Kinetics of Supercritical Water Oxidation. SERDP Compliance Technical Thrust Area

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate This project consists of experiments and theoretical modeling designed to improve our understanding of the detailed chemical kinetics of supercritical water oxidation processes. The objective of the four-year project is to develop working models that accurately predict the oxidation rates and mechanisms for a variety of key organic species over the range of temperatures and pressures important for industrial applications. Our examination of reaction kinetics in supercritical water undertakes in situ measurements of reactants, intermediates, and products using optical spectroscopic techniques, primarily Raman spectroscopy. Our focus is to measure the primary oxidation steps that occur in the oxidation of methanol, higher alcohols, methylene chloride, aromatics, and some simple organic compounds containing nitro groups. We are placing special emphasis on identifying reaction steps that involve hydroxyl radicals, hydroperoxyl radicals, and hydrogen peroxide. The measurements are conducted in two optically accessible reactors located at Sandia's Combustion Research Facility (CRF), the supercritical flow reactor (SFR) and the supercritical constant volume reactor, designed to operate at temperatures and pressures up to 600 °C and 500 MPa. The combination of these two reactors permits reaction rate measurements ranging from 0.1 s to many hours. Project description This project consists of experiments and theoretical modeling designed to improve our understanding of the detailed chemical kinetics of supercritical water oxidation (SCWO) processes. The objective of the four-year project is to develop working models that accurately predict the oxidation rates and mechanisms for a variety of key organic species over the range of temperatures and pressures important for industrial applications. Our examination of reaction kinetics in supercritical water undertakes in situ measurements of reactants, intermediates, and products using optical spectroscopic techniques, primarily Raman spectroscopy. Our focus is to measure the primary oxidation steps that occur in the oxidation of methanol, higher alcohols, methylene chloride, aromatics, and some simple organic compounds containing nitro groups. We are placing special emphasis on identifying reaction steps that involve hydroxyl radicals, hydroperoxyl radicals, and hydrogen peroxide. The measurements are conducted in two optically accessible reactors located at Sandia's Combustion Research Facility (CRF), the supercritical flow reactor (SFR) and the supercritical constant volume reactor (SCVR), designed t...

Review on Mechanisms and Kinetics for Supercritical Water Oxidation Processes

“…Although Yong and Matsunura [100,101] deduced the reaction pathway of benzene decomposition in SCWG that benzene formed phenol and gas, directly or through naphthalene as an intermediate medium, into char and other liquid products, and mainly transformed to phenol under the oxygen-rich condition in SCWO. Dinaro et al [102] [32].…”

“…Savage [2] pointed out that, compared with other organic solvents, subcritical/supercritical water is conducive to the realization of green, environment-friendly chemical Li et al [30] regarded acetic acid as a refractory intermediate for hydrocarbons degradation, which occurred in the oxidation of all the alcohols except methanol [31]. In the SCWO of aromatic hydrocarbons, understanding the oxidation chemistry of phenol is pivotal since phenol is a stable species [32][33][34], which would degrade into various carboxylic acids in the subsequent degradation process. The degradation of carboxylic acids in SCWO proceeded with the sequential oxidation from higher molecular weight to lower molecular weight [35].…”