A system and method for synthesizing trifluoromethyl fluoroformate

Abstract

The present invention provides a system and method for synthesizing trifluoromethyl fluoroformate, the system for synthesizing trifluoromethyl fluoroformate comprises a reaction unit, a heat exchange unit, a cold trap unit, a cryogenic distillation unit and a recovery and circulation unit which are sequentially set up; the reaction unit has a feed pipe, a discharge pipe and a reactor, the discharge pipe is connected to the cold trap unit through 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 circulation unit; the heat exchange unit has a heat exchanger; the cryogenic distillation unit has a distillation section and a stripping section, the recovery and circulation unit has a first circulation pipe and a second circulation pipe for recycling the product from the distillation section, the first circulation pipe and the second circulation pipe are respectively connected to the feed pipe through the second heat exchange pipe and the first heat exchange pipe, and the first heat exchange pipe, the second heat exchange pipe and the third heat exchange pipe are all passed through the heat exchanger. The present invention reduces the loss of raw materials and improves the product yield by recycling the product from the distillation section.

Description

Technical Field

[0001] The invention relates to the field of emission reduction and gas production, and in particular to a reaction distillation coupling system and method for synthesizing trifluoromethyl fluoroformate. Background Art

[0002] Trifluoromethyl fluoroformate CF3OCOF is an intermediate of a new functional monomer perfluoromethoxymethyl vinyl ether MOVE for preparing 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, hexafluoropropylene and oxygen as reaction materials, and 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 the existing synthesis method, trifluoromethyl hypofluorite CF3OF and carbon monoxide CO are used to synthesize trifluoromethyl fluoroformate CF3OCOF by photolysis or thermal decomposition free radical method, and the reaction is as follows:

[0005] (1)

[0006] Main side effects:

[0007] (2)

[0008] In the photolysis or pyrolysis reaction of CF3OF and CO, CF3OCO radicals are formed by the combination of CF3O radicals 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 byproduct target product CF2 with higher yield.

[0009] As for the recovery of the target product, the reaction mixture is currently condensed in a cold trap containing CFCl=CFCl (A1112) at -110 °C, so that the unreacted CF3OF reacts with CFCl=CFCl (A1112) in the cold trap to generate CF3OCFClCF2Cl. After fractionation of the obtained mixture, the target product CF3OCOF, CF3OCFClCF2Cl and COF2 are obtained. The disadvantage of the prior art is that the reaction intermediates are destroyed, which reduces the overall yield.

[0010] Based on this, the present invention proposes a novel reaction distillation coupling system and method for synthesizing trifluoromethyl fluoroformate. Summary of the invention

[0011] The purpose of the present invention is to provide a system and method for synthesizing trifluoromethyl fluoroformate to solve the problems existing in the above-mentioned prior art.

[0012] In order to solve the above problems, the 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 circulation unit which are sequentially set up; the reaction unit has a feed pipe and a discharge pipe, the discharge pipe is connected to the cold trap unit through a third heat exchange pipeline, the cold trap unit is connected to the cryogenic distillation unit, and the cryogenic distillation unit is connected to the recovery circulation unit; wherein 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 distillation section and a stripping section, the recovery circulation unit has a first circulation pipe and a second circulation pipe for recycling the product from the distillation section, the first circulation pipe is connected to the feed pipe through a second heat exchange path, the second circulation pipe is connected to the feed pipe through a first heat exchange pipe, and the first heat exchange pipe, the second heat exchange pipe and the third heat exchange pipe all pass through the multi-stream heat exchanger.

[0013] In one embodiment, the reactor is a coil reactor, the inner diameter of the disc is 40-200 mm, and the tube length is 10-200 m.

[0014] In one embodiment, the reactor is made of stainless steel or polytetrafluoroethylene (PTFE) or lined with modified polytetrafluoroethylene (PFA).

[0015] The second aspect of the present invention provides a method for synthesizing trifluoromethyl fluoroformate, comprising using the above-mentioned system for synthesizing trifluoromethyl fluoroformate to prepare trifluoromethyl fluoroformate.

