A method and production apparatus for preparing a halogenated alkane based on a telomerization reaction

Abstract

A method and production device for preparing halogenated alkane based on telomerization reaction relate to the technical field of chemical raw material manufacturing; the method for preparing halogenated alkane based on telomerization reaction comprises the following steps: uniformly mixing carbon tetrachloride, an iron-based composite catalyst, acetonitrile and a surfactant to obtain a premix; the premix system comprises, based on the weight of CCl4, 0.1-5wt% of the iron-based composite catalyst, 0-5wt% of acetonitrile and 0.01-10wt% of the surfactant; the iron-based composite catalyst comprises iron powder and phosphonate, and the particle size of the iron powder is greater than or equal to 200 mesh; olefin monomers are added to the premix, and telomerization reaction is carried out under the conditions of a reaction temperature of 70-150 DEG C and a pressure of 0.3-1.5 MPa to obtain a halogenated alkane product. The iron powder with a specific particle size is used in cooperation with a specific amount of surfactant, which can effectively reduce the aggregation and sedimentation of the iron powder in the reaction system, improve the production efficiency and product selectivity, does not need to add soluble iron salt, has low production cost and is easy to separate and recover.

Description

Technical Field

[0001] This invention relates to the field of chemical raw material manufacturing technology, and in particular to a method and production apparatus for preparing haloalkanes based on telomerization reaction. Background Technology

[0002] Haloalkanes are mainly prepared by telomerization reactions of alkenes or haloalkenes with corresponding halogenated telomerizing agents (RX). For example, when preparing C3-C4 haloalkanes using carbon tetrachloride as a telomerizing agent, the main chemical synthetic routes for the telomerization reaction include:

[0003] These telomerization reactions were initially prepared using free radical initiators (such as organic peroxides and azo compounds). However, due to problems such as large initiator dosage, insufficient precision in reaction selectivity control, and stringent conditions, those skilled in the art gradually developed reaction systems with "catalytic" characteristics. Among them, transition metal catalytic systems can achieve milder reaction conditions (lower temperature and pressure), better selectivity, and fewer side reactions, and their dosage is far less than that of traditional initiators, thus gaining widespread application.

[0004] Transition metal catalysis systems mainly include copper salts / complexes and iron-based catalysts. Copper salts / complexes exhibit high selectivity for oligomers, but require expensive organic ligands, resulting in high costs. Furthermore, they are difficult to separate and recover, cannot be recycled, and are therefore less economical and environmentally friendly. Iron-based catalysts, on the other hand, are cheaper, more environmentally friendly, and less toxic, making them an ideal choice for developing sustainable chemical processes.

[0005] Common iron-based catalysts are mainly homogeneous catalytic systems of inorganic iron salts or iron complexes, which have low selectivity, are difficult to recover, and have extremely high production costs. To control production costs and improve selectivity, heterogeneous catalytic systems using iron powder and soluble iron salts have been proposed in existing technologies. For example, patent application US20040225166A1 proposes a method for preparing 1,1,1,3-tetrachloropropane, which uses a co-catalytic system of metallic iron, soluble iron salt, and organophosphate ester. This system can promote the addition of carbon tetrachloride to olefins under mild conditions, significantly improving the selectivity and yield of the 1,1,1,3-tetrachloropropane product. However, iron powder has poor dispersion in the reaction system and is prone to aggregation during continuous production, leading to decreased production efficiency and product selectivity. This makes it unsuitable for continuous production in tubular reactors, requiring batch or semi-continuous operation in reaction vessels, and necessitates the additional supply of soluble iron salts to meet production requirements. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects and shortcomings of the prior art and provide a method for preparing haloalkanes based on telomerization reaction, which can suppress the agglomeration of iron powder in the reaction system, improve production efficiency and product selectivity, is suitable for continuous production, and does not require the introduction of soluble iron salts, thus reducing production costs.

