Trifluoromethyl fluoroformate synthesis system and method

Abstract

The present invention provides a trifluoromethyl fluoroformate synthesis system and method. The trifluoromethyl fluoroformate synthesis system comprises a reaction unit, a heat exchange unit, a cold trap unit, a low-temperature rectification unit, and a recycling unit that are arranged in sequence. The reaction unit comprises a feed pipe, a discharge pipe, and a reactor. The discharge pipe is communicated with the cold trap unit by means of a third heat exchange tube, the cold trap unit is communicated with the low-temperature rectification unit, and the low-temperature rectification unit is communicated with the recycling unit. The heat exchange unit comprises a heat exchanger. The low-temperature rectification unit comprises a rectifying section and a stripping section. The recycling unit comprises a first circulating pipe and a second circulating pipe that are used for recycling a product from the rectifying section, wherein the first circulating pipe and the second circulating pipe are respectively communicated with the feed pipe by means of a second heat exchange tube and a first heat exchange tube, and the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube all pass through the heat exchanger. By recycling the product from the rectifying section, the present invention reduces the loss of raw materials, and improves the product yield.

Description

A system and method for synthesizing trifluoromethyl fluoroformate Technical Field

[0001] This invention relates to the fields of emission reduction and gas production, specifically to a reactive distillation coupled system and method for synthesizing trifluoromethyl fluoroformate. Background Technology

[0002] Trifluoromethyl fluoroformate CF3OCOF is an intermediate of perfluoromethoxymethyl vinyl ether (MOVE), a novel functional monomer used in the preparation of low-temperature resistant perfluoroether rubber.

[0003] CN 112778129 A discloses a method for preparing trifluoromethyl fluoroformate (CF3OCOF), comprising: using a fluorine-containing reagent as a solvent, and hexafluoropropylene and oxygen as reactants, reacting under ultraviolet light to generate trifluoromethyl fluoroformate. However, the above synthesis method requires a fluorine-containing reagent as a solvent and ultraviolet light.

[0004] In existing synthetic methods, trifluoromethyl hypofluoroester CF3OF and carbon monoxide CO are used to synthesize trifluoromethyl fluoroformate CF3OCOF via photodecomposition or pyrolysis free radical method, as follows:

[0005] Main side reactions:

[0006] In the photolysis or pyrolysis reaction of CF3OF and CO, the CF3OCO radical is formed by the combination of CF3O radical and CO. Since the cleavage of the OF bond requires high temperature or ultraviolet irradiation, the yield of the target product CF3OCOF is relatively low compared to the higher yield of byproducts such as COF2.

[0007] Regarding the recovery of the target product, the current method involves condensing the reaction mixture in a cold trap containing CFCl=CFCl(Al1112) at -110°C, allowing unreacted CF3OF to react with the CFCl=CFCl(Al1112) in the cold trap to generate CF3OCFClCF2Cl. The resulting mixture is then fractionated to obtain the target product CF3OCOF, as well as CF3OCFClCF2Cl and COF2. A drawback of this existing technique is the destruction of reaction intermediates, leading to a decrease in the overall yield.

[0008] Based on this, the present invention proposes a novel reactive distillation coupling system and method for synthesizing trifluoromethyl fluoroformate. Summary of the Invention

[0009] The purpose of this invention is to provide a system and method for synthesizing trifluoromethyl fluoroformate, so as to solve the problems existing in the prior art.

[0010] To address the aforementioned problems, a first aspect of the present invention provides a system for synthesizing trifluoromethyl fluoroformate, comprising a reaction unit, a heat exchange unit, a cold trap unit, a cryogenic distillation unit, and a recovery and recycling unit arranged sequentially. The reaction unit has a feed pipe and a discharge pipe; the discharge pipe is connected to the cold trap unit via a third heat exchange pipe; the cold trap unit is connected to the cryogenic distillation unit; and the cryogenic distillation unit is connected to the recovery and recycling unit. The reaction unit has a reactor connected to the feed pipe. The heat exchange unit has a multi-stream heat exchanger. The cryogenic distillation unit has a rectification section and a stripping section. The recovery and recycling unit has a first recycling pipe and a second recycling pipe for recycling the product from the rectification section. The first recycling pipe is connected to the feed pipe via a second heat exchange path, and the second recycling pipe is connected to the feed pipe via a first heat exchange pipe. The first heat exchange pipe, the second heat exchange pipe, and the third heat exchange pipe are all connected to the multi-stream heat exchanger.

