A method and device for olefin polymerization with alternating environments

Abstract

The present invention discloses a method and apparatus for olefin polymerization with alternating environments, belonging to the field of olefin polymerization. The present invention utilizes electromagnetic control and other means to position an olefin polymerization reactor in different olefin polymerization environments, enabling switching between olefin copolymerization and homopolymerization, or between different copolymerization reactions, as needed. The olefin polymerization environments include, but are not limited to, varying reaction temperatures, reaction pressures, or feedstock compositions. Furthermore, different types of reactors can be installed within the olefin polymerization reactor to create differentiated polymerization environments, enabling the production of a wider range of polyolefin product grades.

Description

Technical Field

[0001] The present invention relates to an olefin polymerization method and device, and in particular to an olefin polymerization method and device with alternating environments. Background Art

[0002] Polyolefins are a class of thermoplastic resins produced through the homopolymerization or copolymerization of olefin monomers. Due to their abundant raw materials, low cost, and ease of processing and molding, they are widely used in a variety of fields, including agriculture, packaging, electronics, and automotive, demonstrating significant research and economic value. Due to their diverse nature, the production of different polyolefin grades often requires distinct equipment and processes. Polymerization process configurations include kettle, tubular, tower, and fluidized bed reactors. From a technological perspective, factors such as reaction temperature, catalyst feed rate, and comonomer feed rate all influence the final product properties.

[0003] CN105859918A describes a butyl rubber polymerization method that uses periodic feeding of initiator amounts in a solution-type reactor to adjust the number average molecular weight and thus control the molecular weight distribution. CN104628904B describes the use of polymerization monomers and a condensing agent as circulating media to form polymerization reaction zones with different temperatures in a single fluidized bed reactor to produce highly branched, low-density, high-molecular-weight polyolefins and less branched, high-density, low-molecular-weight polyolefins. CN114075309A describes a method and system for controlling polyolefin properties by directly connecting a loop reactor and a fluidized bed reactor. By adjusting the ratio of recycled liquid and / or liquid material returned to the loop reactor and the fluidized bed, the concentration and temperature of the reaction materials in the two reactors in the polymerization reaction system are controlled, and the properties of the polyolefin products in the two reactors are controlled, thereby achieving control of the properties of the final product. However, these methods have a limited range of polyolefin property adjustment within the reactor. Furthermore, due to the limitations of the reactor types, switching between different types of reactors is difficult, which limits the production of polyolefins of different grades.

[0004] Therefore, in response to the above problems, this patent proposes an olefin polymerization method and device that can alternately change the polymerization environment. Summary of the Invention

[0005] The present invention provides an olefin polymerization method and apparatus with alternating environments. This method and apparatus can electromagnetically control the placement of an olefin polymerization reactor in different olefin polymerization environments, enabling switching between olefin copolymerization and homopolymerization, or between different copolymerization reactions. Furthermore, different types of reactors can be installed within the olefin polymerization reactor, creating differentiated polymerization environments and producing a wider range of polyolefin product grades.

[0006] Another embodiment of the present invention relates to an alternating environment olefin polymerization method, which is implemented based on an alternating environment olefin polymerization device, the device comprising: a track housing isolated from the external environment, a track disposed within the track housing, and an olefin polymerization reactor disposed on the track and movable along the track; the space within the track housing is divided into at least a first buffer zone, a high-temperature zone, a second buffer zone, and a low-temperature zone;

[0007] The method comprises the following steps:

[0008] S1, introduce sufficient inert gas into the track housing and then evacuate it, repeatedly removing moisture and residual air from the track housing;

[0009] S2, controls the high temperature zone and the low temperature zone to heat to the specified temperature;

[0010] S3, adding a catalyst, a co-catalyst, a condensing agent, and a molecular weight regulator into the olefin polymerization reactor, and introducing a feed gas into the first buffer zone or the second buffer zone. The feed gas will fill the required area space according to the opening and closing of the electromagnetic valve between the first buffer zone or the second buffer zone and other areas;

[0011] S4, controlling the olefin polymerization reactor to enter the high temperature zone, the low temperature zone, or repeatedly switching positions between the two reaction zones, thereby polymerizing to generate a polyolefin product;

[0012] Depending on the needs of the target product, the valve between the track housing and the feed gas cylinder can be opened or closed to allow or block some of the polymerization monomers from entering the track housing, or to allow feed gas to be introduced into the track housing at regular intervals. This allows for switching between olefin copolymerization and homopolymerization, or between different copolymerization reactions, and regulates the quality of the polyolefin. It is worth noting that the product removal port on the track housing is always closed, except when removing product from the olefin polymerization reactor.

