Attrition resistance of spray-dried iron F–T catalysts: Effect of activation conditions

The focus of the research reported herein was to investigate the effects of phase changes, as occur during Fe catalyst activation and Fischer–Tropsch synthesis, on Fe catalyst attrition resistance. Different activation conditions (CO, H₂ or syngas) were applied prior to attrition testing to a selected spray-dried Fe catalyst containing 9.1 wt.% binder SiO₂, which had been shown to have the highest attrition resistance in our early study of calcined catalysts. Although, XRD indicated that different Fe phase compositions resulted in the differently activated catalyst samples, chemical attrition was not observed for any of the samples. The BET surface areas of the activated samples were smaller than that of the calcined precursor but no significant changes in pore volume and particle size were found. The attrition resistances of the differently activated catalyst samples were found to be similar to that of the calcined catalyst for this spray-dried Fe catalyst. Attrition resistance was found previously to be governed by catalyst particle density, which has been shown earlier to relate to the SiO₂ network in catalysts. It is therefore suggested that the type and concentration of SiO₂ that is incorporated during the preparation of spray-dried Fe catalysts have a much more significant impact on catalyst attrition than Fe phase change during activation in the presence of CO, H₂ or H₂+CO.