Method for continuously preparing alpha-olefin through oligomerization of alpha-olefin and ethylene and application

Abstract

The invention discloses a method for continuously preparing alpha-olefin through oligomerization of alpha-olefin and ethylene, and belongs to the technical field of ethylene oligomerization. The method for continuously preparing alpha-olefin through ethylene oligomerization comprises the following steps: mixing a main catalyst and a cocatalyst in a solvent to obtain a reaction medium; the method comprises the following steps: mixing a reaction medium with ethylene, feeding the mixture into a micro-channel reactor, reacting to obtain a product containing alpha-olefin, continuously feeding through a feeding tank and a feeding pump to realize continuous production, forcibly mixing the reaction medium with ethylene gas through a micro-mixer, and quickly reacting to obtain the alpha-olefin. The reaction medium and the ethylene gas further fully react in the micro-channel reactor and rapidly exchange heat, the temperature of the reaction system is stably controlled, online monitoring is carried out, and the proportion of 1-octene / 1-hexene in the alpha-olefin product is high.

Description

Technical Field

[0001] The invention relates to the technical field of ethylene oligomerization, and in particular to an alpha-olefin and a method and application of continuously preparing the alpha-olefin by ethylene oligomerization. Background Art

[0002] Linear α-olefins (LAOs) refer to monoolefins with a straight molecular chain and a double bond at one end. As an important type of organic chemical raw materials and chemical intermediates, they are widely used in polyethylene copolymerization, polyα-olefins (PAO), polyolefin elastomers (POE), polyolefin plastomers (POP), lubricants, surfactants and oil additives. In particular, 1-octene and 1-hexene, as the main raw materials for a series of high-performance and high-value-added polyolefin products such as high-performance linear low-density polyethylene (LLDPE), polyα-olefins, polyolefin elastomers, are one of the products with the greatest value-added potential and the most urgent need in China, and are also the hot spot of current research on the preparation of α-olefins by ethylene polymerization.

[0003] At present, the preparation methods of linear α-olefins mainly include alcohol dehydration, Fischer-Tropsch synthesis, cycloolefin isomerization, fatty alcohol dehydrogenation, paraffin cracking, ethylene oligomerization, etc. Among them, the ethylene selective oligomerization is to directly obtain 1-hexene and 1-octene through ethylene trimerization and tetramerization, which has the advantages of high atomic utilization, good economy, high product selectivity and purity, and is the current mainstream process route.

[0004] In recent years, with the successive implementation of domestic 1-hexene industrial plants, the price and demand of domestic 1-hexene have gradually fallen, but the price and market demand of 1-octene remain high. Currently, only Maoming Petrochemical has a 1-octene production capacity of only 8,000 tons / year, which mainly relies on imports. With the localization of POE and POP and the growth of the PAO market, the demand for 1-octene will be huge in the future. Therefore, improving the selectivity of preparing 1-octene with high selectivity from ethylene has important research value and practical significance.

[0005] Chinese patent application CN 107746365A discloses a process and system for selective ethylene polymerization to produce α-olefins. The invention connects a material circulation pipeline to the high-pressure reactor and sets a heat exchanger and a gas-liquid separator on the circulation pipeline to achieve selective polymerization of ethylene in the high-pressure reactor. Heat is exchanged on the external pipeline, and the reaction liquid containing the product flows out from the bottom of the reactor and enters the gas-liquid separator for gas-liquid separation after heat exchange in the heat exchanger. The gas is discharged from the top of the gas-liquid separator into the reflux gas mixing tank, and the liquid is returned to the high-pressure reactor. However, the external circulation heat exchange will cause a large change in the solution temperature, and it will also consume a large amount of solvent, which will increase the cost of later separation.

[0006] Chinese patent application CN 113511949A discloses a production process for the selective polymerization of ethylene to produce 1-hexene and 1-octene. The invention provides a production device and process for the selective polymerization of ethylene to produce 1-hexene and 1-octene. The equipment includes a feed metering and reaction system, a flash system, a distillation system and an ethylene compression system. The production of 1-hexene and 1-octene products and the long-term stable operation of the device according to the ethylene trimerization route and the ethylene tetramerization route are realized. However, the selectivity of 1-octene in the product is only 35%, and the main product is 1-hexene, accounting for 51%.

