KR100405187B1 - Preparation Method of Octafluorecyclobutane(RC318) - Google Patents

Abstract

The present invention is a octa by dimerization of tetrafluoroethylene (C ₂ F ₄ , hereinafter referred to as 'TFE') prepared in the pyrolysis reaction of difluorochloromethane (CF ₂ HCl, hereinafter 'R22') The present invention relates to a pyrolysis method for preparing fluorocyclobutane (C ₄ F ₈ , hereinafter referred to as 'RC318'), and more particularly, to prepare TFE from pyrolysis of difluorochloromethane by dilution of superheated steam. Severe exothermic reaction in the dimerization reaction of conventional TFE by supplying TFE and water vapor at a constant molar ratio to a fluidized bed reactor equipped with a nozzle capable of supplying water vapor at a constant reaction temperature and contact time conditions to perform dimerization of TFE. New production method for producing high yield octafluorocyclobutane (RC318) under stable reaction conditions by preventing formation of solid polymer and carbon by preventing local overheating It is about.

Description

Preparation method of octafluorocyclobutane (RCC31) {Preparation Method of Octafluorecyclobutane (RC318)}

The present invention is a dimerization reaction of tetrafluoroethylene (C ₂ F ₄ , hereinafter referred to as 'TFE') prepared by pyrolysis of difluorochloromethane (CF ₂ HCl, hereinafter referred to as 'R22'). The present invention relates to a pyrolysis method for producing octafluorocyclobutane (C ₄ F ₈ , hereinafter referred to as 'RC318'), and more particularly, to TFE from pyrolysis of difluorochloromethane by dilution of superheated steam. After the preparation, the TFE and water vapor in a constant molar ratio are supplied to a fluidized bed reactor equipped with a nozzle capable of supplying water vapor under a constant reaction temperature and contact time conditions to carry out the dimerization reaction of TFE, and thus, in the conventional dimerization reaction of TFE. It is possible to produce high yield octafluorocyclobutane (RC318) under stable reaction conditions by preventing the formation of solid polymer and carbon by preventing local overheating caused by severe exothermic reaction of It relates to a new manufacturing method.

RC318 is used as a propellant, a refrigerant, and a semiconductor cleaning agent. As the refrigerant of the air conditioner turbo compressor is proved to be effective, the demand for the refrigerator market will increase considerably. Recently, RC318 has been announced by Dupont as a cleaning gas for semiconductor CVD (Chemical Vapor Deposition) chambers that can replace hexafluoroethane (C ₂ F ₆ ), which is used as a conventional semiconductor cleaner. However, the demand is expected to increase significantly because of the impact on global warming. The method for preparing RC318 is a method by thermal decomposition of difluorochloromethane [US Patent No. 2,384,821 (1945)], a method by dimerization of tetrafluoroethylene [US Patent No. 2,404,374 (1946), Japanese Patent 57 -59,82 (1982)], Simons electrochemical fluorination (European Patent No. 0,445,399 (1991)) using ethylene and TFE as reaction materials, and polytetrafluoroethylene (PTFE) Methods by pyrolysis (US Pat. No. 2,394,581 (1946), US Pat. No. 2,759,983 (1956)) and the like have been reported to date.

Harmon et al. Have described the formation of RC318 and HFP as the main products of the reaction in the study of pyrolysis of TFE (US Pat. No. 2,404,374 (1946)). Atkinson and Trenwith conducted a kinetic study on the pyrolysis of TFE and the pyrolysis of RC318 [J. of Chem. Soc., 2082 (1953), J. of Chem. Soc., 2086 (1957), reported that pyrolysis of RC318 at temperatures lower than 550 ° C. produced mainly TFE and HFP. The method of preparing RC318 by dimerization of TFE is a method of producing RC318 by dimerizing TFE at about 500 ° C. The synthesis scheme of RC318 by TFE dimerization is shown in Scheme 1 below.

The most common RC318 manufacturing process is the pyrolysis of TFE in a tubular reactor. However, this process is difficult to control the reaction temperature because the dimerization reaction of the TFE is a severe exothermic reaction. TFE is decomposed into carbon and CF ₄ at a high temperature, and also accumulates at the outlet of the reactor together with the produced solid polymer, which acts as a factor of pressure increase in the reaction system. When carbon is generated and accumulated inside the reactor, the reaction pressure increases, the contact time of TFE increases and the calorific value increases, so that the reaction proceeds in series and the reaction temperature rises to 1000 ° C. or more in an instant. It leads to a situation. Therefore, the process of preparing RC318 by performing the dimerization reaction of TFE in the tubular reactor is not suitable for commercialization due to the problem of reaction temperature control caused by severe exothermic reaction.

