Production device and production method for preparing alpha-olefin and application of alpha-olefin

Abstract

The invention belongs to the technical field of chemical production, and particularly relates to a production device and method for preparing alpha-olefin and application of the alpha-olefin. The invention provides a production device for preparing alpha-olefin, and also provides a production method for preparing alpha-olefin by using the production device, which comprises the following steps: polymerization reaction, flash evaporation, reaction termination and separation and purification: the boiling range of a solvent used in the polymerization reaction is 120-287 DEG C, and the flash point of the solvent is 25-135 DEG C. The invention also provides an application of the production device or the production method in preparation of alpha-hexene and / or alpha-octene. According to the method, the solvent with the boiling range and the flash point in the specific range is selected, the dissolving capacity of the polymerization product prepared through polymerization reaction is higher, the polymerization product is fully dissolved in the solvent, cannot be attached to a reaction device and a connecting pipeline and cannot be blocked, heat transfer is facilitated, energy consumption is effectively reduced, the preparation process is simple, continuous production can be conducted, and the method is suitable for industrial production. And the labor cost is effectively reduced.

Description

Technical Field

[0001] The present application belongs to the field of chemical production technology, and in particular relates to a production device, a production method and an application thereof for preparing α-olefins. Background Art

[0002] α-olefin is a terminal olefin product, an important comonomer for the production of high-performance polyolefins, and an important raw material for the production of high-end lubricants, plasticizers, surfactants and other fine chemicals. In recent years, the demand for α-olefins has grown rapidly, and the import volume has increased significantly. The efficient production of α-olefins is of great significance.

[0003] At present, the mainstream production processes of α-olefins include: ethylene polymerization, coal-to-liquid product extraction, Fischer-Tropsch synthesis oil extraction and separation, and paraffin cracking. Among them, ethylene polymerization has the advantages of high linearization and good product quality, and has become the most important industrial production method. In the existing technology, the method of preparing α-hexene and α-octene by ethylene polymerization still has the problems of high labor cost, high energy consumption and easy pipeline blockage.

[0004] Therefore, it has become an urgent problem to be solved by those skilled in the art to develop a production device, a production method and an application thereof for preparing α-olefins to solve the technical defects of the prior art, namely, high labor cost, high energy consumption and easy clogging of pipelines in the production process of α-olefins. Summary of the invention

[0005] Based on this, it is necessary to provide a production device, production method and application of α-olefins in view of the technical defects of the existing α-olefin production process, such as high labor cost, high energy consumption and easy clogging of pipelines.

[0006] The present application provides a production device for preparing α-olefins, the production device comprising: a raw material pretreatment unit, a reaction unit, a termination reaction unit and a separation and purification unit, wherein the raw material pretreatment unit, the reaction unit, the termination reaction unit and the separation and purification unit are connected in sequence;

[0007] The reaction unit comprises: a reactor and a flash evaporator. After the reaction in the reactor is completed, the olefin raw material enters the flash evaporator to be evaporated and then re-enters the reactor.

[0008] In one embodiment, the raw material pretreatment unit is used for dehydration purification and / or deoxygenation purification of each reaction raw material.

[0009] In one embodiment, the separation and purification unit includes: a filtering section, a first solvent purification section and a second solvent purification section. After the reaction mixture system of the termination reaction unit is filtered to remove solid impurities, the reaction product α-olefin is removed through the first solvent purification section, and then the reaction solvent is dehydrated and / or deoxygenated and / or impurity-removed through the second solvent purification section. The outlet of the second solvent purification section is connected to the reaction unit.

[0010] The present application also provides a production method for preparing α-olefins using any of the production devices described above, wherein the production method is:

[0011] Step 1, polymerization reaction: ethylene, catalyst, auxiliary agent and solvent are purified and mixed, and polymerization reaction occurs to obtain the first product;

[0012] Step 2, flash evaporation: flash evaporation of the first product, separation of gaseous ethylene for re-polymerization, and the resulting liquid mixture as the second product;

[0013] Step 3, reaction termination: the second product is mixed with a terminator to obtain a third product;

[0014] Step 4, separation and purification: the third product is separated and purified to obtain an α-olefin product;

[0015] Wherein, the boiling range of the solvent is 120°C to 287°C, and the flash point of the solvent is 25°C to 135°C.

[0016] In one embodiment, the boiling range of the solvent is 140°C to 220°C, and the flash point of the solvent is 30°C to 80°C.

[0017] In one embodiment, the solvent comprises, by mass percentage, 1-30% normal alkanes, 35%-70% isoalkanes and 35-70% cycloalkanes.

[0018] In one embodiment, the solvent includes, by mass percentage, 5-20% normal alkanes, 35-50% isoalkanes and 35-50% cycloalkanes.

