A process and apparatus for separating C6-C12 mono-carbon alpha-olefins from a Fischer-Tropsch synthesis oil

Abstract

The application discloses a method for separating C6-C12 single-carbon alpha-olefins from Fischer-Tropsch synthesis oil products and a device for implementing the method. The method comprises the following steps: performing ordinary rectification, light component removal treatment and more than twice of alkyl-olefin separation treatment on the Fischer-Tropsch synthesis oil products, so that the purity of the obtained alpha-olefin product can be up to more than 90 wt%. The method of the application can not introduce other substances in the separation process, and the process flow is more flexible and the benefit-cost ratio is higher.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of Fischer-Tropsch synthesis oil product separation, and particularly relates to a method for separating single-carbon alpha-olefins from Fischer-Tropsch synthesis oil products, and more particularly to a method for separating C6-C12 single-carbon alpha-olefins from Fischer-Tropsch synthesis oil products. BACKGROUND

[0002] Linear alpha olefins are important organic chemical raw materials and intermediates, and are widely used in many regions and fields.

[0003] C6-C12 linear alpha olefins can be used to produce linear aldehydes by carbonyl synthesis (hydroformylation), and then to produce short-chain fatty acids, carboxylic acids as plasticizers by oxidizing the intermediate aldehyde or linear alcohol; or can be used to prepare surfactants for aqueous detergent formulations (by reacting with benzene to produce linear alkyl benzene (LAB), which is further sulfonated to form linear alkyl benzene sulfonate (LABS), which is a popular relatively low-cost surfactant for household and industrial detergent applications). Among them, for example, 1-decene is mainly used to manufacture poly-alpha-olefin synthetic lubricating oil base oil (PAO) and to be mixed with high-level linear alpha-olefins to manufacture surfactants.

[0004] In industry, the main production routes of linear alpha-olefins are ethylene oligomerization, purification after Fischer-Tropsch synthesis, and the small-scale production route of alcohol dehydration which is currently used in commercial production. With the development and expansion of domestic Fischer-Tropsch synthesis industry, the cost of producing alpha olefins using Fischer-Tropsch oil products is lower, so its prospects are better.

[0005] Patent CN109652111A discloses a device and method for separating olefins from Fischer-Tropsch synthesis oil. The device and method described in the patent are used to remove oxygen-containing compounds and separate alkyl olefins in a partition wall column by extractive distillation. Although the scheme only uses one partition wall column, the column structure and operation are very complex, and the scheme also involves a series of problems such as pretreatment of raw materials and recovery of extractant.

[0006] Patent CN111100683A discloses a method for separating long-chain alkane-olefin. The method described in the patent is used to separate and purify long-chain alpha olefins by deoxidation adsorption and simulated moving bed adsorption. However, the adsorption process needs to use a large amount of adsorbent, the operation of the simulated moving bed is complex, the equipment cost is high, and it is difficult to apply in large-scale industry.

[0007] Patent CN111646876A discloses a method for separating olefins. The method described in the patent mainly uses a composite membrane to separate alkyl olefins, but membrane separation has the disadvantages of high cost, easy pollution and easy breakage.

[0008] In summary, the current method for separating α-olefins from Fischer-Tropsch synthesis oil products has many shortcomings and cannot meet the needs of large-scale industrial applications, and therefore it is necessary to develop a method for efficiently separating α-olefins from Fischer-Tropsch synthesis raw materials suitable for industrial applications. SUMMARY

[0009] The present inventors have provided a method for separating α-olefins from Fischer-Tropsch synthesis oil products, which utilizes a multi-stage separation operation to separate and purify α-olefins, can obtain α-olefins of different carbon numbers, and the purity of the α-olefin product can be as high as 90 wt% or more (even as high as 95% or more). The method has the advantages of high separation purity, simple operation, wide applicability, and environmental friendliness.

[0010] In one aspect, the present application provides a method for separating C6-C12 single-carbon α-olefins from Fischer-Tropsch synthesis oil products, comprising:

[0011] (1) subjecting the Fischer-Tropsch synthesis oil product to ordinary distillation to obtain a mixture of C5-C12 components, subjecting the mixture to ordinary distillation two or more times to obtain a C6-C12 single-carbon fraction;

[0012] (2) subjecting the single-carbon fraction to light-removing treatment to obtain a light component and an α-olefin-rich fraction;

[0013] (3) subjecting the α-olefin-rich fraction to alkylene separation two or more times to obtain an α-olefin product, an alkane product, and an alkene-alkane mixture, and returning the alkene-alkane mixture to alkylene separation.

[0014] In another aspect, the present application provides a device for implementing the above method, comprising:

[0015] a first ordinary distillation column;

[0016] a second ordinary distillation column connected in fluid communication to the first ordinary distillation column, and comprising 1-3 stages of ordinary distillation columns connected in fluid communication, wherein the first stage of ordinary distillation columns is 1, the second stage of ordinary distillation columns and the third stage of ordinary distillation columns are each independently 0-4, and when the second stage of ordinary distillation columns or the third stage of ordinary distillation columns is two or more, the two or more ordinary distillation columns of the same stage are connected in parallel;

[0017] a light-removing column connected in fluid communication to the second ordinary distillation column;

[0018] two or more alkylene separation columns connected in fluid communication to the light-removing column.

[0019] The exemplary schemes of the present application can achieve the following beneficial effects or further other effects or advantages:

[0020] 1. No other substances are introduced in the separation process (such as extractants used in extractive distillation, etc.), no additional three-waste emissions are generated, and no recovery of extractants and other reagents is required.

