| Abstract
| - Raman spectroscopy is used as an in situ diagnostic to measure the oxidation of ethanol byoxygen in supercritical water. An elementary reaction mechanism based on the work of Marinovis shown to predict accurately many of the experimental observations. Experimental measurements are reported at 24.5 MPa over a temperature range of 410−470 °C in supercritical waterwith reaction times ranging from 0.5 to 3.0 s. Concentrations of ethanol, acetaldehyde,formaldehyde, methanol, carbon monoxide, carbon dioxide, and hydrogen peroxide are measuredas functions of time and temperature. The data show that the formaldehyde is the primarystable organic intermediate. An elementary reaction mechanism, modified for supercritical waterconditions and supplemented with key methylperoxyl reactions, is used to interpret theobservations. The experimental data are consistent with the purely radical chain oxidationprocess represented by this mechanism. Analysis of the mechanism identifies the primaryoxidation pathway proceeding through acetaldehyde with oxidation routes involving initialabstraction of the hydroxyl hydrogen or a hydrogen atom from the secondary carbon. A pathwayoriginating from H-abstraction from the methyl group of the ethanol molecule contributes tothe overall conversion to a lesser degree.
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