Method and system for separating 1-hexene from Fischer-Tropsch synthesis oil

Abstract

The invention relates to a Fischer-Tropsch synthetic oil separation technology, and discloses a method and a system for separating 1-hexene from Fischer-Tropsch synthetic oil. The method comprises the following steps: (1) carrying out deacidification treatment on Fischer-Tropsch synthetic oil, and then carrying out first rectification to obtain C6 and C6 + fractions; (2) carrying out second rectification on the C6 and C6 < + > fractions to obtain a C6 fraction; (3) carrying out a first deoxidation reaction on the C6 fraction and hydrogen, then carrying out a second deoxidation reaction on the reacted material, and then carrying out an etherification reaction on the reacted material to obtain a C6 fraction without tertiary carbon olefin; and (4) sequentially carrying out third rectification and fourth rectification on the C6 fraction from which the tertiary carbon olefin is removed. The first deoxidation catalyst contains a first metal, a second metal and a first carrier, and the second deoxidation catalyst contains a first metal oxide, a second metal oxide and a second carrier. According to the method, the technological process can be further simplified, and the purity of the 1-hexene product obtained through separation can be improved.

Description

Technical Field

[0001] This invention relates to a separation technique for Fischer-Tropsch synthetic oil, specifically to a method and system for separating 1-hexene from Fischer-Tropsch synthetic oil. Background Technology

[0002] Fischer-Tropsch synthesis is the core technology of coal-to-oil processes, primarily involving the catalytic conversion of syngas into gasoline, diesel, and other hydrocarbon products. However, its product, crude FT oil, is mainly used as a primary chemical feedstock or fuel oil, resulting in low economic efficiency and weak market competitiveness when oil prices remain low for extended periods. Fischer-Tropsch washed naphtha is characterized by its high content of α-olefins (>50%), straight-chain hydrocarbons, small amounts of cycloalkanes, and almost no aromatic hydrocarbons. Separating the long-chain α-olefins from FT oil can not only yield high-value-added long-chain olefins but also produce clean, high-quality aviation kerosene, lubricating oil base oils, or specialty solvent oils, thereby enhancing the resilience of coal-based FT oil to market risks.

[0003] 1-Hexene, as an important organic raw material and chemical intermediate, is mainly used in the production of high-end polyethylene (PE). The market potential for metallocene LLDPE resin copolymerized with 1-hexene is enormous; currently, over 95% of the comonomers used in LLDPE preparation are 1-butene. As the use of 1-hexene comonomers in LLDPE resin production gradually expands, more 1-butene monomers will be used to produce general-purpose products.

[0004] Currently, the Fischer-Tropsch products from the 4 million tons / year coal-to-oil project are mainly used as primary chemical feedstocks or semi-finished oil products. Among them, the intermediate product, oil-washed naphtha, is generally hydrogenated to become refined naphtha, resulting in a great waste of α-olefin resources. Separating α-olefins from Fischer-Tropsch oil products and obtaining high-value-added α-olefin products can improve the economic benefits of coal-to-oil enterprises and their ability to resist market risks.

[0005] Currently reported methods for separating and purifying 1-hexene from Fischer-Tropsch synthetic oils mainly employ extractive distillation to remove oxygen-containing compounds from the C6 fraction. However, this technology suffers from drawbacks such as high oxide content in the final product, which affects polymerization efficiency, and a complex deoxygenation process. Furthermore, the purity of 1-hexene obtained from commonly used separation techniques is insufficient to meet the requirements for subsequent fine chemical preparation. Therefore, there is a need to further improve the purity of 1-hexene products separated from Fischer-Tropsch synthetic oils. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of complex operation process and insufficient purity of 1-hexene product in the existing technology for separating 1-hexene from Fischer-Tropsch synthetic oil. This invention provides a method and system for separating 1-hexene from Fischer-Tropsch synthetic oil. This method can further simplify the process flow and further improve the purity of the separated 1-hexene product.

[0007] To achieve the above objectives, the present invention provides a method for separating 1-hexene from Fischer-Tropsch synthetic oil, the method comprising the following steps:

[0008] (1) The Fischer-Tropsch synthetic oil was deacidified, and then the resulting material was subjected to a first distillation to obtain C6 and C62. + distillate;

[0009] (2) The C6 and C6 + The fraction was subjected to a second distillation to obtain the C6 fraction;

[0010] (3) In the presence of the first deoxygenation catalyst, the C6 fraction and hydrogen are subjected to a first deoxygenation reaction, and then the reacted material is subjected to a second deoxygenation reaction in the presence of the second deoxygenation catalyst. Then the reacted material is subjected to an etherification reaction with a low alcohol to obtain a C6 fraction with tertiary olefins removed.

[0011] (4) The C6 fraction after the removal of tertiary olefins is subjected to a third and a fourth distillation in sequence;

[0012] (4) The C6 fraction after the removal of tertiary olefins is subjected to a third and a fourth distillation in sequence.

[0013] The first deoxygenation catalyst contains a first metal, a second metal, and a first support. The first metal is Cu and / or Pt, the second metal is selected from at least one of Ag, Au, Pd, Fe, and Co, and the first support is at least one of SiO2, Al2O3, and TiO2. The second deoxygenation catalyst contains a first metal oxide, a second metal oxide, and a second support. The first metal oxide is selected from at least one of TiO2, La2O3, and ThO2, the second metal oxide is selected from at least one of WO3, Mo3, and Cr2O3, and the second support is at least one of SiO2, ZrO2, and Al2O3.

[0014] Preferably, in the first deoxygenation catalyst, the weight ratio of the first metal to the second metal is 1 to 20:1.

[0015] Preferably, in the second deoxygenation catalyst, the weight ratio of the first metal oxide to the second metal oxide is 2 to 20:1, and the ratio of the total weight of the first metal oxide and the second metal oxide to the weight of the second support is 1:5 to 40.

[0016] Preferably, the first deoxygenation reaction conditions include: a reaction temperature of 50-200°C and a volume hourly space velocity of 0.01-8 h⁻¹. -1 The pressure is 1-10 MPa.

[0017] Preferably, the conditions for the second deoxygenation reaction include: a temperature of 160-350°C and a space velocity of 1-2 h⁻¹. -1 The pressure is 0.01-0.5 MPa.

[0018] Preferably, the first deoxygenation catalyst is reduced in hydrogen before use, and the reduction conditions are: hydrogen pressure 0.001-1.0 MPa, hydrogen flow rate 50-200 mL / min, reduction temperature 400-600℃, and reduction time 4-10 h.

[0019] Preferably, the first distillation is carried out in a first distillation column, the first distillation column having 40-60 theoretical plates and a reflux ratio of 4-12.

[0020] Preferably, the top pressure of the first distillation column is 0.1-0.2 MPaG, the top temperature is 40-60℃, and the bottom temperature is 120-140℃.

[0021] Preferably, the second distillation is carried out in a second distillation column, the second distillation column having 40-60 theoretical plates and a reflux ratio of 5-15.

[0022] Preferably, the top temperature of the second distillation column is 55-65℃, and the bottom temperature is 90-120℃.

[0023] Preferably, the preparation method of the first deoxygenation catalyst includes: adjusting the pH value of a solution containing a first metal salt and a second metal salt to 6-8 using a carbonate solution to obtain a first precursor solution, then impregnating the first support in the first precursor solution, and then calcining the impregnated solid phase at 400-600℃ for 2-5 hours.

[0024] Preferably, the immersion time is 2-4 hours and the immersion temperature is 20-40°C.

