Process system and process method for recycling hexafluoropropylene oxide byproduct high-boiling residue

Abstract

The invention provides a process system and a process method for recycling a hexafluoropropylene oxide byproduct high-boiling residue, and relates to the field of fine fluorine chemical industry. The process system comprises a heat exchange device, a tubular pyrolysis reaction device, a carbonyl fluoride-trifluoroacetyl fluoride separation tower, a tubular cracking reaction device, a water washing device and an alkali washing device. According to the method disclosed by the invention, the industrial-grade carbonyl fluoride and trifluoroacetyl fluoride are prepared by catalytically pyrolyzing the hexafluoropropylene oxide by-product high-boiling residue; furthermore, a byproduct high-boiling residue of hexafluoropropylene oxide is subjected to complete catalytic cracking to obtain carbonyl fluoride, and a byproduct industrial hydrofluoric acid can be obtained. According to the process system and the process method, the hexafluoropropylene oxide byproduct is recycled into carbonyl fluoride, trifluoroacetyl fluoride and industrial hydrofluoric acid with high added values, harmlessness and recycling of the hexafluoropropylene oxide byproduct high-boiling residues are achieved, the utilization rate of fluorine atoms is 100%, and the process method is mild in reaction condition, economical and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the field of fine fluorine chemical industry, and in particular to a process system and a process method for resource utilization of high-boiling substances produced as by-products of hexafluoropropylene oxide. Background Art

[0002] Hexafluoropropylene oxide is synthesized by oxidation of hexafluoropropylene, and the oxidants used are hydrogen peroxide, hypochlorite, oxygen, carbonate-chlorine and organic peroxide. At present, the industry mainly uses oxygen oxidation to synthesize hexafluoropropylene oxide, and the selectivity is generally 50-80%, which often produces more high-boiling substances as by-products. The components of high-boiling substances produced under different oxidation reaction conditions are also different. These high-boiling substances are strongly acidic and corrosive, and are generally neutralized with alkali solution and then incinerated. However, after research by scientific researchers, it has been found that the high-boiling substances produced as by-products of hexafluoropropylene oxide have certain practical value.

[0003] CN109678700A discloses a method for preparing byproducts generated in HFPO by comprehensive utilization of oxygen oxidation method, comprising the following steps: 1) using oxygen and hexafluoropropylene as raw materials, preparing hexafluoropropylene oxide under the action of fluoride solvent; the fluoride solvent is recycled; 2) when the byproduct content in the fluoride solvent after recycling is less than 40wt%, ultraviolet light is irradiated every 10 to 30 hours; 3) when the byproduct content is greater than or equal to 40wt%, water is added to the fluoride solvent to obtain a carboxylic acid product. The main component of the oxidized high boiling product in this method is CF3O (CF2O) n (CF(CF3)CF2O) m COF, CF3O(CF2O) n (CF(CF3)CF2O) m OCOF or a mixture thereof, wherein n=1-10, m=1-10. It uses ultraviolet ultraviolet rays to irradiate high boiling points at ultralow temperatures to obtain carbonyl fluoride, and then obtains perfluoropolyether fluid through processes such as adding water, liquid separation, distillation, and fluorination with fluorine gas. However, this method has high reaction temperature requirements, the reaction time is as long as hundreds of hours, and the process is complicated, which is not conducive to industrial scale-up.

[0004] The main component of the high-boiling products of CN102822155 oxidation is CF3O(CF2O)-R (R represents COF, OCOF or CF2COF, and n represents an integer of 0 to 50). The high-boiling products are further thermally decomposed under the condition that the decomposition / isomerization of hexafluoropropylene oxide is not affected, and the high-boiling products are converted into carbonyl fluoride. This method improves the yield of carbonyl fluoride and reduces the amount of high-boiling products. However, the amount of high-boiling products produced as byproducts of hexafluoropropylene oxide cannot be completely recycled, and will affect the yield of the main product hexafluoropropylene oxide.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a process system and a process method for resource utilization of high-boiling products produced as a byproduct of hexafluoropropylene oxide. The present invention uses a "pyrolysis-cracking" method to resource HFPO-GF into industrial-grade carbonyl fluoride and trifluoroacetyl fluoride, and the product has high added value, realizing the resource utilization of high-boiling products produced by distillation of hexafluoropropylene oxide.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a process system for resource utilization of high-boiling products produced as a by-product of hexafluoropropylene oxide, the process system comprising: a heat exchange device, a tubular pyrolysis reaction device, a carbonyl fluoride-trifluoroacetyl fluoride separation tower, a tubular cracking reaction device, a water washing device, and an alkali washing device;

[0009] The outlet end of the heat exchange device is connected to the inlet end of the tubular pyrolysis reaction device, and the high-boiling substances produced by the hexafluoropropylene oxide are preheated by the heat exchange device and then transported to the tubular pyrolysis reaction device;

[0010] The outlet end of the tubular pyrolysis reaction device is connected to the inlet end of the carbonyl fluoride-trifluoroacetyl fluoride separation tower, and the high-boiling substances and oxygen produced as byproducts of hexafluoropropylene oxide are catalytically pyrolyzed in the tubular pyrolysis reaction device, and the catalytic pyrolysis products are sent to the carbonyl fluoride-trifluoroacetyl fluoride separation tower;

