Method for producing trifluoroethylene
To provide a production process with high degree of conversion of HFC-134a and selectivity for HFO-1123, with a high productivity of HFO-1123 and with a small load in process of purification and recovery. A process for producing HFO-1123, which comprises bringing a material gas having a proportion of HFC-134a based on the total amount of a diluent gas and HFC-134a of from 50 to 100 mol % into contact with a dehydrofluorination catalyst to convert part of HFC-134a into HFO-1123, then removing hydrogen fluoride in a reaction product gas, and then bringing the reaction product gas from which hydrogen fluoride has been removed into contact with a dehydrofluorination catalyst to convert at least part of unreacted HFC-134a into HFO-1123.
1. A process for producing trifluoroethylene, the process comprising:
bringing a 1,1,1,2-tetrafluoroethane gas or a 1,1,1,2-tetrafluoroethane gas diluted with a diluent gas, wherein a proportion of 1,1,1,2-tetrafluoroethane based on the total amount of the diluent gas and 1,1,1,2-tetrafluoroethane is at least 50 mol %, into contact with a first dehydrofluorination catalyst in a first reactor, thereby converting a part of 1,1,1,2-tetrafluoroethane into trifluoroethylene, and wherein moisture is formed as a by-product,
conducting a treatment other than removal of hydrogen fluoride that does not change components in the first reactor other than a content of moisture in a reaction product gas,
removing hydrogen fluoride from the obtained reaction product gas, and
bringing the reaction product gas from which hydrogen fluoride has been removed into contact with a second dehydrofluorination catalyst in a second reactor, thereby convening at least a part of 1,1,1,2-tetrafluoroethane into trifluoroethylene.
2. The process for producing trifluoroethylene according to claim 1 , wherein a proportion of 1,1,1,2-tetrafluoroethane based on the total amount of 1,1,1,2-tetrafluoroethane and the diluent gas is at least 70 mol %.
3. The process for producing trifluoroethylene according to claim 1 , wherein the diluent gas is a nitrogen gas.
4. The process for producing trifluoroethylene according to claim 1 , wherein the first dehydrofluorination catalyst and the second dehydrofluorination catalyst are each independently at least one catalyst selected from the group consisting of a metal, a metal oxide and a metal halide.
5. The process for producing trifluoroethylene according to claim 1 , wherein the first dehydrofluorination catalyst and the second dehydrofluorination catalyst are each independently a catalyst comprising at least one compound selected from the group consisting of aluminum oxide, aluminum trifluoride and chromium oxide.
6. The process for producing trifluoroethylene according to claim 1 , wherein the first dehydrofluorination catalyst and the second dehydrofluorination catalyst are catalysts of exactly the same type.
7. The process for producing trifluoroethylene according to claim 1 , wherein each of the contact temperature of 1,1,1,2-tetrafluoroethane and the first dehydrofluorination catalyst and the contact temperature of 1,1,1,2-tetrafluoroethane and the second dehydrofluorination catalyst is from 50 to 500° C.
8. The process for producing trifluoroethylene according to claim 7 , wherein each of the contact temperatures is from 300 to 450° C.
9. The process for producing trifluoroethylene according to claim 1 , wherein each of the contact time of 1,1,1,2-tetrafluoroethane and the first dehydrofluorination catalyst and the contact time of 1,1,1,2-tetrafluoroethane and the second dehydrofluorination catalyst is from 0.1 to 500 seconds.
10. The process for producing trifluoroethylene according to claim 9 , wherein each of the contact times is from 5 to 30 seconds.
11. The process for producing trifluoroethylene according to claim 1 , wherein hydrogen fluoride is removed by bringing the reaction product gas into contact with an alkaline aqueous solution.
12. The process for producing trifluoroethylene according to claim 1 , wherein moisture is removed from the reaction product gas from which hydrogen fluoride has been removed, and then the reaction product gas from which moisture has been removed is brought into contact with the second dehydrofluorination catalyst.
13. The process for producing trifluoroethylene according to claim 1 , wherein the treatment other than removal of hydrogen fluoride is selected from the group consisting of storage in a tank, compression by a compressor, heating, cooling, and removal of moisture.