Field of the invention
The present invention provides a process for the preparation of olefins.
Background of the invention
In recent years, 2,3,3,3-tetrafluoropropene (HFO-1234yf) has attracted attention as a new refrigerant to replace 1,1,1,2-tetrafluoroethane (HFC-134a) which is a greenhouse gas.
The U.S Patent No. 2,931,840 describes a process for the preparation of HFO-1234yf by heating and decomposing a mixture of methylchloride and chlorodifluoromethane or tetrafluoroethylene at a temperature of from 700 to 950°C by a common heating means such as an electric heater in a reactor.
The Japan Publication No. 2016-027004 describes a process for the preparation of HFO-1234yf by feeding heat source selected from steam, nitrogen or carbon dioxide into a reactor containing a mixture of methylchloride and tetrafluoroethylene at a temperature of from 400 to 870°C.
The present inventors have observed that upon feeding methylchloride and tetrafluoroethylene, pre-mixed or separately, into pre-heated reactor at 300°C to 700°C results in the formation of 2,3,3,3-tetrafluoropropene at high rate as compared to feeding heat source selected from steam, nitrogen or carbon dioxide into a reactor containing a mixture of methylchloride and tetrafluoroethylene at a similar temperature range.
The present inventors have further observed that feeding methylchloride and tetrafluoroethylene, pre-mixed or separately, into pre-heated reactor at 300°C to 700°C in the presence of initiator, for example, carbon tetrachloride,
3
hexachloroethane, trichloroacetylchloride, chloroform, phosegene, thionyl chloride, sulfonylchloride, trichloromethylbenzene, organic hypochlorites and inorganic hypochlorites or mixture thereof, results in better selectivity towards 2,3,3,3-tetrafluoropropene. This was primarily because the content of methane (R50) reduces drastically upon the use of aforementioned initiators.
Summary of the invention
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing methylchloride and tetrafluoroethylene, pre-mixed or added separately, in the reactor to obtain a mixture;
c) contacting step b) mixture with heat source to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing methylchloride and tetrafluoroethylene, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
c) contacting the step b) mixture with heat source in the presence of initiator to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing methylchloride, tetrafluoroethylene and initiator, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
4
b) providing the heat source in the reactor;
c) contacting the heat source and the step a) mixture to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing methylchloride, tetrafluoroethylene and initiator, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
c) contacting step b) mixture with heat source to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
Detailed description of the invention
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing methylchloride and tetrafluoroethylene, pre-mixed or added separately, in the reactor to obtain a mixture;
c) contacting step b) mixture with heat source to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing methylchloride and tetrafluoroethylene, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
5
c) contacting the step b) mixture with heat source in the presence of initiator to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing methylchloride, tetrafluoroethylene and initiator, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
b) providing the heat source in the reactor;
c) contacting the heat source and the step a) mixture to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The present invention provides a process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing methylchloride, tetrafluoroethylene and initiator, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
c) contacting step b) mixture with heat source to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
The heat source in a reactor is an electric heater itself and a like.
Further, the heat source is used to provide a temperature in range of 250oC to 700oC or used to provide a temperature to a mixture of methylchloride and tetrafluoroethylene in the range of 250oC to 700oC in the reactor, or both to obtain a mixture.
6
The methylchloride is continuously introduced in the electric furnace set at the furnace temperature of 250oC to 300oC, and methylchloride (R40) is heated at 300oC. The tetrafluoroethylene is continuously introduced into the tube in the electric furnace set at the furnace temperature of 300oC, and tetrafluoroethylene is preheated at 300oC. The initiator is continuously introduced into the tube in the electric furnace set at the furnace temperature of 300oC, and initiator is preheated at 300oC. These preheated material gas components (methylchloride, tetrafluoroethylene and initiator) are supplied to the reactor managed by the internal temperature.
The mixture of methyl chloride to tetrafluoroethylene is present in a molar ratio of 0.1:1 to 3:1.
The reaction may be carried out in batch mode or in continuous mode.
