Author:

Keywords:

Photochemistry, 3D-printing, COMSOL raytracing

Abstract:

There is an increasing interest in photochemical reactions from the industry due to the numerous advantages of photochemistry,e.g., mild reaction conditions, improved selectivity and low requirement of organic solvents. However, these reactions are seldom used in the industry despite the fact that they are already proven to be successful for the production of numerous fine chemicals such as ε-caprolactam, rose oxide and vitamin D. The industry is reluctant to integrate photochemical reactions mainly due to the major limitation of the scalability. This is caused by the uncontrolled coupling between hydrodynamics, photon, mass transfer and photochemical kinetics. Using microstructured reactors solves mentioned problems by providing a high surface area to volume ratio, uniform irradiation and control over exposure time which prevents under- and over-irradiation. One problem that microstructured reactors do not solve, is the scalability. A way to scale-up these reactors is to make use of repetitive structures which are commonly found in monolith structures. There were several attempts to use monoliths for photochemistry but they resulted in slow apparent kinetics since conventional monoliths are made of opaque materials. With the recent advances in 3D-printing, it is possible to print a monolithic structure with translucent materials. This novel method of reactor manufacturing poses a serious challenge in terms of reactor design as there are no design principles to dimensionalise a translucent monolith. In this study, various design aspects of translucent monolith structures were explored. Namely, the ratio of the distance between the channels (l) to the characteristic length (D), channel conformation and refractive indices of support material and reaction media. Mathematical simulations utilizing a 2D model resulted in optimal design rules, maximizing the homogeneity of the light distribution as well as energy efficiency and overall space-time yield.