KR100276377B1 - Method for the preparation of 1,1,1-trifluoroethane - Google Patents

Abstract

The present invention is a method for producing 1,1,1-trifluoroethane, which contaminates a mixture of 1-fluoro-1,1-dichloroethane and 1,1-difluoro 1-chloroethane and hydrofluoric anhydride. In the presence of an antimony catalyst, the initial catalyst input was 3-7 mol% based on the mixture of 1-fluoro-1,1-dichloroethane and 1,1-difluoro-1-chloroethane, and the pressure was 11-12 Kg / Cm ² · G, It relates to a method of continuously producing 1,1,1-trifluoroethane by reacting at a temperature of 30 to 50 ° C.

The method of the present invention not only produces very little by-products but also 1-fluoro-1,1- as compared to the method of preparing 1,1,1-trifluoroethane directly from 1,1,1-trichloroethane. The process can be simplified since the separation process of the mixture does not have to go through a method of using dichloroethane or 1,1-difluoro 1-chloroethane as a raw material, respectively.

Description

Method for preparing 1,1,1-trifluoroethane

The present invention relates to 1-fluoro-1,1-dichloroethane (1-Fluoro-1,1-Dichloroethane-hereinafter referred to as HCFC-141b) and 1,1, -difluoro-1-chloroethane (1,1 A liquid mixture of -Difluoro-1-Chloroethane-hereinafter referred to as HCFC-141b) and hydrofluoric anhydride (hereinafter referred to as HF) were subjected to liquid phase reaction in the presence of an anticontaminated antimony (hereinafter referred to as SbCl ₅ ) catalyst to give 1,1,1-tri A method for producing fluoroethane (hereinafter referred to as HFC-143a).

HCFC-141b and HCFC-142b have lower ozone depletion potential (ODP) than CFCs, but they also contain chlorine molecules, which is a transitional product to replace CFCs. Production facilities are in place.

On the other hand, HFC-143a has a boiling point of -48 ° C, ODP "0" and volume cooling is larger than HCFC-22, and the exhaust temperature is low, so it is already recognized as a substitute for HCFC 22.

HFC-143a is prepared by reacting hydrogen fluoride with 1,1,1-trichloroethane (CH ₃ CCl ₃ ) or vinylidene chloride (CH ₂ CCl ₂ ) by gas phase or liquid phase reaction in the presence of a catalyst or by HCFC-141b. These compounds are separated and purified from a mixture of HCFC-141b and HCFC-142b obtained at the time, and are prepared using HCFC-141b or HCFC-142b as independent raw materials.

The reaction mechanism can be represented by the following reaction formula.

International Publication WO / 9605156A ₁ discloses a method for preparing HFC-143a by liquid phase reaction of 1,1,1-trichloroethane (CH ₃ CCl ₃ ) with HF using an antimony catalyst (SbCl ₅ ). )

The reaction conditions are 15~70 ℃ reaction temperature, reaction pressure 15~300psig, HF / CH ₃ CCl ₃ molar ratio of 3: 1 to 3.6: 1, the amount of catalyst is 5~80wt% by weight ratio of the reaction solution.

Chinese Patent Application Publication No. CH / 1106779A discloses a method for preparing HFC-143a by liquid phase reaction between HCFC-141b and HF using SbCl ₅ , SnCl ₄ , TiCl ₄ , and SO ₃ catalysts dissolved in a solvent.

This reaction condition is performed by adding a specific solvent such as trichlorotrifluoroethane (hereinafter referred to as CFC-113) or dichlorotetrafluoroethane (hereinafter referred to as CFC-114) as a solvent for catalytic dilution to make a reaction solution. The amount of the catalyst was maintained at 5 to 30 wt% with respect to the liquid, the molar ratio of HF / HCFC-141b was 2.0 to 2.5, the reaction temperature was 0 to 100 ° C, and the reaction pressure was 0.1 to 1.5 MPa.

EP-0819668A ₁ describes a method for preparing HFC-143a by reacting HCFC-142b with HF in the liquid phase in the presence of a catalyst (SbCl ₅ ). Under these reaction conditions, the amount of catalyst was 0.01 to 10% as Sb with respect to HCFC-142b, the reaction pressure was 5 to 30 Bar, the reaction temperature was 0 to 120 deg. C, and the amount of Cl ₂ was 0.025 to 0.01 mol% with respect to HCFC-142b.

