Hydroprocessing of oleic acid for the production of aviation turbine fuel range hydrocarbons over bimetallic Fe-Cu/SiO2-Al2O3 catalysts promoted by Sn, Ti and Zr

Abstract

In this work, the synergistic effects of 1 wt.% Ti, 1 wt.% Zr, and Sn in the range of 0.5−2 wt.% on Fe(3)-Cu(13)/SiO2-Al2O3 catalyst were ascertained through extensive characterization and their subsequent evaluation for the production of aviation turbine fuel range hydrocarbons (C8-C16) via hydroprocessing of oleic acid. The largest surface area (571 m2/g) and pore volume (0.65 cm3/g) were obtained from the N2 physisorption analysis of 1 wt.% Sn-promoted catalyst (E). Cu2O and CuO were identified in the X-ray diffractograms (XRD) of all the catalysts except for catalyst E, which revealed only the peaks of Cu2O owing to the small particle size of CuO below the threshold of detection of XRD. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of both oxidized and reduced phases of Cu, Fe, Ti, Zr and Sn in their respective catalysts, with the highest and lowest atomic compositions of reduced Fe and CuO, respectively, detected in catalyst E; corroborating findings from XRD analyses. The relatively homogeneous dispersion of phases present in catalyst E (revealed by its smallest crystallite size of 5.1 nm) was also evidenced by the weakest metal-support interaction from the H2-TPR analysis of the same catalyst. Hydroprocessing of oleic acid using catalyst E at 320 °C under H2 pressure of 2.1 MPa and reaction time of 8 h resulted in the highest aviation turbine fuel range hydrocarbons selectivity of 76.8 % and yield of 71.7 %. This was due to its high metal dispersion, desirable textural properties and high oxophilic reduced iron content.