CN114213239A - Separation and purification process and device for preparing high-purity acyl fluoride compound - Google Patents
Separation and purification process and device for preparing high-purity acyl fluoride compound Download PDFInfo
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Abstract
The invention relates to a separation and purification process and a device for preparing a high-purity acyl fluoride compound, wherein the process comprises the following steps: condensation and separation are firstly carried out on reaction products obtained by preparing hexafluoropropylene oxide by a molecular oxygen liquid-phase oxidation method, low-boiling-point components are pressurized and then input into a rectifying device for two-stage rectification, high-purity carbonyl fluoride can be obtained by membrane separation after the first-stage rectification, and high-purity trifluoroacetyl fluoride can be obtained by membrane separation after the second-stage rectification; the high boiling point component after condensation separation is sequentially input into an extraction rectifying tower and a solvent recovery tower after membrane separation, and high-purity hexafluoropropylene oxide and feed gas hexafluoropropylene can be obtained. Compared with the traditional direct 'washing' separation process, the process disclosed by the invention avoids the generation of a large amount of waste liquid on one hand; on the other hand, the high-purity formyl fluoride and trifluoroacetyl fluoride by-products can be recycled. The invention has simple process route and low energy consumption, and is suitable for the intermittent or continuous production process under the system of preparing the hexafluoropropylene oxide by the molecular oxygen liquid phase oxidation method.
Description
Technical Field
The invention belongs to the technical field of fluorine-containing fine chemicals, and particularly relates to a separation and purification process and a device for preparing a high-purity acyl fluoride compound.
Background
The acyl fluoride compound is widely applied to cleaning agents, etching agents, pesticide intermediates, fluorine-containing material monomers and the like in the electronic industry, and is an important fluorine-containing compound. For example, formyl fluoride (COF)2353-50-4) is an irritant, non-flammable, colorless, toxic gas at ambient temperature. COF2As special electronic gas, the special electronic gas can be used as etching gas and cleaning gas in semiconductor manufacturing, has GWP value of about 1, ODP value of zero and extremely low atmospheric lifetime (< 1a), is environment-friendly electronic gas, and can replace the traditional PFC and NH3. Additional COF2Can also be used as raw materials for organic synthesis to prepare fluorine-containing compounds with high added value, and can also be used for purifying and drying compounds. Trifluoroacetyl fluoride (CF)3COF, CAS:354-34-7) is an important compound which is concerned by being used as an intermediate for chemically synthesizing perfluoroalkyl compounds and is a polymerization monomer necessary for preparing high-purity fluorine-containing polymers, and derivatives thereof are widely applied to various fields.
In the process of preparing hexafluoropropylene oxide by adopting molecular oxygen, besides hexafluoropropylene oxide is generated, byproducts of trifluoroacetyl fluoride and formyl fluoride mainly exist, and the invention patents CN109678700A and CN111072461A adopt a direct water washing mode, so that the problems of resource waste and serious environmental pollution are caused. The new chemical material company of tianjin changliu, CN109678700A, proposes that a fluoride solvent containing by-products is treated by ultraviolet irradiation, on one hand, an important chemical intermediate formyl fluoride can be obtained, and on the other hand, the by-products can be converted into a perfluoro surfactant or a fluorine-containing fluid for further application, but the obtained carboxylic acid solution has high acidity and is seriously corroded on equipment, and the production cost of enterprises is increased. The Dongye company reported in patent CN110845448B that the acyl fluoride by-products were converted into stable neutral esters by alcohol washing, and the esters could be reused, but high purity acyl fluoride compounds could not be obtained directly. Dajin industries corporation in patent CN102822155B proposed a method for producing formyl fluoride and hexafluoropropylene oxide, but this method does not clearly suggest a specific separation process device, and can not be industrialized; the Dongye company reports in patent CN111646916A that trifluoroacetyl fluoride can only be purified to 98 wt% by a simple rectification process, but the purity still can not meet the requirement of electronic special gas.
Disclosure of Invention
In view of the above technical problems in the prior art, the present invention aims to provide a separation and purification process for preparing high purity acyl fluoride compound. The invention provides a separation and purification process and a device for preparing high-purity acyl fluoride compound, which can realize the co-production of hexafluoropropylene oxide, formyl fluoride and trifluoroacetyl fluoride. The invention has simple separation process, low energy consumption and more obvious environmental protection and economic benefits.
Description of terms:
hexafluoropropylene oxide, abbreviated HFPO; hexafluoropropylene, abbreviated HFP.
The boiling points of the various substances in the mixed gas are shown in table 1:
the low-boiling component means COF2And CF3A mixed gas of COF; the high boiling point component means a mixed gas of HFP and HFPO.
