Wet Oxidation of Carboxylic Acids with Hydrogen Peroxide. Wet Peroxide Oxidation (WPO®) Process. Optimal Ratios and Role of Fe:Cu:Mn Metals

The wet peroxide oxidation process (WPO(R)) which was developed at the laboratory uses the Fenton's reagent at high temperature. But the reaction efficiency is limited by the accumulation of volatile fatty acids such as oxalic, malonic, succinic and acetic acids (hereafter OMSA). In order to improve the efficiency of the original process, different transition metal ions are tested as catalyst. The experimental results indicate that the system using homogeneous Fe, Cu, and Mn is a promising one. The oxidation of carboxylic acids is quite completed under mild working conditions (T < 100 degrees C, pH = 3, p = 1 atm, reaction time = 1 h, stoichiometric quantity of H2O2 = 1.5). Optimal design methodology is applied to the catalytic mixture Fe:Cu:Mn in order to determine the optimal proportions of each metal. This results in the determination of an important synergistic effect between the metals and an optimal zone. Cu(II), Mn(II) or Fe(II) alone have a slight catalytic effect while the association is very effective on the oxidation of the mixture of carboxylic acids (OMSA). This apparent synergetic effect existing among them can be explained by the main specific roles of Cu(II) and Mn(II) ions. They respectively enhance significantly the oxidation rate of acetic and oxalic acids.