Process for preparation of halogenated olefins and integrated multi-layer reactor

Abstract

The invention provides a method for preparing halogenated olefin and an integrated multi-layer reactor, the method is carried out by using the integrated multi-layer reactor, and the method comprises the following steps: step 1, conveying C2-C12 halogenated alkane and an alkaline aqueous solution into the integrated multi-layer reactor from a raw material inlet located at the bottom of the reactor, in each reaction layer in the reaction section, under the condition of stirring and mixing, an elimination reaction is carried out while rising, a gas-phase material and a liquid-phase material are generated, and the gas-phase material contains a product C2-C12 halogenated olefin; 2, the liquid-phase material flows out from a liquid outlet in the lower portion of the separation section, and the gas-phase material flows out from a gas outlet in the upper portion of the separation section. According to the invention, more sufficient dispersion and mixing are realized in a shorter time by a simple process flow, backmixing and energy consumption are reduced, and the reaction efficiency and the product yield are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical industry, and more particularly to a method for preparing halogenated olefins and an integrated multi-layer reactor for the reaction. BACKGROUND

[0002] Various halogenated olefins have a wide range of uses in the field of chemical synthesis and other fields, and have extremely high importance and commercial value. As a most typical example, 1,1-dichloroethylene is a very important chemical raw material and fine chemical precursor, which can be used to prepare high value-added fine chemicals such as polyvinylidene chloride membrane, fluorine-based refrigerant, polyvinylidene fluoride membrane, fluorine-based rubber, etc. Therefore, there is a high demand for various halogenated olefins represented by 1,1-dichloroethylene in the relevant field, but unfortunately, the halogenated olefin synthesis technology in the prior art has considerable defects, which seriously restricts the development of the chemical industry using halogenated olefins as raw materials and precursors.

[0003] Specifically, the halogenated olefin synthesis process in the prior art is mainly to make the corresponding halogenated alkane undergo an elimination reaction in the presence of an alkaline aqueous solution to generate the target product halogenated olefin. For example, 1,1-dichloroethylene is mainly prepared by using 1,1,2-trichloroethane and NaOH aqueous solution as raw materials, and the reaction equation is as follows:

[0004] CHCl2-CH2Cl + NaOH (aq.) → CCl2=CH2 + NaCl + H2O

[0005] These prior art methods all have the problem of serious backmixing of reactants, resulting in a long residence time of the reaction (which can be as long as 2.5-3 hours). In addition, in order to improve the reaction conversion rate and the yield of the target product, the prior art methods often recycle the material that has undergone the reaction, and the recycling ratio is generally about 30-300. However, such a degree of material recycling not only increases the energy consumption of the circulating pump, dilutes the concentration of the reactants in the reaction system, reduces the reaction rate and the conversion rate per unit time, but also further prolongs the residence time of the material in the reaction equipment, further deteriorating the yield per unit time. In addition, according to the reports in the prior art, neither a tubular reactor nor other types of reactors can provide sufficient, continuous and uniform high-intensity shear to the oil-water two-phase reactants that are not miscible with each other in the reaction system, resulting in poor mixing and dispersion of the reactants, which is not conducive to achieving excellent conversion rate in the reaction.

[0006] In summary, there is still a need to develop a new process to overcome the above-mentioned defects. SUMMARY

[0007] The inventors of the present application have developed the reaction equipment and method of the present application through a large number of extensive and in-depth researches, unexpectedly solved the above-mentioned problems existing in the prior art, and thus completed the present application.

[0008] The first aspect of the present application provides an integrated multi-layer reactor, which comprises a reaction section and a separation section, the separation section being arranged above the reaction section, the reaction section comprising 3-15 reaction layers and at least one stirring device, the stirring device being provided with at least one set of stirring blades in each reaction layer, and annular baffles being arranged above and below each reaction layer; the separation section has a gas outlet and a liquid outlet, the gas outlet being located at the upper part of the separation section, and the liquid outlet being located at the lower part of the separation section; the bottom of the reactor is provided with a raw material inlet.

