A process is described for the separation of C.sub.5 hydrocarbons present, in a quantity ranging from 0.2 to 20% by weight, in streams prevalently containing C.sub.4 products used for the production of high-octane hydrocarbon compounds, by the selective dimerization of isobutene, characterized in that the dimerization reaction is carried out in the presence of linear and branched alcohols and alkyl ethers in a quantity which is such as to have a molar ratio alcohols/alkyl ethers/isobutene in the feeding higher than 0.01.

The invention pertains to a method for converting butanediol into butadiene that is fed with a butanediol feedstock, where said method comprises at least an esterification step, a pyrolysis step, and a step for separation of the pyrolysis effluent comprising at least one section for cooling said pyrolysis effluent and producing a liquid pyrolysis effluent and a steam pyrolysis effluent and a gas-liquid washing section that is fed at the top with a fraction of the butanediol diester effluent obtained from the esterification step and at the bottom with the steam pyrolysis effluent, where said section produces a butadiene effluent at the top and a washing effluent at the bottom.

The invention pertains to a method for converting butanediol into butadiene that is fed with a butanediol feedstock, where said method comprises at least an esterification step, a pyrolysis step, and a step for separation of the pyrolysis effluent comprising at least one section for cooling said pyrolysis effluent and producing a liquid pyrolysis effluent and a steam pyrolysis effluent and a gas-liquid washing section that is fed at the top with a fraction of the butanediol diester effluent obtained from the esterification step and at the bottom with the steam pyrolysis effluent, where said section produces a butadiene effluent at the top and a washing effluent at the bottom.

Ethylbenzene can be separated from a C8 aromatics mixture containing ethylbenzene and a close boiling compound by extractive distillation using an extractive agent comprising a mixture of a chlorinated aromatic compound and another compound selected from furandione derivatives and organic nitriles.

Ethylbenzene can be separated from a C8 aromatics mixture containing ethylbenzene and a close boiling compound by extractive distillation using an extractive agent comprising a mixture of a chlorinated aromatic compound and another compound selected from furandione derivatives and organic nitriles.

The invention relates to a method for producing butadiene that is fed with a butanediol feedstock, with said method comprising at least: a) An esterification step comprising: A reaction section; A separation section producing a butanediol diester effluent, a water effluent, and a carboxylic acid effluent; b) An esterification pyrolysis step; c) A separation step comprising at least: A cooling section producing a liquid pyrolysis effluent and a vapor pyrolysis effluent; A gas-liquid washing section that is fed at the top with a fraction of the carboxylic acid effluent that is obtained from the separation section of step a) and at the bottom with said vapor pyrolysis effluent and producing at the top a butadiene effluent and at the bottom a washing effluent; in which a carboxylic-acid-rich stream comprising at least a portion of the liquid pyrolysis effluent is recycled to step a); d) A separation step.

The invention relates to a method for producing butadiene that is fed with a butanediol feedstock, with said method comprising at least: a) An esterification step comprising: A reaction section; A separation section producing a butanediol diester effluent, a water effluent, and a carboxylic acid effluent; b) An esterification pyrolysis step; c) A separation step comprising at least: A cooling section producing a liquid pyrolysis effluent and a vapor pyrolysis effluent; A gas-liquid washing section that is fed at the top with a fraction of the carboxylic acid effluent that is obtained from the separation section of step a) and at the bottom with said vapor pyrolysis effluent and producing at the top a butadiene effluent and at the bottom a washing effluent; in which a carboxylic-acid-rich stream comprising at least a portion of the liquid pyrolysis effluent is recycled to step a); d) A separation step.

Process for the distillative separation of ethylbenzene from a mixture comprising ethylbenzene and at least one other C8 aromatic compound, comprising distilling said mixture in a distillation column in the presence of an extractive solvent, characterized in that the distillation column is operated at a sub-atmospheric pressure.

Process for the distillative separation of ethylbenzene from a mixture comprising ethylbenzene and at least one other C8 aromatic compound, comprising distilling said mixture in a distillation column in the presence of an extractive solvent, characterized in that the distillation column is operated at a sub-atmospheric pressure.

Processes and systems for separating a mixture of three or more chemical components into multiple product streams each enriched in one of the components are provided herein. In some aspects, the present invention relates to processes for the separation of a chemical mixture including at least a heavy key component, an intermediate key component, and a light key component to form a product stream enriched in the light key component, a product stream enriched in the intermediate key component, and a product stream enriched in the heavy key component. Systems described herein may include one or more thermally coupled distillation columns including, for example, a dividing wall column, or a plurality of distillation columns arranged in a thermally integrated configuration.