[0019] In one embodiment, the normal alkane is selected from any one or more of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and n-hexadecane;

[0020] and / or, the isoalkane is selected from any one or more of isononane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane and isohexadecane;

[0021] And / or, the cycloalkane is selected from any one or more of trimethylcyclohexane, tetramethylcyclohexane, ethylisopropylcyclohexane, dipropylcyclohexane, propylbutylcyclohexane, dimethyldiisopropylcyclohexane, isobutylisopentylcyclohexane and dimethyldibutylcyclohexane.

[0022] In one embodiment, the normal alkane is selected from any one or more of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane and n-tetradecane;

[0023] And / or, the isoalkane is selected from any one or more of isononane, isodecane, isoundecane and isododecane;

[0024] And / or, the cycloalkane is selected from any one or more of trimethylcyclohexane, tetramethylcyclohexane, ethylisopropylcyclohexane, dipropylcyclohexane, propylbutylcyclohexane and dimethyldiisopropylcyclohexane.

[0025] In one embodiment, the normal alkane is selected from any one or more of n-nonane, n-decane, n-undecane and n-dodecane.

[0026] In one embodiment, the terminator is selected from any one or more of ethanol, propanol, butanol, octanol, isopropanol, isooctyl alcohol, isooctyl acid, ethylene glycol, glycerol and water;

[0027] And / or, the feeding amount of the terminator is 5% to 70% of the feeding amount of the catalyst.

[0028] In one embodiment, the terminator is selected from any one or more of ethanol, isooctyl alcohol, isooctyl acid, ethylene glycol, glycerol and water.

[0029] In one embodiment, the terminator is water.

[0030] In one embodiment, the catalyst comprises: a main catalyst and a co-catalyst;

[0031] The main catalyst is a chromium or titanium catalyst coordinated with a monodentate or multidentate ligand of any one or more structures of PNP, PCCP, PNSiP, NP, NPN and NNN known for olefin polymerization;

[0032] For example, the chromium or titanium catalysts coordinated by the ligands of the following structures:

[0033]

[0034] Wherein, R1 and R1' are selected from alkyl, alkoxy, aryl, amino, mercapto, hydrogen atom or halogen-containing substituents. R2, R3, R4 and R4' are selected from alkyl, alkoxy, aryl, amino, mercapto or hydrogen atom; or catalysts disclosed in Example 1 and Example 2 of patent CN116553993A.

[0035] The co-catalyst is selected from one or more of alkylaluminoxane, a mixture of alkylaluminum and borate, modified alkylaluminoxane and halogenated alkylaluminum.

[0036] In one embodiment, the molar ratio of the co-catalyst metal Al to the main catalyst metal Cr or Ti is (300-600):1 in molar parts.

[0037] In one embodiment, the molar ratio of the co-catalyst metal Al to the main catalyst metal Cr or Ti is (400-500):1 in molar parts.

[0038] In one embodiment, the auxiliary agent is selected from any one or more of hydrogen, halogenated hydrocarbons, alkyl aluminum, alkyl lithium and alkyl zinc.

[0039] In one of the embodiments, in step 1, the reaction temperature of the polymerization reaction is 30° C. to 150° C., and the reaction pressure of the polymerization reaction is 2 MPa to 10 MPa.

[0040] In one of the embodiments, in step 1, the reaction temperature of the polymerization reaction is 30° C. to 100° C., and the reaction pressure of the polymerization reaction is 3 MPa to 6 MPa.

[0041] In one embodiment, in step 1, the reaction temperature of the polymerization reaction is 40°C to 80°C.

[0042] The present application also provides an application of a production device comprising any one of the above or a production method comprising any one of the above in the preparation of α-hexene and / or α-octene.

[0043] In summary, the present application provides a production device for preparing α-olefins, and the present application also provides a production method for preparing α-olefins using the above production device, which is: polymerization reaction, flash evaporation, reaction termination and separation and purification: wherein the boiling range of the solvent used in the polymerization reaction is 120°C to 287°C, and the flash point of the solvent is 25°C to 135°C. The present application also provides an application of the above production device or the above production method in the preparation of α-hexene and / or α-octene. In the technical scheme provided by the present application, by selecting a mixed solvent with a specific range of boiling range and flash point, the dissolving ability of the polymer product obtained by the polymerization reaction is stronger, the polymer product is fully dissolved in the solvent and will not adhere to the reaction device and the connecting pipeline, will not be blocked, and is also conducive to heat transfer, thereby effectively reducing energy consumption, the preparation process is simple, the mixed solvent can be recycled and reused without re-separation, and continuous production can be carried out, effectively reducing labor costs. A production device, production method and application of α-olefins provided by the present application solve the technical defects of high labor cost, high energy consumption and easy blockage of reactors and reaction pipelines in the prior art of the production process of α-olefins, and also reduce the content of ethylene in the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0045] Figure 1 A schematic diagram of a production device for preparing α-olefins in the technical solution provided in the embodiment of the present application;

[0046] Figure 2 A schematic flow chart of a production method for preparing α-olefins in the technical solution provided in the embodiment of the present application;

[0047] Figure 3 This is a schematic structural diagram of a second solvent purification section of a separation and purification unit in a production device for preparing α-olefins provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application provide a production device, a production method and applications of α-olefins, which are used to solve the technical defects of the prior art in the production process of α-olefins, such as high labor cost, high energy consumption and easy clogging of pipelines.