[0009] According to one embodiment of the first aspect of the present application, the stirring device has a shaft arranged along the longitudinal axis of the reactor and a plurality of sets of stirring blades arranged on the shaft, the top end of the stirring shaft being arranged in a motor above the outside of the reactor, and the bottom end of the stirring shaft being fixed to the head of the bottom of the reactor.

[0010] According to another embodiment of the first aspect of the present application, the stirring device is provided with one set of stirring blades in each reaction layer.

[0011] According to another embodiment of the first aspect of the present application, the shape of the blades is selected from at least one of the following: turbine type, straight-blade disc type, inclined-blade open type, curved type, flexible type, wave-belt type, or a combination thereof.

[0012] According to another embodiment of the first aspect of the present application, each set of blades comprises 2-12 blades.

[0013] According to another embodiment of the first aspect of the present application, the ratio of the inner diameter of at least a part of the separation section to the inner diameter of the reaction section is 1.1:1 to 2.5:1. According to another embodiment of the first aspect of the present application, the ratio of the height of the separation section to the height of the reaction section is 1:10 to 5:10.

[0014] According to another embodiment of the first aspect of the present application, each reaction layer comprises 2-5 baffles arranged longitudinally on the inner wall of the reactor. According to another embodiment of the first aspect of the present application, the ratio of the transverse dimension of the baffles to the inner diameter of the reaction layer is 1:100 to 10:100. According to another embodiment of the first aspect of the present application, the ratio of the longitudinal dimension of the baffles to the height of the reaction layer is 50:100 to 90:100. According to another embodiment of the first aspect of the present application, the ratio of the inner opening diameter of the annular baffles to the inner diameter of the reaction layer is 50:100 to 80:100.

[0015] According to another embodiment of the first aspect of the present application, the reactor comprises an interlayer disposed outside the reactor wall, a fluid inlet disposed at the upper portion of the interlayer, and a fluid outlet disposed at the bottom portion of the interlayer.

[0016] A second aspect of the present application provides a method for producing a haloalkene, which uses the integrated multi-layer reactor according to the first aspect of the present application, the method comprising:

[0017] Step one: feeding a C2-C12 haloalkane and an aqueous alkaline solution into the integrated multi-layer reactor from a feedstock inlet located at the bottom portion of the reactor, and allowing the elimination reaction to occur in each reaction layer in the reaction section while ascending with stirring and mixing to form a gas phase material and a liquid phase material, wherein the gas phase material contains a product C2-C12 haloalkene;

[0018] Step two: allowing the liquid phase material to flow out from a liquid outlet located at the lower portion of the separation section, and allowing the gas phase material to flow out from a gas outlet located at the upper portion of the separation section;

[0019] The C2-C12 haloalkane contains at least two halogen atoms, and the C2-C12 haloalkene contains at least one halogen atom.

[0020] According to an embodiment of the second aspect of the present application, the method further comprises a pre-mixing step before the step one, wherein the C2-C12 haloalkane and the aqueous alkaline solution are input into a pre-mixer to form a feedstock mixture.

[0021] According to another embodiment of the second aspect of the present application, the pre-mixer is selected from the group consisting of an eductor, an impingement mixer, a static mixer, or a combination thereof.

[0022] According to another embodiment of the second aspect of the present application, the eductor is a jet pump, a venturi, or a combination thereof.

[0023] According to another embodiment of the second aspect of the present application, the impingement mixer is a multi-nozzle impingement mixer, preferably a double-nozzle opposed impingement mixer.

[0024] According to another embodiment of the second aspect of the present application, the static mixer is selected from the group consisting of an SV-type static mixer, an SK-type static mixer, an SX-type static mixer, an SL-type static mixer, an SH-type static mixer, or a combination thereof.

[0025] According to another embodiment of the second aspect of the present application, the C2-C12 haloalkane is 1,1,2-trichloroethane, and the C2-C12 haloalkene is 1,1-dichloroethene.

