关键词: 碳酸二甲酯, 甲醇, 精馏, 隔板塔, 热集成

Abstract:

Dimethyl carbonate (DMC), methyl formate and methylal etc. are co-products which are not well separated and discharged as waste materials in many coal-to-ethylene glycol plant. As DMC is a valuable and useful raw material in many fields, proper process is needed for DMC rectifying because DMC and methanol forms stable azeotrope and they cannot be completely separated by conventional distillation methods. Pressure swing distillation is chosen after comparing methods of DMC-methanol separation. Three improved process schemes are discussed and designed to be used in the recovery and purification of dimethyl carbonate from the co-product residual liquid, which contain methanol, dimethyl carbonate and methyl formate etc. in coal-to-ethylene glycol plant, to obtain high purity (over 99.9%) DMC product. Those three process schemes are suitable for feeding DMC composition lower than high pressure azeotropic composition, higher than normal pressure azeotropic composition and more than 90% DMC content, respectively, in which the lower energy consumption and high DMC purity can be achieved.

Key words: dimethyl carbonate, methanol, rectifying, divided wall column, heat integration