A continuous apparatus and process for co-producing 1-butene and 1-hexene

Abstract

The application discloses a kind of continuous co-production 1-butene and 1-hexene equipment and process, belong to homogeneous catalysis technical field.The equipment is through a set of heat exchange and separation device, simultaneously carry out ethylene dimerization, trimerization, equipment energy consumption is small, simple operation.The continuous process disclosed in the application significantly reduces the generation of high polymer PE, effectively prevents pipeline blockage and equipment loss, improves the yield and selectivity of 1-butene and 1-hexene, provides guarantee for long-period continuous operation of equipment.Using the equipment and process disclosed in the application, the catalytic activity of the catalyst can be significantly improved, the activity of ethylene dimerization can reach 50-100 kg / gTi·h, the activity of ethylene trimerization can reach 600-1000 kg / gCr·h, the selectivity of 1-butene is above 94%, the selectivity of 1-hexene is above 95%, and the total amount of PE is less than 0.05%, the process can be continuously operated for more than 2160h.

Description

Technical Field

[0001] This invention relates to the field of homogeneous catalysis technology, and in particular to an apparatus and process for the continuous co-production of 1-butene and 1-hexene. Background Technology

[0002] In recent years, high-end chemicals and high-performance materials have developed rapidly, such as linear low-density polyethylene (LDPE) and high-density polyethylene (HDPE), POE polymers, synthetic rubber, and high-performance resins. The comonomers used in the synthesis of these high-performance materials are linear α-olefins such as 1-butene, 1-hexene, and 1-octene. Currently, multiple ethylene selective oligomerization processes have been established both domestically and internationally. The most common method for producing 1-butene in China is still naphtha catalytic cracking to obtain mixed C4, which is then separated to obtain 1-butene. Currently, China's 1-butene production capacity is 890,000 tons per year, with net imports of 170,000 tons per year. Over time, domestic demand for 1-butene has increased exponentially. 1-Butene and 1-hexene can significantly improve the impact strength, durability, and tear resistance of polyethylene (PE) resins, rubber, plasticizers, and other materials. Through continuous research, multiple ethylene selective oligomerization processes have been established both domestically and internationally. In 2004, China National Petroleum Corporation (CNPC) used its independently developed Cr-based catalysts to establish ethylene trimerization processes with capacities of 50,000 tons per year at Daqing Petrochemical and 200,000 tons per year at Dushanzi Petrochemical.

[0003] The synthesis process of 1-butene from ethylene dimerization is mainly based on the Alphabutol process developed by the French Petroleum Institute (IFP), with a production capacity of 10,000 tons per year. After continuous improvements, it has been adopted by many domestic enterprises, which have built corresponding process equipment. The Alphabutol process is simple, consumes less energy, requires less equipment investment, and is easy to operate. However, the cost of obtaining ethylene is high, the selectivity for 1-butene in C4 is not high, and both ethylene dimerization and trimerization inevitably produce high-polymer PE, which clogs pipelines and prevents the equipment from operating for extended periods. Currently, several ethylene dimerization and trimerization units with associated POE have been built in China, employing homogeneous catalysis with transition metals as the active center and co-catalysts to improve activity. However, this polymerization reaction is difficult to control, easily producing a large amount of byproducts, including high PE levels, which clogs equipment and pipelines, causing significant damage to the equipment, high costs, and difficulty in long-term operation. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an apparatus and process for the continuous co-production of 1-butene and 1-hexene. The apparatus uses a single heat exchange and separation unit for the separation of the products 1-butene and 1-hexene, resulting in low energy consumption and simple operation. The process significantly reduces the generation of polymer PE, effectively preventing pipeline blockage and equipment wear, and ensuring long-term continuous operation of the apparatus.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides an apparatus for the continuous co-production of 1-butene and 1-hexene, comprising a polymerization reaction unit and a separation and recovery unit.

[0007] The polymerization reaction unit includes reactor A for ethylene dimerization and reactor B for ethylene trimerization. The rear end of reactor A is connected to quenching reactor C, and the rear end of reactor B is connected to quenching reactor D.

