| 摘要 |
{PG,1 Acetylenic hydrocarbons are removed from a C{HD 4{L - or C{HD 5{L - hydrocarbon mixture containing a C{HD 4{L - or C{HD 5{L - diolefin respectively. The feedstock (e.g. a C{HD 4{L - or C{HD 5{L - cut from an ethylene plant) is extractively distilled to remove paraffins and mono-olefins in the raffinate, using acetonitrile (ACN), dimethyl formamide (DMF), furfural, acetone, dimethylacetamide or N-methyl-2-pyrrolidone mixed with 0{14 12 weight percent water as the extraction solvent. The bottoms from this first extractive distillation is subjected to a second extractive distillation in which virtually acetylenes-free solvent is used. Isoprene is withdrawn as the distillate with substantially reduced acetylenes content. The bottoms of the second extractive distillation is split three ways. Two streams are handled conventionally (recycle and heavies removal). The third is stripped free of acetylenes so that it may be used as solvent in the second extractive distillation.
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