[0026] According to another embodiment of the second aspect of the present application, the ratio of the molar amount of C2-C12haloalkane fed into the reactor to the molar amount of base in the aqueous alkaline solution is 0.3:1 to 3:1.

[0027] According to another embodiment of the second aspect of the present application, the mass percentage of base in the aqueous alkaline solution is 5-25 mass% based on the mass of the aqueous alkaline solution.

[0028] According to another embodiment of the second aspect of the present application, the temperature in the reaction section of the reactor is 65-95°C, the reaction pressure is 1-5 atm, and the residence time of the reaction feed in the reactor is 1 second to 60 minutes.

[0029] In the following detailed description of the application, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments of the application. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a reaction mechanism diagram for preparing 1,1-dichloroethene from 1,1,2-trichloroethane according to an embodiment of the present application.

[0031] Figure 2 is a schematic diagram of the method and apparatus according to an embodiment of the present application.

[0032] Figure 3 shows the detailed structure of the integrated multi-layer reactor.

[0033] Figure 4 shows the gas chromatography characterization diagram of the product prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0034] "Ranges" are disclosed herein in terms of both a lower limit and an upper limit. Ranges can each include one or more lower limit, and one or more upper limit. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined by any combination of lower and upper limits are included and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0035] In the present application, unless otherwise stated, the numerical range "a-b" represents a shorthand for "any real combination of the numbers a to b", wherein a and b are both real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been listed herein, "0-5" is just a shorthand for these numerical combinations.

[0036] In the present application, unless otherwise stated, all embodiments and preferred embodiments mentioned herein can be combined with each other to form new technical solutions.

[0037] In the present application, unless otherwise stated, all technical features and preferred features mentioned herein can be combined with each other to form new technical solutions.

[0038] In the present application, unless otherwise stated, "comprising" mentioned herein represents open-ended, which can also be closed. For example, "comprising" can mean that it can also contain other components not listed, or only include the listed components.

[0039] The C2-C12 haloalkane used in the method of the present application contains two or more halogen atoms per molecule, for example, contains 2-12 halogen atoms, or contains 2-10 halogen atoms, or contains 2-8 halogen atoms, or contains 2-6 halogen atoms, or contains 2-4 halogen atoms, and most preferably contains 2 or three halogen atoms. In the present application, the halogen atoms are selected from: fluorine, chlorine, bromine, iodine, or a combination thereof. According to an exemplary embodiment of the present application, the C2-C12 haloalkane is selected from one or more of the following: 1,1-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1-dichloropropane, 1,1,2-trichloropropane, 1,1,2,2-tetrachloropropane.

[0040] The C2-C12 haloalkene used in the method of the present application contains at least one carbon-carbon double bond and at least one halogen atom per molecule, for example, contains 1-11 halogen atoms, or contains 1-9 halogen atoms, or contains 1-7 halogen atoms, or contains 1-5 halogen atoms, or contains 1-3 halogen atoms, and most preferably contains 1 or 2 halogen atoms. In the present application, the halogen atoms are selected from: fluorine, chlorine, bromine, iodine, or a combination thereof. According to an embodiment of the present application, the C2-C12 haloalkene contains 1-3 carbon-carbon double bonds per molecule, or contains 1-2 carbon-carbon double bonds, or contains one carbon-carbon double bond. According to an exemplary embodiment of the present application, the C2-C12 haloalkane is selected from one or more of the following: 1-chloroethylene, 1,1-dichloroethylene, 1,1,2-trichloroethylene, 1-chloropropene, 1,1-dichloropropene, 1,1,2-trichloropropene.

[0041] In Figure 1 In the exemplary embodiment shown, 1,1,2-trichloroethane undergoes an elimination reaction in the presence of a base (e.g., NaOH) to produce the target product 1,1-dichloroethene and byproducts NaCl and water. Next is Figure 1 The reaction shown is an example to illustrate the method of the present application, but the scope of protection of the method of the present application is not limited to this. All reactions that can produce a target halogenated alkene by reacting a halogenated alkane in the presence of a base solution can be carried out by the method and reactor of the present application and the corresponding benefits can be obtained.

