Continuous Visbreaking of Heavy Oil in the Presence of Hot Compressed Water

: The dealkylation-based visbreaking of heavy oil in a hot compressed water (HCW) environment was investigated in a tubular reactor at 400 degrees C and 18 MPa. Under the applied HCW environment, the heavy oil/water mixture is in a liquid-vapor two-phase structure and the calculated content of solubilized water in heavy oil reaches 3.5 wt %. The viscosity of the oil phase is reduced by the solubilization of water, which decreases the diffusion limitation on the reaction kinetics of dealkylation. Meanwhile, reactive olefin groups formed in dealkylation are partly consumed through the hydration with solubilized water, by which condensation is suppressed and the reaction time window for dealkylation is extended. Only after 3.2 min of visbreaking in the HCW environment, an optimal product with a viscosity reduction rate of 76% and an increased yield of light components could be obtained. In addition, the asphaltene content of the optimal product is lower than the initial value.

Automated summary

In this study, the dealkylation-based visbreaking of heavy oil in a hot compressed water environment was investigated. It was found that the solubilization of water reduces the viscosity of heavy oil, leading to an increase in the reaction rate of dealkylation. The hydration reaction with solubilized water suppresses condensation and extends the reaction time window for dealkylation, resulting in higher yields and lower viscosity of the products.