Method for continuously preparing ethylene sulfate

Abstract

The invention relates to a method for continuously preparing ethylene sulfate, which comprises the following steps: preparing ethylene sulfate by using a fixed bed reactor, the fixed bed reactor comprises a reaction module, a temperature control module, a temperature measurement module and a control system, and the reaction module comprises a temperature control cavity and a reaction cavity which are separated by a partition plate; the temperature control module comprises a heat exchange pipeline spirally wound on the outer wall of the reaction cavity, a first heat exchanger and a second heat exchanger; the method further comprises the following steps: (1) heating the reaction cavity to a set temperature; and (2) reaction raw materials are introduced into the reaction cavity for reaction, a control system controls operation parameters of the first heat exchanger and the second heat exchanger according to the temperature fed back by the temperature measuring assembly, and the difference value between the temperature of each area of the reaction cavity and the set temperature is controlled to be-1 DEG C to 1 DEG C. By accurately controlling the temperature of the reaction cavity, high-concentration reaction of ethylene sulfite and hydrogen peroxide is realized, the utilization rate of a solvent and hydrogen peroxide is effectively increased, the conversion rate of reaction raw materials is high, and the product selectivity is good.

Description

Technical Field

[0001] The invention relates to the technical field of vinyl sulfate preparation, and in particular to a method for continuously preparing vinyl sulfate. Background Art

[0002] At present, there are two main methods for preparing vinyl sulfate: direct addition of sulfur trioxide and ethylene oxide and oxidation synthesis of vinyl sulfite. The raw materials used in the direct addition of sulfur trioxide and ethylene oxide process are highly toxic and volatile, and the production process is under high pressure, which requires high production facilities and safety response measures. In contrast, the oxidation reaction conditions of vinyl sulfite are mild, the process is simple, and the production cost is low. It is the current mainstream industrial process for producing vinyl sulfate.

[0003] Patent CN116425715A provides a method for preparing vinyl sulfate by continuously oxidizing vinyl sulfite. By replacing the traditional kettle reactor with a fixed bed reactor, the reaction operation is simplified and the reaction time is shortened. However, the method requires mixing vinyl sulfite with a large amount of organic solvent to prepare a 10wt% vinyl sulfite solution feed. The amount of solvent used is too large, which increases the solvent cost, the subsequent solvent recovery cost and the cost of treating wastewater. At the same time, a low raw material concentration will reduce the production capacity of the device.

[0004] Patent CN118530214A provides a production process for synthesizing vinyl sulfate by oxidation of vinyl sulfite. Similar to the above patent, the patent also realizes the continuous reaction by adopting a fixed bed reactor. However, the patent also requires mixing vinyl sulfite with a large amount of organic solvent to prepare a vinyl sulfite solution with a mass fraction of 5%, and also requires the addition of acetone or n-butanol, which not only increases the cost of raw materials but also makes solvent recovery more difficult. In addition, the molar ratio of hydrogen peroxide to vinyl sulfite in the patent is 2 to 3:1, and the utilization rate of hydrogen peroxide is low.

[0005] In summary, the method of preparing vinyl sulfate using a fixed bed reactor has the problem of low utilization rate of solvent and hydrogen peroxide. Summary of the invention

[0006] The object of the present invention is to provide a method for continuously preparing vinyl sulfate, which has high conversion rate and high selectivity, and at the same time, higher raw material utilization rate and better atom economy.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for continuously preparing vinyl sulfate, using a fixed bed reactor to prepare the vinyl sulfate, the fixed bed reactor comprising a reaction module, a temperature control module, a temperature measurement module and a control system,

[0009] The reaction module comprises a shell, a cavity formed by the shell, and a partition arranged in the cavity, wherein the partition separates the cavity into a temperature control cavity and a reaction cavity located in the temperature control cavity, the top and bottom of the shell are respectively provided with a feeding channel and a discharge port connected to the reaction cavity, the side wall of the shell is provided with a liquid inlet and a liquid outlet connected to the temperature control cavity, and the reaction cavity is filled with a catalyst;

[0010] The temperature control module comprises a heat exchange pipe spirally wound along the outer wall of the reaction chamber, and a first heat exchanger and a second heat exchanger arranged outside the shell and controlled by the control system, the liquid inlet and the liquid outlet of the heat exchange pipe are connected to the first heat exchanger, and the liquid inlet and the liquid outlet of the shell are connected to the second heat exchanger;

[0011] The temperature measurement module includes a plurality of temperature measurement components arranged in the reaction chamber along the height direction, and the temperature measurement components are used to collect temperature and can feed back the collected temperature to the control system in real time.

