A nitration apparatus and a method for producing nitrobenzene

Abstract

The present application relates to the technical fields of chemical reactor, and discloses a nitration reaction device and a method for preparing nitrobenzene. The nitration reaction device comprises a reaction cavity, a plurality of reaction channels are arranged in the reaction cavity, each reaction channel is separated into a feeding channel and a discharging channel by a partition plate, a feeding port is arranged at the head end of the feeding channel, a discharging port is arranged at the tail end of the discharging channel, and the tail end of the feeding channel and the head end of the discharging channel are communicated with each other. The device has two channels in one reaction channel, so that the material can be fed and discharged in opposite directions in the two channels. The material flows in opposite directions, which can enhance the heat exchange of the feeding and discharging fluids, and the feeding fluid can be heated by using the self-reaction heat energy in the discharging fluid. The energy consumption is reduced, the material temperature tends to be uniform, the reaction rate can be improved without adding concentrated sulfuric acid catalyst, the reaction heat runaway can be effectively inhibited, the side reaction can be controlled, and the reaction yield can be improved.

Description

Technical Field

[0001] This invention relates to the field of chemical reactor technology, specifically to a nitration reaction apparatus and a method for preparing nitrobenzene. Background Technology

[0002] Nitration reactions play a crucial role in chemical production. Nitrobenzene is an important chemical raw material and intermediate, widely used in the production of pharmaceuticals, dyes, pesticides, explosives, and polyurethane foams. Currently, domestic nitrobenzene production mainly uses isothermal nitration reactors, while internationally, adiabatic nitration reactors are predominantly employed. However, due to the high exothermic and rapid nature of nitration reactions, which primarily occur at the interface between the two phases, localized heat accumulation and limited heat transfer within the reactor can easily lead to thermal runaway accidents. Furthermore, current benzene nitration methods typically use concentrated sulfuric acid as a catalyst. If the reaction system malfunctions and the temperature rises excessively, nitrobenzene and concentrated sulfuric acid will produce nitrobenzenesulfonic acid byproducts, which undergo violent decomposition and exothermic reactions at high temperatures, posing a serious thermal safety hazard. Therefore, controlling heat dissipation between the two phases and managing side reactions during the benzene nitration process is key to achieving both rapid and efficient reaction—that is, accelerating the reaction rate while preventing thermal runaway.

[0003] However, existing technologies have not solved the problems of limited heat transfer, local overheating, numerous side reactions, and thermal runaway in reaction systems. Therefore, it is urgent to find new ways to enhance heat exchange in reaction systems, increase reaction rates, control side reactions, and effectively suppress thermal runaway. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of heat accumulation and limited heat transfer in existing nitration reactors, which lead to thermal runaway of the reaction. This invention provides a nitration reactor and a method for preparing nitrobenzene. This apparatus and method can enhance the heat exchange of the reaction system, increase the reaction rate, control side reactions, and effectively suppress thermal runaway of the reaction without adding concentrated sulfuric acid. This fundamentally improves the problems of heat accumulation and risk of reaction runaway in the reactor.

[0005] To achieve the above objectives, the present invention provides a nitration reaction apparatus, which includes a reaction chamber and a plurality of reaction channels. Each reaction channel is divided into a feed channel and a discharge channel by a partition. The feed channel has a feed inlet at its beginning and a discharge outlet at its end. The end of the feed channel and the beginning of the discharge channel are interconnected.

[0006] Preferably, the partition (3) is a metal plate.

[0007] Preferably, the partition (3) is a high-silicon stainless steel plate or a high-silicon iron plate.

[0008] More preferably, the partition (3) is a C4 high-silicon stainless steel plate.

[0009] Preferably, the number of reaction channels provided in the reaction chamber is 1 to 40, and more preferably 6 to 30.

[0010] Preferably, the feed inlets of two adjacent reaction channels are arranged in the same direction or in opposite directions.

[0011] Preferably, the reaction channels are spaced apart or adjacent to each other.

[0012] Preferably, each reaction channel includes a feed channel cavity wall and a discharge channel cavity wall; two adjacent reaction channels share a feed channel cavity wall or a discharge channel cavity wall; or two adjacent reaction channels share a feed channel cavity wall and a discharge channel cavity wall.

[0013] Preferably, the walls of the feed channel and the discharge channel are made of metal plates;

[0014] Preferably, the walls of the feed channel and the discharge channel are made of high-silicon stainless steel or high-silicon iron.

[0015] More preferably, the walls of the feed channel and the discharge channel are made of C4 high-silicon stainless steel.

[0016] Preferably, the thickness of the partition is 10-200 mm, and more preferably 60-150 mm.

[0017] Preferably, the reaction chamber is rectangular.

[0018] Preferably, the thickness of the reaction chamber is 10–200 mm, and more preferably 60–150 mm.

