Synthesis and characterization of Mg-Co catalytic oxide materials for low-temperature N2O decomposition

Abstract

Binary metal Mg-Co oxide materials have been synthesized from Mg-Co hydroxide precursors by a coprecipitation-then-calcination method. The oxide system shows high catalytic activity for low-temperature decomposition of N2O (27 mol%). Using FTIR, XRD, SEM, EA, DSC, BET and GC techniques, the hydrothermal synthesis and chemistry of the double-metal hydroxides have been studied in detail. In anion exchange and XRD studies, a hydrotalcite-like phase is also found to be present in the hydroxides owing to a partial oxidation of Co2+ to Co3+ in air. The precursor subjected to hydrothermal treatment has a higher Mg content, higher crystallinity and is more stable compared to the one aged at room temperature. However, they all give amorphous Mg-Co oxides after calcination. The Mg-Co oxide prepared from the hydrothermally treated precursor has a higher surface area and is more active for N2O decomposition. With this material system, ca. 6 moles of N2O per kg of the precursor materials can be decomposed at 350°C within 1 h.