Device and method for preparing alpha olefins by tetramerization of ethylene

Abstract

The invention discloses a device and method for preparing alpha olefins by tetramerization of ethylene, belongs to the technical field of chemical product preparation, and comprises a feeding system, a jet reactor, a stop kettle, a flash tank and a separation and recovery system connected in sequence; a mixing ejector is provided inside the jet reactor; a plug flow agitator is provided inside the stop kettle; the separation and recovery system comprises a de-ethylene tower, a de-hexene tower, a solvent recovery tower, a de-isomerization hexene tower, a weight removal tower and a de-high carbon tower, and the de-ethylene tower, the de-hexene tower, the solvent recovery tower, the weight removal tower and the de-high carbon tower are connected in sequence, and the solvent recovery tower is also connected to the de-isomerization hexene tower. The present invention can realize the enhanced mixing of gas, liquid and catalyst, ensure a certain polymerization reaction time, enable ethylene to fully complete the polymerization reaction, improve the polymerization reaction conversion rate, improve the activity of the catalyst, reduce the generation of oligomerization and high polymer (PE), and enable production to achieve long-term operation.

Description

Technical Field

[0001] The invention relates to the technical field of chemical product preparation, and in particular to a device and method for preparing alpha olefins by ethylene tetramerization. Background Art

[0002] Ethylene tetramerization is a chemical process used to convert ethylene molecules into alpha-olefins, specifically 1-hexene. Alpha-olefins are a class of hydrocarbon compounds with a specific structure and properties, which contain a double bond and an alpha-carbon atom (the carbon atom directly attached to the double bond) in the molecule. Ethylene tetramerization is usually carried out in the presence of a catalyst, which is usually a metal complex or a metal oxide. The reaction process involves the successive addition of ethylene molecules to form the tetramer, i.e. 1-hexene.

[0003] In the existing ethylene tetramerization high carbon alpha olefin production technology, the polymerization kettle is composed of one or more units with a stirrer, such as patent CN116059939 A. In this way, the mixing effect of ethylene and hydrogen with the solvent and catalyst in the polymerization kettle is poor, the catalyst consumption is large, the catalytic activity and the selectivity of alpha olefins are reduced, and the reaction causes the content of oligomers and polymers (PE) to increase. The polymer will stick to the stirrer and the baffle in the kettle, affecting the decline of product quality. The device must be frequently stopped for maintenance, which seriously affects the operation of the device and cannot achieve long-term operation of the device.

[0004] In the existing industrial ethylene tetramerization high carbon alpha olefin production technology, the terminator is added into a termination kettle with a full mixing agitator, or into a pipeline static mixer to terminate the reaction, such as patent CN110639459A. The reaction endpoint cannot be accurately controlled, resulting in a low ethylene conversion rate in the polymerization reaction, a decrease in polymer yield, and low production efficiency.

[0005] The existing technology has a small surface area for gas-liquid separation, resulting in poor ethylene flash evaporation effect. The amount of ethylene flashed can only reach 58% (wt) of the total amount of unreacted converted ethylene, which increases the load of the unit deethylene tower after the flash evaporation.

[0006] In view of this, this application is filed. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a device and method for preparing alpha olefins by tetramerization of ethylene, which can achieve enhanced mixing of gas, liquid and catalyst, ensure a certain polymerization reaction time, enable ethylene to fully complete the polymerization reaction, improve the polymerization reaction conversion rate, improve the activity of the catalyst, reduce the generation of oligomers and polymers (PE), and enable production to achieve long-term operation.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] An ethylene tetramerization device for preparing alpha olefins comprises a feeding system, a jet reactor, a termination kettle, a flash tank and a separation and recovery system connected in sequence;

[0010] A mixing ejector is provided inside the jet reactor;

[0011] A plug flow agitator is provided inside the termination kettle;

[0012] The separation and recovery system comprises a deethylene tower, a dehexene tower, a solvent recovery tower, a deisomerization hexene tower, a weight removal tower and a high carbon removal tower, wherein the deethylene tower, the dehexene tower, the solvent recovery tower, the weight removal tower and the high carbon removal tower are connected in sequence, and the solvent recovery tower is also connected to the deisomerization hexene tower.

[0013] Preferably, the jet reactor is connected to an external circulation cooler via an external circulation pump.

[0014] Preferably, a first filter is provided between the jet reactor and the termination kettle.

[0015] Preferably, a second filter and a reaction liquid feed pump are sequentially provided between the flash tank and the separation and recovery system.

[0016] Preferably, the feeding system includes an ethylene tank, a co-catalyst tank, a main catalyst tank, a solvent tank, a hydrogen tank, and a promoter tank. The co-catalyst tank and the main catalyst tank are connected to a static mixer. The ethylene tank, the solvent tank and the static mixer are connected to a premixing kettle. The premixing kettle, the hydrogen tank and the promoter tank are all connected to the jet reactor.

