This paper presents the Mossbauer results on the content and type of iron phases in CO-activated and syngas-active precipitated unpromoted ironbased Fischer-Tropsch catalysts in a slurry-phase CSTR at high conversion levels. The distribution of iron phases following CO activation but before active Fischer-Tropsch reaction was 94:6 X-Fe&a-Fe304; during active Fischer-Tropsch reaction, the ,y-Fe& was oxidized to Fe304, until no detectable carbide phase was observed after 453 h onstream. It was observed that there was a strong correlation between iron carbide content and Fisher-Tropsch activity.
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Novel activation of Co/SiOz catalysts prepared by alkoxide method for Fischer-Tropsch synthesis Okabe, K. er ~11. Prcpr.-Am.
Chem. Sot.. Div. Pet. Chem., 1999, 44, (I). 93-96. The result of silica-supported cobalt catalysts promoted by small amounts of noble metals was highly dispersed Fischer-Tropsch catalysts for the production of transportable liquids from remote natural gas fields. The catalysts were prepared by the alkoxide method, in which CO(NO~)~ was dissolved in ethylene glycol, mixed with tetra-ethanol orthosilicate, and hydrolysed to form a glassy gel that was dried and calcined prior to impregnation with the noble metal. Turnover frequencies (TOF) that were two to three times larger than the TOF of conventional catalysts prepared by impregnation were found for the noble metal-promoted catalysts.