[0007] Another object of the present invention is to provide a continuous flow production apparatus for preparing haloalkanes based on telomerization reaction.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution: This invention protects a method for preparing haloalkanes based on telomerization, comprising the following steps: S1, carbon tetrachloride, iron-based composite catalyst, acetonitrile and surfactant are mixed evenly to obtain a premix; Based on the weight of CCl4, the premix system includes: 0.1-5 wt% iron-based composite catalyst, 0-5 wt% acetonitrile, and 0.01-10 wt% surfactant; the iron-based composite catalyst includes iron powder and phosphonate, the particle size of the iron powder is ≥200 mesh, and the mass ratio of the iron powder to the surfactant is (1-100):1; S2, olefin monomers are added to the premix, and a telomerization reaction is carried out under the conditions of reaction temperature 70-150℃ and pressure 0.3-1.5MPa to obtain haloalkanes.

[0009] In some embodiments, the mass ratio of the iron powder to the surfactant is (3-50):1; preferably (10-50):1, more preferably (10-30):1.

[0010] In some embodiments, the iron powder has a particle size of 200-2000 mesh, preferably 400-2000 mesh.

[0011] In some embodiments, the molar ratio of iron to phosphonate in the iron-based composite catalyst is 1:(0.8-1.2).

[0012] In some embodiments, the olefin monomer is selected from C2-C4 olefins and / or C2-C4 haloolefins; specifically, the C2-C4 haloolefin is selected from vinyl chloride, 3,3,3-trifluoropropylene (R1243zf) and 2-chloro-3,3,3-trifluoropropylene (R1233xf).

[0013] In some embodiments, the molar ratio of carbon tetrachloride to olefin monomer is 1:(0.1-1); preferably 1:(0.8-1).

[0014] In some embodiments, the phosphonate is selected from at least one of tributyl phosphonate, dibutyl phosphonate, triethyl phosphonate, trimethyl phosphonate, or triphenyl phosphonate.

[0015] In some embodiments, the surfactant is selected from at least one of N-vinylamide polymers, fatty acids, sorbitan fatty acid esters, organosilicon compounds, polyoxyethylene ethers, sulfonates, polysorbates, fatty alcohols, polyvinyl alcohols, quaternary ammonium salts, alkyl polysaccharides, alkanolamides, or betaine surfactants.

[0016] Preferably, the surfactant is selected from at least one of N-vinylamide polymers, alkyl polyglycosides, and polyoxyethylene ethers.

[0017] In some embodiments, the surfactant is selected from polyvinylpyrrolidone (PVP), oleic acid, sodium dodecylbenzenesulfonate (SDBS), sorbitan monopalmitate (Span 40), sorbitan monostearate (Span 60), and sorbitan monooleate (Span 40). 80), at least one of the following: silicone polyether copolymer (Dow Corning 749), polyethylene glycol octylphenyl ether (Trappon X-100), FS-30, polyoxyethylene sorbitan monolaurate (Tween-20), polyoxyethylene sorbitan monopalmitate (Tween-40), polyoxyethylene sorbitan monostearate (Tween-60), polyoxyethylene sorbitan monooleate (Tween-80), dodecyltrimethylammonium bromide (DTAB), dodecyl alcohol, polyvinyl alcohol, sodium dodecyl sulfate (SDS), fatty alcohol polyoxyethylene ether (AEO), octylphenol polyoxyethylene ether (OP-10), coconut oil fatty acid diethanolamide (DEA), polyoxyethylene-polyoxypropylene block copolymer, alkyl polysaccharide glycoside (APG), hexadecyltrimethylammonium bromide (CTAB), or 3-[(3-cholamidopropyl)dimethylamino]propanesulfonic acid inner salt (CHAPS).

[0018] Preferably, the surfactant is selected from polyvinylpyrrolidone (PVP), polyoxyethylene-polyoxypropylene block copolymer (Planick F-68), and alkyl polysaccharide glycoside (APG).

[0019] In some embodiments, the reaction temperature of the telomerization reaction is 90-110°C.