[0019] Preferably, the length of the reaction channel is 0.5 to 2 m.

[0020] A second aspect of the present invention provides a method for preparing nitrobenzene, the method being carried out in the nitration reaction apparatus described in the first aspect above, the method comprising the following steps:

[0021] S1. Benzene and nitric acid are mixed, and the resulting mixture is injected into the reaction channel from the feed inlet to carry out the reaction;

[0022] S2. The reaction product obtained in step S1 flows out from the discharge port.

[0023] Preferably, in step S1, the molar ratio of benzene to nitric acid is 0.8 to 1.3:1, more preferably 1.1 to 1.2:1.

[0024] Preferably, in step S1, the temperature of the mixture is 5°C to 30°C when it is injected into the reaction channel from the feed inlet.

[0025] Preferably, in step S1, the feed flow rate of the mixture when it is injected into the reaction channel from the feed inlet is 300-1000 g / h.

[0026] Preferably, the length of the reaction channel is 0.5 to 3 m.

[0027] Preferably, step S1 further includes: preheating the temperature of the reaction channel to 70-100°C, preferably 80-90°C, before injecting the mixture into the reaction channel.

[0028] Preferably, in step S2, when the reaction product flows out of the outlet, the temperature of the outlet is 90-150°C, more preferably 120-150°C.

[0029] The novel nitration reaction device provided by this invention is an intrinsically safe benzene nitration reaction device. This device has two channels in one reaction channel, which can allow the material to be fed and discharged in opposite directions in the two channels. The material flows in opposite directions, which can enhance the heat exchange between the feed and discharge fluids, and use the exothermic energy of the discharge stream to heat the feed stream. This saves energy and reduces consumption while making the material temperature more uniform. Thus, the reaction rate can be increased without the need for catalysts such as concentrated sulfuric acid, effectively suppressing thermal runaway, controlling side reactions, thereby increasing the reaction yield and obtaining a high-purity nitrobenzene product.

[0030] Simultaneously, designing materials to proceed in different reaction channels can prevent intermediate products and free radicals generated by uncontrolled reactions in local areas from inducing reactions in fluids in adjacent reaction channels, thereby preventing the reactions in adjacent reaction channels from proceeding in an orderly and stable manner. Attached Figure Description

[0031] Figure 1 This is a top cross-sectional view of the nitration reaction apparatus described in this invention;

[0032] Figure 2 This is a left-side cross-sectional view of the nitration reaction apparatus described in this invention.

[0033] Figure 3 This is a right-side cross-sectional view of the nitration reaction apparatus described in this invention.

[0034] Explanation of reference numerals in the attached figures

[0035] 1. Reaction chamber; 2. Reaction channel; 3. Baffle; 4. Feed channel; 5. Discharge channel; 6. Feed inlet; 7. Discharge outlet; 41. Feed channel cavity wall; 51. Discharge channel cavity wall. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0038] Existing benzene nitration reactions are generally carried out in a reactor. The nitration reaction mainly occurs at the interface between two phases, which can easily lead to local heat accumulation and limited heat transfer in the reactor, resulting in thermal runaway. Furthermore, in order to improve the reaction rate and yield, concentrated sulfuric acid is usually used as a catalyst. Once the reaction system becomes abnormal and the temperature is too high, nitrobenzene and concentrated sulfuric acid will produce nitrobenzenesulfonic acid byproducts, which will decompose violently and release heat at high temperatures, posing a serious thermal safety hazard. Based on this, the present invention provides a device and method that fundamentally improves the problems of heat accumulation and reaction runaway risk in the reaction device.

[0039] This invention provides a nitration reaction apparatus, such as... Figure 1-3 As shown, the nitration reaction device includes a reaction chamber 1, and a plurality of reaction channels 2 are provided in the reaction chamber 1. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed port 6 at its head and a discharge port 7 at its tail. The tail of the feed channel 4 and the head of the discharge channel 5 are connected to each other.

[0040] According to the present invention, the reaction chamber 1 of the nitration reaction apparatus is provided with multiple reaction channels 2, and the reaction can be carried out in different reaction channels 2. This avoids the intermediate products and free radicals generated by the uncontrolled reaction in local areas from reacting with the fluid in the adjacent reaction channels 2, thereby making the reaction in each reaction channel 2 proceed in an orderly and stable manner and improving the reaction yield.

