A production method and production device for epichlorohydrin

Abstract

The present invention provides a production method and a production device for epichlorohydrin. The production method includes the following steps: flowing a liquid-phase material through a catalyst bed to carry out an epoxidation reaction to obtain a reaction system; wherein the liquid-phase material includes at least allyl chloride, hydrogen peroxide, and a solvent; making the reaction system contact reversely with nitrogen gas at a temperature of 1 to 10 °C to obtain a first liquid phase and a first gas phase; separating the first liquid phase to obtain the epichlorohydrin. This method can significantly improve the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, and improve the stability and safety of production.

Description

Technical Field

[0001] The invention belongs to the field of preparation of organic chemical intermediates, and specifically relates to a production method and a production device of epichlorohydrin. Background Art

[0002] Epichlorohydrin is an important organic chemical intermediate, widely used in the fields of medicine, fine chemicals, petrochemicals, etc. At present, the main production methods of epichlorohydrin are the chlorohydrin method, the glycerol method and the hydrogen peroxide method. Among them, the hydrogen peroxide method has the advantages of short process flow, less waste residue and wastewater, low energy consumption and environmental protection, and has become the research focus of technicians in this field.

[0003] The hydrogen peroxide method is to use hydrogen peroxide as an oxidant, and in the presence of a catalyst (such as titanium silicon molecular sieve, heteropoly acid salt compound, etc.), directly epoxidize allyl chloride to prepare epichlorohydrin. At present, the reaction raw materials and catalyst are mixed to react, such as patent documents CN105712955A, CN101486690A, CN102746257A, CN101481364A, etc. The hydrogen peroxide method is essentially a liquid-solid phase catalytic reaction, and the reaction exotherm is large. If the reaction heat cannot be removed in time and the heat transfer effect is poor, the conversion rate of hydrogen peroxide and the yield of epichlorohydrin will be directly affected. The heat transfer capacity of the above-mentioned mixed reaction process is poor, and after the reaction is completed, the solid phase catalyst needs to be separated from the reaction system and recycled, which is difficult to achieve continuous production, thereby affecting the conversion rate of hydrogen peroxide and the yield of epichlorohydrin.

[0004] At present, fixed bed reactors are often used to react hydrogen peroxide and chloropropylene to produce epichlorohydrin, without the need to separate the catalyst, and continuous production can be achieved, thereby improving the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, such as patent documents CN111574481A, CN110698435A, and CN108395418A; fixed bed reactors are also used to make hydrogen peroxide and chloropropylene contact in reverse, and the evaporation and condensation of the solvent are used to remove the reaction heat, improve the heat transfer capacity, and improve the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, such as patent document CN111606871B. However, the above method is far from meeting the demand for the improvement of the conversion rate of hydrogen peroxide and the yield of epichlorohydrin. Therefore, how to provide a method for producing epichlorohydrin with high conversion rate of hydrogen peroxide and high yield of epichlorohydrin, large production capacity, and high safety is a technical problem to be solved in this field. Summary of the invention

[0005] The present invention provides a production method of epichlorohydrin, which avoids the complex separation process of the catalyst; uses nitrogen to remove the reaction heat, can maximize the heat transfer effect and timely remove the oxygen generated by the decomposition of hydrogen peroxide, reduces side reactions, improves the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, and improves the reaction safety.

[0006] The present invention also provides a production device of epichlorohydrin, which has excellent heat transfer capacity and safety, and has advantages such as high conversion rate and high product yield when used to implement the above production method of epichlorohydrin.

[0007] In one aspect of the present invention, a production method of epichlorohydrin is provided, including the following steps:

[0008] Let the liquid-phase material flow through the catalyst bed to carry out an epoxidation reaction to obtain a reaction system; wherein, the liquid-phase material at least includes allyl chloride, hydrogen peroxide, and a solvent;

[0009] Let the reaction system be in reverse contact with nitrogen at a temperature of 1 to 10 °C to obtain a first liquid phase and a first gas phase;

[0010] Separate the first liquid phase to obtain the epichlorohydrin.

[0011] In the production method as described above, the catalyst bed includes 1 to 20 sub-catalyst beds arranged at intervals, and the height of each sub-catalyst bed is independently 0.1 m to 5 m;

[0012] Let the liquid-phase material flow through each sub-catalyst bed in sequence to carry out an epoxidation reaction.

[0013] In the production method as described above, the conditions of the epoxidation reaction are: temperature 30 to 70 °C, pressure 0.001 to 0.6 MPaG, and time 0.5 to 6 h.

[0014] In the production method as described above, in the liquid-phase material, the molar ratio of allyl chloride, hydrogen peroxide, and the solvent is (2 to 8):1:(4 to 60);

[0015] The solvent is selected from at least one of methanol and ethanol.

[0016] In the production method as described above, the flow rate of the liquid-phase material in the catalyst bed is 0.0005 to 0.005 m / s; and / or,

[0017] When the reaction system is in reverse contact with nitrogen, the flow rate of nitrogen is 0.5 to 5 m / s.

[0018] In the production method as described above, it further includes: cooling the first gas phase to obtain a second gas phase and a second liquid phase;

[0019] Separate the second liquid phase from the first liquid phase to obtain the epichlorohydrin;

[0020] After subjecting the second gas phase to deoxidation treatment, it is returned to contact the reaction system in a countercurrent manner.

[0021] On the other hand, the present invention provides a production device for epichlorohydrin for implementing the above production method, and the production device at least includes a tower reactor;

[0022] The liquid phase inlet of the tower reactor is used to input liquid phase materials into the tower body, and the gas phase inlet of the tower reactor is used to input nitrogen into the tower body; the liquid phase inlet of the tower reactor is located at the top of the tower, and the gas phase inlet of the tower reactor is located at the bottom of the tower;

[0023] Along the direction from the liquid phase inlet to the gas phase inlet of the tower reactor, a catalyst bed layer is provided in the tower reactor;

[0024] The liquid phase inlet of the catalyst bed layer is communicated with the liquid phase inlet of the tower reactor, the liquid phase outlet of the catalyst bed layer is communicated with the liquid phase outlet of the tower reactor, and the gas phase inlet of the catalyst bed layer is communicated with the gas phase inlet of the tower reactor.

[0025] In the production device as described above, wherein the catalyst bed layer includes 1 to 20 sub-catalyst bed layers arranged at intervals, and the height of each sub-catalyst bed layer is independently 0.1 m to 5 m;

[0026] The gas phase inlets of each sub-catalyst bed layer are respectively communicated with the gas phase inlet of the tower reactor.

[0027] In the production device as described above, wherein it further includes a cooling unit and a driving unit, the gas phase outlets of each sub-catalyst bed layer are respectively communicated with the gas phase inlet of the cooling unit, and the gas phase outlet of the cooling unit is communicated with the gas phase inlet of the driving unit.