[0011] In one embodiment, the reactor is a coil reactor, with an inner diameter of 40-200 mm for the disc and a tube length of 10-200 m.

[0012] In one embodiment, the reactor is made of stainless steel, polytetrafluoroethylene (PTFE), or lined with modified polytetrafluoroethylene (PFA).

[0013] In a second aspect, the present invention provides a method for synthesizing trifluoromethyl fluoroformate, comprising using the above-described system for synthesizing trifluoromethyl fluoroformate to prepare trifluoromethyl fluoroformate.

[0014] A third aspect of the present invention provides a method for synthesizing trifluoromethyl fluoroformate, comprising the following steps:

[0015] S1. Trifluoromethyl hypofluoroester CF3OF and carbon monoxide CO are reacted in a reactor to generate a reaction mixture including trifluoromethyl fluoroformate CF3OCOF.

[0016] S2. After heat exchange, the reaction mixture in step S1 is separated by cold trap and low-temperature distillation to obtain trifluoromethyl fluoroformate CF3OCOF.

[0017] S3. The fluorophosgene (COF2), raw material CF3OF, and CO in the separated reaction mixture are recovered or recycled after reheating.

[0018] In one embodiment, in step S1, the reactor is a coil reactor with an extended tube length, the tube length is set to 10-200m, the reaction temperature is 150-480℃, and the reaction pressure is 0.1-5 bar (G).

[0019] In one embodiment, in step S1, the CF3OF flow rate is 1-1000 L / h, preferably 10-500 L / h; the carbon monoxide (CO) flow rate is 1-1000 L / h, preferably 10-500 L / h.

[0020] In one embodiment, the flow rate ratio of CF3OF to CO is (0.2-1.5):1, preferably (0.5-1.2):1.

[0021] In one embodiment, in step S2, the temperature of the cold trap is below -100°C.

[0022] In one embodiment, in step S2, the reflux condensation temperature in the distillation column is controlled between -105 and -80°C; preferably, the reflux condensation temperature is controlled between -100 and -85°C; the feed is a saturated liquid feed with a feed temperature below -70°C, preferably below -80°C.

[0023] In one embodiment, a multi-flow heat exchanger is used for heat exchange in step S3.

[0024] In one embodiment, the tubular reactor is made of stainless steel, polytetrafluoroethylene (PTFE), or lined with modified polytetrafluoroethylene (PFA).

[0025] In one embodiment, the tail gas of the reactive distillation coupling system is treated using high-temperature thermal destruction, an alkaline absorption tower, and an adsorption tower.

[0026] In one embodiment, the reactive distillation coupling system includes: a tubular reactor; a heat exchanger connected to the tubular reactor; a cold trap connected to the heat exchanger; a cryogenic distillation system, a product collection device, and a raw material recovery and circulation system connected to the cold trap; and a PLC control system connected to a pressure sensor, a temperature sensor, a flow controller, and a GC-MS component analyzer.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] (1) Use a long coil reactor to improve the conversion rate of the target product;

[0029] (2) The reaction-coupled cryogenic distillation system reduces raw material loss and improves recovery rate by recycling raw materials and by-products;

[0030] (3) A multi-stream heat exchanger is installed between the high-temperature reaction and the cold trap and the low-temperature distillation system to recover heat and cold at the same time. In order to reduce energy consumption, the multi-stream heat exchanger is configured with streams with small temperature differences for heat exchange, or an internal baffle design is adopted to reduce the temperature difference between different heat exchange streams. Attached Figure Description

[0031] Figure 1 is a schematic flowchart of a reactive distillation coupling system and method for synthesizing trifluoromethyl fluoroformate according to an embodiment of the present invention. Detailed Implementation

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0033] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0035] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0036] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0037] As shown in Figure 1, this embodiment provides a reactive distillation coupling system for synthesizing trifluoromethyl fluoroformate, comprising:

[0038] The unit includes a reaction unit 10, a heat exchange unit 20, a cold trap unit 30, a cryogenic distillation unit 40, a recovery and circulation unit 50, a product collection unit 60, and a control unit.

