Patent ID: 9643904
Date: 2017-05-09
CPC Classifications: C07C

Claim:
1. A method for preparing 2,3,3,3-tetrafluoropropene, comprising: a) introducing hexafluoropropylene and hydrogen to a first reactor to allow hexafluoropropylene to react with hydrogen in the presence of a catalyst to obtain a first mixture comprising 1,1,1,2,3-pentafluoropropene, 1,1,1,2,3,3-hexafluoropropane, hydrogen fluoride, and hexafluoropropylene, in which a molar ratio of hexafluoropropylene to hydrogen is between 1:0.95 and 1:0.99, a space velocity is between 200 and 1000 h b) washing and drying the first mixture obtained from a), and introducing the treated first mixture to a first distillation column to obtain 1,1,1,2,3,3-hexafluoropropane in a bottom of the first distillation column and 1,1,1,2,3-pentafluoropropene and hexafluoropropylene at a top of the first distillation column; recycling the 1,1,1,2,3,3-hexafluoropropane to the first reactor, and introducing the 1,1,1,2,3-pentafluoropropene and the hexafluoropropylene to a second distillation column to yield hexafluoropropylene at a top of the second distillation column and 1,1,1,2,3-pentafluoropropene at a bottom the second distillation column; and recycling the hexafluoropropylene to the first reactor; c) introducing the 1,1,1,2,3-pentafluoropropene obtained from b) and hydrogen to a second reactor and allowing the 1,1,1,2,3-pentafluoropropene to react with the hydrogen in the presence of a catalyst, to obtain a second mixture comprising 1,1,1,2,3-pentafluoropropane, 2,3,3,3-tetrafluoropropene, HF, and H2, in which a molar ratio of the hydrogen to the 1,1,1,2,3-pentafluoropropene is between 1:0.95 and 1:0.99, a space velocity is between 300 and 2000 h−1, and a reaction temperature is between 80 and 500° C.; and d) washing and drying the second mixture obtained from c), and introducing the second mixture to a third distillation column to yield 1,1,1,2,3-pentafluoropropane at a bottom of the third distillation column; and recycling the 1,1,1,2,3-pentafluoropropane to the second reactor, to yield 2,3,3,3-tetrafluoropropene at a top of third distillation column.