| 摘要 |
Aliphatic dienes are separated from monoenes and alkanes or mono-enes from alkanes, by extractive distillation in the presence of a polar solvent having a higher boiling-point than the hydrocarbons, an additional gas being added to the lower part of the column, said gas being either a gas inert to the system (e.g. N2 or CO2) or a part of the recovered diene or mono-ene. In a modification the additional gas may be produced in situ in the lower part of the column by carrying out the distillation under sub-atmospheric pressure, with the column head temperature being below 45 DEG C. Suitable solvents are dimethyl sulphoxide, methoxy sulpholane, and b ,b 1-oxydipropionitrile, any of which may contain a small amount of added water. Examples describe the separation of butadiene from a C4-stream; and isoprene from a C5-stream, the added gas being part of the recovered butadiene or isoprene respectively. |