[0041] In this invention, each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 and the discharge channel 5 are respectively provided with a feed port 6 and a discharge port 7. The feed port 6 and the discharge port 7 are located at the same end of each reaction channel 2, and the feed channel 4 and the discharge channel 5 are interconnected at the other end of the feed port 6 and the discharge port 7. When the material enters the feed channel 4 from the feed port 6, it flows out from the discharge port 7 of the discharge channel 5. Therefore, the flow direction of the material in the feed channel 4 and the discharge channel 5 is opposite. The opposite flow direction of the material can promote heat exchange between the feed and discharge fluids, and use the heat energy released by the discharge material itself to heat the feed material. This saves energy and reduces consumption while ensuring that the material temperature tends to be stable and uniform, thereby improving the reaction yield.

[0042] Under preferred conditions, each reaction channel 2 is equipped with a flow guiding device to guide the material from the inlet 6 into the feed channel 4 and out from the outlet 7 of the discharge channel 5, so that the flow direction of the material in the feed channel 4 and the discharge channel 5 is opposite.

[0043] In a preferred embodiment, the partition 3 within each reaction channel 2 is a metal plate. The metal plate can promote heat exchange between opposing flow streams within the reaction channel 2, reduce local heat accumulation, and improve reaction yield.

[0044] The metal plate can be any conventional choice in the art, as long as it can promote heat exchange between the opposing flow streams within the reaction channel 2. Specifically, the partition 3 is a high-silicon stainless steel plate or a high-silicon iron plate; preferably, the partition 3 is a C4 high-silicon stainless steel plate.

[0045] According to the present invention, the number of reaction channels 2 provided in the reaction chamber 1 is not particularly limited and can be selected according to the size of the device. In some specific embodiments, the number of reaction channels 2 provided in the reaction chamber 1 is 1 to 40. In order to improve reaction efficiency and reduce the space occupied by the device, under preferred conditions, it is preferably 6 to 30 channels.

[0046] In a specific embodiment, the reaction chamber 1 is a longitudinal chamber; the location and orientation of the multiple reaction channels 2 within the reaction chamber 1 are not limited.

[0047] Preferably, the reaction chamber 1 has a flat plate structure, that is, the different reaction channels 2 have the same length and are set at the same horizontal height.

[0048] In a specific embodiment, the feed inlets 6 of two adjacent reaction channels 2 can be oriented in the same or opposite directions, without any particular limitation. When the feed inlets 6 of two adjacent reaction channels 2 are oriented in the same direction, all reaction channels 2 form an "E" shape; when the feed inlets 6 of two adjacent reaction channels 2 are oriented in opposite directions, all reaction channels 2 form an "arch" shape.

[0049] According to the present invention, a plurality of reaction channels 2 may be arranged at intervals or adjacent to each other. The interval arrangement means that there is a certain distance between two adjacent reaction channels 2; the adjacent arrangement means that there is no distance between two adjacent reaction channels 2.

[0050] In a specific embodiment, each of the reaction channels 2 includes a feed channel cavity wall 41 and a discharge channel cavity wall 51; the feed channel cavity wall 21 refers to the cavity wall of each reaction channel 2 on the side close to the feed channel 4, and the discharge channel cavity wall 51 refers to the cavity wall of each reaction channel 2 on the side close to the discharge channel 5.

[0051] Under preferred conditions, two adjacent reaction channels 2 share the feed channel cavity wall 41 or the discharge channel cavity wall 51; or the feed channel cavity wall 41 and the discharge channel cavity wall 51 of two adjacent reaction channels 2 are shared.

[0052] In a more preferred embodiment, the feed channel cavity wall 41 and the discharge channel cavity wall 51 of two adjacent reaction channels 2 are shared. In this way, heat exchange between the feed channel 4 and the discharge channel 5 of the two adjacent reaction channels 2 can be promoted, and the heat energy released by the reaction of the material in the discharge channel 5 can heat the material in the feed channel 4.

[0053] In specific embodiments, the materials of the feed channel cavity wall 41 and the discharge channel cavity wall 51 are not limited. Preferably, the feed channel cavity wall 41 and the discharge channel cavity wall 51 are metal plates. Using metal plates for the feed channel cavity wall 41 and the discharge channel cavity wall 51 can promote heat exchange between oppositely flowing materials within each reaction channel 2, reduce localized heat accumulation, and improve reaction yield.

[0054] Preferably, the feed channel cavity wall 41 and the discharge channel cavity wall 51 are made of high-silicon stainless steel plate or high-silicon iron plate; more preferably, the feed channel cavity wall 41 and the discharge channel cavity wall 51 are made of C4 high-silicon stainless steel plate.

[0055] In the nitration reaction apparatus of the present invention, controlling the thickness of the partition 3 can enhance heat dissipation at the reaction interface, control heat accumulation in local areas of the two-phase interface, reduce the generation of by-products, and increase the reaction rate.

[0056] In a preferred embodiment, the thickness of the partition 3 is 10-200mm, preferably 60-150mm, for example, it can be 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm or 150mm.

