and the alkene, thereby achieving the purpose of separating the metal from the alkane.

[0024] Compared with the conventional method using a single organic extractant, this method is simple in operation, uses less organic solution, causes less environmental pollution, has good separation effect, high product yield, low cost, and is more economically effective, and plays a very important role in separating alkanes and alkenes.

[0025] In order to make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described below in detail with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only some of the embodiments of the present disclosure, not all of the embodiments of the present disclosure. Typically, the components of the embodiments of the present disclosure described and shown in the drawings in this specification can be arranged and designed in various different configurations.

[0026] Therefore, the detailed description of the embodiments of the present disclosure provided in the drawings below is not intended to limit the scope of the present disclosure sought to be protected, but only represents selected embodiments of the present disclosure. Based on the embodiments in the present disclosure, any other embodiments obtained by a person skilled in the art without performing any creative labor, all of which fall within the scope of protection of the present disclosure.

[0027] It should be noted that like symbols and letters represent like items in the following drawings, so that once an item is defined in one drawing, it need not be defined and interpreted again in subsequent drawings.

[0028] In the description of this disclosure, orientations or positional relationships indicated by terms such as "upper", "lower", "inner", "outer", etc. are based on orientations or positional relationships shown in the drawings or are orientations or positional relationships normally placed when the products of the present invention are used, and are merely for ease and simplification of the description of the present invention, and are not to be understood as limiting the present invention, as they do not expressly or imply that the devices or elements shown necessarily have a particular orientation, or are constructed and operated in a particular orientation.

[0029] Furthermore, the terms "first," "second," "third," etc. are used merely to distinguish and explain among themselves, and should not be understood as expressing or implying relative importance.

[0030] In addition, unless there is a contradiction, the components in the embodiments of the present disclosure may be combined with each other.

[0031] An embodiment of the present application provides an α-alkene extractant that includes an alcohol amine, a saturated monoketone having a carbon chain length of 7 to 10, and a monovalent salt of a Group IB metal, in which the mass ratio of the alcohol amine, the saturated monoketone having a carbon chain length of 7 to 10, and the monovalent salt of the Group IB metal is (0.9-2.0):(0.8-1.5):(0.1-0.6).

[0032] This disclosure utilizes the principle of complexation extractive rectification technology, and by adding a complexing extractant, a relatively stable complex is formed between the metal and the alkene, improving the selectivity of separation and reducing the amount of organic solution used. The metal used is a monovalent salt of a group IB metal, and the d electrons occupying the 4d orbital of the ion are back-donated to the alkene*π-2p antibonding orbital electrons to form a π bond. (n-1)d 10 n.s. 0 It has an electron configuration that makes it easy to accept electrons and easy to donate excess d-electrons, making it a suitable alkene carrier.

[0033] In this embodiment, by optimizing the composition of the extractant, it is possible to obtain α-alkene with a purity of up to 99.8%.

[0034] In other alternative embodiments, the alcohol amine is at least one of monoethanolamine, diethanolamine, and triethanolamine.

[0035] In other alternative embodiments, the organic ketone is at least one of 2-heptanone, 2-octanone, 2-nonanone, and 3-decanone.

[0036] In other alternative embodiments, the monovalent salt of a Group IB metal comprises at least one of cuprous chloride, cuprous tetrafluoroborate, silver tetrafluoroborate, cuprous trifluoroacetate, silver trifluoroacetate, cuprous acetate, silver acetate, and silver nitrate.

[0037] Considering the cost of the catalyst, the monovalent salts of copper and silver among the group IB metals are preferred, and the monovalent salts of group IB metals having a high degree of ionization are preferred. The monovalent metal cations have a higher degree of freedom and can increase the number of times of complex formation between the monovalent cations and alkenes, and more preferably copper(I) tetrafluoroborate, copper(I) trifluoroacetate, and copper acetate.

[0038] Another embodiment of the present disclosure is an extractive distillation step of extractively distilling a raw material containing alkanes and α-alkenes by using the extractant according to any one of the above-mentioned embodiments to obtain a raffinate phase and a rich solvent containing α-alkene; and rectifying the rich solvent containing the α-alkene to obtain the extractant and separated α-alkene. In another alternative embodiment, the feedstock containing the alkane and α-alkene is a Fischer-Tropsch synthesis oil.

[0039] In another alternative embodiment, the Fischer-Tropsch synthetic oil is first de-acidified and deoxygenated prior to extraction.

[0040] In another alternative embodiment, the feedstock contains, by weight, 20 to 25 parts alkane and 70 to 75 parts α-alkene.