[0021] 2. The process is simple and flexible, and can be flexibly adjusted according to actual conditions to separate target products (such as setting one group of second ordinary distillation columns to separate only one desired olefin product, or setting two groups of second ordinary distillation columns in parallel to simultaneously separate two desired olefin products; this makes the entire process flow more flexible and has a higher benefit-cost ratio).

[0022] 3. The purity of the separated α-olefin can be as high as 90% or even more than 95%. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are part of the specification and, together with the specific embodiments, provide further explanation of the present application, but are not a limitation of the present application.

[0024] Figure 1 A flow chart showing the exemplary separation method in Example 1 is shown.

[0025] Figure 2 A flow chart showing the exemplary separation method in Example 2 is shown.

[0026] Figure 1 The explanation of each reference sign in the drawings is as follows:

[0027] A first ordinary distillation column; B, C, D, E, F, G second ordinary distillation column; I, J, K, L, M, N, O light-removing column; P11, P12, P21, P22, P31, P32, P41, P42, P51, P52, P61, P62, P71, P72 alkylene separation column.

[0028] 1, 5, 7, 9, 11, 13, 15, 17, 21, 23, 27, 29, 33, 35, 39, 41, 45, 47, 51, 53 overhead stream; 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56 column bottom stream; 19 C6 olefin product; 25 C7 olefin product, 31 C8 olefin product; 37 C9 olefin product; 43 C10 olefin product; 49 C11 olefin product; 55 C12 olefin product. DETAILED DESCRIPTION

[0029] The specific embodiments of the present application are described in detail below. The specific embodiments described herein are merely for the purpose of illustrating and explaining the present application, but not for limiting the present application.

[0030] In one embodiment, the present application provides a method for separating C6-C12 single carbon α-olefins from a Fischer-Tropsch synthesis oil product, comprising:

[0031] (1) subjecting the Fischer-Tropsch synthesis oil product to ordinary distillation to obtain a mixture of C5-C12 components, subjecting the mixture to ordinary distillation for more than twice to obtain a C6-C12 single carbon fraction;

[0032] (2) subjecting the single carbon fraction to light-removing treatment to obtain a light component and an α-olefin-rich fraction;

[0033] (3) subjecting the α-olefin-rich fraction to alkylene separation for more than twice to obtain an α-olefin product, an alkane product and an alkene-alkane mixture, and returning the alkene-alkane mixture to alkylene separation.

[0034] In some preferred embodiments, the Fischer-Tropsch synthesis oil product is a Fischer-Tropsch synthesis light oil. In some more preferred embodiments, the Fischer-Tropsch synthesis light oil has a distillation temperature range of 0-500°C, preferably a distillation temperature range of 20-450°C, and more preferably a distillation temperature range of 50-300°C. In this context, the Fischer-Tropsch synthesis light oil mainly comprises C4-C37 n-alkanes and n-olefins (especially C5-C30 n-alkanes and n-olefins, and particularly C5-C13 n-alkanes and n-olefins), and also contains a small amount of iso-alkanes and internal olefins. The n-olefins refer to straight-chain mono-olefins with a double bond at the terminal position, i.e. α-olefins, and the α-olefins according to the present application are any one or more of C6-C12 α-olefins; single carbon number α-olefins are one of them (e.g. C6 α-olefins, C7 α-olefins, etc.). The internal olefins are α-olefin isomers, i.e. olefins with a double bond not at the terminal position.

[0035] In some embodiments, the Fischer-Tropsch synthesis oil product is subjected to ordinary distillation under the conditions of a theoretical plate number of 20-80, a column top temperature of 180-210°C and a reflux ratio of 1-10 to obtain a mixture of C5-C12 components.

[0036] In some embodiments, the mixture of C5-C12 components is subjected to ordinary distillation for more than twice under the conditions of a theoretical plate number of 40-100 (e.g. 40-80, 50-70), a reflux ratio of 2-10 (e.g. 2-5, 3-5) and a column top temperature of 25-200°C (e.g. 28-200°C, 30-195°C). Preferably, the mixture of C5-C12 components is subjected to ordinary distillation for 2-7 times (e.g. 7 times) to obtain a C6-C12 single carbon fraction.

[0037] In some embodiments, the single carbon fraction is subjected to a light ends removal under conditions of 50-100 theoretical plates (e.g., 60-100, 60-90), a reflux ratio of 3-10, and a column top temperature of 50°C-220°C (e.g., 55°C-220°C, 60°C-215°C).

[0038] In some preferred embodiments, the light ends removal can be performed in a light ends removal column, in which the light ends content in the column bottom material is less than 5%, preferably less than 0.1%. In this context, the light ends removal column can use different light ends removal conditions according to the carbon number of the material entering the column. For example, for the separation of C6olefins, the light ends removal column can be set to have 20-200 theoretical plates, a reflux ratio of 3-25, a column top temperature of 25°C-60°C, and the C5light ends content in the column bottom stream is less than 5%, preferably less than 1%, more preferably less than 0.1%; for the separation of C7olefins, the light ends removal column can be set to have 20-200 theoretical plates, a reflux ratio of 3-25, a column top temperature of 60°C-90°C, and the C6light ends content in the column bottom stream is less than 5%, preferably less than 1%, more preferably less than 0.1%.

[0039] In the present application, the α-olefin-rich fraction obtained after light ends removal does not contain light ends or contains very low light ends.

[0040] In some embodiments, the alkene separation is performed in an alkene separation column.

[0041] In some embodiments, the alkene separation is performed twice or three times.

[0042] In some preferred embodiments, the α-olefin-rich fraction is subjected to a first alkene separation to obtain a crude α-olefin product and an alkane product, and then the crude α-olefin product is subjected to a second alkene separation to obtain an α-olefin product and an alkane-olefin mixture, which is returned to the alkene separation.