[0013] In the present invention, the olefin polymerization reactor may further include other reactors therein to serve as carriers of the other reactors. Therefore, the olefin polymerization reactor described herein may include the open container itself, or may be a whole consisting of the open container and other reactors therein.

[0014] In some preferred embodiments of the present invention, the olefin polymerization reactor itself can serve as a reactor, a catalyst, a co-catalyst, a condensing agent and a molecular weight regulator are added to the olefin polymerization reactor, and the raw gas is introduced through the holes on the track shell of the first buffer zone or the second buffer zone to fill the corresponding part of the track shell, and the raw gas undergoes olefin polymerization reaction in the olefin polymerization reactor.

[0015] In some preferred embodiments of the present invention, the other reactors described in the olefin polymerization reactor can be a fluidized bed reactor, which is added to the fluidized bed reactor, and the catalyst, co-catalyst and molecular weight regulator are added to the fluidized bed reactor. The raw gas is introduced into the fluidized bed reactor through the holes on the track shell of the first buffer zone or the second buffer zone, and the catalyst and other particles are fluidized. At the same time, the gas is discharged through the holes on the track shell of the second buffer zone. The discharged gas is circulated into the fluidized bed reactor after heat exchange, condensation, gas-liquid separation and other operations, and the raw gas undergoes olefin polymerization reaction in the fluidized bed reactor.

[0016] In other preferred embodiments of the present invention, the other reactors in the olefin polymerization reactor may be reactors, which are added to the reactors, and catalysts, co-catalysts, molecular weight regulators and magnetons are added to the reactors; the raw gas is introduced through the holes on the track shell of the first buffer zone or the second buffer zone to fill the corresponding part of the track shell, and the raw gas undergoes olefin polymerization reaction in the reactor; the magnetons can rotate under the action of an external magnetic field to play a stirring role.

[0017] In the present invention, the temperature of the olefin polymerization reactor can be adjusted by a resistance wire. Optionally, for example, a first resistance wire and a second resistance wire are arranged in the high-temperature zone and the low-temperature zone respectively to adjust the ambient temperature inside the track housing. The residence time of the olefin polymerization reactor in different areas of the track housing can also be adjusted by adjusting the current and temperature.

[0018] In some embodiments of the present invention, on the one hand, according to the control of the first resistance wire and the second resistance wire by the computer, the temperatures of different parts of the high temperature zone and the low temperature zone at different times can be the same, thereby realizing olefin polymerization reaction under the same temperature conditions; on the other hand, according to the control of the first resistance wire and the second resistance wire by the computer, the temperatures of different parts of the high temperature zone and the low temperature zone at different times can be different, and by flexibly controlling the temperatures of the high temperature zone and the low temperature zone, olefin polymerization reaction under different temperature conditions can be realized.

[0019] In some embodiments of the present invention, a smooth transition of the olefin polymerization reaction temperature is achieved by controlling the temperature of the olefin polymerization reactor to the temperature required by the next reaction zone in the first buffer zone and the second buffer zone.

[0020] In some embodiments of the present invention, the magnitude of the current generated by the DC control power supply may be constant, and the olefin polymerization reactor moves at a constant speed within the track housing, maintaining the same residence time at each position of the track housing to achieve temperature control.

[0021] In other embodiments of the present invention, the magnitude of the current generated by the DC control power supply can be variable, and the olefin polymerization reactor moves at a variable speed in the track housing, adjusting the different residence times at various positions of the track housing to achieve temperature control.

[0022] In the present invention, the feed gas, catalyst, and molecular weight regulator can be added to the track housing before or during the reaction, either all at once or in batches. The addition location is not limited to the vent holes on the track housing; it can also be the product removal port on the track housing located in the buffer zone. In addition to the feed gas, catalyst, and molecular weight regulator, co-catalysts, condensing agents, inert gases, and the like can also be added to the track housing.

[0023] In the present invention, the gas atmosphere in the olefin polymerization reactor in the high temperature zone and the low temperature zone is different, and the specific atmosphere is related to the type and proportion of feed gas, the type and proportion of condensing agent, the temperature at the location, and the catalyst type.

[0024] In the present invention, the feed gas can be a single olefin monomer or at least two olefin monomers. Therefore, the feed gas can be used for both homopolymerization and copolymerization. It can produce high-density olefin polymer products; when used in copolymerization reactions, it can produce linear, low-density polyolefin products with a high degree of branching.

