This research examines how varying cobalt particle sizes and support pore sizes affect CO diffusion in Fischer-Tropsch synthesis (FTS). It explores cobalt catalysts deposited on perlite (P) and its modified version (S) with weight loadings ranging from 5% to 20%. N2 adsorption-desorption, BET analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), hydrogen temperature-programmed desorption (H2-TPD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR) analyses were utilized for characterization. The results designate that higher cobalt loading on the modified support (S) decreases CH4 selectivity while enhancing selectivity towards C5+ hydrocarbons. Despite larger cobalt particles in 15CP compared to 15CS, 15CP exhibits higher CH4 selectivity and reduced C5+ selectivity because of CO diffusion limitations and smaller pore size. DFT calculations reveal product selectivity depends on FTS mechanism and cobalt cluster size influences reaction pathways, with smaller clusters favoring CO insertion and larger clusters favoring carbide mechanisms.

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