KR0176325B1 - The manufacturing method of 1,1,1 trifluoro-2-chloroethan & 1,1,1,2-tetrafluorethane - Google Patents

Abstract

The present invention is to prepare 1,1,1,2-tetrafluoroethane through 1,1,1-trifluoro-2-chloroethane in a two-step reaction using trichloroethylene and hydrogen fluoride as raw materials It is about a method.

In the production method of the present invention, the two-stage reaction is performed in different reactors, and the reactors are arranged in parallel so that by-products (HCl) generated in one reactor are not introduced into another reactor. Preparation of 1,1,1-trifluoro-2-chloroethane When the reaction product mixture produced in the reactor is separated into an upper effluent and a lower effluent in a distillation column, 1,1, The molar ratio composition of 1,1-trifluoro-2-chloroethane and hydrogen fluoride is adjusted to 1 to 1 or more so that it is supplied to the reaction for producing 1,1,1,2-tetrafluoroethane. According to the present invention, a method of easily controlling the composition of the raw materials fed to the two reactors, respectively, is provided, and unreacted substances and by-products that may affect the reaction can be prevented from being introduced into the other reactors.

Description

Process for preparing 1,1,1-trifluoro-2-chloroethane and 1,1,1,2-tetrafluoroethane

1 is a schematic diagram of a conventional reaction process for producing 1,1,1-trifluoro-2-chloroethane and 1,1,1,2-tetrafluoroethane by a two-step reaction, a serial arrangement method.

2 is a schematic diagram of a reaction process for producing 1,1,1-trifluoro-2-chloroethane and 1,1,1,2-tetrafluoroethane by a conventional two-step reaction, parallel arrangement method.

3 is a schematic diagram of a reaction process for producing 1,1,1-trifluoro-2-chloroethane and 1,1,1,2-tetrafluoroethane by a two-step reaction according to the present invention.

1,1,1,2-tetrafluoroethane (1,1,1,2) by two-step reaction using trichloroethylene (hereinafter abbreviated as TCE) and hydrogen fluoride (HF) as raw materials -tetrafluoroethane, hereinafter abbreviated as HFC-134a).

As chlorofluorocarbons (CFCs), such as dichlorodifluoroethane (CFC-12 or R-12), have been identified as chemicals that destroy ozone in the stratosphere, development of materials to replace them has been called for. HFC-134a Is a representative CFC substitute with no ozone depleting capacity. HFC-134a can be manufactured by various methods depending on the starting materials, and it is known to use HF and TCE as raw materials. In addition to TCE, perchlorethylene, dichloroethylene, tetrachloroethane or intermediates thereof may be used, but a method of using TCE as a raw material is industrially promising.

The reaction of TCE with hydrogen fluoride can produce HFC-134a in a one-step reaction, but the method (UK Patent No. 1,589,924) has a problem that the yield of HFC-134a is very low. In order to improve this, by reacting TCE with hydrogen fluoride, the intermediate 1,1,1-trifluoro-2-chloroethane (1,1,1-trifluoro-2-chloro-ethane) And HFC-134a is prepared by the following reaction 2 by reacting the same with hydrogen fluoride.

In the reaction, chromium-based catalysts such as chromium fluoride (CrF ₃ ) catalysts or chromium fluoride (Cr ₂ O _x F _y ) catalysts calcined and fluorinated with chromium hydroxide, chromium oxide, and chromium chloride are used. In addition, magnesium or alumina in which metal components are added or fluorinated may be used as a carrier.

The method of performing such a two-step reaction in the same reaction zone (WO 90/08755, JP4-503215, JP3-48632) has a problem in that the activity of the catalyst is sharply lowered and the reaction temperature is high, resulting in many side reactions. In addition, if oxygen is continuously added to maintain the activity of the catalyst, as in the method proposed in WO 90/08755, water is generated, which causes serious corrosion of the device. Accordingly, a method of performing the above two-stage reaction in two reactors having different reaction conditions has been proposed. The reaction conditions may vary depending on the catalyst used, but in the production reaction of HCFC-133a which is reaction 1, the reaction temperature is maintained at 200 ° C-300 ° C, more preferably 250 ° C-300 ° C. When the reaction temperature is 350 ° C. or higher, deactivation of the catalyst and side reactions are promoted. In addition, since HCFC-133a reaction generates a large amount of heat of reaction (about 30 kcal / mol), hydrogen fluoride is used as a diluent several times per mole of TCE supplied to the reactor, and HCFC-133a, a product, may be used as a diluent gas. In HCFC-134a reaction of reaction 2, the reaction temperature was maintained at 300 ° C-400 ° C, more preferably 350 ° C-380 ° C, and the molar ratio of HF to HCFC-133a was about 2-10.

