Method for separating 1-heptene from Fischer-Tropsch synthesis oil and 1-heptene product

Abstract

The invention discloses a method for separating 1-heptene from Fischer-Tropsch synthetic oil and a 1-heptene product, and relates to the technical field of petrochemical industry. The method comprises the following steps: pre-cutting Fischer-Tropsch synthetic oil to obtain a C7 fraction; the C7 fraction is subjected to deacidification, and a deacidified fraction is obtained; performing etherification treatment on the deacidified fraction to obtain an intermediate product; extracting and deoxidizing the intermediate product to obtain deoxidized oil; carrying out extractive distillation on the deoxidized oil to obtain a C7 olefin-rich component; according to the present invention, the C7 olefin-rich component is sequentially subjected to precise rectification and adsorption deoxidation to obtain the 1-heptene product, such that the high-purity 1-heptene product can be effectively separated, and the yield of the target product 1-heptene is improved.

Description

Technical Field

[0001] The present invention belongs to the field of petrochemical industry, and in particular, relates to a method for separating 1-heptene from Fischer-Tropsch synthetic oil and a 1-heptene product. Background Art

[0002] 1-heptene, as an important chemical raw material, can be used as an ideal raw material for functionalized graphite nanosheets, can be directly used as a fragrance, and can also be used to produce n-octanol, plasticizers, stabilizers, fragrance intermediates, etc., with good application value and development prospects. Fischer-Tropsch synthesis naphtha has the advantage of being rich in α-olefins (content>50%), which is conducive to obtaining 1-heptene with high added value. However, the composition of Fischer-Tropsch synthesis naphtha is complex. In addition to 1-heptene, it also contains tertiary carbon olefins, organic acids, and oxygen-containing compounds such as alcohols, aldehydes, ketones, and esters. The presence of these substances will produce a large amount of by-products in the downstream conversion process, reducing the purity and yield of the product. Therefore, how to improve the purity and yield of 1-heptene is a technical problem that needs to be solved in this field. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for separating 1-heptene from Fischer-Tropsch synthetic oil and a 1-heptene product, so as to solve the problem in the prior art that tertiary carbon olefins, organic acids and oxygen-containing compounds in Fischer-Tropsch synthetic oil are not completely removed, resulting in low purity and low yield of 1-heptene.

[0004] In order to achieve the above object, according to one aspect of the present invention, a method for separating 1-heptene from Fischer-Tropsch synthetic oil is provided, comprising the following steps:

[0005] S1, pre-cutting the Fischer-Tropsch synthetic oil to obtain a C7 fraction;

[0006] S2, deacidifying the C7 fraction to obtain a deacidified fraction;

[0007] S3, etherifying the deacidified fraction to obtain an intermediate product;

[0008] S4, extracting and deoxygenating the intermediate product to obtain deoxygenated oil;

[0009] S5, extracting and distilling the deoxygenated oil to obtain a C7 olefin-rich component;

[0010] S6, sequentially subjecting the C7 olefin-rich component to precise distillation and adsorption deoxygenation to obtain a 1-heptene product.

[0011] Further, the pre-cutting includes a first pre-cutting, a second pre-cutting and a third pre-cutting; S1 includes:

[0012] S11, feeding the Fischer-Tropsch synthetic oil to a C5 cutting tower, and after a first pre-cutting, obtaining a C5 fraction at the top of the tower and a C5+ fraction at the bottom of the tower;

[0013] S12, feeding the C5+ fraction segment to a C6 cutting tower, and after a second pre-cutting, cutting at the top of the tower to obtain a C6 fraction, and obtaining a C6+ fraction segment at the bottom of the tower;

[0014] S13, feeding the C6+ fraction to a C7 cutting tower, and after the third pre-cutting, cutting at the top of the tower to obtain a C7 fraction, and obtaining a C7+ fraction section at the bottom of the tower;

[0015] Preferably, the number of plates of the C5 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 20 to 30°C, and the bottom temperature is 90 to 130°C;

[0016] Preferably, the number of plates of the C6 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 55 to 65°C, and the bottom temperature is 110 to 135°C;

[0017] Preferably, the number of plates of the C7 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 85 to 95°C, and the bottom temperature is 140 to 165°C.

[0018] Furthermore, S2 includes:

[0019] The C7 fraction is mixed with alkali solution in a deacidification tower, and after deacidification, a deacidified fraction is obtained; the deacidified fraction is washed with water in a deacidification water washing tower to obtain a deacidified fraction;

[0020] Preferably, the alkaline substance in the alkali solution includes at least one of potassium hydroxide, sodium hydroxide, sodium carbonate and potassium carbonate, and the mass concentration of the alkaline substance in the alkali solution is 2% to 8%.

[0021] Furthermore, S3 includes:

[0022] The deacidified fraction is mixed with the low-carbon alcohol in an etherification reaction distillation tower, and after etherification treatment, an intermediate product is obtained at the top of the etherification reaction distillation tower, and an ether compound is obtained at the bottom of the tower;

[0023] Preferably, the top temperature of the etherification reaction distillation tower is 85-95°C, and the bottom temperature is 110-130°C;

[0024] Preferably, the low-carbon alcohol includes at least one of methanol, ethanol, and propanol;

[0025] More preferably, the low carbon alcohol is methanol;

[0026] Preferably, the etherification reaction distillation tower is loaded with a catalyst, and the catalyst includes at least one of a strongly acidic cation exchange resin, a heteropolyacid catalyst, and a molecular sieve catalyst.

[0027] Furthermore, S4 includes:

[0028] S41, the intermediate product is contacted with the first extractant in reverse order in an extracting and deoxygenating tower, and after extracting and deoxygenating, a deoxygenated oil and an extractant containing an oxygenate are obtained;

[0029] S42, feeding the oxygenate-containing extractant into the first extractant regeneration tower, and obtaining a first recovered extractant through a first regeneration treatment; and returning the first regenerated extractant to the extraction deoxygenation tower.

[0030] Further, the temperature inside the extractive deoxygenation tower is 30-50° C.; and / or,

[0031] The first extractant regeneration tower has a plate number of 20 to 50, a reflux ratio of 2 to 8, a tower top temperature of 80 to 150° C., and a tower bottom temperature of 150 to 200° C.; and / or,

[0032] The first extractant includes at least one of methanol, ethanol, acetonitrile, dimethyl sulfoxide, nitrogen methyl pyrrolidone, N,N-dimethylformamide, ethylene glycol, 1,4-butanediol, cyclopentane sulfone, and propylene glycol; and / or,

[0033] The volume ratio of the first extractant to the intermediate product is (1-12):1;

[0034] Preferably, the first extractant is a mixed system of sulfolane and propylene glycol, and the volume ratio of sulfolane to propylene glycol is (2-4):1.

