A micro packed-bed reactor for chemical synthesis

A microchemical device has been fabricated using deep-reactive-ion etch technology for the purpose of gas-liquid contacting and for use as a micro packed-bed reactor. A 4 mu L volume reaction chamber holds the packing as reactants are fed continuously in a co-current fashion and distributed at the inlet of the bed. The gas and liquid reactant streams are brought into contact by a series of interleaved, high-aspect ratio (25 mu m X 300 lambda m) inlet channels. The inlet channels meet at the inlet of the reaction chamber which is sized to accommodate a variety of packing materials. These packing materials are fed into the reaction chamber through separate inlets and are held in place by a grating of 40 mu m wide posts with 25 mu m gaps. Several types of materials have been successfully loaded into the reaction chamber, such as glass spheres 50 mu m diameter, polystyrene beads, and granular catalyst particles. Fluid flow regimes and flow behavior have been characterized with and without packing in the reaction chamber. Go-current flow of the gas and liquid has been visualized in-situ to ascertain the nature of the two-phase flow over the packing and to determine the efficiency of the fluid-solid contacting. Granular catalysts of various sizes have been loaded into the micro packed-bed reactor and several classical heterogeneous gas-liquid reactions have been performed, including hydrogenation reactions. Mass transfer effects have been characterized to gauge the efficiency of gas-liquid contacting and to establish the process capabilities of the microchemical device as compared to conventional large-scale multiphase reactors.