Advances in Asphaltene Petroleomics. Part 1: Asphaltenes Are Composed of Abundant Island and Archipelago Structural Motifs

Abstract

For decades, discussion of asphaltene structure focused primarily on molecular weight. Now that it is widely accepted that asphaltene monomers are between ∼250 and 1200 g/mol, disagreement has turned to asphaltene architecture. The classic island model depicts asphaltenes as single core aromatic molecules with peripheral alkyl side chains, whereas the less widely accepted archipelago model, includes multiple aromatic cores that are alkyl-bridged with multiple polar functionalities. Here, we analyze asphaltene samples by positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry and perform infrared multiphoton dissociation to identify their aromatic core structures to shed light on the abundance of island and archipelago structural motifs. Our results indicate that island and archipelago motifs coexist in petroleum asphaltenes, and unlike readily accessible island motifs, asphaltene purification is required to detect and characterize archipelago species by mass spectrometry. Moreover, we demonstrate that mass spectrometry analysis of asphaltenic samples is biased toward the preferential ionization/detection of island structural motifs and that this bias explains the overwhelming mass spectral support of the island model. We demonstrate that the asphaltene structure is a continuum of island and archipelago motifs and hypothesize that the dominant structure (island or archipelago) depends upon the asphaltene sample.

Catalogue of Plausible Molecular Models for the Molecular Dynamics of Asphaltenes and Resins Obtained from Quantitative Molecular Representation

“…13 The most recent comprehensive characterizations performed using extrographic fractionation and ultrahigh-resolution mass spectrometry seem to indicate that, as one would expect, asphaltenes comprise a structural continuum of both continental (island) and archipelago motifs. 14,15,16 In this scenario, not surprisingly, the theoretical descriptions lag behind. Any equation-of-state modelling of asphaltene phase behavior and/or deposition process will invariably suffer from the lack of an appropriate description of what, in essence, is a continuous molecular distribution, and as such, current models struggle to provide quantitative predictions.…”

Further evaluation of the Re-Os systematics of crude oil: Implications for Re-Os geochronology of petroleum systems

“…The typical models of the molecular structure of asphaltene consist of a single polycyclic aromatic hydrocarbon core known as the island or continental type (Mullins, 2010), or multiple alkyl-bridged aromatic cores known as the archipelago type (Strausz et al, 1992;Murgich et al, 1999;Chacón-Patiño et al, 2017) with pendant alkyl chains and functional groups. The asphaltene molecules tend to aggregate even at low concentrations (50-100 mg/l) in solvents like toluene (Durand et al, 2010;Mullins et al, 2012;Yarranton et al, 2013), forming structures which could occlude and adsorb surrounding molecules.…”

Suggested plausible structures for Titan's haze analogs using tandem mass spectrometry

“…Tandem mass spectrometry experiments are carried out using collision-induced dissociation (CID) in order to produce fragments (Chacon-Patino et al, 2017, 2018aRüger et al, 2017). This technique is based on the acceleration of mass selected ions species into a collision cell filled with a neutral gas such as argon or nitrogen, generating laboratory collisional energies.…”