Separation of aromatic hydrocarbons from a mixture of aromatic and non-aromatic hydrocarbons by solute swing extraction

摘要

The invention relates to a process for separating aromatic hydrocarbons from a mixed hydrocarbon feed employing a selective solvent which exhibits a low critical solution temperature of the solvent with a solute. The mixed hydrocarbon feed is passed to an extraction zone wherein the feed is contacted with a lean solvent to provide a raffinate stream comprising non-aromatics and a rich solvent stream comprising aromatics and solvent. Both the raffinate stream and the rich solvent stream are admixed with a sufficient amount of a solute at a temperature which is at or below a low critical solution temperature with the solvent to separate the raffinate and aromatic phases from the solvent/solute mixture. The solvent/solute mixture is heated to a separation temperature which is above the low critical solution temperature to provide a solvent phase which is essentially free of solute at energy levels significantly lower than conventional processes.