The invention aims to provide a separation and purification process and a device for preparing high-purity acyl fluoride compounds.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for separating an acyl fluoride compound during the preparation of hexafluoropropylene oxide comprising the steps of:
(1) the main components of a reaction product obtained by preparing hexafluoropropylene oxide by a molecular oxygen liquid phase oxidation method are hexafluoropropylene HFP serving as a raw material, hexafluoropropylene oxide HFPO serving as a product and acyl fluoride gas serving as a byproduct, wherein the acyl fluoride gas is formyl fluoride COF2And trifluoroacetyl fluoride CF3COF composition, COF2And CF3COF is a low boiling component, HFP and HFPO are high boiling components;
introducing the reaction product into a condensing device for condensation and separation to obtain a mixed gas A containing the acyl fluoride gas and the trace high-boiling-point component and a mixture B containing the trace acyl fluoride gas and the high-boiling-point component;
(2) the mixed gas A in the step (1) is sent into a pressurizing device for pressurization, and then is sent into an acyl fluoride gas rectifying device for two-stage rectification, and the light component gas obtained after the first-stage rectification is further subjected to membrane separation and purification by a membrane separation device to obtain the high-purity COF2Obtaining a finished product; the heavy component after the first stage of rectification is subjected to second stage of rectification, and the light component gas obtained by the second stage of rectification is further subjected to membrane separation and purification by a membrane separation device to obtain high-purity CF3COF；
(3) And (2) reheating the mixture containing trace acyl fluoride gas and high-boiling point components obtained by condensation separation in the step (1) to a gas state, inputting the mixture into a membrane separation device for membrane separation, inputting the separated trace acyl fluoride gas into the first-stage rectification operation of the step (2) for continuous rectification, inputting the high-boiling point components intercepted by the membrane separation and an extracting agent into an extraction rectification tower for extraction rectification, extracting high-purity HFPO from the tower top of the extraction rectification tower, inputting the mixture in the tower bottom into a solvent recovery tower for rectification separation, extracting high-purity HFP from the tower top of the solvent recovery tower, reusing the HFP as a raw material for preparing the HFPO, and recycling the extracting agent to the extraction rectification tower for continuous use after recovery.
Preferably, the reaction product in the step (1) is introduced into a condensing device to carry out two-stage condensation in sequence so as to ensure that a mixed gas A with high purity of the acyl fluoride gas and a mixture B with high purity of the high-boiling-point component are obtained, and the two-stage condensation temperature is controlled to be-55 to-35 ℃.
Preferably, the pressurization is to pressurize the mixed gas A to 2.0-2.5 MPa; the purpose of pressurization is to increase the working temperature of the subsequent rectification equipment and reduce the refrigeration cost.
Preferably, the first-stage rectification in the step (2) adopts two rectification processes which are carried out in sequence, and then the two rectification processes are subjected to membrane separation, so that high-purity formyl fluoride is obtained; wherein, the first rectification is carried out, the rectification pressure is controlled to be 1.0-1.5 MPa, the tower top temperature is-70 to-50 ℃, and the tower kettle temperature is-30 to-0 ℃; and in the second rectification, the rectification pressure is controlled to be 0.9-1.2 MPa, the tower top temperature is-60 to-40 ℃, and the tower kettle temperature is-20 to-0 ℃.
Preferably, after the first stage rectification and membrane separation treatment in the step (2), the method further comprises the step of adding the obtained COF2And (5) carrying out molecular sieve drying.
Preferably, the second-stage rectification in the step (2) is carried out and then membrane separation is carried out, so as to obtain high-purity trifluoroacetyl fluoride, the rectification pressure of the second-stage rectification is 0.6-1.1 MPa, the tower top temperature is-40 to-10 ℃, and the tower kettle temperature is-10 to 10 ℃.
Preferably, after the second stage of rectification and membrane separation treatment in the step (2), the method further comprises the step of subjecting the obtained CF to3COF is subjected to a molecular sieve drying step.
Different pressures are adopted for different rectifications, so that the reaction temperature can be better controlled, the use of a refrigerant is saved, and the cost is saved.
Preferably, the method further comprises the step of recovering and treating trifluoroacetyl fluoride containing trace amount of formyl fluoride under the pressure of 0.8-1.3 MPa after the first-stage rectification, and then performing second-stage rectification. The recovery treatment is carried out under the conditions, so that the purity of the trifluoroacetyl fluoride in the second rectification can be improved. Recovered chip containing a trace amount of COF2The light components can be returned to the first stage rectification operation of step (2)And (5) continuing rectification.
Preferably, the heavy component after the first-stage rectification is sent into a formyl fluoride recovery tower for further rectification and purification before the second-stage rectification, and the rectification pressure of the formyl fluoride recovery tower is 0.8-1.3 MPa; the temperature of the top of the tower is-40 to-20 ℃, and the temperature of the bottom of the tower is-20 to 0 ℃.
Preferably, the rectifying pressure of the extraction rectifying tower in the step (3) is 0.3-0.8 MPa, the tower top temperature is-30-0 ℃, and the tower kettle temperature is 0-20 ℃.
Preferably, the rectification pressure of the solvent recovery tower in the step (3) is normal pressure, the tower top temperature is 0-10 ℃, and the tower kettle temperature is 60-90 ℃.
The separation method not only can realize the separation of hexafluoropropylene oxide and hexafluoropropylene, but also can obtain high-purity formyl fluoride and trifluoroacetyl fluoride. The separation process is simple, the energy consumption is low, and the problems of resource waste and environmental pollution caused by direct water washing are avoided.
The present invention also provides a separation and purification apparatus for producing a high-purity acyl fluoride compound, the apparatus comprising: condensing unit, compressor arrangement, rectifier unit, membrane separation device, extraction rectifying column and solvent recovery tower.
