Wet oxidation

About: Wet oxidation is a research topic. Over the lifetime, 3094 publications have been published within this topic receiving 61536 citations.

Improved MnCeOx Systems for the Catalytic Wet Oxidation (CWO) of Phenol in Wastewater Streams

Abstract: The effects of chemical composition, calcination temperature, and the addition of potassium on the physicochemical properties and reactivity of MnCeO x systems in the catalytic wet oxidation (CWO) of phenol with oxygen (T R = 373 K; P R = 1.0 MPa; W cat /W phenol = 5) have been addressed. Characterization data of "fresh" and "spent" catalysts signal the occurrence of a typically heterogeneous reaction path, the surface reaction between the adsorbed intermediate(s), and activated oxygen species being the rate-determining step (rds). Basic relationships among structural properties, the redox pattern, and CWO activity provide evidence of the main catalyst design requirements. A new synthesis route based on the redox-precipitation reactions of various Mn and Ce precursors then yields MnCeO x , catalysts with improved physicochemical features and superior CWO activity, in comparison to conventional coprecipitated systems.

Alumina-supported noble metal catalysts for destructive oxidation of organic pollutants in effluent from a softwood kraft pulp mill

Abstract: The effectiveness of alumina-supported noble metal catalysts for the destructive oxidation of organic pollutants in effluent from a softwood kraft pulp mill was evaluated in a slurry reactor at 463 K and an oxygen pressure of 1.5 MPa. The effects of catalyst preparation procedures, such as metal loading, calcination, or reduction treatment on the catalytic activities, were also tested. Alumina-supported palladium catalysts were found to be more effective than supported manganese, iron, or platinum catalysts. The rate of oxidation over Pd/alumina catalyst was significantly higher than that of the uncatalyzed reaction. Adding Ce on the alumina support was found to promote the activity of alumina-supported Pt catalyst but inhibit the activity of alumina-supported Pd catalyst. The reaction mechanisms for the catalytic wet oxidation process and the roles of Ce on catalytic activity for destructive oxidation of organic pollutants in wastewater are discussed.

Wet oxidation of lignin model compounds and acetic acid production

Abstract: To investigate the wet oxidation (WO) pathways of acetic acid production from lignin, 2-methoxyphenol, 2,6-dimethoxyphenol, and phenol, as lignin model compounds were oxidized in a batch reactor at a temperature of 300°C, residence times of 10–60 seconds and oxygen supplies of 50–100%. Oxidation experiments using major intermediate products in WO of lignin model compounds, as reactants were also performed.Based on the intermediate products identified by GC/MS and HPLC, WO pathways of lignin model compounds are discussed. Acetic acid production by WO of lignin model compounds is also discussed. It was found that the yield of acetic acid for lignin model compounds was lower, at about 9%. The reason that lignin model compounds cannot produce a large amount of acetic acid may be contributed to the fact that the oxidation of phenols easily forms unsaturated dicarboxylic acids with 4 carbon atoms, which cannot produce a large amount of acetic acid. However, saturated dicarboxylic acids and glutaconic acid can produce a higher yield of acetic acid. Therefore, it is possible to increase the yield of acetic acid from lignin by controlling reaction pathways to increase the formation of saturated dicarboxylic acids and glutaconic acid.

Process for the wet oxidation of organic substances

Abstract: of the Disclosure A process has been developed for the oxidation of organic substances, dissolved or dispersed in an aqueous system, with a gas containing molecular oxygen at elevated temperature and under elevated pressure chiefly to carbon dioxide and water, with subsequent phase separation of the reaction mixture into a gaseous phase substantially containing inert gas, carbon dioxide, steam and organic constituents and a liquid phase substantially containing water, characterized in that the pressure is adjusted, at the given temperature, so that by evaporation of water from the aqueous system, more steam than the exotherm-icity of the oxidation reaction gives rise to,goes into the gaseous phase, which is fed to a heat exchanger in which the amount of heat required to maintain the oxidation temperature is completely or partially transferred to a mixture of water and a gas containing molecular oxygen, which mixture flows in on the other side of the heat exchanger and is subsequently fed to the reactor. A particular advantage of the process of the invention is that, in addition to the oxidation of organic substances, it is possible to fed inorganic constituents, after the oxidative degradation of the organic substances, to a re-use or recovery process.