Continuous method for preparing 4-methyl-1-pentene through propylene dimerization and obtained 4-methyl-1-pentene

Abstract

The invention discloses a continuous method for preparing 4-methyl-1-pentene through propylene dimerization and the obtained 4-methyl-1-pentene. The continuous method for preparing the 4-methyl-1-pentene through propylene dimerization comprises the steps that components containing propylene and a catalyst react in a reactor in the presence of a solvent, the product obtained after the reaction is separated, and then the 4-methyl-1-pentene is obtained, and the reactor comprises a first solid-liquid reaction kettle and a second solid-liquid reaction kettle. According to the invention, the continuous propylene dimerization reaction is realized, the blank of the domestic production technology for preparing 4-methyl-1-pentene by propylene dimerization is hopefully filled, sufficient raw materials are provided for the production of PMP, the current situation that the PMP completely depends on import in China is broken through, and the method has great significance.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of 4-methyl-1-pentene, and in particular to a continuous method for preparing 4-methyl-1-pentene by propylene dimerization and the obtained 4-methyl-1-pentene. Background Art

[0002] At present, my country's 4M1P (4-methyl-1-pentene) products are in the initial stage of the market, with great development potential, large demand for 4M1P, and broad market prospects. However, the current domestic production capacity is obviously insufficient, and 4M1P downstream products are abundant, and the market is still expanding. Although traditional solid base catalysts have been industrialized abroad and highly selective dimerization of propylene has been achieved under laboratory conditions in China, the key technology for large-scale production of 4M1P is still lacking. Therefore, domestic scholars need to design reasonable industrial processes and equipment to ensure the stable performance of the catalyst and achieve highly selective dimerization of propylene, in order to break the foreign technology monopoly. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a continuous method for preparing 4-methyl-1-pentene by propylene dimerization and the obtained 4-methyl-1-pentene. The present invention aims to utilize China's abundant olefin resources to synthesize branched α-olefins through propylene dimerization technology, which can not only be used as comonomers of linear low-density polyethylene, but also can be self-polymerized to prepare new thermoplastic resin PMP. The present invention is conducive to increasing the technical accumulation in the direction of olefin oligomerization and achieving a breakthrough in functional monomer technology. At the same time, the present invention realizes the continuous propylene dimerization reaction, which is expected to fill the gap in the domestic production technology of propylene dimerization to prepare 4-methyl-1-pentene, and provide sufficient raw materials for the production of PMP, which will break the current situation of China's PMP completely relying on imports, and is of great significance.

[0004] One of the purposes of the present invention is to provide a continuous method for preparing 4-methyl-1-pentene by propylene dimerization, comprising the steps of reacting components including propylene and a catalyst in a reactor in the presence of a solvent, and separating the reaction product to obtain 4-methyl-1-pentene, wherein the reactor comprises a first solid-liquid reactor and a second solid-liquid reactor.

[0005] In a preferred embodiment of the present invention,

[0006] The method comprises:

[0007] (1) feeding components including propylene and solvent into a reactor containing a catalyst to react;

[0008] (2) The product after the reaction in step (1) enters a separation unit to remove the light and heavy residues and separate to obtain 4-methyl-1-pentene.

[0009] In a preferred embodiment of the present invention,

[0010] The first solid-liquid reactor and the second solid-liquid reactor are connected in series.

[0011] In a preferred embodiment of the present invention,

[0012] The operating conditions of the first solid-liquid reactor include: an operating temperature of 100-180°C, preferably 140-170°C; and / or a reaction pressure of 4.5-8MPaG; and / or a material residence time of 1-3h; and / or a space velocity of 0.3-1h -1 and / or,

[0013] The operating temperature of the second solid-liquid reactor is higher than that of the first solid-liquid reactor. Preferably, the operating temperature of the second solid-liquid reactor is 5-30°C higher than that of the first solid-liquid reactor, preferably 5-15°C higher. Further preferably, the operating conditions of the second solid-liquid reactor include: an operating temperature of 105-200°C, preferably 150-180°C; and / or a reaction pressure of 4.5-8MPaG; and / or a material residence time of 3-9h; and / or a space velocity of 0.1-0.4h -1 .

[0014] The present invention unexpectedly found that low reaction temperature is beneficial to the selectivity of 4-methyl-1-pentene, and high temperature is beneficial to the conversion rate of raw material propylene. Therefore, the present invention specially sets up a first solid-liquid reactor and a second solid-liquid reactor, and the first solid-liquid reactor realizes the reaction through the induction period at a slightly lower operating temperature, at which time the propylene conversion rate is low, but the high selectivity of 4-methyl-1-pentene is guaranteed, and then the second solid-liquid reactor increases the operating temperature to realize a greater degree of conversion of raw material propylene. If the operating temperature of the second solid-liquid reactor is the same as or lower than the operating temperature of the first solid-liquid reactor, the selectivity of the 4-methyl-1-pentene product and the conversion rate of raw material propylene will be reduced.

[0015] In a preferred embodiment of the present invention,

[0016] The first solid-liquid reactor and / or the second solid-liquid reactor can be a conventional solid-liquid reactor in the prior art, as long as the catalyst can be effectively trapped (the solid-liquid reactor in Chinese Patent No. 202310876009.8 is preferred in the present invention, which is incorporated herein in its entirety).