[0017] Preferably, it also includes a nitrogen tank and a terminator tank, wherein the nitrogen tank is connected to the jet reactor, and the terminator tank is connected to the termination reactor.

[0018] Preferably, it further comprises an ethylene recycling tank, which is connected to the deethylene tower and the flash tank respectively, and is also connected to the premixing kettle via the first compressor.

[0019] The present invention also provides a method for preparing alpha olefins by tetramerization of ethylene, based on the above-mentioned device for preparing alpha olefins by tetramerization of ethylene, comprising the following steps:

[0020] (1) premixing ethylene and a solvent to obtain a premix, premixing a co-catalyst and a main catalyst to obtain a premixed catalyst, adding the premixed catalyst, the premix, hydrogen, and a promoter into a jet reactor to carry out a polymerization reaction, wherein the temperature of the polymerization reaction is controlled by an external circulation cooler;

[0021] (2) The material after the reaction enters the termination kettle, and the terminator is added to terminate the reaction. Then the material enters the flash tank for flash evaporation. The flashed material is filtered through the first filter and then passes through the deethylene tower. Ethylene is extracted from the top of the deethylene tower. The bottom material of the top of the deethylene tower enters the dehexene tower. 1-hexene is extracted from the top of the dehexene tower. The bottom material of the dehexene tower enters the solvent recovery tower. The carbon 6 component is extracted from the top of the solvent recovery tower. The carbon 6 component enters the deisomerization hexene tower. The isomerized carbon 6 product is extracted from the top of the deisomerization hexene tower. The solvent is extracted from the bottom of the deisomerization hexene tower. The bottom material of the solvent recovery tower enters the deheaving tower. 1-octene is extracted from the top of the deheaving tower. The bottom material of the deheaving tower enters the deheaving tower. 1-decene is extracted from the top of the deheaving tower. High carbon mixed olefins are extracted from the bottom of the deheaving tower.

[0022] Preferably, at least one of the following (a) to (e) is satisfied:

[0023] (a) The main catalyst comprises chromium acetylacetonate, tri(tetrahydrofuran)chromium trichloride, and a chromium-based bisphosphamide ligand;

[0024] (b) the co-catalyst comprises at least one of trimethylaluminum, sesquiethylaluminum, methylaluminoxane, and modified methylaluminoxane;

[0025] (c) the solvent comprises at least one of xylene, o-xylene, toluene, cyclohexane, isobutane, n-pentane, isopentane, n-hexane, methylcyclopentane, n-heptane, methylcyclohexane and isooctane;

[0026] (d) the promoter comprises at least one of triethylaluminum and triisobutylaluminum;

[0027] (e) The terminator comprises at least one of isodecyl alcohol, acidified ethanol, 2-methyl-1,5-pentamethylenediamine, ethylene glycol, glycerol, butanediol, hexanediol, isooctyl alcohol, and ethanolamine.

[0028] Preferably, the molar ratio of Cr in the main catalyst to the co-catalyst is (480-650):1.

[0029] Preferably, the amount of the main catalyst added to the jet reactor is 3.5 to 7.5 umol / L based on the Cr molar amount of the main catalyst.

[0030] Preferably, the mass ratio of the solvent to ethylene is 1:(0.5-1.5).

[0031] Preferably, the molar ratio of Al in the promoter to Cr in the main catalyst is (40-60):1.

[0032] Preferably, the molar ratio of Al in the terminator to the promoter is (1.2-2.5):1.

[0033] Preferably, the molar ratio of the flow rate of hydrogen to the Cr in the main catalyst is 1 L / h: (1-10) mol.

[0034] Preferably, the polymerization reaction temperature is 55-68° C., the polymerization reaction time is 15-45 min, and the polymerization reaction pressure is 3.2-4.8 MPa.

[0035] Preferably, the pressure in the termination kettle is 3.5-4 MPa, and the temperature is 55-68°C.

[0036] Preferably, the flash evaporation pressure is 1.5-3 MPa, and the flash evaporation temperature is 60-85°C.

[0037] The beneficial effects of the present invention are as follows: the device for preparing alpha olefins by tetramerization of ethylene of the present invention creatively adopts a feeding system, a jet reactor, a stop kettle, a flash tank and a separation and recovery system connected in sequence; a mixing ejector is arranged inside the jet reactor, and a plug flow agitator is arranged inside the stop kettle, so that gas, liquid and catalyst can be mixed intensively, a certain polymerization reaction time is guaranteed, ethylene can fully complete the polymerization reaction, the polymerization reaction conversion rate is improved, the activity of the catalyst is improved, the generation of oligomers and high polymers (PE) is reduced, and the production can achieve long-term operation (the continuous operation cycle is 60 days, which is higher than the existing 30 days); under the steady state, the reaction materials will not be mixed back, and there is no uneven concentration distribution in the radial direction; the terminator can be selectively added according to the polymerization reaction situation, the polymerization reaction time can be effectively controlled, and the ethylene conversion rate is improved; the present invention adopts flash evaporation to increase the gas-liquid separation area, which is helpful to improve the flash evaporation effect of ethylene; through the flash evaporation effect detection, the amount of ethylene flashed out of the flash tank reaches more than 65% of the total amount of unreacted converted ethylene, and the production load of the deethylene tower is effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic structural diagram of the device for preparing alpha olefins by ethylene tetramerization according to the present invention.

