Catalytic wet oxidation of glucose as a model compound for organic waste using transition metal oxide powders

Abstract

The growing concerns over waste treatment demand an improvement of available technologies for new system development. Catalytic wet oxidation (CWO) is an effective and environmentally friendly process for deconstructing organic waste materials using oxygen or air in the presence of a catalyst. Heterogeneous catalysis using unsupported transition metal oxides are best suited for CWO due to their high reducibility and insolubility of active phases in aqueous solvents. In this study, transition metal oxide powders such as Fe2O3, CuO, NiO, MnO2 and mixed oxide powder Co1.5Mn1.5O4, were used as catalysts for the treatment of d-glucose, a model compound for organic waste. Pre-oxidation of the NiO and MnO2 metal oxide powders was performed at 700 °C and 500 °C for 60 min, respectively, to reduce the metallic Ni content and increase the Mn2O3 content due to its high redox potential value. BET surface area of oxidised NiO was the highest. XRD and SEM provides information about the prepared catalyst composition and microstructures. The prepared catalysts were used to treat glucose across a temperature range of 150–210 °C for 60 min using 20 bar O2 pressure. The catalytic performance of the metal oxide powders reached a COD reduction of 70–77%, with the highest reduction generated by CuO. All catalysts behaved similarly at high severity factor (above 3) with a better performance overall compared to non-catalytic glucose degradations.