The method disclosed in WO / 9605156A ₁ is a process for preparing HFC-143a using CH ₃ CCl ₃ as a starting material in the presence of SbCl ₅ , and the reaction step is complicated in three steps, and also CH ₃ CCl ₃ and SbCl ₅ The catalyst life is accelerated by the reaction of F-121 (CHCl ₂ CCl ₂ F), F-120 (CH ₂ Cl ₂ CCl ₃ ), due to the side reaction of CH ₃ CCl ₃ and SbCl ₅ . F-122 (CHCl ₂ CClF ₂ ), F-130 (CH ₂ ClCCl ₃ ) series F-131 (CH ₂ ClCCl ₂ F), F-132 (CH ₂ ClCClF ₂ ), F-1120 (CHClCCl ₂ ) series Phosphorus F-1120 is generated, such as problems are not commercially useful.

In addition, Chinese Patent Publication No. CN / 1106779A uses HCFC-141b as a starting material and reacts these substances with HF when they are reacted with CFC-113 and CFC-114, which are substances regulated by the Montreal Protocol as a diluent additive for catalysts. The reaction gives rise to chloropentafluoroethane (hereinafter referred to as CFC-115) and other double-bonded materials, resulting in by-product separation problems and recovery and separation of diluent additives. In particular, CFC-115 has a boiling point similar to that of HFC-143a, so that their purification is very difficult.

In European Patent Publication EP / 0819668A ₁ , HCFC-142b is used as a starting material and a large amount of high-boiling materials of F-120 series, F-130 series and F-1120 series are produced by chlorination, dehydrogenation and dehydrogenation during long-term reaction. It is described as being produced and continuously accumulating in the reactor, which will cause many problems such as the addition of a separation process to this in the commercialization process and the treatment of these high boiling materials. In addition, the production of HFC-143a is not useful due to the high conversion and high selectivity of raw materials due to the large amount of by-products produced.

An object of the present invention is a method of producing a large amount of HFC-143a with little production of by-products in a simple process using a mixture of HCFC-141b and HCFC-142b obtained in the process for producing HCFC-141b from trichloroethane. To provide.

1 is a view showing a manufacturing process of HFC-143a according to the present invention.

* Description of the symbols for the main parts of the drawings *

R-1: reactor, V-1: hydrogen chloride reservoir,

P-1: pump, R-2, R-3: reboiler,

E-1, E-2, E-3: condenser, C-1, C-2, C-3, C-4: package column

Currently, most commercial plants use 1,1,1-trichloroethane (CH ₃ CCl ₃ ) or vinylidene chloride (CH ₂ = CCl ₂ ) to prepare HCFC-141b. In this case, HCFC-141b and HCFC-142b are generated simultaneously. In our process, HCFC-141b and HCFC-142b are produced at an average ratio of 90:10 when HCFC-141b is manufactured from CH ₃ CCl ₃ as a raw material.

The characteristics of the present invention is energy saving by proceeding the liquid phase reaction at low temperature in the presence of SbCl ₅ catalyst by using the HCFC-141b / 142b mixture of a certain composition ratio as a raw material in the HCFC-141b manufacturing process of the company that does not undergo a separation process as a raw material Of course, there are few by-products of side reactions, the process efficiency is excellent, and the process can be relatively simplified to mass-produce HFC-143a.

In particular, since the HCFC-141b / 142b mixture in the HCFC-141b manufacturing process is used as the raw material, the mixture is not separated from the mixture as using the HCFC-141b and HCFC-142b as the raw materials. The manufacturing cost is reduced, and there is an economical advantage of reducing the manufacturing cost of HFC-143a. More importantly, by using the HCFC-141b / 142b mixture, the catalyst SbCl ₅ activity is better maintained than when using HCFC-141b and HCFC-142b as raw materials. By-products such as olefins by dehydrogenation and dehydrochlorination can be minimized, and in particular, by-products of F-120 series and F-130 series can be minimized. In addition, as mentioned above, the SbCl ₅ catalyst activity is also excellent in maintaining a small amount of catalyst.

In addition, the present invention is initially used by mixing the catalyst and the raw material HCFC-141b / 142b in a constant ratio in the reactor by using a separate solvent as in other patents, so that by-products that may be generated by the reaction with the solvent Formation can be suppressed, whereby the reaction selectivity can be increased to increase the conversion rate of the raw materials. In addition, the HCFC-141b / 142b mixture has better solubility with the catalyst SbCl ₅ than in each case.

