Method for continuously producing 1, 1, 1, 3-tetrachloropropane

Abstract

The invention relates to a method for continuously producing 1, 1, 1, 3-tetrachloropropane, which comprises the following steps: adopting a loop reactor in which a beam pipe is arranged in the reactor, mixing reaction raw materials ethylene and carbon tetrachloride at a Venturi nozzle at the lower part of the reactor through a gas circulation loop and a liquid circulation loop outside the reactor, and spraying into the reactor filled with a main catalyst. A cocatalyst and a chelating agent are added into a carbon tetrachloride raw material in advance, are pumped into a liquid loop by a feeding pump and then enter a reactor. Reaction raw materials are circularly stirred under the action of a beam pipe in the reactor, so that solid, liquid and gas phases are fully mixed. By adopting the method disclosed by the invention, the selectivity and the production efficiency of the 1, 1, 1, 3-tetrachloropropane can be greatly improved, and the method also has the advantages of simplicity in operation, environment friendliness, long service life of the catalyst and low cost.

Description

Technical Field

[0001] The present invention relates to a method for continuously producing 1,1,1,3-tetrachloropropane, belonging to the field of chemical engineering technology. Background Art

[0002] 1,1,1,3-Tetrachloropropane is an important fine chemical, and is a key raw material for synthesizing trichloropropene and trifluoropropene. It is also a good degreasing agent, paint stripper and solvent. Carbon tetrachloride is a by-product of methane chloride plants. According to the Montreal Protocol, the production and consumption of carbon tetrachloride have been completely stopped except for raw material use, reagent use and special exemption use. Therefore, the comprehensive utilization of carbon tetrachloride, such as synthesizing it into tetrachloropropane, has very important practical significance.

[0003] Industrially, 1,1,1,3-tetrachloropropane is mainly synthesized by telomerization of ethylene and carbon tetrachloride:

[0004] CH2=CH2 + CCl4 → CCl3-CH2-CH2Cl

[0005] Traditional industrial production methods use iron as the main catalyst, and ferric chloride and phosphate ester compounds as co-catalysts, and use a batch reactor. In the batch reactor, the reactants are mixed by a stirring paddle, and the mixing efficiency is limited, which is prone to cause the self-polymerization reaction of local ethylene, generating more by-products such as 1,1,1,5-tetrachloropentane and 1,3,3,5-tetrachloropentane. The product selectivity is low, generally the selectivity of 1,1,1,3-tetrachloropropane is below 90%. At the same time, a large amount of heavy substances are produced as by-products, resulting in a great waste of resources; using a batch reactor, due to repeated heating and cooling operations, the energy consumption is high and the reaction efficiency is low; moreover, the iron catalysts currently used in industry are mainly iron powder or iron rings. When using iron powder or iron rings as catalysts, it is easy to form phosphates with the phosphate groups of the co-catalyst and cover the surface of the iron powder or iron rings, resulting in the gradual loss of catalyst activity, and the catalyst cannot be reused for a long time. Chinese Patent CN111056913A discloses a method for continuously producing 1,1,1,3-tetrachloropropane, which uses metallic iron or supported iron as the main catalyst, and uses phosphate ester or phosphite as the co-catalyst, and uses a fixed-bed reactor, claiming that it can continuously produce 1,1,1,3-tetrachloropropane. Chinese Patent CN114605226A discloses a method for continuously producing 1,1,1,3-tetrachloropropane, which uses metallic iron or supported iron as the main catalyst, and uses phosphate ester, phosphite or formamide-based small molecule organic amine as the co-catalyst, and uses a fixed-bed reactor. The feeding method can be gas-liquid co-current or gas-liquid cross-flow, claiming that it can continuously produce 1,1,1,3-tetrachloropropane.