[0020] In some of these embodiments, the pressure of the telomerization reaction is 0.8-1.2 MPa.

[0021] A continuous flow production apparatus for preparing haloalkanes based on telomerization reaction, for implementing the method for preparing haloalkanes based on telomerization reaction, the apparatus comprising: The batching unit is used to mix raw materials other than olefin monomers evenly. The reaction unit is connected to the output end of the batching unit and is provided with an inlet for introducing olefin monomers for telomerization reaction. The separation unit is connected to the output of the reaction unit and is used for the separation and purification of haloalkane products, and the separated catalyst is refluxed to the feed unit.

[0022] In some embodiments, the reaction unit is selected from a static tubular reactor or a dynamic tubular reactor.

[0023] In some embodiments, the separation unit includes an iron powder filtration structure, a first distillation column, and a second distillation column; The iron powder filtration structure is connected to the output end of the reaction unit and is used to filter and separate iron powder. The filtered iron powder solid phase is returned to the batching unit. The first distillation column is connected to the liquid phase output end of the iron powder filter structure and is used to separate acetonitrile and unreacted carbon tetrachloride. The light components obtained by distillation are returned to the batching unit. The second distillation column is connected to the heavy component output end of the first distillation column and is used to separate haloalkanes. The heavy components obtained from the distillation are sent back to the batching unit.

[0024] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a method for preparing haloalkanes based on telomerization reaction, using iron powder as the main catalyst and phosphonate ester as the co-catalyst. By using iron powder of a specific particle size in combination with a small amount of surfactant, the aggregation of iron powder in the reaction system can be effectively reduced, thereby improving production efficiency and product selectivity. This method is suitable for continuous production, eliminates the need for adding soluble iron salts, and reduces production costs. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a continuous flow production apparatus for preparing haloalkanes based on telomerization reaction according to the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0027] The raw materials used in the following examples and comparative examples are as follows: PVP: Polyvinylpyrrolidone, K90.

[0028] Oleic acid: Commercially available.

[0029] Organosilicon polyether copolymer: Dow Corning 749.

[0030] Tween-40: Polyoxyethylene sorbitan monopalmitate.

[0031] PEO-PPO: Polyoxyethylene-polyoxypropylene block copolymer: Pronnick, F-68.

[0032] OP-10: Octylphenol polyoxyethylene ether, commercially available.

[0033] APG: Alkyl polysaccharide; BASF, 215 UP.

[0034] Examples 1-17 and Comparative Examples 1-5 This embodiment verifies the dispersion performance of iron powder (5wt%) in carbon tetrachloride solution at extreme dosages. The results are shown in Table 1.

[0035] Experimental method: Add 2000g CCl4 to a beaker. Based on the weight of CCl4, add the iron powder and surfactant in the formula of Table 1. Start stirring at 400rpm for 1h. Then let it stand and precipitate for 24h and observe the iron powder agglomeration effect. Take 500 g of the middle layer of the suspension layer after standing and record it as sample 1. Perform rotary evaporation on sample 1. Record the mass of residual iron powder after rotary evaporation as M1. The iron powder dispersion coefficient = (4*M1 / total mass of iron powder added to beaker)*100%. The larger the iron powder dispersion coefficient, the better the dispersion effect.

[0036] Table 1

[0037] The results show that, at extreme dosages (5 wt%), iron powder in carbon tetrachloride solution has a high dispersion coefficient when the particle size of the iron powder is ≥600 mesh and the mass ratio of iron powder to surfactant is less than 50:1; when the surfactant is preferably polyvinylpyrrolidone (PVP), it has good dispersibility for iron powder in carbon tetrachloride solution system.

[0038] Examples 18-25 and Comparative Examples 6-8 This embodiment and comparative example provide a series of methods for preparing haloalkanes based on telomerization reaction, using ethylene to prepare 1,1,1,3-tetrachloropropane (R250fb) by passing it into a carbon tetrachloride premix containing a catalytic system.