[0008] The separation unit includes a filter, a flash evaporation system, an ethylene recovery tower, a butene distillation tower, a hexene distillation tower, and a solvent recovery tower connected in sequence.

[0009] The quenching vessel C and quenching vessel D are respectively connected to the filter.

[0010] The temperature of the pipelines connecting the polymerization reaction unit and the separation and recovery unit of the above equipment (the pipelines connecting the quenching kettles C and D to the filter) is controlled at 45℃~55℃. The energy consumption of heat exchange is small, and the heat taken from the reactor is sufficient to keep the pipelines warm, which greatly reduces energy consumption.

[0011] Preferably, the bottom of the reactor A is provided with a feed pipeline for feeding ethylene, solvent, main catalyst A and co-catalyst;

[0012] Preferably, the bottom of the reactor B is provided with a feed pipeline for feeding ethylene, solvent, main catalyst B and co-catalyst;

[0013] In the continuous co-production equipment for 1-butene and 1-hexene of the present invention, the solvent and ethylene are mixed into a feed line, and there are one co-catalyst and one main catalyst A. The three are mixed into a feed line in front of the reactor and connected to the bottom of the reactor A, so that the feed enters the reactor A to carry out the dimerization reaction of ethylene.

[0014] The feed line of reactor B is the same as that of reactor A. The solvent and ethylene are mixed into one feed line, and the co-catalyst and the main catalyst B are each in one feed line. The three are mixed in front of the reactor and connected to the bottom of reactor B, so that they enter reactor B to carry out the trimerization reaction of ethylene.

[0015] Preferably, the reaction vessel A is connected to the quenching vessel C via an overflow pipeline in the middle of the vessel.

[0016] Preferably, the reaction vessel B is connected to the quenching vessel D via an overflow pipeline in the middle of the vessel.

[0017] Preferably, the top of both the quenching vessel C and the quenching vessel D is provided with a quenching agent feed line.

[0018] Preferably, the flash evaporation system is connected to a waste catalyst recovery device at the bottom.

[0019] The equipment described in this invention separates waste catalysts through a flash evaporation system, which reduces the separation difficulty of the separation and recovery unit, improves product purity, and collects catalysts containing metals Ti, Cr and Al, thus reducing environmental pollution.

[0020] Preferably, the top of the ethylene recovery tower is provided with a recovery pipeline for ethylene recovery and recycling.

[0021] Preferably, the top of the butene distillation column is provided with a recovery pipeline for collecting the product 1-butene.

[0022] Preferably, the top of the hexene distillation column is provided with a recovery pipeline for collecting the product 1-hexene.

[0023] Preferably, the top of the solvent recovery tower is provided with a recovery pipeline for solvent recovery and recycling.

[0024] Preferably, the top of the flash evaporation system is connected to the middle of the ethylene recovery tower.

[0025] Preferably, the bottom of the ethylene recovery tower is connected to the middle of the butene distillation tower.

[0026] Preferably, the bottom of the butene distillation column is connected to the middle of the hexene distillation column.

[0027] Preferably, the bottom of the hexene distillation column is connected to the middle of the solvent recovery column.

[0028] Preferably, the bottom of the solution recovery tower is connected to a heavy component recovery device.

[0029] Preferably, the recovery pipeline for ethylene recovery and recycling is connected to the raw material purification system. Preferably, the recovery pipeline for solvent recovery and recycling is connected to the raw material purification system.

[0030] The present invention does not impose any special limitations on the device and its materials; any device and materials known to those skilled in the art can be used.

[0031] This invention also provides a continuous co-production process for 1-butene and 1-hexene, comprising the following steps:

[0032] 1) A mixed solution of ethylene, solvent, main catalyst A, and co-catalyst is continuously injected into reactor A to carry out ethylene dimerization reaction. Then the reaction solution overflows into quenching reactor C for quenching.

[0033] 2) A mixed solution of ethylene, solvent, main catalyst B, and co-catalyst is continuously injected into reactor B to carry out the trimerization reaction of ethylene. Then the reaction solution overflows into quenching reactor D for quenching.

[0034] 3) The quenched reaction liquids in quenching kettles C and D are simultaneously filtered and then enter the flash evaporation system. The waste catalyst is discharged from the bottom of the flash evaporation system. The remaining reaction liquid is processed sequentially through an ethylene recovery tower, a butene distillation tower, a hexene distillation tower, and a solvent recovery tower to recover ethylene and solvent to the raw material purification system for recycling. The products 1-butene and 1-hexene are collected.

[0035] This invention does not impose any special restrictions on the ethylene raw material used in the process; it can be polymer-grade ethylene.

[0036] In the above process, the reaction liquid in reactors A and B enters quenching reactors C and D through the overflow pipeline in the middle of reactors A and B. The residence time of the reaction liquid in the reactor is controlled to promote the full progress of ethylene dimerization and trimerization reactions and control the generation of by-products.

[0037] In this invention, the residence time of the reaction solution in the reaction vessel is preferably 15-65 min; more preferably 20-50 min; and even more preferably 25-40 min.

[0038] In the quenching vessels C and D, the addition of quenching agents deactivates the catalyst in the reaction system, reducing the formation of byproduct polymers at high temperatures.

[0039] The mixed reaction liquid from quenching kettles C and D is filtered to obtain a relatively clear solution, which then sequentially enters the flash evaporation system, ethylene recovery tower, butene distillation tower, hexene distillation tower, and solvent recovery tower for component separation to obtain a qualified product.

[0040] The spent catalyst enters the catalyst collection device from the bottom through the flash evaporation system, and the recovered ethylene and solvent are returned to the raw material purification system for recycling.

[0041] In the above process, the solvents in steps 1) and 2) are alkane solvents that have a significant temperature difference with 1-butene and 1-hexene, specifically including but not limited to cyclohexane, methylcyclohexane, heptane, isooctane, etc.

[0042] The quenching agents in the quenching vessels C and D are selected from high-boiling-point alcohol solvents. These high-boiling-point alcohol solvents are not easily volatile and can suppress the generation of by-products of ethylene dimerization and ethylene trimerization throughout the reaction system.

[0043] Preferably, the molar ratio of the high-boiling-point alcohol solvent to the ethylene dimerization or trimerization co-catalyst is (1-2):1; more preferably (1.4-1.6):1; and even more preferably 1.5:1.

[0044] The high-boiling-point alcohol solvent is preferably one or more selected from isooctanol, glycerol, butanediol, and glycerol. Preferably, the main catalyst A is selected from titanium-containing organic compounds and pyrrole and its derivatives.

[0045] Preferably, the main catalyst B is selected from trivalent chromium organic compounds, nitrogen-containing ligands, and chlorinated alkanes;

[0046] Preferably, the co-catalyst is selected from alkylaluminum.

[0047] Preferably, the titanium-containing organic compound is selected from one or more of tetrabutyl titanate, tetraethyl titanate, and tetraisopropyl titanate.

[0048] Preferably, the pyrrole and its derivatives are selected from one or more of pyrrole, methylpyrrole, and ethylpyrrole;

[0049] In the ethylene dimerization reaction, pyrrole and its derivatives act as polymerization inhibitors, effectively preventing ethylene oligomerization into polymers, reducing the possibility of pipeline and equipment blockage, and thus improving the conversion rate of 1-butene.

[0050] Preferably, the trivalent chromium-containing organic compounds include, but are not limited to, chromium isooctanoate, chromium trichloride, and chromium acetylacetone;

[0051] Preferably, the nitrogen-containing ligand is selected from pyrrole and its derivatives;

[0052] Preferably, the pyrrole and its derivatives include one or more of pyrrole, methylpyrrole, and ethylpyrrole;

[0053] In the trimerization of ethylene, pyrrole and its derivatives act as ligands, providing lone pairs of electrons to Cr in the main catalyst, thereby increasing the catalytic activity of the main catalyst and thus improving the yield and selectivity of 1-hexene.