[0012] The method comprises the following steps:

[0013] (1) starting the first heat exchanger and the second heat exchanger, and introducing circulating fluid into the heat exchange pipe and the temperature control chamber respectively, so that the reaction chamber is raised to a set temperature;

[0014] (2) the reaction raw materials are introduced into the reaction chamber through the feeding channel for reaction, and the control system controls the operating parameters of the first heat exchanger and the second heat exchanger according to the temperature feedback from the temperature measuring component, so that the difference between the temperature of each area of ​​the reaction chamber and the set temperature is controlled within -1°C to 1°C,

[0015] The reaction raw materials include ethylene sulfite and hydrogen peroxide.

[0016] The reaction of synthesizing vinyl sulfate from the oxidation of vinyl sulfite is a highly exothermic reaction, and hydrolysis of raw materials and products or other side reactions are likely to occur during the reaction, thereby affecting the conversion rate of raw materials and the selectivity of products. The present invention designs a reaction module of a fixed bed reactor, separates the cavity of the reaction module into a temperature control cavity and a reaction cavity, and introduces a circulating liquid into the temperature control cavity through a heat exchanger, so as to control the temperature of the reaction cavity. Furthermore, by installing a heat exchange pipe on the outside of the reaction cavity, the reaction cavity can be accurately temperature controlled in combination with the heat exchange pipe. In addition, the present invention also performs real-time temperature measurement of different areas of the reaction cavity through a temperature measurement module, and further automatically adjusts the operating parameters of the heat exchanger through a control system, effectively controlling the temperature of each area in the reaction cavity to remain basically unchanged, achieving a high-concentration reaction while ensuring a high conversion rate of the reaction raw materials and a high selectivity of the product. The fixed bed reactor of the present invention has accurate temperature control and a high degree of automation.

[0017] Preferably, the difference between the temperature of each area of ​​the reaction chamber and the set temperature is controlled at -0.8° C. to 0.8° C., more preferably -0.5° C. to 0.5° C. During the reaction, the smaller the temperature fluctuation of the reaction chamber is, the more conducive it is to improving the conversion rate of the raw materials and the selectivity of the products.

[0018] Preferably, step (1) further comprises: after the reaction chamber is heated to a set temperature, the control system controls the operating parameters of the first heat exchanger and the second heat exchanger according to the temperature feedback from the temperature measuring component, so that the difference between the temperature of each area of ​​the reaction chamber and the set temperature is controlled within a range of -1°C to 1°C, more preferably -0.8°C to 0.8°C, and even more preferably -0.5 to 0.5°C.

[0019] Preferably, the vinyl sulfite is fed in the form of a vinyl sulfite solution, the vinyl sulfite solution comprises vinyl sulfite and an organic solvent, and the mass concentration of the vinyl sulfite in the vinyl sulfite solution is 30-55%.

[0020] More preferably, the mass concentration of vinyl sulfite in the vinyl sulfite solution is 35-50%, for example, 35%, 40%, 45%, 50%.

[0021] Preferably, the feed rate of the vinyl sulfite solution is controlled to be 80-150 mL / min, more preferably 80-120 mL / min, and even more preferably 90-110 mL / min, for example 90 mL / min, 95 mL / min, 100 mL / min, 105 mL / min, and 100 mL / min.

[0022] Preferably, the organic solvent is selected from one or more carbonate solvents.

[0023] In some embodiments, the carbonate solvent includes dimethyl carbonate and diethyl carbonate.

[0024] Preferably, the mass concentration of the hydrogen peroxide is 40-50%.