[0006] However, although the above method can achieve the continuous production of 1,1,1,3-tetrachloropropane, due to the use of a fixed-bed reactor, the problem of phosphate deposition on the surface of the solid catalyst still exists, and the problem of the activity stability of the catalyst has not been completely solved, so continuous production reactions cannot be carried out for a long time. Moreover, when using a fixed-bed for continuous production, the main catalyst needs to be frequently replaced after being consumed, which increases the complexity of the operation and there is a need for further improvement. Summary of the Invention

[0007] In view of the above situation of the prior art, the inventors of the present invention have conducted in-depth and extensive research in the field of 1,1,1,3-tetrachloropropane synthesis and found that by using a double-circulation mixing reaction of a gas raw material circulation loop and a liquid raw material circulation loop, and arranging two layers of beam tubes inside the reactor, the mixing and separation of the gas-liquid two phases inside the reactor can be greatly promoted, which can not only improve the reaction conversion rate and selectivity, but also realize industrialized continuous production. At the same time, in cooperation with a preferred cocatalyst, the consumption of the main catalyst is reduced, and a chelating agent is added to effectively prevent the formation of phosphate on the catalyst surface, improving the environmental protection of the continuous reaction. The present invention is completed based on the above findings.

[0008] Therefore, the object of the present invention is to provide a method for continuously producing 1,1,1,3-tetrachloropropane. On the basis of using a double-circulation mixing reaction of a gas raw material circulation loop and a liquid raw material circulation loop, the reaction conditions and the types of cocatalysts are optimized to increase the service life of the main catalyst, and a chelating agent is added to effectively prevent the formation of phosphate on the catalyst surface, improving the environmental protection of the continuous reaction.

[0009] The technical solution for achieving the above object of the invention can be summarized as follows:

[0010] A method for continuously producing 1,1,1,3-tetrachloropropane, which is carried out by using a device for continuously producing 1,1,1,3-tetrachloropropane. The device includes a reactor with beam tubes arranged inside. A feeding port and a gas check valve are arranged at the upper part of the reactor. A Venturi nozzle is arranged at the bottom of the reactor. A condenser with a discharge port is connected in the middle of the reactor. The gas check valve is connected to an ethylene feed port and is connected to the Venturi nozzle through an ethylene circulation loop. The Venturi nozzle is also connected to a feed pump through a circulation pump and is connected to the middle of the reactor through a carbon tetrachloride liquid circulation loop;

[0011] The method includes the following steps:

[0012] Carbon tetrachloride, a main catalyst, a co-catalyst, and a chelating agent are added into the reactor through the feeding port. The circulation pump is started. After the liquid forms a circulation loop, ethylene is introduced through the ethylene feeding port and heated. The unreacted ethylene re-enters the bottom of the reactor from the upper part of the reactor through the gas check valve, the gas circulation loop, and the Venturi nozzle. The unreacted carbon tetrachloride re-enters the bottom of the reactor from the middle part of the reactor through the carbon tetrachloride liquid circulation loop, the circulation pump, and the Venturi nozzle. When the conversion rate of carbon tetrachloride in the reactor is between 70% and 85%, the feeding pump and the discharging port are opened simultaneously. The feeding pump pumps in a mixed solution of carbon tetrachloride, the co-catalyst, and the chelating agent for continuous production. The crude product of 1,1,1,3-tetrachloropropane is condensed by the condenser and then produced from the discharging port.

[0013] According to the present invention, preferably, the reactor is a columnar reactor, and the bottom of the reactor is conically arranged.

[0014] According to the present invention, preferably, the beam tube is arranged in the vertical direction; preferably, there are two or more layers of beam tubes.

[0015] According to the present invention, preferably, the feeding mass ratio of carbon tetrachloride to ethylene is 10:0.5 - 2; more preferably, the feeding mass ratio of carbon tetrachloride to ethylene is 10:1 - 1.5.

[0016] According to the present invention, preferably, the main catalyst is at least one of iron filings, iron rings, iron wires, iron pellets, and iron sands; more preferably, the main catalyst is any one selected from iron rings, iron pellets, and iron sands.

[0017] According to the present invention, preferably, the mass ratio of the main catalyst to carbon tetrachloride is 1:20 - 100, and further preferably 1:40 - 60.

[0018] According to the present invention, preferably, the co-catalyst includes phosphates, phosphites, mixtures or complexes of phosphates with ferric chloride or ferrous chloride, mixtures or complexes of phosphites with ferric chloride or ferrous chloride, or mixtures of two or more of the above substances;

[0019] Preferably, the phosphates include at least one of tributyl phosphate, triethyl phosphate, tripropyl phosphate, and dibutyl phosphate; the phosphites include at least one of tributyl phosphite and triethyl phosphite;

[0020] Preferably, the co-catalyst is a mixture of ferric chloride and tributyl phosphate with a mass ratio of 1:2 - 6.

