(97a) Single and Multiphase Mixing and Contacting in Microreactors

Contacting between reactants is a prerequisite in reactor operation. In most cases rapid mixing is required (for single-phase systems) or efficient interdispersion (for multiphase systems). In single phase systems, passive mixing has until recently relied primarily on molecular diffusion. In these cases, mixing structures have been designed so that the lamellae thickness of fluids is minimised. Many successful mixers have been developed on this basis. Recently other highly efficient mixing devices have been developed utilising chaotic advection, where mixing length is not linearly dependent on fluid velocity. In multiphase systems, microreactors open up opportunities not only for good interdispersion between phases by achieving high surface areas and short mass transfer distances but also for efficient non-dispersive contact between phases, due to the thin fluid layers that can be achieved. Relevant studies will be presented, while selected applications demonstrating the improved performance of microscale mixing and contacting will be given.