An experimental study on the effect of alumina nanocomposites on asphaltene precipitation

This study investigates the inhibition of asphaltene precipitation using alumina-iron nanocomposite (NCP). Al:Fe NCP, successfully synthesized from pure aluminum and iron chloride, is crystalline mixture of hematite and alumina phases with a purity of 99%. Decreasing the content in hematite lowers the particle size from similar to 60 to 10 nm. To evaluate the inhibition potential of Al:Fe, a series of experiments consisting of the addition of Al:Fe NCP into a model crude oil followed by a precipitation using n-heptane were conducted. The model oil was a solution consisting of 3 mg of asphaltene extracted from a dead Middle Eastern heavy oil (29.2(o)API) dissolved into 10 g of toluene. 35 vol. % of heptane was required to precipitate asphaltene from the model crude oil. Hereinafter termed as asphaltene onset precipitation (AOP), adding 0.05 wt.% Al:Fe NCP to the model oil requires up to 30 mL of heptane to precipitate the same amount of asphaltenes. The increase in molar ratio in alumina decreases AOV up to 63.5%. The spectral studies revealed that the inhibition of asphaltene precipitation involves both the polar interactions of alumina phase with asphaltene and the decrease of the pi-pi stacking interaction upon addition of NCPs.