Abstract

Solids Handling in Microreactors

Simon Kuhn, Associate Professor, Katholieke Universiteit Leuven

Using microstructured devices in chemical engineering provides several advantages over conventional, and mostly batch, reaction systems. Due to the decrease in length scale an increased surface-to-volume ratio is obtained, which is beneficial to achieve enhanced mass and heat transfer coefficients. However, there are also challenges associated with microchemical devices, especially the prevention of clogging in the presence of solid particles. To address this issue, we developed a Teflon stack microreactor with an integrated piezoelectric actuator for conducting chemical synthesis with solid products. The microreactors are demonstrated with palladium-catalyzed C–N cross-coupling reactions, which are prone to clogging microchannels by forming insoluble salts as by-products. To prevent microchannel clogging, the size of the precipitating particles must be minimized and their interactions with the walls reduced, which is achieved by fabrication the microreactor completely out of Teflon (PTFE) plates with an integrated piezoelectric element as acoustic actuator. The synthesis of nanoparticles in microfluidic devices is also addressed, and the results show a strong correlation between the particle characteristics and the two-phase hydrodynamics inside the microreactor. Based on this observation, we also present a numerical tool to extract kinetic information from experimental results and further feedback on a CFD-DEM (computational fluid dynamics-discrete element modeling) framework, which allows the prediction of particle formation dynamics and clogging phenomena.