SIMULATION OF A MEDIATED ELECTROCHEMICAL PROCESS

Mediated electrosynthesis is a cyclic process involving electrochemical generation of a redox agent and use of that agent to effect a chemical reaction. This process is applicable to a large number of mediators and chemical substrates. Cerium in particular is an excellent mediator for syntheses of aldehydes and quinones. An ASPEN PLUS process and cost model is presented for the cerium mediated electrosynthesis of 1,4-naphthoquinone from naphthalene. The process involves two-phase reaction, phase separation, liquid-liquid extraction, electrochemical oxidation, and crystallization. The ASPEN PLUS simulator, however, does not include a module for the separation of organic and aqueous electrolyte solutions. Therefore, a liquid-liquid extractor block is developed based on distribution coefficients. The extractor model also accounts for phase entrainments. Stream compositions are controlled by maintaining fixed ratios of component mass flows. Finally, an extremely tight tolerance is required to account for minute quantities of organics in the aqueous stream. The use of the model to identify economically interesting operating conditions is demonstrated.