Olefin polymerization method and device

Abstract

The olefin polymerization method is characterized in that a liquid-phase refrigerant is introduced into a high-temperature reactor, a polymerization reaction environment with multiple temperature zones is created in a single reactor through the refrigerant, and active polymer particles shuttle back and forth between the high-temperature zone and the low-temperature zone, so that the condensed state structure of a product can be regulated and controlled; the high-performance polyolefin with remarkably improved processability and usability can be prepared by the method disclosed by the invention.

Description

Field of the Invention

[0001] The present invention belongs to the field of olefin polymerization, and particularly relates to an olefin polymerization method and apparatus. Background Art

[0002] It is known in the art that when olefin catalysts are in different temperature environments, the length of the molecular chains grown and the condensed state structure formed by the molecular chains are different, which will seriously affect the rigidity and toughness of the material. In order to give full play to the advantages of low-temperature catalysts in regulating the molecular weight, degree of branching, and chain entanglement of high-molecular-weight active chains, and to achieve uniform mixing at the molecular chain scale with low-molecular-weight active chains, it is necessary to solve the problem that low-temperature catalysts are not compatible with the process conditions of existing industrial plants.

[0003] Whether it is a double-reactor series process or a single-fluidized-bed process with a composite flow pattern, the reaction temperature can only be reduced to 60-70 °C, and it is impossible to break through the limit of the process heat removal requirement to create a low-temperature zone below 30 °C. Therefore, neither can the regulatory advantages of low-temperature catalysts in the multi-stage structure of polymers be exerted, nor can the problem that active chains do not have time to crystallize to form a large number of chain entanglements at high temperatures be solved, and the mixing of two polymer molecular chains at the reactor scale cannot be achieved.

[0004] It can be seen that how to create a low-temperature zone in a single reaction system and jointly construct a multi-temperature reaction environment with the original high-temperature region, so that low-temperature catalysts and conventional catalysts both have sufficient activity in the reactor, and promote the growth and mixing of the two active chains simultaneously, is the key to flexibly regulating the multi-stage structure of polyethylene and achieving uniform mixing of different polymers at the chain scale. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide an olefin polymerization method and apparatus. The present invention directly introduces a liquid-phase refrigerant into a high-temperature slurry or solution polymerization reactor, creates a multi-temperature polymerization reaction environment in a single reactor through the refrigerant, and the active polymer particles shuttle back and forth between the high-temperature zone and the low-temperature zone to regulate the product structure, and high-performance polyolefins with a wide molecular weight distribution can be produced.

[0006] The present invention first provides an olefin polymerization method: introducing a solvent, a reaction monomer, and a catalyst into a slurry or solution polymerization reaction system to carry out a polymerization reaction. At the same time, introducing at least one stream of liquid-phase refrigerant into the polymerization reaction system, the temperature of the introduced liquid-phase refrigerant being lower than the temperature of the polymerization reaction, creating a multi-temperature slurry or solution polymerization environment in the slurry or solution reaction system through the liquid-phase refrigerant, thereby polymerizing to produce high-performance polyolefins with a wide molecular weight distribution, wherein the multi-temperature slurry or solution polymerization environment is: the main body of the polymerization reaction is maintained in a main body temperature range, and at the same time, there is one or more low-temperature zones generated by the introduction of the liquid-phase refrigerant therein.

[0007] In some embodiments of the present invention, the liquid refrigerant is a mixture composed of one or more of alkanes with 3 to 7 carbon atoms and / or halogenated alkanes with no more than 7 carbon atoms.

[0008] In some alternative embodiments of the present invention, all or part of the liquid refrigerant is a component that can be vaporized at the polymerization reaction temperature. The vaporization of these vaporizable components can generate bubbles in the system. Therefore, on the one hand, the liquid refrigerant can form a low-temperature zone in the main reaction zone, and on the other hand, it can collide with polymer particles through bubbles. The two act together, and the active polymer particles shuttle back and forth between the high-temperature zone and the low-temperature zone, promoting the improvement of the polymerization product.