[0025] Preferably, the preparation method of the second deoxygenation catalyst includes: adjusting the pH value of the solution containing the first metal oxide precursor and the second metal oxide precursor to 8-10 with ammonia water under water bath conditions of 60-95℃ to obtain a second precursor solution, then immersing the second support in the second precursor solution, and then aging it, and then calcining the aged solid phase at 400-600℃ for 4-8h.

[0026] Preferably, the immersion time is 1-2 hours and the immersion temperature is 20-40°C;

[0027] Preferably, the aging time is 4-6 hours and the aging temperature is 20-40℃.

[0028] Preferably, the lower alcohol is a C1-C5 alcohol.

[0029] Preferably, in step (3), the weight ratio of the reacted material to the low-carbon alcohol is 1:0.002-0.004.

[0030] Preferably, the etherification reaction conditions include: a temperature of 50-80°C and a time of 10-120 min.

[0031] Preferably, the etherification reaction is carried out in the presence of an acidic resin catalyst.

[0032] Preferably, the third distillation is carried out in a third distillation column, which has a theoretical plate number of 100-130 and a reflux ratio of 5-15.

[0033] Preferably, the top temperature of the third distillation column is 55-60℃, and the bottom temperature is 60-80℃.

[0034] Preferably, the bottom material of the third distillation column is subjected to a fourth distillation.

[0035] Preferably, the fourth distillation is carried out in a fourth distillation column, which has a theoretical plate number of 110-140 and a reflux ratio of 10-20.

[0036] Preferably, the top temperature of the fourth distillation column is 55-65℃, and the bottom temperature is 60-80℃.

[0037] Preferably, the method further includes: drying and deep deoxygenating the crude 1-hexene obtained from the fourth distillation.

[0038] Preferably, an adsorption tower is used to perform deep deoxygenation on the dried material.

[0039] Preferably, the adsorbent used in the adsorption tower is selected from one or more of silica gel, alumina, activated carbon, resin, silicates, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-34 molecular sieve, 13X molecular sieve, Y-type molecular sieve and MCM-22 molecular sieve, with 13X molecular sieve being the most preferred.

[0040] A second aspect of the present invention provides a system for separating 1-hexene from Fischer-Tropsch synthetic oil, the system comprising a deacidification unit, a first distillation column, a second distillation column, a deoxygenation unit, an etherification reactor, a third distillation column, and a fourth distillation column connected in sequence.

[0041] The deacidification unit is used to deacidify the Fischer-Tropsch synthetic oil to remove acidic substances from it.

[0042] The first distillation column is used to perform a first distillation on the material from the deacidification unit to obtain C6 and C62. + distillate;

[0043] The second distillation column is used to distill the C6 and C6 + The fraction was subjected to a second distillation to obtain the C6 fraction;

[0044] The deoxygenation unit is provided with a hydrodeoxygenation reactor and a chemical deoxygenation reactor connected in sequence. The hydrodeoxygenation reactor is filled with the first deoxygenation catalyst for removing aldehyde oxides and ketone oxides from the C6 fraction.

[0045] The chemical deoxygenation reactor is filled with the second deoxygenation catalyst for removing alcohol oxides from the C6 fraction;

[0046] The etherification reactor is filled with the acidic resin catalyst. The material from the chemical deoxygenation reactor and the low alcohol undergo an etherification reaction in the etherification reactor to obtain a C6 fraction with tertiary olefins removed.

[0047] The third distillation column is used to perform a third distillation on the C6 fraction from which tertiary olefins have been removed.

[0048] The fourth distillation column is used to perform a fourth distillation on the bottom material from the third distillation column to obtain crude 1-hexene.

[0049] Preferably, the system further includes a drying unit and a deep deoxygenation unit;

[0050] The drying unit is used to dry the crude 1-hexene, which is then transported to the deep deoxygenation unit for deep deoxygenation.

[0051] Preferably, the deep deoxygenation unit includes a first adsorption deoxygenation unit and a second adsorption deoxygenation unit connected in parallel, and both the first adsorption deoxygenation unit and the second adsorption deoxygenation unit include a plurality of adsorption deoxygenation towers connected in series.

[0052] The method described in this invention removes aldehyde and ketone oxides from the C6 fraction obtained by distillation through hydrodeoxygenation, followed by chemical deoxygenation to remove alcohol oxides. This combination of two deoxygenation methods ensures complete removal of oxygen-containing compounds from the C6 fraction, resulting in higher purity of the separated 1-hexene. Furthermore, the method further enhances the deoxygenation rate by employing specific components of the first and second deoxygenation catalysts, thereby increasing the purity of the separated 1-hexene product. This effectively solves the problems of complex processes, high equipment investment, high energy consumption, and high operating costs associated with current extraction deoxygenation methods, comprehensively improving the efficiency of separating and purifying 1-hexene from Fischer-Tropsch synthetic oil while simultaneously ensuring the quality of the purified 1-hexene product. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the process flow for separating 1-hexene from Fischer-Tropsch synthetic oil as described in this invention.

[0054] Explanation of reference numerals in the attached figures

[0055] 1. Deacidification unit; 2. First distillation column; 3. Second distillation column;

[0056] 4. Hydrodeoxygenation reactor; 5. Chemical deoxygenation reactor; 6. Etherification reactor;

[0057] 7. Third distillation column; 8. Fourth distillation column; 9. Drying unit;

[0058] 10. Deep deoxygenation unit; 11. Alkali washing tower; 12. Water washing tower;

[0059] 13 Oil-water separation device; 101 First adsorption deoxygenation unit; 102 Second adsorption deoxygenation unit. Detailed Implementation

[0060] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0061] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0062] The method for separating 1-hexene from Fischer-Tropsch synthetic oil according to the present invention includes the following steps:

[0063] (1) The Fischer-Tropsch synthetic oil was deacidified, and then the resulting material was subjected to a first distillation to obtain C6 and C62. + distillate;

[0064] (2) The C6 and C6 + The fraction was subjected to a second distillation to obtain the C6 fraction;

[0065] (3) In the presence of the first deoxygenation catalyst, the C6 fraction and hydrogen are subjected to a first deoxygenation reaction, and then the reacted material is subjected to a second deoxygenation reaction in the presence of the second deoxygenation catalyst. Then the reacted material is subjected to an etherification reaction with a low alcohol to obtain a C6 fraction with tertiary olefins removed.

[0066] (4) The C6 fraction after the removal of tertiary olefins is subjected to a third and a fourth distillation in sequence;

[0067] (4) The C6 fraction after the removal of tertiary olefins is subjected to a third and a fourth distillation in sequence.

[0068] In the method described in this invention, the Fischer-Tropsch synthetic oil can be any oil product commonly obtained through Fischer-Tropsch synthesis in the art, and the method described in this invention is particularly suitable for coal-based low-temperature Fischer-Tropsch synthetic oil feedstock.

[0069] In the method described in this invention, the Fischer-Tropsch synthetic oil is subjected to deacidification treatment to remove acidic substances, such as organic acids, from the Fischer-Tropsch synthetic oil. In some embodiments, the specific method of deacidification treatment includes: reacting the Fischer-Tropsch synthetic oil with an alkaline solution, then washing the reacted material with water, then separating the oil phase material to obtain an oil phase material, and then subjecting the obtained oil phase material to a first distillation to obtain C6 and C62. + Fraction. Specifically, the composition of the alkaline solution described in this invention is not limited, and can be selected with reference to common techniques in the art.

[0070] In the method described in this invention, the first distillation is carried out in a first distillation column. Specifically, the first distillation column has 40-60 theoretical plates and a reflux ratio of 4-12. In some preferred embodiments, the top pressure of the first distillation column is 0.1-0.2 MPaG, the top temperature is 40-60°C, and the bottom temperature is 120-140°C. Specifically, C5 and C52 are collected from the top of the first distillation column. - The distillate fraction, C6 and C62 were collected from the bottom of the first distillation column. + Distillate fraction.