[0021] According to the present invention, preferably, the mass ratio of the co-catalyst to carbon tetrachloride is 1:100 - 1000, and further preferably 1:100 - 200.

[0022] According to the present invention, preferably, the chelating agent is at least one of crown ether, disodium ethylenediaminetetraacetate (EDTA), and sodium nitrilotriacetate (NTA); more preferably, the crown ether is 15-crown-5, 18-crown-6, or dicyclohexano-18-crown (ether)-6;

[0023] Preferably, the mass ratio of carbon tetrachloride to the chelating agent is 1000:0.1 to 5.

[0024] According to the present invention, preferably, the reaction pressure is 0.35 to 0.85 MPa, more preferably 0.45 to 0.65 MPa;

[0025] Preferably, the reaction temperature condition is 90 to 130 °C, more preferably 105 to 120 °C.

[0026] According to the present invention, preferably, the residence time of the reaction liquid in the reactor is 2 to 10 hours, more preferably 2 to 4 hours;

[0027] Preferably, the reaction is carried out under loop circulation, and the loop circulation time is 20 to 200 seconds, more preferably 20 to 50 seconds.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] 1. Low cost and good economy. In the present invention, the main catalyst does not need to be taken out of the reactor after use and is recycled until it is completely consumed, reducing the use cost of the catalyst.

[0030] 2. Simple process. In the continuous production of the present invention, no additional operations are required, significantly simplifying the operation process. The continuous production time is long, and the reactor can be reused without cleaning after use.

[0031] 3. Green and environmentally friendly. The main catalyst of the present invention can be recycled and used for a long time, avoiding the problem of solid waste treatment generated during the production process of 1,1,1,3-tetrachloropropane at present.

[0032] 4. High reaction efficiency. In the continuous production state of the present invention, the conversion rate of carbon tetrachloride is above 75%, and the selectivity of 1,1,1,3-tetrachloropropane is above 97.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the main structure of the device for continuously producing 1,1,1,3-tetrachloropropane according to the present invention.

[0034] Wherein: 1. Ethylene feed inlet; 2. Gas check valve; 3. Ethylene circulation loop; 4. Condenser; 5. Venturi nozzle; 6. Discharge port; 7. Carbon tetrachloride liquid circulation loop; 8. Beam tube; 9. Circulation pump; 10. Feed pump; 11. Charging port; 12. Reactor. Detailed implementation mode

[0035] The present invention provides a method for continuously producing 1,1,1,3-tetrachloropropane, which is carried out by using a device for continuously producing 1,1,1,3-tetrachloropropane. As Figure 1 shown, the device for continuously producing 1,1,1,3-tetrachloropropane includes a reactor 12 internally provided with a beam tube 8. A charging port 11 and a gas check valve 2 are arranged at the upper part of the reactor 12. A venturi nozzle 5 is arranged at the bottom of the reactor 12. A condenser 4 with a discharge port 6 connected is arranged in the middle of the reactor 12. The gas check valve 2 is connected to the ethylene feed inlet 1 and is connected to the venturi nozzle 5 through an ethylene circulation loop 3. The venturi nozzle 5 is also connected to the feed pump 10 through a circulation pump 9 and is connected to the middle of the reactor 12 through a carbon tetrachloride liquid circulation loop 7.

[0036] The method includes the following steps:

[0037] Carbon tetrachloride, a main catalyst, a co-catalyst, and a chelating agent are added into the reactor 12 through the charging port 11. The circulation pump 9 is started. After the liquid forms a circulation loop, ethylene is introduced through the ethylene feed inlet 1 and heated to raise the temperature. The unreacted ethylene enters the bottom of the reactor 12 again from the upper part of the reactor 12 through the gas check valve 2, the gas circulation loop 3, and the venturi nozzle 5. The unreacted carbon tetrachloride enters the bottom of the reactor 12 again from the middle of the reactor 12 through the carbon tetrachloride liquid circulation loop 7, the circulation pump 9, and the venturi nozzle 5. When the conversion rate of carbon tetrachloride in the reactor 12 is between 70% and 85%, the feed pump 10 and the discharge port 6 are opened simultaneously. The feed pump 10 pumps in a mixed solution of carbon tetrachloride, a co-catalyst, and a chelating agent for continuous production. The crude product of 1,1,1,3-tetrachloropropane is condensed by the condenser 4 and produced from the discharge port 6.

