Device and method for preparing 1-octene by ethylene selective oligomerization
阅读说明：本技术 乙烯选择性齐聚制备1－辛烯的装置和方法 (Device and method for preparing 1-octene by ethylene selective oligomerization ) 是由 杨颖� 乔小飞 贾峥瑞 赵楠 宋明焱 冯兴磊 孙媛媛 贾海兵 员玫 薛勇勇 ** 于 2019-10-10 设计创作，主要内容包括：本发明涉及一种连续化乙烯选择性齐聚制备1－辛烯的装置和方法。该流程采用釜式反应器与管式反应器串联的工艺：乙烯低温液相输送至釜式反应器,在反应器内被加热气化,一部分乙烯气体通过分布器喷射进入反应体系内参与反应,另一部分乙烯作为移热介质气化吸收反应热并循环利用,主催化剂a/配体b及助催化剂c分别与溶剂混合后加入釜式反应器,调节剂d直接气相进料至反应釜；反应后的物料经输送泵送入管式反应器,与淬灭剂在管式反应器内高温反应,淬灭后的物料进入分离系统；该方法进行制备1－辛烯,具有高催化活性,高1－辛烯选择性,高淬灭效率,长运转周期等优势。(The invention relates to a device and a method for preparing 1-octene by continuous selective oligomerization of ethylene. The process adopts a process of connecting a kettle reactor and a tubular reactor in series: conveying the ethylene low-temperature liquid phase to a kettle-type reactor, heating and gasifying the ethylene in the reactor, injecting a part of ethylene gas into a reaction system through a distributor to participate in reaction, gasifying the other part of ethylene as a heat transfer medium to absorb reaction heat and recycle the reaction heat, mixing a main catalyst a/ligand b and a cocatalyst c with a solvent respectively, adding the mixture into the kettle-type reactor, and directly feeding a regulator d into the reaction kettle in a gas phase manner; the reacted materials are conveyed into the tubular reactor through a conveying pump, react with the quenching agent at high temperature in the tubular reactor, and the quenched materials enter a separation system; the method for preparing 1-octene has the advantages of high catalytic activity, high 1-octene selectivity, high quenching efficiency, long running period and the like.)
1. A device for preparing 1-octene by ethylene selective oligomerization comprises a compressor, a condenser, a kettle type reactor and a tubular reactor,
wherein the ethylene feeding pipe is connected with the inlet of a compressor, the outlet of the compressor is connected with the inlet of a condenser, the outlet of the condenser is connected with the inlet of an inner coil pipe for heat transfer of the kettle type reactor, the outlet of the inner coil pipe for heat transfer is connected with the inlet of the compressor,
the outlet of the kettle reactor and the feeding pipe of the quenching agent are connected with the inlet of the tubular reactor, wherein the coil pipe in the reaction kettle is provided with small gas distribution holes for feeding ethylene into the reactor.
2. The apparatus according to claim 1, wherein the tubular reactor outlet is connected to a separation unit.
3. The apparatus of claim 1 or 2, wherein the tank reactor is provided with a main catalyst/ligand feeding pipe, a cocatalyst feeding pipe and a solvent feeding pipe for feeding into the tank reactor.
4. The apparatus according to any one of claims 1 to 3, wherein the coil in the tank reactor has 6 to 20 layers, preferably 8 to 12 layers; and/or
3-80, preferably 8-36, more preferably 12-24 gas distribution holes are uniformly distributed in each layer of the coil along the circumference of the inner coil, the gas distribution holes are upward or downward, and preferably the gas distribution holes are alternately distributed downward and upward.
