One of the limitations for reactive distillation to be economically attractive is that the temperature range suitable for reasonable chemical reaction kinetics must match the temperature range suitable for vapor-liquid equilibrium since both separation and reaction occur in a single vessel. This temperature mismatch problem can sometimes be overcome by considering an alternative process flowsheet that features a distillation column linked with several external side reactors. In this alternative flowsheet, the column operates at a low pressure and temperatures favorable for separation. Liquid sidestreams from trap-out trays at intermediate locations in the column are pumped to external reactors operating at higher pressure and temperatures that are favorable for chemical kinetics. The reaction studied here is an exothermic reversible liquid-phase reaction A+B↔C+D, which occurs in adiabatic plug-flow reactors. Reactor effluents are fed back to the column on the tray below the trap-out tray from which they were withdrawn. The light product C leaves in the distillate, while the heavy product D is removed from the bottoms. This study extends the work of Kaymak and Luyben (2004) to provide a more rigorous steady-state economic optimization of the column/side reactor flowsheet. Effects of five optimization variables on the optimization problem are investigated: (i) number of external side reactors N_EXT, (ii) holdup of each reactor V_R, (iii) number of trays between each liquid trap-out N_LT, (iv) number of the stripping trays N_S, and (v) number of the rectifying trays N_R. Results demonstrate that this configuration has better steady-state economics than conventional reactive distillation in cases where there is a temperature mismatch between reaction and separation.

Extended Abstract Status: Not Uploaded