THE EFFECTS OF SOLVENTS AND HETEROATOMS IN ASPHALTENE AGGREGATION PROCESS

• Main Author: Maulidhian Aribowo, Intan
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/88001
• Institution: Institut Teknologi Bandung

Asphaltenes are the heaviest fraction found in petroleum and coal. Based on its solubility, the asphaltene molecules are defined as a fraction that is soluble in aromatics but insoluble in n alkane compounds. The molecular structure of asphaltenes generally consists of polyaromatic hydrocarbons (PAHs), has side groups in the form of aliphatic chains, and has heteroatoms such as N, O, S. Asphaltene molecules from different sources have different structures. Solvents, heteroatoms, and temperature are factors that can affect the formation of aggregates in asphaltene molecules. Therefore, the purpose of this research is to study the effect of heteroatoms, solvents, and temperature on the aggregation process of asphaltene. In addition, the interactions that occur in the system are also analyzed. MD (Molecular Dynamics) simulations were performed on asphaltene molecules in various solvent systems including water, hexane, and toluene with temperature variations. The temperatures used for the simulation were 300 K, 330 K, and 360 K, with a pressure of 1 bar. The asphaltene molecules used in this study are a modified CA21 asphaltene model with the addition of alkyl chains and variations in the position and type of heteroatoms. All simulations were performed using GROMACS software version 2024.3. After MD simulation, trajectory analysis such as calculation of minimum distance between molecules and radial distribution function (RDF) were performed. Based on the trajectory analysis, asphaltene only aggregated in water solvent. In hexane solvent, asphaltene does not aggregate stably, while in toluene it does not aggregate. Different behavior is shown by the model O4 asphaltene system in hexane and toluene solvents. Asphaltene model O4 can form O---H hydrogen bonds at the end of the aliphatic chain between molecules. The increase in temperature can make asphaltene aggregate faster. Position 3 in the aliphatic group forms aggregation longer than other positions in the order of aggregation speed S>N>O. RDF results show the interaction distance between asphaltene molecules simulated in this study are <1 nm. This indicates that the ?-? interactions that occur are mostly parallel or parallel offset.