[0039] The reaction unit 10 includes a feed pipe 11, a reactor 12, a constant temperature chamber 13, a first pipe 14, and a first discharge pipe.

[0040] Reactor 12 is a coil-type reactor with an inner diameter of 40-200 mm and a tube length of 10-200 m. Reactor 12 is placed in a high-temperature constant temperature chamber 13; the reaction temperature is 150-480℃, and the reaction pressure is 0.1-5 bar (G). Optionally, reactor 12 is made of stainless steel, polytetrafluoroethylene (PTFE), or lined with modified polytetrafluoroethylene (PFA).

[0041] In this embodiment, reactor 12 is a coil-type 316L stainless steel reactor, which is placed in a constant temperature chamber 13 at 180°C. The inner diameter of the disc of reactor 12 is 50 mm, and the tube length is 50 m.

[0042] The first pipe 14 is an intermediate feed pipe to improve the reaction rate. One end of it is connected to the feed pipe 11, and the other end is connected to the middle of the reactor 12.

[0043] The heat exchange unit 20 includes a heat exchanger 21 and a first heat exchange tube 22 (reheating), a second heat exchange tube 23 (reheating), a third heat exchange tube 24 (cooling), and a fourth heat exchange tube 25 (reheating) passing through the heat exchanger 21.

[0044] The multi-stream heat exchanger includes four streams: a high-temperature stream of reaction mixture flowing through the third heat exchange tube 24, a low-temperature stream of circulating gas flowing through the first heat exchange tube 22, a cold trap non-condensable gas and a low-temperature stream of top non-condensable gas flowing through the second heat exchange tube 23, and a low-temperature stream of bottom product flowing through the fourth heat exchange tube 25.

[0045] A multi-stream heat exchanger is used to cool the high-temperature reaction mixture, while simultaneously reheating and recycling the low-temperature non-condensable gas and the separated low-temperature unreacted components CF3OF and CO.

[0046] The recycling cycle has two meanings: first, it recovers some by-products by controlling the reflux ratio, such as recovering by-product COF2 as an intermediate product; second, the recovered raw materials enter the reaction cycle system as reactants.

[0047] The cold trap unit 30 includes a first condenser 31, liquid nitrogen and gas nitrogen inlet and outlet pipes 32, and a second outlet pipe 33.

[0048] The first condenser 31 is connected to the first discharge pipe through the third heat exchange tube 24.

[0049] The low-temperature distillation unit 40 includes a distillation section 41, a stripping section 42, a third discharge pipe 43, and a fourth discharge pipe 44.

[0050] The low-temperature distillation unit 40 is connected to the first condenser 31 through the second discharge pipe 33.

[0051] The recycling unit 50 (cold source) includes a gas-liquid separator 51, a second condenser 52, a first circulation pipe 53, a second circulation pipe 54, a first return pipe 55, and a second return pipe 56.

[0052] Product collection unit 60 (heat source) includes reboiler 61, reboiler tube 62, and fifth discharge tube 63.

[0053] The control unit includes a PLC control module, which is connected to a pressure sensor, a temperature sensor, a flow controller, and a GC-MS component analyzer.

[0054] Referring to Figure 1, the process flow is as follows:

[0055] The raw materials, including trifluoromethyl hypofluorite CF3OF, carbon monoxide CO, and unreacted raw materials and byproduct COF2 recovered after reheating, enter the coil reactor 12 through the feed pipe 11 in the direction of the arrow. To improve the reaction rate, some raw materials are fed through the first intermediate feed pipe 14 and enter the middle of the coil reactor 12 in the direction of the arrow.

