Chapter 7: Solar Photochemical Manufacturing of Fine Chemicals: Historical Background, Modern Solar Technologies, Recent Applications and Future Challenges

Sunlight can be used effectively to drive photochemical transformations in a sustainable fashion. Historically, photochemistry has been a solar research area and experiments were routinely conducted on the roof tops of chemical institutes following the ‘flask in the sun’ approach. Once powerful and reliable artificial light sources were developed, photochemistry moved inside and became a successful, but somehow neglected research area. Due to the high energy demands of technical lamps, industrial applications of photochemistry remained limited to the synthesis of certain fine chemicals. To overcome these energy needs, sunlight has recently been rediscovered as a ‘free’ energy and light source. Modern solar concentrators enable an acceleration of photochemical processes and an up-scaling to technical production. After a brief introduction to the history and present challenges of photochemistry, this chapter summarizes the most important solar reactor types and provides examples of their adaptation in preparative solar syntheses. These highlights clearly demonstrate that the solar manufacturing of fine chemicals is technically feasible and environmentally sustainable. It is hoped that further research into this truly enlightening technology will lead to industrial applications in the foreseeable future.