Fe3O4 @SiO2 -hexamethyldisilazane amphiphilic magnetic emulsifier for viscosity-reduction of heavy oils via aquathermolysis reaction

Heavy oil accounts for a large share of global proven oil reserves and is thus a key energy resource. Yet its high viscosity and freezing point require complex, specialized processing. While chemical, microbial, and thermal recovery methods exist, a simple, controllable, and highly effective viscosity reduction method is still needed. Here, novel Fe₃O₄@SiO₂ nanoparticles capped with hexamethyldisilazane (HMDS) were synthesized as magnetic emulsifiers to reduce the viscosity of heavy oil. The as-synthesized Fe₃O₄@SiO₂-HMDS nanoparticles exhibit an average size of approximately 100 nm, along with good dispersion in oil and magnetic responsiveness. As emulsifiers, these nanoparticles promote the aquathermolysis reaction of extra-heavy crude oil at relatively low temperatures. Specifically, in our experiments, the amphiphilic emulsifier ME-8, with an SiO₂/HMDS molar ratio of 8:1, effectively reduced the apparent viscosity of three heavy oil samples (with initial viscosities of 27,500 cP, 58,000 cP, and 85,400 cP) by 67.27%, 68.96%, and 56.67%, respectively. These results were achieved under optimal conditions: an emulsifier mass fraction of 0.5%, a reaction temperature of 150°C, and a reaction time of 24 hours. This emulsifier-based method demonstrates promising potential for the exploitation of heavy crude oil.