Molecular Recognition of Wax Inhibitor Through Pour Point Depressant Type Inhibitor

Abstract

The deposition or crystallization of wax paraffin from crude oils is one of the crucial issues faced in the petroleum industry particularly when the temperature of the crude oil is below the wax appearance temperature (WAT). Pour Point Depressants (PPDs) chemical is proven to be an efficient way to solve this problem. This study investigated poly(ethylene-co-vinyl acetate(EVA)) and Poly(maleic anhydride-alt-1-octadecene)(MA) polymer inhibitors on the van der Waals intermolecular interaction between the major wax component molecule n-octacosane C 28 H 58 , via molecular dynamics simulation (MD) technique on Material Studio 5.5 software Package. COMPASS force field was applied to analyse the desired structural property, Radial Distribution Function (RDF). The results showed that the radial distribution function and g (r) value is able to give the insight on which particular type of fuctional atoms were benefit to inhibit the self-agglomerate of the wax crystal formation. The presence of carbonyl oxygen in EVA plays a significant role to inhibit the wax formation through the van der Waals interaction between active hydrogen atoms in n-octacosane molecule. Therefore the chances of wax inhibition in octacosane is higher by introduced EVA as inhibitor compared to MA.

Inhibiting wax deposition using palm oil additives

“…From the chemical structure shown in Fig. 1a, the hydrogen atoms in the eicosane, especially H59 and H60 (hydrogen atoms at terminal end), form long as well as heavy hydrocarbon chains through van der Waals intermolecular interactions (Chua and Kelland 2012;Jang et al 2007;Ridzuan et al 2016;Zhang et al 2008). Supersaturation point is then reached when the wax crystal nucleates as the hydrocarbon chain concentrates.…”

“…In addition, in the presence of EVA which comprises of ethylene and vinyl acetate (VA), the polar compound consisting of methyl and methylene group (found in VA) has two active oxygen atoms also functions similarly to the active oxygen atoms found in oleic acid when it comes to inhibiting wax crystallization. Moreover, the side chains in both the carboxy group from the oleic acid and the VA from EVA may hinder the agglomeration process and reduce the WAT as well as the pour point of the crude oil (Patel et al, 2017;Ridzuan et al, 2016;Soni et al, 2010).…”

“…Also, the side chains of the vinyl acetate group may also contribute to the inhibition of wax crystallization and decreases the WAT as well as pour point. The two active oxygen atoms in the vinyl acetate perform a significant part to decrease the formation of wax crystals in the crystallization process which has been thoroughly discussed under the simulation results section (Kelland 2009;Ridzuan et al 2016).…”

“…This confirms that the increase in wax deposits is influenced by the concentration of wax inhibitor utilized and as the concentration reaches the optimum value, it alters the wax crystallization behaviour by implementing more structures to disturb and reconcile with edge of the developing wax crystals (Machado et al 2001a, b;Yang et al 2017). On top of that, the van der Waals interaction between the crude oil and wax crystals may be altered by the presence of various concentrations of wax inhibitor used which largely influences the wax solubility in the crude oil (Machado and Lucas 1999;Ridzuan et al 2016;Zhang et al 2008).…”

“…The deposition of paraffin waxes on to the wall of the pipeline usually occurs during the transportation of crude oil particularly when the temperature of the crude oil is below the wax appearance temperature (WAT) (dos Santos et al 2004;Hosseinipour et al 2016;Jang et al 2007;Ridzuan, Adam, and Yaacob 2016;Wei, Acosta, Gawas and Krishnamurthy 2015;Zheng et al 2016). WAT is defined as the maximum temperature where the first wax crystals start to form when waxy crude oil is cooled (Aiyejina et al 2011).…”