[0007] The selective polymerization of ethylene has the characteristics of rapid reaction and high heat release. It is difficult to control the temperature using traditional autoclave reactors, resulting in poor selectivity for 1-octene in the product. In addition, due to the long residence time and poor mass transfer effect of autoclave reactors, ethylene polymerization produces polymers that stick to the autoclave wall and agitator paddles, which is not conducive to continuous operation and production. Summary of the invention

[0008] In view of the above situation, the present invention provides a method for continuously preparing α-olefin by oligomerization of α-olefin and ethylene. By introducing a microchannel reactor as an oligomerization reactor, the selectivity of 1-octene in the ethylene selective oligomerization product is improved and the proportion of polymer in the product is reduced, so as to achieve the purpose of continuously and safely preparing 1-octene with high selectivity.

[0009] A microchannel reactor is a fluid flow channel of micro-machining manufacturing technology, which generally includes a feed unit, a mixer unit, a reactor unit, a heat exchanger unit and a controller unit. Compared with traditional reactors, the specific surface area of ​​a microchannel reactor has increased by dozens to hundreds of times, which greatly improves the heat and mass transfer capacity per unit area, shortens the reaction residence time, and greatly improves the safety performance of operation.

[0010] In order to solve the above technical problems, the first aspect of the present invention provides a method for continuously preparing α-olefins by ethylene polymerization, comprising the following steps:

[0011] S1, mixing the catalyst and the co-catalyst in a solvent to obtain a reaction medium;

[0012] S2, after mixing the reaction medium with ethylene, sending it into a microchannel reactor to react to obtain a product containing α-olefins.

[0013] The microchannel reactor of the present invention has strong heat and mass transfer capabilities, and the ethylene high-selectivity polymerization reaction has the characteristics of fast ethylene consumption rate, fast catalytic activity start-up, high activity and fast activity deactivation. Ethylene and reaction medium react in the microchannel reactor to prepare a mixed solution containing alpha-olefin products.

[0014] According to some embodiments of the present invention, the mass ratio of the solvent, the main catalyst and the co-catalyst in the reaction medium is (5000-200000):1:(200-1000), for example, 50000:1:900, 100000:1:900, 150000:1:900, 200000:1:900.

[0015] According to some embodiments of the present invention, the solvent is selected from at least one of toluene, 1-hexene, 1-octene, n-heptane, cyclohexane, and methylcyclohexane, preferably cyclohexane.

[0016] The selection of the above solvents can reduce the energy consumption of later separation and ensure production safety.

[0017] According to some embodiments of the present invention, the co-catalyst is at least one of methylaluminoxane, modified methylaluminoxane, triisobutylaluminum, tri-n-butylaluminum, triethylaluminum, and tripropylaluminum, preferably modified methylaluminoxane.

[0018] According to some embodiments of the present invention, the main catalyst is selected from at least one of a Cr-based catalyst, a Ni-based catalyst, and a Fe-based catalyst, preferably a Cr-based catalyst.

[0019] According to some embodiments of the present invention, the reaction medium includes a preheating treatment I before mixing with ethylene; preferably, the preheating treatment I is carried out in a liquid phase preheater, the temperature of the liquid phase preheater is 30°C to 60°C, and the volume flow rate of the reaction medium is 1mL / min to 30mL / min, for example 5mL / min.

[0020] According to some embodiments of the present invention, the ethylene includes a preheating treatment II before mixing with the reaction medium; preferably, the preheating treatment II is carried out in a gas phase preheater, the temperature of the gas phase preheater is 30°C to 60°C, and the volume flow rate of ethylene is 50mL / min to 1000mL / min, for example 500mL / min, 800mL / min, 1000mL / min.

[0021] According to some embodiments of the present invention, the reaction conditions include: temperature 30°C to 80°C, preferably 40°C to 60°C, for example 50°C; pressure 1.0MPa to 6.0MPa, preferably 3.0MPa to 5.0MPa, for example 3.0MPa, 4.0MPa, 5.0MPa; reaction time 1min to 60min, preferably 5min to 40min, more preferably 10min to 30min, for example 30min.

