Catalytic decomposition of nitrous oxide over catalysts prepared from Co/Mg-Mn/Al hydrotalcite-like compounds

Co/Mg-Mn/Al hydrotalcite-like compounds with Co:Mg:Mn:Al molar ratios of 4:0:2:0, 2:2:2:0, 2:2:1:1, 4:0:1:1, 4:0:0:2 and 2:2:0:2 were prepared by coprecipitation method. The mixed oxides obtained by calcination at 500 °C were characterized using various techniques (XRD, IR, BET surface area measurements, TPD and TPR). The activities of calcined hydrotalcites were tested for N2O decomposition in an inert gas, and in the presence of oxygen and water vapor as well. Among the catalysts screened, the catalyst prepared from Co hydrotalcite containing Al and Mn as the trivalent cation showed the highest activity, which was retained in the presence of oxygen but was inhibited by water vapor. Redox properties of the catalysts play an important role in the reaction and optimum extent of reduction is necessary for achievement of the highest catalytic activity.