Structural Analysis of Asphaltene Aggregates in Bulk and Slit-Shaped Silica Mesopores Assessed by Coarse-Grained Simulations

Asphaltene aggregation can influence fluid behavior in bulk and confined conditions, such as those provided by porous materials. To improve our collective understanding of the mechanisms involved, the structural properties of asphaltene aggregates are quantified in slit-shaped silica pores of varying widths at a fixed asphaltene concentration of 5 wt %. Coarse-grained simulations reveal aggregates with fractal dimensions of around 2.0, consistent with experimental measurements. The simulations show a preferential adsorption of n-heptane compared to toluene on silica surfaces, yielding nonuniform solvent distributions across the pore width. For the systems considered, this phenomenon does not significantly affect aggregation. Good qualitative agreement with the experiments suggests that the model proposed in this work could lead to a deeper understanding of asphaltene behavior, which is relevant for a variety of energy applications.