[0017] The first solid-liquid reactor and the second solid-liquid reactor have the same or different structures, and each independently comprises a reactor body, a feed inlet is provided on the top of the reactor body, and a discharge port is provided on the side wall of the reactor body.

[0018] A further improvement of the present invention is:

[0019] The discharge port extends outwardly and upwardly from the side wall of the kettle body, and the angle between the discharge port and the horizontal direction is 5°-75°;

[0020] Preferably, the angle between the discharge port and the horizontal direction is 15°-60°;

[0021] The horizontal direction refers to the direction of the plane perpendicular to the longitudinal section of the kettle body.

[0022] A filter element is arranged inside the discharge port, and the end of the filter element is flush with the side wall of the kettle body. Preferably, the filter element is a Johnson mesh, a metal wire mesh or a metal sintered element; and / or,

[0023] The discharge port is provided with a single or multiple backwash ports; and / or,

[0024] The kettle body is provided with an agitator; and / or, a baffle is fixedly installed inside the kettle body, preferably, the baffle is a vertical plate axially arranged along the inner wall of the kettle body, and a plurality of baffles are evenly arranged along the circumferential direction inside the kettle body; and / or,

[0025] The outer wall of the kettle body is provided with a jacket, an intermediate layer is formed between the jacket and the outer wall of the kettle body, a guide plate is provided in the intermediate layer, preferably, the guide plate is spirally wound in the intermediate layer, and / or, the jacket and the outer wall of the kettle body are connected to form an integral structure by welding, and a plurality of supports are provided on the jacket along the circumferential direction; and / or,

[0026] The processing volume ratio of the first solid-liquid reactor to the second solid-liquid reactor is 0.2-1, preferably 0.5-0.8. (The processing volume here refers to the volume of the reaction materials (including the raw materials involved in the reaction and the solvent that does not participate in the reaction) that can be processed by the first solid-liquid reactor and / or the second solid-liquid reactor)

[0027] In the present invention, the discharge port is arranged on the side wall of the reactor body and is inclined upward at an angle of 5°-75° with the horizontal direction, so as to avoid the problem that the solid phase material is discharged together with the liquid phase during the discharge stage after the reactor is operated for a short period of time or for a long period of time, and the solid phase material is blocked in the discharge port. The catalyst is suspended in the reactor and does not flow away with the product, which is more conducive to the separation of subsequent products.

[0028] In a preferred embodiment of the present invention,

[0029] The catalyst is synthesized in situ to avoid contact with air and oxygen, thereby extending the service life of the catalyst; preferably, the catalyst is a solid base catalyst, more preferably, (the solid base catalyst is the solid base catalyst in Chinese patent CN115722240A, which is introduced in its entirety herein), the preparation method of the solid base catalyst comprises: in an argon atmosphere, mixing metal K, M / K2CO3 and an inert solvent to obtain a supported KM / K2CO3 catalyst; wherein M / K2CO3 is K2CO3 modified with an auxiliary metal M; the auxiliary metal M is selected from at least one of Fe, Co, Ni, Zn and Ti.

[0030] In a preferred embodiment of the present invention,

[0031] The solvent is at least one of toluene, heptane, isopentane and dodecane, preferably dodecane; and / or,

[0032] The volume flow ratio of propylene to solvent is 1-8, preferably 1-4.

[0033] In the present invention, ASPEN simulation comparison is adopted, and 4-methyl-1-pentene main product and 4-methyl-1-pentene by-product are taken as examples. Toluene, heptane, isopentane and dodecane are used as solvents respectively. It is found that under the same operating pressure, the boiling points of the product 4M1P and the by-product C9 are greatly different from those of dodecane, and are easier to separate. At the same time, from the comprehensive consideration of solvent stability, safety and environmental protection, compared with toluene, heptane and isopentane, dodecane is used as a solvent to separate the heavy components of the product 4M1P / by-product C9 after propylene dimerization, and the effect is better.

[0034] In a preferred embodiment of the present invention,

[0035] In step (2), the separation unit comprises three-stage distillation towers, wherein the three-stage distillation towers are respectively a light component removal tower, a heavy component removal tower and a product separation tower; preferably,

[0036] At least one of the three-stage distillation towers is a packed tower. The packing in the packed tower can be conventional packing in the prior art, as long as the product 4-methyl-1-pentene can be effectively separated. In the present invention, at least one of structured packing and random packing is preferred, random packing is more preferred, metal random packing is further preferred, and metal wire mesh theta ring packing is further preferred.

[0037] In a preferred embodiment of the present invention,

[0038] In step (1), the reaction is preferably carried out in a nitrogen atmosphere; and / or the propylene and solvent are preferably deoxygenated and dehydrated before reacting.

[0039] In step (2), the light component raw material obtained by light removal in the separation unit is returned to the refining unit for recycling; and / or,

[0040] The solvent obtained by the separation unit is recycled and reused after drying and adsorption. Preferably, when the solvent is dodecane, 100% of the dodecane is recycled and reused.

[0041] In a preferred embodiment of the present invention,

[0042] The continuous method for preparing 4-methyl-1-pentene by propylene dimerization has a propylene per-pass conversion rate of 40-60%, a dimerization product selectivity of >75%, preferably >98%, and a 4-methyl-1-pentene selectivity of more than 70%, preferably more than 80%. Preferably, the accumulated C6 olefin product is subjected to continuous rectification and separation to obtain 4-methyl-1-pentene with a purity greater than 97.5%.