[0035] Furthermore, S5 includes:

[0036] S51, making the deoxygenated oil contact with the second extractant in a extractive distillation tower in reverse order, after extractive distillation, obtaining an alkane-rich component at the top of the extractive distillation tower, and obtaining an extractant containing C7 olefin-rich olefins at the bottom of the tower;

[0037] S52, feeding the C7 olefin-rich extractant into a second extractant regeneration tower, and obtaining a second regenerated extractant at the top of the second extractant regeneration tower after a second regeneration treatment, and obtaining a C7 olefin-rich component at the bottom of the tower;

[0038] S53, returning the second regenerated extractant to the extractive distillation tower;

[0039] Preferably, the number of plates of the extractive distillation tower is 30 to 60, the reflux ratio is 2 to 12, the top temperature is 80 to 150° C., and the bottom temperature is 150 to 200° C.;

[0040] Preferably, the second extractant regeneration tower has a plate number of 20 to 50, a reflux ratio of 2 to 8, a top temperature of 80 to 150° C., and a bottom temperature of 180 to 230° C.

[0041] Further, the second extractant includes at least one of nitrogen methyl pyrrolidone, N,N-dimethylformamide, ethylene glycol, 1,4-butanediol, propylene glycol, nitrogen morpholine, and 1,4-butyrolactone;

[0042] More preferably, the second extractant is a mixed system of nitrogen methyl pyrrolidone and 1,4-butyrolactone, and the volume ratio of nitrogen methyl pyrrolidone to 1,4-butyrolactone is (5-10):1.

[0043] Furthermore, S6 includes:

[0044] S61, feeding the C7 olefin-rich component into a precision distillation tower, and obtaining a crude 1-heptene product at the top of the precision distillation tower after precision distillation;

[0045] S62, feeding the crude 1-hexene product into an adsorption deoxygenation tower, and obtaining a 1-heptene product after adsorption deoxygenation;

[0046] Preferably, the number of plates of the precision distillation tower is 30 to 70, the reflux ratio is 2 to 12, the tower top temperature is 80 to 150° C., and the tower bottom temperature is 150 to 200° C.;

[0047] Preferably, the adsorption deoxidation tower is loaded with an adsorbent, and the adsorbent includes at least one of silica gel, clay, diatomaceous earth, alumina, activated carbon, 3A molecular sieve, 5A molecular sieve, 13X molecular sieve, 13X type zeolite, resin, and silicate adsorbent;

[0048] More preferably, the adsorbent is at least one of silica gel, 13X molecular sieve, and Y-type molecular sieve;

[0049] Preferably, the volume ratio of the second extractant to the deoxygenated oil is (5-10):1.

[0050] The second aspect of the present invention provides a 1-heptene product, which is prepared by the method provided by the first aspect;

[0051] Preferably, the purity of the 1-heptene product is ≥ 99%.

[0052] The technical scheme of the present invention is applied, a composite deoxygenation process of reactive deoxygenation + extractive deoxygenation + adsorption deoxygenation, and a composite separation process of etherification + extractive distillation + precise distillation are adopted, and each step cooperates with each other to remove tertiary carbon olefins, organic acids and oxygen-containing compounds in oil products to the maximum extent, and finally effectively separate high-purity 1-heptene products. In addition, the present invention optimizes the process flow, maximizes the use of raw materials, reduces the generation of intermediate by-products, and improves the yield of the target product 1-heptene. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1The present invention is a process flow chart for separating 1-heptene from Fischer-Tropsch synthetic oil in one embodiment of the present invention.

[0054] Description of reference numerals:

[0055] 1. C5 cutting tower; 2. C6 cutting tower; 3. C7 cutting tower; 4. Deacidification tower; 5. Deacidification water washing tower; 6. Etherification reaction distillation tower; 7. Extraction deoxygenation tower; 8. First extractant regeneration tower; 9. Extraction distillation tower; 10. Second extractant regeneration tower; 11. Precision distillation tower; 12. Adsorption deoxygenation tower; 13. C8 cutting tower; 101-Fischer-Tropsch synthetic oil inlet; 102. C5 fraction outlet; 103. C5+ fraction section inlet; 104. C6 fraction outlet; 105. C6+ fraction section inlet; 106. C7 fraction outlet; 107. C7+ fraction section inlet; 108. C8+ fraction section outlet inlet; 109, C8 fraction outlet; 110, alkali liquor inlet; 111, C7 fraction inlet; 112, deacidified oil outlet; 113, washing water inlet; 114, deacidified oil inlet; 115, first extractant inlet; 116, intermediate product inlet; 117, first regenerated extractant outlet; 118, oxygenate-containing extractant inlet; 119, second extractant inlet; 120, deoxygenated oil inlet; 121, C7 olefin-rich extractant inlet; 122, second regenerated extractant outlet; 123, C7 olefin-rich component inlet; 124, 1-heptene crude product inlet; 125, 1-heptene product outlet. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0057] As described in the background of the present invention, the prior art has the problem that tertiary olefins, organic acids and oxygen-containing compounds in Fischer-Tropsch synthetic oil are not completely removed, resulting in low purity and low yield of 1-heptene. In order to solve the above problems, in a typical embodiment of the present invention, a method for separating 1-heptene from Fischer-Tropsch synthetic oil is provided, comprising the following steps:

[0058] S1, pre-cutting the Fischer-Tropsch synthetic oil to obtain a C7 fraction;

[0059] S2, deacidifying the C7 fraction to obtain a deacidified fraction;

[0060] S3, etherifying the deacidified fraction to obtain an intermediate product;

[0061] S4, extracting and deoxygenating the intermediate product to obtain deoxygenated oil;

[0062] S5, extracting and distilling the deoxygenated oil to obtain a C7 olefin-rich component;

[0063] S6, sequentially subjecting the C7 olefin-rich component to precise distillation and adsorption deoxygenation to obtain a 1-heptene product.

[0064] The Fischer-Tropsch synthetic oil of the present invention refers to an oil product produced by the Fischer-Tropsch synthesis process, which is mainly composed of hydrocarbons from C5 to C11. Among them, Fischer-Tropsch synthesis is a chemical process for converting synthesis gas (mainly composed of carbon monoxide and hydrogen) into liquid fuels and other hydrocarbon products, and is widely used in coal-to-oil, natural gas-to-oil and other processes.

