Method for separating ultra-high-purity alpha-olefin from Fischer-Tropsch synthesis light oil

Abstract

The invention discloses a method for separating ultra-high-purity alpha-olefin from Fischer-Tropsch synthesis light oil, which comprises the following steps of: introducing a Fischer-Tropsch synthesis light oil raw material into an etherification reaction tower filled with an etherification catalyst, and reacting mixed alcohol and mixed isoolefin in the Fischer-Tropsch synthesis oil in the tower to generate ethers; introducing a product of the etherification reaction tower into a deoxidation tower, and removing oxygen-containing compounds in the oil product; introducing a deoxidation tower product into an alkane-alkene separation simulated moving bed, and separating alkene from alkane to obtain a lean alkene component and a rich alkene component; and introducing the olefin-rich component into an olefin-rich component rectifying tower, separating the olefin from the desorption agent to obtain an olefin-rich product with the purity of mixed alpha-olefin being greater than 99.5%, and rectifying and separating the mixed alpha-olefin to obtain single-carbon alpha-olefin with the purity being greater than 99.5%. By increasing the etherification reaction of the mixed alcohol and the mixed isoolefin in the raw material, the content of the isoolefin and the normal alcohol in the raw material is greatly reduced, and the mixed alpha-olefin product with the purity of more than 99.5% is obtained.

Description

Technical Field

[0001] The invention relates to the field of chemical engineering and technology, and in particular to a method for separating ultra-high purity alpha-olefins from Fischer-Tropsch synthetic light oil. Background Art

[0002] Fischer-Tropsch synthetic oil products contain a large amount of valuable chemical raw materials - α-olefins. α-olefins are key raw materials for the production of other fine chemical products and have a very significant impact on its downstream industries. At present, the subsequent processing methods for Fischer-Tropsch synthetic oil products at home and abroad are mainly concentrated in distillation, extraction and simulated moving bed separation. Although a high separation effect has been achieved for the separation of alkanes and olefins, the separation of α-olefins and isoolefins in olefins has not been reported, and isoolefins are the key factor that ultimately affects the purity of α-olefins.

[0003] Prior art CN111647423A discloses a method for separating α-olefins by a simulated moving bed, which comprises using coal-based Fischer-Tropsch synthetic oil as a raw material, the target olefin carbon number N ranges from 9 to 18, and the raw material undergoes pretreatment, fraction cutting, alkane-olefin separation, isomer separation and other processing steps to obtain a high-purity α-olefin product. Compared with traditional distillation and extraction processes, the method of the present invention obtains a product with higher purity, higher yield, lower energy consumption, and significantly reduced production costs.

[0004] Prior art CN109627137A discloses a method for separating olefins from coal-based Fischer-Tropsch light distillate oil, comprising the following steps: (1) deacidifying the Fischer-Tropsch light distillate oil raw material; (2) adsorbing the deacidified distillate oil to remove carbonyl compounds. (3) The deacidified distillate oil enters a light-removing tower; components with a carbon number less than n are separated from the top of the light-removing tower, and components at the bottom enter a heavy-removing tower; components with a carbon number greater than n are separated from the bottom of the heavy-removing tower, and components with a carbon number of n are separated from the top of the heavy-removing tower; (4) components with a carbon number of n enter an extractive distillation tower, and are in reverse contact with an extractant, non-polar alkanes are separated from the top of the tower, and the extractant and target olefins are distilled from the bottom of the tower and enter a recovery tower; (5) The target olefin is distilled from the top of the recovery tower, and the extractant is distilled from the bottom of the tower and circulated into the extractive distillation tower. Since it is the preparation of high-carbon olefins, negative pressure distillation is used to prevent olefin cracking, thereby ensuring the integrity of the olefin structure.