[0022] On the one hand, the limitation of reaction conditions can ensure that the reaction product has a ratio of 1-octene / 1-hexene>1 while ensuring a relatively fast reaction rate and a relatively low polymer content in the reaction liquid, thereby improving catalyst efficiency; on the other hand, the reaction exothermic rate can be controlled as much as possible under high catalyst activity, thereby increasing the ratio of 1-octene / 1-hexene. Finally, by controlling the limitation of reaction time (residence time of the reaction medium in the microchannel reactor), the catalytic activity of the catalyst can be improved as much as possible.

[0023] According to some embodiments of the present invention, a reaction channel is provided in the microchannel reactor; preferably, the length of the reaction channel is 10m to 100m, preferably 10m to 40m, for example 10m, 20m, 30m; the inner diameter of the reaction channel is 1mm to 6mm, preferably 2mm to 5mm, for example 2mm, 4mm; further preferably, the cross-section of the reaction channel is circular.

[0024] In the present invention, the reaction channel is a combination of a curved pipe and a straight pipe, or a combination of curved pipes and curved pipes, and the angle between the inlet direction and the outlet direction of the reaction material in the curved pipe part is 60 to 180°, preferably 90 to 180°.

[0025] According to some embodiments of the present invention, the reaction further includes gas-liquid separation; preferably, the conditions for the gas-liquid separation include: a pressure of 2.0 MPa to 6.0 MPa, preferably 4.0 MPa; further gas-liquid separation is carried out in a gas-liquid separation tank, and condensation is performed to obtain a reaction mixture containing α-olefins, wherein the reaction mixture contains unreacted ethylene, reaction products and reaction medium; further, the reaction mixture is filtered and then distilled, and the solvent is recovered and reused to obtain the target product.

[0026] In the present invention, the ethylene oligomer solution produced by the microchannel reactor is passed through a gas-liquid separation unit for degassing; the obtained raw gas is purified and then recycled.

[0027] According to some embodiments of the present invention, the volume flow ratio of ethylene to the reaction medium is (10-200):1, for example, 100:1, 160:1, 200:1.

[0028] The second aspect of the present invention provides an α-olefin prepared by the above method.

[0029] According to some embodiments of the present invention, the proportion of 1-octene and 1-hexene in the α-olefins exceeds 85%.

[0030] According to some embodiments of the present invention, the ratio of 1-octene / 1-hexene in the α-olefin is 1-8, preferably 2-5.

[0031] The third aspect of the present invention provides an application of α-olefin prepared by the above method in the preparation of polyethylene, poly-α-olefin and polyolefin elastomer.

[0032] The third aspect of the present invention provides a use of α-olefin prepared by the above method in the preparation of lubricating oil or surfactant.

[0033] Beneficial effects:

[0034] The method for continuously preparing α-olefins by ethylene oligomerization of the present invention has a selectivity of 1-octene and 1-hexene in the prepared α-olefins of 80% to 90%;

[0035] The method for continuously preparing alpha-olefins by ethylene polymerization of the present invention can realize continuous production by continuously feeding through a feed tank and a feed pump, can achieve forced mixing and rapid reaction of a reaction medium and ethylene gas through a micro mixer, can realize further sufficient reaction and rapid heat exchange of the reaction medium and ethylene gas in a microchannel reactor, can stably control the temperature of the reaction system and can be monitored online, and can achieve a high ratio of 1-octene / 1-hexene in the alpha-olefin product;

[0036] In the method for continuously preparing alpha-olefins by ethylene polymerization of the present invention, the gas-liquid mixture after the reaction is separated from the reaction product and the raw material gas (ethylene) in the gas-liquid separation tank, the raw material gas (ethylene) is recycled after purification, and the reaction product is collected from the bottom of the gas-liquid separation tank. The high gas flow rate of ethylene not only shortens the residence time of the catalyst, but also reduces the generation of polymers in the process of ethylene polymerization, avoids pipeline blockage, and realizes continuous operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the microchannel reactor in the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0039] In the present invention, the volume flow rates of the reaction medium and ethylene are kept stable during operation, and frequent adjustment of flow setting parameters is avoided, thereby maintaining the gas-liquid mixing effect and the reaction system in a stable state.

[0040] In the present invention, various adjustable parameters of the microchannel reactor can be individually set as needed, such as the temperature, pressure, total residence time of the reaction material, the length, inner diameter and volume flow rate of the reaction channel, etc., so that different conditions can be regulated.