[0042] According to one embodiment of the present application, as shown in Figure 2 The reaction raw materials, halogenated alkane (e.g., 1,1,2-trichloroethane) and alkaline aqueous solution, are first preheated and fed into a premixer, where the oil phase (halogenated alkane) and the water phase (alkaline aqueous solution) are mixed and dispersed sufficiently, and then the mixed raw materials thus obtained are fed into the integrated multi-layer reactor for reaction.

[0043] According to one embodiment of the present application, the "preheating" includes preheating the raw material halogenated alkane (e.g., 1,1,2-trichloroethane) and the alkaline aqueous solution to a temperature close to the reaction temperature, for example, 60-100°C, or 65-95°C, or 70-92°C, or 75-90°C, or 80-85°C, respectively.

[0044] According to one embodiment of the present application, the alkaline aqueous solution is an aqueous solution of an alkaline agent selected from one or more of the following: sodium hydroxide, potassium hydroxide, lithium hydroxide. According to another embodiment of the present application, the concentration of the alkaline agent in the alkaline aqueous solution is 5-25 mass%, or 8-22 mass%, or 10-20 mass%, or 15-20 mass%, based on the total mass of the alkaline aqueous solution.

[0045] According to another embodiment of the present application, in the premixing step, the molar ratio of the halogenated alkane to the alkaline agent contained in the alkaline aqueous solution is 0.3:1 to 3:1, for example, 0.5:1 to 2.5:1, or 0.6:1 to 2:1, or 0.7:1 to 1.5:1, or 0.8:1 to 1.2:1.

[0046] According to another embodiment of the present application, the pre-mixer is selected from one or more of the following: jet mixer, impingement mixer, static mixer. Preferably, the jet mixer is selected from one or more of the following: jet pump mixer, Venturi mixer; the impingement mixer is preferably a multi-nozzle impingement mixer, such as a double-nozzle opposed impingement mixer; examples of the static mixer include SV-type static mixer, SK-type static mixer, SX-type static mixer, SL-type static mixer, SH-type static mixer, etc., or a combination of the above mixers can be used.

[0047] According to another embodiment of the present application, as shown in Figure 2 After the pre-mixing step, the raw material mixture obtained by the pre-mixing step is fed into the integrated multi-layer reactor for reaction.

[0048] The reactor of the present application is an "integrated" reactor, which is fundamentally different from the prior art devices formed by connecting multiple independent reactors in series. Figure 3 A schematic diagram of a reactor according to an embodiment of the present application is shown. The reactor has a reactor wall (also referred to as "cylinder") enclosing a space, which includes a reaction section at the lower part of the reactor and a separation section above the reaction section.

[0049] The reaction section can be divided into multiple reaction layers, for example, 3-15 reaction layers, preferably 7-11 reaction layers. According to an embodiment of the present application, each reaction layer has the same height.

[0050] Each reaction layer is provided with an annular partition plate above and below. The annular partition plate is fixed to the inner wall of the reactor on the outside, and has a circular opening on the inside, so that the material in the reactor can only flow between the reaction layers through the circular opening. Preferably, each annular partition plate is horizontally arranged. According to an embodiment of the present application, the cross-section of the reactor in the horizontal direction is circular, and the ratio of the diameter of the circular opening of the annular partition plate to the inner diameter of the cross-section of the reaction section in the horizontal direction is 50:100 to 80:100, or 60:100 to 75:100, or 65:100 to 70:100; preferably 55:100 to 65:100, more preferably 60:100.