[0049] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0050] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0051] 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 this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0052] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0054] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0055] See also Figure 1 The embodiment of the present application provides a production device for preparing α-olefins, including: a raw material pretreatment unit, a reaction unit, a termination reaction unit and a separation and purification unit, wherein the raw material pretreatment unit, the reaction unit, the termination reaction unit and the separation and purification unit are connected in sequence; the reaction unit includes: a reactor and a flash evaporator, and after the reaction in the reactor is completed, the olefin raw material enters the flash evaporator to evaporate and re-enters the reactor.

[0056] In the production device provided in the embodiment of the present application, after the mixed system in the reactor after the reaction is flash-evaporated by a flash evaporator, the unreacted olefin raw material can be returned to the reactor for secondary utilization, which, on the one hand, avoids the waste of olefin raw materials and effectively reduces the production cost; on the other hand, separating the unreacted olefin raw materials in advance can simplify the structure of the separation and purification unit, which is more helpful to further reduce the production cost.

[0057] In the process of actual application, on the basis of ensuring that the polymerization reaction can be carried out efficiently, the design requirements of reactor cost-effectiveness and easy management and maintenance of the reactor are taken into account. In the technical solution provided in the embodiment of the present application, the reactor is a loop reactor or a kettle reactor.

[0058] Further optimize the technical scheme, in the technical scheme provided in the embodiment of the present application, the raw material pretreatment unit is used for dehydration purification and / or deoxygenation purification of each reaction raw material. Through the raw material pretreatment unit, each reaction raw material used is purified to improve the purity of each reaction raw material, and further effectively improve the yield. In the process of actual application, through the dehydration purification and / or deoxygenation purification of the raw material pretreatment unit, the water and oxygen content of each reaction raw material are less than 1ppm.

[0059] In one embodiment, the separation and purification unit includes: a filtering section, a first solvent purification section and a second solvent purification section. After the reaction mixture system of the termination reaction unit is filtered to remove solid impurities, the reaction product α-olefin is removed through the first solvent purification section, and then the reaction solvent is dehydrated and / or deoxygenated and / or impurity-removed through the second solvent purification section. The outlet of the second solvent purification section is connected to the reaction unit.

[0060] During the operation of the separation and purification unit, first, the reaction mixture passes through the filtration section to remove solid impurities, then the impurity-free liquid mixture is heated for the first time in the first solvent purification section to collect the product α-olefins, and the remaining liquid mixture (including: polymerization products above C10 and solvent) is heated for the second time in the second solvent purification section to obtain a recyclable solvent, at which point the solvent can flow back to the reaction unit for repeated use.

[0061] In order to effectively improve the polymerization reaction yield and production capacity, the recycled solvent obtained by the second solvent purification unit can be purified by dehydration and / or deoxygenation and / or impurity removal again before entering the reaction unit for reaction.

[0062] Accordingly, a solution detection module may also be provided. If the solution entering the reaction unit does not meet the preset conditions, the unit may be shut down or the solution may be replenished or replaced, thereby effectively ensuring that the polymerization reaction can proceed continuously and efficiently and preventing the reaction from shutting down. At the same time, it also reduces dependence on manpower and achieves the design goal of reducing costs and increasing efficiency.

[0063] See here Figure 3 In order to better realize the recycling of solvents and improve the purity of solvents circulating into the polymerization reaction, in the technical solution provided by this application, the second solvent purification unit includes: adsorption or hydrofining to remove olefins and dehydration, deoxygenation and impurity removal, wherein the olefin content is ≤1ppm, and the water and oxygen contents are both ≤1ppm. Among them, the olefin removal method can adopt any combination of adsorption or hydrofining processes, and the adsorbent includes but is not limited to at least one of modified activated carbon, β-type molecular sieve, X-type molecular sieve, A-type molecular sieve, Y-type zeolite and MOF materials; the hydrofining agent includes but is not limited to at least one of a nickel-based catalyst, a platinum-based catalyst, and a palladium-based catalyst, specifically for the removal of olefins in solvents and C10 and above products; the dehydration, deoxygenation and impurity removal method can be removed by adsorbents, and the adsorbents include dehydration adsorbents and deoxygenation adsorbents, specifically for the removal of water and oxygen in solvents and C10 and above products after the removal of olefins. The solvent and C10 and above product recycling section includes a buffer tank and an external solvent discharge port. The former is used to add the mixed solution into the reactor for recycling via a pump, and the latter is used to discharge the solvent regularly.