[0016] The third aspect of the present invention provides a method for synthesizing trifluoromethyl fluoroformate, comprising the following steps:

[0017] S1, in a reactor, using trifluoromethyl hypofluorite CF3OF and carbon monoxide CO to react to generate a reaction mixture including trifluoromethyl fluoroformate CF3OCOF;

[0018] S2, exchanging heat with the reaction mixture in step S1, separating it by cold trap and cryogenic distillation to obtain trifluoromethyl fluoroformate CF3OCOF;

[0019] S3. Reheat the fluorophosgene COF2, raw material CF3OF and CO in the reaction mixture after separation and recover or circulate them.

[0020] In one embodiment, in step S1, the reactor is a coil reactor and the length of the tube is extended, the tube length is set to 10-200 m, the reaction temperature is 150-480 °C, and the reaction pressure is 0.1-5 bar (G).

[0021] 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.

[0022] In one embodiment, the flow ratio of the CF3OF to the CO is (0.2-1.5):1, preferably, (0.5-1.2):1.

[0023] In one embodiment, in step S2, the temperature of the cold trap is lower than -100°C.

[0024] In one embodiment, in step S2, the temperature of the reflux condensation in the distillation tower is controlled between -105 and -80°C; preferably, the temperature of the reflux condensation is controlled between -100 and -85°C; the feed is a saturated liquid feed, and the feed temperature is lower than -70°C, preferably lower than -80°C.

[0025] In one embodiment, a multi-stream heat exchanger is used for heat exchange in step S3.

[0026] In one embodiment, the tubular reactor is made of stainless steel or polytetrafluoroethylene (PTFE) or lined with modified polytetrafluoroethylene (PFA).

[0027] In one embodiment, high temperature thermal destruction, alkaline absorption tower and adsorption tower are used to treat the tail gas of the reaction distillation coupling system.

[0028] In one embodiment, the reaction-distillation coupling system comprises: 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 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 component analyzer GC-MS.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] (1) Using a long coil reactor to improve the conversion rate of the target product;

[0031] (2) The reaction-coupled cryogenic distillation system uses raw materials and by-products to recycle, reducing raw material losses and improving recovery rates;

[0032] (3) A multi-stream heat exchanger is installed between the high-temperature reaction system and the cold trap and low-temperature distillation system to recover both heat and cold. To reduce energy consumption, heat is exchanged between streams with small temperature differences in the multi-stream heat exchanger, or an internal deflection design is used to reduce the temperature difference between different heat exchange streams. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a schematic flow diagram of a reaction distillation coupling system and method for synthesizing trifluoromethyl fluoroformate in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0035] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0036] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an 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 aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0037] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0038] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0039] like Figure 1 As shown, this embodiment provides a reaction distillation coupling system for synthesizing trifluoromethyl fluoroformate, comprising:

[0040] 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.

[0041] The reaction unit 10 includes a feed pipe 11 , a reactor 12 , a thermostat 13 , a first pipe 14 , and a first discharge pipe.

[0042] The reactor 12 is a coil reactor with a disc inner diameter of 40-200 mm and a tube length of 10-200 m. The reactor 12 is placed in a high temperature constant temperature box 13; the reaction temperature is 150-480 ° C, and the reaction pressure is 0.1-5 bar (G). Optionally, the reactor 12 is made of stainless steel or polytetrafluoroethylene PTFE or lined with modified polytetrafluoroethylene PFA.

[0043] In the embodiment, the reactor 12 is a coil-type 316L stainless steel reactor, which is placed in a constant temperature box 13 at 180° C. The inner diameter of the reactor 12 disc is 50 mm and the tube length is 50 m.

[0044] The first tube 14 is an intermediate feed tube for increasing the reaction rate, one end of which is connected to the feed tube 11 , and the other end of which is connected to the middle of the reactor 12 .

[0045] 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 .

[0046] The multi-stream heat exchanger includes four streams: the high-temperature stream reaction mixed gas flowing through the third heat exchange tube 24, the low-temperature stream circulating stream flowing through the first heat exchange tube 22, the cold trap non-condensable gas and the low-temperature stream tower top non-condensable gas flowing through the second heat exchange tube 23, and the low-temperature stream tower bottom product flowing through the fourth heat exchange tube 25.