5. The apparatus according to any one of claims 1 to 4, wherein 1 to 4 upward or downward gas distribution holes are distributed in each layer of the coil pipe every 15 to 60 degrees of central angle, and in the case that more than two gas distribution holes are distributed in the same cross section every 15 to 60 degrees of central angle, the gas distribution holes are distributed on both sides of the topmost or bottommost point of the inner coil pipe or on both sides of the topmost or bottommost point and the bottommost point respectively at equal central angle distances;
further, under the condition that two gas distribution small holes are distributed on the same cross section at intervals of 15-60-degree central angles, the gas distribution small holes are distributed at 45-degree central angles on two sides of the top point or the bottom point of the circular section of the inner coil pipe;
furthermore, the aperture of the gas distribution small hole is 0.1-50%, preferably 5-20% of the diameter of the inner coil.
6. A method for preparing 1-octene by continuous selective oligomerization of ethylene comprises the following steps:
(1) carrying out selective tetramerization reaction on raw material ethylene in a kettle type reactor in the presence of a solvent and a catalyst system;
(2) conveying the reaction liquid and the quenching agent to a tubular reactor through a pump, carrying out high-temperature catalyst inactivation reaction in the tubular reactor, and feeding the quenched material into a separation system for ethylene recovery and product purification;
wherein, the raw material ethylene in the step (1) is fed into the heat exchange inner coil pipe of the reaction kettle in a low-temperature liquid phase mode, the liquid phase ethylene is gasified to remove reaction heat at the operation temperature of the reaction kettle, one part of the gasified ethylene is fed into the reactor through gas distribution holes on the coil pipe in the reaction kettle, and the other part of the ethylene circulates among the coil pipe in the reaction kettle, the outer circulation compressor and the condenser.
7. The method of claim 6, wherein the pressure in the reaction vessel is accurately controlled by controlling the valve opening of the gaseous ethylene outlet line, and the temperature in the reaction vessel is accurately controlled by controlling the amount of liquid ethylene entering the reaction vessel.
8. The method according to claim 6 or 7, wherein the operating temperature of the process for preparing 1-octene by ethylene tetramerization is 30-60 ℃, preferably 40-50 ℃, and the operating pressure of the process for preparing 1-octene by ethylene tetramerization is 3.0-7.0 MPaG, preferably 4.0-5.0 MPaG; and/or
The main catalyst a for oligomerization in the step (1) is chromium acetylacetonate, tetrahydrofuran chromium chloride or chromium isooctanoate; the ligand b can be PNP, SNS or PCCP structure; the cocatalyst c is methyl aluminoxane, ethyl aluminoxane or modified methyl aluminoxane; and/or
The feeding molar ratio of the catalyst a to the ligand b is 1: 1-1: 5, preferably 1: 1.5-1: 2, the feeding molar ratio of the catalyst a to the cocatalyst c is Al: 10-1000, preferably 100-500, and the mass ratio of the catalyst a to the ethylene is 1: 5X 105～1：1×104Preferably 1: 2X 105～1：5×104(ii) a And/or
The solvent for oligomerization in the step (1) is alkane with more than C6, cycloalkane with more than C6 and arene, preferably cycloalkane with more than C6; and/or
The feeding mass ratio of ethylene to the solvent is 0.5: 1-3: 1, preferably 1: 1-1.5: 1; and/or the reaction regulator in the stage (1) is hydrogen, the addition amount of the regulator hydrogen is controlled through analysis of the composition of ethylene and hydrogen in the gas phase space of the reaction kettle, and the composition of the hydrogen in the gas phase space of the reaction kettle in the process of preparing 1-octene through ethylene tetramerization is 1-20 wt.%, preferably 5-10 wt.%.
9. The method according to any one of claims 6-8, wherein: conveying the reaction liquid and the quenching agent pump in the step (2) to a tubular reactor, wherein the operation temperature in the tubular reactor is 80-150 ℃, and preferably 90-110 ℃; and/or
The tubular reactor in the step (2) is heated by adopting an external jacket, and the heat source can be low-pressure steam, hot oil and high-temperature process gas to be condensed by a separation unit; and/or
The quenching agent in the step (2) is water, ethanol or 2-ethylhexanol; and/or
The retention time in the tubular reactor in the step (2) is 3-60 min, preferably 5-15 min; and/or
The molar ratio of the addition amount of the quenching agent in the step (2) to the alkyl aluminum in the reaction liquid is 1: 1-10: 1, preferably 3: 1-6: 1.
