Abstract

Development of Continuous Flow Micro-reactors for Fast Liquid and Liquid-liquid Reactions

Arturo Macchi, Professor of Chemical and Biological Engineering, University of Ottawa

Continuous operation presents multiple advantages over batch chemistry, yet its usage in the fine chemical and pharmaceutical industry remains limited due to its complexity. A holistic tool-box approach for process development is presented such to facilitate technology transfer. Reaction kinetics and reacting phases are taken into consideration for the selection of the most appropriate reactor and operating conditions. A micro-reactor for fast liquid and liquid-liquid reactions is then more specifically developed. The yield of competitive parallel reactions was used to characterize mixing in the single phase system whereas a reactive liquid-liquid extraction was used to investigate interphase mass transfer and resulting flow regimes in the two-phase system. The effects of phase physical properties, mixer geometry, method of energy input and scale were measured and analyzed such to optimize the reactor design. A key finding is that mixing and interphase mass transfer is a scalable function of the average rate of energy dissipation once the flow has reached turbulent flow (single-phase system) and drop flow (two-phase system), independent of reactor geometry, indicating that efficient micro-mixers achieve these flow conditions at the lowest possible energy dissipation rate. Moreover, multiphase micro-mixer geometries that are based on contraction-expansion repeating units with alternating asymmetric obstacles to aid the breakup of the dispersed phase, and desynchronize the recombination of split streams are most effective.