[0011] The carbonyl fluoride-trifluoroacetyl fluoride separation tower comprises a carbonyl fluoride-trifluoroacetyl fluoride crude separation tower and a carbonyl fluoride-trifluoroacetyl fluoride fine separation tower connected in series, and is used to separate and obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride;

[0012] The bottom outlet of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower is connected to the inlet of the tubular cracking reaction device, and the bottom outlet of the tubular cracking reaction device is connected to a water washing device. After the bottom materials and oxygen of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower are cracked in the tubular cracking reaction device, the cracked products are transported to the water washing device to obtain industrial hydrofluoric acid and carbon dioxide;

[0013] The water washing device is connected to the alkali washing device, and the carbon dioxide is transported to the alkali washing device via the water washing device for final absorption.

[0014] Preferably, the carbonyl fluoride-trifluoroacetyl fluoride separation tower is reversely connected to the tubular pyrolysis reaction device; after the carbonyl fluoride and trifluoroacetyl fluoride separated in the carbonyl fluoride-trifluoroacetyl fluoride separation tower are vented, oxygen is transported back to the tubular pyrolysis reaction device.

[0015] Preferably, the outlet end of the tubular cracking reaction device further includes another passage:

[0016] The outlet end of the tubular cracking reaction device is connected to the inlet end of the heat exchange device, and the bottom materials and oxygen of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower are cracked in the tubular cracking reaction device, and the cracked products are transported to the heat exchange device for heat exchange;

[0017] The other outlet end of the heat exchange device is directly connected to the inlet end of the tubular pyrolysis reaction device, and the cracking products after heat exchange are transported back to the tubular pyrolysis reaction device by the heat exchange device for circulation and separation.

[0018] Preferably, the outlet end of the alkali washing device further includes another passage:

[0019] The outlet end of the alkali washing device is connected to the other inlet end of the tubular cracking reaction device, so as to transport the unreacted oxygen back to the tubular cracking reaction device.

[0020] In a second aspect, the present invention provides a process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide, wherein the process is carried out using the process system for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide as described in the first aspect, and specifically comprises the following steps:

[0021] (1) transporting the high-boiling products of hexafluoropropylene oxide as a byproduct to a heat exchange device for preheating, and then catalytically pyrolyzing them with oxygen in a tubular pyrolysis reaction device to obtain catalytic pyrolysis products, and then passing the catalytic pyrolysis products through a carbonyl fluoride-trifluoroacetyl fluoride coarse separation tower and a carbonyl fluoride-trifluoroacetyl fluoride fine separation tower to obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride;

[0022] (2) transporting the bottom material obtained by the crude fractionation of the carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower to a tubular cracking reaction device, so that the bottom material is cracked with oxygen to obtain a cracking product;

[0023] (3) transporting the cracking product to a water washing device for water washing to obtain hydrofluoric acid and carbon dioxide; and transporting the carbon dioxide to an alkali washing device for alkali washing to obtain carbonate.

[0024] Preferably, in step (1), in step (1), the high-boiling products produced by the hexafluoropropylene oxide include CF3O (CF2O) n -R, any one or a combination of at least two thereof; wherein the R group represents any one of -COF, -OCOF or -CF2COF, and n is an integer of 0 to 10.

[0025] Preferably, in step (1), the hexafluoropropylene oxide by-product high boiling point products are obtained by the following steps:

[0026] With fluorocarbon reagent as solvent, hexafluoropropylene is oxidized with oxygen to obtain a mixture of hexafluoropropylene oxide and by-product high-boiling substances, which are then separated by distillation to obtain hexafluoropropylene oxide and hexafluoropropylene oxide by-product high-boiling substances.

[0027] Preferably, in step (1), after preheating, the temperature of the high boiling point by-product of hexafluoropropylene oxide is 50-100°C.

[0028] Preferably, in step (1), the mass ratio of the high-boiling products produced as by-products of hexafluoropropylene oxide to oxygen is (1-10):1; wherein the purity of the oxygen is ≥99.5%.

[0029] Preferably, in step (1), a metal oxide-metal fluoride composite catalyst is provided in the tubular pyrolysis reaction device.

[0030] Preferably, the mass ratio of the metal oxide to the metal fluoride is (5-20):1.

[0031] Preferably, the composite catalyst includes any one of Ag2O-NaF, Al2O-NaF, Ag2O-KF, Al2O-NaF, ZrO2-NaF or Ag2O-CsF, or a combination of at least two thereof.

[0032] Preferably, in step (1), the loading amount of the composite catalyst in the tubular pyrolysis reaction device is 50-80%.

[0033] Preferably, in step (1), in the tubular pyrolysis reaction device, the residence time of the catalytic pyrolysis is 5 to 30 s, the temperature of the catalytic pyrolysis is 100 to 180° C., and the pressure of the catalytic pyrolysis is 0 to 1 MPa.

[0034] Preferably, in step (1), the catalytic pyrolysis product is compressed and then enters a carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower for distillation and purification; wherein the pressure of the distillation and purification is 1 to 2 MPa.

[0035] Preferably, in step (1), the carbonyl fluoride and trifluoroacetyl fluoride obtained by coarse fractionation are further introduced into the carbonyl fluoride-trifluoroacetyl fluoride rectification tower for rectification and distillation; wherein the pressure of the rectification and distillation is 2-3 MPa.