The technical field is as follows:
the invention relates to a device and a method for preparing 1-octene by continuous ethylene selective oligomerization, which comprises a continuous process that ethylene is polymerized to generate 1-octene in an oligomerization catalyst system, reaction liquid is mixed with a quenching agent in a high-temperature tubular reactor, and the catalyst is inactivated.
Background
1-octene is used as an important organic raw material and a chemical intermediate, is mainly used for producing high-end PE and POE, and is obviously improved in the aspects of impact resistance, tearing resistance and the like compared with PE produced by using traditional comonomers such as 1-butene and 1-hexene.
The current process technology for preparing 1-octene by ethylene high-selectivity tetramerization faces greater challenges in the aspects of development, engineering amplification and the like of a catalytic system. CN104220402/CN105263890 describes a selective ethylene tetramerization catalyst system, which comprises a chromium-containing compound as a main catalyst, a N, P-containing compound as a ligand of the main catalyst, and a metal alkyl compound as a cocatalyst; CN102460545 introduces a fourth catalytic component as an accelerant of ethylene selective tetramerization on the basis of the three-way catalytic system, wherein the accelerant can be halogenated alkane or aromatic hydrocarbon, and a fifth component is used as a second ligand of a main catalyst, so as to improve the activity of the catalyst and the selectivity of 1-octene; in addition, WO2004/056479, US2008/0242811 and the like all describe the effect on ethylene tetramerization catalytic activity and 1-octene selectivity after changing Cr precursor substituents and ligand substituents on the basis of Cr/PNP/alkylaluminum catalytic systems.
The method for preparing 1-octene by ethylene selective tetramerization focuses on the research of catalysts, although the ethylene oligomerization catalyst system obtains remarkable results in the generation-by-generation optimization process, compared with the trimerization, the ethylene tetramerization process of the Cr/PNP/alkyl aluminum catalyst system has the characteristics of low reaction temperature, large reaction heat release, low selectivity of 1-octene, adhesion of byproduct oligomers to heat exchange tubes or blockage of pipelines and the like under the reaction condition, and simultaneously the alkyl aluminum serving as a cocatalyst is difficult to completely inactivate, the product rectification cost is increased, the treatment risk of the waste liquid containing the inactivated alkyl aluminum is greatly increased, so that the method for preparing 1-octene by ethylene selective tetramerization has more technical difficulties in the aspect of engineering amplification. CN2010/10543099 describes a feeding improvement method of ethylene tetramer, in which a part of reactants, ethylene and solvent, are first mixed in a premixer, then mixed with a quaternary catalytic system through a pipeline, and then fed into a reaction kettle together, with the effect of increasing mass transfer time to disperse ethylene uniformly so as to improve catalyst activity; however, the problems of the heat transfer of the reaction system, the adhesion and clogging of the oligomer, and the post-treatment of the aluminum alkyl are not described.
Aiming at the characteristics and problems of an ethylene selective tetramerization reaction system, a new process method is required to be found to improve the activity of a catalytic system and the selectivity of 1-octene, effectively remove reaction heat, simultaneously slow down production interruption caused by adhesion and blockage of equipment pipelines, and simultaneously develop an effective quenching method of the catalytic system, so that alkyl aluminum is prevented from entering a separation system to influence the product quality and potential safety hazards are avoided.
Disclosure of Invention
The invention aims to provide a method and a device for preparing 1-octene by continuous selective oligomerization of ethylene, which have the advantages of high catalyst activity, high selectivity of 1-octene, alleviation of adhesion and blockage of equipment pipelines, reduction of oligomer adhesion, high quenching agent inactivation efficiency and the like.
