A review of intensification of photocatalytic processes

Photocatalysis is an attractive technology with potential applications in various disciplines, such as chemical synthesis, environmental technology and medicine, and receives an impressive amount of exposure in the open literature. However, industrial implementation remains limited due to scale up problems and the design of photoreactors. In this paper an overview is presented of recent advances in the design and application of novel reactors and devices. Two issues are essential: photon transfer limitations and mass transfer limitations (in the case of liquid phase reactions). In the field of mass transfer optimisation, spinning disc reactors, monolithic reactors and microreactors have been investigated for their use in photocatalysis. Significant advances are reported compared to conventional reactors. Studies focusing on performance improvement by optimising photon transfer, however, remain limited. While optical fibers and LEDs have been explored, major breakthroughs are still lacking. More focus on the introduction of a multitude of micro- or even nanoscale light emitting sources close to the catalyst particles is likely to be the way forward.