A green solution: Molecular dynamic simulation study of wax inhibition through pour point depressant type inhibitor

Abstract

Paraffin wax deposition from crude oils at low temperature is one of the critical and long standing problems in petroleum industry. An addition of pour point depressants (PPDs) has been proved to be an efficient way to inhibit the wax deposition. The chosen group of PPDs in this study are poly(ethylene-co-vinyl acetate(EVA)) and (Meth)acrylate Ester (MAE) polymers. The molecule geometry structures were labelled as illustrated in Figure 1. This research focuses on the investigation of van der Waals intermolecular interaction between the major wax component molecule C28H58, with the inhibitor molecules via molecular dynamics simulation (MD) technique in Material Studio 5.5 software Package. The simulation system has been equilibrated under NVE essemble at 200ps followed by NVT assemble. COMPASS force field is applied to analyse the desired structural property Radial Distribution Function (RDF). The results show that the functional groups introduced by EVA were benefit to inhibit the self-agglomerate of the wax crystal compared to MAE as reported in a published literature. Simulation output also provides a better understanding on the interaction between wax crystal and inhibitors. The oxygen atoms in EVA play a significant role to inhibit the wax formation through the van der Waals interaction between hydrogen atoms in n-Octacosane molecule. As a conclusion, MD is a promising tool method to recognise the wax-inhibitor intermolecular interaction which is much fast, environmental friendly and economic for further inhibitor screening work. Keywords: poly(ethylene-co-vinyl acetate(EVA)),(Meth)acrylate Ester (MAE) Polymers, COMPASS, van der Waals