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.