[0054] Preferably, the chloroalkane is selected from one or more of dichloroethane, tetrachloroethane, and hexachloroethane;

[0055] Preferably, the alkylaluminum is selected from one or more of trimethylaluminum, triethylaluminum, and triethylbutylaluminum.

[0056] Preferably, the molar ratio of titanium-containing organic matter and pyrrole and its derivatives in the main catalyst A is 1:(2-6); more preferably 1:(2.5-5); and even more preferably 1:(3-4).

[0057] Preferably, the molar ratio of the titanium-containing organic compound to alkyl aluminum is 1:(4-10); more preferably 1:(5-8); and even more preferably 1:(5.5-7).

[0058] Preferably, the molar ratio of the trivalent chromium-containing organic compound to the nitrogen-containing ligand in the main catalyst B is 1:(3-6); more preferably 1:(3.5-5.5); and even more preferably 1:(4-5).

[0059] Preferably, the molar ratio of the trivalent chromium-containing organic compound to the chloroalkane is 1:(6-10); more preferably 1:(7-9); and even more preferably 1:(7.5-8.5).

[0060] Preferably, the molar ratio of the trivalent chromium-containing organic compound to alkyl aluminum is 1:(60-120); more preferably 1:(70-110); and even more preferably 1:(80-100).

[0061] Preferably, in steps 1) and 2), the ethylene content in the mixed solution is 15 wt% to 50 wt%; more preferably, it is 20 wt% to 45 wt%; and even more preferably, it is 25 wt% to 40 wt%. The above process controls the temperature of reactors A and B by using conditions such as jackets, coils, and heat exchangers.

[0062] Preferably, the temperature of the reaction vessel A is 40℃~60℃; more preferably 48℃~56℃; and even more preferably 50℃~54℃.

[0063] Preferably, the pressure of the reactor A is 2-6 MPa; more preferably 2.5-5.5 MPa; and even more preferably 3-5 MPa.

[0064] Preferably, the temperature of the reaction vessel B is 100℃~140℃; more preferably 110℃~135℃; and even more preferably 125℃~130℃.

[0065] Preferably, the pressure of the reactor B is 2-6 MPa; more preferably 2.5-5.5 MPa; and even more preferably 3-5 MPa. Compared with the prior art, the continuous co-production equipment for 1-butene and 1-hexene provided by the present invention uses a set of heat exchange and separation devices to enable simultaneous ethylene dimerization and trimerization, resulting in low energy consumption and simple operation. The process is a continuous process, suitable for various catalytic systems for selective oligomerization of ethylene. The continuous process of the present invention significantly reduces the generation of polymer PE, effectively prevents pipeline blockage and equipment wear, significantly improves the yield and selectivity of 1-butene and 1-hexene, and provides a guarantee for long-term continuous operation of the equipment. Using the equipment and process described in this invention, the catalytic activity of the catalyst can be significantly improved. The activity of ethylene dimerization can reach 50-100 kg / gTi·h, the activity of ethylene trimerization can reach 600-1000 kg / gCr·h, the selectivity of 1-butene is above 94%, the selectivity of 1-hexene is above 95%, the total amount of PE is less than 0.05%, and the process can be continuously operated for more than 2160 hours. Attached Figure Description

[0066] Figure 1 This is a diagram of the equipment for the continuous co-production of 1-butene and 1-hexene according to the present invention. Detailed Implementation

[0067] To further illustrate the present invention, the following detailed description of the equipment and process for the continuous co-production of 1-butene and 1-hexene provided by the present invention is provided in conjunction with embodiments.

[0068] All of the following raw materials are available for purchase. The synthesis method of catalyst A is as follows: Tetrabutyl titanate and pyrrole are mixed and stirred in a solvent at a certain molar ratio.