The rectifying device comprises a first-stage rectifying system and a second-stage rectifying system; the membrane separation device comprises a first membrane separator, a second membrane separator and a third membrane separator. The light component gas discharged from the first-stage rectification system is subjected to membrane separation and purification through a first membrane separator to obtain COF with higher purity2(ii) a The light component gas discharged from the second stage rectification system is subjected to membrane separation and purification through a second membrane separator to obtain high-purity CF3And (3) COF. A light component gas outlet of the condensing device is connected with a feed inlet of the first-stage rectification system through a compression device by a pipeline, and heavy component tower bottoms discharged from the first-stage rectification system are sent to the second-stage rectification system for further rectification; the heavy component outlet of the condensing device is connected with a third membrane separator through a pipeline, the third membrane separator comprises outlets at two sides, one outlet for discharging separated trace acyl fluoride gas is connected with the feed inlet of the first-stage rectification system through a pipeline, and the other outlet is connected with the feed inlet of the second-stage rectification system through a pipelineOne side of the outlet for discharging the high boiling point component intercepted by the membrane separation is connected with the feed inlet of the extraction rectifying tower through a pipeline. And the tower bottom liquid of the extraction and rectification tower is sent to a solvent recovery tower for further separation.
Preferably, the condensing device comprises a first condenser and a second condenser which are connected in series, wherein a gas inlet of the second condenser is connected with a light component gas outlet of the first condenser through a pipeline, and the condensing device is used for carrying out two-stage condensation so as to ensure that a mixed gas A with high acyl fluoride gas purity and a mixture B with high boiling point component purity are obtained.
Preferably, the rectifying device comprises a first rectifying tower, a second rectifying tower, a formyl fluoride recovery tower and a third rectifying tower which are connected in series, and the first rectifying tower and the second rectifying tower are combined to form a COF (chip on film) for rectifying and purifying2The second rectifying tower is used for receiving the light component gas discharged from the first rectifying tower and further rectifying the light component gas to obtain COF with higher purity2(ii) a And tower kettle outlets of the first rectifying tower and the second rectifying tower are connected with a feed inlet of the formyl fluoride recovery tower through pipelines, a tower top gas outlet of the formyl fluoride recovery tower is connected with the first rectifying tower, and tower kettle liquid of the formyl fluoride recovery tower is sent into a third rectifying tower for further rectification.
The light component gas outlet of the second condenser is connected with the feed inlet of the first rectifying tower through a pipeline by a compression device.
Preferably, the membrane separation device comprises a first membrane separator, a second membrane separator and a third membrane separator, the first membrane separator is connected with an air outlet at the top of the second rectifying tower through a pipeline, and the second membrane separator is connected with an air outlet at the top of the third rectifying tower through a pipeline; heavy component outlets of the first condenser and the second condenser are connected with an inlet of a third membrane separator through pipelines, the third membrane separator comprises outlets on two sides, wherein the outlet on one side is connected with a feed inlet of the first rectifying tower through a pipeline, and the outlet on the other side is connected with a feed inlet of the extractive rectifying tower through a pipeline.
The compression device is used for pressurizing the mixed gas A, and aims to improve the working temperature of subsequent rectification equipment and reduce the refrigeration cost.
The first rectifying tower is used for receiving the mixed gas A pressurized by the compression device and the trace acyl fluoride gas separated by the third membrane separator and rectifying the mixed gas A and the trace acyl fluoride gas.
And the second rectifying tower is used for receiving the tower top gas of the first rectifying tower and further rectifying the tower top gas to obtain the formyl fluoride with higher purity.
The first membrane separator is used for receiving the top gas of the second rectifying tower and intercepting impurity gas to obtain higher-purity formyl fluoride.
And the formyl fluoride recovery tower is used for receiving the mixture output from the tower kettle after the treatment of the first rectifying tower and the second rectifying tower.
Preferably, the top of the formyl fluoride recovery tower is used for being connected with the first rectifying tower, and the gas which is not rectified thoroughly is recycled to the first rectifying tower.
And the third rectifying tower is used for receiving the mixture output by the formyl fluoride recovery tower from the tower bottom and rectifying the mixture to output trifluoroacetyl fluoride.
The second membrane separator is used for receiving the top gas of the third rectifying tower and intercepting impurity gas so as to obtain trifluoroacetyl fluoride with higher purity.
The third membrane separator is used for receiving the mixture B output by the first condenser and the second condenser.
And the extraction and rectification tower is used for receiving the high-boiling-point component separated by the third membrane separator and carrying out extraction and rectification to obtain high-purity hexafluoropropylene oxide.
And the solvent recovery tower is used for receiving the mixture output from the tower kettle after the extraction and rectification tower is used for processing so as to respectively obtain the extracting agent and the high-purity raw material gas hexafluoropropylene.
The first membrane separator, the second membrane separator and the third membrane separator are all provided with fluorine-containing polyimide membranes, so that the permeation flux of the acyl fluoride gas can be improved.
The first rectifying tower, the second rectifying tower, the formyl fluoride recovery tower, the third rectifying tower, the extraction rectifying tower and the solvent recovery tower are all conventional packed towers with condensers and reboilers.
More preferably, the first membrane separator further comprises a step of drying the obtained formyl fluoride by a molecular sieve after separation.
And after the separation by the second membrane separator, the step of drying the obtained trifluoroacetyl fluoride by using a molecular sieve is also included.
More preferably, the separation process unit is a packed tower, and the packing is selected from at least one of nickel, Monel, nickel-chromium alloy or polytetrafluoroethylene; the type of the filler is at least one of pall ring, intalox saddle ring or theta ring; the specific surface area of the filler is 100-2500 m2/m3。
More preferably, the filling height of the filler is 1000-30000 mm.