[0038] In one or more preferred implementation modes, the material of the reactor 12 is carbon steel. The reactor 12 is a columnar reactor, and the bottom of the reactor 12 is conically arranged.

[0039] In one or more preferred implementation modes, the beam tube 8 is arranged vertically; preferably, there are two or more layers of beam tubes 8.

[0040] In one or more preferred implementation modes, the mass ratio of the carbon tetrachloride and ethylene fed is 10:0.5 - 2; more preferably, the mass ratio of the carbon tetrachloride and ethylene fed is 10:1 - 1.5.

[0041] In one or more preferred embodiments, the main catalyst is at least one of iron filings, iron rings, iron wires, iron pellets, and iron sands; more preferably, the main catalyst is selected from any one of iron rings, iron pellets, and iron sands.

[0042] In one or more preferred embodiments, the mass ratio of the main catalyst to carbon tetrachloride is 1:20 to 100, and more preferably 1:40 to 60. This ratio is the material ratio controlled in the first feeding from the feeding port 11.

[0043] In one or more preferred embodiments, the co-catalyst includes phosphates, phosphites, mixtures or complexes of phosphates with ferric chloride or ferrous chloride, mixtures or complexes of phosphites with ferric chloride or ferrous chloride, or mixtures of two or more of the above substances;

[0044] Preferably, the phosphates include at least one of tributyl phosphate, triethyl phosphate, tripropyl phosphate, and dibutyl phosphate; the phosphites include at least one of tributyl phosphite and triethyl phosphite;

[0045] Preferably, the co-catalyst is a mixture of ferric chloride and tributyl phosphate with a mass ratio of 1:2 to 6.

[0046] In one or more preferred embodiments, the mass ratio of the co-catalyst to carbon tetrachloride is 1:100 to 1000, and more preferably 1:100 to 200.

[0047] In one or more preferred embodiments, the chelating agent is at least one of crown ethers, disodium ethylenediaminetetraacetate (EDTA), and sodium nitrilotriacetate (NTA); more preferably, the crown ether is 15-crown-5, 18-crown-6, or dicyclohexano-18-crown (ether)-6;

[0048] Preferably, the mass ratio of carbon tetrachloride to the chelating agent is 1000:0.1 to 5.

[0049] According to the present invention, the material ratios among the above carbon tetrachloride, co-catalyst, and chelating agent refer to the material ratios controlled in the first feeding from the feeding port 11. And, the material ratios of the carbon tetrachloride, co-catalyst, and chelating agent pumped into the mixed solution by the feed pump 10.

[0050] In one or more preferred embodiments, the reaction pressure is 0.35 to 0.85 MPa, and more preferably 0.45 to 0.65 MPa;

[0051] Preferably, the reaction temperature condition is 90 to 130 °C, and more preferably 105 to 120 °C.

[0052] In one or more preferred embodiments, the residence time of the reaction liquid in the reactor 12 is 2 to 10 hours, more preferably 2 to 4 hours;

[0053] Preferably, the reaction is carried out under loop circulation, and the loop circulation time is 20 to 200 seconds, more preferably 20 to 50 seconds.

[0054] The basic idea of the present invention:

