Molecular Recognition and Molecular Mechanics of Micelles of Some Model Asphaltenes and Resins

Abstract

Molecular mechanical calculations of resins and a highly aromatic model asphaltene extracted from the spectroscopic data of a 510 °C residue of a Venezuelan crude showed that the driving interaction in the micelle formation is the attraction between their aromatic planes. The molecular recognition process is completed by the interactions produced by the alkyl and cycloalkyl groups present in these molecules. The complex three-dimensional shape of the alkyl parts of this model asphaltene limits the growth of its micelles through steric interference. The shape of these asphaltene molecules allows the aggregation of only those resins that fit its aromatic regions and show the lowest steric interference with its alkyl groups. This type of molecular recognition may explain why only some resins are able to solubilize specific types of asphaltenes through the formation of stable aggregates. It was found also that the steric interference of the alkyl groups may limit the number of available sites for H bonding and other directional interactions in this type of model asphaltenes.