(71k) Flow Regimes in a Catalyst Trap Microreactor

Multiphase reactions play a critical role in refining, gas processing, chemical, biochemical, pharmaceutical, and environmental industries. To be able to efficiently carry out multiphase reactions in micoreactors would benefit chemical process miniaturization in these industries. The primary goal of this study was to achieve a flow configuration with low mass transport resistance to enhance interaction of gas, liquid and solid phases for an exothermic multiphase hydrogenation reaction.

In this study, we propose the use of a novel catalyst trap microreactor. The reactor employs a three-channel design, in which catalyst particles are trapped in the liquid channel by an array of posts. The posts are arranged in a trapezoidal configuration, which can hold particles ranging from 35 to 50 mm. A cross flow configuration is achieved in this system, wherein gas diffuses at a perpendicular angle to the liquid flow through a slotted wall. Experiments were carried out from approximately 25-50 C, below 100 psia, and 0.01 to 0.5-mL/min liquid flow rate, gas flow rates ranging from 2 to 20 sccm. The study focuses mainly on observing the two-phase flow behavior in the catalyst trap microreactor. Three different flow regimes were observed in the process, namely liquid dominated churn flow (signifying the chaotic and oscillatory behavior of the two-phase flow in the microreactor), gas dominated churn flow and a transitional flow. It has been shown that the transitional flow was best suited for the multiphase mixing in microreactors. Flow behavior results will be discussed in detail.