Influence of Textural Properties of Co@SiO2Catalysts on the Performance of Fischer–Tropsch Synthesis

Abstract

Cobalt core–shell catalysts are advanced materials for Fischer–Tropsch synthesis, which enhance catalytic performance. This study explores the impact of pore diameter on the performance of mesoporous silica-coated cobalt oxide core–shell catalysts (Co@SiO2), maintaining a constant shell thickness while varying the porosity. The synthesis method successfully yields a core–shell morphology with a centralized core, an average core diameter ranging from 30 to 34 nm, a total diameter between 97 and 103 nm, and a SiO2shell thickness of 32.5–34.5 nm. Textural characterization shows a specific surface area from 236 to 771 m2/g, with average pore diameters between 3.5 and 11.8 nm. The results indicate a significant change in the distribution of products, exhibiting more expressive selectivity in the range of C19–C24and C25–C29hydrocarbons with the core–shell catalyst and C30+hydrocarbons with the supported catalyst. It also demonstrates that a decrease in pore diameter of the silica shell leads to significant changes in product distribution. Specifically, a reduction in the pore size from 9.2 nm (Co@SiO2_0.03) to 3.5 nm (Co@SiO2_0.09) results in a 17% increase in selectivity toward the C19–C24fraction and a concomitant 24% decrease in the C25–C29fraction. Furthermore, the silica shell provided a protective effect on the active phase, with no evidence of sintering observed in the spent encapsulated catalysts.