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Colloidal behavior of confined model asphaltenes using molecular dynamics
The colloidal behavior of asphaltenes explains the high viscosity of heavy oils and the occurrence of solid deposits in reservoir rocks, production wells or transport lines.
Asphaltenes make refining more difficult because they cause coke deposits and tend to lower the yield in high quality fuels or chemicals. Due to their significant content of sulfur and metals (Ni, V) and high aromaticity, energy-intensive conversion and hydrotreatment processes are required.
The colloidal nature of asphaltenes is known experimentally. It is generally explained by Yen’s model, in which 4-5 molecules form stacks of polyaromatic sheets. However, the behavior of such colloids is still a subject of intensive research, mainly because of the difficulty to consistently determine the behavior of heavy oils under high-temperature conditions, as they are present in steam injection processes and under refining conditions.
We compare the colloidal behavior of two asphaltene models of similar molecular weight in two liquid solvents (toluene and n-heptane), using MedeA-LAMMPS to simulate these systems with the All-Atom PCFF+ forcefield.