[0009] In some alternative embodiments of the present invention, the boiling point of the liquid refrigerant under the polymerization reaction pressure is higher than the polymerization reaction temperature, and the liquid refrigerant does not vaporize. The introduction of the liquid refrigerant forms a low-temperature zone in the main reaction zone. The active polymer particles shuttle back and forth between the high-temperature zone and the low-temperature zone, promoting the improvement of the polymerization product. At the same time, since the liquid refrigerant does not vaporize, gas-liquid separation can be omitted. In this way, preferably, the liquid refrigerant is the same as the solvent, so that part of the solvent can be taken out and cooled to the required temperature and then used as the liquid refrigerant.

[0010] In some embodiments of the present invention, the liquid refrigerant is injected into the polymerization reaction system in a single stream form.

[0011] In some other embodiments of the present invention, the liquid refrigerant is injected into the polymerization reaction system in a multi-stream form.

[0012] In some embodiments of the present invention, the main temperature T0 of the multi-temperature zone polymerization environment and the temperature T of each low-temperature zone d both satisfy (T0 - T d ) / T0 = 0.01 to 2, preferably 0.2 - 1.

[0013] In some embodiments of the present invention, the catalyst is a single-site catalyst and / or a multi-site catalyst.

[0014] In some embodiments of the present invention, the single-site catalyst is composed of a main catalyst and a co-catalyst. Among them, the main catalyst is selected from one or more of Ziegler-Natta catalysts, metallocene catalysts, non-metallocene catalysts, chromium-based catalysts, late transition metal catalysts, and early transition metal catalysts, and the co-catalyst is selected from one or more of alkylaluminums, alkylaluminoxanes, modified alkylaluminoxanes, and boranes.

[0015] In some embodiments of the present invention, the multi-active center catalyst is composed of a main catalyst and a co-catalyst, wherein the main catalyst is selected from Ziegler-Natta / metallocene composite catalysts, metallocene / metallocene composite catalysts, metallocene / post-transition metal composite catalysts, and the same catalyst with different active centers.

[0016] In some embodiments of the present invention, the reaction monomer of the polymerization reaction is one or more of α-olefins having 2 to 10 carbon atoms.

[0017] In some embodiments of the present invention, the main reaction temperature of the polymerization reaction is -10 to 160 °C, and the reaction pressure is 0.1 to 10 MPa.

[0018] In some embodiments of the present invention, the solvent of the polymerization reaction system is selected from alkanes having less than 12 carbon atoms and their mixtures and / or aromatic hydrocarbons having less than 12 carbon atoms and their mixtures.

[0019] In some embodiments of the present invention, the polymerization reaction system is a slurry polymerization system.

[0020] In some embodiments of the present invention, the polymerization reaction system is a solution polymerization system.

[0021] The present invention further provides an apparatus for implementing the above-mentioned olefin polymerization method, specifically including:

[0022] A refrigerant tank (1) for storing liquid-phase refrigerant, and a refrigerant discharge port is provided at the bottom of the refrigerant tank;

[0023] A refrigerant pump (2) for transporting liquid-phase refrigerant, and the inlet of the refrigerant pump is connected to the refrigerant tank through a pipeline and a valve;

[0024] A heat exchanger (3) for adjusting the feeding temperature of liquid-phase refrigerant, and the inlet of the heat exchanger is connected to the outlet of the refrigerant pump through a pipeline and a valve;

[0025] A reactor (4) for olefin polymerization reaction, at least one liquid-phase refrigerant injection port, at least one gas discharge port, a product discharge port, a reaction monomer injection port, and a catalyst injection port are provided on the reactor, and the liquid-phase refrigerant injection port is connected to the outlet of the heat exchanger through a pipeline and a valve.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] In the present invention, a liquid refrigerant is introduced into a high-temperature reactor. By absorbing heat when the liquid refrigerant enters the reactor, a low-temperature zone is created within the high-temperature reactor, and a multi-temperature zone polymerization reaction environment is constructed within a single reactor. Active polymer particles shuttle back and forth between the low-temperature zone and the high-temperature zone for monomer polymerization, enabling the regulation of the product's condensed state structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is a schematic diagram of an olefin polymerization apparatus provided by the present invention.

