Design and operational limits of an ATR-FTIR spectroscopic microreactor for investigating reactions at liquid–solid interface

• An attenuated total reflection microfluidic cell was designed.
• Optimization of the inner flow was obtained by 3D numerical simulations.
• Transport of the reactant is characterized by convection and diffusion.
• Criteria to operate under chemical control are presented.
• CO adsorption in aqueous phase on platinum thin film is studied.

This work presents the design and characterization of an optimized attenuated total reflection (ATR) microfluidic cell to assess intrinsic kinetic parameters of reactions at the liquid/solid interface under chemical control. A theoretical and computational investigation of convection, diffusion, and adsorption is presented. Transport dynamics in transient-flow experiments is characterized by a convective and diffusive mass transport of the solution species to the surface of the ATR crystal. Criteria to determine the mass transport limitations of the adsorption process are presented as a function of the Damköhler and Biot numbers. The CO adsorption on a thin film of platinum is studied in order to validate the model.