Poly(aminopropyl/methyl)silsesquioxane microspheres improve the flowability of model waxy oils associated with asphaltenes

Abstract In this article, poly(aminopropyl/methyl)silsesquioxane (PAMSQ) microspheres with different polarities were first synthesized and characterized. The polarity of the PAMSQ microspheres is progressively enhanced by increasing the aminopropyl molar ratios (1–25 mol%). Then, the effect of PAMSQ microspheres with different polarities on the flowability of the model waxy oils with/without asphaltenes was studied through rheological tests, DSC analyses, microstructure observation and asphaltenes precipitating measurement. The results indicated the PAMSQ microspheres alone could spacially hinder the interactions among the precipitated paraffin crystals, thus slightly improving the flowability of the model waxy oil without asphaltenes (MO-1). The improving ability of PAMSQ microspheres deteriorates with the polarity increasing, and the MO-1 shows the best flowability after adding 200 ppm PAMSQ-1 microsphere (with the aminopropyl molar ratio at 1 mol%). To our surprise, adding PAMSQ microspheres can significantly improve the flow behavior of the model waxy oil with 0.75 wt% asphaltenes (MO-2). Based on the asphaltenes precipitation data, the PAMSQ microspheres could adsorb asphaltenes to form the PAMSQ/asphaltene composite particles in MO-2. The composite particles can play a role of the heterogeneous nucleation templates for paraffin molecules and facilitate the formation of larger and more compact wax floccules, thus enhancing the flowability of MO-2 at low temperatures. The flow improving ability of the PAMSQ microspheres for MO-2 increases with increasing the polarity of the microspheres due to the increased interactions between the microspheres and asphaltenes. The MO-2 exhibits the best flowability after adding 200 ppm PAMSQ-3 microsphere (with aminopropyl molar ratio at 15 mol%). When the polarity of the microspheres is too strong (PMASQ-4 microsphere), however, the microspheres cannot dispersed in waxy oil stably, thus inhibiting the interactions between the microspheres and asphaltenes and deteriorating the flow improving ability of the microspheres for MO-2.