Known: Fluorocarbons can be produced from the reaction of carbon tetrachloride and hydrogen fluoride followed by a number of separation steps.
Given: Flow diagram and a brief description of a fluorocarbons production process in "Chemical Process Industries" , 4th edition, by Shreve and Brink and also in Shreve's Chemical Process Industries", 5th edition, by G. T. Austin, pages 353-355 (Fig. 20.4).
Find: Draw a process flow diagram and describe the process.
Description of Process Two main reactions occur:
CCl4 + HF ---> CCl3F + HCl
CCl3F +HF ---> CCl2F2 + HCl
Excess carbon tetrachloride is reacted in R1 with HF in the presence of antimony pentoxide catalyst and a small amount of chlorine to maintain catalyst activity. The HF contains a small amount of water as an impurity. The effluent from the R1 is HCl, CCl3F, CCl2F2, unreacted CCl4, and small amounts of water and chlorine. The normal boiling points in oC of these components in the order of decreasing volatility are:
HCl ..................... -84.8
Cl2 ....................... -33.8
CCl2F2 ................... -29.8
CCl3F ....................... 23.7
CCl4 .......................... 76.7
H2O .............................100