[0028] In the production device as described above, wherein it further includes a separation unit, the outlet of the cooling unit is communicated with the inlet of the separation unit, the gas phase outlet of the separation unit is communicated with the gas phase inlet of the driving unit, and the liquid phase outlet of the separation unit is communicated with the liquid phase outlet of the tower reactor; and / or,

[0029] It further includes a nitrogen source for providing nitrogen, and the nitrogen source is communicated with the gas phase inlet of the cooling unit; and / or,

[0030] The tower reactor further includes at least one liquid distribution unit;

[0031] On one side of each sub-catalyst bed close to the liquid phase inlet of the tower reactor, a liquid distribution unit is respectively provided; the liquid phase inlet of the tower reactor is communicated with the liquid phase inlet of the liquid distribution unit, and the liquid phase outlet of the liquid distribution unit is communicated with the liquid phase inlet of each sub-catalyst bed; and / or,

[0032] The tower reactor further includes at least one gas distribution unit;

[0033] On one side of each sub-catalyst bed close to the gas phase inlet of the tower reactor, a gas distribution unit is respectively provided; the gas phase inlet of the tower reactor is communicated with the gas phase inlet of the gas distribution unit, and the gas phase outlet of the gas distribution unit is communicated with the gas phase inlet of the sub-catalyst bed.

[0034] The implementation of the present invention has at least the following beneficial effects:

[0035] In the production method of epichlorohydrin provided by the present invention, the catalyst in the catalyst bed is basically not lost, and there is no need to separate the catalyst; secondly, the tower reactor has a large production capacity, which is conducive to industrial scale-up; thirdly, nitrogen can be used to effectively remove the reaction heat in a timely manner. At the same time, nitrogen has the function of stripping and purging, and can effectively remove the oxygen generated by the decomposition of a small amount of hydrogen peroxide in a timely manner. While improving the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, it can also effectively improve the production safety.

[0036] The production device of epichlorohydrin provided by the present invention is used to implement the above production method of epichlorohydrin, can remove the reaction heat to the greatest extent, has excellent heat transfer capacity and safety, and has advantages such as high conversion rate and high product yield when producing epichlorohydrin. Description of the Drawings

[0037] Figure 1 It is a schematic diagram of the production device of epichlorohydrin in an embodiment of the present invention.

[0038] Description of the Reference Numerals:

[0039] MX - mixer; RE - tower reactor; HE - cooling unit; V - separation unit; BL - blower; 1 - first sub-catalyst bed; 2 - second sub-catalyst bed; 3 - third sub-catalyst bed; 4 - feed distribution pipe; 5 - first liquid distribution unit; 6 - second liquid distribution unit; 7 - third liquid distribution unit; 8 - first riser pipe; 9 - second riser pipe; 10 - third riser pipe; 11 - first gas distribution unit; 12 - second gas distribution unit; 13 - third gas distribution unit. Detailed Embodiments

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0041] In the first aspect of the present invention, a production method of epichlorohydrin is provided, including the following steps: allowing a liquid-phase material to flow through a catalyst bed layer to undergo an epoxidation reaction to obtain a reaction system; wherein the liquid-phase material at least includes allyl chloride, hydrogen peroxide, and a solvent; allowing the reaction system to be in reverse contact with nitrogen gas at a temperature of 1 to 10 °C to obtain a first liquid phase and a first gas phase; separating the first liquid phase to obtain epichlorohydrin.

[0042] In the present invention, the catalyst bed layer refers to a solid particle bed layer formed by piling up catalyst particles with a certain size. When the liquid-phase material flows through the catalyst bed layer, the liquid-phase material can flow through the gaps between the catalyst particles and react on the surface of the catalyst. The catalyst particles include but are not limited to titanium silicalite molecular sieves.

[0043] In the liquid-phase material, the presence of the solvent can promote the contact between hydrogen peroxide and allyl chloride and perform an epoxidation reaction on the catalyst. The reaction between allyl chloride and hydrogen peroxide under the action of the catalyst can generate epichlorohydrin and water. Therefore, the reaction system at least contains epichlorohydrin, water, a solvent, and unreacted allyl chloride.

[0044] Since the epoxidation reaction is an exothermic reaction, it is necessary to remove the reaction heat in time to reduce the occurrence of side reactions. When the reaction system is in reverse contact with nitrogen gas at a temperature of 1 to 10 °C, the reaction system is in full contact with the low-temperature nitrogen gas and the reaction heat is removed. At the same time, a small amount of unreacted hydrogen peroxide in the reaction system is prone to decomposition to generate oxygen. When the reaction system is in reverse contact with the low-temperature nitrogen gas, a small amount of oxygen in the reaction system can also be stripped out to improve the production safety.

[0045] In addition, by controlling the nitrogen gas temperature to be 1 to 10 °C, in addition to being beneficial to removing the reaction heat, it can also effectively liquefy epichlorohydrin, water, the solvent, unreacted allyl chloride, impurities, etc. in the reaction system to achieve gas-liquid separation. If the nitrogen gas temperature is too high, it is difficult to remove the reaction heat and effectively liquefy the reaction system; if the nitrogen gas temperature is too low, the entrained moisture is prone to solidification, affecting the production process.

[0046] In the present invention, the first liquid phase at least contains epichlorohydrin, water, and a solvent. By performing refined separation on the first liquid phase, the product epichlorohydrin is obtained. The first gas phase at least contains nitrogen gas and a small amount of oxygen.

[0047] According to the technical solution provided by the present invention, when epichlorohydrin is produced by the above method, the catalyst in the catalyst bed layer hardly leaks, and there is no need to separate the catalyst. In addition to enabling continuous production and significantly improving the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, it is also beneficial to the stability and safety of production. Based on this phenomenon, the inventor analyzed and believed that on the one hand, compared with the mixed reaction system, the liquid-phase material flows through the catalyst bed layer to complete the epoxidation reaction, and there is no need to separate the catalyst after the reaction, avoiding the loss of the catalyst during the separation process; on the other hand, the reaction system is in reverse contact with nitrogen at a temperature of 1-10°C, which can effectively remove the reaction heat in a timely manner. At the same time, nitrogen has the functions of stripping and purging, and can effectively remove the oxygen generated by the decomposition of a small amount of hydrogen peroxide in a timely manner. Therefore, while increasing the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, it can also effectively improve the safety and stability of production; as the liquid-phase material continuously flows through the catalyst bed layer to carry out the epoxidation reaction, and then the reaction system is in reverse contact with nitrogen, continuous production can be achieved.

[0048] The present invention does not limit the device for implementing the above production method, as long as it can be filled with a catalyst bed layer. For example, it can be a tower reactor. During specific operation, catalyst particles can be stacked in the tower reactor to form a catalyst bed layer with a certain height. At this time, the diameter of the catalyst bed layer is the same as the inner diameter of the tower reactor. Further, the diameter of the catalyst bed layer can be effectively increased by increasing the inner diameter of the tower reactor, thereby improving the production capacity. Compared with the method of connecting multiple reactors in series or parallel, it is more conducive to realizing industrial scale-up production.

[0049] The present invention does not limit the specific setting method of the catalyst bed layer. For example, the catalyst bed layer includes 1-20 sub-catalyst bed layers arranged at intervals. At this time, the number of sub-catalyst bed layers and the height of a single-layer sub-catalyst bed layer together determine the total height of the catalyst bed layer. When the catalyst bed layer includes multiple sub-catalyst bed layers arranged at intervals, the present invention does not limit the interval distance between adjacent sub-catalyst bed layers, as long as it is ensured that nitrogen can fully contact the reaction system in the interval area.

[0050] Taking the catalyst bed layer with 3 sub-catalyst bed layers arranged at intervals as an example, the catalyst bed layer includes a first sub-catalyst bed layer, a second sub-catalyst bed layer, and a third sub-catalyst bed layer arranged at intervals. The liquid-phase material flows through the first sub-catalyst bed layer, the second sub-catalyst bed layer, and the third sub-catalyst bed layer in sequence to carry out the epoxidation reaction, obtaining a first liquid phase and a first gas phase.

