Issue 21, 2017

Effects of the asphaltene structure and the tetralin/heptane solvent ratio on the size and shape of asphaltene aggregates

Abstract

Asphaltene molecules, which consist of differently hydrogenated polyaromatic cores grafted with side alkyl chains of different sizes and grafting densities, were simulated with a solvent mixture of heptane and tetralin using coarse-grained force fields. Starting with the initial configuration of randomly distributed asphaltene molecules and solvents, the asphaltene molecules aggregate because of the attractive force between their polyaromatic cores, but their sizes and shapes differ. The average aggregate size decreases with an increase in the hydrogenated polycyclic core, side-chain length, and tetralin concentration, which agree with experimental observations in the hydrocracking process. The number of side chains also influences the aggregate size but only in the presence of tetralin. In particular, the effect of tetralin addition occurs more significantly for asphaltene molecules with more side chains because side chains sterically block the intermolecular interactions between polyaromatic cores, which makes it easier for the aromatic ring of tetralin to bind to the polyaromatic core of asphaltene. These steric effects of side chains yield different shapes of aggregates, showing parallel stacking (face-to-face) for aromatic cores with many side chains, and T-shape (edge-to-face) or offset-parallel stacking for those with fewer side chains. These findings agree with the experimental observation regarding the effect of tetralin on the solubility of asphaltene, and indicate that the extent of the tetralin effect depends on the number of side alkyl chains, implying that tetralin solvents need to be added with consideration for the structural change of asphaltene under hydrogenation or dealkylation conditions.

Graphical abstract: Effects of the asphaltene structure and the tetralin/heptane solvent ratio on the size and shape of asphaltene aggregates

Article information

Article type
Paper
Submitted
12 Mar 2017
Accepted
27 Apr 2017
First published
02 May 2017

Phys. Chem. Chem. Phys., 2017,19, 13931-13940

Effects of the asphaltene structure and the tetralin/heptane solvent ratio on the size and shape of asphaltene aggregates

H. Lee and Y. Lee, Phys. Chem. Chem. Phys., 2017, 19, 13931 DOI: 10.1039/C7CP01579H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements