Effect of polymer weight on the Fischer-Tropsch Synthesis kinetics over the Iron oxide /paraffin/polymer systems as nanocatalysts

This study was set to propose and understand the mechanism of the reactions for the Fischer-Tropsch Synthesis FTS process using iron oxide nanoparticles as nanocatalysts in the form of iron oxide/paraffin/polymer systems (Fe3O4/Pr/PEG); the polymer was used as a stabilizing agent and to prevent agglomeration of iron oxide nanoparticles. All experiments were done under a stream of the inert gas atmosphere and a stirrer. However, the reactor was slurry type at 20 atm, 1:1 ratio of H2:CO feed reactions and a syngas load of 10 Lh-1 with a temperature range of 220-320 ᵒC. The obtained nanocatalysts were based on the iron oxide/paraffin/Poly ethylene glycol (Fe3O4/Pr/PEG) system, and the weights of polyethylene glycol were 6 and 10 g. The success of the synthesis of the nanocatalysts system has been ascertained using X-ray diffraction (XRD) analysis, Dynamic light scattering (DLS), Atomic force microscopy (AFM), and Scanning electron microscopy (FE-SEM) analysis. XRD results further support the FE-SEM images and AFM results, which confirmed the presence of dispersed iron oxide nanoparticles (Fe3O4 NPs) on the polymer surface. Fischer–Tropsch Synthesis (FTS) results confirmed that the Fe3O4/Pr/ 10 g PEG system gave CO conversion and methane formation higher than other systems while using 6 grams of Polyethylene glycol (PEG) gave high formation of liquid hydrocarbons. All thermodynamics function values (∆G, ∆H, and ∆S) were obtained positively, and the adsorption type is chemical adsorption. The experimental data were fitted into the following kinetic models: pseudo-first order, Elovich model, and intra-particle diffusion model. It was observed that intra-particle diffusion (in case 6 g PEG used) and Elovich models (in case 10 g PEG used) describe the adsorption with a high correlation factor (R2) better than the pseudo-first-order kinetic model.