Increasing yield in crude di:methyl terephthalate prodn.

摘要

- Production of crude dimethyl terephthalate (crude DMT) involves (1) oxidation of para-xylene and methyl para-toluate; (2) esterification of the oxidation product with methanol; and (3) separation of the crude ester into (a) a fraction that is recycled to oxidation, (b) a crude DMT fraction and (c) a high-boiling residue fraction. The novelty is that separation is carried out in a distillation unit with structural packing having a surface area of 100-800 m<2>/m<3> at a top temperature of 100-220 deg C at 30-200 mbar and sump temperature of 1180-260 deg C, in which the pressure difference between the top and sump is /} 30 mbar.