Asphaltene dispersants weaken the synergistic modification effect of ethylene-vinyl acetate and asphaltene for model waxy oil. (1st June 2023)

• Record Type: Journal Article
• Authors: Xia, Xue; Li, Chuanxian; Qi, Yujia; Shi, Huimin; Sun, Guangyu; Yao, Bo; Yang, Fei; Zhao, Yansong
• Is Part Of: Fuel. Volume 341(2023)
• Publication Date: 2023-06-01
• Subjects: Asphaltene dispersant -- Model waxy oil -- Pour point depressant -- Rheology; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2023.127628
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: The first evidence of asphaltene dispersant and polymer PPD competing for adsorption on asphaltene surfaces. The adsorption between polymer PPD and asphaltene is the key factor affecting the modification effect of PPD on the rheologyof waxy oil. The addition of asphaltene dispersants can not affect the interference of EVA with the crystallization process of paraffin wax, but it can affect the formation process of EVA/asphaltene composite particles. The greater the ability of an asphaltene dispersant to improve asphaltene stability, the more significant the deterioration effect on the waxy oil's low-temperature rheology. The ability of EVA to compete with asphaltene dispersants depends on the strength of molecular electronegativity. Abstract: It has been proved that colloidal asphaltene and polymer pour point depressants (PPD) synergistically and dramatically modify the rheology of model waxy oil. In the crude oil recovery process, amphiphilic asphaltene dispersant (AD) is often added to inhibit asphaltene deposition, the added AD should affect the synergistic effect of asphaltene and PPD and need to be further investigated. In this work, several asphaltene dispersants were added to the model waxy oil and their influence law on the modification effect of ethylene–vinyl acetate (EVA) was systematically evaluated. The results indicated that AD does not affect the modification effect of EVA alone, but significantly deteriorates the synergistic modification function between EVA and asphaltene. Further, the electron cloud density of AD molecules was calculated using molecular dynamics, revealing the mechanism by which AD influences the modification effect of polymer PPD: the effect of EVA in improving the low-temperature rheology of model wax oil is primarily determined by the adsorption of EVA with asphaltene, while the existence of competitive adsorption between AD and EVA will inhibit the modification effect of EVA. The advantage of AD molecules in the competitive adsorption process increases with their electronegativity, making their dispersion effect on asphaltene and suppression of EVA modification ability more pronounced. The discovery of this phenomenon sheds light on the dispersion stability of asphaltene dramatically affects the performance of PPD, which helps develop new efficient crude oil modifiers.