[0064] See here Figure 2 The present application also provides a production method for preparing α-olefins using the above-mentioned production device, which is:

[0065] Step 1, polymerization reaction: ethylene, catalyst, auxiliary agent and solvent are purified and mixed, and polymerization reaction occurs to obtain the first product;

[0066] Step 2, flash evaporation: flash evaporation of the first product, separation of gaseous ethylene and re-polymerization reaction, and the resulting liquid mixture is the second product;

[0067] Step 3, reaction termination: the second product is mixed with a terminator to obtain a third product;

[0068] Step 4, separation and purification: the third product is separated and purified to obtain an α-olefin product;

[0069] The boiling range of the solvent is 120°C to 250°C, and the flash point of the solvent is 25°C to 100°C.

[0070] In the production method provided in the embodiment of the present application, by specifically selecting the boiling range and flash point of the solvent, firstly, the selected solvent has a stronger solubility for the polymerized olefins generated by the polymerization reaction, and the polymer can be mostly or even completely dissolved in the solvent, so that the polymerization reaction reactor and the connecting pipelines between the steps are rarely attached with polymers, and the polymerization reaction products will not block the reactor or pipelines, thereby ensuring that the entire production process can be carried out continuously and improving the production capacity. At the same time, there is no need to rely on manpower to deal with the blockage problem, reducing manpower loss and further reducing costs; secondly, since the solvent has a stronger solubility for the polymerization reaction product, the product separation and solvent recycling can be achieved by simple filtration and heating, and the separation and purification process is simple and easy to operate, without relying on complex equipment and treatment processes, further reducing the production cost; thirdly, the strong solubility of the polymer in the solvent is conducive to heat transfer during the polymerization reaction in the reactor, reducing thermal consumption and further reducing production costs.

[0071] To further optimize the technical solution and explore solvents with stronger solubility for the polymerization product, when the boiling range of the solvent is 140℃~220℃ and the flash point of the solvent is 30℃~80℃, it has better solubility for polymer olefins.

[0072] According to the characteristics of the polymerization reaction occurring in the technical solution of the present application, on the basis of ensuring that the solvent can fully dissolve the reaction product, at the same time, better utilization of the by-products produced by the polymerization reaction is made. The by-products of the polymerization reaction are used as solvents, which can not only reduce the amount of solvent added and reduce costs, but also simplify the separation and purification process. Taking into account the aforementioned solubility requirements and making full use of the reaction by-products as solvents, in the technical solution provided in the embodiment of the present application, the solvent includes, by mass percentage: 0-20% normal alkanes, 35%-70% isoalkanes and 35-70% cycloalkanes.

[0073] In the actual production process, ensure that the solvent dissolves the polymerization reaction product well to prevent management blockage and the inability to stir the reactor, and ensure that the content of normal alkanes in the solvent is less than 20%. If the content of normal alkanes is greater than 20%, isoalkanes and / or cycloalkanes can be added in time, or a portion of the normal alkanes can be discharged, or both methods can be carried out simultaneously.

[0074] To further optimize the technical solution, the n-alkanes are selected from any one or more of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and n-hexadecane; and / or the isoalkanes are selected from any one or more of isononane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane and isohexadecane; and / or the cycloalkanes are selected from any one or more of trimethylcyclohexane, tetramethylcyclohexane, ethylisopropylcyclohexane, dipropylcyclohexane, propylbutylcyclohexane, dimethyldiisopropylcyclohexane, isobutylisopentylcyclohexane and dimethyldibutylcyclohexane.

[0075] To further optimize the technical solution, the n-alkanes are selected from any one or more of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane and n-tetradecane; and / or the isoalkanes are selected from any one or more of isononane, isodecane, isoundecane and isododecane; and / or the cycloalkanes are selected from any one or more of trimethylcyclohexane, tetramethylcyclohexane, ethylisopropylcyclohexane, dipropylcyclohexane, propylbutylcyclohexane and dimethyldiisopropylcyclohexane.

[0076] To further optimize the technical solution, the normal alkane is selected from any one or more of normal nonane, normal decane, normal undecane and normal dodecane.

[0077] The mixed system entering the termination reaction unit terminates the reaction under the action of the terminator, taking into account the fact that the terminator can quickly terminate the reaction and the cost accounting of the terminator, and considering that the terminator will not cause any instability in the subsequent separation and purification after entering the reaction system. In the technical scheme provided in the embodiment of the present application, the terminator is selected from: any one or more of ethanol, propanol, butanol, octanol, isopropanol, isooctyl alcohol, isooctyl alcohol, ethylene glycol, glycerol and water.