[0065] First, the Fischer-Tropsch synthetic oil is pre-cut to separate the C7 fraction in advance, so that the target component can be concentrated and purified from the complex mixture in advance, reducing the load of the subsequent separation process and improving the overall efficiency. Pre-cutting can remove undesirable components in the Fischer-Tropsch oil, such as the lighter C5 and C6 fractions and the heavier C8+ fraction, so that subsequent processes such as etherification and extractive distillation can focus more on processing the C7 fraction and improve the separation selectivity and efficiency of the target component (such as 1-heptene).

[0066] Next, the C7 fraction is deacidified to remove acidic substances (organic acids, etc.) in the oil.

[0067] Subsequently, the deacidified fraction is subjected to etherification treatment. The etherification treatment is essentially an etherification reaction of tertiary carbon olefins in the deacidified fraction to form high-boiling point ether compounds. These ether compounds can be separated from the target product during the distillation process, effectively removing tertiary carbon olefins in the C7 fraction.

[0068] After the etherification treatment is completed, the intermediate product is subjected to extractive deoxygenation, and oxygen-containing compounds therein are removed by extractive deoxygenation to obtain deoxygenated oil.

[0069] Next, the deoxygenated oil is subjected to extractive distillation to remove the alkane component therein and enrich the C7 olefin component, and then the olefin-rich component (C7 olefin-rich component) and the enriched n-heptane component are obtained through extractive distillation.

[0070] Finally, the C7 olefin-rich component is used to separate the crude 1-heptene product and isoolefins in a precision distillation tower. The crude 1-heptene product is subjected to adsorption deoxygenation and deep deoxygenation to finally obtain the 1-heptene product.

[0071] The technical scheme of the present invention is applied, a composite deoxygenation process of reactive deoxygenation + extractive deoxygenation + adsorption deoxygenation, and a composite separation process of etherification + extractive distillation + precise distillation are adopted, and each step cooperates with each other to remove tertiary carbon olefins, organic acids and oxygen-containing compounds in oil products to the maximum extent, and finally effectively separate high-purity 1-heptene products. In addition, the present invention optimizes the process flow, maximizes the use of raw materials, reduces the generation of intermediate by-products, and improves the yield of the target product 1-heptene.

[0072] Pre-cutting is essentially to remove other fractions except C7 fraction. In some embodiments, pre-cutting includes first pre-cutting, second pre-cutting and third pre-cutting; S1 includes:

[0073] S11, feed the Fischer-Tropsch synthetic oil to the C5 cutting tower, and obtain the C5 fraction at the top of the tower after the first pre-cutting, and the C5 fraction at the bottom of the tower

[0074] Obtaining a C5+ fraction;

[0075] S12, feeding the C5+ fraction segment to the C6 cutting tower, and after the second pre-cutting, cutting at the top of the tower to obtain the C6 fraction,

[0076] The C6+ fraction is obtained at the bottom of the tower;

[0077] S13, feed the C6+ fraction segment to the C7 cutting tower, and after the third pre-cutting, cut at the top of the tower to obtain the C7 fraction, and obtain the C7+ fraction segment at the bottom of the tower.

[0078] Specifically, the Fischer-Tropsch synthetic oil is fed into a C5 cutting tower, and after the first distillation cutting, the C5 fraction with a relatively low boiling point is separated at the top of the tower, and the C5+ fraction segment with a relatively high boiling point is separated at the bottom of the tower; the C5+ fraction segment is fed into a C6 cutting tower, and after the second distillation cutting, the C6 fraction with a relatively low boiling point is separated at the top of the tower, and the C6+ fraction segment with a relatively high boiling point is separated at the bottom of the tower; the C6+ fraction segment is fed into a C7 cutting tower, and after the third distillation cutting, the C7 fraction with a relatively low boiling point is separated at the top of the tower, and the C7+ fraction segment with a relatively high boiling point is separated at the bottom of the tower. The method may also include the following steps: feeding the C7+ fraction segment into a C8 cutting tower, and after the fourth distillation cutting, the C8 fraction with a relatively low boiling point is separated at the top of the C8 tower, and the C8+ fraction with a relatively high boiling point is separated at the bottom of the tower.

[0079] The present invention does not limit the specific types of C5 cutting tower, C6 cutting tower, and C7 cutting tower, as long as the fraction with a specific carbon number is separated. In some embodiments, the number of plates of the C5 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 20 to 30°C, and the bottom temperature is 90 to 130°C; the number of plates of the C6 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 55 to 65°C, and the bottom temperature is 110 to 135°C; the number of plates of the C7 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 85 to 95°C, and the bottom temperature is 140 to 165°C.

[0080] The first pre-cut, the second pre-cut and the third pre-cut utilize the difference in volatility of fractions with different carbon numbers at different temperatures to achieve separation through a distillation process.

[0081] The present invention can use alkaline substances to achieve deacidification. In some embodiments, S2 includes: mixing the C7 fraction with alkali solution in a deacidification tower, and obtaining a deacidified fraction after deacidification; washing the deacidified fraction in a deacidification water washing tower to obtain a deacidified fraction. The alkali solution is used to neutralize the acidic substances in the C7 fraction. The alkaline substances in the alkali solution include at least one of potassium hydroxide, sodium hydroxide, sodium carbonate, and potassium carbonate. The mass concentration of the alkaline substances in the alkali solution is 2% to 8%. The deacidified oil is then washed with water until neutral, and then allowed to stand for stratification to separate the deacidified fraction of the oil phase.

[0082] The etherification treatment of the deacidified fraction is to remove tertiary olefins in the C7 fraction. Specifically, the tertiary olefins and the low-carbon alcohols undergo an etherification reaction under the action of a catalyst to generate high-boiling ether compounds, which are removed by utilizing the difference in boiling points. In some embodiments, S3 includes: mixing the deacidified fraction with the low-carbon alcohol in an etherification reaction distillation tower, and after etherification treatment, obtaining an intermediate product at the top of the etherification reaction distillation tower and obtaining an ether compound at the bottom of the tower.

