Cobalt–iron nano catalysts supported on TiO2–SiO2: Characterization and catalytic performance in Fischer–Tropsch synthesis

Abstract

A series of Co–Fe catalysts supported on TiO2–SiO2 were prepared by the sol–gel method. This research investigated the effects of (Co/Fe)wt.%, the solution pH, different Co/Fe molar ratio, calcination conditions and different promoters on the catalytic performance of cobalt–iron catalysts for the Fisher–Tropsch synthesis (FTS). It was found that the catalyst containing 35wt.% (Co–Fe)/TiO2–SiO2 (Co/Fe molar ratio is 80/20) promoted with 1.5wt.% Cu and calcined in air atmosphere at 600°C for 7h with a heating rate of 3°Cmin−1 is an optimal nano catalyst for converting synthesis gas to light olefins and C5–C12 hydrocarbons. The effects of operational conditions such as the H2/CO ratio, gas hourly space velocity (GHSV), different reaction temperature, and reaction pressure were investigated. The results showed that the best operational conditions for optimal nano catalyst are 250°C, GHSV=2000h−1, H2/CO molar ratio 1/1 under 5bar total pressure. Catalysts and precursors were characterized by, X-ray diffraction (XRD), scanning electron microcopy (SEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), temperature program reduction (TPR) and N2 adsorption–desorption measurements.