Calorimetric Probing of <i>n</i>-Alkane−Petroleum Asphaltene Interactions

Mahmoud, Rachid; Gierycz, Paweł; Solimando, Roland; Rogalski, Marek

doi:10.1021/ef050161u

Cited by 45 publications

(40 citation statements)

References 14 publications

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“…This was explained by the partial dissolution of n-alkanes upon interacting with the lateral aliphatic chains of the asphaltenes; the almost solid nature of the partially immobilized alkanes caused the effect of wax nucleation and induced asphaltenes flocculation. 16 Similar results were found by other researchers. 17,18 Orea et al 19 studied asphaltenes from Furrial and Ayacucho crude oils to test retention of alkane compounds on asphaltenes.…”

Section: Introductionsupporting

confidence: 88%

Understanding the Effect of Chemical Structure of Asphaltenes on Wax Crystallization of Crude Oils from Colorado Oil Field

2017

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the structural differences of asphaltenes in Colombian light crude oils from the same field, i.e., the Colorado oilfield, were presented. Colorado crude oil is a light crude with very low content of asphaltenes (<0.3%, w/w) and presents paraffin crystallization problems during its production. In the parafinic deposits, asphaltenes have also been found. In this work, a new methodology is proposed to determine the effects of chemical structure and concentration of asphaltenes on the wax crystallization of the crude oils from the Colorado oilfield. Six crude oils (from different sands) were fractionated in their respective asphaltenes and maltenes. The crystallization properties of crude oils and maltenes were obtained: wax appearance temperature (WAT), pour point, and crystallization enthalpy. Asphaltenes were characterized by nuclear magnetic resonance analysis, mass spectrometry, X-ray diffraction, and Raman spectroscopy, and their main average molecular parameters (AMPs) were calculated. Partial least-squares regression (PLS) analysis was used to understand the influence of asphaltenes chemical structure on the crystallization processes. The proposed characterization−statistical analysis methodology allowed for the understanding of the effect of the average molecular structure of asphaltenes on the crystallization properties of paraffins from the crude oils of the Colorado field. The effect of asphaltenes was analyzed through correlation between the differences in WAT, the differences in pour poin,t and the relative crystallization (C r ) with the AMPs of asphaltenes. The AMPs of the asphaltenes causing the greatest impact on the increase of the crystallization temperature are the pericondensed carbons (C aaa ), ratio of peripheral carbons/aromatic carbons (C p /C ar ), and aromaticity factor ( f a ), and decreases in these properties are attributed to the length of the aliphatic chains (n) and the naphthenic rings (C n ); the concentration of asphaltenes (C oasf ) has little effect. The degree of crystallization is increased by f a and decreased with C aaa , C p /C ar , paraffinic carbons (C s ), and C oasf . The pour point is only increased by f a and decreased withC aaa and C n , and C oasf is negligible.

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Section: Introductionsupporting

confidence: 88%

Understanding the Effect of Chemical Structure of Asphaltenes on Wax Crystallization of Crude Oils from Colorado Oil Field

2017

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“…A greater abundance of aliphatic chains in AsphIri asphaltenes permits a better interaction with the paraffins of the C24-C28 system promoting co-crystallization phenomena, where the asphaltenes are partially integrated to the crystal network and probably acting as nucleation sites, causing a slight increasing of WAT. Moreover, the partial immobilization of the paraffins engaged in the interactions with the asphaltene alkyl chains may promote a "quasicrystallization" phenomenon of the paraffins in the asphaltene network, such interaction results in exothermic effects as has been reported in literature [46,47], which explains the significant increasing of crystallization heat of the model system with AsphIri asphaltenes as observed in Table 4. On the other hand, the most aromatic asphaltenes (AsphPC) with a bigger and more condensed aromatic core and with a smaller amount of aliphatic substituents inhibit in some extent the paraffin-asphaltene interactions so that they cannot be incorporated to the paraffin crystal structure hindering nucleation process and crystal network growth, which results in a WAT decreasing with a lower crystallization enthalpy due to the formation of a disordered solid phase.…”

Section: Dsc Study Of the Effect Of Asphaltenes On Liquid-solid Phasementioning

confidence: 51%

Liquid-Solid Phase Equilibria of Paraffinic Systems by DSC Measurements

Alcázar-Vara¹,

Buenrostro-González²

2013

Applications of Calorimetry in a Wide Context - Differential Scanning Calorimetry, Isothermal Titration Calorimetry and Microca

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“…Yang and Kilpatrick,41 concluded that there is no evidence for any intermolecular interaction between waxes and asphaltenes to suggest synergy in precipitation, so that only one between wax and asphaltene undergoes a phase change and precipitates, while the other one is just a portion of the crude oil occluded in the deposit. In contrast, Mahmoud et al45 observed that mixing of n ‐alkanes with asphaltenes leads to exothermic thermal effects irrespective of the asphaltene being already precipitated or dissolved. The phenomenon is attributed to a partial immobilization of n ‐alkanes in the protecting shell formed by aliphatic lateral chains of asphaltenes and validates the idea that n ‐alkanes contribute to both nucleation of the wax crystals and asphaltene flocculation.…”

Section: Introductionmentioning

confidence: 89%

Internal structure of bitumen/polymer/wax ternary mixtures for warm mix asphalts

Rossi

Filippi

Merusi

et al. 2013

J of Applied Polymer Sci

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Polymer modified asphalts (PMA) and warm mix asphalts (WMA) are technologies widely adopted in the paving industry. The first one is well established, while the second one is relatively new, but rapidly growing since it guarantees economic and environmental advantages. Until now PMA and WMA have been used disjointedly, but it would be useful to combine them to keep the advantages of both. One of the adopted solutions to obtain a warm effect is the addition of waxes to the asphaltic binder. Therefore, a ''warm mix polymer modified asphalt'' may be potentially obtained with a ternary asphalt/polymer/wax system. However, the final warm effect and performances of the binder will depend on the interactions between the three components. A preliminary investigation was done by mixing asphalt, styrene-butadiene-styrene block copolymer and a wax chosen among the following three categories: paraffinic, partially oxidized and maleic anhydride functionalized. The morphological and calorimetric analyses and solubility tests allowed identifying different behaviors depending on the wax type, which may preferentially interact either with the asphalt or with the polymer, thus influencing the whole binder structure. With regard to the ternary mixes, it was found that: (i) the paraffinic wax preferentially resides in the polymer-rich phase, and slightly enhances the asphalt-polymer compatibility; (ii) the partially oxidized wax prefers the asphaltene-rich phase and reduces the compatibility; (iii) it is not clear where the functionalized wax is located, but it has a considerable compatibilizing effect and strongly alters the colloidal equilibrium of the asphalt-polymer blend.

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Calorimetric Probing of n-Alkane−Petroleum Asphaltene Interactions

Cited by 45 publications

References 14 publications

Understanding the Effect of Chemical Structure of Asphaltenes on Wax Crystallization of Crude Oils from Colorado Oil Field

Understanding the Effect of Chemical Structure of Asphaltenes on Wax Crystallization of Crude Oils from Colorado Oil Field

Liquid-Solid Phase Equilibria of Paraffinic Systems by DSC Measurements

Internal structure of bitumen/polymer/wax ternary mixtures for warm mix asphalts

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