The total oxidation of aqueous solutions of carboxylic acids by air was studied in a slurry reactor over the temperautre range 180-200deg C and oxygen partial pressure of 0.3-1.8 MPa in the presence of a 2.8%Ru/TiO_2 catlayst. The influence of various parameters is presented: the catalytic wet air oxidation of succinic acid is 0 order with respect to succinic acid; the order with respect to oxygen pressure is 0.4, and the activatio energy is ca. 125 kJ/mol. It was found that acetic acid, which is one of the intermediates, and CO_2 have no retarding effect on the total organic carobn abatement rate of succinic acid. Substitution of one hydrogen atom of th emethyl group in acetic acid by Cl, OH, or NH_2 gives an increase of the oxidation rate. However, it was propsoed that the low activity of acetic acid oxidations is due not only to the difficulty to oxidize the methyl group, but also to the low adsorptiion coefficient of acetic acid on ruthenium surface. Inorganic salts, such as sodium chloride, only slightly decrease the oxidation rate of acetic acid.The absence of metal ions (Ru, Ti) in the effluents after reaction and the absence fo particle sintering indicate also a high stability of the catalyst under teh conditions employed. The catalyst canb e recycled without loss of activity after the second run. The activity becomes stable after the attainmetn of a steady-state coverage of the Ru particles by oxygen. The study of hte effect of reduction-oxidation treatmetns of the catalyst showed that the activity depends on the oxidation state of the surface.
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