[0055] The reaction raw materials, ethylene and carbon tetrachloride, are mixed at the venturi nozzle 5 at the bottom of the reactor 12 through the gas circulation loop 3 outside the reactor 12 and the carbon tetrachloride liquid circulation loop 7, and then enter the interior of the reactor 12 filled with the solid main catalyst. A beam tube 8 is provided inside the reactor 12 to strengthen the contact of the materials. Compared with the traditional loop reactor, the present invention can greatly promote the mixing and separation of the gas-liquid two-phase inside the reactor 12 by setting the beam tube 8, enabling the continuous production of the loop reactor. Moreover, the contact between carbon tetrachloride and ethylene is strengthened by the internal circulation in the reactor 12, avoiding the self-polymerization reaction of ethylene, reducing the content of by-products, and increasing the selectivity of the target product 1,1,1,3-tetrachloropropane. At the same time, by adopting the loop reactor, the mixing effect of the gas-liquid-solid three-phase is greatly improved, the reaction rate is increased, the pressure of this reaction is indirectly reduced, the proportion of by-product polymers is reduced, and the selectivity of the product tetrachloropropane is increased again. Compared with the traditional production process, when using the device of the present invention for production, the reaction pressure will be lower than 0.65 MPa. At this pressure, the high-polymer by-products generated due to the self-polymerization of ethylene are extremely low. By using the preferred cocatalyst, on the one hand, it cooperates with the reactor 12 to enable long-term continuous production, and on the other hand, the mixed use of ferric chloride and the like in the cocatalyst can reduce the consumption of the main catalyst and increase the service life of the main catalyst. By adding a small amount of chelating agent, the formation of phosphates on the surface of the catalyst can be effectively prevented. A small amount of precipitate impurities will be discharged with the materials, which will not affect the normal production in the reactor 12, and greatly extend the service life of the catalyst. Moreover, under the strong mixing of the reactor 12, no impurities will adhere to the surface of the main catalyst, and the main catalyst iron rings and the like will be slowly consumed until they disappear, and no solid waste will remain in the reactor. Compared with the traditional production process, the operation is more convenient and more environmentally friendly.

[0056] The present invention will be further described below in conjunction with specific implementation cases, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative solutions, improvement solutions, and equivalent solutions that may be included within the scope of the claims.

[0057] Example 1

[0058] A method for continuously producing 1,1,1,3 - tetrachloropropane, which is carried out by using a device for continuously producing 1,1,1,3 - tetrachloropropane, and the volume of its main reaction area is 50 liters. As Figure 1 shown, the device includes a reactor 12 with a beam tube 8 arranged inside. A feeding port 11 and a gas check valve 2 are arranged at the upper part of the reactor 12. A Venturi nozzle 5 is arranged at the bottom of the reactor 12. A condenser 4 with a discharge port 6 is connected in the middle of the reactor 12. The gas check valve 2 is connected to an ethylene feed port 1 and is connected to the Venturi nozzle 5 through an ethylene circulation loop 3. The Venturi nozzle 5 is also connected to a feed pump 10 through a circulation pump 9 and is connected to the middle of the reactor 12 through a carbon tetrachloride liquid circulation loop 7. In this embodiment, the material of the reactor 12 is carbon steel, and the reactor 12 is a columnar reactor, and the bottom of the reactor 12 is arranged in a conical shape. The beam tube 8 is arranged vertically, and there are two layers of beam tubes 8.

[0059] The method for continuously producing 1,1,1,3 - tetrachloropropane includes the following steps:

[0060] (1) Prepare a co - catalyst. Mix 100 g of ferric trichloride with 300 g of tributyl phosphate to form a complex as the co - catalyst;

[0061] (2) Put 40 kg of carbon tetrachloride, 1 kg of iron sand, 400 g of co - catalyst, and 40 g of EDTA into the reactor 12. After closing the reactor 12, carry out vacuum treatment;

[0062] (3) The reactor 12 starts loop circulation for 30 seconds to pre - heat the reactor 12.

[0063] (4) Feed ethylene to start the reaction. Control the temperature of the reactor 12 at 105 - 115 °C and the pressure inside the reactor 12 at 0.65 MPa;

[0064] (5) After 2 hours, monitor that the conversion rate of carbon tetrachloride in the reactor 12 reaches 75%. Open the feed pump 10 and pump in a mixed solution of carbon tetrachloride and co - catalyst with a chelating agent ratio of 100:1:0.1, and at the same time control the feed ratio of carbon tetrachloride to ethylene at 10:1. Open the discharge port 6 to collect the crude 1,1,1,3 - tetrachloropropane. Keep the residence time of carbon tetrachloride reaction at 2 hours.

[0065] (6) Continuously produce for 500 hours, monitor the reaction pressure, and take samples for detection every hour.