The separation process according to the invention is preferably carried out by means of a separation device according to the invention, comprising the following steps:
(1) introducing a reaction product obtained by preparing hexafluoropropylene oxide by a molecular oxygen liquid phase oxidation method into a first condenser, and collecting COF-containing substances from the top2、CF3COF and a small amount of a high boiling point component, and a mixture X containing HFP, HFPO and a small amount of a low boiling point component is obtained at the bottom.
(2) The mixed gas C is continuously introduced into a second condenser as described in (1), and COF is obtained at the top2、CF3COF and trace amount of high boiling point component, and a mixture D containing HFP, HFPO and trace amount of low boiling point component is obtained at the bottom.
(3) Inputting the mixed gas A obtained in the step (2) into a compression device, and controlling the pressure to be 2.0-2.5 MPa; inputting the mixture X and the mixture D obtained in the steps (1) - (2) into a third membrane separator.
(4) The outlet of the compression device in the step (3) is connected to a first rectifying tower, the operating pressure of the first rectifying tower is controlled to be 1.0-1.5 MPa, the temperature of the top of the tower is-70 to-50 ℃, and the temperature of the bottom of the tower is-30 to 0 ℃; the trace CF is obtained at the top of the first rectifying tower3COF of COF, HFPO, HFP2Mixed gas E, obtaining a product containing trace COF at the bottom of the tower2CF of HFPO, HFP3And recycling the mixture F of the COF to the formyl fluoride recovery tower.
(5) Inputting the mixed gas E into a second rectifying tower through a discharge pipe at the top of the first rectifying tower in the step (4), controlling the operating pressure of the second rectifying tower to be 0.9-1.2 MPa, controlling the temperature at the top of the second rectifying tower to be-60-40 ℃, controlling the temperature at the bottom of the second rectifying tower to be-20-0 ℃, and separating COF containing trace impurity gas at the top of the second rectifying tower2。
(6) Inputting the gas collected from the top of the second rectifying tower into a first membrane separator according to the step (5), and after the gas is subjected to selective separation by a fluorine-containing polyimide membrane, COF2Gas enters a first molecular sieve drying tower to finally obtain COF with the purity of more than 99.99 percent2And (5) finishing.
(7) The discharge pipe of the tower kettle of the second rectifying tower is connected to the formyl fluoride recovery tower in the step (6), the operating pressure of the formyl fluoride recovery tower is controlled to be 0.8-1.3 MPa, the temperature of the tower top is-40 to-20 ℃, the temperature of the tower kettle is-20 to 0 ℃, and the condition that the tower kettle of the formyl fluoride recovery tower does not contain COF (chip on film) is ensured2In the case of (2), a fraction containing CF is withdrawn from the top of the column3COF of COF2And circulating to the first rectifying tower.
(8) The discharging pipe of the tower kettle of the formyl fluoride recovery tower in the step (7) is connected to a third rectifying tower, the operating pressure of the third rectifying tower is controlled to be 0.6-1.1 MPa, the temperature of the tower top is-40 to-10 ℃, the temperature of the tower kettle is-10 to 10 ℃, and CF containing trace impurity gas is separated from the tower top3COF。
(9) Inputting the gas collected from the top of the third rectifying tower into a second membrane separator according to the step (8), and selectively separating the gas by using a fluorine-containing polyimide membrane to obtain CF3COF gas enters a second molecular sieve drying tower to finally obtain CF with the purity of more than 99.999 percent3COF, and discharging residual liquid in the tower kettle at regular intervals.
(10) And (4) after the selective separation of the polyimide membrane in the third membrane separator in the step (3), inputting the low-boiling-point component into the first rectifying tower, and inputting the high-boiling-point component and the extracting agent into the extractive rectifying tower.
(11) Controlling the operating pressure of the extractive distillation tower in the step (10) to be 0.3-0.8 MPa, controlling the temperature at the top of the tower to be-30-0 ℃, controlling the temperature at the bottom of the tower to be 0-20 ℃, and collecting HFPO gas from the top of the tower and introducing the HFPO gas into a third molecular sieve drying tower to finally obtain an HFPO finished product with the purity of more than 99.99%; the mixture G containing the extracting agent and HFP is extracted from the tower bottom and then sent into a solvent recovery tower,
(12) the operation pressure of the solvent recovery tower in the step (11) is normal pressure, the temperature of the top of the tower is 0-10 ℃, the temperature of the bottom of the tower is 60-90 ℃, and HFP with the purity of more than 99.99% is extracted from the top of the tower and circulated to the reaction kettle to be used as a raw material continuously; the extractant is recovered from the bottom of the tower kettle and is circulated to the extraction and rectification tower for continuous use.
By adopting the technical scheme, the invention has the beneficial effects that:
1) compared with the traditional direct washing process for preparing hexafluoropropylene oxide by molecular oxygen, the separation and purification process and the device for preparing the high-purity acyl fluoride compound avoid generating a large amount of waste liquid on one hand; on the other hand, the high-purity formylfluoride and trifluoroacetyl fluoride by-products can be obtained for resource utilization.
2) The separation process has simple route and low energy consumption, and is suitable for the intermittent or continuous production process for preparing hexafluoropropane by preparing molecular oxygen.
