Hydrogenation in flow: Homogeneous and heterogeneous catalysis using Teflon AF-2400 to effect gas–liquid contact at elevated pressure

A Tube-in-Tube reactor/injector has been developed, based on a gas-permeable Teflon AF-2400 membrane, which allows both heterogeneous and homogeneous catalytic hydrogenation reactions to be efficiently carried out at elevated pressure in flow, thereby increasing the safety profile of these reactions. Measurements of the gas permeation through the tubing and uptake into solution, using both a burette method and a novel computer-assisted ‘bubble counting’ technique, indicate that permeation/dissolution follows Henry's law and that saturation is achieved extremely rapidly. The same gas-permeable membrane has also been shown to efficiently effect removal of excess unreacted hydrogen, thus enabling further downstream reaction/processing.