[0069] The method is the same: tetrabutyl titanate can be replaced with one or more of tetraethyl titanate, tetraisopropyl titanate, etc., and pyrrole can be replaced with one or more of methylpyrrole and ethylpyrrole, etc.

[0070] The synthesis method of catalyst B is as follows: a trivalent chromium-containing organic reagent, a nitrogen-containing ligand, and a chloroalkane are mixed and stirred in a solvent at a certain molar ratio; the trivalent chromium-containing organic reagent is one or more of chromium isooctanoate, chromium trichloride, chromium acetylacetone, etc.; the nitrogen-containing ligand is one or more of pyrrole, methylpyrrole, ethylpyridine, etc.; and the chloroalkane is one or more of dichloroethane, tetrachloroethane, hexachloroethane, etc.

[0071] Example 1

[0072] Cyclohexane was selected as the solvent, and ethylene was of polymerization grade. The main catalyst A was a mixed solution of tetrabutyl titanate (1000 μmol / mL) and 2,5-dimethylpyrrole (3000 μmol / mL), with a Ti to pyrrole molar ratio of 1:3. The co-catalyst was triethylaluminum (6000 μmol / mL), with a Ti to Al molar ratio of 1:6. The main catalyst B was a mixed solution of chromium isooctanoate (30 μmol / mL), 2,5-dimethylpyrrole (120 μmol / mL), and tetrachloroethane (240 μmol / mL), with a chromium isooctanoate, 2,5-dimethylpyrrole, and tetrachloroethane molar ratio of 1:4:8. The co-catalyst was triethylaluminum (2400 μmol / mL), and the Cr to Al molar ratio was 1:80. The dimerization and trimerization reactions of ethylene were carried out according to the above method.

[0073] like Figure 1 As shown, ethylene and cyclohexane, purified by the purification system, are mixed in a certain proportion (ethylene accounts for 30 wt% of the mixture) and enter reactors A and B. The prepared main catalysts A and B, along with the co-catalyst, are also introduced into reactors A and B along with the mixture. The pressure in reactors A and B is controlled at 3 MPa, the temperature in reactor A is controlled at 50℃, and the temperature in reactor B is controlled at 125℃. The residence time of the reaction system in reactors A and B is controlled at 30 min. The overflow from the middle of the reactors enters quenching reactors C and D, where it is quenched with isooctanol and then filtered to remove the polymer. The product is then flash-distilled out using a flash evaporation system. The remaining waste catalyst is collected and processed from the bottom of the flash tank. The product sequentially enters an ethylene recovery tower, a butene distillation tower, a hexene distillation tower, and a solvent recovery tower for component separation to obtain a qualified product. Ethylene and solvent are recovered and reused.

[0074] The unit operated continuously for 2530 hours according to the above process. The operation met the requirements of "safe, stable, long-term, full-capacity, and high-quality" production without any unexpected incidents. After shutdown, pipelines and equipment such as reactors were removed, and no large amounts of solid deposits or blockages were found; only a small amount of solids were generated in the filters. Gas phase analysis of the collected products showed that the catalytic activity for ethylene dimerization was approximately 78 kg / gTi·h, with a selectivity of 94.86% for 1-butene and 1.82% for the byproduct 1-hexene. The catalytic activity for ethylene trimerization was 720 kg / gCr·h, with a total selectivity of 95.40% for 1-hexene. 10 Olefins account for 0.42%, and PE accounts for 0.02%.