[0078] In order to effectively improve the reaction efficiency, the terminator can quickly and efficiently stop the polymerization reaction. The amount of the terminator is 5% to 70% of the amount of the catalyst.

[0079] To further optimize the technical solution, the terminator is selected from any one or more of ethanol, isooctyl alcohol, isooctyl acid, ethylene glycol, propylene glycol and water.

[0080] To further optimize the technical solution, the terminator is water.

[0081] In order to effectively improve the reaction efficiency of the polymerization reaction, reduce the occurrence of side reactions, improve the selectivity of the polymerization reaction, and effectively improve the yield of the target product α-olefin, in the technical scheme provided in the embodiment of the present application, the catalyst includes: a main catalyst and a co-catalyst; the main catalyst is: a chromium-based or titanium-based catalyst coordinated by a monodentate or multidentate ligand of any one or more structures of PNP, PCCP, PNSiP, NP, NPN and NNN; the co-catalyst is selected from: one or more of alkylaluminoxanes, a mixture of alkylaluminum and a boron-based auxiliary agent, a modified alkylaluminoxane and a halogenated alkylaluminum.

[0082] To further optimize the technical solution, the molar ratio of the co-catalyst metal Al to the main catalyst metal Cr or Ti is (300-600):1 in molar parts.

[0083] The auxiliary agent is selected from any one or more of hydrogen, halogenated hydrocarbons, alkyl lithium and alkyl zinc.

[0084] In order to effectively improve the reaction efficiency of the polymerization reaction, reduce the occurrence of side reactions, improve the selectivity of the polymerization reaction, and effectively increase the yield of the target product α-olefin, in the technical scheme provided in the embodiment of the present application, in step one, the reaction temperature of the polymerization reaction is 30°C to 150°C, and the reaction pressure of the polymerization reaction is 2MPa to 10MPa.

[0085] To further optimize the technical solution, in step one, the reaction temperature of the polymerization reaction is 30°C to 100°C, and the reaction pressure of the polymerization reaction is 3MPa to 6MPa.

[0086] To further optimize the technical solution, in step one, the reaction temperature of the polymerization reaction is 40°C to 80°C.

[0087] In combination with the above-mentioned production device and / or production method, the following examples will use the above-mentioned technical scheme to prepare α-hexene and α-octene. The catalyst used in the following examples is the PNP coordinated chromium catalyst disclosed in Example 3 of the applicant's prior patent CN116553993A.

[0088] Example 1

[0089] In this embodiment, the mixed solvent used has a boiling range of 140-220° C. and a flash point of 30-80° C., wherein the mixed solvent contains 8% normal alkanes, 42% isoalkanes and 50% cycloalkanes, wherein the normal alkanes include 6% normal nonane and 2% normal decane, the isoalkanes include 26% isononane and 16% isodecane, and the cycloalkanes include 25% trimethylcyclohexane and 25% tetramethylcyclohexane.

[0090] The above-described production device and / or production method is used to carry out ethylene polymerization reaction, water is used as a quenching agent, a chromium complex coordinated by a PNP ligand is used as a main catalyst, and modified methylaluminoxane and alkylaluminum are used as co-catalysts.

[0091] During the polymerization reaction in the reactor, the solvent, main catalyst and co-catalyst solution after dehydration and deoxygenation are continuously added to the reactor; the feed amount is controlled by a metering pump, wherein the molar number of Cr is 4 μmol, Al / Cr=800; the ethylene and hydrogen feed amounts are controlled by a flow meter to maintain the reactor pressure at 5.5 MPa; the reactor temperature is controlled to maintain 55-60°C.

[0092] After the polymerization reaction occurs in the reactor, the obtained reaction product is flashed, and the obtained mixed system enters the termination reaction unit, and a certain amount of terminator is added through a metering pump. The mass of terminator added per hour is 40% of the mass of catalyst added; the temperature in the tank is controlled at 100-180°C through a temperature control system to terminate the reaction of the product generated in the reactor.

[0093] In the separation and purification unit, the first solvent purification section performs distillation of α-hexene and α-octene; wherein, the α-hexene refining tower is used to separate and obtain α-hexene with higher purity, and the α-octene refining tower is used to separate and obtain α-octene with higher purity. In the second solvent purification section, the C10 and above products and solvents generated by the polymerization reaction pass through the solvent purification section, such as Figure 3 As shown, firstly, nickel-based catalyst is used for hydrogenation and refining to remove olefins, then modified MOF materials are used for adsorption and removal of trace olefins, and then dehydration, deoxygenation and impurity removal are carried out through dehydration tower and deoxygenation tower, and the olefin, water and oxygen contents are monitored in real time. When the olefin content is ≤1ppm, and the water and oxygen contents are ≤1ppm, they can be added to the reactor through a pump for recycling.