[0051] In the above-described embodiment, the liquid-phase material flows through the first sub-catalyst bed to undergo the first epoxidation reaction, obtaining a first reaction system. The first reaction system is in reverse contact with the first nitrogen gas at a temperature of 1 to 10 °C, obtaining a first sub-liquid phase and a first sub-gas phase. The first sub-liquid phase flows through the second sub-catalyst bed to undergo the second epoxidation reaction, obtaining a second reaction system. The second reaction system is in reverse contact with the second nitrogen gas at a temperature of 1 to 10 °C, obtaining a second sub-liquid phase and a second sub-gas phase. The second sub-liquid phase flows through the third sub-catalyst bed to undergo the third epoxidation reaction, obtaining a third reaction system. The third reaction system is in reverse contact with the third nitrogen gas at a temperature of 1 to 10 °C, obtaining a first liquid phase and a third sub-gas phase, where the first sub-gas phase, the second sub-gas phase, and the third sub-gas phase are collectively referred to as the first gas phase. In the above production method, by making the reaction system of each catalyst bed in reverse contact with low-temperature nitrogen gas, the reaction heat and a small amount of oxygen can be removed in a timely and effective manner.

[0052] The present invention does not limit the height of each sub-catalyst bed and can be adjusted according to actual production needs. In one embodiment, the height of each sub-catalyst bed is independently 0.1 m to 5 m, preferably 0.5 to 3 m. If the height of the sub-catalyst bed is lower than 0.1 m, in order to ensure the reaction residence time, more sub-catalyst beds, pipelines, etc. are required, increasing the cost; if the height of the sub-catalyst bed is higher than 5 m, the reaction heat accumulated in the sub-catalyst bed and the oxygen generated by the decomposition of a small amount of hydrogen peroxide are difficult to remove in a timely and effective manner, which not only affects the production safety but also causes a large amount of hydrogen peroxide decomposition, affecting the product yield.

[0053] The present invention does not limit the temperature and pressure of the epoxidation reaction, as long as the reaction between allyl chloride and hydrogen peroxide in the liquid-phase material can be achieved. In one embodiment, the conditions of the epoxidation reaction are: the temperature is 30 to 70 °C. If the reaction temperature is lower than 30 °C, the reaction rate is slower, reducing the production efficiency and generating more by-products as the reaction time extends; if the reaction temperature is higher than the boiling point of allyl chloride and the solvent under the reaction pressure, it cannot ensure that the reaction proceeds in the liquid phase. In one embodiment, the conditions of the epoxidation reaction are: the pressure is 0.001 to 0.6 MPaG. If the reaction pressure is lower than 0.001 MPaG, oxygen in the air may enter the semi-closed space in the reactor during the production process, resulting in danger; if the reaction pressure is higher than 0.6 MPaG, not only does the energy consumption for transporting the liquid-phase material increase, but the transportation pressure of nitrogen gas also needs to be increased accordingly, increasing the operating cost.

[0054] The present invention does not limit the reaction residence time, which can be specifically adjusted according to actual production needs. Specifically, the reaction residence time is related to the total height of the catalyst bed. The total height of the catalyst bed divided by the flow rate of the liquid-phase material is the reaction residence time. By adjusting the total height of the catalyst bed and the flow rate of the liquid-phase material, the reaction residence time can be adjusted. In one embodiment, the reaction time (reaction residence time) is 0.5 - 6 h. If the reaction time is less than 0.5 h, the epoxidation reaction is incomplete, and the unreacted hydrogen peroxide is likely to decompose to generate oxygen during subsequent separation processes, thereby reducing the production safety. If the reaction time is more than 6 h, epichlorohydrin is prone to side reactions with water and solvents in the reaction system to generate by-products such as monochloropropanediol, reducing the product yield.

[0055] The present invention does not limit the specific selection of each raw material in the liquid-phase material. For example, hydrogen peroxide can be pre-prepared hydrogen peroxide solution. Among them, the hydrogen peroxide solution can be an aqueous solution with a concentration of 10% - 80%, preferably an aqueous solution with a concentration of 25% - 55%. If the concentration of hydrogen peroxide solution is less than 10%, the amount of wastewater generated by the reaction is too large, and the wastewater treatment cost is relatively high. If the concentration of hydrogen peroxide solution is more than 80%, the amount of oxygen generated by the decomposition of hydrogen peroxide is relatively large, and the tail gas generated by the reaction needs to be discharged frequently. The solvent is selected from at least one of methanol and ethanol.

[0056] The present invention does not limit the molar ratio of each raw material in the liquid-phase material as long as epichlorohydrin can be produced. To avoid or reduce the decomposition of hydrogen peroxide to generate oxygen, allyl chloride can be in excess to ensure that hydrogen peroxide reacts as completely as possible. In one embodiment, the molar ratio of allyl chloride to hydrogen peroxide is (2 - 8):1. The inventors believe through research that if the ratio of allyl chloride to hydrogen peroxide is less than 2:1, the reaction time is relatively long, more than 6 h, and the residence time of the product epichlorohydrin is relatively long, which is prone to side reactions such as hydrolysis and alcoholysis with water and alcohol in the reaction system to generate by-products such as monochloropropanediol, and the total reaction yield is reduced to less than 90%. If the ratio of allyl chloride to hydrogen peroxide is more than 8:1, for the same catalyst usage amount, it is equivalent to reducing the concentration of the raw material hydrogen peroxide, which also leads to a relatively long reaction time, an increase in reaction by-products, and in addition, the single-pass conversion rate of allyl chloride is low, increasing the separation energy consumption of the product.

[0057] In the present invention, the presence of the solvent mainly serves two purposes. Firstly, hydrogen peroxide and allyl chloride are immiscible with each other, and the presence of the solvent enables these two reaction raw materials to come into contact and react on the catalyst bed. Secondly, the solvent can act as a heat transfer medium to convert part of the reaction heat into an increase in its own temperature, and the reaction heat can be carried away as the solvent leaves. In one embodiment, the molar ratio of hydrogen peroxide to the solvent is 1:(4 - 60). Through research, the inventor believes that when the ratio of the solvent to hydrogen peroxide is lower than 4:1, the function of the solvent as a reaction heat carrier is greatly weakened, the reaction temperature is difficult to control, and it will further exacerbate the decomposition of hydrogen peroxide to generate more oxygen, resulting in the product yield being reduced to less than 80%, and the reaction safety significantly decreases. When the ratio of the solvent to hydrogen peroxide is higher than 60:1, the concentration of the reaction raw materials decreases, the reaction time is prolonged, resulting in an increase in by-products generated during the reaction, the product yield is reduced to less than 80%, and in addition, the separation energy consumption of the product increases.

