| 摘要 |
1,148,100. Separating conjugated diolefins. JAPANESE GEON CO. Ltd. 29 Dec., 1966 [30 Dec., 1965(2)], No. 58178/66. Heading C5E. A process for the separation of a conjugated diolefin from a C 4 or C 5 hydrocarbon mixture containing said conjugated diolefin and higher acetylenes (including allenically unsaturated hydrocarbons) comprises subjecting the hydrocarbon mixture to extractive distillation with a solvent consisting essentially of an N-alkyl substituted aliphatic acid amide of the formula RCONR 1 R 2 , wherein R and R 1 are each a hydrogen atom or a C 1 -C 3 alkyl radical and R 2 is a C 1 -C 3 alkyl radical, recovering the conjugated diolefin as a distillate and the higher acetylenes as an extract in the solvent, and subjecting the extract to stripping so as to recover the solvent as bottoms liquid and the acetylenes as overhead fraction. If the hydrocarbon mixture also contains hydrocarbons less soluble than the conjugated diolefins such as paraffins and mono-olefins, then a two stage extractive distillation process may be used to recover the pure conjugated diolefin, a mixture of the conjugated diolefin and higher acetylenes being obtained as an extract in the first stage and the less soluble hydrocarbons removed as top distillate, the extract then being extractively distilled in accordance with the invention to obtain the pure conjugated diolefin as distillate in the second stage. Examples describe the recovery of butadiene 1,3 and isoprene from C 4 and C 5 feedstocks respectively. The amide solvent is preferably dimethyl formamide, diethyl formamide or dimethyl acetamide and may be used in admixture with 0-01 - 30% by wt. of a polymerization inhibitor e.g. tertiary butyl catechol, sulphur, sodium nitrite, furfural benzaldehyde and aromatic nitro compounds. |