[0029] Wherein: 1 - refrigerant tank; 2 - refrigerant pump; 3 - heat exchanger; 4 - reactor EXAMPLES

[0030] The following will describe the embodiments of the present invention in detail. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0031] The following methods are used to test the structure or properties of the polyolefins produced in the examples:

[0032] High-temperature gel permeation chromatography is used to test the molecular weight and its distribution index of the polyolefin.

[0033] A rotational rheometer is used to test the shear storage modulus of the polyolefin. The smaller the initial storage modulus, the lower the degree of chain entanglement. The rheological test temperature is 160 °C.

[0034] It should be noted that the amounts of the catalyst, cocatalyst, solvent, and reaction monomer in each example and each comparative example are exactly the same.

[0035] Example 1

[0036] In this example, MgCl2-supported TiCl4 is used as the catalyst, triethylaluminum is used as the cocatalyst, isopentane is used as the solvent, ethylene is used as the reaction monomer, and liquid-phase propane is used as the refrigerant.

[0037] Isopentane and liquid-phase propane are added to the reactor. The propane is injected into the reactor in a single stream at a injection rate of 0.1 m / s and a propane feed temperature of 30 °C. A slurry polymerization reaction is carried out at a temperature of 160 °C and a pressure of 2 MPa, and the temperature of the low-temperature zone is 120 °C. After the reaction, the resulting polymer slurry enters the post-treatment section to recover the inert liquid and the reaction solvent, and finally a dry olefin polymerization product is obtained. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0038] Example 2

[0039] In this example, MgCl₂-supported TiCl₄ is used as the catalyst, triethylaluminum is used as the cocatalyst, n-hexane is used as the solvent, ethylene is used as the reaction monomer, and liquid-phase isobutane is used as the refrigerant.

[0040] N-hexane and liquid-phase isobutane are added to the reactor. Isobutane is injected into the reactor in three streams at a rate of 1 m / s, and the feed temperature of isobutane is 20 °C. A slurry polymerization reaction is carried out at a temperature of 120 °C and a pressure of 0.8 MPa, and the temperature in the low-temperature zone is 85 °C. After the reaction, the resulting polymer slurry enters the post-treatment section to recover the inert liquid and the reaction solvent, and finally a dry olefin polymerization product is obtained. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0041] Example 3

[0042] In this example, MgCl₂-supported TiCl₄ is used as the catalyst, triethylaluminum is used as the cocatalyst, n-heptane is used as the solvent, ethylene is used as the reaction monomer, and liquid-phase isopentane is used as the refrigerant.

[0043] N-heptane and liquid-phase isopentane are added to the reactor. Isopentane is injected into the reactor in two streams at a rate of 4 m / s, and the feed temperature of isopentane is 0 °C. A slurry polymerization reaction is carried out at a temperature of 100 °C and a pressure of 0.3 MPa, and the temperature in the low-temperature zone is 70 °C. After the reaction, the resulting polymer slurry enters the post-treatment section to recover the inert liquid and the reaction solvent, and finally a dry olefin polymerization product is obtained. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0044] Example 4

[0045] In this example, MgCl₂-supported TiCl₄ is used as the catalyst, triethylaluminum is used as the cocatalyst, toluene is used as the solvent, ethylene is used as the reaction monomer, and liquid-phase n-hexane is used as the refrigerant.

[0046] Toluene and liquid-phase n-hexane are added to the reactor. N-hexane is injected into the reactor in a single stream at a rate of 6 m / s, and the feed temperature of n-hexane is -10 °C. A slurry polymerization reaction is carried out at a temperature of 100 °C and a pressure of 0.1 MPa, and the temperature in the low-temperature zone is 60 °C. After the reaction, the resulting polymer slurry enters the post-treatment section to recover the inert liquid and the reaction solvent, and finally a dry olefin polymerization product is obtained. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0047] Example 5

[0048] In this example, MgCl₂-supported TiCl₄ is used as the catalyst, triethylaluminum is used as the cocatalyst, n-hexane is used as the solvent, ethylene is used as the reaction monomer, and liquid-phase 2-fluoropropane is used as the refrigerant.

