Optimal Design of a Reactive Distillation Process for the Synthesis of Diphenyl Carbonate

Diphenyl carbonate (DPC) is a precursor in the production of polycarbonate, an important engineering thermoplastic with excellent mechanical and optical properties as well as electrical and heat resistance properties. Traditionally, DPC is synthesized by the transesterification reaction of dimethyl carbonate (DMC) and phenol. In the study, phenyl acetate is used instead of phenol to react with DMC to yield DPC due to its higher reaction conversion and the absence of side reactions and azeotrope. A reactive distillation (RD) column conducting the transesterification reaction with excess DMC is designed to obtain high-purity DPC at the column bottom and a mixture of DMC and methyl acetate at the column top. The mixture is then separated by a conventional distillation column. The plant-wide process of the RD is optimized by minimizing the total annual cost. The performance of partially thermal coupling between the RD column and the separation column is also investigated in the study. RD with partially thermal coupling is demonstrated to provide better energy efficiency than conventional RD. The remixing phenomenon associated with thermodynamic inefficiency in conventional distillation sequences can be much reduced by implementing thermal coupling between columns. Reactant concentrations with more near stoichiometric balance in the reaction zone are given in the partially thermally coupled RD column.