[0039] Figure 2 It is a structural schematic diagram of the separation and recovery system of the present invention.

[0040] Markings in the figure: 1. jet reactor; 101. mixing ejector; 2. termination kettle; 201. plug flow agitator; 3. flash tank; 301. agitator; 4. separation and recovery system; 401. deethylene tower; 402. dehexene tower; 403. solvent recovery tower; 404. deisomerization hexene tower; 405. deweighting tower; 406. decarbonization tower; 5. external circulation cooler; 6. external circulation pump; 7. first filter; 8. second filter; 9. reaction liquid feed pump; 10. ethylene recycling tank; 11. first compressor; 12. ethylene tank; 13. second compressor; 14. co-catalyst tank; 15. main catalyst tank; 16. solvent tank; 17. hydrogen tank; 18. nitrogen tank; 19. accelerator tank; 20. static mixer; 21. premixing kettle; 22. termination tank. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0042] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0043] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0044] In the present application, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0045] Unless otherwise specified, the components, raw materials or instruments used in the embodiments and comparative examples of the present invention are all commercially available raw materials or instruments, and the components and raw materials used in each parallel experiment are all of the same kind.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0047] The embodiment of the present application provides a device for preparing alpha olefins by tetramerization of ethylene, comprising a feeding system, a jet reactor 1, a termination kettle 2, a flash tank 3 and a separation and recovery system 4 connected in sequence;

[0048] The jet reactor 1 is provided with a mixing ejector 101 inside;

[0049] The end kettle 2 is provided with a plug flow agitator 201 inside;

[0050] The separation and recovery system includes a deethylene tower 401, a dehexene tower 402, a solvent recovery tower 403, a deisomerization hexene tower 404, a weight removal tower 405 and a high carbon removal tower 406. The deethylene tower 401, the dehexene tower 402, the solvent recovery tower 403, the weight removal tower 405 and the high carbon removal tower 406 are connected in sequence, and the solvent recovery tower 403 is also connected to the deisomerization hexene tower 404.

[0051] The device for preparing alpha olefins by tetramerization of ethylene of the present invention creatively adopts a feeding system, a jet reactor 1, a stopper 2, a flash tank 3 and a separation and recovery system 4 connected in sequence. A mixing ejector 101 is arranged inside the jet reactor 1, and a plug flow agitator 201 is arranged inside the stopper 2, so that gas, liquid and catalyst can be mixed intensively, a certain polymerization reaction time is guaranteed, ethylene can fully complete the polymerization reaction, the polymerization reaction conversion rate is improved, the activity of the catalyst is improved, the generation of oligomers and high polymers (PE) is reduced, and the production can achieve long-term operation (the continuous operation cycle is 60 days, which is higher than the existing 30 days); under the steady state, the reaction materials will not be mixed back, and there is no uneven concentration distribution in the radial direction. The terminator can be selectively added according to the polymerization reaction situation, so that the polymerization reaction time can be effectively controlled and the ethylene conversion rate is improved. The present invention adopts flash evaporation to increase the gas-liquid separation area, which is helpful to improve the flash evaporation effect of ethylene. According to the flash evaporation effect detection, the amount of ethylene flashed out of the flash tank reaches more than 65% of the total amount of unreacted converted ethylene, which effectively reduces the production load of the deethylene tower.

[0052] In one embodiment, the jet reactor 1 is connected to an external circulation cooler 5 via an external circulation pump 6 .

[0053] In one embodiment, the number of the external circulation coolers 5 is two, and the two external circulation coolers 5 are connected in series.

[0054] In one embodiment, the effective volume of the jet reactor 1 is 200 L. The inner cavity aspect ratio is 1.5, the maximum working pressure of the reactor is 10 MPa, the maximum working temperature is 125 ° C, the mixing ejector 2 is a Venturi type mixing ejector, the jet port of the mixing ejector 2 is inserted into the lower part of the jet reactor 1, located at 30% of the liquid level, the inner wall of the jet reactor 1 is mirror polished, and the jet reactor 1 is provided with a liquid level transmitter, a pressure gauge, a safety valve, a pressure sensor, a temperature probe, a temperature transmitter, an emergency pressure relief valve, and is connected to the DCS system to monitor the changes in pressure and temperature in the reactor at any time.