Hukuseishiro also reported a method of preparing RC318 using TFE and ammonia as reaction raw materials (Japanese Patent 57-59822 (1982)). In this case, TFE is bubbled into ammonia and supplied or fed to the reactor using a respective metering pump, followed by reaction at a temperature of 570 to 700 ° C., a reaction pressure of 0 to 5 atm and a contact time of 0.3 to 5 seconds. The conversion rate 50-70% and the selectivity of RC318 85-86% were obtained. However, the process has a problem in that the polymerization rate is generated when the reaction rate is high to block the reaction tube, when the reaction rate is low, the reaction rate is lowered, the industrial value is lowered.

A process for preparing RC318 by pyrolysis of polytetrafluoroethylene was published in 1946 by Benning et al. (US Pat. No. 2,394,581 (1946)). When PTFE was pyrolyzed at a temperature of 575 ° C., 43% of RC318 was produced. Announced. However, the above method is a method for preparing RC318 by polymerizing TFE, and then pyrolyzing PTFE to produce RC318, which is not preferable as a method for preparing commercial RC318 because the process is complicated and the production cost of RC318 is high.

William Ves et al. Published a process for preparing RC318 using TFE, ethylene, and fluorine (European Patent No. 0,455,399 (1991)). First, cyclo-C ₄ F ₄ H ₄ is prepared by reacting a molar ratio of ethylene / TFE at 10/1, and then RC318 is prepared by Simmons electrochemical fluorination at 40 to 50 ° C. However, the process also has a low industrial value because of the high production cost of RC318. At this time, the reaction formula of TFE and ethylene and the fluorination reaction between cyclo-C ₄ F ₄ H ₄ and HF is as shown in equations 2 and 3.

Therefore, in the present invention, in order to solve the problems in the conventional RC318 production, by producing a TFE by pyrolyzing R22 under superheated steam, RC318 was prepared by supplying a certain amount of TFE and water vapor to the fluidized bed reactor, especially the severe TFE The problem of reactor operation due to the formation of solid polymer as well as carbon in the tubular reactor due to the exothermic reaction is to use a fluidized bed reactor equipped with a nozzle capable of supplying water vapor so that the dimerization of TFE in the presence of water vapor is carried out. It has been found that the present invention can be improved to complete the present invention. In the present invention, the dimerization reaction temperature of TFE can be easily controlled by the outer wall temperature of the reactor, the molar ratio of TFE / H ₂ O and the contact time, and under the stable reaction conditions since the formation of solid polymer and carbon is suppressed by supplying water vapor. High yields of RC318 can be made.

Accordingly, an object of the present invention is to provide a novel method for preparing octafluorocyclobutane (RC318) which can be applied in various ways more efficiently, such as pyrolysis reaction or oxidation reaction, in which a reactor operation was difficult due to a severe exothermic reaction.

1 shows an apparatus for pyrolysis of R22 and a dimerization of TFE according to the present invention.

[Explanation of symbols on the main parts of the drawings]

1 Mass Flow Controller 2 Preheater 3 Reactor

4: ultra-high temperature electric reactor 5: water tank 6: pump

7 steam generator 8 HCl absorption column 9 NaOH column

10 Dryer 11 Inert Distillation Column 12 TFE Distillation Column

13 fluidized bed reactor 14 acidic gas scrubber 15 filter

In the present invention, tetrafluoroethylene (TFE) prepared by pyrolyzing difluorochloromethane (R22) and octafluorine are supplied to a fluidized bed reactor at a molar ratio of 0.1 to 10 to carry out the dimerization reaction of tetrafluoroethylene. The manufacturing method of cyclocyclobutane (RC318) is characterized by the above-mentioned.

The present invention will be described in more detail as follows.

Reaction regarding the production of TFE and RC318 according to the present invention is shown in the following schemes 4 and 5.

The present invention is characterized by a method for producing RC318 by dimerization of TFE and water vapor produced in a fluidized bed reactor through the pyrolysis reaction of R22, as shown in the formulas (4) and (5).