Various reactor arrangement methods and recovery and circulation methods of unreacted materials have been proposed to effectively carry out the two-step reaction. In EP449614A2, the HCFC-133a production reaction and the HFC-134a production reaction were arranged in sequence, and the unreacted reaction was recovered to circulate with the HCFC-133a production reactor. In this method, there is a problem that HCl, a by-product generated in the HCFC-133a production reaction, is introduced into the HFC-134a production reaction to promote a reverse reaction. The order of reactor arrangements were changed (EP 499617A2 and EP 446869A1) for higher yield in HFC-134a production. First, HCFC-133a was reacted with excess hydrogen fluoride to prepare HFC-134a by reaction 2 in a HFC-134a preparative reactor, and then HCFC- was arranged in series by mixing TCE with an unreacted hydrogen fluoride reaction product. Preparation of 133a It is a method of manufacturing HCFC-133a by reaction 1 in a reactor. This method involves separating HFC-134a and hydrogen chloride from the reaction mixture and then circulating the remaining unreacted mixture of HCFC-133a and hydrogen fluoride to the HFC-134a reactor. Have the same steps. In this method, however, the two reaction temperatures are connected in series to different reactors, so the reaction product mixture of the previous reactor must be heated or cooled to adjust for the next reaction. In addition, HCl, a byproduct produced in the previous reactor, is directly injected into the rear reactor, which has a problem of affecting the reaction equilibrium.

In order to improve the problem of the serial arrangement, two reactors are arranged in parallel to adjust the reaction temperature and maintain a separate reaction system (JP 5-279276, Korean Patent Publication No. 94-5530 and Korean Patent Publication No. 94 -5532) is also shown. In the parallel arrangement method presented here, the mixture produced in two reactors is separated in the same distillation column (one or two or more distillation columns), and the unreacted material is recycled to the two reactors. This parallel arrangement method is composed of the same steps as in FIG. When separating unreacted materials, one is composed of a mixture of HCFC-133a and hydrogen fluoride, the other is mostly hydrogen fluoride, and the unreacted materials mixed with HCFC-133a are HFC-134a preparation reactors. Unreacted materials, mostly hydrogen, are recycled to the HCFC-133a reactor. It is practical to obtain a mixture of HCFC-133a and HF having a certain composition by the side-cup of the distillation column since it must be maintained in a raw material composition (molar ratio of HCFC-133a to HF) suitable for the reaction conditions of the mixture circulated to the HFC-134a manufacturing reactor. As it is very difficult to maintain a constant composition, a separate distillation column must be used. In addition, there is a problem in that the composition of the circulating HCFC-133a and HF is continuously analyzed to replenish the amount of HF necessary to maintain a composition suitable for the reaction, and then introduced into the HFC-134a manufacturing reactor. Method of separating HFC-134a reaction product into distillation column (HCl, HFC-134a) and unreacted product (HCFC-133a, HF) to circulate only unreacted product to HFC-134a production reactor (EP 554165, Korean Patent Publication 93-16380) has been proposed, but this method adds oxygen and predicts the problem of water generation.

In the present invention, two HCl distillation columns are used, and an azeotropic mixture of HCFC-133a and HF is formed as an upper effluent of the first HCl distillation column, and thus, reactors having different reaction temperatures are arranged in series. The need for a temperature control system in between, ② by-products that may affect the reaction are introduced into the next reactor, and ③ the composition of the reactants cannot be controlled in each of the two reactors. At the same time, it is possible to easily control the composition of the raw materials supplied to the two reactors, which is difficult in the existing parallel arrangement method, to complete the production method of the present invention, which can obtain HFC-134a with high yield.

