A Microchemical System with Continuous Recovery and Recirculation of Catalyst-Immobilized Magnetic Particles

摘要

Microfluidic systems have provided new concepts and challenging subjects for new chemical processes. The advantages offered are increased surface area to volume ratio, rapid mass- and heat-transfer, enhanced process safety, simple feasibility study for scaling up, and reduced waste. The reaction variables in the confined microscale space can also be controlled in easy and precise ways. Furthermore, it is a challenge in the microfluidic community to develop sophisticated continuous flow systems such as micro-TAS (total analytical system) by integrating several consecutive processes of multistep reaction, separation/purification, and detection into a single-chip device. For heterogeneous catalytic reactions, efforts have been made to take advantage of accelerated kinetics resulting from the shortened diffusion path of the reagents, little or no product contamination, and full resource utilization. Immobilizing catalysts on channel surfaces and packing solid catalysts including mesoporous structures have been attempted. However, the catalyst immobilization on the channel surface is hampered by many difficulties such as tricky immobilizing processes, the need for precise quantitative control of immobilized catalysts, and an inability to replace deactivated or poisoned catalysts. With packed catalyst systems, additional difficulties arise such as pressure drop control, low compatibility with a solid co-catalyst or product (or reactant), and clogging of the flow, which also applies to monolithic and porous silica capillary tube type microreactors as recently reported.