According to a first aspect of the invention, the invention provides a device for preparing 1-octene by ethylene selective oligomerization, which comprises a compressor, a condenser, a tank reactor and a tubular reactor,
wherein the ethylene feeding pipe is connected with the inlet of a compressor, the outlet of the compressor is connected with the inlet of a condenser, the outlet of the condenser is connected with the inlet of an inner coil pipe for heat transfer of the kettle type reactor, the outlet of the inner coil pipe for heat transfer is connected with the inlet of the compressor,
the outlet of the kettle reactor and the feeding pipe of the quenching agent are connected with the inlet of the tubular reactor, wherein the coil pipe in the reaction kettle is provided with small gas distribution holes for feeding ethylene into the reactor.
Further, the outlet of the tubular reactor is connected to a separation unit.
Further, the kettle type reactor is provided with a cocatalyst/ligand feeding pipe, a cocatalyst feeding pipe and a solvent feeding pipe which are used for feeding materials into the kettle type reactor.
Further, the coil in the tank reactor has 6 to 20 layers, preferably 8 to 12 layers. Each layer may be spaced 60-150mm apart in the height direction.
The tank reactor of the present invention may be a conventional autoclave-resistant reactor, for example, having an aspect ratio of 1.2: 1-2: the invention relates to an elliptical end socket, which is characterized in that a reaction kettle used in the invention is different from an inner coil pipe for heat transfer, the inner coil pipe is provided with small gas distribution holes, and reaction raw material ethylene is simultaneously used as a heat transfer medium and is fed through the small gas distribution holes on the inner coil pipe.
Further, 3-80, preferably 8-36, more preferably 12-24 gas distribution holes are uniformly distributed in each layer of the coil pipe along the circumference of the inner coil pipe, the gas distribution holes are upward or downward, and preferably the gas distribution holes are alternately distributed downward and upward.
Preferably, in the case that 1-4 upward or downward gas distribution holes are distributed in every 15-60 degree central angle (around the circumference of the whole layer of inner coil) of each layer of coil (i.e. 1-4 upward or downward gas distribution holes are distributed in the same cross section of the inner coil), and more than two gas distribution holes are distributed in the same cross section of every 15-60 degree central angle, each gas distribution hole can be distributed on both sides of the topmost point or the lowest point of the inner coil at equal central angle distance, or the topmost point or the lowest point and both sides thereof, preferably alternately distributed on both sides of the topmost point and the lowest point of the inner coil, or the topmost point and the lowest point and both sides thereof. For example, in the case that two gas distribution small holes are distributed on the same cross section at intervals of 15-60 degrees of central angles, the gas distribution small holes can be distributed on 45-degree central angles on two sides of the top point or the bottom point of the circular section of the inner coil pipe. More than 1 gas distribution small holes on the same cross section are used as one group, and the orifices of the gas distribution small holes between the adjacent groups are alternately distributed upwards and downwards.
Furthermore, the aperture of the gas distribution small hole is 0.1-50%, preferably 5-20% of the diameter of the inner coil. The nominal diameter of the inner coil may be 20-60mm, for example 40mm, and the wall thickness of the tube may be 2-5mm, for example 3.6 mm.
The tubular reactor used in the present invention may be a tubular reactor conventionally used in the art.
According to a second aspect of the present invention, there is provided a process for preparing 1-octene by continuous selective oligomerization of ethylene, which comprises the following steps:
(1) carrying out selective tetramerization reaction on raw material ethylene in a kettle type reactor in the presence of a solvent and a catalyst system;
(2) conveying the reaction liquid and the quenching agent to a tubular reactor through a pump, carrying out high-temperature catalyst inactivation reaction in the tubular reactor, and feeding the quenched material into a separation system for ethylene recovery and product purification;
wherein, the raw material ethylene in the step (1) is fed into the heat exchange inner coil pipe of the reaction kettle in a low-temperature liquid phase mode, the liquid phase ethylene is gasified to remove reaction heat at the operation temperature of the reaction kettle, one part of the gasified ethylene is fed into the reactor through gas distribution holes on the coil pipe in the reaction kettle, and the other part of the ethylene circulates among the coil pipe in the reaction kettle, the outer circulation compressor and the condenser.