[0043] The present invention can adopt the following specific technical solutions:

[0044] The raw materials propylene, solvent and high-pressure nitrogen are deoxidized, dehydrated and dried before entering the solid-liquid reactor in series. The reaction is carried out in two jacketed solid-liquid reactors operated in series. The reaction heat is removed by the jacket circulating heat transfer oil. The reaction is stable, the temperature is evenly controlled and the process is simple. The product after the reaction enters the separation system to remove the light and heavy components to obtain the product 4-methyl-1-pentene. The light component raw material is returned to the refining unit for recycling; after the solvent is removed, dried and adsorbed, it is recycled as a solvent.

[0045] A second object of the present invention is to provide 4-methyl-1-pentene obtained by the method of one of the objects of the present invention.

[0046] The advantages of the present invention are as follows:

[0047] 1) Energy saving: a. The present invention adopts a jacketed kettle reactor, in which the process medium flows, and the jacket is circulated with closed-circuit heat transfer oil to remove heat, and the generated heat is cooled by a heat exchanger; b. The heat of the entire device is integrated and optimized by a heat transfer oil system.

[0048] 2) Reducing material consumption: In existing projects, in order to avoid the accumulation of propane impurities in the raw material propylene in the system, a continuous external discharge method is adopted, which wastes a large amount of propylene and also increases the propane concentration in the reaction system. The present invention adds a propylene recovery system, which returns the propylene to the raw material tank after separating the initial product, thereby reducing propylene consumption, improving reaction efficiency, and performing fixed discharge of impurity propane.

[0049] 3) Product quality: The continuous method for preparing 4-methyl-1-pentene by propylene dimerization of the present invention has a dimerization temperature of 100-200°C, preferably 140-170°C, a reaction pressure of 4.5-8MPaG, a propylene single-pass conversion of 40-60%, a dimerization product selectivity of >75%, preferably >98%, and a 4-methyl-1-pentene selectivity of more than 70%, preferably more than 80%. The accumulated C6 olefin products are continuously distilled and separated to obtain 4-methyl-1-pentene with a purity greater than 97.5%.

[0050] The present invention realizes the continuous production of 4-methyl-1-pentene prepared by propylene dimerization in a continuous solid-liquid reactor. On the one hand, it is helpful for the in-situ preparation of the catalyst, avoiding contact with air and oxygen, and prolonging the service life of the catalyst; on the other hand, it promotes the dispersion of propylene in the solvent, fully contacts with the catalyst, and improves the single-pass conversion rate of propylene. During the reaction process, the solvent can be recycled, which reduces solvent consumption, reduces investment, and minimizes the impact on daily production. Unreacted propylene can also be separated and recycled for reaction, which reduces the waste of raw materials and improves the conversion rate of raw materials. In addition, a catalyst replacement system is designed in the reaction process to ensure that the entire reaction process is carried out continuously. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a simplified process flow diagram of Examples 1-5 of the present invention, wherein: 1-fresh propylene feed logistics; 2-propylene buffer tank; 3-propylene buffer tank outlet logistics; 4-propylene feed pump; 5-propylene feed pump outlet logistics; 6-propylene feed heat exchanger; 7-propylene feed heat exchanger outlet logistics; 8-first solid-liquid reactor; 9-first solid-liquid reactor outlet logistics; 10-second solid-liquid reactor; 11-second solid-liquid reactor outlet logistics; 12-light component removal tower; 13-raw propylene recycling logistics; 14-solvent recycling logistics; 15-product light component removal logistics; 16-heavy component removal tower; 17-crude product logistics; 18-product separation tower; 19-4M1P product logistics; 20-solvent feed logistics; 21-solvent feed buffer tank outlet logistics; 22-solvent feed buffer tank. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with specific embodiments and drawings. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0053] The raw materials used in the present invention are all conventional commercially available raw materials.

[0054] In the present invention:

[0055] Propylene single-pass conversion rate = (propylene consumption / total feed amount) × 100%;

[0056] Dimerization product selectivity = (dimerization product amount / total amount of all products) × 100%;

[0057] 4-methyl-1-pentene selectivity = (4M1P product amount / total amount of all products) × 100%;

[0058] The purity of 4-methyl-1-pentene was calculated using the internal standard method, and the detection instrument was Agilent 7890A gas chromatograph.

[0059] The first solid-liquid reactor and the second solid-liquid reactor used in the embodiment of the present invention, the solid-liquid reactor comprises a kettle body, a feed port is provided at the top of the kettle body; a discharge port is provided at the middle and lower part of the side wall of the kettle body, the discharge port extends outwardly and upwardly from the side wall of the kettle body, and the angle with the horizontal direction is 45°, wherein the horizontal direction refers to the direction of the plane perpendicular to the longitudinal section of the kettle body, a filter element is provided inside the discharge port, and a single backwash port is provided on the discharge port; a sewage outlet is provided at the bottom of the kettle body; an agitator is provided in the kettle body, and a baffle is fixedly installed inside the kettle body, the baffle is a vertical plate axially arranged along the inner wall of the kettle body, and 6 baffles are evenly arranged circumferentially inside the kettle body, and the baffle is welded to the inner wall of the kettle body through a connecting plate; a jacket is provided on the outer wall of the kettle body, an intermediate layer is formed between the jacket and the outer wall of the kettle body, a guide plate is provided in the intermediate layer, and the guide plate is spirally wound in the intermediate layer, so that the heat medium enters from the jacket inlet and is discharged from the jacket outlet; an inspection port is provided on the kettle body.