[0043] In some further preferred embodiments, the first alkylene separation is performed using a first stage alkylene separation column having a number of theoretical plates of 50-100 (e.g. 60-100, 70-90), a reflux ratio of 4-15 (e.g. 4-12, 5-12), and a top temperature of 50°C-220°C (e.g. 55°C-220°C, 60°C-215°C). In some more preferred embodiments, the first stage alkylene separation column has an olefin content in the column bottom stream (mainly alkanes) of 10% or less, preferably 5% or less, thereby further ensuring a higher yield of a-olefins. In some more preferred embodiments, the first stage alkylene separation column has an a-olefin content in the column top stream (mainly olefins) of 80% or more, preferably 85% or more, thereby further achieving a preliminary enrichment of olefins to ensure a subsequent yield.

[0044] In some further preferred embodiments, the second alkylene separation is performed using a second stage alkylene separation column having a number of theoretical plates of 50-100 (e.g. 60-100, 70-90), a reflux ratio of 4-15 (e.g. 4-15, 5-12), and a top temperature of 40°C-250°C (e.g. 55°C-220°C, 60°C-215°C). In some more preferred embodiments, the second stage alkylene separation column has an a-olefin product content in the column top stream of 90% or more, preferably 95% or more.

[0045] In some preferred embodiments, the column bottom material after the second alkylene separation is all returned for the first alkylene separation.

[0046] As an exemplary scheme, high purity C6-C12 individual carbon a-olefins can be simultaneously separated according to the following steps:

[0047] 1. The Fischer-Tropsch synthesis oil product is subjected to ordinary distillation to obtain a mixture of C5-C12 components; the mixture is subjected to ordinary distillation to obtain a C5-C8 fraction at the top and a C9-C12 fraction at the bottom;

[0048] 2. The C5-C8 fraction obtained above is subjected to ordinary distillation to obtain a C5-C6 fraction at the top and a C7-C8 fraction at the bottom; the C5-C6 fraction obtained is subjected to ordinary distillation to obtain a C5 single carbon fraction at the top and a C6 single carbon fraction at the bottom; at the same time, the C7-C8 fraction obtained is subjected to ordinary distillation to obtain a C7 single carbon fraction at the top and a C8 single carbon fraction at the bottom;

[0049] 3. The C9-C12 fraction obtained above is subjected to ordinary distillation, the overheads of which yield a C9-C10 fraction, and the bottoms of which yield a C11-C12 fraction; the C9-C10 fraction obtained is subjected to ordinary distillation, the overheads of which yield a C9 single carbon fraction, and the bottoms of which yield a C10 single carbon fraction; simultaneously, the C11-C12 fraction obtained is subjected to ordinary distillation, the overheads of which yield a C11 single carbon fraction, and the bottoms of which yield a C12 single carbon fraction;

[0050] 4. The C6 single carbon fraction obtained above is subjected to light ends removal, the bottoms of which yield a C6 α-olefin rich single carbon fraction after light ends removal;

[0051] 5. The C6 α-olefin rich single carbon fraction obtained after light ends removal above is subjected to first alkene separation, the overheads of which yield a C6 α-olefin crude product I, and the bottoms of which yield a C6 alkane product;

[0052] 6. The C6 α-olefin crude product I obtained above is subjected to second alkene separation, the overheads of which yield a high purity C6 α-olefin, and the bottoms of which yield a C6 alkane-olefin mixture, wherein the C6 alkane-olefin mixture is returned to step (5) for alkene separation;

[0053] 7. Each of the C7-C12 single carbon fractions obtained above is subjected to the operations of steps (4) through (6) to yield a high purity single carbon α-olefin of C7-C12, respectively.

[0054] Alternatively, as another example, a single high purity C6-C12 single carbon α-olefin can be obtained by the following steps:

[0055] I. The Fischer-Tropsch synthesis oil product containing the target product is subjected to ordinary distillation, the overheads of which yield a fraction having a carbon number less than that of the target product, and the bottoms of which yield a fraction having a carbon number greater than or equal to that of the target product (i.e., the bottoms stream);

[0056] II. The bottoms stream of step I is subjected to second ordinary distillation, the overheads of which yield a single carbon fraction having the carbon number of the target product, and the bottoms of which yield a fraction having a carbon number greater than that of the target product;

[0057] III. The single carbon fraction having the carbon number of the target product obtained in step II is subjected to light ends removal to yield an α-olefin rich fraction;

[0058] IV. The α-olefin rich fraction obtained in step III is subjected to first alkene separation to yield an overhead stream 1 and a bottoms stream 1, wherein the overhead stream 1 consists mostly of the target carbon number olefin and a small amount of the alkane having the carbon number of the target product; and the bottoms stream 1 consists of the alkane having the carbon number of the target product;

[0059] V. subjecting the step IV overhead stream 1 to a second alkylene separation to obtain an overhead stream 2 and a bottoms stream 2, wherein the overhead stream 2 contains target carbon number olefins at a purity of 90% or more, and the remainder is alkane having the target product carbon number; and the bottoms stream 2 contains a mixture of alkane having the target product carbon number and target carbon number olefins, and the bottoms stream 2 is returned to step IV for further alkylene separation;

[0060] VI. subjecting the step V overhead stream 2 to a third alkylene separation to obtain an overhead stream 3 and a bottoms stream 3, wherein the overhead stream 3 contains target carbon number olefins at a purity of 95% or more, and the remainder is alkane having the target product carbon number; and the bottoms stream 3 contains a mixture of alkane having the target product carbon number and target carbon number olefins, and the bottoms stream 3 is returned to step IV for further alkylene separation.