[0051] At least one set of stirring paddles is provided in each reaction layer, more preferably one set of stirring paddles is provided at the center (both transverse and longitudinal center) of each reaction layer. For example, in Figure 3In the reactor of the embodiment shown, the reactor comprises a stirring device, the rotating shaft of which penetrates the reactor along the central longitudinal axis of the reactor, the upper part of the rotating shaft being connected to the motor and the bottom part being fixed to the head of the reactor bottom to avoid swinging when rotating at high speed. The rotating shaft can have stirring paddles in the separation section or can have no stirring paddles. The rotating shaft has 3-15 groups of stirring paddles in the reaction section, preferably the number of groups of stirring paddles in the reaction section is the same as the number of reaction layers, and a group of stirring paddles is arranged in the center of each reaction layer.

[0052] Each group of stirring paddles can comprise 2-12 blades, for example 3-10 blades, preferably 5-10 blades. According to one embodiment of the present application, each blade can have the following shapes: turbine type, straight-blade disc type, inclined-blade open type, curved type, flexible type, wave-belt type, or a combination thereof. The shapes of these blades are known in the art.

[0053] According to another inventive point of the present application, at least one baffle is arranged on the inner wall of the reactor in each reaction layer, for example 2-5 baffles are arranged on the inner wall of the reactor in each reaction layer, preferably 3-4 baffles. Preferably, in each reaction layer, all baffles are uniformly distributed on the inner wall of the reactor.

[0054] The shape of the baffle can be square or rectangular. According to one embodiment of the present application, the ratio of the transverse dimension of the baffle to the inner diameter of the reaction layer is 1:100 to 10:100, or 3:100 to 8:100, or 5:100 to 7:100; preferably 9:100 to 10:100, more preferably 10:100. According to another embodiment of the present application, the ratio of the longitudinal dimension of the baffle to the height of the reaction layer is 50:100 to 90:100, or 60:100 to 85:100, or 70:100 to 80:100; preferably 80:100.

[0055] According to one embodiment of this application, at least a portion of the separation section located above the reaction section has a lateral dimension (e.g., the inner diameter of the horizontal cross-section) larger than that of the reaction section to facilitate the escape of the reaction product haloolefin (e.g., 1,1-dichloroethylene gas) from the top of the reactor. According to a specific embodiment of this application, both the separation section and the reaction section have circular horizontal cross-sections, and the ratio of the inner diameter of the horizontal cross-section of at least a portion of the separation section to the inner diameter of the horizontal cross-section of the reaction section is 1.1:1 to 2.5:1, or 1.3:1 to 2.2:1, or 1.5:1 to 2:1. According to another embodiment of this application, the height ratio of the separation section to the reaction section is 1:10 to 5:10, or 1.5:10 to 4:10, or 2:10 to 1:3.

[0056] According to another embodiment of this application, the reactor further includes a jacket located outside the reactor wall, the jacket having a fluid inlet (e.g., located at the upper part of the jacket) and a fluid outlet (e.g., located at the bottom of the jacket). Preferably, the jacket completely covers the reaction section, more preferably the jacket is substantially the same size as or slightly larger than the reaction section, so as to appropriately control the temperature of the reaction section during the reaction. The heat transfer fluid used in the jacket is selected from one or more of the following: water, steam, and heat transfer oil.

[0057] In addition to the aforementioned components and structures, the reactor also has a raw material inlet at the bottom of the reactor, a liquid material outlet below the separation section, and a gaseous material outlet at the top of the separation section.

[0058] like Figure 2 As shown, in the method of the present invention, the raw material mixture obtained in the premixing step enters the integrated multilayer reactor from the raw material inlet at the bottom of the reactor. Under the driving force of the continuously input raw material flow, it flows upward. The reactant flow is subjected to the action of annular baffles set above and below the reaction layer, baffles set at the edge of the reaction layer, and stirring blades set at the center of the reaction layer in each reaction layer. This allows the oil phase (halogenated alkanes) and the aqueous phase (alkaline aqueous solution) in the reactants to be fully mixed and dispersed throughout the reaction section. Under this effect, the reactants react simultaneously while being mixed, dispersed, and rising layer by layer, achieving excellent raw material conversion rate and target product yield with a shorter residence time.

