The way to obtain 1,1,1,2-tetrafluoroethane

 

(57) Abstract:

Usage: 1,1,1,2-Tetrafluoroethane is used as a solvent, as a refrigerant. Conditions of synthesis: the reaction of HF and trichloroethylene in the presence of a catalyst, resulting in a mixture containing 2-chloro-1,1,1-Cryptor-ethane and 1,1,1,2-Tetrafluoroethane, and optionally other organic by-products. The reaction proceeds in a single reaction zone by extraction 1,2,1,2-Tetrafluoroethane from a mixture and return to the recycling 2-2-chloro-1,1,1-triptorelin, and optionally, other organic by-products from the reaction mixture, together with trichloroethylene and HF. HF take in a molar ratio of 3 to 30 times the molar quantity of trichloroethylene, as the catalyst used is a salt of metal selected from chromium salts, cobalt salts on the media-aluminum fluoride, fluorinated aluminum oxide or coal. 1 C.p. f-crystals, 2 tab.

The invention relates to an improved method of producing 1,1,1,2-Tetrafluoroethane (HFC-134a) by catalytic reaction of trichloroethylene with HF, in which the reaction proceeds in a single reaction zone to return to the recycling of 2-chloro-1,1,1-triptorelin (HCFC-a) with trichloroethylene in the reaction zone.

Known UB>2Y is Br, Cl, F, and Y is chlorine, HF. The interaction is carried out in the vapor phase at elevated temperatures (300-400aboutC). As the catalyst used chromium oxide or which is at least partly is a basic chromium fluoride. HF is passed directly over the catalyst at a temperature within 100-275about[1]

Closest to the proposed method is a way to obtain 1,1,1,2-Tetrafluoroethane by reacting HF with trichloroethylene at an elevated temperature in the presence of catalyst 3-valent chromium compounds. The target product is obtained with a low output [2]

The aim of the invention is to increase the yield of the target product in the implementation process in the same reaction zone.

This goal is achieved by the fact that this method lies in the fact that conduct the interaction of HF with trichloroethylene at 300-425aboutIn the presence of a catalyst metal salt, with the formation of a mixture containing 2-chloro-1,1,1-trifluoroethane and 1,1,1,2-Tetrafluoroethane, and the reaction of lead in a single reaction zone, while extract 1,1,1,2-Tetrafluoroethane from the reaction mixture and recycle 2-chloro-1,1,1-trifluoroethane from the reaction mixture together with trichloroethylene is aftrican, with HF, adding advanced in a molar ratio of 3 to 30 times the molar quantity of trichloroethylene, using as a catalyst a salt of chromium, cobalt salts on the media-aluminum fluoride, fluorinated aluminum oxide or coal.

Moreover, the amount of metal in the calculation of the pure metal in the catalyst composition ranges from 0.02 to 50 wt. from the catalytic composition, and the reaction is carried out in the presence of oxygen.

Usually when using this catalyst composition, the higher the temperature, the greater the molar ratio HF/trichloroethylene, and the longer the duration of contact, the greater the degree of conversion in the fluorinated products and the more intensive is the formation of polyfluorinated products. During implementation of the invention can be achieved by a balance of these parameters, one against another, so that increases up to a maximum formation of CF3CH2F and decreases to a minimum the formation of more highly fluorinated CF3CHF2.

The reaction of trichloroethylene with HF may be carried out in any suitable reactor, including a reactor with a fixed catalyst bed and the reactor with a fluidized bed of sloreta hydrogen, such as alloy Inconel and alloy Hastelloy.

Pressure is not critical. Most suitably atmospheric and surfmaster pressure, and therefore, they are most preferred.

P R I m e R s. In the examples all parts are massive and all percentages are molar and all temperatures are in degrees Celsius unless otherwise stated. Ox all reactions used in industrial HF, containing only trace amounts of water.

The General procedure for fluorination.

