Influences of Molecular Structure of Poly(styrene-co-octadecyl maleimide) on Stabilizing Asphaltenes in Crude Oil

Abstract

A series of poly­(styrene-co-octadecyl maleimide) (SNODMI) with various molecular structures were prepared through RAFT polymerization and subsequent modification with amine. The obtained SNODMIs were applied in the model crude oil with a high content of asphaltenes (3 wt %) to stabilize the asphaltenes particles, which were precipitated by adding n-heptane. The results indicate that SNODMI is a highly effective asphaltene stabilizer and its molecular structures play a pivotal role in determining its performance. With increasing the octadecyl branch content of the SNODMIs, the stabilizing performance is improved. The alternative structure with the highest branch content achieves the best performance. The appropriate molecular weight of the copolymer (Mn = 3500 Da) is required to optimally stabilize asphaltenes. The optimal imidization degree of SNODMI varies with the branch content. For SNODMI with a lower branch content (10.37 mol %), the stabilizing performance increases with the decrease in the imidization degree and samples without any imidization shows the best performance. For SNODMI with a higher branch content (20.92 or 45.26 mol %), an appropriate imidization degree (64.31 or 66.10%) shows the highest stabilizing efficacy for asphaltenes.

Effects of Styrene Ionomers on the Dispersion of Asphaltenes in Crude Heavy Oil

“…If we want to use polymers as effective asphaltene dispersants, the MW of the polymers should be neither too low nor too high. At this time, it should be mentioned that the polymer showed best efficiency when the MW of the polymer was slightly higher than that of asphaltenes, according to the study by Zhu et al of the effect of MW of polymers on asphaltene dispersion . However, it is not yet a generalized result applicable to all polymeric dispersants.…”

“…At this time, it should be mentioned that the polymer showed best efficiency when the MW of the polymer was slightly higher than that of asphaltenes, according to the study by Zhu et al of the effect of MW of polymers on asphaltene dispersion. 120 However, it is not yet a generalized result applicable to all polymeric dispersants. Thus, in the near future, a more systematic study is needed to find out how the MW of the polymers affects the dispersion of asphaltenes and what the optimal MW range is.…”

Effect of Aromatic Pendants in a Maleic Anhydride-co-Octadecene Polymer on the Precipitation of Asphaltenes Extracted from Heavy Crude Oil

“…The polymer-based dispersants have the advantages of small dosage, high efficiency, easy modification, and controllable molecular weight. The influence of molecular weight of polymers on dispersed asphaltenes has been confirmed . The favorable effect can be achieved when the polymer molecular weight is slightly larger than that of asphaltenes, which cannot be achieved by other types of inhibitors.…”

“…The influence of molecular weight of polymers on dispersed asphaltenes has been confirmed. 14 The favorable effect can be achieved when the polymer molecular weight is slightly larger than that of asphaltenes, which cannot be achieved by other types of inhibitors. In addition, different types of functional groups can be attached to the polymer to form a multi-action point situation.…”

Asphaltene Inhibition and Flow Improvement of Crude Oil with a High Content of Asphaltene and Wax by Polymers Bearing Ultra-Long Side Chain

“…However, most small-molecule asphaltene dispersants have problems such as a high cost of preparation and poor compatibility with different crude oils. The polymeric asphaltene dispersants can provide more sites of adsorption and better interaction with asphaltene molecules [10,11]. At the same time, the non-polar alkyls of the polymeric asphaltene dispersants can provide steric hindrance, further reducing the size of asphaltene aggregates.…”