The pressure in the reaction kettle can be accurately controlled by controlling the opening degree of a valve of a gas-phase ethylene outlet pipeline, and the temperature in the reaction kettle can be accurately controlled by controlling the amount of liquid-phase ethylene entering the reaction kettle.
In the invention, in the step (1), the ethylene is sprayed into the reaction liquid through the gas distribution small holes at different positions on the inner coil pipe, so that the mass transfer effect is enhanced, the concentration distribution of the ethylene in the reaction liquid is more uniform, and the phenomenon of excessive generation of by-product oligomers caused by overhigh local concentration of the ethylene is greatly avoided.
In the invention, the by-product oligomer in the ethylene tetramerization process in the step (1) can be separated out and adhered to the surface of a heat exchange tube or stirring blades under the operation condition, so that the resistance of mass transfer and heat transfer is increased, the heat transfer is gradually ineffective, the temperature in a reaction kettle is raised, the catalyst is inactivated, and the production is interrupted. The gas-phase ethylene is sprayed at different parts of the inner coil pipe to enter the reaction system, so that the surface of the heat exchange pipe can be effectively scoured, the turbulent effect of fluid around the heat exchange pipe is increased, the heat transfer efficiency is improved, the adhesion blockage of equipment is reduced, and the stable operation period of the device is prolonged.
In the invention, in the step (1), the reaction grade of the ethylene generated by selective tetramerization in the presence of the catalytic system is higher than that of the ethylene generated by selective trimerization to generate 1-hexene, and the mass transfer resistance can be reduced by gas injection feeding, so that the gas content in a liquid phase is improved, and the selectivity of the 1-octene is effectively improved.
In the invention, the active center of the Cr/PNP/alkyl aluminum catalytic system in the step (1) is unstable, the high catalytic activity time is 0.5-2 h, and ethylene gas is adopted for injection feeding, so that the mass transfer can be enhanced, the ethylene concentration in the reaction liquid is increased, the reaction rate is improved, the operation of the catalyst in the high activity retention time range is ensured, the one-way conversion rate of ethylene is improved, and the production cost is reduced.
In the invention, fresh ethylene and circulating ethylene in the step (1) are mixed, then pressurized by a compressor and liquefied by a condenser in sequence, and then fed into a reaction kettle, a main catalyst a/ligand b is prepared into a solution by a solvent and fed into the reaction kettle, and an auxiliary catalyst c and the solvent are directly fed into the reaction kettle; in the reaction process, the addition amount of the regulator is controlled by analyzing the composition of the gas-phase space ethylene and hydrogen, the composition range of the hydrogen in the gas-phase space is 1-20 wt.%, preferably 5-10 wt.%, the hydrogen is used as a chain transfer agent in the ethylene polymerization process, the molecular weight of the byproduct oligomer can be reduced, the oligomer form can be changed, the byproduct oligomer is flocculent after being regulated by adding a proper amount of hydrogen, the viscosity is low, most of the oligomer is suspended in the reaction liquid, and the oligomer cannot adhere to and block equipment; when the content of the regulator is lower than 1 wt.%, the byproduct oligomer is filamentous and has high viscosity, which affects mass transfer and heat transfer, and when the content of hydrogen is higher than 20 wt.%, the activity of the catalyst is obviously reduced, the conversion rate of ethylene is reduced, and the production cost is increased.