Accordingly, an object of the present invention is to prepare 1,1,1-trifluoro-2-chloroethane using trichloroethylene and hydrogen fluoride as raw materials under a chromium-based catalyst, and to obtain trifluorouro-2-chloroethane. In the method for producing 1,1,1,2-tetrafluoroethane by reacting with hydrogen fluoride, it is to provide a method for preparing 1,1,1,2-tetrafluoroethane comprising the following steps: ( A) The raw material trichloroethylene and the fluorine water reactor were supplied to a reactor for producing 1,1,1-trifluoro-2-chloroethane and reacted at 200-300 ° C. or higher at atmospheric pressure, and (b) 1,1,1-tri The product mixture of the reactor for producing fluoro-2-chloroethane was fed to the first HCl distillation column, and the azeotrope of the product 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride and hydrogen chloride at an operating pressure of normal pressure or higher. Separate the upper effluent consisting of and the unreacted hydrogen fluoride into the lower effluent, ( The upper effluent of the first HCl distillation column is fed to the second HCl distillation column, and all of the lower effluent of the first HCl distillation column is circulated to the reactor for preparing 1,1,1-trifluoro-2-chloroethane. ), The mixture of 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride was separated as a lower effluent of the second distillation column, and introduced into a reactor for preparing 1,1,1,2-tetrafluoroethane. React 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride at 300-400 ° C or above at atmospheric pressure, and (e) step (d) together with the top effluent of the first HCl distillation column of step (c). The product containing 1,1,1,2-tetrafluoroethane produced in the above was supplied to a second HCl distillation column, and (f) hydrogen chloride as a byproduct was separated from the second HCl distillation column operated at atmospheric pressure. 1,1,1,2-tetrafluoroethane was separated, and a mixture of unreacted 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride was all 1, Preparation of 1,1,2-tetrafluoroethane Circulating in a reactor.

The reactor used in the present invention may be any type of reactor, but in the present invention, since the reaction is a gas-solid contact reaction, a conventional single or multi-tube fixed bed reactor or a fluidized bed and mobile bed reactor may be used.

Another object of the present invention is to continuously supply only trichloroethylene and hydrogen fluoride to the reaction of the production of 1,1,1-trifluoro-2-chloroethane in the step (a) and 1,1, It is to provide a method for continuously supplying only 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride to 1,2-tetrafluoroethane production reaction.

Another object of the present invention is to adjust the operating pressure of the first HCl distillation column in the step (b) above the normal pressure and the amount of hydrogen fluoride 1,1,1-trifluoro-2-chloroethane contained in the upper effluent It is to provide a method of controlling the molar ratio to the molar ratio and the amount used in the 1,1,1,2-tetrafluoroethane manufacturing process.

The construction of the reaction process according to the invention can be shown as in the step of FIG. In the present invention, both the raw material HF and TCE are supplied to the HCFC-133a production reactor, and the reaction product mixture of the HCFC-133a production reactor is separated into the upper effluent and the lower effluent in the first HCl distillation column. The top effluent contains HCl and HCFC-133a and HF and the bottom effluent consists of HF. The upper effluent contains all HCl and HCFC-133a produced in the reaction and includes HF having an azeotropic composition with HCFC-133a. The HF separated into the bottom effluent is circulated to the HCFC-133a production reactor and the top effluent is sent to the second HCl distillation column. In the upper effluent of the first HCl distillation column, HCFC-133a and HF form an azeotrope and the composition can vary depending on the operating conditions (pressure) of the column and has a molar ratio of approximately one to one. Since this composition is the theoretical composition required for the production reaction of HFC-134a (Scheme 2), this property can be used to provide a method of separating the two reactions and controlling the composition of the raw materials supplied to each.

The azeotropic mixture composition of HCFC-133a and HF binary system was confirmed as shown in Table 1 by experiment. That is, the azeotropic composition changes according to temperature or pressure change, and the molar ratio of HF / HCFC-133a is about 1.0-1.5. Since the equivalent ratio of HCFC-133a and HF is 1 to 1 in the production reaction of HFC-134a (Scheme 2), the upper effluent of the first HCl distillation column is considered in consideration of the amount of HF lost (e.g., an azeotrope with the product HFC-134a). Adding water to the HFC-134a reaction process can separate the two reaction processes.

The second HCl distillation column is supplied with an upper effluent of the first HCl distillation column and a reaction product for preparing HFC-134a, and its composition may include HCl, HFC-134a, HCFC-133a, and HF as a main component, and may include a side reaction product. HCl and HFC-134a are separated into products, HCFC-133a and HF are separated into unreacted materials, and all unreacted materials are circulated in the HFC-134a manufacturing reactor. Since HFC-134a and HF consumed in the HFC-134a manufacturing reactor are supplemented and supplied from the first HCl distillation column, the HCFC-133a / HF mixture circulated to the HFC-134a manufacturing reactor has a constant composition without additional control. Will be maintained. When a change in composition due to side reaction is expected in the steady state HFC-134a production reaction or when HF is lost in the reaction process, the HF amount may be controlled by adjusting the operating conditions of the first HCl distillation column.

The method of the present invention is described in more detail as follows.