[0005] Prior art CN115011376A discloses a method for separating α-olefins by coupling olefins with adsorption distillation of Fischer-Tropsch light fraction oil. Fischer-Tropsch synthesized light fraction oil is cut into C4-C10 fraction segments; first, the organic oxygen-containing compounds in the C4-C10 fraction segment are deeply removed by simulating a moving bed, a fixed bed or other adsorption separation process; then, the adsorption distillation technology is used to accurately separate the alkanes and olefins in the deoxygenated C4-C10 fraction oil to obtain high-purity α-olefins. The adsorption distillation technology couples the advantages of distillation and adsorption separation technology, and synergistically adsorbs during the distillation process, and finally separates the alkanes and olefins of the fractions that are similar, and then obtains the high-purity target product α-olefins through deep distillation. Compared with the existing technology for Fischer-Tropsch oil alkane-olefin separation, the present invention breaks the original technical barriers, realizes the precise separation of similar fraction products, improves the separation purity of α-olefins, and increases the added value of products.

[0006] From the above, we can see that the current Fischer-Tropsch oil olefin purification process technology is mainly based on extraction and simulated moving bed technology. The purity of the final α-olefin product is limited by the content of isomerized olefins in the raw materials, so the purity of the α-olefin product has a certain room for improvement. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for separating ultra-high purity α-olefins from Fischer-Tropsch synthetic light oil.

[0008] The present invention is achieved by adopting the following technical solutions.

[0009] A method for separating ultra-high purity alpha-olefins from Fischer-Tropsch light oil comprises the following steps:

[0010] The Fischer-Tropsch light oil raw material is passed into an etherification reaction tower equipped with an etherification catalyst, and mixed alcohols and mixed isoolefins in the Fischer-Tropsch synthetic oil in the tower react to generate ethers; the product of the etherification reaction tower is passed into a deoxygenation tower to remove oxygenated compounds in the oil product; the product of the deoxygenation tower is passed into an alkane-olefin separation simulated moving bed to separate olefins from alkanes to obtain olefin-poor components and olefin-rich components; the olefin-rich component is passed into an olefin-rich component distillation tower to separate olefins from desorbents to obtain an olefin-rich product with a mixed α-olefin purity greater than 99.5%. The mixed α-olefin is then subjected to distillation separation to obtain a single carbon α-olefin with a purity greater than 99.5%.

[0011] By adopting the above technical scheme, the present invention significantly reduces the content of isoolefins and normal alcohols in the raw materials by increasing the etherification reaction of mixed alcohols and mixed isoolefins in the raw materials, the removal rate of isoolefins is greater than 98%, and the content of normal alcohols is reduced by 98%; the product of the etherification reaction tower is passed into the deoxygenation tower to remove oxygenated compounds in the oil products, and the oxides are removed to less than 0.1 μg / g; after the product of the deoxygenation tower is passed into the simulated moving bed for alkane-olefin separation, the olefin-rich component is passed into the olefin-rich component distillation tower to separate olefins from desorbents, and a high-purity mixed α-olefin product can be obtained, and the α-olefin purity is greater than 99.5%. After simple distillation, a single carbon high-value-added α-olefin product can be obtained. The method of the present invention has low energy consumption, high economic value, and strong market competitiveness.

[0012] Furthermore, the distillation range of the Fischer-Tropsch synthesis light oil feedstock is 30°C to 160°C.

[0013] Furthermore, the mixed alcohol is all alcohols of C2 to C6.

[0014] Furthermore, the etherification catalyst in the etherification reaction tower is composed of a main agent and a binder, the mass content of the main agent is greater than 95%, the main agent is a mixture of one or more of ZSM-5 zeolite, Y zeolite, and macroporous resin; the binder is a mixture of one or more of bentonite, attapulgite, and diatomaceous earth.

[0015] Furthermore, the reaction temperature of the etherification reaction tower is 50-200°C, the reaction pressure is 0.1-2.0 MPa, and the reaction volume space velocity is 0.05-2h -1 .

[0016] Furthermore, the mass content of active components of the adsorbent in the deoxygenation tower is greater than 90%, and the active component is USY molecular sieve.

[0017] Furthermore, the adsorption temperature of the deoxidation tower is 30-80°C, the height-to-diameter ratio of the adsorption tower is 3-9, and the adsorption volume space velocity is 0.3-2h -1 , adsorption pressure 0.3~1.0MPa.

[0018] Furthermore, the simulated moving bed for alkane-olefin separation adopts a simulated moving bed with 12 to 24 beds, an operating temperature of 60 to 80° C., and a pressure of 0.2 to 0.8 MPa; the desorbent is a mixture of n-dodecene and n-dodecane, wherein n-dodecene accounts for 20% to 60% of the mass fraction of the desorbent.