[0036] Preferably, in step (1), the top temperature of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower is -50 to -20°C.

[0037] Preferably, in step (1), the top temperature of the carbonyl fluoride-trifluoroacetyl fluoride fractionation tower is 0-30°C.

[0038] Preferably, in step (1), the cooling medium in the coarse fractionation tower and / or the fine fractionation tower is selected from any one of R23, R116, ethylene, liquid nitrogen or liquid argon, or a combination of at least two of them.

[0039] Preferably, in step (2), a metal oxide-metal fluoride composite catalyst is provided in the tubular cracking reaction device.

[0040] Preferably, the mass ratio of the metal oxide to the metal fluoride is (5-20):1.

[0041] Preferably, the composite catalyst includes any one of Ag2O-NaF, Al2O-NaF, Ag2O-KF, Al2O-NaF, ZrO2-NaF or Ag2O-CsF, or a combination of at least two thereof.

[0042] Preferably, in step (2), the loading amount of the composite catalyst in the tubular cracking reaction device is 50-80%.

[0043] Preferably, in step (2), the mass ratio of the bottom material to oxygen is (1-5):1; wherein the purity of the oxygen is ≥99.5%.

[0044] Preferably, in step (2), in the tubular cracking reaction device, the residence time of cracking is 5 to 60 s, the temperature of cracking is 500 to 800° C., and the pressure of cracking is 0 to 0.5 MPa.

[0045] Preferably, in step (2), when the oxygen concentration in the cracking product is ≤20%, the cracking product is transported to the heat exchange device for heat exchange, and then enters the carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower; when the oxygen concentration in the cracking product is >20%, the oxygen concentration is too high, affecting the distillation effect, and the cracking product is transported to the water washing device for water washing.

[0046] Preferably, in step (3), the cracking product carbonyl fluoride is washed with water to generate hydrofluoric acid and carbon dioxide, COF2+H2O→2HF+CO2.

[0047] Preferably, in step (3), during the water washing process, the flow rate of water is controlled by the concentration of hydrofluoric acid, and the mass concentration of hydrofluoric acid is ≥30%.

[0048] Preferably, in step (3), the mass percentage of alkali in the alkali solution used in the alkali washing is 3 to 10%.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention adopts the "pyrolysis-cracking" method to recycle the high-boiling products (HFPO-GF) produced as a by-product of hexafluoropropylene oxide into industrial-grade carbonyl fluoride and trifluoroacetyl fluoride, which has high added value and realizes the resource utilization of high-boiling products in the distillation of hexafluoropropylene oxide.

[0051] (2) The present invention uses a metal oxide-metal fluoride composite catalyst to catalyze the pyrolysis and catalytic cracking of HFPO-GF, which has high catalytic efficiency and mild reaction conditions.

[0052] (3) The present invention renders the highly acidic and corrosive by-product high-boiling products (HFPO-GF) harmless and resourceful, and achieves 100% utilization of fluorine atoms, thus having good environmental and economic advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 The present invention is a schematic diagram of the structure of the process system for resource utilization of high-boiling-point by-products of hexafluoropropylene oxide.

[0055] Among them, E represents a heat exchange device, R1 represents a tubular pyrolysis reaction device, R2 represents a tubular cracking reaction device, T1 represents a carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower, T2 represents a carbonyl fluoride-trifluoroacetyl fluoride fine fractionation tower, T3 represents a water washing device, and T4 represents an alkali washing device. DETAILED DESCRIPTION

[0056] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0057] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0058] It should be noted that specific details are described in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0059] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In a first aspect, the present invention provides a process system for resource utilization of high-boiling-point by-products of hexafluoropropylene oxide, such as Figure 1 As shown, the process system includes: a heat exchange device E, a tubular pyrolysis reaction device R1, a carbonyl fluoride-trifluoroacetyl fluoride separation tower, a tubular cracking reaction device R2, a water washing device T3, and an alkali washing device T4;

[0061] The outlet end of the heat exchange device E is connected to the inlet end of the tubular pyrolysis reaction device R1, and the high-boiling products of the hexafluoropropylene oxide byproduct are preheated by the heat exchange device E and then transported to the tubular pyrolysis reaction device R1;

[0062] The outlet end of the tubular pyrolysis reaction device R1 is connected to the inlet end of the carbonyl fluoride-trifluoroacetyl fluoride separation tower, and the high-boiling substances and oxygen produced by the hexafluoropropylene oxide are catalytically pyrolyzed in the tubular pyrolysis reaction device R1, and the catalytic pyrolysis products are sent to the carbonyl fluoride-trifluoroacetyl fluoride separation tower;

[0063] The carbonyl fluoride-trifluoroacetyl fluoride separation tower comprises a carbonyl fluoride-trifluoroacetyl fluoride crude separation tower T1 and a carbonyl fluoride-trifluoroacetyl fluoride fine separation tower T2 connected in series, and is used to separate and obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride;

[0064] The bottom outlet of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower T1 is connected to the inlet of the tubular cracking reaction device R2, and the outlet of the tubular cracking reaction device R2 is connected to the water washing device T3. After the bottom materials and oxygen of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower T1 are cracked in the tubular cracking reaction device R2, the cracked products are transported to the water washing device T3 to obtain industrial hydrofluoric acid and carbon dioxide;

[0065] The water washing device T3 is connected to the alkali washing device T4, and the carbon dioxide is transported to the alkali washing device T4 via the water washing device T3 for final absorption.

