Process for separating solids from an aqueous stream comprising epsilon-caprolactam

Abstract

A method for separating solids from a liquid water stream SR, the liquid water stream SR comprising a monomer ε-caprolactam dissolved in water and having a solid content cR, the method comprising: (i) preparing the stream SR comprising providing a stream SM comprising a solid material M comprising polyamide 6; preparing an aqueous depolymerization mixture based on SM; and subjecting the depolymerization mixture to polyamide 6 depolymerization conditions in a reaction unit UR to obtain the stream SR; (ii) subjecting the stream SR to solid-liquid separation conditions in a solid-liquid separation unit USL comprising at least one centrifuge to obtain a liquid water stream Sp from the USL comprising ε-caprolactam and having a solid content cp, the unit USL having an overall separation efficiency ΘT ≥ 70%. A process for separating solids from a liquid aqueous stream SR comprising monomeric ε-caprolactam dissolved in water and exhibiting a solids content cR, the process comprising (i) preparing the stream SR, comprising providing a stream SM comprising a solid material M comprising polyamide 6; preparing an aqueous depolymerization mixture based on SM; and subjecting the depolymerization mixture to polyamide 6 depolymerization conditions in a reaction unit UR, obtaining the stream SR; (ii) subjecting the stream SR to solid-liquid separation conditions in a solid-liquid separation unit USL comprising at least one centrifuge, obtaining from USL a liquid aqueous stream SP comprising ε caprolactam and exhibiting a solids content cP, the unit USL exhibiting a total separation efficiency ΘT ≥ 70 %.