Oil-Dispersed α-Fe_2O_3 Nanoparticles as a Catalyst for Improving Heavy Oil Oxidation

摘要

Oil-dispersed alpha-Fe2O3 nanocatalysts were prepared by coating alpha-Fe2O3 nanoparticles with oleic acid (OA). Mossbauer spectroscopy, X-ray diffraction, and field emission scanning electron microscopy were used to characterize alpha-Fe2O3 and alpha-Fe2O3@OA. Their impact on the oxidation process of heavy oil was evaluated using a porous medium thermo-effect cell and thermogravimetry-infrared spectroscopy coupled with isoconversional kinetic analysis. Compared with alpha-Fe2O3, alpha-Fe2O3@OA more efficiently catalyzed the combustion of heavy oil due to its good dispersion in heavy oil. alpha-Fe2O3 was found to be transformed into smaller size magnetite (Fe3O4), maghemite (gamma-Fe2O3), and alpha-Fe2O3 during heavy oil combustion. Fe2O3@OA reduced the activation energy from a maximum of 537 to 246 kJ/mol, which considerably facilitates fuel formation and makes an easier transition from fuel formation to its combustion in the high-temperature oxidation (HTO) stage, thus shifting HTO into lower temperatures. These enhanced performances in the heavy oil combustion by alpha-Fe2O3@OA could be favorable for improving the efficiency of the in situ combustion (ISC) technique in oilfields.