Monomer recovery process

A process for recovering and recycling monomers and solvent present in a waste stream from a copolymer polyol production process, the recovering and recycling process comprising the steps of:

• (a) providing a waste feed stream from the copolymer polyol production process, the waste feed stream containing styrene and acrylonitrile monomers, solvent and impurities;
• (b) subjecting the waste feed stream of step (a) to a separation process under conditions for separating the monomers and solvent from the impurities of the waste stream, the separation process including:
• (i) separating the waste feed stream in a first distillation column to form a first overhead stream containing acrylonitrile and water, a first side-stream containing solvent and a first bottoms stream containing styrene;
• (ii) feeding the first bottoms stream into a second distillation column to form a second overhead stream containing impurities, a second side-stream containing styrene, and a second bottoms stream that includes the impurities;
• (iii) feeding the first overhead stream into an extractive distillation column to form an extractive overhead stream containing acrylonitrile, and extractive bottoms stream that includes water, and an extraction solvent;
• (iv) feeding the extractive bottoms stream to a third distillation column to form a third overhead stream that includes water and a third bottoms stream that includes the extraction solvent;
• (c) recovering the monomers and solvent from the first side-stream, the second side-stream, and the extractive overhead stream;
• and
• (d) passing the one or more of the monomers and solvent from step (c) to the feed stream in the copolymer polyol production process.