[0083] Specifically, the deacidified fraction is mixed with a low-carbon alcohol (such as methanol) at the bottom of the tower, and the tertiary carbon olefin and the low-carbon alcohol undergo an etherification reaction under the action of a catalyst to generate high-boiling-point ether compounds. This reaction helps to convert the tertiary carbon olefin into a by-product that is easy to separate. In the etherification reaction distillation tower, the reaction and distillation separation are carried out simultaneously. The C7 fraction that does not participate in the reaction is separated by distillation at the top of the tower, that is, the C7 fraction logistics (i.e., the intermediate product) from which the tertiary carbon olefin is removed, and the logistics containing the high-boiling-point ether compounds are extracted at the bottom of the tower.

[0084] In some embodiments, the low-carbon alcohol includes at least one of methanol, ethanol, and propanol; preferably, the low-carbon alcohol is methanol; the etherification reaction distillation tower is loaded with a catalyst, and the catalyst includes at least one of a strong acid cation exchange resin, a heteropolyacid catalyst, and a molecular sieve catalyst. Under the action of the catalyst, the tertiary carbon olefin and the low-carbon alcohol are more conducive to the etherification reaction.

[0085] The present invention does not limit the specific type of the etherification reaction distillation tower, which can be a conventional reactor in the art. In some embodiments, the top temperature of the etherification reaction distillation tower is 85-95°C, and the bottom temperature is 110-130°C. For example, the etherification reaction distillation tower includes an upper section, a middle section and a lower section along the tower body from top to bottom, the first section is close to the top, the third section is close to the bottom, the middle section is filled with a catalyst, the upper section and the lower end are filled with porcelain balls, the catalyst is filled on the bed in the form of a packing bag, and the deacidification fraction and the low-carbon alcohol are fed from below the catalyst bed of the lower section.

[0086] Extraction deoxygenation is mainly used to remove oxygenated compounds in the C7 fraction, and separation is achieved by using different solvents to separate the components in the mixture due to the difference in solubility. In the present invention, the C7 fraction contains n-heptene, n-heptane and other isomers, as well as a small amount of oxygenated compounds (such as alcohols, aldehydes and alkyl acids). By selecting a specific extractant, these oxygenated compounds can be effectively dissolved, while the solubility for olefins and alkanes is low, thereby achieving the separation of oxygenated compounds from olefins and alkanes. In some embodiments, S4 includes: S41, the intermediate product is contacted with the first extractant in reverse in an extraction deoxygenation tower, and after extraction deoxygenation, deoxygenated oil and an extractant containing oxygenate are obtained; S42, the extractant containing oxygenate is fed to the first extractant regeneration tower, and after the first regeneration treatment, a first recovered extractant is obtained; the first regenerated extractant is returned to the extraction deoxygenation tower. Through the effective operation of the extraction deoxygenation tower, the oxygen-containing compounds in the C7 fraction flow can be significantly reduced, providing purer raw materials for subsequent extraction distillation and precision distillation, thereby improving the purity and yield of the 1-heptene product. At the same time, the efficient recovery and reuse of the first extractant also further reduces the operating cost.

[0087] In the extractive deoxygenation tower, the intermediate product is in reverse contact with the first extractant, ensuring sufficient contact and effective separation of the solvent and the oxides in the oil. After extractive deoxygenation, the extractant phase containing oxygenated compounds (extractant containing oxides) is separated from the C7 fraction phase (deoxygenated oil) from which most of the oxides have been removed. The extractant containing oxides enters the first extractant regeneration tower, where the first extractant is separated from the oxides through heating and other processes, and the first extractant can be recycled.

[0088] Specifically, sufficient space is left in the light component section at the top of the tower and the recombinant section at the bottom of the tower in the extractive deoxygenation tower to ensure that the liquid phase has sufficient residence time to fully contact with the first extractant, so as to improve the extraction efficiency. The light component section at the top of the tower and the recombinant section at the bottom of the tower are both equipped with level gauges, the intermediate product is fed from the bottom of the tower body, a liquid phase distributor is installed at the bottom of the tower body, the first extractant is fed from the top of the tower body, a liquid phase distributor is installed at the top of the tower body, a high-efficiency filler is installed in the middle of the tower body, and porcelain balls and wire mesh are installed at the top and bottom sections of the filler. This ensures the implementation of extractive deoxygenation.

[0089] In some embodiments, the temperature inside the extractive deoxygenation tower is 30-50°C. Within this temperature range, the appropriate solubility of the first extractant can be maintained while reducing energy consumption; the number of plates of the first extractant regeneration tower is 20-50, the reflux ratio is 2-8, the top temperature is 80-150°C, and the bottom temperature is 150-200°C.

[0090] The first extractant includes at least one of methanol, ethanol, acetonitrile, dimethyl sulfoxide, nitrogen methyl pyrrolidone, N,N-dimethylformamide, ethylene glycol, 1,4-butanediol, sulfolane, and propylene glycol. Preferably, the first extractant is a mixed system of sulfolane and propylene glycol, and the volume ratio of sulfolane to propylene glycol is (2-4):1.

[0091] The amount of the first extractant of the present invention can be adjusted according to actual needs to balance the extraction efficiency of the first oxide and the economic efficiency of use. In some embodiments, the volume ratio of the first extractant to the intermediate product is (1-12):1.

[0092] In the present invention, the C7 fraction contains n-heptene, n-heptane and other isomers. Extractive distillation combines the advantages of both extraction and distillation separation methods, and can more effectively separate 1-heptene-rich components from the C7 fraction under mild operating conditions, while separating alkanes and other isomers. In some embodiments, S5 includes: S51, making the deoxygenated oil contact with the second extractant in the extractive distillation tower in reverse, after extractive distillation, obtaining an alkane-rich component at the top of the extractive distillation tower, and obtaining an extractant containing C7 olefin-rich at the bottom of the tower; S52, feeding the extractant containing C7 olefin-rich to the second extractant regeneration tower 10, after the second regeneration treatment, obtaining a second regenerated extractant at the top of the second extractant regeneration tower 10, and obtaining a C7 olefin-rich component at the bottom of the tower; S53, returning the second regenerated extractant to the extractive distillation tower.

[0093] In some embodiments, the number of plates of the extractive distillation tower is 30 to 60, the reflux ratio is 2 to 12, the top temperature is 80 to 150°C, and the bottom temperature is 150 to 200°C; the extractive distillation tower can achieve efficient separation with a smaller number of theoretical plates, reducing the size and complexity of the equipment.

[0094] In some embodiments, the number of plates of the second extractant regeneration tower 10 is 20-50, the reflux ratio is 2-8, the tower top temperature is 80-150° C., and the tower bottom temperature is 180-230° C. The second extractant used in the extractive distillation process can be recycled and reused in the extractant recovery tower, which reduces raw material consumption, reduces production costs, and also reduces waste emissions, which is in line with the principles of green chemistry and sustainable development.