[0071] In the method described in this invention, C6 and C6 + The fraction is further subjected to a second distillation to obtain the C6 fraction. In this invention, the C6 fraction contains 6 carbon atoms. In some embodiments, the second distillation is carried out in a second distillation column. Specifically, the second distillation column has 40-60 theoretical plates, a reflux ratio of 5-15, a top temperature of 55-65°C, and a bottom temperature of 90-120°C. Specifically, the C6 fraction is collected from the top of the second distillation column, and C7 and C8 fractions are collected from the bottom of the second distillation column. + Distillate fraction.

[0072] In the method described in this invention, the C6 fraction is subjected to hydrodeoxygenation and chemical deoxygenation reactions sequentially to remove oxygen-containing compounds such as alcohols, ketones, and aldehydes from the C6 fraction. Compared to the extraction deoxygenation method used in the prior art, the combination of hydrodeoxygenation and chemical deoxygenation employed in this invention ensures a low oxide content in the separated 1-hexene product, and the deoxygenation adsorption tower can operate for extended periods, ensuring the stability of the overall process.

[0073] In the method described in this invention, the first deoxygenation reaction involves hydrogenating the C6 fraction with hydrogen in the presence of the first deoxygenation catalyst to remove aldehyde oxides and ketone oxides from the C6 fraction.

[0074] In some preferred embodiments, the first deoxygenation catalyst further comprises a first metal, a second metal, and a first support. The first metal is Cu and / or Pt, the second metal is selected from at least one of Ag, Au, Pd, Fe, and Co, and the first support is at least one of SiO2, Al2O3, and TiO2. Specifically, the first metal and the second metal are the active components of the first deoxygenation catalyst, and both the first metal and the second metal are supported on the first support. The first metal and the second metal may exist in the form of metal oxides and / or elemental forms, preferably in the form of elemental metals.

[0075] In the method described in this invention, in order to ensure that the first metal and the second metal in the first deoxygenation catalyst exert maximum catalytic activity, the first deoxygenation catalyst is further required to undergo reduction treatment in hydrogen before use. The reduction conditions are: hydrogen pressure 0.001-1.0 MPa, hydrogen flow rate 50-200 mL / min, reduction temperature 400-600℃, and reduction time 4-10 h.

[0076] In some preferred embodiments, the weight ratio of the first metal to the second metal in the first deoxygenation catalyst is 1 to 20:1, preferably 2 to 8:1. By limiting the specific composition of the first deoxygenation catalyst, it is possible to further ensure the removal of aldehyde oxides and ketone oxides from the C6 fraction as much as possible, and further improve the purity of the 1-hexene product.

[0077] In some preferred embodiments, the preparation method of the first deoxygenation catalyst includes: adjusting the pH of a solution containing a first metal salt and a second metal salt to 6-8 using a carbonate solution to obtain a first precursor solution, then impregnating the first support in the first precursor solution, and then calcining the impregnated solid phase at 400-600°C for 2-5 hours.

[0078] In some embodiments, the immersion time is 2-4 hours and the immersion temperature is 20-40°C.

[0079] In some preferred embodiments, the first deoxygenation reaction conditions include: a reaction temperature of 50-200°C and a volume hourly space velocity of 0.01-8 h⁻¹. -1 The pressure is 1-10 MPa.

[0080] In the method described in this invention, the bimetallic active structure contained in the first deoxygenation catalyst can improve the catalytic performance and selectivity of the first deoxygenation catalyst, reduce olefin loss, and improve the removal rate of aldehyde oxides and ketone oxides in C6 fraction due to the strong interaction between species.

[0081] In the method described in this invention, the second deoxygenation reaction is carried out in the presence of the second deoxygenation catalyst. The second deoxygenation reaction is a chemical deoxygenation reaction used to remove alcohol oxides from the C6 fraction. Furthermore, in the method described in this invention, by first subjecting the C6 fraction to a hydrodeoxygenation reaction with hydrogen in the presence of the first deoxygenation catalyst to remove aldehyde oxides and ketone oxides from the C6 fraction, the reduction in activity of the second deoxygenation catalyst and catalyst poisoning caused by the aldehyde oxides and ketone oxides contained in the C6 fraction are avoided. This ensures the smooth progress of the second deoxygenation reaction and further improves the removal rate of oxygen-containing compounds in the C6 fraction, thereby increasing the concentration of 1-hexene in the separated product.

[0082] In some preferred embodiments, the second deoxygenation catalyst contains a first metal oxide, a second metal oxide, and a second support, wherein the first metal oxide is selected from at least one of TiO2, La2O3, and ThO2, the second metal oxide is selected from at least one of WO3, Mo3, and Cr2O3, and the support is at least one of SiO2, ZrO2, and Al2O3.

[0083] In some preferred embodiments, to further ensure the complete removal of alcohol oxides contained in the C6 fraction, the weight ratio of the first metal oxide to the second metal oxide in the second deoxygenation catalyst is further defined as 2 to 20:1, preferably 4 to 8:1, and the weight ratio of the total weight of the first metal oxide and the second metal oxide to the weight of the second support is 1:5 to 40, preferably 1:10 to 16.

[0084] In the method described in this invention, further defining the specific components of the second deoxygenation catalyst can further improve the catalyst selectivity and stability, further improve the removal rate of alcohol oxides, and further improve the purity of the separated 1-hexene. By sequentially subjecting the C6 fraction to the first and second deoxygenation reactions, the deoxygenation steps can be simplified while ensuring that aldehyde oxides, ketone oxides, and alcohol oxides contained in the C6 fraction are removed as much as possible, thereby further saving process costs.

[0085] In some preferred embodiments, the preparation method of the second deoxygenation catalyst includes: adjusting the pH of a solution containing the first metal oxide precursor and the second metal oxide precursor to 8-10 using ammonia water under water bath conditions of 60-95°C to obtain a second precursor solution; then immersing the second support in the second precursor solution and aging it; and then calcining the aged solid phase at 400-600°C for 4-8 hours.

[0086] In some embodiments, the immersion time is 1-2 hours and the immersion temperature is 20-40°C;

[0087] In some embodiments, the aging time is 4-6 hours and the aging temperature is 20-40°C.

[0088] In the method described in this invention, the combination of hydrodeoxygenation and chemical deoxygenation can further ensure the removal of oxygen-containing compounds from the C6 fraction, and the deoxygenation efficiency is further improved by limiting the deoxygenation catalyst used in the hydrodeoxygenation and chemical deoxygenation processes, thereby increasing the yield of high-purity 1-hexene.

[0089] In the method described in this invention, the material after the second deoxygenation reaction is etherified with a low-carbon alcohol, and the tertiary olefins in the material are further etherified with the low-carbon alcohol under the action of an etherification catalyst to generate high-boiling-point ethers. The high-boiling-point ethers are further removed to obtain a C6 fraction with tertiary olefins removed.

[0090] In some embodiments, the lower alcohol is a C1-C5 alcohol, such as at least one of methanol, ethanol, and propanol.

[0091] In some embodiments, the etherification reaction is carried out in the presence of an etherification catalyst. The etherification catalyst can be an acidic resin catalyst. The specific composition of the acidic resin catalyst used is not limited in this invention; it can be a commonly available acidic resin catalyst, such as products from Dandong Mingzhu Special Resin Co., Ltd. with brand name D005-II or DA330, products from Kerry Environmental Protection Technology Co., Ltd. with brand name Y221102, or products from Rohm and Haas with brand name A35.

