Enhancement of catalytic wet air oxidation of tert-amyl methyl ether by the addition of Sn and CeO2 to Rh/Al2O3 catalysts

The Rh and Rh–Sn supported catalyst on γ-Al2O3 and γ-Al2O3–CeO2 (loading 1, 5 and 20 Ce wt%) were characterized by means of electron microscopy (TEM), temperature programmed reduction (TPR), Fourier transformed infrared of CO adsorption (FTIR-CO) and X-ray photoelectron spectroscopy (XPS). The catalysts were tested in the catalytic wet air oxidation of an aqueous solution of 227 ppm of TAME and 1 g/L of catalyst (120 °C and 10 bar of oxygen partial pressure). The rhodium monometallic catalysts showed an increase in the activity with the load of cerium oxide in the catalyst. The coexistence of Rh°/Rhδ+ and Ce4+/Ce3+ redox couples facilitates the activation of TAME and hence the catalytic activity and selectivity to mineralization. The addition of Snδ+ enhances the activity and selectivity; this is explained by assuming that Snδ+ acts as Lewis acid sites trapping the TAME molecules for further oxidation on rhodium metal particles.