Characterization of cobalt-supported catalyst

Abstract

It was reported that the characteristics of cobalt - supported catalyst present a marked contrast with the methods of preparation, and in the case of Co/$SiO_2$, several kinds of cobalt species are formed after calcination. Catalysts were prepared by an impregnation method using cobalt acetate and cobalt nitrate. Physicochemical characterization of prepared Co/$SiO_2$ catalysts by cobalt acetate and cobalt nitrate were carried out to reveal the interaction between cobalt and $SiO_2$ about using PAS, XRD, TPDe, TPR, IR techniques. Interaction modes between cobalt and silica present a contrast with the nature of anions of cobalt source. It was found that several kinds of cobalt species are formed on Co/$SiO_2$. These species are assigned to $Co_3O_4$, mixed oxide, and $Co^{2+}$ in Td. Their proportions strongly depend on the starting salt, cobalt content, and preparation method. In either case, cobalt has octahedral symmetry before calcination, but in the case of Co/$SiO_2$ (A), it changes tetrahedral symmetry during calcination. These results are interpreted to be related to the interaction modes of cobalt-silica and cobalt-anion.