The reaction system for the R22 pyrolysis reaction and the TFE dimerization reaction used in the present invention is as shown in Fig. 1 attached to the present invention. In the present invention, difluorochloromethane (R22) is a preheater shown in Fig. 1. It is prepared through a pyrolysis reaction of R22 using a pyrolysis device composed of a super heating unit, a cooler and a pyrolysis reactor. Tetrafluoroethylene (TFE) discharged from the pyrolysis reactor is purified through a TFE distillation column after passing through an HCl absorption tower, a NaOH neutralization tower and a water dryer, and then supplied to the bottom of the fluidized bed reactor. In addition, H ₂ O is preheated by a liquid pump, and then supplied with steam under a TFE flow through a distributor installed at the bottom of the fluidized bed reactor.

In the present invention, the reaction raw material TFE is prepared through a pyrolysis reaction of R22 using a pyrolysis device composed of a preheater, an electric furnace, a cooler, and a TFE distillation column shown in FIG. 1. At this time, the pure TFE is purified in a distillation column and then fed to the bottom of the fluidized bed reactor. In addition, H ₂ O is preheated by a liquid pump, and then supplied with steam under a TFE flow through a distributor installed at the bottom of the fluidized bed reactor.

In particular, in the present invention, by supplying TFE / H ₂ O having an appropriate molar ratio to the fluidized bed reactor to perform the dimerization reaction of TFE, by producing a high yield of RC318 under stable reaction conditions while suppressing the production of solid polymer and carbon, It is possible to solve the problem of temperature control generated when performing the TFE dimerization reaction in the tubular reactor.

Therefore, in the present invention, the molar ratio of TFE / H ₂ O during the TFE dimerization reaction is maintained at 0.1 to 10, more preferably 0.5 to 5, and if the molar ratio is less than the above range, there is a problem of controlling the reaction temperature. If the range is exceeded, the yield of RC318 falls. And, the reaction temperature is maintained at 550 ~ 700 ℃, more preferably 600 ~ 650 ℃, if the reaction temperature is less than the above range there is a problem that the conversion of the TFE falls, if the above range the side reaction proceeds RC318 There is a problem that the selectivity of. In addition, the contact time in the fluidized bed reactor is maintained at 1 to 30 seconds, more preferably 10 to 20 seconds, and if the contact time is less than the above range, there is a problem that the conversion rate of the TFE falls. Even though the side reaction proceeds, the selectivity of RC318 falls.

In the present invention, TFE can be produced by pyrolysis of R22 by superheated steam dilution. To this end, R22 is supplied to the preheater (2) using a mass flow controller (1), where the temperature of the preheater is maintained between 100 and 300 ° C by a Proportional-Integral-Derivative (PID) temperature controller. And the preheated reactant is fed to a pyrolysis reactor 3 (V = 0.203 liter). Then, the water for superheated steam is depressurized by vacuum in the water tank 5 to remove the air, pressurized with nitrogen and maintained at normal pressure, and then a predetermined amount is supplied to the steam generator 7 by the pump 6. The steam generator 7 adjusts the flow rate of the liquefied natural gas (LPG) so that the outlet temperature of the steam is maintained at about 500 ~ 600 ℃, the superheated steam is 900 ~ 950 in the super heating unit (4) Superheated to < 0 > C and then fed to the pyrolysis reactor (3). Once the reaction system is stable, the pyrolysis reaction is initiated by supplying R22 at the desired flow rate instead of nitrogen gas. The outlet gas of the reactor is quenched by mixing with HCl solution in HCl absorption tower 8 made of carbon graphite to suppress side reactions, and HCl is removed from the absorption tower. HCl absorption tower (8) is a rubber lining (rubber lining), the carbon cooler to circulate the cooling water from the outside to remove the heat of absorption and sensible heat. The organic product from which the acid is removed in the HCl absorption column is neutralized in NaOH column (9) again to remove traces of HCl and passed through a dryer (10) filled with molecular sieve to remove moisture. In addition, since the upper part of the TFE distillation column is concentrated in low water, the concentration of TFE and oxygen may increase, and thus room temperature polymerization may occur. Therefore, alpha-pinene (alpha-pinene) [Wako Pure Chemical] is a polymerization inhibitor for stabilization of TFE. 4] to 0.005 ml / min to stabilize the TFE.

Inert materials such as N ₂ , R 14 (tetrafluoromethane; CF ₄ ), R23 (trifluoromethane; CHF ₃ ), and R116 (hexafluoroethane; CF ₃ CF ₃ ) in the reaction product are separated in an inert distillation column (11), In the TFE distillation column 12, unreacted R22 and the low water are separated, and then pure TFE is purified in the middle stage of the distillation column. When the purity of the TFE was 99.99% or higher, the TFE was passed through a flow controller and then flown into a fluidized bed reactor 13 made of SUS (OD = 60.6 mm, ID = 52.7 cm, L / D = 6 in the reaction zone). Supply to carry out the dimerization reaction of TFE. And activated carbon is used as a heat medium for fluidization. The minimum fluidizing velocity (Umf) was measured in a fluidized bed reactor made of quartz, and the experimental results confirmed that Umf = 4.6 cm / sec. Pure water is fed to the reactor using a pump so that there is a certain amount of TFE / H ₂ O molar ratio. The reaction product is passed through an acid gas scrubber (14) to remove acid, and through a filter (15) to remove the solid polymer, followed by a thermal conductivity detector and gas chromatography [Series 550P, Porapak Q column (1). / 8 inch 3 m, sus) attached, analyzed using Gow-Mac. The reaction product is also identified using GC / MS [HP 5890/5971, Poraplot Q capillary column attached, Hewlett Packard Corporation].

The present invention performs GC calibration of binary mixtures for TFE-RC318 and RC318-HFP to calculate conversion and product selectivity from gas chromatography analysis results. Since other reaction products are produced in a small amount, GC area% is assumed to be GC mole%, and the area ratio of gas chromatography is converted into molar ratio. The conversion rate for the pyrolysis reaction of TFE and the selectivity of RC318 and HFP are calculated from the following Equations 1 to 3, and the selectivity of the other components can be calculated from the carbon resin equation.

As described above, in the present invention, TFE can be obtained with high efficiency by designing a fluidized bed pyrolysis reaction and purification system in consideration of efficient purification of impurities that may be included in TFE, prevention of polymerization in a process, inhibition of carbon production, and stable reaction temperature control. Can be.

In this case, the temperature of the outer wall of the reactor is controlled by using a thermocouple of two heating zones attached to the outer wall of the reactor. The actual reaction temperature varies with the temperature of the outer wall, the molar ratio of TFE / water vapor and the contact time, and the reaction temperature (t ₁ , t ₂ , t ₃ , t ₄ and t ₅ ) using five thermocouples installed inside the fluidized bed reactor. Measure Where t ₁ and t ₂ are the temperatures at which the fluidization of the reactants occurs, and t ₃ , t ₄ and t ₅ are the temperatures of the parts insulated so that polymerization of TFE does not occur. Although the dimerization reaction of TFE is a severe exothermic reaction, the temperature distribution inside the reactor can be controlled relatively uniformly by using a fluidized fluidized bed reaction system.

In particular, the fluidized bed reaction apparatus equipped with a nozzle for supplying water vapor according to the present invention has a severe exothermic reaction, making it difficult to control the temperature, and is applied to a pyrolysis reaction or an oxidation reaction in which acid (fluoric acid, hydrochloric acid, sulfuric acid, or nitric acid) is generated as a by-product. Since it can suppress local temperature rise, it can be usefully applied to reactions with severe exothermic reactions, and there is an advantage of easily removing by-product acids.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited by the examples.

Example 1.

RC318 manufacturing experiments were performed using a TFE dimerization reactor equipped with a fluidized bed reactor shown in FIG. 1. Pure TFE was prepared by performing R22 pyrolysis experiment by superheated steam dilution. R22 was fed to the reactant preheater at 44.2 mol / h using a mass flow controller, preheated to 200 ° C. and then to the reaction system. The oxygen-free water was supplied to a steam generator at 6 kg / h using a pump to generate steam at 550 ° C., and then to an ultra high temperature electric reactor, and a pyrolysis reaction of R22 was performed at a reaction temperature of 740 ° C. to TFE. Was prepared. TFE was purified in a distillation column and then fed to the fluidized bed reactor at 5 mol / h, and water vapor (H ₂ O) was fed at 3 mol / h under the TFE flow in the fluidized bed reactor. And molar ratio of constant reaction conditions (TFE / H ₂ O) = 1.67, contact time (room temperature, atmospheric pressure) = 13.86 seconds, reaction temperature t ₁ = 605 ° C, t ₂ = 604 ° C, and t ₃ = 601 ° C. As a result of the pyrolysis reaction, the conversion of TFE was 63.34% and the selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 89.35% and 5%, respectively.

Example 2.

Dimerization of TFE was carried out under the same reaction conditions as in Example 1, except that the reaction temperature of the fluidized bed reactor was maintained at t ₁ = 662 ° C, t ₂ = 662 ° C, and t ₃ = 623 ° C. . As a result, the conversion of TFE was 78.45%, and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 84.66% and 9.42%, respectively.

Example 3.

