Dispersed Fe₂O₃ nanoparticles preparation in heavy oil and their uptake of asphaltenes

A sol-gel/emulsion technique was used to prepare dispersed Fe₂O₃ nanoparticles in heavy oil and their affinity toward asphaltenes adsorption was assessed. The nanoparticles were identified using XRD and EDX and their mean diameter, 35 ± 5 nm, was based on TEM estimates. Kinetic experiments showed that for the in situ prepared and commercial Fe₂O₃ nanoparticles constant uptake is essentially achieved in the first 1 h, and DCM washing suggested mostly physisorbed hydrocarbons. The in situ prepared nanoparticles displayed much higher, 2.6 ± 0.12 g/g, and much more selective asphaltene uptake. Increasing the concentration of the in situ prepared particles revealed a declining trend in the uptake versus equilibrium asphaltene concentration. Experiments to explore the effect of preparation parameters showed that water did not seem to influence the hydrocarbon uptake for the commercial Fe₂O₃ nanoparticles, while heat treatment of the oil phase in the presence of the nanoparticles reduced their uptake. Centrifuging the nanoparticle together with the adsorbed asphaltenes did not reduce the viscosity of the oil phase or its sulfur content due to the fact that centrifugation removed only a small portion of the nanoparticles.