[0047] A multi-stream heat exchanger is used to cool the high-temperature stream reaction mixed gas, while the low-temperature stream non-condensable gas and the separated low-temperature stream unreacted components CF3OF and CO are reheated and recycled.

[0048] The recovery cycle has two meanings. One is to recover part of the by-products by controlling the reflux ratio, such as recovering the by-product COF2 as an intermediate product. The other is that the recovered raw materials enter the reaction cycle system as reactants.

[0049] The cold trap unit 30 includes a first condenser 31 , liquid nitrogen and gaseous nitrogen inlet and outlet pipes 32 , and a second outlet pipe 33 .

[0050] The first condenser 31 is connected to the first discharge pipe through the third heat exchange pipe 24 .

[0051] The cryogenic distillation unit 40 includes a distillation section 41 , a stripping section 42 , a third discharge pipe 43 , and a fourth discharge pipe 44 .

[0052] The cryogenic distillation unit 40 is connected to the first condenser 31 via the second discharge pipe 33 .

[0053] The recovery circulation 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 reflux pipe 55 , and a second reflux pipe 56 .

[0054] The product collecting unit 60 (heat source) includes a reboiler 61 , a reboiler pipe 62 , and a fifth discharge pipe 63 .

[0055] The control unit comprises a PLC control module, and the PLC control module is respectively connected to a pressure sensor, a temperature sensor, a flow controller and a component analyzer GC-MS.

[0056] Reference Figure 1 , the process flow is as follows:

[0057] The raw materials including trifluoromethyl hypofluorite CF3OF and carbon monoxide CO and the unreacted raw materials and by-product COF2 recovered after reheating enter the coil reactor 12 from the feed pipe 11 along the direction of the arrow. In order to increase the reaction rate, part of the raw materials are fed through the first pipe 14 of the intermediate feed pipe and enter the middle part of the coil reactor 12 along the direction of the arrow.

[0058] The reaction mixture including the target product trifluoromethyl fluoroformate enters the multi-stream heat exchanger 21 for heat exchange through the first discharge pipe through the third heat exchange pipe 24. The high-temperature stream reaction mixed gas in the third heat exchange pipe 24 is cooled and enters the cold trap unit 30 along the direction of the arrow. The cold energy of the cold trap unit 30 comes from the cold energy released by the gasification of liquid nitrogen through the liquid nitrogen and gas nitrogen inlet and outlet pipes 32, so that the reaction mixture after multi-stream heat exchange and cooling is further cooled and condensed, while the non-condensable gas mainly CO in the reaction mixture is removed. These condensates including CF3OF, CF3OCOF, COF2 and a small amount of dissolved gases such as CO and N2 enter the low-temperature distillation unit 40 along the direction of the arrow through the second discharge pipe 33.

[0059] The cryogenic distillation unit 40 includes a distillation section 41 and a stripping section 42. The non-condensable gas and CF3OF, CO, and COF2 are discharged from the distillation section 41 through the third discharge pipe 43 in the direction of the arrow, and the liquid main target product is discharged from the stripping section 42 through the fourth discharge pipe 44 in the direction of the arrow. A part of the target product CF3OCOF (CAS No: 3299-24-9) is obtained after being reheated in the multi-stream heat exchanger 21 through the fifth discharge pipe 63, and the other part passes through the reboiler 61 and enters the stripping section 42 through the reboiler pipe 62 in the direction of the arrow to realize the cryogenic distillation operation process.

[0060] CF3OF, CO, and COF2 from the rectifying section 41 through the third discharge pipe 43 pass through the second condenser 52 in the direction of the arrow and enter the gas-liquid separator 51. Among them, the gas CO and COF2 in the gas-liquid separator 51 pass through the first circulation pipe 53 in the direction of the arrow and through the second heat exchange pipe 23 and enter the feed pipe 11 again in the direction of the arrow after being reheated in the heat exchanger 21. The liquid COF2 in the gas-liquid separator 51 mainly flows out through the first reflux pipe 55, a part of it enters the rectifying section 41 again in the direction of the arrow through the second reflux pipe 56, and the other part passes through the second circulation pipe 54 in the direction of the arrow, and is recovered as an intermediate product after being reheated in the heat exchanger 21 through the first heat exchange pipe 22 or enters the feed pipe 11 in the direction of the arrow.

