Influence of the Architecture of Additives on the Stabilization of Asphaltene and Water-in-Oil Emulsion Separation

Abstract

Amphiphilic chemical additives are widely used to prevent the formation of asphaltene deposits and to promote demulsification of crude oil. Although it is known that the efficiency of these additives is mainly related to their structure and molar mass, this correlation is still not well established, because it is also related to the type of petroleum to be treated. In this work, C10I asphaltenes extracted from two different types of asphaltic residues were used to prepare model systems containing 1 wt % asphaltenes in toluene. Amphiphilic macromolecules, obtained from polymerization of cardanol by polyaddition and polycondensation, were characterized by Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR), and size-exclusion chromatography (SEC) and evaluated regarding their influence on the variation of asphaltene precipitation onset of model systems and the variation of volume and separation kinetics of water in model water-in-oil emulsions. The results show that the structure of polycardanol obtained by polyaddition favors its action as a dispersant of asphaltenes, which can be related to the fact that its phenol groups are relatively free to interact with the sites of the asphaltene molecules, as opposed to polymers obtained by polycondensation, in which the polymerization reaction occurs in the aromatic ring. Besides this, the demulsification results indicate a close relation of the dispersant action of this type of additive with its performance in water–toluene separation, so that the separation kinetics is mainly related to the molar mass of the additive in determining the final performance. The results highlight potential asphaltene dispersants derived from renewable sources.

Polycardanol and Poly(cardanol‐co‐styrene): Synthesis, Characterization, and Performance as Asphaltene Flocculant

“…Different kinds of polymers have been studied regarding asphaltene deposition in crude oil production . Previous studies have evaluated the behavior of asphaltenes in the presence of polycardanol (PCN) and sulfonated polystyrene, with different degrees of sulfonation.…”

“…These polymers have an amphiphilic structure, with a polar group, able to interact with asphaltene molecules. The efficiency of these polymers as asphaltene dispersants or flocculants depends on their concentration in solution and can be determined through the onset of precipitation of asphaltenes of a given crude oil …”

Model Molecules for Evaluating Asphaltene Precipitation Onset of Crude Oils

“…The asphaltene precipitation onset by titration with n-heptane can be monitored by techniques such as optical microscopy (magnification of 200×) 4,22,23 and near-infrared spectroscopy (NIR). [24][25][26][27][28][29][30] For optical microscopy, aliquots of oil after addition of determined volumes of n-heptane are observed under the microscope until detecting the appearance of asphaltene particles. 4,22,23 In turn, NIR is used to monitor the absorption intensity of the sample during titration with n-heptane: the dilution of the sample leads to a reduction of the absorption intensity, while the appearance of particles causes this intensity to increase.…”

“…The oil is considered more stable the greater the volume of n-heptane necessary to cause the asphaltenes to precipitate. [24][25][26][27][28][29][30] Ascertaining the solubility parameter of a crude oil sample by experimental determination of the asphaltene precipitation onset is unreliable when this onset point is hard to detect. This occurs when visualization of the particles by optical microscopy is difficult and the absorption intensity curve in function of n-heptane volume is poorly defined.…”

Influence of Cardanol Encapsulated on the Properties of Poly(lactic Acid) Microparticles

“…3,4 Due to its chemical similarity with nonylphenol (a synthetic chemical additive with proven action as an asphaltene stabilizer), 5 cardanol has been tested for its ability to stabilize asphaltenes in crude oil, both in its original form and after undergoing step-growth or chain-growth polymerization, demonstrating good performance compared to nonylphenol. 4,[6][7][8] Therefore, the substitution of nonylphenol by cardanol can have both environmental and economic advantages because cardanol is obtained from a renewable source and is cheaper to produce.…”