[0041] This disclosure relates to the deoxidized and deoxygenated Fischer-Tropsch synthetic oil of Inner Mongolia Yinuo New Materials Co., Ltd., that is, using a simple hydrocarbon mixture as the raw material, the main composition of the raw material before and after deoxidization and deoxygenation is shown in Table 1. The method disclosed here realizes highly efficient separation of alkane and alkene components, and can obtain α-alkene products with high purity, wide applicability, low cost and strong economical efficiency, breaking the foreign monopoly on α-alkene, and greatly accelerating the rapid development and widespread application of high-value-added products such as high-grade synthetic resins and top-grade lubricants downstream in China.

[0042] [Table 1]

[0043] In another optional embodiment, the extractive distillation step is carried out in an extractive distillation column, and the purification step is carried out in a purification column, and the pressure in the extractive distillation column and / or the purification column is 45 to 56 Kpa and the temperature is 45 to 125°C.

[0044] In another optional embodiment, the temperature in the extractive rectification column and / or the purification column is 45 to 65°C, more preferably, the still temperature of the extractive rectification column is 55 to 59°C, and the still temperature of the purification column is 58 to 62°C, and the α-alkene having a carbon chain length of 6 can be used for separating only the α-alkene.

[0045] In another optional embodiment, the temperature in the extractive rectification column and / or the purification column is 75 to 95°C, more preferably, the still temperature of the extractive rectification column is 84 to 88°C, and the still temperature of the purification column is 87 to 91°C, and the α-alkene having a carbon chain length of 7 can be used for separating alone.

[0046] In another optional embodiment, the temperature in the extractive rectification column and / or the purification column is 95 to 125°C, more preferably, the still temperature of the extractive rectification column is 110 to 114°C, and the still temperature of the purification column is 113 to 117°C, and the α-alkene having a carbon chain length of 8 can be used for separating only the α-alkene.

[0047] In another alternative embodiment, the operating parameters in the extractive rectification column are: the number of trays is 34-36, the feed position is trays 24-26, the extractant is trays 3-5, the reflux ratio is 3.3-3.7:1, and the mass ratio of the extractant to the feed is 2.5-3.5:1.

[0048] In another alternative embodiment, the operating parameters within the extractive rectification column are: number of trays 35, feed charge position at tray 25, extractant charge position at tray 4, reflux ratio of 3.5:1, and extractant to feed mass ratio of 3:1.

[0049] In another alternative embodiment, the operating parameters within the purification column are: number of trays is 39-41, feed position is trays 27-29, and reflux ratio is 2.5-3.5:1.

[0050] In another alternative embodiment, the operating parameters within the purification column are: number of trays 40, charge position at tray 28, and reflux ratio of 3:1.

[0051] In another optional embodiment, before the raw material and the extractant are charged into an extractive rectification column, they are first preheated, the raw material is preheated to 65 to 100°C, and the extractant is preheated to 55 to 85°C.

[0052] In another optional embodiment, before the raw material and the extractant are charged into the extractive rectification column, they are first preheated, the raw material is preheated to 68 to 72°C, and the extractant is preheated to 58 to 62°C, and can be used to separate the α-alkene having a carbon chain length of 7 alone.

[0053] In another optional embodiment, before the raw material and the extractant are charged into the extractive rectification column, they are first preheated, the raw material is preheated to 93 to 97°C, and the extractant is preheated to 78 to 82°C, and can be used to separate the α-alkene having a carbon chain length of 8 alone.

[0054] The constituent elements and performance of the present disclosure will be described in more detail below with reference to examples.

[0055] The disclosed method for separating alkanes and α-alkenes includes the following steps:

[0056] Preparation of test reagents and equipment: ethanolamine, 2-heptanone, cuprous chloride, extractive distillation column, purification column, heat exchanger.

[0057] Operation steps: The feedstock for this test is a pretreated deoxygenated, deacidified and fractionated coal-based Fischer-Tropsch oil, i.e., a mixture containing alkenes and alkanes to be separated, with the carbon chain length of the target α-alkene being n, and 6≦n≦8.

[0058] When the device shown in Figure 1 is used to separate α-alkene with a carbon chain length of 6, the components to be separated enter the extractive distillation column 1 from the middle and lower parts through pipe D4, the composite extractant enters the extractive distillation column 1 from the top through pipe C3, and the bottom of the column is supplied with heat by the reboiler. After the extractive distillation, the alkene in the raw material is dissolved in the composite extractant, and the alkane is discharged from the top of the extractive distillation column 1 through pipe E5, a part of it is refluxed to the extractive distillation column 1 from the top, and the other part is extracted. The rich solvent containing alkene is extracted from the bottom of the extractive distillation tower 1, and enters the purification tower 2 from the center through pipe F6. The bottom of the tower is supplied with a heat source by a reboiler, and the alkene and the composite extractant are separated by rectification. The alkene is discharged from the top of the purification tower 2 through pipe G7, a part of it is refluxed to the purification tower 2 from the top, and the other part is extracted. The extractant is discharged from the bottom of the purification tower 2 through pipe H8, and after being cooled through pipe I9, it is returned to the extractive distillation tower 1 for recycling.

