What is it about?
Pyrene is a large molecule that is found in crude oil. It is representative of a family of compounds called asphaltenes that can form large deposits in oil pipes. Here we compare two different computer methods to calculate the solubility of pyrene in organic solvents. The first method is a direct simulation of solid pyrene and the solvent. The second method involves growing a cavity in the solvent before inserting pyrene and finally shrinking the cavity and calculating the energy of solvation. We found that at room temperature and pressure both methods give very similar results, however at high temperature and pressure, such as those relevant to the oil industry, the cavity-based method performed significantly better.
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Why is it important?
Asphaltene deposits cost the oil and gas industry millions of dollars to remove each year, however the cause of the deposits forming is not clear. By understanding the solubility of an example compound it is hoped that we might provide insight into why this occurs. We have shown that the cavity-based method we developed works at high pressure and temperature where other methods, such as the direct coexistence method and even experiments fail.
Perspectives
I think the comparison of the two methods is a nice example of how computer simulations can be used for real-world applications. Measuring the solubility is not easy at the best of times, let alone at high temperature and pressure that are required in the oil and gas industry.
Dr Charlie Wand
University of Exeter
Read the Original
This page is a summary of: Solubilities of pyrene in organic solvents: Comparison between chemical potential calculations using a cavity-based method and direct coexistence simulations, The Journal of Chemical Thermodynamics, April 2019, Elsevier,
DOI: 10.1016/j.jct.2018.11.029.
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