OSCILLATORY VAPOR-LIQUID TRANSPORT PHENOMENA IN A PACKED REACTIVE DISTILLATION COLUMN FOR FUEL ETHER PRODUCTION

A packed reactive distillation column was operated for the production of the fuel ether methyl-tert-butylether (MTBE) from methanol and isobutene. A new glass-ring-supported porous sulfonic acid ion-exchange catalyst was applied as packing element for simultaneous distillation. During the experiments, sustained oscillations of boiling temperatures and of reflux were observed. It was found out that these oscillatory phenomena come from the non-reactive distillation process of the reactants methanol and isobutene. The oscillation periods depend on reboiler heat input and on the isobutene content in the feed. Simulations with a non-equilibrium-stage model for the packed distillation column reveal that, in a certain region of specified distillate fluxes, increasing refluxes make methanol-isobutene separation worse in the top part of the column. This is caused by interaction of flows and compositions inside the column and corresponds to an unstable operating point. However, the separation of methanol and MTBE is predicted to be stable under the experimental conditions.