[0066] The pressure inside the reactor 12 is 0.50 - 0.55 MPa. The sample is analyzed by gas chromatography. Results: The average conversion rate of raw material ethylene is 99.6%, the average conversion rate of carbon tetrachloride is 75.3%, the selectivity of 1,1,1,3 - tetrachloropropane is 97.9%, and the purity of the 1,1,1,3 - tetrachloropropane obtained after rectification is greater than 99.95%.

[0067] Compared with the traditional loop reactor, by setting two layers of beam tubes 8 in the present invention, the mixing and separation of the gas - liquid two - phase inside the reactor 12 can be greatly promoted, further enhancing the continuous production effect of the reactor 12. It increases the residence time of ethylene gas under a single cycle and greatly improves the conversion rate of raw material ethylene.

[0068] Example 2

[0069] As described in Example 1, the difference is: The device for continuously producing 1,1,1,3 - tetrachloropropane, the volume of its main reaction area is 600 liters, and the steps are as follows:

[0070] (1) Prepare the co - catalyst. Mix 1 kg of ferric chloride with 5 kg of tributyl phosphate to form a complex solid as the co - catalyst;

[0071] (2) Put 500 kg of carbon tetrachloride, 10 kg of iron sand, 5 kg of co - catalyst, and 500 g of EDTA into the reactor 12. After closing the reactor 12, perform vacuum treatment;

[0072] (3) The reactor 12 starts loop circulation with a circulation time of 30 seconds to pre - heat the reactor 12;

[0073] (4) Feed ethylene to start the reaction. Control the temperature of the reactor 12 at 110 - 115 °C and control the pressure inside the reactor 12 at 0.70 MPa;

[0074] (5) After 2 hours, when the conversion rate of carbon tetrachloride inside the reactor 12 reaches 75%, open the feed pump 10 to pump in a mixed solution with the ratio of carbon tetrachloride, co - catalyst, and chelating agent being 100:1:0.1, and at the same time control the feed ratio of carbon tetrachloride to ethylene at 10:1. Open the discharge port 6 to collect the crude 1,1,1,3 - tetrachloropropane. Keep the residence time of carbon tetrachloride in the reaction for 2 hours.

[0075] (6) Continuously produce for 2000 hours, monitor the pressure inside the reactor 12, and take samples for detection every hour.

[0076] The pressure inside reactor 12 is 0.50 - 0.55 MPa. The sample is analyzed by gas chromatography. Results: The average conversion rate of raw material ethylene is 99.7%, the average conversion rate of carbon tetrachloride is 77.8%, the selectivity of 1,1,1,3 - tetrachloropropane is 98.1%, and the purity of the 1,1,1,3 - tetrachloropropane obtained after distillation is greater than 99.95%.

[0077] Comparative Example 1

[0078] In this comparative example, the reactor is a traditional loop reactor. There is no beam tube installed in the main reactor, and the volume of its main reaction area is 50 liters. The operation process is as follows:

[0079] (1) Prepare the cocatalyst. Mix 100 g of ferric chloride with 300 g of tributyl phosphate to form a complex, which is used as the cocatalyst;

[0080] (2) Put 40 kg of carbon tetrachloride, 1 kg of iron sand, 400 g of cocatalyst, and 40 g of EDTA into the reactor. After sealing the reactor, perform a vacuum treatment;

[0081] (3) The loop reactor starts loop circulation. The circulation time is 30 seconds, and the reactor is preheated;

[0082] (4) Feed ethylene and start the reaction. Control the reactor temperature at 105 - 115 °C and control the pressure inside the reactor at 0.65 MPa;

[0083] (5) After 2 hours, monitor that the conversion rate of carbon tetrachloride in the reactor reaches 75%. Open the feed pump and pump in a mixed solution with a ratio of carbon tetrachloride, cocatalyst, and chelating agent of 100:1:0.1, while controlling the feed ratio of carbon tetrachloride to ethylene at 10:1. Open the discharge port and collect the crude 1,1,1,3 - tetrachloropropane. Keep the residence time of carbon tetrachloride reaction at 2 hours.

[0084] (6) Continuously produce for 200 hours, monitor the reaction pressure, and take samples for testing every hour.

