Optimization of Cs content in Co–Mn–Al mixed oxide as catalyst for N2O decomposition

A series of Co–Mn–Al mixed oxide catalysts with different Cs contents (0.5–4.6 wt%) was prepared by calcination of Co–Mn–Al hydrotalcite (Co:Mn:Al = 4:1:1), followed by impregnation by cesium salt (CsNO3, Cs2CO3) using the pore filling method. Chemical analysis, N2 sorption, temperature programmed reduction (TPR)-H2, temperature programmed desorption (TPD)-CO2 and TPD-NH3 and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. All prepared catalysts were tested for N2O catalytic decomposition in inert gas and in the presence of oxygen, water vapor and nitric oxide. The influence of Cs salts used for catalyst preparation and cesium content on catalyst activity were studied. A significant increase in catalytic activity with increasing amount of cesium promoter was observed without respect to the Cs precursor. The strong promotional effect of cesium is electronic in nature and is discussed in term of changes in surface composition and catalyst reducibility.