Effect of CaO promotion on the performance of a precipitated iron Fischer-Tropsch catalyst

Three catalysts containing CaO promoter with nominal compositions 100 Fe/3 Cu/4 K/x Ca/16 SiO2, where x = 0, 2 or 6, were synthesized and their reduction behavior was characterized under both isothermal and temperature programmed conditions. In fixed bed reactor studies of Fischer-Tropsch synthesis it was found that the catalyst activity decreased, whereas the gaseous hydrocarbon selectivity increased, with increasing amount of CaO promoter. Decrease in activity is attributed to both lower surface area and lower, reducibility with increasing amount of CaO promoter. During testing in a stirred tank slurry reactor it was found that the 100 Fe/3 Cu/4 K/2 Ca/16 SiO2catalyst was less active (about 15%) than the baseline catalyst (x = 0) and its deactivation rate was higher. At reaction pressure of 1.48 MPa, methane selectivity on the CaO promoted catalyst was higher than that of the baseline catalyst. Selectivity of the CaO promoted catalyst improved during testing at a higher reaction pressure (2.17 MPa) whereas selectivity of the baseline catalyst was essentially independent of reaction pressure.

Effect of CaO promotion on the performance of a precipitated iron Fischer-Tropsch catalyst Conference Paper