[0019] Furthermore, the filling material of the olefin-rich component distillation tower is one of ball rings and Raschig rings, the number of plates of the distillation tower is 40-50, the absolute pressure of the distillation tower is 5-20 kPa, and the temperature of the tower bottom is 130-180°C.

[0020] This application has the following beneficial effects.

[0021] The present invention adds a raw material etherification pretreatment section on the basis of the existing simulated moving bed technology, converts isoolefins into ether oxides, removes these oxides by deoxygenation, and finally obtains high-purity single-carbon α-olefin products. The purity of the α-olefin products is greater than 99.5%, which solves the problem that isoolefins cannot be separated by extraction and adsorption methods, realizes the efficient separation of α-olefins in Fischer-Tropsch synthetic oil, and provides strong technical support for the subsequent market application of α-olefins. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a process flow chart of the present invention;

[0023] Among them, 1. Etherification reaction tower; 2. Deoxygenation tower; 3. Alkane-olefin separation simulated moving bed; 4. Olefin-rich component distillation tower. DETAILED DESCRIPTION

[0024] The present patent application is further described below in conjunction with embodiments.

[0025] Unless otherwise specified, the experimental methods used in the following preparation examples and embodiments are conventional methods.

[0026] A method for separating ultra-high purity alpha-olefins from Fischer-Tropsch light oil, wherein the distillation range of the Fischer-Tropsch oil raw material is 30°C to 160°C. The method firstly passes the Fischer-Tropsch oil raw material into an etherification reaction tower 1 equipped with an etherification catalyst, wherein the alcohol contained in the Fischer-Tropsch oil reacts with isoolefins to generate ethers, thereby greatly reducing the content of isoolefins and normal alcohols in the oil product, the removal rate of isoolefins is greater than 98%, and the content of normal alcohols is reduced by 98%. The product of the etherification reaction tower 1 is passed into a deoxygenation tower 2 to remove oxygenated compounds in the oil product, and the oxides are removed to less than 0.1 μg / g. The product of the deoxygenation tower 2 is passed into an alkane-olefin separation simulated moving bed 3 to separate olefins from alkanes, and obtain an olefin-poor component and an olefin-rich component. The olefin-rich component is passed into an olefin-rich component distillation tower 4 to separate olefins from a desorbent, and finally a high-purity mixed alpha-olefin product is obtained, wherein the alpha-olefin purity is greater than 99.5%, and then a single-carbon high-value-added alpha-olefin product can be obtained through simple distillation.

[0027] Example 1

[0028] The raw material of Example 1 is Fischer-Tropsch synthetic oil of a certain enterprise, and its raw material hydrocarbon composition is shown in Tables 1.1 and 1.2.

[0029] Table 1.1 Fischer-Tropsch synthetic oil raw materials

[0030] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C3 0.82％ 0.82％ C4 1.47％ 1.47％ C5 3.18％ 7.10％ 0.50％ 1.35％ 12.13％ C6 4.79％ 12.51％ 0.75％ 1.86％ 19.91％ C7 5.27％ 15.15％ 0.78％ 21.20％ C8 5.28％ 16.43％ 0.87％ 22.58％ C9 5.20％ 15.72％ 0.97％ 21.89％ total 23.72％ 66.91％ 3.87％ 5.50％ 100.00％

[0031] Table 1.2 Distillation range of Fischer-Tropsch synthetic oil raw materials

[0032] Distillation range, ℃ Initial distillation point / ℃ 30 5% recovery temperature / ℃ 42 10% recovery temperature / ℃ 55 30% recovery temperature / ℃ 81 50% recovery temperature / ℃ 96 70% recovery temperature / ℃ 119 90% recovery temperature / ℃ 130 95% recovery temperature / ℃ 143 Final distillation point / ℃ 154

[0033] The Fischer-Tropsch synthetic oil enters the etherification reaction tower, which is loaded with commercially available etherification catalyst A. The reaction temperature is 110°C, the reaction pressure is 0.5 MPa, and the reaction volume space velocity is 0.5 h -1 The physical properties of etherification catalyst A are shown in Table 1.3.

