Synthesis and characterization of Mg–Co catalytic oxide materials forlow-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 N ₂ O (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 Co ²⁺ to Co ³⁺ 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 N ₂ O decomposition. With this material system, ca. 6 moles of N ₂ O per kg of the precursor materials can be decomposed at 350 °C within 1 h.