Since the process of the present invention is a continuous process, the unreacted HF and HCFC-141b / 142b can be separated and recovered from the separation column and recycled to the reactor so that a very high conversion rate of the raw material (95 wt% or more) and a very high selectivity (99.9 wt % Or more) to provide a method for producing HFC-143a.

The reason why the activity of the catalyst is maintained well in the method of the present invention is that when the HCFC-141b is used as the sole raw material, the catalyst SbCl ₅ reacts with the HCFC-141b to oxidize the catalyst trivalently, resulting in a rapid decrease in activity. , 1,1-trichloroethane and the like are produced, which also react with the catalyst to lower the activity of the catalyst. In general, the chlorine is supplied to maintain the activity of the catalyst. In this case, an excessive amount of the chlorination is required to increase the activity of the catalyst. Therefore, side reactions due to chlorination promote the formation of by-products of the F-120 and F-130 series. However, when the HCFC-141b / 142b mixed solution is used as a raw material as in the present invention, the conversion of HCFC-141b to HCFC-142b and the conversion of HCFC-142b to HFC-143a are simultaneously performed. This is because the decrease in activity can be reduced and the catalytic activity can be maintained at 50 to 90% by adding a small amount of chlorine during the reaction.

When HCFC-142b is used as a raw material, the reaction rate to HFC-143a is so fast that tar of the reactants is promoted.

The reason for not having to use a separate solvent in the present invention is that the HCFC-141b / 142b mixed solution and the catalyst SbCl ₅ are both liquid and uniformly dissolved well when mixed to form a homogeneous phase, and the catalyst by reacting HCFC-141b with the catalyst This is because the decrease in activity is reduced by using the HCFC-141b / 142b mixture as a raw material, and thus a separate solvent is not required to maintain the catalyst concentration.

The major difference between the method disclosed in WO / 9605156A ₁ , that is, the method of preparing HFC-143a using CH ₃ CCl ₃ as a starting material and the present invention is that the reaction step is complicated in three steps and ₃ CCl _3, and is accelerated tar catalyst upset shortened catalyst life by the reaction of SbCl ₅ and CH ₃ CCl _3, and due to the side reaction of _{SbCl 5 F-120 (CH 2} Cl 2 CCl 3) sequence of F-121 (CHCl ₂ CCl ₂ F), F-122 (CHCl ₂ CClF ₂ ), F-130 (CH ₂ ClCCl ₃ ) series F-131 (CH ₂ ClCCl ₂ F), F-132 (CH ₂ ClCClF ₂ ), F- 1120 (CHClCCl ₂ ) series of F-1120, etc. are generated, but the method of the present invention is simple in the process, almost no by-products are produced, and the activity of the SbCl ₅ catalyst is good, so that a small amount of catalyst is used. It is also possible.

Specific reaction conditions of the present invention are as follows.

Gas phase effluent is used to recover the product from the top of the reactor by liquid phase reaction of HF and HCFC-141b / 142b mixture in the presence of antimony (SbCl ₅ ) catalyst.

The pressure of the reaction system is selected from 11 to ¹² Kg / Cm ² · G.

○ The reaction temperature is selected at 30 to 50 ° C.

The feed ratio of the HF / HCFC-141b / 142b mixture is adjusted to 1.8 / 1 to 1.2 / 1 mole according to the composition ratio HCFC-141b / 142b = 90/10 to 10/90 of the organic mixture.

○ The raw material input method is to supply HCFC-141b / 142b mixture and HF in the liquid phase.

Recover the product from the top of the reactor, and remove the unreacted HF and HCFC-141b / 142b from the high boiling point separation tower and return to the reactor.

○ The amount of catalyst (SbCl ₅ ) is selected from the reaction mixture and the ratio, and the activity of the catalyst during the reaction is maintained at Sb ⁵⁺ / Sb ⁵⁺ + Sb ³⁺ : 50-90wt%. For this purpose, chlorine (Cl ₂ ) is supplied.

○ The said manufacturing method is performed continuously.

The present invention is accomplished using conventional equipment known in the art as shown in the figures.

Hereinafter, the content of the present invention will be described with reference to specific examples.

However, the content of the present invention is not limited only to the examples.

Example 1.