[0092] In some preferred embodiments, in step (3), the weight ratio of the reacted material to the lower alcohol is 1:0.002-0.004. By further limiting the amount of reactants in the etherification reaction, the purity of the separated 1-hexene can be further guaranteed, thereby further enhancing the industrial application value of the recovered 1-hexene. Specifically, the weight ratio of the reacted material to the lower alcohol can be 1:0.002, 1:0.0025, 1:0.028, 1:0.003, 1:0.0035, or 1:0.004.

[0093] In some embodiments, the etherification reaction conditions include a temperature of 50-80°C and a time of 10-120 min.

[0094] In the method described in this invention, the feed mass hourly space velocity (WHSV) is 0.5-1 h⁻¹ during the etherification reaction. -1Specifically, the feed mass hourly space velocity (MAH) refers to the feed mass hourly space velocity of the material after the deoxygenation reaction.

[0095] In the method described in this invention, the C6 fraction from which tertiary olefins have been removed is subjected to a third distillation to remove the 1-hexene light component from the material. The 1-hexene light component refers to the remaining C6 components with a boiling point lower than that of 1-hexene, such as methylpentene and methylpentane.

[0096] In some embodiments, the third distillation is carried out in a third distillation column. Preferably, the third distillation column has 100-130 theoretical plates, a reflux ratio of 5-15, a top temperature of 55-60°C, and a bottom temperature of 60-80°C. Specifically, the top product of the third distillation column is a 1-hexene light fraction, and the bottom product of the third distillation column is sent to a fourth distillation column for a fourth distillation process to remove the 1-hexene heavy fraction from the C6 fraction after tertiary olefin removal.

[0097] In some embodiments, the fourth distillation is carried out in a fourth distillation column. Preferably, the fourth distillation column has 110-140 theoretical plates, a reflux ratio of 10-20, a top temperature of 55-65°C, a top pressure of atmospheric pressure, and a bottom temperature of 60-80°C. Specifically, the top product of the fourth distillation column is crude 1-hexene, and the bottom product is heavy 1-hexene. Specifically, the heavy 1-hexene refers to other C6 components with higher boiling points than 1-hexene, such as n-hexane, 2-hexene, and 3-hexene.

[0098] In the method described in this invention, the method further includes: sequentially drying and deeply deoxygenating the crude 1-hexene obtained from the fourth distillation.

[0099] In some embodiments, the crude 1-hexene is dried using a drying adsorbent to remove moisture. In this invention, the composition of the drying adsorbent is not limited; commonly used drying adsorbents in the art can be selected, such as one or more of silica gel, alumina, 3A molecular sieve, and 5A molecular sieve, preferably 5A molecular sieve.

[0100] In some embodiments, the dried material is subjected to deep deoxidation to further remove oxygen-containing compounds from the material, resulting in a polymer 1-hexene product with an oxide content ≤5ppm and a 1-hexene purity ≥99%.

[0101] In some embodiments, an adsorption tower is used to perform deep deoxygenation on the dried material. The adsorption tower is filled with an adsorbent, which is used to deeply remove oxygen-containing compounds from the material. Preferably, the adsorbent used in the adsorption tower is selected from one or more of silica gel, alumina, activated carbon, resin, silicates, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-34 molecular sieve, 13X molecular sieve, Y-type molecular sieve, and MCM-22 molecular sieve, with 13X molecular sieve being the most preferred.

[0102] The method described in this invention involves subjecting the C6 fraction to a first-stage hydrodeoxygenation reaction and a second-stage chemical deoxygenation reaction, and further employing a first and second deoxygenation catalyst with specific components to ensure the deep removal of oxygen-containing compounds from the C6 fraction, thereby guaranteeing the purity of the recovered 1-hexene. In addition, it further simplifies the purification process, further ensures separation efficiency, and saves separation energy consumption.

[0103] This invention further provides a system for separating 1-hexene from Fischer-Tropsch synthetic oil. Specifically, the system is used to implement the method for separating 1-hexene from Fischer-Tropsch synthetic oil described in this invention. A process flow diagram of this system can be found in the accompanying document. Figure 1 The system includes a deacidification unit 1, a first distillation column 2, a second distillation column 3, a deoxygenation unit, an etherification reactor 6, a third distillation column 7, and a fourth distillation column 8 connected in sequence.

[0104] Specifically, the deacidification unit 1 is used to deacidify the Fischer-Tropsch synthetic oil to remove acidic substances. Specifically, the deacidification unit includes an alkaline washing tower 11, a water washing tower 12, and an oil-water separation device 13. The alkaline washing tower 11 mixes the Fischer-Tropsch synthetic oil with an alkaline solution, and uses the alkaline solution to neutralize the acidic substances in the Fischer-Tropsch synthetic oil. After the reaction is complete, the resulting oil phase is sent to the water washing tower 12 for washing until neutral. After washing, the oil phase is sent to the oil-water separation device 13 for oil-water separation. The resulting oil phase material is then sent to the first distillation tower 2 for first distillation.

[0105] Specifically, the first distillation column 2 is used to perform a first distillation on the oil phase material from the oil-water separation device 13, and C5 and C5 are collected from the top of the column. - The distillate, collected from the bottom of the column, is C6 and C6. + The fraction, then the C6 and C6 + The fraction is fed to the second distillation column 3 for a second distillation.

[0106] Specifically, the second distillation column 3 is used to distill C6 and C6 from the first distillation column 2. +The fraction undergoes a second distillation. The top of the second distillation column yields the C6 fraction, and the bottoms of the second distillation column yield C7 and C8 fractions. + The C6 fraction is then transported to the deoxygenation unit for reactive deoxygenation treatment.

[0107] Specifically, the deoxygenation unit comprises a hydrodeoxygenation reactor 4 and a chemical deoxygenation reactor 5 connected in sequence. Specifically, the hydrodeoxygenation reactor 4 is filled with the first deoxygenation catalyst described above, used to remove aldehyde oxides and ketone oxides from the C6 fraction. After undergoing the first deoxygenation reaction in the hydrodeoxygenation reactor 4, the C6 fraction is further fed into the chemical deoxygenation reactor 5 for a second deoxygenation reaction. The chemical deoxygenation reactor 5 is filled with the second deoxygenation catalyst described above, used to remove alcohol oxides from the C6 fraction. By sequentially subjecting the C6 fraction to the first and second deoxygenation reactions in the deoxygenation unit, the removal of oxygen-containing compounds from the C6 fraction can be ensured as completely as possible, thereby guaranteeing a higher purity of the separated 1-hexene. The material obtained after the reaction in the chemical deoxygenation reactor 5 is further fed into the etherification reactor 6 for an etherification reaction.

[0108] Specifically, the etherification reactor 6 is filled with the etherification catalyst. The material from the chemical deoxygenation reactor 5 reacts with the low-carbon alcohol in the etherification reactor 6 to obtain a C6 fraction with tertiary olefins removed. Then, the C6 fraction with tertiary olefins removed is sent to the third distillation column 6 for third distillation.

[0109] Specifically, the third distillation column 7 is used to perform a third distillation on the C6 fraction from which tertiary olefins have been removed, to remove the 1-hexene light component from the C6 fraction. The 1-hexene light component is collected from the top of the third distillation column 7, and then the bottom fraction of the third distillation column 7 is sent to the fourth distillation column 8 for a fourth distillation process to obtain crude 1-hexene.

[0110] Specifically, the fourth distillation column 8 is used to perform a fourth distillation on the bottom product from the third distillation column 7 to remove the 1-hexene heavy component from the C6 fraction after the removal of tertiary olefins. The bottom product of the fourth distillation column 8 is the 1-hexene heavy component, and the top product is crude 1-hexene.