[0041] The cyclohexane in the examples was obtained from the ethylene glycol workshop of Sinopec Maoming Company with a purity of 99.5%.

[0042] The modified methylaluminoxane in the examples was purchased from Nouryon, model MMAO-3A.

[0043] There is no special requirement for the pump used in the present invention, and any common commercially available horizontal flow pump can be used.

[0044] The liquid phase preheater in the present invention is a traditional shell and tube heat exchanger, and the heating circulation integrated machine used is: JULABO company, model: JULABO F25-HL universal heating and cooling circulation bath.

[0045] The gas phase preheater in the present invention is a conventional shell and tube heat exchanger, and the heating circulation integrated machine used is from JULABO, model: JULABO F25-HL universal heating and cooling circulation bath.

[0046] The micro mixer in the present invention is a P-type micro mixing reactor using the Venturi structure principle. When the liquid contacts a large amount of gas, the liquid can be atomized instantly to achieve a fully mixed and enhanced mass transfer effect.

[0047] The microchannel reactor in the present invention is a coil made of 316L material, and the circulation integrated machine used is: Huber heating and cooling bath circulator model: CC-K15; the reaction channel is a serially connected tubular reaction channel, and the inner diameter of the tubular reaction channel is 2-5 mm; the length of a single tubular reaction channel is 6-30 m, and the tubular reaction channel is continuously annularly bent, and the angle between the inlet direction and the outlet direction of the bent part of the reaction material is 60-180°.

[0048] The gas-liquid separator in the present invention is a stainless steel tank with a top and an internal condensing coil. The design pressure of the stainless steel tank is 6MPa, the volume is 4L, the material is 316L, and a discharge port is provided at the bottom for collecting liquid products. The circulating integrated machine used is an externally purchased product: DHJF-2005 low-temperature constant temperature reaction tank, manufacturer: Zhengzhou Great Wall Science and Technology Industry and Trade Co., Ltd.

[0049] Example 1

[0050] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0051] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture obtained is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 74%, a 1-hexene selectivity of 16%, and a C10+ heavy component selectivity of 10%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0052] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst, the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900; wherein, the preparation process of the Cr-based catalyst is: take 10 mL of tert-butylamine and dissolve it in 50 mL of acetonitrile, stir evenly, then add 29 mL of triethylamine, continue stirring for 30 minutes, and obtain a mixed solution; under ice bath conditions, cool the mixed solution system to 0°C, then drop 38.5 mL of diphenylphosphine chloride, After reacting for 30 minutes, remove the ice bath and stir at room temperature (25°C) for 12 hours; finally, the stirred mixed liquid system is vacuum dried and washed with n-hexane to obtain a white solid, which is the ligand; accurately weigh 1g of the ligand and 0.8242g of CrCl3(THF)3, dissolve in 100mL of toluene, stir at 80°C for 12 hours, then cool to room temperature (25°C), filter and wash with n-hexane, and then vacuum dry the filter cake for 5 hours to obtain a blue solid, which is the Cr-based catalyst.

[0053] Example 2

[0054] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0055] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture obtained is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 62%, a 1-hexene selectivity of 25%, and a C10+ heavy component selectivity of 13%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0056] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 150000:1:900.

[0057] Example 3

[0058] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0059] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the obtained solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 57%, a 1-hexene selectivity of 28%, and a C10+ heavy component selectivity of 15%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0060] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 200000:1:900.

[0061] Example 4

[0062] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0063] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture obtained is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 61%, a 1-hexene selectivity of 25%, and a C10+ heavy component selectivity of 14%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0064] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 50000:1:900.

[0065] Example 5

[0066] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0067] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50° C. and a pressure of 4 MPa for 30 minutes; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0 MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 54%, a 1-hexene selectivity of 30%, and a C10+ heavy component selectivity of 16%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0068] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 10 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0069] Example 6

[0070] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0071] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture obtained is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 72%, a 1-hexene selectivity of 15%, and a C10+ heavy component selectivity of 13%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0072] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 30 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0073] Example 7

[0074] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0075] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 500mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the obtained solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 56%, a 1-hexene selectivity of 30%, and a C10+ heavy component selectivity of 14%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0076] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0077] Example 8

