ES354980A2 - Working-up of gaseous reaction mixtures resulting from a chlorination of methyl chloride - Google Patents

Abstract

The gaseous reaction mixture from the chlorination of methyl chloride which comprises unreacted methyl chloride, hydrogen chloride and higher chlorinated hydrocarbons e.g. methylene chloride, chloroform and carbon tetrachloride, is diluted with an inert gas having a boiling point not greater than that of hydrogen chloride, e.g. nitrogen, and is then separated by washing the mixture with liquid methyl chloride to obtain a liquid phase containing the higher chlorinated products. As shown, the gaseous reaction mixture containing nitrogen from reactor A passes by line 1 to column C where it ascends in counterflow to methyl chloride wash fluid entering by line 8. Generally, column C is maintained at 1-35 atoms. gauge and -50 to 20 C. The bottom product containing methyl chloride and higher chlorinated hydrocarbons passes by line 3 to column F where it is frictionated. Overhead gas from column C passes by line 2 to column D where it ascends in counterflow to HCI-free methyl chloride fed by line 7. The overhead of HC1, N 2 and methyl chloride is recycled to reactor A by line 4. Bottom product of HCl-containing methyl chloride from column D is partly returned by line 8 to column C, but most passes by line 9 to column E where it is separated into an overhead of pure HCI gas and a bottom product of pure methyl chloride which is recycled by line 7 to column D part may be fed by line 10 to line 3. In a modification, the inert gas may comprise only the HCI gas necessarily present in the effluent from reactor A.