[0094] The production unit was operated continuously for 360 hours under the above process. The temperature in the reactor was stably controlled, the reactor was relatively clean, and the pipeline was not blocked. The liquid phase composition was regularly sampled and analyzed. The catalyst activity was 1735 kg product / gCr·h, the α-octene selectivity was 68.1%, the α-hexene selectivity was 15.3%, and the solid polymer was 0.06%.

[0095] Example 2

[0096] In this embodiment, the mixed solvent used has a boiling range of 140-220° C. and a flash point of 30-80° C., wherein the mixed solvent contains 20% normal alkanes, 35% isoalkanes and 45% cycloalkanes, wherein the normal alkanes include 10% normal nonane and 10% normal decane, the isoalkanes include 17% isononane, 8% isodecane and 10% isoundecane, and the cycloalkanes include 25% trimethylcyclohexane and 20% tetramethylcyclohexane.

[0097] The above-described production device and / or production method is used to carry out ethylene polymerization reaction, water is used as a quencher, the above-described device and process are used to carry out ethylene polymerization reaction, a chromium complex coordinated by a PNP ligand is used as a main catalyst, and modified methylaluminoxane and alkylaluminum are used as co-catalysts.

[0098] During the polymerization reaction in the reactor, the solvent, main catalyst and co-catalyst solution after dehydration and deoxygenation are continuously added to the reactor; the feed amount is controlled by a metering pump, wherein the molar number of Cr is 4 μmol, Al / Cr=800; the ethylene and hydrogen feed amounts are controlled by a flow meter to maintain the reactor pressure at 5.5 MPa; the reactor temperature is controlled to maintain 55-60°C.

[0099] After the polymerization reaction occurs in the reactor, the obtained reaction product is flashed, and the obtained mixed system enters the termination reaction unit, and a certain amount of terminator is added through a metering pump. The mass of terminator added per hour is 40% of the mass of catalyst added; the temperature in the tank is controlled at 100-180°C through a temperature control system to terminate the reaction of the product generated in the reactor.

[0100] In the separation and purification unit, the first solvent purification section performs distillation of α-hexene and α-octene; wherein, the α-hexene refining tower is used to separate and obtain α-hexene with higher purity, and the α-octene refining tower is used to separate and obtain α-octene with higher purity. In the second solvent purification section, the C10 and above products and solvents generated by the polymerization reaction pass through the solvent purification section, such as Figure 3 As shown, firstly, nickel-based catalyst is used for hydrogenation and refining to remove olefins, then modified MOF materials are used for adsorption and removal of trace olefins, and then dehydration, deoxygenation and impurity removal are carried out through dehydration tower and deoxygenation tower, and the olefin, water and oxygen contents are monitored in real time. When the olefin content is ≤1ppm, and the water and oxygen contents are ≤1ppm, they can be added to the reactor through a pump for recycling.

[0101] The device was operated continuously for 300 hours under the above process. The temperature in the reactor was stably controlled, the reactor was relatively clean, and there was a small amount of polymer in the pipeline. The liquid phase composition was analyzed by regular sampling. The catalyst activity was 1658 kg product / gCr·h, the α-octene selectivity was 66.7%, the α-hexene selectivity was 16.3%, and the solid polymer was 0.15%.

[0102] Example 3

[0103] In this embodiment, the mixed solvent used has a boiling range of 140-220° C. and a flash point of 30-80° C., wherein the mixed solvent contains 27% normal alkanes, 40% isoalkanes and 33% cycloalkanes, wherein the normal alkanes include 14% normal nonane, 8% normal decane and 5% normal undecane, the isoalkanes include 22% isononane, 10% isodecane and 8% isoundecane, and the cycloalkanes include 25% trimethylcyclohexane and 8% tetramethylcyclohexane.

[0104] The above-described production device and / or production method is used to carry out ethylene polymerization reaction, water is used as a quenching agent, a chromium complex coordinated by a PNP ligand is used as a main catalyst, and modified methylaluminoxane and alkylaluminum are used as co-catalysts.

[0105] During the polymerization reaction in the reactor, the solvent, main catalyst and co-catalyst solution after dehydration and deoxygenation are continuously added to the reactor; the feed amount is controlled by a metering pump, wherein the molar number of Cr is 4 μmol, Al / Cr=800; the ethylene and hydrogen feed amounts are controlled by a flow meter to maintain the reactor pressure at 5.5 MPa; the reactor temperature is controlled to maintain 55-60°C.