[0055] In one embodiment, a first filter 7 is provided between the jet reactor 1 and the termination kettle 2 .

[0056] In one embodiment, the plug flow agitator is provided with nine layers of plug slurries and is divided into three zones. Each zone can selectively add the terminator into one of the latter two zones or into a static mixer outside the kettle according to the polymerization reaction conditions. The effective volume of the termination kettle is 80L, the stirring speed is 58r / min, the inner cavity aspect ratio is 1.4, the maximum working pressure of the reactor is 10Mpa, the maximum working temperature is 120°C, and the inner wall of the termination kettle is mirror polished. The kettle is provided with a stirring current, a pressure gauge, a safety valve, a pressure sensor and a temperature probe, and is connected to the DCS system to monitor the changes in the pressure and temperature in the kettle at any time.

[0057] In one embodiment, a second filter 8 and a reaction liquid feed pump 9 are sequentially provided between the flash tank 3 and the separation recovery system 4 .

[0058] In one embodiment, the flash tank 3 is provided with a jacket hot water heating system to maintain a certain temperature to prevent the polymer from agglomerating and adhering to the wall and clogging the pipeline after being cooled.

[0059] In one embodiment, the flash tank 3 is a horizontal flash tank.

[0060] In one embodiment, the gaseous material flashed out of the flash tank 3 enters the heat exchanger for condensation, and then enters the ethylene recycling buffer tank for gas-liquid separation. The ethylene is metered by the first compressor and then enters the polymerization kettle for recycling. The solvent is cooled and returned by the pump for pressure boosting.

[0061] In one embodiment, the effective volume of the flash tank 3 is 480L. The tank is provided with two agitators 301, each agitator 301 has three layers of turbine paddles, the stirring speed is 38r / min, the inner cavity aspect ratio is 1.2, the maximum working pressure of the first-stage flash tank is 5Mpa, the maximum working temperature is 120°C, and the liquid level control range is 50%. The tank is provided with a liquid level transmitter, a stirring current, a pressure gauge, a safety valve, a pressure sensor and a temperature probe, and is connected to the DCS system to monitor the changes in the liquid level, pressure and temperature in the tank at any time.

[0062] In one embodiment, the feeding system includes an ethylene tank 12, a co-catalyst tank 14, a main catalyst tank 15, a solvent tank 16, a hydrogen tank 17, and a promoter tank 19. The co-catalyst tank 14 and the main catalyst tank 15 are connected to a static mixer 20. The ethylene tank 12, the solvent tank 16 and the static mixer 20 are connected to a premixing kettle 21. The premixing kettle 21, the hydrogen tank 17, and the promoter tank 19 are all connected to the jet reactor 1.

[0063] In one embodiment, a second compressor 13 is further provided between the ethylene tank 12 and the premixing kettle.

[0064] In one embodiment, the system further comprises a nitrogen tank 18 and a terminator tank 22 , wherein the nitrogen tank 18 is connected to the jet reactor 1 , and the terminator tank 22 is connected to the termination reactor 2 .

[0065] The nitrogen tank 18 does not work when the device is in normal operation, but when an emergency occurs in the device, the nitrogen tank 18 is activated to introduce nitrogen to terminate the reaction.

[0066] In one embodiment, an ethylene recycling tank 10 is further included. The ethylene recycling tank 10 is connected to the deethylene tower 401 and the flash tank 3 respectively. The ethylene recycling tank 10 is also connected to the premixing kettle 21 through the first compressor 11.

[0067] The present invention also provides a method for preparing alpha olefins by tetramerization of ethylene, based on the above-mentioned device for preparing alpha olefins by tetramerization of ethylene, comprising the following steps:

[0068] (1) premixing ethylene and a solvent to obtain a premix, premixing a co-catalyst and a main catalyst to obtain a premixed catalyst, adding the premixed catalyst, the premix, hydrogen, and a promoter into a jet reactor to carry out a polymerization reaction, wherein the temperature of the polymerization reaction is controlled by an external circulation cooler;

[0069] (2) The material after the reaction enters the termination kettle, and the terminator is added to terminate the reaction. Then the material enters the flash tank for flash evaporation. The flashed material is filtered through the first filter and then passes through the deethylene tower. Ethylene is extracted from the top of the deethylene tower. The bottom material of the top of the deethylene tower enters the dehexene tower. 1-hexene is extracted from the top of the dehexene tower. The bottom material of the dehexene tower enters the solvent recovery tower. The carbon 6 component is extracted from the top of the solvent recovery tower. The carbon 6 component enters the deisomerization hexene tower. The isomerized carbon 6 product is extracted from the top of the deisomerization hexene tower. The solvent is extracted from the bottom of the deisomerization hexene tower. The bottom material of the solvent recovery tower enters the deheaving tower. 1-octene is extracted from the top of the deheaving tower. The bottom material of the deheaving tower enters the deheaving tower. 1-decene is extracted from the top of the deheaving tower. High carbon mixed olefins are extracted from the bottom of the deheaving tower.