[0078] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0079] Reference Figure 1According to the process flow chart shown in the figure, the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 1000mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the obtained solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 70%, a 1-hexene selectivity of 17%, and a C10+ heavy component selectivity of 13%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0080] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0081] Example 9

[0082] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0083] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 3MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 61%, a 1-hexene selectivity of 26%, and a C10+ heavy component selectivity of 13%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0084] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0085] Example 10

[0086] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0087] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 5MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 71%, a 1-hexene selectivity of 15%, and a C10+ heavy component selectivity of 14%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0088] In this embodiment, the inner diameter of the channel in the microchannel reactor is 4 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0089] Embodiment 11

[0090] This embodiment provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0091] Reference Figure 1The process flow chart shown in the figure is as follows: the main catalyst is stirred in cyclohexane for 30 minutes to dissolve and disperse in advance, and then the co-catalyst is added and stirred for 10 minutes, and the mixture is fully mixed and activated to obtain a reaction medium; then the reaction medium is introduced into a liquid preheater through a pump, and the temperature of the liquid preheater is controlled to be 60°C, and the volume flow rate of the reaction medium is controlled to be 5mL / min; ethylene is introduced into a gas preheater, and the volume flow rate of ethylene is controlled to be 800mL / min through a flow meter, and the temperature of the gas preheater is controlled to be 60°C; the preheated ethylene and the preheated reaction medium are fully mixed in a gas-liquid micromixer to form a gas The gas-liquid mixture is sent into a microchannel reactor, and reacted at a temperature of 50°C and a pressure of 4MPa for 30min; the product after the reaction is sent into a gas-liquid separator, wherein the pressure of the gas-liquid separation is 4.0MPa, the gas phase obtained after separation is purified and recycled, and the solid-liquid mixture is filtered through a filter membrane to obtain a liquid product containing α-olefins; the liquid product containing α-olefins has a 1-octene selectivity of 65%, a 1-hexene selectivity of 23%, and a C10+ heavy component selectivity of 12%, and no wall-adhering polymer is generated in the microchannel reactor during the reaction.

[0092] In this embodiment, the inner diameter of the channel in the microchannel reactor is 2 mm and the length is 20 m. The solvent is cyclohexane, the main catalyst is a Cr-based catalyst (the preparation process is the same as in Example 1), the co-catalyst is modified methylaluminoxane, and the mass ratio of the solvent, the main catalyst, and the co-catalyst is 100000:1:900.

[0093] Comparative Example 1

[0094] This comparative example provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0095] The difference between Comparative Example 1 and Example 1 is that a 5L high-pressure reactor is used instead of a microchannel reactor to carry out the ethylene polymerization reaction, the reaction time is 60 min, and the other processes are exactly the same.

[0096] The obtained liquid phase product containing α-olefins has a 1-octene selectivity of 53%, a 1-hexene selectivity of 31%, and a C10+ heavy component selectivity of 16%. After long-term operation, polymers adhere to the stirring blades and the inner wall of the reactor.

[0097] Comparative Example 2

[0098] This comparative example provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0099] The difference between Comparative Example 2 and Example 1 is that the reaction temperature is 90° C., and the rest of the processes are exactly the same.

[0100] The obtained liquid phase product containing α-olefins had a 1-octene selectivity of 29%, a 1-hexene selectivity of 55%, and a C10+ heavy component selectivity of 16%. During the reaction, the pressure difference between the front and rear increased and blockage occurred.

[0101] Comparative Example 3

[0102] This comparative example provides a method for continuously preparing α-olefins by polymerization of ethylene.

[0103] The difference between Comparative Example 2 and Example 1 is that the reaction pressure is 1.5 MPa, and the rest of the processes are exactly the same.

[0104] The obtained liquid phase product containing α-olefins has a 1-octene selectivity of 32%, a 1-hexene selectivity of 56%, and a C10+ heavy component selectivity of 12%.

[0105] In order to further illustrate the progress of the present invention, the reaction condition parameters of the method for continuously preparing α-olefins by ethylene polymerization in Examples 1-11 and Comparative Examples 1-3 are summarized in Table 1 below;

[0106] At the same time, the selectivity data of each component in the liquid phase products containing α-olefins prepared in Examples 1-11 and Comparative Examples 1-3 are statistically shown in Table 2 below.

