Aggregation of asphaltene model compounds using a porphyrin tethered to a carboxylic acid

Abstract

A Ni(II) porphyrin functionalized with an alkyl carboxylic acid (3) has been synthesized to model the chemical behavior of the heaviest portion of petroleum, the asphaltenes. Specifically, porphyrin 3 is used in spectroscopic studies to probe aggregation with a second asphaltene model compound containing basic nitrogen (4), designed to mimic asphaltene behavior. NMR spectroscopy documents self-association of the porphyrin and aggregation with the second model compound in solution, and a Job's plot suggests a 1 : 2 stoichiometry for compounds 3 and 4.

Asphaltene aggregation studied by molecular dynamics simulations: role of the molecular architecture and solvents on the supramolecular or colloidal behavior

“…These findings indicate that aggregation among individual asphaltene molecules is primarily driven by π − π interactions, in a hierarchical way. Oppositely, experimental (Varadaraj and Brons 2012;Schulze et al 2015;Subramanian et al 2017) as well as simulation-based evidence (Headen et al 2009(Headen et al , 2017 exist corroborating the supramolecular, Gray's model. These works showed that asphaltene self-interaction depends also on acid-base and polar interactions.…”

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

“…This indicates that most polar fractions, insoluble in organic solvents such as heptane, are formed by nanoaggregates of molecules held in place by strong intermolecular forces [86]. (ii) Model compound route [198]: Asphaltene model compounds with known physicochemical properties are used to mirror asphaltene architecture. In order to study the association behavior due to the polyfunctional nature of asphaltenes, a series of pyrene derivative compounds, including hydroxyl groups, ketone alkyl side chains, and alkyl bridges, were synthesized and characterized, using methods such as vapor-pressure osmometry and neutron scattering [199].…”

Model Molecules for Evaluating Asphaltene Precipitation Onset of Crude Oils

“…40 Among these are model molecules based on octaethylporphyrin, N,N'-ditridecyl-3,4,9,10-perylenetetracarboximide, aromatic and aliphatic blocks with molar mass of 750 g mol -1 and quinoline-65. 32,[41][42][43][44][45] For the purpose of assessing the properties of the asphaltenes and the underlying mechanisms involved in these properties, various researchers have studied different model molecules, such as those based on pyrene, coronene, pyridine, and quinoline, always containing an aromatic core and hydrophobic alkyl chains. 34,[36][37][38][46][47][48][49][50] Molecular simulation has also been employed to improve the relation between the physico-mechanical properties of model molecules and those of real asphaltenes, 34,37,[50][51][52] as well as to shed light on the aggregation and separation of asphaltenes in binary solvent systems.…”