Scalable microfabricated multiphase reactors for direct fluorination reactions

Abstract

We report a stacked multichannel microfabricated gas-liquid reactor to carry out direct fluorination reactions with a volumetric liquid throughput of 81 ml/hr, which translates to grams per hour of fluorinated product. Fluorinated compounds are rarely synthesized by direct fluorination in conventional macroscale reactors due to the difficulties in controlling the large heat of reaction and the poor selectivity of the process. The substantial throughput and inherent safety of our microreactor makes it a promising drug discovery tool. We use pressure drop gas and liquid inlet channels to ensure uniform gas-liquid flow distribution over a large number of reaction channels operating in parallel with single gas and liquid inlet and outlet ports. Microfluidic channels are formed in a (100) silicon substrate using standard photolithographic techniques and nested potassium hydroxide etching. Twenty reaction channels are formed in each silicon layer. Gas and liquid are introduced to all layers through vertical fluidic connections. Alternate layers of drilled Pyrex are anodically bonded to the silicon to provide the vertical fluidic connections. Fluorescence microscopy of the gas-liquid flow regimes obtained in individual reaction channels indicates uniform flow distribution within one reaction layer and across different layers.