[0025] Preferably, the feed rate of the hydrogen peroxide is controlled to be 20-45 mL / min, more preferably 25-35 mL / min, and further preferably 27-32 mL / min, for example 27 mL / min, 28 mL / min, 29 mL / min, 30 mL / min, 31 mL / min, and 32 mL / min.

[0026] Preferably, the set temperature is 55-75°C, more preferably 65-75°C, and even more preferably 68-72°C.

[0027] Preferably, the residence time of the vinyl sulfite in the reaction chamber is 150 to 250 s, more preferably 180 to 220 s, and even more preferably 190 to 210 s.

[0028] Preferably, the reaction pressure of the reaction chamber is 0.2-0.5 MPa, more preferably 0.2-0.3 MPa.

[0029] In some embodiments, the discharge port of the housing is connected to a discharge pipe, and a back pressure valve is installed on the discharge pipe. The pressure in the reaction chamber can be adjusted by the back pressure valve, and the details can be referred to the prior art.

[0030] Preferably, the method further comprises mixing the reaction raw materials and preheating them to 50-65° C. before introducing them into the feeding channel.

[0031] In some embodiments, the fixed bed reactor also includes a mixing and emulsification preheating device for mixing and heating the reaction raw materials. The feed end of the mixing and emulsification preheating device is connected to a plurality of feed pipes, each feed pipe is provided with a valve, and the discharge end of the mixing and emulsification preheating device is connected to the feeding channel.

[0032] Preferably, the operating parameters include the inlet flow rate, outlet flow rate and circulating liquid temperature of the heat exchanger.

[0033] Preferably, the temperature of the heat exchange pipe is controlled not to be higher than the reaction temperature. If the temperature is controlled only by the temperature control chamber, the temperature of the reaction chamber can only be roughly maintained at the set temperature, and it is impossible to accurately control the temperature in real time; and if the temperature is controlled only by the heat exchange pipe, the temperature of the reaction chamber will also cause large fluctuations in the temperature. The present invention can accurately control the temperature of the reaction chamber in real time through the combination of the temperature control chamber and the heat exchange pipe. In particular, when the temperature of the reaction chamber is too high, the heat exchange pipe can quickly take away the heat, so that the reaction chamber is always kept at the set temperature.

[0034] Preferably, the temperature measuring component comprises a plurality of thermocouples arranged at intervals around the axis of the shell, and the thermocouples are connected to the control system.

[0035] Further preferably, each group of temperature measurement components has 10 to 15 thermocouples.

[0036] In some implementations, the temperature measurement components have 4 to 8 groups.

[0037] Preferably, the diameter of the heat exchange pipe is 20 to 100 mm, more preferably 40 to 60 mm.

[0038] Preferably, the distance between two adjacent upper and lower heat exchange pipes is 1 to 10 mm, more preferably 1 to 5 mm, and even more preferably 1 to 3 mm.

[0039] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0040] The present invention can accurately control the temperature of the reaction chamber by designing a fixed bed reactor, realize a high-concentration reaction of vinyl sulfite and hydrogen peroxide, and effectively improve the utilization rate of the solvent and hydrogen peroxide and the production capacity of the fixed bed reactor; at the same time, the present invention also has the advantages of high conversion rate of reaction raw materials and good product selectivity.

[0041] The preparation method of the invention has the advantages of simple operation, high automation and good continuity, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural diagram of a fixed bed reactor of the present invention;

[0043] Figure 2 It is a structural schematic diagram of a reaction module of the present invention;

[0044] Figure 3 for Figure 2 Section view on plane AA;

[0045] Among them, 1, shell; 11, partition; 12, temperature control chamber; 13, reaction chamber; 14, feeding channel; 15, discharge port; 16, temperature control chamber liquid inlet; 17, temperature control chamber liquid outlet; 18, heat exchange pipe liquid inlet; 19, heat exchange pipe liquid outlet;

[0046] 2. Mixing emulsification preheating device; 21. First feed pipeline; 22. Second feed pipeline; 23. Third feed pipeline; 25. First control valve; 26. Second control valve; 27. Third control valve;

[0047] 4. The first heat exchanger;

[0048] 5. Second heat exchanger;

[0049] 6. Heat exchange pipe;

[0050] 7. Temperature measurement component; 71. Thermocouple;