[0025] In some specific embodiments of the present invention, in the olefin polymerization reactor, the olefin monomer content is 0.5 to 90 mol%, preferably 4 to 88 mol%; the olefin monomer is selected from ethylene and / or at least one α-olefin having less than 18 carbon atoms; in some specific embodiments of the present invention, the α-olefin is selected from one α-olefin having 4 to 20 carbon atoms; the α-olefin is selected from propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene, preferably selected from 1-butene, 1-pentene, and 1-hexene.

[0026] In some specific embodiments of the present invention, when the olefin monomer is selected from ethylene and at least one α-olefin having less than 18 carbon atoms, the reaction pressure in the low temperature zone is 0.4 MPa to 10 MPa, and the temperature is controlled at 50°C to 75°C. The reaction temperature is relatively low, and it is easy to form a polyolefin product with more branches, lower density, and high molecular weight; the reaction pressure in the high temperature zone is 1 MPa to 12 MPa, and the temperature is controlled at 75°C to 110°C. The reaction temperature is relatively high, which is conducive to the formation of a polyolefin product with fewer branches, lower density, and low molecular weight.

[0027] In some specific embodiments of the present invention, in an olefin polymerization reactor, the condensing agent content is 0.2 to 50 mol%, preferably 3 to 45 mol%. The condensing agent is selected from ethane and / or saturated hydrocarbons having less than 8 carbon atoms. The saturated hydrocarbons are selected from propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane and other saturated C8 hydrocarbons, n-heptane, n-octane and other C7 and C8 alkanes or mixtures thereof. C5 and C6 saturated hydrocarbons are preferred.

[0028] In some embodiments of the present invention, the catalyst added to the olefin polymerization reactor is selected from one or more of a chromium-based catalyst, a Ziegler-Natta (ZN catalyst), a metallocene catalyst and a late transition metal catalyst.

[0029] Another embodiment of the present invention relates to an olefin polymerization apparatus with alternating environments, comprising:

[0030] A track housing isolated from the external environment, wherein the space within the track housing is divided into at least a first buffer zone, a high-temperature zone, a second buffer zone, and a low-temperature zone, wherein resistance wires are provided in both the high-temperature zone and the low-temperature zone to control the temperature of the zones;

[0031] A track is provided in the track housing, the track comprising a first track line and a second track line parallel to each other;

[0032] An olefin polymerization reactor is arranged on a track and can move along the track.

[0033] Preferably, the shape and length of the track housing can vary, such as circular, elliptical, spiral, or broken line. Preferably, the track is a closed-loop track, and the track housing is annular as a whole, with the interior space divided into a first buffer zone, a high-temperature zone, a second buffer zone, and a low-temperature zone connected end to end. The high-temperature zone and the low-temperature zone are both provided with heating devices to control the temperature of the zones.

[0034] The track housing is placed on a horizontal magnetic panel; the olefin polymerization reactor is connected to the first track line and the second track line of the closed-loop track through a first conductive bracket and a second conductive bracket, respectively, and the first track line and the second track line are respectively connected to two electrodes of a DC control power supply through wires; a conductive rod is connected between the first conductive bracket and the second conductive bracket; the first conductive bracket, the second conductive bracket, the first track line, the second track line, and the conductive rod are all made of conductive materials, the DC control power supply generates current along the conductive rod, and the current generates electromagnetic force under the action of the magnetic panel, thereby driving the olefin polymerization reactor to move along the track.

[0035] Preferably, a low-temperature first buffer zone solenoid valve is installed between the low-temperature zone and the first buffer zone, a low-temperature second buffer zone solenoid valve is installed between the low-temperature zone and the second buffer zone, a high-temperature first buffer zone solenoid valve is installed between the high-temperature zone and the first buffer zone, and a high-temperature second buffer zone solenoid valve is installed between the high-temperature zone and the second buffer zone. These solenoid valves are used to control whether the environments between connected zones are connected.

[0036] The method of the present invention uses homopolymerization and copolymerization systems using olefins as reaction raw materials. The terms "homopolymerization" and "copolymerization" used in the present invention refer to the polymerization system containing one polymerization monomer and at least two polymerization monomers, respectively.