[0039] In this embodiment and the comparative example, 600-mesh iron powder is used as the main catalyst in the catalytic system, and a surfactant is added to produce R250fb. The surfactant is PVP, and the mass ratio of iron powder to surfactant is 14:1 to ensure stable operation during continuous production.

[0040] The catalytic system and carbon tetrachloride premix contain, based on the weight of CCl4, 0.8 wt% iron-based composite catalyst and 0.01 wt% surfactant; the iron-based composite catalyst is iron powder and phosphonate in a molar ratio of 1:1.

[0041] The types of phosphonates in different embodiments and comparative examples are shown in Table 2.

[0042] Specifically, the method for preparing haloalkanes based on telomerization reaction in this embodiment and the comparative example adopts... Figure 1 The production of the aforementioned reaction apparatus includes the following steps: 1. The above-mentioned catalytic system and carbon tetrachloride premix are prepared in the mixing tank 1, and then fed into the tubular reactor 2. The tubular reactor 2 is equipped with an electric heating mantle to control the reaction temperature and a pressure sensor controller 10 to control the introduction of the feed gas (ethylene) and maintain the pressure of the reaction system. The reaction condition parameters of the tubular reactor 2 in this embodiment are shown in Table 2.

[0043] 2. The material after the reaction in tubular reactor 2 is completed is sent to the separation unit, which includes an iron powder filtration device 3, a first distillation column 4 (bottom temperature 126℃, top temperature 37℃, reflux ratio 4:1, atmospheric pressure) and a second distillation column 6 (bottom temperature 108℃, top temperature 34℃, reflux ratio 8:3, pressure -0.08mPa). The iron powder filtration device 3 is connected to the output end of the tubular reactor 4 and is used to filter and separate iron powder. The filtered iron powder solid phase is collected in the iron powder intermediate tank 11 and then sent back to the batching tank 1. The first distillation column 4 is connected to the liquid phase output end of the iron powder filter 3 to separate acetonitrile and unreacted carbon tetrachloride. The light components obtained from distillation are collected in the CCl4-acetonitrile intermediate tank 9 and then returned to the feed tank 1. Both the first distillation column 4 and the second distillation column 6 are equipped with a top condenser 14, a bottom reboiler 13, and a centrifugal pump 12 to ensure continuous and stable operation of the distillation process. The bottom of the first distillation column 4 is connected to the first heavy component storage tank 5, which is connected to the second distillation column 6. The light components obtained from distillation in the second distillation column 6 are haloalkanes, which are collected in the refined R250fb storage tank 7. The heavy components (phosphonates and surfactants) obtained from distillation are collected in the second heavy component storage tank 8 and then returned to the feed tank 1 for reuse. The CCl4 conversion rate and product selectivity of the produced products are statistically analyzed, and the results are shown in Table 2.

[0044] Table 2

[0045] Comparative Example 9 A method for preparing haloalkanes based on telomerization reaction differs from Example 1 in that: this comparative example uses a conventional reactor for batch reaction with a stirring rate of 300 rpm; the molar ratio of iron powder: ferric chloride: tributyl phosphonate is 4:1:5; and the tributyl phosphonate accounts for 0.66 wt% of the CCl4 mass. The CCl4 conversion rate was tested to be 81.7%, and the product selectivity was 95.3%.

[0046] The results show that the method for preparing haloalkanes based on telomerization reaction of the present invention can achieve continuous production in a tubular reactor. By improving the iron powder dispersion coefficient in the reaction system, the aggregation of iron powder is reduced, thereby improving production efficiency and product selectivity, and no additional ferric chloride is required; its CCl4 conversion rate is ≥63.7%, and its product selectivity is ≥95.3%. In Comparative Example 9, when the stirring device of the reactor is used to improve the iron powder dispersibility, it has higher production efficiency and product selectivity, but this device is not suitable for the continuous production of haloalkanes.