[0034] Table 1.3 Physical properties of etherification catalyst A

[0035] Etherification Catalyst A Morphology Butterfly Quality composition 96% Y molecular sieve + 4% attapulgite <![CDATA[Specific surface area, m 2 / g]]> 512 Bulk ratio, g / mL 0.68

[0036] The hydrocarbon composition data of the product obtained by the Fischer-Tropsch synthetic oil after the etherification reaction tower are shown in Table 1.4.

[0037] Table 1.4 Hydrocarbon composition of reaction products after etherification

[0038]

[0039]

[0040] The reaction product after etherification is deeply deoxygenated in a deoxygenation tower. The adsorption temperature of the deoxygenation tower is 60°C, the adsorption pressure is 0.7MPa, and the adsorption volume space velocity is 0.9h -1 The height-to-diameter ratio of the adsorption tower is 7. The physical properties of adsorbent TY-1 are shown in Table 1.5. After passing through the deoxygenation adsorption tower, the oxide content of the Fischer-Tropsch synthesis light distillate oil is reduced to less than 0.1ug / g. Its hydrocarbon composition data are shown in Table 1.6.

[0041] Table 1.5 Physical properties of adsorbent TY-1

[0042] Adsorbent TY-1 Morphology 2~3mm clover type Quality composition 98% USY molecular sieve + 2% alumina <![CDATA[Specific surface area, m 2 / g]]> 590 Bulk ratio, g / mL 0.68

[0043] Table 1.6 Hydrocarbon composition of reaction products after deoxygenation

[0044]

[0045]

[0046] After deoxygenation, the reaction product is passed through an alkane-olefin separation simulated moving bed, which has 12 beds, an operating temperature of 80°C, a pressure of 0.5MPa, and a desorbent of 50% n-dodecene + 50% n-dodecane. The obtained olefin-rich component is cut by a distillation tower, the filling of the distillation tower is ball ring, the number of distillation tower plates is 45, and the absolute pressure of the distillation tower is controlled at 10kPa, the temperature of the tower bottom is controlled at 145°C, and the top temperature of the tower changes from 30 to 120°C during the distillation process. The hydrocarbon composition data of the final mixed α-olefin product is shown in Table 1.7, and the α-olefin purity of the mixed α-olefin product is 99.81%.

[0047] Table 1.7 Hydrocarbon composition of mixed α-olefin products

[0048] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C5 0.02％ 10.59％ 0.01％ 10.62％ C6 0.03％ 18.67％ 0.01％ 18.70％ C7 0.03％ 22.60％ 0.01％ 22.64％ C8 0.03％ 24.51％ 0.01％ 24.56％ C9 0.03％ 23.43％ 0.01％ 23.48％ total 0.13％ 99.81％ 0.06％ 0.00％ 100.00％

[0049] Example 2

[0050] The raw material of Example 2 is Fischer-Tropsch synthetic oil of a certain enterprise, and its raw material hydrocarbon composition is shown in Tables 2.1 and 2.2.

[0051] Table 2.1 Fischer-Tropsch synthetic oil raw materials

[0052] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C3 0.82％ 0.82％ C4 1.47％ 1.47％ C5 3.18％ 7.10％ 0.50％ 1.35％ 12.13％ C6 4.79％ 12.51％ 0.75％ 1.86％ 19.91％ C7 5.27％ 15.15％ 0.78％ 21.20％ C8 5.28％ 16.43％ 0.87％ 22.58％ C9 5.20％ 15.72％ 0.97％ 21.89％ total 23.72％ 66.91％ 3.87％ 5.50％ 100.00％

[0053] Table 2.2 Distillation range of Fischer-Tropsch synthetic oil raw materials

[0054]

[0055]

[0056] The Fischer-Tropsch synthetic oil enters the etherification reaction tower, which is loaded with commercially available etherification catalyst B. The reaction temperature is 167°C, the reaction pressure is 1.0 MPa, and the reaction volume space velocity is 0.8 h -1 The physical properties of etherification catalyst B are shown in Table 2.3.

