Semicontinuous Distillation with Chemical Reaction in a Middle Vessel

Semicontinuous distillation with chemical reaction in a middle vessel (SDRMV) has been studied as a feasible means of combining separation and reaction unit operations using forced cyclic methods. A chemical process producing 2,4-dimethyl-1,3-dioxolane (24DMD) and water from the exothermic, reversible reaction of acetaldehyde and propylene glycol has been designed using the SDRMV method. Processes producing equivalent amounts and purities of 24DMD using traditional batch and continuous methods have also been designed. Rigorous simulations and detailed economic analyses over a range of production rates for the three processes show that SDRMV is the most economically optimal method for a broad range of intermediate production rates. The great potential of forced cyclic methods, using continuous distillation with a fed-batch reactor, a holding tank, and a supervisory control system, for the production of fine and specialty chemicals is demonstrated.