Oxidation of hexanal to hexanoic acid in supercritical carbon dioxide: 1. Experiments in a tubular reactor and modeling

The goal of this work is to develop a new, continuous process for the uncatalyzed partial oxidation of hexanal to hexanoic acid in supercritical CO2 as reaction medium. The experiments were conducted in the temperature range of 110–150 °C, at 25 MPa and reaction times up to 56 s. The results are correlated with calculations by a kinetic model consisting of 28 elementary reactions. The model calculation is in good accordance with the measured hexanal to hexanoic acid ratio. Surprisingly the model predicts another reaction pathway than assumed for the liquid phase oxidation. Here more studies are necessary. In summary, the results are promising in view of a technical application.