[0057] Table 2.3 Physical properties of etherification catalyst B

[0058] Etherification Catalyst B Morphology Shamrock Quality composition 97% ZSM-5 molecular sieve + 3% bentonite <![CDATA[Specific surface area, m 2 / g]]> 445 Bulk ratio, g / mL 0.76

[0059] The hydrocarbon composition data of the product obtained by the Fischer-Tropsch synthetic oil after the etherification reaction tower are shown in Table 2.4.

[0060] Table 2.4 Hydrocarbon composition of reaction products after etherification

[0061] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C3 0.09％ 0.09％ C4 0.34％ 0.34％ C5 3.16％ 7.43％ 0.01％ 0.31％ 10.91％ C6 4.81％ 12.55％ 0.02％ 0.29％ 17.67％ C7 5.30％ 15.20％ 0.01％ 0.13％ 20.64％ C8 5.25％ 16.19％ 0.02％ 0.77％ 22.23％ C9 5.23％ 15.50％ 0.01％ 0.65％ 21.39％ C10 1.21％ 1.21％ C11 1.11％ 1.11％ C12 1.47％ 1.47％ C13 1.03％ 1.03％ C14 0.99％ 0.99％ C15 0.94％ 0.94％ total 23.75％ 66.87％ 0.05％ 9.33％ 100.00％

[0062] The reaction product after etherification is deeply deoxygenated in a deoxygenation tower. The adsorption temperature of the deoxygenation tower is 60°C, the adsorption pressure is 0.7MPa, and the adsorption volume space velocity is 0.9h -1 The height-to-diameter ratio of the adsorption tower is 7. The physical properties of adsorbent TY-1 are shown in Table 2.5. After passing through the deoxygenation adsorption tower, the oxide content of the Fischer-Tropsch synthesis light distillate oil is reduced to less than 0.1ug / g. Its hydrocarbon composition data are shown in Table 2.6.

[0063] Table 2.5 Physical properties of adsorbent TY-1

[0064] Adsorbent TY-1 Morphology 2~3mm clover type Quality composition 98% USY molecular sieve + 2% alumina <![CDATA[Specific surface area, m 2 / g]]> 590 Bulk ratio, g / mL 0.68

[0065] Table 2.6 Hydrocarbon composition of reaction products after deoxygenation

[0066] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C5 3.48％ 8.19％ 0.01％ 11.68％ C6 5.30％ 13.84％ 0.02％ 19.16％ C7 5.85％ 16.76％ 0.01％ 22.62％ C8 5.79％ 17.85％ 0.02％ 23.66％ C9 5.77％ 17.09％ 0.01％ 22.87％ total 26.19％ 73.75％ 0.06％ 0.00％ 100.00％

[0067] After deoxygenation, the reaction product is passed through an alkane-olefin separation simulated moving bed, which has 12 beds, an operating temperature of 80°C, a pressure of 0.5MPa, and a desorbent of 50% n-dodecene + 50% n-dodecane. The obtained olefin-rich component is cut by a distillation tower, the filling of the distillation tower is ball ring, the number of distillation tower plates is 45, and the absolute pressure of the distillation tower is controlled at 15kPa, the temperature of the tower bottom is controlled at 165°C, and the top temperature of the tower changes from 30 to 120°C during the distillation process. The hydrocarbon composition data of the final mixed α-olefin product is shown in Table 2.7, and the α-olefin purity of the mixed α-olefin product is 99.79%.

[0068] Table 2.7 Hydrocarbon composition of mixed α-olefin products

[0069] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C5 0.02％ 11.09％ 0.01％ 11.12％ C6 0.03％ 18.74％ 0.02％ 18.78％ C7 0.03％ 22.69％ 0.01％ 22.73％ C8 0.03％ 24.15％ 0.03％ 24.21％ C9 0.03％ 23.12％ 0.01％ 23.16％ total 0.13％ 99.79％ 0.08％ 0.00％ 100.00％

[0070] Example 3

[0071] The raw material of the embodiment is Fischer-Tropsch synthetic oil of a certain enterprise, and its raw material hydrocarbon composition is shown in Tables 3.1 and 3.2.