39.8 Kg of SbCl ₅ and 200 Kg of HCFC-141b / 142b (80/20 wt%) are initially supplied to the reactor R-1 (volume: 500 L). This corresponds to 7 mol% of HCFC-141b / 142b and the mixed solution as SbCl ₅ . Heat was slowly added thereto, and the reactor temperature was raised to 40 ° C. to continuously react with HF and HCFC-141b / 142b at the same time to maintain the reaction pressure at 11 to 12 Kg / Cm ² G.

At this time, the feed molar ratio of the raw material is supplied while maintaining the reactor level (HF / HCFC-141b + 141b = 1.9 / 1). In order to maintain the catalyst (SbCl ₅ ) activity, the catalyst during the reaction is analyzed and chlorine (Cl ₂ ) gas is supplied to maintain the catalytic activity so that the Sb 5 valent component is 50 to 90 wt%.

Reactor internal temperature was 40 degreeC, and the upper reflux temperature of reflux column (C-1) was maintained at 0-5 degreeC. The produced gas is introduced from the top of the reflux condenser (E-1) to the hydrogen chloride separation column (C-2) while maintaining the pressure in the system at 11 to 12 Kg / Cm ² G. At this time, the hydrogen chloride gas is introduced into the hydrogen chloride absorption tower (C-3) is absorbed in water and stored as 35% hydrogen chloride solution.

In addition, the organics flowing out of the reboiler (R-2) are recovered through the fern separation tower (C-4), and the unreacted HF and the fern are recovered and circulated in the reactor (R-1) to be reacted again to increase the conversion rate of the raw materials. give.

The spilled HFC-143a is sent to the product reservoir after alkali cleaning, drying, compression and condensation.

The results under the above conditions are as follows.

In the above experiments, even long-term continuous operation, the generation of other by-products such as ferns is little and the reaction proceeds well. In addition, the conversion rate of the raw material is more than 95wt%, and since most of the reaction organic matter leaving the reactor is HFC-143a (99.9wt%), there is an advantage that the process can be easily operated.

Example 2

It is executed in the same apparatus as in Example 1. The weight ratio of the organic substance mixture to be supplied is HCFC-141b: HCFC-142b = 50:50, the feed molar ratio of the raw material is HF / HCFC-141b + 142b = 1.6 / 1, and the other conditions are carried out under the same conditions as in Example 1.

The results under the above conditions are as follows.

Example 3

It is executed in the same apparatus as in Example 1. The weight ratio of the organic substance mixture to be supplied is HCFC-141b: HCFC-142b = 20:80, the feed molar ratio of the raw material was HF / HCFC-141b + 142b = 1.3 / 1, and the other conditions were carried out under the same conditions as in Example 1.

The results under the above conditions are as follows.

Comparative example

It is executed in the same apparatus as in Example 1. A catalyst amount of 89.4 kg (15 mol%) was supplied, the reaction temperature was 80 占 폚, and the other conditions were carried out under the same conditions as in Example 1.

The results under the above conditions are as follows.

Under the above experimental conditions, high temperature and excessive amount of catalyst proceed to tarry the catalyst inside the reactor, decrease the product selectivity due to the increase of fertilizer and other by-products, and accumulate fertilizer and other by-products in the reactor in a long continuous operation. There was a problem.

The method of the present invention has a very small amount of by-products as well as a very good activity of the catalyst compared to the conventional method for producing 1,1,1-trifluoroethane directly from 1,1,1-trichloroethane. In addition, the process can be simplified because the process does not require separation of the mixture rather than using 1-fluoro-1,1-dichloroethane or 1,1-difluoro 1-chloroethane as raw materials. Have

Claims (3)

In the process for producing 1,1,1-trifluoroethane, a mixture of 1-fluoro-1,1-dichloroethane and 1,1-difluoro 1-chloroethane and hydrofluoric anhydride are present in the presence of an antimony catalyst The initial catalyst input amount was 3-7 mol% based on 1-fluoro-1,1-dichloroethane and 1,1-difluoro-1-chloroethane mixture at a pressure of 11-12 Kg / Cm ² · G, and temperature of 30- A method of continuously producing 1,1,1-trifluoroethane by reacting at 50 ° C. The 1,1,1-trifluoro according to claim 1, wherein the weight ratio of the 1-fluoro-1,1-dichloroethane and 1,1-difluoro 1-chloroethane mixture is 90:10 to 10:90. Method for producing ethane. The method for producing 1,1,1-trifluoroethane according to claim 1, wherein chlorine is supplied to the reaction system to maintain the pentavalent antimony component in the reaction catalyst in the range of 50 to 90 wt%.