GB1172009A - Improvements in or relating to the Separation of Reaction Mixtures Resulting from the Chlorination of Aliphatic Hydrocarbons - Google Patents

Abstract

1,172,009. Separating aliphatic hydrocarbon chlorination products. FARBWERKE HOECHST A.G. 30 Aug., 1967 [30 Aug., 1966], No. 39702/67. Heading B1L. [Also in Division C2] The reaction mixture from the chlorination of an aliphatic hydrocarbon having a boiling point below that of hydrogen chloride, e.g. methane, and which comprises unreacted hydrocarbon, hydrogen chloride and chlorinated hydrocarbons, e.g. methyl and methylene chlorides, chloroform and carbon tetrachloride, is separated by washing the reaction mixture in the gas phase with the liquid monochlorinated product of the hydrocarbon. As shown, reaction mixture from reactor A passes by line 1 to column C where it ascends in counterflow to mono-chlorinated hydrocarbon wash fluid entering by line 8. Generally, column C is maintained at 1-35 atmos. gauge and -50 to 20‹C. The bottom product of chlorinated hydrocarbons passes by line 3 to distillation column F where it is fractionated. Overhead gas from column C passes by line 2 to column D where it ascends in counterflow to HCl-free chlorinated hydrocarbon fed by line 7. If desired, HCl may be added to line 7 to control the HCl level of the cycle. The overhead of unreacted hydrocarbon is recycled to reactor A by line 4. Bottom product of HCl-containing monochlorinated hydrocarbon from column D is partly returned by line 8 to column C, but most passes by line 9, together with the overhead from column F in line 6, to column E. It is there separated into an overhead of pure HCl gas, and a bottom product of pure monochlorinated hydrocarbon which are recycled by line 7 to column D; part may be fed by line 10 into line 3.