[0072] Table 3.1 Fischer-Tropsch synthetic oil raw materials

[0073] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C3 0.82％ 0.82％ C4 1.47％ 1.47％ C5 3.18％ 7.10％ 0.50％ 1.35％ 12.13％ C6 4.79％ 12.51％ 0.75％ 1.86％ 19.91％ C7 5.27％ 15.15％ 0.78％ 21.20％ C8 5.28％ 16.43％ 0.87％ 22.58％ C9 5.20％ 15.72％ 0.97％ 21.89％ total 23.72％ 66.91％ 3.87％ 5.50％ 100.00％

[0074] Table 3.2 Distillation range of Fischer-Tropsch synthetic oil raw materials

[0075] Distillation range, ℃ Initial distillation point / ℃ 30 5% recovery temperature / ℃ 42 10% recovery temperature / ℃ 55 30% recovery temperature / ℃ 81 50% recovery temperature / ℃ 96 70% recovery temperature / ℃ 119 90% recovery temperature / ℃ 130 95% recovery temperature / ℃ 143 Final distillation point / ℃ 154

[0076] The Fischer-Tropsch synthetic oil enters the etherification reaction tower, which is loaded with commercially available etherification catalyst C. The reaction temperature is 154°C, the reaction pressure is 1.2 MPa, and the reaction volume space velocity is 1.5 h -1 The physical properties of etherification catalyst C are shown in Table 3.3.

[0077] Table 3.3 Physical properties of etherification catalyst C

[0078] Etherification Catalyst C Morphology Butterfly Quality composition 99% macroporous resin + 1% diatomaceous earth <![CDATA[Specific surface area, m 2 / g]]> 610 Bulk ratio, g / mL 0.45

[0079] The hydrocarbon composition data of the product obtained by the Fischer-Tropsch synthetic oil after the etherification reaction tower are shown in Table 3.4.

[0080] Table 3.4 Hydrocarbon composition of reaction products after etherification

[0081] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C3 0.11％ 0.11％ C4 0.32％ 0.32％ C5 3.21％ 7.21％ 0.02％ 0.33％ 10.77％ C6 4.89％ 12.30％ 0.01％ 0.30％ 17.50％ C7 5.21％ 15.46％ 0.02％ 0.14％ 20.83％ C8 5.43％ 16.14％ 0.01％ 0.78％ 22.36％ C9 5.12％ 15.68％ 0.01％ 0.66％ 21.47％ C10 1.22％ 1.22％ C11 1.15％ 1.15％ C12 1.49％ 1.49％ C13 1.13％ 1.13％ C14 0.78％ 0.78％ C15 0.87％ 0.87％ total 23.86％ 66.79％ 0.07％ 9.28％ 100.00％

[0082] The reaction product after etherification was deeply deoxygenated in a deoxygenation tower. The adsorption temperature was 60°C, the adsorption pressure was 0.7 MPa, and the adsorption volume space velocity was 0.9 h -1The height-to-diameter ratio of the adsorption tower is 7. The physical properties of adsorbent TY-1 are shown in Table 3.5. After passing through the deoxygenation adsorption tower, the oxide content of the Fischer-Tropsch synthesis light distillate oil is reduced to less than 0.1ug / g. Its hydrocarbon composition data are shown in Table 3.6.

[0083] Table 3.5 Physical properties of adsorbent TY-1

[0084] Adsorbent TY-1 Morphology 2~3mm clover type Quality composition 98% USY molecular sieve + 2% alumina <![CDATA[Specific surface area, m 2 / g]]> 590 Bulk ratio, g / mL 0.68

[0085] Table 3.6 Hydrocarbon composition of reaction products after deoxygenation

[0086]

[0087]

[0088] After deoxygenation, the reaction product is passed through an alkane-olefin separation simulated moving bed, which has 12 beds, an operating temperature of 80°C, a pressure of 0.5MPa, and a desorbent of 50% n-dodecene + 50% n-dodecane. The obtained olefin-rich component is cut by a distillation tower, the filling of the distillation tower is ball ring, the number of distillation tower plates is 45, and the absolute pressure of the distillation tower is controlled at 11kPa, the temperature of the tower bottom is controlled at 148°C, and the top temperature of the tower changes from 30 to 120°C during the distillation process. The hydrocarbon composition data of the final mixed α-olefin product is shown in Table 3.7, and the α-olefin purity of the mixed α-olefin product is 99.76%.