[0056] The reaction mixture containing the target product trifluoromethyl fluoroformate enters the multi-stream heat exchanger 21 through the first discharge pipe and the third heat exchanger 24 for heat exchange. After the high-temperature reaction mixture in the third heat exchanger 24 is cooled, it enters the cold trap unit 30 in the direction of the arrow. The cooling capacity of the cold trap unit 30 comes from the cooling capacity released by the vaporization of liquid nitrogen through the liquid nitrogen and gas nitrogen inlet and outlet pipes 32. This further cools and condenses the reaction mixture after the multi-stream heat exchange, while removing the non-condensable gas, mainly CO, from the reaction mixture. These include condensates of CF3OF, CF3OCOF, and COF2, as well as a small amount of dissolved gases such as CO and N2, which enter the low-temperature distillation unit 40 through the second discharge pipe 33 in the direction of the arrow.

[0057] The cryogenic distillation unit 40 includes a rectification section 41 and a stripping section 42. The rectification section 41 discharges non-condensable gases, CF3OF, CO, and COF2 via the third discharge pipe 43 in the direction of the arrow. The stripping section 42 discharges the main target liquid product via the fourth discharge pipe 44 in the direction of the arrow. Part of this liquid is reheated via the fifth discharge pipe 63 and then via the multi-stream heat exchanger 21 to obtain the target product CF3OCOF (CAS No: 3299-24-9). The other part passes through the reboiler 61 and then through the reboiler pipe 62 in the direction of the arrow into the stripping section 42, thus realizing the cryogenic distillation operation.

[0058] The CF3OF, CO, and COF2 exiting from the rectification section 41 via the third discharge pipe 43 pass through the second condenser 52 and enter the gas-liquid separator 51 in the direction of the arrow. The CO and COF2 gases in the gas-liquid separator 51 pass through the first circulation pipe 53 in the direction of the arrow, then through the second heat exchange pipe 23, are reheated in the heat exchanger 21, and then re-enter the feed pipe 11 in the direction of the arrow. The liquid COF2 in the gas-liquid separator 51 mainly flows out through the first reflux pipe 55; a portion passes through the second reflux pipe 56 and re-enters the rectification section 41 in the direction of the arrow, while the other portion passes through the second circulation pipe 54 in the direction of the arrow, passes through the first heat exchange pipe 22, is reheated in the heat exchanger 21, and is either recovered as an intermediate product or enters the feed pipe 11 in the direction of the arrow.

[0059] The high-temperature reaction mixture in the third heat exchange tube 24 of heat exchanger 21 is cooled down, while the non-condensable gas in the second heat exchange tube 23, the non-condensable gas at the top of the tower, the low-temperature circulating stream in the first heat exchange tube 22, and the low-temperature product in the fourth heat exchange tube 25 are warmed up, recovered or circulated.

[0060] The reactive distillation coupling system for synthesizing trifluoromethyl fluoroformate is located in a closed space. All escaping gases must be treated by a tail gas treatment system before being discharged. The treatment process employs high-temperature thermal destruction, an alkaline absorption tower, and an adsorption tower to treat the tail gas from the reactive distillation coupling system. The tail gas thermal destruction temperature is 600-800℃; the alkaline solution is a 10% NaOH aqueous solution; a packed absorption tower is used, with the packing material being Pall rings of PTFE with a hydrophilic surface; the activated carbon filling the adsorption bed is impregnated with Na2CO3. The tail gas is discharged after passing through a high-temperature pyrolysis alkaline absorption tower and adsorption by the adsorbent.

[0061] The embodiments also provide a method for synthesizing trifluoromethyl fluoroformate, comprising the following steps:

[0062] S1. Trifluoromethyl hypofluoroester CF3OF and carbon monoxide CO are reacted in a reactor to generate a reaction mixture including trifluoromethyl fluoroformate CF3OCOF.

[0063] The tubular reactor is a coil reactor with an inner diameter of 40-200 mm and a tube length of 10-200 m. The reactor is placed in a high-temperature constant temperature chamber; the reaction temperature is 150-480℃, and the reaction pressure is 0.1-5 bar (G).