[0095] By selecting a suitable second extractant, extractive distillation can significantly enhance the separation selectivity of 1-heptene, thereby obtaining a higher purity product. This is because the second extractant can form a more stable complex with a specific component, while the interaction with other components is relatively weak. In some embodiments, the second extractant includes at least one of nitrogen methyl pyrrolidone, N, N-dimethylformamide, ethylene glycol, 1,4-butanediol, propylene glycol, nitrogen methyl morpholine, and 1,4-butyrolactone; preferably, the second extractant is a mixed system of nitrogen methyl pyrrolidone and 1,4-butyrolactone, and the volume ratio of nitrogen methyl pyrrolidone to 1,4-butyrolactone is (5 to 10): 1.

[0096] In the present invention, extractive distillation is combined with precision distillation to further optimize the separation process and reduce overall energy consumption. In some embodiments, S6 includes: S61, feeding the C7 olefin-rich component into a precision distillation tower, and obtaining a 1-heptene crude product at the top of the precision distillation tower after precision distillation; S62, feeding the 1-hexene crude product into an adsorption deoxygenation tower, and obtaining a 1-heptene product after adsorption deoxygenation.

[0097] Specifically, precision distillation can separate compounds with similar boiling points. Through precision distillation, the residual isomers and other impurities in the C7 fraction can be effectively removed to obtain a high-purity 1-heptene product. In some embodiments, the number of plates of the precision distillation tower is 30 to 70, the reflux ratio is 2 to 12, the top temperature is 80 to 150°C, and the bottom temperature is 150 to 200°C. The precision distillation tower can accurately control the temperature of the top and bottom of the tower to ensure that only the target product 1-heptene is extracted from the top of the tower, while other C7 components (such as 2-heptene and n-heptane) are discharged from the bottom of the tower, thereby controlling the quality of the final product. In some embodiments, the volume ratio of the second extractant to the deoxygenated oil is (5 to 10): 1.

[0098] After precise distillation, a small amount of oxides may remain in 1-heptene. Through adsorption deoxygenation, these oxides can be further deeply removed to ensure the high purity of the final product. During the adsorption deoxygenation process, the adsorbent can be regenerated or replaced, reducing waste emissions caused by chemical treatment. In some embodiments, the adsorption deoxygenation tower is loaded with an adsorbent, and the adsorbent includes at least one of silica gel, kaolin, diatomaceous earth, alumina, activated carbon, 3A molecular sieve, 5A molecular sieve, 13X molecular sieve, 13X type zeolite, resin, and silicate adsorbents; preferably, the adsorbent is at least one of silica gel, 13X molecular sieve, and Y-type molecular sieve.

[0099] The second aspect of the present invention provides a 1-heptene product, which is prepared by the method provided by the first aspect. By the method provided by the present invention, a high-purity 1-heptene product can be effectively separated from the Fischer-Tropsch synthetic oil. In some embodiments, the purity of the 1-heptene product is ≥99%.

[0100] The present application is further described in detail below in conjunction with specific embodiments, and these embodiments should not be construed as limiting the scope of protection claimed in the present application. Figure 1 As shown, the device used in the embodiment includes: C5 cutting tower 1, C6 cutting tower 2, C7 cutting tower 3, C8 cutting tower, deacidification tower 4, deacidification water washing tower 5, etherification reaction distillation tower 6, extraction deoxygenation tower 7, first extractant regeneration tower 8, extraction distillation tower 9, second extractant regeneration tower 10, precision distillation tower 11 and adsorption deoxygenation tower 12;

[0101] The C5 cutting tower 1 includes a Fischer-Tropsch synthetic oil inlet 101, a C5 fraction outlet 102 and a C5+ fraction outlet; the Fischer-Tropsch synthetic oil inlet 101 is located in the middle of the C5 cutting tower 1, the C5 fraction outlet 102 is located on the top side of the C5 cutting tower 1, and the C5+ fraction outlet is located at the bottom of the C5 cutting tower 1; the number of plates of the C5 cutting tower 1 is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 20 to 30°C, and the bottom temperature is 90 to 130°C;

[0102] C6 cutting tower 2 includes a C5+ fraction section inlet 103, a C6 fraction outlet 104 and a C6+ fraction section outlet; the C5+ fraction section inlet 103 of C6 cutting tower 2 is connected to the C5+ fraction section outlet of C5 cutting tower 1, the C5+ fraction section inlet 103 is located in the middle of C6 cutting tower 2, the C6 fraction outlet 104 is located at the top side of C6 cutting tower 2, and the C6+ fraction section outlet is located at the bottom of C6 cutting tower 2; the number of plates of C6 cutting tower 2 is 20 to 60, the reflux ratio is 5 to 15, the tower top temperature is 55 to 65° C., and the tower bottom temperature is 110 to 135° C.;

[0103] The C7 cutting tower 3 includes a C6+ fraction section inlet 105, a C7 fraction outlet 106 and a C7+ fraction section outlet; the C6+ fraction section inlet 105 of the C7 cutting tower 3 is connected to the C6+ fraction section outlet of the C6 cutting tower 2, the C6+ fraction section inlet 105 is located in the middle of the C7 cutting tower 3, the C7 fraction outlet 106 is located at the top side of the C7 cutting tower 3, and the C7+ fraction section outlet is located at the bottom of the C7 cutting tower 3; the number of plates of the C7 cutting tower 3 is 20 to 60, the reflux ratio is 5 to 15, the tower top temperature is 85 to 95° C., and the tower bottom temperature is 140 to 165° C.;

[0104] The C8 cutting tower 13 includes a C7+ fraction section inlet 107, a C8+ fraction section outlet 108, and a C8 fraction outlet 109; the C7+ fraction section inlet 107 is connected to the C7+ fraction section outlet of the C7 cutting tower 3;

[0105] The deacidification tower 4 includes a C7 fraction inlet 111, an alkali solution inlet 110 and a deacidified oil outlet 112; the C7 fraction inlet 111 of the deacidification tower 4 is connected to the C7 fraction outlet 106 of the C7 cutting tower 3, the C7 fraction inlet 111 is located at the bottom side of the deacidification tower 4, the alkali solution inlet 110 is located at the top side of the deacidification tower 4, and the deacidified oil outlet 112 is located at the top side of the deacidification tower 4;