The invention can realize the production of hexafluoropropylene oxide and simultaneously obtain high-purity formyl fluoride and trifluoroacetyl fluoride through the combined process device of pressurized rectification and membrane separation. After rectification and membrane separation, the high-purity formyl fluoride and trifluoroacetyl fluoride can be sold or used as raw materials, the profitability is greatly improved, and the benefits of enterprises are increased.
Drawings
FIG. 1 is a schematic flow diagram of a separation process apparatus according to the present invention. In the figure, I-1 is a first condenser; i-2 is a second condenser; II, a compression device; III-1 is a first rectifying tower; III-2 is a second rectifying tower; III-3 is a formyl fluoride recovery tower; III-4 is a third rectifying tower; IV-1 is a first membrane separator; IV-2 is a second membrane separator; IV-3 is a third membrane separator; v-1 is an extraction rectifying tower; v-2 is a solvent recovery tower; VI-1 is a first molecular sieve drying tower; VI-2 is a second molecular sieve drying tower; VI-3 is a third molecular sieve drying tower; VI-4 is a third molecular sieve drying tower.
Detailed Description
The invention is described below with reference to examples. It should be noted that the examples are only for explaining the present invention, and are not limited to these examples. It is within the scope of the present invention to modify and replace the details and forms of the present invention.
Example (b): compare FIG. 1
The separation and purification device for preparing the high-purity acyl fluoride compound comprises a condensing device, a compression device II, a rectifying device, a membrane separation device and an extraction rectifying tower V.
The condensation device comprises a first condenser I-1 and a second condenser II-2 which are connected in series, wherein the gas inlet of the second condenser II-2 is connected with the light component gas outlet of the first condenser I-1 through a pipeline, and the condensation device is used for carrying out two-stage condensation so as to ensure that mixed gas A with high acyl fluoride gas purity is obtained and mixture B with high boiling point component purity is obtained.
The rectifying device comprises a first rectifying tower III-1, a second rectifying tower III-2, a formyl fluoride recovery tower III-3 and a third rectifying tower III-4 which are connected in series, wherein the first rectifying tower III-1 and the second rectifying tower III-2 are combined to form a rectifying and purifying COF2The second rectifying tower III-2 is used for receiving the light component gas discharged from the first rectifying tower III-1 and further rectifying the light component gas to obtain COF with higher purity2(ii) a The tower kettle outlets of the first rectifying tower III-1 and the second rectifying tower III-2 are connected with a feed inlet of a formyl fluoride recovery tower III-3 through a pipeline, a tower top air outlet of the formyl fluoride recovery tower III-3 is connected with the first rectifying tower III-1, and tower kettle liquid of the formyl fluoride recovery tower III-3 is sent to a third rectifying tower III-4 for further rectification;
the membrane separation device comprises a first membrane separator IV-1, a second membrane separator IV-2 and a third membrane separator IV-3, wherein the first membrane separator IV-1 is connected with a gas outlet at the top of the second rectifying tower III-2 through a pipeline, and the second membrane separator IV-2 is connected with a gas outlet at the top of the third rectifying tower III-4 through a pipeline; heavy component outlets of the first condenser I-1 and the second condenser II-2 are connected with an inlet of a third membrane separator IV-3 through a pipeline, the third membrane separator IV-3 comprises outlets on two sides, wherein the outlet on one side is connected with a feed inlet of a first rectifying tower III-1 through a pipeline, and the outlet on the other side is connected with a feed inlet of an extractive rectifying tower V through a pipeline;
and a light component gas outlet of the second condenser II-2 is connected with a feed inlet of the first rectifying tower III-1 through a compression device by a pipeline.
The rectifying device further comprises:
the first molecular sieve drying tower VI-1 is connected with the first membrane separator IV-1 to purify and dry the formyl fluoride;
a second molecular sieve drying tower VI-2 which is used for connecting with the second membrane separator IV-2 to purify and dry trifluoroacetyl fluoride;
and the third molecular sieve drying tower VI-3 is used for being connected with the extractive distillation tower V-1 to dry the hexafluoropropylene oxide gas.
And a fourth molecular sieve drying tower VI-4 which is used for connecting with the solvent recovery tower V-2 to dry the hexafluoropropylene gas.
The first rectifying tower III-1, the second rectifying tower III-2, the formyl fluoride recovery tower III-3, the third rectifying tower III-4, the extractive rectifying tower V-1 and the solvent recovery tower V-2 adopt packed towers, and the packing is selected from at least one of nickel, Monel alloy, nickel-chromium alloy or polytetrafluoroethylene; the type of packing is at least one of pall rings, intalox saddles or theta rings.
Example 1
The separation and purification process and apparatus for preparing a high purity acyl fluoride compound of the present invention are illustrated in the following flow scheme with reference to FIG. 1:
(1) introducing a reaction product obtained by preparing hexafluoropropylene oxide by a molecular oxygen liquid phase oxidation method into a first condenser I-1, wherein the main components of the reaction product comprise 1-5 wt% of hexafluoropropylene HFP serving as a raw material, 59-75 wt% of hexafluoropropylene oxide HFPO serving as a product, and formyl fluoride COF2With trifluoroacetyl fluoride CF3The total content of COF is 20-40 wt%. The temperature of the first condenser I-1 is controlled to be-55 to-35 ℃, and COF is collected from the top2、CF3COF and a small amount of a high boiling point component, and a mixture X containing HFP, HFPO and a small amount of a low boiling point component is obtained at the bottom.