In the invention, the ethylene gas distribution aperture on the inner coil pipe in the step (1) is 0.1-50%, preferably 5-20% of the diameter of the inner coil pipe, the diameter of the inner coil pipe is matched with the heat exchange requirement of the reaction kettle, the gas injection flow speed is reduced when the gas distribution aperture is higher than 50%, the washing effect and the mass transfer enhancement effect on oligomers are not obvious any more, the pressure drop is obviously improved when the aperture is lower than 0.1%, and the risk that catalyst particles in the system block small holes is increased.
In the invention, the main catalyst a in the step (1) is chromium acetylacetonate, tetrahydrofuran chromium chloride and chromium isooctanoate, and is sourced from outsourcing bottles; the ligand b is used as the ligand of the main catalyst a and can be in structures of PNP, SNS and PCCP, and the PNP ligand is shown as the formula (R)1)(R2)P-NH-P(R3)(R4) The SNS type ligand is of the formula (R)1)(R2)S-NH-S(R3)(R4) The PCCP ligand is of the formula (R)1)(R2)P-CH2-CH2-P(R3)(R4) Wherein R is1、R2、R3、R4Independently from each other, the hydrogen atoms on the bridging structure-N-or-C-C-can be substituted by straight-chain or branched-chain alkyl, preferably, the commonly used catalyst b is a diphosphoramine ligand with a PNP structure, the structure connected with P is a benzene ring or an alkyl-substituted benzene ring, the substituent on N is saturated alkyl below C3, and the catalyst b used in the invention is self-made in a laboratory; the cocatalyst c is used as an activator of the main catalyst and can be methylaluminoxane, ethylaluminoxane and modified methylaluminoxane, and is mainly transported from a purchased storage tank; the molar ratio of catalyst a to ligand b feed may be 1: 1-1: 5, preferably 1: 1.5-1: the feeding molar ratio of the catalyst a to the cocatalyst c can be Al: 10-1000, preferably 100-500, and the mass ratio of the catalyst a to the ethylene can be 1: 5X 105～1：1×104Preferably 1: 2X 105～1：5×104The feeding mass ratio of ethylene to the solvent is 0.5: 1-3: 1, preferably 1: 1-1.5: 1; the mass concentration of the main catalyst a in the reaction kettle is 0.1-10 ppm, preferably 0.5-3 ppm, the concentration of the catalyst is lower than 0.1ppm, the reaction rate is obviously reduced, the ethylene conversion rate is reduced, the concentration of the catalyst is higher than 10ppm, the reaction rate is increased, the heat release power is increased, and simultaneously the active center of the generated oligomer is obviously increased, so that the heat transfer of the reaction kettle is difficult, the temperature is increased, the activity of catalytic oligomerization is reduced, and the generation amount of the oligomer is increased.
In the invention, the temperature in the reaction kettle in the step (1) is 30-60 ℃, preferably 40-50 ℃, and the pressure is 3-7 MPaG, preferably 4-5 MPaG. When the temperature is lower than 30 ℃, the catalyst has no catalytic activity, the reaction can not be carried out, and when the temperature is higher than 60 ℃, the general theory of catalyst deactivation is obviously improved, and the overall catalytic activity is reduced; when the pressure is lower than 3MPaG, the ethylene concentration in the reaction liquid is lower, the selectivity of 1-octene is reduced to 40%, the catalyst activity is obviously reduced, and when the pressure is higher than 7MPaG, the ethylene concentration in the reaction liquid is higher, the selectivity of 1-octene is slightly increased, but the generation amount of oligomer is obviously increased, and the risk of interrupting the production due to the adhesion and blockage of equipment is increased.
In the invention, the produced liquid and the quenching agent in the step (2) are fed into a tubular reactor through a delivery pump, the retention time of the catalyst is ensured to be consistent under a plug flow model, the catalyst is fully reacted with the quenching agent and inactivated, the tubular reactor is heated by an outer jacket, and the heating medium can be low-pressure steam, hot oil and high-temperature process gas to be condensed by a separation unit; controlling the outlet pressure of the tubular reactor to make the material in the reaction tube in a full liquid phase state.
