Investigating the effect of magnetic nanoparticles in partial upgrading of bitumen by ultrasonic irradiation

In this study, the performance of magnetic and recyclable NiFe₂O₄ nanoparticles for partial bitumen upgrading under ultrasonic irradiation was investigated the synthesis and stability of the catalyst were confirmed through characterization of both freshly synthesized and recycled nanoparticles from experiments conducted using an open low-power probe (ULP) and a closed high-power probe (UHP). Characterization techniques including SEM, IR, EDX, XRD, and VSM confirmed the stability of the nanoparticles after recycling. These nanoparticles facilitated the upgrading process by amplifying the effects of the intense localized energy from ultrasonic cavitation. Ultrasonic “hot spots” provide sufficient energy to initiate the cleavage of strong chemical bonds within bitumen components. In this context, the NiFe₂O₄ catalyst plays a synergistic role by reducing the activation energy required for bond breaking, disrupting interactions between asphaltene molecules, and interacting with heteroatom-containing components in bitumen through its acidic sites. To further enhance radical stabilization and upgrading efficiency, tetralin was used in a minimum amount of 2% (wt.). Tetralin, by donating hydrogen atoms and forming benzyl radicals, prevents radical recombination, promotes the formation of stable lighter hydrocarbons, facilitates the dealkylation process, and contributes to the long-term viscosity stability (up to one month) of the upgraded bitumen. In summary, the UHP system, with its higher power density, reduced the viscosity of a bitumen from 225,000 to ~159,300 mPa·s (29 %). Also, there was 46% and 35% reduction in asphaltene, and sulfur content of bitumen respectively compared to the untreated sample. These results confirm the synergistic effectiveness of NiFe₂O₄ nanoparticles and a hydrogen donor such as tetralin in ultrasonic-assisted upgrading. Conducted under mild reaction conditions, no external heating, moderate temperatures, short reaction times, and atmospheric pressure, the process proved to be both energy-efficient and practical. These findings highlight the potential of this approach as a scalable, and sustainable strategy for heavy oil upgrading through the integration of ultrasonic and catalytic technologies.