Novel aspects of the physical chemistry of Co/SiO2 Fischer–Tropsch catalyst preparations

Silica-Supported Cobalt Catalysts for Fischer–Tropsch Synthesis: Effects of Calcination Temperature and Support Surface Area on Cobalt Silicate Formation

“…The two oxides can co-exist on the catalyst surface after calcination. Large clusters of Co 3 O 4 can form via oxidative aggregation of small amounts of CoO [5,10]. Following reduction and 48 h FTS, the XRD diffraction peaks of sample 560Co-3 have disappeared, indicating structural irregularity and no cobalt oxide.…”

“…It was found that the loss of surface area after calcination depends on the calcination temperature, the higher the calcination temperature the more significant the surface area loss as is evident in sample 300Co-5. This is due to silica migration which occurs at temperatures higher than 573 K for silica [10,13,19]. It is known that high surface area ([200 m 2 /g) reactive silica favors silica migration [15].…”

“…In this study, the cobalt speciessupport interaction leading to the formation of undesired cobalt silicate phase and, its influence on the activity and performance of the catalyst are presented. Once formed, it is difficult to reduce cobalt silicate to active metallic sites at FTS reaction temperatures [10]. The reported results suggest disagreement on the chemistry and stage at which cobalt silicate form.…”

“…Ernst et al [14] attributed the formation of cobalt silicate during reduction to the reaction of unreduced CoO with silica to form high surface area cobalt orthosilicate: 2CoO þ SiO 2 ! Co 2 SiO 4 Puskas et al [10] proposed a more detailed reaction pathway:…”

Cobalt–silicon mixed oxide nanocomposites by modified sol–gel method

“…FTS reaction appears of particular interest since it is the key step of biomass-to-liquid (BTL) process for the production of biofuels that are forecasted to replace a significant share of fossil fuels in the near future [17,18]. Several recent studies on cobalt-silica systems have shown that the preparation method and the structure of the silica matrix has a marked influence on the type and dispersion of cobalt oxide species, and thus on the properties of the derived catalysts [19][20][21][22][23]. Therefore, there is great interest for the study of new synthesis procedures of these materials as well as for the study of the interactions between the active phase and the silica matrix.…”