[0064] CF3OF and CO are synthesized into CF3OCOF via photodecomposition or pyrolysis of free radicals, as follows:

[0065] Main side reactions:

[0066] In the photodecomposition or pyrolysis reaction of CF3OF and CO, the CF3OCO radical is formed by the combination of CF3O radical and CO. Since the cleavage of the OF bond requires high temperature or ultraviolet irradiation, the yield of the target product CF3OCOF is relatively low (below 10%) compared to the higher yield of byproducts such as COF2, limiting the production and application of perfluoromethoxymethyl vinyl ether (MOVE).

[0067] The reaction mixture mainly contains the target product CF3OCOF, the byproduct COF2, unreacted components CF3OF and CO, and a small amount of nitrogen.

[0068] S2. After heat exchange, the reaction mixture in step S1 is separated by cold trap and low-temperature distillation to obtain the product trifluoromethyl fluoroformate CF3OCOF.

[0069] S3. The fluorophosgene (COF2), raw material CF3OF, and CO in the separated reaction mixture are recovered by reheating to obtain intermediate products or directly recycled.

[0070] Main component parameters of the reaction raw materials and reaction mixture:

[0071] As can be seen from the table above, the boiling points of the various components differ significantly. The target product CF3OCOF, the byproduct COF2, the unreacted component CF3OF, and CO can be separated, purified, and recycled through cold traps and cryogenic distillation.

[0072] The raw materials, including trifluoromethyl hypofluoride CF3OF, carbon monoxide CO, and unreacted raw materials and byproduct COF2 recovered after reheating, enter the coil reactor 12 through the feed pipe 11. To improve the reaction rate, some raw materials are fed through the first intermediate feed pipe 14.

[0073] The reaction mixture including the target product trifluoromethyl fluoroformate is connected to a multi-stream heat exchanger via a first discharge pipe and a third heat exchanger 24. This cools down the high-temperature reaction mixture in the third heat exchanger 24, while simultaneously warming up the non-condensable gas in the second heat exchanger 23, the non-condensable gas at the top of the column, the low-temperature circulating stream in the first heat exchanger 22, and the low-temperature product in the fourth heat exchanger 25 for recovery or recycling.

[0074] The cold trap unit 30 is connected to the multi-stream heat exchanger 21 via the third heat exchange tube 24. The cooling capacity of the cold trap unit 30 comes from the cooling capacity released by the vaporization of liquid nitrogen through the liquid nitrogen and gas nitrogen inlet and outlet pipes 32. This further cools and condenses the reaction mixture after it has been cooled by the multi-stream heat exchanger, while removing non-condensable gases from the reaction mixture. The condensate is transported to the low-temperature distillation unit 40 through the second outlet pipe 33. The liquid entering the low-temperature distillation unit 40 through the second outlet pipe 33 includes CF3OF, CF3OCOF, COF2, and a small amount of dissolved gases such as CO and N2.

[0075] The cryogenic distillation unit 40 includes a recovery circulation unit 50 (cold source) connected to a gas-liquid separator and a product collection unit 60 (heat source) connected to a reboiler 61. The third discharge pipe 43 carries non-condensable gas, and the fourth discharge pipe 44 carries mainly liquid target product. After reheating through heat exchanger 21, the product CF3OCOF is obtained. The product is refluxed through the first reflux pipe 55 and the second reflux pipe 56, and then reboiled through reboiler 62, thus realizing the cryogenic distillation process. The non-condensable gas, mainly containing carbon monoxide (CO) and small amounts of N2 and CF3OF, mixes with the non-condensable gas from the first circulation pipe 53 of the recovery circulation unit 50, which mainly contains CF3OF and CO, and then enters the multi-stream heat exchanger for reheating and recovery circulation.

[0076] Boiling point changes with external pressure; lower pressure results in a lower boiling point, and higher pressure results in a higher boiling point. Increasing pressure helps reduce cooling consumption and improves separation efficiency.

[0077] The nitrogen in the table is the purge gas. This is because, under certain humidity conditions, the target product CF3OCOF, due to the presence of carbonyl functional groups, may decompose, leading to new products such as HF, which could damage equipment and instruments. The feedstock and reaction mixture are transported under conditions of high-purity nitrogen purging at a dew point below -40°C.

[0078] Optionally, the flow rate of the trifluoromethyl hypofluorite CF3OF is 1-1000 L / h, preferably 10-500 L / h; the flow rate of the carbon monoxide CO is 1-1000 L / h, preferably 10-500 L / h.

[0079] Optionally, the flow rate ratio of CF3OF to CO is (0.2-1.5):1, preferably (0.5-1.2):1.

[0080] Optionally, the tubular reactor can be a coil type with an inner diameter of 40-200mm and a tube length of 10-200m.

[0081] Optionally, the tubular reactor is made of stainless steel, PTFE, or lined with modified polytetrafluoroethylene (PFA).

[0082] Optionally, the cold trap temperature is below -100°C.

[0083] Optionally, the temperature of the reflux condensation in the distillation column is controlled between -105 and -80°C, preferably between -100 and -85°C.

[0084] Optionally, the feed is a saturated liquid feed, and the feed temperature is below -70°C, preferably below -80°C.

[0085] Optionally, a multi-flow heat exchanger can be used.

[0086] A multi-stream heat exchanger includes at least a high-temperature reactive gas stream, a low-temperature non-condensable gas stream, a low-temperature byproduct COF2 stream, and low-temperature unreacted components CF3OF and CO streams. The multi-stream heat exchanger is used to cool the high-temperature reactive gas stream while simultaneously reheating and recycling the low-temperature byproduct COF2 and the low-temperature unreacted components CF3OF and CO streams.

[0087] Optionally, high-temperature thermal destruction, alkaline absorption towers, and adsorption towers can be used to treat the tail gas of the reactive distillation coupling system. Since the reactive distillation coupling system for synthesizing trifluoromethyl fluoroformate is located in a closed space, all escaping gases must be treated by the tail gas treatment system before being discharged.

[0088] The exhaust gas undergoes thermal destruction at a temperature of 600-800℃; the alkaline solution is a 10% NaOH aqueous solution; a packed absorber is used, with the packing material being Pall rings of PTFE with a hydrophilic surface; the activated carbon filling the adsorption bed is impregnated with Na2CO3. The exhaust gas is discharged after being adsorbed by the high-temperature pyrolysis alkaline absorber and adsorbent.

[0089] Optionally, the reactive distillation coupling system includes: a tubular reactor; a heat exchanger connected to the tubular reactor; a cold trap connected to the heat exchanger; a cryogenic distillation system, a product collection device, and a raw material recovery and circulation system connected to the cold trap; and a PLC control system connected to a pressure sensor, a temperature sensor, a flow controller, and a GC-MS component analyzer.

[0090] Example 1: A reactor with a tube length of 50m was used, but the reaction mixture and byproducts were not recovered and were not recycled.

[0091] A coiled 316L stainless steel reactor with an inner diameter of 50mm and a tube length of 50m was placed in a constant temperature chamber at 180℃. After purging the reactor with high-purity nitrogen gas with a dew point temperature below -60℃, the feed gases trifluoromethyl hypofluorite (CF3OF) and carbon monoxide (CO) were introduced in a certain proportion. The reactor pressure was 0.5 bar (G), the CF3OF flow rate was 10 L / h, and the CO flow rate was 20 L / h.

[0092] The concentration of each component in the outlet gas mixture when the reaction reaches stability was analyzed online by a gas chromatograph-mass spectrometer (GC-MS) (Agilent 5977B).