[0060] The catalyst used in the embodiment of the present invention is a solid base catalyst prepared with reference to Example 1 of Chinese Patent CN115722240A, and its preparation process is as follows:

[0061] (1) Using ferric acetylacetonate as a precursor, chemical vapor deposition was used to deposit auxiliary metallic iron on the surface of K2CO3 at 300°C in an argon atmosphere, and then it was reduced in a H2 atmosphere to obtain Fe / K2CO3.

[0062] (2) Add molten triacontan (inert solvent) to a high-pressure reactor, then add Fe / K2CO3 and metal K to the solvent in sequence, then replace the gas in the reactor with argon, then slowly raise the temperature to 160°C, stir at a speed of 1500 r / min, and stir for 30 hours to obtain a supported K-Fe / K2CO3 catalyst. The amount of the metal K and Fe / K2CO3 is such that, based on the total amount of the supported KM / K2CO3 catalyst, the content of metal K on the supported K-Fe / K2CO3 catalyst is 4wt%, and the molar ratio of metal K to the auxiliary metal Fe is K:Fe=1:1.

[0063] Figure 1 FIG. 1 is a schematic diagram of a process flow of a continuous method for preparing 4-methyl-1-pentene by propylene dimerization in an embodiment of the present invention. Many conventional equipment, such as compressors and nitrogen pipelines, are omitted in the figure, but these equipment are well known to those skilled in the art. Figure 1 As shown, the process of the method of the present invention is described in detail as follows:

[0064] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene feed stream 1 is buffered by the propylene buffer tank 2 and preheated by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the solid base catalyst for the first polymerization reaction. The material obtained by the first polymerization reaction overflows in an overflow manner to obtain the first solid-liquid reactor outlet stream 9. The first solid-liquid reactor outlet stream 9 enters the second solid-liquid reactor 10 to contact with the solid base catalyst again for the second polymerization reaction. The product after the reaction passes through the filter provided inside the outlet of the second solid-liquid reactor 10. After filtration by the filter element, the second solid-liquid reactor outlet logistics 11 is obtained, and the second solid-liquid reactor outlet logistics 11 is sent to the light component removal tower 12 of the separation unit for the first stage light component separation. The raw material propylene recovery logistics 13 separated at the top of the light component removal tower 12 is recycled as a raw material, and the product light-removed logistics 15 after the first stage light component separation obtained in the bottom of the light component removal tower 12 enters the heavy component removal tower 16 for heavy component separation. The solvent recovery logistics 14 obtained by separation is recycled, and the crude product logistics 17 obtained in the bottom of the heavy component removal tower 16 enters the product separation tower 18 for product separation to obtain 4-methyl-1-pentene product logistics 19.

[0065] Embodiment 1:

[0066] use Figure 1 In the process flow shown, the initial flow rate of fresh propylene feed stream 1 is 320 kg / h. After the raw propylene recycling stream 13 separated at the top of the light component removal tower 12 enters the propylene buffer tank 2, the flow rate of the propylene buffer tank outlet stream 3 is maintained at 320 kg / h. The initial flow rate of the solvent (dodecane) feed stream 20 is 160 kg / h. After the solvent recycling stream 14 enters the solvent feed buffer tank 22, the flow rate of the solvent feed buffer tank outlet stream 21 is maintained at 160 kg / h.

[0067] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene stream 1 is sent to the propylene buffer tank 2 at room temperature and an operating pressure of 3MPaG. The buffered raw propylene is heated to 140°C by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the above-mentioned supported K-Fe / K2CO3 catalyst for the first polymerization reaction. The first solid-liquid reactor is loaded with 30kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under a nitrogen atmosphere, the first solid-liquid reactor has an operating temperature of 140°C, an operating pressure of 5MPaG, and an air velocity of 1h -1 The material after the first polymerization reaction in the first solid-liquid reactor is overflowed by overflowing the first solid-liquid reactor outlet flow 9 into the second solid-liquid reactor 10. The second solid-liquid reactor is loaded with 80 kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under nitrogen atmosphere, the second solid-liquid reactor is operated at a temperature of 150°C, an operating pressure of 5 MPaG, and a space velocity of 0.33 h -1 The volume ratio of the processing capacity of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.5. The product after the second polymerization reaction is filtered through a filter element arranged inside the discharge port to obtain the outlet logistics 11 of the second solid-liquid reactor and sent to a separation unit (including a three-stage separation distillation tower).

[0068] The outlet logistics 11 of the second solid-liquid reactor from the second solid-liquid reactor enters the light component removal tower 12 with an operating pressure of 0.55MPaG and an operating temperature of 180°C for the first stage of light component separation. The raw material propylene recycling logistics 13 separated from the top of the tower is recycled as a raw material. The product light-removing logistics 15 after the first stage of light component separation obtained in the tower bottom enters the heavy component removal tower 16. In the heavy component removal tower 16, the solvent recycling logistics 14 is separated under negative pressure conditions (50KPaA) and recycled. The crude product logistics 17 separated by the light and heavy component removal towers enters the product separation tower 18, and the product separation is carried out at an operating pressure of 0.2MPa(A) and an operating temperature of 65°C to obtain the 4M1P product logistics 19. (The above three-stage separation and distillation towers all use 6mm diameter metal wire mesh west tower ring high-efficiency fillers, and the tower height is 20m)

[0069] The accumulated C6 olefin products in Example 1 can achieve a propylene single-pass conversion rate of 45%, a dimerization product selectivity of 75%, and a 4-methyl-1-pentene selectivity of 70% after the above three-stage separation, and obtain a 4-methyl-1-pentene product with a purity of 97.5%.