[0059] Here, n=6, and the extractant is compounded in the optimum ratio, i.e., ethanolamine:2-heptanone:cuprous chloride (mass ratio)=1:1:0.2. The operating parameters of the extractive rectification column are: still temperature 57°C, operating pressure 55.3 kpa, number of trays 35, feed position at tray 25, feed position of extractant at tray 4, reflux ratio 3.5:1, and mass ratio of extractant to feed 3:1. The operating parameters of the purification column are: still temperature 60°C, operating pressure 55.3 kpa, number of trays 40, feed position at tray 28, reflux ratio 3:1, and purity of alkene after recovery is 99.8 wt% or more.

[0060] When the device shown in Figure 1 is used to separate α-alkene with a carbon chain length of 7, the components to be separated are heated to 70°C by the preheater through pipe D4 and enter the extractive distillation column 1 from the middle and lower parts, the composite extractant is heated to 60°C by the preheater through pipe C3 and enters the extractive distillation column 1 from the top, and the bottom of the column is supplied with heat by the reboiler. Through the extractive distillation, the alkene in the raw material is dissolved in the composite extractant, and the alkane is discharged from the top of the extractive distillation column 1 through pipe E5, a part of it is refluxed to the extractive distillation column 1 from the top, and the other part is extracted. The rich solvent containing alkene is extracted from the bottom of the extractive distillation tower 1, and enters the purification tower 2 from the center through pipe F6. The bottom of the tower is supplied with heat by the reboiler, and the alkene and the composite extractant are separated by rectification. The alkene is discharged from the top of the purification tower 2 through pipe G7, a part of it is refluxed to the purification tower 2 from the top, and the other part is extracted. The extractant is discharged from the bottom of the purification tower 2 through pipe H8, and is cooled through pipe I9 and then returned to the extractive distillation tower 1 for recycling.

[0061] Here, n=7, the extractant is compounded in the optimum ratio, i.e., ethanolamine:2-heptanone:cuprous chloride (mass ratio)=1:1:0.2, and the operation parameters of the extractive rectification column are still temperature 86°C, operation pressure 55.3kpa, number of trays 35, feed position of the raw material is tray 25, feed position of the extractant is tray 4, reflux ratio 3.5:1, and mass ratio of the extractant to the raw material is 3:1. The operation parameters of the purification column are still temperature 89°C, operation pressure 55.3kpa, number of trays 40, feed position of the raw material is tray 28, and reflux ratio 3:1. The purity of the alkene after recovery is more than 99.8wt%.

[0062] When the device shown in Figure 1 is used to separate α-alkene with a carbon chain length of 8, the components to be separated are heated to 95°C by the preheater through pipe D4 and enter the extractive distillation column 1 from the middle and lower parts, the composite extractant is heated to 80°C by the preheater through pipe C3 and enters the extractive distillation column 1 from the top, and the bottom of the column is supplied with heat by the reboiler. Through the extractive distillation, the alkene in the raw material is dissolved in the composite extractant, and the alkane is discharged from the top of the extractive distillation column 1 through pipe E5, a part of it is refluxed to the extractive distillation column 1 from the top, and the other part is extracted. The rich solvent containing alkene is extracted from the bottom of the extractive distillation tower 1, and enters the purification tower 2 from the center through pipe F6. The bottom of the tower is supplied with heat by the reboiler, and the alkene and the composite extractant are separated by rectification. The alkene is discharged from the top of the purification tower 2 through pipe G7, a part of it is refluxed to the purification tower 2 from the top, and the other part is extracted. The extractant is discharged from the bottom of the purification tower 2 through pipe H8, and is cooled through pipe I9 and then returned to the extractive distillation tower 1 for recycling.

[0063] Here, n=8, and the composite extractant is composited in the optimum ratio, i.e., ethanolamine:2-heptanone:cuprous chloride (mass ratio)=1:1:0.2. The operation parameters of the extractive rectification tower are still temperature 112°C, operation pressure 55.3kpa, number of trays 35, feed position of the raw material is tray 25, feed position of the extractant is tray 4, reflux ratio 3.5:1, mass ratio of the extractant to the raw material is 3:1, and the operation parameters of the purification tower are still temperature 115°C, operation pressure 55.3kpa, number of trays 40, feed position of the raw material is tray 28, and reflux ratio 3:1. The purity of the alkene after recovery is more than 99.8wt%.

[0064] It should be noted that the values ​​of the points among the operation parameters may fluctuate to some extent due to the precision of the device control, but within the allowable error range, the effect on the results is within a controllable range.

[0065] [Table 2]

[0066] Comparative Example 1: The only difference from the test in Group 1 is that the alcohol amine solution is excluded from the composite solution, and the composite extractant is composed only of organic ketone and metal salt. The purity of the obtained product is 80wt% and the yield is 4%.