(2) The mixed gas C is continuously introduced into a second condenser I-2 as in (1), the temperature is controlled to be-55 to-35 ℃, and COF is obtained at the top2、CF3COF and trace amount of high boiling point component, and a mixture D containing HFP, HFPO and trace amount of low boiling point component is obtained at the bottom.
(3) Inputting the mixed gas A into a compression device II as in the step (2), and controlling the pressure to be 2.0-2.5 MPa; and (3) rewarming the mixture X and the mixture D obtained in the steps (1) to (2) to a gas state, and inputting the mixture X and the mixture D into a third membrane separator IV-3 for membrane separation.
(4) The outlet of the compression device II is connected to a first rectifying tower III-1 according to the step (3), the operating pressure of the first rectifying tower III-1 is controlled to be 1.0-1.5 MPa, the temperature of the top of the tower is-70 to-50 ℃, and the temperature of the bottom of the tower is-30 to-0 ℃; the trace CF is obtained at the top of the first rectifying tower III-13COF of COF, HFPO, HFP2Mixed gas E, obtaining a product containing trace COF at the bottom of the tower2CF of HFPO, HFP3And recycling the mixture F of the COF to the formyl fluoride recovery tower III-3.
(5) The mixed gas E is input into a second rectifying tower III-2 through a discharge pipe at the top of the first rectifying tower III-1 in the step (4), the operating pressure of the second rectifying tower III-2 is controlled to be 0.9-1.2 MPa, the temperature at the top of the second rectifying tower is controlled to be-60-40 ℃, the temperature at the bottom of the second rectifying tower is controlled to be-20-0 ℃, and COF containing trace impurity gas is separated from the top of the second rectifying tower2。
(6) The gas collected from the top of the second rectifying tower III-2 in the step (5) is input into a first membrane separator IV-1, and after the gas is selectively separated by a fluorine-containing polyimide membrane, COF2Gas enters a first molecular sieve drying tower VI-1 to finally obtain COF with the purity of more than 99.99 percent2Finished product, COF2The recovery rate is more than 99 percent.
(7) The discharge pipe of the second rectifying tower III-2 tower bottom is connected to a formyl fluoride recovery tower III-3 in the step (6), the operation pressure of the formyl fluoride recovery tower III-3 is controlled to be 0.8-1.3 MPa, the tower top temperature is-40 to-20 ℃, the tower bottom temperature is-20 to-0 ℃, and the tower bottom of the formyl fluoride recovery tower is ensured not to contain COF2In the case of (2), a fraction containing CF is withdrawn from the top of the column3COF of COF2Recycled to the first rectifying tower III-1.
(8) The formyl fluoride recovery tower III-3 kettle discharge pipe is connected to a third rectifying tower III-4 as shown in (7), the operating pressure of the third rectifying tower III-4 is controlled to be 0.6-1.1 MPa, the temperature at the top of the tower is-40 to-10 ℃, the temperature at the bottom of the tower is-10 to 10 ℃, and CF containing trace impurity gas is separated from the top of the tower3COF。
(9) The gas collected from the top of the third rectifying tower III-4 is input into a second membrane separator IV-2 according to the step (8), and after the gas is selectively separated by a fluorine-containing polyimide membrane, CF is3COF gas enters a second molecular sieve drying tower VI-2 to finally obtain CF with the purity of more than 99.999 percent3COF，CF3COF recovery rate is more than 99 percent; and discharging residual liquid in the tower kettle at regular intervals.
(10) After the fluorine-containing polyimide film in the third film separator IV-3 is subjected to selective film separation, the low boiling point component is input into the first rectifying tower III-1, and the high boiling point component and the extractant dichloroethane are input into the extraction rectifying tower V.
(11) The operation pressure of the extraction and rectification tower V is controlled to be 0.3-0.8 MPa, the temperature of the top of the tower is-30-0 ℃, the temperature of the bottom of the tower is 0-20 ℃, HFPO gas is extracted from the top of the tower and enters a third molecular sieve drying tower VI-3, finally, an HFPO finished product with the purity of more than 99.99 percent is obtained, and the recovery rate of the HFPO is more than 99 percent. And (4) inputting the tower kettle mixture of the extraction and rectification tower V into a solvent recovery tower for rectification and separation.