[0061] In one embodiment, the present application provides a device for implementing the above-mentioned method, comprising:

[0062] a first common rectifying column;

[0063] a second common rectifying column, which is connected to the first common rectifying column in fluid communication, and the second common rectifying column comprises 1-3 stages of common rectifying columns connected in fluid communication, wherein the first stage of common rectifying column is 1, the second stage of common rectifying column and the third stage of common rectifying column are each independently 0-4, and when the second stage of common rectifying column or the third stage of common rectifying column is more than 2, the two or more common rectifying columns of the same stage are connected in parallel;

[0064] a light-removing column, which is connected to the second common rectifying column in fluid communication;

[0065] two or more alkylene separation columns, which are connected to the light-removing column in fluid communication.

[0066] In some embodiments, the first common rectifying column has a theoretical plate number of 20-80 and a reflux ratio of 1-10.

[0067] In some embodiments, the second common rectifying column has a theoretical plate number of 40-100 and a reflux ratio of 2-20.

[0068] In some embodiments, the second ordinary rectification column comprises one stage of ordinary rectification column, thereby achieving separation of a single single-carbon fraction. In some embodiments, the second ordinary rectification column comprises two stages of ordinary rectification column, wherein the first stage of ordinary rectification column is one, and the second stage of ordinary rectification column is one, two, three, or four, thereby achieving separation of one or more (e.g., two, three, four, five, six, or seven) single-carbon fractions. In some embodiments, the second ordinary rectification column comprises three stages of ordinary rectification column, wherein the first stage of ordinary rectification column is one, the second stage of ordinary rectification column is one or two, and the third stage of ordinary rectification column is one, two, three, or four, thereby achieving separation of one or more (e.g., two, three, four, five, six, or seven) single-carbon fractions.

[0069] In some embodiments, the light-removing column has a theoretical plate number of 50-100 plates and a reflux ratio of 3-10.

[0070] In some embodiments, the alkylene separation column is two or three. In some preferred embodiments, the alkylene separation column has a theoretical plate number of 50-100 plates and a reflux ratio of 4-15. In this context, the theoretical plate number and the reflux ratio between two or more alkylene separation columns connected to the same light-removing column can be the same or different from each other. For example, as shown in the present application, two alkylene separation columns connected in series are connected to the light-removing column, thereby performing two or more alkylene separations on the α-olefin-rich fraction from the light-removing column. Figure 1

[0071] The method of the present application can simultaneously separate all single-carbon olefins of C6-C12, or only separate the desired single-carbon-number olefin as needed, through multi-column combined operation, thereby flexibly adjusting the process according to actual needs.

[0072] The present application has the characteristics of mature and reliable technology, simple equipment operation, and environmental friendliness without using additional solvents and adsorbents.

[0073] Next, exemplary embodiments of the present application will be described by the following numbered paragraphs:

[0074] 1. A method for separating single-carbon α-olefins of C6-C12 from a Fischer-Tropsch synthesis oil product, comprising:

[0075] (1) subjecting the Fischer-Tropsch synthesis oil product to ordinary rectification to obtain a mixture of C5-C12 components, and subjecting the mixture to two or more ordinary rectifications to obtain single-carbon fractions of C6-C12;

[0076] (2) subjecting the single-carbon fractions to light-removing treatment to obtain a light component and an α-olefin-rich fraction;

[0077] ​(3) The α-olefin-rich fraction is subjected to alkane-alkene separation more than twice to obtain α-olefin products, alkane products and alkene-alkane mixtures, and the alkene-alkane mixtures are returned for alkane-alkene separation.

[0078] 2. The method as described in paragraph 1, wherein the Fischer-Tropsch synthetic oil is a Fischer-Tropsch light synthetic oil.

[0079] 3. The method as described in paragraph 1 or 2, wherein the distillation temperature of the Fischer-Tropsch light oil is 0-500°C.

[0080] 4. The method described in any of paragraphs 1-3, wherein the Fischer-Tropsch synthetic oil is subjected to ordinary distillation under the conditions of 20-80 theoretical plates, a top temperature of 180℃-210℃, and a reflux ratio of 1-10 to obtain a mixture of the C5-C12 components.

[0081] 5. The method described in any of paragraphs 1-4, wherein the mixture of C5-C12 components is subjected to the above-mentioned ordinary distillation more than twice under the conditions of 40-100 theoretical plates, reflux ratio of 2-10, and top temperature of 25℃-200℃.

[0082] 6. The method described in any of paragraphs 1-5, wherein the single carbon fraction is subjected to the light-weight removal treatment under the conditions of 50-100 theoretical plates, a reflux ratio of 3-10, and a top temperature of 50℃-220℃.

[0083] 7. The method as described in any of paragraphs 1-6, wherein the light component removal treatment is carried out in a light component removal tower, wherein the light component content in the bottom material of the tower is less than 5%.

[0084] 8. The method described in any of paragraphs 1-7, wherein the alkane-ene separation is carried out in an alkane-ene separation tower.

[0085] 9. The method as described in any of paragraphs 1-8, wherein the alkane separation is performed two or three times.

[0086] 10. The method as described in any of paragraphs 1-9, wherein the α-olefin-rich fraction is subjected to a first alkene-alkene separation to obtain a crude α-olefin product and an alkane product, and then the crude α-olefin product is subjected to a second alkene-alkene separation to obtain an α-olefin product and an alkene-alkane mixture, the alkene-alkane mixture being returned for alkene-alkene separation.