[0037] The present invention has the beneficial effect of electromagnetically controlling the olefin polymerization reactor to locate in different olefin polymerization environments, thereby enabling switching between olefin copolymerization and homopolymerization reactions, or switching between different copolymerization reactions. Furthermore, different types of reactors can be installed in the olefin polymerization reactor to create differentiated polymerization environments, thereby producing a wider range of polyolefin product grades. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of an environment-alternating olefin polymerization device according to one embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the structure of the olefin polymerization reactor of the present invention;

[0040] Figure 3 A cross-sectional view of an olefin polymerization reactor according to the present invention taken along a vertical plane passing through the center of the circle;

[0041] The meanings of the reference numerals in the figures are as follows:

[0042] 1. First resistance wire, 2. Second resistance wire, 3. First track line, 4. Second track line, 5. Low-temperature first buffer zone solenoid valve, 6. High-temperature first buffer zone solenoid valve, 7. Low-temperature second buffer zone solenoid valve, 8. High-temperature second buffer zone solenoid valve, 9. Pressure gauge, 10. Temperature sensor, 11. Data cable, 12. Computer, 13. Vacuum pump, 14. Raw gas cylinder, 15. Inert gas, 16. Magnetic panel, 17. Valve, 18. Track housing, 19. Wire, 20. DC control power supply, 21. Olefin polymerization reactor, 22. First conductive bracket, 23. Second conductive bracket, 24. Conductive rod, 25. Product outlet, 26. Reactor flat non-conductive plate, 27. Reactor arc-shaped non-conductive plate. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the accompanying drawings.

[0044] like Figure 1 、 2 As shown in , 3, the olefin polymerization method includes the following steps.

[0045] S1, after introducing a sufficient amount of inert gas 15 into the device, evacuate the device, repeatedly removing moisture and residual air in the track housing 18;

[0046] S2, controlling the first resistance wire 1 and the second resistance wire 2 to heat the designated space to a designated temperature;

[0047] S3, adding catalyst, co-catalyst and molecular weight regulator into the olefin polymerization reactor 21, and introducing feed gas into the track housing 18. The feed gas will fill the designated space according to the opening and closing of the electromagnetic valve between the first buffer zone or the second buffer zone and other zones;

[0048] S4, controlling the DC control power supply 20, the olefin polymerization reactor 21 will enter the high temperature zone, the low temperature zone, or repeatedly switch between the two reaction zones to generate polyolefin products;

[0049] S5, taking out the polyolefin product from the olefin polymerization reactor 21;

[0050] In a preferred embodiment, an olefin polymerization unit such as Figure 1 and Figure 2 As shown, the track housing 18 is placed horizontally on the magnetic panel 16, and the olefin polymerization reactor 21 is connected to the first track line 3 and the second track line 4 on the track housing 18 through the first conductive bracket 22 and the second conductive bracket 23 respectively. The first track line 3 and the second track line 4 are respectively connected to the two electrodes of the DC control power supply 20 through the wire 19; the first track line 3 and the second track line 4 are connected by a non-conductive material to form a track, and the track housing 18 wraps the track line to form a closed area, which is divided into at least a first buffer zone, a low temperature zone, a second buffer zone, and a high temperature zone, all of which are distributed with a pressure gauge 9 and a temperature sensor 10; the first buffer zone and the corresponding area of ​​the low temperature zone are wound with a first resistance wire 1, and the second A second resistance wire 2 is wound around the corresponding areas of the buffer zone and the high-temperature zone, and the first resistance wire 1 and the second resistance wire 2 are connected to the computer 12 through a data line 11; a low-temperature first buffer zone solenoid valve 5 is installed between the low-temperature zone and the first buffer zone, a low-temperature second buffer zone solenoid valve 7 is installed between the low-temperature zone and the second buffer zone, a high-temperature first buffer zone solenoid valve 6 is installed between the high-temperature zone and the first buffer zone, and a high-temperature second buffer zone solenoid valve 8 is installed between the high-temperature zone and the second buffer zone; air holes are opened on the track housing 18 located in the first buffer zone and the second buffer zone, and are connected to their respective vacuum pumps 13 and raw gas cylinders 14 through valves 17; in addition, there are openable and closable product removal outlets 25 on the track housing 18 of the first buffer zone and the second buffer zone.

[0051] like Figure 1 、 Figure 2 and Figure 3 As shown, the shape and length of the enclosed area can be varied, such as circular, elliptical, spiral, straight, or broken line. Figure 1 As shown, its shape is a circular ring, the orbit line it forms is an annular closed-loop orbit line, and the closed area is an annular closed area.

