Theoretical Approach to the Stability of Visbroken Residues

Abstract

A theoretical method to calculate solubility parameter distributions was used to study the main factors that affect the stability of residues and products of their visbreaking with respect to asphaltene deposition. With this method it was possible to analyze the changes observed on the solubility parameter distributions of asphaltenes due to visbreaking. The results obtained showed a decrease in easily soluble asphaltenes, while there is an increase in difficult-to-dissolve asphaltenes during processing. To evaluate the instability, a compatibility index between asphaltenes and resins/or aromatics is proposed using the theoretical solubility profiles. By use of this index, it was possible to identify the factors involved in instability and to establish their relative importance for each sample. Among all the factors studied, the characteristics of the asphaltene fraction seem to be the main one. For the group of fractions examined, it was found that the average solubility parameter calculated was directly proportional to the H/C atomic ratio.

Preparative Subfractionation of Petroleum Resins and Asphaltenes. II. Characterization of Size Exclusion Chromatography Isolated Fractions

“…Average molecular parameters and average molecular weights were estimated by following a published methodology based on 1 H NMR determinations (Leo´n, 1987 There is ample evidence supporting the important effects derived from the H contents of petroleum fractions on their solubility and distillation properties (Boduszynski, 1987;Boduszynski et al, 1998;Rogel, 1997;Rogel, 1998;Wiehe and Liang, 1996), their crackeability and coking indexes (Wiehe, 1992;Wiehe, 1993;Wiehe, 1994) and their tendency to separate solid phases as well (Carbognani et al, 2000;Rogel et al, 2001). About 25 mg of sample was dissolved in 1 mL of a mixture CS 2 /CH 2 Cl 2 : 1/1: vol.…”

Colloidal stability and hot filtration test of residual fuel oils based on visbreaking and ebullated bed residue H-Oil hydrocracking

“…Unfortunately, the conversion level in most residue conversion processes is limited by the colloidal instability of the unconverted residual oil. The colloidal stability deterioration and increasing of the soft coke like sediment content in the unconverted residual oil during thermal conversion of residual oils has been documented in several studies (Bartholdy and Andersen, 2000;Deng et al, 2011;Gawel et al, 2005;Higuerey et al, 2001;Li et al, 1999;Matsushita et al, 2004;Marafi et al, 2005;Rahimi et al, 1997;Robert et al, 2003;Rogel, 1998;Tojima et al, 1998;Wang et al, 2009;Zerlia and Pinelli, 1993;Zhang et al, 2006). The increased sediment content in the unconverted residual oil has impact on the quality of the finished residual fuel oil product, that is produced from the residue conversion unit unconverted residual oil and the added to it cutter stocks.…”

Storage Stability of Products from Visbreaking of Oilsands Bitumen

“…7 (c) It was shown that the increase in phase instability could be related to a change in the solubility parameter (δ) distribution of the visbroken product. 11 As visbreaking severity increased, there was a decrease in the lower solubility parameter material. A correlation was found between the hydrogen-to-carbon ratio of the visbroken material and the solubility parameter.…”