TFE was prepared in the same manner as in Example 1 except that TFE was supplied to the fluidized bed reactor at 7.17 mol / h, and water vapor was supplied under the TFE flow in the fluidized bed reactor at 3 mol / h. The dimerization reaction was carried out under the reaction conditions of TFE / H ₂ O molar ratio = 2.39, contact time 10.9 sec, reaction temperature t ₁ = 662 ° C, t ₂ = 663 ° C, and t ₃ = 632 ° C. The conversion of was 78.85% and selectivity of octafluorocyclobutane and hexafluoropropylene was 87.96% and 7.14%, respectively.

Example 4.

Dimerization of TFE was carried out under the same reaction conditions as in Example 3, except that the reaction temperature of the fluidized bed reactor was maintained at t ₁ = 610 ° C, t ₂ = 610 ° C, and t ₃ = 603 ° C. . The conversion of TFE was 70.9% and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 90.5% and 5.86%, respectively.

Example 5.

TFE was prepared in the same manner as in Example 1 except that TFE was supplied to the fluidized bed reactor at 2.85 mol / h and water vapor was supplied under the TFE flow in the fluidized bed reactor at 3 mol / h. The dimerization reaction was carried out under the reaction conditions of TFE / H ₂ O = 0.95, contact time 18.96 sec, reaction temperature t ₁ = 631 ℃, t ₂ = 630 ℃, and t ₃ = 603 ℃, and as a result The conversion was 73.39% and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 89.6% and 4.18%, respectively.

Example 6.

Dimerization of TFE was carried out under the same reaction conditions as in Example 5, except that the reaction temperatures t ₁ = 718 ° C., t ₂ = 718 ° C., and t ₃ = 665 ° C. of the fluidized bed reactor were maintained. The conversion of TFE was 81.54% and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 51.24% and 25.88%, respectively.

Example 1-6 The contact time of TFE with H ₂ O feed rate, TFE / H ₂ O molar ratio, the reactor entrance criteria for the reaction temperature (t _1, t ₂ and t _3), the conversion rate and the respective product The selectivity for is summarized in Table 1 below.

Comparative Example 1.

Instead of the fluidized bed reactor in the pyrolysis and purification system shown in FIG. 1, a TFE dimerization reaction was carried out using a tubular reactor (ID = 21 mm, OD = 24.5 mm, L = 1200 mm) (not shown). It was. Five thermocouples were used to measure the longitudinal temperature distribution (T ₁ , T ₂ , T ₃ , T ₄ and T ₅ ) from the inlet to the outlet of the tubular reactor. The distance between the thermocouples is 30 cm, and T ₃ , T ₄ and T ₅ are the longitudinal temperature distributions of the zone where the reaction takes place in the tubular reactor. Then, TFE was prepared in the same manner as in Example 1. TFE was purified in a distillation column and then fed to the TFE pyrolysis reactor at 5 mol / h to carry out the pyrolysis reaction under reaction conditions of reaction pressure 1.5 kg / cm 2 and reaction temperature (T ₃ , T ₄ , T ₅ ) 454 ~ 517 ℃. It was. Initial conversion of TFE was 91.3%, and selectivity of octafluorocyclobutane and hexafluoropropylene was 92.05% and 7.56%, respectively. The temperature of the reaction zone was measured at 30 cm intervals from the reactor inlet standard. However, since the local exothermic reaction zone moves according to the outer wall temperature and the contact time of the reactor, the temperature of the intermediate point between the thermocouples could not be measured and the exact reaction temperature could not be confirmed. In addition, as the reaction proceeded, the amount of solid polymer produced increased, and carbonization of TFE proceeded by local exothermic reaction to produce CF ₄ . Because of the problems of reactor temperature control, the produced carbide accumulates in the tubular reactor and the line, causing the pressure to rise, resulting in further exothermic reactions.

Comparative Example 2.

Pyrolysis experiment of TFE was performed under the same conditions as in Comparative Example 1 except that the reaction temperature (T ₃ , T ₄ , T ₅ ) was maintained at 533-581 ° C. The conversion of TFE was 96.0%, and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 79.79% and 18.0%, respectively. The same reactor operation problem as in Comparative Example 1 occurred, and as the reaction temperature range was higher than that of Comparative Example 1, the local exothermic reaction proceeded more severely, resulting in a large problem of reactor temperature control.

Comparative Example 3.