[0070] In one embodiment, at least one of the following (a) to (e) is satisfied:

[0071] (a) The main catalyst comprises chromium acetylacetonate, tri(tetrahydrofuran)chromium trichloride, and a chromium-based bisphosphamide ligand;

[0072] (b) the co-catalyst comprises at least one of trimethylaluminum, sesquiethylaluminum, methylaluminoxane, and modified methylaluminoxane;

[0073] (c) the solvent comprises at least one of xylene, o-xylene, toluene, cyclohexane, isobutane, n-pentane, isopentane, n-hexane, methylcyclopentane, n-heptane, methylcyclohexane and isooctane;

[0074] (d) the promoter comprises at least one of triethylaluminum and triisobutylaluminum;

[0075] (e) The terminator comprises at least one of isodecyl alcohol, acidified ethanol, 2-methyl-1,5-pentamethylenediamine, ethylene glycol, glycerol, butanediol, hexanediol, isooctyl alcohol, and ethanolamine.

[0076] Wherein, ethylene, solvent, co-catalyst, main catalyst, promoter, and terminator are fed respectively through corresponding tanks, for example, ethylene is fed through an ethylene tank.

[0077] Optionally, the raw materials in the solvent tank can be pressurized by a pump and selectively passed through one or more of a deoxygenation bed, a drying bed, a desulfurization bed, a dechlorination bed, a carbon monoxide removal bed, and a carbon dioxide removal bed for refining according to the impurity situation. After the raw materials are refined, they enter the refined solvent tank for storage. An online water and oxygen detection probe is installed after the refining bed. If the water and oxygen in the refined raw materials are greater than 3ppm, they can be returned to the raw material tank through the reflux pipeline for re-refining.

[0078] Optionally, the raw materials in each gas raw material tank (ethylene tank, co-catalyst tank, main catalyst tank, promoter tank, terminator tank, hydrogen tank, nitrogen tank) can be pressurized and selectively refined through one or more of the deoxygenation bed, drying bed, desulfurization bed, dechlorination bed, carbon monoxide removal bed, and carbon dioxide removal bed according to the impurity situation, and directly used by the polymerization system. An online water and oxygen detection probe is installed after the refining bed. If the water and oxygen in the refined gas raw material are >3ppm, the spare bed can be switched to ensure that the gas raw material meets the control index.

[0079] In one embodiment, the molar ratio of Cr in the main catalyst to the co-catalyst is (480-650):1.

[0080] In one embodiment, the amount of the main catalyst added to the jet reactor is 3.5 to 7.5 umol / L based on the Cr molar amount of the main catalyst.

[0081] In one embodiment, the mass ratio of the solvent to ethylene is 1:(0.5-1.5).

[0082] In one embodiment, the molar ratio of Al in the promoter to Cr in the main catalyst is (40-60):1.

[0083] In one embodiment, the molar ratio of Al in the terminator to the promoter is (1.2-2.5):1.

[0084] In one embodiment, the molar ratio of the flow rate of hydrogen to the Cr in the main catalyst is 1 L / h: (1-10) mol.

[0085] In one embodiment, the feed temperature of ethylene and solvent is 15-25°C.

[0086] In one embodiment, the polymerization reaction temperature is 55-68° C., the polymerization reaction time is 15-45 min, and the polymerization reaction pressure is 3.2-4.8 MPa.

[0087] In one embodiment, the pressure in the termination kettle is 3.5-4 MPa, and the temperature is 55-68°C.

[0088] In one embodiment, the flash evaporation pressure is 1.5-3 MPa, and the flash evaporation temperature is 60-85°C.

[0089] In one embodiment, the deethylene tower has a pressure of 1-3 MPa and a temperature of 200-230°C.

[0090] In one embodiment, the dehexene tower has a pressure of 0.11-0.13 MPa and a temperature of 110-115°C.

[0091] In one embodiment, the pressure of the solvent recovery tower is 0.13-0.15 MPa and the temperature is 115-120°C.

[0092] In one embodiment, the deisomerization hexene tower has a pressure of 0.15-0.18 MPa and a temperature of 145-150°C.

[0093] In one embodiment, the deweighting tower has a pressure of -0.025 to -0.028 MPa and a temperature of 180 to 185°C.

[0094] In one embodiment, the pressure of the high carbon removal tower is -0.030 to -0.035 MPa, and the temperature is 205 to 215°C.