[0106] After the polymerization reaction occurs in the reactor, the obtained reaction product is flashed, and the obtained mixed system enters the termination reaction unit, and a certain amount of terminator is added through a metering pump. The mass of terminator added per hour is 40% of the mass of catalyst added; the temperature in the tank is controlled at 100-180°C through a temperature control system to terminate the reaction of the product generated in the reactor.

[0107] In the separation and purification unit, the first solvent purification section performs distillation of α-hexene and α-octene; wherein, the α-hexene refining tower is used to separate and obtain α-hexene with higher purity, and the α-octene refining tower is used to separate and obtain α-octene with higher purity. In the second solvent purification section, the C10 and above products and solvents generated by the polymerization reaction pass through the solvent purification section, such as Figure 3 As shown, firstly, nickel-based catalyst is used for hydrogenation and refining to remove olefins, then modified MOF materials are used for adsorption and removal of trace olefins, and then dehydration, deoxygenation and impurity removal are carried out through dehydration tower and deoxygenation tower, and the olefin, water and oxygen contents are monitored in real time. When the olefin content is ≤1ppm, and the water and oxygen contents are ≤1ppm, they can be added to the reactor through a pump for recycling.

[0108] The device was operated continuously for 260 hours under the above process. The temperature control in the reactor was relatively stable. A small amount of polymer adhered to the reactor wall and a thin layer of polymer was also attached to the pipeline. The liquid phase composition was analyzed by regular sampling. The catalyst activity was 1559 kg product / gCr·h, the α-octene selectivity was 67.0%, the α-hexene selectivity was 14.8%, and the solid polymer was 0.59%.

[0109] Comparative Example 1

[0110] Using cyclohexane as solvent, the reaction unit and part of the separation unit of the above device were used to carry out ethylene polymerization reaction, and other process conditions were the same as those in Example 1. After the device was continuously operated for 50 hours, the pipeline from the liquid outlet of the flash tank to the termination reactor was blocked by polymer, and the reactor also had a lot of solid polymer, with a PE content of 0.91%. The catalyst activity was 1673 kg product / gCr·h, the α-octene selectivity was 67.6%, and the α-hexene selectivity was 14.8%.

[0111] Comparative Example 2

[0112] A mixed solvent of n-hexane and cyclohexane in a volume ratio of 1:1 was used as the solvent, and the reaction unit and part of the separation unit of the above device were used to carry out ethylene polymerization reaction, and other process conditions were the same as those in Example 1. After the device was continuously operated for 50 hours, the pipeline from the liquid outlet of the flash tank to the termination reactor was blocked by polymer, and the reactor also had a lot of polymer, with a PE content of 0.96%. The catalyst activity was 1588 kg product / gCr·h, the α-octene selectivity was 67.8%, and the α-hexene selectivity was 14.9%.

[0113] Comparative Example 3

[0114] Methylcyclohexane was used as solvent, and the reaction unit and part of the separation unit of the above device were used to carry out ethylene polymerization reaction, and other process conditions were the same as those in Example 1. After the device was continuously operated for 50 hours, the pipeline from the liquid outlet of the flash tank to the termination reactor was blocked by polymer, and the reactor also had a lot of polymer, with a PE content of 1.10%. The liquid phase composition was sampled and analyzed. The catalyst activity was 1601 kg product / gCr·h, the α-octene selectivity was 67.1%, and the α-hexene selectivity was 14.4%.

[0115] Comparative Example 4

[0116] A mixed solvent of methylcyclohexane and normal hexane in a volume ratio of 1:1 was used as the solvent, and the reaction unit and part of the separation unit of the above device were used to carry out ethylene polymerization reaction, and other process conditions were the same as those in Example 1. After the device was continuously operated for 50 hours, the pipeline from the liquid outlet of the flash tank to the termination reactor was blocked by polymer, and the reactor also had a lot of polymer, with a PE content of 0.95%. The catalyst activity was 1623 kg product / gCr·h, the α-octene selectivity was 67.3%, and the α-hexene selectivity was 14.5%.

[0117] Combining the above embodiments and comparative examples, it can be further concluded that since the selected solvent has a stronger solubility for the polymerized olefins generated by the polymerization reaction, there is little polymer attachment to the reactor and the connecting pipes between the steps, which significantly extends the duration of the continuous reaction and effectively improves the production capacity; at the same time, the polymerization reaction has better selectivity for the produced α-octene and α-hexene.

