Thermogravimetric investigation of the influence of colloidal phase on the processing properties of crude oil residues

Abstract

An atmospheric residue, a vacuum residue, a visbreaking residue, the maltene fractions of the residues, mixtures of the atmospheric residue with the vacuum residue and the residue from the supercritical extraction of the vacuum residue as well as residues mixed with dispersing agents were investigated by thermogravimetry at three different heating rates. From that, the activation energies of the weight loss were estimated. At temperatures up to about 400 °C the activation energy corresponds to the evaporation enthalpy, above 400 °C to the cracking energy. Comparing the results the strength of the interactions between colloid disperse phase and the components of dispersion medium was evaluated. It was found that besides the content of colloid disperse phase its stability has a significant influence on the properties of the residues, especially on the evaporation enthalpy. The stability of residues was investigated by the flocculation point determination. The obtained dependencies of evaporation enthalpies are also reflected in the yields of distillates and in the thermogravimetric residues at 500 °C. Thermogravimetry proves to be an effective method for the determination of important parameters of processing of crude oil residues considering the influence of the colloidal character of these complex mixtures.