[0106] The deacidification water washing tower 5 includes a deacidification oil inlet, a washing water inlet 113, and a deacidification oil outlet; the deacidification oil outlet 112 of the deacidification tower 4 is connected to the deacidification oil inlet of the deacidification water washing tower 5; wherein the deacidification oil inlet is located at the bottom side of the deacidification water washing tower 5, the deacidification oil outlet is located at the top side of the deacidification water washing tower 5, and the washing water inlet 113 is located at the top side of the deacidification water washing tower 5;

[0107] The etherification reaction distillation tower 6 includes a deacidified oil inlet 114 and an intermediate product outlet. The deacidified oil inlet 114 of the etherification reaction distillation tower 6 is connected to the deacidified oil outlet of the deacidified water washing tower 5. The intermediate product outlet is located at the top side of the etherification reaction distillation tower 6, and the deacidified oil inlet 114 is located at the bottom side of the etherification reaction distillation tower 6. The top temperature of the etherification reaction distillation tower 6 is 85-95°C, and the bottom temperature is 110-130°C.

[0108] The extracting deoxygenation tower 7 includes an intermediate product inlet 116, a first extracting agent inlet 115, a deoxygenated oil outlet and an oxygenated extracting agent outlet; the intermediate product inlet 116 of the extracting deoxygenation tower 7 is connected to the intermediate product outlet of the etherification reaction distillation tower 6, the intermediate product inlet 116 is located in the middle of the extracting deoxygenation tower 7, the first extracting agent inlet 115 is located at the top side of the extracting deoxygenation tower 7, the deoxygenated oil outlet is located at the top of the extracting deoxygenation tower 7, and the oxygenated extracting agent outlet is located at the bottom side of the extracting deoxygenation tower 7; the tower temperature of the extracting deoxygenation tower 7 is 30-50°C;

[0109] The first extractant regeneration tower 8 includes an oxygenate extractant inlet 118 and a first regeneration extractant outlet 117; the oxygenate extractant inlet 118 of the first extractant regeneration tower 8 is connected to the oxygenate extractant outlet of the extractive deoxygenation tower 7, the oxygenate extractant inlet 118 is located in the middle of the first extractant regeneration tower 8, and the first regeneration extractant outlet 117 is located at the bottom of the first extractant regeneration tower 8; the first extractant regeneration tower 8 has a plate number of 20 to 50, a reflux ratio of 2 to 8, a tower top temperature of 80 to 150°C, and a tower bottom temperature of 150 to 200°C;

[0110] The extractive distillation tower 9 includes a deoxygenated oil inlet 120, a second extractant inlet 119, an alkane-rich component outlet, and an extractant outlet containing C7-rich olefins; the deoxygenated oil inlet 120 of the extractive distillation tower 9 is connected to the deoxygenated oil outlet of the extractive deoxygenation tower 7, the deoxygenated oil inlet 120 is located at the bottom side of the extractive distillation tower 9, the second extractant inlet 119 is located at the top side of the extractive distillation tower 9, the alkane-rich component outlet is located at the top of the extractive distillation tower 9, and the extractant outlet containing C7-rich olefins is located at the bottom of the extractive distillation tower 9; the number of plates of the extractive distillation tower 9 is 30-60, the reflux ratio is 2-12, the tower top temperature is 80-150°C, and the tower bottom temperature is 150-200°C;

[0111] The second extractant regeneration tower 10 comprises an extractant inlet 121 containing C7 rich olefins, a second regenerated extractant outlet 122 and a C7 rich olefin component outlet, the extractant inlet 121 containing C7 rich olefins of the second extractant regeneration tower 10 is connected to the extractant inlet 121 containing C7 rich olefins of the extractive distillation tower 9; the second regenerated extractant outlet 122 of the second extractant regeneration tower 10 is connected to the second extractant inlet 119 of the extractive distillation tower 9, the extractant inlet 121 containing C7 rich olefins is located in the middle of the second extractant regeneration tower 10, the second regenerated extractant outlet 122 is located at the bottom, and the C7 rich olefin component outlet is located at the top of the tower; the second extractant regeneration tower 10 has a plate number of 20 to 50, a reflux ratio of 2 to 8, a tower top temperature of 80 to 150° C., and a tower bottom temperature of 180 to 230° C.;

[0112] The precision distillation tower 11 includes a C7 olefin-rich component inlet 123, a 1-heptene crude product outlet and an impurity outlet; the C7 olefin-rich component inlet 123 of the precision distillation tower 11 is connected to the C7 olefin-rich component outlet of the second extractant regeneration tower 10, the C7 olefin-rich component inlet 123 is located in the middle of the tower, the 1-heptene crude product outlet is located at the top of the tower, and the impurity outlet is located at the bottom of the tower; the number of plates of the precision distillation tower 11 is 30 to 70, the reflux ratio is 2 to 12, the tower top temperature is 80 to 150° C., and the tower bottom temperature is 150 to 200° C.;

[0113] The adsorption deoxygenation tower 12 includes a 1-heptene crude product inlet 124 and a 1-heptene product outlet 125; the 1-heptene crude product inlet 124 of the adsorption deoxygenation tower 12 is connected to the 1-heptene crude product outlet of the precision distillation tower 11; the 1-heptene crude product inlet 124 is located in the middle of the adsorption deoxygenation tower 12, and the 1-heptene product outlet 125 is located at the top of the adsorption deoxygenation tower 12.

[0114] Example 1

[0115] The method for separating 1-heptene from Fischer-Tropsch synthetic oil in this embodiment comprises the following steps:

[0116] S1, pre-cutting the Fischer-Tropsch synthetic oil to obtain a C7 fraction; specifically comprising:

[0117] S11, feed the Fischer-Tropsch synthetic oil to the C5 cutting tower 1, and obtain the C5 fraction at the top of the tower after the first pre-cutting.

[0118] The C5+ fraction is obtained at the bottom;

[0119] S12, feeding the C5+ fraction segment to the C6 cutting tower 2, and after the second pre-cutting, cutting at the top of the tower to obtain the C6 fraction, and obtaining the C6+ fraction segment at the bottom of the tower;

[0120] S13, feed the C6+ fraction to the C7 cutting tower 3, and after the third pre-cutting, cut at the top of the tower to obtain the C7 fraction,

[0121] The C7+ fraction is obtained at the bottom of the tower; the number of plates of C7 cutting tower 3 is 60, the reflux ratio is 5:1, and the top temperature is 91°C.

