The effect of catalyst pretreatment, using hydrogen or carbon monoxide, on the activity and selectivity of cobalt on ZnO catalyst (10 wt% Co/ZnO) during Fischer-Tropsch synthesis was studied in a fixed bed reactor. Catalyst reduced with hydrogen had higher activity and higher olefin content, and produced less methane than the CO activated catalyst. Catalysts were characterized by means of Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), temperature programmed reduction (TPR), and hydrogen chemisorption (H 2-TPD) with pulse re-oxidation. Reduction of Co 3O 4 occurs in two stages during H 2-TPR and CO-TPR. In the latter case CoO, metallic cobalt, cobalt carbides (Co xC; x = 2 or 3) and carbon (from CO disproportionation) are formed during the reduction process. The existence of Co 0 along with CoO and Co xC, indicates a possibility of two reaction paths for formation of Co xC from CoO: the direct path (CoO → Co xC) and a series reaction via Co 0 (i.e. CoO → Co 0 → Co xC).
- Catalyst characterization
- Co/ZnO catalyst
- Fischer-Tropsch synthesis
- Hydrogen and carbon monoxide activation
ASJC Scopus subject areas
- Process Chemistry and Technology