Co3O4-KIT-6 composite catalysts: synthesis, characterization, and application in catalytic decomposition of N2O

Two sets of Co3O4-KIT-6 composite catalysts were prepared. To prepare the first set of catalysts, mesoporous silica (KIT-6) samples with different pore sizes were obtained by changing the hydrothermal temperature during synthesis, and the same amount of Co3O4 (10 %) was loaded by impregnation. In the second set, KIT-6 prepared by hydrothermal synthesis at 100 °C was used to load different amounts of Co3O4 (up to 50 %). These materials were characterized by low-angle and wide-angle X-ray diffraction, transmission electron microscopy (TEM), and N2 adsorption–desorption. The TEM results showed that Co3O4 species do not disperse on the inner pores of KIT-6 homogeneously, nor do they form separate Co3O4 particles detached from KIT-6. Rather, Co3O4 crystals grow into the KIT-6 matrix, forming Co3O4-KIT-6 composite grains in some parts of the KIT-6 matrix, whereas there are empty mesoporous silica channels in other parts. The influences of textural properties of KIT-6 support and the loading of Co3O4 on the catalytic activity in N2O decomposition were studied. It was found that the textural properties (e.g., pore size, surface area) of KIT-6 have little effect on the catalytic activity, whereas the amount of Co3O4 directly correlates with the catalytic activity.