[0093] Table 1 Main components of the gas mixture in Example 1

[0094] Based on the data in Table 1, the conversion rate can be calculated. yield and selectivity The percentages are 54.8%, 44.7%, and 81.6%, respectively. The specific calculations are shown in the following formulas:

[0095] Conversion rate of CF3OF for

[0096] Yield of CF3OCOF for

[0097] Selectivity of CF3OCOF for

[0098] The cold trap uses liquid nitrogen as a cold source, and the temperature of the cold trap is -100℃. The non-condensable gas contains most of CO, trace amounts of N2 and CF3OF, and the remainder is dissolved in the mixture before entering the cryogenic distillation column.

[0099] The feed to the cryogenic distillation column is liquid, with a feed temperature of approximately -90°C; the bottom temperature is -45°C; and the reflux condensation temperature is -90°C.

[0100] Unreacted feed mixtures and byproducts are recovered using cold traps or cryogenic distillation, but are not recycled.

[0101] The multi-stream heat exchanger has four streams: a high-temperature stream of reactant gas mixture, a low-temperature stream of cold trap non-condensable gas, a low-temperature stream of overhead non-condensable gas, a low-temperature stream of overhead reflux recovery components, and a low-temperature stream of bottom product. The multi-stream heat exchanger cools the high-temperature stream of reactant gas mixture while simultaneously reheating and recycling the low-temperature stream of non-condensable gas, unreacted components CF3OF, and CO.

[0102] The tail gas from the reactive distillation coupling system is treated using high-temperature thermal destruction, an alkaline absorption tower, and an adsorption tower. The reactive distillation coupling system for synthesizing trifluoromethyl fluoroformate is located in a closed space; all escaping gases must be treated by the tail gas treatment system before being discharged.

[0103] The exhaust gas undergoes thermal destruction at a temperature of 700℃; the alkaline solution is a 10% NaOH aqueous solution; a packed absorber is used, with the packing material being Pall rings of PTFE with a hydrophilic surface; the activated carbon filling the adsorption bed is impregnated with Na2CO3. The exhaust gas is discharged after being adsorbed by the high-temperature pyrolysis alkaline absorber and adsorbent.

[0104] Example 2: Recovery and recycling of unreacted reaction mixtures and byproducts in a 50m long reactor.

[0105] The operation is the same as in Example 1, except that the unreacted reaction mixture and byproducts are recovered and recycled.

[0106] Table 2 Main components of the gas mixture and recycle products in Example 2

[0107] Based on the data in Table 2, the conversion rate can be calculated. yield and selectivity The percentages were 73.7%, 82.3%, and 81.4%, respectively.

[0108] Set the reflux ratio to 1.

[0109] Table 3. Cyclic Process of Example 2

[0110] Comparative Example 1: A 10m long reactor was used, but the reaction mixture and byproducts were not recovered or recycled.

[0111] The operation was the same as in Example 1, except that a coiled 316L stainless steel reactor with a tube length of 10m was used.

[0112] Table 4 Main Components of the Outlet Mixture and Recovered Products in Comparative Example 1

[0113] Based on the data in Table 4, the conversion rate can be calculated. yield and selectivity The percentages were 18.6%, 8.4%, and 45.2%, respectively.

[0114] Comparative Example 2: 10m long reactor, recovery and recycling of unreacted reaction mixture and byproducts.

[0115] The operation was the same as in Example 2, except that a coiled 316L stainless steel reactor with a tube length of 10m was used.

[0116] Table 5 Main components of the gas mixture and cycle products in Comparative Example 2

[0117] Based on the data in Table 5, the conversion rate can be calculated. yield and selectivity The percentages were 28.9%, 16.2%, and 56.8%, respectively.

[0118] As can be seen from the above embodiments and comparative examples:

[0119] In Example 1, with a tube length of 50m, the conversion rate of CF3OF was investigated. The yield of CF3OCOF was 54.8%. It is 44.7%.

[0120] In Comparative Example 1, with a tube length of 10m, the conversion rate is... The yield was 18.6%. It is 8.4%.

[0121] In Example 2, with a tube length of 50m, the conversion rate of CF3OF was investigated. The yield of CF3OCOF was 73.7%. It is 82.3%.

[0122] In Comparative Example 2, with a tube length of 10m, the conversion rate... The yield was 28.9%. It is 16.2%.