[0066] In the present invention, a process system for resource treatment of high-boiling-point by-products of hexafluoropropylene oxide is provided. The system mainly comprises a heat exchange device E, a tubular pyrolysis reaction device R1, a carbonyl fluoride-trifluoroacetyl fluoride separation tower, a tubular cracking reaction device R2, a water washing device T3, and an alkali washing device T4. The high-boiling-point by-products of hexafluoropropylene oxide (HFPO-GF) are resourced into industrial-grade carbonyl fluoride and trifluoroacetyl fluoride by adopting a "pyrolysis-cracking" method. The products have high added value, and the resource recovery of high-boiling-point by-products of hexafluoropropylene oxide is realized.

[0067] As an optional embodiment, the carbonyl fluoride-trifluoroacetyl fluoride separation tower T2 is reversely connected to the tubular pyrolysis reaction device R1; after the carbonyl fluoride and trifluoroacetyl fluoride separated in the carbonyl fluoride-trifluoroacetyl fluoride separation tower T2 are vented, oxygen is transported back to the tubular pyrolysis reaction device R1.

[0068] As an optional embodiment, the outlet end of the tubular cracking reaction device R2 further includes another passage:

[0069] The outlet end of the tubular cracking reaction device R2 is connected to the inlet end of the heat exchange device E. After the bottom materials and oxygen of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower T1 are cracked in the tubular cracking reaction device R2, the cracked products are transported to the heat exchange device E for heat exchange;

[0070] The other outlet end of the heat exchange device E is directly connected to the inlet end of the tubular pyrolysis reaction device R1, and the cracking products after heat exchange are transported back to the tubular pyrolysis reaction device R1 by the heat exchange device E for circulation and separation.

[0071] As an optional embodiment, the outlet end of the alkali washing device T4 also includes another passage:

[0072] The outlet end of the alkali washing device T4 is connected to the other inlet end of the tubular cracking reaction device R2, so as to transport the unreacted oxygen back to the tubular cracking reaction device R2.

[0073] In a second aspect, the present invention provides a process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide, wherein the process is carried out using the process system for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide as described in the first aspect, and specifically comprises the following steps:

[0074] (1) transporting the high-boiling byproduct of hexafluoropropylene oxide to a heat exchange device E for preheating, and then catalytically pyrolyzing it with oxygen in a tubular pyrolysis reaction device R1 to obtain a catalytic pyrolysis product, and then passing the catalytic pyrolysis product through a carbonyl fluoride-trifluoroacetyl fluoride coarse fractionation tower T1 for coarse fractionation, and a carbonyl fluoride-trifluoroacetyl fluoride fine fractionation tower T2 for fine fractionation, to obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride;

[0075] (2) transporting the bottom material obtained by the crude fractionation of carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower T1 to a tubular cracking reaction device R2, so that the bottom material is cracked with oxygen to obtain a cracking product;

[0076] (3) The cracking product is transported to a water washing device T3 for water washing to obtain hydrofluoric acid and carbon dioxide; and the carbon dioxide is transported to an alkali washing device T4 for alkali washing to obtain carbonate.

[0077] As an optional embodiment, the process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide specifically comprises the following steps:

[0078] (a) using a fluorocarbon reagent as a solvent, hexafluoropropylene and oxygen as raw materials, under conditions of certain temperature and pressure, to synthesize hexafluoropropylene oxide and by-product high boiling products, and separating the by-product high boiling products of hexafluoropropylene oxide (HFPO-GF) by distillation;

[0079] (b) After preheating, HFPO-GF is catalytically pyrolyzed with oxygen in a tubular pyrolysis reaction device R1 containing a catalyst, and the catalytic pyrolysis product is passed through a carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower T1 and further purified in a carbonyl fluoride-trifluoroacetyl fluoride fine fractionation tower T2; the vented components of T2 are returned to R1, and the reflux of T2 and the bottom of the tower are used to obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride respectively;

[0080] (c) The bottom material of T1 is subjected to high-temperature cracking with oxygen in the tubular cracking reaction device R2, and the cracking products are returned to T1 or enter the water washing device T3 after heat exchange;

[0081] (d) The water washing device T3 sprays the cracking products from R2 with water to prepare industrial hydrofluoric acid; the carbon dioxide generated by the water washing is absorbed by the alkaline solution of the alkaline washing device T4; and the unreacted oxygen is returned to the tubular cracking reaction device R2 for cracking reaction.

[0082] As an optional embodiment, in step (1), the high boiling products produced by the hexafluoropropylene oxide include CF3O (CF2O) n-R, any one or a combination of at least two thereof; wherein the R group represents any one of -COF, -OCOF or -CF2COF, and n is an integer from 0 to 10, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0083] It should be noted that under the conditions of catalytic pyrolysis, CF3O(CF2O) n -COF, CF3O(CF2O) n -OCOF main pyrolysis product is carbonyl fluoride; CF3O(CF2O) n The main pyrolysis products of -CF2COF are carbonyl fluoride and trifluoroacetyl fluoride. If the catalytic pyrolysis is too high, trifluoroacetyl fluoride will further decompose into carbonyl fluoride, 2CF3COF+O2→4COF2.