[0085] The pressure inside the reactor is 0.65 - 0.85 MPa. The sample is analyzed by gas chromatography. Results: The average conversion rate of raw material ethylene is 95.5%, the average conversion rate of carbon tetrachloride is 74.3%, the selectivity of 1,1,1,3 - tetrachloropropane is 94.8%, and the purity of the 1,1,1,3 - tetrachloropropane obtained after distillation is greater than 99.95%.

[0086] Comparative Example 2

[0087] As described in Example 2, the difference is that: The cocatalyst and chelating agent are not used in combination. The operation process is as follows:

[0088] (1) Put 40 kg of carbon tetrachloride, 1 kg of iron sand, and 400 g of triethyl phosphite into the reactor. After closing the reactor, perform a vacuum treatment.

[0089] (2) The reactor 12 starts the loop circulation for 30 seconds to preheat the reactor 12.

[0090] (3) Feed ethylene to start the reaction. Control the temperature of the reactor 12 at 105 - 115 °C and the pressure inside the reactor 12 at 0.65 MPa.

[0091] (4) After 2 hours, monitor that the conversion rate of carbon tetrachloride in the reactor 12 reaches 75%. Open the feed pump 10 to pump in a mixed solution with a ratio of carbon tetrachloride to triethyl phosphite of 100:1, and at the same time control the feed ratio of carbon tetrachloride to ethylene at 10:1. Open the discharge port 6 to collect the crude 1,1,1,3 - tetrachloropropane. Keep the residence time of carbon tetrachloride in the reaction for 2 hours.

[0092] (5) Continuously produce for 200 hours, monitor the reaction pressure, and take samples for detection every hour.

[0093] The pressure inside the reactor 12 is 0.45 - 0.90 MPa. As the production progresses, the pressure inside the reactor 12 gradually increases. The sample is analyzed by gas chromatography. Results: The average conversion rate of raw material ethylene is 99.5%, the average conversion rate of carbon tetrachloride is 67.3%, and the selectivity of 1,1,1,3 - tetrachloropropane is 91.4%.

[0094] Comparative Example 3

[0095] The reactor in this comparative example is a continuous stirred - tank reactor with a volume of 50 liters, and the reaction solution is mixed by a mechanical stirring device. Do not add EDTA during feeding, and the others are the same as in Example 2. Continuously produce, monitor the pressure inside the reactor, and take samples for detection every hour.

[0096] After operating for 50 hours, the pressure inside the reactor starts to gradually increase to 1.2 MPa. The sample is analyzed by gas chromatography. Results: The average conversion rate of raw material ethylene is 87.4%, the average conversion rate of carbon tetrachloride is 70%, the selectivity of 1,1,1,3 - tetrachloropropane gradually decreases from 96.2% to 92.3%, and the reaction cannot operate stably for a long time.

[0097] Comparative Example 4

[0098] The reactor in this comparative example is a fixed-bed tubular reactor with a main reaction zone volume of 1 liter. The reactor is filled with iron ring catalysts. Carbon tetrachloride and the cocatalyst triethyl phosphite are pumped in by a feed pump with a mass ratio of 100:1. The reactor temperature is controlled at 115 - 120 °C, the pressure in the reactor is controlled at 0.6 - 0.7 MPa, the feed ratio of carbon tetrachloride to ethylene is controlled at 10:1, and the residence time of the reaction is controlled at 2 hours. Continuous production is carried out, and samples are taken for testing every hour.

[0099] After running for 100 hours, the samples are analyzed by gas chromatography. The results show that the average conversion rate of the raw material ethylene is 87.7%, and the selectivity of 1,1,1,3-tetrachloropropane is 94.3%. However, the average conversion rate of carbon tetrachloride gradually decreases from 50% at the beginning to 40%, and shows a continuous downward trend, so this reaction cannot operate stably for a long time.