[0075] Example 2

[0076] Using heptane as solvent and ethylene as polymerization-grade ethylene, the main catalyst A is a mixed solution of tetraethyl titanate (1000 μmol / mL) and pyrrole (4000 μmol / mL), with a Ti to pyrrole molar ratio of 1:4. The co-catalyst is triethylaluminum (5500 μmol / mL), with a Ti to Al molar ratio of 1:5.5. The main catalyst B is a mixed solution of chromium isooctanoate (30 μmol / mL), pyrrole (150 μmol / mL), and hexachloroethane (240 μmol / mL), with a chromium isooctanoate, pyrrole, and hexachloroethane molar ratio of 1:5:8. The co-catalyst is triethylaluminum (2700 μmol / mL), with a Cr to Al molar ratio of 1:90. Ethylene dimerization and trimerization reactions are carried out according to the above method. Figure 1 As shown, ethylene and cyclohexane, purified by the purification system, are mixed in a certain proportion (ethylene accounts for 35 wt% of the mixture) and fed into reactors A and B. The prepared main catalysts A and B, along with the co-catalyst, are also fed into reactors A and B respectively along with the mixture. The pressure in reactors A and B is controlled at 4 MPa, the temperature in reactor A is controlled at 53℃, and the temperature in reactor B is controlled at 128℃. The residence time of the reaction system in reactors A and B is controlled at 35 min. The device operated continuously for approximately 2837 h according to the above process. Gas phase analysis of the collected products showed that the catalytic activity for ethylene dimerization was approximately 87 kg / g Ti·h, with a selectivity of 95.61% for 1-butene and a selectivity of 1.23% for the byproduct 1-hexene. The catalytic activity for ethylene trimerization was 882 kg / g Cr·h, with a selectivity of 95.57% for 1-hexene and C. 10 Olefins accounted for 0.91%, and PE accounted for 0.03%.

[0077] Example 3

[0078] Using methylcyclohexane as solvent and ethylene as polymerization grade, the main catalyst A is a mixed solution of tetraisopropyl titanate (1000 μmol / mL) and ethylpyrrole (3500 μmol / mL), with a Ti:ethylpyrrole molar ratio of 1:3.5. The co-catalyst is triethylaluminum (5000 μmol / mL), with a Ti:Al molar ratio of 1:5. The main catalyst B is a mixed solution of chromium trichloride (30 μmol / mL), ethylpyrrole (120 μmol / mL), and dichloroethane (270 μmol / mL), with a chromium trichloride, ethylpyrrole, and dichloroethane molar ratio of 1:4:9. The co-catalyst is triethylaluminum (2400 μmol / mL), and the Cr:Al molar ratio is 1:80. Ethylene dimerization and trimerization reactions are carried out according to the above method. Figure 1As shown, ethylene and cyclohexane, purified by the purification system, are mixed in a certain proportion (ethylene accounts for 40 wt% of the mixture) and fed into reactors A and B. The prepared main catalysts A and B, along with the co-catalyst, are also fed into reactors A and B respectively along with the mixture. The pressure in reactors A and B is controlled at 3.5 MPa, the temperature in reactor A is controlled at 54℃, and the temperature in reactor B is controlled at 130℃. The residence time of the reaction system in reactors A and B is controlled at 30 min. The device operated continuously for approximately 2672 h according to the above process. Gas phase analysis of the collected products showed that the catalytic activity for ethylene dimerization was approximately 65 kg / g Ti·h, with a selectivity of 94.89% for 1-butene and a selectivity of 3.02% for the byproduct 1-hexene. The catalytic activity for ethylene trimerization was 753 kg / g Cr·h, with a selectivity of 95.33% for 1-hexene and C… 10 Olefins account for 0.62%, and PE accounts for 0.03%.

[0079] Comparative Example 1

[0080] Furan was selected as the polymerization inhibitor for ethylene dimerization. Continuous ethylene dimerization and trimerization reactions were carried out using the reaction and separation units of the apparatus described in Example 1. Other process conditions were the same as in Example 1, with a running time of 1342 h. Gas phase analysis results showed that the catalytic activity for ethylene dimerization was 12 kg / gTi·h, the selectivity for 1-butene was 84.56%, and no 1-hexene was produced as a byproduct. The catalytic activity for ethylene trimerization was 275 kg / gCr·h, the total selectivity for 1-hexene was 82.42%, and the PE content was 0.8%.