[0111] In the system described in this invention, the system further includes a drying unit 9 and a deep deoxygenation unit 10. Specifically, the drying unit 9 is provided with a drying tower, which is filled with a drying adsorbent for drying the crude 1-hexene from the fourth distillation tower 8 to remove moisture from the material. The processed material is then conveyed to the deep deoxygenation unit 10 for deep deoxygenation treatment.

[0112] In some preferred embodiments, the deep deoxygenation unit 10 includes a first adsorption deoxygenation unit 101 and a second adsorption deoxygenation unit 102 connected in parallel. Both the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 contain several adsorption deoxygenation towers connected in series. These towers are filled with adsorbent, which performs deep deoxygenation treatment on the oxygen-containing compounds in the material. After treatment by the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102, a high-purity 1-hexene product can be obtained.

[0113] The inventors unexpectedly discovered that the saturated adsorption capacity of the adsorbent selected in the adsorption deoxygenation tower could reach 50 mg / g. However, it was prone to penetration during deep deoxygenation, causing the oxides in the final product to exceed the target prematurely, failing to achieve the expected effect. Therefore, to further improve the purity of the separated 1-hexene product, four adsorption deoxygenation towers were used, with two towers in each of the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102. In this embodiment, the dried material was divided into two streams and transported to the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 for processing. The materials transported to the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 were processed sequentially in two adsorption deoxygenation towers connected in series before being combined and output to obtain polymer-grade 1-hexene.

[0114] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0115] The methods in the following examples and comparative examples are as follows: Figure 1 The system shown is implemented in which 1-hexene is separated from Fischer-Tropsch synthetic oil. The system includes a deacidification unit 1, a first distillation column 2, a second distillation column 3, a deoxygenation unit, an etherification reactor 6, a third distillation column 7, a fourth distillation column 8, a drying unit 9, and a deep deoxygenation unit 10 connected in sequence.

[0116] The deoxygenation unit is provided with a hydrodeoxygenation reactor 4 and a chemical deoxygenation reactor 5 connected in sequence. The hydrodeoxygenation reactor 4 is filled with the first deoxygenation catalyst, and the chemical deoxygenation reactor 5 is filled with the second deoxygenation catalyst.

[0117] The etherification reactor 6 is filled with an acidic resin catalyst, which is a product with the brand name Y221102 purchased from Kerry Environmental Protection Technology Co., Ltd.

[0118] The deep deoxygenation unit 10 includes a first adsorption deoxygenation unit 101 and a second adsorption deoxygenation unit 102 connected in parallel. Both the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 contain two adsorption deoxygenation towers connected in series, and the adsorbent used in the adsorption deoxygenation towers is 13X molecular sieve.

[0119] Preparation Example 1

[0120] CuCl2 and CoCl2 were dissolved in deionized water at a weight ratio of 5:1 to obtain a precursor solution (CuCl2 and CoCl2 are both calculated as metal elements). The pH value of the precursor solution was adjusted to 7 using sodium carbonate solution as a precipitant to obtain an impregnation solution. Then, SiO2 support (the total weight of CuCl2 and CoCl2 to the weight ratio of SiO2 support was 10:100, where CuCl2 and CoCl2 are both calculated as metal elements) was added to the impregnation solution and stirred for 3 hours to allow them to impregnate each other. The impregnated solid phase was washed with deionized water, dried at 120℃ for 10 hours, and then calcined at 500℃ for 3 hours to obtain the first deoxygenation catalyst. The first deoxygenation catalyst was reduced in hydrogen and then loaded into the hydrodeoxygenation reactor 4. The reduction conditions were: hydrogen pressure 0.005 MPa, hydrogen flow rate 100 mL / min, reduction temperature 500℃, and reduction time 5 hours.

[0121] Preparation Example 2

[0122] La(NO3)3 and Na2WO4 were mixed at a weight ratio of 10:1 (La(NO3)3 was calculated as La2O3 and Na2WO4 as WO3) and dissolved in deionized water to obtain a precursor solution. Then, under a water bath temperature of 90°C, ammonia was added to the precursor solution to adjust the pH value of the precursor solution to 9. Then, the support Al2O3 was added to the above solution and stirring was continued for 1 hour (the total weight ratio of La(NO3)3 and Na2WO4 to the support Al2O3 was 1:20, where La(NO3)3 was calculated as La2O3 and Na2WO4 as WO3). The mixture was then aged for another 5 hours. After solid-liquid separation, the obtained solid phase was washed with deionized water until neutral, dried at 120°C for 10 hours, and then calcined at 500°C for 5 hours to obtain a second deoxygenation catalyst. The second deoxygenation catalyst was then loaded into a chemical deoxygenation reactor 5.

[0123] Example 1

[0124] The Fischer-Tropsch synthetic oil is fed to the alkaline washing tower 11 and mixed with an alkaline solution to react and remove acidic substances from the Fischer-Tropsch synthetic oil. After the reaction is complete, the resulting oil phase is fed to the water washing tower 12 for washing until neutral. After washing, the oil phase is fed to the oil-water separation device 13 for oil-water separation. The resulting oil phase is then fed to the first distillation tower 2 for first distillation. The first distillation tower 2 has 60 theoretical trays, a reflux ratio of 4:1, a top pressure of 0.15 MPaG, a top temperature of 50°C, a bottom temperature of 130°C, and a feed of 30 trays. C5 and C52 are collected from the top of the first distillation tower 2. - The distillate, with C6 and C6 extracted from the bottom of the column. + The fraction, then the C6 and C6 + The distillate is fed to the second distillation column 3 for a second distillation. The second distillation column 3 has 50 theoretical trays, a reflux ratio of 12:1, atmospheric pressure, a top temperature of 55°C, a bottom temperature of 110°C, and a feed of 25 trays. The top of the second distillation column 3 yields C6 fraction, and the bottom of the second distillation column 3 yields C7 and C8 fractions. + The C6 fraction is then fed to the hydrodeoxygenation reactor 4 to undergo a first deoxygenation reaction with hydrogen in the presence of the first deoxygenation catalyst. The reacted material is then fed to the chemical deoxygenation reactor 5 to undergo a second deoxygenation reaction in the presence of a second deoxygenation catalyst. The temperature of the first deoxygenation reaction is 120°C, and the volume hourly space velocity (VHSV) is 2 h⁻¹. -1 The pressure is 3 MPa; the temperature of the second deoxygenation reaction is 180 °C, and the volume hourly space velocity is 1 h⁻¹. -1 The pressure is 0.2 MPa;

[0125] The reacted material from the chemical deoxygenation reactor 5 is mixed with methanol and fed into the etherification reactor 6 for etherification in the presence of an acidic resin catalyst. The etherification reaction is carried out at 60°C for 50 minutes, yielding a C6 fraction free of tertiary olefins. This C6 fraction is then fed into a third distillation column 7 for third distillation to remove the 1-hexene light component from the material. The third distillation column 7 has 110 theoretical plates, a reflux ratio of 12:1, and a top temperature of 55°C. The bottom temperature of the column is 70°C, and 55 trays are fed. The top product of the third distillation column 7 is 1-hexene light component. The bottom product of the third distillation column 7 is sent to the fourth distillation column 8 for fourth distillation treatment to remove the 1-hexene heavy component from the material. The fourth distillation column 8 has a theoretical number of trays of 130, a reflux ratio of 15:1, a top temperature of 55°C, a bottom temperature of 70°C, and 65 trays are fed. The bottom product of the fourth distillation column 8 is 1-hexene heavy component, and the top product is crude 1-hexene.