[0059] After the reaction, the material rises to the separation section, the liquid phase in the material flows out from the liquid outlet, for example, by way of overflow, and is then subjected to cooling, NaCl separation, and organic waste treatment. The gas phase in the material (mainly containing the target product halogenated olefin, for example, 1,1-dichloroethylene) escapes from the gas outlet at the top of the reactor and can then be subjected to condensation, purification, refining, and the like as needed. These subsequent condensation, purification, refining, and the like post-treatment processes and related conditions are known in the art.

[0060] According to another embodiment of the present application, the temperature in the reaction section of the reactor is 65-95°C, or 70-90°C, preferably 75-85°C. According to another embodiment of the present application, the reaction pressure in the reactor is 1-5 atm, for example, 1-3 atm, preferably at atmospheric pressure. According to another embodiment of the present application, the residence time of the reaction feedstock in the reactor is 1 second to 60 minutes, for example, 5 seconds to 30 minutes, preferably 10 seconds to 15 minutes.

[0061] According to one embodiment of the present application, during the reaction, the originally immiscible oil phase and water phase are fully mixed and dispersed in each reaction layer, so that the size of the formed droplets is 1-1000 microns, preferably 10-100 microns.

[0062] According to another embodiment of the present application, the material is not circulated, that is, no intentionally designed circulation of any reacted material back to the reactor to undergo reaction again.

[0063] Applicants believe that the method and reactor of the present application can achieve the following effects:

[0064] 1. Compared with the prior art using a tubular reactor or multiple serial reaction kettles, the present application uses a simple structure and lower capital cost integrated multi-layer reactor, achieves more sufficient mixing and lower back mixing effect (the flow in the reactor of the present application is very close to plug flow in a tubular reactor), while the process flow is more concise and easier to operate and control.

[0065] 2. The present application does not need to use a large amount of material circulation as in the prior art, thereby significantly reducing energy consumption.

[0066] 3. The reactor of the present application is designed in a delicate manner, which can achieve complete reaction in a shorter time.

[0067] 4. The separation section of the present application can achieve gas-liquid separation during reaction with a simple design, achieving integration and simplification of the synthesis-separation process flow.

[0068] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0069] Example

[0070] All reactants used in the following examples were commercially available chemically pure reagents, and all water used was deionized water.

[0071] Example 1

[0072] In this embodiment, according to Figure 2 The method of the present invention is illustrated. The reactor used in this embodiment has... Figure 3 The reactor structure shown comprises nine reaction layers, each with identical dimensions and structural design. Specifically, each reaction layer is 20 cm high and has a 20 cm inner diameter cross-section. Annular baffles are positioned above and below each reaction layer, with adjacent layers sharing a single baffle. The diameter of the circular opening in the center of the baffle is 12 cm. Each reaction layer includes three rectangular baffles evenly distributed along the reactor's inner wall, each with a radial dimension of 2 cm and a height of 16 cm. Each reaction layer contains a set of oblique-blade open-type turbine propellers (each set includes 10 blades, each blade being 9 cm long).

[0073] The horizontal cross-section of the separation section is circular, with an inner diameter of 30 centimeters and a height of approximately 60 centimeters.

[0074] During the reaction, 1,1,2-trichloroethane preheated to 85°C (flow rate 36.5 mL / s) and a 20% NaOH aqueous solution (flow rate 68.3 mL / s) are respectively fed into a dual-nozzle opposed impact mixer for premixing and dispersion, so that the raw material mixture is conveyed from the raw material inlet at the bottom of the reactor into an integrated multilayer reactor.

[0075] The agitator in the reactor was set to rotate at 273 rpm. Low-pressure steam was introduced into the jacket to maintain the temperature of the reaction section of the reactor at 85°C. The residence time of the reactants in the reactor was 1 minute. An aqueous NaCl solution containing organic matter overflowed from the liquid outlet, while a gaseous phase mainly containing 1,1-dichloroethylene escaped from the gas outlet at the top of the reactor. The content of the target product was detected by gas chromatography (GC). Figure 4 The GC chromatogram of the gaseous product obtained in this embodiment is shown, and the total yield of the target product 1,1-dichloroethylene is calculated to be 99%.

