Catalytic wet oxidation of ethylene glycol: kinetics of reaction on a Mn-Ce-O catalyst

Wet oxidation (WO) is an ambitious key technology looking for the treatment of different industrial effluents, safeguarding environmental problems. Ethylene glycol (EG) has been found to be a refractory compound. Different heterogeneous catalysts in slurry conditions using a high-pressure batch reactor at 160-220 degreesC and 15-25 bar of oxygen partial pressure were studied for enhancing WO efficiency. The activity of commercial catalysts (Pt/Al2O3, CuO-ZnO/Al2O3, CuO-MnOx/Al2O3, Fe2O3-MnOx and CuO-MnOx) was compared with the one related to various catalysts prepared in our laboratory (Ag-Ce-O, Mn-Ce-O and Ce-O). The Mn-Ce-O catalyst showed very high activity in terms of total oxidation of EG as well as total organic carbon reductions (up to 99.3%). Formic acid was identified as the only intermediate compound and the pH evolution was related with its formation/oxidation. Kinetic studies revealed activation energies of 31.8 and 45.0kJ/mol concerning the two step mechanism of EG degradation by means of Mn-Ce-O. The catalyst stability was observed in terms of metal leaching and carbon adsorption, and its texture and morphology were analyzed by SEM, TEM, EDXS and SAED, Whiskers of MnOOH and/or beta-MnO2 were detected. (C) 2004 Elsevier Ltd. All rights reserved.