[0126] The crude 1-hexene is conveyed to the drying tower of the drying unit 9 for drying to remove moisture. Then, the processed material is divided into two streams and conveyed to the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 for deep deoxygenation treatment. After treatment, a polymer-grade 1-hexene product with a purity ≥99%, a water content ≤5ppm, and an oxide content ≤5ppm is obtained, wherein the purity of 1-hexene is 99.3%.

[0127] Example 2

[0128] The Fischer-Tropsch synthetic oil is fed to the alkaline washing tower 11 and mixed with an alkaline solution to react and remove acidic substances from the Fischer-Tropsch synthetic oil. After the reaction is complete, the resulting oil phase is fed to the water washing tower 12 for washing until neutral. After washing, the oil phase is fed to the oil-water separation device 13 for oil-water separation. The resulting oil phase is then fed to the first distillation tower 2 for first distillation. The first distillation tower 2 has 60 theoretical trays, a reflux ratio of 4:1, a top pressure of 0.15 MPaG, a top temperature of 55°C, a bottom temperature of 130°C, and a feed of 30 trays. C5 and C52 are collected from the top of the first distillation tower 2. - The distillate, with C6 and C6 extracted from the bottom of the column. + The fraction, then the C6 and C6 + The fraction is fed to the second distillation column 3 for a second distillation. The second distillation column 3 has 50 theoretical trays, a reflux ratio of 12:1, atmospheric pressure, a top temperature of 58°C, a bottom temperature of 115°C, and a feed of 25 trays. The top of the second distillation column 3 yields C6 fraction, and the bottom of the second distillation column 3 yields C7 and C8 fractions. +The C6 fraction is then fed to the hydrodeoxygenation reactor 4 to undergo a first deoxygenation reaction with hydrogen in the presence of the first deoxygenation catalyst. The reacted material is then fed to the chemical deoxygenation reactor 5 to undergo a second deoxygenation reaction in the presence of a second deoxygenation catalyst. The first deoxygenation reaction is carried out at a temperature of 180°C and a volume hourly space velocity (VHSV) of 6 h⁻¹. -1 The pressure was 5 MPa; the temperature of the second deoxygenation reaction was 250 °C, and the volume hourly space velocity was 1.5 h⁻¹. -1 The pressure is 0.5 MPa;

[0129] The reacted material from the chemical deoxygenation reactor 5 is mixed with methanol and fed into the etherification reactor 6 for etherification in the presence of an acidic resin catalyst. The etherification reaction is carried out at 65°C for 40 minutes, yielding a C6 fraction free of tertiary olefins. This C6 fraction is then fed into a third distillation column 7 for third distillation to remove the 1-hexene light component from the material. The third distillation column 7 has 110 theoretical plates, a reflux ratio of 12:1, and a top temperature of 58°C. The bottom temperature of the column is 80℃, and 55 trays are fed. The top product of the third distillation column 7 is 1-hexene light component. The bottom product of the third distillation column 7 is sent to the fourth distillation column 8 for fourth distillation treatment to remove the 1-hexene heavy component from the material. The fourth distillation column 8 has a theoretical number of trays of 130, a reflux ratio of 15:1, a top temperature of 58℃, a bottom temperature of 80℃, and 65 trays are fed. The bottom product of the fourth distillation column 8 is 1-hexene heavy component, and the top product is crude 1-hexene.

[0130] The crude 1-hexene is conveyed to the drying tower of the drying unit 9 for drying to remove moisture. Then, the processed material is divided into two streams and conveyed to the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 for deep deoxygenation treatment. After treatment, a polymer-grade 1-hexene product with a purity ≥99%, a water content ≤5ppm, and an oxide content ≤5ppm is obtained, wherein the purity of 1-hexene is 99.4%.

[0131] Example 3

[0132] The Fischer-Tropsch synthetic oil is fed to the alkaline washing tower 11 and mixed with an alkaline solution to react and remove acidic substances from the Fischer-Tropsch synthetic oil. After the reaction is complete, the resulting oil phase is fed to the water washing tower 12 for washing until neutral. After washing, the oil phase is fed to the oil-water separation device 13 for oil-water separation. The resulting oil phase is then fed to the first distillation tower 2 for first distillation. The first distillation tower 2 has 60 theoretical trays, a reflux ratio of 4:1, a top pressure of 0.15 MPaG, a top temperature of 60°C, a bottom temperature of 140°C, and a feed of 30 trays. C5 and C52 are collected from the top of the first distillation tower 2. - The distillate, with C6 and C6 extracted from the bottom of the column. + The fraction, then the C6 and C6 + The fraction is fed to the second distillation column 3 for a second distillation. The second distillation column 3 has 50 theoretical trays, a reflux ratio of 12:1, atmospheric pressure, a top temperature of 63°C, a bottom temperature of 120°C, and a feed of 25 trays. The top of the second distillation column 3 yields C6 fraction, and the bottom of the second distillation column 3 yields C7 and C8 fractions. + The C6 fraction is then fed to the hydrodeoxygenation reactor 4 to undergo a first deoxygenation reaction with hydrogen in the presence of the first deoxygenation catalyst. The reacted material is then fed to the chemical deoxygenation reactor 5 to undergo a second deoxygenation reaction in the presence of a second deoxygenation catalyst. The temperature of the first deoxygenation reaction is 100°C, and the volume hourly space velocity (VHSV) is 1 h⁻¹. -1 The pressure is 4 MPa; the temperature of the second deoxygenation reaction is 300 °C, and the volume hourly space velocity is 1 h⁻¹. -1 The pressure is 0.1 MPa;

[0133] The reacted material from the chemical deoxygenation reactor 5 is mixed with methanol and fed into the etherification reactor 6 for etherification in the presence of an acidic resin catalyst. The etherification reaction is carried out at 70°C for 35 minutes, yielding a C6 fraction free of tertiary olefins. This C6 fraction is then fed into a third distillation column 7 for third distillation to remove the 1-hexene light component from the material. The third distillation column 7 has 110 theoretical plates, a reflux ratio of 12:1, and a top temperature of 60°C. The bottom temperature of the column is 80℃, and 55 trays are fed. The top product of the third distillation column 7 is 1-hexene light component. The bottom product of the third distillation column 7 is sent to the fourth distillation column 8 for fourth distillation treatment to remove the 1-hexene heavy component from the material. The fourth distillation column 8 has a theoretical number of trays of 130, a reflux ratio of 15:1, a top temperature of 65℃, a bottom temperature of 75℃, and 65 trays are fed. The bottom product of the fourth distillation column 8 is 1-hexene heavy component, and the top product is crude 1-hexene.

[0134] The crude 1-hexene is conveyed to the drying tower of the drying unit 9 for drying to remove moisture. Then, the processed material is divided into two streams and conveyed to the first adsorption deoxygenation unit 101 and the second adsorption deoxygenation unit 102 for deep deoxygenation treatment. After treatment, a polymer-grade 1-hexene product with a purity ≥99%, a water content ≤5ppm, and an oxide content ≤5ppm is obtained, wherein the purity of 1-hexene is 99.3%.

[0135] Example 4

[0136] The method described in Example 1 is followed, except that the preparation method of the first deoxygenation catalyst packed in the hydrodeoxygenation reactor 4 is as follows:

[0137] CuCl2 and CoCl2 were dissolved in deionized water at a weight ratio of 25:1 to obtain a precursor solution (CuCl2 and CoCl2 are both calculated as metal elements). The pH value of the precursor solution was adjusted to 7 using sodium carbonate solution as a precipitant to obtain an impregnation solution. Then, SiO2 support (the total weight of CuCl2 and CoCl2 to the weight ratio of SiO2 support was 10:100, where CuCl2 and CoCl2 are both calculated as metal elements) was added to the impregnation solution and stirred for 3 hours to allow them to impregnate each other. The impregnated solid phase was washed with deionized water, dried at 120℃ for 10 hours, and then calcined at 500℃ for 3 hours to obtain the first deoxygenation catalyst. The first deoxygenation catalyst was reduced in hydrogen and then loaded into the hydrodeoxygenation reactor 4. The reduction conditions were: hydrogen pressure 0.005 MPa, hydrogen flow rate 100 mL / min, reduction temperature 500℃, and reduction time 5 hours.