[0051] 8. Oil-water separation tank;

[0052] 9. Control system;

[0053] 10. Back pressure valve. DETAILED DESCRIPTION

[0054] Compared with the traditional kettle reaction, the preparation of vinyl sulfate by oxidation of vinyl sulfite using a fixed bed reactor has good continuity and short reaction time. However, since the reaction is a highly exothermic reaction, the temperature inside the reactor is easy to rise, which will affect the raw material conversion rate and product selectivity. In order to improve the conversion rate and selectivity, the prior art usually uses a large amount of organic solvents mixed with vinyl sulfite to prepare a low-concentration vinyl sulfite solution for oxidation reaction. However, the use of a large amount of organic solvents results in low utilization of organic solvents, increases raw material costs and subsequent separation costs, and also reduces the production capacity of the reactor. It is even necessary to invest more hydrogen peroxide to ensure that the reaction is fully carried out, which will lead to a waste of raw materials and increase the difficulty and cost of subsequent solvent recovery.

[0055] Based on this, the inventor has provided a method for continuously preparing vinyl sulfate after a large number of experimental studies. By improving the fixed bed reactor, a partition is added in the reactor to separate the cavity into a temperature control cavity and a reaction cavity. By introducing a circulating liquid into the temperature control cavity and using a heat exchanger to exchange heat for the circulating liquid, the temperature of the reaction cavity is basically kept constant. A heat exchange pipe is further provided on the outer wall of the reaction cavity. The heat exchange pipe can take away the heat released by the reaction in the reaction cavity in time to avoid the occurrence of side reactions such as hydrolysis of raw materials and products caused by overheating of the reaction cavity, so that the temperature of the reaction cavity can be accurately controlled to ensure high conversion rate and high selectivity when using high-concentration vinyl sulfite solution and hydrogen peroxide reaction, effectively improving the utilization rate of solvents and hydrogen peroxide and the production capacity of fixed bed reactors. The present invention also designs a temperature measurement module and a control system, and uses the control system to control the operating parameters of the heat exchanger, thereby automatically controlling the flow rate and temperature of the circulating liquid in the temperature control cavity and the heat exchange pipe, and realizing more accurate automatic temperature control.

[0056] In addition, the inventors have designed the process to further improve the raw material conversion rate and product selectivity by controlling the feed flow rate of the vinyl sulfite solution and hydrogen peroxide and setting the temperature and other parameters. The vinyl sulfite conversion rate of the present invention can reach 99%, the selectivity of vinyl sulfate can reach 96%, and the utilization rate of hydrogen peroxide can reach 98%.

[0057] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0058] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available products, or can be prepared by referring to existing preparation methods.

[0059] Example 1

[0060] A fixed bed reactor, such as Figures 1 to 3 As shown, it includes a reaction module, a mixed emulsification preheating device 2, a temperature control module, a temperature measurement module and a control system 9.

[0061] The reaction module includes a shell 1, a cavity formed around the shell 1, and a partition 11 arranged in the cavity. The partition 11 is preferably cylindrical and extends in the up and down direction. The partition 11 separates the cavity into a temperature control chamber 12 and a reaction chamber 13. The reaction chamber 13 is located in the temperature control chamber 12 and is coaxial with the shell 1. The reaction chamber 13 is filled with a catalyst, and the catalyst is preferably a TS-1 titanium silicon molecular sieve. The top and bottom of the shell 1 are respectively provided with a feeding channel 14 and a discharge port 15 connected to the reaction chamber 13. After the reaction raw materials enter the reaction chamber 13 from the feeding channel 14 for reaction, they are discharged from the discharge port 15. A liquid inlet and a liquid outlet connected to the temperature control chamber 12 are provided on the side wall of the shell 1, and one or more liquid inlets and liquid outlets can be optionally provided. In this embodiment, there are two liquid inlets and two liquid outlets, namely: the temperature control chamber liquid inlet 16, the temperature control chamber liquid outlet 17, the heat exchange pipe liquid inlet 18 and the heat exchange pipe liquid outlet 19. The temperature control chamber liquid inlet 16 and the heat exchange pipe liquid inlet 18 are located on the lower side, and the temperature control chamber liquid outlet 17 and the temperature control chamber liquid outlet 17 are located on the upper side.