[0076] In addition, the diameter of the small droplets (oil phase) dispersed in the reaction section was about 70 microns, which was measured by using an on-line laser droplet analysis technique during the reaction.

[0077] Comparative Example 1

[0078] The comparative example 1 used the same process conditions and equipment as the example 1, except that all the ring baffles, baffle plates and stirring blades in the reaction section of the reactor were removed. Here, the reactor was equivalent to a static mixing tube reactor with the same overall size.

[0079] The content of the target product was detected by using a gas chromatograph, and the total yield of the target product 1,1-dichloroethylene was calculated to be 50%. The diameter of the small droplets (oil phase) dispersed in the reaction section was about 70 microns, which was measured by using an on-line laser droplet analysis technique during the reaction.

[0080] Example 2

[0081] In this example, the method of the present application was implemented according to the scheme shown in FIG. 1. The reactor used in this example had the structure shown in FIG. 2, and the reaction section of the reactor included 9 reaction layers, each of which had the same size and structural design. Specifically, each reaction layer had a height of 20 cm, a cross-sectional inner diameter of 20 cm, a ring baffle above and below each reaction layer, and a ring baffle shared by adjacent reaction layers, a circular opening in the middle of the baffle with a diameter of 16 cm, three rectangular baffle plates in each reaction layer, which were evenly distributed on the inner wall of the reactor, a radial dimension of 1 cm and a height of 12 cm, and a set of inclined open turbine blades (each set including 10 blades, each blade having a length of 9 cm) in each reaction layer. Figure 2 Figure 3 The separation section had a circular cross-section in the horizontal direction with an inner diameter of 30 cm and a height of about 60 cm.

[0082] The separation section had a circular cross-section in the horizontal direction with an inner diameter of 30 cm and a height of about 60 cm.

[0083] During the reaction, 1,1,2-trichloroethane (flow rate of 36.5 ml / s) and 20% NaOH aqueous solution (flow rate of 68.3 ml / s) preheated to 85°C were respectively input into the double-nozzle opposed impingement mixer for pre-mixing and dispersion to obtain a raw material mixture, which was transported from the raw material inlet at the bottom of the reactor into the integrated multi-layer reactor.

[0084] ​The rotation speed of the stirrer in the reactor was set at 273 rpm, low pressure steam was inputted into the jacket to keep the temperature of the reaction section of the reactor at 85°C, and the residence time of the reactant stream in the reactor was 1 minute. The NaCl aqueous solution containing organic substances overflowed from the liquid outlet, and the gas phase mainly containing 1,1-dichloroethylene escaped from the gas outlet at the top of the reactor. The content of the target product in the gas phase was detected by gas chromatography, and the total yield of the target product 1,1-dichloroethylene was calculated to be 95%.

[0085] In addition, the diameter of the small droplets (oil phase) dispersed in the reaction section during the reaction was about 95 microns, which was measured by using an online laser droplet analysis technique.

[0086] From the above examples and comparative examples, it can be seen that, compared with the static mixing tube reactor with the same overall size, both Examples 1 and 2 using the specially designed reactor of the present application can achieve better dispersion and mixing effects, specifically, the droplet size of the small droplets (oil phase) in the reaction section during the reaction is observed to be smaller and more uniform, thereby achieving significantly improved target product yield. In addition, the inventors have found that, compared with Example 2, Example 1 can achieve further significantly improved dispersion efficiency (manifested as smaller oil phase droplets) and target product yield by the size design of the baffles and partitions thereof.

Claims

1. An integrated multi-layer reactor, the reactor comprising: a reaction section and a separation section arranged above the reaction section, the reaction section comprising 3-15 reaction layers and at least one stirring device, the stirring device being provided with at least one set of stirring blades in each reaction layer, and annular baffles being arranged above and below each reaction layer; the separation section having a gas outlet at the upper part of the separation section and a liquid outlet at the lower part of the separation section; the reactor being provided with a feedstock inlet at the bottom of the reactor.