Reactor (internal diameter of 12.7 mm, length 305 mm) loaded catalyst in amounts specified in the following examples, and placed in a sand bath. This bath is slowly heated to 400aboutWith the transmission of gaseous N2a flow rate of 50 cm3/min through the reactor to remove traces of water. The temperature is reduced to 200aboutWith and gaseous HF and N2(in a molar ratio of 1/4) are passed through the reactor, and the flow rate of N2decreases with time as long as the reactor will not be only pure HF. At this point, the temperature is gradually increased to 425aboutWith and is maintained at this level for 15-300 oresti flows adjusted to achieve the above molar ratio, and time of contact, as given in the examples.

A sample of the product leaving the reactor taken along the line of the stream for chromatographic analysis on a Hewlett Packard HP 5890 using the chromatographic column length (between 6.08 mm) and diameter (3.2 mm), filled with fully fluorinated polyester Krytox inert carrier and a helium flow of 35 cm3/min. Conditions in the chromatograph of the following: temperature 70aboutC for 3 min, followed programmed to increase the temperature to 180aboutWith heating rate of 6aboutC/min

P R I m e R 1. The fluorination of trichloroethylene recycle HCFC-a.

The fluorination is carried out with the use 19,0 g (30 ml) CoCl2/Al2O3(2% Co) as the initial mass of the catalyst. The molar ratio HF/a/trichloroethylene/ABOUT2is 10/1/0,2/0,2. The flow of the product resulting from the reaction of HF to HCFC-a, trichloroethylene and air formed over the catalyst at the time of contact with the catalyst for 20 s at 390aboutWith, and after 53 hours of work get the following results:

17.4% OF CF3CH2F (HFC-134a), 80.8% of CF3CH2Cl (HCFC-133a),

1.2% OF CF2=CHCl (FC-1122), 0,3% C
P R I m e R s 2-7. The fluorination of trichloroethylene recycle HCFC-133a.

Is the General procedure for fluorination using 21.1 g (30 ml) (CoCl2+ CrCl3) Al2O3(1% Co + 1% Cr) as the initial catalyst mass. The results of the reaction of HF with HCFC-a, and trichloroethylene, and HCFC-133a and with trichloroethylene and air formed over the catalyst at the time of the probe 20 with the table.1.

The molar ratio HF/133a/trichloroethylene/O2is 10/1/0,2/0 for examples 2-4, and is 10/1/0,2/0,2 for examples 5-7.

P R I m e R s 8-14. The fluorination of trichloroethylene recycle HCFC-a.

In the Inconel reactor load 31.0 g (30 ml) Cr2O3. The results of the reaction of HF with HFCF-a and oxygen, and HCFC-a and trichloroethylene and oxygen over the catalyst at the time of contact 20 seconds are given in table. 2. The molar ratio HF/133a/trichloroethylene/oxygen is 10/1/0/0,2 for comparative examples 8 and 9, and is 10/1/0,2/0,2 for examples 10-14. The comparison of these results with the results of examples 1 to 7 clearly show that the preferred catalyst that meets the invention has many advantages, one of which is that chem is cnyh products. Significant quantities of by-products are not formed when using the catalysts according to examples 1-7.

1. The WAY to OBTAIN 1,1,1,2-TETRAFLUOROETHANE by the reaction of HF with trichloroethylene at 300-425oIn the presence of a catalyst metal salt with the formation of a mixture containing 2-chloro-1,1,1-trifluoroethane and 1,1,1,2-Tetrafluoroethane, wherein the reaction of lead in a single reaction zone, while extract 1,1,1,2-Tetrafluoroethane from the reaction mixture and recycle 2-chloro-1,1,1-trifluoroethane from the reaction mixture together with trichloroethylene in the reaction zone in a molar amount at least equal to the molar quantity of the extracted 1,1,1,2-Tetrafluoroethane, with HF added additionally, in a molar ratio of 3 to 30 times the molar quantity of trichloroethylene, using as a catalyst a metal salt selected from the salts of chromium, cobalt salts on the media, the aluminum fluoride, fluorinated aluminum oxide or coal.

2. The method according to p. 1, characterized in that the amount of metal in the calculation of the pure metal in the catalytic composition is 0.02-50 wt. from the catalytic composition, and the reaction is carried out in the presence of oxygen.

 

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