[0062] The mixed emulsification preheating device 2 is used to mix and heat the reaction raw materials. The feed end of the mixed emulsification preheating device 2 is connected to a plurality of feed pipes, each of which is provided with a valve and a feed pump (not shown in the figure). In the present embodiment, there are three feed pipes, namely, a first feed pipe 21, a second feed pipe 22, and a third feed pipe 23, and the first feed pipe 21, the second feed pipe 22, and the third feed pipe 23 are respectively provided with a first control valve 25, a second control valve 26, and a third control valve 27. The discharge end of the mixed emulsification preheating device 2 is connected to the feeding channel 14 through a pipe, and a control valve is provided on the pipe.

[0063] The temperature control module includes a heat exchange pipe 6 spirally wound along the outer wall of the reaction chamber 13, and a first heat exchanger 4 and a second heat exchanger 5 arranged on the outside of the shell 1 and controlled by the control system 9. The heat exchange pipe liquid inlet 18 and the heat exchange pipe liquid outlet 19 are respectively connected to the first heat exchanger 4 through pipes, and the liquid inlet and liquid outlet of the shell 1 are respectively connected to the second heat exchanger 5 through pipes, and valves are provided on the pipes. In this embodiment, the diameter of the heat exchange pipe 6 is 50mm, and the spacing between the adjacent upper and lower pipes is 2mm. Usually, the control system 9 controls the operating parameters of the first heat exchanger 4 and the second heat exchanger 5 so that the temperature of the heat exchange pipe 6 is not higher than the set temperature (i.e., the reaction temperature), while the temperature of the temperature control chamber 12 can be higher than the set temperature. Therefore, when the temperature of the reaction chamber 13 is too high, the heat exchange pipe 6 can be used to cool down, so that the temperature of the reaction chamber 13 is always maintained at the set temperature.

[0064] The temperature measurement module includes a plurality of temperature measurement components 7 arranged in the reaction chamber 13 along the height direction. The temperature measurement components 7 are used to collect temperature and can feed back the collected temperature to the control system 9 in real time. In this embodiment, there are 6 groups of temperature measurement components 7, and each group of temperature measurement components 7 also includes 12 thermocouples 71 and a collection device evenly arranged around the axis of the shell 1. The thermocouple 71 outputs an electrical signal to the collection device, and the collection device transmits the data to the control system 9 through the output wire. Of course, in some other embodiments, wireless communication can also be used for signal transmission.

[0065] The control system 9 controls the operating parameters of the first heat exchanger 4 and the second heat exchanger 5 (including the inlet flow rate, outlet flow rate, and temperature of the circulating liquid of the heat exchanger) according to the temperature feedback from the temperature measuring component 7, so that the difference between the temperature of each area of ​​the reaction chamber 13 and the set temperature is controlled within a preset range. For example, when the temperature in the reaction chamber 13 is lower than the set temperature, the inlet temperature and speed of the circulating liquid in the temperature control chamber 12 or the heat exchange pipe 6 can be selectively adjusted to increase the temperature of the reaction chamber 13; when the temperature in the reaction chamber 13 is higher than the set temperature, the inlet flow rate and temperature of the circulating liquid in the temperature control chamber 12 or the heat exchange pipe 6 can be adjusted to increase the temperature of the reaction chamber 13.

[0066] In this embodiment, the fixed bed reactor also includes an oil-water separation tank 8, the feed end of the oil-water separation tank 8 is connected to the discharge port 15 of the shell 1 through a discharge pipe, and a back pressure valve 10 is provided on the discharge pipe; the two discharge ends of the oil-water separation tank 8 are respectively connected to the waste liquid tank and the storage tank, the storage tank is used to collect the organic phase containing the product, and the waste liquid tank is used to collect the waste liquid.

