In situ spatiotemporal characterization and analysis of chemical reactions using an ATR-integrated microfluidic reactor

Abstract

Determining kinetic reaction parameters with great detail has been of utmost importance in the field of chemical reaction engineering. However, commonly used experimental and computational methods however are unable to provide sufficiently resolved spatiotemporal information that can aid in the process of understanding these chemical reactions. With our work, we demonstrate the use of a custom designed single-bounce ATR-integrated microfluidic reactor to obtain spatiotemporal resolution for in situ monitoring of chemical reactions. Having a single-bounce ATR accessory allows us to individually address different sensing areas, thereby providing the ability to obtain spatially and temporally resolved information. To further enhance the spatial resolution, we utilize the benefits of synchrotron IR radiation with the smallest beam spot-size ∼150 μm. An on-flow modular microreactor additionally allows us to monitor the chemical reaction in situ, where the temporal characterization can be controlled with the operational flowrate. With a unique combination of experimental measurements and numerical simulations, we characterize and analyse a model S_N2 reaction. For a chemical reaction between benzyl bromide (BB) and sodium azide (SA) to produce benzyl azide (BA), we successfully show the capability of our device to determine the diffusion coefficients of BB and SA as 0.367 ± 0.115 10⁻⁹ m² s⁻¹ and 1.17 ± 0.723 10⁻⁹ m² s⁻¹, respectively. Finally, with the above characteristics of our device, we also calculate a reaction rate of k = 0.0005 (m³s⁻¹mol⁻¹) for the given chemical reaction.