[0138] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 99%.

[0139] Example 5

[0140] The method described in Example 1 is followed, except that the preparation method of the second deoxygenation catalyst packed in the hydrodeoxygenation reactor 4 is as follows:

[0141] La(NO3)3 and Na2WO4 were mixed at a weight ratio of 25:1 (La(NO3)3 was calculated as La2O3 and Na2WO4 as WO3) and dissolved in deionized water to obtain a precursor solution. Then, under a water bath temperature of 90°C, ammonia was added to the precursor solution to adjust the pH value of the precursor solution to 9. Then, the support Al2O3 was added to the above solution and stirring was continued for 1 hour (the total weight of La(NO3)3 and Na2WO4 to the weight of support Al2O3 was 1:20, where La(NO3)3 was calculated as La2O3 and Na2WO4 as WO3). The mixture was then aged for another 5 hours. After solid-liquid separation, the obtained solid phase was washed with deionized water until neutral, dried at 120°C for 10 hours, and then calcined at 500°C for 5 hours to obtain a second deoxygenation catalyst. The second deoxygenation catalyst was then loaded into a chemical deoxygenation reactor 5.

[0142] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 99%.

[0143] Comparative Example 1

[0144] The method described in Example 1 is followed, except that the preparation method of the first deoxygenation catalyst packed in the hydrodeoxygenation reactor 4 is as follows:

[0145] CuCl2 was dissolved in deionized water to obtain a precursor solution. The pH of the precursor solution was adjusted to 7 using sodium carbonate solution as a precipitant to obtain an impregnation solution. Then, SiO2 support (the weight ratio of CuCl2 to SiO2 support was 10:100, where CuCl2 was calculated as a metal element) was added to the impregnation solution and stirred for 3 hours to allow them to impregnate each other. The impregnated solid phase was washed with deionized water, dried at 120°C for 10 hours, and then calcined at 500°C for 3 hours to obtain the first deoxygenation catalyst. The first deoxygenation catalyst was reduced in hydrogen and then loaded into the hydrodeoxygenation reactor 4. The reduction conditions were: hydrogen pressure 0.005 MPa, hydrogen flow rate 100 mL / min, reduction temperature 500°C, and reduction time 5 hours.

[0146] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 98.8%.

[0147] Comparative Example 2

[0148] The method described in Example 1 is followed, except that the preparation method of the second deoxygenation catalyst packed in the chemical deoxygenation reactor 5 is as follows:

[0149] La(NO3)3 was dissolved in deionized water to obtain a precursor solution. Then, under a water bath temperature of 90°C, ammonia was added to the precursor solution to adjust the pH value of the precursor solution to 9. Then, Al2O3 support was added to the above solution and stirring was continued for 1 hour (the weight ratio of La(NO3)3 to Al2O3 support was 1:20, where La(NO3)3 was calculated as La2O3). After aging for another 5 hours, solid-liquid separation was performed. The obtained solid phase was washed with deionized water until neutral, dried at 120°C for 10 hours, and then calcined at 500°C for 5 hours to obtain a second deoxygenation catalyst. The second deoxygenation catalyst was loaded into the chemical deoxygenation reactor 5.

[0150] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 98.5%.

[0151] Comparative Example 3

[0152] The method described in Example 1 is followed, except that the preparation method of the first deoxygenation catalyst packed in the hydrodeoxygenation reactor 4 is as follows:

[0153] CuCl2 and ZnCl2 were dissolved in deionized water at a weight ratio of 5:1 to obtain a precursor solution (CuCl2 and ZnCl2 are both calculated as metal elements). The pH value of the precursor solution was adjusted to 7 using sodium carbonate solution as a precipitant to obtain an impregnation solution. Then, SiO2 support (the total weight of CuCl2 and ZnCl2 to the weight ratio of SiO2 support was 10:100, where CuCl2 and ZnCl2 are both calculated as metal elements) was added to the impregnation solution and stirred for 3 hours to allow them to impregnate each other. The impregnated solid phase was washed with deionized water, dried at 120℃ for 10 hours, and then calcined at 500℃ for 3 hours to obtain the first deoxygenation catalyst. The first deoxygenation catalyst was reduced in hydrogen and then loaded into the hydrodeoxygenation reactor 4. The reduction conditions were: hydrogen pressure 0.005 MPa, hydrogen flow rate 100 mL / min, reduction temperature 500℃, and reduction time 5 hours.

[0154] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 98.8%.

[0155] Comparative Example 4

[0156] The method described in Example 1 is followed, except that the preparation method of the second deoxygenation catalyst packed in the chemical deoxygenation reactor 5 is as follows:

[0157] La(NO3)3 and CuCl2 were mixed at a weight ratio of 10:1 (La(NO3)3 was calculated as La2O3 and CuCl2 as CuO) and dissolved in deionized water to obtain a precursor solution. Then, under the condition of 90°C in a water bath, ammonia was added to the precursor solution to adjust the pH value of the precursor solution to 9. Then, Al2O3 support was added to the above solution and stirring was continued for 1 hour (the total weight of La(NO3)3 and CuCl2 to the weight of Al2O3 support was 1:20, where La(NO3)3 was calculated as La2O3 and CuCl2 as CuO). After aging for another 5 hours, solid-liquid separation was performed. The obtained solid phase was washed with deionized water until neutral, dried at 120°C for 10 hours, and then calcined at 500°C for 5 hours to obtain a second deoxygenation catalyst. The second deoxygenation catalyst was loaded into the chemical deoxygenation reactor 5.

[0158] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 98.7%.

[0159] Comparative Example 5

[0160] The method of Example 1 is implemented, except that the C6 fraction is fed to the hydrodeoxygenation reactor 4 for a first deoxygenation reaction, and then the reacted material obtained from the hydrodeoxygenation reactor 4 is mixed with methanol and fed to the etherification reactor 6 for an etherification reaction in the presence of an acidic resin catalyst.

[0161] The purity of 1-hexene in the separated polymer-grade 1-hexene product is 98.2%, and the adsorption deoxygenation regeneration cycle is significantly reduced.

[0162] Comparative Example 6

[0163] The method of Example 1 is implemented, except that the C6 fraction is sent to the chemical deoxygenation 5 for a second deoxygenation reaction, and then the reacted material obtained in the chemical deoxygenation 5 is mixed with methanol and sent to the etherification reactor 6 for etherification reaction in the presence of an acidic resin catalyst.

[0164] The purity of 1-hexene in the separated polymer-grade 1-hexene product was 98.3%.

[0165] Comparative Example 7

[0166] The method of Example 1 is implemented, except that the deoxygenation unit in the system is replaced with an adsorption deoxygenation reactor.

[0167] Because the adsorbent is easily penetrated in the presence of a large number of oxides, the purity of the product decreases. At the same time, the regeneration cycle of the adsorbent is greatly reduced. The purity of 1-hexene in the separated polymer-grade 1-hexene product is 98.1%.

[0168] As can be seen from the examples and comparative examples, the method described in this invention can further improve the purity of the separated 1-hexene product, further simplify the purification process, and save system energy consumption.