[0057] According to the present invention, the reaction chamber 1 can be rectangular. In order to enhance heat dissipation within the reaction channel 2 and avoid local heat accumulation leading to reaction runaway, the thickness of the reaction chamber 1 needs to be controlled within a suitable range.

[0058] Under preferred conditions, the thickness of the reaction chamber 1 can be 10-200mm, preferably 60-150mm, for example, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm or 150mm.

[0059] In this invention, the reaction residence time can be controlled by controlling the length of the reaction channel 2, that is, the reaction time can be controlled by controlling the length of the reaction channel 2.

[0060] In some preferred embodiments, the length of the reaction channel 2 is 0.5 to 3 m, for example, it can be 0.5 m, 0.8 m, 1 m, 1.2 m, 1.4 m, 1.5 m, 1.8 m, 2 m, 2.2 m, 2.5 m, 2.8 m or 3 m.

[0061] The nitration reactor described in this invention is particularly suitable for reactions that can proceed spontaneously after the raw materials are mixed, especially for the benzene nitration reaction to prepare nitrobenzene. The reaction in the nitration reactor is typically evaluated for normal progress by monitoring the temperature at the outlet 7. If the temperature at the outlet 7 is within the normal range, it indicates that the reaction within the nitration reactor is normal; if the temperature at the outlet 7 is higher than the normal temperature, it indicates that there is heat accumulation and the reaction is out of control within the nitration reactor.

[0062] In this invention, the reaction raw materials are injected from the feed port 6 into each reaction channel 2 for reaction by using a feeding device, which can be a device commonly used in the art.

[0063] In a more preferred embodiment, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 6 to 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of C4 high-silicon stainless steel. The feed inlets 6 of adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of adjacent reaction channels 2 are shared, and both the feed channel wall 41 and the discharge channel wall 51 are made of C4 high-silicon stainless steel. The thickness of the partition 3 is 60 to 150 mm. The thickness of the reaction chamber 1 is 60 to 150 mm.

[0064] The nitration reactor described in this invention is safe and economical, overcoming the problems of heat accumulation and reaction runaway present in existing industrial nitration reactors. Compared with existing technologies, on the one hand, it can enhance heat transfer in the reaction system, achieve uniform and controllable temperature range, avoid local heat accumulation, increase reaction rate, and save energy and reduce consumption; on the other hand, the device uses a method of direct synthesis of nitrobenzene from benzene and nitration, which, compared with the existing concentrated sulfuric acid catalytic method, avoids the nitrobenzene sulfonic acid side reaction, reduces the risk of process thermal runaway, and achieves inherent process safety.

[0065] A second aspect of the present invention provides a method for preparing nitrobenzene, wherein, under preferred conditions, the method is carried out in the nitration reaction apparatus described in the first aspect above.

[0066] The method for preparing nitrobenzene according to the present invention includes:

[0067] S1. Benzene and nitric acid are mixed, and the resulting mixture is injected into the reaction channel 2 from the feed port 6 to carry out the reaction;

[0068] S2. The reaction product obtained in step S1 flows out from the discharge port 7.

[0069] The method of this invention directly synthesizes nitrobenzene from benzene and nitric acid without the need for concentrated sulfuric acid as a catalyst. The mixture of benzene and nitric acid is injected into the reaction channel 2, flowing in through the feed channel 4 and out through the discharge channel 5. The flow directions of the material are opposite, thereby enhancing the heat exchange between the feed and discharge fluids. Furthermore, the exothermic energy of the discharge stream itself is used to heat the feed stream, saving energy and reducing consumption while ensuring that the material temperature tends to be stable and uniform, thus improving the reaction yield.

[0070] According to the present invention, in some specific embodiments, in step S1, the molar ratio of benzene to nitric acid can be 0.8 to 1.3:1, preferably 1.1 to 1.2:1.

[0071] According to the present invention, in some specific embodiments, in step S1, when the mixture is injected into the reaction channel 2 from the feed port 6, the temperature of the mixture can be 5°C to 30°C, for example, 5°C, 10°C, 15°C, 20°C, 25°C or 30°C.

[0072] To increase the reaction rate and prevent local heat accumulation and reaction runaway in reaction channel 2, the feed flow rate needs to be controlled within an appropriate range.

[0073] Under preferred conditions, in step S1, the feed flow rate of the mixture when it is injected into the reaction channel 2 from the feed inlet (6) is 300-1000 g / h, for example, it can be 300 g / h, 400 g / h, 500 g / h, 600 g / h, 700 g / h, 800 g / h, 900 g / h or 1000 g / h.

[0074] In this invention, the reaction residence time can be controlled by controlling the length of the reaction channel 2, that is, the reaction time can be controlled by controlling the length of the reaction channel 2.

