Interaction mechanisms between liquid organic matter and solid bitumen

As a hydrocarbon-rich byproduct of petroleum systems, natural solid bitumen demonstrates dual dissolution and adsorption functionalities toward liquid hydrocarbons. Elucidating these adsorption mechanisms provides critical insights into hydrocarbon expulsion dynamics during bitumen secondary cracking and informs strategies for fluidity modulation. This molecular-scale investigation systematically examines interfacial binding mechanisms governing bitumen-hydrocarbon interactions. Building upon atomistically resolved models, semi-flexible docking simulations were conducted across hydrocarbon compound classes and thermal maturation stages. Quantitative analysis of binding Gibbs free energy differentials between saturated and aromatic hydrocarbons revealed distinct interaction modalities governing solid-liquid organic interfaces. These interfacial interactions exhibit four governing parameters: hydrocarbon type, molecular weight, methyl group density at organic interfaces, and condensation degree. High molecular weight polycyclic aromatic hydrocarbons with elevated condensation degrees and their derivatives display enhanced binding affinities, contrasting with the weak retention observed for light hydrocarbons, small cycloalkanes, and low-weight aromatic species.