[0061] The high-temperature reaction mixed gas in the third heat exchange tube 24 in the heat exchanger 21 is cooled, while the non-condensable gas in the second heat exchange tube 23 of the low-temperature stream and the non-condensable gas at the top of the low-temperature stream, 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 reheated, recovered or circulated.

[0062] The reaction distillation coupling system for synthesizing trifluoromethyl fluoroformate is set in a confined space. All escaping gases must be treated by the tail gas treatment system before being discharged. The treatment process uses high-temperature thermal destruction, alkaline absorption tower and adsorption tower to treat the tail gas of the reaction distillation coupling system. The temperature of the tail gas thermal destruction is 600-800 ℃; the alkali solution is a 10% NaOH aqueous solution, and a packed absorption tower is used. The packing is a ball ring of PTFE with hydrophilic surface modification; the activated carbon filled in the adsorption bed is impregnated with Na2CO3. The tail gas is discharged after being adsorbed by a high-temperature cracking alkaline absorption tower and adsorbent.

[0063] The embodiment also provides a method for synthesizing trifluoromethyl fluoroformate, comprising the following steps:

[0064] S1, in a reactor, using trifluoromethyl hypofluorite CF3OF and carbon monoxide CO to react to generate a reaction mixture including trifluoromethyl fluoroformate CF3OCOF;

[0065] The tubular reactor adopts 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 box; the reaction temperature is 150-480 ° C, and the reaction pressure is 0.1-5 bar (G).

[0066] CF3OF and CO are synthesized from CF3OCOF by photolysis or thermal decomposition free radical method, the reaction is as follows:

[0067] (1)

[0068] Main side effects:

[0069] (2)

[0070] In the photolysis or pyrolysis reaction of CF3OF and CO, CF3OCO radicals are formed by the combination of CF3O radicals 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, less than 10%, compared with the byproducts such as COF2 with higher yields, which limits the production and application of perfluoromethoxymethyl vinyl ether MOVE.

[0071] The reaction mixture mainly contains the target product CF3OCOF, the by-product COF2, the unreacted components CF3OF and CO and a small amount of nitrogen.

[0072] S2, exchanging heat with the reaction mixture in step S1, and separating it by cold trap and cryogenic distillation to obtain the product trifluoromethyl fluoroformate CF3OCOF;

[0073] S3. Reheat the fluorophosgene COF2, raw material CF3OF and CO in the reaction mixture after separation and recover them to obtain intermediate products or directly circulate them.

[0074] Main component parameters of reaction raw materials and reaction mixture:

[0075]

[0076] As can be seen from the above table, the boiling points of the components are quite different. The target product CF3OCOF, by-product COF2, unreacted component CF3OF and CO can be separated, purified and recycled through cold trap and cryogenic distillation.

[0077] The raw materials including trifluoromethyl hypofluorite CF3OF, carbon monoxide CO, unreacted raw materials recovered after reheating, and by-product COF2 enter the coil reactor 12 through the feed pipe 11. In order to increase the reaction rate, part of the raw materials are fed through the first pipe 14 of the intermediate feed pipe.

[0078] The reaction mixture including the target product trifluoromethyl fluoroformate is connected to the multi-stream heat exchanger through the first discharge pipe and the third heat exchange pipe 24, so that the high-temperature stream reaction mixed gas in the third heat exchange pipe 24 is cooled, and at the same time, the non-condensable gas in the second heat exchange pipe 23 of the low-temperature stream and the non-condensable gas at the top of the low-temperature stream, the circulating stream of the low-temperature stream in the first heat exchange pipe 22, and the low-temperature product in the fourth heat exchange pipe 25 are restored to temperature, recovered or circulated;

[0079] The cold trap unit 30 is connected to the multi-stream heat exchanger 21 through the third heat exchange pipe 24. The cold energy of the cold trap unit 30 comes from the cold energy released by the gasification of liquid nitrogen through the liquid nitrogen and gas nitrogen inlet and outlet pipes 32, so that the reaction mixture after cooling by multi-stream heat exchange is further cooled and condensed while removing the non-condensable gas in the reaction mixture. The condensate is transported to the cryogenic distillation unit 40 through the second discharge pipe 33; the liquid entering the cryogenic distillation unit 40 through the second discharge pipe 33 includes CF3OF, CF3OCOF, COF2 and a small amount of dissolved gases such as CO and N2.