[0084] As an optional embodiment, in step (1), the hexafluoropropylene oxide by-product high boiling point product is obtained by the following steps:

[0085] With fluorocarbon reagent as solvent, hexafluoropropylene is oxidized with oxygen to obtain a mixture of hexafluoropropylene oxide and by-product high-boiling substances, which are then separated by distillation to obtain hexafluoropropylene oxide and hexafluoropropylene oxide by-product high-boiling substances.

[0086] As an optional embodiment, in step (1), after preheating, the temperature of the high boiling point by-product of hexafluoropropylene oxide is 50-100°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc.

[0087] As an optional embodiment, in step (1), the mass ratio of the high-boiling products of hexafluoropropylene oxide by-product to oxygen is (1-10):1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.; wherein the purity of the oxygen is ≥99.5%.

[0088] As an optional embodiment, in step (1), the tubular pyrolysis reaction device R1 is provided with a metal oxide-metal fluoride composite catalyst (M x O y -NaF).

[0089] It should be noted that the metal oxide-metal fluoride composite catalyst (M x O y -NaF) is not only beneficial to reduce the reaction time of pyrolysis, but also HFPO-GF can be completely decomposed in an oxygen atmosphere at a lower reaction temperature.

[0090] As an optional embodiment, in step (1), the metal oxide-metal fluoride composite catalyst (Mx O y -NaF) was prepared by dry mixing method.

[0091] As an optional embodiment, in step (1), the mass ratio of the metal oxide to the metal fluoride is (5-20):1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, etc.

[0092] As an optional embodiment, in step (1), the composite catalyst includes any one of Ag2O-NaF, Al2O-NaF, Ag2O-KF, Al2O-NaF, ZrO2-NaF or Ag2O-CsF, or a combination of at least two thereof.

[0093] As an optional embodiment, in step (1), the loading amount of the composite catalyst in the tubular pyrolysis reaction device is 50-80%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0094] As an optional embodiment, in step (1), in the tubular pyrolysis reaction device R1, the residence time of pyrolysis is 5 to 30 s, for example, it can be 5 s, 6 s, 8 s, 10 s, 12 s, 14 s, 16 s, 18 s, 20 s, 22 s, 24 s, 28 s, 30 s, etc., the pyrolysis temperature is 100 to 180°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc., and the pyrolysis pressure is 0 to 1 MPa, for example, it can be 0 MPa, 0.1 MPa, 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa, 1 MPa, etc.

[0095] As an optional embodiment, in step (1), the catalytic pyrolysis product is compressed and enters the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower T1 for distillation and purification; wherein the distillation and purification pressure is 1 to 2 MPa, for example, it can be 1 MPa, 1.2 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2 MPa, etc.

[0096] As an optional embodiment, in step (1), the crude carbonyl fluoride-trifluoroacetyl fluoride obtained by crude fractionation enters the carbonyl fluoride-trifluoroacetyl fluoride rectification tower T2 for rectification and distillation; wherein the pressure of the rectification and distillation is 2 to 3 MPa, for example, 2MPa, 2.1MPa, 2.2MPa, 2.3MPa, 2.4MPa, 2.5MPa, 2.6MPa, 2.7MPa, 2.8MPa, 2.9MPa, 3MPa, etc.

[0097] As an optional embodiment, in step (1), the top temperature of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower T1 is -50 to -20°C, for example, -50°C, -45°C, -40°C, -35°C, -30°C, -25°C, -20°C, etc.

[0098] As an optional embodiment, in step (1), the top temperature of the carbonyl fluoride-trifluoroacetyl fluoride rectification tower T2 is 0-30°C, for example, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, etc.

[0099] As an optional embodiment, in step (1), the cooling medium in the coarse fractionation tower and / or the fine fractionation tower is selected from any one of R23, R116, ethylene, liquid nitrogen or liquid argon, or a combination of at least two of them.

[0100] As an optional embodiment, in step (2), the tubular cracking reaction device R2 is provided with a metal oxide-metal fluoride composite catalyst (M x O y -NaF).

[0101] It should be noted that the metal oxide-metal fluoride composite catalyst (M x O y -NaF) is beneficial to reducing the reaction time of cracking and lowering the reaction temperature of cracking.

[0102] As an optional embodiment, in step (2), the metal oxide-metal fluoride composite catalyst (M x O y -NaF) was prepared by dry mixing method.

[0103] As an optional embodiment, in step (2), the mass ratio of the metal oxide to the metal fluoride is (5-20):1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, etc.

[0104] As an optional embodiment, the composite catalyst includes any one of Ag2O-NaF, Al2O-NaF, Ag2O-KF, Al2O-NaF, ZrO2-NaF or Ag2O-CsF, or a combination of at least two thereof.

[0105] As an optional embodiment, in step (2), the loading amount of the composite catalyst in the tubular cracking reaction device is 50-80%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0106] As an optional embodiment, in step (2), the mass ratio of the bottom material to oxygen is (1-5):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc.; wherein the purity of the oxygen is ≥99.5%, for example, it can be 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, etc.