[0067] A method for continuously preparing vinyl sulfate, comprising:

[0068] (a) Start the first heat exchanger 4 and the second heat exchanger 5, and introduce circulating fluid into the heat exchange pipe 6 and the temperature control chamber 12 respectively. The circulating fluid of the first heat exchanger 4 and the second heat exchanger 5 is a mixture of 30% ethanol and ultrapure water. The circulating fluid flow rate of the first heat exchanger 4 is 100 L / min, and the inlet temperature and outlet temperature are set to 70°C; the circulating fluid flow rate of the second heat exchanger 5 is 150 L / min, and the inlet temperature and outlet temperature are set to 70°C, so that the reaction chamber 13 is raised to the set temperature of 70°C. The control system 9 controls the operating parameters of the first heat exchanger 4 and the second heat exchanger 5 according to the temperature feedback from the temperature measuring component 7, so that the difference between the temperature of each area of ​​the reaction chamber 13 and the set temperature is controlled within ±0.5°C;

[0069] (b) vinyl sulfite and dimethyl carbonate are mixed to form a vinyl sulfite solution with a mass concentration of 35%, and the feed volume flow rates of the vinyl sulfite solution and hydrogen peroxide (40 wt%) are set to 100 mL / min and 31 mL / min respectively. After entering the mixed emulsification preheating device 2 and preheating to 60° C., they are continuously pumped into the reaction chamber 13 for reaction, wherein the molar ratio of vinyl sulfite to hydrogen peroxide is 1:1, and the residence time of the material in the reaction chamber 13 is 200 s. The control system 9 controls the deviation between the temperature of each area of ​​the reaction chamber 13 and the set temperature to be ±0.5° C., and the pressure is 0.25 MPa;

[0070] (c) After the reaction is completed, the reaction liquid is passed into the oil-water separation tank 8 for separation to obtain an organic phase containing the product and a waste liquid containing hydrogen peroxide.

[0071] Sampling and testing revealed that the conversion rate of vinyl sulfite was 99%, the selectivity to vinyl sulfate was 96%, and the utilization rate of hydrogen peroxide was 98%.

[0072] Conversion rate = (the amount of raw material in the feed - the amount of raw material after the reaction) / the amount of raw material in the feed × 100%;

[0073] Selectivity = amount of product substance / (amount of raw material substance in the feed - amount of raw material substance after reaction) × 100%;

[0074] Utilization rate = amount of product substance / (amount of feed hydrogen peroxide substance - amount of hydrogen peroxide substance after reaction) × 100%.

[0075] Example 2

[0076] The method is basically the same as Example 1, except that step (b) is as follows:

[0077] Ethylene sulfite and dimethyl carbonate are mixed to form an ethylene sulfite solution with a concentration of 35%. The feed volume flow rates of the ethylene sulfite solution and hydrogen peroxide (40 wt%) are set to 105 mL / min and 31 mL / min respectively. After entering the mixed emulsification preheating device 2 and preheating to 60° C., the mixture is continuously pumped into the reaction chamber 13 for reaction. The molar ratio of ethylene sulfite to hydrogen peroxide is 1.05:1. The residence time of the material in the reaction chamber 13 is 200 s. The control system 9 controls the deviation between the temperature of the reaction chamber 13 and the set temperature to be ±0.5° C., and the pressure to be 0.25 MPa.

[0078] Sampling and testing revealed that the conversion rate of vinyl sulfite was 92%, the selectivity to vinyl sulfate was 91%, and the utilization rate of hydrogen peroxide was 94%.

[0079] Example 3

[0080] The method is basically the same as Example 1, except that step (b) is as follows:

[0081] Ethylene sulfite and dimethyl carbonate are mixed to form an ethylene sulfite solution with a concentration of 45%. The feed volume flow rates of the ethylene sulfite solution and hydrogen peroxide (40 wt%) are set to 82 mL / min and 31 mL / min respectively. After entering the mixed emulsification preheating device 2 and preheating to 60° C., the mixture is continuously pumped into the reaction chamber 13 for reaction. The residence time of the material in the reaction chamber 13 is 200 s, the molar ratio of ethylene sulfite to hydrogen peroxide is 1.05:1, and the control system 9 controls the deviation between the temperature of the reaction chamber 13 and the set temperature to be ±0.5° C., and the pressure is 0.25 MPa.