[0080] 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, wherein the third discharge pipe 43 is non-condensable gas and the fourth discharge pipe 44 is mainly liquid. The target product is reheated through the heat exchanger 21 to obtain the product CF3OCOF, which is refluxed through the first reflux pipe 55 and the second reflux pipe 56 and reboiled through the reboiler pipe 62 to realize the cryogenic distillation operation process. The non-condensable gas mainly containing carbon monoxide CO and a small amount of N2 and CF3OF is mixed with the non-condensable gas of the first circulation pipe 53 mainly containing CF3OF and CO from the recovery circulation unit 50 and enters the multi-stream heat exchanger reheat recovery cycle.

[0081] The boiling point changes with the external pressure. The lower the pressure, the lower the boiling point, and the higher the pressure, the higher the boiling point. Increasing the pressure is conducive to reducing the consumption of cold and improving the separation efficiency.

[0082] The nitrogen in the table is the purge gas. Because under a certain humidity, the target product CF3OCOF may decompose to produce some new products such as HF due to the presence of carbonyl functional groups, which may damage equipment and instruments. The transportation of raw materials and reaction mixtures is carried out in an environment with a dew point temperature of less than -40 ℃ under high-purity nitrogen purge.

[0083] Optionally, the flow rate of trifluoromethyl hypofluorite CF3OF is 1-1000 L / h, preferably 10-500 L / h; the flow rate of carbon monoxide CO is 1-1000 L / h, preferably 10-500 L / h.

[0084] Optionally, the flow ratio of the CF3OF to the CO is (0.2-1.5):1, preferably (0.5-1.2):1.

[0085] Optionally, the tubular reactor is of coil type with an inner diameter of 40-200 mm and a tube length of 10-200 m.

[0086] Optionally, the tubular reactor is made of stainless steel or PTFE or lined with modified polytetrafluoroethylene PFA.

[0087] Optionally, the cold trap temperature is lower than -100 °C.

[0088] Optionally, the reflux condensation temperature of the distillation tower is controlled between -105 and -80°C, preferably between -100 and -85°C.

[0089] Optionally, the feed is a saturated liquid feed, and the feed temperature is lower than -70°C, preferably lower than -80°C.

[0090] Optionally, the heat exchanger is a multi-stream heat exchanger.

[0091] The multi-stream heat exchanger includes at least a high-temperature stream reaction mixed gas, a low-temperature stream non-condensable gas and a low-temperature stream byproduct COF2, and a low-temperature stream unreacted component CF3OF and CO. The multi-stream heat exchanger is used to cool the high-temperature stream reaction mixed gas, and at the same time, the low-temperature stream byproduct COF2, and the low-temperature stream unreacted component CF3OF and CO are recovered and recycled.

[0092] Optionally, high temperature thermal destruction, alkaline absorption tower and adsorption tower are used to treat the tail gas of the reaction distillation coupling system. The reaction distillation coupling system for synthesizing trifluoromethyl fluoroformate is in a closed space, and all escaping gases must be treated by the tail gas treatment system before being discharged.

[0093] The temperature of thermal destruction of tail gas is 600-800℃; the alkali solution is 10% NaOH aqueous solution, and a packed absorption tower is used. The packing is a ball ring of PTFE with hydrophilic surface modification; the activated carbon filled in the adsorption bed is impregnated with Na2CO3. The tail gas is discharged after high temperature cracking alkaline absorption tower and adsorption by adsorbent.

[0094] Optionally, the reaction distillation coupling system includes: a tubular reactor; a heat exchanger connected to the tubular reactor; a cold trap connected to the heat exchanger; a low-temperature distillation system, a product collection device and a raw material recovery 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 component analyzer GC-MS.

