Effect of Colloidal Stability and Miscibility of Polar/Aromatic Phases on Heavy Oil Demetallization

Chemical demetallization is a promising pretreatment method for processing heavy residues with ultrahigh metal content. However, hydrophilic demetallization reagents usually have poor miscibility with the lipophilic oil phase and tend to break the colloidal stability of heavy oils, limiting the demetallization effectiveness. It was first found that maltenes could promote the demetallization percentage of the asphaltenes fraction from 35.7% to 74.3%. Herein, the effect of colloidal stability and miscibility of the polar/aromatic phases on asphaltenes demetallization was investigated. Optical and UV-vis monitoring, as well as dynamic light scattering, revealed that maltenes could substantially hinder the formation of asphaltenes deposition after the addition of methanesulfonic acid. The interfacial tension between the polar/aromatic phases was significantly reduced by maltenes and had a strong linear correlation with asphaltenes demetallization efficiency. It was also observed that the byproducts after demetallization could be efficiently eluted in the presence of maltenes. The addition of surfactants or antisolvents also affected asphaltenes demetallization. The colloidal stability and the miscibility of reagents in oils may be essential considerations for the chemical demetallization method of residue oils.