Abstract: High temperatures and oxygen exposure during extractive distillation can result in polymerization of vinyl aromatic compounds. In various embodiments, the present disclosure relates to methods for inhibiting polymerization of vinyl aromatic compounds during extractive distillation. In various embodiments, the methods include a) providing a mixture containing at least one vinyl aromatic compound, b) adding at least one dinitrophenol inhibitor to the mixture, and c) after step b), performing an extractive distillation on the mixture to isolate the at least one vinyl aromatic compound. Purified styrene can be isolated by the methods described herein. In some embodiments, the dinitrophenol inhibitor is 2-sec-butyl-4,6-dinitrophenol (DNBP).

Abstract: In various embodiments, the present disclosure describes methods for removing impurities from a hydrocarbon stream containing at least one vinyl aromatic compound such as, for example, styrene. The methods include pretreating at least one sorbent to make the at least one sorbent operable for adsorbing the impurities, contacting the hydrocarbon stream with the at least one sorbent in order to adsorb at least a portion of the impurities and separating the hydrocarbon stream from the at least one sorbent. Impurities include, for example, colored impurities, sulfur-containing impurities and combinations thereof.

Abstract: In various embodiments, the present disclosure describes processes and systems for recovery of styrene from a styrene-rich feedstock. The processes and systems maintain performance of an extractive solvent used in the styrene recovery. In general, the processes include introducing a styrene-rich feedstock to an extractive distillation column, removing a styrene-rich stream from the extractive distillation column, introducing the styrene-rich stream to a solvent recovery column, removing a styrene-lean stream from the solvent recovery column, separating and treating a portion of the styrene-lean stream to form a treated extractive solvent and recycling the treated extractive solvent. In some embodiments, the treating process also includes steam stripping. Styrene-recovery systems including an extractive distillation column, a solvent recovery column, a solvent treatment apparatus having at least one equilibrium stage and a continuous circulation loop connecting these components are also disclosed herein.