[0087] 11. The method as described in paragraph 10, wherein the first alkane-ene separation is carried out using a first-stage alkane-ene separation tower, wherein the theoretical number of plates in the first-stage alkane-ene separation tower is 50-100, the reflux ratio is 4-15, and the top temperature of the tower is 50℃-220℃.

[0088] 12. The method of paragraph 11, wherein the olefin content of the column bottoms stream of the first stage alkylene separation column is 10% or less.

[0089] 13. The method of paragraph 11 or 12, wherein the content of alpha-olefins in the overhead stream of the first stage alkylene separation column is 80% or more.

[0090] 14. The method of any one of paragraphs 10-13, wherein the second alkylene separation is performed using a second stage alkylene separation column having a number of theoretical plates of 50-100, a reflux ratio of 4-15, and an overhead temperature of 40°C-250°C.

[0091] 15. The method of paragraph 14, wherein the content of alpha-olefin product in the overhead stream of the second stage alkylene separation column is 90% or more.

[0092] 16. The method of any one of paragraphs 10-15, wherein the column bottoms material obtained after the second alkylene separation is returned in its entirety for the first alkylene separation.

[0093] 17. An apparatus for carrying out the method of any one of paragraphs 1-16, comprising:

[0094] a first ordinary rectifying column;

[0095] a second ordinary rectifying column, which is connected in fluid communication to the first ordinary rectifying column, and which comprises 1-3 stages of ordinary rectifying columns connected in fluid communication, wherein the first stage of ordinary rectifying columns is 1, the second stage of ordinary rectifying columns and the third stage of ordinary rectifying columns are each independently 0-4, and when there are two or more of the second stage of ordinary rectifying columns or the third stage of ordinary rectifying columns, two or more of the same stage of ordinary rectifying columns are connected in parallel;

[0096] a light-removing column, which is connected in fluid communication to the second ordinary rectifying column;

[0097] two or more alkylene separation columns, which are connected in fluid communication to the light-removing column.

[0098] 18. The apparatus of paragraph 17, wherein the first ordinary rectifying column has a number of theoretical plates of 20-80 and a reflux ratio of 1-10.

[0099] 19. The apparatus of paragraph 17 or 18, wherein the second ordinary rectifying column has a number of theoretical plates of 40-100 and a reflux ratio of 2-20.

[0100] 20. The apparatus of any of paragraphs 17-19, wherein the second conventional rectifier column comprises a 1 stage conventional rectifier column.

[0101] 21. The apparatus of any of paragraphs 17-19, wherein the second conventional rectifier column comprises a 2 stage conventional rectifier column, wherein the 1 stage conventional rectifier column is 1 and the 2 stage conventional rectifier column is 1, 2, 3, or 4.

[0102] 22. The apparatus of any of paragraphs 17-19, wherein the second conventional rectifier column comprises a 3 stage conventional rectifier column, wherein the 1 stage conventional rectifier column is 1, the 2 stage conventional rectifier column is 1 or 2, and the 3 stage conventional rectifier column is 1, 2, 3, or 4.

[0103] 23. The apparatus of any of paragraphs 17-22, wherein the de-light column has a theoretical plate count of 50-100 and a reflux ratio of 3-10.

[0104] 24. The apparatus of any of paragraphs 17-23, wherein the alkylene separation column is 2 or 3.

[0105] 25. The apparatus of any of paragraphs 17-24, wherein the alkylene separation column has a theoretical plate count of 50-100 and a reflux ratio of 4-15.

[0106] The application is further illustrated by the following examples, but the scope of the application is not limited thereto.

[0107] Examples

[0108] Unless otherwise indicated, the reagents, materials and apparatuses referred to in the following examples are commercially available and conventional in the art; the procedures referred to in the following examples are conventional and can be found in published patents, patent applications and publications.

[0109] Example 1

[0110] C6 olefin product-stream 19, C7 olefin product-stream 25, C8 olefin product-stream 31, C9 olefin product-stream 37, C10 olefin product-stream 43, C11 olefin product-stream 49, and C12 olefin product-stream 55 are produced simultaneously.

[0111] The flow of the separation process is shown in Figure 1As shown, the Fischer-Tropsch synthesis light oil is used as raw material, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 20-80, the overhead temperature is 180-210°C, and the reflux ratio is 2-10, to obtain a mixture of C5-C12 components. The mixture of C5-C12 components enters the ordinary distillation column A, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 64°C, to obtain an overhead stream 1 and a column bottom stream 2;

[0112] The overhead stream 1 enters the ordinary distillation column B, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 46°C, to obtain an overhead stream 3 and a column bottom stream 4;

[0113] The column bottom stream 2 enters the ordinary distillation column C, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 150°C, to obtain an overhead stream 5 and a column bottom stream 6;

[0114] The overhead stream 3 enters the ordinary distillation column D, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 32.5°C, to obtain an overhead stream 7 and a column bottom stream 8,

[0115] The column bottom stream 4 enters the ordinary distillation column E, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 95°C, to obtain an overhead stream 9 and a column bottom stream 10;

[0116] The overhead stream 5 enters the ordinary distillation column F, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 147°C, to obtain an overhead stream 11 and a column bottom stream 12;

[0117] The column bottom stream 6 enters the ordinary distillation column G, and the ordinary distillation is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 193°C, to obtain an overhead stream 13 and a column bottom stream 14;

[0118] The column bottom stream 8 enters the light-removing column I, and the light-removing treatment is carried out under the conditions that the theoretical plate number is 60, the reflux ratio is 3, and the overhead temperature is 63.6°C, to obtain an overhead stream 15 and a column bottom stream 16, wherein the C6 olefin content in the column bottom stream 16 is 74%;