[0081] Comparative Example 2

[0082] 1,4-Dioxane was selected as the polymerization inhibitor for ethylene dimerization. Continuous ethylene dimerization and trimerization reactions were carried out using the reaction and separation units of the apparatus described in Example 1. Other process conditions were the same as in Example 1, with a running time of 1248 h. Gas phase analysis results showed that the catalytic activity for ethylene dimerization was 13 kg / gTi·h, the selectivity for 1-butene was 83.42%, the selectivity for by-product 1-hexene was 0.21%, the catalytic activity for ethylene trimerization was 248 kg / gCr·h, the total selectivity for 1-hexene was 83.52%, and the PE content was 0.95%.

[0083] Comparative Example 3

[0084] Ethylene glycol dimethyl ether was selected as the polymerization inhibitor for ethylene dimerization. Continuous ethylene dimerization and trimerization reactions were carried out using the reaction and separation units of the apparatus described in Example 1. Other process conditions were the same as in Example 1, with a running time of 1245 h. Gas phase analysis results showed that the catalytic activity for ethylene dimerization was 15 kg / gTi·h, the selectivity for 1-butene was 82.74%, the selectivity for by-product 1-hexene was 0.35%, the catalytic activity for ethylene trimerization was 312 kg / gCr·h, the total selectivity for 1-hexene was 82.15%, and the PE content was 1.2%.

[0085] Comparative Example 4, without using a polymerization inhibitor, employed the reaction and separation units of the apparatus described in Example 1 to conduct continuous ethylene dimerization and trimerization reactions, with all other process conditions identical to Example 1. However, after 200 hours of operation, the pipelines from the reactor to the quencher and from the quencher to the filter section became clogged. Upon disassembling the pipelines, reactor, and filter, numerous filamentous polymer deposits were found, clogging the discharge valve and pipelines. Cleaning the apparatus and pipelines required significant manpower and resources.

[0086] The results of Examples 1 and Comparative Examples 1-4 show that selecting other ether compounds as polymerization inhibitors significantly reduces the activity of ethylene dimerization and ethylene trimerization, as well as the selectivity of the products 1-butene and 1-hexene. PE content remains above 0.8%, and the operating time is within 1400 hours. Without polymerization inhibitors, pipeline blockage and large amounts of solid deposition in the reactors quickly occur. However, selecting pyrrole and its derivatives as ligands for the ethylene trimerization catalyst, by providing lone pairs of electrons to Cr and increasing Cr activity, not only improves the catalytic activity and selectivity of 1-hexene in ethylene trimerization but also acts as a polymerization inhibitor in ethylene dimerization. This significantly inhibits the high-polymerization of ethylene into polyethylene, making it easier for the reaction products to enter the separation and recovery unit for separation, extending the reaction cycle, and reducing energy consumption in pipelines, filters, and separation units. Simultaneously, pyrrole increases the selectivity of 1-hexene in ethylene dimerization, further improving the yield and selectivity of the 1-hexene product.

[0087] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A continuous process for co-producing 1-butene and 1-hexene, characterized in that, The equipment used in the process includes a polymerization reaction unit and a separation and recovery unit; The polymerization reaction unit includes reactor A for ethylene dimerization and reactor B for ethylene trimerization. The rear end of reactor A is connected to quenching reactor C, and the rear end of reactor B is connected to quenching reactor D. The separation and recovery unit includes a filter, a flash evaporation system, an ethylene recovery tower, a butene distillation tower, a hexene distillation tower, and a solvent recovery tower connected in sequence; the quenching kettles C and D are respectively connected to the filter; The process includes the following steps: 1) A mixed solution of ethylene, solvent, main catalyst A, and co-catalyst is continuously injected into reactor A to carry out ethylene dimerization reaction. Then the reaction solution overflows into quenching reactor C for quenching. 2) A mixed solution of ethylene, solvent, main catalyst B, and co-catalyst is continuously injected into reactor B to carry out the trimerization reaction of ethylene. Then the reaction solution overflows into quenching reactor D for quenching. 3) The quenched reaction liquids in quenching kettles C and D are simultaneously filtered and then enter the flash evaporation system. The waste catalyst is discharged from the bottom of the flash evaporation system. The remaining reaction liquid is processed in sequence through an ethylene recovery tower, a butene distillation tower, a hexene distillation tower, and a solvent recovery tower to recover ethylene and solvent to the raw material purification system for recycling. The products 1-butene and 1-hexene are collected. The main catalyst A is selected from titanium-containing organic compounds and pyrrole and its derivatives; The main catalyst B is selected from organic compounds containing trivalent chromium, nitrogen-containing ligands, and chlorinated alkanes; The nitrogen-containing ligand is selected from pyrrole and its derivatives; The co-catalyst is selected from one or more of trimethylaluminum, triethylaluminum, and triethylbutylaluminum; The titanium-containing organic compound is selected from one or more of tetrabutyl titanate, tetraethyl titanate, and tetraisopropyl titanate. The pyrrole and its derivatives are selected from one or more of pyrrole, methylpyrrole, and ethylpyrrole; The trivalent chromium-containing organic compound is selected from one or more of chromium isooctanoate, chromium trichloride, and chromium acetylacetonate; The chloroalkane is selected from one or more of dichloroethane, tetrachloroethane, and hexachloroethane.

