Microscopic mechanism of single-walled carbon nanotubes (SWCNTS) as a dispersant for alleviating asphaltene aggregation

Abstract

The flow properties of crude oil have been seriously affected by the aggregation behavior of asphaltenes. The single-walled carbon nanotubes (SWCNTs) can exhibit positive alleviation effect as a dispersant for asphaltene aggregation, but the influence mechanism at the molecular level is still controversial. With the action of SWCNTs, the rate of asphaltene self-aggregation decreased, and the time to form asphaltene clusters came later. At the same time, the structure of asphaltene clusters became looser. Interestingly, when a small number of asphaltene molecules start to accumulate, the density of asphaltene molecules in the accumulation body is relatively low. In addition, the peak value of RDF between the SWCNTs and asphaltene is much higher than that between asphaltene molecules, which indicates that the interaction between SWCNTs and asphaltene molecules is stronger than that between asphaltene molecules, thus affecting the self-aggregation of asphaltene molecules. In addition to that, it is worth mentioning that in the vmd snapshot, we also observed that the aggregation mode of asphaltene would change to SWCNTs as the core. This work explains the decrease of asphaltene self-aggregation degree and speed with the addition of SWCNTs from the microscopic point of view, which is due to the strong interaction between SWCNTs and asphaltene molecules weakens the interaction between asphaltene molecules.