[0047] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing haloalkanes based on telomerization reaction, characterized in that, Includes the following steps: S1, carbon tetrachloride, iron-based composite catalyst, acetonitrile and surfactant are mixed evenly to obtain a premix; Based on the weight of CCl4, the premix system includes: 0.1-5 wt% iron-based composite catalyst, 0-5 wt% acetonitrile, and 0.01-10 wt% surfactant; the iron-based composite catalyst includes iron powder and phosphonate, the particle size of the iron powder is ≥200 mesh, and the mass ratio of the iron powder to the surfactant is (1-100):1; S2, olefin monomers are added to the premix, and a telomerization reaction is carried out under the conditions of reaction temperature 70-150℃ and pressure 0.3-1.5MPa to obtain haloalkanes.

2. The method for preparing haloalkanes based on telomerization reaction according to claim 1, characterized in that, The mass ratio of the iron powder to the surfactant is (10-50):

1.

3. The method for preparing haloalkanes based on telomerization reaction according to claim 1, characterized in that, The molar ratio of iron to phosphonate in the iron-based composite catalyst is 1:(0.8-1.2).

4. The method for preparing haloalkanes based on telomerization reaction according to claim 1, characterized in that, The olefin monomers are selected from C2-C4 olefins and / or C2-C4 haloolefins.

5. The method for preparing haloalkanes based on telomerization reaction according to claim 1, characterized in that, The phosphonate is selected from at least one of tributyl phosphonate, dibutyl phosphonate, triethyl phosphonate, trimethyl phosphonate, or triphenyl phosphonate.

6. The method for preparing haloalkanes based on telomerization reaction according to claim 1, characterized in that, The surfactant is selected from at least one of N-vinylamide polymers, fatty acids, sorbitan fatty acid esters, organosilicon compounds, polyoxyethylene ethers, sulfonates, polysorbates, fatty alcohols, polyvinyl alcohols, quaternary ammonium salts, alkyl polysaccharides, alkanolamides, or betaine surfactants.

7. The method for preparing haloalkanes based on telomerization reaction according to claim 6, characterized in that, The surfactant is selected from at least one of polyvinylpyrrolidone, oleic acid, sodium dodecylbenzenesulfonate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, organosilicon polyether copolymer, polyethylene glycol octylphenyl ether, FS-30, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, dodecyltrimethylammonium bromide, dodecyl alcohol, polyvinyl alcohol, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, coconut oil fatty acid diethanolamide, polyoxyethylene-polyoxypropylene block copolymer, alkyl polysaccharide glycoside, hexadecyltrimethylammonium bromide, or 3-[(3-cholamidopropyl)dimethylamino]propanesulfonic acid inner salt.

8. A continuous flow production apparatus for preparing haloalkanes based on telomerization reaction, characterized in that, For implementing the method for preparing haloalkanes based on telomerization reaction according to any one of claims 1-7, the apparatus comprises: The batching unit is used to mix raw materials other than olefin monomers evenly. The reaction unit is connected to the output end of the batching unit and is provided with an inlet for introducing olefin monomers for telomerization reaction. The separation unit is connected to the output of the reaction unit and is used for the separation and purification of haloalkane products, and the separated catalyst is refluxed to the feed unit.

9. The continuous flow production apparatus for preparing haloalkanes based on telomerization reaction according to claim 8, characterized in that, The reaction unit is selected from either a static tubular reactor or a dynamic tubular reactor.

10. The continuous flow production apparatus for preparing haloalkanes based on telomerization reaction according to claim 8, characterized in that, The separation unit includes an iron powder filtration structure, a first distillation column, and a second distillation column; The iron powder filtration structure is connected to the output end of the reaction unit and is used to filter and separate iron powder. The filtered iron powder solid phase is returned to the batching unit. The first distillation column is connected to the liquid phase output end of the iron powder filter structure and is used to separate acetonitrile and unreacted carbon tetrachloride. The light components obtained by distillation are returned to the batching unit. The second distillation column is connected to the heavy component output end of the first distillation column and is used to separate haloalkanes. The heavy components obtained from the distillation are sent back to the batching unit.

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