Influence of pretreatment conditions on the structure and catalytic performance of supported cobalt catalysts derived from metal-organic frameworks

Supported cobalt catalysts (Co@C-ZnZrO₂ and Co/ZnZrO₂) were prepared through a metal-organic frameworks (MOFs)-mediated synthesis strategy. The influence of MOFs pyrolysis on the structure and Fischer-Tropsch synthesis performance of supported cobalt catalysts was investigated. The crystalline phase and microstructure of supported cobalt catalysts were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), N₂ adsorption-desorption and X-ray photoelectron spectroscopy (XPS). The Co/ZnZrO₂ showed the CO conversion of 18.1% and the C_{5 +} selectivity of 77.4%, whereas the Co@C-ZnZrO₂ exhibited the CO conversion of 8.5% and the C_{5 +} selectivity of 35.2%. The excellent CO conversion for Co/ZnZrO₂ was attributed to the more exposure of active Co sites. Meanwhile, the activity of Co sites on Co@C-ZnZrO₂ catalyst was restricted by the carbon layer, suppressing the adsorption and activation of syngas on Co sites.