[0107] As an optional embodiment, in step (2), in the tubular cracking reaction device R2, the residence time of cracking is 5 to 60 s, for example, it can be 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, 60 s, etc., the temperature of cracking is 500 to 800 ° C, for example, it can be 500 ° C, 550 ° C, 600 ° C, 650 ° C, 700 ° C, 750 ° C, 800 ° C, etc., and the pressure of cracking is 0 to 0.5 MPa, for example, it can be 0 MPa, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, etc.

[0108] As an optional implementation, in step (2), when the oxygen concentration in the cracking product is ≤20%, the cracking product is transported to the heat exchange device E for heat exchange, and then transported back to the tubular pyrolysis reaction device R1; when the oxygen concentration in the cracking product is >20%, the cracking product is transported to the water washing device T3 for water washing.

[0109] As an optional embodiment, in step (3), the cracking product carbonyl fluoride is washed with water to generate hydrofluoric acid and carbon dioxide.

[0110] As an optional embodiment, in step (3), during the water washing process, the flow rate of water is controlled by the concentration of hydrofluoric acid, and the mass concentration of hydrofluoric acid is ≥30%, for example, it can be 30%, 32%, 34%, 36%, 38%, 40%, etc.

[0111] As an optional embodiment, in step (3), the mass percentage of alkali in the alkali solution is 3% to 10%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0112] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0113] Example 1

[0114] This embodiment provides a process for resource recovery of high-boiling-point products produced as by-products of hexafluoropropylene oxide, the method comprising the following steps:

[0115] S1. Preparation of carbonyl fluoride and trifluoroacetyl fluoride:

[0116] S1-1, Pyrolysis:

[0117] After a certain amount of HFPO-GF obtained by the liquid phase oxidation of hexafluoropropylene is transported to a heat exchanger, it is then transported to a tubular pyrolysis reaction device for catalytic pyrolysis with oxygen (the mass ratio of HFPO-GF to oxygen is 6:1) to obtain a catalytic pyrolysis product;

[0118] The tubular pyrolysis reaction device includes a composite catalyst with a loading amount of 60% (mass ratio of Ag2O:NaF = 9:1), a pyrolysis temperature of 150°C, a pressure of 0.6MPa, and a residence time of 10s;

[0119] S1-2, coarse classification-fine classification:

[0120] The catalytic pyrolysis product is passed through T1 distillation (tower pressure of about 0.8-1 MPa, tower top temperature of about -38--42°C), T2 distillation (tower pressure of about 2.6-2.8 MPa, tower top temperature of about 0-5°C) to further obtain industrial grade carbonyl fluoride and trifluoroacetyl fluoride;

[0121] S2, lysis:

[0122] The mass ratio of the sample in the tower bottom of T1 to oxygen is 4:1 and enters the tubular cracking reaction device for catalytic cracking to obtain cracking products; the cracking products return to T1 or enter the water washing device after heat exchange;

[0123] The tubular cracking reaction device includes a composite catalyst with a loading amount of 60% (mass ratio of Ag2O:NaF=9:1); the cracking temperature is 500°C, the pressure is 0.5MPa, and the residence time is 30s.

[0124] S3, water washing-alkali washing

[0125] The pyrolysis product in the tubular pyrolysis reaction device is transported to a water washing device for water washing to obtain hydrofluoric acid and carbon dioxide; wherein the concentration of the hydrofluoric acid is 30%;

[0126] The carbon dioxide is transported to the alkali washing device for absorption through alkali washing; the oxygen is recycled to the tubular cracking reaction device; wherein the mass percentage of sodium hydroxide in the alkali solution is 5%.

[0127] Example 2

[0128] This embodiment 2 provides a process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide, which differs from embodiment 1 in that, in S1, the tubular pyrolysis reaction device includes a composite catalyst with a loading amount of 80%.

[0129] Example 3

[0130] This embodiment 3 provides a process for resource recovery of high-boiling-point products produced as by-products of hexafluoropropylene oxide. The difference from embodiment 1 is that in S1 and S2, the composite catalyst in the tubular pyrolysis reaction device and the tubular cracking reaction device is Ag2O:NaF=20:1.

[0131] Example 4

[0132] This embodiment 4 provides a process for resource recovery of high-boiling-point products produced as by-products of hexafluoropropylene oxide. The difference from embodiment 1 is that in S1 and S2, the composite catalyst in the tubular pyrolysis reaction device and the tubular cracking reaction device is Ag2O:NaF=5:1.

[0133] Example 5

[0134] This embodiment 5 provides a process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide, which differs from embodiment 1 in that, in S1, the pyrolysis temperature in the tubular pyrolysis reaction device is 180°C.

[0135] Example 6

[0136] This Example 6 provides a process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide, which differs from Example 1 in that in S2, the cracking temperature in the tubular cracking reaction device is 800°C.

