Investigation of the effect of catalyst support on oleic acid catalytic deoxygenation for green diesel production

Abstract

The presence of certain oxygenated species has led to the development of green diesel produced using deoxygenation (DO) technology to replace conventional biodiesel. The study focused on the effects of the supports on the deoxygenation of oleic acid using the CoMo catalyst. The results of this study revealed that the Molybdenum and Cobalt species have a significant influence on the reactivity and distribution of the product. The CoMo-based catalyst supported on Cerium oxide (CeO₂), Titanium dioxide (TiO₂), activated carbon (AC), and Aluminum oxide (Al₂O₃) were prepared by wet impregnation method and then calcinated under 20 mL min⁻¹ N₂ flow for 4 h at a temperature of 550 °C. The prepared catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Thermo-Gravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) analysis. The influence of support type (activated carbon, Al₂O₂, CeO₂, and TiO₂) on the removal of various oxygenated functional groups was examined during the deoxygenation of oleic acid using supported CoMo catalysts at 350 °C and atmospheric pressure. The deoxygenated liquid products were characterized by Fourier-transform infrared spectroscopy (FTIR), Gas Chromatography–Mass Spectrometry (GC–MS), Higher heating value (HHV), and CHNOS analysis. The yield of hydrocarbons increased in the order Blank < CoMo/TiO₂ < CoMo/CeO₂ < CoMo/Al₂O₃ < CoMo/AC. Based on the study results, CoMo/AC is the most active catalyst with 93.20% hydrocarbon yield for 2 h. at 350 °C and 300 rpm in the absence of hydrogen. However, a significant deoxygenation reaction was still observed for the catalysts having CoMo supported on Al₂O₃, CeO₂, and TiO₂. In summary, CoMo/AC demonstrates better catalytic performance, attributed to its favorable physicochemical properties.