| 摘要 |
PURPOSE: Processes to produce high purity styrene from a pyrolysis gasoline stream containing close-boiling aromatic and non-aromatic hydrocarbons by extractive distillation employing a more selective solvent are provided. CONSTITUTION: The process for separating styrene from at least one close-boiling aromatic or non-aromatic hydrocarbon such as o-xylene comprises the steps of extractively distilling the mixture in the presence of a two-part extractive solvent, the first part of which is selected from the group consisting of propylene carbonate, sulfolane (tetramethylene sulfon), methyl carbitol, 1-methyl-2-pyrrolidinone, 2-pyrrolidinone, and mixtures thereof, and the second part of which is water, to obtain a solvent fraction relatively rich in styrene, and stripping styrene from the solvent fraction. The extractive solvent preferably contains 0-10 wt% of the second part to the first part. Also the process for producing styrene from a feedstock comprising styrene and at least one close-boiling aromatic or non-aromatic hydrocarbon comprises feeding the feedstock into a distillation zone, feeding the two-part extractive solvent into the distillation zone, distilling the feedstock in the distillation zone in the presence of the extractive solvent to produce a solvent fraction relatively rich in styrene compared to the solvent fed to the distillation zone and an overhead fraction comprising the hydrocarbon and being relatively lean in styrene compared to the feedstock, withdrawing the solvent fraction from the distillation zone and withdrawing the overhead fraction from the distillation zone.
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