Pyrolysis experiment of TFE under the same conditions as in Comparative Example 1 except that the feed flow rate of TFE was increased to 6.5 mol / h and the reaction temperature (T ₃ , T ₄ , T ₅ ) was maintained at 547-590 ° C. Was performed. The conversion of TFE was 95.12% and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 76.71% and 21.11%, respectively.

Comparative Example 4.

Except that the flow rate of TFE was increased to 6.0 mol / h and the reaction temperature (T ₃ , T ₄ , T ₅ ) of the initial reaction was maintained at 510 to 616 ° C, Pyrolysis experiments were performed. The conversion of TFE was 95.66% and selectivity of octafluorocyclobutane and hexafluoropropylene was obtained at 65.0% and 34.7%, respectively.

The feed rate, reaction pressure, reaction temperature (T ₃ , T ₄ , T ₅ ), conversion rate, and selectivity of each product for TFE for Comparative Examples 1 to 4 are summarized in Table 2 below.

As a result of comparing Examples 1 to 6 and Comparative Examples 1 to 4, the TFE pyrolysis conversion in the conventional tubular reactor was obtained higher than that in the fluidized bed reactor due to the local severe exothermic reaction. In addition, the initial stage RC318 selectivity of the reactor in the tubular reactor was higher than that of the fluidized bed reactor. However, as the reaction proceeds, the reaction temperature increases as the local exothermic reaction region moves, but the selectivity of RC318 decreases, but the selectivity of HFP increases with the increase of carbide.

In contrast, the present invention is a process for producing TFE by pyrolyzing R22 under superheated steam, and then supplying TFE and water vapor to a fluidized bed reactor to produce RC318, in particular carbon production in the tubular reactor due to severe exothermic reaction of TFE Of course, problems in reactor operation due to the production of solid polymers have been greatly improved. The dimerization reaction temperature of TFE was easily controlled by the outer wall temperature of the reactor, the molar ratio of TFE / H ₂ O and the contact time, and the production of solid polymer and carbon was suppressed by supplying water vapor. In addition, Example 5 and Example 6 is a case in which the dimerization reaction is performed in a fluidized bed reactor under the same conditions but with different reaction temperatures. Example 6, which remained in the high temperature range compared to Example 5, had a significantly lower selectivity of RC318 of 51.24%. As a result, it was confirmed that the selectivity of RC318 was determined by the reaction conditions such as the reaction temperature, the molar ratio of TFE / H 2 O, and the contact time.

According to the results of Table 1 and Table 2, it is expected that if a fluidized bed reactor equipped with a nozzle capable of supplying water vapor is used, it may be variously applied to pyrolysis reactions or oxidation reactions that are difficult to operate due to severe exothermic reactions. It can be seen that the selectivity of RC318 can be increased by optimizing the reaction conditions such as the reaction temperature, the molar ratio of TFE / H 2 O and the contact time.

As described above, the method of manufacturing RC318 according to the present invention is conventionally severe by preventing local overheating by performing a dimerization reaction of a TFE produced by pyrolyzing R22 in a fluidized bed reactor equipped with a nozzle for steam supply. It suppresses the formation of solid polymer and carbon in the tubular reactor due to exothermic reaction and has the effect of producing high yield RC318 under stable reaction conditions.

Claims (6)

Pyrolysis of difluorochloromethane (R22) to produce tetrafluoroethylene (TFE), The prepared tetrafluoroethylene and water vapor were supplied to a fluidized bed reactor at a molar ratio of 0.95 to 2.39, and contacted for 10.9 to 18.96 seconds in a temperature range of 550 to 700 ° C. to carry out a dimerization reaction of tetrafluoroethylene (TFE). Method for producing octafluorocyclobutane (RC318) characterized in that. The method for producing octafluorocyclobutane according to claim 1, wherein the fluidized bed reactor is attached with a nozzle capable of supplying water vapor. The method of claim 1, wherein the tetrafluoroethylene (TFE) is prepared in a pyrolysis apparatus of difluorochloromethane (R22) consisting of a preheater, a super heating unit, a cooler and a pyrolysis reactor. The tetrafluoroethylene (TFE) gas discharged from the pyrolysis reactor is passed through an HCl absorption tower, a NaOH neutralization tower, and a water dryer, and then purified in a TFE distillation column and supplied to a fluidized bed reactor, octafluorocyclobutane (RC318). Manufacturing method. The method of claim 1, wherein the water vapor is preheated by supplying water to the liquid pump, and then supplied to the fluidized bed reactor under a tetrafluoroethylene flow through a distributor installed at the bottom of the fluidized bed reactor. Process for producing cyclocyclobutane. delete delete