[0119] The column bottom stream 16 enters the alkylene separation column P11, and the first alkylene separation is carried out under the conditions that the theoretical plate number is 80, the reflux ratio is 5, and the overhead temperature is 63.7°C, to obtain an overhead stream 17 and a column bottom stream 18, wherein the C6 olefin content in the overhead stream 17 is 86.2%;

[0120] The overhead stream 17 enters the alkylene separation column P12, and is subjected to a second alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 63.1°C, to obtain an overhead stream 19 and a column bottom stream 20, wherein the C6 alkylene content in the overhead stream 19 is 99.5%, and the column bottom stream 20 is returned to the alkylene separation column P11 to be recycled for alkylene separation;

[0121] The overhead stream 9 enters the light-removing column J, and is subjected to light-removing treatment under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 90°C, to obtain an overhead stream 21 and a column bottom stream 22, wherein the C7 alkylene content in the column bottom stream 22 is 84.8%;

[0122] The column bottom stream 22 enters the alkylene separation column P21, and is subjected to a first alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 94°C, to obtain an overhead stream 23 and a column bottom stream 24, wherein the C7 alkylene content in the column bottom stream 23 is 86.4%;

[0123] The column bottom stream 23 enters the alkylene separation column P22, and is subjected to a second alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 93.6°C, to obtain an overhead stream 25 and a column bottom stream 26, wherein the C7 alkylene content in the overhead stream 25 is 95%, and the column bottom stream 26 is returned to the alkylene separation column P21 to be recycled for alkylene separation;

[0124] The column bottom stream 10 enters the light-removing column K, and is subjected to light-removing treatment under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 119°C, to obtain an overhead stream 27 and a column bottom stream 28, wherein the C8 alkylene content in the column bottom stream 28 is 76.8%;

[0125] The column bottom stream 28 enters the alkylene separation column P31, and is subjected to a first alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 121.1°C, to obtain an overhead stream 29 and a column bottom stream 30, wherein the C8 alkylene content in the overhead stream 29 is 90.8%;

[0126] The overhead stream 29 enters the alkylene separation column P32, and is subjected to a second alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 7, and an overhead temperature of 120.7°C, to obtain an overhead stream 31 and a column bottom stream 32, wherein the C8 alkylene content in the overhead stream 31 is 96.6%, and the column bottom stream 32 is returned to the alkylene separation column P31 to be recycled for alkylene separation;

[0127] The overhead stream 11 enters the light-removing column L, and is subjected to light-removing treatment under the conditions of 80 theoretical plates, a reflux ratio of 5, and an overhead temperature of 140.7°C, to obtain an overhead stream 33 and a column bottom stream 34, wherein the C9 alkylene content in the column bottom stream 34 is 73.4%;

[0128] The column bottom stream 34 enters the alkylene separation column P41, and a first alkylene separation is carried out under the conditions of 80 theoretical plates, a reflux ratio of 7, and a column top temperature of 146.6°C, to obtain a column top stream 35 and a column bottom stream 36, wherein the C9 alkylene content in the column top stream 34 is 87.4%;

[0129] The column top stream 35 enters the alkylene separation column P42, and a second alkylene separation is carried out under the conditions of 80 theoretical plates, a reflux ratio of 9, and a column top temperature of 146.2°C, to obtain a column top stream 37 and a column bottom stream 38, wherein the C9 alkylene content in the column top stream 37 is 96.4%, and the column bottom stream 38 is returned to the alkylene separation column P41 to circulate and carry out alkylene separation;

[0130] The column bottom stream 12 enters the light-removing column M, and a light-removing treatment is carried out under the conditions of 80 theoretical plates, a reflux ratio of 5, and a column top temperature of 170.4°C, to obtain a column top stream 39 and a column bottom stream 40, wherein the C10 alkylene content in the column bottom stream 40 is 72.3%;

[0131] The column bottom stream 40 enters the alkylene separation column P51, and a first alkylene separation is carried out under the conditions of 80 theoretical plates, a reflux ratio of 7, and a column top temperature of 170.3°C, to obtain a column top stream 41 and a column bottom stream 42, wherein the C10 alkylene content in the column top stream 41 is 86.1%;

[0132] The column top stream 41 enters the alkylene separation column P52, and a second alkylene separation is carried out under the conditions of 80 theoretical plates, a reflux ratio of 10, and a column top temperature of 170.0°C, to obtain a column top stream 43 and a column bottom stream 44, wherein the C10 alkylene content in the column top stream 43 is 95.9%, and the column bottom stream 44 is returned to the alkylene separation column P51 to circulate and carry out alkylene separation;

[0133] The column top stream 13 enters the light-removing column N, and a light-removing treatment is carried out under the conditions of 80 theoretical plates, a reflux ratio of 7, and a column top temperature of 192.3°C, to obtain a column top stream 45 and a column bottom stream 46, wherein the C11 alkylene content in the column bottom stream 46 is 70.4%;

[0134] The column bottom stream 46 enters the alkylene separation column P61, and a first alkylene separation is carried out under the conditions of 80 theoretical plates, a reflux ratio of 9, and a column top temperature of 192.2°C, to obtain a column top stream 47 and a column bottom stream 48, wherein the C11 alkylene content in the column top stream 47 is 86.2%;

[0135] The overhead stream 47 enters the alkylene separation column P62, and is subjected to a second alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 10, and an overhead temperature of 191.8°C, to obtain an overhead stream 49 and a column bottom stream 50, wherein the C11 olefin content in the overhead stream 49 is 95.6%, and the column bottom stream 50 enters the alkylene separation column P61 to circulate and be subjected to alkylene separation;

