Fundamental research on direct NO decomposition is still needed for the design of a sufficiently active, stable and selective catalyst. Co-based mixed oxides promoted by alkali metals are promising catalysts for direct NO decomposition, but which parameters play the key role in NO decomposition over mixed oxide catalysts? How do applied preparation conditions affect the obtained catalyst’s properties?

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Co3O4 modified with Cs was deposited on an α-Al2O3 open-cell foam, characterized by X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction by hydrogen (TPR-H2), and scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDAX) and tested for the low-temperature decomposition of N2O. The aim was to study the effect of the amount of active phase on N2O conversion. Three different approaches were used: (i) the application of foam supports with different cell sizes, (ii) influencing catalyst loading using impregnation solutions with different precursor concentrations, and (iii) deposition of the active phase precursor by repeated immersion–calcination cycles. Increasing the geometric surface area of the support, and thus catalyst loading, was successfully done using the support with higher pore densities. A higher loading was also achieved by increasing the nitrate precursor concentration in the impregnation solution. In both cases, the catalyst activity increased with an increase in the amount of the active phase. Compared to that, a repeated impregnation procedure can ensure the deposition of a higher amount of active phase in comparison to that obtained with one-step impregnation, but only the last layer is used in the reaction and the rest of the active phase remains unutilized, which makes this type of preparation unfavorable. The high catalytic activity was preserved at 450 °C even in the presence of O2, H2O, and NO.