[0058] The present invention does not limit the flow rates of the liquid-phase material and nitrogen, as long as the liquid-phase material can flow through the catalyst bed and the reaction system can be in reverse contact with nitrogen. In one embodiment, the flow rate of the liquid-phase material in the catalyst bed is 0.0005 - 0.005 m / s. The flow rate of the liquid-phase material refers to the flow rate of the liquid-phase material flowing through the catalyst bed. If the flow rate of the liquid-phase material in the catalyst bed is lower than 0.0005 m / s, the reaction time is longer and more by-products are likely to be generated. If the flow rate of the liquid-phase material is higher than 0.005 m / s, in order to ensure the same residence time, the total height of the catalyst bed needs to be increased, thus significantly increasing the cost. In one embodiment, the flow rate of nitrogen when the reaction system is in reverse contact with nitrogen is 0.5 - 5 m / s. The flow rate of nitrogen refers to the flow rate when nitrogen is in reverse contact with the reaction system. When the catalyst bed has multiple sub-catalyst beds arranged at intervals, the flow rate of nitrogen refers to the flow rate of nitrogen in the gas phase space between the sub-catalyst beds. If the flow rate of nitrogen is lower than 0.5 m / s, both the reaction heat and the oxygen generated by the decomposition of hydrogen peroxide are difficult to remove in a timely and effective manner. If the flow rate of nitrogen is higher than 5 m / s, since the temperature of nitrogen is relatively low, it will directly affect the temperature of the epoxidation reaction, resulting in a slower reaction rate, and even causing hydrogen peroxide to not react completely, affecting the conversion rate of hydrogen peroxide and the product yield.

[0059] In the present invention, allyl chloride, hydrogen peroxide, and the solvent can be first mixed in a pipeline mixer to obtain a liquid-phase material, and this liquid-phase material is made to flow through the catalyst bed to undergo an epoxidation reaction.

[0060] In the production method of the present invention, it also includes cooling the first gas phase to obtain a second gas phase and a second liquid phase; separating the second liquid phase and the first liquid phase to obtain epichlorohydrin; and after deoxygenating the second gas phase, returning it to be in reverse contact with the reaction system.

[0061] Among them, by cooling the first gas phase, the easily liquefied materials such as allyl chloride, solvent, epichlorohydrin, and water entrained by nitrogen can be separated from gases such as nitrogen and oxygen to obtain a second gas phase and a second liquid phase. The second gas phase contains at least nitrogen and oxygen, and the second liquid phase includes at least the entrained epichlorohydrin, water, and solvent, etc. By refining and separating the first liquid phase and the second liquid phase, the product epichlorohydrin is obtained. After deoxygenating the second gas phase, it is returned to contact the reaction system reversely, which is beneficial to the recycling of nitrogen. Among them, the temperature of the cooling treatment is 1-10°C.

[0062] In the above embodiment, a blower can be used to pressurize the second gas phase and recycle it. The process of returning the second gas phase to contact the reaction system reversely after deoxygenating can be achieved through the following process: using a blower to discharge part of the second gas phase to the tail gas treatment system, and then supplementing the same volume of fresh nitrogen to return to contact the reaction system reversely together with the remaining second gas phase. In the above process, it can not only prevent the oxygen in the second gas phase from accumulating in the reaction system and causing danger, but also realize the recycling of nitrogen.

[0063] In the second aspect of the present invention, a production device for epichlorohydrin is provided for implementing the production method of the first aspect. The production device at least includes a tower reactor; the liquid phase inlet of the tower reactor is used to input liquid phase materials into the tower body, and the gas phase inlet of the tower reactor is used to input nitrogen into the tower body; along the direction from the liquid phase inlet to the gas phase inlet of the tower reactor, a catalyst bed layer is provided in the tower reactor; the liquid phase inlet of the catalyst bed layer is communicated with the liquid phase inlet of the tower reactor, the liquid phase outlet of the catalyst bed layer is communicated with the liquid phase outlet of the tower reactor, and the gas phase inlet of the catalyst bed layer is communicated with the gas phase inlet of the tower reactor.

[0064] The liquid phase inlet of the tower reactor is located on the top side of the tower, the gas phase inlet of the tower reactor is located on the bottom side of the tower, the liquid phase outlet of the tower reactor is located at the bottom of the tower, and the gas phase outlet of the tower reactor is located at the top of the tower. Among them, the catalyst bed layer includes 1-20 sub-catalyst bed layers arranged at intervals, and the height of each sub-catalyst bed layer is independently 0.1 m-5 m; the gas phase inlets of each sub-catalyst bed layer are respectively communicated with the gas phase inlet of the tower reactor. Further, there are gas phase spaces on both sides of each sub-catalyst bed layer, and the gas phase inlet of each sub-catalyst bed layer can be located at the lower part of the gas phase space on one side of each sub-catalyst bed layer close to the gas phase inlet of the tower reactor.

[0065] Taking the catalyst bed layer including three spaced sub-catalyst bed layers as an example, along the direction from the liquid phase inlet to the gas phase inlet of the tower reactor, the catalyst bed layer includes a first sub-catalyst bed layer, a second sub-catalyst bed layer, and a third sub-catalyst bed layer that are spaced apart. The first sub-catalyst bed layer is closer to the liquid phase inlet of the tower reactor. The third sub-catalyst bed layer is closer to the gas phase inlet of the tower reactor. When the liquid phase material enters through the liquid phase inlet of the tower reactor, the liquid phase material can flow through the gaps between the catalyst particles in the catalyst bed layer. Under the action of gravity, it flows through the first sub-catalyst bed layer, the second sub-catalyst bed layer, and the third sub-catalyst bed layer in sequence.

[0066] In the above production device, at least one liquid distribution unit is further included in the tower reactor. The liquid distribution unit is used to disperse the liquid phase material to ensure uniform distribution of the liquid phase in the catalyst bed layer. Further, a liquid distribution unit is respectively provided on the side of each sub-catalyst bed layer close to the liquid phase inlet of the tower reactor. Taking the catalyst bed layer including three spaced sub-catalyst bed layers as an example, a first liquid distribution unit, a second liquid distribution unit, and a third liquid distribution unit are respectively provided on the sides of the first sub-catalyst bed layer, the second sub-catalyst bed layer, and the third sub-catalyst bed layer close to the liquid phase inlet of the tower reactor. When the liquid phase material enters through the liquid phase inlet of the tower reactor, the liquid phase material can flow through the gaps of the liquid distribution unit and the gaps between the catalyst particles in the catalyst bed layer. Under the action of gravity, it flows through the first liquid distribution unit, the first sub-catalyst bed layer, the second liquid distribution unit, the second sub-catalyst bed layer, the third liquid distribution unit, and the third sub-catalyst bed layer in sequence. As the reaction proceeds, the first liquid phase converges to the bottom of the tower reactor, is discharged from the liquid phase outlet of the tower reactor, and flows into the separation and purification unit for purification and separation to obtain the product epichlorohydrin.

[0067] In the above production device, a feed distribution pipe is further included. The liquid phase inlet of the feed distribution pipe is communicated with the liquid phase inlet of the tower distributor, and the feed distribution pipe is located above the first liquid distribution unit. When the liquid phase material enters the tower reactor, after being dispersed by the feed distribution pipe, it then flows through the first liquid distribution unit and the first sub-catalyst bed layer in sequence.

[0068] In the above production device, the tower reactor further includes at least one gas distribution unit. The gas distribution unit is used to disperse nitrogen to ensure uniform distribution of nitrogen. Further, a gas distribution unit is respectively provided on one side of each sub-catalyst bed close to the gas inlet of the tower reactor; the gas inlet of the tower reactor is communicated with the gas inlet of the gas distribution unit, and the gas inlet of each sub-catalyst bed is respectively communicated with the gas outlet of the corresponding gas distribution unit. Still taking the catalyst bed including 3 spaced sub-catalyst beds as an example, a first gas distribution unit, a second gas distribution unit, and a third gas distribution unit are respectively provided on one side of the first sub-catalyst bed, the second sub-catalyst bed, and the third sub-catalyst bed close to the gas inlet of the tower reactor. The gas inlet of the tower reactor is respectively communicated with the gas inlets of the first gas distribution unit, the second gas distribution unit, and the third gas distribution unit, and the gas outlets of the first gas distribution unit, the second gas distribution unit, and the third gas distribution unit are communicated with the gas inlets of each sub-catalyst bed. At this time, when nitrogen enters through the gas inlet of the tower reactor, nitrogen can flow through the gaps of the gas distribution unit and the gaps between the catalyst particles in the catalyst bed. The first nitrogen gas flows through the first gas distribution unit, the first sub-catalyst bed and is in reverse contact with the first reaction system, the second nitrogen gas flows through the second gas distribution unit, the second sub-catalyst bed in sequence and is in reverse contact with the second reaction system, and the third nitrogen gas flows through the third gas distribution unit, the third sub-catalyst bed in sequence and is in reverse contact with the third reaction system. As the reaction proceeds, the first sub-gas phase, the second sub-gas phase, and the third sub-gas phase (collectively referred to as the first gas phase) generated are collected and discharged from the gas outlet of the tower reactor.

[0069] In the above implementation, the opening direction of the gas distribution unit is downward to prevent liquid from blocking the distribution pipe of the gas distribution unit.

[0070] In the above production device, a cooling unit and a driving unit are further included. The cooling unit is used to cool the first gas phase, and the driving unit is used to extract the first gas phase from the tower reactor. The gas outlets of each sub-catalyst bed are respectively communicated with the gas inlets of the cooling unit, and the gas outlet of the cooling unit is communicated with the gas inlet of the driving unit. At this time, under the action of the driving unit, the first gas phase is discharged from the gas outlet of the tower reactor and flows into the cooling unit for cooling treatment.

[0071] Further, except for the sub-catalyst bed closest to the gas phase outlet of the tower reactor among each sub-catalyst bed, on the side of each sub-catalyst bed close to the gas phase outlet of the tower reactor, there is a gas phase space, and the gas phase outlet of each sub-catalyst bed is located at this gas phase space. Among them, the gas phase outlet of the sub-catalyst bed closest to the gas phase outlet of the tower reactor can be first connected to the gas phase outlet of the tower reactor, the gas phase outlet of the tower reactor is connected to the gas phase inlet of the cooling unit, and the gas phase outlets of other sub-catalyst beds are respectively communicated with the gas phase inlet of the cooling unit.

[0072] The present invention does not limit the types of the cooling unit and the driving unit. For example, the cooling unit can be a cooler, and the driving unit can be a blower.

[0073] The present invention does not limit the above connection method. For example, it can be connected by a pipeline. Specifically, the gas phase outlet of each sub-catalyst bed is communicated with the gas phase inlet of the cooling unit through a riser pipe. That is to say, a riser pipe is respectively provided on the side of each sub-catalyst bed close to the gas phase outlet of the tower reactor, and the gas phase is led out through the riser pipe. The gas phase inlet of the tower reactor is communicated with the gas phase inlet of the gas distribution unit corresponding to each sub-catalyst bed through a nitrogen inlet pipe. Among them, the number and diameter of the riser pipes ensure that nitrogen can leave the tower reactor in time. For example, the total cross-sectional area of the riser pipes of a section of sub-catalyst bed is 1.05 to 1.2 times the total cross-sectional area of the nitrogen inlet pipe corresponding to this section of sub-catalyst bed.

[0074] Taking the catalyst bed including 3 sections of spaced sub-catalyst beds as an example, a first riser pipe, a second riser pipe, and a third riser pipe are respectively provided on the side of the first sub-catalyst bed, the second sub-catalyst bed, and the third sub-catalyst bed close to the gas phase outlet of the tower reactor; the gas in the first riser pipe can be directly led out from the gas phase outlet at the top of the tower reactor, and converges with the gas led out from the second riser pipe and the third riser pipe to form a first gas phase, and then the first gas phase enters the cooling unit for cooling treatment.

[0075] In the above production device, a separation unit is further included. The separation unit is used to separate the second gas phase and the second liquid phase generated after the cooling treatment of the first gas phase. The outlet of the cooling unit is communicated with the inlet of the separation unit, the gas phase outlet of the separation unit is communicated with the gas phase inlet of the driving unit, and the liquid phase outlet of the separation unit is communicated with the liquid phase outlet of the tower reactor. As the reaction proceeds, the first gas phase after cooling treatment flows into the separation unit, forming a second gas phase and a second liquid phase. The second gas phase flows into the driving unit, and after deoxidation treatment, it returns to the tower reactor for recycling; the second liquid phase flows through the liquid phase outlet of the separation unit to the liquid phase outlet of the tower reactor, converges with the first liquid phase, and jointly flows into the separation and purification unit for purification separation to obtain the product epichlorohydrin.

[0076] The present invention does not limit the type of the separation unit. For example, the separation unit can be a gas-liquid separation tank.

[0077] In the above production device, a nitrogen source for providing nitrogen is further included. The nitrogen source is used to convey nitrogen into the tower distributor. The nitrogen source is communicated with the gas-phase inlet of the cooling unit. The temperature of the nitrogen can be controlled at 1-10 °C through the cooling unit. If the temperature of the nitrogen entering the tower reactor is higher than 10 °C, after the nitrogen contacts the reaction system reversely, impurities such as allyl chloride, hydrogen peroxide, solvent, epichlorohydrin, and water entrained by the nitrogen are difficult to be effectively liquefied and separated from the nitrogen in the cooling unit. Even if gas-liquid separation can be achieved, the product epichlorohydrin will have a relatively high partial pressure in the nitrogen and will be lost when the tail gas is discharged from the gas-phase outlet of the fan. More seriously, it may condense into a liquid at the gas-phase inlet of the fan, causing cavitation of the fan and affecting the operation of the fan. If the temperature of the nitrogen is lower than 1 °C, the entrained moisture is likely to solidify and block the pipeline, affecting the operation of the production device.

[0078] In the present invention, a part of the second gas phase can be discharged from the tail gas outlet of the fan and sent to the tail gas treatment system, and fresh nitrogen with an equal volume is supplemented by the nitrogen source communicated with the cooling unit, so as to complete the deoxygenation treatment of the second gas phase to obtain a third gas phase. A part of the third gas phase is discharged from the gas-phase outlet of the fan, and the remaining third gas phase can be returned to the tower reactor for recycling, and it can also avoid the accumulation of oxygen in the reaction system and cause danger, improving the safety of production.

[0079] In the present invention, a mixer is further included. The mixer is used to mix allyl chloride, hydrogen peroxide, and solvent evenly to form a liquid-phase material. The liquid-phase outlet of the mixer is communicated with the liquid-phase inlet of the tower reactor.

[0080] In the present invention, an oxygen on-line analyzer can also be arranged at the bottom of the tower, the top of the tower or between any two sections of the sub-catalyst beds of the tower reactor to monitor the oxygen concentration in the tower reactor in real time, and when the oxygen concentration exceeds the standard, part of the gas is discharged from the fan outlet to reduce the oxygen concentration in the tower reactor to ensure the safe and stable operation of the reaction. For example, when the oxygen concentration in the tower reactor ≥ 0.8%, part of the second gas phase is discharged from the tail gas outlet of the fan until the oxygen concentration is reduced to below 0.5%.

[0081] The present invention will be further described below through specific examples and comparative examples. Unless otherwise specified, the reagents, materials, and instruments used below are all conventional reagents, conventional materials, and conventional instruments, which can be obtained commercially, and the reagents and materials involved can also be synthesized by conventional synthesis methods.