[0095] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0096] Example 1

[0097] An apparatus for preparing alpha olefins by tetramerization of ethylene comprises a feeding system, a jet reactor, a first filter, a stop kettle, a second flash tank filter, a reaction liquid feed pump and a separation and recovery system which are connected in sequence; a mixing ejector is arranged inside the jet reactor; a plug flow agitator is arranged inside the stop kettle; the separation and recovery system comprises a deethylene tower, a dehexene tower, a solvent recovery tower, a deisomerization hexene tower, a weight removal tower and a high carbon removal tower, wherein the deethylene tower, the dehexene tower, the solvent recovery tower, the weight removal tower and the high carbon removal tower are connected in sequence, and the solvent recovery tower is also connected to the deisomerization hexene tower.

[0098] Wherein, the jet reactor is connected to an external circulation cooler via an external circulation pump, the number of the external circulation coolers is two, and the two external circulation coolers are connected in series.

[0099] The flash tank is provided with a jacket hot water heating system to maintain a certain temperature to prevent the polymer from agglomerating and adhering to the wall and clogging the pipeline after being cooled.

[0100] Among them, the feeding system includes an ethylene tank, a co-catalyst tank, a main catalyst tank, a solvent tank, a hydrogen tank, and a promoter tank. The co-catalyst tank and the main catalyst tank are connected with a static mixer, and the ethylene tank, the solvent tank and the static mixer are connected with a premixing kettle. The premixing kettle, the hydrogen tank, and the promoter tank are all connected with the jet reactor.

[0101] Wherein, a second compressor is also provided between the ethylene tank and the premixing kettle.

[0102] Among them, it also includes a nitrogen tank, a terminator tank and an ethylene recovery tank. The nitrogen tank is connected to the jet reactor, the terminator tank is connected to the termination kettle, the ethylene recovery tank is connected to the deethylene tower and the flash tank respectively, and the ethylene recovery tank is also connected to the premixing kettle through the first compressor.

[0103] The device for preparing alpha olefins based on the above-mentioned ethylene tetramerization comprises the following steps:

[0104] (1) premixing ethylene and a solvent to obtain a premix, premixing a co-catalyst and a main catalyst to obtain a premixed catalyst, adding the premixed catalyst, the premix, hydrogen, and a promoter into a jet reactor to carry out a polymerization reaction, wherein the temperature of the polymerization reaction is controlled by an external circulation cooler;

[0105] (2) The material after the reaction enters the termination kettle, and the terminator is added to terminate the reaction. Then the material enters the flash tank for flash evaporation. The flashed material is filtered through the first filter and then passes through the deethylene tower. Ethylene is extracted from the top of the deethylene tower. The bottom material of the top of the deethylene tower enters the dehexene tower. 1-hexene is extracted from the top of the dehexene tower. The bottom material of the dehexene tower enters the solvent recovery tower. The carbon 6 component is extracted from the top of the solvent recovery tower. The carbon 6 component enters the deisomerization hexene tower. The isomerized carbon 6 product is extracted from the top of the deisomerization hexene tower. The solvent is extracted from the bottom of the deisomerization hexene tower. The bottom material of the solvent recovery tower enters the deheaving tower. 1-octene is extracted from the top of the deheaving tower. The bottom material of the deheaving tower enters the deheaving tower. 1-decene is extracted from the top of the deheaving tower. High carbon mixed olefins are extracted from the bottom of the deheaving tower.

[0106] In this embodiment, the main catalyst is chromium acetylacetonate, the co-catalyst is methylaluminoxane, the solvent is cyclohexane, the promoter is triethylaluminum, and the terminator is isooctyl alcohol.

[0107] In this embodiment, the molar ratio of Cr in the main catalyst to the co-catalyst is 550:1, the amount of the main catalyst added to the jet reactor is 4.5umol / L based on the molar amount of Cr in the main catalyst, the mass ratio of the solvent to ethylene is 1:1, the molar ratio of Al in the promoter to Cr in the main catalyst is 50:1, the molar ratio of the terminator to Al in the promoter is 1.5:1, and the molar ratio of the flow rate of hydrogen to Cr in the main catalyst is L / h:4mol.

[0108] In this embodiment, the polymerization reaction temperature is 58°C, the polymerization reaction time is 30 min, and the polymerization reaction pressure is 4.5 MPa; the pressure in the termination kettle is 3.7 MPa and the temperature is 58°C; the flash pressure is 1.78 MPa and the flash temperature is 80°C.

[0109] In this embodiment, the pressure of the deethylene tower is 2MPa and the temperature is 220°C. The pressure of the dehexene tower is 0.12MPa and the temperature is 112°C. The pressure of the solvent recovery tower is 0.14MPa and the temperature is 118°C. The pressure of the deisomerization hexene tower is 0.6MPa and the temperature is 148°C. The pressure of the deweighting tower is -0.026MPa and the temperature is 182°C. The pressure of the high carbon removal tower is -0.032MPa and the temperature is 210°C.

