Molecular Distillation of Petroleum Residues and Physical-Chemical Characterization of Distillate Cuts Obtained in the Process

Abstract

Molecular distillation is presented as an alternative technique for the separation of petroleum residues. The technique was used to obtain 13 heavy petroleum cuts from three atmospheric residues (ARs) at 673.15 K and above. The cuts present initial and final boiling points between (673.15 and 951.15) K. To evaluate the efficiency of the technique, chemical characterization of residues and distillate cuts, which included SARA fractionation, 13 C NMR, elemental composition, and density and viscosity analysis, was performed. In addition, extended true boiling point curves of crude oils by simulated distillation and by molecular distillation were compared. An increase in the viscosity and in the density was observed in all cuts with an increased molecular distillation temperature. Such behavior demonstrates that highly polar components that have a high structural complexity, such as resins and asphaltenes, are concentrated at the higher temperatures of the process. A sensitivity analysis of these two properties, together with the temperature, showed that viscosity and density decreased with increased temperature. On the other hand, the thermal expansion coefficient values obtained were equivalent to those reported in literature for petroleum products. Furthermore, a complete characterization of crude oils was made using the molecular distillation process to extend the true boiling point (TBP) curves.

Fractionation and Characterization of a Petroleum Residue by Molecular Distillation Process

“…In the molecular distillation process, the FBP MD is expected to be equivalent to the FBP HTSD of the generated cut. 12 As observed, this expectation is confirmed and the small differences between the FBP of the HTDS method and the FBP defined for each cut generated by Framol correlation indicate that the TBP curve determinate by MD is representative of crude oils.…”

“…11 Since the molecular distillation process is capable of obtaining distillate cuts without the heavy compounds of the sample, they can be analyzed by SimDis. Linañ et al 12 presented the TBP curve extend by the molecular distillation process and the SimDis curve for the crude oils AL and JES, indicating that the TBP curve defined by HTDS was representative of the crude oils.…”

“…19 This method has been widely used for determining the kinematic viscosity of crude oil and its fractions. 12,20 The standard method consists of introducing the sample into the measuring cells, which are at a closely controlled and known temperature. The measuring cells consist of a pair of rotating concentric cylinders and an oscillating U-tube.…”

Advances in Asphaltene Petroleomics. Part 4. Compositional Trends of Solubility Subfractions Reveal that Polyfunctional Oxygen-Containing Compounds Drive Asphaltene Chemistry

“…Moreover, Boduszynski hypothesized that all nonaggregated petroleum compounds are n -heptane soluble, and only aggregated species exhibit insolubility. Therefore, if the Boduszynski continuum is correct, the solubility/aggregation behavior of petroleum asphaltenes must be the result of the synergy between several intermolecular forces, including π-stacking, hydrogen bonding, acid/base interactions between carboxylic acids and nitrogen bases, and London forces between aliphatic moieties, as pointed out by Yarranton, Gray, Silva, Acevedo, and Murgich et al ,− Eventually, comprehensive and selective fractionation of distillation residues and asphaltenes should yield fractions enriched in species with a distillable nature and higher solubility in n -heptane. ,, Simply, if the increased boiling point of asphaltenes is due, in part, to intermolecular interactions, removal of these interactions (albeit difficult) should yield species of a lower apparent boiling point.…”

Fuzzy cognitive approach of a molecular distillation process

“…The technique is based upon short path distillation in high vacuum conditions (0.1 Pa), which represents a smaller operational temperature and a smaller exposure time of the distilled liquid on the heated surface. In addition, research carried out and in progress at LDPS/LOPCA/UNICAMP-Petrobras Sbaite et al, 2006;Zuñiga Liñan et al, 2010) has demonstrated the TBP curves can be extended above 838.15 K, which represents a gain of over 70-80% in mass of the petroleum residue yield, compared with the 30-60% in mass obtained by conventional methods. The molecular distillation of petroleum residues is a complex process characterized by nonlinear dynamic and space-varying behavior.…”