[0122] The tower bottom temperature is 150°C, the tower pressure is atmospheric pressure, and the feed is at 30 trays;

[0123] S2, mixing the C7 fraction with the alkali solution in a deacidification tower 4, and obtaining a deacidified fraction after deacidification; washing the deacidified fraction in a deacidification water washing tower 5 until it is nearly neutral, and entering an oil-water separator for oil-water separation, and obtaining a deacidified fraction in the upper oil phase; the alkali solution is a NaOH solution with a mass concentration of 10%; the volume of the C7 fraction and the alkali solution is 1:1;

[0124] S3, feeding the deacidified fraction and methanol at the bottom of the etherification reaction distillation tower 6, mixing, and carrying out etherification reaction under the action of a strong acidic cation exchange resin Amberlyst catalyst, obtaining an intermediate product at the top of the etherification reaction distillation tower 6, and obtaining an ether compound at the bottom; the molar ratio of methanol to tertiary carbon olefins in the deacidified fraction is 5:1;

[0125] S4, extracting and deoxygenating the intermediate product to obtain deoxygenated oil; specifically comprising:

[0126] S41, the intermediate product is contacted with the first extractant in reverse in an extracting deoxygenation tower 7, and after extracting and deoxygenating, a deoxygenated oil and an extractant containing an oxygenate are obtained; the first extractant is a mixed system of sulfolane and propylene glycol, and the volume ratio of sulfolane to propylene glycol is 3:1; the volume ratio of the first extractant to the intermediate product is 5:1;

[0127] S42, feed the oxygenated extractant into the first extractant regeneration tower 8, and obtain the first recovered extractant after the first regeneration treatment; return the first regenerated extractant to the extractive deoxygenation tower 7; the number of plates of the first extractant regeneration tower 8 is

[0128] is 30, the reflux ratio is 4, the tower top temperature is 90-95°C, and the tower bottom temperature is 150-200°C;

[0129] S5, extracting and distilling the deoxygenated oil to obtain a C7 olefin-rich component; specifically comprising:

[0130] S51, making the deoxygenated oil contact with the second extractant in the extractive distillation tower 9 in reverse order, after extractive distillation, obtaining an alkane-rich component at the top of the extractive distillation tower 9, and obtaining an extractant containing C7 olefin-rich olefins at the bottom; the second extractant is a mixed system of nitrogen methyl pyrrolidone and 1,4-butyrolactone, and the volume ratio of nitrogen methyl pyrrolidone to 1,4-butyrolactone is 6:1; the volume ratio of the second extractant to the deoxygenated oil is 8:1, the number of plates of the extractive distillation tower 9 is 60, the reflux ratio is 15, the top temperature is 93° C., and the bottom temperature is 165° C.;

[0131] S52, feeding the C7 olefin-rich extractant into the second extractant regeneration tower 10, and obtaining the second regenerated extractant at the top of the second extractant regeneration tower 10 after the second regeneration treatment, and obtaining the C7 olefin-rich component at the bottom of the tower; the second extractant regeneration tower 10 has 30 plates, a reflux ratio of 5, a top temperature of 90-95° C., and a bottom temperature of 180-220° C.;

[0132] S53, returning the second regenerated extractant to the extractive distillation tower 9;

[0133] S6, sequentially subjecting the C7 olefin-rich component to precise distillation and adsorption deoxygenation to obtain a 1-heptene product; specifically comprising:

[0134] S61, feeding the C7 olefin-rich component into a precision distillation tower 11, and obtaining a crude 1-heptene product at the top of the precision distillation tower 11 after precision distillation; the precision distillation tower 11 has 70 plates, a reflux ratio of 11, a top temperature of 90-93° C., and a bottom temperature of 150° C.;

[0135] S62, feeding the crude 1-hexene product into an adsorption deoxygenation tower 12, and obtaining a 1-heptene product after adsorption deoxygenation;

[0136] The adsorption deoxygenation tower 12 is loaded with 13X molecular sieve.

[0137] Example 2

[0138] The difference from Example 1 is that the first extracting agent is methanol.

[0139] Example 3

[0140] The difference from Example 1 is that the first extractant is acetonitrile.

[0141] Example 4

[0142] The difference from Example 1 is that the first extracting agent is dimethyl sulfoxide.

[0143] Example 5

[0144] The difference from Example 1 is that the first extractant is N,N-dimethylformamide.

[0145] Example 6

[0146] The difference from Example 1 is that the first extracting agent is 1,4-butanediol.

[0147] Example 7

[0148] The difference from Example 1 is that the first extracting agent is sulfolane.

[0149] Example 8

[0150] The difference from Example 1 is that in the first extractant, the volume ratio of sulfolane to propylene glycol is 2:1.

[0151] Example 9

[0152] The difference from Example 1 is that the second extractant is N,N-dimethylformamide.

[0153] Example 10

[0154] The difference from Example 1 is that the second extracting agent is 1,4-butanediol.

[0155] Embodiment 11

[0156] The difference from Example 1 is that the second extractant is nitrogen morpholine.

[0157] Example 12

[0158] The difference from Example 1 is that in the second extractant, the volume ratio of nitrogen methyl pyrrolidone to 1,4-butyrolactone is 10:1.

[0159] Comparative Example 1

[0160] The difference from Example 1 is that S3 is omitted.

[0161] Comparative Example 2

[0162] The difference from the first embodiment is that S62 is omitted.

[0163] 1-heptene purity = mass of 1-heptene / total mass of raw materials × 100%

[0164] 1-heptene yield = 1-heptene product amount / 1-heptene amount in raw material × 100%

[0165] Table 1

[0166]

[0167]

[0168] It can be seen from Table 1 that the present invention can effectively separate high-purity 1-heptene products and improve the yield of the target product 1-heptene, which can be directly used as a polymerization monomer.

[0169] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for separating 1-heptene from Fischer-Tropsch synthetic oil, characterized in that: The following steps are involved: S1, pre-cutting the Fischer-Tropsch synthetic oil to obtain a C7 fraction; S2, deacidifying the C7 fraction to obtain a deacidified fraction; S3, subjecting the deacidified fraction to etherification treatment to obtain an intermediate product; S4, extracting and deoxygenating the intermediate product to obtain deoxygenated oil; S5, extracting and distilling the deoxygenated oil to obtain a C7 olefin-rich component; S6, sequentially subjecting the C7 olefin-rich component to precise distillation and adsorption deoxygenation to obtain a 1-heptene product.