The raw materials TCE and HF are fed to the HCFC-133a reactor, and the reaction products are separated in the first HCl distillation column, and the upper effluent HCl and HCFC-133a and HF are sent to the second HCl distillation column, and the lower effluent, HF is HFC-133a reactor. Circulate At this time, the amount and molar ratio of HCFC-133a and HF in the upper effluent should be the amount and molar ratio required for the production reaction of HFC-134a. The reaction product HFC-134a prepared together with the top effluent of the first HCl distillation column is introduced into a second HCl distillation column to separate the product and the unreacted product. In order to separate HCl, HFC-134a and the unreacted product, HCl and HFC-134a were separated with the upper part of the second HCl distillation column, and HCFC-133a and HF, which were not reacted with the lower part, were separated. The HFC-134a may be separated or alternatively, only HCl of the second HCl distillation column is separated and the remainder is separated, which is then distilled in a separate distillation column to separate HFC-134a at the top and the unreacted HCFC-133a at the bottom. Separation of and HF can be used. The unreacted mixture from which HCl and HFC-134a have been removed is circulated to the HFC-134a preparation reactor. Since HFC-134a and HF form an azeotropic mixture, about 0.1 to 0.15 moles of HF per mole of HFC-134a flow out of the separation process as an azeotropic mixture, depending on the operating conditions of the distillation process. Therefore, the required amount of HF must be replenished in the first HCl distillation column. HF leaked from the separation process may be recovered and supplied to the HCFC-133a reactor or circulated to the HFC-134a reactor.

The reaction conditions of the reactor may vary depending on the catalyst used. HCFC-133a reaction conditions generally have a molar ratio of HF / TCE of about 10-50 and a reaction rate of at least 95% at 250 ° C-300 ° C. The raw materials TCE and HF are supplied in consideration of the theoretical equivalent (HF / TCE: molar ratio 4/1) and reaction rate required for the overall reaction (preparation of HCFC-133a and HFC-134a) and the amount of HF lost in the HFC-134a separation process. By recovering and circulating the unreacted HF and adding the HF and TCE used in the reaction, the composition of the raw material fed to the HCFC-133a manufacturing reaction can be kept constant. In addition, since the HCFC-133a and the required amount of HF are replenished at the top of the first HCl distillation column, the composition of HCFC-133a and HF is maintained without additional addition of the reactants in the HFC-134a production reactor. That is, HCFC-133a production reaction requires only HF, TCE and HF recovered from the bottom of the first HCl distillation column, and HFC-134a production reaction by simply circulating the HCFC-133a and HF mixture recovered as unreacted materials. The composition of the raw material required for the reaction can be maintained.

When explaining the present invention as an example as follows. The following examples are intended to illustrate the invention and do not limit the scope of the invention.

The HCFC-133a reactor for the embodiment of the present invention used an Inconel 1.5 liter single tube reactor and 1.4 kg of chromium-based catalyst fluorinated by adding magnesium. As a HFC-134a reactor, an Inconel 5 liter single tube reactor was used, and 4.8 kg of the same chromium-based catalyst was used. The reactor outer wall was heated and insulated with an electric heater to maintain the temperature of the reactor. For the first HCl distillation column and the second HCl distillation column, a packed column having a diameter of 2 inches and a height of 6 meters was used, and the filling was used as a 1/4 inch lashing ring.

Example 1

TCE 315.6g / hr and HF 1440g / hr was heated to 230 ℃ through a vaporizer was added to the HCFC-133a production reactor. The reaction pressure was maintained at 11 atmospheres and the reaction temperature was raised to 293 ℃. The conversion of TCE was at least 98% and the reaction product mixture was charged to the first HCl distillation column. The ratio of HCFC-133a and HF flowing out to the top was controlled by changing the operating conditions of the distillation column. As an example, the pressure was 7.8 atm and the temperature of the reboiler was maintained at 88 ° C. when the temperature of the reactor of the first distillation column was maintained at 40 ° C. When the gaseous effluent was obtained at a flow rate of 508 g / hr at the top of the distillation column, the composition was 474 mol /% HCl, 23.7 mol /% HCFC-133a, and 28.9 mol /% HF. All HCl and HCFC-133a produced were separated into the upper effluent and 1.22 moles of HF per 1 mole of HCFC-133a flowed out together. When the operating pressure of the first HCl distillation column was 4.7 atm, the temperature of the reboiler was 68 ° C. The composition was 46.2 mol% HCl and 23.1 mol% HCFC-133a when gaseous effluent was obtained at a flow rate of 513 g / hr at the top of the distillation column. All HCl and HCFC-133a produced were separated into the upper effluent and 1.33 moles of HF per 1 mole of HCFC-133a flowed out together. When the operating pressure of the first HCl distillation column was 10.5 atm, the temperature of the reboiler was 100 ° C., and the composition was obtained with 49 mol% HCl and 24 mol% HCFC-133a when obtaining gaseous effluent at a flow rate of 503 g / hr at the top of the distillation column. And HF became 27 mol%. All the resulting HCl and HCFC-133a were separated into the upper effluent and 1.05 moles of HF per 1 mole of HCFC-133a flowed out. Thus, by adjusting the operating conditions (pressure or temperature) of the first HCl distillation column, it was possible to control the molar ratio of HCFC-133a and HF, and this composition maintained the expected composition in the azeotropic mixture and the HCFC-133a required in the HFC-134a manufacturing reaction. And the composition ratio of HF. The reboiler of the first HCl distillation column contained a small amount of unreacted TCE in addition to HF, which was reused as a raw material without purification.

