Construction of a novel continuous flow reactor for solid-state photochemistry

Abstract

Solid-state photoreaction has recently gained more attention due to its high selectivity, which has the potential to design chiral synthesis or shorten the synthesis pathway. One of the limitations of scaling up these solid-state reactions is the lack of a controllable reactor. The existing photoreactors have some problems with mobile particles, including dealing with particle blockage and reducing the attenuation effect of light transport during scaling up.

In this thesis, a swirl-induced pipe is applied to design a multiphase flow tubular photochemical reactor creating a ring distribution of particles, which can reduce particle accumulation and expose particles evenly to light. The particle distribution along the pipe was obtained using the Eulerian method with the k-ω shear stress transport (SST) turbulence model. The radiation transfer equation
was solved by the discrete ordinate (DO) model. The absorption coefficient was calculated from the UV-absorption spectrum, and the scattering coefficient was determined by Mie scattering theory.

The results show that the settled particle can be redistributed by the tangential velocity induced by the swirl-induced pipe, showing an anti-blocking effect. Moreover, the local volumetric rate of energy absorbed (LVREA) is increased up to about twice that in the straight pipe due to the increasing retention time caused by the swirl. Different inlet conditions were compared according to their corresponding LVREA and specific radiation absorption (absorbed energy per weight of particles), and the specific absorption has a 5% increase compared to the straight pipe for cinnamic acid crystalline. Meanwhile, the induction of the swirl pipe improves the continuous flow of solids, which facilitates the flow chemistry of solid materials. To further explore the cause affecting the performance of the reactor, factors are defined to describe the particle distribution. A fully expended and compact layer of solid particles can receive more photons. This thesis provides insight into the insertion of the swirl pipe into the photoreactor design.

Date of Award	15 Jul 2025
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Philip Hall (Supervisor), Mike George (Supervisor) & Nick Miles (Supervisor)