[0082] After the reaction reaches stability, the reaction liquid enters the oil-water separation tank 8 to obtain an organic phase containing the product and a waste liquid containing hydrogen peroxide.

[0083] Sampling and testing revealed that the conversion rate of vinyl sulfite was 92%, the selectivity to vinyl sulfate was 89%, and the utilization rate of hydrogen peroxide was 95%.

[0084] Example 4

[0085] The method is basically the same as Example 1, except that step (b) is as follows:

[0086] Ethylene sulfite and dimethyl carbonate are mixed to form an ethylene sulfite solution with a concentration of 35%. The feed volume flow rates of the ethylene sulfite solution and hydrogen peroxide (45wt%) are set to 100mL / min and 27.6mL / min respectively. After entering the mixed emulsification preheating device 2 and preheating to 60°C, the mixture is continuously pumped into the reaction chamber 13 for reaction. The residence time of the material in the reaction chamber 13 is 200s, the molar ratio of ethylene sulfite to hydrogen peroxide is 1:1, and the control system 9 controls the deviation between the temperature of the reaction chamber 13 and the set temperature to be ±0.5°C, and the pressure is 0.25MPa.

[0087] Sampling and testing revealed that the conversion rate of vinyl sulfite was 97%, the selectivity to vinyl sulfate was 95%, and the utilization rate of hydrogen peroxide was 94%.

[0088] Example 5

[0089] The method is basically the same as Example 1, except that step (b) is as follows:

[0090] Ethylene sulfite and dimethyl carbonate are mixed to form an ethylene sulfite solution with a mass concentration of 35%. The feed volume flow rates of the ethylene sulfite solution and hydrogen peroxide (40 wt%) are set to 100 mL / min and 31 mL / min respectively. After entering the mixed emulsification preheating device 2 and preheating to 65° C., the materials are continuously pumped into the reaction chamber 13 for reaction. The residence time of the materials in the temperature control chamber 12 is 200 s, the molar ratio of ethylene sulfite to hydrogen peroxide is 1.:1, and the control system 9 controls the deviation between the temperature of the reaction chamber 13 and the set temperature to be ±0.5° C., and the pressure is 0.25 MPa.

[0091] Sampling and testing revealed that the conversion rate of vinyl sulfite was 97%, the selectivity to vinyl sulfate was 88%, and the utilization rate of hydrogen peroxide was 94%.

[0092] Example 6

[0093] The method is basically the same as Example 1, except that step (a) is as follows:

[0094] (a) Start the first heat exchanger 4 and the second heat exchanger 5, and introduce circulating fluid into the heat exchange pipe 6 and the temperature control chamber 12 respectively, so that the reaction chamber 13 is raised to the set temperature of 75°C. The control system 9 controls the operating parameters of the first heat exchanger 4 and the second heat exchanger 5 according to the temperature feedback from the temperature measuring component 7, so that the difference between the temperature of each area of ​​the reaction chamber 13 and the set temperature is controlled within ±0.5°C.

[0095] Sampling and testing revealed that the conversion rate of vinyl sulfite was 93%, the selectivity to vinyl sulfate was 87%, and the utilization rate of hydrogen peroxide was 82%.

[0096] Comparative Example 1

[0097] This comparative example is substantially the same as Example 1, except that the reaction materials react in a common fixed bed reactor (without a temperature control module).

[0098] The detection results show that the conversion rate of vinyl sulfite is 72%, the selectivity to vinyl sulfate is 74%, and the utilization rate of hydrogen peroxide is 65%.

[0099] The existing fixed bed reactor is used for the oxidation reaction of vinyl sulfite, but the conversion rate of vinyl sulfite, the utilization rate of hydrogen peroxide, and the product selectivity are not high. The inventors speculate that since the oxidation reaction of vinyl sulfite is a highly exothermic reaction, when a high concentration of vinyl sulfite solution is used, a large amount of heat will be released, causing the temperature of the reaction chamber 13 to rise, and eventually leading to side reactions, thereby affecting the conversion rate, selectivity and utilization rate.

[0100] Comparative Example 2

[0101] This comparative example is substantially the same as Example 1, except that in step (a) and step (b), the control system 9 controls the deviation between the temperature of the reaction chamber 13 and the set temperature to be ±1.5°C.

