Effect of support on the catalytic activity of Co3O4-Cs deposited on open-cell ceramic foams for N2O decomposition

Cobalt mixed oxide with cesium promoter was deposited on different ceramic open-cell foams (Al2O3 + SiO2, ZrO2 and SiO2 + Al2O3 + C-graphite, Lanik Ltd., Czech Republic) by wet impregnation method. The catalysts were tested for N2O decomposition and characterized by AAS, XRD, TPR-H-2, FTIR, Raman, XPS, SEM and nitrogen adsorption. The same impregnation procedure resulted in different amounts of deposited Co3O4-Cs on each support and different dispersion of Co3O4 and Cs on the surface. The Al2O3 + SiO2 (Al-Si) based ceramic foam was recognized as the most suitable support. The difference in the catalytic activity of unsupported Co3O4 Cs and Co-Cs/Al-Si could be explained in terms of different dispersion levels of individual components on the support, leading to changes in the Cs/Co surface molar ratio of atoms in close contact and subsequent changes in reducibility. Direct correlation of specific rate constant for N2O decomposition and surface Cs/Co molar ratio was found.