Claims

1. A method for continuously producing 1,1,1,3-tetrachloropropane, which is carried out using a device for continuously producing 1,1,1,3-tetrachloropropane, characterized in that: The device comprises a reactor (12) having a beam tube (8) disposed therein, a feed port (11) and a gas one-way valve (2) disposed at the top of the reactor (12), a venturi nozzle (5) disposed at the bottom of the reactor (12), a condenser (4) provided with a discharge port (6) connected to the middle of the reactor (12), the gas one-way valve (2) connected to an ethylene feed port (1) and connected to the venturi nozzle (5) via an ethylene circulation loop (3), the venturi nozzle (5) further connected to a feed pump (10) via a circulation pump (9) and connected to the middle of the reactor (12) via a carbon tetrachloride liquid circulation loop (7); The method comprises the following steps: Carbon tetrachloride, a main catalyst, a co-catalyst and a chelating agent are added to the reactor (12) through the feed port (11), and the circulation pump (9) is started. After the liquid forms a circulation loop, ethylene is introduced through the ethylene feed port (1) and heated to a high temperature. Unreacted ethylene re-enters the bottom of the reactor (12) from the upper part of the reactor (12) through the gas check valve (2), the gas circulation loop (3) and the venturi nozzle (5). Unreacted carbon tetrachloride re-enters the bottom of the reactor (12) from the middle part of the reactor (12) through the carbon tetrachloride liquid circulation loop (7), the circulation pump (9) and the venturi nozzle (5). When the carbon tetrachloride conversion rate in the reactor (12) is between 70% and 85%, the feed pump (10) and the discharge port (6) are opened simultaneously. The feed pump (10) pumps a mixed liquid of carbon tetrachloride, the co-catalyst and the chelating agent to perform continuous production. The crude 1,1,1,3-tetrachloropropane product is condensed by the condenser (4) and then produced from the discharge port (6).

2. The method for continuously producing 1,1,1,3-tetrachloropropane according to claim 1, characterized in that: The reactor (12) is a column reactor, and the bottom of the reactor (12) is arranged in a conical shape.

3. The method for continuously producing 1,1,1,3-tetrachloropropane according to claim 1, characterized in that: The beam tube (8) is arranged in a vertical direction.

4. The method for continuously producing 1,1,1,3-tetrachloropropane according to claim 1, characterized in that: The beam tube (8) is provided with more than two layers.

5. The method for continuously producing 1,1,1,3-tetrachloropropane according to any one of claims 1 to 4, characterized in that: The feed mass ratio of carbon tetrachloride to ethylene is 10:0.5-2, preferably 10:1-1.

5.

6. The method for continuously producing 1,1,1,3-tetrachloropropane according to any one of claims 1 to 4, characterized in that: The main catalyst is at least one of iron filings, iron rings, iron wires, iron pellets, and iron sand; Preferably, the mass ratio of the main catalyst to carbon tetrachloride is 1:20~100.

7. The method for continuously producing 1,1,1,3-tetrachloropropane according to any one of claims 1 to 4, characterized in that: The co-catalyst includes phosphate, phosphite, a mixture or complex of phosphate and ferric chloride or ferrous chloride, a mixture or complex of phosphite and ferric chloride or ferrous chloride, or a mixture of two or more of the above substances; Preferably, the phosphate ester includes at least one of tributyl phosphate, triethyl phosphate, tripropyl phosphate, and dibutyl phosphate; the phosphite includes at least one of tributyl phosphite and triethyl phosphite; Preferably, the mass ratio of the co-catalyst to carbon tetrachloride is 1:100-1000.

8. The method for continuously producing 1,1,1,3-tetrachloropropane according to any one of claims 1 to 4, characterized in that: The chelating agent is at least one of crown ether, disodium ethylenediaminetetraacetic acid, and sodium nitrilotriacetate; preferably, the crown ether is 15-crown-5, 18-crown-6, and dicyclohexane-18-crown (ether)-6; Preferably, the mass ratio of carbon tetrachloride to the chelating agent is 1000:0.1-5.

9. The method for continuously producing 1,1,1,3-tetrachloropropane according to any one of claims 1 to 4, characterized in that: The reaction pressure is 0.35~0.85MPa, preferably 0.45~0.65MPa; Preferably, the reaction temperature is 90-130°C, preferably 105-120°C.

10. The method for continuously producing 1,1,1,3-tetrachloropropane according to any one of claims 1 to 4, characterized in that: The residence time of the reaction liquid in the reactor 12 is 2 to 10 hours, preferably 2 to 4 hours; Preferably, the reaction is carried out under a loop cycle, and the loop cycle time is 20 to 200 seconds.

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