[0102] The detection results show that the conversion rate of vinyl sulfite is 88%, the selectivity to vinyl sulfate is 85%, and the utilization rate of hydrogen peroxide is 72%.

[0103] During the reaction, if the temperature of the reaction chamber 13 deviates greatly from the set temperature, it will also affect the conversion rate of vinyl sulfite, the utilization rate of hydrogen peroxide, and the selectivity of the product. Therefore, the reaction temperature of the reaction chamber 13 must be accurately controlled so that its fluctuation is not too large. The difference between the reaction chamber 13 and the set temperature is preferably within ±1°C, and the best is ±0.5°C.

[0104] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them. It does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for continuously preparing vinyl sulfate, using a fixed bed reactor to prepare the vinyl sulfate, characterized in that: The fixed bed reactor includes a reaction module, a temperature control module, a temperature measurement module and a control system. The reaction module comprises a shell, a cavity formed by the shell, and a partition arranged in the cavity, wherein the partition separates the cavity into a temperature control cavity and a reaction cavity located in the temperature control cavity, the top and bottom of the shell are respectively provided with a feeding channel and a discharge port connected to the reaction cavity, the side wall of the shell is provided with a liquid inlet and a liquid outlet connected to the temperature control cavity, and the reaction cavity is filled with a catalyst; The temperature control module comprises a heat exchange pipe spirally wound along the outer wall of the reaction chamber, and a first heat exchanger and a second heat exchanger arranged outside the shell and controlled by the control system, the liquid inlet and the liquid outlet of the heat exchange pipe are connected to the first heat exchanger, and the liquid inlet and the liquid outlet of the shell are connected to the second heat exchanger; The temperature measurement module includes a plurality of temperature measurement components arranged in the reaction chamber along the height direction, and the temperature measurement components are used to collect temperature and can feed back the collected temperature to the control system in real time. The method comprises the following steps: (1) starting the first heat exchanger and the second heat exchanger, and introducing circulating fluid into the heat exchange pipe and the temperature control chamber respectively, so that the reaction chamber is raised to a set temperature; (2) the reaction raw materials are introduced into the reaction chamber through the feeding channel for reaction, and the control system controls the operating parameters of the first heat exchanger and the second heat exchanger according to the temperature feedback from the temperature measuring component, so that the difference between the temperature of each area of ​​the reaction chamber and the set temperature is controlled within -1°C to 1°C, The reaction raw materials include ethylene sulfite and hydrogen peroxide.

2. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The vinyl sulfite is fed in the form of a vinyl sulfite solution, which includes vinyl sulfite and an organic solvent. The mass concentration of the vinyl sulfite in the vinyl sulfite solution is 30-55%.

3. The method for continuously preparing vinyl sulfate according to claim 2, characterized in that: The feed rate of the vinyl sulfite solution is controlled to be 80-150 mL / min.

4. The method for continuously preparing vinyl sulfate according to claim 2, characterized in that: The organic solvent is selected from one or more carbonate solvents.

5. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The mass concentration of the hydrogen peroxide is 40-50%; and / or, The feed rate of the hydrogen peroxide solution is controlled to be 20-45 mL / min.

6. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The set temperature is 55-75°C; and / or, The reaction pressure of the reaction chamber is 0.2-0.5 MPa; and / or, The residence time of the vinyl sulfite in the reaction chamber is 150 to 250 seconds.

7. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The method further comprises mixing the reaction raw materials and preheating them to 50-65° C. before introducing them into the feeding channel.

8. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The operating parameters include the inlet flow rate, outlet flow rate and circulating fluid temperature of the heat exchanger.

9. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The temperature of the heat exchange pipe is controlled not to be higher than the set temperature.

10. The method for continuously preparing vinyl sulfate according to claim 1, characterized in that: The temperature measuring assembly comprises a plurality of thermocouples arranged at intervals around the axis of the shell, and the thermocouples are connected to the control system; and / or, The diameter of the heat exchange pipe is 20 to 100 mm; and / or, The distance between two adjacent upper and lower heat exchange pipes is 1 to 10 mm.

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