[0110] In this embodiment, sampling is performed after the termination reaction is completed, and the collected products are analyzed and calculated by gas chromatography. The catalytic activity of ethylene tetramerization is about 4540kg / gCr.h, the selectivity of 1-hexene is 17.332%, the selectivity of 1-octene is 72.168%, the polymer PE content is 0.01%, the ethylene conversion rate is 75%, and the amount of ethylene flashed out of the flash tank is measured and calculated to reach 65% (wt) of the total amount of unreacted converted ethylene.

[0111] The purity of 1-octene obtained in this example is as high as 99.45%.

[0112] Example 2

[0113] The difference between Example 2 and Example 1 is that the reaction parameters are different, and the others are the same.

[0114] In this embodiment, the polymerization reaction temperature is 55°C, the polymerization reaction time is 45 min, and the polymerization reaction pressure is 3.2 MPa; the pressure in the termination kettle is 3.5 MPa and the temperature is 68°C; the flash pressure is 3 MPa and the flash temperature is 60°C.

[0115] In this embodiment, sampling is performed after the termination reaction is completed, and the collected products are analyzed and calculated by gas chromatography. The catalytic activity of ethylene tetramerization is 4205kg / gCr.h, the selectivity of 1-hexene is 16.167%, the selectivity of 1-octene is 70.325%, the polymer PE content is 0.01%, the ethylene conversion rate is 73%, and the amount of ethylene flashed out of the flash tank is measured and calculated to reach 65% (wt) of the total amount of unreacted converted ethylene.

[0116] The purity of 1-octene obtained in this example is 98.55%.

[0117] Example 3

[0118] The difference between Example 3 and Example 1 is that the reaction parameters are different, and the others are the same.

[0119] In this embodiment, the polymerization reaction temperature is 68°C, the polymerization reaction time is 15 min, and the polymerization reaction pressure is 4.8 MPa; the pressure in the termination kettle is 4 MPa and the temperature is 55°C; the flash pressure is 1.5 MPa and the flash temperature is 85°C.

[0120] In this embodiment, sampling is performed after the termination reaction is completed, and the collected products are analyzed and calculated by gas chromatography. The catalytic activity of ethylene tetramerization is 3814kg / gCr.h, the selectivity of 1-hexene is 16.28%, the selectivity of 1-octene is 71.325%, the polymer PE content is 0.01%, the ethylene conversion rate is 65%, and the amount of ethylene flashed out of the flash tank is measured and calculated to reach 58% (wt) of the total amount of unreacted converted ethylene.

[0121] The purity of 1-octene obtained in this example is 98.71%.

[0122] Comparative Example 1

[0123] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses a kettle reactor to replace the jet reactor, and the polymerization reaction temperature and time and other conditions are the same as those of Example 1.

[0124] In this comparative example, sampling was performed after the termination reaction was completed, and the collected products were analyzed and calculated by gas chromatography. The catalytic activity of ethylene tetramerization was 3537kg / gCr.h, the selectivity of 1-hexene was 15.16%, the selectivity of 1-octene was 58.154%, the polymer PE content was 0.18%, the ethylene conversion rate was 45%, and the amount of ethylene flashed out of the flash tank was measured to reach 52% (wt) of the total amount of unreacted converted ethylene.

[0125] The purity of 1-octene obtained in this example is 88.18%.

[0126] Comparative Example 2

[0127] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses a pipeline static mixer to replace the termination kettle (that is, this comparative example terminates in the pipeline), and the rest is the same.

[0128] In this comparative example, sampling was performed after the termination reaction was completed, and the collected products were analyzed and calculated by gas chromatography. The catalytic activity of ethylene tetramerization was 3558kg / gCr.h, the selectivity of 1-hexene was 14.23%, the selectivity of 1-octene was 70.21%, the polymer PE content was 0.06%, the ethylene conversion rate was 73%, and the amount of ethylene flashed out of the flash tank was measured to reach 62% (wt) of the total amount of unreacted converted ethylene.