The initiator is selected from carbon tetrachloride, hexachloroethane, trichloroacetylchloride, chloroform, phosegene, thionyl chloride, sulfonylchloride, trichloromethylbenzene, organic hypochlorites and inorganic hypochlorites or mixture thereof.
The entire reaction temperature may range from about 300oC to about 700oC. The entire process for the preparation of 2,3,3,3-tetrafluoropropene may be carried out in the presence of nitrogen. The reaction mixture comprises 2,3,3,3-tetrafluoropropene, obtained by the present invention, is optionally, converted to anhydrous reaction mixture comprises 2,3,3,3-tetrafluoropropene.
The isolation of 2,3,3,3-tetrafluoropropene from the reaction mixture is carried out by any method known in the art, for example, by series of distillations, absorption and adsorption or mixture thereof.
7
Examples
Process for the preparation of 2,3,3,3-tetrafluoropropene
A mixture of tetrafluoroethylene and methylchloride in the molar ratio of 1:0.82 respectively is preheated and then superheated to 350oC and was fed to the Inconel reactor which pre-heated and maintained at 620oC by electrical heater.
Comparative results of with and without initiator on the yield of 2,3,3,3-tetrafluoropropene:
Initiator % (carbon tetrachloride) by mass of methylchloride
0
1.3 %
Temperature (oC)
620
620
Tetrafluoroethylene : methyl chloride (molar ratio)
1:0.82
1:0.83
Residence time (Seconds)
2.74
0.86
Initiator % (carbon tetrachloride)
0
1.3 %
Composition
methane
13.17 %
0.49 %
tetrafluoroethylene
20.16 %
9.90 %
trifluoromethane
0.25 %
1.07 %
vinylidenefluoride
1.63 %
2.23 %
trifluoroethyelene
0.16 %
0.30 %
difluoromethane
1.06 %
0.09 %
Hexafluoropropene
1.14 %
12.72 %
chlorodifluoromethane
4.13 %
2.15 %
2,3,3,3-tetrafluoropropene
3.95 %
15.62 %
octafluorocyclobutane
6.49 %
6.96 %
8
chlorofluoroethyelenes
3.21 %
4.20 %
methylchloride
33.64 %
25.93 %
chlorofluoroethanes
0.86 %
3.19 %
chlorofluoropropenes
5.48 %
1.83 %
chlorofluoropropanes
2.00 %
2.01%
Total tetrafluoroethyelene conversion
60 %
85 %
2,3,3,3-tetrafluoropropene Selectivity
12 %
25.5 %
Formation of methane in comparison to formation of 2,3,3,3-tetrafluoropropene
333%
3.13 %
Formation of vinylidenefluoride in comparison to formation of 2,3,3,3-tetrafluoropropene
41.2 %
14.2 %
Formation of octafluorocyclobutane in comparison to formation of 2,3,3,3-tetrafluoropropene
164 .3 %
44.5 %
Process for the preparation of 2,3,3,3-tetrafluoropropene:
A mixture of tetrafluoroethylene and methylchloride in the mol ratio of 1:1.16 respectively is preheated and then superheated to 350oC and was fed to the Inconel reactor which is maintained at 550oC by electrical heater.
