The Catalytic Wet Air Oxidation (CWAO) of aqueous solutions of p-hydroxybenzoic acid (a phenolic compound typically found in olive mill wastewaters) has been carried out over titania supported ruthenium catalysts (Ru/TiO2) at 140°C and 50 bar air. The ruthenium catalysts were prepared by the sol-gel method, either from solutions containing the Ru and Ti precursors, or by impregnation with ethanolic solutions of ruthenium acetylacetonate of TiO2 prepared by sol-gel). Ru catalysts were able to remove most of the Total Organic Carbon (TOC) of aqueous solutions of p-hydroxybenzoic acid. The most important intermediates detected were phenol, hydroquinone and maleic acid. The influence of catalyst preparation, of drying of the gel and of pre-calcination of the catalyst precursor at 300°C under oxygen before reduction on the performances for conversion of p-hydroxybenzoic acid have been studied.
M. Triki, D. Pham Minh, Z. Ksibi, A. Ghorbel, P. Gallezot, M. Besson
Wet air oxidation, Olive mill wastewaters, Sol-gel, Titanium oxide, Ruthenium catalysts