[0070] Comparative Example 1:

[0071] use Figure 1In the process flow shown, the initial flow rate of fresh propylene feed stream 1 is 320 kg / h. After the raw propylene recycling stream 13 separated at the top of the light component removal tower 12 enters the propylene buffer tank 2, the flow rate of the propylene buffer tank outlet stream 3 is maintained at 320 kg / h. The initial flow rate of the solvent (dodecane) feed stream 20 is 160 kg / h. After the solvent recycling stream 14 enters the solvent feed buffer tank 22, the flow rate of the solvent feed buffer tank outlet stream 21 is maintained at 160 kg / h.

[0072] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene stream 1 is sent to the propylene buffer tank 2 at room temperature and an operating pressure of 3MPaG. The buffered raw propylene is heated to 140°C by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the above-mentioned supported K-Fe / K2CO3 catalyst to carry out the first polymerization reaction under a nitrogen atmosphere. The first solid-liquid reactor is loaded with 30kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under a nitrogen atmosphere, the operating temperature of the first solid-liquid reactor is 140°C, the operating pressure is 5MPaG, and the air velocity is 1h -1 The material after the first polymerization reaction in the first solid-liquid reactor is overflowed by overflowing the first solid-liquid reactor outlet flow 9 to enter the second solid-liquid reactor 10. The second solid-liquid reactor is loaded with 80 kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under nitrogen atmosphere, the second solid-liquid reactor is operated at a temperature of 130°C, an operating pressure of 5 MPaG, and a space velocity of 0.33 h -1 The volume ratio of the processing capacity of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.5. The product after the second polymerization reaction is filtered through a filter element arranged inside the discharge port to obtain the outlet logistics 11 of the second solid-liquid reactor and sent to a separation unit (including a three-stage separation distillation tower).

[0073] The outlet logistics 11 of the second solid-liquid reactor from the second solid-liquid reactor enters the light component removal tower 12 with an operating pressure of 0.55MPaG and an operating temperature of 180°C for the first stage of light component separation. The raw material propylene recycling logistics 13 separated from the top of the tower is recycled as a raw material. The product light-removing logistics 15 after the first stage of light component separation obtained in the tower bottom enters the heavy component removal tower 16. In the heavy component removal tower 16, the solvent recycling logistics 14 is separated under negative pressure conditions (50KPaA) and recycled. The crude product logistics 17 separated by the light and heavy component removal towers enters the product separation tower 18, and the product separation is carried out at an operating pressure of 0.2MPa(A) and an operating temperature of 65°C to obtain the 4M1P product logistics 19. (The above three-stage separation and distillation towers all use 6mm diameter metal wire mesh west tower ring high-efficiency fillers, and the tower height is 20m)

[0074] The accumulated C6 olefin products in Comparative Example 1 can achieve a propylene single-pass conversion rate of 42%, a dimerization product selectivity of 71%, and a 4-methyl-1-pentene selectivity of 63% after the above three-stage separation, and obtain a 4-methyl-1-pentene product with a purity of 97%.

[0075] Embodiment 2:

[0076] use Figure 1 In the process flow shown, the initial flow rate of fresh propylene feed stream 1 is 320 kg / h. After the raw propylene recycling stream 13 separated at the top of the light component removal tower 12 enters the propylene buffer tank 2, the flow rate of the propylene buffer tank outlet stream 3 is maintained at 320 kg / h. The initial flow rate of the solvent (dodecane) feed stream 20 is 192 kg / h. After the solvent recycling stream 14 enters the solvent feed buffer tank 22, the flow rate of the solvent feed buffer tank outlet stream 21 is maintained at 192 kg / h.

[0077] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene stream 1 is sent to the propylene buffer tank 2 at room temperature and an operating pressure of 3MPaG. The buffered raw propylene is heated to 150°C by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the above-mentioned supported K-Fe / K2CO3 catalyst for the first polymerization reaction. The first solid-liquid reactor is loaded with 30kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under a nitrogen atmosphere, the first solid-liquid reactor has an operating temperature of 150°C, an operating pressure of 5MPaG, and an air velocity of 0.5h -1 The material after the first polymerization reaction in the first solid-liquid reactor is overflowed by overflowing the first solid-liquid reactor outlet flow 9 to enter the second solid-liquid reactor 10. The second solid-liquid reactor is loaded with 80 kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under nitrogen atmosphere, the second solid-liquid reactor is operated at a temperature of 160°C, an operating pressure of 5 MPaG, and a space velocity of 0.17 h -1 The volume ratio of the processing capacity of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.6. The product after the second polymerization reaction is filtered through a filter element arranged inside the discharge port to obtain the outlet logistics 11 of the second solid-liquid reactor and sent to a separation unit (including a three-stage separation distillation tower).