[0052] like Figure 1 、 Figure 2 and Figure 3 As shown, the olefin polymerization reactor 21 is an open container located within the cavity of the track housing 18. The olefin polymerization reactor 21 is formed by connecting a first conductive bracket 22, a second conductive bracket 23, a conductive rod 24, a reactor flat non-conductive plate 26, and a reactor curved non-conductive plate 27. The reactor flat non-conductive plate 26 is connected to the first conductive bracket 22 and the second conductive bracket 23 and is coplanar. The edges of the reactor curved non-conductive plate 27 are aligned with the four edges of the reactor flat non-conductive plate 26, and the area enclosed by the reactor curved non-conductive plate 27 has an opening in the middle. A conductive rod 24 is connected between the first conductive bracket 22 and the second conductive bracket 23 and is located below the reactor flat non-conductive plate 26. A DC control power supply 20 generates current along the conductive rod 24. The current generates an electromagnetic force under the action of the magnetic panel 16, thereby driving the olefin polymerization reactor 21 to move along the track line. The instantaneous motion direction is perpendicular to the direction of the magnetic field generated by the conductive rod 24 and the magnetic panel 16.

[0053] To make the present invention easier to understand, the present invention will be further described in detail below with reference to the following examples. These examples are merely illustrative and are not intended to limit the scope of application of the present invention. The raw materials or components used in the present invention can be obtained by commercial routes or conventional methods unless otherwise specified.

[0054] Example 1

[0055] exist Figure 1In the illustrated environment-alternating olefin polymerization apparatus, ethylene / 1-butene / 1-hexene copolymerization is performed to produce polyolefins. The low-temperature second buffer zone solenoid valve 7 and the high-temperature first buffer zone solenoid valve 6 are closed, the high-temperature second buffer zone solenoid valve 8 is opened, a sufficient amount of inert gas 15 is introduced into the apparatus through the air holes in the second buffer zone, and vacuum is applied. This process is repeated several times to remove moisture and residual air from the circular track housing 18. After vacuum application, ethylene / 1-butene / 1-hexene feed gas having a unit content of 96.14 / 3.86 / 0 mol% is introduced into the circular track housing 18. A DC control power supply 20 controls the olefin polymerization reactor 21 to enter the second buffer zone, the high-temperature second buffer zone solenoid valve 8 is closed, and a computer 12 controls the second resistance wire 2 to adjust the temperature of the high-temperature zone and the second buffer zone to 80°C. ZN catalyst is then added to the olefin polymerization reactor 21, the high-temperature second buffer zone solenoid valve 8 is opened, and the olefin polymerization reactor 21 is rotated into the high-temperature zone. The high-temperature second buffer zone solenoid valve 8 is closed. The high-temperature first buffer zone solenoid valve 6 is opened to control the olefin polymerization reactor 21 to rotate into the first buffer zone, and then the high-temperature first buffer zone solenoid valve 6 is closed. The low-temperature second buffer zone solenoid valve 7 is closed, and the low-temperature first buffer zone solenoid valve 5 is opened to introduce ethylene / 1-butene / 1-hexene feed gas with a unit content of 97.3 / 0 / 2.7 mol% into the first buffer zone through the air holes on the first buffer zone. The low-temperature first buffer zone solenoid valve 5 is closed, and the computer 12 controls the first resistor 1 to adjust the low-temperature zone temperature and the first buffer zone temperature to 67°C and the reaction pressure to 2.4 MPa. The low-temperature first buffer zone solenoid valve 5 is opened to control the olefin polymerization reactor 21 to rotate into the low-temperature zone for olefin polymerization. In this way, the high-temperature zone and the low-temperature zone are continuously rotated and cycled, switching 5 times per hour. The obtained polyolefin product has a molecular weight distribution of 5.3, a molecular weight of 143825, a melt index of 0.892 g / 10 min, a crystallinity of 42.6%, a branching degree of 1.39 / 1000, and a density of 0.9140 g / cm 3 The impact mass of the falling dart is 154g.