2. The continuous co-production process of 1-butene and 1-hexene according to claim 1, characterized in that, The molar ratio of titanium-containing organic matter and pyrrole and its derivatives in the main catalyst A is 1:(2~6); The molar ratio of the titanium-containing organic compound to the co-catalyst is 1:(4~10). The molar ratio of trivalent chromium organic matter to nitrogen-containing ligands in the main catalyst B is 1:(3~6). The molar ratio of the trivalent chromium-containing organic compound to the chlorinated alkanes is 1:(6~10). The molar ratio of the trivalent chromium-containing organic compound to the co-catalyst is 1:(60~120).

3. The continuous co-production process for 1-butene and 1-hexene according to claim 1, characterized in that, The ethylene in step 1) is 15 wt% to 50 wt% of the mixed solution; The ethylene in step 2) is 15 wt% to 50 wt% of the mixed solution.

4. The continuous co-production process of 1-butene and 1-hexene according to claim 1, characterized in that, The temperature of the reactor A is 40℃~60℃, and the pressure is 2~6 MPa; The temperature of the reactor B is 100℃~140℃, and the pressure is 2~6 MPa.

5. The continuous co-production process of 1-butene and 1-hexene according to claim 1, characterized in that, In the equipment used in the process, a feed pipeline is provided at the bottom of the reactor A for feeding ethylene, solvent, main catalyst A and co-catalyst; The bottom of the reactor B is equipped with a feed pipeline for feeding ethylene, solvent, main catalyst B and co-catalyst; The reaction vessel A is connected to the quenching vessel C via an overflow pipeline in the middle of the vessel; The reaction vessel B is connected to the quenching vessel D via an overflow pipeline in the middle of the vessel.

6. The continuous co-production process of 1-butene and 1-hexene according to claim 1, characterized in that, In the equipment used in the process, both the top of the quenching vessel C and the quenching vessel D are equipped with quenching agent feed lines; The flash evaporation system is connected to a waste catalyst recovery device at the bottom.

7. The continuous co-production process of 1-butene and 1-hexene according to claim 1, characterized in that, In the equipment used in the process, a recovery pipeline is installed at the top of the ethylene recovery tower for the recovery and recycling of ethylene. The top of the butene distillation column is equipped with a recovery pipeline for collecting the product 1-butene; The top of the hexene distillation column is equipped with a recovery pipeline for collecting the product 1-hexene; The top of the solvent recovery tower is equipped with a recovery pipeline for solvent recovery and recycling. The top of the flash evaporation system is connected to the middle of the ethylene recovery tower; The bottom of the ethylene recovery tower is connected to the middle of the butene distillation tower; The bottom of the butene distillation column is connected to the middle of the hexene distillation column; The bottom of the hexene distillation column is connected to the middle of the solvent recovery column; The bottom of the solution recovery tower is connected to a heavy component recovery device.

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