[0137] Comparative Example 1

[0138] This comparative example provides a process for treating high-boiling products produced as a by-product of hexafluoropropylene oxide, the method comprising the following steps:

[0139] The HFPO-G obtained by the quantitative hexafluoropropylene liquid phase oxidation method is directly transported to a tubular pyrolysis reaction device for catalyst-free catalytic pyrolysis with oxygen (the mass ratio of HFPO-GF to oxygen is 6:1) at a temperature of 150°C, a pressure of 1.2 MPa, and a residence time of 10 seconds to obtain a pyrolysis product; the pyrolysis product is passed through T1 distillation (tower pressure of about 0.8 to 1 MPa, tower top temperature of about -35 to -45°C), T2 distillation (tower pressure of about 2.6 to 2.8 MPa, tower top temperature of about 0 to 10°C) to further obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride; the tower bottom sample of T1 is sent to a tubular cracking reaction device for cracking at a mass ratio of 4:1 to oxygen, at a temperature of 500°C, a pressure of 0.2 MPa, and a residence time of 30 seconds to obtain a cracking product.

[0140] Test Case

[0141] Test samples: products obtained in Examples 1 to 6, and the product obtained in Comparative Example 1;

[0142] Test method: gas chromatography test analysis;

[0143] The test results are shown in Table 1 below:

[0144] Table 1

[0145]

[0146] As shown in Table 1, after being processed by the process method for resource utilization of high-boiling-point byproducts of hexafluoropropylene oxide according to the present invention, the yield of carbonyl fluoride (purity ≥ 99%) obtained is ≥ 50%, and the yield of trifluoroacetyl fluoride (purity ≥ 99%) is ≥ 9%. It is explained that the process method of the present invention can resource the byproducts of hexafluoropropylene oxide into high-value-added carbonyl fluoride, trifluoroacetyl fluoride and industrial hydrofluoric acid, realize the harmlessness and resource utilization of high-boiling-point byproducts of hexafluoropropylene oxide, and the utilization rate of fluorine atoms is 100%, which is a process method with mild reaction conditions, economy and environmental protection.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process system for resource utilization of high-boiling products produced by hexafluoropropylene oxide, characterized in that: The process system comprises: a heat exchange device, a tubular pyrolysis reaction device, a carbonyl fluoride-trifluoroacetyl fluoride separation tower, a tubular cracking reaction device, a water washing device, and an alkali washing device; The outlet end of the heat exchange device is connected to the inlet end of the tubular pyrolysis reaction device, and the high-boiling substances produced by the hexafluoropropylene oxide are preheated by the heat exchange device and then transported to the tubular pyrolysis reaction device; The outlet end of the tubular pyrolysis reaction device is connected to the inlet end of the carbonyl fluoride-trifluoroacetyl fluoride separation tower, and the high-boiling substances and oxygen produced as by-products of hexafluoropropylene oxide are pyrolyzed in the tubular pyrolysis reaction device, and the pyrolysis products are sent to the carbonyl fluoride-trifluoroacetyl fluoride separation tower; The carbonyl fluoride-trifluoroacetyl fluoride separation tower comprises a carbonyl fluoride-trifluoroacetyl fluoride crude separation tower and a carbonyl fluoride-trifluoroacetyl fluoride fine separation tower connected in series, and is used to separate and obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride; The bottom outlet of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower is connected to the inlet of the tubular cracking reaction device, and the bottom outlet of the tubular cracking reaction device is connected to a water washing device. After the bottom materials and oxygen of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower are cracked in the tubular cracking reaction device, the cracked products are transported to the water washing device to obtain industrial hydrofluoric acid and carbon dioxide; The water washing device is connected to the alkali washing device, and the carbon dioxide is transported to the alkali washing device via the water washing device for final absorption.

2. The process system for resource utilization of high-boiling-point by-products of hexafluoropropylene oxide according to claim 1, characterized in that: The carbonyl fluoride-trifluoroacetyl fluoride separation tower is reversely connected to the tubular pyrolysis reaction device; after the carbonyl fluoride and trifluoroacetyl fluoride separated in the carbonyl fluoride-trifluoroacetyl fluoride separation tower are emptied, oxygen is transported back to the tubular pyrolysis reaction device.

3. The process system for resource utilization of high-boiling-point by-products of hexafluoropropylene oxide according to claim 1, characterized in that: The outlet end of the tubular cracking reaction device also includes another passage: The outlet end of the tubular cracking reaction device is connected to the inlet end of the heat exchange device, and the bottom materials and oxygen of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower are cracked in the tubular cracking reaction device, and the cracked products are transported to the heat exchange device for heat exchange; The other outlet end of the heat exchange device is directly connected to the inlet end of the tubular pyrolysis reaction device, and the cracking products after heat exchange are transported back to the tubular pyrolysis reaction device by the heat exchange device for circulation and separation.

4. The process system for resource utilization of high-boiling-point by-products of hexafluoropropylene oxide according to claim 1, characterized in that: The outlet end of the alkali washing device also includes another passage: The outlet end of the alkali washing device is connected to the other inlet end of the tubular cracking reaction device, so as to transport the unreacted oxygen back to the tubular cracking reaction device.