[0056] Example 2

[0057] exist Figure 1In the illustrated environment-alternating olefin polymerization apparatus, ethylene / 1-butene / 1-hexene copolymerization is performed to produce polyolefins. The low-temperature second buffer zone solenoid valve 7 and the high-temperature first buffer zone solenoid valve 6 are closed, the high-temperature second buffer zone solenoid valve 8 is opened, a sufficient amount of inert gas 15 is introduced into the apparatus through the air holes in the second buffer zone, and vacuum is applied. This process is repeated several times to remove moisture and residual air from the circular track housing 18. After vacuum application, ethylene / 1-butene / 1-hexene feed gas having a unit content of 96.14 / 3.86 / 0 mol% is introduced into the circular track housing 18. A DC control power supply 20 controls the olefin polymerization reactor 21 to enter the second buffer zone, the high-temperature second buffer zone solenoid valve 8 is closed, and a computer 12 controls the second resistance wire 2 to adjust the temperature of the high-temperature zone and the second buffer zone to 80°C. ZN catalyst is then added to the olefin polymerization reactor 21, the high-temperature second buffer zone solenoid valve 8 is opened, and the olefin polymerization reactor 21 is rotated into the high-temperature zone. The high-temperature second buffer zone solenoid valve 8 is closed. The high-temperature first buffer zone solenoid valve 6 is opened to control the olefin polymerization reactor 21 to rotate into the first buffer zone, and then the high-temperature first buffer zone solenoid valve 6 is closed. The low-temperature second buffer zone solenoid valve 7 is closed, and the low-temperature first buffer zone solenoid valve 5 is opened to introduce ethylene / 1-butene / 1-hexene feed gas with a unit content of 97.3 / 0 / 2.7 mol% into the first buffer zone through the air holes on the first buffer zone. The low-temperature first buffer zone solenoid valve 5 is closed, and the computer 12 controls the first resistor 1 to adjust the low-temperature zone temperature and the first buffer zone temperature to 67°C and the reaction pressure to 2.4 MPa. The low-temperature first buffer zone solenoid valve 5 is opened to control the olefin polymerization reactor 21 to rotate into the low-temperature zone for olefin polymerization. In this way, the high-temperature zone and the low-temperature zone are continuously rotated and cycled, switching 15 times per hour. The obtained polyolefin product has a molecular weight distribution of 6.1, a molecular weight of 135380, a melt index of 0.92 g / 10 min, a crystallinity of 39.6%, a branching degree of 1.36 / 1000, and a density of 0.9040 g / cm 3 The impact mass of the dart is 129g.

[0058] Example 3

[0059] exist Figure 1In the illustrated alternating environment olefin polymerization apparatus, ethylene / 1-butene / 1-hexene copolymerization is performed to produce polyolefins. The low-temperature second buffer zone solenoid valve 7 and the high-temperature first buffer zone solenoid valve 6 are closed, the high-temperature second buffer zone solenoid valve 8 is opened, a sufficient amount of inert gas 15 is introduced into the apparatus through the air holes in the second buffer zone, and vacuum is applied. This process is repeated several times to remove moisture and residual air from the circular orbit housing 18. After vacuum application, ethylene / 1-butene / 1-hexene feed gas having a unit content of 93.74 / 0 / 2.98 mol% is introduced into the circular orbit housing 18. A DC control power supply 20 controls the olefin polymerization reactor 21 to enter the second buffer zone, the high-temperature second buffer zone solenoid valve 8 is closed, and the computer 12 controls the second resistance wire 2 to adjust the temperature of the high-temperature zone and the second buffer zone to 80°C. ZN catalyst is then added to the olefin polymerization reactor 21, the high-temperature second buffer zone solenoid valve 8 is opened, and the olefin polymerization reactor 21 is rotated into the high-temperature zone. The high-temperature second buffer zone solenoid valve 8 is closed. The high-temperature first buffer zone solenoid valve 6 is opened to control the olefin polymerization reactor 21 to rotate into the first buffer zone, and then the high-temperature first buffer zone solenoid valve 6 is closed. The low-temperature second buffer zone solenoid valve 7 is closed, and the low-temperature first buffer zone solenoid valve 5 is opened to introduce ethylene / 1-butene / 1-hexene feed gas with a unit content of 95.1 / 0 / 4.9 mol% into the first buffer zone through the air holes on the first buffer zone. The low-temperature first buffer zone solenoid valve 5 is closed, and the computer 12 controls the first resistor 1 to adjust the low-temperature zone temperature and the first buffer zone temperature to 67°C and the reaction pressure to 2.4 MPa. The low-temperature first buffer zone solenoid valve 5 is opened to control the olefin polymerization reactor 21 to rotate into the low-temperature zone for olefin polymerization. In this way, the high-temperature zone and the low-temperature zone are continuously rotated and cycled, switching 5 times per hour. The obtained polyolefin product has a molecular weight distribution of 6.7, a molecular weight of 144012, a melt index of 0.877 g / 10 min, a crystallinity of 40.3%, a branching degree of 1.21 / 1000, and a density of 0.9120 g / cm 3 , the impact mass of the falling dart is 149g.

