Multiphase photocatalytic microreactors

Heterogenous photocatalysis has been paid much attention in the last decades since it can utilize clean and abundant sunlight energy to drive reaction systems for cleaner productions and environmental protections. Those applications are usually conducted by multiphase reactors to make immobilized or dispersed solid photocatalyst in contact with reactants involved in gas (G) or liquid (L) single phase, otherwise in GL-multiphase medium. Such GS/LS/GLS multiphase microreactors have intrinsic advantage of high specific surface area leading to high mass transport in liquid/gas bulk or through interface. This study at first provided a set of general references on fundamentals of such reactors, and subsequently review on the state of the art researches highlighting engineering efforts to intensify the merits of multiphase photocatalytic microreactors. It was also shown that one of recent trends was to use photocatalyst slurry in millimeter/centimeter scale reactors rather than in microreactors to combine advantages of high surface area, sufficient illumination and high-throughput without clogging, even by leaving the issue of catalyst recovery aside. The intensification of photocatalytic processes in such mini-size reactors was also discussed.