[0082] In the following examples, the production device for epichlorohydrin used is as Figure 1As shown, it includes a mixer MX, a tower reactor RE, a cooling unit HE, a separation unit V, a blower BL, a catalyst bed located in the tower reactor RE, and a nitrogen source;

[0083] The tower reactor RE includes a feed distribution pipe 4, a first liquid distribution unit 5, a second liquid distribution unit 6, a third liquid distribution unit 7, a first riser pipe 8, a second riser pipe 9, a third riser pipe 10, a first gas distribution unit 11, a second gas distribution unit 12, and a third gas distribution unit 13;

[0084] The liquid phase inlet of the tower reactor RE is located on the top side of the tower, and the gas phase inlet of the tower reactor RE is located on the bottom side of the tower; the liquid phase outlet of the tower reactor RE is located at the bottom of the tower, and the gas phase outlet of the tower reactor RE is located at the top of the tower;

[0085] Along the direction from the liquid phase inlet to the gas phase inlet of the tower reactor RE, spaced first sub-catalyst beds 1, second sub-catalyst beds 2, and third sub-catalyst beds 3 are arranged in the tower reactor. Among them, the catalyst bed uses titanium silicalite molecular sieve;

[0086] On the side of the first sub-catalyst bed 1, second sub-catalyst bed 2, and third sub-catalyst bed 3 close to the liquid phase inlet of the tower reactor, a first liquid distribution unit 5, a second liquid distribution unit 6, and a third liquid distribution unit 7 are respectively provided; on the side of the first liquid distribution unit 5 close to the liquid phase inlet of the tower reactor RE, a feed distribution pipe 4 is provided; the first liquid distribution unit 5, the second liquid distribution unit 6, and the third liquid distribution unit 7 are respectively located above the first sub-catalyst bed 1, the second sub-catalyst bed 2, and the third sub-catalyst bed 3;

[0087] On the side of the first sub-catalyst bed 1, second sub-catalyst bed 2, and third sub-catalyst bed 3 close to the gas phase inlet of the tower reactor, a first gas distribution unit 11, a second gas distribution unit 12, and a third gas distribution unit 13 are respectively provided; the first gas distribution unit 11, the second gas distribution unit 12, and the third gas distribution unit 13 are respectively located below the first sub-catalyst bed 1, the second sub-catalyst bed 2, and the third sub-catalyst bed 3;

[0088] On the side of the first sub-catalyst bed 1, second sub-catalyst bed 2, and third sub-catalyst bed 3 close to the gas phase outlet of the tower reactor, a first riser pipe 8, a second riser pipe 9, and a third riser pipe 10 are respectively provided;

[0089] The liquid phase outlet of the mixer MX is connected to the liquid phase inlet of the tower reactor RE, and the liquid phase inlet of the tower reactor RE is connected to the feed distribution pipe 4; the gas phase inlet of the tower reactor RE is respectively connected to the gas phase inlets of the first gas distribution unit 11, the second gas distribution unit 12, and the third gas distribution unit 13; the liquid phase outlet of the tower reactor is connected to the separation and purification system;

[0090] The gas phase outlets of the first sub-catalyst bed 1, the second sub-catalyst bed 2, and the third sub-catalyst bed 3 are respectively connected to the gas phase inlet of the cooling unit HE through the first riser pipe 8, the second riser pipe 9, and the third riser pipe 10; the outlet of the nitrogen source is connected to the gas phase inlet of the cooling unit HE; the outlet of the cooling unit HE is connected to the inlet of the separation unit V, the gas phase outlet of the separation unit V is connected to the gas phase inlet of the blower BL, and the liquid phase outlet of the separation unit V is connected to the liquid phase outlet of the tower reactor; the gas phase outlet of the blower BL is connected to the gas phase inlet of the tower reactor RE, and the tail gas outlet of the blower is connected to the tail gas treatment system.

[0091] In the following examples, the calculation processes of the conversion rate of hydrogen peroxide a and the yield of epichlorohydrin b are as follows: The conversion rate w1 of hydrogen peroxide a = (m0 - m1) / m0, where m0 is the product of the mass of hydrogen peroxide a entering the tower reactor RE and its mass concentration x0, and m1 is the mass of hydrogen peroxide in the liquid phase reaction products (including the first liquid phase and the second liquid phase) in the tower reactor RE (i.e., the mass of unreacted hydrogen peroxide); the yield w2 of epichlorohydrin b = m2 / (m0×M b / M a ), where m0 is the product of the mass of hydrogen peroxide a entering the tower reactor RE and its concentration x0, m2 is the mass of epichlorohydrin in the liquid phase reaction products of the tower reactor RE, M a is the relative molecular mass of hydrogen peroxide, and M b is the relative molecular mass of epichlorohydrin.

[0092] Example 1

[0093] Mix allyl chloride, hydrogen peroxide, and methanol in mixer MX to obtain a liquid-phase material; among them, hydrogen peroxide is an aqueous solution with a mass concentration of 50%, and the molar ratio of allyl chloride: hydrogen peroxide: methanol is 3:1:6; let the liquid-phase material flow through the feed distribution pipe 4, the first liquid distribution unit 5, the first sub-catalyst bed 1, the second liquid distribution unit 6, the second sub-catalyst bed 2, the third liquid distribution unit 7, and the third sub-catalyst bed 3 in sequence to carry out an epoxidation reaction to obtain a reaction system; meanwhile, nitrogen at 5°C enters from the first gas distribution unit 11, the second gas distribution unit 12, and the third gas distribution unit 13, exchanges heat with the reaction system and strips out oxygen to obtain the first sub-gas phase, the second sub-gas phase, the third sub-gas phase, and the first liquid phase respectively; among them, the height of the first sub-catalyst bed 1 is 0.8 m, the height of the second sub-catalyst bed 2 is 1.4 m, and the height of the third sub-catalyst bed 3 is 2.2 m; the flow rate of nitrogen is 1.5 m / s. The flow rate of the liquid-phase material is 0.001 m / s; the conditions for the epoxidation reaction are: temperature 50°C, pressure 0.1 MPaG, and residence time 1.2 h;

[0094] The first sub-gas phase, the second sub-gas phase, and the third sub-gas phase leave the first sub-catalyst bed 1, the second sub-catalyst bed 2, and the third sub-catalyst bed 3 from the first riser pipe 8, the second riser pipe 9, and the third riser pipe 10 respectively; the first sub-gas phase in the first riser pipe 8 is led out from the gas-phase outlet at the top of the tower reactor RE and converges with the second sub-gas phase and the third sub-gas phase led out from the second riser pipe 9 and the third riser pipe 10 to form a first gas phase, and the first gas phase enters the cooling unit HE, is cooled to 5°C, and then enters the gas-liquid separation tank V for gas-liquid separation to obtain a second gas phase and a second liquid phase;

[0095] The second liquid phase is recycled to the liquid-phase outlet of the tower reactor RE, converges with the first liquid phase, and goes to the separation and refining system for refining treatment to obtain the product epichlorohydrin b;

[0096] The second gas phase is pressurized to 0.2 MPaG by the blower BL, and after overcoming the pressure drops of the first gas distribution unit 11, the second gas distribution unit 12, the third gas distribution unit 13, and the corresponding pipelines, it is recycled back into the tower reactor RE through the gas-phase inlet of the tower reactor;

[0097] When the oxygen concentration in the tower reactor RE is ≥0.8%, part of the second gas phase is discharged from the tail gas outlet of the blower BL until the oxygen concentration is reduced to less than 0.5%; when the pressure at the top of the tower reactor RE is lower than 0.08 MPaG, fresh nitrogen is supplemented from the nitrogen source to the cooling unit HE, and flows out of the gas phase of the cooling unit into the tower reactor until the pressure rises above 0.1 MPaG.