[0089] Table 3.7 Hydrocarbon composition of mixed α-olefin products

[0090] Carbon number Alkanes α-Olefins Isoolefins Oxide Subtotal C5 0.02％ 10.78％ 0.03％ 10.82％ C6 0.03％ 18.38％ 0.01％ 18.43％ C7 0.03％ 23.06％ 0.03％ 23.12％ C8 0.03％ 24.12％ 0.01％ 24.17％ C9 0.03％ 23.42％ 0.01％ 23.46％ total 0.13％ 99.76％ 0.10％ 0.00％ 100.00％

[0091] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for separating ultra-high purity α-olefins from Fischer-Tropsch light oil, characterized in that: The following steps are involved: The Fischer-Tropsch synthetic light oil raw material is passed into an etherification reaction tower (1) equipped with an etherification catalyst, and mixed alcohol and mixed isomeric olefins in the Fischer-Tropsch synthetic oil in the tower react to generate ethers; the product of the etherification reaction tower (1) is passed into a deoxygenation tower (2) to remove oxygen-containing compounds in the oil product; the product of the deoxygenation tower (2) is passed into an alkane-olefin separation simulated moving bed (3) to separate olefins from alkanes to obtain an olefin-poor component and an olefin-rich component; The olefin-rich component is introduced into an olefin-rich component distillation tower (4) to separate the olefin from the desorbent, thereby obtaining an olefin-rich product with a mixed α-olefin purity greater than 99.5%.

2. The method for separating ultra-high purity α-olefins from Fischer-Tropsch light oil according to claim 1, characterized in that: The distillation range of the Fischer-Tropsch synthesis light oil raw material is 30°C to 160°C.

3. The method for separating ultra-high purity α-olefins from Fischer-Tropsch light oil according to claim 1, characterized in that: Mixed alcohols are all alcohols from C2 to C6.

4. The method for separating ultra-high purity α-olefins from Fischer-Tropsch light oil according to claim 1, characterized in that: The etherification catalyst in the etherification reaction tower (1) is composed of a main agent and a binder. The mass content of the main agent is greater than 95%. The main agent is a mixture of one or more of ZSM-5 zeolite, Y zeolite and macroporous resin; the binder is a mixture of one or more of bentonite, attapulgite and diatomaceous earth.

5. The method for separating ultra-high purity α-olefins from Fischer-Tropsch synthesis light oil according to claim 1, characterized in that: The reaction temperature of the etherification reaction tower (1) is 50-200°C, the reaction pressure is 0.1-2.0 MPa, and the reaction volume space velocity is 0.05-2h -1 .

6. The method for separating ultra-high purity α-olefins from Fischer-Tropsch synthesis light oil according to claim 1, characterized in that: The mass content of active components of the adsorbent in the deoxidation tower (2) is greater than 90%, and the active component is USY molecular sieve.

7. The method for separating ultra-high purity α-olefins from Fischer-Tropsch synthesis light oil according to claim 1, characterized in that: The adsorption temperature of the deoxygenation tower (2) is 30-80°C, the height-to-diameter ratio of the adsorption tower is 3-9, and the adsorption volume space velocity is 0.3-2h -1 , adsorption pressure 0.3~1.0MPa.

8. The method for separating ultra-high purity α-olefins from Fischer-Tropsch synthesis light oil according to claim 1, characterized in that: The simulated moving bed for separation of alkane and olefin (3) adopts a simulated moving bed with 12 to 24 layers, an operating temperature of 60 to 80°C, and a pressure of 0.2 to 0.8 MPa; the desorbent is a mixture of n-dodecene and n-dodecane, wherein the n-dodecene accounts for 20% to 60% of the mass fraction of the desorbent.

9. The method for separating ultra-high purity α-olefins from Fischer-Tropsch synthesis light oil according to claim 1, characterized in that: The filler of the olefin-rich component distillation tower (4) is selected from ball rings and Raschig rings, the number of plates of the distillation tower is 40-50, the absolute pressure of the distillation tower is 5-20 kPa, and the temperature of the tower bottom is 130-180°C.

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