[0060] Example 4

[0061] exist Figure 1In the illustrated environment-alternating olefin polymerization device, ethylene / 1-butene / 1-hexene copolymerization is performed to produce polyolefins. The low-temperature second buffer zone solenoid valve 7 and the high-temperature first buffer zone solenoid valve 6 are closed, the high-temperature second buffer zone solenoid valve 8 is opened, a sufficient amount of inert gas 15 is introduced into the device through the air holes in the second buffer zone, and vacuum is applied. The moisture and residual air in the circular orbit housing 18 are removed repeatedly several times. After vacuum application, ethylene / 1-butene / 1-hexene feed gas having a unit content of 93.74 / 3.28 / 2.98 mol% is introduced into the device. Simultaneously, hydrogen is introduced, with a hydrogen / feed gas ratio of 0.165. A DC control power supply 20 controls the olefin polymerization reactor 21 to enter the second buffer zone. The high-temperature second buffer zone solenoid valve 8 is closed, and the computer 12 controls the second resistance wire 2 to adjust the temperature of the high-temperature zone and the second buffer zone to 80°C. ZN catalyst is added to the olefin polymerization reactor 21. The high-temperature second buffer zone solenoid valve 8 is opened, and the olefin polymerization reactor 21 is controlled to rotate into the high-temperature zone. The high-temperature second buffer zone solenoid valve 8 is closed. The buffer zone solenoid valve 8 has a reaction pressure of 2.1 MPa, and an olefin polymerization reaction is carried out; the high-temperature first buffer zone solenoid valve 6 is opened, the olefin polymerization reactor 21 is controlled to rotate into the first buffer zone, and then the high-temperature first buffer zone solenoid valve 6 is closed. The low-temperature second buffer zone solenoid valve 7 is closed, and the low-temperature first buffer zone solenoid valve 5 is opened. Ethylene / 1-butene / 1-hexene feed gas with a unit content of 95.1 / 0 / 4.9 mol% is introduced into the first buffer zone through the air holes on the first buffer zone. At the same time, hydrogen is introduced with a hydrogen / feed gas ratio of 0.165. The low-temperature first buffer zone solenoid valve 5 is closed, and the computer 12 controls the first resistor 1 to adjust the temperature of the low-temperature zone and the first buffer zone to 67°C and the reaction pressure to 2.4 MPa. The low-temperature first buffer zone solenoid valve 5 is opened to control the olefin polymerization reactor 21 to rotate into the low-temperature zone for olefin polymerization reaction. In this way, the reactor rotates and cycles between the high-temperature zone and the low-temperature zone, switching five times per hour. The obtained polyolefin product has a molecular weight distribution of 6.4, a molecular weight of 104012, a melt index of 1.277 g / 10 min, a crystallinity of 38.4%, a branching degree of 1.01 / 1000, and a density of 0.9020 g / cm 3 , the impact mass of the falling dart is 94g.

[0062] Comparative Example 1

[0063] This comparative example employed the method disclosed in Example 5 of Chinese Patent No. 102190742A to prepare a polyolefin product using ethylene and 1-hexene as raw materials. The ethylene to 1-hexene ratio was 96.8 / 3.2 mol%, the reaction temperature was 80°C, and the reaction pressure was 2.1 MPa. The resulting polyolefin product had a molecular weight distribution of 2.1, a molecular weight of 136,427, a melt index of 0.892 g / 10 min, a crystallinity of 42.6%, a branching degree of 1.544 / 1000, and a density of 0.9350 g / cm 3The impact mass of the falling dart is 164g.

[0064] The characterization results of the olefin polymers prepared in Examples 1-4 and Comparative Example 1 above indicate that the products prepared in Examples 1-4 have a larger molecular weight distribution coefficient than the product in Comparative Example 1, indicating that the olefin polymers obtained using the method of the present invention have a wider molecular weight distribution. Furthermore, the density and crystallinity of the products prepared using the method of the present invention are lower than those of the product obtained in Comparative Example 1, further improving the tensile and tear resistance of the polymers. By adjusting the gas atmosphere within the high-temperature and low-temperature zones of the olefin polymerization reactor by varying the feed gas type and ratio, the condensing agent type and ratio, the location temperature, the catalyst type, and the switching frequency, the method of the present invention significantly improves the yield and performance of olefin polymers per unit time and per unit bed volume compared to the method disclosed in Comparative Example 1.