[0098] After testing, the conversion rate of hydrogen peroxide a in this example is 99.98%, and the yield of epichlorohydrin b is 98.9%.

[0099] Example 2

[0100] Allyl chloride, hydrogen peroxide, and methanol are mixed in mixer MX to obtain a liquid-phase material; among them, hydrogen peroxide is an aqueous solution with a mass concentration of 27.5%, and the molar ratio of allyl chloride: hydrogen peroxide: methanol is 5:1:20. The liquid-phase material flows through the feed distribution pipe 4, the first liquid distribution unit 5, the first sub-catalyst bed 1, the second liquid distribution unit 6, the second sub-catalyst bed 2, the third liquid distribution unit 7, and the third sub-catalyst bed 3 in sequence to carry out an epoxidation reaction to obtain a reaction system; meanwhile, nitrogen gas at 2°C enters from the first gas distribution unit 11, the second gas distribution unit 12, and the third gas distribution unit 13, exchanges heat with the reaction system and strips out oxygen to obtain the first sub-gas phase, the second sub-gas phase, the third sub-gas phase, and the first liquid phase respectively; among them, the height of the first sub-catalyst bed 1 is 2 m, the height of the second sub-catalyst bed 2 is 3 m, and the height of the third sub-catalyst bed 3 is 4 m; the flow rate of nitrogen gas is 2.5 m / s. The flow rate of the liquid-phase material is 0.002 m / s; the conditions for the epoxidation reaction are: temperature 60°C, pressure 0.2 MPaG, and residence time 1.25 h;

[0101] The first sub-gas phase, the second sub-gas phase, and the third sub-gas phase leave the first sub-catalyst bed 1, the second sub-catalyst bed 2, and the third sub-catalyst bed 3 from the first riser pipe 8, the second riser pipe 9, and the third riser pipe 10 respectively; the first sub-gas phase in the first riser pipe 8 is led out from the gas-phase outlet at the top of the tower reactor RE and converges with the second sub-gas phase and the third sub-gas phase led out from the second riser pipe 9 and the third riser pipe 10 to form a first gas phase. The first gas phase enters the cooling unit HE, is cooled to 2°C, and then enters the gas-liquid separation tank V for gas-liquid separation to obtain a second gas phase and a second liquid phase;

[0102] The second liquid phase is recycled to the liquid-phase outlet of the tower reactor RE, converges with the first liquid phase, and goes to the separation and refining system for refining treatment to obtain the product epichlorohydrin b;

[0103] The second gas phase is pressurized to 0.3 MPaG by the blower BL, and after overcoming the pressure drops of the first gas distribution unit 11, the second gas distribution unit 12, the third gas distribution unit 13, and the corresponding pipelines, it is recycled back into the tower reactor RE through the gas-phase inlet of the tower reactor;

[0104] When the oxygen concentration in the tower reactor RE ≥ 0.8%, part of the second gas phase is discharged from the tail gas outlet of the blower BL until the oxygen concentration drops below 0.5%; when the pressure at the top of the tower reactor RE is lower than 0.16 MPaG, fresh nitrogen is replenished from the nitrogen source to the cooling unit HE, and flows out from the gas phase of the cooling unit into the tower reactor until the pressure rises above 0.2 MPaG.

[0105] After testing, the conversion rate of hydrogen peroxide a in this example is 99.3%, and the yield of epichlorohydrin b is 97.2%.

[0106] Example 3

[0107] It is basically the same as the production device and production method of Example 1. The difference is that a 5-stage catalyst bed is used for the epoxidation reaction of allyl chloride and hydrogen peroxide to prepare epichlorohydrin. The height of the first sub-catalyst bed is 0.8 m, the height of the second sub-catalyst bed is 0.8 m, and the height of the third sub-catalyst bed is 0.8 m; the height of the fourth sub-catalyst bed is 1.0 m; the height of the fifth sub-catalyst bed is 1.0 m, and other conditions remain unchanged.

[0108] After testing, the conversion rate of hydrogen peroxide a in this example is 99.99%, and the yield of epichlorohydrin b is 99.31%.

[0109] By comparing with Example 1, it can be found that since the conversion rate of hydrogen peroxide a is already relatively high, increasing the number of catalyst beds in this example has little effect on further improving the conversion rate of hydrogen peroxide a, but the yield of epichlorohydrin b has increased significantly. The inventor believes through research that on the premise of keeping the total height of the catalyst bed unchanged, increasing the number of catalyst beds reduces the height of each catalyst bed layer, which is more conducive to the timely removal of reaction heat, thereby reducing local overheating and the side reactions caused thereby.

[0110] Example 4

[0111] It is basically the same as the production device and production method of Example 1. The difference is that nitrogen at 10 °C is used for reverse contact with the reaction system in the catalyst bed gap of the tower reactor to compare the reaction effects. Other operating conditions are the same as those in Example 1.

[0112] After testing, the conversion rate of hydrogen peroxide a in this example is 99.99%, and the yield of epichlorohydrin b is 96.92%. The reaction temperature at the lower part of the first sub-catalyst bed is tested to be 56 °C, which is higher than 50 °C in Example 1. The inventor believes through research that it may be that the temperature in this example is higher and the by-products increase, resulting in a slightly lower yield of epichlorohydrin b, but the conversion rate of hydrogen peroxide a is still very high.

[0113] Example 5

[0114] It is basically the same as the production device and production method of Example 1. The difference is that the nitrogen gas flow rate between the catalyst beds is 0.5 m / s for the epoxidation reaction of allyl chloride and hydrogen peroxide to prepare epichlorohydrin to compare the reaction effects. Other operating conditions are the same as those in Example 1.

[0115] After testing, the conversion rate of hydrogen peroxide a in this embodiment is 99.98%, and the yield of epichlorohydrin b is 97.52%. The reaction temperature at the lower part of the first sub-catalyst bed layer is tested to be 54°C, slightly higher than 50°C in Example 1. By comparing with Example 1, it can be found that due to the higher temperature, the by-products increase, resulting in a slightly lower yield of epichlorohydrin b, but the conversion rate of hydrogen peroxide a is still very high.

[0116] Example 6

[0117] It is basically the same as the production device and production method in Example 1, except that the molar ratio of allyl chloride: hydrogen peroxide: methanol is 8:1:4 for the epoxidation reaction of allyl chloride and hydrogen peroxide to prepare epichlorohydrin to compare the reaction effects. Other operating conditions are the same as those in Example 1.

[0118] After testing, the conversion rate of hydrogen peroxide a in this embodiment is 98.20%, and the yield of epichlorohydrin b is 97.41%. By comparing with Example 1, it can be found that the conversion rate of hydrogen peroxide a and the yield of epichlorohydrin b are slightly reduced.

[0119] Example 7

[0120] It is basically the same as the production device and production method in Example 1, except that the liquid phase material flow rate of the catalyst bed layer is 0.005 m / s for the epoxidation reaction of allyl chloride and hydrogen peroxide to prepare epichlorohydrin to compare the reaction effects. Other operating conditions are the same as those in Example 1.

