Removal of dimethylterephthalate from a methanolysis vapor stream

摘要

A method of removing dimethyl terephthalate (DMT) from a vapor stream. The vapor stream includes dimethyl terephthalate (DMT), methylhydroxyethyl terephthalate (MHET), glycols and methanol. A distillation column is held under an elevated pressure of 100 to 500 kPag and at a temperature of at least 85 DEG C. It has (i) a plurality of distillation trays; (ii) methanol liquid sprays between the trays; (iii) a main spray zone below the trays and (iv) a liquid pool of methanol in the bottom of the column. The vapor stream is directed into the distillation column, above the liquid pool and below the main spray zone, thereby forming a stream of liquid and vapor. The stream of liquid is directed away from the distillation column walls and into the liquid pool at the bottom of the column. Concurrently, a portion of the liquid in the bottom of the column is (i) recycled back into the distillation column as a spray in the column above the vapor stream inlet, thereby preventing build up of solid DMT on column surfaces and (ii) removed from the column to enable DMT removal.