[0075] In some preferred embodiments, the length of the reaction channel 2 can be 0.5 to 2 m, for example, 0.5 m, 0.8 m, 1 m, 1.2 m, 1.4 m, 1.5 m, 1.8 m or 2 m.

[0076] According to the present invention, in order to better carry out the reaction, step S1 further includes: before injecting the mixture into the reaction channel 2, preheating the temperature of the reaction channel 2 to 70-100°C, preferably 80-90°C, during the initial start-up reaction.

[0077] The method described in this invention evaluates whether the reaction is proceeding normally by monitoring the temperature of the discharge port 7. If the temperature of the discharge port 7 is within the normal range, it indicates that the reaction in the nitration reactor is normal; if the temperature of the discharge port 7 is higher than the normal temperature, it indicates that there is heat accumulation and reaction runaway in the nitration reactor.

[0078] In some preferred embodiments, in step S2, when the reaction product flows out of the outlet 7, the temperature of the outlet 7 can be 90 to 150°C, preferably 120 to 150°C, for example 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C.

[0079] Furthermore, after the reaction product flows out of the outlet 7, it is cooled by air and water. The resulting product is then washed with water and purified by distillation to obtain the nitrobenzene product. The distillation purification method can be carried out according to conventional procedures in the art.

[0080] The present invention will be described in detail below through examples, but the scope of protection of the present invention is not limited thereto. In the following examples, all reagents are commercially available products.

[0081] In the following examples, the concentration of nitric acid is 63% by weight.

[0082] In this invention, the purity of nitrobenzene in the nitrobenzene product is the mass fraction of nitrobenzene component in the total product; the reaction yield is the amount of nitrobenzene generated / the theoretical amount of nitrobenzene generated when the reactants are completely converted.

[0083] Example 1

[0084] Example 1 was carried out in the following nitration reaction apparatus, such as Figure 1-3 As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. Ten reaction channels 2 are arranged within the reaction chamber 1. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of C4 high-silicon stainless steel. The feed inlets 6 of two adjacent reaction channels 2 are arranged in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of two adjacent reaction channels 2 are shared. The feed channel wall 41 and the discharge channel wall 51 are both made of C4 high-silicon stainless steel. The partition 3 is 120 mm thick. The reaction chamber 1 is 120 mm thick, and the reaction channel 2 is 2 m long.

[0085] Methods for preparing nitrobenzene include:

[0086] S1. Benzene and nitric acid are mixed at room temperature (25°C) in a molar ratio of 1.1, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 80°C and the feed flow rate is controlled at 600g / h.

[0087] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 140-143℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0088] Testing revealed that the purity of nitrobenzene in the purified product (the mass fraction of nitrobenzene component in the total product) was 99.6 wt% to 99.9 wt%, the reaction yield (the amount of nitrobenzene produced / the theoretical amount of nitrobenzene produced when the reactants are completely converted) was 96 wt% to 99 wt%, and the highest temperature difference at the outlet under abnormal operating conditions of the equipment during the entire reaction process was 3℃.

[0089] Example 2

[0090] Example 2 was carried out in the following nitration reaction apparatus, such as Figure 1-3 As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 20 reaction channels 2, each of which is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of C4 high-silicon stainless steel. The feed inlets 6 of adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of adjacent reaction channels 2 are shared, and both are made of C4 high-silicon stainless steel. The partition 3 is 150 mm thick. The reaction chamber 1 is 150 mm thick, and the reaction channel 2 is 2 m long.

[0091] Methods for preparing nitrobenzene include:

[0092] S1. Benzene and nitric acid are mixed at room temperature (20°C) in a molar ratio of 1.2, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 80°C and the feed flow rate is controlled at 800g / h.

[0093] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 142-145℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0094] Tests showed that the purity of nitrobenzene in the purified product was 99.5 wt% to 99.8 wt%, the reaction yield was 95 wt% to 99 wt%, and the highest temperature difference at the outlet under abnormal operating conditions of the equipment during the entire reaction process was 3.5℃.

[0095] Example 3

[0096] Example 3 was carried out in the following nitration reaction apparatus, such as Figure 1-3 As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 20 reaction channels 2, each of which is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of high-silicon iron plate. The feed inlets 6 of adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of adjacent reaction channels 2 are shared, and both are made of high-silicon iron plate. The partition 3 is 60 mm thick. The reaction chamber 1 is 60 mm thick, and the length of each reaction channel 2 is 2.5 m.

[0097] Methods for preparing nitrobenzene include:

[0098] S1. Benzene and nitric acid are mixed at room temperature (10°C) in a molar ratio of 1.0. The resulting mixture is then injected into the reaction channel 2 through the feed inlet 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 90°C and the feed flow rate is controlled at 400 g / h.