[0121] After testing, the conversion rate of hydrogen peroxide a in this embodiment is 97.11%, and the yield of epichlorohydrin b is 99.15%. The inventor believes through research that perhaps due to the shorter residence time, the conversion rate of hydrogen peroxide a is slightly reduced, and the yield of epichlorohydrin b is still very high.

[0122] Comparative Example 1

[0123] It is basically the same as the production device and production method in Example 1, except that nitrogen at 20°C is used for countercurrent contact with the reaction product in the catalyst bed layer gap of the tower reactor to compare the reaction effects. Other operating conditions are the same as those in Example 1.

[0124] After testing, the conversion rate of hydrogen peroxide a in this embodiment is 99.99%, and the yield of epichlorohydrin b is 92.00%. The reaction temperature at the lower part of the first sub-catalyst bed layer is tested to be 71°C, significantly higher than 50°C in Example 1. The inventor's research shows that due to the higher temperature of nitrogen, the by-products increase, resulting in a significant reduction in the yield of epichlorohydrin b.

[0125] Comparative Example 2

[0126] It is basically the same as the production device and production method of Example 1, except that a conventional fixed-bed reactor is used for the epoxidation of allyl chloride and hydrogen peroxide to prepare epichlorohydrin to compare the reaction effects. The operating conditions are basically the same as those of Example 1, except that a single catalyst bed layer is used, and the bed layer height is 4.4 m, which is the same as the sum of the heights of the three catalyst bed layers in Example 1. In addition, the nitrogen counter-current contact operation is cancelled.

[0127] After testing, the conversion rate of hydrogen peroxide a in this example is 99.2%, and the yield of epichlorohydrin b is 87.4%. The temperature of the catalyst bed layer gradually increases from top to bottom. The temperature at the bottom of the catalyst bed layer is 71.3 °C. Excessive reaction temperature will increase the occurrence of side reactions such as alcoholysis and hydrolysis of epichlorohydrin, reducing the selectivity of the reaction. In addition, too high reaction temperature will also cause part of hydrogen peroxide to decompose to produce oxygen. The oxygen content in the first gas phase is detected by gas chromatography. Without supplementing fresh nitrogen, the oxygen content in the first gas phase reaches 1.8%, and the reaction safety is poor.

[0128] According to the above examples and comparative examples, the production method and production device of epichlorohydrin provided by the present invention can remove the reaction heat to the greatest extent, thereby improving the conversion rate of hydrogen peroxide and the yield of epichlorohydrin, and can also effectively improve the production safety.

[0129] The preferred specific embodiments of the present invention and experimental verification have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A production method of epichlorohydrin, characterized in that, It includes the following steps: The liquid-phase material passes through the liquid-phase inlet of the tower reactor and then the liquid-phase inlet of the catalyst bed layer in sequence, and then flows through the catalyst bed layer to undergo an epoxidation reaction to obtain a reaction system; wherein, the liquid-phase material at least includes allyl chloride, hydrogen peroxide, and a solvent; the catalyst bed layer is arranged in the tower reactor along the direction from the liquid-phase inlet to the gas-phase inlet of the tower reactor; the catalyst bed layer refers to a solid particle bed layer formed by piling up catalyst particles, and the catalyst particles include: titanium silicalite molecular sieve; Nitrogen with a temperature of 1 to 10 °C passing through the gas-phase inlet of the tower reactor is in reverse contact with the reaction system to obtain a first liquid phase and a first gas phase; The first liquid phase is separated to obtain the epichlorohydrin; Based on a cooling unit, the first gas phase is cooled to obtain a second gas phase and a second liquid phase; based on a separation unit, the second liquid phase is separated to obtain the epichlorohydrin; based on a driving unit, the second gas phase is deoxygenated and then returned to be in reverse contact with the reaction system.

2. The production method according to claim 1, characterized in that, The catalyst bed layer includes 1 to 20 sub-catalyst bed layers arranged at intervals, and the height of each sub-catalyst bed layer is independently 0.1 m to 5 m; The liquid-phase material flows through each sub-catalyst bed layer in sequence to undergo an epoxidation reaction.

3. The production method according to claim 1 or 2, characterized in that, The conditions for the epoxidation reaction are: temperature 30 to 70 °C, pressure 0.001 to 0.6 MPaG, and time 0.5 to 6 h.

4. The production method according to claim 1 or 2, characterized in that, In the liquid-phase material, the molar ratio of allyl chloride, hydrogen peroxide, and the solvent is (2 to 8):1:(4 to 60); The solvent is selected from at least one of methanol and ethanol.

5. The production method according to claim 1 or 2, characterized in that, The flow rate of the liquid-phase material in the catalyst bed layer is 0.0005 to 0.005 m / s; and / or, When the reaction system is in reverse contact with nitrogen, the flow rate of nitrogen is 0.5 to 5 m / s.

6. An epoxy chloropropane production device, characterized in that, For implementing the production method according to any one of claims 1-5, the production device at least includes a tower reactor; The liquid-phase inlet of the tower reactor is used to input the liquid-phase material into the tower body, and the gas-phase inlet of the tower reactor is used to input nitrogen into the tower body; the liquid-phase inlet of the tower reactor is located on the top side of the tower, and the gas-phase inlet of the tower reactor is located on the bottom side of the tower; Along the direction from the liquid-phase inlet to the gas-phase inlet of the tower reactor, a catalyst bed layer is provided in the tower reactor; wherein, the catalyst bed layer refers to a solid particle bed layer formed by piling up catalyst particles, and the catalyst particles include: titanium silicalite molecular sieve; The liquid-phase inlet of the catalyst bed layer is communicated with the liquid-phase inlet of the tower reactor, the liquid-phase outlet of the catalyst bed layer is communicated with the liquid-phase outlet of the tower reactor, and the gas-phase inlet of the catalyst bed layer is communicated with the gas-phase inlet of the tower reactor; It further includes a cooling unit and a driving unit. The gas-phase outlet of each sub-catalyst bed layer is respectively communicated with the gas-phase inlet of the cooling unit, and the gas-phase outlet of the cooling unit is communicated with the gas-phase inlet of the driving unit; It further includes a separation unit. The outlet of the cooling unit is communicated with the inlet of the separation unit. The gas-phase outlet of the separation unit is communicated with the gas-phase inlet of the driving unit. The liquid-phase outlet of the separation unit is communicated with the liquid-phase outlet of the tower reactor.

7. The production device according to claim 6, characterized in that, The catalyst bed layer includes 1 to 20 sub-catalyst bed layers arranged at intervals, and the height of each sub-catalyst bed layer is independently 0.1 m to 5 m; The gas-phase inlets of each sub-catalyst bed layer are respectively communicated with the gas-phase inlet of the tower reactor.

8. The production device according to claim 7, characterized in that, It further includes a nitrogen source for providing nitrogen, and the nitrogen source is communicated with the gas-phase inlet of the cooling unit; and / or, At least one liquid distribution unit is further included in the tower reactor; A liquid distribution unit is respectively arranged on one side of each sub-catalyst bed layer close to the liquid-phase inlet of the tower reactor; and / or, At least one gas distribution unit is further included in the tower reactor; A gas distribution unit is respectively arranged on one side of each sub-catalyst bed layer close to the gas-phase inlet of the tower reactor; the gas-phase inlet of the tower reactor is communicated with the gas-phase inlet of the gas distribution unit, and the gas-phase outlet of the gas distribution unit is communicated with the gas-phase inlet of the sub-catalyst bed layer.

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