In the invention, the pipeline between the kettle type reactor and the tubular reactor in the step (2) is as short as possible, the pipeline and the shell of the delivery pump need to be heated to more than 80 ℃, the operating temperature of the tubular reactor is 80-150 ℃, preferably 90-110 ℃, and the oligomer is completely dissolved in the reaction liquid at the moment, so that the adhesion and blockage of the delivery pipeline and the reaction pipe are avoided, the continuous and stable production of the device is facilitated, meanwhile, the reaction rate of the quenching agent and the catalyst is higher than 80 ℃, the residence time in the reaction pipe is shortened, the production efficiency is facilitated to be improved, but when the temperature is higher than 150 ℃, the thermal stability of the reaction liquid is obviously reduced, the product yield is reduced, and the operation risk is increased.
In the invention, the residence time in the tubular reactor in the step (2) is 3-60 min, preferably 5-15 min, when the residence time is less than 3min, the inactivation of the alkyl aluminum serving as the cocatalyst is incomplete, the alkyl aluminum entering a separation system is difficult to separate from a product, the production cost is increased, meanwhile, part of the alkyl aluminum is enriched in a produced stream, the production operation risk of the component is increased, when the residence time is more than 60min, the inactivation rate of the alkyl aluminum is not obviously changed along with the increase of time, and the quenching efficiency is reduced.
In the invention, the molar ratio of the addition amount of the quenching agent in the step (2) to the alkyl aluminum in the reaction liquid is 1: 1-10: 1, preferably 3: 1-6: 1, when the addition amount of the quenching agent is more than 10: when the catalyst is 1 hour, the entrainment of the quenching agent in the recycled ethylene is higher than 1ppm, and the catalyst activity can be obviously reduced when the quenching agent returns to the reaction kettle along with the ethylene.
By combining the technical scheme, the invention has the advantages that:
(1) ethylene in the oligomerization kettle type reactor is injected and fed through distribution holes in a coil pipe in the reaction kettle, so that mass transfer is enhanced, and the phenomenon of sudden increase of low polymer caused by overhigh local ethylene concentration is avoided;
(2) the ethylene injection feeding method is adopted, so that the surface of the heat exchange pipe is washed, the adhesion of the polymer to the heat exchange pipe is obviously slowed down, and the stable operation period of the reaction kettle is effectively prolonged;
(3) by adopting the method for selective tetramerization of ethylene, the activity of the catalyst is obviously improved, the ratio of Al to Cr is reduced to 100, and the activity of the catalyst reaches 600 kg/gCr/h;
(4) by adopting the method for selective tetramerization of ethylene, the selectivity of 1-octene is higher and is 70 percent;
(5) the catalyst deactivation reaction is carried out in the high-temperature tubular reactor, and the flocculent oligomer in the reaction liquid is completely dissolved, so that the blockage of a reaction tube and a pump is avoided;
(6) the catalyst deactivation reaction is carried out in the high-temperature tubular reactor, the reaction rate is obviously improved, the retention time is 15min, and the conversion rate of the alkyl aluminum is 99.5 percent;
(7) the tubular reactor is operated at high temperature, so that secondary preheating before flash evaporation of ethylene in a separation unit is avoided, and efficient utilization of heat is realized.
Drawings
FIG. 1 is a schematic diagram of a reaction system for preparing 1-octene by ethylene selective oligomerization.
In fig. 1: 1. the reactor comprises an ethylene compressor, 2. an ethylene condenser, 3. a kettle type reactor, 4. a reaction liquid delivery pump, 5. a quenching agent delivery pump and 6. a tubular reactor.
FIG. 2 is a schematic view of a tank reactor in the example of the present invention.
FIG. 3 is a schematic view of the structure of a tubular reactor in the example of the present invention.