[0107] Table 1

[0108]

[0109] In Table 1, “ / ” indicates that the data in question has not been measured; Comparative Example 1 uses a 5L high-pressure reactor instead of a microchannel reactor, and therefore does not involve the channel inner diameter and channel length of the microchannel reactor.

[0110] Table 2

[0111]

[0112]

[0113] The 1-octene / 1-hexene ratio in Table 2 is calculated as the ratio of the selectivity for 1-octene to the selectivity for 1-hexene.

[0114] From the data recorded in Table 2, it can be seen that the method for continuously preparing α-olefins by ethylene polymerization of the present invention uses a microchannel reactor and limits the channel inner diameter and channel length of the microchannel reactor, the mass ratio of the solvent, the main catalyst and the co-catalyst, the volume flow rate of ethylene, and the reaction temperature and reaction time. The proportion of 1-octene and 1-hexene in the prepared α-olefins exceeds 85%, and the ratio of 1-octene / 1-hexene is 1 to 8.

[0115] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for continuously preparing α-olefins by ethylene oligomerization, characterized in that: The following steps are involved: S1, mixing the main catalyst and the co-catalyst in a solvent to obtain a reaction medium; S2, mixing the reaction medium with ethylene and feeding the mixture into a microchannel reactor to react and obtain a product containing α-olefins; A reaction channel is arranged in the microchannel reactor; the length of the reaction channel is 10m to 100m; and the inner diameter of the reaction channel is 1mm to 6mm.

2. The method according to claim 1, characterized in that The mass ratio of the solvent, the main catalyst and the co-catalyst in the reaction medium is (5000-200000):1:(200-1000); And / or, the solvent is selected from at least one of toluene, 1-hexene, 1-octene, n-heptane, cyclohexane, and methylcyclohexane; And / or, the co-catalyst is at least one of methylaluminoxane, modified methylaluminoxane, triisobutylaluminum, tri-n-butylaluminum, triethylaluminum, and tripropylaluminum; And / or, the main catalyst is selected from at least one of a Cr-based catalyst, a Ni-based catalyst, and a Fe-based catalyst.

3. The method according to claim 1 or 2, characterized in that: The reaction medium includes a preheating treatment I before mixing with ethylene; preferably, the preheating treatment I is carried out in a liquid phase preheater, the temperature of the liquid phase preheater is 30° C. to 60° C., and the volume flow rate of the reaction medium is 1 mL / min to 30 mL / min; And / or, the ethylene includes a preheating treatment II before mixing with the reaction medium; preferably, the preheating treatment II is carried out in a gas phase preheater, the temperature of the gas phase preheater is 30°C to 60°C, and the volume flow rate of ethylene is 50mL / min to 1000mL / min.

4. The method according to any one of claims 1 to 3, characterized in that The reaction conditions include: temperature of 30°C to 80°C, preferably 40°C to 60°C; pressure of 1.0MPa to 6.0MPa, preferably 3.0MPa to 5.0MPa; reaction time of 1min to 60min, preferably 5min to 40min, more preferably 10min to 30min.

5. The method according to any one of claims 1 to 4, characterized in that The length of the reaction channel is 10m to 40m; the inner diameter of the reaction channel is 2mm to 5mm; preferably, the cross section of the reaction channel is circular.

6. The method according to any one of claims 1 to 5, characterized in that The reaction further includes gas-liquid separation; preferably, the conditions for the gas-liquid separation include: a pressure of 2.0 MPa to 6.0 MPa.

7. The method according to any one of claims 1 to 6, characterized in that The volume flow ratio of the ethylene and the reaction medium is (10-200):

1.

8. An α-olefin prepared by the method according to any one of claims 1 to 7; preferably, the proportion of 1-octene and 1-hexene in the α-olefin exceeds 90%; and / or the ratio of 1-octene / 1-hexene in the α-olefin is 1 to 8, preferably 2 to 5.

9. Use of the α-olefin prepared by the method according to any one of claims 1 to 7 or the α-olefin according to claim 8 in the preparation of polyethylene, poly-α-olefin, or polyolefin elastomer.

10. Use of the α-olefin prepared by the method according to any one of claims 1 to 7 or the α-olefin according to claim 8 in the preparation of lubricating oil or surfactant.

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