[0095] Example 1: Reactor with a length of 50 m, unreacted solution and by-products recovered but not recycled

[0096] A coil-type 316L stainless steel reactor with an inner diameter of 50 mm and a tube length of 50 m was placed in a constant temperature box at 180 °C. After the reactor was purged with high-purity nitrogen with a dew point temperature below -60 °C, the raw gas 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.

[0097] The outlet of the tubular reactor was analyzed online by gas chromatography-mass spectrometer GC-MS (Agilent 5977B) to measure the concentration of each component in the outlet mixed gas when the reaction reached stability.

[0098] Table 1 Main composition of the mixed gas in Example 1

[0099]

[0100] According to the data in Table 1, the conversion rate can be calculated , yield and selectivity They are 54.8%, 44.7% and 81.6% respectively. The specific calculation is shown in the following formula:

[0101] Conversion rate of CF3OF for ;

[0102] Yield of CF3OCOF for ;

[0103] Selectivity of CF3OCOF for .

[0104] The cold trap uses liquid nitrogen as the cold source, and the cold trap temperature is -100 ° C. The non-condensable gas contains most of CO, trace amounts of N2 and CF3OF, and the rest is dissolved in the mixed liquid and enters the cryogenic distillation tower.

[0105] The feed of the low-temperature distillation tower is liquid, and the feed temperature is about -90 ℃; the temperature of the tower bottom is -45 ℃; the reflux condensing temperature of the distillation tower is -90 ℃.

[0106] The unreacted raw material mixture and by-products are recovered by cold trap or cryogenic distillation but not recycled.

[0107] The multi-stream heat exchanger has 4 streams. Including high-temperature stream reaction mixed gas, low-temperature stream cold trap non-condensable gas and low-temperature stream tower top non-condensable gas, low-temperature stream tower top reflux recovery components, and low-temperature stream tower bottom products. The multi-stream heat exchanger is used to cool the high-temperature stream reaction mixed gas, and at the same time, the low-temperature stream non-condensable gas and the low-temperature stream unreacted components CF3OF and CO are reheated and recycled.

[0108] High temperature thermal destruction, alkaline absorption tower and adsorption tower are used to treat the tail gas of the reaction distillation coupling system. The reaction distillation coupling system for synthesizing trifluoromethyl fluoroformate is in a closed space, and all escaping gases must be treated by the tail gas treatment system before being discharged.

[0109] The temperature of thermal destruction of tail gas is 700℃; the alkali solution is 10% NaOH aqueous solution, and a packed absorption tower is used. The packing is a ball ring of PTFE with hydrophilic surface modification; the activated carbon filled in the adsorption bed is impregnated with Na2CO3. The tail gas is discharged after high temperature cracking alkaline absorption tower and adsorption by adsorbent.

[0110] Example 2 50 m long reactor, recovery and recycling of unreacted mixture and by-products

[0111] The same operation as in Example 1 was performed, except that only the unreacted mixture and by-products were recovered and recycled.

[0112] Table 2 Main composition of the mixed gas and circulating products of Example 2

[0113]

[0114] According to the data in Table 2, the conversion rate can be calculated , yield and selectivity They are 73.7%, 82.3% and 81.4% respectively.

[0115] The reflux ratio was set to 1.

[0116] Table 3 Cyclic process of Example 2

[0117]

[0118] Comparative Example 1: 10 m long reactor, unreacted mixture and by-product recovery without recycling

[0119] The same operation as in Example 1 was performed, except that a coil-type 316L stainless steel reactor with a tube length of 10 m was used.

[0120] Table 4 Main composition of the outlet mixed gas and recovered products of Comparative Example 1

[0121]

[0122] According to the data in Table 4, the conversion rate can be calculated , yield and selectivity They are 18.6%, 8.4% and 45.2% respectively.

[0123] Comparative Example 2 10 m long reactor, unreacted mixture and by-product recovery and circulation

[0124] The same operation as in Example 2 was performed, except that a coil-type 316L stainless steel reactor with a tube length of 10 m was used.

[0125] Table 5 Main composition of mixed gas and circulating product of Comparative Example 2

[0126]

[0127] According to the data in Table 5, the conversion rate can be calculated , yield and selectivity They are 28.9%, 16.2% and 56.8% respectively.