[0118] In summary, the present application provides a production device for preparing α-olefins, and the present application also provides a production method for preparing α-olefins using the above production device, which is: polymerization reaction, flash evaporation, reaction termination and separation and purification: wherein the boiling range of the solvent used in the polymerization reaction is 120°C to 287°C, and the flash point of the solvent is 25°C to 135°C. The present application also provides an application of the above production device or the above production method in the preparation of α-hexene and / or α-octene. In the technical scheme provided by the present application, by selecting a mixed solvent with a specific range of boiling range and flash point, the dissolving ability of the polymer product obtained by the polymerization reaction is stronger, the polymer product is fully dissolved in the solvent and will not adhere to the reaction device and the connecting pipeline, will not be blocked, and is also conducive to heat transfer, thereby effectively reducing energy consumption, the preparation process is simple, the mixed solvent can be recycled and reused without re-separation, and continuous production can be carried out, effectively reducing labor costs. A production device, production method and application of α-olefins provided by the present application solve the technical defects of high labor cost, high energy consumption and easy blockage of reactors and reaction pipelines in the prior art of the production process of α-olefins, and also reduce the content of ethylene in the product.

[0119] The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. At the same time, other implementation methods can be derived from the above-mentioned embodiments, so that structural and logical replacements and changes can be made without departing from the scope of this disclosure.

[0120] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A production device for preparing α-olefins, characterized in that: The production device comprises: a raw material pretreatment unit, a reaction unit, a termination reaction unit and a separation and purification unit, wherein the raw material pretreatment unit, the reaction unit, the termination reaction unit and the separation and purification unit are connected in sequence; The reaction unit comprises: a reactor and a flash evaporator. After the reaction in the reactor is completed, the olefin raw material enters the flash evaporator to be evaporated and then re-enters the reactor; The raw material pretreatment unit is used for dehydration purification and / or deoxygenation purification of each reaction raw material.

2. The production device according to claim 1, characterized in that: The separation and purification unit comprises: a filtering section, a first solvent purification section and a second solvent purification section. After the reaction mixture system of the termination reaction unit is filtered to remove solid impurities, the reaction product α-olefin is removed through the first solvent purification section, and then the reaction solvent is dehydrated and / or deoxygenated and / or impurity-removed and purified through the second solvent purification section. The outlet of the second solvent purification section is connected to the reaction unit.

3. A method for preparing α-olefins using the production device according to claim 1 or 2, characterized in that: The production method is: Step 1, polymerization reaction: ethylene, catalyst, auxiliary agent and solvent are purified and mixed, and polymerization reaction occurs to obtain the first product; Step 2, flash evaporation: flash evaporation of the first product, separation of gaseous ethylene for re-polymerization, and the resulting liquid mixture as the second product; Step 3, reaction termination: the second product is mixed with a terminator to obtain a third product; Step 4, separation and purification: the third product is separated and purified to obtain an α-olefin product; Wherein, the boiling range of the solvent is 120°C to 287°C, and the flash point of the solvent is 25°C to 135°C.

4. The production method according to claim 3, characterized in that: In terms of mass percentage, the solvent includes: 1-30% normal alkane, 35-70% isoalkane and 35-70% cycloalkane.

5. The production method according to claim 4, characterized in that: The normal alkane is selected from any one or more of n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and n-hexadecane; and / or, the isoalkane is selected from any one or more of isononane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane and isohexadecane; And / or, the cycloalkane is selected from any one or more of trimethylcyclohexane, tetramethylcyclohexane, ethylisopropylcyclohexane, dipropylcyclohexane, propylbutylcyclohexane, dimethyldiisopropylcyclohexane, isobutylisopentylcyclohexane and dimethyldibutylcyclohexane.

6. The production method according to any one of claims 3 to 5, characterized in that: The terminator is selected from any one or more of ethanol, propanol, butanol, octanol, isopropanol, isooctyl alcohol, isooctyl acid, ethylene glycol, glycerol and water; And / or, the feeding amount of the terminator is 5% to 70% of the feeding amount of the catalyst.

7. The production method according to any one of claims 3 to 5, characterized in that: The catalyst comprises: a main catalyst and a co-catalyst; The main catalyst is a chromium or titanium catalyst coordinated by any one or more monodentate or multidentate ligands of PNP, PCCP, PNSiP, NP, NPN and NNN; The co-catalyst is one or more selected from: alkylaluminoxane, a mixture of alkylaluminum and borate, modified alkylaluminoxane and halogenated alkylaluminum.

8. The production method according to claim 7, characterized in that: In terms of molar parts, the molar ratio of the co-catalyst metal Al to the main catalyst metal Cr or Ti is (300-600):

1.

9. The production method according to any one of claims 3 to 5, characterized in that: The auxiliary agent is selected from any one or more of hydrogen, halogenated hydrocarbons, alkyl lithium and alkyl zinc.

10. The production method according to any one of claims 3 to 5, characterized in that: In step 1, the reaction temperature of the polymerization reaction is 30° C. to 150° C., and the reaction pressure of the polymerization reaction is 2 MPa to 10 MPa.

11. Use of the production device according to any one of claims 1 to 2 or the production method according to any one of claims 3 to 10 in the preparation of α-hexene and / or α-octene.

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