Claims

1. An olefin polymerization method with alternating environments, wherein the method is implemented based on an olefin polymerization device with alternating environments, the device comprising: A track housing isolated from the external environment, a track disposed in the track housing, and an olefin polymerization reactor disposed on the track and movable along the track; the space in the track housing is divided into at least a first buffer zone, a high-temperature zone, a second buffer zone, and a low-temperature zone; The method is characterized in that the method comprises the following steps: S1, introduce sufficient inert gas into the track housing and then evacuate it, repeatedly removing moisture and residual air from the track housing; S2, controls the high temperature zone and the low temperature zone to heat to the specified temperature; S3, adding a catalyst, a co-catalyst, a condensing agent, and a molecular weight regulator into the olefin polymerization reactor, and introducing a feed gas into the first buffer zone or the second buffer zone. The feed gas will fill the required area space according to the opening and closing of the electromagnetic valve between the first buffer zone or the second buffer zone and other areas; S4, controlling the olefin polymerization reactor to enter a high temperature zone, a low temperature zone, or repeatedly switch positions between the high temperature zone and the low temperature zone, thereby polymerizing to generate a polyolefin product; Among them, according to the needs of the target product, the valve between the track housing and the raw gas cylinder can be opened or closed to allow part of the polymerization monomer to enter or not enter the track housing, or the raw gas can be introduced into the track housing at regular intervals, thereby achieving switching between olefin copolymerization and homopolymerization or different copolymerization reactions and regulating the quality of polyolefins.

2. The method according to claim 1, characterized in that The gas atmosphere in the olefin polymerization reactor in the high temperature zone and the low temperature zone is different, and the specific atmosphere can be adjusted according to the type and proportion of raw gas, the type and proportion of condensing agent, the temperature at the location, and the catalyst type.

3. The method according to claim 1, characterized in that The feed gas can be one olefin monomer or at least two olefin monomers; in the olefin polymerization reactor, the molar content of the olefin monomer is 0.5 to 90 mol%, and is selected from ethylene and / or at least one α-olefin with less than 18 carbon atoms.

4. The method according to claim 1, wherein In the olefin polymerization reactor, the molar content of the condensing agent is 0.2 to 50 mol%, and the condensing agent is selected from ethane and / or saturated hydrocarbons with less than 8 carbon atoms.

5. The method according to claim 4, characterized in that The saturated hydrocarbon is selected from at least one of propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane and isohexane.

6. The method according to claim 1, characterized in that The reaction pressure in the low temperature zone is 0.4Mpa~10Mpa, and the temperature is controlled at 50℃~75℃. The reaction pressure in the high temperature zone is 1Mpa~12Mpa, and the temperature is controlled at 75℃~110℃.

7. The method according to claim 1, characterized in that The catalyst is selected from one or more of a chromium-based catalyst, a Ziegler-Natta catalyst, a metallocene catalyst and a late transition metal catalyst.

8. The method according to claim 1, characterized in that The track is a circular closed-loop track, and the track shell is circular as a whole. The space inside it is divided into a first buffer zone, a high-temperature zone, a second buffer zone and a low-temperature zone connected end to end. Heating devices are provided in the high-temperature zone and the low-temperature zone to control the temperature of the temperature zone.

9. An olefin polymerization device for implementing the method according to any one of claims 1 to 8, characterized in that include: The track housing is isolated from the external environment. The track housing is annular in shape. The space inside is divided into a first buffer zone, a high temperature zone, a second buffer zone and a low temperature zone connected end to end. The high temperature zone and the low temperature zone are both equipped with heating devices to control the temperature of the temperature zone. A track is provided in the track housing, the track comprising a first track line and a second track line parallel to each other; An olefin polymerization reactor is arranged on a track and can move along the track.

10. The olefin polymerization device according to claim 9, characterized in that: The track housing is placed on a horizontal magnetic panel; the olefin polymerization reactor is connected to the first track line and the second track line of the closed-loop track through a first conductive bracket and a second conductive bracket, respectively, and the first track line and the second track line are respectively connected to two electrodes of a DC control power supply through wires; a conductive rod is connected between the first conductive bracket and the second conductive bracket; the first conductive bracket, the second conductive bracket, the first track line, the second track line, and the conductive rod are all made of conductive materials, the DC control power supply generates current along the conductive rod, and the current generates electromagnetic force under the action of the magnetic panel, thereby driving the olefin polymerization reactor to move along the track.

11. The olefin polymerization device according to claim 9 or 10, characterized in that: A low-temperature first buffer zone solenoid valve is installed between the low-temperature zone and the first buffer zone, a low-temperature second buffer zone solenoid valve is installed between the low-temperature zone and the second buffer zone, a high-temperature first buffer zone solenoid valve is installed between the high-temperature zone and the first buffer zone, and a high-temperature second buffer zone solenoid valve is installed between the high-temperature zone and the second buffer zone.

Images