Detailed Description
The technical solution of the present invention is illustrated by the following specific examples, which show specific implementation and specific operation procedures, but the scope of the present invention is not limited to the following examples.
As shown in figure 1, the invention provides a device for preparing 1-octene by ethylene selective oligomerization, which comprises a
wherein, the ethylene feeding pipe is connected with the inlet of a
an outlet pipeline of the kettle reactor 3 and a quenching agent feeding pipe are respectively connected with an inlet of the
The outlet of the tubular reactor is connected with a separation unit.
The kettle type reactor is provided with a main catalyst/ligand feeding pipe, a cocatalyst feeding pipe and a solvent feeding pipe which are used for feeding materials into the kettle type reactor.
Fig. 2 is a schematic view of a tank reactor, fig. 2(a) is a schematic view of a main body of the tank reactor, fig. 2(b) is a schematic view of an inner coil, fig. 2(c) is a schematic view of a cross section of one layer of the inner coil, and fig. 2(d) is a sectional view taken along a line a-a in fig. 2 (c). The coil in the reaction vessel has 6 to 20 layers, preferably 8 to 12 layers, 10 layers as shown in FIG. 2, each layer being spaced apart by 100mm in the height direction.
3-80, preferably 8-36, more preferably 12-24 gas distribution holes are uniformly distributed in each layer of the coil along the circumference of the inner coil, the distribution holes face upwards or downwards, and preferably the distribution holes are distributed alternately downwards and upwards.
1-4 upward or downward gas distribution small holes are distributed in each layer of the coil pipe at intervals of a central angle of 15-60 degrees (surrounding the circumference of the whole layer of the coil pipe), namely 1-4 upward or downward gas distribution small holes are distributed on the same cross section of the inner coil pipe, and under the condition that more than two gas distribution small holes are distributed on the same cross section, the gas distribution small holes can be respectively distributed on two sides of the topmost point or the lowest point of the inner coil pipe at equal central angle distances, or the topmost point or the lowest point and two sides of the topmost point or the lowest point. In fig. 2(c) and (d), two gas distribution small holes are distributed on the coil pipe in each layer every 45-degree central angle (two gas distribution small holes are distributed on the same cross section distributed with the gas distribution small holes), 16 gas distribution small holes with the diameter of 4mm are distributed on the coil pipe in each layer totally, every two adjacent gas distribution small holes are alternately distributed on the 45-degree central angles on two sides of the top point or the bottom point of the circular section of the inner coil pipe, the nominal diameter of the inner coil pipe is DN40(40mm), and the wall thickness of the pipe is 3.6 mm.
Furthermore, the aperture of the gas distribution small hole is 0.1-50%, preferably 5-20% of the diameter of the inner coil.
FIG. 3 is a schematic view of a tubular reactor of the present invention, and the tubular reactor used in the present invention may be a tubular reactor conventionally used in the art.
A two-stage series reaction system as shown in FIG. 1 was employed, in which a tank reactor (FIG. 2) had a total volume of 1.0m3900mm in diameter, 1500mm in height, DN40mm in nominal diameter of internal coil, 3.6mm in wall thickness of tube, 4mm in gas distribution aperture, 50mm in diameter of tubular reactor (figure 3), 36m in length and DN80mm in nominal diameter of jacket.
Product analysis instrument: the gas chromatograph is Agilent 7820A, capillary column (DB-5, 30m × 0.25mm × 0.25 μm), initial temperature is 60 deg.C, and is maintained for 1 min; raising the temperature to 80 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 minute; then the temperature was raised to 250 ℃ at a rate of 15 ℃/min and held for 8 minutes. The carrier gas is high-purity N2The split ratio is 30:1, and the split flow is 39 mL/min. The flow rate of the carrier gas is 20mL/min, the waiting time is started to be 2min, the sample injection temperature is 250 ℃, the FID is used as a detector, the temperature of the detector is 260 ℃, and the sample injection amount is 0.2 mu L.
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