[0099] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 138-141℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0100] Testing revealed that the purity of nitrobenzene in the purified product was 99.0 wt% to 99.5 wt%, the reaction yield was 93 wt% to 98 wt%, and the highest temperature difference at the outlet under abnormal operating conditions during the entire reaction process was 2℃.

[0101] Example 4

[0102] Example 4 was carried out in the following nitration reaction apparatus, such as Figure 1-3 As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains six reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of high-silicon iron plate. The feed inlets 6 of adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of adjacent reaction channels 2 are shared, and both are made of high-silicon iron plate. The partition 3 is 100 mm thick. The reaction chamber 1 is 100 mm thick, and the reaction channel 2 is 3 m long.

[0103] Methods for preparing nitrobenzene include:

[0104] S1. Benzene and nitric acid are mixed at a molar ratio of 0.8 at room temperature (30°C), and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 80°C, and the feed flow rate is controlled at 1000g / h.

[0105] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 146-148℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0106] The purity of the purified nitrobenzene product was found to be 99.0 wt% to 99.5 wt%, and the reaction yield was 92 wt% to 97 wt%. During the entire reaction process, the highest temperature difference at the discharge port under abnormal operating conditions was 2℃.

[0107] Example 5

[0108] Example 5 was carried out in the following nitration reaction apparatus, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of high-silicon iron plate. The feed inlets 6 of two adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of two adjacent reaction channels 2 are shared, and both are made of high-silicon iron plate. The partition 3 is 150 mm thick. The reaction chamber 1 is 150 mm thick, and the reaction channel 2 is 1.5 m long.

[0109] Methods for preparing nitrobenzene include:

[0110] S1. Benzene and nitric acid are mixed at room temperature (5°C) in a molar ratio of 0.9, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 90°C and the feed flow rate is controlled at 500g / h.

[0111] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 143-146℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0112] Testing revealed that the purity of nitrobenzene in the purified product was 99.2%–99.6%, the reaction yield was 92%–95%, and the highest temperature difference at the outlet under abnormal operating conditions during the entire reaction process was 3.2℃.

[0113] Example 6

[0114] Example 6 was carried out in the following nitration reaction apparatus, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of C4 high-silicon stainless steel. The feed inlets 6 of adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of adjacent reaction channels 2 are shared. The feed channel wall 41 and the discharge channel wall 51 are both made of C4 high-silicon stainless steel. The partition 3 is 80 mm thick. The reaction chamber 1 is 80 mm thick, and the reaction channel 2 is 1.0 m long.

[0115] Methods for preparing nitrobenzene include:

[0116] S1. Benzene and nitric acid are mixed at room temperature (20°C) in a molar ratio of 1.2, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 85°C and the feed flow rate is controlled at 500g / h.

[0117] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 135-140℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0118] Tests showed that the purity of nitrobenzene in the purified product was 99.6 wt% to 99.8 wt%, the reaction yield was 92 wt% to 95 wt%, and the highest temperature difference at the outlet under abnormal operating conditions of the equipment during the entire reaction process was 3.5℃.

[0119] Example 7

[0120] Example 7 was carried out in the following nitration reaction apparatus, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of C4 high-silicon stainless steel. The feed inlets 6 of two adjacent reaction channels 2 are arranged in opposite directions, and all reaction channels 2 are in an overall "bow" shape; all reaction channels 2 are arranged adjacent to each other; the feed channel cavity wall 41 and the discharge channel cavity wall 51 of two adjacent reaction channels 2 are shared, and the feed channel cavity wall 41 and the discharge channel cavity wall 51 are made of C4 high silicon stainless steel plate; the thickness of the partition 3 is 140mm; the thickness of the reaction chamber 1 is 140mm, and the length of the reaction channel 2 is 1.4m.

[0121] Methods for preparing nitrobenzene include:

[0122] S1. Benzene and nitric acid are mixed at room temperature (25°C) in a molar ratio of 1.1, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 90°C and the feed flow rate is controlled at 700 g / h.

[0123] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 138-143℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0124] Tests showed that the purity of nitrobenzene in the purified product was 99.5 wt% to 99.7 wt%, the reaction yield was 93 wt% to 94 wt%, and the highest temperature difference at the outlet under abnormal operating conditions of the equipment during the entire reaction process was 2.8℃.

[0125] Example 8

[0126] Example 8 was carried out in the following nitration reaction apparatus, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is a high-silicon iron metal plate. The feed inlets 6 of two adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of two adjacent reaction channels 2 are shared. The feed channel wall 41 and the discharge channel wall 51 are both made of high-silicon iron metal plates. The partition 3 has a thickness of 160 mm. The reaction chamber 1 has a thickness of 160 mm, and the reaction channel 2 has a length of 1.8 m.