[0128] It can be seen from the above embodiments and comparative examples that:

[0129] In Example 1 with a tube length of 50 m, the conversion rate of CF3OF The yield of CF3OCOF is 54.8%. It is 44.7%.

[0130] In Comparative Example 1 with a tube length of 10 m, the conversion rate The yield is 18.6%. It is 8.4%.

[0131] In Example 2 with a tube length of 50 m, the conversion rate of CF3OF The yield of CF3OCOF is 73.7%. It is 82.3%.

[0132] In comparative example 2 with a tube length of 10 m, the conversion rate The yield is 28.9%. It is 16.2%.

[0133] The present embodiment provides a reaction distillation coupling system and method for synthesizing trifluoromethyl fluoroformate. By comparing Example 1 and Example 2 with Comparative Example 1 and Comparative Example 2, respectively, the conversion rate of the raw material and the yield of the target product are significantly improved.

[0134] Reactions (1) and (2) are reversible reactions with high activation energy. Before reaching equilibrium, the reactions are under kinetic control. It can be seen that increasing the length of the coil reactor, i.e., the residence time of the reaction raw materials, can significantly increase the conversion rate of the raw materials and the yield of the target product.

[0135] Furthermore, compared with Example 1, the conversion rate of CF3OF in Example 2 is The yield of CF3OCOF increased from 54.8% in Example 1 to 73.7%. It increased from 44.7% in Example 1 to 82.3%.

[0136] Compared with Comparative Example 1, the conversion rate of CF3OF in Comparative Example 2 is The yield of CF3OCOF increased from 18.6% in Comparative Example 1 to 28.9%. It increased from 8.4% in Comparative Example 1 to 16.2%.

[0137] It can be seen that material recycling can significantly improve the conversion rate of raw materials and the yield of target products. The yield of target products is increased to more than 180% of the state without material recycling. At the same time, it shows that the addition of by-product COF2 can inhibit the reaction to a certain extent (2).

[0138] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for synthesizing trifluoromethyl fluoroformate, characterized in that: The method adopts a system for synthesizing trifluoromethyl fluoroformate, which comprises a reaction unit, a heat exchange unit, a cold trap unit, a cryogenic distillation unit and a recovery circulation unit which are sequentially set up; the reaction unit comprises a feed pipe and a discharge pipe, the discharge pipe is connected to the cold trap unit through 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 circulation unit; wherein the reaction unit comprises a reactor connected to the feed pipe; the heat exchange unit comprises a multi-stream heat exchanger; the cryogenic distillation unit comprises a distillation section and a stripping section, the recovery circulation unit comprises a first circulation pipe and a second circulation pipe for recycling the product from the distillation section, the first circulation pipe is connected to the feed pipe through the second heat exchange pipe, the second circulation pipe is connected to the feed pipe through the first heat exchange pipe, and the first heat exchange pipe, the second heat exchange pipe and the third heat exchange pipe all pass through the multi-stream heat exchanger; the method comprises the following steps: S1, in a reactor, reacting trifluoromethyl hypofluorite with carbon monoxide to generate a reaction mixture including trifluoromethyl fluoroformate; S2, exchanging heat with the reaction mixture in step S1, and separating by cold trap and cryogenic distillation to obtain trifluoromethyl fluoroformate; S3, recovering or recycling the fluorophosgene, raw material trifluoromethyl hypofluorite and carbon monoxide in the reaction mixture after separation after reheating; Wherein, in step S1, the flow rate of trifluoromethyl hypofluorite is 1-1000 L / h; In step S2, the cold trap temperature is lower than -100°C; the temperature of the reflux condensation in the distillation tower is controlled between -105 and -80°C; the feed is a saturated liquid feed, and the feed temperature is lower than -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 and the length of the tube is extended, the tube length is set to 10-200 m, the reaction temperature is 150-480 ° C, and the reaction pressure is 0.1-5 bar (G).

3. The method for synthesizing trifluoromethyl fluoroformate according to claim 1, characterized in that: The flow ratio of the trifluoromethyl hypofluorite 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 or polytetrafluoroethylene or lined with modified polytetrafluoroethylene.

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