[0067] Comparative Example 2 The only difference from the test in Group 1 is that the organic ketone solution is excluded from the composite solution, and the composite extractant is composed only of alcohol amine and metal salt. The purity of the obtained product is 86 wt%, and the yield is 19%.

[0068] The above are merely specific embodiments of the present disclosure, and the scope of protection of the present disclosure is not limited thereto, and any changes or replacements that a person skilled in the art can easily think of within the technical scope disclosed in the present disclosure are included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be consistent with the scope of protection of the claims.

Claims

1. An α-alkene extractant comprising an alcohol amine, a saturated monoketone having a carbon chain length of 7 to 10, and a monovalent salt of a Group IB metal, wherein the mass ratio of the alcohol amine, the saturated monoketone having a carbon chain length of 7 to 10, and the monovalent salt of the Group IB metal is (0.9-2.0):(0.8-1.5):(0.1-0.6).

2. The α-alkene extractant according to claim 1, characterized in that the alcohol amine is at least one of monoethanolamine, diethanolamine and triethanolamine.

3. The α-alkene extractant according to claim 1, characterized in that the saturated monoketone having a carbon chain length of 7 to 10 is at least one of 2-heptanone, 2-octanone, 2-nonanone, and 3-decanone.

4. The α-alkene extractant according to claim 1, characterized in that the monovalent salt of a Group IB metal includes at least one of cuprous chloride, cuprous tetrafluoroborate, silver tetrafluoroborate, cuprous trifluoroacetate, silver trifluoroacetate, cuprous acetate, silver acetate, and silver nitrate.

5. An extractive distillation step of extractively distilling a raw material containing an alkane and an α-alkene by using the extractant according to any one of claims 1 to 4 to obtain a raffinate phase and a rich solvent containing an α-alkene; a purification step of rectifying the rich solvent containing the α-alkene to obtain the extractant and the separated α-alkene; A method for separating alkanes and α-alkenes, comprising:

6. The feedstock containing an alkane and an α-alkene is a Fischer-Tropsch synthetic oil, Preferably, before extracting the Fischer-Tropsch synthetic oil, the oil is first deoxidized and deoxidized with a compound; 6. The method for separating alkanes and α-alkenes according to claim 5, characterized in that the feedstock preferably contains, by weight, 20-25 parts alkane and 70-75 parts α-alkene.

7. The extractive distillation step is carried out in an extractive distillation column, the purification step is carried out in a purification column, the pressure in the extractive distillation column and / or the purification column is 45 to 56 Kpa and the temperature is 45 to 125° C., Preferably, the temperature in the extractive distillation column and / or the purification column is 45 to 65° C., more preferably, the still temperature of the extractive distillation column is 55 to 59° C., and the still temperature of the purification column is 58 to 62° C.; Preferably, the temperature in the extractive distillation column and / or the purification column is 75 to 95° C., more preferably, the still temperature of the extractive distillation column is 84 to 88° C., and the still temperature of the purification column is 87 to 91° C.; The method for separating an alkane and an α-alkene according to claim 5, characterized in that the temperature in the extractive distillation column and / or the purification column is preferably 95 to 125°C, and more preferably, the still temperature of the extractive distillation column is 110 to 114°C, and the still temperature of the purification column is 113 to 117°C.

8. The operation parameters in the extractive distillation column are: the number of trays is 34-36, the feed position is trays 24-26, the extractant is trays 3-5, the reflux ratio is 3.3-3.7:1, and the mass ratio of the extractant to the feed is 2.5-3.5:1; The method for separating alkanes and α-alkenes according to claim 7, characterized in that the operating parameters in the extractive rectification column are: number of trays 35, feed position at tray 25, extractant feed position at tray 4, reflux ratio 3.5:1, and extractant to feed mass ratio 3:

1.

9. The operating parameters in the purification column are: number of trays 39-41, feed position at trays 27-29, reflux ratio 2.5-3.5:1; Preferably, the operating parameters in the purification column are: number of trays is 40, the feed position is tray 28, and the reflux ratio is 3:

1. The method for separating alkanes and α-alkene according to claim 7.

10. Before the raw material and the extractant are charged into the extractive distillation column, they are first preheated, the raw material is preheated to 65 to 100 ° C., and the extractant is preheated to 55 to 85 ° C.; Preferably, before the raw material and the extractant are charged into the extractive distillation column, the raw material is preheated to 68 to 72 ° C. and the extractant is preheated to 58 to 62 ° C.; The method for separating alkanes and α-alkenes according to claim 5, characterized in that, before the raw material and the extractant are charged into an extractive rectification column, preheating is first performed, the raw material being preheated to 93 to 97 ° C, and the extractant being preheated to 78 to 82 ° C.

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