Highly dispersed cobalt Fischer–Tropsch synthesis catalysts supported on γ-Al2O3, CNTs, and graphene nanosheet using chemical vapor deposition

Authors

• Iraj Kazemnejad ¹
• Alireza Feizbakhsh * ¹
• Ali Niazi ¹
• Ahmad Tavasoli ²

1. Department of Chemistry, Central Tehran Branch, Islamic Azad University, Tehran, Iran
2. School of Chemistry, College of Science, University of Tehran, Tehran, Iran

Abstract

Highly dispersed 15.0 wt% cobalt catalysts were prepared on γ-Al₂O₃, carbon nanotubes (CNTs), and graphene nanosheet (GNS) using chemical vapor deposition (CVD) procedure. The physico-chemical properties of the catalysts were studied by inductively coupled plasma (ICP), Brunauer–Emmett–Teller (BET), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), and temperature-programmed reduction (TPR) techniques, and the Fischer–Tropsch synthesis (FTS) performance of the catalysts was assessed at 220 °C, 18 bar, H₂/CO = 2 and feed flow rate of 45 ml/min g cat. Based on BET results, Co/GNS catalyst provided highest surface area in comparison to the other catalysts. XRD and FESEM results revealed that CVD method prepared smaller particles on GNS compared to the other supports and resulted in the most dispersed metal particles on GNS according to H₂-chemisorption results. The performance of Co/Al₂O₃ catalyst prepared by CVD method was compared with conventional 15 wt% Co/Al₂O₃ catalyst prepared by impregnation method. The Co/Al₂O₃ catalyst prepared with CVD method showed 5.3% higher %CO conversion and 2.1% lower C₅⁺ selectivity as compared with the Co/Al₂O₃ catalysts prepared by impregnation method. Among three catalysts prepared by CVD, Co/GNS showed higher %CO conversion of 78.4% and C₅⁺ selectivity of 70.3%. Co/γ-Al₂O₃ catalyst showed higher stability.

Keywords

• Selectivity
• Activity
• Chemical vapor deposition
• Cobalt
• Dispersion