Temperature
550oC
M.R (tetrafluoroethyelene: methylchloride )
1:1.16
Residence time (Seconds)
3.19
Initiator % (carbon tetrachloride) by mass of methylchloride
5
Composition
methane
0.02 %
tetrafluoroethyelene
20.44 %
9
trifluoromethane
0.06 %
vinylidenefluoride
0.77 %
trifluoroethyelene
0.06 %
difluoromethane
0.04 %
hexafluoropropene
3.10 %
chlorotrifluoroethyelene
0.07 %
chlorodifluoromethane
1.02 %
2,3,3,3-tetrafluoropropene
11.89 %
octafluorocyclobutane
2.23 %
chlorofluoroethyelenes
8.78 %
methylchloride
36.02 %
chlorofluoroethanes
0.96 %
chlorofluoropropenes
3.0 %
chlorofluoropropanes
3.05 %
tetrafluoroethyelene (TFE) Conversion
62 %
tetrafluoroethyelene (TFE) Selectivity
28.5 %
Formation of methane in comparison to formation of 2,3,3,3-tetrafluoropropene
0.17 %
Formation of vinylidenefluoride in comparison to formation of 2,3,3,3-tetrafluoropropene
6.48 %
Formation of Trifluoromethane in comparison to formation of 2,3,3,3-tetrafluoropropene
0.50 %
Formation of Difluoromethane in comparison to formation of 2,3,3,3-tetrafluoropropene
0.34 %
10
Formation of Octafluorocyclobutane in comparison to formation of 2,3,3,3-tetrafluoropropene
18.75%
Process for the preparation of 2,3,3,3-tetrafluoropropene:
Temperature
808
620
M.R (tetrafluoroethyelene : methyl chloride)
1:3
1:1.2
Residence time (Seconds)
2.19
2.53
Composition
methane
2.45%
5.15 %
tetrafluoroethyelene
7.72 %
25.28 %
trifluoromethane
1.71 %
0.17 %
vinylidenefluoride
13.89 %
1.18 %
trifluoroethyelene
0.724 %
0.16 %
difluoromethane
1.05 %
0.47 %
hexafluoropropene
1.97 %
0.48 %
chlorodifluoromethane
1.35 %
3.25 %
2,3,3,3-tetrafluoropropene
5.55 %
2.67 %
octafluorocyclobutane
0.67 %
9.11 %
methylchloride
59.52 %
46.52 %
Formation of vinylidenefluoride in comparison to formation of 2,3,3,3-tetrafluoropropene
250 %
44 %
Formation of Trifluoromethane in comparison to formation of 2,3,3,3-tetrafluoropropene
31 %
6.4 %
11
Formation of Difluoromethane in comparison to formation of 2,3,3,3-tetrafluoropropene
18.9 %
17.6 %
The isolation of 2,3,3,3-tetrafluoropropene from the reaction mixture/composition, obtained by the process of present invention, is carried out by any method known in the art, for example, by series of distillations, absorption and adsorption or mixture thereof.
The present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.

WE CLAIM:
1. A process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing a mixture of methylchloride and tetrafluoroethylene, said mixture is either premixed or added separately, in the reactor to obtain a mixture;
c) contacting the step b) mixture with heat source in the presence of initiator to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
2. A process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a mixture of methylchloride , tetrafluoroethylene and initiator, said mixture is either premixed or added separately, in a reactor to obtain a mixture;
b) providing the heat source in the reactor;
c) contacting the heat source and the step a) mixture to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
3. A process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
b) providing a mixture of methylchloride, tetrafluoroethylene and initiator, said mixture is either premixed or added separately, to obtain a mixture;
c) contacting step b) mixture with heat source to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
4. A process for the preparation of 2,3,3,3-tetrafluoropropene comprising:
a) providing a heat source in a reactor;
13
b) providing methylchloride and tetrafluoroethylene, pre-mixed or added separately, in the reactor to obtain a mixture;
c) contacting step b) mixture with heat source to obtain a reaction mixture comprises 2,3,3,3-tetrafluoropropene; and
d) isolating 2,3,3,3-tetrafluoropropene from step c).
5. The process as claimed in claims 1 to 4, wherein the heat source is an electric heater.
6. The process as claimed in claims 1 to 4, wherein the heat source is used to provide a temperature in range of 250oC to 700oC or used to provide a temperature to a mixture of methylchloride and tetrafluoroethylene in the range of 250oC to 700oC in the reactor, or both to obtain a mixture.
7. The process as claimed in claims 1 to 4, wherein in step a) the mixture of methyl chloride to tetrafluoroethylene is in a molar ratio of 0.1:1 to 3:1.
8. The process as claimed in claims 1 to 3, wherein initiator is selected from carbon tetrachloride, hexachloroethane, trichloroacetylchloride, chloroform, phosegene, thionyl chloride, sulfonylchloride, trichloromethylbenzene, organic hypochlorites and inorganic hypochlorites and mixture thereof.