[0078] The outlet logistics 11 of the second solid-liquid reactor from the second solid-liquid reactor enters the light component removal tower 12 with an operating pressure of 0.55MPaG and an operating temperature of 180°C for the first stage of light component separation. The raw material propylene recycling logistics 13 separated from the top of the tower is recycled as a raw material. The product light-removing logistics 15 after the first stage of light component separation obtained in the tower bottom enters the heavy component removal tower 16. In the heavy component removal tower 16, the solvent recycling logistics 14 is separated under negative pressure conditions (50KPaA) and recycled. The crude product logistics 17 separated by the light and heavy component removal towers enters the product separation tower 18, and the product separation is carried out at an operating pressure of 0.2MPa(A) and an operating temperature of 65°C to obtain the 4M1P product logistics 19. (The above three-stage separation and distillation towers all use 6mm diameter metal wire mesh west tower ring high-efficiency fillers, and the tower height is 20m)

[0079] The accumulated C6 olefin products in Example 2 can achieve a propylene single-pass conversion rate of 50%, a dimerization product selectivity of 80%, and a 4-methyl-1-pentene selectivity of 70% after the above three-stage separation, and obtain a 4-methyl-1-pentene product with a purity of 98%.

[0080] Embodiment 3:

[0081] use Figure 1 In the process flow shown, the initial flow rate of fresh propylene feed stream 1 is 320 kg / h. After the raw propylene recycling stream 13 separated at the top of the light component removal tower 12 enters the propylene buffer tank 2, the flow rate of the propylene buffer tank outlet stream 3 is maintained at 320 kg / h. The initial flow rate of the solvent (dodecane) feed stream 20 is 240 kg / h. After the solvent recycling stream 14 enters the solvent feed buffer tank 22, the flow rate of the solvent feed buffer tank outlet stream 21 is maintained at 240 kg / h.

[0082] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene stream 1 is sent to the propylene buffer tank 2 at room temperature and an operating pressure of 3MPaG. The buffered raw propylene is heated to 160°C by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the above-mentioned supported K-Fe / K2CO3 catalyst for the first polymerization reaction. The first solid-liquid reactor is loaded with 30kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under a nitrogen atmosphere, the first solid-liquid reactor has an operating temperature of 160°C, an operating pressure of 5MPaG, and an air velocity of 0.33h -1The material after the first polymerization reaction in the first solid-liquid reactor is overflowed by overflowing the first solid-liquid reactor outlet flow 9 to enter the second solid-liquid reactor 10. The second solid-liquid reactor is loaded with 80 kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under nitrogen atmosphere, the second solid-liquid reactor is operated at a temperature of 170°C, an operating pressure of 5 MPaG, and a space velocity of 0.11 h -1 The volume ratio of the processing capacity of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.7. The product after the second polymerization reaction is filtered through a filter element arranged inside the discharge port to obtain the outlet logistics 11 of the second solid-liquid reactor and sent to a separation unit (including a three-stage separation distillation tower).

[0083] The outlet logistics 11 of the second solid-liquid reactor from the second solid-liquid reactor enters the light component removal tower 12 with an operating pressure of 0.55MPaG and an operating temperature of 180°C for the first stage of light component separation. The raw material propylene recycling logistics 13 separated from the top of the tower is recycled as a raw material. The product light-removing logistics 15 after the first stage of light component separation obtained in the tower bottom enters the heavy component removal tower 16. In the heavy component removal tower 16, the solvent recycling logistics 14 is separated under negative pressure conditions (50KPaA) and recycled. The crude product logistics 17 separated by the light and heavy component removal towers enters the product separation tower 18, and the product separation is carried out at an operating pressure of 0.2MPa(A) and an operating temperature of 65°C to obtain the 4M1P product logistics 19. (The above three-stage separation and distillation towers all use 6mm diameter metal wire mesh west tower ring high-efficiency fillers, and the tower height is 20m)

[0084] The accumulated C6 olefin products in Example 3 can achieve a propylene single-pass conversion rate of 48%, a dimerization product selectivity of 98%, and a 4-methyl-1-pentene selectivity of 80% after the above three-stage separation, and a 4-methyl-1-pentene product with a purity of 98.5% can be obtained.

[0085] Embodiment 4:

[0086] use Figure 1 In the process flow shown, the initial flow rate of fresh propylene feed stream 1 is 320 kg / h. After the raw propylene recycling stream 13 separated at the top of the light component removal tower 12 enters the propylene buffer tank 2, the flow rate of the propylene buffer tank outlet stream 3 is maintained at 320 kg / h. The initial flow rate of the solvent (dodecane) feed stream 20 is 240 kg / h. After the solvent recycling stream 14 enters the solvent feed buffer tank 22, the flow rate of the solvent feed buffer tank outlet stream 21 is maintained at 240 kg / h.

[0087] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene stream 1 is sent to the propylene buffer tank 2 at room temperature and an operating pressure of 3MPaG. The buffered raw propylene is heated to 170°C by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the above-mentioned supported K-Fe / K2CO3 catalyst for the first polymerization reaction. The first solid-liquid reactor is loaded with 30kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under a nitrogen atmosphere, the first solid-liquid reactor has an operating temperature of 170°C, an operating pressure of 6.5MPaG, and an air velocity of 0.33h -1 The material after the first polymerization reaction in the first solid-liquid reactor is overflowed by overflowing the first solid-liquid reactor outlet flow 9 into the second solid-liquid reactor 10. The second solid-liquid reactor is loaded with 80 kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under nitrogen atmosphere, the second solid-liquid reactor is operated at a temperature of 180°C, an operating pressure of 6.5 MPaG, and a space velocity of 0.11 h -1 The volume ratio of the processing capacity of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.8. The product after the second polymerization reaction is filtered through a filter element arranged inside the discharge port to obtain the outlet logistics 11 of the second solid-liquid reactor and sent to a separation unit (including a three-stage separation distillation tower).