[0169] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for separating 1-hexene from Fischer-Tropsch synthetic oil, characterized in that, The method includes the following steps: (1) The Fischer-Tropsch synthetic oil was deacidified, and then the resulting material was subjected to a first distillation to obtain C6 and C62. + distillate; (2) The C6 and C6 + The fraction was subjected to a second distillation to obtain the C6 fraction; (3) In the presence of the first deoxygenation catalyst, the C6 fraction and hydrogen are subjected to a first deoxygenation reaction, and then the reacted material is subjected to a second deoxygenation reaction in the presence of the second deoxygenation catalyst. Then the reacted material is subjected to an etherification reaction with a low alcohol to obtain a C6 fraction with tertiary olefins removed. (4) The C6 fraction after the removal of tertiary olefins is subjected to a third and a fourth distillation in sequence; The first deoxygenation catalyst contains a first metal, a second metal, and a first support. The first metal is Cu and / or Pt, the second metal is selected from at least one of Ag, Au, Pd, Fe, and Co, and the first support is at least one of SiO2, Al2O3, and TiO2. The second deoxygenation catalyst contains a first metal oxide, a second metal oxide, and a second support. The first metal oxide is selected from at least one of TiO2, La2O3, and ThO2, the second metal oxide is selected from at least one of WO3, Mo3, and Cr2O3, and the second support is at least one of SiO2, ZrO2, and Al2O3.

2. The method according to claim 1, characterized in that, In the first deoxygenation catalyst, the weight ratio of the first metal to the second metal is 1 to 20:

1.

3. The method according to claim 1 or 2, characterized in that, In the second deoxygenation catalyst, the weight ratio of the first metal oxide to the second metal oxide is 2 to 20:1, and the ratio of the total weight of the first metal oxide and the second metal oxide to the weight of the second support is 1:5 to 40.

4. The method according to any one of claims 1-3, characterized in that, The conditions for the first deoxygenation reaction include: a reaction temperature of 50-200℃ and a volume hourly space velocity of 0.01-8 h⁻¹. -1 The pressure is 1-10 MPa; and / or The conditions for the second deoxygenation reaction include: a temperature of 160-350℃ and a space velocity of 1-2 h⁻¹. -1 The pressure is 0.01-0.5 MPa.

5. The method according to any one of claims 1-4, characterized in that, Before use, the first deoxygenation catalyst is reduced in hydrogen gas. The reduction conditions are: hydrogen pressure 0.001-1.0 MPa, hydrogen flow rate 50-200 mL / min, reduction temperature 400-600℃, and reduction time 4-10 h.

6. The method according to any one of claims 1-5, characterized in that, The first distillation is carried out in a first distillation column, which has a theoretical plate number of 40-60 and a reflux ratio of 4-12. Preferably, the top pressure of the first distillation column is 0.1-0.2 MPaG, the top temperature is 40-60℃, and the bottom temperature is 120-140℃.

7. The method according to any one of claims 1-6, characterized in that, The second distillation is carried out in a second distillation column, which has a theoretical plate number of 40-60 and a reflux ratio of 5-15. Preferably, the top temperature of the second distillation column is 55-65℃, and the bottom temperature is 90-120℃.

8. The method according to any one of claims 1-7, characterized in that, The preparation method of the first deoxygenation catalyst includes: adjusting the pH value of a solution containing a first metal salt and a second metal salt to 6-8 using a carbonate solution to obtain a first precursor solution, then impregnating the first support in the first precursor solution, and then calcining the impregnated solid phase at 400-600℃ for 2-5 hours. Preferably, the immersion time is 2-4 hours and the immersion temperature is 20-40°C.

9. The method according to any one of claims 1-8, characterized in that, The preparation method of the second deoxygenation catalyst includes: adjusting the pH value of the solution containing the first metal oxide precursor and the second metal oxide precursor to 8-10 with ammonia water under water bath conditions of 60-95℃ to obtain a second precursor solution; then immersing the second support in the second precursor solution and aging it; and then calcining the aged solid phase at 400-600℃ for 4-8h. Preferably, the immersion time is 1-2 hours and the immersion temperature is 20-40°C; Preferably, the aging time is 4-6 hours and the aging temperature is 20-40℃.

10. The method according to any one of claims 1-9, characterized in that, The lower alcohols are C1-C5 alcohols; Preferably, in step (3), the weight ratio of the reacted material to the low-carbon alcohol is 1:0.002-0.004; Preferably, the conditions for the etherification reaction include: a temperature of 50-80°C and a time of 10-120 min; Preferably, the etherification reaction is carried out in the presence of an acidic resin catalyst.

11. The method according to any one of claims 1-10, characterized in that, The third distillation is carried out in a third distillation column, which has a theoretical plate number of 100-130 and a reflux ratio of 5-15. Preferably, the top temperature of the third distillation column is 55-60°C, and the bottom temperature is 60-80°C. Preferably, the bottom product of the third distillation column is subjected to a fourth distillation; Preferably, the fourth distillation is carried out in a fourth distillation column, the fourth distillation column having a theoretical plate number of 110-140 and a reflux ratio of 10-20; Preferably, the top temperature of the fourth distillation column is 55-65℃, and the bottom temperature is 60-80℃.

12. The method according to any one of claims 1-11, characterized in that, The method further includes: sequentially drying and deeply deoxygenating the crude 1-hexene obtained from the fourth distillation; Preferably, an adsorption tower is used to perform deep deoxygenation on the dried material; Preferably, the adsorbent used in the adsorption tower is selected from one or more of silica gel, alumina, activated carbon, resin, silicates, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-34 molecular sieve, 13X molecular sieve, Y-type molecular sieve and MCM-22 molecular sieve, with 13X molecular sieve being the most preferred.

13. A system for separating 1-hexene from Fischer-Tropsch synthetic oil, characterized in that, The system is used to implement the method according to any one of claims 1-12, and the system includes a deacidification unit (1), a first distillation column (2), a second distillation column (3), a deoxygenation unit, an etherification reactor (6), a third distillation column (7), and a fourth distillation column (8) connected in sequence. The deacidification unit (1) is used to deacidify the Fischer-Tropsch synthetic oil to remove acidic substances from the Fischer-Tropsch synthetic oil. The first distillation column (2) is used to perform a first distillation on the material from the deacidification unit (1) to obtain C6 and C62. + distillate; The second distillation column (3) is used to distill the C6 and C6 + The fraction was subjected to a second distillation to obtain the C6 fraction; The deoxygenation unit is provided with a hydrodeoxygenation reactor (4) and a chemical deoxygenation reactor (5) connected in sequence. The hydrodeoxygenation reactor (4) is filled with the first deoxygenation catalyst for removing aldehyde oxides and ketone oxides from the C6 fraction. The chemical deoxygenation reactor (5) is filled with the second deoxygenation catalyst for removing alcohol oxides from the C6 fraction; The etherification reactor (6) is filled with the acidic resin catalyst. The material from the chemical deoxygenation reactor (5) and the low alcohol undergo an etherification reaction in the etherification reactor (6) to obtain a C6 fraction with tertiary olefins removed. The third distillation column (7) is used to perform a third distillation on the C6 fraction from which tertiary olefins have been removed; The fourth distillation column (8) is used to perform a fourth distillation on the bottom material from the third distillation column (7) to obtain crude 1-hexene.

14. The system according to claim 13, characterized in that, The system also includes a drying unit (9) and a deep deoxygenation unit (10); The drying unit (9) is used to dry the crude 1-hexene and then transport it to the deep deoxygenation unit (10) for deep deoxygenation. Preferably, the deep deoxygenation unit (10) is provided with a first adsorption deoxygenation unit (101) and a second adsorption deoxygenation unit (102) connected in parallel. Both the first adsorption deoxygenation unit (101) and the second adsorption deoxygenation unit (102) are provided with a plurality of adsorption deoxygenation towers connected in series.

Images