(12) The operation pressure of the solvent recovery tower in the step (11) is normal pressure, the temperature of the top of the tower is 0-10 ℃, the temperature of the bottom of the tower is 60-90 ℃, HFP with the purity of more than 99.99 percent is extracted from the top of the tower and recycled to the reaction kettle to be used as a raw material, and the recovery rate of the HFP is more than 98 percent; the extractant is recovered from the bottom of the tower kettle and is circulated to the extraction and rectification tower for continuous use.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (10)
1. A separation and purification process for preparing high-purity acyl fluoride compounds is characterized by comprising the following steps:
(1) the main components of a reaction product obtained by preparing hexafluoropropylene oxide by a molecular oxygen liquid phase oxidation method are hexafluoropropylene HFP serving as a raw material, hexafluoropropylene oxide HFPO serving as a product and a byproduct acyl fluoride gas, wherein the byproduct acyl fluoride gas is formyl fluoride COF2And trifluoroacetyl fluoride CF3COF composition, COF2And CF3COF is a low boiling component, HFP and HFPO are high boiling components;
introducing the reaction product into a condensing device for condensation and separation to obtain a mixed gas A containing the acyl fluoride gas and the trace high-boiling-point component and a mixture B containing the trace acyl fluoride gas and the high-boiling-point component;
(2) the mixed gas A in the step (1) is sent into a pressurizing device for pressurization, then is sent into a rectifying device for two-stage rectification, and the light component gas obtained after the first-stage rectification is further subjected to membrane separation and purification by a membrane separation device to obtain the high-purity COF2Obtaining a finished product; the heavy component after the first stage of rectification is subjected to second stage of rectification, and the light component gas obtained by the second stage of rectification is further subjected to membrane separation and purification by a membrane separation device to obtain high-purity CF3COF；
(3) And (2) reheating the mixture containing trace acyl fluoride gas and high-boiling point components obtained by condensation separation in the step (1) to a gas state, inputting the mixture into a membrane separation device for membrane separation, inputting the separated trace acyl fluoride gas into the first-stage rectification operation of the step (2) for continuous rectification, inputting the high-boiling point components intercepted by the membrane separation and an extracting agent into an extraction rectification tower for extraction rectification, extracting high-purity HFPO from the tower top of the extraction rectification tower, inputting the mixture in the tower bottom into a solvent recovery tower for rectification separation, extracting high-purity HFP from the tower top of the solvent recovery tower, reusing the HFP as a raw material for preparing the HFPO, and recycling the extracting agent to the extraction rectification tower for continuous use after recovery.
2. The separation and purification process for preparing high-purity acyl fluoride compound according to claim 1, wherein the membrane separation devices in the steps (2) - (3) are all provided with fluorine-containing polyimide membranes.
3. The separation and purification process for preparing high-purity acyl fluoride compound according to claim 1, wherein the reaction product in step (1) is introduced into a condensing device to perform two-stage condensation successively, so as to ensure that the mixed gas A with high purity of acyl fluoride gas and the mixture B with high purity of high-boiling-point component are obtained, and the temperature of the two-stage condensation is controlled to be-55 to-35 ℃;
and (3) pressurizing and compressing the mixed gas A to 2.0-2.5 MPa by using a pressurizing device in the step (2), wherein the purpose of pressurizing is to improve the working temperature of subsequent rectification equipment and reduce the refrigeration cost.
4. The separation and purification process for preparing acyl fluoride compound with high purity according to claim 1, wherein the first stage of rectification in step (2) adopts two rectification processes which are sequentially carried out, and then the acyl fluoride compound is subjected to membrane separation, so that high-purity formyl fluoride is obtained; wherein, the first rectification is carried out, the rectification pressure is controlled to be 1.0-1.5 MPa, the tower top temperature is-70 to-50 ℃, and the tower kettle temperature is-30 to-0 ℃; the second rectification is carried out, wherein the rectification pressure is controlled to be 0.9-1.2 MPa, the tower top temperature is-60 to-40 ℃, and the tower kettle temperature is-20 to-0 ℃;
after the first-stage rectification and membrane separation treatment in the step (2), the method also comprises the step of carrying out COF treatment on the obtained COF2And (5) carrying out molecular sieve drying.
5. The separation and purification process for preparing high-purity acyl fluoride compound according to claim 1, wherein the second stage rectification in step (2) is followed by membrane separation to obtain high-purity trifluoroacetyl fluoride, the rectification pressure of the second stage rectification is controlled to be 0.6-1.1 MPa, the temperature of the top of the column is-40 to-10 ℃, and the temperature of the bottom of the column is-10 to 10 ℃;
after the second stage of rectification and membrane separation treatment in the step (2), the method also comprises the step of carrying out CF treatment on the obtained product3COF is subjected to a molecular sieve drying step.
6. The separation and purification process for preparing high-purity acyl fluoride compound according to claim 1, wherein the heavy component after the first rectification in step (2) is sent to a formyl fluoride recovery tower for further rectification and purification before the second rectification, so as to further remove trace COF2To increase CF in the second stage of rectification3Purity of COF, trace COF contained extracted from top of formyl fluoride recovery tower2Returning the light components to the first stage of rectification operation in the step (2) for continuous rectification;
the rectification pressure of the formyl fluoride recovery tower is 0.8-1.3 MPa; the temperature of the top of the tower is-40 to-20 ℃, and the temperature of the bottom of the tower is-20 to 0 ℃.
7. The separation and purification process for preparing a high-purity acyl fluoride compound according to claim 1, wherein in the step (3), the rectification pressure of the extractive rectification tower is 0.3-0.8 MPa, the temperature of the top of the tower is-30-0 ℃, and the temperature of the bottom of the tower is 0-20 ℃;
in the step (3), the rectification pressure of the solvent recovery tower is normal pressure, the tower top temperature is 0-10 ℃, and the tower kettle temperature is 60-90 ℃.