[0123] The reactive distillation coupled system and method for synthesizing trifluoromethyl fluoroformate provided in this embodiment significantly improves the conversion rate of raw materials and the yield of target products compared with Comparative Examples 1 and 2, respectively, through Examples 1 and 2.

[0124] Reactions (1) and (2) are reversible reactions with high activation energies. Before reaching equilibrium, the reaction is under kinetic control. It can be seen that increasing the length of the coil reactor, i.e. the residence time of the raw materials, can significantly improve the conversion rate of the raw materials and the yield of the target product.

[0125] Furthermore, compared to Example 1, the conversion rate of CF3OF in Example 2 was [higher / lower / etc.]. The yield of CF3OCOF increased from 54.8% in Example 1 to 73.7%. The percentage increased from 44.7% in Example 1 to 82.3%.

[0126] Compared with Comparative Example 1, the conversion rate of CF3OF in Comparative Example 2 was... The yield of CF3OCOF increased from 18.6% in Comparative Example 1 to 28.9%. The percentage increased from 8.4% in Comparative Example 1 to 16.2%.

[0127] It is evident that material recycling can significantly improve the conversion rate of raw materials and the yield of target products, with the yield of target products increasing to more than 180% of that in the case of no material recycling. This also indicates that the addition of byproduct COF2 can inhibit the reaction to a certain extent (2).

[0128] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for synthesizing trifluoromethyl fluoroformate, characterized in that, This method employs a system for synthesizing trifluoromethyl fluoroformate, the system comprising a reaction unit, a heat exchange unit, a cold trap unit, a cryogenic distillation unit, and a recovery and recycling unit arranged sequentially. The reaction unit has a feed pipe and a discharge pipe; the discharge pipe is connected to the cold trap unit via a third heat exchange pipe; the cold trap unit is connected to the cryogenic distillation unit; and the cryogenic distillation unit is connected to the recovery and recycling unit. The reaction unit has a reactor connected to the feed pipe. The heat exchange unit has a multi-stream heat exchanger. The cryogenic distillation unit has a rectification section and a stripping section. The recovery and recycling unit has a first recycling pipe and a second recycling pipe for recycling the product from the rectification section. The first recycling pipe is connected to the feed pipe via a second heat exchange pipe, and the second recycling pipe is connected to the feed pipe via a first heat exchange pipe. The first, second, and third heat exchange pipes are all connected to the multi-stream heat exchanger. The method includes the following steps: S1. A reaction mixture including trifluoromethyl fluoroester is generated by reacting trifluoromethyl fluoroester and carbon monoxide in a reactor. S2. After heat exchange, the reaction mixture in step S1 is separated by cold trap and low-temperature distillation to obtain trifluoromethyl fluoroformate. S3. The fluorophosgene, raw material trifluoromethyl hypofluoroester and carbon monoxide in the separated reaction mixture are recovered or recycled after reheating. In step S1, the flow rate of the trifluoromethyl hypofluoroester is 1-1000 L / h; In step S2, the temperature of the cold trap is below -100°C; the temperature of the reflux condensation in the distillation column is controlled between -105°C and -80°C; the feed is a saturated liquid feed with a feed temperature below -70°C.

2. The method for synthesizing trifluoromethyl fluoroformate according to claim 1, characterized in that, In step S1, the reactor is a coil reactor with an extended tube length, set to 10-200m, the reaction temperature is 150-480℃, and the reaction pressure is 0.1-5bar(G).

3. The method for synthesizing trifluoromethyl fluoroformate according to claim 1, characterized in that, The flow rate ratio of the trifluoromethyl hypofluoroester to the carbon monoxide is (0.2-1.5):

1.

4. The method for synthesizing trifluoromethyl fluoroformate according to claim 2, characterized in that, The inner diameter of the reactor disc is 40-200 mm.

5. The method for synthesizing trifluoromethyl fluoroformate according to claim 2, characterized in that, The reactor is made of stainless steel, polytetrafluoroethylene (PTFE), or a modified PTFE lining.

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