[0136] The column bottom stream 14 enters the light-removing column O, and is subjected to light-removing treatment under the conditions of 80 theoretical plates, a reflux ratio of 10, and an overhead temperature of 212.5°C, to obtain an overhead stream 51 and a column bottom stream 52, wherein the C12 olefin content in the column bottom stream 52 is 45.1%;

[0137] The column bottom stream 52 enters the alkylene separation column P71, and is subjected to a first alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 10, and an overhead temperature of 212.6°C, to obtain an overhead stream 53 and a column bottom stream 54, wherein the C12 olefin content in the overhead stream 53 is 82.4%;

[0138] The stream 53 enters the alkylene separation column P72, and is subjected to a second alkylene separation under the conditions of 80 theoretical plates, a reflux ratio of 12, and an overhead temperature of 212.2°C, to obtain an overhead stream 55 and a column bottom stream 56, wherein the C12 olefin content in the overhead stream 55 is 93.1%, and the column bottom stream 56 enters the alkylene separation column P71 to circulate and be subjected to alkylene separation.

[0139] The relevant analysis results of the above streams are as follows (F represents Fischer-Tropsch light oil):

[0140] The conditions of each stream involved in the separation process of C6 olefins are as follows:

[0141] Stream No. ≤ C5 (wt%) C6 olefins (wt%) C6 paraffins (wt%) ≥ C7 (wt%) F 8.9 9.4 3.4 78.25 1 18.2 19.2 7.0 55.6 3 41.4 43.6 0 0 8 0 74.2 25.8 0 16 0 74.0 26.0 0 17 0 86.2 13.8 0 19 0 99.5 0.5 0

[0142] The conditions of each stream involved in the separation process of C7 olefins are as follows:

[0143] Stream No. ≤ C6 (wt%) C7 olefins (wt%) C7 paraffins (wt%) ≥ C8 (wt%) F 21.8 10.5 3.5 64.3 1 44.4 21.4 7.0 27.2 4 0.7 38.2 12.6 48.5 9 1.4 74.8 23.8 0 22 0 84.8 26.7 0 23 0 86.4 11.2 0 25 0 95.0 3.9 0

[0144] The conditions of each stream involved in the separation process of C8 olefins are as follows:

[0145] Stream No. ≤ C7 (wt%) C8 olefins (wt%) C8 paraffins (wt%) ≥ C9 (wt%) F 35.7 10.5 3.3 50.6 1 72.8 21.3 5.9 0 4 51.5 38.0 10.5 0 10 0 77.5 21.5 0 28 0 76.8 22.8 0 29 0 90.8 8.7 0 31 0 96.6 2.5 0

[0146] The conditions of each stream involved in the separation process of C9 olefins are as follows:

[0147] Stream No. ≤ C8 (wt%) C9 olefins (wt%) C9 paraffins (wt%) ≥ C10 (wt%) F 49.4 9.8 3.1 37.6 2 0.9 19.3 6.1 73.8 5 1.7 38.5 12.2 47.5 11 3.3 73.4 23.2 0.1 34 0.3 73.4 26.2 0.1 35 0.3 87.4 12.2 0 37 0.7 96.4 2.9 0

[0148] The conditions of each stream involved in the separation process of C10 olefins are as follows:

[0149] Stream No. ≤ C9 (wt%) C10 olefins (wt%) C10 paraffins (wt%) ≥ C11 (wt%) F 62.4 9.0 3.0 25.6 2 26.2 17.5 6.0 50.3 5 40.3 35.1 11.9 0.5 12 0 73.8 25.1 1.1 40 0 72.3 26.4 1.2 41 0 86.1 13.9 0 43 0 95.9 4.1 0

[0150] The situation of each stream involved in the separation process of C11 olefins:

[0151] Stream No. ≤ C10 (wt%) C11 olefins (wt%) C11 paraffins (wt%) ≥ C12 (wt%) F 74.4 8.0 3.0 14.7 2 49.7 15.6 5.8 28.8 6 0 30.8 11.7 57.5 13 0 71.5 27.1 1.4 46 0 70.4 28.0 1.5 47 0 86.2 13.8 0 49 0 95.6 4.4 0

[0152] The situation of each stream involved in the separation process of C12 olefins:

[0153]

[0154]

[0155] Example 2

[0156] C8 olefins are produced from a Fischer-Tropsch light oil as raw material, and the separation process is as shown in Figure 2

[0157] A mixture of C5-C12 components is obtained by subjecting the Fischer-Tropsch oil product to ordinary rectification under the conditions of a theoretical plate number of 20-80, a column top temperature of 180°C-210°C, and a reflux ratio of 2-10.

[0158] The above mixture of C5-C12 components is subjected to ordinary rectification in ordinary rectification column 1 under the conditions of a theoretical plate number of 60, a reflux ratio of 5, and a column top temperature of 84.5°C, to obtain column top stream 1 and column bottom stream 2, wherein the content of ≤C7 components in column bottom stream 2 is 0.

[0159] Column bottom stream 2 is subjected to ordinary rectification in ordinary rectification column 2 under the conditions of a theoretical plate number of 60, a reflux ratio of 5, and a column top temperature of 125°C, to obtain column top stream 3 and column bottom stream 4, wherein the content of C8 olefins in column top stream 3 is 75.54%.

[0160] Column top stream 3 is subjected to light-removing treatment in light-removing column 3 under the conditions of a theoretical plate number of 80, a reflux ratio of 10, and a column top temperature of 123.1°C, to obtain column top stream 5 and column bottom stream 6, wherein the content of C8 olefins in column bottom stream 6 is 5.96%.

