The automation of continuous reactions in supercritical CO2: the acid-catalysed etherification of short chain alcohols

We describe a new, automated apparatus for continuous catalytic reactions in supercritical carbon dioxide, scCO2. The reactor incorporates on-line sampling, enabling us to quantify gaseous products such as light alkenes, which would normally be lost in the decompression stage of more conventional supercritical reactors. The on-line sampling is coupled to a gas chromatograph running an isothermal program, which provides automated analysis of the reaction products. We illustrate the operation of the reactor by studying the acid-catalysed etherification of linear alcohols, C1 to C5, both individually and in pairs, over a range of temperatures and pressures equating to a total of 180 different experiments.