(8a) Achieving Ultrafast Dynamic Catalytic Operation Using Microcapillary Flow Reactors

The fundamental shift from centralized to distributed chemical systems has driven innovation in microreactor technology and reactor operation. While those small-footprint systems don’t benefit from economies of scale, they can be intensified to enhance production. Dynamic catalysis is a promising method for intensifying processes with modulation of reaction inputs like temperature or pressure, in place of traditional static operation. Several studies have demonstrated rate enhancements from dynamic operation, which can be attributed to distinct phenomena: tuning of surface coverage for optimal energetics, operation in favorable thermodynamic conditions for each catalytic step, or periodic surface cleaning. To study those phenomena and their contribution to catalytic enhancement, the field of dynamic catalysis needs reactors that can achieve sharp input modulation, and deconvolute competing transport effects. In this work, we have designed a pressure-modulated microreactor capable of 25Hz periodic switching with minimal mixing at millisecond-resolution. Experiments and computational fluid dynamics were used to characterize the reactor and choose optimal parameters. Pressure tests showed that operation at a high flowrate of 1000 sccm resulted in a 2.5 bar pressure drop. Residence time distributions validated the plug flow assumption with a low degree of mixing and demonstrated space velocities fast enough to achieve residence times of 15-40ms at 2-14 psi pressure. The millisecond-resolution allows operation at high switching frequency and ensures fine tuning of surface coverage as well as transport deconvolution for short contact time dynamic reactions.