Development and Exploitation of Asphaltenic Structures and Properties using Crystallographic Structural Informatics and Molecular-Scale Modelling

Basic hydrocarbon compounds including linear, branched and cyclic saturated and unsaturated aliphatic compounds, as well as polyaromatic compounds, are encountered in a range of industries, with their structural properties underpin the formulation and manufacture of a range of materials spanning e.g. pharmaceutical-, personal-, domestic- and energy-related products. Despite their obvious societal relevance, there is a surprising paucity of direct crystallographic information of these compounds. This, in turn, limits innovation opportunities for either the rational design of new compounds and formulations or, in cases when the formation of such compounds is undesired, of being able to mitigate and control the effects associated with their formation.

Part of the reason for this lack of crystallographic data lies in challenges associated with preparing good quality single crystals for structure solution. A further reason reflects upon the huge number of potential hydrocarbons that exist, e.g. polyaromatic asphaltene compounds found in petroleum deposits have been shown to exhibit over 20,000 distinct structures. Despite the above narrative, the CCDC’s Cambridge Structural Database (CSD) is rich in structural data, containing many of the structures of direct interest to the hydrocarbon sector. This suggests the value of curating the asphaltenic structures in the CSD into a structural subset analogous to that recently developed for the pharmaceutical sector.

Creation of the asphaltenic subset would build on existing experimental work to identify the key molecular features relevant to these compounds, allowing different classes of asphaltenic structures to be easily categorised. Having established the asphaltenic subset, analysis of different classes of structures would enable an understanding of the key intramolecular geometries and intermolecular interactions that underpin aggregation of these molecules.

This informatics-based approach will then be complemented by modelling intermolecular (synthonic) interactions to provide both a statistical and energetic analysis of the interplay between structure, crystallisability, and properties. Building on this energetic approach will also enable the prediction of particle surface properties (aggomeratability, hydophobisity, hydrophilistitry, surface energy etc.) related to the formation of asphaltenic solids. Taking a holistic structural approach to the analysis of this class of molecules will provide a thorough understanding of the fundamental science that drives unwanted formation and aggregation of asphaltenic solids, thus potentially enabling the rational design of novel additive molecules which might have the ability to disrupt these processes.