[0127] Methods for preparing nitrobenzene include:

[0128] S1. Benzene and nitric acid are mixed at room temperature (30°C) in a molar ratio of 1.2, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 90°C and the feed flow rate is controlled at 700 g / h.

[0129] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 145-150℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0130] Testing revealed that the purity of nitrobenzene in the purified product was 99.2 wt% to 99.5 wt%, the reaction yield was 90 wt% to 93 wt%, and the highest temperature difference at the outlet under abnormal operating conditions during the entire reaction process was 3.8 ℃.

[0131] Example 9

[0132] Example 9 was carried out in the following nitration reaction apparatus, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of high-silicon iron plate. The feed inlets 6 of two adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of two adjacent reaction channels 2 are shared, and both are made of high-silicon iron plate. The partition 3 is 10 mm thick. The reaction chamber 1 is 10 mm thick, and the length of each reaction channel 2 is 0.5 m.

[0133] Methods for preparing nitrobenzene include:

[0134] S1. Benzene and nitric acid are mixed at room temperature (15°C) in a molar ratio of 1.1, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 90°C and the feed flow rate is controlled at 300g / h.

[0135] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 120-125℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0136] Testing revealed that the purity of nitrobenzene in the purified product was 99.0 wt% to 99.5 wt%, the reaction yield was 90 wt% to 95 wt%, and the highest temperature difference at the outlet under abnormal operating conditions during the entire reaction process was 5.2℃.

[0137] Example 10

[0138] Example 10 was carried out in the following nitration reaction apparatus, such as Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. The reaction chamber 1 contains 30 reaction channels 2. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is made of high-silicon iron plate. The feed inlets 6 of two adjacent reaction channels 2 are oriented in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of two adjacent reaction channels 2 are shared. The feed channel wall 41 and the discharge channel wall 51 are both made of high-silicon iron plate. The partition 3 is 200 mm thick. The reaction chamber 1 is 200 mm thick, and the reaction channel 2 is 2 m long.

[0139] Methods for preparing nitrobenzene include:

[0140] S1. Benzene and nitric acid are mixed at room temperature (5°C) in a molar ratio of 1.1, and the resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 80°C and the feed flow rate is controlled at 900 g / h.

[0141] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 110-115℃ (the temperature of the outlet 7 of different reaction channels 2 is slightly different). The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0142] Testing revealed that the purity of nitrobenzene in the purified product was 98.5 wt%–98.9 wt%, the reaction yield was 89 wt%–92 wt%, and the highest temperature difference at the outlet under abnormal operating conditions during the entire reaction process was 6.5 ℃.

[0143] Comparative Example 1

[0144] Comparative Example 1 was carried out in the following nitration reaction apparatus, such as... Figure 1-3As shown, the nitration reaction apparatus includes a reaction chamber 1, which can be rectangular and has a flat plate structure. Two reaction channels 2 are arranged within the reaction chamber 1. Each reaction channel 2 is divided into a feed channel 4 and a discharge channel 5 by a partition 3. The feed channel 4 has a feed inlet 6 at its beginning, and the discharge channel 5 has a discharge outlet 7 at its end. The end of the feed channel 4 and the beginning of the discharge channel 5 are interconnected. The partition 3 is a high-silicon iron plate. The feed inlets 6 of two adjacent reaction channels 2 are arranged in opposite directions, and all reaction channels 2 are generally in an "arch" shape. All reaction channels 2 are arranged adjacent to each other. The feed channel wall 41 and the discharge channel wall 51 of two adjacent reaction channels 2 are shared, and both the feed channel wall 41 and the discharge channel wall 51 are made of high-silicon iron plate. The partition 3 has a thickness of 40 mm. The reaction chamber 1 has a thickness of 40 mm, and the reaction channel 2 has a length of 1.8 m.

[0145] Methods for preparing nitrobenzene include:

[0146] S1. Benzene, nitric acid and sulfuric acid (concentration of 98% by weight) are mixed at room temperature (22°C) in a molar ratio of 1:1.1:2. The resulting mixture is injected into the reaction channel 2 through the feed port 6 of each reaction channel 2 for reaction. When starting the reaction for the first time, the temperature of the reaction channel 2 is preheated to 80°C and the feed flow rate is controlled at 300g / h.

[0147] S2. The reaction product obtained in step S1 flows out from the outlet 7. The temperature of the outlet 7 of each reaction channel 2 is measured to be 165-170°C. The material at the outlet 7 is cooled by air and water and then fed into the nitrobenzene storage tank. After washing with water and distillation separation and purification, the nitrobenzene product is obtained.

[0148] Tests showed that the purity of nitrobenzene in the purified product was 60wt% to 80wt%, the reaction yield was 50wt% to 55wt%, and the highest temperature difference at the outlet under abnormal operating conditions of the equipment during the entire reaction process was 20℃.