[0161] Column top stream 5 is subjected to first alkylene separation in alkylene separation column 4 under the conditions of a theoretical plate number of 80, a reflux ratio of 10, and a column top temperature of 121.4°C, to obtain column top stream 7 and column bottom stream 8, wherein the content of C8 olefins in column top stream 7 is 99.05%.

[0162] Column top stream 7 is subjected to second alkylene separation in alkylene separation column 5 under the conditions of a theoretical plate number of 80, a reflux ratio of 10, and a column top temperature of 121.4°C, to obtain column top stream 9 and column bottom stream 10, wherein the content of C8 olefins in column top stream 9 is 99.9%.

[0163] ​The results of the analysis of each stream are as follows:

[0164] The conditions of each stream involved in the separation process of C8 olefins are as follows:

[0165]

[0166]

Claims

1. A method for separating C6-C12 mono-carbon α-olefins from a Fischer-Tropsch synthesis oil product, comprising: (1) subjecting the Fischer-Tropsch synthesis oil product to ordinary distillation to obtain a mixture of C5-C12 components, and subjecting the mixture to ordinary distillation for two or more times to obtain a mono-carbon fraction of C6-C12; (2) subjecting the mono-carbon fraction to light-removing treatment under the conditions of a theoretical plate number of 50-100, a reflux ratio of 3-10, and a column top temperature of 50-220°C to obtain a light component and an α-olefin-rich fraction; (3) subjecting the α-olefin-rich fraction to alkylene separation for two or more times, wherein the α-olefin-rich fraction is subjected to first alkylene separation to obtain a crude α-olefin product and an alkane product, and then the crude α-olefin product is subjected to second alkylene separation to obtain an α-olefin product and an alkane-olefin mixture, which is returned to the alkylene separation, wherein the first alkylene separation is performed by using a first-stage alkylene separation column having a theoretical plate number of 50-100, a reflux ratio of 4-15, and a column top temperature of 50-220°C, and the second alkylene separation is performed by using a second-stage alkylene separation column having a theoretical plate number of 50-100, a reflux ratio of 4-15, and a column top temperature of 40-250°C.

2. The method of claim 1, wherein, The Fischer-Tropsch synthesis oil product is a Fischer-Tropsch synthesis light oil.

3. The method of claim 2, wherein, The Fischer-Tropsch synthesis light oil has a distillation temperature range of 0-500°C.

4. The method of any one of claims 1-3, wherein, The Fischer-Tropsch synthesis oil product is subjected to ordinary distillation under the conditions of a theoretical plate number of 20-80, a column top temperature of 180-210°C, and a reflux ratio of 1-10 to obtain the mixture of C5-C12 components.

5. The method of any one of claims 1-3, wherein, The mixture of C5-C12 components is subjected to the ordinary distillation for two or more times under the conditions of a theoretical plate number of 40-100, a reflux ratio of 2-10, and a column top temperature of 25-200°C.

6. The method of any one of claims 1-3, wherein, The light-removing treatment is performed in a light-removing column, wherein the content of light components in the column bottom material is less than 5%.

7. The method of any one of claims 1-3, wherein, The alkylene separation is performed for two or three times.

8. The method of claim 1, wherein, The content of olefins in the column bottom stream of the first-stage alkylene separation column is less than 10%.

9. The method of claim 1 or 8, wherein, The content of α-olefins in the column top stream of the first-stage alkylene separation column is more than 80%.

10. The method of claim 1, wherein, The content of the α-olefin product in the column top stream of the second-stage alkylene separation column is more than 90%.

11. The method of any one of claims 1-3, wherein, The column bottom material obtained after the second alkylene separation is returned to the first alkylene separation.

12. An apparatus for implementing the method of any one of claims 1-11, comprising: a first ordinary distillation column; a second ordinary distillation column, which is connected in fluid communication to the first ordinary distillation column, and which comprises 1-3 stages of ordinary distillation columns connected in fluid communication, wherein the first stage of ordinary distillation columns is 1, the second stage of ordinary distillation columns and the third stage of ordinary distillation columns are each independently 0-4, and when there are two or more of the second stage of ordinary distillation columns or the third stage of ordinary distillation columns, two or more of the same stage of ordinary distillation columns are connected in parallel. a light-removing column connected to the second common rectifying column in fluid communication, wherein the light-removing column has a theoretical plate number of 50-100 and a reflux ratio of 3-10; two or more alkylene separation columns connected to the light-removing column in fluid communication, wherein the alkylene separation column has a theoretical plate number of 50-100 and a reflux ratio of 4-15.

13. The apparatus of claim 12, wherein, The first common rectifying column has a theoretical plate number of 20-80 and a reflux ratio of 1-10.

14. The apparatus of claim 12 or 13, wherein, The second common rectifying column has a theoretical plate number of 40-100 and a reflux ratio of 2-20.

15. The apparatus of claim 12 or 13, wherein, The second common rectifying column comprises a first-stage common rectifying column.

16. The apparatus of claim 12 or 13, wherein, The second common rectifying column comprises a first-stage common rectifying column and a second-stage common rectifying column, wherein the first-stage common rectifying column is one, and the second-stage common rectifying column is one, two, three, or four.

17. The apparatus of claim 12 or 13, wherein, The second common rectifying column comprises a first-stage common rectifying column, a second-stage common rectifying column, and a third-stage common rectifying column, wherein the first-stage common rectifying column is one, the second-stage common rectifying column is one or two, and the third-stage common rectifying column is one, two, three, or four.

18. The apparatus of claim 12 or 13, wherein, The alkylene separation column is two or three.

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