Example 2

The mixture (2620 g / hr) having a molar ratio of HCFC-133a and HF of 1 to 8 (2620 g / hr) was vaporized and heated to 380 ° C., and then supplied to a HFC-134a reactor. When the reaction temperature was maintained at 380 ° C. and the reaction pressure was maintained at 8 atmospheres, the reaction rate of HCFC-133a was 24.5% on average and the selectivity of HFC-134a was 98.2% or more. The HCl / HCFC-133a / HF mixture (508 g / hr) and the HFC-134a preparation reaction product (2620 g / hr) flowing out of the upper portion of the first HCl distillation column operated at 7.8 atmospheres were introduced into a second HCl distillation column, followed by a second HCl. The top temperature of the distillation column was maintained at -5 ° C. The pressure of the second HCl distillation column was 6 atm and the temperature of the reboiler was maintained at 58 ℃. When separating all HCl and HFC-134a to the top of the second HCl distillation column, about 0.22 moles of HF per mole of HFC-134a formed an azeotrope and flowed out together, and the composition of the unreacted product exiting the reboiler was HF / HCFC-133a. The molar ratio was automatically adjusted between 7.9-8.1. HCl was removed from the upper oil mixture (HCl, HFC-134a, HF and other by-products) of the second HCl distillation column, and then increased and purified to obtain 200 g / hr of HFC-134a.

Claims (3)

Under the chromium-based catalyst, 1,1,1-trifluoro-2-chloroethane was prepared using trichloroethylene and hydrogen fluoride as raw materials, and the trifluoro-2-chloroethane and hydrogen fluoride were reacted to obtain 1,1,1-trifluoro-2-chloroethane. A method for producing 1,1,2-tetrafluoroethane, the method of producing 1,1,1,2-tetrafluoroethane in a parallel reactor configuration consisting of the following steps: (A) Raw material trichloroethylene and Hydrogen fluoride was supplied to a reactor for producing 1,1,1-trifluoro-2-chloroethane and reacted at 200-300 ° C. or higher at atmospheric pressure, and (b) 1,1,1-trifluoro-2-chloroethane The product mixture of the production reactor was fed to the first HCl distillation column, and the upper effluent consisting of azeotrope of 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride and hydrogen chloride and hydrogen chloride at an operating pressure of atmospheric pressure or higher and The reactant hydrogen fluoride is separated into the bottoms effluent and (c) the phase of the first HCl distillation column. The effluent is fed to the second HCl distillation column and the bottom effluent is all circulated to the reactor for the preparation of 1,1,1-trifluoro-2-chloroethane, and (d) 1,1, A mixture of 1,1-trifluoro-2-chloroethane and hydrogen fluoride was separated and supplied to a reactor for producing 1,1,1,2-tetrafluoroethane, and the mixture was subjected to 1,1, at 300-400 ° C. or higher at atmospheric pressure. 1-trifluoro-2-chloroethane and hydrogen fluoride are reacted, and (e) 1,1,1,2- produced in step (d) together with the top effluent of the first HCl distillation column of step (c). The product containing tetrafluoroethane was fed to a second HCl distillation column, and (f) hydrogen chloride as a by-product was separated from the second HCl distillation column operated above atmospheric pressure, and then the desired product was 1,1,1,2-tetrafluoro. The ethane was separated and an unreacted mixture of 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride was added to the mixture of 1,1,1,2-tetrafluoroethane. Circulating in the reactor. The hydrogen fluoride / 1,1,1-trifluoro-2-chloroethane contained in the upper effluent according to claim 1, wherein the operating pressure of the first HCl distillation column is adjusted to 2.5 kg / cm 2 or more and 10 kg / cm 2 or less. To control the molar ratio. The process according to claim 2, wherein the molar ratio of hydrogen fluoride / 1,1,1-trifluoro-2-chloroethane is 1.0 or more and 1.5 or less.