The effect of the precursor on the characteristics of Co/SiO2 catalysts Original Research Article

The effect of the precursor on the characteristics of the Co/SiO2 catalysts prepared from Co(NO3)2, Co2(CO)8 and Co4(CO)12 was determined. The near-surface reduction was clearly lower for the Co2(CO)8 derived catalyst than for the Co4(CO)12 based one. The hydrogen chemisorption, CO desorption, XRD and XPS measurements indicated that the dispersion of the metallic species decreased in the precursor order Co2(CO)8 > Co4(CO)12 ≫ Co(NO3)2. The TPD studies showed that CO was more strongly adsorbed on catalysts derived from carbonyls than on those based on nitrate, resulting in greater initial activity in CO hydrogenation. In pulsed CO hydrogenation reactions, the selectivity of the Co2(CO)8 derived catalyst differed from the other two. Thus, despite the well documented transformation of the Co2(CO)8 to Co4(CO)12 on the silica support, the supported catalysts derived from these two precursors exhibited distinct characteristics and reactivity.