2. The integrated multi-layer reactor of claim 1, wherein, the stirring device having a shaft arranged along the longitudinal axis of the reactor and a plurality of sets of stirring blades arranged on the shaft, the top end of the stirring shaft being arranged in a motor above the outside of the reactor, and the bottom end of the stirring shaft being fixed to the head of the reactor bottom; and / or the stirring device being provided with one set of stirring blades in each reaction layer; and / or the shape of the blades being selected from at least one of the following: turbine, straight-blade disc, pitched-blade open, curved, flexible, wave, or a combination thereof; and / or each set of blades comprising 2-12 blades.

3. The integrated multi-layer reactor of claim 1, wherein the ratio of the inner diameter of at least a part of the separation section to the inner diameter of the reaction section is: 1.1:1 to 2.5:1; the ratio of the height of the separation section to the height of the reaction section is: 1:10 to 5:

10.

4. The integrated multi-layer reactor of claim 1, wherein each reaction layer comprises 2-5 baffles arranged along the longitudinal direction on the inner wall of the reactor; and / or the ratio of the lateral dimension of the baffles to the inner diameter of the reaction layer is: 1:100 to 10:100; the ratio of the longitudinal dimension of the baffles to the height of the reaction layer is: 50:100 to 90:100; the ratio of the inner opening diameter of the annular baffles to the inner diameter of the reaction layer is: 50:100 to 80:

100.

5. The integrated multi-layer reactor of claim 1, wherein the reactor comprises a jacket arranged outside the wall of the reactor, a fluid inlet arranged at the upper part of the jacket, and a fluid outlet arranged at the bottom of the jacket.

6. A method for preparing a halogenated alkene, the method using the integrated multi-layer reactor according to any one of claims 1-5, the method comprising: Step 1: feeding C2-C12 halogenated alkane and aqueous alkali solution into the integrated multi-layer reactor from the feedstock inlet at the bottom of the reactor, and in each reaction layer in the reaction section, the elimination reaction occurs while ascending with stirring and mixing to form gas phase material and liquid phase material, the gas phase material containing the product C2-C12 halogenated alkene; Step 2: the liquid phase material flows out from the liquid outlet at the lower part of the separation section, and the gas phase material flows out from the gas outlet at the upper part of the separation section; the C2-C12 halogenated alkane contains at least two halogen atoms, and the C2-C12 halogenated alkene contains at least one halogen atom.

7. The method of claim 6, wherein, a pre-mixing step before the step 1, in which the C2-C12 halogenated alkane and aqueous alkali solution are input into a pre-mixer for pre-mixing to form a feedstock mixture; the pre-mixer is selected from the following: an eductor, an impingement mixer, a static mixer, or a combination thereof; the eductor is a jet pump, a Venturi tube, or a combination thereof; the impingement mixer is a multi-nozzle impingement mixer, preferably a double-nozzle opposed impingement mixer; The static mixer is selected from the group consisting of an SV type static mixer, an SK type static mixer, an SX type static mixer, an SL type static mixer, an SH type static mixer, or a combination thereof.

8. The method of claim 6, wherein, The C2-C12 haloalkane is 1,1,2-trichloroethane, and the C2-C12 haloalkene is 1,1-dichloroethene.

9. The method of claim 6, wherein, The ratio of the molar amount of the C2-C12 haloalkane to the molar amount of the base in the aqueous alkaline solution is 0.3:1 to 3:1; The mass percentage of the base in the aqueous alkaline solution is 5-25 mass% based on the mass of the aqueous alkaline solution.

10. The method of claim 6, wherein, The temperature in the reaction section of the reactor is 65-95°C, the reaction pressure is 1-5 atm, and the residence time of the reaction raw material in the reactor is 1 second to 60 minutes.

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