We demonstrate a rapid fabrication procedure for solvent-resistant microfluidic devices based on the perfluoropolyether (PFPE) SIFEL. We carefully modified the poly-dimethylsiloxane (PDMS) micromolding procedure, such that it can still be executed using the standard facilities for PDMS devices. Most importantly, devices with a thin SIFEL layer for the patterned channels and a PDMS support layer on top offered the best of two worlds in terms of chemical and mechanical stability during fabrication and use. Tests revealed that these devices overcome two important drawbacks of PDMS devices: (i) incompatibility with almost all non-aqueous solvents, and (ii) leaching of oligomer into solution. The potential of our device is shown by performing a relevant organic synthesis reaction with aggressive reactants and solvents. PFPE-PDMS devices will greatly expand the application window of micromolded devices.

The step response, including various startup procedures, in a three-phase microreactor of 2 mm internal diameter packed with nonporous particles of 100 μm is reported. We demonstrate that the bed behaves reproducibly through many cycles of operating conditions. Interestingly, we find that the different startup procedures have little effect on the steady state that is achieved. In other words, minimal hysteresis was observed, in sharp contrast to larger-scale reactors with larger particles where prewetting has a remarkable impact on the hydrodynamic behavior. The powder-packed beds have very high liquid saturation values, and prewetting is not needed. At least four liquid-residence times were needed to achieve stable pressure drop and dispersion values over the bed. This indicates that the hydrodynamic response into a stable operation may well be the limiting factor that determines the rate at which kinetic experiments can be performed in high-throughput equipment.

This paper describes the effect of volatility on residence time distribution and conversion in multiphase reactors. This is relevant for the many processes where substantial vaporization of the liquid feed occurs. The typical situation is that the evaporated molecules not only lower the concentration in the liquid phase but also travel faster through the reactor. Our complete model uses two mobile zones, one for the liquid phase and one for the gas phase, with dispersion in each zone and mutual mass transfer. In short, this work can be thought of as extending the popular Piston-Dispersion-Exchange model by adding mobility and dispersion to the second zone. We explore the entire parameter space for our model numerically. We describe quantitatively how the mean residence time of a component decreases when it significantly evaporates to a faster-moving gas phase. We explore how slow mass transfer contributes to the broadening of the residence time distribution. Experimentally, we validated the model in a more limited parameter space in a gas–liquid micro-packed bed with volatile compounds (isopentane, pentane, and 2,2 dimethylbutane) and non-volatile compounds (1-methylethyl benzene) in different solvents (tetradecane and 1-nonanol). The effect of volatility on conversion was analyzed for an n̲th-order liquid-phase reaction at different mass-transfer rates. Wherever possible, we extract from the detailed numerical model practical engineering correlations for average residence time and conversion. The results presented in this work teach whether reactant volatility should be considered in a reactor design.