2. The method according to claim 1, characterized in that The pre-cutting includes a first pre-cutting, a second pre-cutting and a third pre-cutting; S1 includes: S11, feeding the Fischer-Tropsch synthetic oil to a C5 cutting tower, and obtaining a C5 fraction at the top of the tower and a C5+ fraction at the bottom of the tower after a first pre-cutting; S12, feeding the C5+ fraction segment to a C6 cutting tower, and after a second pre-cutting, cutting at the top of the tower to obtain a C6 fraction, and obtaining a C6+ fraction segment at the bottom of the tower; S13, feeding the C6+ fraction to a C7 cutting tower, and after the third pre-cutting, cutting at the top of the tower to obtain a C7 fraction, and obtaining a C7+ fraction section at the bottom of the tower; Preferably, the number of plates of the C5 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 20 to 30° C., and the bottom temperature is 90 to 130° C.; Preferably, the number of plates of the C6 cutting tower is 20 to 60, the reflux ratio is 5 to 15, the top temperature is 55 to 65° C., and the bottom temperature is 110 to 135° C.; Preferably, the C7 cutting tower has a plate number of 20 to 60, a reflux ratio of 5 to 15, a top temperature of 85 to 95° C., and a bottom temperature of 140 to 165° C.

3. The method according to claim 1, characterized in that The S2 includes: The C7 fraction is mixed with alkali solution in a deacidification tower to obtain a deacidified fraction after deacidification; the deacidified fraction is washed with water in a deacidification water washing tower to obtain the deacidified fraction; Preferably, the alkaline substance in the alkali solution includes at least one of potassium hydroxide, sodium hydroxide, sodium carbonate and potassium carbonate, and the mass concentration of the alkaline substance in the alkali solution is 2% to 8%.

4. The method according to any one of claims 1 to 3, characterized in that The S3 includes: The deacidified fraction is mixed with low-carbon alcohol in an etherification reaction distillation tower, and after etherification treatment, an intermediate product is obtained at the top of the etherification reaction distillation tower, and an ether compound is obtained at the bottom of the tower; Preferably, the top temperature of the etherification reaction distillation tower is 85-95°C, and the bottom temperature is 110-130°C; Preferably, the low-carbon alcohol includes at least one of methanol, ethanol and propanol; More preferably, the low-carbon alcohol is methanol; Preferably, the etherification reaction distillation tower is loaded with a catalyst, and the catalyst includes at least one of a strongly acidic cation exchange resin, a heteropolyacid catalyst, and a molecular sieve catalyst.

5. The method according to any one of claims 1 to 3, characterized in that The S4 includes: S41, contacting the intermediate product with the first extractant in reverse order in an extractive deoxygenation tower, and obtaining deoxygenated oil and an extractant containing an oxygenate after extractive deoxygenation; S42, feeding the oxygenate-containing extractant into a first extractant regeneration tower, and subjecting the first regeneration treatment to obtain a first recovered extractant; and returning the first regenerated extractant to the extraction deoxygenation tower.

6. The method according to claim 5, characterized in that The temperature inside the extractive deoxygenation tower is 30-50°C; and / or, The first extractant regeneration tower has a plate number of 20 to 50, a reflux ratio of 2 to 8, a tower top temperature of 80 to 150° C., and a tower bottom temperature of 150 to 200° C.; and / or, The first extractant comprises at least one of methanol, ethanol, acetonitrile, dimethyl sulfoxide, nitrogen methyl pyrrolidone, N,N-dimethylformamide, ethylene glycol, 1,4-butanediol, cyclopentane sulfone, and propylene glycol; and / or, The volume ratio of the first extractant to the intermediate product is (1-12):1; Preferably, the first extractant is a mixed system of sulfolane and propylene glycol, and the volume ratio of the sulfolane to the propylene glycol is (2-4):

1.

7. The method according to any one of claims 1 to 3, characterized in that The S5 includes: S51, making the deoxygenated oil contact with the second extractant in a extractive distillation tower in reverse order, after extractive distillation, obtaining an alkane-rich component at the top of the extractive distillation tower, and obtaining an extractant containing C7 olefin-rich components at the bottom of the tower; S52, feeding the C7 olefin-rich extractant into a second extractant regeneration tower, and obtaining a second regenerated extractant at the top of the second extractant regeneration tower after a second regeneration treatment, and obtaining a C7 olefin-rich component at the bottom of the tower; S53, returning the second regenerated extractant to the extractive distillation tower; Preferably, the extractive distillation tower has a plate number of 30 to 60, a reflux ratio of 2 to 12, a top temperature of 80 to 150° C., and a bottom temperature of 150 to 200° C.; Preferably, the second extractant regeneration tower has a plate number of 20 to 50, a reflux ratio of 2 to 8, a top temperature of 80 to 150° C., and a bottom temperature of 180 to 230° C.

8. The method according to claim 7, characterized in that The second extractant comprises at least one of nitrogen methyl pyrrolidone, N,N-dimethylformamide, ethylene glycol, 1,4-butanediol, propylene glycol, nitrogen morpholine, and 1,4-butyrolactone; More preferably, the second extractant is a mixed system of nitrogen methyl pyrrolidone and 1,4-butyrolactone, and the volume ratio of the nitrogen methyl pyrrolidone to the 1,4-butyrolactone is (5-10):

1.

9. The method according to claim 7, characterized in that: The S6 includes: S61, feeding the C7 olefin-rich component into a precision distillation tower 11, and obtaining a crude 1-heptene product at the top of the precision distillation tower 11 after precision distillation; S62, feeding the crude 1-hexene product into an adsorption deoxygenation tower, and obtaining the 1-heptene product after adsorption deoxygenation; Preferably, the number of plates of the precision distillation tower 11 is 30 to 70, the reflux ratio is 2 to 12, the top temperature is 80 to 150° C., and the bottom temperature is 150 to 200° C.; Preferably, the adsorption deoxidation tower is loaded with an adsorbent, and the adsorbent includes at least one of silica gel, kaolin, diatomaceous earth, alumina, activated carbon, 3A molecular sieve, 5A molecular sieve, 13X molecular sieve, 13X type zeolite, resin, and silicate adsorbent; More preferably, the adsorbent is at least one of silica gel, 13X molecular sieve, and Y-type molecular sieve; Preferably, the volume ratio of the second extractant to the deoxygenated oil is (5-10):

1.

10. A 1-heptene product, characterized in that The 1-heptene product is prepared by the method according to any one of claims 1 to 9; Preferably, the purity of the 1-heptene product is ≥ 99%.

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