[0049] n-Hexane and liquid-phase 2-fluoropropane were added to the reactor. The 2-fluoropropane was divided into two streams and injected into the reactor at a spraying rate of 8 m / s. The feeding temperature of 2-fluoropropane was -20°C. A slurry polymerization reaction was carried out at a temperature of 80°C and a pressure of 0.2 MPa, and the temperature of the low-temperature zone was 35°C. After the reaction, the obtained polymer slurry entered the post-treatment section to recover the inert liquid and the reaction solvent, and finally a dried olefin polymerization product was obtained. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0050] Comparative Example 1

[0051] Differing from Example 1, propane was not added to the reactor, and the remaining operating conditions were the same. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0052] Comparative Example 2

[0053] Differing from Example 2, isobutane was not added to the reactor, and the remaining operating conditions were the same. The relevant characterization and performance test results of the obtained product are shown in Table 1.

[0054] Table 1 Test results of the polyethylene products finally obtained in Examples 1-5 and Comparative Examples 1-2

[0055]

[0056]

[0057] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A process for olefin polymerization, characterized in that, A solvent, a reaction monomer, and a catalyst are introduced into a slurry or solution polymerization reaction system to carry out a polymerization reaction. At the same time, at least one stream of liquid refrigerant is introduced into the polymerization reaction system, and the temperature of the introduced liquid refrigerant is lower than the temperature of the polymerization reaction. A multi-temperature zone slurry or solution polymerization environment is created in the slurry or solution reaction system through the liquid refrigerant, so as to polymerize and produce a high-performance polyolefin product with a wide molecular weight distribution. The multi-temperature zone slurry or solution polymerization environment is as follows: the main body of the polymerization reaction is maintained in a main body temperature range, and at the same time, one or more low-temperature zones are present therein due to the introduction of the liquid refrigerant.

2. The method according to claim 1, wherein The liquid refrigerant is a mixture composed of one or more of alkanes with 3-7 carbon atoms and / or halogenated alkanes with no more than 7 carbon atoms.

3. The method according to claim 1, wherein The liquid refrigerant is sprayed into the polymerization reaction system in a single stream form.

4. The method according to claim 1, wherein The liquid refrigerant is sprayed into the polymerization reaction system in a multi-stream form.

5. The method according to claims 1 and 4, characterized in that, The main body temperature T0 of the multi-temperature zone polymerization environment and the temperatures T of each low-temperature zone d both satisfy (T0 - T d ) / T0 = 0.01 to 2, preferably 0.2 - 1.

6. The method according to claim 1, characterized in that, The catalyst is a single-site catalyst and / or a multi-site catalyst.

7. The method according to claim 1, characterized in that, The reaction monomer of the polymerization reaction is one or more of α-olefins with 2-10 carbon atoms.

8. The method according to claim 1, characterized in that The main reaction temperature of the polymerization reaction is -10 - 160 °C, and the reaction pressure is 0.1 - 10 MPa.

9. The method according to claim 1, characterized in that, The solvent of the polymerization reaction system is selected from alkanes with less than 12 carbon atoms and their mixtures and / or aromatic hydrocarbons with less than 12 carbon atoms and their mixtures.

10. An apparatus for implementing the olefin polymerization method according to claim 1, characterized in that, It includes: A refrigerant tank (1) for storing the liquid refrigerant, and a refrigerant discharge port is provided at the bottom of the refrigerant tank; A refrigerant pump (2) for transporting the liquid refrigerant, and the inlet of the refrigerant pump is connected to the refrigerant tank through pipelines and valves; A heat exchanger (3) for adjusting the feed temperature of the liquid refrigerant, and the inlet of the heat exchanger is connected to the outlet of the refrigerant pump through pipelines and valves; A reactor (4) for olefin polymerization, and at least one liquid refrigerant injection port, at least one gas discharge port, a product discharge port, a reaction monomer injection port, and a catalyst injection port are provided on the reactor. The liquid refrigerant injection port is connected to the outlet of the heat exchanger through pipelines and valves.

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