Strategies for adding tetralin in thermal processing of heavy oil

The strategy of adding tetralin as a H-donor in the thermal processing of heavy oil was investigated by experimental characterization and theoretical calculations. According to the experiments, the timing of adding 1 wt% of tetralin has a great influence on the visbreaking performance of heavy oil. Calculations based on density functional theory showed that benzyl radicals released from the thermal cracking of tetralin accelerate the dealkylation that determines the heavy oil upgrading. Meanwhile, Hα provided by tetralin is able to selectively saturate aromatic C radicals which are essential for condensation. Compared with the conventional H-donor addition, i.e., pre-mixing of tetralin with heavy oil, a similar viscosity reduction rate of about 98% can be obtained during the visbreaking with delayed tetralin addition. Furthermore, the addition of tetralin before the significant occurrence of condensation further increases the conversion of vacuum residue fraction by 3.4% and reduces the asphaltene content of the product by 2.6 wt%.