5. A process for resource utilization of high-boiling-point by-products of hexafluoropropylene oxide, characterized in that: The process method is carried out using the process system for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide according to any one of claims 1 to 4, and specifically comprises the following steps: (1) transporting the high-boiling products of hexafluoropropylene oxide as a byproduct to a heat exchange device for preheating, and then catalytically pyrolyzing them with oxygen in a tubular pyrolysis reaction device to obtain catalytic pyrolysis products, and then passing the catalytic pyrolysis products through a carbonyl fluoride-trifluoroacetyl fluoride coarse separation tower and a carbonyl fluoride-trifluoroacetyl fluoride fine separation tower to obtain industrial-grade carbonyl fluoride and trifluoroacetyl fluoride; (2) transporting the bottom material obtained by the crude fractionation of the carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower to a tubular cracking reaction device, so that the bottom material is cracked with oxygen to obtain a cracking product; (3) transporting the cracking product to a water washing device for water washing to obtain hydrofluoric acid and carbon dioxide; and transporting the carbon dioxide to an alkali washing device for alkali washing to obtain carbonate.

6. The process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide according to claim 5, characterized in that: In step (1), the high-boiling products produced by the hexafluoropropylene oxide include CF3O (CF2O) n -R, any one or a combination of at least two; wherein the R group represents any one of -COF, -OCOF or -CF2COF, and n is an integer of 0 to 10; And / or, in step (1), the hexafluoropropylene oxide by-product high boiling point products are obtained by the following steps: With fluorocarbon reagent as solvent, hexafluoropropylene is oxidized with oxygen to obtain a mixture of hexafluoropropylene oxide and by-product high-boiling substances, which are then separated by distillation to obtain hexafluoropropylene oxide and hexafluoropropylene oxide by-product high-boiling substances.

7. The process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide according to claim 5, characterized in that: In step (1), after preheating, the temperature of the high-boiling products of the hexafluoropropylene oxide byproduct is 50 to 100° C.; Preferably, in step (1), the mass ratio of the high-boiling products produced as by-products of hexafluoropropylene oxide to oxygen is (1-10):1; wherein the purity of the oxygen is ≥99.5%; Preferably, in step (1), a metal oxide-metal fluoride composite catalyst is provided in the tubular pyrolysis reaction device; Preferably, the mass ratio of the metal oxide to the metal fluoride is (5-20):1; Preferably, the composite catalyst comprises any one or a combination of at least two of Ag2O-NaF, Al2O-NaF, Ag2O-KF, Al2O-NaF, ZrO2-NaF or Ag2O-CsF; Preferably, in step (1), the loading amount of the composite catalyst in the tubular pyrolysis reaction device is 50-80%; Preferably, in step (1), in the tubular pyrolysis reaction device, the residence time of the catalytic pyrolysis is 5 to 30 s, the temperature of the catalytic pyrolysis is 100 to 180° C., and the pressure of the catalytic pyrolysis is 0 to 1 MPa.

8. The process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide according to claim 5, characterized in that: In step (1), the catalytic pyrolysis product is compressed and then enters a carbonyl fluoride-trifluoroacetyl fluoride crude fractionation tower for distillation and purification; wherein the pressure of the distillation and purification is 1 to 2 MPa; Preferably, in step (1), the carbonyl fluoride and trifluoroacetyl fluoride obtained by crude fractionation are further introduced into the carbonyl fluoride-trifluoroacetyl fluoride rectification tower for rectification and distillation; wherein the pressure of the rectification and distillation is 2-3 MPa; Preferably, in step (1), the top temperature of the carbonyl fluoride-trifluoroacetyl fluoride crude fraction tower is -50 to -20°C; Preferably, in step (1), the top temperature of the carbonyl fluoride-trifluoroacetyl fluoride fractionation tower is 0 to 30° C.; Preferably, in step (1), the cooling medium in the coarse fractionation tower and / or the fine fractionation tower is selected from any one of R23, R116, ethylene, liquid nitrogen or liquid argon, or a combination of at least two of them.

9. The process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide according to claim 5, characterized in that: In step (2), a metal oxide-metal fluoride composite catalyst is provided in the tubular cracking reaction device; Preferably, the mass ratio of the metal oxide to the metal fluoride is (5-20):1; Preferably, the composite catalyst comprises any one or a combination of at least two of Ag2O-NaF, Al2O-NaF, Ag2O-KF, Al2O-NaF, ZrO2-NaF or Ag2O-CsF; Preferably, in step (2), the loading amount of the composite catalyst in the tubular cracking reaction device is 50-80%; Preferably, in step (2), the mass ratio of the bottom material to oxygen is (1-5):1; wherein the purity of the oxygen is ≥99.5%; Preferably, in step (2), in the tubular cracking reaction device, the residence time of cracking is 5 to 60 s, the temperature of cracking is 500 to 800° C., and the pressure of cracking is 0 to 0.5 MPa; Preferably, in step (2), when the oxygen concentration in the cracking product is ≤20%, the cracking product is transported to the heat exchange device for heat exchange, and then transported back to the tubular pyrolysis reaction device; when the oxygen concentration in the cracking product is >20%, the cracking product is transported to the water washing device for water washing.

10. The process for resource recovery of high-boiling-point by-products of hexafluoropropylene oxide according to claim 5, characterized in that: In step (3), the cracking product carbonyl fluoride is washed with water to generate hydrofluoric acid and carbon dioxide; Preferably, in step (3), during the water washing process, the flow rate of water is controlled by the concentration of hydrofluoric acid, and the mass concentration of hydrofluoric acid is ≥30%; Preferably, in step (3), the mass percentage of alkali in the alkali solution used in the alkali washing is 3 to 10%.

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