8. A separation and purification device for preparing high-purity acyl fluoride compounds is characterized by comprising a condensing device, a compressing device, a rectifying device, a membrane separation device, an extractive rectifying tower (V-1) and a solvent recovery tower (V-2);
the rectifying device comprises a first-stage rectifying system and a second-stage rectifying system; the membrane separation device comprises a first membrane separator (IV-1), a second membrane separator (IV-2) and a third membrane separator (IV-3);
the light component gas discharged from the first-stage rectification system is subjected to membrane separation and purification through a first membrane separator (IV-1) to obtain COF with higher purity2(ii) a The light component gas discharged from the second stage rectification system is subjected to membrane separation and purification by a second membrane separator (IV-2) to obtain CF with higher purity3COF；
A light component gas outlet of the condensing device is connected with a feed inlet of the first-stage rectification system through a compression device by a pipeline, and heavy component tower bottoms discharged from the first-stage rectification system are sent to the second-stage rectification system for further rectification; the heavy component outlet of the condensing device is connected with a third membrane separator (IV-3) through a pipeline, the third membrane separator (IV-3) comprises outlets at two sides, wherein one outlet for discharging separated trace acyl fluoride gas is connected with the feed inlet of the first-stage rectification system through a pipeline, and the outlet at the other side for discharging high-boiling-point components intercepted by membrane separation is connected with the feed inlet of the extraction rectification tower (V-1) through a pipeline.
9. The separation and purification apparatus for producing a high-purity acyl fluoride compound according to claim 8,
the condensation device comprises a first condenser (I-1) and a second condenser (II-2) which are connected in series, wherein a gas inlet of the second condenser (II-2) is connected with a light component gas outlet of the first condenser (I-1) through a pipeline, and the condensation device is used for carrying out two-stage condensation to ensure that a mixed gas A with high acyl fluoride gas purity and a mixture B with high boiling point component purity are obtained;
the rectifying device comprises a first rectifying tower (III-1), a second rectifying tower (III-2), a formyl fluoride recovery tower (III-3) and a third rectifying tower (III-4) which are connected in series, wherein the first rectifying tower (III-1) and the second rectifying tower (III-2) are combined to form a rectifying and purifying COF2The second rectifying tower (III-2) is used for receiving the light component gas discharged from the first rectifying tower (III-1) and further rectifying the light component gas to obtain COF with higher purity2(ii) a The tower kettle outlets of the first rectifying tower (III-1) and the second rectifying tower (III-2) are connected with the feed inlet of the formyl fluoride recovery tower (III-3) through pipelines, and the tower top gas outlet of the formyl fluoride recovery tower (III-3) is connected with the first rectifying tower (III)-1) connecting, and feeding the tower bottoms of the formyl fluoride recovery tower (III-3) to a third rectifying tower (III-4) for further rectification;
the membrane separation device comprises a first membrane separator (IV-1), a second membrane separator (IV-2) and a third membrane separator (IV-3), wherein the first membrane separator (IV-1) is connected with a gas outlet at the top of the second rectifying tower (III-2) through a pipeline, and the second membrane separator (IV-2) is connected with a gas outlet at the top of the third rectifying tower (III-4) through a pipeline; heavy component outlets of the first condenser (I-1) and the second condenser (II-2) are connected with an inlet of a third membrane separator (IV-3) through a pipeline, the third membrane separator (IV-3) comprises outlets on two sides, wherein the outlet on one side is connected with a feed inlet of the first rectifying tower (III-1) through a pipeline, and the outlet on the other side is connected with a feed inlet of the extractive rectifying tower (V-1) through a pipeline;
a light component gas outlet of the second condenser (II-2) is connected with a feed inlet of the first rectifying tower (III-1) through a compression device by a pipeline;
the outlet of the extraction rectifying tower (V-1) is connected with the feed inlet of the solvent recovery tower (V-2) through a pipeline.
10. The apparatus for separating and purifying an acyl fluoride compound having a high purity as claimed in claim 9, wherein the rectification apparatus further comprises:
a first molecular sieve drying tower (VI-1) which is connected with the first membrane separator (IV-1) to purify and dry the formyl fluoride;
a second molecular sieve drying tower (VI-2) which is used for connecting with the second membrane separator (IV-2) to purify and dry trifluoroacetyl fluoride;
the first rectifying tower (III-1), the second rectifying tower (III-2), the formyl fluoride recovery tower (III-3), the third rectifying tower (III-4), the extractive rectifying tower (V-1) and the solvent recovery tower (V-2) adopt packed towers, and the packing is selected from at least one of nickel, Monel alloy, nickel-chromium alloy or polytetrafluoroethylene; the type of packing is at least one of pall rings, intalox saddles or theta rings.
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| GB1545174A (en) * | 1977-11-17 | 1979-05-02 | Asahi Glass Co Ltd | Method of purifying hexafluoropropylene oxide |
| CN101003524A (en) * | 2006-12-29 | 2007-07-25 | 山东东岳神舟新材料有限公司 | Method for recovering hexafluropropylene oxide |
| CN101070266A (en) * | 2007-06-20 | 2007-11-14 | 北京萃亨科技有限公司 | Freon 22/hexafluoropropylene azeotrope separating and recovering method |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1545174A (en) * | 1977-11-17 | 1979-05-02 | Asahi Glass Co Ltd | Method of purifying hexafluoropropylene oxide |
| CN101003524A (en) * | 2006-12-29 | 2007-07-25 | 山东东岳神舟新材料有限公司 | Method for recovering hexafluropropylene oxide |
| CN101070266A (en) * | 2007-06-20 | 2007-11-14 | 北京萃亨科技有限公司 | Freon 22/hexafluoropropylene azeotrope separating and recovering method |
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