Effect of n-Alkanes on Asphaltene Structuring in Petroleum Oils

Abstract

The interactions between asphaltenes and short- to medium-chain n-alkanes were studied using titration microcalorimetry and inverse chromatography. The exothermic heat effects observed upon mixing of asphaltenes and n-alkanes were interpreted in terms of assembling of the two types of compounds into mixed structures. We show that the energy of the interactions between n-alkanes and the asphaltene hydrocarbon chains is close to the energy of the interactions between the asphaltene chains. We propose that the latter interactions are responsible for the formation of the asphaltene aggregates and are the driving force of the aggregate assembly into higher structures.

Crystal network for edible oil organogels: Possibilities and limitations of the fatty acid and fatty alcohol systems

“…However we do note that there is a similar discussion going on about wax crystallization in crude oil (Visintin et al, 2005;Stachowiak et al, 2005;Buenrostro-Gonzalez et al, 2004). Although this latter discussion is more about how to prevent the formation of organogel, it would interesting to combine the different approaches in order to obtain insight in the mechanism of organogel formation.…”

“…Personal care products are to deliver functionality whilst being structured, while the crude oil industry just tries to avoid that the oil gets structured (Visintin, Lapasin, Vignati, Dántona, & Lockhart, 2005;Stachowiak, Viguié, Grolier, & Rogalski, 2005; Buenrostro-Gonzalez, Lira-Galeana, Gil-Villegas, & Wu, 2004). A recent review on oil structuring is presented by Pernetti, van Malssen, Flö ter, and Bot (2007 There are several schemes that can be applied to structure oil, such as the application of polymers (Atta & Arndt, 2005), surfactant systems (Angelico et al, 2005), or low-molecular weight gelators (Ojijo et al, 2004a(Ojijo et al, , 2004bGandolfo et al, 2004;Realdon et al, 2001), in order to replace classical structuring components.…”

Waxes in asphaltenes of crude oils and wax deposits

“…However, the traditional methods used to isolate asphaltenes by adding 40 volumes in excess of low boiling point paraffin hydrocarbons can produce a fraction which is contaminated with a significant amount of waxes (Chouparova and Philp 1998;Thanh et al 1999;Liao et al 2006;Acevedo et al 2009;Coto et al 2011). The presence of paraffin hydrocarbons in asphaltenes can be explained by their coprecipitation as a result of low solubility in low molecular weight n-alkanes (Thanh et al 1999;Coto et al 2011), by interaction between the alkyl lateral chains (C 7 -C 10 ) of asphaltenes with high molecular weight n-alkanes (Garcia and Carbognani 2001;Stachowiak et al 2005;Ganeeva et al 2014), and by their adsorption and/or occlusion inside asphaltene aggregates (Liao et al 2005(Liao et al , 2006Acevedo et al 2009;Gray et al 2011). Now, it is well-known that the asphaltenes exist as three-dimensional aggregates due to the strong intermolecular forces such as hydrogen bonding and p-bonding (Murgich 2002) and even at very low concentration as 50-150 mg/L in a good solvent such as toluene (Mullins et al 2012).…”

Liquid-Solid Phase Equilibria of Paraffinic Systems by DSC Measurements

“…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.…”