Method for separating and recovering dimethyl terephthalate and ethylene glycol from polyester waste

A process for separation and recovery of dimethyl terephthalate and ethylene glycol from polyester waste characterized in that a polyester waste containing polyethylene terephthalate as the major component along with foreign material is successively subjected to the following steps (a) to (f):

• step (a) in which said polyester waste is mixed into ethylene glycol containing a polyester depolymerization catalyst, the resultant mixture is treated at a temperature of 175 to 190° C. under a pressure of 0.1 to 0.5 MPa, and, from solid foreign materials contained in the resulting reaction solution, a fraction of the solid foreign materials which have floated to the surface of said solution, is removed by means of a floatation separation method;
• step (b) in which, from the solution fraction delivered from step (a), the residual solid foreign materials which are contained in the solution and have not floated to the solution surface in step (a) is removed, by a solid/liquid separation method;
• step (c) in which the residual solution fraction delivered from step (b) is distilled and concentrated to recover the distilled ethylene glycol;
• step (d) in which the distillation residue delivered from the step (c) is mixed with a transesterification reaction catalyst and methanol to cause a transesterification reaction between said distillation residue and methanol to occur to produce dimethyl terephthalate and ethylene glycol, the resultant reaction mixture is subjected to recrystallization treatment and then to centrifugal separation to separate the reaction mixture into a dimethyl terephthalate cake and a mixture solution, and said cake is subjected to a distillation purification, to recover the distilled dimethyl terephthalate, having a high degree of purity;
• step (e) in which said mixture solution delivered from step (d) is subjected to a distillation treatment to recover the distilled methanol, and
• step (f) in which the distillation residue delivered through step (e) is subjected to a distillation treatment to recover the distilled ethylene glycol.