[0129] The purity of 1-octene obtained in this example is 90.86%.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing alpha olefins by tetramerization of ethylene, characterized in that: The device for preparing alpha olefins based on ethylene tetramerization comprises the following steps: (1) premixing ethylene and a solvent to obtain a premix, premixing a co-catalyst and a main catalyst to obtain a premixed catalyst, adding the premixed catalyst, the premix, hydrogen, and a promoter into a jet reactor to carry out a polymerization reaction, wherein the temperature of the polymerization reaction is controlled by an external circulation cooler; (2) The materials after the reaction enter the termination kettle, and the terminator is added to terminate the reaction. Then the materials enter the flash tank for flash evaporation. After the flash evaporation, the materials are filtered through the first filter and then pass through the deethylene tower. Ethylene is extracted from the top of the deethylene tower. The materials at the bottom of the deethylene tower enter the dehexene tower. 1-hexene is extracted from the top of the dehexene tower. The materials at the bottom of the dehexene tower enter the solvent recovery tower. The carbon 6 component is extracted from the top of the solvent recovery tower. The carbon 6 component enters the deisomerization hexene tower. The isomerized carbon 6 product is extracted from the top of the deisomerization hexene tower. The solvent is extracted from the bottom of the deisomerization hexene tower. The materials at the bottom of the solvent recovery tower enter the deheaving tower. 1-octene is extracted from the top of the deheaving tower. The materials at the bottom of the deheaving tower enter the high carbon tower. 1-decene is extracted from the top of the high carbon tower. High carbon mixed olefins are extracted from the bottom of the high carbon tower. The device for preparing alpha olefins by tetramerization of ethylene comprises a feeding system, a jet reactor, a termination kettle, a flash tank and a separation and recovery system connected in sequence; A mixing ejector is provided inside the jet reactor; A plug flow agitator is provided inside the termination kettle; The separation and recovery system comprises a deethylene tower, a dehexene tower, a solvent recovery tower, a deisomerization hexene tower, a weight removal tower and a high carbon removal tower, wherein the deethylene tower, the dehexene tower, the solvent recovery tower, the weight removal tower and the high carbon removal tower are connected in sequence, and the solvent recovery tower is also connected to the deisomerization hexene tower; A first filter is provided between the jet reactor and the termination kettle; A second filter and a reaction liquid feed pump are sequentially arranged between the flash tank and the separation and recovery system; The feeding system includes an ethylene tank, a co-catalyst tank, a main catalyst tank, a solvent tank, a hydrogen tank, and a promoter tank. The co-catalyst tank and the main catalyst tank are connected with a static mixer. The ethylene tank, the solvent tank and the static mixer are connected with a premixing kettle. The premixing kettle, the hydrogen tank and the promoter tank are all connected with a jet reactor.

2. The method for preparing alpha olefins by tetramerization of ethylene according to claim 1, characterized in that: Satisfy at least one of the following (a) to (e): (a) The main catalyst comprises chromium acetylacetonate, tri(tetrahydrofuran)chromium trichloride or a chromium-based bisphosphamide ligand; (b) the co-catalyst comprises at least one of trimethylaluminum, sesquiethylaluminum, methylaluminoxane, and modified methylaluminoxane; (c) the solvent comprises at least one of o-xylene, toluene, cyclohexane, isobutane, n-pentane, isopentane, n-hexane, methylcyclopentane, n-heptane, methylcyclohexane and isooctane; (d) the promoter comprises at least one of triethylaluminum and triisobutylaluminum; (e) The terminator includes at least one of isodecyl alcohol, acidified ethanol, 2-methyl-1,5-pentamethylenediamine, ethylene glycol, glycerol, butanediol, hexanediol, isooctyl alcohol, and ethanolamine.

3. The method for preparing alpha olefins by tetramerization of ethylene according to claim 2, characterized in that: The molar ratio of Cr in the main catalyst to the co-catalyst is (480-650):1; and / or The amount of the main catalyst added to the jet reactor is 3.5-7.5 umol / L based on the molar amount of Cr of the main catalyst; and / or The mass ratio of the solvent to ethylene is 1:(0.5-1.5); and / or The molar ratio of Al in the promoter to Cr in the main catalyst is (40-60):1; and / or The molar ratio of the terminator to the Al in the promoter is (1.2-2.5):1; and / or The ratio of the flow rate of hydrogen to the amount of Cr in the main catalyst is 1 L / h: (1~10) mol.

4. The method for preparing alpha olefins by tetramerization of ethylene according to claim 1, characterized in that: The polymerization reaction temperature is 55-68° C., the polymerization reaction time is 15-45 min, and the polymerization reaction pressure is 3.2-4.8 MPa; and / or The pressure in the termination kettle is 3.5-4Mpa and the temperature is 55-68°C; and / or The flash evaporation pressure is 1.5-3 Mpa, and the flash evaporation temperature is 60-85°C.

5. The method for preparing alpha olefins by tetramerization of ethylene according to claim 1, characterized in that: The jet reactor is connected to an external circulation cooler via an external circulation pump.

6. The method for preparing alpha olefins by tetramerization of ethylene according to claim 1, characterized in that: It also includes a nitrogen tank and a terminator tank, wherein the nitrogen tank is connected to the jet reactor, and the terminator tank is connected to the termination reactor.

7. The method for preparing alpha olefins by tetramerization of ethylene according to claim 1, characterized in that: It also includes an ethylene recycling tank, which is connected to the deethylene tower and the flash tank respectively, and is also connected to the premixing kettle through the first compressor.

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