[0088] The outlet logistics 11 of the second solid-liquid reactor from the second solid-liquid reactor enters the light component removal tower 12 with an operating pressure of 0.55MPaG and an operating temperature of 180°C for the first stage of light component separation. The raw material propylene recycling logistics 13 separated from the top of the tower is recycled as a raw material. The product light-removing logistics 15 after the first stage of light component separation obtained in the tower bottom enters the heavy component removal tower 16. In the heavy component removal tower 16, the solvent recycling logistics 14 is separated under negative pressure conditions (50KPaA) and recycled. The crude product logistics 17 separated by the light and heavy component removal towers enters the product separation tower 18, and the product separation is carried out at an operating pressure of 0.2MPa(A) and an operating temperature of 65°C to obtain the 4M1P product logistics 19. (The above three-stage separation and distillation towers all use 6mm diameter metal wire mesh west tower ring high-efficiency fillers, and the tower height is 20m)

[0089] The accumulated C6 olefin products in Example 4 are separated by the above three stages and separated by a metal mesh theta ring high-efficiency packing separation process, which can achieve a propylene single-pass conversion rate of 42%, a dimerization product selectivity of 92%, and a 4-methyl-1-pentene selectivity of 75%, and a 4-methyl-1-pentene product with a purity of 98% can be obtained.

[0090] Embodiment 5:

[0091] use Figure 1In the process flow shown, the initial flow rate of fresh propylene feed stream 1 is 320 kg / h. After the raw propylene recycling stream 13 separated at the top of the light component removal tower 12 enters the propylene buffer tank 2, the flow rate of the propylene buffer tank outlet stream 3 is maintained at 320 kg / h. The initial flow rate of the solvent (dodecane) feed stream 20 is 240 kg / h. After the solvent recycling stream 14 enters the solvent feed buffer tank 22, the flow rate of the solvent feed buffer tank outlet stream 21 is maintained at 240 kg / h.

[0092] The solvent feed stream 20 is buffered by the solvent feed buffer tank 22 to obtain the solvent feed buffer tank outlet stream 21 which is sent to the first solid-liquid reactor 8. The fresh propylene stream 1 is sent to the propylene buffer tank 2 at room temperature and an operating pressure of 3MPaG. The buffered raw propylene is heated to 170°C by the propylene feed heat exchanger 6 and then sent to the first solid-liquid reactor 8 to contact with the above-mentioned supported K-Fe / K2CO3 catalyst for the first polymerization reaction. The first solid-liquid reactor is loaded with 30kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under a nitrogen atmosphere, the first solid-liquid reactor has an operating temperature of 170°C, an operating pressure of 6.5MPaG, and an air velocity of 0.33h -1 The material after the first polymerization reaction in the first solid-liquid reactor is overflowed by overflowing the first solid-liquid reactor outlet flow 9 into the second solid-liquid reactor 10. The second solid-liquid reactor is loaded with 80 kg of the above-mentioned supported K-Fe / K2CO3 catalyst. Under nitrogen atmosphere, the second solid-liquid reactor is operated at a temperature of 180°C, an operating pressure of 6.5 MPaG, and a space velocity of 0.11 h -1 The volume ratio of the processing capacity of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.8. The product after the second polymerization reaction is filtered through a filter element arranged inside the discharge port to obtain the outlet logistics 11 of the second solid-liquid reactor and sent to a separation unit (including a three-stage separation distillation tower).

[0093] The outlet logistics 11 of the second solid-liquid reactor from the second solid-liquid reactor enters the light component removal tower 12 with an operating pressure of 0.55MPaG and an operating temperature of 180°C for the first stage of light component separation. The raw material propylene recycling logistics 13 separated from the top of the tower is recycled as a raw material. The product light-removing logistics 15 after the first stage of light component separation obtained in the tower bottom enters the heavy component removal tower 16. In the heavy component removal tower 16, the solvent recycling logistics 14 is separated under negative pressure conditions (50KPaA) and recycled. The crude product logistics 17 separated by the light and heavy component removal towers enters the product separation tower 18, and the product separation is carried out at an operating pressure of 0.2MPa(A) and an operating temperature of 65°C to obtain the 4M1P product logistics 19. (The above three-stage separation and distillation towers all use structured packing (750Y high-efficiency packing), and the tower height is 30m)

[0094] The accumulated C6 olefin products in Example 5 are separated by the above three stages and the 750Y high-efficiency filler separation process, which can achieve a propylene single-pass conversion rate of 42%, a dimerization product selectivity of 92%, and a 4-methyl-1-pentene selectivity of 74%, and a 4-methyl-1-pentene product with a purity of 97.5% can be obtained.

[0095] It can be seen from Examples 1-5 of the present invention that the present invention adopts a solid-liquid reactor with a special outlet structure, so that after the dimerization reaction, the catalyst does not flow out with the reaction products, saving the subsequent steps and equipment for separating the catalyst.