[0149] Comparative Example 2

[0150] The benzene nitration reaction was carried out in a traditional jacketed fixed-bed isothermal nitration stirred tank reactor (1m inner diameter, 0.8m height, and 150r / min stirring speed). Benzene and nitric acid were mixed in a molar ratio of 1.1:1 and reacted at 80℃. The product and temperature were measured without cooling medium.

[0151] Tests showed that the purity of nitrobenzene in the purified reaction product was 35wt% to 40wt%, and the highest temperature difference during the process under abnormal operating conditions was 185℃.

[0152] The results of Examples 1-10 and Comparative Example 1 demonstrate that the method for directly synthesizing nitrobenzene from benzene and nitric acid exhibits a more stable reactor temperature and significantly reduced side reactions compared to the traditional method using concentrated sulfuric acid as a catalyst. The results of Examples 1-10 and Comparative Example 2 demonstrate that, compared to the traditional isothermal nitration reactor, Figure 1 The benzene nitration reactor shown can effectively prevent runaway reaction and is an intrinsically safe reactor.

[0153] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing nitrobenzene, characterized in that, The method is implemented in a nitration reaction device, which includes a reaction chamber (1) and a plurality of reaction channels (2) are provided in the reaction chamber (1). Each reaction channel (2) is divided into a feed channel (4) and a discharge channel (5) by a partition (3). The partition (3) is a metal plate. The feed channel (4) has a feed port (6) at the beginning and a discharge port (7) at the end of the discharge channel (5). The end of the feed channel (4) and the beginning of the discharge channel (5) are connected to each other. Several reaction channels (2) are set adjacent to each other, and the feed inlets (6) of two adjacent reaction channels (2) are set in the same direction or in opposite directions; Each of the reaction channels (2) includes a feed channel cavity wall (41) and a discharge channel cavity wall (51), the feed channel cavity wall (41) and the discharge channel cavity wall (51) being metal plates; the feed channel cavity wall (41) and the discharge channel cavity wall (51) of two adjacent reaction channels (2) are shared; The method includes the following steps: S1. Benzene and nitric acid are mixed, and the resulting mixture is injected into the reaction channel (2) from the feed port (6) to carry out the reaction; S2, The reaction product obtained in step S1 flows out from the discharge port (7).

2. The method according to claim 1, characterized in that, The partition (3) is a high-silicon stainless steel plate or a high-silicon iron plate.

3. The method according to claim 1, characterized in that, The partition (3) is a C4 high-silicon stainless steel plate.

4. The method according to claim 1, characterized in that, The number of reaction channels (2) set in the reaction chamber (1) is 6 to 30.

5. The method according to claim 1, characterized in that, The feed channel cavity wall (41) and the discharge channel cavity wall (51) are made of high silicon stainless steel plate or high silicon iron plate.

6. The method according to claim 1, characterized in that, The feed channel cavity wall (41) and the discharge channel cavity wall (51) are made of C4 high silicon stainless steel plate.

7. The method according to claim 1, characterized in that, The thickness of the partition (3) is 10~200mm.

8. The method according to claim 7, characterized in that, The thickness of the partition (3) is 60~150mm.

9. The method according to claim 1, characterized in that, The reaction chamber (1) is rectangular.

10. The method according to claim 1 or 9, characterized in that, The thickness of the reaction chamber (1) is 10~200mm.

11. The method according to claim 10, characterized in that, The thickness of the reaction chamber (1) is 60~150mm.

12. The method according to claim 1, characterized in that, In step S1, the molar ratio of benzene to nitric acid is 0.8~1.3:

1.

13. The method according to claim 12, characterized in that, In step S1, the molar ratio of benzene to nitric acid is 1.1~1.2:

1.

14. The method according to claim 1, characterized in that, In step S1, the temperature of the mixture is 5°C to 30°C when it is injected into the reaction channel (2) from the feed port (6).

15. The method according to claim 1, characterized in that, In step S1, the feed flow rate of the mixture when it is injected into the reaction channel (2) from the feed port (6) is 300~1000g / h.

16. The method according to claim 1, characterized in that, The length of the reaction channel (2) is 0.5~3m.

17. The method according to claim 1, characterized in that, Step S1 further includes: preheating the temperature of the reaction channel (2) to 70-100°C before injecting the mixture into the reaction channel (2).

18. The method according to claim 17, characterized in that, Step S1 further includes: preheating the temperature of the reaction channel (2) to 80~90°C before injecting the mixture into the reaction channel (2).

19. The method according to claim 1, characterized in that, In step S2, the temperature of the outlet (7) is 90~150°C when the reaction product flows out from the outlet (7).

20. The method according to claim 19, characterized in that, In step S2, the temperature of the outlet (7) is 120~150°C when the reaction product flows out from the outlet (7).

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