[0096] It can be seen from Examples 4 and 5 of the present invention that, under the same process conditions, the three-stage separation distillation tower of the present invention has a better separation effect when using random packing (preferably metal wire mesh theta ring high-efficiency packing) than when using regular packing (preferably 750Y high-efficiency packing), because when obtaining a 4-methyl-1-pentene product with similar purity, the separation efficiency of using random packing is higher and the tower height is lower.

Claims

1. A continuous method for preparing 4-methyl-1-pentene by propylene dimerization, comprising the steps of reacting components including propylene and a catalyst in the presence of a solvent in a reactor, and separating the reaction product to obtain 4-methyl-1-pentene, wherein the reactor comprises a first solid-liquid reactor and a second solid-liquid reactor.

2. The method according to claim 1, characterized in that The method comprises: (1) feeding components including propylene and solvent into a reactor containing a catalyst to react; (2) The product after the reaction in step (1) enters a separation unit to remove light and heavy substances and obtain 4-methyl-1-pentene.

3. The method according to claim 1, characterized in that: The first solid-liquid reactor and the second solid-liquid reactor are connected in series.

4. The method according to claim 3, characterized in that: The operating conditions of the first solid-liquid reactor include: an operating temperature of 100-180°C, preferably 140-170°C; and / or a reaction pressure of 4.5-8 MPaG; and / or a space velocity of 0.3-1 h -1 and / or, The operating temperature of the second solid-liquid reactor is higher than that of the first solid-liquid reactor. Preferably, the operating temperature of the second solid-liquid reactor is 5-30°C higher than that of the first solid-liquid reactor. Further preferably, the operating conditions of the second solid-liquid reactor include: an operating temperature of 105-200°C, preferably 150-180°C; and / or a reaction pressure of 4.5-8MPaG; and / or a space velocity of 0.1-0.4h / min. -1 .

5. The method according to claim 1, characterized in that: The structures of the first solid-liquid reactor and the second solid-liquid reactor are the same or different, and they independently include a reactor body, a feed port is provided on the top of the reactor body, and a discharge port is provided on the side wall of the reactor body; preferably, the discharge port extends outwardly and upwardly from the side wall of the reactor body, and the angle between the discharge port and the horizontal direction is 5°-75°; more preferably, the angle between the discharge port and the horizontal direction is 15°-60°; wherein the horizontal direction refers to the direction of the plane perpendicular to the longitudinal section of the reactor body.

6. The method according to claim 5, characterized in that: A filter element is arranged inside the discharge port, and the end of the filter element is flush with the side wall of the kettle body. Preferably, the filter element is a Johnson mesh, a metal wire mesh or a metal sintered element; and / or, The discharge port is provided with a single or multiple backwash ports; and / or, The kettle body is provided with an agitator; and / or, a baffle is fixedly installed inside the kettle body, preferably, the baffle is a vertical plate axially arranged along the inner wall of the kettle body, and a plurality of baffles are evenly arranged along the circumferential direction inside the kettle body; and / or, The outer wall of the kettle body is provided with a jacket, an intermediate layer is formed between the jacket and the outer wall of the kettle body, a guide plate is provided in the intermediate layer, preferably, the guide plate is spirally wound in the intermediate layer, and / or, the jacket and the outer wall of the kettle body are connected to form an integral structure by welding, and a plurality of supports are provided on the jacket along the circumferential direction; and / or, The volume ratio of the processing volume of the first solid-liquid reactor to that of the second solid-liquid reactor is 0.2-1, preferably 0.5-0.

8.

7. The method according to claim 1, characterized in that: The catalyst is synthesized in situ. Preferably, the catalyst is a solid base catalyst. More preferably, the preparation method of the solid base catalyst comprises: mixing metal K, M / K2CO3 and an inert solvent in an argon atmosphere to obtain a supported KM / K2CO3 catalyst; wherein M / K2CO3 is K2CO3 modified with an auxiliary metal M; and the auxiliary metal M is selected from at least one of Fe, Co, Ni, Zn and Ti.

8. The method according to claim 1, characterized in that: The solvent is at least one of toluene, heptane, isopentane and dodecane, preferably dodecane; and / or, The volume flow ratio of propylene to solvent is 1-8, preferably 1-4.

9. The method according to claim 2, characterized in that: In step (2), the separation unit comprises three-stage distillation towers, wherein the three-stage distillation towers are respectively a light component removal tower, a heavy component removal tower and a product separation tower; preferably, At least one of the three-stage distillation towers is a packed tower, and the packing in the packed tower is at least one of a structured packing and a random packing, preferably a random packing, more preferably a metal random packing, and further preferably a metal wire mesh theta ring packing.

10. The method according to claim 2, characterized in that: In step (2), the light component raw material obtained by light removal in the separation unit is returned to the refining unit for recycling; and / or, The solvent obtained by the separation unit is recycled and reused after drying and adsorption. Preferably, when the solvent is dodecane, 100% of the dodecane is recycled and reused.

11. The method according to any one of claims 1 to 10, characterized in that: The continuous method for preparing 4-methyl-1-pentene by propylene dimerization has a propylene single-pass conversion rate of 40-60%; and / or, the dimerization product selectivity is >75%, preferably >98%; and / or, the 4-methyl-1-pentene selectivity is above 70%, preferably above 80%.

12. 4-Methyl-1-pentene obtained by the method according to any one of claims 1 to 11.

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